U.S. patent application number 12/269591 was filed with the patent office on 2009-03-19 for vehicular drive system.
Invention is credited to Atsushi TABATA, Yutaka Taga.
Application Number | 20090075774 12/269591 |
Document ID | / |
Family ID | 34744044 |
Filed Date | 2009-03-19 |
United States Patent
Application |
20090075774 |
Kind Code |
A1 |
TABATA; Atsushi ; et
al. |
March 19, 2009 |
VEHICULAR DRIVE SYSTEM
Abstract
Vehicular drive system which is small-sized and/or improved in
its fuel economy. A power distributing mechanism 16, which is
provided with a differential-state switching device in the form of
a switching clutch C0 and a switching brake B0, is switchable by
the switching device between a differential state
(continuously-variable shifting state) in which the mechanism is
operable as an electrically controlled continuously variable
transmission, and a fixed-speed-ratio shifting state in which the
mechanism is operable as a transmission having a fixed speed ratio
or ratios. The power distributing mechanism 16 is placed in the
fixed-speed-ratio shifting state during a high-speed running of the
vehicle or a high-speed operation of engine 8, so that the output
of the engine 8 is transmitted to drive wheels 38 primarily through
a mechanical power transmitting path, whereby fuel economy of the
vehicle is improved owing to reduction of a loss of conversion of a
mechanical energy into an electric energy. The mechanism 16 is also
placed in the fixed-speed-ratio shifting state during a high-output
operation of the engine 8, so that the required electric reaction
of first electric motor M1 can be reduced, whereby the required
size of the first electric motor M1, and the required size of the
drive system 10 including the electric motor M1 can be reduced.
Inventors: |
TABATA; Atsushi;
(Okazaki-shi, JP) ; Taga; Yutaka; (Aichi-gun,
JP) |
Correspondence
Address: |
KENYON & KENYON LLP
1500 K STREET N.W., SUITE 700
WASHINGTON
DC
20005
US
|
Family ID: |
34744044 |
Appl. No.: |
12/269591 |
Filed: |
November 12, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11019337 |
Dec 23, 2004 |
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12269591 |
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Current U.S.
Class: |
475/150 |
Current CPC
Class: |
B60W 20/00 20130101;
F16H 2200/0039 20130101; B60K 6/365 20130101; Y02T 10/6226
20130101; Y10S 903/91 20130101; Y10T 477/6934 20150115; B60K 6/485
20130101; Y10S 903/906 20130101; F16H 2200/0056 20130101; F16H
2061/0223 20130101; Y10S 903/903 20130101; F16H 2061/6603 20130101;
F16H 2200/201 20130101; Y10T 477/6217 20150115; B60K 1/02 20130101;
F16H 2200/0008 20130101; Y10T 477/26 20150115; F16H 2200/0034
20130101; F16H 2200/0043 20130101; Y02T 10/40 20130101; Y02T
10/6239 20130101; Y10T 477/23 20150115; F16H 3/728 20130101; Y10T
477/60 20150115; Y02T 10/6286 20130101; B60K 6/547 20130101; B60W
10/02 20130101; B60W 20/30 20130101; Y02T 10/52 20130101; Y10S
903/909 20130101; F16H 2200/0086 20130101; Y02T 10/62 20130101;
B60W 2520/10 20130101; F16H 2200/0047 20130101; B60K 6/445
20130101; Y10T 477/69 20150115; B60W 10/08 20130101; Y02T 10/6221
20130101; B60K 6/48 20130101; B60W 10/06 20130101; F16H 2200/2005
20130101; B60W 10/18 20130101; F16H 2200/006 20130101; Y10S 903/904
20130101; B60W 10/10 20130101; F16H 3/666 20130101; F16H 2200/2007
20130101 |
Class at
Publication: |
475/150 |
International
Class: |
F16H 48/00 20060101
F16H048/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 26, 2003 |
JP |
2003-435967 |
Feb 25, 2004 |
JP |
2004-050530 |
Feb 26, 2004 |
JP |
2004-052211 |
May 26, 2004 |
JP |
2004-156884 |
May 28, 2004 |
JP |
2004-159602 |
Jun 30, 2004 |
JP |
2004-194792 |
Nov 17, 2004 |
JP |
2004-333627 |
Dec 16, 2004 |
JP |
2004-365143 |
Dec 16, 2004 |
JP |
2004-365144 |
Claims
1. A vehicular drive system including a power distributing
mechanism operable to distribute an output of an engine to a first
electric motor and a power transmitting member, and a second
electric motor disposed between the power transmitting member and a
drive wheel of a vehicle, characterized by comprising: a
differential-state switching device operable to place said power
distributing mechanism selectively in a differential state in which
the power distributing mechanism is operable as an electrically
controlled continuously variable transmission, and a
fixed-speed-ratio shifting state in which the power distributing
mechanism is operable as a transmission having a single speed ratio
or a plurality of speed ratios.
2. A vehicular drive system according to claim 1, wherein said
power distributing mechanism include a first element fixed to said
engine, a second element fixed to said first electric motor, and a
third element fixed to said power transmitting member, and said
differential-state switching device is operable to permit said
first, second and third elements to be rotated relative to each
other, for thereby placing the power distributing mechanism in said
differential state, and to connect at least two of said first,
second and third elements to each other or to hold said second
element stationary, for thereby placing the power distributing
mechanism in said fixed-speed-ratio shifting state.
Description
TECHNICAL FIELD
[0001] The present invention relates to a vehicular drive system
arranged to transmit an output of an engine to drive wheels of a
vehicle and including a control device, and more particularly to
techniques for reducing a size of an electric motor or electric
motors, techniques for switching of the drive system between an
electrically established continuously-variable shifting state and a
step-variable shifting state, and shifting control techniques for
suitable controlling the speed ratio of a continuously-variable
shifting portion and the speed ratio of a step-variable shifting
portion.
BACKGROUND ART
[0002] As one example of a vehicular drive system arranged to
transmit an output of an engine to drive wheels of a vehicle, there
is known a drive system including a power distributing mechanism
arranged to distribute the output of the engine to a first electric
motor and an output shaft, and a second electric motor disposed
between the output shaft of the power distributing mechanism and
the drive wheels. Examples of this type of drive system include
hybrid vehicle drive systems disclosed in Patent Documents 1, 6 and
8. In these hybrid vehicle drive systems, the power distributing
mechanism is constituted, for example, by a planetary gear set
which functions as a differential mechanism a differential action
of which permits a major portion of a drive force of the engine to
be mechanically transmitted to the drive wheels, and the rest of
the drive force to be electrically transmitted from the first
electric motor to the second electric motor, through an electric
path therebetween, thereby making it possible to drive the vehicle
with the engine kept in an optimum operating state with an improved
fuel economy. Where a step-variable transmission is provided
between a power transmitting member and the output shaft, a torque
to be transmitted to the power transmitting member is boosted,
making it possible to reduce the size of a drive power source
including the electric motors.
[0003] [Patent Document 1] JP-2003-127681A
[0004] [Patent Document 2] JP-11-198670A
[0005] [Patent Document 3] JP-11-198668A
[0006] [Patent Document 4] JP-11-217025A
[0007] [Patent Document 5] JP-WO 03/016749A1
[0008] [Patent Document 6] JP-2003-130202A
[0009] [Patent Document 7] JP-2003-130203A
[0010] [Patent Document 8] JP-2000-2327A
DISCLOSURE OF INVENTION
Problems Solved by the Invention
[0011] Generally, a continuously variable transmission is known as
a device for improving the fuel economy of a vehicle, while on the
other hand a planetary gear type power transmitting device such as
a step-variable transmission is known as a device having a high
power transmission efficiency. In a conventional vehicular drive
system including a transmission mechanism operable as an
electrically controlled continuously variable transmission as
described above, there is provided an electric path through which
an electric energy is transmitted from the first electric motor to
the second electric motor, that is, through which a portion of the
vehicle drive force is transmitted as an electric energy. Where
this vehicular drive system uses an engine an output of which is
relatively high, the drive system requires the first electric motor
to be large-sized, and further requires the second electric motor
to be large-size since the second electric motor is driven by an
electric energy supplied from the large-sized first electric motor,
whereby the vehicular drive system as a whole is unfavorably
large-sized. Alternatively, the conventional vehicular drive
system, wherein a portion of the output of the engine is once
converted into an electric energy and then transmitted to the drive
wheels, has a risk of deterioration of the fuel economy in some
running condition of the vehicle, for instance, during running of
the vehicle at a relatively high speed. Similar problems are
encountered in a transmission such as a continuously variable
transmission so-called "electric CVT" wherein the speed ratio of
the power distributing mechanism described above is electrically
changed.
[0012] In the above-described vehicular drive system having the
electric path for transmission of the electric energy from the
first electric motor to the second electric motor, a portion of the
vehicle drive force is once converted into the electric energy,
that is, a portion of the output of the engine is once converted
into the electric energy and then transmitted to the drive wheels,
so that the power transmission efficiency of the present vehicular
drive system is lower than that of a gear type power transmission
such as a step-variable transmission. On the other hand, the gear
type power transmission not having an electric path as described
above is known as a device having a relatively high power
transmission efficiency, but the drive system including the gear
type power transmission cannot always be controlled to maximize the
fuel economy of the engine, since the engine speed is kept at a
value determined by the running speed of the vehicle. Thus, there
is not available a power transmitting mechanism which permits a
high fuel economy of the engine. For improving the fuel economy, it
is considered to modify the conventional vehicular drive system
such that the drive system is selectively operable in an
electrically established continuously-variable shifting state, and
in a step-variable shifting state in which the output of the engine
is primarily transmitted to the drive wheels through a mechanical
path, in the absence of the electric path, so as to minimize a loss
of conversion of the engine output into an electric energy. In this
case, the drive system is switchable between the
continuously-variable and step-variable shifting states. However,
it is not easy to assure adequate switching between the
continuously-variable and step-variable shifting states, so as to
enable the vehicle to run with a high fuel economy. In other words,
inadequate switching may cause deterioration of the fuel
economy.
[0013] Also known is a vehicular drive system including an
electrically controlled continuously variable transmission and a
step-variable transmission. This drive system has a large number of
combinations of the speed ratio of the electrically controlled
continuously variable transmission and the speed ratio of the
step-variable transmission. In this respect, the drive system of
this type has a room for improvement in connection with the control
of the speed ratio of the electrically controlled continuously
variable transmission. For example, the continuously variable
transmission has a relatively high power transmission efficiency
during acceleration of the vehicle with an output of the first
electric motor driven in the forward direction and an output of the
engine, but may suffer from a relatively low power transmission
efficiency during steady running of the vehicle at a comparatively
high speed, which requires the output shaft of the continuously
variable transmission to be rotated at a comparatively high speed
and therefore requires the first electric motor to be driven in the
reverse direction.
[0014] The present invention was made in view of the background art
described above. It is accordingly an object of the present
invention to provide a vehicular drive system with a control
device, which is small-sized or improved in its fuel economy. It is
another object of the invention to provide a vehicular drive system
selectively operable in an electrically established
continuously-variable shifting state and a step-variable shifting
state, together with a control device which permits adequate
switching between the continuously-variable and step-variable
shifting states, and a significant improvement in the fuel economy
of the drive system. It is a further object of the present
invention to provide a control device for a vehicular drive system,
which permits adequate control of the speed ratios of the
continuously variable transmission and the step-variable
transmission of the drive system, so as to improve the fuel
economy.
[0015] As a result of extensive studies in an effort to solve the
problems indicated above, the inventors of the present invention
obtained a finding that the first and second electric motors are
not required to be large-sized when operated in a normal output
state while the engine output is comparatively small, but are
required to be large-sized so as to have a large capacity or output
when operated in a relatively large output state such as a maximum
output state while the engine output is relatively large as in a
high-output running of the vehicle, and a finding that the
vehicular drive system can be made compact with the small-sized
first and second electric motors, by controlling the drive system
such that the output of the engine is primarily transmitted to the
drive wheels through a mechanical power transmitting path, when the
output of the engine is relatively large. The inventors further
obtained a finding that by controlling the drive system such that
the output of the engine is primarily transmitted to the drive
wheels through the mechanical power transmitting path, the fuel
economy of the drive system can be further improved with a reduced
amount of loss of conversion of the output of the engine into an
electric energy, in the absence of an electric path through which a
portion of the engine output during a high-speed running of the
vehicle is once converted by the first electric motor into the
electric energy and then transmitted from the second electric motor
to the drive wheels. The present invention was made based on these
findings.
Means for Solving the Problem
[0016] The object indicated above may be achieved according to a
1.sup.st form of the invention, which provide a vehicular drive
system including a power distributing mechanism operable to
distribute an output of an engine to a first electric motor and a
power transmitting member, and a second electric motor disposed
between the power transmitting member and a drive wheel of a
vehicle, characterized by comprising a differential-state switching
device operable to place the power distributing mechanism
selectively in (a) a differential state in which the power
distributing mechanism is operable as an electrically controlled
continuously variable transmission, and (b) a locked state in which
the power distributing mechanism is not operable as the
electrically controlled continuously variable transmission.
ADVANTAGES OF THE INVENTION
[0017] In the present drive system described above, the power
distributing mechanism is controlled by the differential-state
switching device, to be placed selectively in the differential
state in which the power distributing mechanism is operable as an
electrically controlled continuously variable transmission, and the
locked state in which the power distributing mechanism is not
operable as the electrically controlled continuously variable
transmission. Therefore, the present drive system has not only an
advantage of an improvement in the fuel economy owing to a function
of a transmission whose speed ratio is electrically variable, but
also an advantage of high power transmitting efficiency owing to a
function of a gear type transmission capable of mechanically
transmitting a vehicle drive force. Accordingly, when the engine is
in a normal output state with a relatively low or medium output
while the vehicle is running at a relatively low or medium running
speed, the power distributing mechanism is placed in the
differential state, assuring a high degree of fuel economy of the
vehicle. When the vehicle is running at a relatively high speed, on
the other hand, the power distributing mechanism is placed in the
locked state in which the output of the engine is transmitted to
the drive wheel primarily through a mechanical power transmitting
path, so that the fuel economy is improved owing to reduction of a
loss of conversion of a mechanical energy into an electric energy,
which loss would take place when the drive system is operated as
the transmission whose speed ratio is electrically variable. When
the engine is in a high-output state, the power distributing
mechanism is also placed in the locked state. Therefore, the power
distributing mechanism is operated as the transmission whose speed
ratio is electrically variable, only when the vehicle speed is
relatively low or medium or when the engine output is relatively
low or medium, so that the required amount of electric energy
generated by the electric motor that is, the maximum amount of
electric energy that must be transmitted from the electric motor
can be reduced, making it possible to minimize the required sizes
of the electric motor, and the required size of the drive system
including the electric motor.
OTHER FORMS OF THE INVENTION
[0018] The object indicated above may be achieved according to a
2.sup.nd form of this invention according to the 1.sup.st form,
wherein the power distributing mechanism include a first element
fixed to the engine, a second element fixed to the first electric
motor, and a third element fixed to the power transmitting member,
and the differential-state switching device is operable to permit
the first, second and third elements to be rotated relative to each
other, for thereby placing the power distributing mechanism in the
differential state, and to connect at least two of the first,
second and third elements to each other or to hold the second
element stationary, for thereby placing the power distributing
mechanism in the locked state. The present form of the invention
assures a simple arrangement of the power distributing mechanism
that can be selectively switched by the differential-state
switching device between the differential state and the locked
state.
[0019] The object indicated above may also be achieved according to
a 3.sup.rd form of this invention, which provides a vehicular drive
system including a power distributing mechanism operable to
distribute an output of an engine to a first electric motor and a
power transmitting member, and a second electric motor disposed
between the power transmitting member and a drive wheel of a
vehicle, characterized by comprising a differential-state switching
device operable to place the power distributing mechanism
selectively in a differential state in which the power distributing
mechanism is operable as an electrically controlled continuously
variable transmission, and a fixed-speed-ratio shifting state in
which the power distributing mechanism is operable as a
transmission having a single speed ratio or a plurality of speed
ratios.
[0020] In the present drive system described above, the power
distributing mechanism is controlled by the differential-state
switching device, to be placed selectively in the differential
state in which the power distributing mechanism is operable as an
electrically controlled continuously variable transmission, and the
fixed-speed-ratio shifting state in which the power distributing
mechanism is operable as a transmission having a single speed ratio
or a plurality of speed ratios. Therefore, the present drive system
has not only an advantage of an improvement in the fuel economy
owing to a function of a transmission whose speed ratio is
electrically variable, but also an advantage of high power
transmitting efficiency owing to a function of a gear type
transmission capable of mechanically transmitting a vehicle drive
force. Accordingly, when the engine is in a normal output state
with a relatively low or medium output while the vehicle is running
at a relatively low or medium running speed, the power distributing
mechanism is placed in the differential state, assuring a high
degree of fuel economy of the vehicle. When the vehicle is running
at a relatively high speed, on the other hand, the power
distributing mechanism is placed in the fixed-speed-ratio shifting
state in which the output of the engine is transmitted to the drive
wheel primarily through a mechanical power transmitting path, so
that the fuel economy is improved owing to reduction of a loss of
conversion of a mechanical energy into an electric energy, which
loss would take place when the drive system is operated as the
transmission whose speed ratio is electrically variable. When the
engine is in a high-output state, the power distributing mechanism
is also placed in the fixed-speed-ratio shifting state. Therefore,
the power distributing mechanism is operated as the transmission
whose speed ratio is electrically variable, only when the vehicle
speed is relatively low or medium or when the engine output is
relatively low or medium, so that the required amount of electric
energy generated by the electric motor that is, the maximum amount
of electric energy that must be transmitted from the electric motor
can be reduced, making it possible to minimize the required sizes
of the electric motor, and the required size of the drive system
including the electric motor.
[0021] In a 4.sup.th form of the present invention according to the
3.sup.rd form, wherein the power distributing mechanism include a
first element fixed to the engine, a second element fixed to the
first electric motor, and a third element fixed to the power
transmitting member, and the differential-state switching device is
operable to permit the first, second and third elements to be
rotated relative to each other, for thereby placing the power
distributing mechanism in the differential state, and to connect at
least two of the first, second and third elements to each other or
to hold the second element stationary, for thereby placing the
power distributing mechanism in the fixed-speed-ratio shifting
state. The present form of the invention assures a simple
arrangement of the power distributing mechanism that can be
selectively switched by the differential-state switching device
between the differential state and the fixed-speed-ratio shifting
state.
[0022] In a 5.sup.th form of this invention according to the
2.sup.nd form, the power distributing mechanism is a planetary gear
set, and the first element is a carrier of the planetary gear set,
and the second element is a sun gear of the planetary gear set,
while the third element is a ring gear of the planetary gear set,
the differential-state switching device including a clutch operable
to connect selected two of the carrier, sun gear and ring gear to
each other, and/or a brake operable to fix the sun gear to a
stationary member. In the present form of the invention, the
dimension of the power distributing mechanism in its axial
direction can be reduced, and the power distributing mechanism is
simply constituted by one planetary gear set, for example.
[0023] In a 6.sup.th form of this invention according to the
5.sup.th form, the planetary gear set is a planetary gear set of
single-pinion type. In this form of the invention, the dimension of
the power distributing mechanism in its axial direction can be
reduced, and the power distributing mechanism is simply constituted
by one planetary gear set of single-pinion type.
[0024] According to a 7.sup.th form of this invention according to
the 6.sup.th form, the differential-state switching device is
operable to connect the carrier and sun gear of the planetary gear
set of single-pinion type, for enabling the planetary gear set to
operate as a transmission having a speed ratio of 1, or to hold the
sun gear stationary, for enabling the planetary gear set as a
speed-increasing transmission having a speed ratio lower than 1. In
this form of the invention, the power distributing mechanism is
simply constituted by a planetary gear set of single-pinion type,
as a transmission having a single fixed speed ratio or a plurality
of fixed speed ratios.
[0025] In an 8.sup.th form of this invention according to the
5.sup.th form, the planetary gear set is a planetary gear set of
double-pinion type. In this form of the invention, the dimension of
the power distributing mechanism in its axial direction can be
reduced, and the power distributing mechanism is simply constituted
by one planetary gear set of double-pinion type.
[0026] In a 9.sup.th form of this invention according to the
8.sup.th form, the differential-state switching device is operable
to connect the carrier and sun gear of the planetary gear set of
double-pinion type, for enabling the planetary gear set to operate
as a transmission having a speed ratio of 1, or to hold the sun
gear stationary, for enabling the planetary gear set to operate as
a speed-reducing transmission having a speed ratio higher than 1.
In this form of the invention, the power distributing mechanism is
simply constituted by a planetary gear set of double-pinion type,
as a transmission having a single fixed speed ratio or a plurality
of fixed speed ratios.
[0027] In a 10.sup.th form of this invention according to the
1.sup.st form, the drive system further comprises an automatic
transmission disposed between the power transmitting member and the
drive wheel, and a speed ratio of the drive system is determined by
a speed ratio of the automatic transmission. In this form of the
invention, the drive force is available over a wide range of speed
ratio, by utilizing the speed ratio of the automatic
transmission.
[0028] In an 11.sup.th form of this invention according to the
1.sup.st form, the drive system further comprises an automatic
transmission disposed between the power transmitting member and the
drive wheel, and an overall speed ratio of the drive system is
determined by a speed ratio of the power distributing mechanism and
a speed the of the automatic transmission. In this form of the
invention, the drive force is available over a wide range of speed
ratio, by utilizing the speed ratio of the automatic transmission,
so that the efficiency of operation of the power distributing
mechanism in its continuously-variable shifting state can be
improved.
[0029] In a 12.sup.th form of this invention according to the
10.sup.th form, the automatic transmission is a step-variable
automatic transmission. In this form of the invention, a
continuously variable transmission the speed ratio of which is
electrically variable is constituted by the step-variable automatic
transmission and the power distributing mechanism placed in its
differential state, while a step-variable transmission is
constituted by the step-variable automatic transmission and the
power distributing mechanism placed in its locked state or
fixed-speed-ratio shifting state.
[0030] The drive system described above is preferably arranged such
that the second electric motor is fixed to the power transmitting
member. In this case, the required input torque of the automatic
transmission can be made lower than the torque of its output shaft,
making it possible to further reduce the required size of the
second electric motor.
[0031] The drive system described above is preferably arranged such
that the automatic transmission is a speed-reducing transmission
having a speed ration higher than 1. In this case, the required
input torque of the automatic transmission can be made lower than
the torque of its output shaft, when the second electric motor is
fixed to the power transmitting member, for example, making it
possible to further reduce the required size of the second electric
motor.
[0032] According to a 13.sup.th form of this invention, there is
provided a vehicular drive system including a power distributing
mechanism operable to distribute an output of an engine to a first
electric motor and a power transmitting member, a step-variable
automatic transmission disposed between the power transmitting
member and a drive wheel of a vehicle, and a second electric motor
disposed between the power transmitting member and the drive wheel,
characterized in that: (a) the power distributing mechanism
includes a first planetary gear set having three elements
consisting of a sun gear, a carrier and a ring gear rotating speeds
of which are indicated along respective straight lines in a
collinear chart in which the three elements are arranged as a
second element, a first element and a third element, respectively,
in the order of description, in a direction from one of opposite
ends of the collinear chart toward the other end, the first element
being fixed to the engine, the second element being fixed to the
first electric motor, while the third element being fixed to the
power transmitting member, the power distributing mechanism further
including a switching clutch operable to connect the second element
to the first element, and/or a switching brake operable to fix the
second element to a stationary member, the power distributing
mechanism being placed in a differential state by releasing the
switching clutch and/or the switching brake, and in a
fixed-speed-ratio shifting state in which the power distributing
mechanism has a fixed speed ratio, by engaging the switching clutch
and/or the switching brake; and (b) the step-variable automatic
transmission includes a second planetary gear set, a third
planetary gear set and a fourth planetary gear set, and has five
rotary elements each of which is constituted by at least one of sun
gears, carriers and ring gears of the second, third and fourth
planetary gear sets, rotating speeds of the five rotary elements
being indicated along respective straight lines in a collinear
chart in which the five rotary elements are arranged as a fourth
element, a fifth element, a sixth element, a seventh element and an
eighth element, respectively, in the order of description, in a
direction from one of opposite ends of the collinear chart toward
the other end, the fourth element being selectively connected
through a second clutch to the power transmitting member and
selectively fixed through a first brake to the stationary member,
and the fifth element being selectively fixed through a second
brake to the stationary member, while the sixth element being
selectively fixed through a third brake to the stationary member,
the seventh element being fixed to an output rotary member of the
step-variable automatic transmission, the eighth element being
selectively connected through a first clutch to the power
transmitting member, the step-variable automatic transmission
having a plurality of operating positions that are established by
engaging actions of respective combinations of the first clutch,
second clutch, first brake, second brake and third brake.
[0033] According to a 14.sup.th form of this invention, there is
provided a vehicular drive system including a power distributing
mechanism operable to distribute an output of an engine to a first
electric motor and a power transmitting member, a step-variable
automatic transmission disposed between the power transmitting
member and a drive wheel of a vehicle, and a second electric motor
disposed between the power transmitting member and the drive wheel,
characterized in that: (a) the power distributing mechanism
includes a first planetary gear set of single-pinion type having a
first sun gear, a first carrier and a first ring gear, the first
carrier being fixed to the engine, and the first sun gear being
fixed to the first electric motor, while the first ring gear being
fixed to the power transmitting member, the power distributing
mechanism further including a switching clutch operable to connect
the first carrier and the first sun gear to each other, and/or a
switching brake operable to fix the first sun gear to a stationary
member; and (b) the step-variable automatic transmission includes a
second planetary gear set of single-pinion type, a third planetary
gear set of single-pinion type and a fourth planetary gear set of
single-pinion type, the second planetary gear set having a second
sun gear, a second carrier and a second ring gear, and the third
planetary gear set having a third sun gear, a third carrier and a
third ring gear, while the fourth planetary gear set having a
fourth sun gear, a fourth carrier and a fourth ring gear, the
second sun gear and the third sun gear being selectively connected
through a second clutch to the power transmitting member and
selectively fixed through a first brake to the stationary member,
and the second carrier being selectively fixed through a second
brake to the stationary member, while the fourth ring gear being
selectively fixed through a third brake to the stationary member,
and wherein the second ring gear, the third carrier and the fourth
carrier are fixed to an output rotary member of the step-variable
automatic transmission, and the third ring gear and the fourth sun
gear are selectively connected through a first clutch to the power
transmitting member.
[0034] According to a 15.sup.th form of this invention, there is
provided a vehicular drive system including a power distributing
mechanism operable to distribute an output of an engine to a first
electric motor and a power transmitting member, a step-variable
automatic transmission disposed between the power transmitting
member and a drive wheel of a vehicle, and a second electric motor
disposed between the power transmitting member and the drive wheel,
characterized in that: (a) the power distributing mechanism
includes a first planetary gear set having three elements
consisting of a sun gear, a carrier and a ring gear rotating speeds
of which are indicated along respective straight lines in a
collinear chart in which the three elements are arranged as a
second element, a first element and a third element, respectively,
in the order of description, in a direction from one of opposite
ends of the collinear chart toward the other end, the first element
being fixed to the engine, the second element being fixed to the
first electric motor, while the third element being fixed to the
power transmitting member, the power distributing mechanism further
including a switching clutch operable to connect the second element
to the first element, and/or a switching brake operable to fix the
second element to a stationary member, the power distributing
mechanism being placed in a differential state by releasing the
switching clutch and/or the switching brake, and in a
fixed-speed-ratio shifting state in which the power distributing
mechanism has a fixed speed ratio, by engaging the switching clutch
and/or the switching brake; and (b) the step-variable automatic
transmission includes a second planetary gear set and a third
planetary gear set, and has four rotary elements each of which is
constituted by at least one of sun gears, carriers and ring gears
of the second and third planetary gear sets, rotating speeds of the
fourth rotary elements being indicated along respective straight
lines in a collinear chart in which the four rotary elements are
arranged as a fourth element, a fifth element, a sixth element and
a seventh element, respectively, in the order of description, in a
direction from one of opposite ends of the collinear chart toward
the other end, the fourth element being selectively connected
through a second clutch to the power transmitting member and
selectively fixed through a first brake to the stationary member,
and the fifth element being selectively fixed through a second
brake to the stationary member, while the sixth element being fixed
to an output rotary member of the step-variable automatic
transmission, the seventh element being selectively connected
through a first clutch to the power transmitting member, the
step-variable automatic transmission having a plurality of
operating positions that are established by engaging actions of
respective combinations of the first clutch, second clutch, first
brake and second brake.
[0035] According to a 16.sup.th form of this invention, there is
provided a vehicular drive system including a power distributing
mechanism operable to distribute an output of an engine to a first
electric motor and a power transmitting member, a step-variable
automatic transmission disposed between the power transmitting
member and a drive wheel of a vehicle, and a second electric motor
disposed between the power transmitting member and the drive wheel,
characterized in that: (b) the power distributing mechanism
includes a first planetary gear set of single-pinion type having a
first sun gear, a first carrier and a first ring gear, the first
carrier being fixed to the engine, and the first sun gear being
fixed to the first electric motor, while the first ring gear being
fixed to the power transmitting member, the power distributing
mechanism further including a switching clutch operable to connect
the first carrier and the first sun gear to each other, and/or a
switching brake operable to fix the first sun gear to a stationary
member; and (b) the step-variable automatic transmission includes a
second planetary gear set of single-pinion type and a third
planetary gear set of single-pinion type, the second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and the third planetary gear set having a third sun gear, a
third carrier and a third ring gear, the second sun gear and the
third sun gear being selectively connected through a second clutch
to the power transmitting member and selectively fixed through a
first brake to the stationary member, and the third carrier being
selectively fixed through a second brake to the stationary member,
while the second carrier and the third ring gear being fixed to an
output rotary element of the step-variable automatic transmission,
the second ring gear being selectively connected through a first
clutch to the power transmitting member.
[0036] According to a 17.sup.th form of this invention, there is
provided a vehicular drive system including a power distributing
mechanism operable to distribute an output of an engine to a first
electric motor and a power transmitting member, a step-variable
automatic transmission disposed between the power transmitting
member and a drive wheel of a vehicle, and a second electric motor
disposed between the power transmitting member and the drive wheel,
characterized in that: (a) the power distributing mechanism
includes a first planetary gear set having three elements
consisting of a sun gear, a carrier and a ring gear rotating speeds
of which are indicated along respective straight lines in a
collinear chart in which the three elements are arranged as a
second element, a first element and a third element, respectively,
in the order of description, in a direction from one of opposite
ends of the collinear chart toward the other end, the first element
being fixed to the engine, the second element being fixed to the
first electric motor, while the third element being fixed to the
power transmitting member, the power distributing mechanism further
including a switching clutch operable to connect the second element
to the first element, and/or a switching brake operable to fix the
second element to a stationary member, the power distributing
mechanism being placed in a differential state by releasing the
switching clutch and/or the switching brake, and in a
fixed-speed-ratio shifting state in which the power distributing
mechanism has a fixed speed ratio, by engaging the switching clutch
and/or the switching brake; and (b) the step-variable automatic
transmission includes a second planetary gear set and a third
planetary gear set, and has four rotary elements each of which is
constituted by at least one of sun gears, carriers and ring gears
of the second and third planetary gear sets, rotating speeds of the
fourth rotary elements being indicated along respective straight
lines in a collinear chart in which the four rotary elements are
arranged as a fourth element, a fifth element, a sixth element and
a seventh element, respectively, in the order of description, in a
direction from one of opposite ends of the collinear chart toward
the other end, the fourth element being selectively connected
through a second clutch to the power transmitting member and
selectively connected through a fourth brake to the engine, and the
fifth element being selectively connected through a third clutch to
the engine and selectively fixed through a second brake to the
stationary member, while the sixth element being fixed to an output
rotary member of the step-variable automatic transmission, the
seventh element being selectively connected through a first clutch
to the power transmitting member and selectively fixed through a
first brake to the stationary member, the step-variable automatic
transmission having a plurality of operating positions that are
established by engaging actions of respective combinations of the
first clutch, second clutch, third clutch and fourth clutch, first
brake and second brake.
[0037] According to an 18.sup.th form of this invention, there is
provided a vehicular drive system including a power distributing
mechanism operable to distribute an output of an engine to a first
electric motor and a power transmitting member, a step-variable
automatic transmission disposed between the power transmitting
member and a drive wheel of a vehicle, and a second electric motor
disposed between the power transmitting member and the drive wheel,
characterized in that: (a) the power distributing mechanism
includes a first planetary gear set of single-pinion type having a
first sun gear, a first carrier and a first ring gear, the first
carrier being fixed to the engine, and the first sun gear being
fixed to the first electric motor, while the first ring gear being
fixed to the power transmitting member, the power distributing
mechanism further including a switching clutch operable to connect
the first carrier and the first sun gear to each other, and/or a
switching brake operable to fix the first sun gear to a stationary
member; and (b) the step-variable automatic transmission includes a
second planetary gear set of double-pinion type and a third
planetary gear set of single-pinion type, the second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and the third planetary gear set having a third sun gear, a
third carrier and a third ring gear, the third sun gear being
selectively connected through a second clutch to the power
transmitting member and selectively connected through a fourth
clutch to the engine, the second carrier and the third carrier
being selectively connected through a third clutch to the engine
and selectively fixed through a second brake to the stationary
member, while the second ring gear and the third ring gear being
fixed to an output rotary element of the step-variable automatic
transmission, the second sun gear being selectively connected
through a first clutch to the power transmitting member and
selectively fixed through a first brake to the stationary
member.
[0038] According to a 19.sup.th form of this invention, there is
provided a vehicular drive system including a power distributing
mechanism operable to distribute an output of an engine to a first
electric motor and a power transmitting member, a step-variable
automatic transmission disposed between the power transmitting
member and a drive wheel of a vehicle, and a second electric motor
disposed between the power transmitting member and the drive wheel,
characterized in that: (a) the power distributing mechanism
includes a first planetary gear set having three elements
consisting of a sun gear, a carrier and a ring gear rotating speeds
of which are indicated along respective straight lines in a
collinear chart in which the three elements are arranged as a
second element, a third element and a first element, respectively,
in the order of description, in a direction from one of opposite
ends of the collinear chart toward the other end, the first element
being fixed to the engine, the second element being fixed to the
first electric motor, while the third element being fixed to the
power transmitting member, the power distributing mechanism further
including a switching clutch operable to connect the second element
to the first element, and/or a switching brake operable to fix the
second element to a stationary member, the power distributing
mechanism being placed in a differential state by releasing the
switching clutch and/or the switching brake, and in a
fixed-speed-ratio shifting state in which the power distributing
mechanism has a fixed speed ratio, by engaging the switching clutch
and/or the switching brake; and (b) the step-variable automatic
transmission includes a second planetary gear set and a third
planetary gear set, and has four rotary elements each of which is
constituted by at least one of sun gears, carriers and ring gears
of the second and third planetary gear sets, rotating speeds of the
fourth rotary elements being indicated along respective straight
lines in a collinear chart in which the four rotary elements are
arranged as a fourth element, a fifth element, a sixth element and
a seventh element, respectively, in the order of description, in a
direction from one of opposite ends of the collinear chart toward
the other end, the fourth element being selectively connected
through a third clutch to the power transmitting member and
selectively fixed through a first brake to the stationary member,
and the fifth element being selectively connected through a second
clutch to the engine and selectively fixed through a second brake
to the stationary member, while the sixth element being fixed to an
output rotary member of the step-variable automatic transmission,
the seventh element being selectively connected through a first
clutch to the power transmitting member, the step-variable
automatic transmission having a plurality of operating positions
that are established by engaging actions of respective combinations
of the first clutch, second clutch, third clutch, first brake and
second brake.
[0039] According to a 20.sup.th form of this invention, there is
provided a vehicular drive system including a power distributing
mechanism operable to distribute an output of an engine to a first
electric motor and a power transmitting member, a step-variable
automatic transmission disposed between the power transmitting
member and a drive wheel of a vehicle, and a second electric motor
disposed between the power transmitting member and the drive wheel,
characterized in that: (a) the power distributing mechanism
includes a first planetary gear set of double-pinion type having a
first sun gear, a first carrier and a first ring gear, the first
carrier being fixed to the engine, and the first sun gear being
fixed to the first electric motor, while the first ring gear being
fixed to the power transmitting member, the power distributing
mechanism further including a switching clutch operable to connect
the first carrier and the first sun gear to each other, and/or a
switching brake operable to fix the first sun gear to a stationary
member; and (b) the step-variable automatic transmission includes a
second planetary gear set of single-pinion type and a third
planetary gear set of double-pinion type, the second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and the third planetary gear set having a third sun gear, a
third carrier and a third ring gear, the second sun gear being
selectively connected through a third clutch to the power
transmitting member and selectively fixed through a first brake to
the stationary member, the second carrier and the third carrier
being selectively connected through a second clutch to the engine
and selectively fixed through a second brake to the stationary
member, while the second ring gear and the third ring gear being
fixed to an output rotary element of the step-variable automatic
transmission, the third sun gear being selectively connected
through a first clutch to the power transmitting member.
[0040] According to a 21.sup.st form of this invention, there is
provided a vehicular drive system including a power distributing
mechanism operable to distribute an output of an engine to a first
electric motor and a power transmitting member, a step-variable
automatic transmission disposed between the power transmitting
member and a drive wheel of a vehicle, and a second electric motor
disposed between the power transmitting member and the drive wheel,
characterized in that: (a) the power distributing mechanism
includes a first planetary gear set having three elements
consisting of a sun gear, a carrier and a ring gear rotating speeds
of which are indicated along respective straight lines in a
collinear chart in which the three elements are arranged as a
second element, a first element and a third element, respectively,
in the order of description, in a direction from one of opposite
ends of the collinear chart toward the other end, the first element
being fixed to the engine, the second element being fixed to the
first electric motor, while the third element being fixed to the
power transmitting member, the power distributing mechanism further
including a switching clutch operable to connect the second element
to the first element, and/or a switching brake operable to fix the
second element to a stationary member, the power distributing
mechanism being placed in a differential state by releasing the
switching clutch and/or the switching brake, and in a
fixed-speed-ratio shifting state in which the power distributing
mechanism has a fixed speed ratio, by engaging the switching clutch
and/or the switching brake; and (b) the step-variable automatic
transmission includes a second planetary gear set, a third
planetary gear set and a fourth planetary gear set, and has five
rotary elements each of which is constituted by at least one of sun
gears, carriers and ring gears of the second, third and fourth
planetary gear sets, rotating speeds of the five rotary elements
being indicated along respective straight lines in a collinear
chart in which the five rotary elements are arranged as a fourth
element, a fifth element, a sixth element, a seventh element and an
eighth element, respectively, in the order of description, in a
direction from one of opposite ends of the collinear chart toward
the other end, the fourth element being selectively connected
through a second clutch to the power transmitting member and
selectively fixed through a first brake to the stationary member,
and the fifth element being selectively fixed through a second
brake to the stationary member, while the sixth element being
selectively fixed through a third brake to the stationary member,
the seventh element being fixed to an output rotary member of the
step-variable automatic transmission, the eighth element being
fixed to the power transmitting member, the step-variable automatic
transmission having a plurality of operating positions that are
established by engaging actions of respective combinations of the
second clutch, first brake, second brake and third brake.
[0041] According to a 22.sup.nd form of this invention, there is
provided a vehicular drive system including a power distributing
mechanism operable to distribute an output of an engine to a first
electric motor and a power transmitting member, a step-variable
automatic transmission disposed between the power transmitting
member and a drive wheel of a vehicle, and a second electric motor
disposed between the power transmitting member and the drive wheel,
characterized in that: (a) the power distributing mechanism
includes a first planetary gear set of single-pinion type having a
first sun gear, a first carrier and a first ring gear, the first
carrier being fixed to the engine, and the first sun gear being
fixed to the first electric motor, while the first ring gear being
fixed to the power transmitting member, the power distributing
mechanism further including a switching clutch operable to connect
the first carrier and the first sun gear to each other, and/or a
switching brake operable to fix the first sun gear to a stationary
member; and (b) the step-variable automatic transmission includes a
second planetary gear set of single-pinion type, a third planetary
gear set of single-pinion type and a fourth planetary gear set of
single-pinion type, the second planetary gear set having a second
sun gear, a second carrier and a second ring gear, and the third
planetary gear set having a third sun gear, a third carrier and a
third ring gear, while the fourth planetary gear set having a
fourth sun gear, a fourth carrier and a fourth ring gear, the
second sun gear and the third sun gear being selectively connected
through a second clutch to the power transmitting member and
selectively fixed through a first brake to the stationary member,
and the second carrier being selectively fixed through a second
brake to the stationary member, while the fourth ring gear being
selectively fixed through a third brake to the stationary member,
and wherein the second ring gear, the third carrier and the fourth
carrier are fixed to an output rotary member of the step-variable
automatic transmission, and the third ring gear and the fourth sun
gear are fixed to the power transmitting member.
[0042] According to a 23.sup.rd form of this invention, there is
provided a vehicular drive system including a power distributing
mechanism operable to distribute an output of an engine to a first
electric motor and a power transmitting member, a step-variable
automatic transmission disposed between the power transmitting
member and a drive wheel of a vehicle, and a second electric motor
disposed between the power transmitting member and the drive wheel,
characterized in that: (a) the power distributing mechanism
includes a first planetary gear set having three elements
consisting of a sun gear, a carrier and a ring gear rotating speeds
of which are indicated along respective straight lines in a
collinear chart in which the three elements are arranged as a
second element, a first element and a third element, respectively,
in the order of description, in a direction from one of opposite
ends of the collinear chart toward the other end, the first element
being fixed to the engine, the second element being fixed to the
first electric motor, while the third element being fixed to the
power transmitting member, the power distributing mechanism further
including a switching clutch operable to connect the second element
to the first element, and/or a switching brake operable to fix the
second element to a stationary member, the power distributing
mechanism being placed in a differential state by releasing the
switching clutch and/or the switching brake, and in a
fixed-speed-ratio shifting state in which the power distributing
mechanism has a fixed speed ratio, by engaging the switching clutch
and/or the switching brake; and (b) the step-variable automatic
transmission includes a second planetary gear set and a third
planetary gear set, and has four rotary elements each of which is
constituted by at least one of sun gears, carriers and ring gears
of the second and third planetary gear sets, rotating speeds of the
fourth rotary elements being indicated along respective straight
lines in a collinear chart in which the four rotary elements are
arranged as a fourth element, a fifth element, a sixth element and
a seventh element, respectively, in the order of description, in a
direction from one of opposite ends of the collinear chart toward
the other end, the fourth element being selectively connected
through a second clutch to the power transmitting member and
selectively fixed through a first brake to the stationary member,
and the fifth element being selectively fixed through a second
brake to the stationary member, while the sixth element being fixed
to an output rotary member of the step-variable automatic
transmission, the seventh element being fixed to the power
transmitting member, the step-variable automatic transmission
having a plurality of operating positions that are established by
engaging actions of respective combinations of the second clutch,
first brake and second brake.
[0043] According to a 24.sup.th form of this invention, there is
provided a vehicular drive system including a power distributing
mechanism operable to distribute an output of an engine to a first
electric motor and a power transmitting member, a step-variable
automatic transmission disposed between the power transmitting
member and a drive wheel of a vehicle, and a second electric motor
disposed between the power transmitting member and the drive wheel,
characterized in that: (a) the power distributing mechanism
includes a first planetary gear set of single-pinion type having a
first sun gear, a first carrier and a first ring gear, the first
carrier being fixed to the engine, and the first sun gear being
fixed to the first electric motor, while the first ring gear being
fixed to the power transmitting member, the power distributing
mechanism further including a switching clutch operable to connect
the first carrier and the first sun gear to each other, and/or a
switching brake operable to fix the first sun gear to a stationary
member; and (b) the step-variable automatic transmission includes a
second planetary gear set of single-pinion type and a third
planetary gear set of single-pinion type, and the second planetary
gear set having a second sun gear, a second carrier and a second
ring gear, the third planetary gear set having a third sun gear, a
third carrier and a third ring gear, the second sun gear and the
third sun gear being selectively connected through a second clutch
to the power transmitting member and selectively fixed through a
first brake to the stationary member, the third carrier being
selectively fixed through a second brake to the stationary member,
while the second carrier and the third ring gear being fixed to an
output rotary element of the step-variable automatic transmission,
the second ring gear being fixed to the power transmitting
member.
[0044] In a 25.sup.th form of this invention according to the
10.sup.th form, the power distributing mechanism is disposed on a
first axis, and the automatic transmission is disposed on a second
axis parallel to the first axis, the power transmitting member
being constituted by a pair of members which are disposed on the
first and second axes, respectively, the power distributing
mechanism and the automatic transmission being connected to each
other through the power transmitting member, so as to transit a
drive force therebetween. In this form of the invention, the
dimension of the drive system in the axial direction can be made
smaller than that of the drive system wherein the power
distributing mechanism and the automatic transmission are coaxially
disposed on the same axis. Accordingly, the present drive system
can be suitably used on a transversal FF or RR vehicle such that
the first and second axes are parallel to the transverse or width
direction of the vehicle. In this respect, it is noted that the
maximum axial dimension of a drive system for such a transverse FF
or RR vehicle is generally limited by the width dimension of the
vehicle.
[0045] In a 26.sup.th form of this invention according to the
25.sup.th form, the second electric motor is disposed on the first
axis. In this case, the dimension of the second axis of the drive
system in the axial direction can be reduced.
[0046] In a 27.sup.th form of this invention according to the
25.sup.th form, the second electric motor is disposed on the second
axis. In this case, the dimension of the first axis of the drive
system in the axial direction can be reduced.
[0047] In a 28.sup.th form of this invention according to the
25.sup.th form, the power transmitting member is located on one
side of the power distributing mechanism which is remote from the
engine. In other words, the power distributing member is located
between the engine and the power transmitting member. In this case,
the dimension of the first axis of the drive system in the axial
direction can be reduced.
[0048] In a 29.sup.th form of this invention according to the
25.sup.th form, the automatic transmission includes a differential
drive gear as an output rotary member thereof, and this
differential drive gear is located at one end of the automatic
transmission which is remote from the power transmitting member. In
other words, the automatic transmission is located between the
power transmitting member and the differential drive gear. In this
case, the dimension of the second axis of the drive system in the
axial direction can be reduced.
[0049] In a 30.sup.th form of this invention according to the
21.sup.st form, a direction of an output rotary motion of the power
distributing mechanism to be transmitted to the automatic
transmission is reversed with respect to that of an input rotary
motion of the power distributing mechanism, and the drive system
has a rear-drive position established by engaging the third brake.
In this form of the invention, the direction of the rotary motion
of the power transmitting member to be transmitted to the automatic
transmission in the rear-drive position of the drive system is
reversed with respect to that in the forward-drive positions of the
drive system. Accordingly, the automatic transmission is not
required to be provided with coupling devices or gear devices for
reversing the direction of rotation of the output rotary member
with respect to that of the input rotary motion as received by the
automatic transmission, for establishing the rear-drive position
for the rotary motion of the output rotary member in the direction
opposite to that in the forward-drive positions. Thus, the
rear-drive position can be established in the absence of the first
clutch in the automatic transmission, for example. Further, in the
rear-drive position, the speed of the output rotary motion of the
automatic transmission is made lower than that of the input rotary
motion received from the power distributing mechanism the speed
ratio of which is continuously variable in the engaged state of the
third brake. Accordingly, the rear-drive position has a desired
speed ratio, which may be higher than that of the first-gear
position, for example.
[0050] In a 31.sup.st form of this invention according to the
23.sup.rd form, a direction of an output rotary motion of the power
distributing mechanism to be transmitted to the automatic
transmission is reversed with respect to that of an input rotary
motion of the power distributing mechanism, and the drive system
has a rear-drive position established by engaging the second brake.
In this form of the invention, the direction of the rotary motion
of the power transmitting member to be transmitted to the automatic
transmission in the rear-drive position is reversed with respect to
that in the forward-drive positions. Accordingly, the automatic
transmission is not required to be provided with coupling devices
or gear devices for reversing the direction of rotation of the
output rotary member with respect to that of the input rotary
motion as received by the automatic transmission, for establishing
the rear-drive position for the rotary motion of the output rotary
member in the direction opposite to that in the forward-drive
positions. Thus, the rear-drive position can be established in the
absence of the first clutch in the automatic transmission, for
example. Further, in the rear-drive position, the speed of the
output rotary motion of the automatic transmission is made lower
than that of the input rotary motion received from the power
distributing mechanism the speed ratio of which is continuously
variable in the engaged state of the second brake. Accordingly, the
rear-drive position has a desired speed ratio, which may be higher
than that of the first-gear position, for example.
[0051] In a 32.sup.nd form of this invention according to the
21.sup.st form, a direction of an output rotary motion of the power
distributing mechanism to be transmitted to the automatic
transmission is reversed with respect to that of an input rotary
motion of the power distributing mechanism, and the drive system
has a rear-drive position established by engaging the second
clutch. In this form of the invention, the direction of the rotary
motion of the power transmitting member to be transmitted to the
automatic transmission in the rear-drive position is reversed with
respect to that in the forward-drive positions. Accordingly, the
automatic transmission is not required to be provided with coupling
devices or gear devices for reversing the direction of rotation of
the output rotary member with respect to that of the input rotary
motion as received by the automatic transmission, for establishing
the rear-drive position for the rotary motion of the output rotary
member in the direction opposite to that in the forward-drive
positions. Thus, the rear-drive position can be established in the
absence of the first clutch in the automatic transmission, for
example. Further, in the rear-drive position, the speed of the
output rotary motion of the automatic transmission is made equal to
that of the input rotary motion received from the power
distributing mechanism the speed ratio of which is continuously
variable in the engaged state of the second clutch. Accordingly,
the rear-drive position has a desired speed ratio, which may be
higher than that of the first-gear position, for example.
[0052] According to a 33.sup.rd form of this invention, there is
provided a method of controlling a vehicular drive system including
a power distributing mechanism operable to distribute an output of
an engine to a first electric motor and a power transmitting
member, and a second electric motor disposed between the power
transmitting member and a drive wheel of a vehicle, characterized
by comprising (a) placing the power distributing mechanism
selectively, on the basis of a condition of the vehicle, in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission.
[0053] In the present method described above, the power
distributing mechanism is controlled to be placed selectively, on
the basis of the condition of the vehicle, in the differential
state in which the power distributing mechanism is operable as an
electrically controlled continuously variable transmission, and the
locked state in which the power distributing mechanism is not
operable as the electrically controlled continuously variable
transmission. Therefore, the drive system has not only an advantage
of an improvement in the fuel economy owing to a function of a
transmission whose speed ratio is electrically variable, but also
an advantage of high power transmitting efficiency owing to a
function of a gear type transmission capable of mechanically
transmitting a vehicle drive force. Accordingly, when the vehicle
condition as represented by a running speed and an engine torque is
normal, for example, when the engine is in a normal output state
with a relatively low or medium engine output while the vehicle is
running at a relatively low or medium running speed, the power
distributing mechanism is placed in the differential state,
assuring a high degree of fuel economy of the vehicle. When the
vehicle is running at a relatively high speed, on the other hand,
the power distributing mechanism is placed in the locked state in
which the output of the engine is transmitted to the drive wheel
primarily through a mechanical power transmitting path, so that the
fuel economy is improved owing to reduction of a loss of conversion
of a mechanical energy into an electric energy, which loss would
take place when the drive system is operated as the transmission
whose speed ratio is electrically variable. When the engine is in a
high-output state, the power distributing mechanism is also placed
in the locked state. Therefore, the power distributing mechanism is
operated as the transmission whose speed ratio is electrically
variable, only when the vehicle speed is relatively low or medium
or when the engine output is relatively low or medium, so that the
required amount of electric energy generated by the electric motor
that is, the maximum amount of electric energy that must be
transmitted from the electric motor can be reduced, making it
possible to minimize the required sizes of the electric motor, and
the required size of the drive system including the electric
motor.
[0054] According to a 34.sup.th form of this invention, there is
provided a method controlling a vehicular drive system including a
power distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member,
and a second electric motor disposed between the power transmitting
member and a drive wheel of a vehicle, characterized by comprising
(a) placing the power distributing mechanism selectively, on the
basis of a condition of the vehicle, in a differential state in
which the power distributing mechanism is operable as an
electrically controlled continuously variable transmission, and a
fixed-speed-ratio shifting state in which the power distributing
mechanism is operable as a transmission having a single speed ratio
or a plurality of speed ratios.
[0055] In the present method described above, the power
distributing mechanism is controlled to be placed selectively, on
the basis of the condition of the vehicle, in the differential
state in which the power distributing mechanism is operable as an
electrically controlled continuously variable transmission, and the
fixed-speed-ratio shifting state in which the power distributing
mechanism is operable as a transmission having a single speed ratio
or a plurality of speed ratios. Therefore, the drive system has not
only an advantage of an improvement in the fuel economy owing to a
function of a transmission whose speed ratio is electrically
variable, but also an advantage of high power transmitting
efficiency owing to a function of a gear type transmission capable
of mechanically transmitting a vehicle drive force. Accordingly,
when the vehicle condition as represented by a running speed and an
engine torque is normal, for example, when the engine is in a
normal output state with a relatively low or medium engine output
while the vehicle is running at a relatively low or medium running
speed, the power distributing mechanism is placed in the
differential state, assuring a high degree of fuel economy of the
vehicle. When the vehicle is running at a relatively high speed, on
the other hand, the power distributing mechanism is placed in the
locked state in which the output of the engine is transmitted to
the drive wheel primarily through a mechanical power transmitting
path, so that the fuel economy is improved owing to reduction of a
loss of conversion of a mechanical energy into an electric energy,
which loss would take place when the drive system is operated as
the transmission whose speed ratio is electrically variable. When
the engine is in a high-output state, the power distributing
mechanism is also placed in the locked state. Therefore, the power
distributing mechanism is operated as the transmission whose speed
ratio is electrically variable, only when the vehicle speed is
relatively low or medium or when the engine output is relatively
low or medium, so that the required amount of electric energy
generated by the electric motor that is, the maximum amount of
electric energy that must be transmitted from the electric motor
can be reduced, making it possible to minimize the required sizes
of the electric motor, and the required size of the drive system
including the electric motor.
[0056] In a 35.sup.th form of this invention according to the
33.sup.rd or 34.sup.th form, the drive system further includes an
automatic transmission disposed between the power transmitting
member and the drive wheel, and an overall speed ratio of the drive
system is determined by a speed ratio of the power distributing
mechanism and a speed ratio of the automatic transmission, and
wherein the overall speed ratio is controlled by controlling the
speed ratio of the power distributing mechanism and the speed ratio
of the automatic transmission, on the basis of the condition of the
vehicle. In this form of the invention, the vehicle drive force can
be obtained over a wide rage of the speed ratio, by utilizing the
speed ratio of the automatic transmission, so that the efficiency
of the continuously variable shifting control of the power
distributing mechanism can be further improved. In addition, the
vehicle drive force can be adjusted so as to meet the vehicle
condition.
[0057] In a 36.sup.th form of this invention according to the
33.sup.rd form, the condition of the vehicle is represented by a
value relating to a drive force of the vehicle. In this case, the
overall speed ratio of the drive system is controlled by taking
account of the fuel economy, and the vehicle drive force can be
suitably adjusted.
[0058] In a 37.sup.th form of this invention according to the
33.sup.rd form, the condition of the vehicle is represented by a
running speed of the vehicle. In this case, the overall speed ratio
of the drive system is controlled by taking account of the fuel
economy, and the vehicle drive force can be suitably adjusted.
[0059] According to a 38.sup.th form of this invention, there is
provided a vehicular drive system including a power distributing
mechanism operable to distribute an output of an engine to a first
electric motor and a power transmitting member, a step-variable
automatic transmission disposed between the power transmitting
member and a drive wheel of a vehicle, and a second electric motor
disposed between the power transmitting member and the drive wheel,
characterized in that: (a) the power distributing mechanism
includes a first planetary gear set having three elements
consisting of a sun gear, a carrier and a ring gear rotating speeds
of which are indicated along respective straight lines in a
collinear chart in which the three elements are arranged as a
second element, a first element and a third element, respectively,
in the order of description, in a direction from one of opposite
ends of the collinear chart toward the other end, the first element
being fixed to the engine, the second element being fixed to the
first electric motor, while the third element being fixed to the
power transmitting member, the power distributing mechanism further
including a switching clutch operable to connect the second element
to the first element, and/or a switching brake operable to fix the
second element to a stationary member, the power distributing
mechanism being placed in a differential state by releasing the
switching clutch and/or the switching brake, and in a
fixed-speed-ratio shifting state in which the power distributing
mechanism has a fixed speed ratio, by engaging the switching clutch
and/or the switching brake; and (b) a direction of a rotary motion
of the power transmitting member to be transmitted to the automatic
transmission in a rear-drive position of the drive system is
reversed by the power distributing mechanism, with respect to that
in forward-drive positions of the drive system.
[0060] In this form of the invention, the direction of the rotary
motion of the power transmitting member to be transmitted to the
automatic transmission in the rear-drive position of the drive
system is reversed with respect to that in the forward-drive
positions of the drive system. Accordingly, the automatic
transmission is not required to be provided with coupling devices
or gear devices for reversing the direction of rotation of the
output rotary member with respect to that of the input rotary
motion as received by the automatic transmission, for establishing
the rear-drive position for the rotary motion of the output rotary
member in the direction opposite to that in the forward-drive
positions.
[0061] In a 39.sup.th form of this invention according to the
38.sup.th form, the step-variable automatic transmission includes a
planetary gear set having a sun gear, a carrier and a ring gear
which mesh with each other and constitute at least three rotary
elements rotating speeds of which are indicated along respective
straight lines in a collinear chart in which the five rotary
elements are arranged as a fourth element, a fifth element and a
sixth element, respectively, in the order of description, in a
direction from one of opposite ends of the collinear chart toward
the other end, the fourth element being fixed to the power
transmitting member such that a drive force can be transmitted to
the power transmitting member, and the fifth element being fixed to
an output rotary element of the automatic transmission such that
the drive force can be transmitted to the output rotary element,
while the sixth element is selectively fixed through a brake to a
stationary member, and wherein a rear-drive position of the drive
system is established by engaging the brake. In this form of the
invention, the rotary motion of the fourth element, which is one of
the mutually meshing fourth, fifth and sixth elements, is
transmitted as an output of the power distributing mechanism
operating in the continuously-variable shifting state, to the
automatic transmission, namely, as the input rotary motion of the
automatic transmission, and the sixth element is held stationary,
so that the rotating speed of the fifth element is reduced with
respect to the rotating speed of the fourth element, that is, with
respect to the speed of the input rotary motion of the automatic
transmission. Thus, the speed of the output rotary motion of the
automatic transmission is reduced with respect to the speed of the
input rotary motion of the automatic transmission, so that the
speed ratio of the rear-drive position can be set as desired. For
instance, the speed ratio of the rear-drive position may be higher
than that of a first-gear position.
[0062] In a 40.sup.th form of this invention according to the
38.sup.th form, the step-variable automatic transmission includes a
planetary gear set having a sun gear, a carrier and a ring gear
which mesh with each other and constitute at least three rotary
elements, the fourth element being fixed to the power transmitting
member such that a drive force can be transmitted to the power
transmitting member, and the fifth element being fixed to an output
rotary element of the automatic transmission such that the drive
force can be transmitted to the output rotary element, and wherein
the automatic transmission further includes a clutch operable to
rotate the rotary elements as a unit, and a rear-drive position of
the drive system is established by engaging the clutch. In this
form of the invention, the rotary elements of the automatic
transmission are rotated as a unit by engagement of the clutch, so
that the output of the power distributing mechanism is transmitted
to the automatic transmission, namely, as an input rotary motion of
the automatic transmission, such that the speed of the output
rotary motion of the automatic transmission is equal to that of the
input rotary motion. Accordingly, the speed ratio of the rear-drive
position can be set as desired. For instance, the speed ratio of
the rear-drive position may be higher than that of a first-gear
position.
[0063] The object indicated above may also be achieved according to
a 41.sup.st form of this invention, which provides a control device
for a vehicular drive system arranged to transmit an output of an
engine to a drive wheel of a vehicle, characterized by comprising:
(a) a transmission mechanism of switchable type switchable between
a continuously-variable shifting state in which the transmission
mechanism is operable as an electrically controlled continuously
variable transmission, and a step-variable shifting state in which
the transmission mechanism is operable as a step-variable
transmission; and (b) switching control means for placing the
transmission mechanism of switchable type selectively in one of the
continuously-variable shifting state and the step-variable shifting
state, on the basis of a predetermined condition of the
vehicle.
[0064] According to the present control device described above, the
transmission mechanism of switchable type, which is switchable
between the continuously-variable shifting state in which the
transmission mechanism is operable as the electrically controlled
continuously variable transmission and the step-variable shifting
state in which the transmission mechanism is operable as the
step-variable transmission, is switched by the switching control
means, so as to be selectively placed in the continuously-variable
shifting state and the step-variable shifting state, on the basis
of the predetermined condition of the vehicle. Therefore, the
present control device permits the drive system to have not only an
advantage of an improvement in the fuel economy owing to a function
of a transmission whose speed ratio is electrically variable, but
also an advantage of high power transmitting efficiency owing to a
function of a gear type transmission capable of mechanically
transmitting a vehicle drive force. Accordingly, when the vehicle
is in a low- or medium-speed running state, or in a low- or
medium-output running state, for example, the transmission
mechanism of switchable type is placed in the continuously-variable
shifting state, assuring a high degree of fuel economy of the
vehicle. When the vehicle is in a high-speed running state, on the
other hand, the transmission mechanism is placed in the
step-variable shifting state in which the transmission mechanism is
operable as the step-variable transmission and the output of the
engine is transmitted to the drive wheel primarily through a
mechanical power transmitting path, so that the fuel economy is
improved owing to reduction of a loss of conversion of a mechanical
energy into an electric energy, which loss would take place when
the transmission mechanism is operated as the electrically
controlled continuously variable transmission. When the vehicle is
in a high-output running state, the transmission mechanism is also
placed in the step-variable shifting state. Therefore, the
transmission mechanism is operated as the electrically controlled
continuously variable transmission, only when the vehicle is in the
low- or medium-speed running state or low- or medium-output running
state, so that the required amount of electric energy generated by
the electric motor that is, the maximum amount of electric energy
that must be transmitted from the electric motor can be reduced,
making it possible to minimize the required sizes of the electric
motor, and the required size of the drive system including the
electric motor.
[0065] In a 42.sup.nd form of this invention according to the
41.sup.st form, the transmission mechanism of switchable type
includes a power distributing mechanism having a first element
fixed to the engine, a second element fixed to a first electric
motor, and a third element fixed to a power transmitting member,
and the power distributing mechanism includes a differential-state
switching device operable to place the transmission mechanism of
switchable type selectively in the continuously-variable shifting
state and the step-variable shifting state, the switching control
means being operable to control the differential-state switching
device, so as to place the transmission mechanism selectively in
the continuously-variable shifting state and the step-variable
shifting state. In this case, the differential-state switching
device is controlled by the switching control means, for easy
switching of the transmission mechanism of switchable type of the
vehicular drive system between the continuously-variable shifting
state in which the transmission mechanism is operable as the
continuously variable transmission, and the step-variable shifting
state in which the transmission mechanism is operable as the
step-variable transmission.
[0066] In a 43.sup.rd form of this invention according to the
41.sup.st form, the differential-state switching device is operable
not only to place the transmission mechanism of switchable type
selectively in the continuously-variable shifting state and the
step-variable shifting state, and but also to place the
transmission mechanism placed in the step-variable shifting state,
in one of a plurality of operating positions thereof, the switching
control means being operable to control the differential-state
switching device on the basis of the predetermined condition of the
vehicle, to place the transmission mechanism in one of the
plurality of operating positions after the transmission mechanism
is switched from the continuously-variable shifting state to the
step-variable shifting state. In this form of the invention, the
differential-state switching device is controlled by the switching
control means, to switch the transmission mechanism of switchable
type of the vehicular drive system from the continuously-variable
shifting state in which the transmission mechanism is operable as
the continuously variable transmission, to the step-variable
shifting state in which the transmission mechanism is operable as
the step-variable transmission. While the transmission mechanism is
placed in its step-variable shifting state, the differential-state
switching device is further controlled by the switching control
means, to place the transmission mechanism in one of its plurality
of operating positions, on the basis of the predetermined condition
of the vehicle. When the vehicle is in a low- or medium-speed
running state or in a low- or medium-output running state, for
example, the transmission mechanism of switchable type is placed in
the continuously-variable shifting state, assuring a high degree of
fuel economy of the vehicle. When the vehicle is in a high-speed
running state, on the other hand, the transmission mechanism is
placed in the step-variable shifting state in which the
transmission mechanism is operable as the step-variable
transmission suitable for the high-speed running of the vehicle, so
that the output of the engine is transmitted to the drive wheel
primarily through a mechanical power transmitting path, whereby the
fuel economy is improved owing to reduction of a loss of conversion
of a mechanical energy into an electric energy, which loss would
take place when the transmission mechanism is operated as the
electrically controlled continuously variable transmission. When
the vehicle is in a high-output running state, the transmission
mechanism is also placed in the step-variable shifting state.
Therefore, the transmission mechanism is operated as the
electrically controlled continuously variable transmission, only
when the vehicle is in the low- or medium-speed running state or
low- or medium-output running state, so that the required amount of
electric energy generated by the electric motor that is, the
maximum amount of electric energy that must be transmitted from the
electric motor can be reduced, making it possible to minimize the
required sizes of the electric motor, and the required size of the
drive system including the electric motor. Thus, the switching
control means permits a change from the continuously-variable
shifting state to the step-variable shifting state, and controls
the differential-state switching device such that the transmission
mechanism placed in the step-variable shifting state is place in
one of the plurality of operating positions, on the predetermined
condition of the vehicle, assuring an adequate control of the
step-variable shifting of the transmission mechanism depending upon
the specific running condition of the vehicle, such as the
high-speed and high-output running states of the vehicle.
[0067] In a 44.sup.th form of this invention according to the
41.sup.st form, the predetermined condition of the vehicle includes
a predetermined upper limit of a running speed of the vehicle, and
the switching control means is operable to place the transmission
mechanism of switchable type in the step-variable shifting state,
when an actual value of the running speed of the vehicle has
exceeded the predetermined upper limit. In this form of the
invention, when the actual running speed of the vehicle has
exceeded the predetermined upper limit, the output of the engine is
transmitted to the drive wheel primarily through a mechanical power
transmitting path, so that the fuel economy is improved owing to
reduction of a loss of conversion of a mechanical energy into an
electric energy, which loss would take place when the transmission
mechanism is operated as the electrically controlled continuously
variable transmission. The predetermined upper limit of the running
speed is determined for determining whether the vehicle is in a
high-speed running state.
[0068] In a 45.sup.th form of this invention according to the
41.sup.st form, the predetermined condition of the vehicle includes
a predetermined upper limit of a running speed of the vehicle, and
the switching control means is operable to inhibit the transmission
mechanism of switchable type from being placed in the
continuously-variable shifting state, when an actual value of the
running speed of the vehicle has exceeded the predetermined upper
limit. In this form of the invention, when a drive-force-related
value of the vehicle has exceeded the upper limit, the transmission
mechanism is inhibited from being placed in the
continuously-variable shifting state, and the output of the engine
is transmitted to the drive wheel primarily through a mechanical
power transmitting path, so that the fuel economy is improved owing
to reduction of a loss of conversion of a mechanical energy into an
electric energy, which loss would take place when the transmission
mechanism is operated as the electrically controlled continuously
variable transmission.
[0069] In a 46.sup.th form of this invention according to the
41.sup.st form, the predetermined condition of the vehicle includes
a predetermined upper limit of an output of the vehicle, and the
switching control means is operable to place the transmission
mechanism of switchable type in the step-variable shifting state
when a drive-force-related value of the vehicle has exceeded the
upper limit. In this form of the invention, when the
drive-force-related value such as a required vehicle drive force or
an actual value of the vehicle drive force has exceeded the
predetermined upper limit, which is comparatively high, the output
of the engine is transmitted to the drive wheel primarily through a
mechanical power transmitting path, so that the maximum amount of
an electric energy that must be generated when the transmission
mechanism is operated as the electrically controlled continuously
variable transmission can be reduced, making it possible to reduce
the required size of the electric motor, and the overall size of
the vehicular drive system including the electric motor. The
drive-force-related value indicated above may be any parameter
directly or indirectly relating to a drive force of the vehicle,
such as an output torque of the engine, an output torque of a
transmission, a drive torque of the drive wheel, or a torque in any
other portion of the power transmitting path, or an angle of
opening of a throttle valve which represents a required value of
the torque in such portion of the power transmitting path. The
predetermined upper limit of the vehicle output is determined for
determining whether the vehicle is in a high-output running
state.
[0070] In a 47.sup.th form of this invention according to the
41.sup.st form, the predetermined condition of the vehicle includes
a predetermined upper limit of an output of the vehicle, and the
switching control means is operable to inhibit the transmission
mechanism of switchable type from being placed in the
continuously-variable shifting state, when a drive-force-related
value of the vehicle has exceeded the upper limit. In this form of
the invention, when the drive-force-related value such as a
required vehicle drive force or an actual value of the vehicle
drive force has exceeded the predetermined upper limit, which is
comparatively high, the transmission mechanism of switchable type
is inhibited from being placed in the continuously-variable
shifting state, and the output of the engine is transmitted to the
drive wheel primarily through a mechanical power transmitting path,
so that the maximum amount of an electric energy that must be
generated when the transmission mechanism is operated as the
electrically controlled continuously variable transmission can be
reduced, making it possible to reduce the required size of the
electric motor, and the overall size of the vehicular drive system
including the electric motor.
[0071] In a 48.sup.th form of this invention according to the
44.sup.th form, the predetermined condition of the vehicle is
represented by a stored switching boundary line map including an
upper vehicle-speed limit line and an upper output limit line that
respectively represent the upper limit of the running speed and an
upper limit of a drive-force-related value of the vehicle, with
which actual values of the running speed and the
drive-force-related value are compared. The stored switching
boundary line map permits easy determination as to whether the
vehicle is in the high-speed running state or in the high-torque
running state.
[0072] In a 49.sup.th form of this invention according to the
41.sup.st form, the predetermined condition of the vehicle includes
a predetermined diagnosing condition for determining whether
control components operable to place the transmission mechanism of
switchable type in the continuously-variable shifting state have a
deteriorated function, and the switching control means is operable
to place the transmission mechanism in the step-variable shifting
state, when the predetermined diagnosing condition is satisfied. In
this form of the invention, the transmission mechanism of
switchable type is necessarily placed in the step-variable shifting
state if the diagnosing condition is satisfied, even where the
transmission mechanism should be otherwise placed in the
continuously-variable shifting state. Thus, the vehicle can be run
with the transmission mechanism placed in the step-variable
shifting state, even in the event of the functional
deterioration.
[0073] In a 50.sup.th form of this invention according to the
41.sup.st form, the predetermined condition of the vehicle includes
the predetermined diagnosing condition, and the switching control
means is operable to inhibit the transmission mechanism of
switchable type from being placed in the continuously-variable
shifting state, when the predetermined diagnosing condition is
satisfied. In this form of the invention, when the control
components operable to place the transmission mechanism in the
continuously-variable shifting state have a deteriorated function,
the transmission mechanism is inhibited from being placed in the
continuously-variable shifting state, and is necessarily placed in
the step-variable shifting state, so that the vehicle can be run in
the step-variable shifting state, even in the event of the
functional deterioration.
[0074] In a 51.sup.st form of this invention according to the
42.sup.nd form wherein the power distributing mechanism includes
the first element fixed to the engine, the second element fixed to
the first electric motor and the third element fixed to the power
distributing member, the differential-state switching device
includes a coupling device such as a frictional coupling device,
which is operable to connect selected two of the first through
third elements to each other, and/or fix the second element to a
stationary member, and the switching control means places the
transmission mechanism in the continuously-variable shifting state
by releasing the engaging device to permit the first, second and
third elements to be rotatable relative to each other, and places
the transmission mechanism in the step-variable shifting state by
engaging the coupling device to connect at least two of the first,
second and third elements to each other or fix the second element
to the stationary member. In this form of the invention, the power
distributing mechanism can be made simple in construction, and the
transmission mechanism can be easily controlled by the switching
control means, so as to be selectively placed in the
continuously-variable shifting state and the step-variable shifting
state.
[0075] In a 52.sup.nd form of this invention according to the
51.sup.st form, the predetermined condition of the vehicle includes
a predetermined upper limit of a running speed of the vehicle, and
the switching control means is operable to control the coupling
device, so as to fix the second element to the stationary member
when an actual value of the running speed of the vehicle has
exceeded the predetermined upper limit. In this form of the
invention, when the actual running speed of the vehicle has
exceeded the predetermined upper limit, the output of the engine is
transmitted to the drive wheel primarily through a mechanical power
transmitting path, so that the fuel economy is improved owing to
reduction of a loss of conversion of a mechanical energy into an
electric energy, which loss would take place when the transmission
mechanism is operated as the electrically controlled continuously
variable transmission.
[0076] In a 53.sup.rd form of this invention according to the
51.sup.st form, the predetermined condition of the vehicle includes
a predetermined upper limit of an output of the vehicle, and the
switching control means is operable to control the coupling device,
so as to connect at least two of the first, second and third
elements to each other, when the drive-force-related value of the
vehicle has exceeded the upper limit. In this form of the
invention, when the drive-force-related value such as a required
vehicle drive force or an actual value of the vehicle drive force
has exceeded the predetermined upper limit, which is comparatively
high, the at least two of the three elements of the power
distributing mechanism are connected to each other, and the output
of the engine is transmitted to the drive wheel primarily through a
mechanical power transmitting path, so that the maximum amount of
an electric energy that must be generated when the transmission
mechanism is operated as the electrically controlled continuously
variable transmission can be reduced, making it possible to reduce
the required size of the electric motor, and the overall size of
the vehicular drive system including the electric motor.
[0077] In a 54.sup.th form of this invention according to the
51.sup.st form, the power distributing mechanism is a planetary
gear set, and the first element is a carrier of the planetary gear
set, and the second element is a sun gear of the planetary gear
set, while the third element is a ring gear of the planetary gear
set, the differential-state switching device including a clutch
operable to connect selected two of the carrier, sun gear and ring
gear to each other, and/or a brake operable to fix the sun gear to
the stationary member. In this form of the invention, the dimension
of the power distributing mechanism in its axial direction can be
reduced, and the power distributing mechanism is simply constituted
by one planetary gear set.
[0078] In a 55.sup.th form of this invention according to the
54.sup.th form, the planetary gear set is a planetary gear set of
single-pinion type. In this form of the invention, the dimension of
the power distributing mechanism in its axial direction can be
reduced, and the power distributing mechanism is simply constituted
by one planetary gear set of single-pinion type.
[0079] In a 56.sup.th form of this invention according to the
55.sup.th form, the switching control means is operable to control
the coupling device, so as to connect the carrier and sun gear of
the planetary gear set of single-pinion type, for enabling the
planetary gear set to operate as a transmission having a speed
ratio of 1, or to hold the sun gear stationary, for enabling the
planetary gear set as a speed-increasing transmission having a
speed ratio lower than 1. In this form of the invention, the power
distributing mechanism can be easily controlled, as a transmission
which is constituted by a planetary gear set of single-pinion type
and which has a single fixed speed ratio or a plurality of fixed
speed ratios.
[0080] In a 57.sup.th form of this invention according to the
54.sup.th form, the planetary gear set is a planetary gear set of
double-pinion type. In this form of the invention, the dimension of
the power distributing mechanism in its axial direction can be
reduced, and the power distributing mechanism is simply constituted
by one planetary gear set of double-pinion type.
[0081] In a 58.sup.th form of this invention according to the 57
form, the differential-state switching device is operable to
control the coupling device, so as to connect the carrier and sun
gear of the planetary gear set of double-pinion type, for enabling
the planetary gear set to operate as a transmission having a speed
ratio of 1, or to hold the sun gear stationary, for enabling the
planetary gear set to operate as a speed-reducing transmission
having a speed ratio higher than 1. In this form of the invention,
the power distributing mechanism is simply controlled, as a
transmission which is constituted by a planetary gear set of
double-pinion type and which has a single fixed speed ratio or a
plurality of fixed speed ratios.
[0082] In a 59.sup.th form of this invention according to the
42.sup.nd form, the transmission mechanism of switchable type
further comprises an automatic transmission disposed between the
power transmitting member and the drive wheel and connected in
series to the power distributing mechanism, and a speed ratio of
the transmission mechanism of switchable type is determined by a
speed ratio of the automatic transmission. In this form of the
invention, the drive force is available over a wide range of speed
ratio, by utilizing the speed ratio of the automatic
transmission.
[0083] In a 60.sup.th form of this invention according to the
59.sup.th form, an overall speed ratio of the transmission
mechanism of switchable type is determined by a speed ratio of the
power distributing mechanism and a speed ratio of the automatic
transmission. In this form of the invention, the drive force is
available over a wide range of speed ratio, by utilizing the speed
ratio of the automatic transmission, so that the efficiency of
operation of the power distributing mechanism in its
continuously-variable shifting state can be improved. Preferably,
the automatic transmission is a step-variable automatic
transmission. In this preferred form of the transmission mechanism,
a continuously variable transmission is constituted by the
step-variable automatic transmission and the power distributing
mechanism placed in its continuously-variable shifting state, while
a step-variable transmission is constituted by the step-variable
automatic transmission and the power distributing mechanism placed
in its step-variable shifting state.
[0084] In a 61.sup.st form of this invention according to the
59.sup.th form, the automatic transmission is a step-variable
transmission, and the step-variable transmission is shifted
according to a stored shifting boundary line map. In this case, the
shifting operation of the step-variable transmission can be easily
performed.
[0085] In a 62.sup.nd form of this invention according to the
41.sup.st form, the switching control means places the transmission
mechanism in the continuously-variable shifting state when the
vehicle is in a predetermined running state, and does not place the
transmission mechanism in the continuously-variable shifting state
when the vehicle is in the other running state. In this form of the
invention, the transmission mechanism is placed in the electrically
established continuously-variable shifting state, when the vehicle
is in the predetermined running state suitable for running of the
vehicle with the transmission mechanism operating in the
continuously-variable shifting state, so that the fuel economy of
the vehicle is improved.
[0086] Preferably, the transmission mechanism of switchable type is
arranged such that a second electric motor is connected in series
to the power transmitting member. In this case, the required input
torque of the automatic transmission can be made lower than the
torque of its output shaft, making it possible to reduce the
required size of the second electric motor.
[0087] The object indicated above may be achieved according to a
63.sup.rd form of the present invention, which provides a control
device for a vehicular drive system arranged to transmit outputs of
a plurality of drive power sources to a drive wheel of a vehicle,
characterized by comprising: (a) a differential gear device of
switchable type disposed in a power transmitting path between the
plurality of drive power sources and the drive wheel and switchable
between a locked state and a non-locked state; and (b) switching
control means for placing the differential gear device of
switchable type selectively in one of the locked state and the
non-locked state, on the basis of a predetermined condition of the
vehicle. In this form of the invention, the differential gear
device of switchable type is switched by the switching control
means, so as to be selectively placed in the locked state and the
non-locked state, on the basis of the predetermined condition of
the vehicle. Therefore, the present control device permits the
drive system to have not only an advantage of high power
transmitting efficiency owing to running of the vehicle with one of
the drive power sources in the locked state of the differential
gear device, but also an advantage of an improvement in the fuel
economy owing to running of the vehicle with another drive power
source in the non-locked state of the differential gear device.
Thus, the present control device assures a high degree of fuel
economy of the vehicle. When the vehicle is in a high-output
running state, the differential gear device of switchable type is
placed in the locked state. Namely, the differential gear device is
placed in the non-locked state only when the vehicle is in the low-
or medium-speed running state or low- or medium-output running
state. Where an electric motor is used as the drive power source in
the non-locked state, the maximum amount of electric energy that
must be transmitted from the electric motor can be reduced, making
it possible to minimize the required sizes of the electric motor,
and the required size of the drive system including the electric
motor.
[0088] Preferably, the differential gear device of switchable type
includes a first electric motor, a power distributing mechanism
operable to distribute an output of the engine to the first
electric motor and a power transmitting member, and a second
electric motor disposed between the power transmitting member and
the drive wheel. Preferably, the power distributing mechanism
includes a first element fixed to the engine, a second element
fixed to the first electric motor, and a third element fixed to the
second electric motor and the power distributing mechanism. The
power distributing mechanism includes a differential-state
switching device operable to place the differential gear device of
switchable type selectively in the non-locked state in which the
differential gear device is operable as an electrically controlled
differential device and in the locked state in which the
differential gear device is not operable as the electrically
controlled differential device. The switching control means
indicated above is operable to control the differential-state
switching device, so as to place the differential gear device
selectively in the non-locked and locked state. In this case, the
differential-state switching device is controlled by the switching
control means, to permit easy switching of the differential gear
device between the non-locked state in which the differential gear
device is operable as the electrically controlled differential
device, and the locked state in which the differential gear device
is operable as the electrically controlled differential device.
[0089] Preferably, the differential-state switching device is
operable not only to place the differential gear device of
switchable type selectively in the non-locked state and the locked
state, and but also to place the differential gear device placed in
the locked state, in one of a plurality of operating positions
thereof, the switching control means being operable to control the
differential-state switching device on the basis of the
predetermined condition of the vehicle, to place the differential
gear device in one of the plurality of operating positions after
the differential gear device is switched from the non-locked state
to the locked state. In this form of the invention, the
differential-state switching device is controlled by the switching
control means, to switch the differential gear device of switchable
type of the vehicular drive system from the non-locked state in
which the differential gear device is operable as the electrically
controlled differential device, to the locked state. While the
differential gear device is placed in the locked state, the
differential-state switching device is further controlled by the
switching control means, to place the differential gear device in
one of its plurality of operating positions, on the basis of the
predetermined condition of the vehicle. When the vehicle is in a
low- or medium-speed running state or in a low- or medium-output
running state, for example, the differential gear device of
switchable type is placed in the non-locked state, assuring a high
degree of fuel economy of the vehicle. When the vehicle is in a
high-speed running state, on the other hand, the differential gear
device is placed in the locked state, so that the output of the
engine is transmitted to the drive wheel primarily through a
mechanical power transmitting path, whereby the fuel economy is
improved owing to reduction of a loss of conversion of a mechanical
energy into an electric energy, which loss would take place when
the differential gear device is operated as the electrically
controlled differential device. When the vehicle is in a
high-output running state, the differential gear device is also
placed in the locked state. Therefore, the differential gear device
is operated as the electrically controlled differential device,
only when the vehicle is in the low- or medium-speed running state
or low- or medium-output running state, so that the maximum amount
of electric energy that must be transmitted from the electric motor
can be reduced, making it possible to minimize the required sizes
of the electric motor, and the required size of the drive system
including the electric motor. Thus, the switching control means
permits a change from the non-locked state to the locked state, and
controls the differential-state switching device such that the
differential gear device placed in the locked state is placed in
one of the plurality of operating positions, on the predetermined
condition of the vehicle, assuring an adequate control of the
step-variable shifting of the differential gear device depending
upon the specific running condition of the vehicle, such as the
high-speed and high-output running states of the vehicle.
[0090] Preferably, the predetermined condition of the vehicle
includes a predetermined upper limit of a running speed of the
vehicle, and the switching control means is operable to place the
differential gear device of switchable type in the locked state,
when an actual value of the running speed of the vehicle has
exceeded the predetermined upper limit. In this case, when the
actual running speed of the vehicle has exceeded the predetermined
upper limit, the output of the engine is transmitted to the drive
wheel primarily through a mechanical power transmitting path, so
that the fuel economy is improved owing to reduction of a loss of
conversion of a mechanical energy into an electric energy, which
loss would take place when the differential gear device is operated
as the electrically controlled differential device. The
predetermined upper limit of the running speed is determined for
determining whether the vehicle is in a high-speed running
state.
[0091] Preferably, the predetermined condition of the vehicle
includes a predetermined upper limit of a running speed of the
vehicle, and the switching control means is operable to inhibit the
differential gear device of switchable type from being placed in
the non-locked state, when an actual value of the running speed of
the vehicle has exceeded the predetermined upper limit. In this
case, when a drive-force-related value of the vehicle has exceeded
the upper limit, the differential gear device is inhibited from
being placed in the non-locked state, and the output of the engine
is transmitted to the drive wheel primarily through a mechanical
power transmitting path, so that the fuel economy is improved owing
to reduction of a loss of conversion of a mechanical energy into an
electric energy, which loss would take place when the differential
gear device is operated as the electrically controlled differential
device.
[0092] Preferably, the predetermined condition of the vehicle
includes a predetermined upper limit of an output of the vehicle,
and the switching control means is operable to place the
differential gear device of switchable type in the locked state
when a drive-force-related value of the vehicle has exceeded the
upper limit. In this case, when the drive-force-related value such
as a required vehicle drive force or an actual value of the vehicle
drive force has exceeded the predetermined upper limit, which is
comparatively high, the output of the engine is transmitted to the
drive wheel primarily through a mechanical power transmitting path,
so that the maximum amount of an electric energy that must be
generated when the differential gear device is operated as the
electrically controlled differential device can be reduced, making
it possible to reduce the required size of the electric motor, and
the overall size of the vehicular drive system including the
electric motor. The drive-force-related value indicated above may
be any parameter directly or indirectly relating to a drive force
of the vehicle, such as an output torque of the engine, an output
torque of a transmission, a drive torque of the drive wheel, or a
torque in any other portion of the power transmitting path, or an
angle of opening of a throttle valve which represents a required
value of the torque in such portion of the power transmitting path.
The predetermined upper limit of the vehicle output is determined
for determining whether the vehicle is in a high-output running
state.
[0093] Preferably, the predetermined condition of the vehicle
includes a predetermined upper limit of an output of the vehicle,
and the switching control means is operable to inhibit the
differential gear device of switchable type from being placed in
the non-locked state, when a drive-force-related value of the
vehicle has exceeded the upper limit. In this case, when the
drive-force-related value such as a required vehicle drive force or
an actual value of the vehicle drive force has exceeded the
predetermined upper limit, which is comparatively high, the
differential gear device of switchable type is inhibited from being
placed in the non-locked state, and the output of the engine is
transmitted to the drive wheel primarily through a mechanical power
transmitting path, so that the maximum amount of an electric energy
that must be generated when the differential gear device is
operated as the electrically controlled differential device can be
reduced, making it possible to reduce the required size of the
electric motor, and the overall size of the vehicular drive system
including the electric motor.
[0094] Preferably, the predetermined condition of the vehicle is
represented by a stored switching boundary line map including an
upper vehicle-speed limit line and an upper output limit line that
respectively represent the upper limit of the running speed and an
upper limit of a drive-force-related value of the vehicle, with
which actual values of the running speed and the
drive-force-related value are compared. The stored switching
boundary line map permits easy determination as to whether the
vehicle is in the high-speed running state or in the high-torque
running state.
[0095] Preferably, the predetermined condition of the vehicle
includes a predetermined diagnosing condition for determining
whether control components operable to place the differential gear
device of switchable type in the non-locked state have a
deteriorated function, and the switching control means is operable
to place the differential gear device in the locked state, when the
predetermined diagnosing condition is satisfied. In this case, the
differential gear device of switchable type is necessarily placed
in the locked state if the diagnosing condition is satisfied, even
where the differential gear device should be otherwise placed in
the non-locked state. Thus, the vehicle can be run with the
differential gear device placed in the locked state, even in the
event of the functional deterioration.
[0096] Preferably, the predetermined condition of the vehicle
includes the predetermined diagnosing condition, and the switching
control means is operable to inhibit the differential gear device
of switchable type from being placed in the non-locked state, when
the predetermined diagnosing condition is satisfied. In this form
of the invention, when the control components operable to place the
differential gear device in the non-locked state have a
deteriorated function, the differential gear device is inhibited
from being placed in the non-locked state, and is necessarily
placed in the locked state, so that the vehicle can be run in the
step-variable shifting state, even in the event of the functional
deterioration.
[0097] Where the power distributing mechanism includes the first
element fixed to the engine, the second element fixed to the first
electric motor and the third element fixed to the power
distributing member, it is preferable that the differential-state
switching device includes a coupling device such as a frictional
coupling device, which is operable to connect selected two of the
first through third elements to each other, and/or fix the second
element to a stationary member, and that the switching control
means places the differential gear device in the non-locked state
by releasing the engaging device to permit the first, second and
third elements to be rotatable relative to each other, and places
the differential gear device in the locked state by engaging the
coupling device to connect at least two of the first, second and
third elements to each other or fix the second element to the
stationary member. In this case, the power distributing mechanism
can be made simple in construction, and the differential gear
device can be easily controlled by the switching control means, so
as to be selectively placed in the non-locked state and the locked
state.
[0098] Preferably, the predetermined condition of the vehicle
includes a predetermined upper limit of a running speed of the
vehicle, and the switching control means is operable to control the
coupling device, so as to fix the second element to the stationary
member when an actual value of the running speed of the vehicle has
exceeded the predetermined upper limit. In this case, when the
actual running speed of the vehicle has exceeded the predetermined
upper limit, the output of the engine is transmitted to the drive
wheel primarily through a mechanical power transmitting path, so
that the fuel economy is improved owing to reduction of a loss of
conversion of a mechanical energy into an electric energy, which
loss would take place when the differential gear device is operated
as the electrically controlled differential device.
[0099] Preferably, the predetermined condition of the vehicle
includes a predetermined upper limit of an output of the vehicle,
and the switching control means is operable to control the coupling
device, so as to connect at least two of the first, second and
third elements to each other, when the drive-force-related value of
the vehicle has exceeded the upper limit. In this case, when the
drive-force-related value such as a required vehicle drive force or
an actual value of the vehicle drive force has exceeded the
predetermined upper limit, which is comparatively high, the at
least two of the three elements of the power distributing mechanism
are connected to each other, and the output of the engine is
transmitted to the drive wheel primarily through a mechanical power
transmitting path, so that the maximum amount of an electric energy
that must be generated when the differential gear device is
operated as the electrically controlled differential device can be
reduced, making it possible to reduce the required size of the
electric motor, and the overall size of the vehicular drive system
including the electric motor.
[0100] Preferably, the power distributing mechanism is a planetary
gear set, and the first element is a carrier of the planetary gear
set, and the second element is a sun gear of the planetary gear
set, while the third element is a ring gear of the planetary gear
set, and the differential-state switching device includes a clutch
operable to connect selected two of the carrier, sun gear and ring
gear to each other, and/or a brake operable to fix the sun gear to
the stationary member. In this case, the dimension of the power
distributing mechanism in its axial direction can be reduced, and
the power distributing mechanism is simply constituted by one
planetary gear set.
[0101] Preferably, the planetary gear set is a planetary gear set
of single-pinion type. In this case, the dimension of the power
distributing mechanism in its axial direction can be reduced, and
the power distributing mechanism is simply constituted by one
planetary gear set of single-pinion type.
[0102] Preferably, the switching control means is operable to
control the coupling device, so as to connect the carrier and sun
gear of the planetary gear set of single-pinion type, for enabling
the planetary gear set to operate as a transmission having a speed
ratio of 1, or to hold the sun gear stationary, for enabling the
planetary gear set as a speed-increasing transmission having a
speed ratio lower than 1. In this case, the power distributing
mechanism can be easily controlled, as a transmission which is
constituted by a planetary gear set of single-pinion type and which
has a single fixed speed ratio or a plurality of fixed speed
ratios.
[0103] Preferably, the planetary gear set is a planetary gear set
of double-pinion type. In this case, the dimension of the power
distributing mechanism in its axial direction can be reduced, and
the power distributing mechanism is simply constituted by one
planetary gear set of double-pinion type.
[0104] Preferably, the differential-state switching device is
operable to control the coupling device, so as to connect the
carrier and sun gear of the planetary gear set of double-pinion
type, for enabling the planetary gear set to operate as a
transmission having a speed ratio of 1, or to hold the sun gear
stationary, for enabling the planetary gear set to operate as a
speed-reducing transmission having a speed ratio higher than 1. In
this case, the power distributing mechanism is simply controlled,
as a transmission which is constituted by a planetary gear set of
double-pinion type and which has a single fixed speed ratio or a
plurality of fixed speed ratios.
[0105] Preferably, the differential gear device of switchable type
further comprises an automatic transmission disposed between the
power transmitting member and the drive wheel and connected in
series to the power distributing mechanism, and a speed ratio of
the differential gear device of switchable type is determined by a
speed ratio of the automatic transmission. In this case, the drive
force is available over a wide range of speed ratio, by utilizing
the speed ratio of the automatic transmission.
[0106] Preferably, an overall speed ratio of the differential gear
device of switchable type is determined by a speed ratio of the
power distributing mechanism and a speed ratio of the automatic
transmission. In this case, the drive force is available over a
wide range of speed ratio, by utilizing the speed ratio of the
automatic transmission, so that the efficiency of operation of the
power distributing mechanism in its non-locked state can be
improved. Preferably, the automatic transmission is a step-variable
automatic transmission. In this case, a continuously variable
transmission is constituted by the step-variable automatic
transmission and the power distributing mechanism placed in its
non-locked state, while a step-variable transmission is constituted
by the step-variable automatic transmission and the power
distributing mechanism placed in its locked state.
[0107] Preferably, the automatic transmission is a step-variable
transmission, and the step-variable transmission is shifted
according to a stored shifting boundary line map. In this case, the
shifting operation of the step-variable transmission can be easily
performed.
[0108] In a 64.sup.th form of this invention according to the
63.sup.rd form, the switching control means places the differential
gear device in the non-locked state when the vehicle is in a
predetermined running state, and does not place the differential
gear device in the non-locked state when the vehicle is in the
other running state.
[0109] Preferably, the differential device of switchable type
includes a second electric connected in series to the power
transmitting member. In this case, the required input torque of the
automatic transmission can be made lower than the torque of its
output shaft, making it possible to reduce the required size of the
second electric motor.
[0110] The object indicated above may be achieved according to a
64.sup.th form of this invention, which provides a control device
for a vehicular drive system arranged to transmit an output of an
engine to a drive wheel of a vehicle, characterized by comprising:
(a) a transmission mechanism of switchable type switchable between
a continuously-variable shifting state in which the transmission
mechanism is operable as an electrically controlled continuously
variable transmission, and a fixed-speed-ratio shifting state; and
(b) switching control means for placing the transmission mechanism
of switchable type selectively in one of the continuously-variable
shifting state and the fixed-speed-ratio shifting state, on the
basis of a running speed of the vehicle, and a load of the vehicle
or an output torque of the vehicular drive system, and according to
a predetermined relationship.
[0111] The control device described above, which includes the
above-described transmission mechanism of switchable type and the
above-described switching control means, is suitable to effect a
shifting control of the transmission mechanism operable as the
electrically controlled continuously variable transmission.
[0112] The object indicated above may be achieved according to a
66.sup.th form of this invention, which provides a control device
for a vehicular drive system arranged to transmit an output of an
engine to a drive wheel of a vehicle, characterized by comprising:
(a) a transmission mechanism of switchable type switchable between
a continuously-variable shifting state in which the transmission
mechanism is operable as an electrically controlled continuously
variable transmission, and a step-variable shifting state in which
the transmission mechanism is operable as a step-variable
transmission; and (b) switching control means for placing the
transmission mechanism of switchable type selectively in one of the
continuously-variable shifting state and the step-variable shifting
state, on the basis of a running speed of the vehicle, and a load
of the vehicle or an output torque of the vehicular drive system,
and according to a predetermined relationship.
[0113] The control device described above, which includes the
above-described transmission mechanism of switchable type and the
above-described switching control means, is suitable to effect a
shifting control of the transmission mechanism operable as the
electrically controlled continuously variable transmission.
[0114] The object indicated above may be achieved according to a
67.sup.th form of this invention, which provides a control device
for a vehicular drive system arranged to transmit an output of an
engine to a drive wheel of a vehicle, characterized by comprising:
(a) a transmission mechanism of switchable type switchable between
a continuously-variable shifting state in which the transmission
mechanism is operable as an electrically controlled continuously
variable transmission, and a fixed-speed-ratio shifting state; (b)
a control map which defines, with control parameters consisting of
a running speed of the vehicle and a load of the vehicle or an
output torque of the vehicular drive system, a first region in
which the transmission mechanism of switchable type is placed in
the continuously-variable shifting state, and a second region in
which the transmission mechanism is placed in the fixed-speed-ratio
shifting state; and (c) switching control means for placing the
transmission mechanism of switchable type selectively in one of the
continuously-variable shifting state and the fixed-speed-ratio
shifting state, according to the control map.
[0115] The control device described above, which includes the
above-described transmission mechanism of switchable type, the
above-described map for defining the first region and second
region, and the above-described switching control means, is
operable with a simple program for suitably effecting a shifting
control of the transmission mechanism operable as the electrically
controlled continuously variable transmission.
[0116] The object indicated above may be achieved according to a
68.sup.th form of this invention, which provides a vehicular drive
system arranged to transmit an output of an engine to a drive wheel
of a vehicle, characterized by comprising: (a) a transmission
mechanism of switchable type switchable between a
continuously-variable shifting state in which the transmission
mechanism is operable as an electrically controlled continuously
variable transmission, and a step-variable shifting state; (b) a
control map which defines, with control parameters consisting of a
running speed of the vehicle and a load of the vehicle or an output
torque of the vehicular drive system, a first region in which the
transmission mechanism of switchable type is placed in the
continuously-variable shifting state, and a second region in which
the transmission mechanism is placed in the step-variable shifting
state; and (c) switching control means for placing the transmission
mechanism of switchable type selectively in one of the
continuously-variable shifting state and the step-variable shifting
state, according to the control map.
[0117] The control device described above, which includes the
above-described transmission mechanism of switchable type, the
above-described control map for defining the first region and
second region, and the above-described switching control means, is
operable with a simple map for suitably effecting a shifting
control of the transmission mechanism selectively operable as the
electrically controlled continuously variable transmission and the
step-variable transmission.
[0118] The object indicated above may be achieved according to a
69.sup.th form of this invention, which provides a control device
for a vehicular drive system including a continuously-variable
shifting portion which functions as a continuously variable
transmission and which has a differential mechanism operable to
distribute an output of an engine to a first electric motor and a
power transmitting member, and a second electric motor disposed in
a power transmitting path between the power transmitting member and
a drive wheel of a vehicle, the vehicular drive system further
including a step-variable shifting portion which constitutes a part
of the power transmitting path and which functions as a
step-variable automatic transmission, characterized by comprising:
(a) a differential-state switching device provided in the
differential mechanism and operable to place the
continuously-variable shifting portion selectively in a
differential state in which the differential mechanism is operable
as an electrically controlled continuously variable transmission,
and a locked state in which the differential mechanism is in a
non-differential state; (b) a first control map which defines, with
predetermined control parameters, shifting lines for effecting a
shifting control of the step-variable automatic transmission; and
(c) a second control map which defines, with the same control
parameters as used for the first control map, a differential region
in which the differential mechanism is placed in the differential
state by the differential-state switching device, and a
non-differential state in which the differential mechanism is
placed in the non-differential state by the differential-state
switching device.
[0119] The control device described above, which includes the
above-described differential-state switching device, the
above-described first control map and the above-described second
control map, is operable with a simple program for suitably
effecting a shifting control of the transmission mechanism operable
selectively as the electrically controlled continuously variable
transmission and the step-variable transmission.
[0120] The object indicated above may be achieved according to a
70.sup.th form of this invention, which provides a control device
for a vehicular drive system including a differential mechanism
operable to distribute an output of an engine to a first electric
motor and a power transmitting member, and a second electric motor
disposed in a power transmitting path between the power
transmitting member and a drive wheel of a vehicle, characterized
by comprising: (b) a differential-state switching device operable
to place the differential mechanism selectively in a differential
state in which the differential mechanism is operable as an
electrically controlled continuously variable transmission, and a
locked state in which the differential mechanism is in a
non-differential state; (b) a first control map which defines, with
predetermined control parameters, a plurality of regions for
effecting a drive-power-source selection control to select at least
one drive power source to be operated to generate a drive force,
from among the engine, the first electric motor and the second
electric motor; and (c) a second control map which defines, with
the same control parameters used for the first control map, a
differential region in which the differential mechanism is placed
in the differential state by the differential-state switching
device, and a non-differential region in which the differential
mechanism is placed in the non-differential state by the
differential-state switching device.
[0121] The control device described above, which includes the
above-described differential-state switching device, the
above-described first control map and the above-described second
control map, is operable with a simple program for suitably
effecting a shifting control of the transmission mechanism operable
as the electrically controlled continuously variable transmission,
and the drive-power-source selection control.
[0122] The object indicated above may be achieved according to a
71.sup.st form of this invention, which provides a control device
for a vehicular drive system including a differential mechanism
operable to distribute an output of an engine to a first electric
motor and a power transmitting member, and a second electric motor
disposed in a power transmitting path between the power
transmitting member and a drive wheel of a vehicle, characterized
by comprising: (a) a differential-state switching device operable
to place the differential mechanism selectively in a differential
state in which the differential mechanism is operable as an
electrically controlled continuously variable transmission, and a
step-variable shifting state in which the differential mechanism is
operable as a step-variable transmission; (b) a first control map
which defines, with predetermined control parameters, a plurality
of regions for effecting a drive-power-source selection control to
select at least one drive power source to be operated to generate a
drive force, from among the engine, the first electric motor and
the second electric motor; and (c) a second control map which
defines, with the same control parameters used for the first
control map, a differential region in which the differential
mechanism is placed in the differential state by the
differential-state switching device, and a non-differential region
in which the differential mechanism is placed in the
non-differential state by the differential-state switching
device.
[0123] The control device described above, which includes the
above-described transmission mechanism of switchable type, the
above-described first control map and the above-described second
control map, is operable with a simple program for suitably
effecting a shifting control of the transmission mechanism operable
as the electrically controlled continuously variable transmission,
and the drive-power-source selection control.
[0124] In a 72.sup.nd form of this invention, according to any one
of the 69.sup.th through 71.sup.st form, the predetermined control
parameters consist of a running speed of the vehicle, and a load of
the vehicle or an output torque of the vehicular drive system. In
this case, the shifting control of the transmission mechanism
operable as the electrically controlled continuously variable
transmission can be effected with a simple program.
[0125] The object indicated above may be achieved according to a
73.sup.rd form of this invention, which provides a control device
for a vehicular drive system arranged to transmit an output of an
engine to a drive wheel of a vehicle, characterized by comprising:
(a) a transmission mechanism of switchable type switchable between
a continuously-variable shifting state in which the transmission
mechanism is operable as an electrically controlled continuously
variable transmission, and a step-variable shifting state in which
the transmission mechanism is operable as a step-variable
transmission; and (b) switching control means operable to place the
transmission mechanism of switchable type selectively in one of the
continuously-variable shifting state and the step-variable shifting
state in which a fuel consumption ratio of the vehicle is
lower.
[0126] In the control device described above, the transmission
mechanism of switchable type switchable between the electrically
established continuously-variable shifting state in which the
transmission mechanism is operable as the electrically controlled
continuously variable transmission and the step-variable shifting
state in which the transmission mechanism is operable as the
step-variable transmission is controlled by the switching control
means, so as to be placed selectively in one of the
continuously-variable shifting state and the step-variable shifting
states, in which the fuel consumption ratio is lower. Accordingly,
the vehicle can be run with improved fuel economy.
[0127] In a 74.sup.th form of this invention according to the
73.sup.rd form, the fuel consumption ratio is calculated from time
to time, on the basis of a condition of the vehicle. In this case,
values of the fuel consumption ratio in the continuously-variable
shifting state and the step-variable shifting state are calculated
from time to time, and the transmission mechanism of switchable
type is placed in one of those shifting states in which the fuel
economy is higher. Preferably, fuel-consumption-ratio calculating
means is provided to calculate from time to time the fuel
consumption ratio values on the basis of the vehicle condition. In
this case, the fuel consumption ratio values in the
continuously-variable shifting state and in the step-variable
shifting state are calculated from time to time, by the
fuel-consumption-ratio calculating means, so that the transmission
mechanism of switchable type can be placed in one of the
continuously-variable and step-variable shifting states in which
the fuel economy is higher.
[0128] In a 75.sup.th form of this invention according to the
74.sup.th form, the fuel consumption ratio which is calculated from
time to time on the basis of the condition of the vehicle is
calculated on the basis of a fuel consumption ratio of the engine
obtained according to a stored relationship. In this case, the fuel
consumption ratio of the vehicle can be adequately calculated.
[0129] In a 76.sup.th form of this invention according to the
74.sup.th or 75.sup.th form, the fuel consumption ratio which is
calculated from time to time on the basis of the condition of the
vehicle is obtained by taking account of an efficiency of power
transmission from the engine to the drive wheel. In this case, the
fuel consumption ratio can be adequately calculated. Preferably,
power-transmitting-efficiency calculating means is provided to
calculate the efficiency of power transmission from the engine to
the drive wheel. In this case, the fuel consumption ratio of the
vehicle can be adequately calculated by the
power-transmitting-efficiency calculating means, with the
efficiency of power transmission being taken into account.
[0130] In a 77.sup.th form of this invention according to the
76.sup.th form, the efficiency of power transmission changes with a
running resistance of the vehicle. In this case, the fuel
consumption ratio can be adequately calculated.
[0131] In a 78.sup.th form of this invention according to the
76.sup.th or 77.sup.th form, the efficiency of power transmission
changes with a running speed of the vehicle. In this case, the fuel
consumption ratio can be adequately calculated.
[0132] In a 79.sup.th form of this invention according to any one
of the 76.sup.th through 78.sup.th forms, the efficiency of power
transmission changes with a drive-force-related value of the
vehicle. In this case the fuel consumption ratio can be adequately
calculated. The drive-force-related value indicated above is a
parameter directly or indirectly relating to the drive force of the
vehicle, which may be a torque or rotary force at a suitable
portion of a power transmitting path, such as an output torque of
the engine, an output torque of the transmission and a drive torque
of the drive wheel, or may be an angle of opening of a throttle
valve or an amount of operation of an accelerator pedal, which
represents a required value of such a torque or rotary force.
[0133] In an 80.sup.th form of this invention according to the
73.sup.rd form, the transmission mechanism of switchable type is
placed selectively in one of the continuously-variable shifting
state and the step-variable shifting state, on the basis of a
condition of the vehicle, and according to a stored relationship
which defines shifting regions corresponding to the
continuously-variable and step-variable shifting states such that
the transmission mechanism is placed in one of the
continuously-variable and step-variable shifting states in which
the fuel consumption ratio is lower. In this case, the shifting
state of the transmission mechanism of switchable type is easily
selected so as to improve the fuel economy.
[0134] In an 81.sup.st form of this invention according to any one
of the 73.sup.rd through 80.sup.th forms, the switching control
means is operable to place the transmission mechanism of switchable
type in the step-variable shifting state when an actual speed of
the vehicle has exceeded a predetermined upper limit. In this form
of the invention, while the actual vehicle speed is higher than the
upper limit above which the vehicle is in the high-speed running
state, the output of the engine is transmitted to the drive wheel
primarily through the mechanical power transmitting path, so that
the fuel economy of the vehicle is improved owing to reduction of a
loss of conversion of the mechanical energy into the electric
energy, which would take place when the transmission mechanism is
operated as the electrically controlled continuously variable
transmission. The upper limit of the vehicle speed indicated above
is obtained by experimentation, to detect the high-speed running
state of the vehicle in which the transmission mechanism is
switched to the step-variable shifting state, since the fuel
economy in the high-speed running state is higher in the
step-variable shifting state than in the continuously-variable
shifting state. Thus, the transmission mechanism is placed in the
step-variable shifting state, not on the basis of the fuel
consumption ratio value, but on the basis of the actual vehicle
speed as compared with the predetermined upper limit.
[0135] Preferably, the switching control means inhibits the
transmission mechanism of switchable time from being placed in the
continuously-variable shifting state when the actual vehicle speed
has exceeded the predetermined upper limit. In this case, when the
actual vehicle speed has exceeded the upper limit, the transmission
mechanism is inhibited from being placed in the
continuously-variable shifting state, so that the output of the
engine is transmitted to the drive wheel primarily through the
mechanical power transmitting path, whereby the fuel economy of the
vehicle is improved owing to reduction of a loss of conversion of
the mechanical energy into the electric energy, which would take
place when the transmission mechanism is operated as the
electrically controlled continuously variable transmission.
[0136] In an 82.sup.nd form of the invention according to any one
of the 73.sup.rd through 81.sup.st forms, the switching control
means is operable to place the transmission mechanism of switchable
type in the step-variable shifting state when a drive-force-related
value of the vehicle has exceeded a predetermined upper limit. In
this form of the invention, while the drive-force-related value
such as the required or actual drive force of the vehicle is larger
than the predetermined upper limit, the output of the engine is
transmitted to the drive wheel primarily through the mechanical
power transmitting path, so that the maximum amount of electric
energy that must be generated by he electric motor can be reduced,
making it possible to reduce the required sizes of the electric
motor and the drive system including the electric motor. The upper
limit of the drive-force-related value indicated above is
determined to detect the high-output running state of the vehicle
in which the transmission mechanism of switchable time should be
switched to the step-variable shifting state, that is, to detect
the high-output running state of the vehicle in which the
transmission mechanism should not be operated as an electrically
controlled continuously variable transmission and in which the
engine output is higher than a predetermined upper limit determined
based on the nominal output of the electric motor. Thus, the
transmission mechanism is placed in the step-variable shifting
state, not on the basis of the fuel consumption ratio, but on the
basis of the actual drive-force-related value as compared with the
predetermined upper limit.
[0137] Preferably, the switching control means inhibits the
transmission mechanism of switchable time from being placed in the
continuously-variable shifting state when the actual
drive-force-related value of the vehicle has exceeded the
predetermined upper limit. In this case, when the actual
drive-force-related value such as the required or actual drive
force of the vehicle has exceeded the upper limit, the transmission
mechanism is inhibited from being placed in the
continuously-variable shifting state, so that the output of the
engine is transmitted to the drive wheel primarily through the
mechanical power transmitting path, whereby the maximum amount of
electric energy that must be generated by he electric motor can be
reduced, making it possible to reduce the required sizes of the
electric motor and the drive system including the electric
motor.
[0138] In an 83ard form of this invention according to any one of
the 73.sup.rd through 82.sup.nd form, the switching control means
is operable to place the transmission mechanism of switchable type
in the step-variable shifting state when it is determined that a
predetermined diagnosing condition indicative of functional
deterioration of control components that are operable to place the
transmission mechanism in the above-indicated electrically
established continuously-variable shifting state is satisfied. In
this case, the vehicle can be run with the transmission mechanism
of switchable type operating in the step-variable shifting state,
even when the transmission mechanism cannot be normally operated in
the continuously-variable shifting state.
[0139] Preferably, the switching control means inhibits the
transmission mechanism of switchable time from being placed in the
continuously-variable shifting state when the predetermined
diagnosing condition indicative of the functional deterioration of
the control components operable to place the transmission mechanism
in the electrically established continuously-variable shifting
state is satisfied. In this case, the vehicle can be run with the
transmission mechanism of switchable type operating in the
step-variable shifting state, even when the transmission mechanism
cannot be normally operated in the continuously-variable shifting
state.
[0140] In an 84.sup.th form of this invention according to any one
of the 73.sup.rd through 83.sup.rd forms, 84. the transmission
mechanism of switchable type includes a first electric motor, a
power distributing mechanism operable to distribute the output of
the engine to the first electric motor and a power transmitting
member, and a second electric motor disposed between the power
transmitting member and the drive wheel. Preferably, the power
distributing mechanism has a first element fixed to the engine, a
second element fixed to the first electric motor, and a third
element fixed to the second electric motor and the power
transmitting member. This power distributing mechanism includes a
differential-state switching device operable to place the
transmission mechanism selectively in one of the
continuously-variable shifting state and the step-variable shifting
states, and the switching control means controls the
differential-state switching device to place the transmission
mechanism selectively in one of the continuously-variable shifting
state and the step-variable shifting state. In this form of the
invention, the differential-state switching device is controlled by
the switching control means, so that the transmission mechanism of
switchable type of the drive system can be easily switched between
the continuously-variable shifting state in which the transmission
mechanism is operable as the continuously variable transmission and
the step-variable shifting state in which the transmission
mechanism is operable as the step-variable transmission.
[0141] In a 85.sup.th form of this invention according to the
84.sup.th form, the power distributing mechanism has the first
element fixed to the engine, the second element fixed to the first
electric motor and the third element fixed to the power
transmitting member, and the differential-state switching device
includes a frictional coupling device operable to connect selected
two of the first, second and third elements to each other, and/or
fix the second element to a stationary member. In this case, the
switching control means is operable to release the coupling device
to permit the first, second and third elements to be rotated
relative to each other, for thereby placing the transmission
mechanism in the continuously-variable shifting state, and to
engage the coupling device to connect at least two of the first,
second and third elements to each other or fix the second element
to the stationary member, for thereby placing the transmission
mechanism in the step-variable shifting state. In this form of the
invention, the power distributing mechanism is simple in
construction, and the transmission mechanism can be easily switched
by the switching control means, between the continuously-variable
shifting state and the step-variable shifting state.
[0142] In an 86.sup.th form of this invention according to the
85.sup.th form, the power distributing mechanism is a planetary
gear set, and the first element is a carrier of the planetary gear
set, and the second element is a sun gear of the planetary gear
set, while the third element is a ring gear of the planetary gear
set. In this case, the differential-state switching device includes
a clutch operable to connect selected two of the carrier, sun gear
and ring gear to each other, and/or a brake operable to fix the sun
gear to the stationary member. In this form of the invention, the
required dimension of the power distributing mechanism in its axial
direction can be reduced, and the power distributing mechanism is
simply constituted by one planetary gear set.
[0143] In an 87.sup.th form of this invention according to the
86.sup.th form the planetary gear set is a planetary gear set of
single-pinion type. In this case, the required dimension of the
power distributing mechanism in its axial direction can be reduced,
and the power distributing mechanism is simply constituted by one
planetary gear set of single pinion type.
[0144] In an 88.sup.th form of this invention according to the
87.sup.th form, the switching control device is operable to control
the coupling device, so as to connect the carrier and the sun gear
of the planetary gear set of single-pinion type, for enabling the
planetary gear set to operate as a transmission having a speed
ratio of 1, or to hold the sun ear stationary, for enabling the
planetary gear set as a speed-increasing transmission having a
speed ratio lower than 1. In this form of the invention, the power
distributing mechanism can be easily controlled by the switching
control means, as a transmission which is constituted by one
planetary gear set of single-pinion type and which has a single
fixed speed ratio or a plurality of fixed speed ratios.
[0145] In an 89.sup.th form of this invention according to the
84.sup.th form, the transmission mechanism of switchable type
further includes an automatic transmission disposed in series
between the power transmitting member and the drive wheel, and a
speed ration of the transmission mechanism of switchable type is
determined by a speed ratio of the automatic transmission. In this
form of the invention, the drive force is available over a wide
range of speed ratio, by utilizing the speed ratio of the automatic
transmission.
[0146] In a 90.sup.th form of this invention according to the
89.sup.th form, an overall speed ratio of the transmission
mechanism of switchable type is determined by a speed ratio of the
power distributing mechanism and the speed ratio of the automatic
transmission. In this form of the invention, the drive force is
available over a wide range of speed ratio, by utilizing the speed
ratio of the automatic transmission, so that the efficiency of
operation of the power distributing mechanism in its
continuously-variable shifting state can be improved. Preferably,
the automatic transmission is a step-variable automatic
transmission. In this case, a continuously variable transmission is
constituted by the step-variable automatic transmission and the
power distributing mechanism placed in the continuously-variable
shifting state, while a step-variable transmission is constituted
by the step-variable automatic transmission and the power
distributing mechanism placed in the step-variable shifting state
and the step-variable automatic transmission.
[0147] In a 91.sup.st form of this invention according to the
89.sup.th form, the automatic transmission is a step-variable
automatic transmission, which is shifted according to a stored
shifting control map. In this form of the invention, a shifting
action of the step-variable automatic transmission can be easily
controlled.
[0148] Preferably, the transmission mechanism of switchable type is
arranged such that the second electric motor is directly connected
to the power transmitting member. In this case, the required input
torque of the automatic transmission can be made lower than the
torque of its output shaft, making it possible to reduce the
required size of the second electric motor.
[0149] According to a 92.sup.nd form of this invention, there is
provided a control device for a vehicular drive system including
(a) a continuously-variable shifting portion operable in an
electrically established continuously-variable shifting state, and
(b) a step-variable shifting portion operable as a step-variable
shifting state, the continuously-variable shifting portion
including a differential gear device having three elements
consisting of a first element fixed to a first electric motor, a
second element fixed to an engine and a third element fixed to an
output shaft, the continuously-variable shifting portion further
including a second electric motor operatively connected to a power
transmitting path between the output shaft and a drive wheel of a
vehicle, the step-variable shifting portion being disposed in the
power transmitting path, characterized by comprising (c)
speed-ratio control means operable in the continuously-variable
shifting state of the continuously-variable shifting portion, for
controlling a speed ratio of the step-variable shifting portion and
a speed ratio of the continuously-variable shifting portion, so as
to maximize a fuel economy of the vehicle.
[0150] In the control device according to the 92.sup.nd form of
this invention, the speed ratio of the step-variable shifting
portion and the speed ratio of the continuously-variable shifting
portion are controlled by the speed-ratio control means, so as to
maximize the fuel economy of the vehicle, in the
continuously-variable shifting state of the continuously-variable
shifting portion, so that the fuel economy is improved in the
present form of the invention, as compared with that in the case
where those speed ratios are controlled independently of each
other. For instance, the speed-ratio control means controls the
speed ratio of the step-variable shifting portion so as to prevent
reverse rotation of the first electric motor of the
continuously-variable shifting portion, even in a steady-state
running state of the vehicle at a comparatively high speed.
Accordingly, the fuel economy of the vehicle as a whole can be
maximized.
[0151] According to a 93.sup.rd form of this invention, there is
provided a control device for a vehicular drive system including
(a) a continuously-variable shifting portion operable in an
electrically established continuously-variable shifting state, and
(b) a step-variable shifting portion operable in a step-variable
shifting state, the continuously-variable shifting portion
including a differential gear device having three elements
consisting of a first element fixed to a first electric motor, a
second element fixed to an engine and a third element fixed to an
output shaft, the continuously-variable shifting portion further
including a second electric motor operatively connected to a power
transmitting path between the output shaft and a drive wheel of a
vehicle, the step-variable shifting portion being disposed in the
power transmitting path, characterized by comprising (c)
speed-ratio control means operable in the continuously-variable
shifting state of the continuously-variable shifting portion, for
controlling a speed ratio of the continuously-variable shifting
portion, depending upon a speed ratio of the step-variable shifting
portion.
[0152] In the control device according to the 93.sup.rd form of
this invention, the speed ratio of the continuously-variable
shifting portion is controlled by the speed-ratio control means,
depending upon the speed ratio of the step-variable shifting
portion, in the continuously-variable shifting state of the
continuously-variable shifting portion. Accordingly, the speed
ratios of the step-variable shifting portion and the
continuously-variable shifting portion are controlled to improve
the power transmitting efficiency of the vehicle as a whole.
[0153] In a 94.sup.th form of this invention according to the
92.sup.nd or 93.sup.rd form, the speed-ratio control means is
operable to control the speed ratio of the step-variable shifting
portion and the speed ratio of the continuously-variable shifting
portion, on the basis of an efficiency of the first electric motor
of the continuously-variable shifting portion and an efficiency of
the second electric motor of the continuously-variable shifting
portion.
[0154] In the control device according to the 94.sup.th form of the
invention according to the 92.sup.nd or 93.sup.rd form, the
speed-ratio control means controls the speed ratio of the
step-variable shifting portion and the speed ratio of the
continuously-variable shifting portion, on the basis of the
efficiency of the first electric motor of the continuously-variable
shifting portion and the efficiency of the second electric motor of
the continuously-variable shifting portion. Accordingly, the speed
ratio of the step-variable shifting portion and the speed ratio of
the continuously-variable shifting portion are controlled by taking
account of the efficiency values of the first and second electric
motors, so that the power transmitting efficiency is further
improved.
[0155] In a 95.sup.th form of this invention according to the
92.sup.nd or 93.sup.rd form, the speed-ratio control means is
operable to change a rotating speed of the output shaft of the
continuously-variable shifting portion, by adjusting the speed
ratio of the step-variable shifting portion.
[0156] In the control device according to the 95.sup.th form, the
speed-ratio control means changes the rotating speed of the output
shaft of the continuously-variable shifting portion by adjusting
the speed ratio of the step-variable shifting portion. Accordingly,
the power transmitting efficiency and fuel economy of the vehicle
as a whole can be improved.
[0157] In a 96.sup.th form of this invention, the control device
further comprises a switching device operable to switch the
continuously-variable shifting portion between the
continuously-variable shifting portion in which the speed ratio is
continuously variable, and the step-variable shifting portion in
which the speed ratio is held constant, and
continuously-variable-shifting-run determining means operable for
determining that the continuously-variable shifting portion has
been switched by the switching device to the continuously-variable
shifting state. In this form of the invention, the speed-ratio
control means is operable, upon determination by the
continuously-variable-shifting run determining means that the
continuously-variable shifting portion has been switched by the
switching device to the continuously-variable shifting state, to
control the speed ratio of the step-variable shifting portion and
the speed ratio of the continuously-variable shifting portion, so
as to maximize the fuel economy of the vehicle.
[0158] In the control device of the 96.sup.th form of the invention
according to the 92.sup.nd or 93.sup.rd form, the control device
comprises the switching device to switch the continuously-variable
shifting portion between the continuously-variable shifting portion
in which the speed ratio is continuously variable, and the
step-variable shifting portion in which the speed ratio is held
constant, and the continuously-variable-shifting-run determining
means for determining that the continuously-variable shifting
portion has been switched by the switching device to the
continuously-variable shifting state. Upon determination by the
continuously-variable-shifting-run determining means that the
continuously-variable shifting portion has been switched to the
continuously-variable shifting state, the speed ratio of the
step-variable shifting portion and the speed ratio of the
continuously-variable shifting portion are controlled so as to
maximize the fuel economy of the vehicle. Accordingly, the power
transmitting efficiency and fuel economy of the vehicle as a whole
can be improved.
[0159] Preferably, the control device according to any one of the
92.sup.nd through 96.sup.th forms of this invention comprises
engine-fuel-economy map memory means for storing an
engine-fuel-economy map, and the speed-ratio control means includes
target-engine-speed calculating means for determining a target
speed of the engine on the basis of an actual value of an operating
angle of an accelerator pedal and according to the
engine-fuel-economy map, and two-speed-ratios determining means for
determining the speed ratio of the step-variable shifting portion
and the speed ratio of the continuously-variable shifting portion
which give the determined target speed of the engine, on the basis
of an actual value of a running speed of the vehicle.
[0160] Preferably, the target-engine-speed calculating means is
arranged to select one of iso-horsepower curves which corresponds
to an output of the engine satisfying a vehicle drive force
required by an operator of the vehicle, on the basis of the actual
value of the operating angle Acc of the accelerator pedal and
according to the engine-fuel-economy map, and determine, as the
target speed of the engine, a speed of the engine corresponding to
a point of intersection between the selected iso-horsepower curve
and a highest-fuel-economy curve.
[0161] Preferably, the two-speed-ratios determining means is
arranged to an overall speed ratio of a transmission mechanism
which gives the target speed of the engine, on the basis of the
target speed of the engine and the actual value of the running
speed of the vehicle, and determine the speed ratio of the
step-variable shifting portion and the speed ratio of the
continuously-variable shifting portion which give the determined
overall speed ratio of the transmission mechanism, such that a
power transmitting efficiency of the transmission mechanism as a
whole is maximized.
[0162] Preferably, the two-speed-ratios determining means is
arranged to calculate a fuel consumption amount of the vehicle for
each of a plurality of candidate values of the speed ratio of the
step-variable shifting portion which give a speed of the engine
higher than the target speed of the engine. The candidate values
are set on the basis of the actual value of the running speed V of
the vehicle and according to a relationship between the engine
speed and the vehicle running speed. The two-speed-ratios
determining means calculates the fuel consumption amount on the
basis of the overall speed ratio which gives the target speed
N.sub.EM of the engine, and the candidate values of the speed ratio
of the step-variable shifting portion, and according to a stored
equation for calculating the fuel consumption amount. The
two-speed-ratios determining means determines, as the speed ratio
of the step-variable shifting portion, one of the candidate values
which corresponds to a smallest one of the calculated fuel
consumption amounts, and determine the speed ratio of the
continuously-variable shifting portion on the basis of the
determined speed ratio of the step-variable shifting portion, and
the overall speed ratio which gives the target speed of the
engine.
[0163] Preferably, the equation for calculating the fuel
consumption amount is formulated to calculate the fuel consumption
amount of the vehicle on the basis of the efficiency of the first
electric motor and the efficiency of the second electric motor.
[0164] Preferably, a planetary gear type step-variable transmission
or a permanent meshing type parallel-two-axes step-variable
transmission is disposed between the output shaft and the drive
wheel. For example, the planetary gear type step-variable
transmission is constituted by a plurality of planetary gear sets,
and the parallel-two-axes step-variable transmission includes a
plurality of gear pairs which have respective different gear ratios
and which are mounted on parallel two shafts such that each of the
gear pairs is selectively placed by a synchronous coupling device
in a power transmitting state.
[0165] Preferably, the differential gear device is operable as an
electrically controlled continuously variable transmission the
speed ratio of which is a ratio of the rotating speed of an input
shaft and the rotating speed of an output shaft and which is
continuously variable by electrically controlling the speed of the
first electric motor fixed to the first element.
[0166] Preferably, a switching device is provided for switching the
step-variable shifting portion having the differential gear device,
between a differential state and a locked state. This switching
device includes a clutch which is disposed between the first and
second elements of the differential gear device and which is
engaged to rotate the third element of the differential gear
device.
[0167] Preferably, the differential gear device is constituted by a
planetary gear set including a sun gear, a ring gear, and a carrier
which rotatably supports a planetary gear or gears meshing with the
sun gear and the ring gear. However, the differential gear device
may be constituted by a pair of bevel gears connected to the input
and output shafts, and a rotary element which rotatably supports a
pinion or pinions meshing with the pair of bevel gears.
[0168] Preferably, the step-variable shifting portion is a
planetary gear type step-variable transmission, or a continuously
variable transmission the speed ratio of which is variable in
steps.
[0169] Preferably, the switching device arranged to switch the
differential gear device between the differential and locked states
is a hydraulically operated frictional coupling device, or a
coupling device of a magnetic-powder type, an electromagnetic type
or a mechanical type, such as a powder (magnetic powder) clutch, an
electromagnetic clutch and a meshing type dog clutch, which is
arranged to connect selected ones of the elements of the
differential gear device to each other or a selected one of the
elements to a stationary element.
[0170] Preferably, the second electric motor is operatively
connected to a portion of the power transmitting path between the
output shaft of the differential gear device and the drive wheel.
For example, the second electric motor is connected to a rotary
member such as the output shaft of the differential gear device, a
rotary member of an automatic transmission provided in the power
transmitting path, or an output shaft of this automatic
transmission.
[0171] According to a 97.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a first planetary gear device having as three
elements a sun gear, a carrier and a ring gear, the three elements
consisting of a first element, a second element and a third element
which are arranged in the order of the second element, the first
element and the third elements in a direction from one of opposite
ends of a collinear chart toward the other end, the collinear chart
having straight lines indicating rotating speeds of the three
elements, the first element being fixed to the engine, the second
element being fixed to the first electric motor, and the third
element being fixed to the power transmitting member, the power
distributing mechanism further including a differential-state
switching device operable to place the power distributing mechanism
selectively in a differential state in which the power distributing
mechanism is operable as an electrically controlled continuously
variable transmission, and a non-differential state in which the
power distributing mechanism is not operable as the electrically
controlled continuously variable transmission, and (c) the
automatic transmission includes a second planetary gear set and a
third planetary gear set, the second and third planetary gear sets
having sun gears, carriers and ring gears selected ones of which
are fixed to each other to constitute four elements consisting of a
fourth element, a fifth element, a sixth element and a seventh
elements rotating speeds of which are indicated by straight lines
of a collinear chart in which the four elements are arranged in the
order of the fourth element, the fifth element, the sixth element
and the seventh element in a direction from one of opposite ends of
the collinear chart toward the other end, the fourth element being
selectively connected to the power transmitting member through a
second clutch and selectively fixed to a stationary member through
a first brake, the fifth element being selectively connected to the
power transmitting member through a third clutch and selectively
fixed to the stationary member through a second brake, the sixth
element being fixed to an output rotary member of the automatic
transmission, and the seventh element being selectively connected
to the power transmitting member through a first clutch, the
automatic transmission having a plurality of gear positions which
are established by engaging respective combinations of the first,
second and third clutches and the first and second brakes.
[0172] In a 98.sup.th form of this invention according to the
97.sup.th form, the differential-state switching device includes a
switching clutch operable to connect the second element to the
first element, and/or a switching brake operable to fix the second
element to the stationary member, the first planetary gear set
being placed in the differential state by releasing the switching
clutch and/or the switching brake, and in the locked state by
engaging the switching clutch and/or the switching brake.
[0173] In a 99.sup.th form of this invention according to the
98.sup.th form, the plurality of gear positions includes: a
first-gear position which has a highest speed ratio and which is
established by engaging the switching clutch, the first clutch and
the second brake; a second-gear position which has a speed ratio
lower than that of the first-gear position and which is established
by engaging the switching clutch, the first clutch and the first
brake; a third-gear position which has a speed ratio lower than
that of the second-gear position and which is established by
engaging the switching clutch, the first clutch and the third
clutch; a fourth-gear position which has a speed ratio lower than
that of the third-gear position and which is established by
engaging the switching clutch, the third clutch and the first
brake; and a fifth-gear position which has a speed ratio lower than
that of the fourth-gear position and which is established by
engaging the third clutch, the switching brake and the first
brake.
[0174] In a 100.sup.th form of this invention according to any one
of the 97.sup.th through 99.sup.th forms, the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a double-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear functioning as the fourth element, the second carrier and
the third carrier functioning as the fifth element, the second ring
gear and the third ring gear functioning as the sixth element, and
the third sun gear functioning as the seventh element.
[0175] In a 101.sup.st form of this invention according to any one
of the 97.sup.th through 99.sup.th forms, the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
carrier and the third sun gear functioning as the fourth element,
the second ring gear and the third carrier functioning as the fifth
element, the third ring gear functioning as the sixth element, and
the third ring gear functioning as the seventh element.
[0176] In a 102.sup.nd form of this invention according to any one
of the 97.sup.th through 99.sup.th forms, the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear and the third sun gear functioning as the fourth element,
the second ring gear functioning as the fifth element, the third
carrier functioning as the sixth element, and the second carrier
and the third ring gear functioning as the seventh element.
[0177] In a 103.sup.rd form of this invention according to any one
of the 97.sup.th through 99.sup.th forms, the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear functioning as the fourth element, the second ring gear
and the third ring gear functioning as the fifth element, the third
carrier functioning as the sixth element, and the second carrier
and the third sun gear functioning as the seventh element.
[0178] In a 104.sup.th form of this invention according to any one
of the 97.sup.th through 99.sup.th forms, the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a double-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the third
sun gear functioning as the fourth element, the second ring gear
functioning as the fifth element, the second carrier and third ring
gear functioning as the sixth element, and the second sun gear and
the third carrier functioning as the seventh element.
[0179] In a 105.sup.th form of this invention according to any one
of the 97.sup.th through 99.sup.th forms, the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear functioning as the fourth element, the second carrier and
third ring gear functioning as the fifth element, the second ring
gear and the third carrier functioning as the sixth element, and
the third sun gear functioning as the seventh element.
[0180] In a 106.sup.th form of this invention according to any one
of the 97.sup.th through 99.sup.th forms, the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the third
sun gear functioning as the fourth element, the second ring gear
functioning as the fifth element, the second carrier and the third
carrier functioning as the sixth element, and the second sun gear
and the third ring gear functioning as the seventh element.
[0181] In a 107.sup.th form of this invention according to any one
of the 97.sup.th through 99.sup.th forms, the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear and the third sun gear functioning as the fourth element,
the third carrier functioning as the fifth element, the second
carrier and the third ring gear functioning as the sixth element,
and the second ring gear functioning as the seventh element.
[0182] According to a 108.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a double-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear being selectively connected to the power transmitting
member through a second clutch and selectively fixed to a
stationary member through a first brake, the second carrier and the
third carrier being selectively connected to the power transmitting
member through a third clutch and selectively fixed to the
stationary member through a second brake, the second ring gear and
the third ring gear being fixed to an output rotary member of the
automatic transmission, and the third sun gear being selectively
connected to the power transmitting member through a first
clutch.
[0183] According to a 109.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear being selectively connected to the power transmitting
member through a first clutch, the second carrier and the third sun
gear being selectively connected to the power transmitting member
through a second clutch and selectively fixed to a stationary
member through a first brake, the second ring gear and the third
carrier being selectively connected to the power transmitting
member through a third clutch and selectively fixed to the
stationary member through a second brake, and the third ring gear
being fixed an output rotary member of the automatic
transmission.
[0184] According to a 110.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear and the third sun gear being selectively connected to the
power transmitting member through a second clutch and selectively
fixed to a stationary member through a first brake, the second
carrier and the third ring gear being selectively connected to the
power transmitting member through a first clutch, the second ring
gear being selectively connected to the power transmitting member
through a third clutch and selectively fixed to the stationary
member through a second brake, and the third carrier being fixed to
an output rotary member of the automatic transmission.
[0185] According to a 111.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear being selectively connected to the power transmitting
member through a second clutch and selectively fixed to a
stationary member through a first brake, the second carrier and the
third sun gear being selectively connected to the power
transmitting member through a first clutch, the second ring gear
and the third ring gear being selectively connected to the power
transmitting member through a third clutch and selectively fixed to
the stationary member through a second brake, and the third carrier
being fixed to an output rotary member of the automatic
transmission.
[0186] According to a 112.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a double-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear and the third carrier being selectively connected to the
power transmitting member through a second clutch, the second
carrier and the third ring gear being integrally fixed to each
other for rotation as a unit and fixed to an output rotary member
of the automatic transmission, the second ring gear being
selectively connected to the power transmitting member through a
third clutch and selectively fixed to a stationary member through a
second brake, and the third sun gear being selectively connected to
the power transmitting member through a second clutch and
selectively fixed to the stationary member through a first
brake.
[0187] According to a 113.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear being selectively connected to the power transmitting
member through a second clutch and selectively fixed to a
stationary member through a first brake, the second carrier and the
third ring gear being selectively connected to the power
transmitting member through a third clutch and selectively fixed to
a stationary member through a second brake, the second ring gear
and the third carrier being fixed to an output rotary member of the
automatic transmission, and the third sun gear being selectively
connected to the power transmitting member through a first
clutch.
[0188] According to a 114.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear and the third ring gear being selectively connected to the
power transmitting member through a second clutch, the second
carrier and the third carrier being fixed to an output rotary
member of the automatic transmission, the second ring gear being
selectively connected to the power transmitting member through a
third clutch and selectively fixed to a stationary member through a
second brake, and the third sun gear being selectively connected to
the power transmitting member through a second clutch and
selectively fixed to the stationary member through a first
brake.
[0189] According to a 115.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear and the third sun gear being selectively fixed to a
stationary member through a first brake, the second carrier and the
third ring gear being fixed to an output rotary member of the
automatic transmission, the second ring gear being selectively
connected to the power transmitting member through a first clutch,
and the third carrier being selectively connected to the power
transmitting member through a third clutch and selectively fixed to
the stationary member through a second brake.
[0190] In a 116.sup.th form of this invention according to any one
of the 108.sup.th through 115.sup.th forms, the shifting-state
switching device includes a switching clutch operable to connect
the first carrier and the first sun gear to each other, and/or a
switching brake operable fix the first sun gear to the stationary
member.
[0191] According to a 117.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member,
an automatic transmission disposed between the power transmitting
member and a drive wheel of a vehicle, and a second electric motor
disposed between the power transmitting member and the drive wheel,
characterized in that the automatic transmission includes a
plurality of input clutches selectively connected to an output
shaft of the power distributing mechanism, and the automatic
transmission has a plurality of gear positions which are
established by selectively engaging and releasing the plurality of
input clutches.
[0192] In a 118.sup.th form of this invention according to the
117.sup.th form, the power distributing mechanism includes a first
planetary gear set having as three elements a sun gear, a carrier
and a ring gear, the three elements consisting of a first element,
a second element and a third element which are arranged in the
order of the second element, the first element and the third
elements in a direction from one of opposite ends of a collinear
chart toward the other end, the collinear chart having straight
lines indicating rotating speeds of the three elements, the first
element being fixed to the engine, the second element being fixed
to the first electric motor, and the third element being fixed to
the power transmitting member.
[0193] In a 119.sup.th form of this invention according to the
118.sup.th form, the power distributing mechanism further includes
a differential-state switching device operable to place the power
distributing mechanism selectively in a differential state in which
the power distributing mechanism is operable as an electrically
controlled continuously variable transmission, and a locked state
in which the power distributing mechanism is not operable as the
electrically controlled continuously variable transmission
[0194] In a 120.sup.th form of this invention according to any one
of the 117.sup.th through 119.sup.th forms, the automatic
transmission is a step-variable automatic transmission.
[0195] In the drive system according to any one of the 97.sup.th
through 116.sup.th forms and the 117.sup.th through 120.sup.th
forms of this invention, the power distributing mechanism is
controlled by the differential-state switching device, to be placed
selectively in the differential state in which the power
distributing mechanism is operable as an electrically controlled
continuously variable transmission, and the locked state in which
the power distributing mechanism is not operable as the
electrically controlled continuously variable transmission.
Therefore, the present drive system has not only an advantage of an
improvement in the fuel economy owing to a function of a
transmission whose speed ratio is electrically variable, but also
an advantage of high power transmitting efficiency owing to a
function of a gear type transmission capable of mechanically
transmitting a vehicle drive force. Accordingly, when the engine is
in a normal output state with a relatively low or medium output
while the vehicle is running at a relatively low or medium running
speed, the power distributing mechanism is placed in the
differential state, assuring a high degree of fuel economy of the
vehicle. When the vehicle is running at a relatively high speed, on
the other hand, the power distributing mechanism is placed in the
locked state in which the output of the engine is transmitted to
the drive wheel primarily through a mechanical power transmitting
path, so that the fuel economy is improved owing to reduction of a
loss of conversion of a mechanical energy into an electric energy,
which loss would take place when the drive system is operated as
the transmission whose speed ratio is electrically variable. When
the engine is in a high-output state, the power distributing
mechanism is also placed in the locked state. Therefore, the power
distributing mechanism is operated as the transmission whose speed
ratio is electrically variable, only when the vehicle speed is
relatively low or medium or when the engine output is relatively
low or medium, so that the required amount of electric energy
generated by the electric motor that is, the maximum amount of
electric energy that must be transmitted from the electric motor
can be reduced, making it possible to minimize the required sizes
of the electric motor, and the required size of the drive system
including the electric motor.
[0196] In the 99.sup.th form of this invention, the drive system
having five forward drive positions when the power distributing
mechanism is placed in the locked state is available with a small
size, particularly, in the dimension in its axial direction.
[0197] In the 117.sup.th form of the invention, a vehicle drive
force is transmitted from the power transmitting member to the
automatic transmission through the plurality of input clutches, so
that the automatic transmission is small-sized, whereby the overall
size of the drive system including the automatic transmission is
reduced.
[0198] According to a 121.sup.st form of the invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a first planetary gear device having as three
elements a sun gear, a carrier and a ring gear, the three elements
consisting of a first element, a second element and a third element
which are arranged in the order of the second element, the first
element and the third elements in a direction from one of opposite
ends of a collinear chart toward the other end, the collinear chart
having straight lines indicating rotating speeds of the three
elements, the first element being fixed to the engine, the second
element being fixed to the first electric motor, and the third
element being fixed to the power transmitting member, the power
distributing mechanism further including a differential-state
switching device operable to place the power distributing mechanism
selectively in a differential state in which the power distributing
mechanism is operable as an electrically controlled continuously
variable transmission, and a locked state in which the power
distributing mechanism is not operable as the electrically
controlled continuously variable transmission, and (c) the
automatic transmission includes a second planetary gear set and a
third planetary gear set, the second and third planetary gear sets
having sun gears, carriers and ring gears selected ones of which
are fixed to each other to constitute four elements consisting of a
fourth element, a fifth element, a sixth element and a seventh
elements rotating speeds of which are indicated by straight lines
of a collinear chart in which the four elements are arranged in the
order of the fourth element, the fifth element, the sixth element
and the seventh element in a direction from one of opposite ends of
the collinear chart toward the other end, the fourth element being
selectively connected to the power transmitting member through a
first clutch and selectively fixed to a stationary member through a
second brake, the fifth element being selectively connected to the
power transmitting member through a second clutch and selectively
fixed to the stationary member through a third brake, the sixth
element being fixed to an output rotary member of the automatic
transmission, and the seventh element being selectively fixed to
the stationary member through a first brake, the automatic
transmission having a plurality of gear positions which are
established by engaging respective combinations of the first and
second clutches and the first, second and third brakes.
[0199] In a 122.sup.nd form of this invention according to the
121.sup.st form, the differential-state switching device includes a
switching clutch operable to connect the second element to the
first element, and/or a switching brake operable to fix the second
element to the stationary member, the first planetary gear set
being placed in the differential state by releasing the switching
clutch and/or the switching brake, and in the locked state by
engaging the switching clutch and/or the switching brake.
[0200] In a 123.sup.rd form of this invention according to the
122.sup.nd form, the plurality of gear positions includes: a
first-gear position which has a highest speed ratio and which is
established by engaging the switching clutch, the first clutch and
the first brake; a second-gear position which has a speed ratio
lower than that of the first-gear position and which is established
by engaging the switching clutch, the second clutch and the first
brake; a third-gear position which has a speed ratio lower than
that of the second-gear position and which is established by
engaging the switching clutch, the first clutch and the second
clutch; a fourth-gear position which has a speed ratio lower than
that of the third-gear position and which is established by
engaging the switching clutch, the second clutch and the second
brake; and a fifth-gear position which has a speed ratio lower than
that of the fourth-gear position and which is established by
engaging the second clutch, the switching brake and the second
brake.
[0201] In a 124.sup.th form of this invention according to any one
of the 121.sup.st through 123.sup.rd forms, the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a double-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
carrier and the third sun gear functioning as the fourth element,
the second ring gear functioning as the fifth element, the third
carrier functioning as the sixth element, and the second sun gear
and the third ring gear functioning as the seventh element.
[0202] In a 125.sup.th form of this invention according to any one
of the 121.sup.st through 123.sup.rd forms, the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
carrier and the third sun gear functioning as the fourth element,
the second ring gear and the third carrier functioning as the fifth
element, the third ring gear functioning as the sixth element, and
the second sun gear functioning as the seventh element.
[0203] In a 126.sup.th form of this invention according to any one
of the 121.sup.st through 123.sup.rd forms, the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear and the third sun gear functioning as the fourth element,
the second ring gear and the third carrier functioning as the fifth
element, the third ring gear functioning as the sixth element, and
the second carrier functioning as the seventh element.
[0204] In a 127.sup.th form of this invention according to any one
of the 121.sup.st through 123.sup.rd forms, the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear and the third sun gear functioning as the fourth element,
the second ring gear functioning as the fifth element, the third
carrier functioning as the sixth element, and the second carrier
and the third ring gear functioning as the seventh element.
[0205] In a 128.sup.th form of this invention according to any one
of the 121.sup.st through 123.sup.rd forms, the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a double-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the third
sun gear functioning as the fourth element, the second carrier
functioning as the fifth element, the second ring gear and the
third carrier functioning as the sixth element, and the second sun
gear and the third ring gear functioning as the seventh
element.
[0206] In a 129.sup.th form of this invention according to any one
of the 121.sup.st through 123.sup.rd forms, the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a double-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear and the third sun gear functioning as the fourth element,
the second carrier functioning as the fifth element, the second
ring gear and the third ring gear functioning as the sixth element,
and the third carrier functioning as the seventh element.
[0207] In a 130.sup.th form of this invention according to any one
of the 121.sup.st through 123.sup.rd forms, the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a double-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear functioning as the fourth element, the second carrier and
the third carrier functioning as the fifth element, the second ring
gear and the third ring gear functioning as the sixth element, and
the third sun gear functioning as the seventh element.
[0208] In a 131.sup.st form of this invention according to any one
of the 121.sup.st through 123.sup.rd forms, wherein the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear functioning as the fourth element, the second ring gear
and the third ring gear functioning as the fifth element, the third
carrier, and the second carrier and the third sun gear functioning
as the seventh element.
[0209] In a 132.sup.nd form of this invention according to any one
of the 121.sup.st through 123.sup.rd forms, the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
carrier functioning as the fourth element, the second ring gear and
the third ring gear functioning as the fifth element, the third
carrier functioning as the sixth element, and the second sun gear
and the third sun gear functioning as the seventh element.
[0210] In a 133.sup.rd form of this invention according to any one
of the 121.sup.st through 123.sup.rd forms, the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear functioning as the fourth element, the third ring gear and
the third ring gear functioning as the fifth element, the second
ring gear and the third carrier functioning as the sixth element,
and the second carrier and the third sun gear functioning as the
seventh element.
[0211] In a 134.sup.th form of this invention according to any one
of the 121.sup.st through 123.sup.rd forms, the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear and the third sun gear functioning as the fourth element,
the second carrier functioning as the fifth element, the second
ring gear and the third carrier functioning as the sixth element,
and the third ring gear functioning as the seventh element.
[0212] In a 135.sup.th form of this invention according to any one
of the 121.sup.st through 123.sup.rd forms, the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear functioning as the fourth element, the second carrier and
the third ring gear functioning as the fifth element, the second
ring gear and the third carrier functioning as the sixth element,
and the third sun gear functioning as the seventh element.
[0213] In a 136.sup.th form of this invention according to any one
of the 121.sup.st through 123.sup.rd form, the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the third
sun gear functioning as the fourth element, the second ring gear
functioning as the fifth element, the second carrier and the third
carrier functioning as the sixth element, and the second sun gear
and the third ring gear functioning as the seventh element.
[0214] According to a 137.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear and the third ring gear being selectively fixed to a
stationary member through a first brake, the second carrier and the
third sun gear being selectively connected to the power
transmitting member through a first clutch and selectively fixed to
the stationary member through a second brake, the second ring gear
being selectively connected to the power transmitting member
through a second clutch and selectively fixed to the stationary
member through a third brake, the third carrier being fixed to an
output rotary member of the automatic transmission.
[0215] According to a 138.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear being selectively connected to the power transmitting
member through a first clutch, the second carrier and the third sun
gear being selectively connected to the power transmitting member
through a second clutch and selectively fixed to a stationary
member through a first brake, the second sun gear being selectively
fixed to a stationary member through a first brake, the second
carrier and the third sun gear being selectively connected to the
power transmitting member through a first clutch and selectively
fixed to the stationary member through a second brake, the second
ring gear and the third carrier being selectively connected to the
power transmitting member through a second clutch and selectively
fixed to the stationary member through a third brake, and the third
ring gear being fixed an output rotary member of the automatic
transmission.
[0216] According to a 139.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear and the third sun gear being selectively connected to the
power transmitting member through a second clutch and selectively
fixed to a stationary member through a first brake, the second sun
gear and the third sun gear being selectively connected to the
power transmitting member through a first clutch and selectively
fixed to a stationary member through a second brake, the second
carrier being selectively fixed to the stationary member through a
first brake, the second ring gear and the third carrier being
selectively connected to the power transmitting member through a
second clutch and selectively fixed to the stationary member
through a third brake, and the third ring gear being fixed to an
output rotary member of the automatic transmission.
[0217] According to a 140.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear and the third sun gear being selectively connected to the
power transmitting member through a first clutch and selectively
fixed to a stationary member through a second brake, the second
carrier being selectively connected to the power transmitting
member through a second clutch and selectively fixed to the
stationary member through a third brake, the second ring gear and
the third ring gear being fixed to an output rotary member of the
automatic transmission, and the third carrier being selectively
fixed to the stationary member through a first brake.
[0218] According to a 141.sup.st form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (b) the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear and the third ring gear being selectively fixed to a
stationary member through a first brake, the second carrier being
selectively connected to the power transmitting member through a
second clutch and selectively fixed to the stationary member
through a third brake, the second ring gear and the third carrier
being fixed to an output rotary member of the automatic
transmission, the third sun gear being selectively connected to the
power transmitting member through a first clutch and selectively
fixed to the stationary member through a second brake.
[0219] According to a 142.sup.nd form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a double-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear and the third sun gear being selectively connected to the
power transmitting member through a first clutch and selectively
fixed to a stationary member through a second brake, the second
carrier being selectively connected to the power transmitting
member through a second clutch and selectively fixed to the
stationary member through a third brake, the second ring gear and
the third ring gear being fixed to an output rotary member of the
automatic transmission, and the third carrier selectively fixed to
the stationary member through a first brake.
[0220] According to a 143.sup.rd form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a double-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear being selectively connected to the power transmitting
member through a first clutch and selectively fixed to a stationary
member through a second brake, the second carrier and the third
carrier being selectively connected to the power transmitting
member through a second clutch and selectively fixed to the
stationary member through a third brake, the second ring gear and
the third ring gear being fixed to an output rotary member of the
automatic transmission, the third sun gear being selectively fixed
to the stationary member through a first brake.
[0221] According to a 144.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear being selectively connected to the power transmitting
member through a first clutch and selectively fixed to a stationary
member through a second brake, the second carrier and the third sun
gear being selectively fixed to the stationary member through a
first brake, the second ring gear and the third ring gear being
selectively connected to the power transmitting member through a
second clutch and selectively fixed to the stationary member
through a third brake, the third carrier being fixed an output
rotary member of the automatic transmission.
[0222] According to a 145.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear and the third sun gear being selectively fixed to a
stationary member through a first brake, the second carrier being
selectively connected to the power transmitting member through a
first clutch and selectively fixed to the stationary member through
a second brake, the second ring gear and the third ring being
selectively connected to the power transmitting member through a
second clutch and selectively fixed to the stationary member
through a third brake, the third carrier being fixed an output
rotary member of the automatic transmission.
[0223] According to a 146.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a double-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear being selectively connected to the power transmitting
member through a first clutch and selectively fixed to a stationary
member through a second brake, the second carrier and the third sun
gear being selectively fixed to the stationary member through a
first brake, the second ring gear and the third carrier being fixed
to an output rotary member of the automatic transmission, and the
third ring gear being selectively connected to the power
transmitting member through a second clutch and selectively fixed
to the stationary member through a third brake.
[0224] According to a 147.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear and the third sun gear being selectively connected to the
power transmitting member through a first clutch and selectively
fixed to a stationary member through a second brake, the second
carrier being selectively connected to the power transmitting
member through a second clutch and selectively fixed to the
stationary member through a third brake, the second ring gear and
the third carrier being fixed to an output rotary member of the
automatic transmission, and the third ring gear being selectively
fixed to the stationary member through a first brake.
[0225] According to a 148.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear being selectively connected to the power transmitting
member through a first clutch and selectively fixed to a stationary
member through a second brake, the second carrier and the third
ring gear being selectively connected to the power transmitting
member through a second clutch and selectively fixed to the
stationary member through a third brake, the second ring gear and
the third carrier being fixed to an output rotary member of the
automatic transmission, and the third sun gear being selectively
fixed to the stationary member through a first brake.
[0226] According to a 149.sup.th form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member, a
step-variable automatic transmission disposed between the power
transmitting member and a drive wheel of a vehicle, and a second
electric motor disposed between the power transmitting member and
the drive wheel, characterized in that (b) the power distributing
mechanism includes a single-pinion type first planetary gear device
having a first sun gear, a first carrier and a first ring gear, the
first carrier being fixed to the engine, the first sun being fixed
to the first electric motor, and the first ring gear being fixed to
the power transmitting member, the power distributing mechanism
further including a differential-state switching device operable to
place the power distributing mechanism selectively in a
differential state in which the power distributing mechanism is
operable as an electrically controlled continuously variable
transmission, and a locked state in which the power distributing
mechanism is not operable as the electrically controlled
continuously variable transmission, and (c) the automatic
transmission includes a single-pinion type second planetary gear
set having a second sun gear, a second carrier and a second ring
gear, and a single-pinion type third planetary gear set having a
third sun gear, a third carrier and a third ring gear, the second
sun gear and the third ring gear being selectively fixed to a
stationary member through a first brake, the second carrier and the
third carrier being fixed to an output rotary member of the
automatic transmission, and the second ring gear being selectively
connected to the power transmitting member through a second clutch
and selectively fixed to the stationary member through a third
brake, and the third sun gear being selectively connected to the
power transmitting member through a first clutch and selectively
fixed to the stationary member through a second brake.
[0227] In a 150.sup.th form of this invention according to any one
of the 137.sup.th through 149.sup.th forms, the shifting-state
switching device includes a switching clutch operable to connect
the first carrier and the first sun gear to each other, and/or a
switching brake operable fix the first sun gear to the stationary
member.
[0228] According to a 151.sup.st form of this invention, there is
provided a vehicular drive system including (a) a power
distributing mechanism operable to distribute an output of an
engine to a first electric motor and a power transmitting member,
an automatic transmission disposed between the power transmitting
member and a drive wheel of a vehicle, and a second electric motor
disposed between the power transmitting member and the drive wheel,
characterized in that (b) the power distributing mechanism includes
a planetary gear device having as three elements a sun gear, a
carrier and a ring gear, the three elements consisting of a first
element, a second element and a third element which are arranged in
the order of the second element, the first element and the third
elements in a direction from one of opposite ends of a collinear
chart toward the other end, the collinear chart having straight
lines indicating rotating speeds of the three elements, the first
element being fixed to the engine, the second element being fixed
to the first electric motor, and the third element being fixed to
the power transmitting member, and (b) the automatic transmission
is arranged to increase a rotating speed of the power transmitting
member.
[0229] In a 152.sup.nd form of this invention according to the
151.sup.st form, the power distributing mechanism further includes
a differential-state switching device operable to place the power
distributing mechanism selectively in a differential state in which
the power distributing mechanism is operable as an electrically
controlled continuously variable transmission, and a locked state
in which the power distributing mechanism is not operable as the
electrically controlled continuously variable transmission
[0230] In the drive system according to any one of the 121.sup.st
through 150.sup.th forms of this invention, the power distributing
mechanism is controlled by the differential-state switching device,
to be placed selectively in the differential state in which the
power distributing mechanism is operable as an electrically
controlled continuously variable transmission, and the locked state
in which the power distributing mechanism is not operable as the
electrically controlled continuously variable transmission.
Therefore, the present drive system has not only an advantage of an
improvement in the fuel economy owing to a function of a
transmission whose speed ratio is electrically variable, but also
an advantage of high power transmitting efficiency owing to a
function of a gear type transmission capable of mechanically
transmitting a vehicle drive force. Accordingly, when the engine is
in a normal output state with a relatively low or medium output
while the vehicle is running at a relatively low or medium running
speed, the power distributing mechanism is placed in the
differential state, assuring a high degree of fuel economy of the
vehicle. When the vehicle is running at a relatively high speed, on
the other hand, the power distributing mechanism is placed in the
locked state in which the output of the engine is transmitted to
the drive wheel primarily through a mechanical power transmitting
path, so that the fuel economy is improved owing to reduction of a
loss of conversion of a mechanical energy into an electric energy,
which loss would take place when the drive system is operated as
the transmission whose speed ratio is electrically variable. When
the engine is in a high-output state, the power distributing
mechanism is also placed in the locked state. Therefore, the power
distributing mechanism is operated as the transmission whose speed
ratio is electrically variable, only when the vehicle speed is
relatively low or medium or when the engine output is relatively
low or medium, so that the required amount of electric energy
generated by the electric motor that is, the maximum amount of
electric energy that must be transmitted from the electric motor
can be reduced, making it possible to minimize the required sizes
of the electric motor, and the required size of the drive system
including the electric motor.
[0231] In the 123.sup.rd form of this invention, the drive system
having five forward drive positions when the power distributing
mechanism is placed in the locked state is available with a small
size, particularly, in the dimension in its axial direction.
[0232] In the 151.sup.st form of the invention, the rotating speed
of the power transmitting member is increased by the automatic
transmission, so that the power transmitting member, and the third
element of the planetary gear set which is rotated with the power
transmitting member, can be rotated at a comparatively low speed,
whereby there is not a high degree of opportunity wherein the first
electric motor M1 fixed to the first element must be rotated in the
negative direction, that is must be operated by application of an
electric energy thereto. Accordingly, the fuel economy can be
improved.
BRIEF DESCRIPTION OF DRAWINGS
[0233] [FIG. 1] This figure is a schematic view for explaining an
arrangement of a drive system of a hybrid vehicle according to one
embodiment of the present invention.
[0234] [FIG. 2] This figure is a table indicating shifting actions
of the drive system of the hybrid vehicle of the embodiment of FIG.
1 operable in a continuously variable shifting state or a
step-variable shifting state, in relation to different combinations
of operating states of hydraulically operated frictional coupling
devices to effect the respective shifting actions.
[0235] [FIG. 3] This figure is a collinear chart showing relative
rotating speeds of rotary elements of the drive system of the
hybrid vehicle of the embodiment of FIG. 1 operated in the
step-variable shifting state, in different gear positions of the
drive system.
[0236] [FIG. 4] This figure is a view showing an example of an
operating state of a power distributing mechanism of the drive
system when switched to the continuously-variable shifting state,
the view corresponding to a part of the collinear chart of FIG. 3
which shows the power distributing mechanism.
[0237] [FIG. 5] This figure is a view showing the operating state
of the power distributing mechanism 16 of the drive system when
switched to the step-variable shifting state by engagement of a
switching clutch C0, the view corresponding to the part of the
collinear chart of FIG. 3 which shows the power distributing
mechanism.
[0238] [FIG. 6] This figure is a view for explaining input and
output signals of an electronic control device provided in the
drive system of the embodiment of FIG. 1.
[0239] [FIG. 7] This figure is a functional block diagram for
explaining major control functions performed by the electronic
control device of FIG. 6.
[0240] [FIG. 8] This figure is a view indicating a stored map used
by switching control means of FIG. 7 to selectively place the drive
system in the continuously-variable shifting state and the
step-variable shifting state.
[0241] [FIG. 9] This figure is a view showing an example of a
manually operable shifting device which includes a shift lever and
which is used to select a plurality of operating positions.
[0242] [FIG. 10] This figure is a view illustrating an example of a
change of the operating speed of an engine during a ship-up action
of a step-variable transmission.
[0243] [FIG. 11] This figure is a functional block diagram
corresponding to that of FIG. 7, for explaining major control
functions performed by an electronic control device of a drive
system according to another embodiment of the present
invention.
[0244] [FIG. 12] This figure is a view for explaining an operation
of switching control means in the electronic control device in the
embodiment of FIG. 11.
[0245] [FIG. 13] This figure is a flow chart illustrating major
control operations performed by the electronic control device in
the embodiment of FIG. 11.
[0246] [FIG. 14] This figure is a schematic view corresponding to
that of FIG. 1, for explaining an arrangement of a drive system of
a hybrid vehicle according to another embodiment of the
invention.
[0247] [FIG. 15] This figure is a table corresponding to that of
FIG. 2, indicating shifting actions of the drive system of the
hybrid vehicle of the embodiment of FIG. 14 operable in a
continuously variable shifting state or a step-variable shifting
state, in relation to different combinations of operating states of
hydraulically operated frictional coupling devices to effect the
respective shifting actions.
[0248] [FIG. 16] This figure is a collinear chart corresponding to
that of FIG. 3, showing relative rotating speeds of rotary elements
of the drive system of the hybrid vehicle of the embodiment of FIG.
14 operated in the step-variable shifting state, in different gear
positions of the drive system.
[0249] [FIG. 17] This figure is a schematic view corresponding to
that of FIG. 1, for explaining an arrangement of a drive system of
a hybrid vehicle according to another embodiment of the
invention.
[0250] [FIG. 18] This figure is a table corresponding to that of
FIG. 2, indicating shifting actions of the drive system of the
hybrid vehicle of the embodiment of FIG. 17 operable in a
step-variable shifting state, in relation to different combinations
of operating states of hydraulically operated frictional coupling
devices to effect the respective shifting actions.
[0251] [FIG. 19] This figure is a collinear chart corresponding to
that of FIG. 3, showing relative rotating speeds of rotary elements
of the drive system of the hybrid vehicle of the embodiment of FIG.
17 operated in the step-variable shifting state, in different gear
positions of the drive system.
[0252] [FIG. 20] This figure is a table indicating shifting actions
of the drive system of the hybrid vehicle of the embodiment of FIG.
17 operable in a continuously-variable shifting state, in relation
to different combinations of operating states of the hydraulically
operated frictional coupling devices to effect the respective
shifting actions.
[0253] [FIG. 21] This figure is a collinear chart showing relative
rotating speeds of the rotary elements of the drive system of the
hybrid vehicle of the embodiment of FIG. 17 operated in the
continuously-variable shifting state, in the different gear
positions of the drive system.
[0254] [FIG. 22] This figure is a schematic view corresponding to
that of FIG. 1, for explaining an arrangement of a drive system of
a hybrid vehicle according to another embodiment of the
invention.
[0255] [FIG. 23] This figure is a table corresponding to that of
FIG. 2, indicating shifting actions of the drive system of the
hybrid vehicle of the embodiment of FIG. 22 operable in a
step-variable shifting state, in relation to different combinations
of operating states of hydraulically operated frictional coupling
devices to effect the respective shifting actions.
[0256] [FIG. 24] This figure is a collinear chart corresponding to
that of FIG. 3, showing relative rotating speeds of rotary elements
of the drive system of the hybrid vehicle of the embodiment of FIG.
22 operated in the step-variable shifting state, in different gear
positions of the drive system.
[0257] [FIG. 25] This figure is a table indicating shifting actions
of the drive system of the hybrid vehicle of the embodiment of FIG.
22 operable in a continuously-variable shifting state, in relation
to different combinations of operating states of the hydraulically
operated frictional coupling devices to effect the respective
shifting actions.
[0258] [FIG. 26] This figure is a collinear chart showing relative
rotating speeds of the rotary elements of the drive system of the
hybrid vehicle of the embodiment of FIG. 22 operated in the
continuously-variable shifting state, in the different gear
positions of the drive system.
[0259] [FIG. 27] This figure is a schematic view corresponding to
that of FIG. 1, for explaining an arrangement of a drive system of
a hybrid vehicle according to another embodiment of the
invention.
[0260] [FIG. 28] This figure is a table corresponding to that of
FIG. 2, indicating shifting actions of the drive system of the
hybrid vehicle of the embodiment of FIG. 27 operable in a
continuously-variable shifting state or a step-variable shifting
state, in relation to different combinations of operating states of
hydraulically operated frictional coupling devices to effect the
respective shifting actions.
[0261] [FIG. 29] This figure is a collinear chart corresponding to
that of FIG. 3, showing relative rotating speeds of rotary elements
of the drive system of the hybrid vehicle of the embodiment of FIG.
27 operated in the step-variable shifting state, in different gear
positions of the drive system.
[0262] [FIG. 30] This figure is a schematic view corresponding to
that of FIG. 1, for explaining an arrangement of a drive system of
a hybrid vehicle according to another embodiment of the
invention.
[0263] [FIG. 31] This figure is a table corresponding to that of
FIG. 2, indicating shifting actions of the drive system of the
hybrid vehicle of the embodiment of FIG. 30 operable in a
continuously-variable shifting state or a step-variable shifting
state, in relation to different combinations of operating states of
hydraulically operated frictional coupling devices to effect the
respective shifting actions.
[0264] [FIG. 32] This figure is a collinear chart corresponding to
that of FIG. 3, showing relative rotating speeds of rotary elements
of the drive system of the hybrid vehicle of the embodiment of FIG.
30 operated in the step-variable shifting state, in different gear
positions of the drive system.
[0265] [FIG. 33] This figure is a schematic view corresponding to
that of FIG. 30, for explaining an arrangement of a drive system of
a hybrid vehicle according to another embodiment of the
invention.
[0266] [FIG. 34] This figure is a schematic view corresponding to
that of FIG. 30, for explaining an arrangement of a drive system of
a hybrid vehicle according to another embodiment of the
invention.
[0267] [FIG. 35] This figure is a schematic view corresponding to
that of FIG. 27, for explaining an arrangement of a drive system of
a hybrid vehicle according to another embodiment of the
invention.
[0268] [FIG. 36] This figure is a table corresponding to that of
FIG. 28, indicating shifting actions of the drive system of the
hybrid vehicle of the embodiment of FIG. 35 operable in a
continuously-variable shifting state or a step-variable shifting
state, in relation to different combinations of operating states of
hydraulically operated frictional coupling devices to effect the
respective shifting actions.
[0269] [FIG. 37] This figure is a collinear chart corresponding to
that of FIG. 29, showing relative rotating speeds of rotary
elements of the drive system of the hybrid vehicle of the
embodiment of FIG. 35 operated in the step-variable shifting state,
in different gear positions of the drive system.
[0270] [FIG. 38] This figure is a schematic view corresponding to
that of FIG. 35, for explaining an arrangement of a drive system of
a hybrid vehicle according to another embodiment of the
invention.
[0271] [FIG. 39] This figure is a schematic view corresponding to
that of FIG. 14, for explaining an arrangement of a drive system of
a hybrid vehicle according to another embodiment of the
invention.
[0272] [FIG. 40] This figure is a table corresponding to that of
FIG. 15, indicating shifting actions of the drive system of the
hybrid vehicle of the embodiment of FIG. 39 operable in a
continuously-variable shifting state or a step-variable shifting
state, in relation to different combinations of operating states of
hydraulically operated frictional coupling devices to effect the
respective shifting actions.
[0273] [FIG. 41] This figure is a collinear chart corresponding to
that of FIG. 16, showing relative rotating speeds of rotary
elements of the drive system of the hybrid vehicle of the
embodiment of FIG. 39 operated in the step-variable shifting state,
in different gear positions of the drive system.
[0274] [FIG. 42] This figure is a schematic view corresponding to
that of FIG. 14, for explaining an arrangement of a drive system of
a hybrid vehicle according to another embodiment of the
invention.
[0275] [FIG. 43] This figure is a table corresponding to that of
FIG. 15, indicating shifting actions of the drive system of the
hybrid vehicle of the embodiment of FIG. 42 operable in a
continuously-variable shifting state or a step-variable shifting
state, in relation to different combinations of operating states of
hydraulically operated frictional coupling devices to effect the
respective shifting actions.
[0276] [FIG. 44] This figure is a collinear chart corresponding to
that of FIG. 16, showing relative rotating speeds of rotary
elements of the drive system of the hybrid vehicle of the
embodiment of FIG. 42 operated in the step-variable shifting state,
in different gear positions of the drive system.
[0277] [FIG. 45] This figure is a schematic view corresponding to
that of FIG. 42, for explaining an arrangement of a drive system of
a hybrid vehicle according to another embodiment of the
invention.
[0278] [FIG. 46] This figure is a schematic view corresponding to
that of FIG. 42, for explaining an arrangement of a drive system of
a hybrid vehicle according to another embodiment of the
invention.
[0279] [FIG. 47] This figure is a schematic view corresponding to
that of FIG. 39, for explaining an arrangement of a drive system of
a hybrid vehicle according to another embodiment of the
invention.
[0280] [FIG. 48] This figure is a table corresponding to that of
FIG. 40, indicating shifting actions of the drive system of the
hybrid vehicle of the embodiment of FIG. 47 operable in a
continuously-variable shifting state or a step-variable shifting
state, in relation to different combinations of operating states of
hydraulically operated frictional coupling devices to effect the
respective shifting actions.
[0281] [FIG. 49] This figure is a collinear chart corresponding to
that of FIG. 41, showing relative rotating speeds of rotary
elements of the drive system of the hybrid vehicle of the
embodiment of FIG. 47 operated in the step-variable shifting state,
in different gear positions of the drive system.
[0282] [FIG. 50] This figure is a schematic view corresponding to
that of FIG. 47, for explaining an arrangement of a drive system of
a hybrid vehicle according to another embodiment of the
invention.
[0283] [FIG. 51] This figure is a view showing an example of a
shifting-state selecting device manually operable by the user to
select the shifting state, in the form of a seesaw switch
functioning as a selector switch.
[0284] [FIG. 52] This figure is a functional block diagram for
explaining major control functions performed by an electronic
control device in another embodiment of the invention, which is a
modification of the embodiment of FIG. 6.
[0285] [FIG. 53] This figure is a view illustrating a stored
step-variable-shifting control map used for determining a shifting
action of an automatic shifting portion, in a two-dimensional
coordinate system defined by an axis of a vehicle speed and an axis
of an output torque, the shifting map including shift-up boundary
lines and shift-down boundary lines.
[0286] [FIG. 54] This figure is a view illustrating an example of a
stored drive-power-source selection control map used to select an
engine drive state and a motor drive state, in the same
two-dimensional coordinate system described above, the
drive-power-source selection control map defining boundary lines
defining an engine drive region and a motor drive region.
[0287] [FIG. 55] This figure is a view corresponding to a part of
the collinear chart of FIG. 3 which shows a differential portion,
for explaining an operating state of the differential portion in
the continuously-variable shifting state, in which the engine speed
is substantially zero in the motor drive state.
[0288] [FIG. 56] This figure is a view illustrating an example of a
stored switching control map in a two-dimensional coordinate system
defined by an axis of a vehicle speed and an axis of an output
torque, the switching control map including boundary lines defining
a continuously-variable shifting region and a step-variable
shifting region.
[0289] [FIG. 57] This figure is a view illustrating a complex
control map which is a combination of the step-variable-shifting
control map of FIG. 53, the drive-power-source selection control
map of FIG. 54 and the switching control map of FIG. 56.
[0290] [FIG. 58] This figure is a view corresponding to that of
FIG. 53, illustrating a stored power-mode step-variable-shifting
control map corresponding to that of FIG. 53, in a two-dimensional
coordinate system defined by an axis of a vehicle speed and an axis
of an output torque.
[0291] [FIG. 59] This figure is a view corresponding to that of
FIG. 54, illustrating a stored power-mode drive-power-source
selection control map corresponding to that of FIG. 54, in a
two-dimensional coordinate system defined by an axis of a vehicle
sped and an axis of an output torque.
[0292] [FIG. 60] This figure is a view corresponding to that of
FIG. 57, illustrating a power-mode complex control map which is a
combination of the step-variable-shifting control map of FIG. 58,
the drive-power-source selection control map of FIG. 59 and the
switching control map of FIG. 56.
[0293] [FIG. 61] This figure is a view illustrating an example of a
stored engine-fuel-economy map, together with iso-torque curves
(one-dot chain lines) and an iso-fuel-economy curve (solid line),
in a two-dimensional coordinate system defined by an axis of an
engine speed and an axis of an engine torque, the
engine-fuel-economy map being used to determine a speed ratio of
the automatic shifting portion and a speed ratio of the
differential portion, which speed ratios give a target speed of the
engine.
[0294] [FIG. 62] This figure is a flow chart illustrating a control
operation of the electronic control device to control the hybrid
drive system in the embodiment of FIG. 52.
[0295] [FIG. 63] This figure is a functional block diagram for
explaining major control functions performed by an electronic
control device in another embodiment of the invention, which is
another modification of the embodiment of FIG. 6.
[0296] [FIG. 64] This figure is a view illustrating an example of a
fuel-economy map used to calculate fuel economy.
[0297] [FIG. 65] This figure is a view illustrating an example of
power transmission efficiency values in the continuously-variable
and step-variable shifting states, which change with the vehicle
speed.
[0298] [FIG. 66] This figure is a flow chart illustrating a major
control operation of the electronic control device in the
embodiment of FIG. 63.
[0299] [FIG. 67] This figure is a functional block diagram for
explaining major control functions performed by an electronic
control device in another embodiment of the invention, which is a
modification of the embodiment of FIG. 63.
[0300] [FIG. 68] This figure is a view indicating a relationship
used by switching control means in the embodiment of FIG. 67.
[0301] [FIG. 69] This figure is a functional block diagram for
explaining major control functions performed by an electronic
control device in another embodiment of the invention, which is
another modification of the embodiment of FIG. 63.
[0302] [FIG. 70] This figure is a view indicating a relationship
used by switching control means in the embodiment of FIG. 69.
[0303] [FIG. 71] This figure is a functional block diagram for
explaining major control functions performed by an electronic
control device in another embodiment of the invention, which is
another modification of the embodiment of FIG. 6.
[0304] [FIG. 72] This figure is a view illustrating one example of
a stored optimum-fuel-economy map used to calculate efficiency
.eta.M1 of a first electric motor M1, which is used to calculate an
amount of fuel consumption of the vehicle.
[0305] [FIG. 74] This figure is a view illustrating one example of
a stored optimum-fuel-economy map used to calculate efficiency
.eta.M2 of a second electric motor M2, which is used to calculate
the amount of fuel consumption of the vehicle.
[0306] [FIG. 74] This figure is a view indicating a shifting map
used in the step-variable shifting state when the differential
portion (continuously-variable shifting portion) is not placed in
the continuously-variable shifting state.
[0307] [FIG. 75] This figure is a flow chart illustrating a major
control operation performed by the electronic control device in the
embodiment of FIG. 71, that is, an operation to control the speed
ratio of the step-variable shifting portion during deceleration of
the vehicle.
[0308] [FIG. 76] This figure is a flow chart for explaining in
detail a speed-ratio calculating routine in the control operation
of FIG. 75.
[0309] [FIG. 77] This figure is a schematic view for explaining an
arrangement of a drive system of a hybrid vehicle according to one
embodiment of the present invention.
[0310] [FIG. 78] This figure is a table indicating shifting actions
of the drive system of the hybrid vehicle of the embodiment of FIG.
77 operable in a continuously variable shifting state or a
step-variable shifting state, in relation to different combinations
of operating states of hydraulically operated frictional coupling
devices to effect the respective shifting actions.
[0311] [FIG. 79] This figure is a collinear chart showing relative
rotating speeds of rotary elements of the drive system of the
hybrid vehicle of the embodiment of FIG. 77 operated in the
step-variable shifting state, in different gear positions of the
drive system.
[0312] [FIG. 80] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0313] [FIG. 81] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0314] [FIG. 82] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0315] [FIG. 83] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0316] [FIG. 84] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0317] [FIG. 85] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0318] [FIG. 86] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0319] [FIG. 87] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0320] [FIG. 88] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0321] [FIG. 89] This figure is an example of a collinear chart for
explaining an shifting operation of the drive system of the
embodiment of FIG. 88.
[0322] [FIG. 90] This figure is a table indicating gear positions
of the drive system and combinations of hydraulically operated
frictional coupling devices to be engaged to establish the
respective gear positions.
[0323] [FIG. 91] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0324] [FIG. 92] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0325] [FIG. 93] This figure is a table indicating shifting actions
of the drive system of the hybrid vehicle of the embodiment of FIG.
92 operable in a continuously variable shifting state or a
step-variable shifting state, in relation to different combinations
of operating states of hydraulically operated frictional coupling
devices to effect the respective shifting actions.
[0326] [FIG. 94] This figure is a collinear chart showing relative
rotating speeds of rotary elements of the drive system of the
hybrid vehicle of the embodiment of FIG. 92 operated in the
step-variable shifting state, in different gear positions of the
drive system.
[0327] [FIG. 95] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0328] [FIG. 96] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0329] [FIG. 97] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0330] [FIG. 98] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0331] [FIG. 99] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0332] [FIG. 100] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0333] [FIG. 101] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0334] [FIG. 102] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0335] [FIG. 103] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0336] [FIG. 104] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0337] [FIG. 105] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0338] [FIG. 1061] This figure is a schematic view for explaining
an arrangement of a hybrid vehicle drive system according to
another embodiment of this invention.
[0339] [FIG. 107] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
[0340] [FIG. 1081] This figure is a schematic view for explaining
an arrangement of a hybrid vehicle drive system according to
another embodiment of this invention.
[0341] [FIG. 109] This figure is a schematic view for explaining an
arrangement of a hybrid vehicle drive system according to another
embodiment of this invention.
NOMENCLATURE OF ELEMENTS
[0342] 8: Engine [0343] 10, 70, 80, 92, 110, 120, 130, 140, 150,
160, 170, 180, 190, 200, 210, 220: Drive system (Switchable type
transmission mechanism) [0344] 11, 81, 93: Differential portion
(Switchable type shifting portion) [0345] 12: Transmission casing
(Stationary member) [0346] 14: Input shaft [0347] 16, 84, 94: Power
distributing mechanism (Differential gear device) [0348] 18: Power
transmitting member (Output shaft) [0349] 20, 72, 86, 96, 112, 172:
Step-variable automatic transmission (Step-variable automatic
transmission portion; Step-variable shifting portion; Automatic
transmission portion) [0350] 22: Output shaft (Output rotary
member) [0351] 24: First planetary gear set (Single-pinion type
planetary gear set) [0352] 26: Second planetary gear set [0353] 28:
Third planetary gear set [0354] 30: Fourth planetary gear set
[0355] 32: Differential drive gear (Output rotary member) [0356]
34: Differential ring gear [0357] 36: Differential gear device
[0358] 37: Drive axle [0359] 38: Drive wheels [0360] 40: Electronic
control device [0361] 42: Hydraulic control unit [0362] 44: Seesaw
switch [0363] 46: Manually operable shifting device [0364] 48:
Shift lever [0365] 50: Switching control means [0366] 52: HB
control means [0367] 54: Step-variable shifting control means
[0368] 56: Shifting-map memory means [0369] 58: Inverter [0370] 60:
Electric-energy storage device [0371] 62: High-speed-running
determining means [0372] 64: High-output-running determining means
[0373] 66: Electric-path-function diagnosing means [0374] 67:
Shift-position determining means [0375] 68: High-speed-gear
determining means [0376] 82: First planetary gear set
(Double-pinion type planetary gear set) [0377] 84: Second planetary
gear set [0378] 90: Third planetary gear set [0379] 98: Second
planetary gear set [0380] 100: Third planetary gear set [0381] M1:
First electric motor [0382] M2: Second electric motor [0383] C0:
Switching clutch (Differential-state switching device) [0384] B0:
Switching brake (Differential-state switching device) [0385] CG:
Counter gear pair (Power transmitting member) [0386] 152:
Step-variable shifting control means [0387] 156: Hybrid control
means (Drive-power-source selection control means) [0388] 159:
Switching control means [0389] 162, 171: Step-variable-shifting
control map [0390] 164, 172: Drive-power-source selection control
map [0391] 166, 176: Switching control map [0392] 280: Fuel-economy
curve selecting means [0393] 282: Fuel-economy curve memory means
[0394] 284: Power-transmitting-efficiency calculating means [0395]
286: Fuel-consumption-ratio calculating means [0396] 288:
Shifting-state fuel-economy calculating means [0397] 290: Fuel
consumption sensor [0398] 380: Continuously-variable-shifting-run
determining means [0399] 386: Continuously-variable-shifting-run
speed-ratio control means [0400] 388: Target-engine-speed
calculating means [0401] 390: Two-speed-ratios determining means
[0402] 410, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570: Drive
system [0403] 420, 492, 512, 422, 532, 542, 552, 562: Step-variable
automatic transmission [0404] 426, 494, 514, 524, 534, 544, 554,
564: Second planetary gear set [0405] 428, 496, 516, 526, 536, 546,
556, 566: Third planetary gear set [0406] 610, 680, 690, 700, 710,
720, 730, 740, 750, 760, 770, 780, 790, 800, 810, 820; Drive system
[0407] 620, 692, 712, 732, 742, 752, 762, 772, 782, 792, 802, 812,
822: Step-variable automatic transmission [0408] 626, 694, 714,
734, 744, 754, 764, 774, 784, 794, 804, 814, 824: Second planetary
gear set [0409] 628, 696, 716, 736, 746, 756, 766, 776, 786, 796,
806, 816, 826: Third planetary gear set
BEST MODE FOR CARRYING OUT THE INVENTION
[0410] Referring to the drawings, there will be described in detail
the embodiments of the present invention.
Embodiment 1
[0411] FIG. 1 is a schematic view explaining a drive system 10 for
a hybrid vehicle, which includes a control device according to one
embodiment of this invention. The drive system 10 shown in FIG. 1
includes: an input rotary member in the form of an input shaft 14
disposed on a common axis in a transmission casing 12 (hereinafter
abbreviated as "casing 12") functioning as a stationary member
attached to a body of the vehicle; a differential mechanism in the
form of a power distributing mechanism 16 connected to the input
shaft 14 either directly, or indirectly via a pulsation absorbing
damper (vibration damping device) not shown; a step-variable or
multiple-step automatic transmission 20 interposed between and
connected in series via a power transmitting member 18 (power
transmitting shaft) to the power distributing mechanism 16 and an
output shaft 22; and an output rotary member in the form of the
above-indicated output shaft 22 connected to the automatic
transmission 20. The input shaft 12, power distributing mechanism
16, automatic transmission 20 and output shaft 22 are connected in
series with each other. This drive system 10 is suitably used for a
transverse FR vehicle (front-engine, rear-drive vehicle), and is
disposed between a drive power source in the form of an engine 8
and a pair of drive wheels 38, to transmit a vehicle drive force to
the pair of drive wheels 38 through a differential gear device 36
(final speed reduction gear) and a pair of drive axles, as shown in
FIG. 7. It is noted that a lower half of the drive system 10, which
is constructed symmetrically with respect to its axis, is omitted
in FIG. 1. This is also true in each of the other embodiments
described below.
[0412] The drive system 10 has a differential portion 11 also
functioning as a switchable type shifting portion, which is
operable in a two-step-variable shifting state and an electrically
established continuously-variable shifting state. This differential
portion 11 includes: a first electric motor M1; the above-described
power distributing mechanism 16 functioning as the differential
mechanism operable to mechanically distribute the output of the
engine 8 transmitted to the input shaft 14, to the first electric
motor M1 and the power transmitting member 18; and a second
electric motor M2 rotatable with the power transmitting member
18.
[0413] The power distributing mechanism 16 is a mechanical device
arranged to mechanically synthesize or distribute the output of the
engine 8 received by the input shaft 14, that is, to distribute the
output of the engine 8 to the first electric motor M1 and the power
transmitting member 18, or to synthesize the output of the engine 8
and the output of the first electric motor M1 and transmit a sum of
these outputs to the power transmitting member 18. While the second
electric motor M2 is arranged to be rotated with the power
transmitting member 18 in the present embodiment, the second
electric motor M2 may be disposed at any desired position between
the power transmitting member 18 and the output shaft 22. In the
present embodiment, each of the first electric motor M1 and the
second electric motor M2 is a so-called motor/generator also
functioning as an electric generator. The first electric motor M1
should function at least as an electric generator operable to
generate an electric energy while generating a reaction force, and
the second electric motor M2 should function at least as an
electric motor operable to generate a vehicle drive force. Both of
the first and second electric motors M1, M2 cooperate with the
engine 8 to function as a drive power source for driving the
vehicle.
[0414] The power distributing mechanism 16 includes, as major
components, a first planetary gear set 24 of single pinion type
having a gear ratio .rho.1 of about 0.418, for example, a switching
clutch C0 and a switching brake B1. The first planetary gear set 24
has rotary elements consisting of: a first sun gear S1, a first
planetary gear P1; a first carrier CA1 supporting the first
planetary gear P1 such that the first planetary gear P1 is
rotatable about its axis and about the axis of the first sun gear
S1; and a first ring gear R1 meshing with the first sun gear S1
through the first planetary gear P1. Where the numbers of teeth of
the first sun gear S1 and the first ring gear R1 are represented by
ZS1 and ZR1, respectively, the above-indicated gear ratio .rho.1 is
represented by ZS1/ZR1.
[0415] In the power distributing mechanism 16, the first carrier
CA1 is connected to the input shaft 14, that is, to the engine 8,
and the first sun gear S1 is connected to the first electric motor
M1, while the first ring gear R1 is connected to the power
transmitting member 18. The switching brake B0 is disposed between
the first sun gear S1 and the transmission casing 12, and the
switching clutch C0 is disposed between the first sun gear S1 and
the first carrier CA1. When the switching clutch C0 and brake B0
are released, the power distributing mechanism 16 is placed in a
differential state in which the first sun gear S1, first carrier
CA1 and first ring gear R1 are rotatable relative to each other, so
as to perform a differential function, so that the output of the
engine 8 is distributed to the first electric motor M1 and the
power transmitting member 18, whereby a portion of the output of
the engine 8 is used to drive the first electric motor M1 to
generate an electric energy which is stored or used to drive the
second electric motor M2. Accordingly, the power distributing
mechanism 16 is placed in the continuously-variable shifting state
(electrically established CVT state), in which the rotating speed
of the power transmitting member 18 is continuously variable,
irrespective of the rotating speed of the engine 8, namely, in the
differential state in which a speed ratio .gamma.0 (rotating speed
of the input shaft 14/rotating speed of the power transmitting
member 18) of the power distributing mechanism 16 is electrically
changed from a minimum value .gamma.0min to a maximum value
.gamma.0max, for instance, in the continuously-variable shifting
state in which the power distributing mechanism 16 functions as an
electrically controlled continuously variable transmission the
speed ratio .gamma.0 of which is continuously variable from the
minimum value .gamma.0min to the maximum value .gamma.0max.
[0416] When the switching clutch C0 or brake B0 is engaged during
running of the vehicle with the output of the engine 8 while the
power distributing mechanism 16 is placed in the
continuously-variable shifting state, the mechanism 16 is brought
into a non-differential state or locked state in which the
differential function is not available. Described in detail, when
the switching clutch C0 is engaged, the first sun gear S1 and the
first carrier CA1 are connected together, so that the power
distributing mechanism 16 is placed in the locked state or
non-differential state in which the three rotary elements of the
first planetary gear set 24 consisting of the first sun gear S1,
first carrier CA1 and first ring gear R1 are rotatable as a unit,
and so that the switchable type shifting portion 11 is also placed
in a non-differential state. In this non-differential state, the
rotating speed of the engine 8 and the rotating speed of the power
transmitting member 18 are made equal to each other, so that the
power distributing mechanism 16 is placed in a fixed-speed-ratio
shifting state or step-variable shifting state in which the
mechanism 16 functions as a transmission having a fixed speed ratio
.gamma.0 equal to 1. When the switching brake B0 is engaged in
place of the switching clutch C0, the first sun gear S1 is fixed to
the transmission casing 12, so that the power distributing
mechanism 16 is placed in the locked or non-differential state in
which the first sun gear S1 is not rotatable, while the switchable
type shifting portion 11 is also placed in the non-differential
state. Since the rotating speed of the first ring gear R1 is made
higher than that of the first carrier CA1, the power distributing
mechanism 16 is placed in the step-variable shifting state in which
the mechanism 16 functions as a speed-increasing transmission
having a fixed speed ratio .gamma.0 smaller than 1, for example,
about 0.7.
[0417] In the present embodiment described above, the switching
clutch C0 and brake B0 function as a differential-state switching
device operable to selectively place the power distributing
mechanism 16 in the differential state (continuously-variable
shifting state or non-locked state) in which the mechanism 16
functions as an electrically controlled continuously variable
transmission the speed ratio of which is continuously variable, and
in the non-differential or locked state in which the mechanism 16
does not function as the electrically controlled continuously
variable transmission. Namely, the switching clutch C0 and brake B0
function as the differential-state switching device operable to
switch the power distributing mechanism 16 between a differential
state, and a fixed-speed-ratio shifting state in which the
mechanism 16 functions as a transmission having a single gear
position with one speed ratio or a plurality of gear positions with
respective speed ratios. It is also noted that the differential
portion 11 consisting of the first electric motor M1, the second
electric motor M2 and the power distributing mechanism 16 cooperate
to function as a shifting-state switchable type shifting portion
(mechanism) which is switchable between a continuously-variable
shifting state or state in which the shifting portion 11 is
operated as an electrically controlled continuously variable
transmission the speed ratio of which is continuously variable, and
a locked state in which the shifting portion 11 does not function
as the electrically controlled continuously variable transmission
but functions as a transmission having a single gear position with
one speed ratio or a plurality of gear positions with respective
speed ratios. The power distributing mechanism 16 described above
functions as a switchable type differential (planetary) gear device
switchable between a locked state and a non-locked state.
[0418] In other words, the above-described switching clutch C0 and
switching brake B0 used in the present embodiment function as a
differential-state switching device operable to selectively place
the power distributing mechanism 16 in the differential or
non-locked state and in the non-differential or locked state.
Namely, the switching clutch C0 and brake B0 function as a
differential-state switching device operable to switch the
switchable type shifting portion 11 between a non-locked state
(differential state) or an electrically established
continuously-variable shifting state, and a locked state
(non-differential state) or a fixed-speed-ratio shifting state. In
the non-locked state, the shifting portion 11 functions as an
electrically controlled differential device. In the electrically
established continuously-variable shifting state, the shifting
portion 11 functions as an electrically controlled continuously
variable transmission. In the locked state, the shifting portion 11
does not function as the electrically controlled differential
device. In the fixed-speed-ratio shifting state, the shifting
portion 11 does not function as an electrically controlled
continuously variable transmission, but functions as a transmission
having a single gear position with one speed ratio or a plurality
of gear positions with respective speed ratios. The switchable type
shifting portion 11, which includes the power distributing
mechanism 16 provided with the switching clutch C0 and brake B0,
functions as a switchable type differential gear device switchable
between a locked state and a non-locked state.
[0419] The automatic transmission 20 includes a single-pinion type
second planetary gear set 26, a single-pinion type third planetary
gear set 28 and a single-pinion type fourth planetary gear set 30.
The second planetary gear set 26 has: a second sun gear S2; a
second planetary gear P2; a second carrier CA2 supporting the
second planetary gear P2 such that the second planetary gear P2 is
rotatable about its axis and about the axis of the second sun gear
S2; and a second ring gear R2 meshing with the second sun gear S2
through the second planetary gear P2. For example, the second
planetary gear set 26 has a gear ratio .rho.2 of about 0.562. The
third planetary gear set 28 has: a third sun gear S3; a third
planetary gear P3; a third carrier CA3 supporting the third
planetary gear P3 such that the third planetary gear P3 is
rotatable about its axis and about the axis of the third sun gear
S3; and a third ring gear R3 meshing with the third sun gear S3
through the third planetary gear P3. For example, the third
planetary gear set 28 has a gear ratio .rho.3 of about 0.425. The
fourth planetary gear set 30 has: a fourth sun gear S4; a fourth
planetary gear P4; a fourth carrier CA4 supporting the fourth
planetary gear P4 such that the fourth planetary gear P4 is
rotatable about its axis and about the axis of the fourth sun gear
S4; and a fourth ring gear R4 meshing with the fourth sun gear S4
through the fourth planetary gear P4. For example, the fourth
planetary gear set 30 has a gear ratio .rho.4 of about 0.421. Where
the numbers of teeth of the second sun gear S2, second ring gear
R2, third sun gear S3, third ring gear R3, fourth sun gear S4 and
fourth ring gear R4 are represented by ZS2, ZR2, ZS3, ZR3, ZS4 and
ZR4, respectively, the above-indicated gear ratios .rho.2, .rho.3
and .rho.4 are represented by ZS2/ZR2. ZS3/ZR3, and ZS4/ZR4,
respectively.
[0420] In the automatic transmission 20, the second sun gear S2 and
the third sun gear S3 are integrally fixed to each other as a unit,
selectively connected to the power transmitting member 18 through a
second clutch C2, and selectively fixed to the transmission casing
12 through a first brake B1. The fourth ring gear R4 is selectively
fixed to the transmission casing 12 through a third brake B3, and
the second ring gear R2, third carrier CA3 and fourth carrier CA4
are integrally fixed to each other and fixed to the output shaft
22. The third ring gear R3 and the fourth sun gear S4 are
integrally fixed to each other and selectively connected to the
power transmitting member 18 through a first clutch C1.
[0421] The above-described switching clutch C0, first clutch C1,
second clutch C2, switching brake B0, first brake B1, second brake
B2 and third brake B3 are hydraulically operated frictional
coupling devices used in a conventional vehicular automatic
transmission. Each of these frictional coupling devices is
constituted by a wet-type multiple-disc clutch including a
plurality of friction plates which are superposed on each other and
which are forced against each other by a hydraulic actuator, or a
band brake including a rotary drum and one band or two bands which
is/are wound on the outer circumferential surface of the rotary
drum and tightened at one end by a hydraulic actuator. Each of the
clutches C0-C2 and brakes B0-B3 is selectively engaged for
connecting two members between which each clutch or brake is
interposed.
[0422] In the drive system 10 constructed as described above, one
of a first-gear position (first-speed position) through a
fifth-gear position (fifth-speed position), a reverse-gear position
(rear-drive position) and a neural position is selectively
established by engaging actions of a corresponding combination of
the frictional coupling devices selected from the above-described
switching clutch C0, first clutch C1, second clutch C2, switching
brake B0, first brake B1, second brake B2 and third brake B3, as
indicated in the table of FIG. 2. Those positions have respective
speed ratios .gamma. (input shaft speed N.sub.IN/output shaft speed
N.sub.OUT) which change as geometric series. In particular, it is
noted that the power distributing mechanism 16 provided with the
switching clutch C0 and brake B0 can be selectively placed by
engagement of the switching clutch C0 or switching brake B0, in the
fixed-speed-ratio shifting state in which the mechanism 16 is
operable as a transmission having a single gear position with one
speed ratio or a plurality of gear positions with respective speed
ratios, as well as in the continuously-variable shifting state in
which the mechanism 16 is operable as a continuously variable
transmission, as described above. In the present drive system 10,
therefore, a step-variable transmission is constituted by the
automatic transmission 20, and the power distributing mechanism 16
which is placed in the fixed-speed-ratio shifting state by
engagement of the switching clutch C0 or switching brake B0.
Further, a continuously variable transmission is constituted by the
automatic transmission 20, and the power distributing mechanism 16
which is placed in the continuously-variable shifting state, with
none of the switching clutch C0 and brake B0 being engaged. In
other words, the transmission system (drive system) 10 is switched
to the step-variable shifting state by engaging one of the
switching clutch C0 and switching brake B0, and switched to the
continuously-variable shifting state by releasing both of the
switching clutch C0 and brake B0. Namely, the drive system 10
functions as a transmission mechanism of switchable type switchable
between the continuously-variable shifting state in which the drive
system 10 is operable as an electrically controlled continuously
variable transmission, and the step-variable shifting state in
which the drive system 10 operable as the step-variable
transmission. The differential portion (switchable type shifting
portion) 11 is also considered to be a transmission switchable
between the step-variable shifting state and the
continuously-variable shifting state.
[0423] Where the drive system 10 functions as the step-variable
transmission, for example, the first-gear position having the
highest speed ratio .gamma.1 of about 3.357, for example, is
established by engaging actions of the switching clutch C0, first
clutch C1 and third brake B3, and the second-gear position having
the speed ratio .gamma.2 of about 2.180, for example, which is
lower than the speed ratio .gamma.1, is established by engaging
actions of the switching clutch C0, first clutch C1 and second
brake B2, as indicated in FIG. 2. Further, the third-gear position
having the speed ratio .gamma.3 of about 1.427, for example, which
is lower than the speed ratio .gamma.2, is established by engaging
actions of the switching clutch C0, first clutch C1 and first brake
B1, and the fourth-gear position having the speed ratio .gamma.4 of
about 1.000, for example, which is lower than the speed ratio
.gamma.3, is established by engaging actions of the switching
clutch C0, first clutch C1 and second clutch C2. The fifth-gear
position having the speed ratio .gamma.5 of about 0.705, for
example, which is smaller than the speed ratio .gamma.4, is
established by engaging actions of the first clutch C1, second
clutch C2 and switching brake B0. Further, the reverse-gear
position having the speed ratio .gamma.R of about 3.209, for
example, which is intermediate between the speed ratios .gamma.1
and .gamma.2, is established by engaging actions of the second
clutch C2 and the third brake B3. The neutral position N is
established by engaging only the switching clutch C0.
[0424] Where the drive system 10 functions as the
continuously-variable transmission, on the other hand, the
switching clutch C0 and the switching brake B0 are both released,
as indicated in FIG. 2, so that the power distributing mechanism 16
functions as the continuously variable transmission, while the
automatic transmission 10 connected in series to the power
distributing mechanism 16 functions as the step-variable
transmission, whereby the speed of the rotary motion transmitted to
the automatic transmission 20 placed in one of the first-gear,
second-gear, third-gear and fourth-gear positions, namely, the
rotating speed of the power transmitting member 18 is continuously
changed, so that the speed ratio of the drive system when the
automatic transmission 20 is placed in one of those gear positions
is continuously variable over a predetermined range. Accordingly,
the speed ratio of the automatic transmission 20 is continuously
variable across the adjacent gear positions, whereby the overall
speed ratio .gamma.T of the drive system 10 is continuously
variable.
[0425] The collinear chart of FIG. 3 indicates, by straight lines,
a relationship among the rotating speeds of the rotary elements in
each of the gear positions of the drive system 10, which is
constituted by the differential portion 11 or power distributing
mechanism 16 functioning as the continuously-variable shifting
portion or first shifting portion, and the automatic transmission
20 functioning as the step-variable shifting portion or second
shifting portion. The collinear chart of FIG. 3 is a rectangular
two-dimensional coordinate system in which the gear ratios .rho. of
the planetary gear sets 24, 26, 28, 30 are taken along the
horizontal axis, while the relative rotating speeds of the rotary
elements are taken along the vertical axis. A lower one of three
horizontal lines X1, X2, XG, that is, the horizontal line X1
indicates the rotating speed of 0, while an upper one of the three
horizontal lines, that is, the horizontal line X2 indicates the
rotating speed of 1.0, that is, an operating speed N.sub.E of the
engine 8 connected to the input shaft 14. The horizontal line XG
indicates the rotating speed of the power transmitting member
18.
[0426] Three vertical lines Y1, Y2 and Y3 corresponding to the
power distributing mechanism 16 which principally constitutes the
differential portion 11 respectively represent the relative
rotating speeds of a second rotary element (second element) RE2 in
the form of the first sun gear S1, a first rotary element (first
element) RE1 in the form of the first carrier CA1, and a third
rotary element (third element) RE3 in the form of the first ring
gear R1. The distances between the adjacent ones of the vertical
lines Y1, Y2 and Y3 are determined by the gear ratio .rho.1 of the
first planetary gear set 24. That is, the distance between the
vertical lines Y1 and Y2 corresponds to "1", while the distance
between the vertical lines Y2 and Y3 corresponds to the gear ratio
.rho.1. Further, five vertical lines Y4, Y5, Y6, Y7 and Y8
corresponding to the automatic transmission 20 respectively
represent the relative rotating speeds of a fourth rotary element
(fourth element) RE4 in the form of the second and third sun gears
S2, S3 integrally fixed to each other, a fifth rotary element
(fifth element) RE5 in the form of the second carrier CA2, a sixth
rotary element (sixth element) RE6 in the form of the fourth ring
gear R4, a seventh rotary element (seventh element) RE7 in the form
of the second ring gear R2 and third and fourth carriers CA3, CA4
that are integrally fixed to each other, and an eighth rotary
element (eighth element) RE8 in the form of the third ring gear R3
and fourth sun gear S4 integrally fixed to each other. The
distances between the adjacent ones of the vertical lines Y4-Y8 are
determined by the gear ratios .rho.2, .rho.3 and .rho.4 of the
second, third and fourth planetary gear sets 26, 28, 30. That is,
the distances between the sun gear and carrier of each of the
second, third and fourth planetary gear sets 26, 28, 30 corresponds
to "1", while the distances between the carrier and ring gear of
each of those planetary gear sets 26 28, 30 corresponds to the gear
ratio .rho..
[0427] Referring to the collinear chart of FIG. 3, the power
distributing mechanism (continuously variable shifting portion) 16
or differential portion 11 of the drive system (transmission
mechanism) 10 is arranged such that the first rotary element RE1
(first carrier CA1), which is one of the three rotary elements of
the first planetary gear set 24, is integrally fixed to the input
shaft 14 and selectively connected to another rotary element in the
form of the first sun gear S1 through the switching clutch C0, and
this rotary element RE2 (first sun gear S1) is fixed to the first
electric motor M1 and selectively fixed to the transmission casing
12 through the switching brake B0, while the third rotary element
RE3 (first ring gear R1) is fixed to the power transmitting member
18 and the second electric motor M2, so that a rotary motion of the
input shaft 14 is transmitted to the automatic transmission
(step-variable transmission) 20 through the power transmitting
member 18. A relationship between the rotating speeds of the first
sun gear S1 and the first ring gear R1 is represented by an
inclined straight line L0 which passes a point of intersection
between the lines Y2 and X2. When the power distributing mechanism
16 is brought into the continuously-variable shifting state by
releasing actions of the switching clutch C0 and brake B0, for
instance, the rotating speed of the first sun gear S1 represented
by a point of intersection between the line L0 and the vertical
line Y1 is raised or lowered by controlling the reaction force
generated by an operation of the first electric motor M1 to
generate an electric energy, so that the rotating speed of the
first ring gear R1 represented by a point of intersection between
the line L0 and the vertical line Y3 is lowered or raised. When the
switching clutch C0 is engaged, the first sun gear S1 and the first
carrier CA1 are connected to each other, and the above-indicated
three rotary elements are rotated as a unit, so that the line L0 is
aligned with the horizontal line X2, so that the power transmitting
member 18 is rotated at a speed equal to the engine speed NE. When
the switching brake B0 is engaged, on the other hand, the rotation
of the first sun gear S1 is stopped, the line L0 is inclined in the
state indicated in FIG. 3, so that the rotating speed of the first
ring gear R1, that is, the rotation of the power transmitting
member 18 represented by a point of intersection between the lines
L0 and Y3 is made higher than the engine speed NE and transmitted
to the automatic transmission 20.
[0428] FIGS. 4 and 5 correspond to a part of the collinear chart of
FIG. 3 which shows the power distributing mechanism 16. FIG. 4
shows an example of an operating state of the power distributing
mechanism 16 placed in the continuously-variable shifting state
with the switching clutch C0 and the switching brake B0 held in the
released state. The rotating speed of the first sun gear S1
represented by the point of intersection between the straight line
L0 and vertical line Y1 is raised or lowered by controlling the
reaction force generated by an operation of the first electric
motor M1 to generate an electric energy, so that the rotating speed
of the first ring gear R1 represented by the point of intersection
between the lines L0 and Y3 is lowered or raised.
[0429] FIG. 5 shows an example of an operating state of the power
distributing mechanism 16 placed in the fixed-speed-ratio shifting
state (step-variable shifting state) with the switching clutch C0
held in the engaged state. When the first sun gear S1 and the first
carrier CA1 are connected to each other in this fixed-speed-ratio
shifting state, the three rotary elements indicated above are
rotated as a unit, so that the line L0 is aligned with the
horizontal line X2, whereby the power transmitting member 18 is
rotated at a speed equal to the engine speed N.sub.E. When the
switching brake B0 is engaged, on the other hand, the rotation of
the power transmitting member 18 is stopped, and the power
distributing mechanism 16 is placed in the non-differential state
in which the mechanism 16 functions as a speed-increasing device,
so that the straight line L0 is inclined in the state indicated in
FIG. 3, whereby the rotating speed of the first ring gear R1, that
is, the rotation of the power transmitting member 18 represented by
a point of intersection between the straight line L0 and vertical
line Y3 is made higher than the engine speed N.sub.E and
transmitted to the automatic transmission 20.
[0430] In the automatic transmission 20, the fourth rotary element
RE4 is selectively connected to the power transmitting member 18
through the second clutch C2, and selectively fixed to the casing
12 through the first brake B1, and the fifth rotary element RE5 is
selectively fixed to the casing 12 through the second brake B2,
while the sixth rotary element RE6 is selectively fixed to the
casing 12 through the third brake B3. The seventh rotary element
RE7 is fixed to the output shaft 22, while the eighth rotary
element RE8 is selectively connected to the power transmitting
member 18 through the first clutch C1.
[0431] When the first clutch C1 and the third brake B3 are engaged,
the automatic transmission 20 is placed in the first-speed
position. The rotating speed of the output shaft 22 in the
first-speed position is represented by a point of intersection
between the vertical line Y7 indicative of the rotating speed of
the seventh rotary element RE7 fixed to the output shaft 22 and an
inclined straight line L1 which passes a point of intersection
between the vertical line Y8 indicative of the rotating speed of
the eighth rotary element RE8 and the horizontal line X2, and a
point of intersection between the vertical line Y6 indicative of
the rotating speed of the sixth rotary element RE6 and the
horizontal line X1. Similarly, the rotating speed of the output
shaft 22 in the second-speed position established by the engaging
actions of the first clutch C1 and second brake B2 is represented
by a point of intersection between an inclined straight line L2
determined by those engaging actions and the vertical line Y7
indicative of the rotating speed of the seventh rotary element RE7
fixed to the output shaft 22. The rotating speed of the output
shaft 22 in the third-speed position established by the engaging
actions of the first clutch C1 and first brake B1 is represented by
a point of intersection between an inclined straight line L3
determined by those engaging actions and the vertical line Y7
indicative of the rotating speed of the seventh rotary element RE7
fixed to the output shaft 22. The rotating speed of the output
shaft 22 in the fourth-speed position established by the engaging
actions of the first clutch C1 and second clutch C2 is represented
by a point of intersection between a horizontal line L4 determined
by those engaging actions and the vertical line Y7 indicative of
the rotating speed of the seventh rotary element RE7 fixed to the
output shaft 22. In the first-speed through fourth-speed positions
in which the switching clutch C0 is placed in the engaged state,
the eighth rotary element RE8 is rotated at the same speed as the
engine speed N.sub.E, with the drive force received from the power
distributing mechanism 16. When the switching clutch B0 is engaged
in place of the switching clutch C0, the eighth rotary element RE8
is rotated at a speed higher than the engine speed N.sub.E, with
the drive force received from the power distributing mechanism 16.
The rotating speed of the output shaft 22 in the fifth-speed
position established by the engaging actions of the first clutch
C1, second clutch C2 and switching brake B0 is represented by a
point of intersection between a horizontal line L5 determined by
those engaging actions and the vertical line Y7 indicative of the
rotating speed of the seventh rotary element RE7 fixed to the
output shaft 22. The rotating speed of the output shaft 22 in the
reverse-gear position R established by the second clutch C2 and
third brake B3 is represented by a point of intersection between an
inclined straight line LR determined by those engaging actions and
the vertical line Y7 indicative of the rotating speed of the
seventh rotary element RE7 fixed to the output shaft 22.
[0432] FIG. 6 illustrates signals received by an electronic control
device 40 provided to control the drive system 10, and signals
generated by the electronic control device 40. This electronic
control device 40 includes a so-called microcomputer incorporating
a CPU, a ROM, a RAM and an input/output interface, and is arranged
to process the signals according to programs stored in the ROM
while utilizing a temporary data storage function of the ROM, to
implement hybrid drive controls of the engine 8 and electric motors
M1 and M2, and drive controls such as shifting controls of the
automatic transmission 20.
[0433] The electronic control device 40 is arranged to receive,
from various sensors and switches shown in FIG. 6, various signals
such as: a signal indicative of a temperature of cooling water of
the engine; a signal indicative of a selected operating position of
a shift lever; a signal indicative of the operating speed N.sub.E
of the engine 8; a signal indicative of a value indicating a
selected group of forward-drive positions of the drive system; a
signal indicative of an M mode (motor drive mode); a signal
indicative of an operated state of an air conditioner; a signal
indicative of a vehicle speed corresponding to the rotating speed
of the output shaft 22; a signal indicative of a temperature of a
working oil of the automatic transmission 20; a signal indicative
of an operated state of a side brake; a signal indicative of an
operated state of a foot brake; a signal indicative of a
temperature of a catalyst; a signal indicative of an angle of
operation of an accelerator pedal; a signal indicative of an angle
of a cam; a signal indicative of the selection of a snow drive
mode; a signal indicative of a longitudinal acceleration value of
the vehicle; a signal indicative of the selection of an
auto-cruising drive mode; a signal indicative of a weight of the
vehicle; signals indicative of speeds of the drive wheels of the
vehicle; a signal indicative of an operating state of a
step-variable shifting switch provided to place the power
distributing mechanism 16 in the fixed-speed-ratio shifting state
in which the drive system 10 functions as a step-variable
transmission; a signal indicative of a continuously-variable
shifting switch provided to place the power distributing mechanism
16 in the continuously variable-shifting state in which the drive
system 10 functions as the continuously variable transmission; a
signal indicative of a rotating speed N.sub.M1 of the first
electric motor M1; and a signal indicative of a rotating speed
N.sub.M2 of the second electric motor M2. The electronic control
device 40 is further arranged to generate various signals such as:
a signal to drive a throttle actuator for controlling an angle of
opening of a throttle valve; a signal to adjust a pressure of a
supercharger; a signal to operate the electric air conditioner; a
signal for controlling an ignition timing of the engine 8; signals
to operate the electric motors M1 and M2; a signal to operate a
shift-range indicator for indicating the selected operating
position of the shift lever; a signal to operate a gear-ratio
indicator for indicating the gear ratio; a signal to operate a
snow-mode indicator for indicating the selection of the snow drive
mode; a signal to operate an ABS actuator for anti-lock braking of
the wheels; a signal to operate an M-mode indicator for indicating
the selection of the M-mode; signals to operate solenoid-operated
valves incorporated in a hydraulic control unit 42 provided to
control the hydraulic actuators of the hydraulically operated
frictional coupling devices of the power distributing mechanism 16
and the automatic transmission 20; a signal to operate an electric
oil pump used as a hydraulic pressure source for the hydraulic
control unit 42; a signal to drive an electric heater; and a signal
to be applied to a cruise-control computer.
[0434] FIG. 7 is a functional block diagram for explaining a method
of controlling the drive system 10, that is, major control
functions performed by the electronic control device 40. Switching
control means 50 is arranged to detect a condition of the hybrid
vehicle on the basis of the actual operating speed N.sub.E of the
engine 8, and a drive-force-related value relating to the drive
force of the hybrid vehicle, such as an output torque T.sub.E of
the engine, and determine, according to a stored relationship
(switching map) shown in FIG. 8 by way of example, whether the
detected vehicle condition is in a continuously variable shifting
region for placing the drive system 10 in the continuously-variable
shifting state, or in a step-variable shifting region for placing
the drive system 10 in the step-variable shifting state. When the
switching control means 50 determines that the vehicle condition is
in the step-variable shifting region, the switching control means
50 disables hybrid control means 52 to effect a hybrid control or
continuously-variable shifting control, and enables step-variable
shifting control means 54 to effect a predetermined step-variable
shifting control. In this case, the step-variable shifting control
means 54 effects an automatic shifting control according to a
shifting boundary line map (not shown) stored in shifting-map
memory means 56. FIG. 2 indicates the combinations of the operating
states of the hydraulically operated frictional coupling devices
C0, C1, C2, B0, B1, B2 and B3, which are selectively engaged for
effecting the step-variable shifting control. In this step-variable
automatic shifting control mode, the power distributing mechanism
16 functions as an auxiliary transmission having a fixed speed
ratio .gamma.0 of 1, with the switching clutch C0 placed in the
engaged state, when the drive system is placed in any one of the
first-speed position through the fourth-speed position. When the
drive system is placed in the fifth-speed position, the switching
brake B0 is engaged in place of the switching clutch C0, so that
the power distributing mechanism 16 functions as an auxiliary
transmission having a fixed speed ratio .gamma.0 of about 0.7. In
the step-variable automatic shifting control mode, therefore, the
drive system 10 which includes the power distributing mechanism 16
functioning as the auxiliary transmission, and the automatic
transmission 20, functions as a so-called automatic
transmission.
[0435] The drive-force-related value indicated above is a parameter
corresponding to the drive force of the vehicle, which may be an
output torque T.sub.OUT of the automatic transmission 20, an engine
output torque T.sub.E or an acceleration value of the vehicle, as
well as a drive torque or drive force of drive wheels 38. The
engine output torque T.sub.E may be an actual value calculated on
the basis of the operating angle of the accelerator pedal or the
opening angle of the throttle valve (or intake air quantity,
air/fuel ratio or amount of fuel injection) and the engine speed
N.sub.E, or an estimated value of the engine output torque T.sub.E
or required vehicle drive force which is calculated on the basis of
the amount of operation of the accelerator pedal by the vehicle
operator or the operating angle of the throttle valve. The vehicle
drive torque may be calculated on the basis of not only the output
torque T.sub.OUT, etc., but also the ratio of a differential gear
device of and the radius of the drive wheels 38, or may be directly
detected by a torque sensor or the like.
[0436] When the switching control means 50 determines that the
vehicle condition represented by the engine speed N.sub.E and the
engine output torque T.sub.E is in the continuously-variable
shifting region, on the other hand, the switching control means 50
commands the hydraulic control unit 42 to release the switching
clutch C0 and the switching brake B0 for placing the power
distributing mechanism 16 in the electrically established
continuously-variable shifting state. At the same time, the
switching control means 50 enables the hybrid control means 52 to
effect the hybrid control, and commands the step-variable shifting
control means 54 to select and hold a predetermined one of the gear
positions, or to permit an automatic shifting control according to
the shifting boundary line map stored in the shifting-map memory
means 56. In the latter case, the variable-step shifting control
means 54 effects the automatic shifting control by suitably
selecting the combinations of the operating states of the
frictional coupling devices indicated in the table of FIG. 2,
except the combinations including the engagement of the switching
clutch C0 and brake B0. Thus, the power distributing mechanism 16
functions as the continuously variable transmission while the
automatic transmission connected in series to the power
distributing mechanism 16 functions as the step-variable
transmission, so that the drive system provides a sufficient
vehicle drive force, such that the speed of the rotary motion
transmitted to the automatic transmission 20 placed in one of the
first-speed, second-speed, third-speed and fourth-gear positions,
namely, the rotating speed of the power transmitting member 18 is
continuously changed, so that the speed ratio of the drive system
when the automatic transmission 20 is placed in one of those gear
positions is continuously variable over a predetermined range.
Accordingly, the speed ratio of the automatic transmission 20 is
continuously variable through the adjacent gear positions, whereby
the overall speed ratio .gamma.T of the drive system 10 is
continuously variable.
[0437] The hybrid control means 52 controls the engine 8 to be
operated with high efficiency, and controls the first electric
motor M1 and the second electric motor M2, so as to establish an
optimum proportion of the drive forces which are produced by the
engine 8, and the first electric motor M1 and/or the second
electric motor M2. For instance, the hybrid control means 52
calculates the output as required by the vehicle operator at the
present running speed of the vehicle, on the basis of the operating
amount of the accelerator pedal and the vehicle running speed, and
calculate a required vehicle drive force on the basis of the
calculated required output and a required amount of generation of
an electric energy by the first electric motor M1. On the basis of
the calculated required vehicle drive force, the hybrid control
means 52 calculates desired speed N.sub.E and total output of the
engine 8, and controls the actual output of the engine 8 and the
amount of generation of the electric energy by the first electric
motor M1, according to the calculated desired speed and total
output of the engine. The hybrid control means 52 is arranged to
effect the above-described hybrid control while taking account of
the presently selected gear position of the automatic transmission
20, or controls the shifting operation of the automatic
transmission 20 so as to improve the fuel economy of the engine. In
the hybrid control, the power distributing mechanism 16 is
controlled to function as the electrically controlled
continuously-variable transmission, for optimum coordination of the
engine speed N.sub.E and vehicle speed for efficient operation of
the engine 8, and the rotating speed of the power transmitting
member 18 determined by the selected gear position of the automatic
transmission 20. That is, the hybrid control means 52 determines a
target value of the overall speed ratio .gamma.T of the drive
system 10, so that the engine 8 is operated according a stored
highest-fuel-economy curve that satisfies both of the desired
operating efficiency and the highest fuel economy of the engine 8.
The hybrid control means 52 controls the speed ratio .gamma.0 of
the power distributing mechanism 16, so as to obtain the target
value of the overall speed ratio .gamma.T, so that the overall
speed ratio .gamma.T can be controlled within a predetermined
range, for example, between 13 and 0.5.
[0438] In the hybrid control, the hybrid control means 52 controls
an inverter 58 such that the electric energy generated by the first
electric motor M1 is supplied to an electric-energy storage device
60 and the second electric motor M2 through the inverter 58. That
is, a major portion of the drive force produced by the engine 8 is
mechanically transmitted to the power transmitting member 18, while
the remaining portion of the drive force is consumed by the first
electric motor M1 to convert this portion into the electric energy,
which is supplied through the inverter 58 to the second electric
motor M2, or subsequently consumed by the first electric motor M1.
A drive force produced by an operation of the second electric motor
M1 or first electric motor M1 with the electric energy is
transmitted to the power transmitting member 18. Thus, the drive
system is provided with an electric path through which an electric
energy generated by conversion of a portion of a drive force of the
engine 8 is converted into a mechanical energy. This electric path
includes components associated with the generation of the electric
energy and the consumption of the generated electric energy by the
second electric motor M2.
[0439] It is also noted that the hybrid control means 52 is further
arranged to establish a so-called "motor starting and drive" mode
in which the vehicle is started and driven with only the electric
motor (e.g., second electric motor M2) used as the drive power
source, by utilizing the electric CVT function (differential
function) of the switchable type shifting portion 11, irrespective
of whether the engine 8 is in the non-operated state or in the
idling state. Generally, this motor starting and drive mode is
established when the vehicle condition is in a region of a
comparatively low value of the output torque T.sub.OUT or the
engine torque T.sub.E, in which the engine efficiency is
comparatively low, or in a region of a comparatively low value of
the vehicle speed V or a region of a comparatively low value of the
vehicle load (e.g., a region defined by solid line A in FIG. 12).
In principle, therefore, the vehicle is started by the electric
motor rather than the engine.
[0440] An example of the step-variable shifting region is indicated
in FIG. 8. This step-variable shifting region is defined as a
high-torque region (high output drive region) in which the output
torque T.sub.E of the engine 8 is not smaller than a predetermined
value T.sub.E1, a high-speed region in which the engine speed
N.sub.E is not lower than a predetermined value N.sub.E1 (a
high-vehicle-speed region in which the vehicle speed as one running
condition of the vehicle determined by the engine speed N.sub.E and
the overall speed ratio .gamma.T is not lower than a predetermined
value), or a high-output region in which the engine output
determined by the output torque T.sub.E and speed N.sub.E of the
engine 8 is not smaller than a predetermined value. Accordingly,
the step-variable shifting control is effected when the torque,
speed or output of the engine 8 is comparatively high, while the
continuously-variable shifting control is effected when the torque,
speed or output of the engine is comparatively low, that is, when
the engine is in a normal output state. A switching boundary line
map in FIG. 8, which defines the step-variable shifting region and
the continuously-variable shifting region, functions as an upper
vehicle-speed limit line consisting of a series of upper speed
limits, and an upper output limit line consisting of a series of
upper output limits.
[0441] FIG. 9 shows an example of a manually operable shifting
device in the form of a shifting device 46 including a shift lever
48, which is disposed laterally adjacent to an operator's seat, for
example, and which is manually operated to select one of a
plurality of gear positions consisting of a parking position P for
placing the drive system 10 (namely, automatic transmission 20) in
a neutral state in which a power transmitting path is disconnected
with both of the switching clutch C0 and brake B0 placed in the
released state, while at the same time the output shaft 22 of the
automatic transmission 20 is in the locked state; a reverse-drive
position R for driving the vehicle in the rearward direction; a
neutral position N for placing the drive system 10 in the neutral
state; an automatic forward-drive shifting position D; and a manual
forward-drive shifting position M. The parking position P and the
neutral position N are non-driving positions selected when the
vehicle is not driven, while the reverse-drive position R, and the
automatic and manual forward-drive shifting positions D, M are
driving positions selected when the vehicle is driven. The
automatic forward-drive shifting position D provides a
highest-speed position, and positions "4" through "L" selectable in
the manual forward-drive shifting position M are engine-braking
positions in which an engine brake is applied to the vehicle.
[0442] The manual forward-drive shifting position M is located at
the same position as the automatic forward-drive shifting position
D in the longitudinal direction of the vehicle, and is spaced from
or adjacent to the automatic forward-drive shifting position D in
the lateral direction of the vehicle. The shift lever 48 is
operated to the manual forward-drive shifting position M, for
manually selecting one of the positions "D" through "L". Described
in detail, the shift lever 48 is movable from the manual
forward-drive shifting position M to a shift-up position "+" and a
shift-down position "-", which are spaced from each other in the
longitudinal direction of the vehicle. Each time the shift lever 48
is moved to the shift-up position "+" or the shift-down position
"-", the presently selected position is changed by one position.
The five positions "D" through "L" have respective different lower
limits of a range in which the overall speed ratio .gamma.T of the
drive system 10 is automatically variable, that is, respective
different lowest values of the overall speed ratio .gamma.T which
corresponds to the highest output speed of the drive system 10.
Namely, the five positions "D" through "L" select respective
different numbers of the speed positions or gear positions of the
automatic transmission 20 which are automatically selectable, so
that the lowest overall speed ratio .gamma.T available is
determined by the selected number of the gear positions. The shift
lever 48 is biased by biasing means such as a spring so that the
shift lever 48 is automatically returned from the shift-up position
"+" and shift-down position "-" back to the manual forward-drive
shifting position M. The shifting device 46 is provided with
shift-position sensors operable to detect the presently selected
position of the shift lever 48, so that signals indicative of the
presently selected operating position of the shift lever 48 and the
number of shifting operations of the shift lever 48 in the manual
forward-shifting position M.
[0443] When the shift lever 48 is operated to the automatic
forward-drive shifting position D, the switching control means 50
effects an automatic switching control of the drive system 10
according to a stored switching map indicated in FIG. 8, and the
hybrid control means 52 effects the continuously-variable shifting
control of the power distributing mechanism 16, while the
step-variable shifting control means 54 effects an automatic
shifting control of the automatic transmission 20. When the drive
system 10 is placed in the step-variable shifting state, for
example, the shifting action of the drive system 10 is
automatically controlled to select an appropriate one of the
first-gear position through the fifth-gear position indicated in
FIG. 2. When the drive system is placed in the
continuously-variable shifting state, the speed ratio of the power
distributing mechanism 16 is continuously changed, while the
shifting action of the automatic transmission 20 is automatically
controlled to select an appropriate one of the first-gear through
fourth-gear positions, so that the overall speed ratio .gamma.T of
the drive system 10 is controlled so as to be continuously variable
within the predetermined range. The automatic forward-drive
position D is a position selected to establish an automatic
shifting mode (automatic mode) in which the drive system 10 is
automatically shifted.
[0444] When the shift lever 48 is operated to the manual
forward-drive shifting position M, on the other hand, the shifting
action of the drive system 10 is automatically controlled by the
switching control means 50, hybrid control means 52 and
step-variable shifting control means 54, such that the overall
speed ratio .gamma.T is variable within a predetermined range the
lower limit of which is determined by the gear position having the
lowest speed ratio, which gear position is determined by the
manually selected one of the positions "D" through "L". When the
drive system 10 is placed in the step-variable shifting state, for
example, the shifting action of the drive system 10 is
automatically controlled within the above-indicated predetermined
range of the overall speed ratio .gamma.T. When the drive system 10
is placed in the step-variable shifting state, the speed ratio of
the power distributing mechanism 16 is continuously changed, while
the shifting action of the automatic transmission 20 is
automatically controlled to select an appropriate one of the gear
positions the number of which is determined by the manually
selected one of the positions "D" through "L", so that the overall
speed ratio .gamma.T of the drive system 10 is controlled so as to
be continuously variable within the predetermined range. The manual
forward-drive position M is a position selected to establish a
manual shifting mode (manual mode) in which the selectable gear
positions of the drive system 10 are manually selected.
[0445] In the present embodiment described above, the power
distributing mechanism 16 includes the switching clutch C0 and the
switching brake B0, which constitute the differential-state
switching device operable to selectively place the power
distributing mechanism 16 in the differential state in which the
mechanism 16 is capable of performing a differential function, for
example, the continuously-variable shifting state in which the
mechanism 16 functions as an electrically controlled continuously
variable transmission the speed ratio of which is continuously
variable, and in the non-differential state in which the mechanism
16 is not capable of performing a differential function, for
example, the fixed-speed-ratio shifting state in which the
mechanism 16 is operable as a transmission having fixed speed
ratios. Accordingly, when the engine is in a normal output state
with a relatively low or medium output while the vehicle is running
at a relatively low or medium running speed, the power distributing
mechanism 16 is placed in the continuously-variable shifting state,
assuring a high degree of fuel economy of the hybrid vehicle. When
the vehicle is running at a relatively high speed or when the
engine is operating at a relatively high speed, on the other hand,
the power distributing mechanism 16 is placed in the fixed-ratio
shifting state in which the output of the engine 8 is transmitted
to the drive wheels 38 primarily through the mechanical power
transmitting path, so that the fuel economy is improved owing to
reduction of a loss of conversion of the mechanical energy into the
electric energy. When the engine 8 is in a high-output state, the
power distributing mechanism 16 is also placed in the
fixed-speed-ratio shifting state. Therefore, the mechanism 16 is
placed in the continuously-variable shifting state only when the
vehicle speed is relatively low or medium or when the engine output
is relatively low or medium, so that the required amount of
electric energy generated by the first electric motor M1, that is,
the maximum amount of electric energy that must be transmitted from
the first electric motor M1 can be reduced, whereby the required
electrical reaction force of the first electric motor M1 can be
reduced, making it possible to minimize the required sizes of the
first electric motor M1 and the second electric motor M2, and the
required size of the drive system including those electric motors.
Alternatively, when the engine 8 is in a high-output
(high-torque)state, the power distributing mechanism 16 is placed
in the fixed-speed-ratio shifting state while at the same time the
automatic transmission 20 is automatically shifted, so that the
engine speed N.sub.E changes with a shift-up action of the
automatic transmission 20, assuring a comfortable rhythmic change
of the engine speed N.sub.E as the automatic transmission is
shifted up, as indicated in FIG. 10. Stated in the other way, when
the engine is in a high-output state, it is more important to
satisfy a vehicle operator's desire to improve the drivability of
the vehicle, than a vehicle operator's desire to improve the fuel
economy. In this respect, the power distributing mechanism 16 is
switched from the continuously-variable shifting state to the
step-variable shifting state (fixed-speed-ratio shifting state)
when the engine output becomes relatively high. Accordingly, the
vehicle operator is satisfied with a comfortable rhythmic change of
the engine speed N.sub.E during the high-output operation of the
engine, as indicated in FIG. 10.
[0446] The present embodiment has a further advantage that the
power distributing mechanism 16 is simple in construction, by using
the first planetary gear set 24 of single-pinion type including the
three rotary elements in the form of the first carrier CA1, first
sun gear S1 and first ring gear R1.
[0447] In the present embodiment, the automatic transmission 20 is
connected in series to and interposed between the power
distributing mechanism 16 and the drive wheels 38, so that the
overall speed ratio of the drive system is determined by the speed
ratio of the power distributing mechanism 16 and the speed ratio of
the automatic transmission 20. The width or range of the overall
speed ratio can be broadened by the width of the speed ratio of the
automatic transmission 20, making it possible to improve the
efficiency of operation of the power distributing mechanism 16 in
its continuously-variable shifting state, that is, the efficiency
of hybrid control of the vehicle.
[0448] The present embodiment has another advantage that when the
power distributing mechanism 16 is placed in the fixed-speed-ratio
shifting state, this mechanism 16 functions as if the mechanism 16
was a part of the automatic transmission 20, so that the drive
system provides an overdrive position in the form of the fifth-gear
position the speed ratio of which is lower than 1.
[0449] The present embodiment is further arranged such that the
second electric motor M2 is connected to the power transmitting
member 18 which is provided as an input rotary member of the
automatic transmission 20, so that the required input torque of the
automatic transmission 20 can be made lower than the torque of the
output shaft 22, making it possible to further reduce the required
size of the second electric motor M2.
[0450] Then, the other embodiments of the present invention will be
described. In the following embodiments, the same reference signs
as used in the preceding embodiment will be used to identify
elements similar to those in the preceding embodiment, which will
not be described.
Embodiment 2
[0451] FIG. 11 is a functional block diagram illustrating the
electronic control device 40 according to another embodiment of
this invention, wherein the switching control means 50 is different
from that of the embodiment of FIG. 7 in that the switching control
means 50 of FIG. 11 includes high-speed-running determining means
62, high-output-running determining means 64, and
electric-path-function diagnosing means 66, and is arranged to
effect a switching control on the basis of a relationship shown in
FIG. 12.
[0452] In the embodiment of FIG. 11, the high-speed-running
determining means 62 is arranged to determine whether a vehicle
speed V which is one of operating states of the hybrid vehicle has
reached a predetermined speed value V1, which is an upper limit
value above which it is determined that the vehicle is in a
high-speed running state. The high-output-running determining means
64 is arranged to determine whether a drive-force-related value
such as the output torque T.sub.OUT of the automatic transmission
20, relating to the vehicle drive force which is another operating
state of the hybrid vehicle, has reached a predetermined torque or
drive-force value T1, which is an upper limit value above which it
is determined that the vehicle is in a high-output running state.
Namely, the high-output-running determining means 64 determines
whether the vehicle is running with a high output, on the basis of
a drive-force-related parameter which directly or indirectly
represents the drive force with which the vehicle is driven. The
electric-path-function diagnosing means 66 is arranged to determine
whether the components of the drive system 10 that are operable to
establish the continuously-variable shifting state have a
deteriorated function. This determination by the diagnosing means
66 is based on the functional deterioration of the components
associated with the electric path through which an electric energy
generated by the first electric motor M1 is converted into a
mechanical energy. For example, the determination is made on the
basis of a failure, or a functional deterioration or defect due to
a failure or low temperature, of any one of the first electric
motor M1, second electric motor M2, inverter 58, electric-energy
storage device 60 and electric conductors connecting those
components.
[0453] Shift-position determining means 67 is provided to select or
determine the gear position to which the drive system 10 should be
shifted while the drive system 10 consisting of the power
distributing mechanism 16 and the automatic transmission 10 is
placed in the step-variable shifting state in which the drive
system 10 as a whole functions as the step-variable automatic
transmission. For example, this determination by the shift-position
determining means 67 is based on the vehicle condition represented
by the vehicle speed V and the output torque T.sub.OUT, and
according to the shifting boundary line map of FIG. 12 stored in
the shifting-map memory means 56. The step-variable shifting
control means 54 controls the shifting action of the automatic
transmission 20 on the basis of the gear position selected by the
shift-position determining means 67, irrespective of whether the
drive system 10 is in the step-variable shifting state or the
continuously-variable shifting state. The gear position selected by
the shift-position determining means 67 is checked by
high-speed-gear determining means 68, as to whether this gear
position is a high-speed-gear position or not.
[0454] The high-speed-gear determining means 68 is arranged to
determine whether the gear position which is selected by the
shift-position determining means 67 and to which the drive system
10 should be shifted is the high-speed-gear position, for example,
the fifth-gear position. This determination by the high-speed-gear
determining means 68 is made to determine which one of the
switching clutch C0 and brake B0 should be engaged to place the
drive system 10 in the step-variable shifting state. While the
drive system 10 as a whole is placed in the step-variable shifting
state, the switching clutch C0 is engaged to place the drive system
10 in any of the first-gear position through the fourth-gear
position, while the switching brake B0 is engaged to place the
drive system 10 in the fifth-gear position.
[0455] The switching control means 50 determines that the vehicle
state is in the step-variable shifting region, in any one of the
following conditions or cases: where the high-speed-running
determining means 62 has determined that the vehicle is in the
high-speed running state; where the high-output-running determining
means 64 has determined that the vehicle is in the high-output
running state; and where the electric-path-function diagnosing
means 66 has determined that the electric path function is
deteriorated. In this case, the switching control means 50 disables
the hybrid control means 52 to operate, that is, inhibits the
hybrid control means 52 from effecting the hybrid control or
continuously-variable shifting control, and commands the
step-variable shifting control means 54 to perform predetermined
step-variable shifting control operations, for example, an
operation to command the automatic transmission 20 to be
automatically shifted to the gear position selected by the
shift-position determining means 67, and an operation to command
the hydraulic control unit 42 to engage an appropriate one of the
switching clutch C0 and brake B0, depending upon a result of the
determination by the high-speed-gear determining means 68 as to
whether the gear position selected by the shift-position
determining means 67 is the fifth-gear position. In this case,
therefore, the drive system 10 as a whole consisting of the power
distributing mechanism 16 and the automatic transmission 20
functions as the so-called step-variable automatic transmission,
and performs the automatic shifting actions as indicated in the
table of FIG. 2.
[0456] Where the high-speed-gear determining means 68 determines
that the selected speed is the fifth-gear position, while the
high-speed-running determining means 62 determines that the vehicle
is in the high-speed running state, or while the
high-output-running determining means 64 determines that the
vehicle is in the high-output running state, the switching control
means 50 commands the hydraulic control unit 42 to release the
switching clutch C0 and engage the switching brake B0 to enable the
power distributing mechanism 16 to function as an auxiliary
transmission having a fixed speed ratio .gamma.0 of 0.7, for
example, so that the drive system 10 as a whole is placed in the
high-speed gear position, so-called "overdrive gear position"
having a speed ratio lower than 1.0. Where the high-output-running
determining means 64 determines that the vehicle is in the
high-output running state, and where the high-speed-gear
determining means 68 does not determine that the selected gear
position is the fifth-gear position, the switching control means 50
commands the hydraulic control unit 42 to engage the switching
clutch C0 and release the switching brake B0 to enable the power
distributing mechanism 16 to function as an auxiliary transmission
having a fixed speed ratio .gamma.0 of 1, for example, so that the
drive system 10 as a whole is placed in a low-gear position having
a speed ratio not lower than 1.0. Thus, the switching control means
50 places the drive system 10 in the step-variable shifting state
in any one of the predetermined conditions described above, and
selectively places the power distributing mechanism 16 functioning
as the auxiliary transmission in the high-gear or low-gear
position, while the automatic transmission 20 connected in series
to the power distributing mechanism 16 is enabled to function as
the step-variable transmission, so that the drive system 10 as a
whole functions as the so-called step-variable automatic
transmission.
[0457] For instance, the upper vehicle-speed limit V1 of the
vehicle speed is determined so that the drive system 10 is placed
in the step-variable shifting state while the vehicle speed V is
higher than the limit V1. This determination is effective to
minimize a possibility of deterioration of the fuel economy of the
vehicle if the drive system 10 were placed in the
continuously-variable shifting state at a relatively high running
speed of the vehicle. The upper output-torque limit T1 is
determined depending upon the operating characteristics of the
first electric motor M1, which is small-sized and the maximum
electric energy output of which is made relatively small so that
the reaction torque of the first electric motor M1 is not so large
when the engine output is relatively high in the high-output
running state of the vehicle.
[0458] However, the switching control means 50 commands the
hydraulic control unit 42 to release both of the switching clutch
C0 and brake B0 to place the power distributing mechanism 16 in the
continuously-variable shifting state, while the drive system 10 as
a whole is normally operable in its continuously-variable shifting
state, that is, when the high-speed-running determining means 62
does not determine that the vehicle is in the high-speed running
state, when the high-output-running determining means 64 does not
determine that the vehicle is in the high-output running state, and
when the electric-path-function diagnosing means 66 does not
determine that the electric path function is deteriorated. In this
case, the switching control means 50 enables the hybrid control
means 52 to effect the hybrid control, and commands the
step-variable shifting control means 54 to hold the automatic
transmission 20 in the predetermined gear position selected for the
continuously-variable shifting control, or to permit the automatic
transmission 20 to be automatically shifted to the gear position
selected by the shift-position determining means 67. Thus, in the
predetermined condition of the vehicle, the switching control means
50 enables the power distributing mechanism 16 to operate in the
continuously-variable shifting state, functioning as the
continuously variable transmission, while the automatic
transmission 20 connected in series to the power distributing
mechanism 16 functions as the step-variable transmission, so that
the drive system provides a sufficient vehicle drive force, such
that the speed of the rotary motion transmitted to the automatic
transmission 20 placed in one of the first-speed, second-speed,
third-speed and fourth-gear positions, namely, the rotating speed
of the power transmitting member 18 is continuously changed, so
that the speed ratio of the drive system when the automatic
transmission 20 is placed in one of those gear positions is
continuously variable over a predetermined range. Accordingly, the
speed ratio of the automatic transmission 20 is continuously
variable across the adjacent gear positions, whereby the overall
speed ratio .gamma.T of the drive system 10 is continuously
variable.
[0459] FIG. 12 shows an example of the shifting boundary line map
(shifting map or relationship) which is stored in the shifting-map
memory means 56 and which is used for determining whether the
automatic transmission 20 should be shifted. The shifting boundary
line map consists of shift boundary lines in a rectangular
two-dimensional coordinate system having an axis along which the
vehicle speed V is taken, and an axis along which the
drive-force-related value in the form of the output torque
T.sub.OUT is taken. In FIG. 12, solid lines are shift-up boundary
lines, and one-dot chain lines are shift-down boundary lines.
Broken lines in FIG. 12 are boundary lines defining a step-variable
shifting region and a continuously-variable shifting region which
are used by the switching control means 50. These boundary lines
represent the upper vehicle-speed limit V1 and the upper
output-torque limit T1 above which it is determined that the
vehicle is in the high-speed or high-output running state. FIG. 12
also shows two-dot chain lines which are boundary line offset with
respect to the broken lines, by a suitable amount of control
hysteresis, so that the broken lines and the two-dot chain lines
are selectively used as the boundary lines. Thus, FIG. 12 also
shows a stored switching boundary line map used by the switching
control means 50 to determine whether the vehicle is in the
step-variable shifting state or the continuously-variable shifting
state, depending upon whether the vehicle speed V and the output
torque T.sub.OUT are higher than the predetermined upper limit
values V, T1. Therefore, the above-described determining means 62,
64 may be arranged to determine the vehicle condition according to
this switching boundary line map and on the basis of the actual
values of the vehicle speed V and output torque T.sub.OUT. This
switching boundary line map as well as the shifting boundary line
map may be stored in the shifting-map memory means 56. The
switching boundary line map may include at least one of the
boundary lines representative of the upper vehicle-speed limit V1
and the upper output-torque limit T1, and may use only one of the
two parameters V and T.sub.OUT. The shifting boundary line map and
the switching boundary line may be replaced by stored equations for
comparison of the actual vehicle speed V with the limit value V1
and comparison of the actual output torque T.sub.OUT with the limit
value T1.
[0460] It is noted that the step-variable shifting region and
continuously-variable shifting region of FIG. 12 are considered to
be a modification of the step-variable shifting region and
continuously-variable shifting region of FIG. 8 which are defined
by the output torque T.sub.E and speed N.sub.E of the engine 8.
According to the shifting regions of FIG. 12, the step-variable
shifting region consists of a high-torque region in which the
output torque T.sub.OUT is not lower than the upper limit value T1,
and a high-speed region in which the vehicle speed V is not lower
than the upper limit value V1, so that the step-variable shifting
state is established when the vehicle is in a high-output running
state with the engine 8 having a comparatively high output, or in a
high-speed running state with the engine 8 operating at a
comparatively high speed, and the continuously-variable shifting
state is established when the vehicle is in a low-output running
state with the engine 8 having a comparatively low output, or in a
low-speed running state with the engine 8 operating at a
comparatively low speed, that is, when the engine 8 is in a normal
output state.
[0461] FIG. 13 is a flow chart illustrating one of major control
operations of the electronic control device 40, that is, a
switching control of the drive system 10 in the embodiment of FIG.
11. This switching control is repeatedly executed with an extremely
short cycle time of about several milliseconds to several tens of
milliseconds, for example.
[0462] Initially, step S1 (hereinafter "step" being omitted)
corresponding to the high-speed-running determining means 62 is
implemented to determine whether the actual speed V of the hybrid
vehicle is equal to or higher than the predetermined upper limit
V1. If a negative decision is obtained in S1, the control flow goes
to S2 corresponding to the high-output-running determining means
64, to determine whether the actual drive torque of the hybrid
vehicle or the actual output toque T.sub.OUT of the automatic
transmission 20 is equal to or higher than the predetermined upper
limit T1. If a negative decision is obtained in S2, the control
flow goes to S3 corresponding to the electric-path-function
diagnosing means 66, to diagnose the components associated with the
electric path (electric energy transmitting path) through which an
electric energy generated by the first electric motor M1 is
converted into a mechanical energy, for example, to determine
whether any one of the first electric motor M1, second electric
motor M2, inverter 58, electric-energy storage device 60, and
electric conductors connecting those components has a deteriorated
function, such as a failure or a functional defect due to a low
temperature.
[0463] If a negative decision is obtained in S3, the control flow
goes to S4 corresponding to the switching control means 50, in
which the switching control means 50 commands the hydraulic control
unit 42 to release the switching clutch C0 and the switching brake
B0, for placing the power distributing mechanism 16 in the
continuously-variable shifting state, and at the same time enables
the hybrid control means 52 to effect the hybrid control and
commands the step-variable control means 54 to permit the automatic
transmission 20 to be automatically shifted to the gear position
selected by the shift-position determining means 67. Accordingly,
the power distributing mechanism 16 is enabled to function as the
continuously variable transmission, while the automatic
transmission 20 connected in series to the power distributing
mechanism 16 is enabled to function as the step-variable
transmission, so that the drive system provides a sufficient
vehicle drive force, such that the speed of the rotary motion
transmitted to the automatic transmission 20 placed in one of the
first-speed, second-speed, third-speed and fourth-gear positions,
namely, the rotating speed of the power transmitting member 18 is
continuously changed, so that the speed ratio of the drive system
when the automatic transmission 20 is placed in one of those gear
positions is continuously variable over a predetermined range.
Accordingly, the speed ratio of the automatic transmission 20 is
continuously variable across the adjacent gear positions, whereby
the overall speed ratio .gamma.T of the drive system 10 is
continuously variable.
[0464] If an affirmative decision is obtained in any one of S1, S2
and S3, the control flow goes to S5 corresponding to the
shift-position determining means 67, to determine or select the
gear position to which the drive system 10 should be shifted. This
determination is effected, for example, on the basis of the vehicle
condition and according to the shifting boundary line map stored in
the shifting-map memory means 56 and shown in FIG. 12. Then, S6
corresponding to the high-speed-gear determining means 68 is
implemented to determine whether the gear position of the drive
system 10 which is selected in S5 is the high-gear position, for
example, the fifth-gear position.
[0465] If an affirmative decision is obtained in S6, the control
flow goes to S8 corresponding to the switching control means 50, in
which the switching control means 50 commands the hydraulic control
unit 42 to release the switching clutch C0 and engage the switching
brake B0 to enable the power distributing mechanism 16 to function
as the auxiliary transmission having the fixed speed ratio .gamma.0
of 0.7, for example. At the same time, the switching control means
50 disables the hybrid control means 52 to effect the hybrid
control, that is, inhibits the hybrid control means 52 from
effecting the hybrid control or continuously-variable shifting
control, and commands the step-variable shifting control means 54
to command the automatic transmission 20 to be automatically
shifted to the fourth-gear position, so that the drive system 10 as
a whole is placed in the fifth-gear position selected in S6. If a
negative decision is obtained in S6, the control flow goes to S7
corresponding to the switching control means 50, in which the
switching control means 50 commands the hydraulic control unit 42
to engage the switching clutch C0 and release the switching brake
B0 to enable the power distributing mechanism 16 to function as the
auxiliary transmission having the fixed speed ratio .gamma.0 of 1,
for example. At the same time, the switching control means 50
inhibits the hybrid control means 52 from effecting the hybrid
control or continuously-variable shifting control, and commands the
step-variable shifting control means 54 to command the automatic
transmission 20 to be automatically shifted to one of the
first-gear position through the fourth-gear position, which was
selected in S5. Thus, S7 and S8 are arranged such that the power
distributing mechanism 16 is enabled to function as the auxiliary
transmission while the automatic transmission 20 connected in
series to the power distributing mechanism 16 is enabled to
function as the step-variable transmission, so that the drive
system 10 as a whole placed in the step-variable transmission is
enabled to function as the so-called step-variable automatic
transmission.
[0466] Like the preceding embodiment, the present embodiment is
arranged such that the power distributing mechanism 16 includes the
switching clutch C0 and the switching brake B0, which constitute
the differential-state switching device operable to selectively
place the drive system 10 in the continuously-variable shifting
state in which the drive system functions as an electrically
controlled continuously variable transmission the speed ratio of
which is continuously variable, and in the step-variable shifting
state in which the drive system is operable as a step-variable
transmission. The drive system 10 is automatically placed in the
continuously-variable shifting state or the step-variable shifting
state, under the control of the switching control means 50, on the
basis of the running condition of the vehicle, so that the drive
system 10 has not only an advantage of improved fuel economy owing
to the electrically controlled continuously variable transmission,
but also an advantage of high power transmitting efficiency owing
to the step-variable transmission capable of mechanical
transmission of a vehicle drive force. When the engine is in a
normal output state, for example, when the vehicle condition is in
the continuously-variable shifting region of FIG. 12 in which the
vehicle speed V is not higher than the upper limit V1 while the
output torque T.sub.OUT is not higher than the upper limit value
T1, the drive system 10 is placed in the continuously-variable
shifting state. This arrangement assures a high degree of fuel
economy of the hybrid vehicle during its normal city running, that
is, at a relatively low or medium speed with a relatively low or
medium output. When the vehicle is in the high-speed running state,
for example, when the vehicle condition is in the step-variable
shifting region of FIG. 12 in which the vehicle speed V is higher
than the upper limit V1, the drive system 10 is placed in the
step-variable shifting state, in which the output of the engine 8
is transmitted to the drive wheels 38 primarily through the
mechanical power transmitting path, so that the fuel economy is
improved owing to reduction of a loss of conversion of the
mechanical energy into the electric energy. When the vehicle is in
the high-output running state, for example, when the vehicle
condition is in the step-variable shifting region in which the
output torque T.sub.OUT is higher than the upper limit T1, the
drive system is placed in the step-variable shifting state, in
which the output of the engine 8 is transmitted to the drive wheels
38 primarily through the mechanical power transmitting path. Thus,
the drive system 10 is placed in the continuously-variable shifting
state only when the vehicle is in the low- or medium-speed running
state or low- or medium-output running state, so that the required
amount of electric energy generated by the first electric motor M1,
that is, the maximum amount of electric energy that must be
transmitted from the first electric motor M1 can be reduced,
whereby the required electrical reaction force of the first
electric motor M1 can be reduced, making it possible to minimize
the required sizes of the first electric motor M1 and the second
electric motor M2, and the required size of the drive system
including those electric motors.
[0467] The present embodiment is further advantageous in that when
the drive system 10 is switched from the continuously-variable
shifting state to the step-variable-shifting state depending upon a
change of the vehicle condition, one of the switching clutch C0 and
the switching brake B0 which constitute the differential-state
switching device is engaged depending upon the vehicle condition,
to select the gear position to which the automatic transmission is
shifted in the step-variable shifting state. Thus, the shifting
action of the automatic transmission can be suitably controlled in
the step-variable shifting mode, depending upon whether the vehicle
is in the high-speed or high-output running state or not.
[0468] In the present embodiment, the determination as to whether
the vehicle is in the high-speed running state is made by
determining whether the vehicle speed is higher than the upper
limit V1. The switching control means 50 places the transmission
mechanism 10 in the step-variable shifting state when the actual
vehicle speed V has exceeded the upper limit V1. Accordingly, while
the actual vehicle speed V is higher than the upper limit V1, the
output of the engine 8 is transmitted to the drive wheels 38
primarily through the mechanical power transmitting path, so that
the fuel economy of the vehicle is improved owing to reduction of a
loss of conversion of the mechanical energy into the electric
energy, which would take place when the transmission mechanism 10
is operated as the electrically controlled continuously variable
transmission.
[0469] In the present embodiment, the determination as to whether
the vehicle is in the high-output running state is made by
determining whether the output torque is higher than the upper
limit T1. The switching control means 50 places the transmission
mechanism 10 in the step-variable shifting state when the actual
output torque T.sub.OUT has exceeded the upper limit T1.
Accordingly, while the actual output torque T.sub.OUT is higher
than the upper limit T1, the output of the engine 8 is transmitted
to the drive wheels 38 primarily through the mechanical power
transmitting path. Thus, the transmission mechanism 10 is operated
as the electrically controlled continuously variable transmission
only when the vehicle is in the low- or medium-output running
state, so that the maximum amount of electric energy that must be
generated by the first electric motor M1 can be reduced, whereby
the required output capacity of the first electric motor M1 can be
reduced, making it possible to minimize the required sizes of the
first electric motor M1 and the second electric motor M2, and the
required size of the drive system including those electric
motors.
[0470] Further, the present embodiment uses the switching boundary
line map representative of the upper vehicle-speed limit V1 and the
upper output-torque limit T1, with which the actual vehicle speed V
and output torque T.sub.OUT are compared by the switching control
means 50, for simple determination of the vehicle condition, more
specifically, for simple determination as to whether the vehicle is
in the high-speed-running state or in the high-output-running
state.
[0471] The present embodiment is further arranged such that the
switching control means 50 places the drive system 10 in the
step-variable shifting state, when it is determined that a
predetermined diagnosing condition indicative of functional
deterioration of the control components that are operable to place
the drive system 10 in the continuously-variable shifting state is
satisfied. Thus, the vehicle can be run with the drive system 10
operating in the step-variable shifting state, even when the drive
system cannot be normally operated in the continuously-variable
shifting state.
[0472] The present embodiment is further arranged such that the
switching control means 50 engages the hydraulically operated
frictional coupling device in the form of the switching brake B0
serving as the differential-state switching device, to hold the
second rotary element (first sun gear S1) stationary, when the
actual vehicle speed V has exceeded the upper limit V1.
Accordingly, while the actual vehicle speed V is higher than the
upper limit V1, the output of the engine 8 is transmitted to the
drive wheels 38 primarily through the mechanical power transmitting
path, so that the fuel economy of the vehicle is improved owing to
reduction of a loss of conversion of the mechanical energy into the
electric energy, which would take place when the transmission
mechanism 10 is operated as the electrically controlled
continuously variable transmission.
[0473] The present embodiment is further arranged such that the
switching control means 50 engages the hydraulically operated
frictional coupling device in the form of the switching clutch C0
serving as the differential-state switching device, to connect the
first sun gear S1 and the first carrier CA1 to each other, when the
actual output toque T.sub.OUT has exceeded the upper limit T1.
Accordingly, while the actual output torque T.sub.OUT is higher
than the upper limit T1, the output of the engine 8 is transmitted
to the drive wheels 38 primarily through the mechanical power
transmitting path, so that the maximum amount of electric energy
that must be transmitted from the first electric motor M1 when the
transmission mechanism 10 is operated as the electrically
controlled continuously variable transmission can be reduced,
making it possible to minimize the required sizes of the first
electric motor M1 and the second electric motor M2, and the
required size of the drive system including those electric
motors.
[0474] The present embodiment has a further advantage that the
power distributing mechanism 16 is simple in construction and has a
reduced axial dimension, by using the first planetary gear set 24
of single-pinion type including the three rotary elements in the
form of the first carrier CA1, first sun gear S1 and first ring
gear R1. The power distributing mechanism 16 incorporates the
hydraulically operated frictional coupling devices in the form of
the switching clutch C0 operable to connect the first sun gear S1
and the first carrier CA1 to each other, and the switching brake B0
operable to fix the first sun gear S1 to the transmission casing
12. Accordingly, the switching control means 50 permits simple
switching of the drive system 10 between the continuously-variable
shifting state and the step-variable shifting state.
[0475] In the present embodiment, the automatic transmission 20 is
connected in series to and interposed between the power
distributing mechanism 16 and the drive wheels 38, so that the
overall speed ratio of the drive system is determined by the speed
ratio of the power distributing mechanism 16 and the speed ratio of
the automatic transmission 20. The width or range of the overall
speed ratio can be broadened by the width of the speed ratio of the
automatic transmission 20, making it possible to improve the
efficiency of the continuously-variable shifting control of the
power distributing mechanism 16, that is, the efficiency of hybrid
control of the vehicle.
[0476] The present embodiment has another advantage that when the
power distributing mechanism 16 is placed in the step-variable
shifting state, the switchable type shifting portion 11 functions
as if the shifting portion 11 was a part of the automatic
transmission 20, so that the drive system provides an overdrive
position in the form of the fifth-gear position the speed ratio of
which is lower than 1.
[0477] The present embodiment is further arranged such that the
second electric motor M2 is connected to the power transmitting
member 18 which is provided as an input rotary member of the
automatic transmission 20, so that the required input torque of the
automatic transmission 20 can be made lower than the torque of the
output shaft 22, making it possible to further reduce the required
size of the second electric motor M2.
Embodiment 3
[0478] FIG. 14 is a schematic view for explaining an arrangement of
a drive system 70 according to another embodiment of this
invention, and FIG. 15 is a table indicating gear positions of the
drive system 70, and different combinations of engaged states of
the hydraulically operated frictional coupling devices for
respectively establishing those gear positions, while FIG. 16 is a
collinear chart for explaining shifting operation of the drive
system 70.
[0479] The drive system 70 includes the power distributing
mechanism 16, which has the first planetary gear set 24 of
single-pinion type having a gear ratio .rho.1 of about 0.418, for
example, and the switching clutch C0 and the switching brake B0, as
in the preceding embodiment. The drive system 70 further includes
an automatic transmission 72 which has three forward-drive
positions and which is interposed between and connected in series
to the power distributing mechanism 16 and the output shaft 22
through the power transmitting member 18. The automatic
transmission 72 includes a single-pinion type second planetary gear
set 26 having a gear ratio .rho.2 of about 0.532, for example, and
a single-pinion type third planetary gear set 28 having a gear
ratio .rho.3 of about 0.418, for example. The second sun gear S2 of
the second planetary gear set 26 and the third sun gear S3 of the
third planetary gear set 28 are integrally fixed to each other as a
unit, selectively connected to the power transmitting member 18
through the second clutch C2, and selectively fixed to the
transmission casing 12 through the first brake B1. The second
carrier CA2 of the second planetary gear set 26 and the third ring
gear R3 of the third planetary gear set 28 are integrally fixed to
each other and fixed to the output shaft 22. The second ring gear
R2 is selectively connected to the power transmitting member 18
through the first clutch C1, and the third carrier CA3 is
selectively fixed to the casing 12 through the second brake B2.
[0480] In the drive system 70 constructed as described above, one
of a first-gear position (first-speed position) through a
fourth-gear position (fourth-speed position), a reverse-gear
position (rear-drive position) and a neural position is selectively
established by engaging actions of a corresponding combination of
the frictional coupling devices selected from the above-described
switching clutch C0, first clutch C1, second clutch C2, switching
brake B0, first brake B1 and second brake B2, as indicated in the
table of FIG. 15. Those gear positions have respective speed ratios
.gamma. (input shaft speed N.sub.IN/output shaft speed N.sub.OUT)
which change as geometric series. In particular, it is noted that
the power distributing mechanism 16 provided with the switching
clutch C0 and brake B0 can be selectively placed by engagement of
the switching clutch C0 or switching brake B0, in the
fixed-speed-ratio shifting state in which the mechanism 16 is
operable as a transmission having a single gear position with one
speed ratio or a plurality of gear positions with respective speed
ratios, as well as in the continuously-variable shifting state in
which the mechanism 16 is operable as a continuously variable
transmission, as described above. In the present drive system 70,
therefore, a step-variable transmission is constituted by the
automatic transmission 20, and the power distributing mechanism 16
which is placed in the fixed-speed-ratio shifting state by
engagement of the switching clutch C0 or switching brake B0.
Further, a continuously variable transmission is constituted by the
automatic transmission 20, and the power distributing mechanism 16
which is placed in the continuously-variable shifting state, with
none of the switching clutch C0 and brake B0 being engaged.
[0481] Where the drive system 70 functions as the step-variable
transmission, for example, the first-gear position having the
highest speed ratio .gamma.1 of about 2.804, for example, is
established by engaging actions of the switching clutch C0, first
clutch C1 and second brake B2, and the second-gear position having
the speed ratio .gamma.2 of about 1.531, for example, which is
lower than the speed ratio .gamma.1, is established by engaging
actions of the switching clutch C0, first clutch C1 and first brake
B1, as indicated in FIG. 15. Further, the third-gear position
having the speed ratio .gamma.3 of about 1.000, for example, which
is lower than the speed ratio .gamma.2, is established by engaging
actions of the switching clutch C0, first clutch C1 and second
clutch C2, and the fourth-gear position having the speed ratio
.gamma.4 of about 0.705, for example, which is lower than the speed
ratio .gamma.3, is established by engaging actions of the first
clutch C1, second clutch C2, and switching brake B0. Further, the
reverse-gear position having the speed ratio .gamma.R of about
2.393, for example, which is intermediate between the speed ratios
.gamma.1 and .gamma.2, is established by engaging actions of the
second clutch C2 and the second brake B2. The neutral position N is
established by engaging only the switching clutch C0.
[0482] Where the drive system 70 functions as the
continuously-variable transmission, on the other hand, the
switching clutch C0 and the switching brake B0 are both released,
as indicated in FIG. 15, so that the power distributing mechanism
16 functions as the continuously variable transmission, while the
automatic transmission 72 connected in series to the power
distributing mechanism 16 functions as the step-variable
transmission, whereby the speed of the rotary motion transmitted to
the automatic transmission 72 placed in one of the first-gear,
second-gear and third-gear positions, namely, the rotating speed of
the power transmitting member 18 is continuously changed, so that
the speed ratio of the drive system when the automatic transmission
72 is placed in one of those gear positions is continuously
variable over a predetermined range. Accordingly, the speed ratio
of the automatic transmission 72 is continuously variable across
the adjacent gear positions, whereby the overall speed ratio
.gamma.T of the drive system 70 is continuously variable.
[0483] The collinear chart of FIG. 16 indicates, by straight lines,
a relationship among the rotating speeds of the rotary elements in
each of the gear positions of the drive system 70, which is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 72 functioning as the
step-variable shifting portion or second shifting portion. The
collinear chart of FIG. 16 indicates the rotating speeds of the
individual elements of the power distributing mechanism 16 when the
switching clutch C0 and brake B0 are released, and the rotating
speeds of those elements when the switching clutch C0 or brake B0
is engaged, as in the preceding embodiments
[0484] In FIG. 16, four vertical lines Y4, Y5, Y6 and Y7
corresponding to the automatic transmission 72 respectively
represent the relative rotating speeds of a fourth rotary element
(fourth element) RE4 in the form of the second and third sun gears
S2, S3 integrally fixed to each other, a fifth rotary element
(fifth element) RE5 in the form of the third carrier CA3, a sixth
rotary element (sixth element) RE6 in the form of the second
carrier CA2 and third ring gear R3 that are integrally fixed to
each other, and a seventh rotary element (seventh element) RE7 in
the form of the second ring gear R2. In the automatic transmission
72, the fourth rotary element RE4 is selectively connected to the
power transmitting member 18 through the second clutch C2, and is
selectively fixed to the casing 12 through the first brake B1, and
the fifth rotary element RE5 is selectively fixed to the casing 12
through the second brake B2. The sixth rotary element RE6 is fixed
to the output shaft 22 of the automatic transmission 72, and the
seventh rotary element RE7 is selectively connected to the power
transmitting member 18 through the first clutch C1.
[0485] When the first clutch C1 and the second brake B2 are
engaged, the automatic transmission 72 is placed in the first-speed
position. The rotating speed of the output shaft 22 in the
first-speed position is represented by a point of intersection
between the vertical line Y6 indicative of the rotating speed of
the sixth rotary element RE6 fixed to the output shaft 22 and an
inclined straight line L1 which passes a point of intersection
between the vertical line Y7 indicative of the rotating speed of
the seventh rotary element RE7 and the horizontal line X2, and a
point of intersection between the vertical line Y5 indicative of
the rotating speed of the fifth rotary element RE5 and the
horizontal line X1. Similarly, the rotating speed of the output
shaft 22 in the second-speed position established by the engaging
actions of the first clutch C1 and first brake B1 is represented by
a point of intersection between an inclined straight line L2
determined by those engaging actions and the vertical line Y6
indicative of the rotating speed of the sixth rotary element RE6
fixed to the output shaft 22. The rotating speed of the output
shaft 22 in the third-speed position established by the engaging
actions of the first clutch C1 and second clutch C2 is represented
by a point of intersection between an inclined straight line L3
determined by those engaging actions and the vertical line Y6
indicative of the rotating speed of the sixth rotary element RE6
fixed to the output shaft 22. In the first-speed through
third-speed positions in which the switching clutch C0 is placed in
the engaged state, the seventh rotary element RE7 is rotated at the
same speed as the engine speed N.sub.E, with the drive force
received from the power distributing mechanism 16. When the
switching clutch B0 is engaged in place of the switching clutch C0,
the sixth rotary element RE6 is rotated at a speed higher than the
engine speed N.sub.E, with the drive force received from the power
distributing mechanism 16. The rotating speed of the output shaft
22 in the fourth-speed position established by the engaging actions
of the first clutch C1, second clutch C2 and switching brake B0 is
represented by a point of intersection between a horizontal line L4
determined by those engaging actions and the vertical line Y6
indicative of the rotating speed of the sixth rotary element RE6
fixed to the output shaft 22. The rotating speed of the output
shaft 22 in the reverse drive position R established by the
engaging actions of the second clutch C2 and second brake B2 is
represented by a point of intersection between an inclined straight
line LR determined by those engaging actions and the vertical line
Y6 indicative of the rotating speed of the sixth rotary element RE6
fixed to the output shaft 22.
[0486] The drive system 70 of the present embodiment is also
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 72 functioning as the
step-variable shifting portion or second shifting portion, so that
the present drive system 70 has advantages similar to those of the
preceding embodiments.
Embodiment 4
[0487] FIG. 17 is a schematic view for explaining an arrangement of
a drive system 80 according to another embodiment of this
invention, and FIG. 18 is a table indicating gear positions of the
drive system 80 placed in the step-variable shifting state, and
different combinations of engaged states of the hydraulically
operated frictional coupling devices for respectively establishing
those gear positions, while FIG. 19 is a collinear chart for
explaining step-variable shifting operations of the drive system
70. FIG. 20 is a table indicating the gear positions of the drive
system 80 placed in the continuously-variable shifting state and
different combinations of engaged states of the hydraulically
operated frictional coupling devices for respectively establishing
those gear positions, and FIG. 21 is a collinear chart for
explaining continuously-variable shifting operations of the drive
system 90.
[0488] The drive system 80 includes a power distributing mechanism
84, which has a first planetary gear set 82 of double-pinion type,
and the switching clutch C0 and the switching brake B0. The drive
system 80 further includes an automatic transmission 86 which has
seven forward-drive positions and which is interposed between and
connected in series to the power distributing mechanism 16 and the
output shaft 22 through the power transmitting member 18. The
double-pinion type first planetary gear set 82 of the power
distributing mechanism 84 in the present embodiment includes rotary
elements consisting of: a first sun gear S1; a first planetary gear
P1 and a second planetary gear P2 which mesh with each other; a
first carrier CA1 supporting the first and second planetary gears
P1, P2 such that each of the first and second planetary gears P1,
P2 is rotatable about its axis and about the axis of the first sun
gear S1; and a first ring gear R1 meshing with the first sun gear
S1 through the first and second planetary gears P1, P2. The first
planetary gear set 82 has a gear ratio .rho.1 of about 0.425, for
example. In the power distributing mechanism 84, which is similar
to the power distributing mechanism 16, the first carrier CA1 is
connected to the input shaft 14, that is, to the engine 8, and the
first sun gear S1 is connected to the first electric motor M1,
while the first ring gear R1 is connected to the power transmitting
member 18. The switching brake B0 is disposed between the first sun
gear S1 and the transmission casing 12, and the switching clutch C0
is disposed between the first sun gear S1 and the first carrier
CA1. When the switching clutch C0 and brake B0 are released, the
power distributing mechanism 84 is placed in a
continuously-variable shifting state in which the mechanism 84
functions as a continuously variable transmission the speed ratio
.gamma.0 of which is continuously variable. When the switching
clutch C0 is engaged, the power distributing mechanism 84 is placed
in a fixed-speed-ratio shifting state in which the mechanism 84
functions as a transmission having a fixed speed ratio .gamma.0 of
1. When the switching brake B0 rather than the switching clutch C0
is engaged, the power distributing mechanism 84 is placed in a
fixed-speed-ratio shifting state in which the mechanism 84
functions as a speed-reducing transmission having a fixed speed
ratio .gamma.0 of about 1.7, for example, which is larger than 1.
In this embodiment, too, the switching clutch C0 and brake B0
function as a differential-state switching device operable to
selectively place the power distributing mechanism 84 in the
continuously-variable shifting state in which the mechanism 84
functions as a continuously variable transmission the speed ratio
of which is continuously variable, and in the fixed-speed-ratio
shifting state in which the mechanism 84 functions as a
transmission having a single gear position with one speed ratio or
a plurality of gear positions with respective speed ratios.
[0489] The automatic transmission 86 includes a single-pinion type
second planetary gear set 88 having a gear ratio .rho.2 of about
0.550, for example, and double-pinion type third planetary gear set
90 having a gear ratio .rho.3 of about 0.462, for example. The
double-pinion third planetary gear set 90 has a pair of pinions P1,
P2 which are rotatably supported by a third carrier CA3 and which
mesh with each other. The outer pinion P2 is formed integrally with
a pinion of the second planetary gear set 88. A third ring gear R3
and the third carrier CA3 which mesh with the pinion P2 are formed
integrally with a second ring gear R2 and a second carrier CA2 of
the second planetary gear set 88. A third sun gear S3 of the third
planetary gear set 90 is selectively connected to the power
transmitting member 18 through a first clutch C1, and a second sun
gear S2 of the second planetary gear set 88 is selectively fixed to
the transmission casing 12 through a first brake B1, and
selectively connected to the power transmitting member 18 through a
third clutch C3. The second carrier CA2 and the third carrier CA3
are selectively fixed to the transmission casing 12 through a
second brake B2, and selectively connected to the input shaft 14
through a second clutch C2. The second ring gear R2 and the third
ring gear R3 are integrally fixed to the output shaft 22.
[0490] In the drive system 80 constructed as described above, one
of a first-gear position (first-speed position) through a
seventh-gear position (seventh-speed position), a reverse-gear
position (rear-drive position) and a neural position is selectively
established by engaging actions of a corresponding combination of
the frictional coupling devices selected from the above-described
switching clutch C0, first clutch C1, second clutch C2, third
clutch C3, switching brake B0, first brake B1 and second brake B2,
as indicated in the table of FIG. 18. Those gear positions have
respective speed ratios .gamma. (input shaft speed N.sub.IN/output
shaft speed N.sub.OUT) which change as geometric series. In
particular, it is noted that the power distributing mechanism 84
provided with the switching clutch C0 and brake B0 can be
selectively placed by engagement of the switching clutch C0 or
switching brake B0, in the fixed-speed-ratio shifting state in
which the mechanism 84 is operable as a transmission having a
single speed ratio or a plurality of speed ratios, as well as in
the continuously-variable shifting state in which the mechanism 84
is operable as a continuously variable transmission, as described
above. In the present drive system 80, therefore, a step-variable
transmission is constituted by the automatic transmission 86, and
the power distributing mechanism 84 which is placed in the
fixed-speed-ratio shifting state by engagement of the switching
clutch C0 or switching brake B0. Further, a continuously variable
transmission is constituted by the automatic transmission 86, and
the power distributing mechanism 84 which is placed in the
continuously-variable shifting state, with none of the switching
clutch C0 and brake B0 being engaged.
[0491] Where the drive system 80 functions as the step-variable
transmission, for example, the first-gear position having the
highest speed ratio .gamma.1 of about 3.763, for example, is
established by engaging actions of the first clutch C1, second
brake B2 and switching brake B0, and the second-gear position
having the speed ratio .gamma.2 of about 2.457, for example, which
is lower than the speed ratio .gamma.1, is established by engaging
actions of the first clutch C1, switching brake B0 and first brake
B1, as indicated in FIG. 18. Further, the third-gear position
having the speed ratio .gamma.3 of about 1.739, for example, which
is lower than the speed ratio .gamma.2, is established by engaging
actions of the first clutch C1, third clutch C3 and switching brake
B0, and the fourth-gear position having the speed ratio .gamma.4 of
about 1.244, for example, which is lower than the speed ratio
.gamma.3, is established by engaging actions of the first clutch
C1, second clutch C2, and switching brake B0. The fifth-gear
position having the speed ratio .gamma.5 of 1.000 is established by
engaging actions of the switching clutch C0 and the second clutch
C2. The sixth-gear position having the speed ratio .gamma.6 of
about 0.811, for example, which is lower than the speed ratio
.gamma.5, is established by engaging actions of the second clutch
C2, third clutch C3 and switching brake B0. The seventh-gear
position having the speed ratio .gamma.7 of about 0.645, for
example, which is lower than the speed ratio .gamma.6, is
established by engaging actions of the second clutch C2, switching
brake B0 and first brake B1. Further, the reverse-gear position
having the speed ratio .gamma.R of about 3.162, for example, which
is intermediate between the speed ratios .gamma.1 and .gamma.2, is
established by engaging actions of the third clutch C3, switching
brake B0 and second brake B2.
[0492] Where the drive system 80 functions as the step-variable
transmission, on the other hand, the switching clutch C0 and the
switching brake B0 are both released, as indicated in FIG. 20, so
that the power distributing mechanism 84 functions as the
continuously variable transmission, while the automatic
transmission 86 connected in series to the power distributing
mechanism 84 functions as the step-variable transmission having
three forward-drive positions, whereby the speed of the rotary
motion transmitted to the automatic transmission 86 placed in one
of the first-gear, second-gear and third-gear positions, namely,
the rotating speed of the power transmitting member 18 is
continuously changed, so that the speed ratio of the drive system
when the automatic transmission 86 is placed in one of those gear
positions is continuously variable over a predetermined range.
Accordingly, the speed ratio of the automatic transmission 86 is
continuously variable across the adjacent gear positions, whereby
the overall speed ratio .gamma.T of the drive system 80 is
continuously variable.
[0493] The collinear chart of FIG. 19 indicates, by straight lines,
a relationship among the rotating speeds of the rotary elements in
each of the gear positions of the drive system 80 including the
power distributing mechanism 84 and the automatic transmission 86,
when the power distributing mechanism 84 is placed in the
step-variable shifting state established by the engaging action of
one of the switching clutch C0 and brake B0.
[0494] In FIG. 19, vertical lines Y1, Y2 and Y3 respectively
indicate the rotating speeds of the first sun gear S1 (second
rotary element RE2), the first ring gear R1 (third rotary element
RE3) and the first carrier CA1 (first rotary element RE1) of the
first planetary gear set 82 of the power distributing mechanism 84.
When the switching brake B0 is engaged to establish the first-speed
position through the fourth-speed position, the sixth-speed
position and the seventh-speed position, the rotating speed of the
first sun gear S1 is zeroed, while the rotating speed of the first
carrier CA1 is made equal to the engine speed N.sub.E, so that the
relative rotating speed of the first ring gear R1, that is, the
relative rotating speed of the power transmitting member 18 is
represented by a point of intersection between the vertical line Y2
and a straight line L0 which connects a point of intersection
between the horizontal line X1 and the vertical line Y1, and a
point of intersection between the vertical line Y3 and the
horizontal line X2 indicative of the engine speed N.sub.E. In this
case, the relative rotating speed of the power transmitting member
18 is lower than the engine speed N.sub.E represented by the
horizontal line X2, so that the power distributing mechanism 84
functions as a speed reducing device. For vertical lines Y4-Y7, the
horizontal line X3 indicates the reduced rotating speed. When the
switching clutch C0 is engaged in place of the switching brake B0,
to establish the fifth-speed position, the first sun gear S1, first
ring gear R1 and first carrier CA1 of the first planetary gear set
82 are rotated as a unit at the engine speed N.sub.E, and the
relative rotating speed of the first ring gear R1, that is, the
relative rotating speed of the power transmitting member 18 is
represented by a point of intersection between the horizontal line
X2 and the vertical line Y2. In this case, the relative rotating
speed of the power transmitting member 18 is equal to the engine
speed N.sub.E, so that the power distributing mechanism 84
functions as a fixed-speed-ratio transmission having a speed ratio
of 1. For the vertical lines Y4-Y7, the horizontal line X2
indicates the rotating speed.
[0495] As shown in the collinear chart of FIG. 19, the automatic
transmission 86 is placed in the first-speed position when the
first clutch C1, switching brake B0 and second brake B2 are
engaged. The rotating speed of the output shaft 22 in the
first-speed position is represented by a point of intersection
between the vertical line Y6 indicative of the rotating speed of
the sixth rotary element RE6 (R2, R3) fixed to the output shaft 22
and an inclined straight line L1 which passes a point of
intersection between the vertical line Y7 indicative of the
rotating speed of the seventh rotary element RE7 (S3) and the
horizontal line X3, and a point of intersection between the
vertical line Y5 indicative of the rotating speed of the fifth
rotary element RE5 (CA2, CA3) and the horizontal line X1.
Similarly, the rotating speed of the output shaft 22 in the
second-speed position established by the engaging actions of the
first clutch C1, switching brake B0 and first brake B1 is
represented by a point of intersection between an inclined straight
line L2 determined by those engaging actions and the vertical line
Y6 indicative of the rotating speed of the sixth rotary element RE6
fixed to the output shaft 22. The rotating speed of the output
shaft 22 in the third-speed position established by the engaging
actions of the first clutch C1, third clutch C3 and switching brake
B0 is represented by a point of intersection between an inclined
straight line L3 and the vertical line Y6 determined by those
engaging actions indicative of the rotating speed of the sixth
rotary element RE6 fixed to the output shaft 22. The rotating speed
of the output shaft 22 in the fourth-speed position established by
the engaging actions of the first clutch C1, second clutch C2 and
witching brake B0 is represented by a point of intersection between
the vertical line Y6 indicative of the rotating speed of the sixth
rotary element RE6 fixed to the output shaft 22 and an inclined
straight line L4 which passes a point of intersection between the
horizontal line X2 indicative of the rotating speed of the input
shaft 14 and the vertical line Y5 indicative of the rotating speed
of the fifth rotary element RE5, and a point of intersection
between the vertical line Y7 indicative of the rotating speed of
the seventh rotary element RE7 and the horizontal line X3. The
rotating speed of the output shaft 22 in the fifth-speed position
established by the engaging actions of the switching clutch C0 and
second clutch C2 is represented by a point of intersection between
straight line L5 aligned with the horizontal line X2 and the
vertical line Y6 indicative of the rotating speed of the sixth
rotary element RE6 fixed to the output shaft 22. The rotating speed
of the output shaft 22 in the sixth-speed position established by
the engaging actions of the second clutch C2, third clutch C3 and
switching brake B0 is represented by a point of intersection
between an inclined straight line L6 determined by those engaging
actions and the vertical line Y6 indicative of the rotating speed
of the sixth rotary element RE6 fixed to the output shaft 22. The
rotating speed of the output shaft 22 in the seventh-speed position
established by the engaging actions of the second clutch C2,
switching brake B0 and first brake B1 is represented by a point of
intersection between an inclined straight line L7 determined by
those engaging actions and the vertical line Y6 indicative of the
rotating speed of the sixth rotary element RE6 fixed to the output
shaft 22. The rotating speed of the output shaft 22 in the
reverse-gear position R established by the engaging actions of the
third clutch C3, switching brake B0 and second brake B2 is
represented by a point of intersection between an inclined straight
line LR determined by those engaging actions and the vertical line
Y6 indicative of the rotating speed of the sixth rotary element RE6
connected to the output shaft 22. It is noted that the switching
brake B0 need not be engaged to establish the seventh-speed
position shown in FIGS. 18 and 19, and that the first clutch C1 or
the third clutch C3 need not be engaged to establish the
fifth-speed position.
[0496] FIG. 20 is a table indicating shifting control operations of
the automatic transmission 86 of the drive system 80 when the power
distributing mechanism 84 is placed in the continuously-variable
shifting state. FIG. 21 is a collinear chart for explaining the
shifting control operations. In the continuously-variable shifting
state of the power distributing mechanism 84 which is established
by releasing actions of the switching clutch C0 and the switching
brake B0, the rotating speed of the first electric motor M1 is
variable over a wide range by controlling the reaction force of the
first electric motor M1. Namely, the rotating speed of the first
ring gear R1, that is, the rotating speed of the power transmitting
member 18 is changed over a range a midpoint of which is the engine
speed N.sub.E, as represented by a point of intersection between
the vertical line Y2 and a straight line L0 which is pivoted as
indicated by arrows about a point of intersection between the
horizontal line X2 and the vertical line Y3. As indicated in FIG.
21, the automatic transmission 86 is placed in the first-speed
position when the first clutch C1 and second brake B2 are engaged.
The rotating speed of the output shaft 22 in the first-speed
position is represented by a point of intersection between the
vertical line Y6 indicative of the rotating speed of the sixth
rotary element RE6 (R2, R3) fixed to the output shaft 22 and an
inclined straight line L1 which passes a point of intersection
between the vertical line Y7 indicative of the rotating speed of
the seventh rotary element RE7 (S3) and the horizontal line X3, and
a point of intersection between the vertical line Y5 indicative of
the rotating speed of the fifth rotary element RE5 (CA2, CA3) and
the horizontal line X1. Similarly, the rotating speed of the output
shaft 22 in the second-speed position established by the engaging
actions of the first clutch C1 and first brake B1 is represented by
a point of intersection between an inclined straight line L2
determined by those engaging actions and the vertical line Y6
indicative of the rotating speed of the sixth rotary element RE6
fixed to the output shaft 22. The rotating speed of the output
shaft 22 in the third-speed position established by the engaging
actions of the first clutch C1 and third clutch C3 is represented
by a point of intersection between an inclined straight line L3
determined by those engaging actions and the vertical line Y6
indicative of the rotating speed of the sixth rotary element RE6
fixed to the output shaft 22. Thus, the power distributing
mechanism 84 functions as a continuously-variable transmission
while the automatic transmission 86 connected in series to the
power distributing mechanism 86 functions as a step-variable
transmission, so that the speed of the rotary motion transmitted to
the automatic transmission 86 placed in one of the first-gear,
second-gear and third-gear positions, namely, the rotating speed of
the power transmitting member 18 is continuously changed, whereby
the speed ratio of the drive system when the automatic transmission
86 is placed in one of those gear positions is continuously
variable over a predetermined range. Accordingly, the speed ratio
of the automatic transmission 86 is continuously variable across
the adjacent gear positions, whereby the overall speed ratio
.gamma.T of the drive system 80 is continuously variable.
[0497] The drive system 80 of the present embodiment is also
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 72 functioning as the
step-variable shifting portion or second shifting portion, so that
the present drive system 80 has advantages similar to those of the
preceding embodiments.
Embodiment 5
[0498] FIG. 22 is a schematic view for explaining an arrangement of
a drive system 92 according to another embodiment of this
invention, and FIG. 23 is a table indicating gear positions of the
drive system 92 placed in the step-variable shifting state, and
different combinations of engaged states of the hydraulically
operated frictional coupling devices for respectively establishing
those gear positions, while FIG. 24 is a collinear chart for
explaining step-variable shifting operations of the drive system
92. FIG. 25 is a table indicating the gear positions of the drive
system 92 placed in the continuously-variable shifting state and
different combinations of engaged states of the hydraulically
operated frictional coupling devices for respectively establishing
those gear positions, and FIG. 26 is a collinear chart for
explaining continuously-variable shifting operations of the drive
system 92.
[0499] The drive system 92 includes a power distributing mechanism
94, which has a first planetary gear set 24 of single-pinion type
similar to that shown in FIG. 14, which has a gear ratio .rho.1 of
about 0.590, for example. The power distributing mechanism 94 has
the switching brake B0. The drive system 92 further includes an
automatic transmission 96 which has eight forward-drive positions
and which is interposed between and connected in series to the
power distributing mechanism 94 and the output shaft 22 through the
power transmitting member 18. While the power distributing
mechanism 94 in the present embodiment has the switching brake B0
operable to selectively fix the first sun gear S1 of the first
planetary gear set 24 to the transmission casing 12, the mechanism
94 does not have the switching clutch C0 operable to selectively
connect the first sun gear S1 and the first carrier CA1 to each
other. When the switch brake B0 is engaged, the rotating speed of
the first ring gear R1 is made higher than that of the first
carrier CA1, so that the power distributing mechanism 94 is placed
in a fixed-speed-ratio shifting state in which the mechanism 94
functions as a speed-increasing transmission having a fixed speed
ratio .gamma.0 of about 0.63, for example, which is lower than 1.
In the present embodiment therefore, the switching brake B0
functions as a differential-state switching device operable to
selectively place the power distributing mechanism 84 in the
continuously-variable shifting state in which the mechanism 84 is
operable as a continuously variable transmission the speed ratio
.gamma.0 of which is continuously variable, and the
fixed-speed-ratio shifting state in which the mechanism 84 is
operable as a transmission having a single gear position the speed
ratio .gamma.0 of which is lower than 1.
[0500] The automatic transmission 96 includes a double-pinion type
second planetary gear set 98 having a gear ratio .rho.2 of about
0.435, for example, and a single-pinion type third planetary gear
set 100 having a gear ratio .rho.3 of about 0.435, for example. The
double-pinion second planetary gear set 98 has a pair of pinions
P1, P2 which are rotatably supported by a second carrier CA2 and
which mesh with each other. The outer pinion P2 is formed
integrally with a pinion of the third planetary gear set 100. A
second ring gear R2 and the second carrier CA2 which mesh with the
pinion P2 are formed integrally with a third ring gear R3 and a
third carrier CA3 of the third planetary gear set 100. A second sun
gear S2 of the second planetary gear set 98 is selectively
connected to the power transmitting member 18 through a first
clutch C1, and selectively fixed to the transmission casing 12
through a first brake B1. A third sun gear S3 of the third
planetary gear set 100 is selectively connected to the power
transmitting member 18 through a second clutch C2, and selectively
connected to the input shaft 14 through a fourth clutch C4. The
second carrier CA2 and the third carrier CA3 are selectively
connected to the input shaft 14 through a third clutch C3, and
selectively fixed to the transmission casing 12 through a second
brake B2. The second ring gear R2 and the third ring gear R3 are
integrally fixed to the output shaft 22.
[0501] In the drive system 92 constructed as described above, one
of a first-gear position (first-speed position) through an
eighth-gear position (eighth-speed position), a reverse-gear
position (rear-drive position) and a neural position is selectively
established by engaging actions of a corresponding combination of
the frictional coupling devices selected from the above-described
first clutch C1, second clutch C2, third clutch C3, fourth clutch
C4, switching brake B0, first brake B1 and second brake B2, as
indicated in the table of FIG. 23. Those gear positions have
respective speed ratios .gamma. (input shaft speed N.sub.IN/output
shaft speed N.sub.OUT) which change as geometric series. In
particular, it is noted that the power distributing mechanism 94
provided with the switching brake B0 can be selectively placed by
engagement of the switching brake B0, in the fixed-speed-ratio
shifting state in which the mechanism 94 is operable as a
transmission having a single gear position with a single speed
ratio, as well as in the continuously-variable shifting state in
which the mechanism 94 is operable as a continuously variable
transmission, as described above. In the present drive system 92,
therefore, a step-variable transmission is constituted by the
automatic transmission 96, and the power distributing mechanism 94
which is placed in the fixed-speed-ratio shifting state by
engagement of the switching brake B0. Further, a continuously
variable transmission is constituted by the automatic transmission
96, and the power distributing mechanism 94 which is placed in the
continuously-variable shifting state established by a releasing
action of the switching brake B0.
[0502] Where the drive system 92 functions as the step-variable
transmission, for example, the first-gear position having the
highest speed ratio .gamma.1 of about 3.538, for example, is
established by engaging actions of the fourth clutch C1, switching
brake B0 and first brake B1, and the second-gear position having
the speed ratio .gamma.2 of about 2.226, for example, which is
lower than the speed ratio .gamma.1, is established by engaging
actions of the second clutch C2, switching brake B0 and first brake
B1, as indicated in FIG. 23. Further, the third-gear position
having the speed ratio .gamma.3 of about 1.769, for example, which
is lower than the speed ratio .gamma.2, is established by engaging
actions of the third clutch C3, switching brake B0 and first brake
B1, and the fourth-gear position having the speed ratio .gamma.4 of
about 1.345, for example, which is lower than the speed ratio
.gamma.3, is established by engaging actions of the second clutch
C2, third clutch C3 and switching brake B0. The fifth-gear position
having the speed ratio .gamma.5 of 1.000, which is lower than the
speed ration .gamma.4, is established by engaging actions of the
third clutch C3, fourth clutch C4 and switching brake B0. The
sixth-gear position having the speed ratio .gamma.6 of about 0.796,
for example, which is lower than the speed ratio .gamma.5, is
established by engaging actions of the first clutch C1, third
clutch C3 and switching brake B0. The seventh-gear position having
the speed ratio .gamma.7 of about 0.703, for example, which is
lower than the speed ratio .gamma.6, is established by engaging
actions of the first clutch C1, fourth clutch C4 and switching
brake B0, and the eighth-gear position having the speed ratio
.gamma.8 of about 0.629, for example, which is lower than the speed
ratio .gamma.7, is established by engaging actions of the first
clutch C1, second clutch C2 and switching brake B0. Further, the
reverse-gear position having the speed ratio .gamma.R of about
2.300, for example, which is intermediate between the speed ratios
.gamma.1 and .gamma.2, is established by engaging actions of the
fourth clutch C4, switching brake B0 and second brake B2.
[0503] Where the drive system 92 functions as the step-variable
transmission, on the other hand, the switching brake B0 is held in
the released state, as indicated in FIG. 25, so that the power
distributing mechanism 94 functions as the continuously variable
transmission, while the automatic transmission 96 connected in
series to the power distributing mechanism 94 functions as the
step-variable transmission having two forward-drive positions,
whereby the speed of the rotary motion transmitted to the automatic
transmission 96 placed in one of the second-gear and eighth-gear
positions, namely, the rotating speed of the power transmitting
member 18 is continuously changed, so that the speed ratio of the
drive system when the automatic transmission 96 is placed in one of
those gear positions is continuously variable over a predetermined
range. Accordingly, the speed ratio of the automatic transmission
96 is continuously variable across the adjacent gear positions,
whereby the overall speed ratio .gamma.T of the drive system 92 is
continuously variable.
[0504] The collinear chart of FIG. 24 indicates, by straight lines,
a relationship among the rotating speeds of the rotary elements in
each of the gear positions of the drive system 92 constituted by
the power distributing mechanism 94 and the automatic transmission
96, when the power distributing mechanism 94 is placed in the
step-variable shifting state established by the engaging action of
the switching brake B0.
[0505] In FIG. 24 similar to FIGS. 3 and 16, vertical lines Y1, Y2
and Y3 respectively indicate the rotating speeds of the first sun
gear S1 (second rotary element RE2), the first carrier CA1 (first
rotary element RE1) and the first ring gear R1 (third rotary
element RE2) of the first planetary gear set 24 of the power
distributing mechanism 94. In the step-variable shifting state, the
switching brake B0 is engaged to establish each of the gear
positions, and the rotating speed of the first sun gear S1 is
zeroed, while the rotating speed of the first carrier CA1 is made
equal to the engine speed N.sub.E, so that the relative rotating
speed of the first ring gear R1, that is, the relative rotating
speed of the power transmitting member 18 is represented by a point
of intersection between the vertical line Y3 and a straight line L0
which connects a point of intersection between the horizontal line
X1 and the vertical line Y1, and a point of intersection between
the vertical line Y2 and the horizontal line X2 indicative of the
engine speed N.sub.E. In this case, the relative rotating speed of
the power transmitting member 18 is higher than the engine speed
N.sub.E represented by the horizontal line X2, so that the power
distributing mechanism 94 functions as a speed increasing device.
For vertical lines Y4-Y7, the horizontal line X3 indicates the
increased rotating speed.
[0506] As shown in the collinear chart of FIG. 24, the automatic
transmission 96 is placed in the first-speed position when the
fourth clutch C4, switching brake B0 and first brake B1 are
engaged. The rotating speed of the output shaft 22 in the
first-speed position is represented by a point of intersection
between the vertical line Y6 indicative of the rotating speed of
the sixth rotary element RE6 (R2, R3) fixed to the output shaft 22
and an inclined straight line L1 which passes a point of
intersection between the vertical line Y4 indicative of the
rotating speed of the fourth rotary element RE4 (S3) and the
horizontal line X2, and a point of intersection between the
vertical line Y7 indicative of the rotating speed of the seventh
rotary element RE7 (S2) and the horizontal line X1. Similarly, the
rotating speed of the output shaft 22 in the second-speed position
established by the engaging actions of the second clutch C2,
switching brake B0 and first brake B1 is represented by a point of
intersection between an inclined straight line L2 determined by
those engaging actions and the vertical line Y6 indicative of the
rotating speed of the sixth rotary element RE6 fixed to the output
shaft 22. The rotating speed of the output shaft 22 in the
third-speed position established by the engaging actions of the
third clutch C3, switching brake B0 and first brake B1 is
represented by a point of intersection between an inclined straight
line L3 determined by those engaging actions and the vertical line
Y6 indicative of the rotating speed of the sixth rotary element RE6
fixed to the output shaft 22. The rotating speed of the output
shaft 22 in the fourth-speed position established by the engaging
actions of the second clutch C2, third clutch C3 and switching
brake B0 is represented by a point of intersection between an
inclined straight line L4 determined by those engaging actions and
the vertical line Y6 indicative of the rotating speed of the sixth
rotary element RE6 (R2, R3) fixed to the output shaft 22. The
rotating speed of the output shaft 22 in the fifth-speed position
established by the engaging actions of the third clutch c2, fourth
clutch C4 and switching brake B0 is represented by a point of
intersection between straight line L5 determined by those engaging
actions and the vertical line Y6 indicative of the rotating speed
of the sixth rotary element RE6 (R2, R3) fixed to the output shaft
22. The rotating speed of the output shaft 22 in the sixth-speed
position established by the engaging actions of the first clutch
C1, third clutch C3 and switching brake B0 is represented by a
point of intersection between an inclined straight line L6
determined by those engaging actions and the vertical line Y6
indicative of the rotating speed of the sixth rotary element RE6
(R2, R3) fixed to the output shaft 22. The rotating speed of the
output shaft 22 in the seventh-speed position established by the
engaging actions of the first clutch C1, fourth clutch C4 and
switching brake B0 is represented by a point of intersection
between an inclined straight line L7 determined by those engaging
actions and the vertical line Y6 indicative of the rotating speed
of the sixth rotary element RE6 (R2, R3) fixed to the output shaft
22. The rotating speed of the output shaft 22 in the eighth-speed
position established by the engaging actions of the first clutch
C1, second clutch C2 and switching brake B0 is represented by a
point of intersection between an inclined straight line L8
determined by those engaging actions and the vertical line Y6
indicative of the rotating speed of the sixth rotary element RE6
(R2, R3) fixed to the output shaft 22. The rotating speed of the
output shaft 22 in the reverse-gear position R established by the
engaging actions of the fourth clutch C4, switching brake B0 and
second brake B2 is represented by a point of intersection between
an inclined straight line LR determined by those engaging actions
and the vertical line Y6 indicative of the rotating speed of the
sixth rotary element RE6 connected to the output shaft 22. It is
noted that the switching brake B0 need not be engaged to establish
the first-speed position, third-speed position, fifth-speed
position and reverse-gear position R shown in FIGS. 23 and 24.
[0507] FIG. 25 is a table indicating shifting control operations of
the automatic transmission 96 of the drive system 92 when the power
distributing mechanism 94 is placed in the continuously-variable
shifting state. FIG. 26 is a collinear chart for explaining the
shifting control operations. In the continuously-variable shifting
state of the power distributing mechanism 94 which is established
by a releasing action of the switching brake B0, the rotating speed
of the first electric motor M1 is variable over a wide range by
controlling the reaction force of the first electric motor M1.
Namely, the rotating speed of the first ring gear R1, that is, the
rotating speed of the power transmitting member 18 is changed over
a range a midpoint of which is the engine speed N.sub.E, as
represented by a point of intersection between the vertical line Y3
and a straight line L0 which is pivoted as indicated by arrows
about a point of intersection between the horizontal line X2 and
the vertical line Y2. As indicated in FIG. 26, the automatic
transmission 96 is placed in a low-gear position when the second
clutch C2 and first brake B1 are engaged. The rotating speed of the
output shaft 22 in the low-gear position in the form of the
second-speed position is represented by a point of intersection
between the vertical line Y6 indicative of the rotating speed of
the sixth rotary element RE6 (R2, R3) fixed to the output shaft 22
and an inclined straight line L2 which passes a point of
intersection between the vertical line Y7 indicative of the
rotating speed of the seventh rotary element RE7 (S2) and the
horizontal line X1, and a point of intersection between the
vertical line Y4 indicative of the rotating speed of the fourth
rotary element RE4 (S3) and the horizontal line X3. Similarly, the
rotating speed of the output shaft 22 in a high-gear position in
the form of the eighth-speed position established by the engaging
actions of the first clutch C1 and second clutch C2 is represented
by a point of intersection between a horizontal straight line L8
and the vertical line Y6 indicative of the rotating speed of the
sixth rotary element RE6 fixed to the output shaft 22. In the
low-speed position of the automatic transmission 96, the straight
line L2 is pivoted to a position indicated by a broken line when
the straight line L0 is pivoted to a position indicated by a broken
line, so that the point of intersection of the straight line L2
with the vertical line Y6 is moved, whereby the rotating speed of
the output shaft 22 is continuously variable. Thus, the power
distributing mechanism 96 functions as a continuously-variable
transmission while the automatic transmission 96 connected in
series to the power distributing mechanism 94 functions as a
step-variable transmission having two gear positions consisting of
the low-speed position and the high-speed position, so that the
speed of the rotary motion transmitted to the automatic
transmission 96 placed in one of the second-speed and eighth-speed
positions, namely, the rotating speed of the power transmitting
member 18 is continuously changed, whereby the speed ratio of the
drive system when the automatic transmission 96 is placed in one of
those gear positions is continuously variable over a predetermined
range. Accordingly, the speed ratio of the automatic transmission
96 is continuously variable across the adjacent gear positions,
whereby the overall speed ratio .gamma.T of the drive system 92 is
continuously variable.
[0508] The drive system 92 of the present embodiment is also
constituted by the power distributing mechanism 94 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 96 functioning as the
step-variable shifting portion or second shifting portion, so that
the present drive system 92 has advantages similar to those of the
preceding embodiments.
Embodiment 6
[0509] FIG. 27 is a schematic view for explaining an arrangement of
a drive system 110 according to another embodiment of this
invention, and FIG. 28 is a table indicating gear positions of the
drive system 110, and different combinations of engaged states of
the hydraulically operated frictional coupling devices for
respectively establishing those gear positions, while FIG. 29 is a
collinear chart for explaining shifting operations of the drive
system 110. The present embodiment is different from the embodiment
shown in FIGS. 1-3 in that the first clutch C1 is not provided the
present embodiment, and in the manner of establishing a
reverse-gear position in the present embodiment. The following
description of the present embodiment primarily relates to a
difference between the drive system 110 and the drive system
10.
[0510] The drive system 110 includes a power distributing mechanism
16, which has a first planetary gear set 24 of single-pinion type
having a gear ratio .rho.1 of about 0.418, for example, and the
switching clutch C0 and the switching brake B0. The drive system
110 further includes an automatic transmission 112 which has four
forward-drive positions and which is interposed between and
connected in series to the power distributing mechanism 16 and the
output shaft 22 through the power transmitting member 18. The
automatic transmission 112 includes a second planetary gear set 26
of single-pinion type having a gear ratio .rho.2 of about 0.562,
for example, a third planetary gear set 28 of single-pinion type
having a gear ratio .rho.3 of about 0.425, for example, and a
fourth planetary gear set 30 of single-pinion type having a gear
ratio .rho.4 of about 0.421, for example.
[0511] In the automatic transmission 112, the first clutch C1
provided in the drive system 10 is not provided, so that the third
ring gear R3 and the fourth sun gear S4. which are selectively
connected to the power transmitting member 18 through the first
clutch C1 in the drive system 10, are integrally fixed to the power
transmitting member 18. Namely, the automatic transmission 112 is
arranged such that the second sun gear S2 and the third sun gear S3
are integrally fixed to each other, selectively connected to the
power transmitting member 18 through the second clutch C2, and
selectively fixed to the transmission casing 12 through the first
brake B1, and such that the second carrier CA2 is selectively fixed
to the transmission casing 12 through the second brake B2, while
the fourth ring gear R4 is selectively fixed to the transmission
casing 12 through the third brake B3. Further, the second ring gear
R2, third carrier CA3 and fourth carrier CA4 are integrally fixed
to the output shaft 22, and the third ring gear R3 and fourth sun
gear S4 are integrally fixed to the power transmitting member
18.
[0512] In the drive system 110 constructed as described above, one
of a first-gear position (first-speed position) through a
fifth-gear position (fifth-speed position), a reverse-gear position
(rear-drive position) and a neural position is selectively
established by engaging actions of a corresponding combination of
the frictional coupling devices selected from the above-described
switching clutch C0, second clutch C2, switching brake B0, first
brake B1, second brake B2 and third brake B3, as indicated in the
table of FIG. 28. Those gear positions have respective speed ratios
.gamma. (input shaft speed N.sub.IN/output shaft speed N.sub.OUT)
which change as geometric series. Although the present embodiment
does not use the first clutch C1 provided in the drive system 10,
the present drive system 110 has the first-speed position through
the fifth-speed position as in the drive system 10. In the drive
system 10, the first clutch C1 is engaged to establish the
first-speed position through the fifth-speed position, as is
apparent from the table of FIG. 2. In the present drive system 110,
however, the third ring gear R3 and the fourth sun gear S4 are
integrally fixed to the power transmitting member 18.
[0513] As in the drive system 10, the power distributing mechanism
16 is provided with the switching clutch C0 and brake B0, and can
be selectively placed by engagement of the switching clutch C0 or
switching brake B0, in the fixed-speed-ratio shifting state in
which the mechanism 16 is operable as a transmission having a
single gear position with one speed ratio or a plurality of gear
positions with respective speed ratios, as well as in the
continuously-variable shifting state in which the mechanism 16 is
operable as a continuously variable transmission, as described
above. In the present drive system 110, therefore, a step-variable
transmission is constituted by the automatic transmission 112, and
the power distributing mechanism 16 which is placed in the
fixed-speed-ratio shifting state by engagement of the switching
clutch C0 or switching brake B0. Further, a continuously variable
transmission is constituted by the automatic transmission 112, and
the power distributing mechanism 16 which is placed in the
continuously-variable shifting state, with none of the switching
clutch C0 and brake B0 being engaged.
[0514] Where the drive system 110 functions as the step-variable
transmission, for example, the first-gear position having the
highest speed ratio .gamma.1 of about 3.357, for example, is
established by engaging actions of the switching clutch C0 and
third brake B3, and the second-gear position having the speed ratio
.gamma.2 of about 2.180, for example, which is lower than the speed
ratio .gamma.1, is established by engaging actions of the switching
clutch C0 and second brake B2, as indicated in FIG. 28. Further,
the third-gear position having the speed ratio .gamma.3 of about
1.424, for example, which is lower than the speed ratio .gamma.2,
is established by engaging actions of the switching clutch C0 and
first brake B1, and the fourth-gear position having the speed ratio
.gamma.4 of about 1.000, for example, which is lower than the speed
ratio .gamma.3, is established by engaging actions of the switching
clutch C0 and second clutch C2, while the fifth-gear position
having the speed ratio .gamma.5 of about 0.705, for example, which
is lower than the speed ratio .gamma.4, is established by engaging
actions of the second clutch C2 and switching brake B0. Further,
the neutral position N is established by releasing all of the
switching clutch C0, second clutch C2, switching brake B0, first
brake B1, second brake B2 and third brake B3.
[0515] Where the drive system 110 functions as the
continuously-variable transmission, on the other hand, the
switching clutch C0 and the switching brake B0 are both released,
as indicated in FIG. 28, so that the power distributing mechanism
16 functions as the continuously variable transmission, while the
automatic transmission 112 connected in series to the power
distributing mechanism 16 functions as the step-variable
transmission, whereby the speed of the rotary motion transmitted to
the automatic transmission 112 placed in one of the first-gear,
second-gear, third-gear and fourth-gear positions, namely, the
rotating speed of the power transmitting member 18 is continuously
changed, so that the speed ratio of the drive system when the
automatic transmission 112 is placed in one of those gear positions
is continuously variable over a predetermined range. Accordingly,
the speed ratio of the automatic transmission 112 is continuously
variable across the adjacent gear positions, whereby the overall
speed ratio .gamma.T of the drive system 110 is continuously
variable.
[0516] In the embodiment shown in FIGS. 1-3, the reverse-gear
position is established by engaging the second clutch C2 and third
brake B3, and releasing the first clutch C1 to prevent transmission
of the rotary motion of the power transmitting member 18 to the
output shaft 22 due to the engagement of the second clutch C2,
which causes the rotary elements of the automatic transmission 20
to be rotated as a unit as in the fourth-gear and fifth-gear
positions. In the present embodiment, a reverse-gear or rear-drive
position is established by reversing the direction of rotation of
the power transmitting member 18 as transmitted to the automatic
transmission 112, with respect to the direction of rotation in the
first-gear through fifth-gear positions, without reversal of the
rotating direction of the power transmitting member 18 within the
automatic transmission 112. Namely, the present embodiment does not
use the first clutch C1 in the automatic transmission 112, to
establish the reverse-gear or rear-drive positions.
[0517] Described in detail, during an operation of the engine 8,
for example, the power distributing mechanism 16 operating as the
continuously variable transmission functions to reverse the
direction of rotation of the power transmitting member 18 with
respect to the operating direction of the engine 8, so that a
rotary motion of the power transmitting member 18 in the reverse
direction is transmitted to the automatic transmission 112. By
engaging the third brake B3, a rear-drive position in the form of a
first reverse-gear position having a desired speed ratio .lamda.R1
is established. The speed ratio .lamda.R1 may usually be set to be
about 3.209 as in the drive system 10 shown in FIGS. 1-3, but may
be changed by changing the rotating speed of the power transmitting
member 18 in the reverse direction, depending upon the vehicle
running condition, for instance, whether the roadway is flat,
uphill, or deteriorated of its surface condition. The speed ratio
.lamda.R1 of the reverse-drive position can be made higher than the
speed ratio .lamda.1 of the first-gear position, by lowering the
absolute value of the negative rotating speed of the power
transmitting member 18.
[0518] A second reverse-gear position may be provided in place of,
or in addition to the first reverse-gear position indicated above.
This second reverse-gear position is established by engaging the
second clutch C2 while rotary motion of the power transmitting
member 18 in the reverse direction is transmitted to the automatic
transmission 112. In this second reverse-gear position, the rotary
elements of the automatic transmission 112 are rotated as a unit,
so that the rotary motion of the power transmitting member 18 in
the reverse direction is transmitted to the output shaft 22. The
second reverse-gear position has a desired speed ratio
.lamda.R2.
[0519] The collinear chart of FIG. 29 indicates, by straight lines,
a relationship among the rotating speeds of the rotary elements in
each of the gear positions of the drive system 110, which is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 112 functioning as the
step-variable shifting portion or second shifting portion. The
rotating speeds of the individual rotary elements when the
switching clutch C0 and the switching brake B0 are in the released
state, and those when the switching clutch C0 or brake B0 is in the
engaged state, have been described above. The arrangements of the
fourth rotary element RE4 through the eighth rotary elements RE8 of
the automatic transmission 112 are the same as those of the
automatic transmission 20.
[0520] In the automatic transmission 112, the fourth rotary element
RE4 is selectively connected to the power transmitting member 18
through the second clutch C2, and selectively fixed to the
transmission casing 12 through the first brake B1, and the fifth
rotary element RE5 is selectively fixed to the transmission casing
12 through the second brake B2, while the sixth rotary element RE6
is selectively fixed to the transmission casing 12 through the
third brake B3. Further, the seventh rotary element RE7 is fixed to
the output shaft 22, and the eighth rotary element RE8 is fixed to
the power transmitting member 18.
[0521] As shown in the collinear chart of FIG. 29, the automatic
transmission 112 is placed in the first-speed position when the
third clutch C3 is engaged. The rotating speed of the output shaft
22 in the first-speed position is represented by a point of
intersection between the vertical line Y7 indicative of the
rotating speed of the seventh rotary element RE7 fixed to the
output shaft 22 and an inclined straight line L1 which passes a
point of intersection between the vertical line Y8 indicative of
the rotating speed of the eighth rotary element RE8 and the
horizontal line X2, and a point of intersection between the
vertical line Y6 indicative of the rotating speed of the sixth
rotary element RE6 and the horizontal line X1. Similarly, the
rotating speed of the output shaft 22 in the second-speed position
established by the engaging actions of the second brake B2 is
represented by a point of intersection between an inclined straight
line L2 determined by those engaging actions and the vertical line
Y7 indicative of the rotating speed of the seventh rotary element
RE7 fixed to the output shaft 22. The rotating speed of the output
shaft 22 in the third-speed position established by the engaging
actions of the first brake B1 is represented by a point of
intersection between an inclined straight line L3 determined by
those engaging actions and the vertical line Y7 indicative of the
rotating speed of the seventh rotary element RE7 fixed to the
output shaft 22. The rotating speed of the output shaft 22 in the
fourth-speed position established by the engaging actions of the
second brake C2 is represented by a point of intersection between
an inclined straight line L4 determined by those engaging actions
and the vertical line Y7 indicative of the rotating speed of the
seventh rotary element RE7 fixed to the output shaft 22. In the
first-speed through fourth-speed positions in which the switching
clutch C0 is engaged, the rotary motion of the power distributing
mechanism 16 at the same speed as the engine speed N.sub.E is
transmitted to the eighth rotary element RE8. When the switching
brake B0 is engaged in place of the switching clutch C0, the rotary
motion of the power distributing mechanism 16 at a speed higher
than the engine speed N.sub.E is transmitted to the eighth rotary
element. The rotating speed of the output shaft 22 in the fifth
speed position established by the engaging actions of the second
clutch C2 and switching brake B0 is represented by a point of
intersection between a horizontal straight line L5 determined by
those engaging actions and the vertical line Y7 indicative of the
rotating speed of the seventh rotary element RE7 fixed to the
output shaft 22.
[0522] When the switching clutch C0 and the switching brake B0 are
both released, the rotary motion of the power distributing
mechanism 16 transmitted to the eighth rotary element RE8 is
continuously variable with respect to the engine speed N.sub.E.
When the direction of the rotary motion to be transmitted to the
eighth rotary element RE8 is reversed, in this state, by the power
distributing mechanism 16 with respect to the operating direction
of the engine 8, as indicated by a straight line L0R1, the rotating
speed of the output shaft 22 in the first reverse-gear position
having a speed ratio Rev1 established by the engaging action of the
third brake B3 is represented by a point of intersection between an
inclined straight line LR1 determined by that engaging action and
the vertical line Y7 indicative of the rotating speed of the
seventh rotary element RE7 fixed to the output shaft 22. When the
direction of the rotary motion to be transmitted to the eighth
rotary element RE8 is reversed with respect to the operating
direction of the engine 8, as indicated by a straight line L0R2,
while the power distributing mechanism 16 is placed in the
continuously-variable shifting state, the rotating speed of the
output shaft 22 in the second reverse-gear position having a speed
ratio Rev2 established by the engaging action of the second clutch
C2 is represented by a point of intersection of a horizontal
straight line LR2 determined by that engaging action and the
vertical line Y7 indicative of the rotating direction of the
seventh rotary element RE7 fixed to the output shaft 22.
[0523] In the present embodiment, too, the drive system 110 is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 112 functioning as the
step-variable shifting portion or second shifting portion, so that
the present drive system 110 has advantages similar to those of the
preceding embodiments. The present embodiment has a further
advantage that the drive system 110 is small-sized and has a
reduced axial dimension, owing to the elimination of the first
clutch C1 provided in the embodiment shown in FIGS. 1-3.
[0524] The drive system 110 of the present embodiment is further
arranged such that the direction of the rotary motion of the power
transmitting member 18 transmitted to the automatic transmission
112 in the rear-drive position is reversed with respect to that in
the first-gear through fifth-gear positions. Accordingly, the
automatic transmission 112 is not required to be provided with
coupling devices or gear devices for reversing the direction of
rotation of the output shaft 22 with respect to that of the input
rotary motion, for establishing the reverse-gear position for the
rotary motion of the output shaft 22 in the direction opposite to
that in the forward-drive positions. Thus, the rear-drive position
can be established in the absence of the first clutch C1 in the
automatic transmission, so that the drive system can be
small-sized. Further, in the rear-drive position, the speed of the
output rotary motion of the automatic transmission 112 is made
lower than or equal to that of the input rotary motion received
from the power distributing mechanism 16 the speed ratio of which
is continuously variable in the engaged state of the third brake B3
or second clutch C2. Accordingly, the rear-drive position has a
desired speed ratio .lamda.R, which may be higher than that of the
first-gear position.
Embodiment 7
[0525] FIG. 30 is a schematic view for explaining an arrangement of
a drive system 120 according to another embodiment of this
invention, and FIG. 31 is a table indicating gear positions of the
drive system 120, and different combinations of engaged states of
the hydraulically operated frictional coupling devices for
respectively establishing those gear positions, while FIG. 32 is a
collinear chart for explaining shifting operations of the drive
system 120. The present embodiment is different from the embodiment
shown in FIGS. 1-3, primarily in that the power distributing
mechanism 16 and the automatic transmission 20 are not disposed
coaxially with each other in the present embodiment. The following
description of the present embodiment primarily relates to a
difference between the drive system 120 and the drive system
10.
[0526] The drive system 120 shown in FIG. 30 is provided, within a
casing 12 attached to the vehicle body, with: an input shaft 14
disposed rotatably about a first axis 14c; the power distributing
mechanism 16 mounted on the input shaft 14 directly, or indirectly
through a pulsation absorbing damper (vibration damping device);
the automatic transmission 20 disposed rotatably about a second
axis 32c parallel to the first axis 14c; an output rotary member in
the form of a differential drive gear 32 connected to the automatic
transmission 20; and a power transmitting member in the form of a
counter gear pair CG which connects the power distributing
mechanism 16 and the automatic transmission 20, so as to transmit a
drive force therebetween. This drive system 120 is suitably used on
a transverse FF (front-engine, front-drive) vehicle or a transverse
RR (rear-engine, rear-drive) vehicle, and is disposed between a
drive power source in the form of an engine 8 and a pair of drive
wheels 38. The drive force is transmitted from the differential
drive gear 32 to the pair of drive wheels 38, through a
differential gear 34 meshing with the differential drive gear 32, a
differential gear device 36, a pair of drive axles 37, etc.
[0527] The counter gear pair CG indicated above consists of a
counter drive gear CG1 disposed rotatably on the first axis 14c and
coaxially with the power distributing mechanism 16 and fixed to a
first ring gear R1, and a counter driven gear CG2 disposed
rotatably on the second axis 32c and coaxially with the automatic
transmission 20 and connected to the automatic transmission 20
through a first clutch C1 and a second clutch C2. The counter drive
gear CG1 and the counter driven gear CG2 serve as a pair of members
in the form of a pair of gears which are held in meshing engagement
with each other. Since the speed reduction ratio of the counter
gear pair CG (rotating speed of the counter drive gear CG1/rotating
speed of the counter driven gear CG2) is about 1.000, the counter
gear pair CG functionally corresponds to the power transmitting
member 18 in the embodiment shown in FIGS. 1-3, which connects the
power distributing mechanism 16 and the automatic transmission 20.
That is, the counter drive gear CG1 corresponds to a power
transmitting member which constitutes a part of the power
transmitting member 18 on the side of the first axis 14c, while the
counter driven gear CG2 corresponds to a power transmitting member
which constitutes another part of the power transmitting member 18
on the side of the second axis 32c.
[0528] Referring to FIG. 30, the individual elements of the drive
system 120 will be described. The counter gear pair CG is disposed
adjacent to one end of the power distributing mechanism 16 which
remote from the engine 8. In other words, the power distributing
mechanism 16 is interposed between the engine 8 and the counter
gear pair CG, and located adjacent to the counter gear pair CG. A
second electric motor M2 is disposed on the first axis 14c, between
a first planetary gear set 24 and the counter gear pair CG, such
that the second electric motor M2 is fixed to the counter drive
gear CG1. The differential drive gear 32 is disposed adjacent to
one end of the automatic transmission 20 which is remote from the
counter gear pair CG, that is, on the side of the engine 8. In
other words, the automatic transmission 20 is interposed between
the counter gear pair CG and the differential drive gear 32 (engine
8), and located adjacent to the counter gear pair CG. Between the
counter gear pair CG and the differential drive gear 32, a second
planetary gear set 26, a third planetary gear set 28 and a fourth
planetary gear set 30 are disposed in the order of description, in
the direction from the counter gear pair CG toward the differential
drive gear 32. The first clutch C1 and the second clutch C2 are
disposed between the counter gear pair CG and the second planetary
gear set 26.
[0529] The present embodiment is different from the embodiment
shown in FIGS. 1-3, only in that the counter gear pair CG replaces
the power transmitting member 18 connecting the power distributing
mechanism 16 and the automatic transmission 20, and is identical
with the embodiment of FIGS. 1-3 in the arrangements of the power
distributing mechanism 16 and automatic transmission 20.
Accordingly, the table of FIG. 31 and the collinear chart of FIG.
32 are the same as the table of FIG. 2 and the collinear chart of
FIG. 3, respectively.
[0530] In the present embodiment, too, the drive system 120 is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 20 functioning as the
step-variable shifting portion or second shifting portion, so that
the drive system 120 has advantages similar to those of the
preceding embodiments. Unlike the embodiment shown in FIGS. 1-3,
the present embodiment is arranged such that the power distributing
mechanism 16 and the automatic transmission 20 are not disposed
coaxially with each other, so that the required dimension of the
drive system 120 in the axial direction can be reduced.
Accordingly, the present drive system can be suitably used on a
transversal FF or RR vehicle such that the first and second axes
14c, 32c are parallel to the transverse or width direction of the
vehicle. In this respect, it is noted that the maximum axial
dimension of a drive system for such a transverse FF or RR vehicle
is generally limited by the width dimension of the vehicle. The
present embodiment has an additional advantage that the required
axial dimension of the drive system 120 can be further reduced,
since the power distributing mechanism 16 and the automatic
transmission 20 are located between the engine 8 (differential
drive gear 32) and the counter gear pair CG. Further, the required
axial dimension of the second axis 32c can be reduced owing to the
arrangement in which the second electric motor M2 is disposed on
the first axis 13c.
Embodiment 8
[0531] FIG. 33 is a schematic view for explaining an arrangement of
a drive system 130 according to another embodiment of this
invention. This embodiment is different from the embodiment shown
in FIGS. 30-32, in the position of the second electric motor M2.
Referring to FIG. 33, the positional arrangement of the second
electric motor M2 will be described. The second electric motor M2
is located between an assembly of the first and second clutches C1,
C2 and the counter gear pair CG, and disposed on the second axis
32c, and adjacent to the counter gear pair CG, such that the second
electric motor M2 is fixed to the counter driven gear CG2 serving
as the power transmitting member on the side of the second axis
32c. The arrangements of the power distributing mechanism 16 and
the automatic transmission 20 are identical with those of the
embodiment of FIGS. 30-32. Accordingly, the table of FIG. 31 and
the collinear chart of FIG. 32 apply to the present embodiment of
FIG. 33.
[0532] In the present embodiment, too, the drive system 130 is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 20 functioning as the
step-variable shifting portion or second shifting portion, so that
the drive system 130 has advantages similar to those of the
preceding embodiments. Unlike the embodiment shown in FIGS. 1-3,
the present embodiment is arranged such that the power distributing
mechanism 16 and the automatic transmission 20 are not disposed
coaxially with each other, so that the required dimension of the
drive system 130 in the axial direction can be reduced.
Accordingly, the present drive system can be suitably used on a
transversal FF or RR vehicle such that the first and second axes
14c, 32c are parallel to the transverse or width direction of the
vehicle. In this respect, it is noted that the maximum axial
dimension of a drive system for such a transverse FF or RR vehicle
is generally limited by the width dimension of the vehicle. The
present embodiment has an additional advantage that the required
axial dimension of the drive system 130 can be further reduced,
since the power distributing mechanism 16 and the automatic
transmission 20 are located between the engine 8 (differential
drive gear 32) and the counter gear pair CG. Further, the required
axial dimension of the second axis 32c can be reduced owing to the
arrangement in which the second electric motor M2 is disposed on
the first axis 13c.
Embodiment 9
[0533] FIG. 34 is a schematic view for explaining an arrangement of
a drive system 140 according to another embodiment of this
invention. This embodiment is different from the embodiment shown
in FIGS. 30-32, in the positions of the second electric motor M2
and the first and second clutches C1, C2. Referring to FIG. 34, the
positional arrangements of the second electric motor M2 and the
clutches C1, C2 will be described. The second electric motor M2 is
located on one side of the counter gear pair CG which is remote
from the first planetary gear set 24, and disposed on the first
axis 14c, and adjacent to the counter gear pair CG, such that the
second electric motor M2 is fixed to the counter drive gear CG1
serving as the power transmitting member on the side of the first
axis 14c. The first clutch C1 and the second clutch C2 are located
on one side of the counter gear pair CG which is remote from the
second planetary gear set 26, and disposed on the second axis 32c,
and adjacent to the counter gear pair CG. The arrangements of the
power distributing mechanism 16 and the automatic transmission 20
are identical with those of the embodiment shown in FIGS. 30-32.
Accordingly, the table of FIG. 31 and the collinear chart of FIG.
32 apply to the present embodiment of FIG. 34.
[0534] In the present embodiment, too, the drive system 140 is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 20 functioning as the
step-variable shifting portion or second shifting portion, so that
the drive system 140 has advantages similar to those of the
preceding embodiments. Unlike the embodiment shown in FIGS. 1-3,
the present embodiment is arranged such that the power distributing
mechanism 16 and the automatic transmission 20 are not disposed
coaxially with each other, so that the required dimension of the
drive system 140 in the axial direction can be reduced.
Accordingly, the present drive system can be suitably used on a
transversal FF or RR vehicle such that the first and second axes
14c, 32c are parallel to the transverse or width direction of the
vehicle. In this respect, it is noted that the maximum axial
dimension of a drive system for such a transverse FF or RR vehicle
is generally limited by the width dimension of the vehicle.
Further, the required axial dimension of the second axis 32c can be
reduced owing to the arrangement in which the second electric motor
M2 is disposed on the first axis 13c.
Embodiment 10
[0535] FIG. 35 is a schematic view for explaining an arrangement of
a drive system 150 according to another embodiment of this
invention, and
[0536] FIG. 36 is a table indicating gear positions of the drive
system 150, and different combinations of engaged states of the
hydraulically operated frictional coupling devices for respectively
establishing those gear positions, while FIG. 37 is a collinear
chart for explaining shifting operations of the drive system 150.
The present embodiment is different from the embodiment shown in
FIGS. 27-29, primarily in that the power distributing mechanism 16
and the automatic transmission 20 are not disposed coaxially with
each other in the present embodiment, and is different from the
embodiment shown in FIGS. 30-32, in that the first clutch C1 is not
provided in the present embodiment, and in the manner of
establishing a reverse-gear position in the present embodiment.
[0537] The present embodiment is different from the embodiment
shown in FIGS. 27-29, only in that the counter gear pair CG
replaces the power transmitting member 18 connecting the power
distributing mechanism 16 and the automatic transmission 112, and
is identical with the embodiment shown in FIGS. 1-3 in the
arrangements of the power distributing mechanism 16 and automatic
transmission 20, including the means for establishing the
reverse-gear positions. Accordingly, the table of FIG. 36 and the
collinear chart of FIG. 37 are the same as the table of FIG. 28 and
the collinear chart of FIG. 29, respectively. Further, the
arrangement of the drive system 150 shown in FIG. 35 and the
arrangement of the counter gear pair CG (corresponding to the power
transmitting member 18 of FIG. 27) are identical with those of the
embodiment shown FIG. 30, except for the elimination of the first
clutch C1.
[0538] In the present embodiment, too, the drive system 150 is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 112 functioning as the
step-variable shifting portion or second shifting portion, so that
the drive system 150 has advantages similar to those of the
preceding embodiments. Unlike the embodiment shown in FIGS. 27-29,
the present embodiment is arranged such that the power distributing
mechanism 16 and the automatic transmission 112 are not disposed
coaxially with each other, so that the required dimension of the
drive system 150 in the axial direction can be reduced.
Accordingly, the present drive system can be suitably used on a
transversal FF or RR vehicle such that the first and second axes
14c, 32c are parallel to the transverse or width direction of the
vehicle. In this respect, it is noted that the maximum axial
dimension of a drive system for such a transverse FF or RR vehicle
is generally limited by the width dimension of the vehicle. The
present embodiment has an additional advantage that the required
axial dimension of the drive system 150 can be further reduced,
since the power distributing mechanism 16 and the automatic
transmission 112 are located between the engine 8 (differential
drive gear 32) and the counter gear pair CG. Further, the required
axial dimension of the second axis 32c can be reduced owing to the
arrangement in which the second electric motor M2 is disposed on
the first axis 13c.
Embodiment 11
[0539] FIG. 38 is a schematic view for explaining an arrangement of
a drive system 160 according to another embodiment of this
invention. This embodiment is different from the embodiment shown
in FIGS. 35-37, in the positions of the second electric motor M2
and the second clutch C2. Referring to FIG. 38, the positional
arrangements of the second electric motor M2 and the second clutch
C2 will be described. The second electric motor M2 is located on
one side of the counter gear pair CG which is remote from the first
planetary gear set 24, and disposed on the first axis 14c, and
adjacent to the counter gear pair CG, such that the second electric
motor M2 is fixed to the counter drive gear CG1 serving as the
power transmitting member on the side of the first axis 14c. The
second clutch C2 is located on one side of the counter gear pair CG
which is remote from the second planetary gear set 26, and disposed
on the second axis 32c, and adjacent to the counter gear pair CG.
The arrangements of the power distributing mechanism 16 and the
automatic transmission 112 are identical with those of the
embodiment shown in FIGS. 35-37. Accordingly, the table of FIG. 36
and the collinear chart of FIG. 37 apply to the present embodiment
of FIG. 38.
[0540] In the present embodiment, too, the drive system 160 is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 112 functioning as the
step-variable shifting portion or second shifting portion, so that
the drive system 160 has advantages similar to those of the
preceding embodiments. Unlike the embodiment shown in FIGS. 27-29,
the present embodiment is arranged such that the power distributing
mechanism 16 and the automatic transmission 112 are not disposed
coaxially with each other, so that the required dimension of the
drive system 160 in the axial direction can be reduced.
Accordingly, the present drive system can be suitably used on a
transversal FF or RR vehicle such that the first and second axes
14c, 32c are parallel to the transverse or width direction of the
vehicle. In this respect, it is noted that the maximum axial
dimension of a drive system for such a transverse FF or RR vehicle
is generally limited by the width dimension of the vehicle.
Further, the required axial dimension of the second axis 32c can be
reduced owing to the arrangement in which the second electric motor
M2 is disposed on the first axis 13c.
Embodiment 12
[0541] FIG. 39 is a schematic view for explaining an arrangement of
a drive system 170 according to another embodiment of this
invention, and FIG. 40 is a table indicating gear positions of the
drive system 170, and different combinations of engaged states of
the hydraulically operated frictional coupling devices for
respectively establishing those gear positions, while FIG. 41 is a
collinear chart for explaining shifting operation of the drive
system 170. The present embodiment is different from the embodiment
shown in FIGS. 14-16 in that the first clutch C1 is not provided
the present embodiment, and in the manner of establishing a
reverse-gear position in the present embodiment. The following
description of the present embodiment primarily relates to a
difference between the drive system 170 and the drive system
70.
[0542] Like the drive system 70, the drive system 170 includes the
power distributing mechanism 16, which has the first planetary gear
set 24 of single-pinion type having a gear ratio .rho.1 of about
0.418, for example, and the switching clutch C0 and the switching
brake B0. The drive system 170 further includes an automatic
transmission 172 which has three forward-drive positions and which
is interposed between and connected in series to the power
distributing mechanism 16 and the output shaft 22 through the power
transmitting member 18. The automatic transmission 172 includes a
single-pinion type second planetary gear set 26 having a gear ratio
.rho.2 of about 0.532, for example, and a single-pinion type third
planetary gear set 28 having a gear ratio .rho.3 of about 0.418,
for example.
[0543] In the automatic transmission 170, the first clutch C1
provided in the drive system 70 is not provided, so that the second
ring gear R2, which is selectively connected to the power
transmitting member 18 through the first clutch C1 in the drive
system 70, is integrally fixed to the power transmitting member 18.
Namely, the automatic transmission 172 is arranged such that the
second sun gear S2 of the second planetary gear set 26 and the
third sun gear S3 of the third planetary gear set 28 are integrally
fixed to each other, selectively connected to the power
transmitting member 18 through the second clutch C2, and
selectively fixed to the transmission casing 12 through the first
brake B1, and such that the second carrier CA2 of the second
planetary gear set 24 and the third ring gear R3 of the third
planetary gear set 28 are integrally fixed to each other and to the
output shaft 22. Further, the second ring gear R2 is fixed to the
power transmitting member 18, and the third carrier CA3 is
selectively fixed to the transmission casing 12 through the second
brake B2.
[0544] In the drive system 170 constructed as described above, one
of a first-gear position (first-speed position) through a
fourth-gear position (fourth-speed position), a reverse-gear
position (rear-drive position) and a neural position is selectively
established by engaging actions of a corresponding combination of
the frictional coupling devices selected from the above-described
switching clutch C0, second clutch C2, switching brake B0, first
brake B1 and second brake B2, as indicated in the table of FIG. 40.
Those gear positions have respective speed ratios .gamma. (input
shaft speed N.sub.IN/output shaft speed N.sub.OUT) which change as
geometric series. Although the present embodiment does not use the
first clutch C1 provided in the drive system 70, the present drive
system 170 has the first-speed position through the fourth-speed
position as in the drive system 70. In the drive system 70, the
first clutch C1 is engaged to establish the first-speed position
through the fourth-speed position, as is apparent from the table of
FIG. 15. In the present drive system 170, however, the second ring
gear R2 is integrally fixed to the power transmitting member
18.
[0545] As in the drive system 70, the power distributing mechanism
16 is provided with the switching clutch C0 and brake B0, and can
be selectively placed by engagement of the switching clutch C0 or
switching brake B0, in the fixed-speed-ratio shifting state in
which the mechanism 16 is operable as a transmission having a
single gear position with one speed ratio or a plurality of gear
positions with respective speed ratios, as well as in the
continuously-variable shifting state in which the mechanism 16 is
operable as a continuously variable transmission, as described
above. In the present drive system 170, therefore, a step-variable
transmission is constituted by the automatic transmission 112, and
the power distributing mechanism 16 which is placed in the
fixed-speed-ratio shifting state by engagement of the switching
clutch C0 or switching brake B0. Further, a continuously variable
transmission is constituted by the automatic transmission 112, and
the power distributing mechanism 16 which is placed in the
continuously-variable shifting state, with none of the switching
clutch C0 and brake B0 being engaged.
[0546] Where the drive system 170 functions as the step-variable
transmission, for example, the first-gear position having the
highest speed ratio .gamma.1 of about 2.804, for example, is
established by engaging actions of the switching clutch C0 and
second brake B3, and the second-gear position having the speed
ratio .gamma.2 of about 1.531, for example, which is lower than the
speed ratio .gamma.1, is established by engaging actions of the
switching clutch C0 and first brake B1, as indicated in FIG. 39.
Further, the third-gear position having the speed ratio .gamma.3 of
about 1.000, for example, which is lower than the speed ratio
.gamma.2, is established by engaging actions of the switching
clutch C0 and second clutch C2, and the fourth-gear position having
the speed ratio .gamma.4 of about 0.705, for example, which is
lower than the speed ratio .gamma.3, is established by engaging
actions of the second clutch C1 and switching brake B0. Further,
the neutral position N is established by releasing all of the
switching clutch C0, second clutch C2, switching brake B0, first
brake B1 and second brake B2.
[0547] Where the drive system 170 functions as the
continuously-variable transmission, on the other hand, the
switching clutch C0 and the switching brake B0 are both released,
as indicated in FIG. 40, so that the power distributing mechanism
16 functions as the continuously variable transmission, while the
automatic transmission 172 connected in series to the power
distributing mechanism 16 functions as the step-variable
transmission, whereby the speed of the rotary motion transmitted to
the automatic transmission 112 placed in one of the first-gear,
second-gear and third-gear positions, namely, the rotating speed of
the power transmitting member 18 is continuously changed, so that
the speed ratio of the drive system when the automatic transmission
172 is placed in one of those gear positions is continuously
variable over a predetermined range. Accordingly, the speed ratio
of the automatic transmission 172 is continuously variable across
the adjacent gear positions, whereby the overall speed ratio
.gamma.T of the drive system 170 is continuously variable.
[0548] In the embodiment shown FIGS. 14-16, the reverse-gear
position is established by engaging the second clutch C2 and second
brake B2, and releasing the second clutch C2 to prevent
transmission of the rotary motion of the power transmitting member
18 to the output shaft 22 due to the engagement of the second
clutch C2, which causes the rotary elements of the automatic
transmission 72 to be rotated as a unit as in the third-gear and
fourth-gear positions. In the present embodiment, a reverse-gear or
rear-drive position is established by reversing the direction of
rotation of the power transmitting member 18 as transmitted to the
automatic transmission 112, with respect to the direction of
rotation in the first-gear through fourth-gear positions, without
reversal of the rotating direction of the power transmitting member
18 within the automatic transmission 172. Namely, the present
embodiment does not use the first clutch C1 in the automatic
transmission 172, to establish the reverse-gear or rear-drive
positions.
[0549] Described in detail, during an operation of the engine 8,
for example, the power distributing mechanism 16 operating as the
continuously variable transmission functions to reverse the
direction of rotation of the power transmitting member 18 with
respect to the operating direction of the engine 8, so that a
rotary motion of the power transmitting member 18 in the reverse
direction is transmitted to the automatic transmission 172. By
engaging the second brake B2, a rear-drive position in the form of
a first reverse-gear position having a desired speed ratio
.lamda.R1 is established. The speed ratio .lamda.R1 may usually be
set to be about 2.393 as in the drive system 70 shown in FIGS.
14-16, but may be changed by changing the rotating speed of the
power transmitting member 18 in the reverse direction, depending
upon the vehicle running condition, for instance, whether the
roadway is flat, uphill, or deteriorated of its surface condition.
The speed ratio .lamda.R1 of the reverse-drive position can be made
higher than the speed ratio .lamda.1 of the first-gear position, by
lowering the absolute value of the negative rotating speed of the
power transmitting member 18.
[0550] A second reverse-gear position may be provided in place of,
or in addition to the first reverse-gear position indicated above.
This second reverse-gear position is established by engaging the
second clutch C2 while rotary motion of the power transmitting
member 18 in the reverse direction is transmitted to the automatic
transmission 172. In this second reverse-gear position, the rotary
elements of the automatic transmission 172 are rotated as a unit,
so that the rotary motion of the power transmitting member 18 in
the reverse direction is transmitted to the output shaft 22. The
second reverse-gear position has a desired speed ratio
.lamda.R2.
[0551] The collinear chart of FIG. 41 indicates, by straight lines,
a relationship among the rotating speeds of the rotary elements in
each of the gear positions of the drive system 170, which is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 172 functioning as the
step-variable shifting portion or second shifting portion. The
rotating speeds of the individual rotary elements when the
switching clutch C0 and the switching brake B0 are in the released
state, and those when the switching clutch C0 or brake B0 is in the
engaged state, have been described above. The arrangements of the
fourth rotary element RE4 through the seventh rotary elements RE7
of the automatic transmission 172 are the same as those of the
automatic transmission 72.
[0552] In the automatic transmission 172, the fourth rotary element
RE4 is selectively connected to the power transmitting member 18
through the second clutch C2, and selectively fixed to the
transmission casing 12 through the first brake B1, and the fifth
rotary element RE5 is selectively fixed to the transmission casing
12 through the second brake B2. Further, the sixth rotary element
RE6 is fixed to the output shaft 22, and the seventh rotary element
RE7 is fixed to the power transmitting member 18.
[0553] As shown in the collinear chart of FIG. 41, the automatic
transmission 172 is placed in the first-speed position when the
second brake B2 is engaged. The rotating speed of the output shaft
22 in the first-speed position is represented by a point of
intersection between the vertical line Y6 indicative of the
rotating speed of the sixth rotary element RE6 fixed to the output
shaft 22 and an inclined straight line L1 which passes a point of
intersection between the vertical line Y7 indicative of the
rotating speed of the seventh rotary element RE7 and the horizontal
line X2, and a point of intersection between the vertical line Y5
indicative of the rotating speed of the fifth rotary element RE5
and the horizontal line X1. Similarly, the rotating speed of the
output shaft 22 in the second-speed position established by the
engaging actions of the first brake B1 is represented by a point of
intersection between an inclined straight line L2 determined by
those engaging actions and the vertical line Y6 indicative of the
rotating speed of the sixth rotary element RE6 fixed to the output
shaft 22. The rotating speed of the output shaft 22 in the
third-speed position established by the engaging actions of the
second clutch C2 is represented by a point of intersection between
an inclined straight line L3 determined by those engaging actions
and the vertical line Y6 indicative of the rotating speed of the
sixth rotary element RE6 fixed to the output shaft 22. In the
first-speed through third-speed positions in which the switching
clutch C0 is engaged, the rotary motion of the power distributing
mechanism 16 at the same speed as the engine speed N.sub.E is
transmitted to the seventh rotary element RE7. When the switching
brake B0 is engaged in place of the switching clutch C0, the rotary
motion of the power distributing mechanism 16 at a speed higher
than the engine speed N.sub.E is transmitted to the seventh rotary
element. The rotating speed of the output shaft 22 in the
fourth-speed position established by the engaging actions of the
second clutch C2 and switching brake B0 is represented by a point
of intersection between a horizontal straight line L4 determined by
those engaging actions and the vertical line Y6 indicative of the
rotating speed of the sixth rotary element RE6 fixed to the output
shaft 22.
[0554] When the switching clutch C0 and the switching brake B0 are
both released, the rotary motion of the power distributing
mechanism 16 transmitted to the seventh rotary element RE7 is
continuously variable with respect to the engine speed N.sub.E.
When the direction of the rotary motion to be transmitted to the
seventh rotary element RE7 is reversed, in this state, by the power
distributing mechanism 16 with respect to the operating direction
of the engine 8, as indicated by a straight line L0R1, the rotating
speed of the output shaft 22 in the first reverse-gear position
having a speed ratio Rev1 established by the engaging action of the
second brake B2 is represented by a point of intersection between
an inclined straight line LR1 determined by that engaging action
and the vertical line Y6 indicative of the rotating speed of the
sixth rotary element RE6 fixed to the output shaft 22. When the
direction of the rotary motion to be transmitted to the seventh
rotary element RE7 is reversed with respect to the operating
direction of the engine 8, as indicated by a straight line L0R2,
while the power distributing mechanism 16 is placed in the
continuously-variable shifting state, the rotating speed of the
output shaft 22 in the second reverse-gear position having a speed
ratio Rev 2 established by the engaging action of the second clutch
C2 is represented by a point of intersection of a horizontal
straight line LR2 determined by that engaging action and the
vertical line Y6 indicative of the rotating direction of the sixth
rotary element RE6 fixed to the output shaft 22.
[0555] In the present embodiment, too, the drive system 170 is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 172 functioning as the
step-variable shifting portion or second shifting portion, so that
the present drive system 170 has advantages similar to those of the
preceding embodiments. The present embodiment has a further
advantage that the drive system 170 is small-sized and has a
reduced axial dimension, owing to the elimination of the first
clutch C1 provided in the embodiment shown in FIGS. 14-16.
[0556] The drive system 170 of the present embodiment is further
arranged such that the direction of the rotary motion of the power
transmitting member 18 transmitted to the automatic transmission
172 in the rear-drive position is reversed with respect to that in
the first-gear through fourth-gear positions. Accordingly, the
automatic transmission 172 is not required to be provided with
coupling devices or gear devices for reversing the direction of
rotation of the output shaft 22 with respect to that of the input
rotary motion, for establishing the reverse-gear position for the
rotary motion of the output shaft 22 in the direction opposite to
that in the forward-drive positions. Thus, the rear-drive position
can be established in the absence of the first clutch C1 in the
automatic transmission, so that the drive system can be
small-sized. Further, in the rear-drive position, the speed of the
output rotary motion of the automatic transmission 172 is made
lower than or equal to that of the input rotary motion received
from the power distributing mechanism 16 the speed ratio of which
is continuously variable in the engaged state of the second brake
B2 or second clutch C2. Accordingly, the rear-drive position has a
desired speed ratio .lamda.R, which may be higher than that of the
first-gear position.
Embodiment 13
[0557] FIG. 42 is a schematic view for explaining an arrangement of
a drive system 180 according to another embodiment of this
invention, and FIG. 43 is a table indicating gear positions of the
drive system 180, and different combinations of engaged states of
the hydraulically operated frictional coupling devices for
respectively establishing those gear positions, while FIG. 43 is a
collinear chart for explaining shifting operations of the drive
system 180. The present embodiment is different from the embodiment
shown in FIGS. 14-16, primarily in that the power distributing
mechanism 16 and the automatic transmission 72 are not disposed
coaxially with each other in the present embodiment. The following
description of the present embodiment primarily relates to a
difference between the drive system 180 and the drive system
70.
[0558] The drive system 180 shown in FIG. 42 is provided, within a
casing 12 attached to the vehicle body, with: an input shaft 14
disposed rotatably about a first axis 14c; the power distributing
mechanism 16 mounted on the input shaft 14 directly, or indirectly
through a pulsation absorbing damper (vibration damping device);
the automatic transmission 72 disposed rotatably about a second
axis 32c parallel to the first axis 14c; an output rotary member in
the form of a differential drive gear 32 connected to the automatic
transmission 72; and a power transmitting member in the form of a
counter gear pair CG which connects the power distributing
mechanism 16 and the automatic transmission 72, so as to transmit a
drive force therebetween. This drive system 180 is suitably used on
a transverse FF (front-engine, front-drive) vehicle or a transverse
RR (rear-engine, rear-drive) vehicle, and is disposed between a
drive power source in the form of an engine 8 and a pair of drive
wheels 38. The drive force is transmitted from the differential
drive gear 32 to the pair of drive wheels 38, through a
differential gear 34 meshing with the differential drive gear 32, a
differential gear device 36, a pair of drive axles 37, etc.
[0559] The counter gear pair CG indicated above consists of a
counter drive gear CG1 disposed rotatably on the first axis 14c and
coaxially with the power distributing mechanism 16 and fixed to a
first ring gear R1, and a counter driven gear CG2 disposed
rotatably on the second axis 32c and coaxially with the automatic
transmission 20 and connected to the automatic transmission 20
through a first clutch C1 and a second clutch C2. The counter drive
gear CG1 and the counter driven gear CG2 serve as a pair of members
in the form of a pair of gears which are held in meshing engagement
with each other. Since the speed reduction ratio of the counter
gear pair CG (rotating speed of the counter drive gear CG1/rotating
speed of the counter driven gear CG2) is about 1.000, the counter
gear pair CG functionally corresponds to the power transmitting
member 18 in the embodiment shown in FIGS. 14-16, which connects
the power distributing mechanism 16 and the automatic transmission
72. That is, the counter drive gear CG1 corresponds to a power
transmitting member which constitutes a part of the power
transmitting member 18 on the side of the first axis 14c, while the
counter driven gear CG2 corresponds to a power transmitting member
which constitutes another part of the power transmitting member 18
on the side of the second axis 32c.
[0560] Referring to FIG. 42, the individual elements of the drive
system 180 will be described. The counter gear pair CG is disposed
adjacent to one end of the power distributing mechanism 16 which
remote from the engine 8. In other words, the power distributing
mechanism 16 is interposed between the engine 8 and the counter
gear pair CG, and located adjacent to the counter gear pair CG. A
second electric motor M2 is disposed on the first axis 14c, between
a first planetary gear set 24 and the counter gear pair CG, such
that the second electric motor M2 is fixed to the counter drive
gear CG1. The differential drive gear 32 is disposed adjacent to
one end of the automatic transmission 72 which is remote from the
counter gear pair CG, that is, on the side of the engine 8. In
other words, the automatic transmission 72 is interposed between
the counter gear pair CG and the differential drive gear 32 (engine
8), and located adjacent to the counter gear pair CG. Between the
counter gear pair CG and the differential drive gear 32, a second
planetary gear set 26 and a third planetary gear set 28 are
disposed in the order of description, in the direction from the
counter gear pair CG toward the differential drive gear 32. The
first clutch C1 and the second clutch C2 are disposed between the
counter gear pair CG and the second planetary gear set 26.
[0561] The present embodiment is different from the embodiment
shown in FIGS. 14-16, only in that the counter gear pair CG
replaces the power transmitting member 18 connecting the power
distributing mechanism 16 and the automatic transmission 72, and is
identical with the embodiment shown in FIGS. 14-16 in the
arrangements of the power distributing mechanism 16 and automatic
transmission 72. Accordingly, the table of FIG. 43 and the
collinear chart of FIG. 44 are the same as the table of FIG. 15 and
the collinear chart of FIG. 16, respectively.
[0562] In the present embodiment, too, the drive system 180 is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 72 functioning as the
step-variable shifting portion or second shifting portion, so that
the drive system 180 has advantages similar to those of the
preceding embodiments. Unlike the embodiment shown in FIGS. 14-16,
the present embodiment is arranged such that the power distributing
mechanism 16 and the automatic transmission 72 are not disposed
coaxially with each other, so that the required dimension of the
drive system 180 in the axial direction can be reduced.
Accordingly, the present drive system can be suitably used on a
transversal FF or RR vehicle such that the first and second axes
14c, 32c are parallel to the transverse or width direction of the
vehicle. In this respect, it is noted that the maximum axial
dimension of a drive system for such a transverse FF or RR vehicle
is generally limited by the width dimension of the vehicle. The
present embodiment has an additional advantage that the required
axial dimension of the drive system 180 can be further reduced,
since the power distributing mechanism 16 and the automatic
transmission 72 are located between the engine 8 (differential
drive gear 32) and the counter gear pair CG. Further, the required
axial dimension of the second axis 32c can be reduced owing to the
arrangement in which the second electric motor M2 is disposed on
the first axis 13c.
Embodiment 14
[0563] FIG. 45 is a schematic view for explaining an arrangement of
a drive system 190 according to another embodiment of this
invention. This embodiment is different from the embodiment shown
in FIGS. 42-44, in the position of the second electric motor M2.
Referring to FIG. 45, the positional arrangement of the second
electric motor M2 will be described. The second electric motor M2
is located between an assembly of the first and second clutches C1,
C2 and the counter gear pair CG, and disposed on the second axis
32c, and adjacent to the counter gear pair CG, such that the second
electric motor M2 is fixed to the counter driven gear CG2 serving
as the power transmitting member on the side of the second axis
32c. The arrangements of the power distributing mechanism 16 and
the automatic transmission 72 are identical with those of the
embodiment of FIGS. 42-44. Accordingly, the table of FIG. 43 and
the collinear chart of FIG. 44 apply to the present embodiment
shown in FIG. 45.
[0564] In the present embodiment, too, the drive system 190 is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 72 functioning as the
step-variable shifting portion or second shifting portion, so that
the drive system 190 has advantages similar to those of the
preceding embodiments. Unlike the embodiment shown in FIGS. 14-16,
the present embodiment is arranged such that the power distributing
mechanism 16 and the automatic transmission 72 are not disposed
coaxially with each other, so that the required dimension of the
drive system 190 in the axial direction can be reduced.
Accordingly, the present drive system can be suitably used on a
transversal FF or RR vehicle such that the first and second axes
14c, 32c are parallel to the transverse or width direction of the
vehicle. In this respect, it is noted that the maximum axial
dimension of a drive system for such a transverse FF or RR vehicle
is generally limited by the width dimension of the vehicle. The
present embodiment has an additional advantage that the required
axial dimension of the drive system 190 can be further reduced,
since the power distributing mechanism 16 and the automatic
transmission 72 are located between the engine 8 (differential
drive gear 32) and the counter gear pair CG. Further, the required
axial dimension of the second axis 32c can be reduced owing to the
arrangement in which the second electric motor M2 is disposed on
the first axis 13c.
Embodiment 15
[0565] FIG. 46 is a schematic view for explaining an arrangement of
a drive system 200 according to another embodiment of this
invention. This embodiment is different from the embodiment shown
in FIGS. 42-44, in the positions of the second electric motor M2,
first clutch C1 and second planetary gear set 26. Referring to FIG.
46, the positional arrangements of the second electric motor M2,
clutch C1 and second planetary gear set 26 will be described. The
second electric motor M2 is located on one side of the counter gear
pair CG which is remote from the first planetary gear set 24, and
disposed on the first axis 14c, and adjacent to the counter gear
pair CG, such that the second electric motor M2 is fixed to the
counter drive gear CG1 serving as the power transmitting member on
the side of the first axis 14c. The first clutch C1 and the second
planetary gear set 26 are located on one side of the counter gear
pair CG which is remote from the second clutch C2 and the third
planetary gear set 28, and disposed on the second axis 32c, such
that the first clutch C1 is located closer to the counter gear pair
CG than the second planetary gear set 26. The arrangements of the
power distributing mechanism 16 and the automatic transmission 72
are identical with those of the embodiment shown in FIGS. 42-44.
Accordingly, the table of FIG. 43 and the collinear chart of FIG.
44 apply to the present embodiment of FIG. 46.
[0566] In the present embodiment, too, the drive system 200 is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 72 functioning as the
step-variable shifting portion or second shifting portion, so that
the drive system 200 has advantages similar to those of the
preceding embodiments. Unlike the embodiment shown in FIGS. 14-16,
the present embodiment is arranged such that the power distributing
mechanism 16 and the automatic transmission 72 are not disposed
coaxially with each other, so that the required dimension of the
drive system 200 in the axial direction can be reduced.
Accordingly, the present drive system can be suitably used on a
transversal FF or RR vehicle such that the first and second axes
14c, 32c are parallel to the transverse or width direction of the
vehicle. In this respect, it is noted that the maximum axial
dimension of a drive system for such a transverse FF or RR vehicle
is generally limited by the width dimension of the vehicle.
Further, the required axial dimension of the second axis 32c can be
reduced owing to the arrangement in which the second electric motor
M2 is disposed on the first axis 13c.
Embodiment o16
[0567] FIG. 47 is a schematic view for explaining an arrangement of
a drive system 210 according to another embodiment of this
invention, and FIG. 48 is a table indicating gear positions of the
drive system 210, and different combinations of engaged states of
the hydraulically operated frictional coupling devices for
respectively establishing those gear positions, while FIG. 49 is a
collinear chart for explaining shifting operations of the drive
system 210. The present embodiment is different from the embodiment
shown in FIGS. 39-41, primarily in that the power distributing
mechanism 16 and the automatic transmission 172 are not disposed
coaxially with each other in the present embodiment, and is
different from the embodiment shown in FIGS. 42-44, in that the
first clutch C1 is not provided in the present embodiment, and in
the manner of establishing a reverse-gear position in the present
embodiment.
[0568] The present embodiment is different from the embodiment
shown in FIGS. 39-42, only in that the counter gear pair CG
replaces the power transmitting member 18 connecting the power
distributing mechanism 16 and the automatic transmission 172, and
is identical with the embodiment shown in FIGS. 39-42 in the
arrangements of the power distributing mechanism 16 and automatic
transmission 172, including the means for establishing the
reverse-gear positions. Accordingly, the table of FIG. 48 and the
collinear chart of FIG. 49 are the same as the table of FIG. 40 and
the collinear chart of FIG. 41, respectively. Further, the
arrangement of the drive system 210 shown in FIG. 47 and the
arrangement of the counter gear pair CG (corresponding to the power
transmitting member 18 of FIG. 39) are identical with those of the
embodiment shown FIG. 42, except for the elimination of the first
clutch C1.
[0569] In the present embodiment, too, the drive system 210 is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 172 functioning as the
step-variable shifting portion or second shifting portion, so that
the drive system 210 has advantages similar to those of the
preceding embodiments. Unlike the embodiment shown in FIGS. 39-41,
the present embodiment is arranged such that the power distributing
mechanism 16 and the automatic transmission 172 are not disposed
coaxially with each other, so that the required dimension of the
drive system 210 in the axial direction can be reduced.
Accordingly, the present drive system can be suitably used on a
transversal FF or RR vehicle such that the first and second axes
14c, 32c are parallel to the transverse or width direction of the
vehicle. In this respect, it is noted that the maximum axial
dimension of a drive system for such a transverse FF or RR vehicle
is generally limited by the width dimension of the vehicle. The
present embodiment has an additional advantage that the required
axial dimension of the drive system 210 can be further reduced,
since the power distributing mechanism 16 and the automatic
transmission 172 are located between the engine 8 (differential
drive gear 32) and the counter gear pair CG. Further, the required
axial dimension of the second axis 32c can be reduced owing to the
arrangement in which the second electric motor M2 is disposed on
the first axis 13c.
Embodiment 17
[0570] FIG. 50 is a schematic view for explaining an arrangement of
a drive system 220 according to another embodiment of this
invention. This embodiment is different from the embodiment shown
in FIGS. 47-49, in the positions of the second electric motor M2
and second planetary gear set 26. Referring to FIG. 50, the
positional arrangements of the second electric motor M2 and second
planetary gear set 26 will be described. The second electric motor
M2 is located on one side of the counter gear pair CG which is
remote from the first planetary gear set 24, and disposed on the
first axis 14c, and adjacent to the counter gear pair CG, such that
the second electric motor M2 is fixed to the counter drive gear CG1
serving as the power transmitting member on the side of the first
axis 14c. The second planetary gear set 26 is located on one side
of the counter gear pair CG which is remote from the second clutch
C2 and the third planetary gear set 28, and disposed adjacent to
the counter gear pair CG. The arrangements of the power
distributing mechanism 16 and the automatic transmission 172 are
identical with those of the embodiment shown in FIGS. 47-49.
Accordingly, the table of FIG. 48 and the collinear chart of FIG.
49 apply to the present embodiment of FIG. 50.
[0571] In the present embodiment, too, the drive system 220 is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 172 functioning as the
step-variable shifting portion or second shifting portion, so that
the drive system 220 has advantages similar to those of the
preceding embodiments. Unlike the embodiment shown in FIGS. 39041,
the present embodiment is arranged such that the power distributing
mechanism 16 and the automatic transmission 172 are not disposed
coaxially with each other, so that the required dimension of the
drive system 220 in the axial direction can be reduced.
Accordingly, the present drive system can be suitably used on a
transversal FF or RR vehicle such that the first and second axes
14c, 32c are parallel to the transverse or width direction of the
vehicle. In this respect, it is noted that the maximum axial
dimension of a drive system for such a transverse FF or RR vehicle
is generally limited by the width dimension of the vehicle.
Further, the required axial dimension of the second axis 32c can be
reduced owing to the arrangement in which the second electric motor
M2 is disposed on the first axis 13c.
Embodiment of FIG. 51
[0572] FIG. 51 shows a seesaw type switch 44 functioning as a
manually shifting-state selecting device manually operable to
select the shifting state of the drive device 10. In the preceding
embodiments, the shifting state of the drive system 10 is
automatically switched on the basis of a change of the vehicle
condition and according to the relationship shown in FIG. 8 or FIG.
12 by way of example. However, the shifting state of the drive
system 10 may be manually switched by a manual operation of the
seesaw switch 44. Namely, the switching control means 50 may be
arranged to selectively place the transmission mechanism 10 in the
continuously-variable shifting state or the step-variable shifting
state, depending upon whether the switch 44 is placed in its
continuously-variable shifting position or step-variable shifting
position. For instance, the user of the vehicle manually operates
the switch 44 to place the drive system 10 in the
continuously-variable shifting state when the user likes the drive
system 10 to operate as a continuously variable transmission or
wants to improve the fuel economy of the engine, or alternatively
in the step-variable shifting state when the user likes a change of
the engine speed as a result of a shifting action of the drive
system 10 operating as a step-variable transmission. The switch 44
may have a neutral position in addition to the
continuously-variable shifting position and the step-variable
shifting position. In this case, the switch 44 may be placed in its
neutral position when the user has not selected the desired
shifting state or likes the drive system to be automatically placed
in one of the continuously-variable and step-variable shifting
states.
[0573] FIG. 52 is a functional block diagram for explaining major
control functions performed by the electronic control device 40
provided in another embodiment of this invention. In FIG. 52,
step-variable control means 152 is arranged to control a shifting
action of the transmission mechanism 10 on the basis of
predetermined control variables and according to a stored
relationship. FIG. 53 illustrates one example of the stored
relationship in the form of a step-variable-shifting control map
(shifting boundary line map) 162. Like the step-variable shifting
control means 54 described above, the step-variable shifting
control means 152 is arranged to determine whether a shifting
action of the automatic transmission portion 20 should be effected,
according to the step-variable-shifting control map 162 stored in
relationship memory means 154 and indicated by solid and one-dot
chain lines in FIG. 53, and on the basis of the vehicle condition
represented by a vehicle speed V, and a vehicle load, that is, an
output torque T.sub.OUT of the automatic transmission portion 20.
In other words, the step-variable shifting control means 152
determines the gear position to which the automatic transmission
portion 20 should be shifted, and commands a shifting action of the
automatic transmission portion 20 to the determined gear position.
Thus, the present embodiment is arranged to control the shifting
operation of the automatic transmission portion as a function of
the vehicle speed V and the vehicle load in the form of the output
torque T.sub.OUT. The map shown in FIG. 53 uses the same control
variables as used for defining the continuously-variable shifting
region and the step-variable shifting region.
[0574] Like the hybrid control means 52, hybrid control means 156
is arranged to control the engine 8 to be operated with high
efficiency while the transmission mechanism 10 is placed in the
continuously-variable shifting state, that is, while the
differential portion 11 is placed in its differential state. The
hybrid control means 156 is further arranged to control the speed
ratio .gamma.0 of the differential portion 11 operating as an
electrically controlled continuously variable transmission, so as
to establish an optimum proportion of the drive forces produced by
the engine 8 and the second electric motor M2, and to optimize a
reaction force generated during generation of an electric energy by
the first electric motor M1 and/or the second electric motor M2.
For instance, the hybrid control means 156 calculates the output as
required by the vehicle operator at the present running speed of
the vehicle, on the basis of an operating amount Acc of the
accelerator pedal and the vehicle speed V, and calculate a required
vehicle drive force on the basis of the calculated required output
and a required amount of generation of the electric energy. On the
basis of the calculated required vehicle drive force, the hybrid
control means 156 calculates desired speed N.sub.E and total output
of the engine 8, and controls the actual output of the engine 8 and
the amount of generation of the electric energy by the first
electric motor M1 and/or the second electric motor M2, according to
the calculated desired speed and total output of the engine.
[0575] The hybrid control means 156 is arranged to effect the
above-described hybrid control while taking account of the
presently selected gear position of the automatic transmission
portion 20, so as to improve the fuel economy of the engine. In the
hybrid control, the differential portion 11 is controlled to
function as the electrically controlled continuously-variable
transmission, for optimum coordination of the engine speed N.sub.E
and vehicle speed V for efficient operation of the engine 8, and
the rotating speed of the power transmitting member 18 determined
by the selected gear position of the automatic transmission portion
20. That is, the hybrid control means 156 determines a target value
of the overall speed ratio .gamma.T of the transmission mechanism
10, so that the engine 8 is operated according a stored
highest-fuel-economy curve that satisfies both of the desired
operating efficiency and the highest fuel economy of the engine 8.
The hybrid control means 156 controls the speed ratio .gamma.0 of
the differential portion 11, so as to obtain the target value of
the overall speed ratio .gamma.T, so that the overall speed ratio
.gamma.T can be controlled within a predetermined range, for
example, between 13 and 0.5.
[0576] In the hybrid control, the hybrid control means 156 supplies
the electric energy generated by the first electric motor M1, to
the electric-energy storage device 60 and second electric motor M2
through the inverter 58. That is, a major portion of the drive
force produced by the engine 8 is mechanically transmitted to the
power transmitting member 18, while the remaining portion of the
drive force is consumed by the first electric motor M1 to convert
this portion into the electric energy, which is supplied through
the inverter 58 to the second electric motor M2, or subsequently
consumed by the first electric motor M1. A drive force produced by
an operation of the second electric motor M1 or first electric
motor M1 with the electric energy is transmitted to the power
transmitting member 18. Thus, the drive system is provided with an
electric path through which an electric energy generated by
conversion of a portion of a drive force of the engine 8 is
converted into a mechanical energy. This electric path includes
components associated with the generation of the electric energy
and the consumption of the generated electric energy by the second
electric motor M2. It is also noted that the hybrid control means
156 is further arranged to establish a motor drive mode in which
the vehicle is driven with only the electric motor (e.g., second
electric motor M2) used as the drive power source, by utilizing the
electric CVT function (differential function) of the differential
shifting portion 11, irrespective of whether the engine 8 is in the
non-operated state or in the idling state. The hybrid control means
156 can establish the motor drive mode by operation of the first
electric motor M1 and/or the second electric motor M2, even when
the differential portion 11 is placed in the step-variable shifting
state (fixed-speed-ratio shifting state) while the engine 8 is in
its non-operated state.
[0577] The hybrid control means 156 also functions as
drive-power-source selection control means for selecting one of a
plurality of drive power sources, that is, one of the engine 8,
first electric motor M1 and second electric motor M2, on the basis
of predetermined control parameters and according to a
predetermined relationship. FIG. 54 shows an example of a stored
relationship, namely, a boundary line which defines an engine drive
region and a motor drive region and which is used to select the
engine 8 or the electric motors M1, M2, as the drive power source
(to select one of the engine drive mode and the motor drive mode).
That is, the stored relationship is represented by a
drive-power-source selection control map (drive-power-source
switching boundary line map) 164 in a rectangular two-dimensional
coordinate system having an axis along which the vehicle speed V is
taken, and an axis along which the drive-force-related value in the
form of the output torque T.sub.OUT is taken. FIG. 54 also shows a
one-dot chain line which is located inside the solid boundary line,
by a suitable amount of control hysteresis. For example, the
drive-power-source selection control map 164 shown in FIG. 54 is
stored in the relationship memory means 154. The hybrid control
means 156 determines whether the vehicle condition represented by
the vehicle speed V and the output torque T.sub.OUT is in the motor
drive region defined by the drive-power-source selection control
map 164. As is apparent from FIG. 54, the hybrid control means 156
selects the motor drive mode when the output torque T.sub.OUT is
comparatively small, or when the vehicle speed is comparatively
low, that is, when the vehicle load is in a comparatively low range
in which the operating efficiency of the engine is generally lower
than in a comparatively high range. Thus, the present embodiment is
arranged to select the desired drive power source as a function of
the vehicle speed V and the vehicle load in the form of the output
torque T.sub.OUT of the automatic transmission portion 20. The map
shown in FIG. 54 uses the same control variables as used for
defining the continuously-variable shifting region and the
step-variable shifting region.
[0578] For reducing a tendency of dragging of the engine 8 held in
its non-operated state in the motor drive mode, for thereby
improving the fuel economy, the hybrid control means 156 controls
the differential portion 11 so that the engine speed N.sub.E is
held substantially zero, that is, held zero or close to zero, with
the differential function of the differential portion 11. FIG. 55
is a view corresponding to a portion of the collinear chart of FIG.
3 which shows the differential portion 11. The collinear chart of
FIG. 55 indicates an example of the operating state of the
differential portion 11 placed in its continuously-variable
shifting state, in the motor drive mode of the vehicle. Where the
vehicle is run with the output torque of the second electric motor
M2, the first electric motor M1 is freely rotated in the negative
direction so that the engine speed N.sub.E (rotating speed of the
first carrier CA1) is held substantially zero while the second
electric motor M2 is operated at a speed corresponding to the
vehicle speed V.
[0579] Referring back to FIG. 52, high-speed-gear determining means
158 is arranged to determine whether the gear position to which the
transmission mechanism 10 should be shifted is the high-gear
position, for example, the fifth-gear position. This determination
is made on the basis of the vehicle condition and according to a
shifting boundary line map of FIG. 53 stored in the relationship
memory means 154, for example, to determine one of the switching
clutch C0 and brake B0 that should be engaged, to place the
transmission mechanism 10 in the step-variable shifting state.
[0580] Switching control means 159 is arranged to switch the
differential portion 11 between the continuously-variable shifting
state and the fixed-speed-ratio shifting state, in other words, to
place the transmission mechanism 10 selectively in the
continuously-variable shifting state and the step-variable shifting
state, on the basis of predetermined control variables and
according to a predetermined relationship. FIG. 56 shows an example
of a stored relationship indicative of boundary lines for switching
of the differential portion 11 between the continuously-variable
shifting state and the fixed-speed-ratio shifting state (for
switching of the transmission mechanism between the step-variable
shifting state). The stored relationship is represented by a
switching control map (switching boundary line map) 166 in a
rectangular two-dimensional coordinate system having an axis along
which the vehicle speed V is taken, and an axis along which the
drive-force-related value in the form of the output torque
T.sub.OUT is taken. The switching control map 166 is stored in the
relationship memory means 154. The switching control means 159
determines, according to the switching control map 166 of FIG. 53,
whether the vehicle condition represented by the vehicle speed V
and the output torque T.sub.OUT is in a continuously-variable
shifting region for placing the differential portion 11 in the
continuously-variable shifting state, or in a step-variable
shifting region for placing the differential portion 11 in the
fixed-speed-ration shifting state. On the basis of a result of the
determination, the differential portion 11 is placed in one of the
continuously-variable shifting state and the fixed-speed-ratio
shifting state. In other words, the switching control means 159
determines whether the vehicle condition is in a
continuously-variable shifting region for placing the transmission
mechanism 10 in the continuously-variable shifting state, or in a
step-variable shifting region for placing the transmission
mechanism 10 in the step-variable shifting state, so that the
transmission mechanism 10 is placed in one of the
continuously-variable shifting state and the step-variable shifting
state, on the basis of a result of the determination. Thus, the
present embodiment is arranged to select the continuously-variable
shifting state or the step-variable shifting state (locking state),
as a function of the vehicle speed V and the vehicle load in the
form of the output torque T.sub.OUT of the automatic transmission
portion 20. The map shown in FIG. 56 represents the predetermined
relationship between those control variables.
[0581] When the switching control means 159 determines that the
vehicle condition is in the continuously-variable shifting region,
the switching control means 159 disables the hybrid control means
156 effect a hybrid control or continuously-variable shifting
control, and enables step-variable shifting control means 152 to
effect a predetermined step-variable shifting control. In this
case, the step-variable shifting control means 152 effects an
automatic shifting control according to the step-variable-shifting
control map 162 shown in FIG. 53 and stored in relationship memory
means 154. FIG. 2 indicates the combinations of the operating
states of the hydraulically operated frictional coupling devices
C0, C1, C2, B0, B1, B2 and B3, which are selectively engaged for
effecting the step-variable shifting control. In this automatic
step-variable shifting control mode, the transmission mechanism 10
as a whole consisting of the differential portion 11 and the
automatic transmission portion 20 functions as a so-called
"step-variable automatic transmission", the gear positions of which
are established according to the table of engagement of the
frictional coupling devices shown in FIG. 2.
[0582] When the high-speed-gear determining means 158 determines
that the fifth-gear position should be established as the high-gear
position, the switching control means 159 commands the hydraulic
control unit 42 to release the switching clutch C0 and engage the
switch brake B0, so that the differential portion 11 functions as
an auxiliary transmission having a fixed speed ratio .gamma.0, for
example, a speed ratio .gamma.0 of 0.7, whereby the transmission
mechanism 10 as a whole is placed in a so-called "overdrive gear
position" having a speed ratio lower than 1.0. When the
high-speed-gear determining means 158 determines that a gear
position other than the fifth-gear position should be established,
the switching control means 159 commands the hydraulic control unit
42 to engage the switching clutch C0 and release the switching
brake B0, so that the differential portion 11 functions as an
auxiliary transmission having a fixed speed ratio .gamma.0, for
example, a speed ratio .gamma.0 of 1, whereby the transmission
mechanism 10 as a whole is placed in a low-gear position the speed
ratio of which is not lower than 1.0. Thus, the transmission
mechanism 10 is switched to the step-variable shifting state, by
the switching control means 60, and the differential portion 11
placed in the step-variable shifting state is selectively placed in
one of the two gear positions, so that the differential portion 11
functions as the auxiliary transmission, while at the same time the
automatic transmission portion 20 connected in series to the
differential portion 11 functions as the step-variable
transmission, whereby the transmission mechanism 10 as the whole
functions as a so-called "step-variable automatic
transmission".
[0583] When the switching control means 159 determines that the
vehicle condition is in the continuously-variable shifting region
for placing the transmission mechanism 10 in the
continuously-variable shifting state, on the other hand, the
switching control means 159 commands the hydraulic control unit 42
to release the switching clutch C0 and the switching brake B0 for
placing the differential portion 11 in the continuously-variable
shifting state, so that the transmission mechanism 10 as a whole is
placed in the continuously-variable shifting state. At the same
time, the switching control means 159 enables the hybrid control
means 156 to effect the hybrid control, and commands the
step-variable shifting control means 152 to select and hold a
predetermined one of the gear positions, or to permit an automatic
shifting control according to the step-variable-shifting control
map 162 of FIG. 53 stored in the relationship memory means 154. In
the latter case, the variable-step shifting control means 152
effects the automatic shifting control by suitably selecting the
combinations of the operating states of the frictional coupling
devices indicated in the table of FIG. 2, except the combinations
including the engagement of the switching clutch C0 and brake B0.
Thus, the differential portion 11 placed in the
continuously-variable shifting state under the control of the
switching control means 159 functions as the continuously variable
transmission while the automatic transmission portion 20 connected
in series to the differential portion 11 functions as the
step-variable transmission, so that the drive system provides a
sufficient vehicle drive force, such that the speed of the rotary
motion transmitted to the automatic transmission portion 20 placed
in one of the first-speed, second-speed, third-speed and
fourth-gear positions, namely, the rotating speed of the power
transmitting member 18 is continuously changed, so that the speed
ratio of the drive system when the automatic transmission portion
20 is placed in one of those gear positions is continuously
variable over a predetermined range. Accordingly, the speed ratio
of the automatic transmission portion 20 is continuously variable
through the adjacent gear positions, whereby the overall speed
ratio .gamma.T of the transmission mechanism 10 as a whole is
continuously variable. In other words, the switching control means
159 controls the engaging and releasing actions of the
differential-state switching device in the form of the switching
brake B0 and switching clutch B0, for selectively placing the power
distributing mechanism 16 in one of the differential state and the
non-differential state.
[0584] FIG. 57 illustrates a complex control map 168 which is a
combination of the step-variable-shifting control map 162, the
drive-power-source selection control map 164 and the switching
control map 166. Preferably, the step-variable-shifting control map
162, the drive-power-source selection control map 164 and the
switching control map 166 use common control variables in the form
of the vehicle speed V and the vehicle load, that is, the output
torque T.sub.OUT of the automatic transmission portion 20, as shown
in FIG. 57. In other words, the step-variable shifting control
means 152, the hybrid control means 156, the high-speed-gear
determining means 158 and the switching control means 159 cooperate
to effect a complex shifting control and a drive-power-source
selecting control on the basis of the common control variables
consisting of the vehicle speed V and the output torque T.sub.OUT
of the automatic transmission portion 20, and according to the
stored relationships in the form of the complex control map 168
stored in the relationship memory means 154. The use of the common
control variables permits an adequate overall shifting control to
selectively effect the continuously-variable shifting control and
the step-variable shifting control, and an adequate overall drive
control including the drive-power-source selection control as well
as the continuously-variable shifting control and the step-variable
shifting control. Thus, the relationship memory means 154 stores
the maps which define the continuously-variable shifting region,
step-variable shifting region (locking-state region), etc., in a
manner as simple as possible, with the two control variables, that
is, the vehicle speed V and the output torque T.sub.OUT of the
automatic transmission portion 20. Further, various controls of the
drive system can be carried out in a simple manner as a function of
the power output which determines whether the continuously-variable
shifting is advantageous or disadvantageous and the required
capacity of the electric motor, and as a function of the vehicle
speed V which determines whether the continuously-variable shifting
is advantageous or disadvantageous in terms of the power
transmitting efficiency. It is noted that although FIG. 57 shows
the complex control map 168 as a combination of the
step-variable-shifting control map 162, drive-power-source
selection control map 164 and switching control map 166, for
convenience' sake, those maps 162, 164, 166 which are respectively
shown in FIGS. 53, 54 and 56 are stored in the relationship memory
means 154, independently of each other.
[0585] FIG. 58 is a view illustrating an example of a power-mode
step-variable-shifting control map (shifting boundary line map) 171
used by the step-variable shifting control means 152 for the
step-variable shifting control. FIG. 59 is a view illustrating an
example of a power-mode drive-power-source selection control map
(drive-power-source switching boundary line map) 172 used by the
hybrid control means 156 for the drive-power-source selection
control. FIG. 60 is a view illustrating an example of a power-mode
complex control map 174 which is a combination of the
step-variable-shifting control map 171, the drive-power-source
selection control map 172 and the switching control map 166. When a
power-mode selector switch such as an ETC switch is operated to
select a power mode running of the vehicle, the step-variable
shifting control means 152, hybrid control means 156,
high-speed-gear determining means 158 and switching control means
159 perform the respective control functions described above, on
the basis of the vehicle speed V and the output torque T.sub.OUT of
the automatic transmission portion 20, and according to the
power-mode control maps stored in the relationship memory means
154. The control maps shown in FIG. 53, FIG. 54, FIG. 56 and FIG.
57 are used in a normal-mode running of the vehicle. The switching
control map 166 shown in FIG. 56 is commonly used in the
normal-mode running and the power-mode running. However, one of the
normal-mode step-variable-shifting control map and the power-mode
step-variable shifting control map, and one of the normal-mode
drive-power-source selection control map and the power-mode
drive-power-source selection control map are selectively used
depending upon the presently selected running mode of the vehicle.
Thus, the relationship memory means 154 stores a plurality of
relationships in the form of a plurality of control maps for
performing the step-variable shifting control, drive-power-source
selection control and shifting-state switching control.
[0586] The shifting boundary line maps shown in FIGS. 53 and 58
will be described in detail. These shifting boundary line maps
(relationships) shown in these figures for illustrative purpose are
stored in the relationship memory means 154, and used to determine
whether a shifting action of the automatic transmission portion 20
should be effected. These shifting boundary line maps are defined
in a rectangular two-dimensional coordinate system having an axis
of the vehicle speed V and an axis of the vehicle load in the form
of the output torque T.sub.OUT. Solid lines in FIGS. 53 and 58 are
shift-up boundary lines, while one-dot chain lines are shift-down
boundary lines. Broken lines in FIGS. 56 and 60 indicate an upper
vehicle-speed limit V1 and an upper output-torque limit T1 which
are used to determine whether the vehicle condition is in the
step-variable shifting region or the continuously-variable shifting
region. That is, the broke lines in FIGS. 56 and 60 are a
predetermined upper vehicle-speed limit line consisting of a series
of upper speed limits V1 for determining whether the hybrid vehicle
is in the high-speed running state, and a predetermined upper
output limit line consisting of a series of upper output limits in
the form of upper limits T1 of the output torque T.sub.OUT of the
automatic transmission portion 20 as a drive-force-related value
for determining whether the hybrid vehicle is in the high-output
running state. Two-dot chain lines also shown in FIGS. 56 and 60
are limit lines which are offset with respect the broken lines, by
a suitable amount of control hysteresis, so that the broken lines
and the two-dot chain lines are selectively used as the boundary
lines defining the step-variable shifting region and the
continuously-variable shifting region. These boundary lines of
FIGS. 56 and 60 are stored switching boundary line maps (switching
maps or relationships) each of which includes the upper
vehicle-speed limit V1 and the upper output torque limit T1 and is
used by the switching control means 60 to determine whether the
vehicle condition is in the step-variable shifting region or
continuously-variable shifting region, on the basis of the vehicle
speed V and the output torque T.sub.OUT. These switching boundary
line maps may be included in the shifting boundary line maps stored
in the relationship memory means 154. The switching boundary line
maps may include at least one of the upper vehicle-speed limit V1
and the upper output-torque limit T1, and may use only one of the
vehicle speed V and the output torque T.sub.OUT as a control
parameter. The shifting boundary line maps, switching boundary line
maps, etc. described above may be replaced by equations for
comparison of the actual value of the vehicle speed V with the
upper vehicle-speed limit V1, and equations for comparison of the
actual value of the output torque T.sub.OUT with the upper
output-torque limit T1.
[0587] The vehicle load indicated above is a parameter directly
corresponding to the vehicle drive force, and may be represented by
not only a drive torque or force of the drive wheels 38, but also
the output torque T.sub.OUT of the automatic transmission portion
20, engine torque T.sub.E or vehicle acceleration value, or an
actual value of the engine torque T.sub.E which is calculated from
the engine speed N.sub.E and an angle of operation of an
accelerator pedal or an angle of opening of a throttle valve
(intake air quantity, air/fuel ratio or amount of fuel injection),
or an estimated value of an operator's required vehicle drive force
calculated from an amount of operation of the accelerator pedal or
angle of opening of the throttle valve. The drive torque indicated
above may be calculated on the basis of the output torque
T.sub.OUT, and by taking account of the gear ratio of the
differential gear device, the radius of the drive wheels 38, etc.,
or directly detected by a torque sensor.
[0588] The upper vehicle-speed limit V1 is determined so that the
transmission mechanism 10 is placed in the step-variable shifting
state while the vehicle speed V is higher than the upper limit V1.
This determination is effective to minimize a possibility of
deterioration of the fuel economy of the vehicle if the
transmission mechanism 10 were placed in the continuously-variable
shifting state at a relatively high running speed of the vehicle.
The upper output-torque limit T1 is determined depending upon the
operating characteristics of the first electric motor M1, which is
small-sized and the maximum electric energy output of which is made
relatively small so that the reaction torque of the first electric
motor M1 is not so large when the engine output is relatively high
in the high-output running state of the vehicle.
[0589] As shown in FIGS. 56 and 60, the step-variable shifting
region is set to be a high output-torque region in which the output
torque T.sub.OUT is not lower than the upper output-torque limit
T1, and a high vehicle-speed region in which the vehicle speed V is
not lower than the upper vehicle-speed limit V1. Accordingly, the
step-variable shifting control is effected when the vehicle is in a
high-output running state with a comparatively high output of the
engine 8 or when the vehicle is in a high-speed running state,
while the continuously-variable shifting control is effected when
the vehicle is in a low-output running state with a comparatively
low output of the engine 8 or when the vehicle is in a low-speed
running state, that is, when the engine 8 is in a normal output
state. The step-variable shifting region indicated in FIG. 8 is set
to be a high-torque region in which the engine output torque
T.sub.E is not lower than a predetermined value T.sub.E1, a
high-speed region in which the engine speed N.sub.E is not lower
than a predetermined value N.sub.E1, or a high-output region in
which the engine output determined by the output torque T.sub.E and
speed N.sub.E of the engine 8 is not lower than a predetermined
value. Accordingly, the step-variable shifting control is effected
when the torque, speed or output of the engine 8 is comparatively
high, while the continuously-variable shifting control is effected
when the torque, speed or output of the engine is comparatively
low, that is, when the engine is in a normal output state. The
switching boundary lines in FIG. 8, which defines the step-variable
shifting region and the continuously-variable shifting region,
function as an upper vehicle-speed limit line consisting of a
series of upper vehicle-speed limits, and an upper output limit
line consisting of a series of upper output limits.
[0590] Therefore, when the vehicle is in a low- or medium-speed
running state or in a low- or medium-output running state, the
transmission mechanism 10 is placed in the continuously-variable
shifting state, assuring a high degree of fuel economy of the
hybrid vehicle. When the vehicle is in a high-speed running state
with the vehicle speed V exceeding the upper vehicle-speed limit
V1, on the other hand, the transmission mechanism 10 is placed in
the step-variable shifting in which the transmission mechanism 10
is operated as a step-variable transmission, and the output of the
engine 8 is transmitted to the drive wheels 38 primarily through
the mechanical power transmitting path, so that the fuel economy is
improved owing to reduction of a loss of conversion of the
mechanical energy into the electric energy, which would take place
when the transmission mechanism 10 is operated as an electrically
controlled continuously variable transmission. When the vehicle is
in a high-output running state in which the drive-force-related
value in the form of the output torque T.sub.OUT exceeds the upper
output-torque limit T1, the transmission mechanism 10 is also
placed in the step-variable shifting state. Therefore, the
transmission mechanism 10 is placed in the continuously-variable
shifting state or operated as the electrically controlled
continuously variable transmission, only when the vehicle speed is
relatively low or medium or when the engine output is relatively
low or medium, so that the required amount of electric energy
generated by the first electric motor M1, that is, the maximum
amount of electric energy that must be transmitted from the first
electric motor M1 can be reduced, whereby the required electrical
reaction force of the first electric motor M1 can be reduced,
making it possible to minimize the required sizes of the first
electric motor M1, and the required size of the drive system
including the electric motor. In other words, the transmission
mechanism 10 is switched from the continuously-variable shifting
state to the step-variable shifting state (fixed-speed-ratio
shifting state) in the high-output running state of the vehicle in
which the vehicle operator desires an increase of the vehicle drive
force, rather than an improvement in the fuel economy. Accordingly,
the vehicle operator is satisfied with a change of the engine speed
N.sub.E as a result of a shift-up action of the automatic
transmission portion in the step-variable shifting state, that is,
a comfortable rhythmic change of the engine speed N.sub.E, as
indicated in FIG. 10.
[0591] In the present embodiment, too, the switching control map
166 shown in FIG. 56 used for switching between the step-variable
shifting region and the continuously-variable shifting region may
be replaced by the switching control map shown in FIG. 8. In this
case, the switching control means 159 uses the switching control
map of FIG. 8, in place of the switching control map of FIG. 56, to
determine whether the vehicle condition represented by the engine
speed N.sub.E and the engine torque T.sub.E is in the
continuously-variable shifting region or step-variable shifting
region. The broken lines in FIG. 56 can be generated the basis of
the switching control map of FIG. 8. In other words, the broken
lines of FIG. 56 are switching boundary lines which are defined on
the basis of the relationship (map) of FIG. 8, in the rectangular
two-dimensional coordinate system having an axis along which the
vehicle speed V is taken, and an axis along which the output torque
T.sub.OUT is taken.
[0592] There will be described in detail the operation of the
switching control means 159 in the motor drive mode in which only
the electric motor, for example, only the second electric motor M2
is operated as the drive power source, owing to the electric CVT
function (differential function) of the differential portion 11.
When it is determined that the vehicle condition is in the motor
drive region, the switching control means 159 places the power
distributing mechanism 16 in its differential state, so that the
engine speed N.sub.E is held substantially zero, as indicated in
FIG. 55, under the control of the hybrid control means 156, for
reducing a tendency of dragging of the engine 8 held in its
non-operated state in the motor drive mode, for thereby improving
the fuel economy.
[0593] In the motor drive mode, the switching control means 159
places the power distributing mechanism 16 in its differential
state, even when the step-variable shifting state or
non-differential state of the power distributing mechanism 16 is
selected by the switch 48. As is apparent from the
drive-power-source selection control map 164 of FIG. 54, the
vehicle running in the motor drive mode is in a low-load state, in
which a comfortable change of the engine speed that would be
obtained in a high-torque running state cannot be obtained as a
result of a shifting action of the automatic transmission, and in
which the vehicle operator does not expect such a comfortable
change of the engine speed. In the motor drive mode, therefore, the
switching control means 159 places the power distributing mechanism
16 in the differential state, for improving the fuel economy, even
when the non-differential state is selected by the switch 44.
[0594] If there is a high possibility of starting of the engine in
the motor drive mode, the switching control means 159 places the
power distributing mechanism 16 I the non-differential state even
in the motor drive mode, for raising the engine speed N.sub.E to
facilitate the ignition of the engine. Since the engine speed
N.sub.E is held substantially zero in the motor drive mode, as
described above, the switching control means 159 places the power
distributing mechanism 16 in the non-differential state, by
engaging the switching brake B0 or switching clutch C0, for raising
the rotating speed of the first sun gear S1 to raise the engine
speed N.sub.E at a higher rate than a rate of increase of the first
sun gear S1 by the first electric motor M1 in the differential
state of the power distributing mechanism 16.
[0595] Referring back to FIG. 52, continuously-variable-shifting
speed-ratio control means (hereinafter referred to as "speed-ratio
control means") 161 is arranged to control the speed ratio .gamma.
of the automatic transmission and the speed ratio .gamma.0 of the
differential portion 11, so as to maximize the fuel economy, on the
basis of the operating efficiency .eta.M1 of the first electric
motor M1 and the operating efficiency .eta.M2 of the second
electric motor M2, when it is determined that the
continuously-variable shifting portion in the form of the
differential portion 11 is placed in the continuously-variable
shifting state. For instance, the speed-ratio control means 161
adjusts the speed ratio .gamma. of the step-variable shifting
portion in the form of the automatic transmission portion 20 to
thereby change the speed ratio .gamma.0 of the
continuously-variable shifting portion in the form of the
differential portion 11, so as to reduce the output shaft speed
(input shaft speed of the automatic transmission portion 20)
N.sub.IN of the differential portion 11, for the purpose of
preventing reverse rotation of the first electric motor M1 even in
a steady-state running state of the vehicle at a comparatively high
speed.
[0596] The speed-ratio control means 161 determines a target speed
N.sub.EM of the engine 8 on the basis of the actual operating angle
Acc of the accelerator pedal and according to an
engine-fuel-economy map 167 shown in FIG. 61, which is stored in
the relationship memory means 154. On the basis of the actual
vehicle speed V, the speed-ratio control means 161 determines the
speed ratio .gamma. of the automatic transmission portion 20 and
the speed ratio .gamma.0 of the differential portion 11, which
speed ratios give the target engine speed N.sub.EM. Namely, the
speed-ratio control means 161 selects, according to a well-known
relationship, one of iso-horsepower curves L3a (shown in FIG. 61)
which corresponds to the output of the engine 8, on the basis of
the actual operating angle Acc of the accelerator pedal
representative of the vehicle drive force as required by the
vehicle operator. The speed-ratio control means 161 determines, as
the target engine speed N.sub.EM, the engine speed corresponding to
a point Ca of intersection between the selected iso-horsepower
curve L3a and a highest-fuel-economy curve L2, as indicated in FIG.
61. Further, the speed-ratio control means 161 determines the
overall speed ratio .gamma.T of the transmission mechanism 10 that
gives the target engine speed N.sub.EM, on the basis of the target
engine speed N.sub.EM and the actual vehicle speed V, and according
to the following equation (1). A relationship between the rotating
speed N.sub.OUT(rpm) of the output shaft 22 of the automatic
transmission portion 20 and the vehicle speed V (km/h) is
represented by the following equation (2), wherein a speed ratio of
the final speed reducer is represented by .gamma.f, and the radius
of the drive wheels 38 is represented by r. Then, the speed-ratio
control means 161 determines, according to the equations (1), (2),
(3) and (4), the speed ratio .gamma. of the automatic transmission
portion 20 and the speed ratio .gamma.0 of the differential portion
11, which give the overall speed ratio .gamma.T
(=.gamma..times..gamma.0) of the transmission mechanism 10 and
which maximize the overall power transmitting efficiency of the
transmission mechanism 10.
[0597] The speed ratio .gamma.0 of the differential portion 11
varies from zero to 1. Initially, therefore, a plurality of
candidate speed ratio values .gamma.a, .gamma.b, etc. of the
automatic transmission portion 20 that give the engine speed
N.sub.E higher than the target engine speed N.sub.EM when the speed
ratio .gamma.0 is assumed to be 1 are obtained on the basis of the
actual vehicle speed V and according to the relationships between
the engine speed N.sub.E and the vehicle speed V as represented by
the following equations (1) and (2). Then, fuel consumption amounts
Mfce corresponding to the candidate speed ratio values .gamma.a,
.gamma.b, etc. are calculated on the basis of the overall speed
ratio .gamma.T that give the target engine speed N.sub.EM, and the
candidate speed ratio values .gamma.a, .gamma.b, etc., and
according to the following equation (3), for example. One of the
candidate speed ratio values which corresponds to the smallest one
of the calculated fuel consumption values Mfce is determined as the
speed ratio .gamma. of the automatic transmission portion 20. The
speed ratio .gamma.0 of the differential portion 11 is determined
on the basis of the determined speed ratio .gamma. and the overall
speed ratio .gamma.T that gives the target engine speed
N.sub.EM.
[0598] In the following equation (3), Fce, PL, .eta.ele, .eta.CVT,
k1, k2 and .eta.gi represent the following: Fce=fuel consumption
ratio; PL=instantaneous required drive force; .eta.ele=efficiency
of the electric system; .eta.CVT=power transmitting efficiency of
the differential portion 11; k1=power transmitting ratio of the
electric path of the differential portion 11; k2=power transmitting
ratio of the mechanical path of the differential portion 11; and
.eta.gi=power transmitting efficiency of the automatic transmission
portion. Efficiency .eta.M1 of the first electric motor .eta.M1 and
efficiency M2 of the second electric motor M2 in the equation (3)
are obtained on the basis of the rotating speeds which give the
overall speed ratio .gamma.T of the differential portion 11 to
obtain the target engine speed N.sub.EM for each of the candidate
speed ratio values .gamma.a, .gamma.b, etc. and which correspond to
candidate speed ratio values .gamma.0a, .gamma.0b, etc. of the
differential portion 11, and on the basis of the output torque
values of the electric motors required to generate the required
vehicle drive force. The ratio k1 is usually about 0.1, while the
ratio k2 is usually about 0.9. However, the ratios k1 and k2 vary
as a function of the required vehicle output. The power
transmitting efficiency .eta.gi of the automatic transmission
portion 20 is determined as a function of a transmitted torque T1
(which varies with the selected gear position i), a rotating speed
Ni of the rotating member, and an oil temperature H. For
convenience' sake, the fuel consumption ratio Fce, instantaneous
required drive force PL, efficiency .eta.ele of the electric system
and power transmitting efficiency .eta.CVT of the differential
portion 11 are held constant. Further, The power transmitting
efficiency .eta.gi of the automatic transmission portion 20 may be
held constant, as long as the use of a constant value as the
efficiency .eta.gi does not cause an adverse influence.
N.sub.EM=.gamma.T.times.N.sub.OUT (1)
N.sub.OUT=(V.times..gamma.f)/2.pi.r60 (2)
Nfce=Fce.times.PL/(.eta.M1.times..eta.M2.times..eta.ele.times.k1+.eta.CV-
T.times.k2).times..eta.gi) (3)
.eta.gi=f(Ti,Ni,H) (4)
[0599] The speed-ratio control means 161 commands the step-variable
shifting control means 152 and the hybrid control means 156 to
perform the respective step-variable shifting and hybrid control
functions, so as to establish the determined speed ratio .gamma. of
the automatic transmission portion 20 and the determined speed
ratio .gamma.0 of the differential portion 11.
[0600] FIG. 62 is a flow chart illustrating one of major control
operations of the electronic control device 40, that is, a
switching control of the transmission mechanism 10 in the
embodiment of FIG. 52. This switching control is repeatedly
executed with an extremely short cycle time of about several
milliseconds to several tens of milliseconds, for example.
[0601] Initially, step SA1 (hereinafter "step" being omitted) is
implemented to determine whether the vehicle condition represented
by the vehicle speed V and the output torque T.sub.OUT is in a
motor-drive region. This determination is made according to the
drive-power-source selection control map 164 illustrated in FIG.
54. If an affirmative decision is obtained in SA1, the control flow
goes to SA10 in which the vehicle is run in the motor-drive mode
with the first electric motor M1 and/or second electric motor M2
used as the drive power source. Then, the present control routine
is terminated. If a negative decision is obtained in SA1, SA2 is
implemented to determine whether the actual speed V of the hybrid
vehicle is equal to or higher than the predetermined upper limit
V1. If an affirmative decision is obtained in SA2, step SA6 and the
following steps are implemented. If a negative decision is obtained
in SA2, however, the control flow goes to SA3 to determine whether
the actual drive torque of the hybrid vehicle or the actual output
toque T.sub.OUT of the automatic transmission portion 20 is equal
to or higher than the predetermined upper limit T1. If an
affirmative decision is obtained in SA3, step SA6 and the following
steps are implemented. If a negative decision is obtained in SS3,
the control flow goes to SA4 to diagnose the components associated
with the electric path (electric energy transmitting path) through
which an electric energy generated by the first electric motor M1
is converted into a mechanical energy, for example, to determine
whether any one of the first electric motor M1, second electric
motor M2, inverter 58, electric-energy storage device 60, and
electric conductors connecting those components has a deteriorated
function, such as a failure or a functional defect due to a low
temperature.
[0602] If an affirmative decision is obtained in SA4, step SA6 and
the following steps are implemented. If a negative decision is
obtained in SA4, the control flow goes to SA5 corresponding to the
speed-ratio control means 161, in which the speed-ratio control
means 161 commands the hydraulic control unit 42 to release the
switching clutch C0 and the switching brake B0, for placing the
differential portion 11 in the continuously-variable shifting
state, and at the same time enables the hybrid control means 156 to
effect the hybrid control and commands the step-variable control
means 152 to permit the automatic transmission portion 20 to be
automatically shifted. Accordingly, the differential portion 11 is
enabled to function as the continuously variable transmission,
while the automatic transmission portion 20 connected in series to
the differential portion 11 is enabled to function as the
step-variable transmission, so that the drive system provides a
sufficient vehicle drive force, such that the speed of the rotary
motion transmitted to the automatic transmission portion 20 placed
in one of the first-speed, second-speed, third-speed and
fourth-gear positions, namely, the rotating speed of the power
transmitting member 18 is continuously changed, so that the speed
ratio of the drive system when the automatic transmission portion
20 is placed in one of those gear positions is continuously
variable over a predetermined range. Accordingly, the speed ratio
of the automatic transmission portion 20 is continuously variable
across the adjacent gear positions, whereby the overall speed ratio
.gamma.T of the transmission mechanism 10 is continuously
variable.
[0603] If an affirmative decision is obtained in any one of SA2,
SA3 and SA4, the control flow goes to SAG to determine or select
the gear position to which the transmission mechanism 10 should be
shifted. This determination is effected according to the
step-variable-shifting control map 162 stored in the relationship
memory means 154 and shown in FIG. 53. Then, SA7 corresponding to
the high-speed-gear determining means 158 is implemented to
determine whether the gear position of the transmission mechanism
10 which is selected in SA6 is the high-gear position, for example,
the fifth-gear position.
[0604] If an affirmative decision is obtained in SA7, the control
flow goes to SA8 to command the hydraulic control unit 42 to
release the switching clutch C0 and engage the switching brake B0
to enable the differential portion 11 to function as the auxiliary
transmission having the fixed speed ratio .gamma.0 of 0.7, for
example. At the same time, the hybrid control means 156 is disabled
to effect the hybrid control, that is, inhibited from effecting the
hybrid control or continuously-variable shifting control, and the
step-variable shifting control means 152 is commanded to
automatically shift the automatic transmission portion 20 to the
fourth-gear position, so that the transmission mechanism 10 as a
whole is placed in the fifth-gear position selected in SA6. If a
negative decision is obtained in SA76, the control flow goes to SA9
to command the hydraulic control unit 42 to engage the switching
clutch C0 and release the switching brake B0 to enable the
differential portion 11 to function as the auxiliary transmission
having the fixed speed ratio .gamma.0 of 1, for example. At the
same time, the hybrid control means 156 is disabled to effect, that
is, inhibited from effecting the hybrid control or
continuously-variable shifting control, and the step-variable
shifting control means 152 is commanded to automatically shift the
automatic transmission portion 20 to one of the first-gear position
through the fourth-gear position, which was selected in S5. Thus,
SA8 and SA9 are arranged such that the differential portion 11 is
enabled to function as the auxiliary transmission while the
automatic transmission portion 20 connected in series to the
differential portion 11 is enabled to function as the step-variable
transmission, so that the transmission mechanism 10 as a whole
placed in the step-variable transmission is enabled to function as
the so-called step-variable automatic transmission portion. In the
above-described controls, SA6, SA8 and SA9 correspond to steps
performed by the step-variable shifting control means 152, and SA1,
SA5, SA8 and SA9 correspond to steps performed by the hybrid
control means 156, while SA5, SA8 and SA9 correspond to steps
performed by the switching control means 159.
[0605] It will be understood from the foregoing description, the
present embodiment includes the differential portion 11 switchable
between a continuously-variable shifting state in which the
differential portion 11 is operable as an electrically controlled
continuously variable transmission, and a fixed-speed-ratio
shifting state, and further includes the switching control means
159 (SA5, SA8 and SA9) operable to place the differential portion
11 selectively in one of the continuously-variable shifting portion
and the fixed-speed-ratio shifting portion, on the basis of the
vehicle speed and the vehicle load in the form of the output torque
of the vehicle drive system, and according to a predetermined
relationship. Thus, the present embodiment provides a control
device suitable for effecting a shifting control of the
transmission mechanism 10 which is operable as the electrically
controlled continuously variable transmission.
[0606] It is also noted that the present embodiment includes the
transmission mechanism 10 switchable between a
continuously-variable shifting state in which the transmission
mechanism 10 is operable as an electrically controlled continuously
variable transmission, and a step-variable shifting state in which
the transmission mechanism 10 is operable as a step-variable
transmission, and further includes the switching control means 159
operable to place the transmission mechanism 10 selectively in one
of the continuously-variable shifting state and the step-variable
shifting state, on the basis of the vehicle speed and the vehicle
load in the form of the output torque of the vehicle drive system,
and according to a predetermined relationship. Thus, the present
embodiment provides a control device suitable for effecting a
shifting control of the transmission mechanism 10 operable as the
electrically controlled continuously variable transmission.
[0607] It is further noted that the present embodiment includes:
the transmission mechanism 10 switchable between a
continuously-variable shifting state in which the transmission
mechanism 10 is operable as an electrically controlled continuously
variable transmission, and a fixed-speed-ratio shifting state; the
switching control map 166 which defines, with control parameters
consisting of the vehicle speed and the vehicle load or the output
torque of the vehicle drive system, a first region in which the
transmission mechanism 10 is placed in the continuously-variable
shifting state, and a second region in which the transmission
mechanism 10 is placed in the step-variable shifting state; and the
switching control means 159 operable to place the transmission
mechanism 10 selectively in one of the continuously-variable
shifting state and the fixed-speed-ratio shifting state, according
to the switching control map 166. Thus, the present embodiment
provides a control device operable with a simple program for
suitably effecting a shifting control of the transmission mechanism
10 operable as the electrically controlled continuously variable
transmission.
[0608] It is further noted that the present embodiment includes:
the transmission mechanism 10 switchable between a
continuously-variable shifting state in which the transmission
mechanism 10 is operable in an electrically controlled continuously
variable transmission, and the step-variable shifting state in
which the transmission mechanism 10 is operable as a step-variable
transmission; the switching control map 166 which defines, with
control parameters consisting of the vehicle speed and the vehicle
load or the output torque of the vehicle drive system used as the
control parameters, a first region in which the transmission
mechanism 10 is placed in the continuously-variable shifting state,
and a second region in which the transmission mechanism 10 is
placed in the step-variable shifting state; and the switching
control means 159 operable to place the transmission mechanism 10
selectively in one of the continuously-variable shifting state and
the fixed-speed-ratio shifting state, according to the switching
control map 166. Thus, the present embodiment provides a control
device operable with a simple program for suitably effecting a
shifting control of the transmission mechanism 10 operable
selectively as the electrically controlled continuously variable
transmission and the step-variable transmission.
[0609] It is also noted that the present embodiment includes: a
differential-state switching device in the form of the switching
brake B0 and the switching clutch C0 device operable to place the
differential mechanism 16 in a differential state in which the
mechanism 16 is operable as an electrically controlled continuously
variable transmission, and a locked state in which the differential
mechanism 16 is in a non-differential state; the
step-variable-shifting control map 162 which defines, with suitable
control parameters, shifting lines for effecting a shifting control
of the step-variable automatic transmission portion 20; and the
switching control map 166 which defines, with the same control
parameters used for the step-variable-shifting control map 162, a
differential region in which the differential mechanism 16 is
placed in the differential state by the differential-state
switching device, and a non-differential region in which the
differential mechanism 16 is placed in the non-differential state
by the differential-state switching device. Thus, the present
embodiment provides a control device operable with a simple program
for suitably effecting a shifting control of the step-variable
automatic transmission portion 20 and a shifting control of the
transmission mechanism 10 operable selectively as the electrically
controlled continuously variable transmission and the step-variable
transmission.
[0610] It is further noted that the present embodiment includes: a
differential-state switching device in the form of the switching
brake B0 and the switching clutch C0 device operable to place the
differential mechanism 16 in a differential state in which the
mechanism 16 is operable as an electrically controlled continuously
variable transmission, and a locked state in which the differential
mechanism 16 is in a non-differential state; the drive-power-source
selection control map 164 which defines, with suitable control
parameters, a plurality of regions for effecting a
drive-power-source selection control to select at least one drive
power source to be operated to generate a drive force, from among
the engine 8, first electric motor M1 and second electric motor M2;
and the switching control map 166, which defines, with the same
control parameters used for the drive-power-source selection
control map 164, a differential region in which the differential
mechanism 16 is placed in the differential state by the
differential-state switching device, and a non-differential region
in which the differential mechanism 16 is placed in the
non-differential state by the differential-state switching device.
Thus, the present embodiment provides a control device operable
with a simple program for suitably effecting a shifting control of
the step-variable automatic transmission portion 20 and a shifting
control of the transmission mechanism 10 operable selectively as
the electrically controlled continuously variable transmission and
the drive-power-source selection control.
[0611] It is further noted that the present embodiment includes:
the transmission mechanism 10 switchable between a
continuously-variable shifting state in which the transmission
mechanism 10 is operable as a continuously variable transmission,
and a step-variable shifting state in which the transmission
mechanism 10 is operable as a step-variable transmission; the
drive-power-source selection control map 164 which defines, with
suitable control parameters, a plurality of regions for effecting a
drive-power-source selection control to select at least one drive
power source to be operated to generate a drive force, from among
the engine 8, first electric motor M1 and second electric motor M2;
and the switching control map 166, which defines, with the same
control parameters used for the drive-power-source selection
control map 164, a continuously-variable shifting region in which
the transmission mechanism 10 is placed in the
continuously-variable shifting state, and a step-variable shifting
region in which the transmission mechanism 10 is placed in the
step-variable shifting state. Thus, the present embodiment provides
a control device operable with a simple program for suitably
effecting a shifting control of the transmission mechanism 10
operable selectively as the electrically controlled continuously
variable transmission and the step-variable transmission.
[0612] The control parameters used in the present embodiment are
the vehicle speed, and the vehicle load in the form of the output
torque T.sub.OUT of the automatic transmission portion 20, so that
the shifting control of the transmission mechanism 10 operable as
the electrically controlled continuously variable transmission can
be effected with a simple program.
Embodiment 20
[0613] FIG. 63 is a functional block diagram for explaining major
control functions of the electronic control device 40 in another
embodiment of this invention.
[0614] Fuel-economy curve selecting means 280 is arranged to select
a fuel consumption map (hereinafter referred to as "fuel-economy
map) or select one of fuel-economy curves of the engine 8 stored in
fuel-economy curve memory means 282, which permits an optimum
operating state of the engine 10 for the vehicle. The fuel-economy
map is selected by taking account of the fuel economy or energy
efficiency and the vehicle drivability. The fuel-economy map may be
changed in a real-time fashion, or may be obtained by
experimentation and stored in the memory means 282. An example of a
highest-fuel-economy curve is indicated by broken line in FIG. 64.
For instance, the fuel-economy map is defined in a rectangular
two-dimensional coordinate system having an axis along which the
engine speed N.sub.E is taken, and an axis along which the engine
torque Te is taken. The highest-fuel-economy curve is a curve which
connects highest fuel economy points obtained by experimentation
and which extends through a lowest-fuel-consumption region
represented by one of iso-fuel-economy curves indicated by solid
lines, as the engine speed N.sub.E rises. The highest-fuel-economy
curve may be defined by a group of lowest-fuel-consumption points.
In FIG. 64, each of the iso-fuel-economy curves is defined by a
series of points having an equal engine fuel consumption ratio fe.
One of the adjacent regions represented by the adjacent
iso-fuel-economy curves, which one region is located inside the
other, indicates a lower engine fuel consumption ratio fe, that is,
a higher fuel economy. Namely, the highest fuel economy region
corresponds to a medium-speed high-load operating state of the
engine 8.
[0615] The fuel-economy map indicated above is basically determined
by the specifications of the engine 8, and are influenced by a
condition of the vehicle such as internal factors and external
factors of the engine 8. Accordingly, the fuel-economy map changes
with the internal and external factors of the engine such as a
cooling water temperature, a catalyst temperature, a working oil
temperature, and a burning state (that is, an air/fuel ratio
indicative of a lean-burn state, a stoichiometric state, etc.).
Therefore, the fuel-economy curve memory means 282 stores a
plurality of fuel-economy maps on the basis of the above-indicated
internal and external factors, or the stored single fuel-economy
map is changed in the real-time fashion on the basis of the
internal and external factors. In this respect, the fuel-economy
curve selecting means 280 may be considered to select one of the
plurality of fuel economy curves on the basis of the internal and
external factors.
[0616] There will be briefly described a relationship between the
fuel consumption ratio fe and efficiency .eta. of power
transmission from the engine 8 to the drive wheels 38 (hereinafter
referred to as "power transmitting efficiency .eta.").
[0617] Generally, the fuel economy of an engine is represented by
the fuel consumption ratio fe, that is, an amount of fuel
consumption per unit output.times.time (=unit work), and is usually
expressed by grams of fuel consumption per unit output per one
hour, that is, g/psh or g/kWh. Conceptually, the engine fuel
consumption ratio fe is equal to fuel consumption amount F/engine
output Pe. Therefore, the fuel consumption ratio fe decreases or
the fuel economy increases with a decrease in the fuel consumption
amount F and with an increase in the engine output Pe. In other
words, the fuel economy for a given value of the fuel consumption
amount F can be represented by the engine output Pe. The engine
output Pe is higher when the engine 8 is operated along the
highest-fuel-economy curve, than when the engine 8 is not operated
along the highest-fuel-economy curve. In FIG. 64, the broken line
indicates the highest-fuel-economy curve as the fuel-economy map
when the transmission mechanism 10 is operated in the
continuously-variable shifting state, while the solid line
indicates the fuel-economy map when the transmission mechanism 10
is operated in the step-variable shifting state. In the
continuously-variable shifting state, the speed ratio is
continuously changed such that the engine speed N.sub.E changes
with respect to the vehicle speed V, along the highest-fuel-economy
curve. In the step-variable shifting state, the speed ratio changes
in steps, so that the engine speed N.sub.E is held constant with
respect to the vehicle speed V. Although the highest-fuel-economy
curve indicated by the broken line is used as the fuel-economy map
in the continuously-variable shifting state, as distinguished from
the fuel-economy map used in the step-variable shifting state, for
illustrative purpose, the fuel-economy map in the
continuously-variable shifting state need not be consistent with
the highest-fuel-economy curve.
[0618] According to the fuel-economy maps described above, the
engine output Pecvt during running of the vehicle in the
continuously-variable shifting state is higher than the engine
output Peu during running of the vehicle in the step-variable
shifting state, for the same engine speed NE, since the fuel
economy during the vehicle running in the continuously-variable
shifting state is closer to the highest fuel economy curve. That
is, the engine output Pecvt in the continuously-variable shifting
state is always higher than the engine output Peu in the
step-variable shifting state. Generally, a drive-wheel output Pw
obtained by the drive wheels 38 is represented by engine output
Pe.times.power transmitting efficiency .eta..times.system
efficiency .eta.sys of the transmission mechanism 10, and the
drive-wheel output Pwcvt during running of the vehicle in the
continuously-variable shifting state is always higher than the
drive-wheel output Pwu during running of the vehicle in the
step-variable shifting state, for the same value of a product of
the power transmitting efficiency .eta. and the system efficiency
.eta.sys (the product .eta..times..eta.sys being hereinafter
referred to as "vehicle running efficiency .eta.t"). Accordingly,
where the fuel economy is represented by a fuel consumption ratio
fs=fuel consumption amount F/drive-wheel output Pw, the fuel
economy of the vehicle is always higher in the
continuously-variable shifting state than in the step-variable
shifting state, for the same vehicle condition, that is, for the
same vehicle speed V and for the same fuel consumption amount
F.
[0619] Actually, however, the power transmitting efficiency .eta.
is generally higher in the step-variable shifting state in which
the drive force is transmitted primarily through a mechanical power
transmitting path, than in the electrically established
continuously-variable shifting state. In this respect, the
drive-wheel output Pwcvt in the continuously-variable shifting
state (=engine output Pecvt.times.power transmitting efficiency
.eta.cvt.times.system efficiency .eta.sysc, in the
continuously-variable shifting state) is not necessarily higher
than the drive-wheel output Pwu in the step-variable shifting state
(=engine output Peu.times.power transmitting efficiency
.eta.u.times.system efficiency .eta.sysu, in the step-variable
shifting state), depending upon a difference between the engine
output Pecvt in the continuously-variable shifting state and the
engine output Peu in the step-variable shifting state, the power
transmitting efficiency .eta.cvt and system efficiency .eta.sysc in
the electrically established continuously-variable shifting state,
and the power transmitting efficiency .eta.u and system efficiency
.eta.sysu in the step-variable shifting state. Therefore, the fuel
economy of the vehicle is not necessarily higher during the vehicle
running in the continuously-variable shifting state than during the
vehicle running in the step-variable shifting state. From another
point of view, the vehicle running in the step-variable shifting
state having a higher power transmitting efficiency T1 is more
advantageous in terms of the fuel economy, but the vehicle running
in the continuously-variable shifting state in which the fuel
economy is high particularly in a low- and medium-speed running
state is more advantageous in terms of the fuel economy for the
engine per se. In view of this fact, the present embodiment is
arranged to calculate the power transmitting efficiency
.eta.cvt.times.system efficiency .eta.sysc in the
continuously-variable shifting state, and the power transmitting
efficiency .eta.u.times.system efficiency .eta.sysu in the
step-variable shifting state, and to calculate the drive-wheel
output Pwcvt in the continuously-variable shifting state and the
drive-wheel output Pwu in the step-variable shifting state, on the
basis of the engine output Pecvt in the continuously-variable
shifting state and the engine output Peu in the step-variable
shifting state, while taking account of the calculated running
efficiency values .eta.t, in particular, the power transmitting
efficiency values .eta., that is, while taking account of an
influence of a difference of the running efficiency values .eta.t
on the fuel economy. Thus, the fuel economy in the
continuously-variable shifting state and the fuel economy in the
step-variable shifting state are compared with each other.
[0620] The system efficiency .eta.sysc in the continuously-variable
shifting state is obtained on the basis of efficiency values of the
electric system such as charging and discharging efficiency values
of the electric-energy storage device 60, efficiency of the
electric wires and amount of electric energy consumption by the
inverter 48, when the transmission mechanism 10 is operated as the
electrically controlled continuously variable transmission, and on
the basis of a power loss of the oil pump and amount of energy
consumption by optional devices. The system efficiency .eta.sysu in
the step-variable shifting state is obtained on the basis of the
power loss of the oil pump and amount of energy consumption by the
optional devices. In the present embodiment, however, those system
efficiency values .eta.sysc and .eta.sysu are obtained by
experimentation and stored in memory.
[0621] The fuel-economy curve selecting means 280, which is
arranged to select the fuel maps to be used in the
continuously-variable and step-variable shifting states, which are
selected in the fuel-economy curve memory means 282, is further
arranged to read in the engine output Pecvt in the
continuously-variable shifting state and the engine output Peu in
the step-variable shifting state, in the present vehicle condition,
that is, at the present vehicle speed V, on the basis of the
selected fuel-economy maps, for example, the fuel-economy maps
illustrated in FIG. 64. In other words, the engine output values P
are obtained according to the fuel-economy maps, for calculating
the fuel consumption ratio values fs of the vehicle on the basis of
the fuel consumption ratio values fe of the engine 8.
[0622] Power transmitting-efficiency calculating means 284 is
arranged to calculate the fuel consumption ratio values fs in the
continuously-variable and step-variable shifting states of the
transmission mechanism 10, by calculating the running efficiency
.eta.tcvt (power transmitting efficiency .eta.cvt.times.system
efficiency .eta.sysc) in the continuously-variable shifting state,
and the running efficiency .eta.tu (power transmitting efficiency
.eta.u.times.system efficiency .eta.sysu) in the step-variable
shifting state, as the values of efficiency of power transmission
from the engine 8 to the drive wheels 38 in the
continuously-variable and step-variable shifting states.
[0623] FIG. 65 indicates a stored relationship (map) for obtaining
the power transmitting efficiency .eta. on the basis of a
drive-force-related value which relates to the vehicle speed V and
the vehicle drive force. Broke line A indicates an example of the
power transmitting efficiency T1 in the continuously-variable
shifting state, which changes with the vehicle speed V, more
precisely, which increases with an increase in the vehicle speed V,
while solid line A indicates an example of the power transmitting
efficiency .eta. in the step-variable shifting state. Broken line B
and solid line B indicate examples of the power transmitting
efficiency values T1 when the drive-force-related value (e.g.,
output torque Tout) is increased with respect to that of the lines
A. It will be understood from FIG. 65 that the power transmitting
efficiency .eta. changes with a change of the output torque Tout,
that is, increases with an increase in the output torque. The power
transmitting efficiency .eta. increases with an increase in the
vehicle speed and an increase in the output torque, because the
power transmission loss decreases with an increase in the
drive-wheel output Pw. Therefore, the power-transmitting-efficiency
calculating means 284 calculates the power transmitting efficiency
.eta.cvt in the continuously-variable shifting state and the power
transmitting efficiency .eta.u in the step-variable shifting state,
on the basis of the actual vehicle speed, for example, the vehicle
speed V and the drive-force-related value, and according to the
stored relationship described above. Generally, the power
transmitting efficiency .eta.cvt in the continuously-variable
shifting state is about 0.8, which is a power transmitting
efficiency of an electrically controlled continuously variable
transmission, including power transmitting efficiency values of the
first electric motor M1 and the second electric motor M2, and which
is determined by taking account of a power loss of an electric
power transmitting path. On the other hand, the power transmitting
efficiency .eta.u is about 0.92, which is a power transmitting
efficiency of a step-variable transmission having a mechanical
power transmitting path. In the present embodiment, those power
transmitting efficiency values .eta.cvt and .eta.u are changed as a
function of the vehicle condition, according to the stored
relationship.
[0624] As previously described, the drive-force-related value
indicated above is a parameter directly corresponding to the drive
force of the vehicle, which may be the output torque T.sub.OUT of
the automatic transmission portion 20, engine output torque Te or
acceleration value of the vehicle, as well as the drive torque or
drive force of drive wheels 38. The engine output torque Te may be
an actual value calculated on the basis of the operating angle of
the accelerator pedal or the opening angle of the throttle valve
(or intake air quantity, air/fuel ratio or amount of fuel
injection) and the engine speed NE, or an estimated value of a
required vehicle drive force which is calculated on the basis of
the amount of operation of the accelerator pedal by the vehicle
operator or the operating angle of the throttle valve. The
increased toque indicated in FIG. 65 is obtained not only when the
output torque Tout is increased, but also when any other
drive-force-related value such as the operating angle of the
accelerator pedal or the opening angle of the throttle valve is
increased. The fuel injection amount, intake air quantity and
intake negative pressure may also be considered as the
torque-related parameters. The increased torque is also obtained
when a resistance to running of the vehicle is relatively high, for
example, when the vehicle is running on an uphill. The running
resistance includes a rolling resistance, an air resistance and an
acceleration resistance. The rolling resistance and air resistance
relate to the vehicle speed, while the acceleration resistance
relates to the above-described drive-force-related value. In this
respect, the running resistance of the vehicle may be considered as
the drive-force-related value.
[0625] Fuel-consumption-ratio calculating means 286 is arranged to
calculate, from time to time, the fuel consumption ratios fs of the
vehicle in the continuously-variable and step-variable shifting
states. For instance, the fuel-consumption-ratio calculating means
286 calculates the fuel consumption ratio fscvt of the vehicle in
the continuously-variable shifting state (fscvt=fuel consumption
amount F/(engine output Pecvt.times.running efficiency .eta.tcvt in
the continuously-variable shifting state), and the fuel consumption
ratio fsu of the vehicle in the step-variable shifting state (fsu
fuel consumption amount F/(engine output Peu.times.running
efficiency .eta.tu in the step-variable shifting state), on the
basis of the engine output Pecvt and engine output Peu read by the
highest-fuel-economy curve selecting means 280, the running
efficiency .eta.tcvt and running efficiency .eta.tu calculated by
the power-transmitting-efficiency calculating means 284, and the
fuel consumption amount F detected by a fuel consumption sensor
290. Thus, the fuel-consumption-ratio calculating means 286
calculates the fuel consumption ratio fs of the vehicle on the
basis of the vehicle condition in the form of the vehicle speed V
and the drive-force-related value, for example.
[0626] Since the same fuel consumption amount F detected by the
fuel consumption sensor 290 is used to calculate the fuel
consumption ratio values fs in the continuously-variable and
step-variable shifting states, the fuel-consumption-ratio
calculating means 286 may calculate those fuel consumption ratio
values fs, by using a stored constant value of the fuel consumption
amount F. In this case, the calculated fuel consumption ratio
values fs are not necessarily highly accurate and may be considered
to be "values relating to the fuel consumption ratio", but it is
advantageous in that the fuel consumption sensor 290 need not
detect the fuel consumption amount F, or the provision of the
sensor 290 is not necessary.
[0627] In this embodiment, the switching control means 50 places
the transmission mechanism 10 selectively in one of the
continuously-variable shifting state and the step-variable shifting
state, depending upon the shifting state in which the fuel
consumption ratio is lower. The switching control means 50 includes
shifting-state fuel-economy determining means 288, which is
arranged to determine one of the continuously-variable and
step-variable shifting states in which the fuel consumption ratio
is lower, that is, the fuel economy is higher. On the basis of a
result of this determination, the switching control means 50 places
the transmission mechanism 10 in one of the continuously-variable
and step-variable shifting states. The shifting-state fuel-economy
determining means 288 determines whether the fuel consumption ratio
is lower (the fuel economy is higher) in the continuously-variable
shifting state or in the step-variable shifting state, by comparing
the fuel consumption ratio fscvt in the continuously-variable
shifting state and the fuel consumption ration fsu in the
step-variable shifting states, which have been calculated by the
fuel-consumption-ratio calculating means 286.
[0628] Where the fuel-consumption-ratio calculating means 286
calculates the fuel consumption ratio values fs in the
continuously-variable and step-variable shifting states, by using
the constant value of the fuel consumption amount F of the vehicle,
the shifting-state fuel-economy determining means 288 may compare
the drive-wheel output Pwcvt in the continuously-variable shifting
state and the drive-wheel output value Pwu in the step-variable
shifting state, with each other, to determine the shifting state in
which the fuel economy is higher. In this case, the
fuel-consumption-ratio calculating means 286 is required to
calculate only the drive-wheel output values Pwcvt and Pwu in the
respective continuously-variable and step-variable shifting states,
as the values relating to the fuel consumption ratio fs.
[0629] FIG. 66 is a flow chart illustrating one of major control
operations of the electronic control device 40 in the present
embodiment, that is, a switching control of the transmission
mechanism 10 on the basis of the fuel economy of the vehicle. This
switching control is repeatedly executed with an extremely short
cycle time of about several milliseconds to several tens of
milliseconds, for example.
[0630] Initially, step SB1 (hereinafter "step" being omitted)
corresponding to the highest-fuel-economy curve selecting means 280
is implemented to select the fuel-economy maps of the engine 8
stored in the fuel-economy curve memory means 282, and read in the
engine output Pecvt in the continuously-variable shifting state and
the engine output Peu in the step-variable shifting state, on the
basis of the vehicle condition in the form of the vehicle speed V,
and according to the selected fuel-economy maps. The fuel-economy
maps change with the internal and external factors of the engine 8,
such as changes of the cooling water temperature and operating
temperature of the engine, and the burning condition of the engine
(air/fuel ratio indicative of a lean burn state, a stoichiometric
state, etc.).
[0631] Then, SB2 corresponding to the power-transmitting-efficiency
calculating means 284 is implemented to calculate the power
transmitting efficiency .eta.cvt in the continuously-variable
shifting state of the transmission mechanism 10, on the basis of
the vehicle condition in the form of the actual vehicle speed V and
drive-force-related value, and according to the stored relationship
illustrated in FIG. 65 by way of example. Preferably, the running
efficiency .eta.tcvt=power transmitting efficiency
.eta.cvt.times.system efficiency .eta.sysc in the
continuously-variable shifting state is calculated on the basis of
the power transmitting efficiency .eta.cvt and the stored constant
value of the system efficiency .eta.sysc. SB3 corresponding to the
fuel-consumption-ratio calculating means 286 is then implemented to
calculate the fuel consumption ratio fscvt=fuel consumption amount
F/(engine output Pecvt.times.running efficiency .eta.cvt) in the
continuously-variable shifting state, on the basis of the engine
output Pecvt read in SB1 and the running efficiency .eta.tcvt
calculated in SB2.
[0632] Then, SB4 corresponding to the power-transmitting-efficiency
calculating means 284 is implemented to calculate the power
transmitting efficiency .eta.u in the step-variable shifting state
of the transmission mechanism 10, on the basis of the vehicle
condition in the form of the actual vehicle speed V and
drive-force-related value, and according to the stored relationship
illustrated in FIG. 65 by way of example. Preferably, the running
efficiency .eta.tu=power transmitting efficiency
.eta.u.times.system efficiency .eta.sysu in the step-variable
shifting state is calculated on the basis of the power transmitting
efficiency .eta.u and the stored constant value of the system
efficiency .eta.sysu. SB5 corresponding to the
fuel-consumption-ratio calculating means 286 is then implemented to
calculate the fuel consumption ratio fsu=fuel consumption amount
F/(engine output Peu.times.running efficiency .eta.tu) in the
step-variable shifting state, on the basis of the engine output Peu
read in SB1 and the running efficiency .eta.tu calculated in
SB4.
[0633] SB6 corresponding to the shifting-state fuel-economy
determining means 288 is then implemented to determine one of the
continuously-variable and step-variable shifting states in which
the fuel consumption ratio fs is lower (the fuel economy is
higher). This determination is made by comparing the fuel
consumption ratio fscvt in the continuously-variable shifting state
calculated in SB3 and the fuel consumption ratio fsu in the
step-variable shifting state calculated in SB5, with each other.
Preferably, SB6 is formulated to determine whether the fuel economy
is higher in the step-variable shifting state, that is, whether the
operation to switch the transmission mechanism 10 to the
step-variable shifting state is advantageous in terms of the fuel
economy.
[0634] If a negative decision is obtained in SB6, that is, if it is
determined in SB6 that the fuel economy is higher in the
continuously-variable shifting state is higher, SB7 corresponding
to the switching control means 50 is implemented to command the
hydraulic control unit 42 to release the switching clutch C0 and
switching brake B0, for thereby placing the transmission mechanism
10 in the continuously-variable shifting state. At the same time,
the hybrid control means 52 is enabled to effect the hybrid
control, while the step-variable shifting control means 54 is
commanded to select and hold a predetermined one of the gear
positions, or to permit an automatic shifting control according to
the shifting boundary line map (shown in FIG. 12, for example)
stored in the shifting-map memory means 56. In the
continuously-variable shifting state, therefore, the shifting
portion 11 of switchable type functions as the continuously
variable transmission, and the automatic transmission portion 20
connected in series to the shifting portion 11 functions as the
step-variable transmission, so that the drive system provides a
sufficient vehicle drive force, such that the speed of the rotary
motion transmitted to the automatic transmission portion 20 placed
in one of the first-speed, second-speed, third-speed and
fourth-gear positions, namely, the rotating speed of the power
transmitting member 18 is continuously changed, so that the speed
ratio of the drive system when the automatic transmission portion
20 is placed in one of those gear positions is continuously
variable over a predetermined range. Accordingly, the speed ratio
of the automatic transmission portion 20 is continuously variable
through the adjacent gear positions, whereby the overall speed
ratio .gamma.T of the transmission mechanism 10 is continuously
variable.
[0635] If an affirmative decision is obtained in SB6, that is, if
it is determined in SB6 that the fuel economy is higher in the
step-variable shifting state, SB8 corresponding to the switching
control means 50 is implemented to disable the hybrid control means
52 to effect the hybrid control or continuously-variable shifting
control, and enable the step-variable shifting control means 54 to
effect the predetermined step-variable shifting control. In this
case, the step-variable shifting control means 54 effects an
automatic shifting control according to the shifting boundary line
map (shown in FIG. 12, for example) stored the shifting-map memory
means 56. FIG. 2 indicates the combinations of the operating states
of the hydraulically operated frictional coupling devices C0, C1,
C2, B0, B1, B2 and B3, which are selectively engaged for effecting
the step-variable shifting control. In this step-variable automatic
shifting control mode, the shifting portion 11 of switchable type
functions as the auxiliary transmission having a fixed speed ratio
.gamma.0 of 1, with the switching clutch C0 placed in the engaged
state, when the drive system is placed in any one of the
first-speed position through the fourth-speed position. When the
drive system is placed in the fifth-speed position, the switching
brake B0 is engaged in place of the switching clutch C0, so that
the shifting portion 11 of switchable type functions as the
auxiliary transmission having a fixed speed ratio .gamma.0 of about
0.7. In the step-variable automatic shifting control mode,
therefore, the transmission mechanism 10 which includes the
shifting portion 11 functioning as the auxiliary transmission, and
the automatic transmission portion 20, functions as a so-called
step-variable automatic transmission.
[0636] Thus, the transmission mechanism 10, which may function as
an electrically controlled continuously variable transmission that
is generally considered to have a high degree of fuel economy, is
selectively placed in the continuously-variable or step-variable
shifting state in which the fuel economy of the vehicle is higher.
Accordingly, the fuel economy is further improved.
[0637] In the present embodiment described above, the transmission
mechanism 10 of switchable type which is switchable between the
continuously-variable shifting state in which the mechanism 10 is
operable as an electrically controlled continuously-variable
transmission and the step-variable shifting state in which the
mechanism 10 is operable as a step-variable transmission, is
controlled by the switching control means 50 (SB6, SB7, SB8), so as
to be placed selectively in one of the continuously-variable
shifting state and the step-variable shifting state, in which the
fuel consumption ratio f is lower. Accordingly, the vehicle can be
run with improved fuel economy.
[0638] The present embodiment is further arranged such that the
fuel-consumption-ratio calculating means 286 (SB3, SB5) calculates,
from time to time, the fuel consumption ratio values f on the basis
of the vehicle condition such as the vehicle speed V and the
drive-force-related value. That is, the fuel consumption ratio
values f in the continuously-variable shifting state and the
step-variable shifting state are calculated in a real-time fashion,
to place the transmission mechanism 10 in one of the
continuously-variable and step-variable shifting states in which
the fuel economy is higher.
[0639] In the present embodiment, the fuel consumption ratio values
f are calculated on the basis of the fuel consumption ratio fe of
the engine 8 which is obtained according to the stored relationship
illustrated in FIG. 64 by way of example. Accordingly, the fuel
consumption ratio values fs of the vehicle are adequately
calculated by the fuel-consumption-ratio calculating means 286.
[0640] The present embodiment is further arranged such that the
fuel consumption ratio values f calculated on the basis of the
vehicle condition are obtained by taking account of the efficiency
.eta. of power transmission from the engine 8 to the drive wheels
38, which is calculated by the power-transmitting-efficiency
calculating means 284 (SB2, SB4). Accordingly, the fuel consumption
ratio values f are adequately calculated by the
fuel-consumption-ratio calculating means 286.
[0641] The present embodiment is further arranged such that the
fuel consumption ratio values f are adequately calculated by the
fuel-consumption-ratio calculating means 286, on the basis of the
power transmitting efficiency T1 which changes with the running
resistance of the vehicle, for example, with an increase in the
vehicle load as in the vehicle running on an uphill.
[0642] The present embodiment is further arranged such that the
fuel consumption ratio values f are adequately calculated by the
fuel-consumption-ratio calculating means 286, on the basis of the
power transmitting efficiency .eta. which changes with the vehicle
speed V.
[0643] The present embodiment is further arranged such that the
fuel consumption ratio values f are adequately calculated by the
fuel-consumption-ratio calculating means 286, on the basis of the
power transmitting efficiency .eta. which changes with the
drive-force-related value of the vehicle.
[0644] Further, the present embodiment has an advantage that the
power distributing mechanism 16 is simply constituted with a
reduced dimension in its axial direction, by the first planetary
gear set 24 of single-pinion type having three elements consisting
of the first carrier CA1, first sun gear S1 and first ring gear R1.
In addition, the power distributing mechanism 16 is provided with
the hydraulically operated frictional coupling devices in the form
of the switching clutch C0 operable to connect the first sun gear
S1 and the first carrier CA1 to each other, and the switching brake
B0 operable to fix the first sun gear S1 to the transmission casing
12. Accordingly, the transmission mechanism 10 is easily controlled
by the switching control means 50, so as to be placed selectively
in the continuously-variable shifting state and the step-variable
shifting state.
[0645] The present embodiment is further arranged such that the
automatic transmission portion 20 is disposed in series between the
power distributing mechanism 16 and the drive wheels 38, and that
the overall speed ratio of the transmission mechanism 10 is
determined by a speed ratio of the power distributing mechanism 16,
that is, a speed ratio of the shifting portion 11 of switchable
type, and a speed ratio of the automatic transmission portion 20.
Accordingly, the drive force is available over a wide range of
speed ratio, by utilizing the speed ratio of the automatic
transmission portion 20, so that the efficiency of operation of the
shifting portion 11 of switchable type in its continuously-variable
shifting state, that is, the efficiency of the hybrid control can
be improved.
[0646] The present embodiment has a further advantage that the
transmission mechanism 10 provides an overdrive gear position or
the fifth-gear position having a speed ratio lower than 1, when the
transmission mechanism 10 is placed in the step-variable shifting
state in which the shifting portion 11 of switchable type functions
as if it were a part of the automatic transmission portion 20.
[0647] The present embodiment has another advantage that the second
electric motor M2 is connected to the power transmitting member,
which is an input rotary member of the automatic transmission
portion 20, so that the required input torque of the automatic
transmission portion 20 can be made lower than the torque of its
output shaft 22, making it possible to reduce the required size of
the second electric motor M2.
Embodiment 21
[0648] FIG. 67 is a functional block diagram illustrating major
control functions performed by the electronic control device 40
according to another embodiment of this invention, which is a
modification of the embodiment of FIG. 63.
[0649] FIG. 68 shows an example of a shifting boundary line map
(shifting map or relationship) which is stored in the shifting-map
memory means 56 and which is used for determining whether the
automatic transmission portion 20 should be shifted. The shifting
boundary line map consists of shift boundary lines in a rectangular
two-dimensional coordinate system using the vehicle speed V and the
drive-force-related value in the form of the output torque Tout as
control parameters. In FIG. 68, solid lines are shift-up boundary
lines, and one-dot chain lines are shift-down boundary lines. The
shifting boundary line map shown in FIG. 68 is similar to that
shown in FIG. 12, but is different from that of FIG. 12 in that the
continuously-variable shifting region in which the transmission
mechanism 10 is placed in the continuously-variable shifting state
and the step-variable shifting region in which the transmission
mechanism 10 is placed in the step-variable shifting state are
determined by considering which one of the fuel consumption ratio
values fs in the continuously-variable and step-variable shifting
states is lower.
[0650] Namely, FIG. 68 also shows an example of a stored switching
boundary line map (switching map or relationship) which uses the
vehicle speed V and the drive-force-related value in the form of
the output torque Tout as the control parameters, and which is
formulated to place the transmission mechanism 10 in one of the
continuously-variable shifting state and the step-variable shifting
state in which the fuel consumption ratio fs is lower. In FIG. 68,
broken lines and one-dot chain lines that are offset with respect
to the broken lines by a suitable amount of control hysteresis
indicate boundary lines which define the continuously-variable and
step-variable shifting regions and which are obtained by
experimentation conducted to determine which one of the fuel
consumption ratio values fs in the continuously-variable and
step-variable shifting states of the transmission mechanism 10 is
lower. Thus, FIG. 68 shows both the shifting map and the switching
map in the same two-dimensional coordinate system, which are stored
together in the shifting-map memory means 56. The shifting map and
the switching map may be defined in respective different
two-dimensional coordinate systems, and the switching map may be
stored in memory means other than the shifting-map memory means 56,
for example, in switching-map memory means not shown.
[0651] The switching control means 50 in the present embodiment is
not arranged to determine the shifting state of the transmission
mechanism on the basis of the fuel consumption ratio values f in
the manner described above with respect to the preceding
embodiment, but is arranged to place the transmission mechanism 10
selectively in one of the continuously-variable shifting state and
the step-variable shifting state, on the basis of the present
vehicle condition in the form of the actual vehicle speed V and
output torque Tout, and according to the switching map shown in
FIG. 68 by way of example, which is stored in the shifting-map
memory means 56.
[0652] Thus, the transmission mechanism 10, which may function as
an electrically controlled continuously variable transmission that
is generally considered to have a high degree of fuel economy, is
selectively placed in the continuously-variable or step-variable
shifting state in which the fuel economy of the vehicle is higher.
Accordingly, the fuel economy is further improved. Unlike the
preceding embodiment arranged to calculate the fuel consumption
ratio values f from time to time, the present embodiment permits an
easy control of the transmission mechanism, resulting in a reduced
control load of the electronic control device 40.
[0653] In the present embodiment described above, the transmission
mechanism 10 is placed selectively in one of the
continuously-variable and step-variable shifting states, on the
basis of the vehicle condition in the form of the vehicle speed V
and the output torque Tout, and according to the stored
relationship shown in FIG. 68 which defines the shifting regions
corresponding to the respective continuously-variable and
step-variable shifting states such that the transmission mechanism
10 is placed in one of the continuously-variable and step-variable
shifting states in which the fuel consumption ratio f is lower.
Accordingly, the shifting state of the transmission mechanism 10 is
easily selected so as to improve the fuel economy.
Embodiment 22
[0654] FIG. 69 is a functional block diagram illustrating major
control functions of the electronic control device 40 in another
embodiment of this invention, which is another modification of the
embodiment of FIG. 63.
[0655] As shown in FIG. 69, the switching control means 50 further
includes high-speed-running determining means 62,
high-output-running determining means 64 and electric-path-function
diagnosing means 66. The switching control means 50 is arranged to
place the transmission mechanism 10 in the step-variable shifting
state, on the basis of the predetermined vehicle condition, but not
on the basis of the fuel consumption ratio f used in the preceding
embodiments.
[0656] The high-speed-running determining means 62 is arranged to
determine whether the actual running speed V of the hybrid vehicle
has reached a predetermined speed value V1, which is an upper limit
value above which it is determined that the vehicle is in a
high-speed running state. The high-output-running determining means
64 is arranged to determine whether a drive-force-related value
such as the output torque Tout of the automatic transmission
portion 20 relating to the vehicle drive force has reached a
predetermined torque or drive-force value T1, which is an upper
limit value above which it is determined that the vehicle is in a
high-output running state. Namely, the high-output-running
determining means 64 determines whether the vehicle is running with
a high output, on the basis of a drive-force-related parameter
which directly or indirectly represents the drive force with which
the vehicle is driven. The electric-path-function diagnosing means
66 is arranged to determine whether the control components of the
transmission mechanism 10 that are operable to establish the
continuously-variable shifting state have a deteriorated function.
This determination by the diagnosing means 66 is based on the
functional deterioration of the components associated with the
electric path through which an electric energy generated by the
first electric motor M1 is converted into a mechanical energy. For
example, the determination is made on the basis of a failure, or a
functional deterioration or defect due to a failure or low
temperature, of any one of the first electric motor M1, second
electric motor M2, inverter 58, electric-energy storage device 60
and electric conductors connecting those components.
[0657] The upper vehicle-speed limit V1 is obtained by
experimentation and stored in memory, to detect the high-speed
running state of the vehicle in which the transmission mechanism 10
is switched to the step-variable shifting state, since the fuel
economy in the high-speed running state is higher in the
step-variable shifting state than in the continuously-variable
shifting state, that is, to prevent a possibility of deterioration
of the fuel economy if the transmission mechanism 10 were placed in
the continuously-variable shifting state in the high-speed running
of the vehicle. Thus, the transmission mechanism 10 is placed in
the step-variable shifting state, not on the basis of the fuel
consumption ratio value f used in the preceding embodiments, but on
the basis of the actual vehicle speed as compared with the
predetermined upper limit V1.
[0658] The upper output-torque limit T1 is determined depending
upon the operating characteristics of the first electric motor M1,
which is small-sized and the maximum electric energy output of
which is made relatively small so that the reaction torque of the
first electric motor M1 is not so large when the engine output is
relatively high in the high-output running state of the vehicle.
Namely, the upper output-torque limit T1 is determined to detect
the high-output running state of the vehicle in which the
transmission mechanism 10 should be switched to the step-variable
shifting state, that is, to detect the high-output running state of
the vehicle in which the transmission mechanism 10 should not be
operated as an electrically controlled continuously variable
transmission and in which the engine output is higher than a
predetermined upper limit determined based on the nominal output of
the electric motor. Thus, the transmission mechanism 10 is placed
in the step-variable shifting state, not on the basis of the fuel
consumption ratio value f used in the preceding embodiments, but on
the basis of the actual output torque as compared with the
predetermined upper limit T1.
[0659] The switching control means 50 determines that the vehicle
state is in the step-variable shifting region, in any one of the
following conditions or cases: where the high-speed-running
determining means 62 has determined that the vehicle is in the
high-speed running state; where the high-output-running determining
means 64 has determined that the vehicle is in the high-output
running state, that is, in the high-torque running state; and where
the electric-path-function diagnosing means 66 has determined that
the electric path function is deteriorated. In this case, the
switching control means 50 determines that the vehicle is in the
step-variable shifting region in which the transmission mechanism
10 should be switched to the step-variable shifting state, disables
the hybrid control means 52 to operate, that is, inhibits the
hybrid control means 52 from effecting the hybrid control or
continuously-variable shifting control, and commands the
step-variable shifting control means 54 to perform predetermined
step-variable shifting control operations. Thus, the switching
control means 50 places the transmission mechanism 10 in the
step-variable shifting state, on the basis of the predetermined
condition, and places the shifting portion 11 of switchable type in
one of the two gear positions, so that the shifting portion 11
functions as an auxiliary transmission, while the automatic
transmission portion 20 connected in series to the shifting portion
11 functions as a step-variable transmission, whereby the
transmission mechanism 10 as a whole functions as a so-called
step-variable automatic transmission.
[0660] The switching control means 50 may be arranged to select one
of the switching clutch C0 and switching brake B0 which is to be
engaged, such that the switching clutch C0 is engaged when the
high-output-running determining means 64 has determined that the
vehicle is in the high-output running state, while the switching
brake B0 is engaged when the high-speed-running determining means
62 has determined that the vehicle is in the high-speed running
state. However, the fifth-gear position is selected, the switching
control means 50 determines that the switching brake B0 should be
engaged, even when the vehicle is in the high-output running
state.
[0661] FIG. 70 shows a switching map stored in the shifting-map
memory means 56, which is used to determine one of the
continuously-variable shifting state and the step-variable shifting
state, in which the fuel economy is higher than in the other
shifting state. This switching map consists of boundary lines
between the continuously-variable shifting region and the
step-variable shifting region, which are defined in a rectangular
two-dimensional coordinate system having an axis along which the
engine speed NE is taken and an axis along which the engine torque
TE is taken. The switching control means 50 may use this switching
map of FIG. 70, in place of the predetermined conditions described
above, to determine whether the transmission mechanism 10 should be
switched to the step-variable shifting state, on the basis of the
engine speed NE and engine torque TE. That is, the switching
control means 50 may be arranged to determine whether the vehicle
condition represented by the actual engine speed NE and engine
torque TE is in the sep-variable shifting region, and to place the
transmission mechanism 10 in the step-variable shifting region when
the vehicle condition is in the step-variable shifting region,
irrespective of the calculated fuel consumption ratio values.
[0662] That is, the relationship of FIG. 70 indicates a region
corresponding to the regions in which the vehicle speed and output
torque are not lower than the upper limit V1 and upper output
torque limit T1, namely, a high-torque region in which the engine
torque TE is not lower than a predetermined upper limit TE1, a
high-speed region in which the engine speed NE is not lower than an
upper limit NE1, or a high-output region in which the engine output
represented by the engine torque TE and engine speed NE is not
lower than a predetermined upper limit. This relationship is
obtained by experimentation and stored in memory, to determine
whether the transmission mechanism 10 should be switched to the
step-variable shifting state, without relying on the fuel
consumption ratio values f used in the preceding embodiments.
[0663] In the present embodiment described above, the switching
control means 50 places the transmission mechanism 10 in the
step-variable shifting state when the actual vehicle speed has
exceeded the predetermined upper limit V1. Accordingly, while the
actual vehicle speed V is higher than the upper limit V1 above
which the vehicle is in the high-speed running state in which the
fuel economy is higher in the step-variable shifting state of the
transmission mechanism 10, the output of the engine is transmitted
to the drive wheels primarily through the mechanical power
transmitting path, so that the fuel economy of the vehicle is
improved owing to reduction of a loss of conversion of the
mechanical energy into the electric energy, which would take place
when the transmission mechanism 10 is operated as the electrically
controlled continuously variable transmission.
[0664] The present embodiment is further arranged such that the
switching control means 50 places the transmission mechanism 10 in
the step-variable shifting state when the actual output torque Tout
has exceeded the upper limit T1. Accordingly, while the actual
output torque Tout is higher than the upper limit T1 above which
the vehicle is in the high-output running state in which engine
output is higher than a predetermined upper limit determined based
on the nominal rating of the first electric motor M1 and in which
the transmission mechanism 10 should not be operated as an
electrically controlled continuously variable transmission, the
output of the engine 8 is transmitted to the drive wheels 38
primarily through the mechanical power transmitting path. Thus, the
transmission mechanism 10 is operated as the electrically
controlled continuously variable transmission only when the vehicle
is in the low- or medium-output running state, so that the maximum
amount of electric energy that must be generated by the first
electric motor M1 can be reduced, whereby the required output
capacity of the first electric motor M1 can be reduced, making it
possible to minimize the required sizes of the first electric motor
M1 and the second electric motor M2, and the required size of the
drive system including those electric motors.
[0665] The present embodiment is further arranged such that the
switching control means 50 places the transmission mechanism 10 in
the step-variable shifting state, when it is determined that a
predetermined diagnosing condition indicative of functional
deterioration of the control components that are operable to place
the transmission mechanism 10 in the electrically controlled
continuously-variable shifting state is satisfied. Thus, the
vehicle can be run with the transmission mechanism 10 operating in
the step-variable shifting state, even when the transmission
mechanism cannot be normally operated in the continuously-variable
shifting state.
Embodiment 23
[0666] FIG. 71 is a functional block diagram illustrating major
control functions performed by the electronic control device 40 in
another embodiment of this invention. In FIG. 71, the step-variable
control means 54 is arranged to determine whether a shifting action
of the step-variable shifting portion 20 should take place, that
is, determine the gear position to which the step-variable shifting
portion 20 should be shifted. This determination is made on the
basis of the vehicle condition represented by the vehicle speed V
and the output torque T.sub.OUT of the step-variable shifting
portion 20, and according to a shifting boundary line map (shifting
map) which is indicated by solid and one-dot chain lines in FIG. 12
and stored in the shifting-map memory means 56.
[0667] In the present embodiment, the hybrid control means 52 is
arranged to control the engine 8 to be operated with high
efficiency while the transmission mechanism 10 is placed in the
continuously-variable shifting state, that is, while the
differential portion 11 is placed in its differential state. The
hybrid control means 52 is further arranged to control the speed
ratio .gamma.0 of the differential portion 11 operating as an
electrically controlled continuously variable transmission, so as
to establish an optimum proportion of the drive forces produced by
the engine 8 and the second electric motor M2, and to optimize a
reaction force generated during generation of an electric energy by
the first electric motor M1. For instance, the hybrid control means
52 calculates the output as required by the vehicle operator at the
present running speed of the vehicle, on the basis of an operating
amount Acc of the accelerator pedal and the vehicle speed V, and
calculate a required vehicle drive force on the basis of the
calculated required output and a required amount of generation of
the electric energy. On the basis of the calculated required
vehicle drive force, the hybrid control means 52 calculates desired
speed N.sub.E and total output of the engine 8, and controls the
actual output of the engine 8 and the amount of generation of the
electric energy by the first electric motor M1, according to the
calculated desired speed and total output of the engine.
[0668] The hybrid control means 52 is arranged to effect the
above-described hybrid control while taking account of the
presently selected gear position of the step-variable shifting
portion 20, so as to improve the fuel economy of the engine. In the
hybrid control, the differential portion 11 is controlled to
function as the electrically controlled continuously-variable
transmission, for optimum coordination of the engine speed N.sub.E
and vehicle speed V for efficient operation of the engine 8, and
the rotating speed of the power transmitting member 18 determined
by the selected gear position of the step-variable shifting portion
20. That is, the hybrid control means 52 determines a target value
of the overall speed ratio .gamma.T of the transmission mechanism
10, so that the engine 8 is operated according a stored
highest-fuel-economy curve that satisfies both of the desired
operating efficiency and the highest fuel economy of the engine 8.
The hybrid control means 52 controls the speed ratio .gamma.0 of
the differential portion 11, so as to obtain the target value of
the overall speed ratio .gamma.T, so that the overall speed ratio
.gamma.T can be controlled within a predetermined range, for
example, between 13 and 0.5.
[0669] In the hybrid control, the hybrid control means 52 supplies
the electric energy generated by the first electric motor M1, to
the electric-energy storage device 60 and second electric motor M2
through the inverter 58. That is, a major portion of the drive
force produced by the engine 8 is mechanically transmitted to the
power transmitting member 18, while the remaining portion of the
drive force is consumed by the first electric motor M1 to convert
this portion into the electric energy, which is supplied through
the inverter 58 to the second electric motor M2, or subsequently
consumed by the first electric motor M1. A drive force produced by
an operation of the second electric motor M1 or first electric
motor M1 with the electric energy is transmitted to the power
transmitting member 18. Thus, the drive system is provided with an
electric path through which an electric energy generated by
conversion of a portion of a drive force of the engine 8 is
converted into a mechanical energy. This electric path includes
components associated with the generation of the electric energy
and the consumption of the generated electric energy by the second
electric motor M2. It is also noted that the hybrid control means
52 is further arranged to establish a motor drive mode in which the
vehicle is driven with only the electric motor (e.g., second
electric motor M2) used as the drive power source, by utilizing the
electric CVT function (differential function) of the differential
shifting portion 11, irrespective of whether the engine 8 is in the
non-operated state or in the idling state. The hybrid control means
52 can establish the motor drive mode by operation of the first
electric motor M1 and/or the second electric motor M2, even when
the differential portion 11 is placed in the step-variable shifting
state (fixed-speed-ratio shifting state) while the engine 8 is in
its non-operated state.
[0670] The hybrid control means 52 is also arranged to effect a
regenerative braking control to adjust an amount of generation of
an electric energy by the electric motor M1 and/or electric motor
M2, on the basis of the vehicle speed and/or an amount of operation
of a braking device, during deceleration or braking of the vehicle.
In this regenerative braking control, the electric energy generated
by the electric motor M1 and/or electric motor M2 is stored in the
electric energy-storage device 50 through the inverter 58.
[0671] FIG. 54 shows an example of a stored relationship, namely, a
boundary line p) which defines an engine drive region and a motor
drive region and which is used to select one of the engine 8 and
the electric motors M1, M2, as the drive power source (one of the
engine drive mode and the motor drive mode). That is, the stored
relationship is represented by a drive-power-source switching
boundary line map (drive-power-source map) in a rectangular
two-dimensional coordinate system using the vehicle speed V and the
drive-force-related value in the form of the output torque
T.sub.OUT as control parameters. FIG. 54 also shows a one-dot chain
line which is located inside the solid boundary line, by a suitable
amount of control hysteresis. For example, the drive-power-source
switching boundary line map shown in FIG. 54 is stored in the
shifting-map memory means 56. As is apparent from FIG. 54, the
hybrid control means 52 selects the motor drive mode when the
output torque T.sub.OUT is comparatively small, or when the vehicle
speed is comparatively low, that is, when the vehicle load is in a
comparatively low range in which the operating efficiency of the
engine is generally lower than in a comparatively high range.
[0672] For reducing a tendency of dragging of the engine 8 held in
its non-operated state with a fuel-cut control in the motor drive
mode, for thereby improving the fuel economy, the hybrid control
means 52 controls the differential portion 11 so that the engine
speed N.sub.E is held substantially zero, that is, held zero or
close to zero, owing to the differential function of the
differential portion 11. Where the vehicle is run with the output
torque of the second electric motor M2, for example, the first
electric motor M1 is freely rotated in the negative direction so
that the engine speed N.sub.E (rotating speed of the first carrier
CA1) is held substantially zero while the second electric motor M2
is operated at a speed corresponding to the vehicle speed V.
[0673] The high-speed-gear determining means 68 is arranged to
determine whether the gear position which is selected on the basis
of the vehicle condition and according to the shifting boundary
line map shown in FIG. 12 and stored in the shifting-map memory
means 56 and to which the drive transmission mechanism 10 should be
shifted is the high-speed-gear position, for example, the
fifth-gear position. This determination by the high-speed-gear
determining means 68 is made to determine which one of the
switching clutch C0 and brake B0 should be engaged to place the
transmission mechanism 10 in the step-variable shifting state.
[0674] The switching control means 50 is arranged to place the
transmission mechanism 10 selectively one of the
continuously-variable shifting state and the step-variable shifting
state, by determining whether the vehicle condition represented by
the vehicle speed V and the output torque T.sub.OUT is in the
continuously-variable shifting region in which the transmission
mechanism 10 should be placed in the continuously-variable shifting
state, or in the step-variable shifting state in which the
transmission mechanism 10 should be placed in the step-variable
shifting state. This determination is made according to the
switching boundary line map (switching map or relationship
indicated by broken and two-dot chain lines in FIG. 12, which map
is stored in the shifting-map memory means 56.
[0675] When the switching control means 50 determines that the
vehicle condition is in the continuously-variable shifting region,
the switching control means 50 disables the hybrid control means 52
effect a hybrid control or continuously-variable shifting control,
and enables step-variable shifting control means 54 to effect a
predetermined step-variable shifting control. In this case, the
step-variable shifting control means 54 effects an automatic
shifting control according to the shifting boundary line map shown
in FIG. 12 and stored in shifting-map memory means 56. FIG. 2
indicates the combinations of the operating states of the
hydraulically operated frictional coupling devices C0, C1, C2, B0,
B1, B2 and B3, which are selectively engaged for effecting the
step-variable shifting control. In this automatic step-variable
shifting control mode, the transmission mechanism 10 as a whole
consisting of the differential portion 11 and the step-variable
shifting portion 20 functions as a so-called "step-variable
automatic transmission", the gear positions of which are
established according to the table of engagement of the frictional
coupling devices shown in FIG. 2.
[0676] When the high-speed-gear determining means 68 determines
that the fifth-gear position should be established as the high-gear
position, the switching control means 50 commands the hydraulic
control unit 42 to release the switching clutch C0 and engage the
switch brake B0, so that the differential portion 11 functions as
an auxiliary transmission having a fixed speed ratio .gamma.0, for
example, a speed ratio .gamma.0 of 0.7, whereby the transmission
mechanism 10 as a whole is placed in a so-called "overdrive gear
position" having a speed ratio lower than 1.0. When the
high-speed-gear determining means 68 determines that a gear
position other than the fifth-gear position should be established,
the switching control means 50 commands the hydraulic control unit
42 to engage the switching clutch C0 and release the switching
brake B0, so that the differential portion 11 functions as an
auxiliary transmission having a fixed speed ratio .gamma.0, for
example, a speed ratio .gamma.0 of 1, whereby the transmission
mechanism 10 as a whole is placed in a low-gear position the speed
ratio of which is not lower than 1.0. Thus, the transmission
mechanism 10 is switched to the step-variable shifting state, by
the switching control means 50, and the differential portion 11
placed in the step-variable shifting state is selectively placed in
one of the two gear positions, so that the differential portion 11
functions as the auxiliary transmission, while at the same time the
step-variable shifting portion 20 connected in series to the
differential portion 11 functions as the step-variable
transmission, whereby the transmission mechanism 10 as a whole
functions as a so-called "step-variable automatic transmission
portion".
[0677] When the switching control means 50 determines that the
vehicle condition is in the continuously-variable shifting region
for placing the transmission mechanism 10 in the
continuously-variable shifting state, on the other hand, the
switching control means 50 commands the hydraulic control unit 42
to release the switching clutch C0 and the switching brake B0 for
placing the differential portion 11 in the continuously-variable
shifting state, so that the transmission mechanism 10 as a whole is
placed in the continuously-variable shifting state. At the same
time, the switching control means 50 enables the hybrid control
means 52 to effect the hybrid control, and commands the
step-variable shifting control means 54 to select and hold a
predetermined one of the gear positions, or to permit an automatic
shifting control according to the step-variable-shifting control
map of FIG. 12 stored in the shifting-map memory means 56. In the
latter case, the variable-step shifting control means 54 effects
the automatic shifting control by suitably selecting the
combinations of the operating states of the frictional coupling
devices indicated in the table of FIG. 2, except the combinations
including the engagement of the switching clutch C0 and brake B0.
Thus, the differential portion 11 placed in the
continuously-variable shifting state under the control of the
switching control means 50 functions as the continuously variable
transmission while the step-variable shifting portion 20 connected
in series to the differential portion 11 functions as the
step-variable transmission, so that the drive system provides a
sufficient vehicle drive force, such that the speed of the rotary
motion transmitted to the step-variable shifting portion 20 placed
in one of the first-speed, second-speed, third-speed and
fourth-gear positions, namely, the rotating speed of the power
transmitting member 18 is continuously changed, so that the speed
ratio of the drive system when the step-variable shifting portion
20 is placed in one of those gear positions is continuously
variable over a predetermined range. Accordingly, the speed ratio
of the step-variable shifting portion 20 is continuously variable
through the adjacent gear positions, whereby the overall speed
ratio .gamma.T of the transmission mechanism 10 as a whole is
continuously variable.
[0678] The control maps shown in FIG. 12 will be described in
detail. Solid lines in FIG. 12 are shift-up boundary lines, while
one-dot chain lines are shift-down boundary lines. Broken lines in
FIG. 12 indicate an upper vehicle-speed limit V1 and an upper
output-torque limit T1 which are used to determine whether the
vehicle condition is in the step-variable shifting region or the
continuously-variable shifting region. That is, the broke lines in
FIG. 12 are a predetermined upper vehicle-speed limit line
consisting of a series of upper speed limits V1 for determining
whether the hybrid vehicle is in the high-speed running state, and
a predetermined upper output limit line consisting of a series of
upper output limits in the form of upper limits T1 of the output
torque T.sub.OUT of the step-variable shifting portion 20 as a
drive-force-related value for determining whether the hybrid
vehicle is in the high-output running state. Two-dot chain lines
also shown in FIG. 12 are limit lines which are offset with respect
the broken lines, by a suitable amount of control hysteresis, so
that the broken lines and the two-dot chain lines are selectively
used as the boundary lines defining the step-variable shifting
region and the continuously-variable shifting region. These
boundary lines of FIG. 12 are stored switching boundary line maps
(switching maps or relationships) each of which includes the upper
vehicle-speed limit V1 and the upper output torque limit T1 and is
used by the switching control means 50 to determine whether the
vehicle condition is in the step-variable shifting region or
continuously-variable shifting region, on the basis of the vehicle
speed V and the output torque T.sub.OUT. These switching boundary
line maps may be included in the shifting maps stored in the
shifting-map memory means 56. The switching boundary line maps may
include at least one of the upper vehicle-speed limit V1 and the
upper output-torque limit T1, and may use only one of the vehicle
speed V and the output torque T.sub.OUT as a control parameter. The
shifting boundary line maps, switching boundary line maps, etc.
described above may be replaced by equations for comparison of the
actual value of the vehicle speed V with the upper vehicle-speed
limit V1, and equations for comparison of the actual value of the
output torque T.sub.OUT with the upper output-torque limit T1.
[0679] The upper vehicle-speed limit V1 is determined so that the
transmission mechanism 10 is placed in the step-variable shifting
state while the vehicle speed V is higher than the upper limit V1.
This determination is effective to minimize a possibility of
deterioration of the fuel economy of the vehicle if the
transmission mechanism 10 were placed in the continuously-variable
shifting state at a relatively high running speed of the vehicle.
The upper output-torque limit T1 is determined depending upon the
operating characteristics of the first electric motor M1, which is
small-sized and the maximum electric energy output of which is made
relatively small so that the reaction torque of the first electric
motor M1 is not so large when the engine output is relatively high
in the high-output running state of the vehicle.
[0680] FIG. 8 shows a switching boundary line map (switching map or
relationship) which is stored in the shifting-map memory means 56
and which has switching boundary lines in the form of engine output
lines defining a step-variable shifting region and a
continuously-variable shifting region one of which is selected by
the switching control means 50 on the basis of parameters
consisting of the engine speed N.sub.E and engine torque T.sub.E.
The switching control means 50 may use the switching boundary line
map of FIG. 8 in place of the switching boundary line map of FIG.
12, to determine whether the vehicle condition represented by the
engine speed N.sub.E and engine torque T.sub.E is in the
continuously-variable shifting region or in the step-variable
shifting region. The broken lines in FIG. 12 can be generated on
the basis of the switching boundary line map of FIG. 8. In other
words, the broken lines of FIG. 12 are switching boundary lines
which are defined on the basis of the relationship (map) of FIG. 8,
in the rectangular two-dimensional coordinate system having
parameters consisting of the vehicle speed V and the output torque
T.sub.OUT.
[0681] As shown in FIG. 12, the step-variable shifting region is
set to be a high output-torque region in which the output torque
T.sub.OUT is not lower than the upper output-torque limit T1, and a
high vehicle-speed region in which the vehicle speed V is not lower
than the upper vehicle-speed limit V1. Accordingly, the
step-variable shifting control is effected when the vehicle is in a
high-output running state with a comparatively high output of the
engine 8 or when the vehicle is in a high-speed running state,
while the continuously-variable shifting control is effected when
the vehicle is in a low-output running state with a comparatively
low output of the engine 8 or when the vehicle is in a low-speed
running state, that is, when the engine 8 is in a normal output
state. Similarly, the step-variable shifting region indicated in
FIG. 8 is set to be a high-torque region in which the engine output
torque T.sub.E is not lower than a predetermined value T.sub.E1, a
high-speed region in which the engine speed N.sub.E is not lower
than a predetermined value N.sub.E1, or a high-output region in
which the engine output determined by the output torque T.sub.E and
speed N.sub.E of the engine 8 is not lower than a predetermined
value. Accordingly, the step-variable shifting control is effected
when the torque, speed or output of the engine 8 is comparatively
high, while the continuously-variable shifting control is effected
when the torque, speed or output of the engine is comparatively
low, that is, when the engine is in a normal output state. The
switching boundary lines in FIG. 8, which defines the step-variable
shifting region and the continuously-variable shifting region,
function as an upper vehicle-speed limit line consisting of a
series of upper vehicle-speed limits, and an upper output limit
line consisting of a series of upper output limits.
[0682] Therefore, when the vehicle is in a low- or medium-speed
running state or in a low- or medium-output running state, the
transmission mechanism 10 is placed in the continuously-variable
shifting state, assuring a high degree of fuel economy of the
vehicle. When the vehicle is in a high-speed running state with the
vehicle speed V exceeding the upper vehicle-speed limit V1, on the
other hand, the transmission mechanism 10 is placed in the
step-variable shifting in which the transmission mechanism 10 is
operated as a step-variable transmission, and the output of the
engine 8 is transmitted to the drive wheels 38 primarily through
the mechanical power transmitting path, so that the fuel economy is
improved owing to reduction of a loss of conversion of the
mechanical energy into the electric energy, which would take place
when the transmission mechanism 10 is operated as an electrically
controlled continuously variable transmission. When the vehicle is
in a high-output running state in which the drive-force-related
value in the form of the output torque T.sub.OUT exceeds the upper
output-torque limit T1, the transmission mechanism 10 is also
placed in the step-variable shifting state. Therefore, the
transmission mechanism 10 is placed in the continuously-variable
shifting state or operated as the electrically controlled
continuously variable transmission, only when the vehicle speed is
relatively low or medium or when the engine output is relatively
low or medium, so that the required amount of electric energy
generated by the first electric motor M1, that is, the maximum
amount of electric energy that must be transmitted from the first
electric motor M1 can be reduced, whereby the required electrical
reaction force of the first electric motor M1 can be reduced,
making it possible to minimize the required sizes of the first
electric motor M1, and the required size of the drive system
including the electric motor. In other words, the transmission
mechanism 10 is switched from the continuously-variable shifting
state to the step-variable shifting state (fixed-speed-ratio
shifting state) in the high-output running state of the vehicle in
which the vehicle operator desires an increase of the vehicle drive
force, rather than an improvement in the fuel economy. Accordingly,
the vehicle operator is satisfied with a change of the engine speed
N.sub.E as a result of a shift-up action of the automatic
transmission portion in the step-variable shifting state, that is,
a comfortable rhythmic change of the engine speed N.sub.E, as
indicated in FIG. 10.
[0683] Referring back to FIG. 71, fuel-cut control means 378 is
arranged to cut a fuel supply to the engine 8 when a predetermined
fuel-cut condition is satisfied, for example, when a decelerating
run of the vehicle is continued for more than a predetermined time
with a required drive-force-related value being zero. The required
drive-force-related value may be the operating angle Acc of the
accelerator pedal, the opening angle .theta..sub.th of the throttle
valve or the amount of fuel injection during running of the
vehicle.
[0684] Step-variable-shifting-run determining means 380 is arranged
to determine whether the vehicle is in a step-variable-shifting
run. This determination may be made on the basis of an output of
the switching control means 50. or an output of the switch 44
provided to select the step-variable shifting state.
Engine-fuel-economy map memory means 382 stores the engine
fuel-economy map shown in FIG. 61 by way of example. This
engine-fuel-economy map is a relationship which is obtained by
experimentation and which is defined in a two-dimensional
coordinate system having an engine-speed axis AX1 and an
engine-output-torque axis AX2. The engine-fuel-economy map includes
iso-fuel-economy curves L1 like contour lines indicated by solid
lines, a highest fuel-economy curve L2 indicated by broke line, and
iso-horsepower lines L3 indicated by one-dot chain lines. One of
the adjacent highest-fuel-economy curves L2 which is located inside
the other indicates a higher fuel economy, and each of the
iso-horsepower curves L3 indicates an increase of the horsepower
with an increase of the engine speed. Motor-efficiency map memory
means 384 stores an efficiency map of the first electric motor M1
shown in FIG. 72 by way of example, and an efficiency map of the
second electric motor shown in FIG. 73 by way of example. These
efficiency maps of the first and second electric motors M1, M2 are
defined a two-dimensional coordinate system having an axis of the
speed and an axis of the output torque, and have efficiency curves
L4 in the form of contour lines indicated by solid lines. One of
the adjacent efficiency curves L4 which is located inside the other
indicates a higher efficiency.
[0685] Continuously-variable-shifting-run speed-ratio control means
(hereinafter referred to as "speed-ratio control means") 386 is
arranged to control the speed ratio .gamma. of the step-variable
shifting portion 20 and the speed ratio .gamma.0 of the
differential portion (continuously variable transmission portion)
11, so as to maximize the fuel economy, on the basis of the
operating efficiency .eta.M1 of the first electric motor M1 and the
operating efficiency .eta.M2 of the second electric motor M2, when
it is determined that the continuously-variable shifting portion in
the form of the differential portion (continuously-variable
shifting portion) 11 is in the continuously-variable shifting
state. For instance, the speed-ratio control means 161 adjusts the
speed ratio .gamma. of the step-variable shifting portion 20 to
thereby change the speed ratio .gamma.0 of the differential portion
(continuously-variable shifting portion) 11, so as to reduce the
output shaft speed (input shaft speed of the step-variable shifting
portion 20) N.sub.IN of the differential portion 11, for the
purpose of preventing reverse rotation of the first electric motor
M1 even in a steady-state running state of the vehicle at a
comparatively high speed.
[0686] The speed-ratio control means 386 includes
target-engine-speed calculating means 388 for determining a target
speed N.sub.EM of the engine 8 on the basis of the actual operating
angle Acc of the accelerator pedal and according to the
engine-fuel-economy map shown in FIG. 61, which is stored in the
engine-fuel-economy memory means 382. The speed-ratio control means
386 further includes two-speed-rations determining means 390 for
determining, on the basis of the actual vehicle speed V, the speed
ratio .gamma. of the step-variable shifting portion 20 and the
speed ratio .gamma.0 of the differential portion
(continuously-variable shifting portion) 11, which speed ratios
give the target engine speed N.sub.EM.
[0687] The target-engine-speed calculating means 388 is arranged to
select, according to a well-known relationship, one of
iso-horsepower curves L3a (shown in FIG. 61) which corresponds to
the output of the engine 8, on the basis of the actual operating
angle Acc of the accelerator pedal representative of the vehicle
drive force as required by the vehicle operator. The
target-engine-speed calculating means 388 determines, as the target
engine speed N.sub.EM, the engine speed corresponding to a point Ca
of intersection between the selected iso-horsepower curve L3a and
the highest-fuel-economy curve L2, as indicated in FIG. 61.
[0688] The two-speed-ratios determining means 390 is arranged to
determine the overall speed ratio .gamma.T of the transmission
mechanism 10 that gives the target engine speed N.sub.EM, on the
basis of the target engine speed N.sub.EM and the actual vehicle
speed V, and according to the equation (1), for example. A
relationship between the rotating speed N.sub.OUT(rpm) of the
output shaft 22 of the step-variable shifting portion 20 and the
vehicle speed V (km/h) is represented by the equation (2), wherein
the speed ratio of the final speed reducer 36 is represented by
.gamma.f, and the radius of the drive wheels 38 is represented by
r. Then, the speed-ratio control means two-speed-ratios determining
means 390 determines, according to the equations (1), (2), (3) and
(4), the speed ratio .gamma. of the step-variable shifting portion
20 and the speed ratio .gamma.0 of the differential portion
(continuously-variable shifting portion) 11, which give the overall
speed ratio .gamma.T (=.gamma..times..gamma.0) of the transmission
mechanism 10 and which maximize the overall power transmitting
efficiency of the transmission mechanism 10.
[0689] The speed ratio .gamma.0 of the differential portion
(continuously-variable shifting portion) 11 varies from zero to 1.
Initially, therefore, a plurality of candidate speed ratio values
.gamma.a, .gamma.b, etc. of the step-variable shifting portion 20
that give the engine speed N.sub.E higher than the target engine
speed N.sub.EM when the speed ratio .gamma.0 is assumed to be 1 are
obtained on the basis of the actual vehicle speed V and according
to the relationships between the engine speed N.sub.E and the
vehicle speed V as represented by the equations (1) and (2). Then,
fuel consumption amounts Mfce corresponding to the candidate speed
ratio values .gamma.a, .gamma.b, etc. are calculated on the basis
of the overall speed ratio .gamma.T that give the target engine
speed N.sub.EM, and the candidate speed ratio values .gamma.a,
.gamma.b, etc., and according to the equation (3), for example. One
of the candidate speed ratio values which corresponds to the
smallest one of the calculated fuel consumption values Mfce is
determined as the speed ratio .gamma. of the step-variable shifting
portion 20. The speed ratio .gamma.0 of the differential portion
(continuously-variable shifting portion) 11 is determined on the
basis of the determined speed ratio .gamma. and the overall speed
ratio .gamma.T that gives the target engine speed N.sub.EM.
[0690] In the equation (3), Fce, PL, .eta.ele, .eta.CVT, k1, k2 and
.eta.gi represent the following: Fce=fuel consumption ratio;
PL=instantaneous required drive force; .eta.ele=efficiency of the
electric system; .eta.CVT=power transmitting efficiency of the
differential portion 11; k1=power transmitting ratio of the
electric path of the differential portion 11; k2=power transmitting
ratio of the mechanical path of the differential portion 11; and
.eta.gi=power transmitting efficiency of the step-variable shifting
transmission portion. Efficiency .eta.M1 of the first electric
motor .eta.M1 and efficiency M2 of the second electric motor M2 in
the equation (3) are obtained according to the relationships of
FIGS. 72 and 73, on the basis of the rotating speeds which give the
overall speed ratio .gamma.T of the differential portion 11 to
obtain the target engine speed N.sub.EM for each of the candidate
speed ratio values .gamma.a, .gamma.b, etc. and which correspond to
candidate speed ratio values .gamma.0a, .gamma.0b, etc. of the
differential portion 11, and on the basis of the output torque
values of the electric motors required to generate the required
vehicle drive force. The ratio k1 is usually about 0.1, while the
ratio k2 is usually about 0.9. However, the ratios k1 and k2 vary
as a function of the required vehicle output. The power
transmitting efficiency .eta.gi of the step-variable shifting
portion 20 is determined as a function of a transmitted torque Ti
(which varies with the selected gear position i), a rotating speed
Ni of the rotating member, and an oil temperature H. For
convenience' sake, the fuel consumption ratio Fce, instantaneous
required drive force PL, efficiency .eta.ele of the electric system
and power transmitting efficiency .eta.CVT of the differential
portion 11 are held constant. Further, The power transmitting
efficiency .eta.gi of the step-variable shifting portion 20 may be
held constant, as long as the use of a constant value as the
efficiency .eta.gi does not cause an adverse influence.
[0691] The speed-ratio control means 386 commands the step-variable
shifting control means 54 and the hybrid control means 52 to
perform the respective step-variable shifting and hybrid control
functions, so as to establish the determined speed ratio .gamma. of
the step-variable shifting portion 20 and the determined speed
ratio .gamma.0 of the differential portion 11.
[0692] When the continuously-variable-shifting-run determining
means 380 has determined that the differential portion is not in
the continuously-variable shifting state, that is, is in the
step-variable shifting state, however, the speed-ratio control
means 386 commands the step-variable shifting control means 54 to
effect the step-variable shifting control, according to the
shifting boundary line map which is stored in the shifting-map
memory means 56 and which is shown in FIG. 74 by way of example.
According to this shifting boundary line map shown in FIG. 74, the
shifting boundary lines are determined such that the operating
point of the engine is close to a highest fuel-economy point,
namely, such that the engine speed N.sub.E is close to the
above-described target engine speed N.sub.EM. Accordingly, the
shifting boundary lines of FIG. 74 are determined such that the
step-variable shifting portion 20 is shifted up at lower vehicle
speeds, than according to the shifting boundary lines of FIG. 12.
However, the step-variable shifting portion 20 may be shifted to
its gear position or to select its speed ratio .gamma., which gear
position or speed ratio makes it possible to control the engine
speed N.sub.E to a value which is as close as possible to the
target engine speed N.sub.EM obtained according to the
engine-fuel-economy map of FIG. 61.
[0693] FIG. 75 is a flow chart illustrating one of major control
operations of the electronic control device 40, that is, a
speed-ratio control operation in the continuously-variable shifting
state, in the present embodiment. This speed-ratio control is
repeatedly executed with an extremely short cycle time of about
several milliseconds to several tens of milliseconds, for example.
FIG. 76 is a flow chart illustrating a speed-ratio calculating
routine shown in FIG. 75.
[0694] Initially, step SC1 (hereinafter "step" being omitted)
corresponding to the above-described step-variable-shifting-run
determining means 380 is implemented to determine whether the
vehicle is in the continuously-variable shifting run. This
determination is made on the basis of the output of the switching
control means 50 or the output of the switch 44. If an affirmative
decision is obtained in SA1, the control flow goes to SC2 to read
in the engine-fuel-economy map stored in the engine-fuel-economy
map memory means 82, and then goes to SC3 to read in the efficiency
map of FIG. 72 the first electric motor M1 stored in the
motor-efficiency-map memory means 384, and to SC4 to read in the
efficiency map of FIG. 73 of the second electric motor M2 stored in
the stored in the motor-efficiency-map memory means 384. Then, SC5
corresponding to the above-described
continuously-variable-shifting-run speed-ratio control means 386 is
implemented to execute the speed-ratio calculating routine, and SC6
is implemented to effect the speed-ratio control.
[0695] Referring to FIG. 76 illustrating the speed-ratio
calculating routine in SC5, SC51 is implemented to read in the
actual vehicle speed V and operating angle Acc of the throttle
valve. Then, SC52 and SC53 corresponding to the above-described
target-engine-speed calculating means 388 are implemented. SC52 is
provided to select one curve L3a of the iso-horsepower curves shown
in FIG. 61, which one curve L3a corresponds to an output of the
engine 8 satisfying the operator's required vehicle drive force.
This selection is made on the basis of the iso-horsepower curves L3
shown in FIG. 61 and the actual operating angle Acc of the
accelerator pedal. The selected iso-horsepower curve L3a indicates
the target engine output satisfying the operator's required vehicle
drive force. Then, SC53 is implemented to determine, as the target
engine speed N.sub.EM, the engine speed corresponding to the
intersection point Ca between the determined iso-horsepower curve
L3a and the highest fuel-economy curve L2. SC54 corresponding to
the above-described two-speed-ratios determining means 390 is
implemented to determine, according to the equation (1), for
example, the overall speed ratio .gamma.T of the transmission
mechanism 10 for obtaining the target engine speed N.sub.EM, on the
basis of the target engine speed N.sub.EM and the actual vehicle
speed V. The speed ratio .gamma. of the step-variable shifting
portion 20 and the speed ratio .gamma.0 of the differential portion
(continuously-variable shifting portion) 11, which give the
determined overall speed ratio .gamma.T of the transmission
mechanism 10 and which permit the maximum overall power
transmitting efficiency of the transmission mechanism 10, are
determined according to the equations (1), (2), (3) and (4).
[0696] Referring back to FIG. 75, SC6 is implemented to command the
step-variable shifting control means 54 and the hybrid control
means 52, so as to establish the determined speed ratio .gamma. of
the step-variable shifting portion 20 and the determined speed
ratio .gamma.0 of the differential portion (continuously-variable
shifting portion) 11.
[0697] If a negative decision is obtained in SC1, the control flow
goes to SC7 identical to step SC2, to read in the engine-fuel map
of FIG. 61 stored in the engine-fuel-map memory means 382. Then,
SC8 is implemented to calculate, as a highest-fuel-economy
step-variable gear position, or a highest-fuel-economy speed ratio,
the gear position or speed ratio .gamma. of the step-variable
shifting portion 20, which permits the engine speed NE to be as
close as possible to the target engine speed N.sub.EM obtained
according to the engine-fuel-economy map. Then, SC6 is implemented
to command the step-variable shifting control means 54 to effect
the shifting control, so as to obtain the speed ratio .gamma. of
the step-variable shifting portion 20, which has been determined as
the highest-fuel-economy speed ratio.
[0698] In the present embodiment described above, the speed-ratio
control means 386 is arranged to control the speed ratio .gamma. of
the step-variable shifting portion 20 and the speed ratio .gamma.0
of the differential portion (continuously-variable shifting
portion) 11, so as to maximize the fuel economy, in the
continuously-variable shifting state of the differential portion
(continuously-variable shifting portion) 11, so that the fuel
economy is improved in the present embodiment, as compared with
that in the case where those speed ratios are controlled
independently of each other. For instance, the speed-ratio control
means 386 controls the speed ratio .gamma. of the step-variable
shifting portion 20 so as to prevent reverse rotation of the first
electric motor M1 in the differential portion
(continuously-variable shifting portion) 11 as indicated in FIG. 4,
even in a steady-state running state of the vehicle at a
comparatively high speed. Accordingly, the fuel economy of the
vehicle as a whole can be maximized.
[0699] The present embodiment is further arranged such that the
speed-ratio control means 386 controls the speed ratio .gamma.0 of
the differential portion (continuously-variable shifting portion)
11, depending upon the speed ratio .gamma. of the step-variable
shifting portion 20, in the continuously-variable shifting state of
the differential portion (continuously-variable shifting portion)
11. Thus, the speed ratios of the step-variable shifting portion 20
and the differential portion (continuously-variable shifting
portion) 11 are controlled to improve the power transmitting
efficiency of the vehicle as a whole. For instance, the speed-ratio
control means 386 controls the speed ratio .gamma. of the
step-variable shifting portion 20 so as to prevent reverse rotation
of the first electric motor M1 in the differential portion
(continuously-variable shifting portion) 11 as indicated in FIG. 4,
even in a steady-state running state of the vehicle at a
comparatively high speed. Accordingly, the fuel economy of the
vehicle as a whole can be maximized.
[0700] The present embodiment is further arranged such that the
speed-ratio control means 386 controls the speed ratio .gamma. of
the step-variable shifting portion 20 and the speed ratio .gamma.0
of the differential portion (continuously-variable shifting
portion) 11, on the basis of the efficiency values .eta.M1 and
.eta.M2 of the respective first and second electric motors M1, M2
of the differential portion (continuously-variable shifting
portion) 11. Thus, the speed ratio .gamma. of the step-variable
shifting portion 20 and the speed ratio .gamma.0 of the
differential portion (continuously-variable shifting portion) 11
are controlled by taking account of the efficiency values .eta.M1
and .eta.M2 of the respective first and second electric motors M1,
M2. Accordingly, the power transmitting efficiency is further
improved.
[0701] The present embodiment is also arranged such that the
speed-ratio control means 386 changes the output shaft speed
N.sub.IN of the differential portion (continuously-variable
shifting portion) 11, by adjusting the speed ratio .gamma. of the
step-variable shifting portion 20. Thus, the speed ratio .gamma. of
the step-variable shifting portion 20 can be controlled so as to
prevent reverse rotation of the first electric motor M1 in the
differential portion (continuously-variable shifting portion) 11 as
indicated in FIG. 4, even in a steady-state running state of the
vehicle at a comparatively high speed. Accordingly, the fuel
economy of the vehicle as a whole can be maximized.
Embodiment 24
[0702] FIG. 77 is a schematic view explaining a drive system 410
for a hybrid vehicle, according to another embodiment of this
invention. The drive system 410 shown in FIG. 1 includes: an input
rotary member in the form of an input shaft 14 disposed on a common
axis in a transmission casing 12 (hereinafter abbreviated as
"casing 12") functioning as a stationary member attached to a body
of the vehicle; a differential mechanism in the form of a power
distributing mechanism 16 connected to the input shaft 14 either
directly, or indirectly via a pulsation absorbing damper (vibration
damping device) not shown; a step-variable or multiple-step
automatic transmission 20 interposed between and connected in
series via a power transmitting member 18 (power transmitting
shaft) to the power distributing mechanism 16 and an output shaft
22; and an output rotary member in the form of the above-indicated
output shaft 22 connected to the automatic transmission 20. The
input shaft 12, power distributing mechanism 16, automatic
transmission 20 and output shaft 22 are connected in series with
each other. This drive system 410 is suitably used for a transverse
FR vehicle (front-engine, rear-drive vehicle), and is disposed
between a drive power source in the form of an engine 8 and a pair
of drive wheels 38, to transmit a vehicle drive force to the pair
of drive wheels 38 through a differential gear device 36 (final
speed reduction gear) and a pair of drive axles, as shown in FIG.
7. It is noted that a lower half of the drive system 10, which is
constructed symmetrically with respect to its axis, is omitted in
FIG. 77. This is also true in each of the other embodiments
described below.
[0703] The power distributing mechanism 16 is a mechanical device
arranged to mechanically synthesize or distribute the output of the
engine 8 received by the input shaft 14, that is, to distribute the
output of the engine 8 to the first electric motor M1, and to the
power transmitting member 18 provided to transmit a drive force to
the automatic transmission 20, or to synthesize the output of the
engine 8 and the output of the first electric motor M1 and transmit
a sum of these outputs to the power transmitting member 18. While
the second electric motor M2 is arranged to be rotated with the
power transmitting member 18 in the present embodiment, the second
electric motor M2 may be disposed at any desired position between
the power transmitting member 18 and the output shaft 22. In the
present embodiment, each of the first electric motor M1 and the
second electric motor M2 is a so-called motor/generator also
functioning as an electric generator. The first electric motor M1
should function at least as an electric generator operable to
generate an electric energy while generating a reaction force, and
the second electric motor M2 should function at least as an
electric motor operable to generate a vehicle drive force.
[0704] The power distributing mechanism 16 includes, as major
components, a first planetary gear set 24 of single pinion type
having a gear ratio .rho.1 of about 0.300, for example, a switching
clutch C0 and a switching brake B1. The first planetary gear set 24
has rotary elements consisting of a first sun gear S1, a first
planetary gear P1; a first carrier CA1 supporting the first
planetary gear P1 such that the first planetary gear P1 is
rotatable about its axis and about the axis of the first sun gear
S1; and a first ring gear R1 meshing with the first sun gear S1
through the first planetary gear P1. Where the numbers of teeth of
the first sun gear S1 and the first ring gear R1 are represented by
ZS1 and ZR1, respectively, the above-indicated gear ratio .rho.1 is
represented by ZS1/ZR1.
[0705] In the power distributing mechanism 16, the first carrier
CA1 is connected to the input shaft 14, that is, to the engine 8,
and the first sun gear S1 is connected to the first electric motor
M1, while the first ring gear R1 is connected to the power
transmitting member 18. The switching brake B0 is disposed between
the first sun gear S1 and the casing 12, and the switching clutch
C0 is disposed between the first sun gear S1 and the first carrier
CA1. When the switching clutch C0 and brake B0 are released, the
power distributing mechanism 16 is placed in a differential state
in which the first sun gear S1, first carrier CA1 and first ring
gear R1 are rotatable relative to each other, so as to perform a
differential function, so that the output of the engine 8 is
distributed to the first electric motor M1 and the power
transmitting member 18, whereby a portion of the output of the
engine 8 is used to drive the first electric motor M1 to generate
an electric energy which is stored or used to drive the second
electric motor M2. Accordingly, the power distributing mechanism 16
is placed in the continuously-variable shifting state, in which the
rotating speed of the power transmitting member 18 is continuously
variable, irrespective of the rotating speed of the engine 8,
namely, in the differential state in which a speed ratio .gamma.0
(rotating speed of the input shaft 14/rotating speed of the power
transmitting member 18) of the power distributing mechanism 16 is
electrically changed from a minimum value .gamma.0min to a maximum
value .gamma.0max, for instance, in the continuously-variable
shifting state in which the power distributing mechanism 16
functions as an electrically controlled continuously variable
transmission the speed ratio .gamma.0 of which is continuously
variable from the minimum value .gamma.0min to the maximum value
.gamma.0max.
[0706] When the switching clutch C0 is engaged during running of
the vehicle with the output of the engine 8 while the power
distributing mechanism 16 is placed in the continuously-variable
shifting state, the first sun gear S1 and the first carrier CA1 are
connected together, so that the power distributing mechanism 16 is
placed in the locked state or non-differential state in which the
three rotary elements S1, CA1, R1 of the first planetary gear set
24 are rotatable as a unit. In other words, the power distributing
mechanism 16 is placed in a fixed-speed-ratio shifting state in
which the mechanism 16 functions as a transmission having a fixed
speed ratio .gamma.0 equal to 1. When the switching brake B0 is
engaged in place of the switching clutch C0, to place the power
distributing mechanism in the locked or non-differential state in
which the first sun gear S1 is held stationary, the rotating speed
of the first ring gear R1 is made higher than that of the first
carrier CA1, so that the power distributing mechanism 16 is placed
in the fixed-speed-ration shifting state in which the mechanism 16
functions as a speed-increasing transmission having a fixed speed
ratio .gamma.0 smaller than 1, for example, about 0.77. In the
present embodiment described above, the switching clutch C0 and
brake B0 function as a differential-state switching device operable
to selectively place the power distributing mechanism 16 in the
differential state (continuously-variable shifting state) in which
the mechanism 16 functions as an electrically controlled
continuously variable transmission the speed ratio of which is
continuously variable, and in the non-differential or locked state
in which the mechanism 16 does not function as the electrically
controlled continuously variable transmission, namely, in the
fixed-speed-ration shifting state in which the mechanism 16
functions as a transmission having a single gear position with one
speed ratio or a plurality of gear positions with respective speed
ratios.
[0707] The automatic transmission 420 includes a single-pinion type
second planetary gear set 426, and a double-pinion type third
planetary gear set 428. The third planetary gear set 428 has: a
third sun gear S3; a plurality of pairs of mutually meshing third
planetary gears P3; a third carrier CA3 supporting the third
planetary gears P3 such that each third planetary gear P3 is
rotatable about its axis and about the axis of the third sun gear
S3; and a third ring gear R3 meshing with the third sun gear S3
through the third planetary gears P3. For example, the third
planetary gear set 428 has a gear ratio .rho.3 of about 0.315. The
second planetary gear set 426 has: a second sun gear S2, a second
planetary gear P2 formed integrally with one of the third planetary
gears P3; a second carrier CA2 formed integrally with the third
carrier CA3; and a second ring gear R2 which is formed integrally
with the third ring gear R3 and which meshes with the second sun
gear S2 through the second planetary gear P2. For example, the
second planetary gear set 426 has a gear ratio .rho.2 of about
0.368. The second planetary gear set 426 and the third planetary
gear set 428 is of a so-called Ravigneaux type wherein the second
and third carriers are formed integrally with each other and the
second and third ring gears are formed integrally with each other.
The second planetary gear P2 formed integrally with one of the
third planetary gears P3 may have different diameters or numbers of
teeth on the respective sides corresponding to the second and third
planetary gears P2, P3. The third planetary gears P3 and the second
planetary gear P2 may be formed separately from each other, and the
third carrier CA3 and the second carrier CA2 may be formed
separately from each other. The third ring gear R3 and the second
ring gear R2 may be formed separately from each other. Where the
numbers of teeth of the second sun gear S2, second ring gear R2,
third sun gear S3, third ring gear R3, are represented by ZS2, ZR2,
ZS3 and ZR3, respectively, the above-indicated gear ratios .rho.2
and .rho.3 are represented by ZS2/ZR2 and ZS3/ZR3,
respectively.
[0708] In the automatic transmission 420, the second sun gear S2 is
selectively connected to the power transmitting member 18 through a
second clutch C2, and selectively fixed to the casing 12 through a
first brake B1. The second carrier CA2 and the third carrier CA3
are selectively connected to the power transmitting member 18
through a third clutch C3, ad selectively fixed to the casing 12
through a second brake B2. The second ring gear R2 and the third
ring gear R3 are fixed to the output shaft 22, and the third sun
gear S3 is selectively connected to the power transmitting member
18 through a first clutch C1.
[0709] The above-described switching clutch C0, first clutch C1,
second clutch C2, third clutch C3, switching brake B0, first brake
B1 and second brake B2 are hydraulically operated frictional
coupling devices used in a conventional vehicular automatic
transmission. Each of these frictional coupling devices is
constituted by a wet-type multiple-disc clutch including a
plurality of friction plates which are superposed on each other and
which are forced against each other by a hydraulic actuator, or a
band brake including a rotary drum and one band or two bands which
is/are wound on the outer circumferential surface of the rotary
drum and tightened at one end by a hydraulic actuator. Each of the
clutches C0-C2 and brakes B0-B3 is selectively engaged for
connecting two members between which each clutch or brake is
interposed.
[0710] In the drive system 410 constructed as described above, one
of a first-gear position (first-speed position) through a
fifth-gear position (fifth-speed position), a reverse-gear position
(rear-drive position) and a neural position is selectively
established by engaging actions of a corresponding combination of
the frictional coupling devices selected from the above-described
switching clutch C0, first clutch C1, second clutch C2, third
clutch C3, switching brake B0, first brake B1 and second brake B2,
as indicated in the table of FIG. 78. In particular, it is noted
that the power distributing mechanism 16 provided with the
switching clutch C0 and brake B0 can be selectively placed by
engagement of the switching clutch C0 or switching brake B0, in the
fixed-speed-ratio shifting state in which the mechanism 16 is
operable as a transmission having a single gear position with one
speed ratio or a plurality of gear positions with respective speed
ratios, as well as in the continuously-variable shifting state in
which the mechanism 16 is operable as a continuously variable
transmission, as described above. In the present drive system 410,
therefore, a step-variable transmission is constituted by the
automatic transmission 420, and the power distributing mechanism 16
which is placed in the fixed-speed-ratio shifting state by
engagement of the switching clutch C0 or switching brake B0.
Further, a continuously variable transmission is constituted by the
automatic transmission 420, and the power distributing mechanism 16
which is placed in the continuously-variable shifting state, with
none of the switching clutch C0 and brake B0 being engaged.
[0711] Where the drive system 410 functions as the step-variable
transmission, for example, the first-gear position having the
highest speed ratio .gamma.1 of about 3.174, for example, is
established by engaging actions of the switching clutch C0, first
clutch C1 and second brake B2, and the second-gear position having
the speed ratio .gamma.2 of about 1.585, for example, which is
lower than the speed ratio .gamma.1, is established by engaging
actions of the switching clutch C0, first clutch C1 and first brake
B1, as indicated in FIG. 78. The speed ratio is equal to the input
shaft speed N.sub.IN/output shaft speed N.sub.OUT. Further, the
third-gear position having the speed ratio .gamma.3 of about 1.000,
for example, which is lower than the speed ratio .gamma.2, is
established by engaging actions of the switching clutch C0, first
clutch C1 and third clutch C1, and the fourth-gear position having
the speed ratio .gamma.4 of about 0.731, for example, which is
lower than the speed ratio .gamma.3, is established by engaging
actions of the switching clutch C0, third clutch C3 and first brake
B1. The fifth-gear position having the speed ratio .gamma.5 of
about 0.562, for example, which is smaller than the speed ratio
.gamma.4, is established by engaging actions of the third clutch
C3, switching brake B0 and first brake B1. Further, the
reverse-gear position having the speed ratio .gamma.R of about
2.717, for example, which is intermediate between the speed ratios
.gamma.1 and .gamma.2, is established by engaging actions of the
second clutch C2 and the second brake B2. The neutral position N is
established by engaging only the second brake B2.
[0712] Where the drive system 410 functions as the
continuously-variable transmission, on the other hand, the
switching clutch C0 and the switching brake B0 are both released,
as indicated in FIG. 78, so that the power distributing mechanism
16 functions as the continuously variable transmission, while the
automatic transmission 420 connected in series to the power
distributing mechanism 16 functions as the step-variable
transmission, whereby the speed of the rotary motion transmitted to
the automatic transmission 420 placed in one of the first-gear,
second-gear, third-gear and fourth-gear positions, namely, the
rotating speed of the power transmitting member 18 is continuously
changed, so that the speed ratio of the drive system when the
automatic transmission 420 is placed in one of those gear positions
is continuously variable over a predetermined range. Accordingly,
the speed ratio of the automatic transmission 420 is continuously
variable across the adjacent gear positions, whereby the overall
speed ratio .gamma.T of the drive system 410 is continuously
variable.
[0713] The collinear chart of FIG. 79 indicates, by straight lines,
a relationship among the rotating speeds of the rotary elements in
each of the gear positions of the drive system 410, which is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 420 functioning as the
step-variable shifting portion or second shifting portion. The
collinear chart of FIG. 79 is a rectangular two-dimensional
coordinate system in which the gear ratios .rho. of the planetary
gear sets 424, 426, 428 are taken along the horizontal axis, while
the relative rotating speeds of the rotary elements are taken along
the vertical axis. A lower one of three horizontal lines X1, X2,
XG, that is, the horizontal line X1 indicates the rotating speed of
0, while an upper one of the three horizontal lines, that is, the
horizontal line X2 indicates the rotating speed of 1.0, that is, an
operating speed N.sub.E of the engine 8 connected to the input
shaft 14. The horizontal line XG indicates the rotating speed of
the power transmitting member 18. Three vertical lines Y1, Y2 and
Y3 corresponding to the power distributing mechanism 16
respectively represent the relative rotating speeds of a second
rotary element (second element) RE2 in the form of the first sun
gear S1, a first rotary element (first element) RE1 in the form of
the first carrier CA1, and a third rotary element (third element)
RE3 in the form of the first ring gear R1. The distances between
the adjacent ones of the vertical lines Y1, Y2 and Y3 are
determined by the gear ratio .rho.1 of the first planetary gear set
424. That is, the distance between the vertical lines Y1 and Y2
corresponds to "1", while the distance between the vertical lines
Y2 and Y3 corresponds to the gear ratio .rho.1. Further, five
vertical lines Y4, Y5, Y6 and Y7 corresponding to the automatic
transmission 20 respectively represent the relative rotating speeds
of a fourth rotary element (fourth element) RE4 in the form of the
second and third sun gears S2, S3, a fifth rotary element (fifth
element) RE5 in the form of the second carrier CA2 and the third
carrier CA3 that are integrally fixed to each other, a sixth rotary
element (sixth element) RE6 in the form of the second ring gear R2
and the third ring gear R3 that are integrally fixed to each other,
and a seventh rotary element (seventh element) RE7 in the form of
the third sun gear S3. The distances between the adjacent ones of
the vertical lines Y4-Y7 are determined by the gear ratios .rho.2
and .rho.3 of the second and third planetary gear sets 426,
428.
[0714] Referring to the collinear chart of FIG. 79, the power
distributing mechanism (continuously variable shifting portion) 16
of the drive system 410 is arranged such that the first rotary
element RE1 (first carrier CA1), which is one of the three rotary
elements of the first planetary gear set 424, is integrally fixed
to the input shaft 14 and selectively connected to the second
rotary element RE2 in the form of the first sun gear S1 through the
switching clutch C0, and this second rotary element RE2 (first sun
gear S1) is fixed to the first electric motor M1 and selectively
fixed to the casing 12 through the switching brake B0, while the
third rotary element RE3 (first ring gear R1) is fixed to the power
transmitting member 18 and the second electric motor M2, so that a
rotary motion of the input shaft 14 is transmitted to the automatic
transmission (step-variable transmission) 420 through the power
transmitting member 18. A relationship between the rotating speeds
of the first sun gear S1 and the first ring gear R1 is represented
by an inclined straight line L0 which passes a point of
intersection between the lines Y2 and X2.
[0715] FIGS. 4 and 5 correspond to a part of the collinear chart of
FIG. 79 which shows the power distributing mechanism 16. FIG. 4
shows an example of an operating state of the power distributing
mechanism 16 placed in the continuously-variable shifting state
with the switching clutch C0 and the switching brake B0 held in the
released state. The rotating speed of the first sun gear S1
represented by the point of intersection between the straight line
L0 and vertical line Y1 is raised or lowered by controlling the
reaction force generated by an operation of the first electric
motor M1 to generate an electric energy, so that the rotating speed
of the first ring gear R1 represented by the point of intersection
between the lines L0 and Y3 is lowered or raised. In the operating
state of FIG. 4, the first sun gear S1 is rotated in the negative
direction, with the first electric motor M1 being operated by
application of an electric energy thereto. While the first sun gear
S1 is rotated in the negative direction as indicated in FIG. 4, the
angle of inclination of the straight line L0 is relatively large,
indicating an accordingly high speed of rotation of the first ring
gear R1 and the power transmitting member 18, making it possible to
drive the vehicle at a relatively high speed. On the other hand,
the application of the electric energy to the first electric motor
M1 results in deterioration of the fuel economy. In the drive
system 10 according to the present embodiment, however, the
automatic transmission 420 is arranged to increase the speed of a
rotary motion transmitted through the power transmitting member 18,
as described below, so that there is not a high degree of
opportunity wherein the first sun gear S1 must be rotated in the
negative direction. Accordingly, the fuel economy is higher in the
present drive system than in the case where the automatic
transmission 420 were not able to increase the speed of the rotary
motion transmitted through the power transmitting member 18.
[0716] FIG. 5 shows an example of an operating state of the power
distributing mechanism 16 placed in the step-variable shifting
state with the switching clutch C0 held in the engaged state. When
the first sun gear S1 and the first carrier CA1 are connected to
each other in this step-variable shifting state, the three rotary
elements indicated above are rotated as a unit, so that the line L0
is aligned with the horizontal line X2, whereby the power
transmitting member 18 is rotated at a speed equal to the engine
speed N.sub.E. When the switching brake B0 is engaged, on the other
hand, the rotation of the power transmitting member 18 is stopped,
so that the straight line L0 is inclined in the state indicated in
FIG. 79, whereby the rotating speed of the first ring gear R1, that
is, the rotation of the power transmitting member 18 represented by
a point of intersection between the straight line L0 and vertical
line Y3 is made higher than the engine speed N.sub.E and
transmitted to the automatic transmission 420.
[0717] In the automatic transmission 420, the fourth rotary element
RE4 is selectively connected to the power transmitting member 18
through the second clutch C2, and selectively fixed to the
transmission casing 12 through the first brake B1, and the fifth
rotary element RE5 is selectively connected to the power
transmitting member 18 through the third clutch C3 and selectively
fixed to the casing 12 through the second brake B2. The sixth
rotary element RE6 is fixed to the output shaft 22, while the
seventh rotary element RE7 is selectively connected to the power
transmitting member 18 through the first clutch C1.
[0718] When the first clutch C1 and the second brake B2 are
engaged, the automatic transmission 420 is placed in the
first-speed position. The rotating speed of the output shaft 22 in
the first-speed position is represented by a point of intersection
between the vertical line Y6 indicative of the rotating speed of
the sixth rotary element RE6 fixed to the output shaft 22 and an
inclined straight line L1 which passes a point of intersection
between the vertical line Y7 indicative of the rotating speed of
the seventh rotary element RE7 and the horizontal line X1, and a
point of intersection between the vertical line Y5 indicative of
the rotating speed of the fifth rotary element RE5 and the
horizontal line X1. Similarly, the rotating speed of the output
shaft 22 in the second-speed position established by the engaging
actions of the first clutch C1 and first brake B1 is represented by
a point of intersection between an inclined straight line L2
determined by those engaging actions and the vertical line Y6
indicative of the rotating speed of the sixth rotary element RE6
fixed to the output shaft 22. The rotating speed of the output
shaft 22 in the third-speed position established by the engaging
actions of the first clutch C1 and third clutch C3 is represented
by a point of intersection between an inclined straight line L3
determined by those engaging actions and the vertical line Y6
indicative of the rotating speed of the sixth rotary element RE6
fixed to the output shaft 22. The rotating speed of the output
shaft 22 in the fourth-speed position established by the engaging
actions of the first brake B1 and third clutch C3 is represented by
a point of intersection between a horizontal line L4 determined by
those engaging actions and the vertical line Y6 indicative of the
rotating speed of the sixth rotary element RE6 fixed to the output
shaft 22. In the first-speed through fourth-speed positions in
which the switching clutch C0 is placed in the engaged state, the
fifth rotary element RE5 is rotated at the same speed as the engine
speed N.sub.E, with the drive force received from the power
distributing mechanism 16. When the switching clutch B0 is engaged
in place of the switching clutch C0, the sixth rotary element RE6
is rotated at a speed higher than the engine speed N.sub.E, with
the drive force received from the power distributing mechanism 16.
The rotating speed of the output shaft 22 in the fifth-speed
position established by the engaging actions of the first brake B1,
third clutch C3 and switching brake B0 is represented by a point of
intersection between a horizontal line L5 determined by those
engaging actions and the vertical line Y6 indicative of the
rotating speed of the sixth rotary element RE6 fixed to the output
shaft 22. The rotating speed of the output shaft 22 in the
reverse-gear position R established by the second clutch C2 and
second brake B2 is represented by a point of intersection between
an inclined straight line LR determined by those engaging actions
and the vertical line Y6 indicative of the rotating speed of the
sixth rotary element RE6 fixed to the output shaft 22.
[0719] In the drive system 410 constructed as described above, the
electronic control unit 40 shown in FIG. 66 having the control
functions shown in FIG. 7 or FIG. 11 and FIG. 13 by way of example
performs the hybrid controls of the engine 8 and the first and
second electric motors M1, M2, the shifting control of the
automatic transmission 20, and other vehicle drive controls.
[0720] In the present embodiment described above, the power
distributing mechanism 16 is selectively switched by the engaging
and releasing actions of the switching clutch C0 and the switching
brake B0, between the continuously-variable shifting state in which
the mechanism 16 is operable as an electrically controlled
continuously variable transmission, and the fixed-speed-ratio
shifting state in which the mechanism 16 is operable as a
transmission having fixed speed ratios. Accordingly, when the
engine is in a normal output state with a relatively low or medium
output while the vehicle is running at a relatively low or medium
running speed, the power distributing mechanism 16 is placed in the
continuously-variable shifting state, assuring a high degree of
fuel economy of the hybrid vehicle. When the vehicle is running at
a relatively high speed or when the engine is operating at a
relatively high speed, on the other hand, the power distributing
mechanism 16 is placed in the fixed-ratio shifting state in which
the output of the engine 8 is transmitted to the drive wheels 38
primarily through the mechanical power transmitting path, so that
the fuel economy is improved owing to reduction of a loss of
conversion of the mechanical energy into the electric energy. When
the engine 8 is in a high-output state, the power distributing
mechanism 16 is also placed in the fixed-speed-ratio shifting
state. Therefore, the mechanism 16 is placed in the
continuously-variable shifting state only when the vehicle speed is
relatively low or medium or when the engine output is relatively
low or medium, so that the maximum amount of electric energy
generated by the first electric motor M1, that is, the maximum
amount of electric energy that must be transmitted from the first
electric motor M1 can be reduced, whereby the required electrical
reaction force of the first electric motor M1 can be reduced,
making it possible to minimize the required sizes of the first
electric motor M1 and the second electric motor M2, and the
required size of the drive system including those electric motors.
Alternatively, when the engine 8 is in a high-output
(high-torque)state, the power distributing mechanism 16 is placed
in the fixed-speed-ratio shifting state while at the same time the
automatic transmission 20 is automatically shifted, so that the
engine speed N.sub.E changes with a shift-up action of the
automatic transmission 20, assuring a comfortable rhythmic change
of the engine speed N.sub.E as the automatic transmission is
shifted up, as indicated in FIG. 10. Stated in the other way, when
the engine is in a high-output state, it is more important to
satisfy a vehicle operator's desire to improve the drivability of
the vehicle, than a vehicle operator's desire to improve the fuel
economy. In this respect, the power distributing mechanism 16 is
switched from the continuously-variable shifting state to the
step-variable shifting state (fixed-speed-ratio shifting state)
when the engine output becomes relatively high. Accordingly, the
vehicle operator is satisfied with a comfortable rhythmic change of
the engine speed N.sub.E during the high-output operation of the
engine, as indicated in FIG. 10. Further, the automatic
transmission 20 principally constituted by the two planetary gear
sets 26, 28 has a comparatively small dimension in its axial
direction, making it possible to further reduce the required axial
dimension of the drive system 10 including those planetary gear
sets.
Embodiment 25
[0721] FIG. 80 is a schematic view for explaining an arrangement of
a drive system 480 according to another embodiment of this
invention. The present embodiment is different from the embodiment
shown in FIGS. 77-79, primarily in that the power distributing
mechanism 16 and an automatic transmission 420 are not disposed
coaxially with each other in the present embodiment. The following
description of the present embodiment primarily relates to a
difference between the drive system 480 and the drive system
410.
[0722] The drive system 480 shown in FIG. 80 is provided, within a
casing 12 attached to the vehicle body, with: an input shaft 14
disposed rotatably about a first axis 14c; the power distributing
mechanism 16 mounted on the input shaft 14 directly, or indirectly
through a pulsation absorbing damper (vibration damping device);
the automatic transmission 420 disposed rotatably about a second
axis 32c parallel to the first axis 14c; an output rotary member in
the form of a differential drive gear 32 connected to the automatic
transmission 420; and a power transmitting member in the form of a
counter gear pair CG which connects the power distributing
mechanism 16 and the automatic transmission 420, so as to transmit
a drive force therebetween. This drive system 480 is suitably used
on a transverse FF (front-engine, front-drive) vehicle or a
transverse RR (rear-engine, rear-drive) vehicle, and is disposed
between a drive power source in the form of an engine 8 and a pair
of drive wheels 38. The drive force is transmitted from the
differential drive gear 32 to the pair of drive wheels 38, through
a differential gear 34 meshing with the differential drive gear 32,
a differential gear device 36, a pair of drive axles 37, etc.
[0723] The counter gear pair CG indicated above consists of a
counter drive gear CG1 disposed rotatably on the first axis 14c and
coaxially with the power distributing mechanism 16 and fixed to a
first ring gear R1, and a counter driven gear CG2 disposed
rotatably on the second axis 32c and coaxially with the automatic
transmission 20 and connected to the automatic transmission 20
through a first clutch C1 and a second clutch C2. The counter drive
gear CG1 and the counter driven gear CG2 serve as a pair of members
in the form of a pair of gears which are held in meshing engagement
with each other. Since the speed reduction ratio of the counter
gear pair CG (rotating speed of the counter drive gear CG1/rotating
speed of the counter driven gear CG2) is about 1.000, the counter
gear pair CG functionally corresponds to the power transmitting
member 18 in the embodiment shown in FIGS. 77-79, which connects
the power distributing mechanism 16 and the automatic transmission
420. That is, the counter drive gear CG1 corresponds to a power
transmitting member which constitutes a part of the power
transmitting member 18 on the side of the first axis 14c, while the
counter driven gear CG2 corresponds to a power transmitting member
which constitutes another part of the power transmitting member 18
on the side of the second axis 32c.
[0724] Referring to FIG. 80, the individual elements of the drive
system 480 will be described. The counter gear pair CG is disposed
adjacent to one end of the power distributing mechanism 16 which
remote from the engine 8. In other words, the power distributing
mechanism 16 is interposed between the engine 8 and the counter
gear pair CG, and located adjacent to the counter gear pair CG. A
second electric motor M2 is disposed on the first axis 14c, between
a first planetary gear set 24 and the counter gear pair CG, such
that the second electric motor M2 is fixed to the counter drive
gear CG1. The differential drive gear 32 is disposed adjacent to
one end of the automatic transmission 420 which is remote from the
counter gear pair CG, that is, on the side of the engine 8. In
other words, the automatic transmission 20 is interposed between
the counter gear pair CG and the differential drive gear 32 (engine
8), and located adjacent to the counter gear pair CG. Between the
counter gear pair CG and the differential drive gear 32, a second
planetary gear set 426 and a third planetary gear set 428 are
disposed in the order of description, in the direction from the
counter gear pair CG toward the differential drive gear 32. The
first clutch C1 and the second clutch C2 are disposed between the
counter gear pair CG and the second planetary gear set 426, and the
third clutch C3 is disposed between the third planetary gear set
428 and the differential drive gear 32.
[0725] The present embodiment is different from the embodiment
shown in FIGS. 77-79, only in that the counter gear pair CG
replaces the power transmitting member 18 connecting the power
distributing mechanism 16 and the automatic transmission 420, and
is identical with the embodiment of FIGS. 77-79 in the arrangements
of the power distributing mechanism 16 and automatic transmission
420. Accordingly, the table of FIG. 78 and the collinear chart of
FIG. 79 apply to the present embodiment.
[0726] In the present embodiment, too, the drive system 480 is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 420 functioning as the
step-variable shifting portion or second shifting portion, so that
the drive system 480 has advantages similar to those of the
preceding embodiments. Unlike the embodiment shown in FIGS. 77-79,
the present embodiment is arranged such that the power distributing
mechanism 16 and the automatic transmission 420 are not disposed
coaxially with each other, so that the required dimension of the
drive system 480 in the axial direction can be reduced.
Accordingly, the present drive system can be suitably used on a
transversal FF or RR vehicle such that the first and second axes
14c, 32c are parallel to the transverse or width direction of the
vehicle. In this respect, it is noted that the maximum axial
dimension of a drive system for such a transverse FF or RR vehicle
is generally limited by the width dimension of the vehicle. The
present embodiment has an additional advantage that the required
axial dimension of the drive system 480 can be further reduced,
since the power distributing mechanism 16 and the automatic
transmission 420 are located between the engine 8 (differential
drive gear 32) and the counter gear pair CG. Further, the required
axial dimension of the second axis 32c can be reduced owing to the
arrangement in which the second electric motor M2 is disposed on
the first axis 13c.
Embodiment 26
[0727] FIG. 81 is a schematic view for explaining a drive system
490 according to another embodiment of this invention, which
includes the power distributing mechanism 16, the first electric
motor M1 and the second electric motor M2, as in the embodiment of
FIG. 77. The first and second electric motors M1, M2 are connected
to the power distributing mechanism 16 in the same manner as in the
embodiment of FIG. 77. In the present embodiment, too, the
step-variable automatic transmission 492 is disposed between and
coaxially with the output shaft 22 and the input shaft 14.
[0728] The automatic transmission 492 described above includes a
double-pinion type second planetary gear set 494 and a
single-pinion type third planetary gear set 496. The second
planetary gear set 494 includes: a second sun gear S2; a plurality
of pairs of mutually meshing second planetary gears P2; a second
carrier CA2 supporting the second planetary gears P2 such that each
second planetary gear PA2 is rotatable about its axis and about the
axis of the second sun gear S2; and a second ring gear R2 meshing
with the second sun gear S2 through the second planetary gears P2.
For example, the second planetary gear set 494 has a gear ratio
.rho.2 of about 0.461. The third planetary gear set 496 has: a
third sun gear S3, a third planetary gear P3; a third carrier CA3
supporting the third planetary gear P3 such that the third
planetary gear P3 is rotatable about its axis and about the axis of
the third sun gear S3; and a third ring gear R3 meshing with the
third sun gear S3 through the third planetary gear P3. For example,
the third planetary gear set 496 has a gear ratio .rho.3 of about
0.368.
[0729] Like the automatic transmission 420 of FIG. 77, the
automatic transmission 492 includes the first and second brakes B1,
B2 and the first through third clutches C1-C3. The second sun gear
S2 is selectively connected to the power transmitting member 18
through the first clutch C1. The second ring gear R2 and the third
carrier CA3 are integrally fixed to each other and selectively
connected to the power transmitting member 18 through the third
clutch C3, and selectively fixed to the casing 12 through the
second brake B2. The third ring gear R3 is fixed to the output
shaft 22.
[0730] The above-described second carrier CA2 and third sun gear S3
integrally fixed to each other function as the fourth rotary
element RE4, and the second ring gear R2 and the third carrier CA3
integrally fixed to each other function as the fifth rotary element
RE5. Further, the third ring gear R3 functions as the sixth rotary
element RE6, and the second sun gear S2 functions as the seventh
rotary element RE7. The collinear chart of the embodiment of FIG.
77 applies to the drive system 490.
[0731] The present drive system 490 also includes the power
distributing mechanism 16 functioning as a continuously-variable
shifting portion or a first shifting portion, and the automatic
transmission 492 functioning as a step-variable shifting portion or
a second shifting portion. The automatic transmission 492 is
principally constituted by the two planetary gear sets 494, 496,
and has the same advantage as that in the embodiment of FIG.
77.
Embodiment 27
[0732] FIG. 82 is a schematic view for explaining an arrangement of
a drive system 500 according to another embodiment of this
invention, which is different from the embodiment of FIG. 80 in
that the automatic transmission 492 of FIG. 81 is used in place of
the automatic transmission 420 in the present embodiment. In other
words, the present embodiment is different from the embodiment of
FIG. 81, like the embodiment of FIG. 80 is different from the
embodiment of FIG. 77, only in that the counter gear pair CG is
used in place of the power transmitting member 18, for connection
between the power distributing mechanism 16 and the automatic
transmission 492. Therefore, the drive system 500 of the present
embodiment has the same advantage as the embodiment of FIG. 80.
Embodiment 28
[0733] FIG. 83 is a schematic view for explaining a drive system
510 according to another embodiment of this invention, which
includes the power distributing mechanism 16, the first electric
motor M1, the second electric motor M2 and the counter gear pair
CG, as in the embodiment of FIG. 82. The present embodiment is
different from the embodiment of FIG. 80 or 82, only in the
construction of a step-variable automatic transmission 512 disposed
on the second axis 32c.
[0734] The automatic transmission 512 described above includes a
double-pinion type second planetary gear set 514 and a
single-pinion type third planetary gear set 516. The second
planetary gear set 514 includes: a second sun gear S2; a plurality
of pairs of mutually meshing second planetary gears P2; a second
carrier CA2 supporting the second planetary gears P2 such that each
second planetary gear P2 is rotatable about its axis and about the
axis of the second sun gear S2; and a second ring gear R2 meshing
with the second sun gear S2 through the second planetary gears P2.
For example, the second planetary gear set 514 has a gear ratio
.rho.2 of about 0.539. The third planetary gear set 516 has: a
third sun gear S3, a third planetary gear P3; a third carrier CA3
supporting the third planetary gear P3 such that the third
planetary gear P3 is rotatable about its axis and about the axis of
the third sun gear S3; and a third ring gear R3 meshing with the
third sun gear S3 through the third planetary gear P3. For example,
the third planetary gear set 516 has a gear ratio .rho.3 of about
0.585.
[0735] Like the automatic transmission 420 of FIG. 80 and the
automatic transmission 492 of FIG. 82, the automatic transmission
512 includes the first and second brakes B1, B2 and the first
through third clutches C1-C3. However, the first brake B1 in the
present embodiment is of a wet-type multiple-disc type. The second
sun gear S2 and the third sun gear S3 that are integrally fixed to
each other are selectively connected to a power transmitting member
in the form of the counter driven gear CG2 of the counter gear pair
CG through the second clutch C2, and selectively fixed to the
casing 12 through the first brake B1. The second carrier CA2 and
the third ring gear R3 are integrally fixed to each other and
selectively connected to the counter driven gear CG2 through the
first clutch C1. The second ring gear R2 is selectively connected
to the counter driven gear CG2 through the third clutch C3, and
selectively fixed to the casing 12 through the second brake B2. The
third carrier CA3 is fixed to an output rotary member in the form
of the differential drive gear 32.
[0736] The components of the automatic transmission 512 of the
drive system 510 will be described. The first through third
clutches C1-C3 are disposed between the second planetary gear set
514 and the counter driven gear CG2, such that the third clutch C3
is located closer to the counter driven gear CG2 than the first and
second clutches C1, C2. The first brake B1 is disposed on one side
of the differential drive gear 32 which is remote from the third
planetary gear set 516. In other words, the differential drive gear
32 is disposed between the third planetary gear set 516 and the
first brake B1.
[0737] The above-described second sun gear S2 and third sun gear S3
integrally fixed to each other function as the fourth rotary
element RE4, and the second ring gear R2 functions as the fifth
rotary element RE5. The third carrier CA3 functions as the sixth
rotary element RE6, and the second carrier CA2 and third ring gear
R3 integrally fixed to each other function as the seventh rotary
element RE7. The collinear chart of the embodiments of FIGS. 77-82
applies to the drive system 510.
[0738] The present drive system 510 also includes the power
distributing mechanism 16 functioning as a continuously-variable
shifting portion or a first shifting portion, and the automatic
transmission 512 functioning as a step-variable shifting portion or
a second shifting portion. In this respect, the present embodiment
has the same advantage as the embodiment of FIG. 77. Further, the
power distributing mechanism 16 and the automatic transmission 512
are not disposed coaxially with each other, and are disposed
between the engine 8 and the counter gear pair CG, and the second
electric motor M2 is disposed on the first axis 14c, so that the
required dimension of the drive system in the axial direction can
be favorably reduced.
Embodiment 29
[0739] FIG. 84 is a schematic view for explaining an arrangement of
a drive system 520 according to another embodiment of this
invention. The present embodiment also includes the power
distributing mechanism 16, the first electric motor M1, the second
electric motor M2 and the counter gear pair CG, as in the
embodiment shown in FIG. 80. The present embodiment is different
from the embodiment of FIG. 80, only in the construction of a
step-variable automatic transmission 522 disposed on the second
axis 32c.
[0740] The automatic transmission 522 includes a double-pinion type
second planetary gear set 524 and a single-pinion type third
planetary gear set 526. The second planetary gear set 524 includes:
a second sun gear S2; a plurality of pairs of mutually meshing
second planetary gears P2; a second carrier CA2 supporting the
second planetary gears P2 such that each second planetary gear P2
is rotatable about its axis and about the axis of the second sun
gear S2; and a second ring gear R2 meshing with the second sun gear
S2 through the second planetary gears P2. For example, the second
planetary gear set 524 has a gear ratio .rho.2 of about 0.539. The
third planetary gear set 526 has: a third sun gear S3, a third
planetary gear P3; a third carrier CA3 supporting the third
planetary gear P3 such that the third planetary gear P3 is
rotatable about its axis and about the axis of the third sun gear
S3; and a third ring gear R3 meshing with the third sun gear S2
through the third planetary gear P3. For example, the third
planetary gear set 526 has a gear ratio .rho.3 of about 0.460.
[0741] Like the automatic transmission 512 of FIG. 83, the
automatic transmission 522 includes the first and second brakes B1,
B2 and the first through third clutches C1-C3. The second sun gear
S2 is selectively connected to a power transmitting member in the
form of the counter driven gear CG2 of the counter gear pair CG
through the second clutch C2, and selectively fixed to the casing
12 through the first brake B1. The second carrier CA2 and the third
sun gear S3 are integrally fixed to each other and selectively
connected to the counter driven gear CG2 through the first clutch
C1. The second ring gear R2 and the third ring gear R3 are
integrally fixed to each other and selectively connected to the
counter driven gear CG2 through the third clutch C3, and
selectively fixed to the casing 12 through the second brake B2. The
third carrier CA3 is fixed to an output rotary member in the form
of the differential drive gear 32.
[0742] The components of the automatic transmission 520 of the
drive system 520 will be described. The first through third
clutches C1-C3 are disposed between the second planetary gear set
524 and the counter driven gear CG2, such that the third clutch C3
is located closer to the counter driven gear CG2 than the first and
second clutches C1, C2. The first brake B1 is disposed on one side
of the counter driven gear CG2 which is remote from the third
clutch C3, and the second planetary gear set 524 and the third
planetary gear set 526 are disposed between the first and second
clutches C, C2 and the differential drive gear 32.
[0743] The above-described second sun gear S2 functions as the
fourth rotary element RE4, and the second ring gear R2 and third
ring gear R3 integrally fixed to each other function as the fifth
rotary element RE5. The third carrier CA3 functions as the sixth
rotary element RE6, and the second carrier CA2 and third sun gear
S3 integrally fixed to each other function as the seventh rotary
element RE7. The collinear chart of the embodiments of FIGS. 77-83
applies to the drive system 520.
[0744] The present drive system 520 also includes the power
distributing mechanism 16 functioning as a continuously-variable
shifting portion or a first shifting portion, and the automatic
transmission 522 functioning as a step-variable shifting portion or
a second shifting portion, and the automatic transmission 522 is
principally constituted by the two planetary gear sets 524, 526. In
this respect, the present embodiment has the same advantage as the
embodiment of FIG. 77. Further, the power distributing mechanism 16
and the automatic transmission 522 are not disposed coaxially with
each other, and the second electric motor M2 is disposed on the
first axis 14c, so that the required dimension of the drive system
in the axial direction can be favorably reduced.
Embodiment 30
[0745] FIG. 85 is a schematic view for explaining an arrangement of
a drive system 530 according to another embodiment of this
invention. The drive system 530 of the present embodiment also
includes the power distributing mechanism 16, the first electric
motor M1, the second electric motor M2 and the counter gear pair
CG, as in the embodiment shown in FIG. 80. The present embodiment
is different from the embodiment of FIG. 80, only in the
construction of a step-variable automatic transmission 532 disposed
on the second axis 32c.
[0746] The automatic transmission 532 includes a single-pinion type
second planetary gear set 534 and a double-pinion type third
planetary gear set 536. The second planetary gear set 534 includes:
a second sun gear S2; a second planetary gear P2; a second carrier
CA2 supporting the second planetary gear P2 such that the second
planetary gear P2 is rotatable about its axis and about the axis of
the second sun gear S2; and a second ring gear R2 meshing with the
second sun gear S2 through the second planetary gear P2. For
example, the second planetary gear set 534 has a gear ratio .rho.2
of about 0.460. The third planetary gear set 536 has: a third sun
gear S3, a plurality of pairs of mutually meshing third planetary
gears P3; a third carrier CA3 supporting the third planetary gears
P3 such that each third planetary gear P3 is rotatable about its
axis and about the axis of the third sun gear S3; and a third ring
gear R3 meshing with the third sun gear S2 through the third
planetary gears P3. For example, the third planetary gear set 536
has a gear ratio .rho.3 of about 0.369.
[0747] Like the automatic transmission 512 of FIG. 83 and the
automatic transmission 522 of FIG. 84, the automatic transmission
530 includes the first and second brakes B1, B2 and the first
through third clutches C1-C3. The second sun gear S2 and the third
carrier CA3 are integrally fixed to each other and selectively
connected to a power transmitting member in the form of the counter
driven gear CG2 of the counter gear pair CG through the first
clutch C1. The second carrier CA2 and the third ring gear R3 are
integrally fixed to each other and fixed to an output rotary member
in the form of the differential drive gear 32, and the second ring
gear R2 is selectively connected to the counter driven gear CG2
through the third clutch C3 and selectively fixed to the casing 12
through the second brake B2. The second sun gear S2 is selectively
connected to the counter driven gear CG2 through the second clutch
C2 and selectively fixed to the casing through the first brake
B1.
[0748] The components of the automatic transmission 532 of the
drive system 530 will be described. The first through third
clutches C1-C3 are disposed between the second planetary gear set
534 and the counter driven gear CG2, such that the third clutch C3
is located closer to the counter driven gear CG2 than the first and
second clutches C1, C2. The first brake B1 is disposed on one side
of the differential drive gear 32 which is remote from the third
planetary gear set 536. In other words, the differential drive gear
32 is disposed between the first brake B1 and the third planetary
gear set 536.
[0749] The above-described third sun gear S3 functions as the
fourth rotary element RE4, and the second ring gear R2 functions as
the fifth rotary element RE5. The second carrier CA2 and third ring
gear R3 integrally fixed to each other function as the sixth rotary
element RE6, and the second sun gear S3 and third carrier CA3
integrally fixed to each other function as the seventh rotary
element RE7. The collinear chart of the embodiments of FIGS. 77-84
applies to the drive system 530.
[0750] The present drive system 530 also includes the power
distributing mechanism 16 functioning as a continuously-variable
shifting portion or a first shifting portion, and the automatic
transmission 532 functioning as a step-variable shifting portion or
a second shifting portion, and the automatic transmission 532 is
principally constituted by the two planetary gear sets 534, 536. In
this respect, the present embodiment has the same advantage as the
embodiment of FIG. 77. Further, the power distributing mechanism 16
and the automatic transmission 532 are not disposed coaxially with
each other, and the power distributing mechanism 16 and the
automatic transmission 532 are disposed between the engine 8 and
the counter gear pair CG, and the second electric motor M2 is
disposed on the first axis 14c, so that the required dimension of
the drive system in the axial direction can be favorably reduced,
as in the embodiment of FIG. 80.
Embodiment of FIG. 31
[0751] FIG. 86 is a schematic view for explaining an arrangement of
a drive system 540 according to another embodiment of this
invention. The drive system 540 of the present embodiment also
includes the power distributing mechanism 16, the first electric
motor M1, the second electric motor M2 and the counter gear pair
CG, as in the embodiment shown in FIG. 80. The present embodiment
is different from the embodiment of FIG. 80, only in the
construction of a step-variable automatic transmission 542 disposed
on the second axis 32c.
[0752] The automatic transmission 542 includes a single-pinion type
second planetary gear set 544 and a single-pinion type third
planetary gear set 546. The second planetary gear set 544 includes:
a second sun gear S2; a second planetary gear P2; a second carrier
CA2 supporting the second planetary gear P2 such that the second
planetary gear P2 is rotatable about its axis and about the axis of
the second sun gear S2; and a second ring gear R2 meshing with the
second sun gear S2 through the second planetary gear P2. For
example, the second planetary gear set 544 has a gear ratio .rho.2
of about 0.368. The third planetary gear set 546 has: a third sun
gear S3, a third planetary gear P3; a third carrier CA3 supporting
the third planetary gear P3 such that the third planetary gear P3
is rotatable about its axis and about the axis of the third sun
gear S3; and a third ring gear R3 meshing with the third sun gear
S2 through the third planetary gear P3. For example, the third
planetary gear set 546 has a gear ratio .rho.3 of about 0.460. The
automatic transmission 542 includes the first and second brakes B1,
B2 and the first through third clutches C1-C3, as in the automatic
transmission 522 of FIG. 84.
[0753] The second sun gear S2 is selectively connected to a power
transmitting member in the form of the counter driven gear CG2 of
the counter gear pair CG through the second clutch C2, and is
selectively fixed to the casing 12 through the first brake B1. The
second carrier CA2 and third ring gear R3 that are integrally fixed
to each other are selectively connected to the counter driven gear
CG2 through the third clutch C3, and are selectively fixed to the
casing 12 through the second brake B2. The second ring gear R2 and
third carrier CA3 are integrally fixed to each other and to the
differential drive gear 32. The third sun gear S3 is selectively
connected to the counter driven gear CG2 through the first clutch
C1.
[0754] The components of the drive system 540 are identical with
those of the embodiment shown in FIG. 80. That is, the power
distributing mechanism 16 is disposed between the engine 8 and the
counter gear pair CG, and adjacent to the counter gear pair CG. The
second electric motor M2 is disposed on the first axis 14c, between
the first planetary gear set 544 and the counter gear pair CG, and
adjacent to the counter gear pair CG. The automatic transmission
542 is disposed between the counter gear pair CG and the
differential drive gear 32 (engine 8), and adjacent to the counter
gear pair CG.
[0755] The above-described second sun gear S2 functions as the
fourth rotary element RE4, and the second carrier CA2 and third
ring gear R3 integrally fixed to each other function as the fifth
rotary element RE5. The second ring gear R2 and third carrier CA3
integrally fixed to each other function as the sixth rotary element
RE6, and the third sun gear S3 functions as the seventh rotary
element RE7. The collinear chart of the embodiments of FIGS. 77-85
applies to the drive system 540.
[0756] The automatic transmission 540 of the present embodiment
also includes the power distributing mechanism 16 functioning as a
continuously-variable shifting portion or a first shifting portion,
and the automatic transmission 542 functioning as a step-variable
shifting portion or a second shifting portion, and the automatic
transmission 542 is principally constituted by the two planetary
gear sets 544, 546. In this respect, the present embodiment has the
same advantage as the embodiment of FIG. 77. Further, the power
distributing mechanism 16 and the automatic transmission 542 are
not disposed coaxially with each other, and the power distributing
mechanism 16 and the automatic transmission 542 are disposed
between the engine 8 and the counter gear pair CG, and the second
electric motor M2 is disposed on the first axis 14c, so that the
required dimension of the drive system in the axial direction can
be favorably reduced, as in the embodiment of FIG. 80.
Embodiment 32
[0757] FIG. 87 is a schematic view for explaining an arrangement of
a drive system 550 according to another embodiment of this
invention. The drive system 550 of the present embodiment also
includes the power distributing mechanism 16, the first electric
motor M1, the second electric motor M2 and the counter gear pair
CG, as in the embodiment shown in FIG. 80. The present embodiment
is different from the embodiment of FIG. 80, only in the
construction of a step-variable automatic transmission 552 disposed
on the second axis 32c.
[0758] The automatic transmission 552 includes a single-pinion type
second planetary gear set 554 and a single-pinion type third
planetary gear set 556. The second planetary gear set 554 includes:
a second sun gear S2; a second planetary gear P2; a second carrier
CA2 supporting the second planetary gear P2 such that the second
planetary gear P2 is rotatable about its axis and about the axis of
the second sun gear S2; and a second ring gear R2 meshing with the
second sun gear S2 through the second planetary gear P2. For
example, the second planetary gear set 544 has a gear ratio .rho.2
of about 0.460. The third planetary gear set 556 has: a third sun
gear S3, a third planetary gear P3; a third carrier CA3 supporting
the third planetary gear P3 such that the third planetary gear P3
is rotatable about its axis and about the axis of the third sun
gear S3; and a third ring gear R3 meshing with the third sun gear
S2 through the third planetary gear P3. For example, the third
planetary gear set 556 has a gear ratio .rho.3 of about 0.585. The
automatic transmission 552 includes the first and second brakes B1,
B2 and the first through third clutches C1-C3, as in the automatic
transmission 522 of FIG. 84.
[0759] The second sun gear S2 and third ring gear R3 are integrally
fixed to each other and selectively connected to a power
transmitting member in the form of the counter driven gear CG2 of
the counter gear pair CG through the first clutch C1. The second
carrier CA2 and third carrier CA3 are integrally fixed to each
other and to an output rotary member in the form of the
differential drive gear 32. The second ring gear R2 is selectively
connected to the counter drive gear CG2 through the third clutch C3
and selectively fixed to the casing 12 through the second brake B2.
The third sun gear S3 is selectively connected to the counter
driven gear CG2 through the first clutch C1 and selectively fixed
to the casing 12 through the first brake B1. The components of the
drive system 550 are identical with those of the preceding
embodiment of FIG. 87.
[0760] The above-described third sun gear S3 functions as the
fourth rotary element RE4, and the second ring gear R2 functions as
the fifth rotary element RE5. The second carrier CA2 and third
carrier CA3 integrally fixed to each other function as the sixth
rotary element RE6, and the second sun gear S2 and third ring gear
R3 integrally fixed to each other function as the seventh rotary
element RE7. The collinear chart of the embodiments of FIGS. 77-86
applies to the drive system 550.
[0761] The automatic transmission 550 of the present embodiment
also includes the power distributing mechanism 16 functioning as a
continuously-variable shifting portion or a first shifting portion,
and the automatic transmission 552 functioning as a step-variable
shifting portion or a second shifting portion, and the automatic
transmission 552 is principally constituted by the two planetary
gear sets 554, 556. In this respect, the present embodiment has the
same advantage as the embodiment of FIG. 77. Further, the power
distributing mechanism 16 and the automatic transmission 552 are
not disposed coaxially with each other, and the power distributing
mechanism 16 and the automatic transmission 552 are disposed
between the engine 8 and the counter gear pair CG, and the second
electric motor M2 is disposed on the first axis 14c, so that the
required dimension of the drive system in the axial direction can
be favorably reduced, as in the embodiment of FIG. 80.
Embodiment 33
[0762] FIG. 88 is a schematic view for explaining a drive system
560 according to another embodiment of this invention. The drive
system 560 of the present embodiment includes the power
distributing mechanism 16, the first electric motor M1, the second
electric motor M2 and the counter gear pair CG, as in the
embodiment shown in FIG. 80. The first and second electric motors
M1, M2 and the counter drive gear CG1 of the counter gear pair CG
are connected to the power distributing mechanism 16 in the same
manner as in the embodiment of FIG. 80.
[0763] The counter driven gear CG2 and the differential drive gear
32 are disposed on the second axis 32c parallel to the first axis
14c. An automatic transmission 562 is disposed on the second axis
32c, between the counter driven gear CG2 and the differential drive
gear 32.
[0764] The automatic transmission 562 includes a single-pinion type
second planetary gear set 564 having a predetermined gear ratio
.rho.2 of about 0.585, for example, and a single-pinion type third
planetary gear set 566 having a predetermined gear ratio .rho.3 of
about 0.368, for example. The automatic transmission 562 includes
the first and second brakes B1, B2 and the first and third clutches
C1, C3. Each of the two brakes B1, B2 and the two clutches C1, C3
is of a wet-type multiple-disc type having a plurality of friction
plates which are superposed on each other and which are forced
against each other by a hydraulic actuator.
[0765] In the automatic transmission 562, the second sun gear S2
and third sun gear S3 are integrally fixed to each other and
selectively fixed to the casing 12 through the first brake B1, and
the second carrier CA2 and third ring gear R3 are integrally fixed
to each other and to an output rotary member in the form of the
differential drive gear 32. The second ring gear R2 is selectively
connected to a power transmitting member in the form of the counter
driven gear CG2 of the counter gear pair CG, and the third carrier
CA3 is selectively connected to the counter driven gear CG2 through
the third clutch. C3 and selectively fixed to the casing 12 through
the second brake B2.
[0766] FIG. 89 is a collinear chart showing an example of the
shifting operation of the drive system 560. As indicated in this
collinear chart, the second sun gear S2 and third sun gear S3
integrally fixed to each other function as the fourth rotary
element RE4, and the third carrier CA3 functions as the fifth
rotary element RE5. Further, the second carrier CA2 and third ring
gear R3 integrally fixed to each other function as the sixth rotary
element RE6, and the ring gear R2 functions as the seventh rotary
element RE7. In the first planetary gear set 24, the first sun gear
S1 functions as the second rotary element RE2, and the first
carrier CA1 functions as the first rotary element RE1, while the
first ring gear R1 functions as the third rotary element RE3.
[0767] The first-gear position is established when the switching
clutch C0, first clutch C1 and second brake B2 are engaged, and the
second-gear position is established when the switching clutch C0,
first clutch C1 and first brake B1 are engaged. The third-gear
position is established when the switching clutch C0, first clutch
C1 and third clutch C3 are engaged, and the fourth-gear position is
established when the switching clutch C3, third clutch C3 and first
brake B1 are engaged. The fifth-gear position is established when
the switching brake B0, third clutch C3 and first brake B1 are
engaged. The first-gear position through the fifth-gear positions
have respective gear ratios .gamma.1-.gamma.5 similar to those in
the preceding embodiments.
[0768] The reverse-gear position is established by reverse rotation
of the third rotary element RE3 (first ring gear R1) which is
caused by rotation of the second electric motor M2 in the direction
opposite to the direction of rotation of the engine 8, and by
engaging actions of the first clutch C1 and third clutch C3 to
transmit a rotary motion of the third rotary element RE3 to the
differential drive gear 32. The gear ratio of this reverse-gear
position is continuously variable by controlling the rotating speed
of the second electric motor M2. In the reverse-gear position, the
rotating speed of the first rotary element RE1 (first carrier CA1)
is zero, as indicated by a straight line L0R1, that is, the engine
8 is at rest. Where the amount of electric energy stored for
operating the second electric motor M2 is smaller than a lower
limit, the engine 8 is operated to operate the first electric motor
M1, as indicated by a straight line L0R2, so that the second
electric motor M2 can be operated with an electric energy generated
by the first electric motor M1.
[0769] The table of FIG. 90 indicates a relationship between the
gear positions of the above-described drive system 560 and
combinations of the hydraulically operated frictional coupling
devices that are engaged to establish the respective gear
positions. As indicated in this table of FIG. 90 by way of example,
the neutral position "N" is established by engaging only the second
clutch C2.
[0770] The present drive system 560 also includes the power
distributing mechanism 16 functioning as a continuously-variable
shifting portion or a first shifting portion, and the automatic
transmission 562 functioning as a step-variable shifting portion or
a second shifting portion. The automatic transmission 562 is
principally constituted by the two planetary gear sets 564, 566,
and has the same advantage as that in the embodiment of FIG. 77.
Further, the power distributing mechanism 16 and the automatic
transmission 562 are not disposed coaxially with each other, and
are disposed between the engine 8 and the counter gear pair CG,
while the second electric motor M2 is disposed on the first axis
14c, so that the required dimension of the drive system in the
axial direction can be favorably reduced, as in the embodiment of
FIG. 80. In the absence of the second clutch C2 provided in the
embodiments of FIGS. 77-87, the size and the axial dimension of the
drive system 560 are further reduced.
Embodiment 34
[0771] FIG. 91 is a schematic view for explaining a drive system
570 according to another embodiment of this invention. The present
embodiment is different from the preceding embodiment of FIG. 88,
primarily in that the power distributing mechanism 16 and the
automatic transmission 562 are disposed coaxially with each other.
Namely, the drive system 570 of the present embodiment is different
from the embodiment of FIG. 88, only in the use of the power
transmitting member 18 in place of the counter gear pair CG, and in
that the automatic transmission 562 is disposed coaxially with the
output shaft 22, between the power transmitting member 18 and the
output shaft 22.
[0772] The present drive system 570 also includes the power
distributing mechanism 16 functioning as a continuously-variable
shifting portion or a first shifting portion, and the automatic
transmission 562 functioning as a step-variable shifting portion or
a second shifting portion. The automatic transmission 562 is
principally constituted by the two planetary gear sets 564, 566,
and has the same advantage as that in the embodiment of FIG. 77.
Further, in the absence of the second clutch C2 provided in the
embodiments of FIGS. 77-87, the size and the axial dimension of the
drive system 570 are further reduced.
Embodiment 35
[0773] FIG. 92 is a schematic view explaining a drive system 460
for a hybrid vehicle, according to another embodiment of this
invention. The drive system 610 shown in FIG. 92 includes: an input
rotary member in the form of an input shaft 14 disposed on a common
axis in a transmission casing 12 (hereinafter abbreviated as
"casing 12") functioning as a stationary member attached to a body
of the vehicle; a differential mechanism in the form of a power
distributing mechanism 16 connected to the input shaft 14 either
directly, or indirectly via a pulsation absorbing damper (vibration
damping device) not shown; a step-variable or multiple-step
automatic transmission 620 interposed between and connected in
series via a power transmitting member 18 (power transmitting
shaft) to the power distributing mechanism 16 and an output shaft
22; and an output rotary member in the form of the above-indicated
output shaft 22 connected to the automatic transmission 20. The
input shaft 12, power distributing mechanism 16, automatic
transmission 620 and output shaft 22 are connected in series with
each other. This drive system 610 is suitably used for a transverse
FR vehicle (front-engine, rear-drive vehicle), and is disposed
between a drive power source in the form of an engine 8 and a pair
of drive wheels 38, to transmit a vehicle drive force to the pair
of drive wheels 38 through a differential gear device 36 (final
speed reduction gear) and a pair of drive axles, as shown in FIG.
7. It is noted that a lower half of the drive system 610, which is
constructed symmetrically with respect to its axis, is omitted in
FIG. 77.
[0774] The automatic transmission 620 includes a double-pinion type
second planetary gear set 626, and a single-pinion type third
planetary gear set 628. The second planetary gear set 426 has: a
second sun gear S2; a plurality of pairs of mutually meshing second
planetary gears P2; a second carrier CA2 supporting the second
planetary gears P2 such that each second planetary gear P2 is
rotatable about its axis and about the axis of the second sun gear
S2; and a second ring gear R2 meshing with the second sun gear S2
through the second planetary gears P2. For example, the second
planetary gear set 626 has a gear ratio .rho.2 of about 0.529. The
third planetary gear set 428 has: a third sun gear S3, a third
planetary gear P3 P3; a third carrier CA3 supporting the third
planetary gear P3 such that the third planetary gear P3 is
rotatable about its axis and about the axis of the third sun gear
S3; and a third ring gear R3 meshing with the third sun gear S3
through the third planetary gear P3. For example, the third
planetary gear set 628 has a gear ratio .rho.3 of about 0.417.
Where the numbers of teeth of the second sun gear S2, second ring
gear R2, third sun gear S3, third ring gear R3, are represented by
ZS2, ZR2, ZS3 and ZR3, respectively, the above-indicated gear
ratios .rho.2 and .rho.3 are represented by ZS2/ZR2 and ZS3/ZR3,
respectively.
[0775] In the automatic transmission 620, the second sun gear S2
and the third ring gear R3 are selectively fixed to the casing 12
through a first brake B1. The second carrier CA2 and the third sun
gear S3 are selectively connected to the power transmitting member
18 through a first clutch C1 and selectively fixed to the casing
through a second brake B2. The second ring gear R2 is selectively
connected to the power transmitting member 18 through a second
clutch C2 and selectively fixed to the casing 12 through a third
brake B3. The third carrier CA3 is fixed to the output shaft
22.
[0776] The above-described switching clutch C0, first clutch C1,
second clutch C2, switching brake B0, first brake B1, second brake
B2 and third brake B3 are hydraulically operated frictional
coupling devices used in a conventional vehicular automatic
transmission. For example, each of these frictional coupling
devices is constituted by a wet-type multiple-disc coupling device
including a plurality of friction plates which are superposed on
each other and which are forced against each other by a hydraulic
actuator, to selective connect two members between which the
coupling device is interposed.
[0777] In the drive system 610 constructed as described above, one
of a first-gear position (first-speed position) through a
fifth-gear position (fifth-speed position), a reverse-gear position
(rear-drive position) and a neural position is selectively
established by engaging actions of a corresponding combination of
the frictional coupling devices selected from the above-described
switching clutch C0, first clutch C1, second clutch C2, switching
brake B0, first brake B1, second brake B2 and third brake B3, as
indicated in the table of FIG. 93. In particular, it is noted that
the power distributing mechanism 16 provided with the switching
clutch C0 and brake B0 can be selectively placed by engagement of
the switching clutch C0 or switching brake B0, in the
fixed-speed-ratio shifting state in which the mechanism 16 is
operable as a transmission having a single gear position with one
speed ratio or a plurality of gear positions with respective speed
ratios, as well as in the continuously-variable shifting state in
which the mechanism 16 is operable as a continuously variable
transmission, as described above. In the present drive system 610,
therefore, a step-variable transmission is constituted by the
automatic transmission 620, and the power distributing mechanism 16
which is placed in the fixed-speed-ratio shifting state by
engagement of the switching clutch C0 or switching brake B0.
Further, a continuously variable transmission is constituted by the
automatic transmission 620, and the power distributing mechanism 16
which is placed in the continuously-variable shifting state, with
none of the switching clutch C0 and brake B0 being engaged.
[0778] Where the drive system 610 functions as the step-variable
transmission, for example, the first-gear position having the
highest speed ratio .gamma.1 of about 3.500, for example, is
established by engaging actions of the switching clutch C0, first
clutch C1 and first brake B1, and the second-gear position having
the speed ratio .gamma.2 of about 1.600, for example, which is
lower than the speed ratio .gamma.1, is established by engaging
actions of the switching clutch C0, second clutch C2 and first
brake B1, as indicated in FIG. 93. The speed ratio is equal to the
input shaft speed N.sub.IN/output shaft speed N.sub.OUT. Further,
the third-gear position having the speed ratio .gamma.3 of about
1.000, for example, which is lower than the speed ratio .gamma.2,
is established by engaging actions of the switching clutch C0,
first clutch C1 and second clutch C2, and the fourth-gear position
having the speed ratio .gamma.4 of about 0.760, for example, which
is lower than the speed ratio .gamma.3, is established by engaging
actions of the switching clutch C0, second clutch C2 and second
brake B2. The fifth-gear position having the speed ratio .gamma.5
of about 0.585, for example, which is smaller than the speed ratio
.gamma.4, is established by engaging actions of the second clutch
C2, switching brake B0 and second brake B2. Further, the
reverse-gear position having the speed ratio .gamma.R of about
2.717, for example, which is intermediate between the speed ratios
.gamma.1 and .gamma.2, is established by engaging actions of the
first clutch C1 and the third brake B3. The neutral position N is
established by engaging only the first clutch C1.
[0779] Where the drive system 610 functions as the
continuously-variable transmission, on the other hand, the
switching clutch C0 and the switching brake B0 are both released,
as indicated in FIG. 93, so that the power distributing mechanism
16 functions as the continuously variable transmission, while the
automatic transmission 620 connected in series to the power
distributing mechanism 16 functions as the step-variable
transmission, whereby the speed of the rotary motion transmitted to
the automatic transmission 620 placed in one of the first-gear,
second-gear, third-gear and fourth-gear positions, namely, the
rotating speed of the power transmitting member 18 is continuously
changed, so that the speed ratio of the drive system when the
automatic transmission 620 is placed in one of those gear positions
is continuously variable over a predetermined range. Accordingly,
the speed ratio of the automatic transmission 620 is continuously
variable across the adjacent gear positions, whereby the overall
speed ratio .gamma.T of the drive system 610 is continuously
variable.
[0780] The collinear chart of FIG. 94 indicates, by straight lines,
a relationship among the rotating speeds of the rotary elements in
each of the gear positions of the drive system 610, which is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 620 functioning as the
step-variable shifting portion or second shifting portion. The
collinear chart of FIG. 94 is a rectangular two-dimensional
coordinate system in which the gear ratios .rho. of the planetary
gear sets 624, 626, 628 are taken along the horizontal axis, while
the relative rotating speeds of the rotary elements are taken along
the vertical axis. A lower one of three horizontal lines X1, X2,
XG, that is, the horizontal line X1 indicates the rotating speed of
0, while an upper one of the three horizontal lines, that is, the
horizontal line X2 indicates the rotating speed of 1.0, that is, an
operating speed N.sub.E of the engine 8 connected to the input
shaft 14. The horizontal line XG indicates the rotating speed of
the power transmitting member 18. Three vertical lines Y1, Y2 and
Y3 corresponding to the power distributing mechanism 16
respectively represent the relative rotating speeds of a second
rotary element (second element) RE2 in the form of the first sun
gear S1, a first rotary element (first element) RE1 in the form of
the first carrier CA1, and a third rotary element (third element)
RE3 in the form of the first ring gear R1. The distances between
the adjacent ones of the vertical lines Y1, Y2 and Y3 are
determined by the gear ratio .rho.1 of the first planetary gear set
624. That is, the distance between the vertical lines Y1 and Y2
corresponds to "1", while the distance between the vertical lines
Y2 and Y3 corresponds to the gear ratio .rho.1. Further, five
vertical lines Y4, Y5, Y6 and Y7 corresponding to the automatic
transmission 20 respectively represent the relative rotating speeds
of a fourth rotary element (fourth element) RE4 in the form of the
second carrier S2 and third sun gear S3 that are integrally fixed
to each other, a fifth rotary element (fifth element) RE5 in the
form of the second ring gear R2, a sixth rotary element (sixth
element) RE6 in the form of the third carrier CA3, and a seventh
rotary element (seventh element) RE7 in the form of the second sun
gear S2 and third ring gear R3 that are integrally fixed to each
other. The distances between the adjacent ones of the vertical
lines Y4-Y7 are determined by the gear ratios .rho.2 and .rho.3 of
the second and third planetary gear sets 626, 628.
[0781] Referring to the collinear chart of FIG. 94, the power
distributing mechanism (continuously variable shifting portion) 16
of the drive system 610 is arranged such that the first rotary
element RE1 (first carrier CA1), which is one of the three rotary
elements of the first planetary gear set 624, is integrally fixed
to the input shaft 14 and selectively connected to the second
rotary element RE2 in the form of the first sun gear S1 through the
switching clutch C0, and this second rotary element RE2 (first sun
gear S1) is fixed to the first electric motor M1 and selectively
fixed to the casing 12 through the switching brake B0, while the
third rotary element RE3 (first ring gear R1) is fixed to the power
transmitting member 18 and the second electric motor M2, so that a
rotary motion of the input shaft 14 is transmitted to the automatic
transmission (step-variable transmission) 620 through the power
transmitting member 18. A relationship between the rotating speeds
of the first sun gear S1 and the first ring gear R1 is represented
by an inclined straight line L0 which passes a point of
intersection between the lines Y2 and X2.
[0782] FIGS. 4 and 5 correspond to a part of the collinear chart of
FIG. 94 which shows the power distributing mechanism 16. FIG. 4
shows an example of an operating state of the power distributing
mechanism 16 placed in the continuously-variable shifting state
with the switching clutch C0 and the switching brake B0 held in the
released state. The rotating speed of the first sun gear S1
represented by the point of intersection between the straight line
L0 and vertical line Y1 is raised or lowered by controlling the
reaction force generated by an operation of the first electric
motor M1 to generate an electric energy, so that the rotating speed
of the first ring gear R1 represented by the point of intersection
between the lines L0 and Y3 is lowered or raised. In the operating
state of FIG. 4, the first sun gear S1 is rotated in the negative
direction, with the first electric motor M1 being operated by
application of an electric energy thereto. While the first sun gear
S1 is rotated in the negative direction as indicated in FIG. 4, the
angle of inclination of the straight line L0 is relatively large,
indicating an accordingly high speed of rotation of the first ring
gear R1 and the power transmitting member 18, making it possible to
drive the vehicle at a relatively high speed. On the other hand,
the application of the electric energy to the first electric motor
M1 results in deterioration of the fuel economy. In the drive
system 610 according to the present embodiment, however, the
automatic transmission 620 is arranged to increase the speed of a
rotary motion transmitted through the power transmitting member 18,
as described below, so that there is not a high degree of
opportunity wherein the first sun gear S1 must be rotated in the
negative direction. Accordingly, the fuel economy is higher in the
present drive system than in the case where the automatic
transmission 620 were not able to increase the speed of the rotary
motion transmitted through the power transmitting member 18.
[0783] FIG. 5 shows an example of an operating state of the power
distributing mechanism 16 placed in the step-variable shifting
state with the switching clutch C0 held in the engaged state. When
the first sun gear S1 and the first carrier CA1 are connected to
each other in this step-variable shifting state, the three rotary
elements indicated above are rotated as a unit, so that the line L0
is aligned with the horizontal line X2, whereby the power
transmitting member 18 is rotated at a speed equal to the engine
speed N.sub.E. When the switching brake B0 is engaged, on the other
hand, the rotation of the power transmitting member 18 is stopped,
so that the straight line L0 is inclined in the state indicated in
FIG. 94, whereby the rotating speed of the first ring gear R1, that
is, the rotation of the power transmitting member 18 represented by
a point of intersection between the straight line L0 and vertical
line Y3 is made higher than the engine speed N.sub.E and
transmitted to the automatic transmission 620.
[0784] In the automatic transmission 620, the fourth rotary element
RE4 is selectively connected to the power transmitting member 18
through the first clutch C1, and selectively fixed to the
transmission casing 12 through the second brake B2, and the fifth
rotary element RE5 is selectively connected to the power
transmitting member 18 through the second clutch C2 and selectively
fixed to the casing 12 through the third brake B3. The sixth rotary
element RE6 is fixed to the output shaft 22, while the seventh
rotary element RE7 is selectively connected to the casing 12
through the first brake B1.
[0785] When the first clutch C1 and the first brake B1 are engaged,
the automatic transmission 620 is placed in the first-speed
position. The rotating speed of the output shaft 22 in the
first-speed position is represented by a point of intersection
between the vertical line Y6 indicative of the rotating speed of
the sixth rotary element RE6 fixed to the output shaft 22 and an
inclined straight line L1 which passes a point of intersection
between the vertical line Y4 indicative of the rotating speed of
the fourth rotary element RE4 and the horizontal line X2, and a
point of intersection between the vertical line Y7 indicative of
the rotating speed of the seventh rotary element RE7 and the
horizontal line X1. Similarly, the rotating speed of the output
shaft 22 in the second-speed position established by the engaging
actions of the second clutch C1 and first brake B1 is represented
by a point of intersection between an inclined straight line L2
determined by those engaging actions and the vertical line Y6
indicative of the rotating speed of the sixth rotary element RE6
fixed to the output shaft 22. The rotating speed of the output
shaft 22 in the third-speed position established by the engaging
actions of the first clutch C1 and second clutch C2 is represented
by a point of intersection between an inclined straight line L3
determined by those engaging actions and the vertical line Y6
indicative of the rotating speed of the sixth rotary element RE6
fixed to the output shaft 22. The rotating speed of the output
shaft 22 in the fourth-speed position established by the engaging
actions of the second brake B2 and second clutch C2 is represented
by a point of intersection between a horizontal line L4 determined
by those engaging actions and the vertical line Y6 indicative of
the rotating speed of the sixth rotary element RE6 fixed to the
output shaft 22. In the fourth-speed position, the output speed of
the automatic transmission is higher than the rotating speed of the
power transmitting member 18. In the first-speed through
fourth-speed positions in which the switching clutch C0 is placed
in the engaged state, the fifth rotary element RE5 is rotated at
the same speed as the engine speed N.sub.E, with the drive force
received from the power distributing mechanism 16. When the
switching clutch B0 is engaged in place of the switching clutch C0,
the sixth rotary element RE6 is rotated at a speed higher than the
engine speed N.sub.E, with the drive force received from the power
distributing mechanism 16. The rotating speed of the output shaft
22 in the fifth-speed position established by the engaging actions
of the second brake B2, second clutch C2 and switching brake B0 is
represented by a point of intersection between a horizontal line L5
determined by those engaging actions and the vertical line Y6
indicative of the rotating speed of the sixth rotary element RE6
fixed to the output shaft 22. In this fifth-speed position, too,
the output speed of the automatic transmission is higher than the
rotating speed of the power transmitting member 18. The rotating
speed of the output shaft 22 in the reverse-gear position R
established by the first clutch C1 and third brake B3 is
represented by a point of intersection between an inclined straight
line LR determined by those engaging actions and the vertical line
Y6 indicative of the rotating speed of the sixth rotary element RE6
fixed to the output shaft 22.
[0786] In the drive system 610 constructed as described above, the
electronic control unit 40 shown in FIG. 6 having the control
functions shown in FIG. 7 or FIG. 11 by way of example performs the
hybrid controls of the engine 8 and the first and second electric
motors M1, M2, the shifting control of the automatic transmission
20, and other vehicle drive controls.
[0787] In the drive system 610 of the present embodiment, the power
distributing mechanism 16 is selectively switched by the engaging
and releasing actions of the switching clutch C0 and the switching
brake B0, between the continuously-variable shifting state in which
the mechanism 16 is operable as an electrically controlled
continuously variable transmission, and the fixed-speed-ratio
shifting state in which the mechanism 16 is operable as a
transmission having fixed speed ratios. On the basis of the vehicle
condition, the switching control means 50 automatically switches
the drive system 610 between the continuously-variable shifting
state and the step-variable shifting state. Therefore, the present
drive system has not only an advantage of an improvement in the
fuel economy owing to a function of a transmission whose speed
ratio is electrically variable, but also an advantage of high power
transmitting efficiency owing to a function of a gear type
transmission capable of mechanically transmitting a vehicle drive
force. Accordingly, when the engine is in a normal output state at
the vehicle running speed V not higher than the upper limit V1,
with the output torque T.sub.OUT not lower than the upper limit T1,
for example, as indicated in FIG. 12, the drive system 610 is
placed in the continuously-variable shifting state, assuring a high
degree of fuel economy of the hybrid vehicle during a normal
city-running, that is, during a low- or medium-speed and low- or
medium-output running. When the vehicle is running at a relatively
high speed V not lower than the upper limit V1, for example, as
indicated in FIG. 12, on the other hand, the drive system 610 is
placed in the step-variable shifting state in which the output of
the engine 8 is transmitted to the drive wheels 38 primarily
through the mechanical power transmitting path, so that the fuel
economy is improved owing to reduction of a loss of conversion of
the mechanical energy into the electric energy, which would take
place when the drive system were placed in the
continuously-variable shifting state. When the vehicle is running
at a relatively high output torque T.sub.OUT not lower than the
upper limit T1, for example, as indicated in FIG. 12, the drive
system 610 is also placed in the step-variable shifting state.
Therefore, the drive system 610 is placed in the
continuously-variable shifting state only when the vehicle speed is
relatively low or medium or when the output torque is relatively
low or medium, so that the maximum amount of electric energy
generated by the first electric motor M1, that is, the maximum
amount of electric energy that must be transmitted from the first
electric motor M1 can be reduced, whereby the required electrical
reaction force of the first electric motor M1 can be reduced,
making it possible to minimize the required sizes of the first
electric motor M1 and the second electric motor M2, and the
required size of the drive system including those electric motors.
Further, the automatic transmission 620 principally constituted by
the two planetary gear sets 626, 628 has a comparatively small
dimension in its axial direction, making it possible to further
reduce the required axial dimension of the drive system 610
including those planetary gear sets.
[0788] The present embodiment is further arranged such that the
output speed of the automatic transmission 620 is higher than the
rotating speed of the power transmitting member 18, so that the
first ring gear R1 of the first planetary gear set 624 which is
rotated with the power transmitting member 18 can be made
comparatively low, even when the vehicle running speed is
comparatively high. Accordingly, there is not a high degree of
opportunity wherein the first electric motor M1 fixed to the first
sun gear S1 must be rotated in the negative direction. Accordingly,
the fuel economy can be improved.
Embodiment 36
[0789] FIG. 95 is a schematic view for explaining an arrangement of
a drive system 680 according to another embodiment of this
invention. The present embodiment is different from the embodiment
shown in FIGS. 92-94, primarily in that the power distributing
mechanism 16 and an automatic transmission 620 are not disposed
coaxially with each other in the present embodiment. The following
description of the present embodiment primarily relates to a
difference between the drive system 680 and the drive system
610.
[0790] The drive system 680 shown in FIG. 95 is provided, within a
casing 12 attached to the vehicle body, with: an input shaft 14
disposed rotatably about a first axis 14c; the power distributing
mechanism 16 mounted on the input shaft 14 directly, or indirectly
through a pulsation absorbing damper (vibration damping device);
the automatic transmission 620 disposed rotatably about a second
axis 32c parallel to the first axis 14c; an output rotary member in
the form of a differential drive gear 32 connected to the automatic
transmission 420; and a power transmitting member in the form of a
counter gear pair CG which connects the power distributing
mechanism 16 and the automatic transmission 620, so as to transmit
a drive force therebetween. This drive system 480 is suitably used
on a transverse FF (front-engine, front-drive) vehicle or a
transverse RR (rear-engine, rear-drive) vehicle, and is disposed
between a drive power source in the form of an engine 8 and a pair
of drive wheels 38. The drive force is transmitted from the
differential drive gear 32 to the pair of drive wheels 38, through
a differential gear 34 meshing with the differential drive gear 32,
a differential gear device 36, a pair of drive axles 37, etc.
[0791] The counter gear pair CG indicated above consists of a
counter drive gear CG1 disposed rotatably on the first axis 14c and
coaxially with the power distributing mechanism 16 and fixed to a
first ring gear R1, and a counter driven gear CG2 disposed
rotatably on the second axis 32c and coaxially with the automatic
transmission 620 and connected to the 6automatic transmission 20
through a first clutch C1 and a second clutch C2. The counter drive
gear CG1 and the counter driven gear CG2 serve as a pair of members
in the form of a pair of gears which are held in meshing engagement
with each other. Since the speed reduction ratio of the counter
gear pair CG (rotating speed of the counter drive gear CG1/rotating
speed of the counter driven gear CG2) is about 1.000, the counter
gear pair CG functionally corresponds to the power transmitting
member 18 in the embodiment shown in FIGS. 92-94, which connects
the power distributing mechanism 16 and the automatic transmission
620. That is, the counter drive gear CG1 corresponds to a power
transmitting member which constitutes a part of the power
transmitting member 18 on the side of the first axis 14c, while the
counter driven gear CG2 corresponds to a power transmitting member
which constitutes another part of the power transmitting member 18
on the side of the second axis 32c.
[0792] Referring to FIG. 95, the individual elements of the drive
system 680 will be described. The counter gear pair CG is disposed
adjacent to one end of the power distributing mechanism 16 which
remote from the engine 8. In other words, the power distributing
mechanism 16 is interposed between the engine 8 and the counter
gear pair CG, and located adjacent to the counter gear pair CG. A
second electric motor M2 is disposed on the first axis 14c, between
a first planetary gear set 24 and the counter gear pair CG, such
that the second electric motor M2 is fixed to the counter drive
gear CG1. The differential drive gear 32 is disposed adjacent to
one end of the automatic transmission 620 which is remote from the
counter gear pair CG, that is, on the side of the engine 8. In
other words, the automatic transmission 620 is interposed between
the counter gear pair CG and the differential drive gear 32 (engine
8), and located adjacent to the counter gear pair CG. Between the
counter gear pair CG and the differential drive gear 32, a second
planetary gear set 626 and a third planetary gear set 628 are
disposed in the order of description, in the direction from the
counter gear pair CG toward the differential drive gear 32. The
first clutch C1 and the second clutch C2 are disposed between the
counter gear pair CG and the second planetary gear set 426.
[0793] The present embodiment is different from the embodiment
shown in FIGS. 92-94, only in that the counter gear pair CG
replaces the power transmitting member 18 connecting the power
distributing mechanism 16 and the automatic transmission 620, and
is identical with the embodiment of FIGS. 92-94 in the arrangements
of the power distributing mechanism 16 and automatic transmission
620. Accordingly, the table of FIG. 93 and the collinear chart of
FIG. 94 apply to the present embodiment.
[0794] In the present embodiment, too, the drive system 680 is
constituted by the power distributing mechanism 16 functioning as
the continuously-variable shifting portion or first shifting
portion, and the automatic transmission 620 functioning as the
step-variable shifting portion or second shifting portion, so that
the drive system 680 has advantages similar to those of the
preceding embodiments. Unlike the embodiment shown in FIGS. 92-94,
the present embodiment is arranged such that the power distributing
mechanism 16 and the automatic transmission 620 are not disposed
coaxially with each other, so that the required dimension of the
drive system 680 in the axial direction can be reduced.
Accordingly, the present drive system can be suitably used on a
transversal FF or RR vehicle such that the first and second axes
14c, 32c are parallel to the transverse or width direction of the
vehicle. In this respect, it is noted that the maximum axial
dimension of a drive system for such a transverse FF or RR vehicle
is generally limited by the width dimension of the vehicle. The
present embodiment has an additional advantage that the required
axial dimension of the drive system 680 can be further reduced,
since the power distributing mechanism 16 and the automatic
transmission 620 are located between the engine 8 (differential
drive gear 32) and the counter gear pair CG. Further, the required
axial dimension of the second axis 32c can be reduced owing to the
arrangement in which the second electric motor M2 is disposed on
the first axis 13c.
Embodiment 37
[0795] FIG. 96 is a schematic view for explaining a drive system
690 according to another embodiment of this invention, which
includes the power distributing mechanism 16, the first electric
motor M1 and the second electric motor M2, as in the embodiment of
FIG. 92. The first and second electric motors M1, M2 are connected
to the power distributing mechanism 16 in the same manner as in the
embodiment of FIG. 92. In the present embodiment, too, the
step-variable automatic transmission 692 is disposed between and
coaxially with the output shaft 22 and the input shaft 14.
[0796] The automatic transmission 692 described above includes a
double-pinion type second planetary gear set 694 and a
single-pinion type third planetary gear set 696. The second
planetary gear set 694 includes: a second sun gear S2; a plurality
of pairs of mutually meshing second planetary gears P2; a second
carrier CA2 supporting the second planetary gears P2 such that each
second planetary gear PA2 is rotatable about its axis and about the
axis of the second sun gear S2; and a second ring gear R2 meshing
with the second sun gear S2 through the second planetary gears P2.
For example, the second planetary gear set 494 has a gear ratio
.rho.2 of about 0.529. The third planetary gear set 696 has: a
third sun gear S3, a third planetary gear P3; a third carrier CA3
supporting the third planetary gear P3 such that the third
planetary gear P3 is rotatable about its axis and about the axis of
the third sun gear S3; and a third ring gear R3 meshing with the
third sun gear S3 through the third planetary gear P3. For example,
the third planetary gear set 696 has a gear ratio .rho.3 of about
0.333.
[0797] Like the automatic transmission 620 of FIG. 92, the
automatic transmission 692 includes the first through third brakes
B1-B3 and the first and second third clutches C1, C2. The second
sun gear S2 is selectively fixed to the casing 12 through the first
brake B1. The second carrier CA2 and the third sun gear S3 are
integrally fixed to each other and selectively connected to the
power transmitting member 18 through the first clutch C1 and
selectively fixed to the casing 12 through the second brake B2. The
second ring gear R2 and the third carrier CA3 that are integrally
fixed to each other are selectively connected to the power
transmitting member 18 through the second clutch C2 and selectively
fixed to the casing 12 through the third brake B3. The third ring
gear R3 is fixed to the output shaft 22.
[0798] The above-described second carrier CA2 and third sun gear S3
integrally fixed to each other function as the fourth rotary
element RE4, and the second ring gear R2 and the third carrier CA3
integrally fixed to each other function as the fifth rotary element
RE5. Further, the third ring gear R3 functions as the sixth rotary
element RE6, and the second sun gear S2 functions as the seventh
rotary element RE7. The collinear chart of the embodiment of FIG.
92 applies to the drive system 690.
[0799] The present drive system 690 also includes the power
distributing mechanism 16 functioning as a continuously-variable
shifting portion or a first shifting portion, and the automatic
transmission 692 functioning as a step-variable shifting portion or
a second shifting portion. The automatic transmission 692 is
principally constituted by the two planetary gear sets 694, 696,
and has the same advantage as that in the embodiment of FIG.
92.
Embodiment 38
[0800] FIG. 97 is a schematic view for explaining an arrangement of
a drive system 700 according to another embodiment of this
invention, which is different from the embodiment of FIG. 95 in
that the automatic transmission 692 of FIG. 96 is used in the
present embodiment, in place of the automatic transmission 680 of
the embodiment of FIG. 95. In other words, the present embodiment
is different from the embodiment of FIG. 96, like the embodiment of
FIG. 92 is different from the embodiment of FIG. 95, only in that
the counter gear pair CG is used in place of the power transmitting
member 18, for connection between the power distributing mechanism
16 and the automatic transmission 692. Therefore, the drive system
700 of the present embodiment has the same advantage as the
embodiment of FIG. 95.
Embodiment 39
[0801] FIG. 98 is a schematic view for explaining a drive system
710 according to another embodiment of this invention, which
includes the power distributing mechanism 16, the first electric
motor M1, the second electric motor M2 and the counter gear pair
CG, as in the embodiment of FIG. 92 or 96. The connection between
the first and second electric motors M, M2 and the power
distributing mechanism 16 is the same as in the embodiment of FIG.
92 or 97. In the present embodiment, too, a step-variable automatic
transmission 712 is disposed between the power transmitting member
18 and the output shaft 22, such that the step-variable automatic
transmission 712 is coaxial with the output shaft 22 and the input
shaft 14.
[0802] The automatic transmission 712 described above includes a
double-pinion type second planetary gear set 714 and a
single-pinion type third planetary gear set 716. The second
planetary gear set 714 includes: a second sun gear S2; a plurality
of pairs of mutually meshing second planetary gears P2; a second
carrier CA2 supporting the second planetary gears P2 such that each
second planetary gear P2 is rotatable about its axis and about the
axis of the second sun gear S2; and a second ring gear R2 meshing
with the second sun gear S2 through the second planetary gears P2.
For example, the second planetary gear set 714 has a gear ratio
.rho.2 of about 0.471. The third planetary gear set 716 has: a
third sun gear S3, a third planetary gear P3; a third carrier CA3
supporting the third planetary gear P3 such that the third
planetary gear P3 is rotatable about its axis and about the axis of
the third sun gear S3; and a third ring gear R3 meshing with the
third sun gear S2 through the third planetary gear P3. For example,
the third planetary gear set 516 has a gear ratio .rho.3 of about
0.333.
[0803] Like the above-described automatic transmissions 620, etc.,
the automatic transmission 712 includes the first through third
brakes B1-B3 and the first and second third clutches C1, C2. The
second sun gear S2 and the third sun gear S3 that are integrally
fixed to each other are selectively connected to the power
transmitting member 18 through the first clutch and selectively
fixed to the casing 12 through the second brake B2. The second
carrier CA2 is selectively fixed to the casing 12 through the first
brake B1. The second ring gear R2 and the third carrier CA3 that
are integrally fixed to each other are selectively connected to the
power transmitting member 18 through the second clutch C2 and
selectively fixed to the casing 12 through the third brake B3. The
third ring gear R3 is fixed to the output shaft 22.
[0804] The above-described second sun gear S2 and third sun gear S3
integrally fixed to each other function as the fourth rotary
element RE4, and the second ring gear R2 and the third carrier CA3
integrally fixed to each other function as the fifth rotary element
RE5. Further, the third ring gear R3 functions as the sixth rotary
element RE6, and the second carrier CA2 functions as the seventh
rotary element RE7. The collinear chart of the embodiment of FIGS.
92-97 applies to the drive system 710.
[0805] The present drive system 710 also includes the power
distributing mechanism 16 functioning as a continuously-variable
shifting portion or a first shifting portion, and the automatic
transmission 712 functioning as a step-variable shifting portion or
a second shifting portion. The automatic transmission 712 is
principally constituted by the two planetary gear sets 714, 716,
and has the same advantage as that in the embodiment of FIG.
92.
Embodiment 40
[0806] FIG. 99 is a schematic view for explaining an arrangement of
a drive system 720 according to another embodiment of this
invention, which is different from the embodiments of FIGS. 95 and
97 in that the automatic transmission 712 of FIG. 98 is used in the
present embodiment, in place of the automatic transmission 620, 692
of the embodiments of FIGS. 95 and 97. In other words, the present
embodiment is different from the embodiment of FIG. 98, like the
embodiment of FIG. 92 is different from the embodiment of FIG. 95,
only in that the counter gear pair CG is used in place of the power
transmitting member 18, for connection between the power
distributing mechanism 16 and the automatic transmission 712.
Therefore, the drive system 720 of the present embodiment has the
same advantage as the embodiments of FIGS. 95 and 97.
Embodiment 41
[0807] FIG. 100 is a schematic view for explaining a drive system
730 according to another embodiment of this invention, which
includes the power distributing mechanism 16, the first electric
motor M1, the second electric motor M2 and the counter gear pair
CG, as in the embodiment of FIG. 95. The present embodiment is
different from the embodiment of FIG. 95, only in the construction
of a step-variable automatic transmission 732 disposed on the
second axis 32c.
[0808] The automatic transmission 732 described above includes a
double-pinion type second planetary gear set 734 and a
single-pinion type third planetary gear set 736. The second
planetary gear set 7344 includes: a second sun gear S2; a plurality
of pairs of mutually meshing second planetary gears P2; a second
carrier CA2 supporting the second planetary gears P2 such that each
second planetary gear P2 is rotatable about its axis and about the
axis of the second sun gear S2; and a second ring gear R2 meshing
with the second sun gear S2 through the second planetary gears P2.
For example, the second planetary gear set 734 has a gear ratio
.rho.2 of about 0.471. The third planetary gear set 73 has: a third
sun gear S3, a third planetary gear P3; a third carrier CA3
supporting the third planetary gear P3 such that the third
planetary gear P3 is rotatable about its axis and about the axis of
the third sun gear S3; and a third ring gear R3 meshing with the
third sun gear S3 through the third planetary gear P3. For example,
the third planetary gear set 736 has a gear ratio .rho.3 of about
0.333.
[0809] Like the above-described automatic transmission 620, etc.,
the automatic transmission 732 includes the first through third
brakes B1-B3 and the first and second clutches C1, C2. The second
sun gear S2 and the third sun gear S3 that are integrally fixed to
each other are selectively connected to a power transmitting member
in the form of the counter driven gear CG2 of the counter gear pair
CG through the first clutch C1 and selectively fixed to the casing
12 through the second brake B2. The second carrier CA2 and the
third ring gear R3 are integrally fixed to each other and
selectively fixed to the casing 12 through the first brake B1. The
second ring gear R2 is selectively connected to the counter driven
gear CG2 through the second clutch C2, and selectively fixed to the
casing 12 through the third brake B3. The third carrier CA3 is
fixed to an output rotary member in the form of the differential
drive gear 32. The thus constructed automatic transmission 732 is
disposed on one side of the counter gear pair CG on which the power
distributing mechanism 16 and the engine 8 are disposed. Namely,
the automatic transmission 732 is disposed in parallel with the
power distributing mechanism 16 and engine 8 disposed on the first
axis 14c.
[0810] The above-described second sun gear S2 and third sun gear S3
integrally fixed to each other function as the fourth rotary
element RE4, and the second ring gear R2 functions as the fifth
rotary element RE5. The third carrier CA3 functions as the sixth
rotary element RE6, and the second carrier CA2 and third ring gear
R3 integrally fixed to each other function as the seventh rotary
element RE7. The collinear chart of the embodiments of FIGS. 92-99
applies to the drive system 730.
[0811] The present drive system 730 also includes the power
distributing mechanism 16 functioning as a continuously-variable
shifting portion or a first shifting portion, and the automatic
transmission 732 functioning as a step-variable shifting portion or
a second shifting portion, and the automatic transmission 732 is
principally constituted by the two planetary gear sets 734, 736. In
this respect, the present embodiment has the same advantage as the
embodiment of FIG. 92. Further, the power distributing mechanism 16
and the electric motor M2 are disposed on the first axis 14c, and
between the engine 8 and the counter gear pair CG, while the
automatic transmission 732 is disposed on the second axis 32c
separate from the first axis 14c, and in parallel with the engine 8
and power distributing mechanism 16 disposed on the first axis 14c,
so that the required dimension of the drive system 730 in its axial
direction can be reduced.
Embodiment 42
[0812] FIG. 101 is a schematic view for explaining an arrangement
of a drive system 740 according to another embodiment of this
invention. The present embodiment also includes the power
distributing mechanism 16, the first electric motor M1, the second
electric motor M2 and the counter gear pair CG, as in the
embodiment shown in FIG. 95. The present embodiment is different
from the embodiment of FIG. 95, only in the construction of a
step-variable automatic transmission 742 disposed on the second
axis 32c.
[0813] The automatic transmission 742 includes a double-pinion type
second planetary gear set 744 and a single-pinion type third
planetary gear set 746. The second planetary gear set 744 includes:
a second sun gear S2; a plurality of pairs of mutually meshing
second planetary gears P2; a second carrier CA2 supporting the
second planetary gears P2 such that each second planetary gear P2
is rotatable about its axis and about the axis of the second sun
gear S2; and a second ring gear R2 meshing with the second sun gear
S2 through the second planetary gears P2. For example, the second
planetary gear set 524 has a gear ratio .rho.2 of about 0.375. The
third planetary gear set 746 has: a third sun gear S3, a third
planetary gear P3; a third carrier CA3 supporting the third
planetary gear P3 such that the third planetary gear P3 is
rotatable about its axis and about the axis of the third sun gear
S3; and a third ring gear R3 meshing with the third sun gear S2
through the third planetary gear P3. For example, the third
planetary gear set 526 has a gear ratio .rho.3 of about 0.417. The
automatic transmission 742 includes the first through third brakes
B1-B3 and the first and second clutch C1, C2, as in the
above-described automatic transmissions 620, etc.
[0814] The second sun gear S2 and third ring gear R3 are integrally
fixed to each other and is selectively fixed to the casing 12
through the first brake B1. The second carrier CA2 is selectively
connected to a power transmitting member in the form of the counter
driven gear CG2 of the counter gear pair CG through the second
clutch C2 and selectively fixed to the casing through the third
brake B3. The second ring gear R2 and third carrier CA3 are
integrally fixed to each other and to an output rotary member in
the form of the differential drive gear 32. The third sun gear S3
is selectively connected to the counter driven gear CG2 through the
first clutch C1 and selectively fixed to the casing 12 through the
second brake B2. The thus constructed automatic transmission 742 is
disposed on one side of the counter gear pair CG on which the power
distributing mechanism 16 and engine 8 are disposed. Namely, the
automatic transmission 742 is disposed in parallel with the power
distributing mechanism 16 and engine 8 disposed on the first axis
14c.
[0815] The above-described third sun gear S3 functions as the
fourth rotary element RE4, and the second carrier CA2 functions as
the fifth rotary element RE5. The second ring gear R2 and third
carrier CA3 integrally fixed to each other function as the sixth
rotary element RE6, and the second sun gear S2 and third ring gear
R3 integrally fixed to each other function as the seventh rotary
element RE7. The collinear chart of the embodiments of FIGS. 92-100
applies to the drive system 740.
[0816] The present drive system 740 also includes the power
distributing mechanism 16 functioning as a continuously-variable
shifting portion or a first shifting portion, and the automatic
transmission 742 functioning as a step-variable shifting portion or
a second shifting portion, and the automatic transmission 742 is
principally constituted by the two planetary gear sets 744, 74. In
this respect, the present embodiment has the same advantage as the
embodiment of FIG. 92. Further, the power distributing mechanism 16
and the electric motor M2 are disposed on the first axis 14c, and
between the engine 8 and the counter gear pair CG, while the
automatic transmission 742 is disposed on the second axis 32c
separate from the first axis 14c, and in parallel with the engine 8
and the power distributing mechanism 16 disposed on the first axis
14c, so that the required dimension of the drive system 740 in its
axial direction can be reduced.
Embodiment 43
[0817] FIG. 102 is a schematic view for explaining an arrangement
of a drive system 750 according to another embodiment of this
invention. The drive system 750 of the present embodiment also
includes the power distributing mechanism 16, the first electric
motor M1, the second electric motor M2 and the counter gear pair
CG, as in the embodiment shown in FIG. 95. The present embodiment
is different from the embodiment of FIG. 95, only in the
construction of a step-variable automatic transmission 752 disposed
on the second axis 32c.
[0818] The automatic transmission 752 includes a single-pinion type
second planetary gear set 754 and a double-pinion type third
planetary gear set 756. The second planetary gear set 754 includes:
a second sun gear S2; a second planetary gear P2; a second carrier
CA2 supporting the second planetary gear P2 such that the second
planetary gear P2 is rotatable about its axis and about the axis of
the second sun gear S2; and a second ring gear R2 meshing with the
second sun gear S2 through the second planetary gear P2. For
example, the second planetary gear set 754 has a gear ratio .rho.2
of about 0.333. The third planetary gear set 756 has: a third sun
gear S3, a plurality of pairs of mutually meshing third planetary
gears P3; a third carrier CA3 supporting the third planetary gears
P3 such that each third planetary gear P3 is rotatable about its
axis and about the axis of the third sun gear S3; and a third ring
gear R3 meshing with the third sun gear S2 through the third
planetary gears P3. For example, the third planetary gear set 756
has a gear ratio .rho.3 of about 0.294. The automatic transmission
750 includes the first through third brakes B1-B3 and the first and
second clutches C1, C2, as in the above-described automatic
transmissions 620, etc.
[0819] The second sun gear S2 and third sun gear S3 are integrally
fixed to each other and selectively connected to a power
transmitting member in the form of the counter driven gear CG2 of
the counter gear pair CG through the first clutch C1 and
selectively fixed to the casing 12 through the second brake B2. The
second carrier CA2 is selectively connected to the counter driven
gear CG2 through the second clutch C2 and selectively fixed to the
casing 12 through the third brake B3. The second ring gear R2 and
third ring gear R3 are integrally fixed to each other and to an
output rotary member in the form of the differential drive gear 32,
and the third carrier CA3 is selectively fixed to the casing 12
through the first brake B1. The thus constructed automatic
transmission 752 is disposed on one side of the counter gear pair
CG on which the power distributing mechanism 16 and engine 8 are
disposed. Namely, the automatic transmission 752 is disposed in
parallel with the power distributing mechanism 16 and engine 8
disposed on the first axis 14c.
[0820] The above-described second sun gear S2 and third sun gear S3
integrally fixed to each other function as the fourth rotary
element RE4, and the second carrier CA2 functions as the fifth
rotary element RE5. The second ring gear R2 and third ring gear R3
integrally fixed to each other function as the sixth rotary element
RE6, and the third carrier CA3 functions as the seventh rotary
element RE7. The collinear chart of the embodiments of FIGS. 91-101
applies to the drive system 750.
[0821] The present drive system 750 also includes the power
distributing mechanism 16 functioning as a continuously-variable
shifting portion or a first shifting portion, and the automatic
transmission 752 functioning as a step-variable shifting portion or
a second shifting portion, and the automatic transmission 752 is
principally constituted by the two planetary gear sets 754, 756. In
this respect, the present embodiment has the same advantage as the
embodiment of FIG. 92. Further, the power distributing mechanism 16
and the second electric motor M2 are disposed on one side of the
counter gear pair CG on which the engine 8 and counter gear pair CG
are disposed, while the automatic transmission 752 is disposed on
the second axis 32c separate from the first axis 14c, and in
parallel with the engine 8 and power distributing mechanism 16, so
that the required dimension of the drive system 750 in its axial
direction can be reduced, as in the embodiment of FIG. 80.
Embodiment of FIG. 44
[0822] FIG. 103 is a schematic view for explaining an arrangement
of a drive system 760 according to another embodiment of this
invention. The drive system 76 of the present embodiment also
includes the power distributing mechanism 16, the first electric
motor M1, the second electric motor M2 and the counter gear pair
CG, as in the embodiment shown in FIG. 95. The present embodiment
is different from the embodiment of FIG. 95, only in the
construction of a step-variable automatic transmission 762 disposed
on the second axis 32c.
[0823] The automatic transmission 762 includes a single-pinion type
second planetary gear set 764 and a double-pinion type third
planetary gear set 766. The second planetary gear set 764 includes:
a second sun gear S2; a second planetary gear P2; a second carrier
CA2 supporting the second planetary gear P2 such that the second
planetary gear P2 is rotatable about its axis and about the axis of
the second sun gear S2; and a second ring gear R2 meshing with the
second sun gear S2 through the second planetary gear P2. For
example, the second planetary gear set 544 has a gear ratio .rho.2
of about 0.368. The third planetary gear set 766 has: a third sun
gear S3, a plurality of pairs of mutually meshing third planetary
gears P3; a third carrier CA3 supporting the third planetary gears
P3 such that each third planetary gear P3 is rotatable about its
axis and about the axis of the third sun gear S3; and a third ring
gear R3 meshing with the third sun gear S3 through the third
planetary gears P3. For example, the third planetary gear set 766
has a gear ratio .rho.3 of about 0.375. The automatic transmission
762 includes the first through third brakes B1-B3 and the first and
second clutches C1, C2, as in the above-described automatic
transmissions 620, etc.
[0824] The second sun gear S2 is selectively connected to a power
transmitting member in the form of the counter driven gear CG2 of
the counter gear pair CG through the first clutch C1 and is
selectively fixed to the casing 12 through the second brake B2. The
second carrier CA2 and third carrier CA3 that are integrally fixed
to each other are selectively connected to the counter driven gear
CG2 through the second clutch C2 and selectively fixed to the
casing 12 through the third brake B3. The second ring gear R2 and
third ring gear R3 are integrally fixed to each other and to an
output rotary member in the form of the differential drive gear 32.
The third sun gear S3 is selectively fixed to the casing 12 through
the first brake B1. The thus constructed automatic transmission 762
is disposed on one side of the counter gear pair CG on which the
power distributing mechanism 16 and engine 8 are disposed. Namely,
the automatic transmission 762 is disposed in parallel with the
power distributing mechanism 16 and engine 8 disposed on the first
axis 14c.
[0825] The above-described second sun gear S2 functions as the
fourth rotary element RE4, and the second carrier CA2 and third
carrier CA3 integrally fixed to each other function as the fifth
rotary element RE6. The second ring gear R2 and third ring gear R3
integrally fixed to each other function as the sixth rotary element
RE6, and the third sun gear S3 functions as the seventh rotary
element RE7. The collinear chart of the embodiments of FIGS. 92-102
applies to the drive system 760.
[0826] The drive system 760 of the present embodiment also includes
the power distributing mechanism 16 functioning as a
continuously-variable shifting portion or a first shifting portion,
and the automatic transmission 762 functioning as a step-variable
shifting portion or a second shifting portion, and the automatic
transmission 762 is principally constituted by the two planetary
gear sets 764, 766. In this respect, the present embodiment has the
same advantage as the embodiment of FIG. 92. Further, the power
distributing mechanism 16 and second electric motor M2 are disposed
on the first axis 14c, and between the engine 8 and the counter
gear pair CG, while the automatic transmission 762 is disposed on
the second axis 32c separate from the first axis 14c, in parallel
with the engine 8 and power distributing mechanism 16 disposed on
the first axis 14c, so that the required dimension of the drive
system 760 in the axial direction can be reduced.
Embodiment 45
[0827] FIG. 104 is a schematic view for explaining an arrangement
of a drive system 770 according to another embodiment of this
invention. The drive system 770 of the present embodiment also
includes the power distributing mechanism 16, the first electric
motor M1, the second electric motor M2 and the counter gear pair
CG, as in the embodiments shown in FIG. 95, etc. The present
embodiment is different from the embodiment of FIG. 95, only in the
construction of a step-variable automatic transmission 772 disposed
on the second axis 32c.
[0828] The automatic transmission 772 includes a double-pinion type
second planetary gear set 774 and a single-pinion type third
planetary gear set 776. The second planetary gear set 774 includes:
a second sun gear S2, a plurality of pairs of mutually meshing
second planetary gears P2; a second carrier CA2 supporting the
second planetary gears P2 such that each second planetary gear P2
is rotatable about its axis and about the axis of the second sun
gear S2; and a second ring gear R2 meshing with the second sun gear
S2 through the second planetary gear P3. For example, the second
planetary gear set 774 has a gear ratio .rho.2 of about 0.471. The
third planetary gear set 776 has: a third sun gear S3, a third
planetary gear P3; a third carrier CA3 supporting the third
planetary gear P3 such that the third planetary gear P3 is
rotatable about its axis and about the axis of the third sun gear
S3; and a third ring gear R3 meshing with the third sun gear S2
through the third planetary gear P3. For example, the third
planetary gear set 776 has a gear ratio .rho.3 of about 0.600. The
automatic transmission 772 includes the first through third brakes
B1-B3 and the first and second clutches C1, C2, as in the
above-described automatic transmissions 620, etc.
[0829] The second sun gear S2 is selectively connected to a power
transmitting member in the form of the counter driven gear CG2 of
the counter gear pair CG through the first clutch C1 and
selectively fixed to the casing 12 through the second brake B2. The
second carrier CA2 and third sun gear S3 are integrally fixed to
each other and selectively fixed to the casing through the first
brake B1. The second ring gear R2 and third ring gear R3 that are
integrally fixed to each other are selectively connected to the
counter driven gear CG2 through the second clutch C2 and
selectively fixed to the casing 12 through the third brake B3. The
third carrier CA3 is fixed to an output rotary member in the form
of the differential drive gear 32. The thus constructed automatic
transmission 772 is disposed on one side of the counter gear pair
CG on which the power distributing mechanism 16 and engine 8 are
disposed. Namely, the automatic transmission 772 is disposed in
parallel with the power distributing mechanism 16 and engine 8
disposed on the first axis 14c.
[0830] The above-described second sun gear S2 functions as the
fourth rotary element RE4, and the second ring gear R2 and third
ring gear R3 integrally fixed to each other function as the fifth
rotary element RE5. The third carrier CA3 functions as the sixth
rotary element RE6, and the second carrier CA2 and third sun gear
S3 integrally fixed to each other function as the seventh rotary
element RE7. The collinear chart of the embodiments of FIGS. 92-103
applies to the drive system 770.
[0831] The drive system 770 of the present embodiment also includes
the power distributing mechanism 16 functioning as a
continuously-variable shifting portion or a first shifting portion,
and the automatic transmission 772 functioning as a step-variable
shifting portion or a second shifting portion, and the automatic
transmission 772 is principally constituted by the two planetary
gear sets 774, 776. In this respect, the present embodiment has the
same advantage as the embodiment of FIG. 92. Further, the power
distributing mechanism 16 and second electric motor M2 are disposed
on the first axis 14c, and between the engine 8 and counter gear
pair CG, while the automatic transmission 772 are disposed on the
second axis 32c separate from the first axis 14c, in parallel with
the engine 8 and power distributing mechanism 16, so that the
required dimension of the drive system 770 in its axial direction
can be reduced.
Embodiment 46
[0832] FIG. 105 is a schematic view for explaining a drive system
780 according to another embodiment of this invention. The drive
system 780 of the present embodiment includes the power
distributing mechanism 16, the first electric motor M1, the second
electric motor M2 and the counter gear pair CG, as in the
embodiment shown in FIG. 95, etc. The present embodiment is
different from the embodiment of FIG. 95, only in the construction
of a step-variable automatic transmission 782 disposed on the
second axis 32c.
[0833] The automatic transmission 782 includes a double-pinion type
second planetary gear set 784 and a single-pinion type third
planetary gear set 786. The second planetary gear set 784 includes:
a second sun gear S2, a plurality of pairs of mutually meshing
second planetary gears P2; a second carrier CA2 supporting the
second planetary gears P2 such that each second planetary gear P2
is rotatable about its axis and about the axis of the second sun
gear S2; and a second ring gear R2 meshing with the second sun gear
S2 through the second planetary gear P3. For example, the second
planetary gear set 784 has a gear ratio .rho.2 of about 0.529. The
third planetary gear set 786 has: a third sun gear S3, a third
planetary gear P3; a third carrier CA3 supporting the third
planetary gear P3 such that the third planetary gear P3 is
rotatable about its axis and about the axis of the third sun gear
S3; and a third ring gear R3 meshing with the third sun gear S2
through the third planetary gear P3. For example, the third
planetary gear set 786 has a gear ratio .rho.3 of about 0.600. The
automatic transmission 782 includes the first through third brakes
B1-B3 and the first and second clutches C1, C2, as in the
above-described automatic transmissions 620, etc.
[0834] The second sun gear S2 and third sun gear S3 are integrally
fixed to each other and selectively fixed to the casing 12 through
the first brake B1, and the second carrier CA2 is selectively
connected to a power transmitting member in the form of the counter
driven gear CG2 of the counter gear pair CG through the first
clutch and selectively fixed to the casing 12 through the second
brake B2. The second ring gear R2 and third ring gear R3 that are
integrally fixed to each other are selectively connected to the
counter driven gear CG2 through the second clutch C2 and
selectively fixed to the casing 12 through the third brake B3. The
third carrier CA3 is fixed to an output rotary member in the form
of the differential drive bear 32. The thus constructed automatic
transmission 782 is disposed on one side of the counter gear pair
CG on which the power distributing mechanism 16 and engine 8 are
disposed. Namely, the automatic transmission 782 is disposed in
parallel with the power distributing mechanism 16 and engine 8
disposed on the first axis 14c.
[0835] The above-described second carrier CA2 functions as the
fourth rotary element RE4, and the second ring gear R2 and third
ring gear R3 integrally fixed to each other function as the fifth
rotary element RE5. The third carrier CA3 functions as the sixth
rotary element RE6, and the second sun gear S2 and third sun gear
S3 integrally fixed to each other function as the seventh rotary
element RE7. The collinear chart of the embodiments of FIG. 92-104
applies to the drive system 780.
[0836] The drive system 780 of the present embodiment also includes
the power distributing mechanism 16 functioning as a
continuously-variable shifting portion or a first shifting portion,
and the automatic transmission 782 functioning as a step-variable
shifting portion or a second shifting portion, and the automatic
transmission 782 is principally constituted by the two planetary
gear sets 784, 786. In this respect, the present embodiment has the
same advantage as the embodiment of FIG. 92. Further, the power
distributing mechanism 16 and second electric motor M2 are disposed
on the first axis 14c, and between the engine 8 and counter gear
pair CG, while the automatic transmission 782 are disposed on the
second axis 32c separate from the first axis 14c, in parallel with
the engine 8 and power distributing mechanism 16, so that the
required dimension of the drive system 780 in its axial direction
can be reduced.
Embodiment 47
[0837] FIG. 106 is a schematic view for explaining a drive system
790 according to another embodiment of this invention. The drive
system 790 of the present embodiment includes the power
distributing mechanism 16, the first electric motor M1, the second
electric motor M2 and the counter gear pair CG, as in the
embodiment shown in FIG. 95, etc. The present embodiment is
different from the embodiment of FIG. 95, only in the construction
of a step-variable automatic transmission 792 disposed on the
second axis 32c.
[0838] The automatic transmission 792 includes a double-pinion type
second planetary gear set 794 and a single-pinion type third
planetary gear set 796. The second planetary gear set 794 includes:
a second sun gear S2, a plurality of pairs of mutually meshing
second planetary gears P2; a second carrier CA2 supporting the
second planetary gears P2 such that each second planetary gear P2
is rotatable about its axis and about the axis of the second sun
gear S2; and a second ring gear R2 meshing with the second sun gear
S2 through the second planetary gear P3. For example, the second
planetary gear set 794 has a gear ratio .rho.2 of about 0.294. The
third planetary gear set 796 has: a third sun gear S3, a third
planetary gear P3; a third carrier CA3 supporting the third
planetary gear P3 such that the third planetary gear P3 is
rotatable about its axis and about the axis of the third sun gear
S3; and a third ring gear R3 meshing with the third sun gear S2
through the third planetary gear P3. For example, the third
planetary gear set 796 has a gear ratio .rho.3 of about 0.600. The
automatic transmission 792 includes the first through third brakes
B1-B3 and the first and second clutches C1, C2, as in the
above-described automatic transmissions 620, etc.
[0839] The second sun gear S2 is selectively connected to a power
transmitting member in the form of the counter drive gear CG2 of
the counter gear pair CG through the first clutch C1 and
selectively fixed to the casing 12 through the second brake B2, and
the second carrier CA2 and third sun gear S3 are integrally fixed
to each other and selectively fixed to the casing 12 through the
first brake B1. The second ring gear R2 and third carrier CA3 are
integrally fixed to each other and to an output rotary member in
the form of the differential drive gear 32. The third ring gear R3
is selectively connected to the counter driven gear CG2 through the
second clutch C2 and selectively fixed to the casing 12 through the
third brake B3. The thus constructed automatic transmission 792 is
disposed on one side of the counter gear pair CG on which the power
distributing mechanism 16 and engine 8 are disposed. Namely, the
automatic transmission 792 is disposed in parallel with the power
distributing mechanism 16 and engine 8 disposed on the first axis
14c.
[0840] The above-described second sun gear S2 functions as the
fourth rotary element RE4, and the third ring gear R3 functions as
the fifth rotary element RE5. The second ring gear R2 and third
carrier CA3 integrally fixed to each other function as the sixth
rotary element RE6, and the second carrier CA2 and third sun gear
S3 integrally fixed to each other function as the seventh rotary
element RE7. The collinear chart of the embodiments of FIG. 92-105
applies to the drive system 790.
[0841] The drive system 790 of the present embodiment also includes
the power distributing mechanism 16 functioning as a
continuously-variable shifting portion or a first shifting portion,
and the automatic transmission 792 functioning as a step-variable
shifting portion or a second shifting portion, and the automatic
transmission 792 is principally constituted by the two planetary
gear sets 794, 796. In this respect, the present embodiment has the
same advantage as the embodiment of FIG. 92. Further, the power
distributing mechanism 16 and second electric motor M2 are disposed
on the first axis 14c, and between the engine 8 and counter gear
pair CG, while the automatic transmission 792 are disposed on the
second axis 32c separate from the first axis 14c, in parallel with
the engine 8 and power distributing mechanism 16, so that the
required dimension of the drive system 790 in its axial direction
can be reduced.
Embodiment 48
[0842] FIG. 107 is a schematic view for explaining a drive system
800 according to another embodiment of this invention. The drive
system 800 of the present embodiment includes the power
distributing mechanism 16, the first electric motor M1, the second
electric motor M2 and the counter gear pair CG, as in the
embodiment shown in FIG. 95, etc. The present embodiment is
different from the embodiment of FIG. 95, only in the construction
of a step-variable automatic transmission 802 disposed on the
second axis 32c.
[0843] The automatic transmission 802 includes a single-pinion type
second planetary gear set 804 and a single-pinion type third
planetary gear set 806. The second planetary gear set 804 includes:
a second sun gear S2, a second planetary gear P2; a second carrier
CA2 supporting the second planetary gear P2 such that the second
planetary gear P2 is rotatable about its axis and about the axis of
the second sun gear S2; and a second ring gear R2 meshing with the
second sun gear S2 through the second planetary gear P3. For
example, the second planetary gear set 804 has a gear ratio .rho.2
of about 0.333. The third planetary gear set 806 has: a third sun
gear S3, a third planetary gear P3; a third carrier CA3 supporting
the third planetary gear P3 such that the third planetary gear P3
is rotatable about its axis and about the axis of the third sun
gear S3; and a third ring gear R3 meshing with the third sun gear
S2 through the third planetary gear P3. For example, the third
planetary gear set 806 has a gear ratio .rho.3 of about 0.417. The
automatic transmission 802 includes the first through third brakes
B1-B3 and the first and second clutches C1, C2, as in the
above-described automatic transmissions 620, etc.
[0844] The second sun gear S2 and third sun gear S3 that are
integrally fixed to each other are selectively connected to a power
transmitting member in the form of the counter drive gear CG2 of
the counter gear pair CG through the first clutch C1 and
selectively fixed to the casing 12 through the second brake B2, and
the second carrier CA2 is selectively connected to the counter
drive gear CG2 through the second clutch C2 and selectively fixed
to the casing 12 through the third brake B3. The second ring gear
R2 and third carrier CA3 are integrally fixed to each other and to
an output rotary member in the form of the differential drive gear
32. The third ring gear R3 is selectively fixed to the casing 12
through the first brake B1.
[0845] The above-described second sun gear S2 and third sun gear R3
function as the fourth rotary element RE4, and the second carrier
CA2 functions as the fifth rotary element RE5. The second ring gear
R2 and third carrier CA3 integrally fixed to each other function as
the sixth rotary element RE6, and the third ring gear S3 functions
as the seventh rotary element RE7. The collinear chart of the
embodiments of FIG. 92-106 applies to the drive system 800.
[0846] The drive system 800 of the present embodiment also includes
the power distributing mechanism 16 functioning as a
continuously-variable shifting portion or a first shifting portion,
and the automatic transmission 802 functioning as a step-variable
shifting portion or a second shifting portion, and the automatic
transmission 802 is principally constituted by the two planetary
gear sets 804, 806. In this respect, the present embodiment has the
same advantage as the embodiment of FIG. 95. Further, the power
distributing mechanism 16 and second electric motor M2 are disposed
on the first axis 14c, and between the engine 8 and counter gear
pair CG, while the automatic transmission 802 are disposed on the
second axis 32c separate from the first axis 14c, in parallel with
the engine 8 and power distributing mechanism 16, so that the
required dimension of the drive system 800 in its axial direction
can be reduced.
Embodiment 49
[0847] FIG. 108 is a schematic view for explaining a drive system
810 according to another embodiment of this invention. The drive
system 810 of the present embodiment includes the power
distributing mechanism 16, the first electric motor M1, the second
electric motor M2 and the counter gear pair CG, as in the
embodiment shown in FIG. 95, etc. The present embodiment is
different from the embodiment of FIG. 95, only in the construction
of a step-variable automatic transmission 812 disposed on the
second axis 32c.
[0848] The automatic transmission 812 includes a single-pinion type
second planetary gear set 814 and a single-pinion type third
planetary gear set 816. The second planetary gear set 814 includes:
a second sun gear S2, a second planetary gear P2; a second carrier
CA2 supporting the second planetary gear P2 such that the second
planetary gear P2 is rotatable about its axis and about the axis of
the second sun gear S2; and a second ring gear R2 meshing with the
second sun gear S2 through the second planetary gear P3. For
example, the second planetary gear set 814 has a gear ratio .rho.2
of about 0.333. The third planetary gear set 816 has: a third sun
gear S3, a third planetary gear P3; a third carrier CA3 supporting
the third planetary gear P3 such that the third planetary gear P3
is rotatable about its axis and about the axis of the third sun
gear S3; and a third ring gear R3 meshing with the third sun gear
S2 through the third planetary gear P3. For example, the third
planetary gear set 816 has a gear ratio .rho.3 of about 0.600. The
automatic transmission 812 includes the first through third brakes
B1-B3 and the first and second clutches C1, C2, as in the
above-described automatic transmissions 620, etc.
[0849] The second sun gear S2 is selectively connected to a power
transmitting member in the form of the counter drive gear CG2 of
the counter gear pair CG through the first clutch C1 and
selectively fixed to the casing 12 through the second brake B2, and
the second carrier CA2 and third ring gear R3 that are integrally
fixed to each other are selectively connected to the counter drive
gear CG2 through the second clutch C2 and selectively fixed to the
casing 12 through the third brake B3. The second ring gear R2 and
third carrier CA3 are integrally fixed to each other and to an
output rotary member in the form of the differential drive gear 32.
The third sun gear S3 is selectively fixed to the casing 12 through
the first brake B1. The thus constructed automatic transmission 812
is disposed on one side of the counter gear pair CG on which the
power distributing mechanism 16 and engine 8 are disposed. Namely,
the automatic transmission 812 is disposed in parallel with the
power distributing mechanism 16 and engine 8 disposed on the first
axis 14c.
[0850] The above-described second sun gear S2 functions as the
fourth rotary element RE4, and the second carrier CA2 and third
ring gear R3 integrally fixed to each other function as the fifth
rotary element RE6. The second ring gear R2 and third carrier CA3
integrally fixed to each other function as the sixth rotary element
RE6, and the third sun gear R3 functions as the seventh rotary
element RE7. The collinear chart of the embodiments of FIG. 92-107
applies to the drive system 810.
[0851] The drive system 810 of the present embodiment also includes
the power distributing mechanism 16 functioning as a
continuously-variable shifting portion or a first shifting portion,
and the automatic transmission 812 functioning as a step-variable
shifting portion or a second shifting portion, and the automatic
transmission 812 is principally constituted by the two planetary
gear sets 814, 816. In this respect, the present embodiment has the
same advantage as the embodiment of FIG. 92. Further, the power
distributing mechanism 16 and second electric motor M2 are disposed
on the first axis 14c, and between the engine 8 and counter gear
pair CG, while the automatic transmission 812 are disposed on the
second axis 32c separate from the first axis 14c, in parallel with
the engine 8 and power distributing mechanism 16, so that the
required dimension of the drive system 810 in its axial direction
can be reduced.
Embodiment 50
[0852] FIG. 109 is a schematic view for explaining a drive system
820 according to another embodiment of this invention. The drive
system 820 of the present embodiment includes the power
distributing mechanism 16, the first electric motor M1, the second
electric motor M2 and the counter gear pair CG, as in the
embodiment shown in FIG. 95, etc. The present embodiment is
different from the embodiment of FIG. 95, only in the construction
of a step-variable automatic transmission 822 disposed on the
second axis 32c.
[0853] The automatic transmission 822 includes a single-pinion type
second planetary gear set 824 and a single-pinion type third
planetary gear set 826. The second planetary gear set 824 includes:
a second sun gear S2, a second planetary gear P2; a second carrier
CA2 supporting the second planetary gear P2 such that the second
planetary gear P2 is rotatable about its axis and about the axis of
the second sun gear S2; and a second ring gear R2 meshing with the
second sun gear S2 through the second planetary gear P3. For
example, the second planetary gear set 824 has a gear ratio .rho.2
of about 0.600. The third planetary gear set 826 has: a third sun
gear S3, a third planetary gear P3; a third carrier CA3 supporting
the third planetary gear P3 such that the third planetary gear P3
is rotatable about its axis and about the axis of the third sun
gear S3; and a third ring gear R3 meshing with the third sun gear
S2 through the third planetary gear P3. For example, the third
planetary gear set 826 has a gear ratio .rho.3 of about 0.417. The
automatic transmission 822 includes the first through third brakes
B1-B3 and the first and second clutches C1, C2, as in the
above-described automatic transmissions 620, etc.
[0854] The second sun gear S2 is selectively fixed to the casing 12
through the first brake B1, and the second carrier CA2 and third
carrier CA3 are fixed to an output rotary member in the form of the
differential drive gear 32. The second ring gear R2 is selectively
connected to the counter drive gear CG2 through the second clutch
C2 and selectively fixed to the casing 12 through the third brake
B3, and the third sun gear is selectively connected to a power
transmitting member in the form of the counter driven gear CG2 of
the counter gear pair CG through the first clutch C1 and
selectively fixed to the casing 12 through the second brake B2. The
thus constructed automatic transmission 822 is disposed on one side
of the counter gear pair CG on which the power distributing
mechanism 16 and engine 8 are disposed. Namely, the automatic
transmission 822 is disposed in parallel with the power
distributing mechanism 16 and engine 8 disposed on the first axis
14c.
[0855] The above-described third sun gear S3 functions as the
fourth rotary element RE4, and the second ring gear R2 functions as
the fifth rotary element RE5. The second carrier CA2 and third
carrier CA3 integrally fixed to each other function as the sixth
rotary element RE6, and the second sun gear S2 and third ring gear
R3 integrally fixed to each other function as the seventh rotary
element RE7. The collinear chart of the embodiments of FIG. 92-108
applies to the drive system 820.
[0856] The drive system 820 of the present embodiment also includes
the power distributing mechanism 16 functioning as a
continuously-variable shifting portion or a first shifting portion,
and the automatic transmission 822 functioning as a step-variable
shifting portion or a second shifting portion, and the automatic
transmission 822 is principally constituted by the two planetary
gear sets 824, 826. In this respect, the present embodiment has the
same advantage as the embodiment of FIG. 92. Further, the power
distributing mechanism 16 and second electric motor M2 are disposed
on the first axis 14c, and between the engine 8 and counter gear
pair CG, while the automatic transmission 822 are disposed on the
second axis 32c separate from the first axis 14c, in parallel with
the engine 8 and power distributing mechanism 16, so that the
required dimension of the drive system 820 in its axial direction
can be reduced.
[0857] While the embodiments of the present invention have
described above in detail by reference to the drawings, the present
invention may be otherwise embodied.
[0858] Each of the drive systems 10, 70, 80, 92-, 110, 120, 130,
140, 150, 160, 170, 180, 190, 200, 210, 220, 410, 480, 490, 500,
510, 520, 530, 540, 550, 560, 570, 610, 680, 690, 700, 710, 720,
730, 740, 750, 760, 770, 780, 790, 800, 810 and 820 according to
the embodiments described above is switchable between the
continuously-variable shifting state in which the drive system
functions as an electrically controlled continuously variable
transmission, and the step-variable shifting state in which the
drive system functions as a step-variable transmission, by
switching the power distributing mechanism 16 between its
differential state and non-differential state. This manner of
switching between the continuously-variable shifting state and the
step-variable shifting state is one mode of switching of the
shifting state as a result of the switching of the power
distributing mechanism 16 between the differential and
non-differential states. For example, the speed ratio of the power
distributing mechanism 16 may be variable in steps rather than
continuously even in its differential state, so that the drive
system functions as a step-variable transmission in the
differential state of the power distributing mechanism 16. In other
words, the differential state and non-differential state of the
drive system 10, 70, 80, 92-, 110, 120, 130, 140, 150, 160, 170,
180, 190, 200, 210, 220, 410, 480, 490, 500, 510, 520, 530, 540,
550, 560, 570, 610, 680, 690, 700, 710, 720, 730, 740, 750, 760,
770, 780, 790, 800, 810 and 820 (power distributing mechanism 16)
do not necessarily correspond to the continuously-variable shifting
state and the step-variable shifting state, respectively, and the
drive system 10, 70, 80, 92-, 110, 120, 130, 140, 150, 160, 170,
180, 190, 200, 210, 220, 410, 480, 490, 500, 510, 520, 530, 540,
550, 560, 570, 610, 680, 690, 700, 710, 720, 730, 740, 750, 760,
770, 780, 790, 800, 810 and 820 is not arranged to be switchable
between the continuously-variable and step-variable shifting
states. The principle of the present invention merely requires the
switching between the differential state and the non-differential
state (locked state) of the drive system (transmission mechanism)
10, 70, 80, 92-, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200,
210, 220, 410, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570,
610, 680, 690, 700, 710, 720, 730, 740, 750, 760, 770, 780, 790,
800, 810 and 820, the power distributing mechanism 16, or the
differential portion 11 (switchable type shifting portion 11, 81,
93, or power distributing mechanism 16, 84, 94).
[0859] The automatic transmission 112 in the illustrated
embodiments has the five rotary elements including the eighth
rotary element RE8 directly fixed to the power transmitting member
18 for transmission of a drive force to the power transmitting
member 18, the seventh rotary element RE7 fixed to the output shaft
22 and the sixth rotary element RE6 fixed to the casing 12 through
the third brake B3, and the direction of rotation of the rotary
motion input to the automatic transmission 112 is reversed with
respect to that of the engine 8, by the power distributing
mechanism 16, so that the power transmitting member 18 is rotated
in the negative direction, and the drive system 110 is placed in
the reverse-gear position by engaging the third brake B3. However,
the direction of rotation of the rotary motion input to the
automatic transmission can be reversed by the power distributing
mechanism, provided the automatic transmission has at least three
rotary elements the rotating speeds of which are represented by
straight lines in a collinear chart in which the at least three
rotary elements are arranged in a direction from one of opposite
ends of the collinear chart toward the other end, in a
predetermined order, such that one of the at least three rotary
elements is connected to the power transmitting member 18 for
transmission of the drive force to the power transmitting member
18, that is, connected to the power transmitting member 18 directly
or through a clutch, and another of the at least three rotary
elements is connected to the output member for transmission of the
drive force to the output member of the automatic transmission,
while a further one of the at least three rotary elements is fixed
to a stationary member through a brake. When this brake is engaged,
the drive system is placed in the reverse-gear position. Where one
of the at least three rotary elements is connected to the power
transmitting member 18 through the clutch, this clutch as well as
the brake is engaged to establish the reverse-gear position.
[0860] For example, the first brake B1 in place of the third brake
B3 may be engaged in the automatic transmission 112, to place the
drive system 110 in the reverse-gear position. Further, the
direction of rotation of the rotary motion input to the automatic
transmission 92, for example, can be reversed by the power
distributing mechanism 84, and the drive system can be placed in
the reverse-gear position by engaging the first clutch C1 and the
second brake B2.
[0861] The automatic transmission 112 in the illustrated
embodiments has the five rotary elements including the eighth
rotary element RE8 directly fixed to the power transmitting member
18 for transmission of a drive force to the power transmitting
member 18, and the seventh rotary element RE7 fixed to the output
shaft 22, and the second clutch C2 for rotation of the rotary
elements of the automatic transmission 112 as a unit, and the
direction of rotation of the rotary motion input to the automatic
transmission 112 is reversed with respect to that of the engine 8,
by the power distributing mechanism 16, so that the power
transmitting member 18 is rotated in the negative direction, and
the drive system 110 is placed in the reverse-gear position by
engaging the second clutch C2. However, the direction of rotation
of the rotary motion input to the automatic transmission can be
reversed by the power distributing mechanism, provided the
automatic transmission has at least three rotary elements one of
which is connected to the power transmitting member 18 for
transmission of the drive force to the power transmitting member
18, that is, connected to the power transmitting member 18 directly
or through a power transmitting clutch, and another of which is
connected to the output member for transmission of the drive force
to the output member of the automatic transmission, and provided
that the automatic transmission has a clutch for rotation of the
rotary elements of the automatic transmission as a unit. When this
clutch is engaged, the drive system is placed in the reverse-gear
position. Where one of the at least three rotary elements is
connected to the power transmitting member 18 through the power
transmitting clutch, this power transmitting clutch as well as the
clutch is engaged to establish the reverse-gear position.
[0862] In the power distributing mechanisms 16, 84, 94 in the
illustrated embodiments, the first carrier CA1 is fixed to the
engine 8, and the first sun gear S1 is fixed to the first electric
motor M1, while the first ring gear R1 is fixed to the power
transmitting member 18 or the counter gear pair CG. This
arrangement of connection is not essential, provided the engine 8,
first electric motor M1 and power transmitting member 18 or counter
gear pair CG are fixed to respective ones of the three elements
CA1, S1 and R1 of the first planetary gear set 24.
[0863] Although the engine 8 is directly connected to the input
shaft 14 in the illustrated embodiments, the engine 8 may be
operatively connected to the input shaft 14 through gears, a belt
or the like, and need not be disposed coaxially with the input
shaft 14.
[0864] In the illustrated embodiments, each of the first electric
motor M1 and the second electric motor M2 is disposed coaxially
with the input shaft 14, the first axis 14c or the second axis 32c,
and the first electric motor M1 is fixed to the first sun gear S1
while the second electric motor M2 is fixed to the power
transmitting member 18 or the counter gear pair CG. However, this
arrangement is not essential. For example, the first electric motor
M1 may be fixed to the first sun gear S1 through gears, a belt or
the like, and the second electric motor M2 may be fixed to the
power transmitting member 18 or the counter gear pair CG through
gears, a belt or the like.
[0865] Although each power distributing mechanism 16, 84 described
above is provided with the switching clutch C0 and the switching
brake B0, the power distributing mechanism need not be provided
with both of these switching clutch C0 and brake B0, and may be
provided with only one of the switching clutch C0 and brake B0.
While the power distributing mechanism 94 is provided with the
switching brake B0, this power distributing mechanism may be
provided with both of the switching clutch C0 and the switching
brake B0 or only the switching clutch C0. Although the switching
clutch C0 is arranged to selectively connect the sun gear S1 and
carrier CA1 to each other, the switching clutch C0 may be arranged
to selectively connect the sun gear S1 and ring gear R1 to each
other, or the carrier CA1 and ring gear R1. In essence, the
switching clutch C0 is required to be a switching device arranged
to connect any two of the three elements of the first planetary
gear set 24.
[0866] The switching clutch C0 is engaged to establish the neutral
position "N" in the drive systems 10, 70, 80, 92-, 120, 130, 140,
180, 190, 200, 210, 220, 410, 480, 490, 500, 510, 520, 530, 540,
550, 560, 570, 610, 680, 690, 700, 710, 720, 730, 740, 750, 760,
770, 780, 790, 800, 810 and 820 of the illustrated embodiments.
However, the neutral position need not be established by engaging
the switching clutch C0. Conversely, the switching clutch C0 may be
engaged to establish the neutral position "N" in the drive systems
110, 150, 160, 170, 210 and 220.
[0867] Each of the hydraulically operated frictional coupling
devices such as the switching clutch C0 and switching brake B0 used
in the illustrated embodiments may be a coupling device of a
magnetic-powder type, an electromagnetic type or a mechanical type,
such as a powder (magnetic powder) clutch, an electromagnetic
clutch and a meshing type dog clutch. Each brake may be a band
brake including a rotary drum and one band or two bands which
is/are wound on the outer circumferential surface of the rotary
drum and tightened at one end by a hydraulic actuator.
[0868] In the illustrated embodiments, the second electric motor M2
is fixed to the power transmitting member 18 or the counter gear
pair CG. However, the second electric motor M2 may be fixed to the
output shaft 22 or the differential drive gear 32, or to a rotary
member of the automatic transmission 20, 72, 86, 96, 112, 172, 420,
492, 512, 522, 532, 542, 552, 562, 620, 692, 712, 732, 742, 752,
762, 772, 782, 792, 802, 812, 822.
[0869] In the illustrated embodiments, the step-variable automatic
transmission (automatic transmission portion) 20, 72, 86, 96, 112,
172 is disposed between the drive wheels 38, and the power
transmitting member 18 or counter gear pair CG which is the output
member of the switchable type shifting portion (differential
portion) 11, 81, 93, namely, of the power distributing mechanism
16, 84, 94. However, such step-variable automatic transmission may
be replaced by any other type of power transmitting device such as
a permanent meshing type parallel-two-axes automatic transmission
the gear positions of which are automatically selectable by select
cylinders and shift cylinders and which is well known as an
automatic transmission such as a continuously variable transmission
(CVT), and a manual transmission. Alternatively, any automatic
transmission need not be provided. Where a continuously variable
transmission (CVT) is provided, the drive system may be placed in
the step-variable shifting state when the power distributing
mechanism 16, 84, 94 is placed in its fixed-speed-ratio shifting
state. The step-variable shifting state is interpreted to mean a
state in which a vehicle drive force is transmitted primarily
through a mechanical power transmitting path, without using an
electric path. The continuously variable transmission may be
arranged to establish a plurality of predetermined fixed speed
ratios which correspond to those of the gear positions of a
step-variable transmission and which are stored in a memory.
[0870] In the illustrated embodiments, each of the drive systems
10, 70, 80, 92, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200,
210, 220, 410, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570,
610, 680, 690, 700, 710, 720 730, 740, 750, 760, 770, 780, 790,
800, 810, 820 is used as a drive system for a hybrid vehicle which
is arranged to be driven with a torque of the first electric motor
M1 or second electric motor M2 as well as a torque of the engine 8.
However, the present invention is applicable to a vehicular drive
system which has only a function of a continuously variable
transmission called "electric CVT" and in which a hybrid control is
not implemented with respect to the power distributing mechanism
16, 84, 94 of the drive system 10, 70, 80, 92, 110, 120, 130, 140,
150, 160, 170, 180, 190, 200, 210, 220, 410, 480, 490, 500, 510,
520, 530, 540, 550, 560, 570, 610, 680, 690, 700, 710, 720 730,
740, 750, 760, 770, 780, 790, 800, 810, 820.
[0871] The power distributing mechanism 16, 84, 94 provided in the
illustrated embodiments may be replaced by a differential gear
device including a pinion rotated by the engine, and a pair of
bevel gears which mesh with the pinion and which are respectively
operatively connected to the first and second electric motors M1,
M2.
[0872] Although the power distributing mechanism 16, 84, 94 is
constituted by one planetary gear set in the illustrated
embodiments, the power distributing mechanism may be constituted by
two or more planetary gear sets and arranged to be operable as a
transmission having three or more gear positions when placed in its
fixed-speed-ratio shifting state.
[0873] The counter gear pair CG used as the power transmitting
member in the illustrated embodiments may be replaced by a power
transmitting device, which is constituted, for example, by a
sprocket wheel disposed on the first axis 14c, another sprocket
wheel disposed on the second axis 20c, and a chain which
operatively connects those sprocket wheels. This power transmitting
device may be replaced by a device using pulleys and a belt in
place of the sprocket wheels and chain. In these cases, another
counter shaft is provided, since the relationship between the
direction of rotation of the engine 8 and the direction of rotation
of the drive wheels 38 is reversed with respect to that where the
counter gear pair CG is used.
[0874] In the illustrated embodiments, the shift lever 48 placed in
its manual position M permits the selection of the gear positions.
However, the shift lever may be arranged to manually select a
desired one of the gear positions, for example, first-gear through
fifth-gear positions in the drive system 10, according to a manual
operation of the shift lever from the manual position M to the
shift-up position "+" or shift-down position "-".
[0875] While the switch 44 is of a seesaw type switch in the
illustrated embodiments, the switch 44 may be replaced by a single
pushbutton switch, two pushbutton switches that are selectively
pressed into operated positions, a lever type switch, a slide-type
switch or any other type of switch or switching device that is
operable to select a desired one of the continuously-variable
shifting state (differential state) and the step-variable shifting
state (non-differential state). The switch 44 may or may not have a
neutral position. Where the switch 44 does not have the neutral
position, an additional switch may be provided to enable and
disable the switch 44. The function of this additional switch
corresponds to the neutral position of the switch 44.
[0876] In the illustrated embodiments, each of the automatic
transmission portions 20, 72, 86, 96, 112, 172 is connected in
series to and coaxially with the differential portion 11 through
the power transmitting member 18. However, those automatic
transmissions may be disposed on a counter shaft disposed in
parallel with the input shaft 14. In this case, the differential
portion 11 and the automatic transmission 20, 82 are connected to
each other for transmission of a drive force therebetween, by a
counter gear pair, or a power transmitting device such as a set of
sprocket wheels and a chain.
[0877] Although the relationship memory means 54 stores one map or
two maps for each of the step-variable shifting control, the
drive-power-source selection control and the switching control, the
memory means 54 may store three or more maps for each of those
controls, as needed.
[0878] In the illustrated embodiments, the system efficiency
.eta.sysc in the continuously-variable shifting state and the
system efficiency .eta.sysu in the step-variable shifting state are
stored constants obtained by experimentation. However, these
efficiencies may be changed as a function of the vehicle condition
such as the vehicle running speed V and the temperature of the
working oil of the automatic transmission 20. Further, the system
efficiency .eta.sysc in the continuously-variable shifting state
and the system efficiency .eta.sysu in the step-variable shifting
state need not be used to calculate the fuel consumption ratio fs.
In this case, the calculated fuel consumption ratio fs is not
necessarily accurate, but approximate values of the fuel economy in
the continuously-variable and step-variable shifting states may be
compared with each other.
[0879] The value .eta.gi in the right side of the equation (3) used
in the illustrated embodiments need not be used.
[0880] In the illustrated embodiments, the switching-map changing
means 86 of the switching control means 50 is arranged to change
the switching boundary line map of FIG. 12 so as to change the
entirety of the continuously-variable or step-variable shifting
region corresponding to the shifting state not selected by the
switch 44, to the other shifting region corresponding to the
shifting state selected by the switch 44. However, the
switching-map changing means 86 may be arranged to change a portion
of the shifting region corresponding to the non-selected shifting
state to the other shifting region corresponding to the selected
shifting state. For example, the switching boundary lines in FIG.
12 are moved to increase the upper vehicle-speed limit V1 or upper
output-torque limit T1, so as to enlarge the continuously-variable
or step-variable shifting region corresponding to the shifting
state selected by the switch 44.
[0881] In the illustrated embodiment of FIG. 12, the transmission
mechanism 10 is selectively placed in one of the
continuously-variable and step-variable shifting states, according
to the stored continuously-variable and step-variable shifting
regions. However, the stored switching map of FIG. 12 may be
formulated such that the continuously-variable shifting region
covers the entire area of the vehicle condition, so that the
transmission mechanism 10 is normally held in the
continuously-variable shifting state, and placed in the
step-variable shifting state when the switching map of FIG. 12 is
entirely or partially changed as a result of manual selection of
the step-variable shifting state by the vehicle operator. In other
words, the stored switching map may be formulated to normally
select the continuously-variable shifting state, and to permit the
switching control means 50 to switch the shifting state to the
step-variable shifting state upon selection of the step-variable
shifting state by the vehicle operator. In this case, the vehicle
operator is required to operate the switch 44 only when the vehicle
operator desires the step-variable shifting state, and the switch
44 need not be arranged to select the continuously-variable
shifting state.
[0882] In the embodiment of FIGS. 88-90, the reverse-gear position
is established by engaging the first clutch C1 and the third clutch
C3. However, the reverse-gear position may be established by
engaging the first clutch C1 and the first brake B1, or the first
clutch C1 and the second brake B2.
[0883] While the embodiments of the present invention have been
described above for illustrative purpose only, it is to be
understood that the present invention may be embodied with various
changes and improvements, which may occur to those skilled in the
art.
* * * * *