U.S. patent application number 12/851058 was filed with the patent office on 2011-03-24 for hybrid drive system.
This patent application is currently assigned to AISIN AW CO., LTD.. Invention is credited to Shoji TAKAHASHI, Hideyuki UMEDA, Mitsugi YAMASHITA.
Application Number | 20110070995 12/851058 |
Document ID | / |
Family ID | 43757119 |
Filed Date | 2011-03-24 |
United States Patent
Application |
20110070995 |
Kind Code |
A1 |
YAMASHITA; Mitsugi ; et
al. |
March 24, 2011 |
HYBRID DRIVE SYSTEM
Abstract
A hybrid drive system configured with an input shaft and a
friction type continuously variable transmission (CVT) device. The
CVT includes an input member drivingly connected to the input
shaft, and an output member. Rotation of the input member is
steplessly changed in speed and transmitted to the output member by
a shear force of an oil film interposed at the contact position.
The drive system includes an electric motor having a dedicated
output shaft, a differential device, and a gear transmission device
that is structured from a meshing rotary transmission mechanism. A
case includes at least a first space filled with traction oil and
accommodating the CVT device, and a second space filled with
lubricant oil and accommodating the gear transmission device.
Inventors: |
YAMASHITA; Mitsugi; (Anjo,
JP) ; TAKAHASHI; Shoji; (Anjo, JP) ; UMEDA;
Hideyuki; (Chiryu, JP) |
Assignee: |
AISIN AW CO., LTD.
Anjo-shi
JP
|
Family ID: |
43757119 |
Appl. No.: |
12/851058 |
Filed: |
August 5, 2010 |
Current U.S.
Class: |
476/30 ; 476/33;
476/47; 903/909; 903/918 |
Current CPC
Class: |
F16H 37/021 20130101;
F16H 15/42 20130101; B60K 6/405 20130101; B60K 6/48 20130101; B60K
6/543 20130101; Y02T 10/6221 20130101; Y02T 10/62 20130101; F16H
57/0491 20130101; Y10T 74/19014 20150115 |
Class at
Publication: |
476/30 ; 476/47;
476/33; 903/909; 903/918 |
International
Class: |
F16H 37/02 20060101
F16H037/02; F16H 15/04 20060101 F16H015/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 18, 2009 |
JP |
2009-218120 |
Claims
1. A hybrid drive system comprising: an input shaft that moves in
accordance with an engine; a friction type continuously variable
transmission device that includes an input member that is drivingly
connected to the input shaft, and an output member, wherein a
contact position between the input member and the output member is
changed, and a rotation of the input member is steplessly changed
in speed and transmitted to the output member by a shear force of
an oil film interposed at the contact position; an electric motor
that includes a dedicated output shaft; a differential device; a
gear transmission device that forms at least part of a power
transmission path that transmits a rotation of the output shaft of
the electric motor to the differential device, and is structured
from a meshing rotary transmission mechanism; and a case that
includes at least a first space that is filled with traction oil
and accommodates the friction type continuously variable
transmission device, and a second space that is filled with
lubricant oil and accommodates the gear transmission device,
wherein the first space and the second space are divided in an
oil-tight manner.
2. The hybrid drive system according to claim 1, wherein the output
shaft of the electric motor is a first shaft, the input shaft and
the input member of the friction type continuously variable
transmission device disposed coaxially form a second shaft, the
output member of the friction type continuously variable
transmission device is a third shaft, right and left axle shafts
connected to the differential device form a fourth shaft, the
first, second, third, and fourth shafts are arranged mutually
parallel and rotatably supported by the case, and gears that form
the gear transmission device are disposed on the first, second,
third, and fourth shafts, and the electric motor and the
continuously variable transmission device are disposed on a first
side in an axial direction of the gear transmission device, and a
second side of the gear transmission device is connected to the
engine.
3. The hybrid drive system according to claim 1, wherein the gear
transmission device transmits a rotation of the output shaft of the
electric motor to the input member of the friction type
continuously variable transmission device, and transmits a rotation
of the output member to the differential device.
4. The hybrid drive system according to claim 1, wherein the case
includes: a first case member that supports a first end portion of
the output shaft of the electric motor, respective first end
portions of the input member and the output member of the friction
type continuously variable transmission device, and a first end
portion of a differential case of the differential device; a second
case member that supports a second end portion of the output shaft
of the electric motor, the input shaft, an output shaft mounted
with the output member of the friction type continuously variable
transmission device, and a second end portion of the differential
case of the differential device; and a partition that supports
respective second end portions of the input member and the output
member of the friction type continuously variable transmission
device, wherein the first case member and the second case member
are connected, and the partition divides the first space and the
second space in an oil-tight manner.
5. The hybrid drive system according to claim 1, wherein the gear
transmission device includes an output gear that is provided on the
output shaft of the electric motor, and a differential ring gear
that forms an input portion of the differential device, wherein the
output gear and the differential ring gear disposed so as to
overlap in the axial direction.
6. The hybrid drive system according to claim 5, wherein the gear
transmission device includes an intermediate gear that is provided
on the input shaft and moves in accordance with the output gear,
and an output gear of the continuously variable transmission device
that is provided integrated with the output member of the friction
type continuously variable transmission device in a rotating
direction, wherein the intermediate gear and the output gear of the
continuously variable transmission device are disposed so as to
overlap the output gear and the differential ring gear in the axial
direction.
7. The hybrid drive system according to claim 6, wherein the output
gear and the intermediate gear are toothed gears, and power is
transmitted between the toothed gears through a toothed idler
gear.
8. The hybrid drive system according to claim 6, wherein the output
gear and the intermediate gear are sprockets, and power is
transmitted between the sprockets through a chain wound between the
sprockets.
9. The hybrid drive system according to claim 7, wherein the
toothed idler gear is disposed overlapping the electric motor in a
radial direction.
10. The hybrid drive system according to claim 1, wherein the
friction type continuously variable transmission device is a cone
ring type continuously variable transmission device, with the input
member and the output member formed from conical friction wheels
that are disposed such that axes of the friction wheels are
mutually parallel and large diameter portions and small diameter
portions of the friction wheels are respectively opposite each
other in the axial direction, and a ring provided interposed
between opposing inclined surfaces of the friction wheels and moved
in the axial direction to steplessly change a speed.
11. The hybrid drive system according to claim 1, wherein the input
shaft and the input member of the friction type continuously
variable transmission device are drivingly connected by a
spline.
12. The hybrid drive system according to claim 2, wherein the gear
transmission device transmits a rotation of the output shaft of the
electric motor to the input member of the friction type
continuously variable transmission device, and transmits a rotation
of the output member to the differential device.
13. The hybrid drive system according to claim 12, wherein the case
includes: a first case member that supports a first end portion of
the output shaft of the electric motor, respective first end
portions of the input member and the output member of the friction
type continuously variable transmission device, and a first end
portion of a differential case of the differential device; a second
case member that supports a second end portion of the output shaft
of the electric motor, the input shaft, an output shaft mounted
with the output member of the friction type continuously variable
transmission device, and a second end portion of the differential
case of the differential device; and a partition that supports
respective second end portions of the input member and the output
member of the friction type continuously variable transmission
device, wherein the first case member and the second case member
are connected, and the partition divides the first space and the
second space in an oil-tight manner.
14. The hybrid drive system according to claim 13, wherein the gear
transmission device includes an output gear that is provided on the
output shaft of the electric motor, and a differential ring gear
that forms an input portion of the differential device, wherein the
output gear and the differential ring gear disposed so as to
overlap in the axial direction.
15. The hybrid drive system according to claim 14, wherein the gear
transmission device includes an intermediate gear that is provided
on the input shaft and moves in accordance with the output gear,
and an output gear of the continuously variable transmission device
that is provided integrated with the output member of the friction
type continuously variable transmission device in a rotating
direction, wherein the intermediate gear and the output gear of the
continuously variable transmission device are disposed so as to
overlap the output gear and the differential ring gear in the axial
direction.
16. The hybrid drive system according to claim 15, wherein the
output gear and the intermediate gear are toothed gears, and power
is transmitted between the toothed gears through a toothed idler
gear.
17. The hybrid drive system according to claim 15, wherein the
output gear and the intermediate gear are sprockets, and power is
transmitted between the sprockets through a chain wound between the
sprockets.
18. The hybrid drive system according to claim 16, wherein the
toothed idler gear is disposed overlapping the electric motor in a
radial direction.
19. The hybrid drive system according to claim 18, wherein the
friction type continuously variable transmission device is a cone
ring type continuously variable transmission device, with the input
member and the output member formed from conical friction wheels
that are disposed such that axes of the friction wheels are
mutually parallel and large diameter portions and small diameter
portions of the friction wheels are respectively opposite each
other in the axial direction, and a ring provided interposed
between opposing inclined surfaces of the friction wheels and moved
in the axial direction to steplessly change a speed.
20. The hybrid drive system according to claim 19, wherein the
input shaft and the input member of the friction type continuously
variable transmission device are drivingly connected by a spline.
Description
INCORPORATION BY REFERENCE
[0001] The disclosure of Japanese Patent Application No.
2009-218120 filed on Sep. 18, 2009, including the specification,
drawings and abstract is incorporated herein by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a hybrid drive system in
which an engine and an electric motor drive a vehicle wheel, and
more specifically relates to a hybrid drive system that
integratedly incorporates a friction type continuously variable
transmission device, such as a cone ring continuously variable
transmission device.
DESCRIPTION OF THE RELATED ART
[0003] A conventional hybrid drive system in which an engine and an
electric motor drive a vehicle wheel is known that integratedly
incorporates one electric motor and a continuously variable
transmission device. A belt type continuously variable transmission
device is generally used as the continuously variable transmission
device for the hybrid drive system. The belt type continuously
variable transmission device is formed from a pair of pulleys and a
belt (or chain) made of metal that is wound around the pulleys, and
steplessly changes the speed by changing an effective diameter of
the pulleys.
[0004] Also known is a cone ring type continuously variable
transmission device that is formed from a pair of conical friction
wheels and a ring made of metal interposed between the friction
wheels. By moving the ring so as to change contacting portions
between the ring and the friction wheels, the speed is steplessly
changed (see Published Japanese Translation of PCT Application No.
2006-501425 (JP2006-501425A), for example).
SUMMARY OF THE INVENTION
[0005] In the conventional hybrid drive system, the electric motor
is arranged coaxial to an output shaft of the engine, and the belt
type continuously variable transmission device and a gear
transmission device formed from a plurality of gears are both
housed inside the same case and lubricated by the same lubricant
oil, e.g. ATF or the like.
[0006] The cone ring type continuously variable transmission device
may also be applied as a continuously variable transmission device
for the above hybrid drive system. In such case, the belt type
continuously variable transmission device can achieve a desired
transmission torque even in the presence of lubricant oil, and the
contact surface area between the pulleys and the metal belt is
relatively broad; however, the contact surface area between the
conical friction wheels and the metal ring is small and it is
difficult to achieve a desired transmission torque with lubricant
oil, so the use of specialized traction oil for achieving a
sufficient shear torque is preferable.
[0007] The belt type continuously variable transmission device also
has a relatively small axial dimension and the electric motor can
be arranged coaxial to the output shaft of the engine. However, the
friction type, that is, the cone ring type, continuously variable
transmission device is relatively long in the axial direction.
Therefore, the overall layout of the hybrid drive system, including
the arrangement of the electric motor, must be improved due to
restrictions in terms of automobile installation.
[0008] The present invention provides a hybrid drive system wherein
a friction type, that is, a cone ring type, continuously variable
transmission device is accommodated in an enclosed space defined
from a space that accommodates a gear transmission device and the
enclosed space is filled with traction oil, such that reliable
torque transmission and shifting can be achieved in a compact
structure.
[0009] The present invention is a hybrid drive system that
includes: an input shaft that moves in accordance with an engine; a
friction type continuously variable transmission device that
includes an input member that is drivingly connected to the input
shaft, and an output member, wherein a contact position between the
input member and the output member is changed, and a rotation of
the input member is steplessly changed in speed and transmitted to
the output member by a shear force of an oil film interposed at the
contact position; an electric motor that includes a dedicated
output shaft; a differential device; a gear transmission device
that forms at least part of a power transmission path that
transmits a rotation of the output shaft of the electric motor to
the differential device, and is structured from a meshing rotary
transmission mechanism; and a case that includes at least a first
space that is filled with traction oil and accommodates the
friction type continuously variable transmission device, and a
second space that is filled with lubricant oil and accommodates the
gear transmission device, wherein the first space and the second
space are divided in an oil-tight manner.
[0010] Note that, in the present invention, the term "gear" refers
to a meshing rotary transmission mechanism including toothed gears
and sprockets. Thus, the gear transmission device refers to a
transmission device that uses the meshing transmission mechanism.
Further note that the dedicated output shaft of the electric motor
refers to a shaft that is different from the input shaft, the input
member and the output member of the continuously variable
transmission device, and shafts of the differential device.
[0011] The output shaft of the electric motor is a first shaft. The
input shaft and the input member of the friction type continuously
variable transmission device disposed coaxially form a second
shaft. The output member of the friction type continuously variable
transmission device is a third shaft. Right and left axle shafts
connected to the differential device form a fourth shaft. The
first, second, third, and fourth shafts are arranged mutually
parallel and rotatably supported by the case, and gears that form
the gear transmission device are disposed on the first, second,
third, and fourth shafts. The electric motor and the continuously
variable transmission device are disposed on a first side in an
axial direction of the gear transmission device, and a second side
of the gear transmission device is connected to the engine.
[0012] The gear transmission device transmits a rotation of the
output shaft of the electric motor to the input member of the
friction type continuously variable transmission device, and
transmits a rotation of the output member to the differential
device.
[0013] The case includes: a first case member that supports a first
end portion of the output shaft of the electric motor, respective
first end portions of the input member and the output member of the
friction type continuously variable transmission device, and a
first end portion of a differential case of the differential
device; a second case member that supports a second end portion of
the output shaft of the electric motor, the input shaft, an output
shaft mounted with the output member of the friction type
continuously variable transmission device, and a second end portion
of the differential case of the differential device; and a
partition that supports respective second end portions of the input
member and the output member of the friction type continuously
variable transmission device, wherein the first case member and the
second case member are connected, and the partition divides the
first space and the second space in an oil-tight manner.
[0014] The gear transmission device includes an output gear that is
provided on the output shaft of the electric motor, and a
differential ring gear that forms an input portion of the
differential device, wherein the output gear and the differential
ring gear disposed so as to overlap in the axial direction.
[0015] The gear transmission device includes an intermediate gear
that is provided on the input shaft and moves in accordance with
the output gear, and an output gear of the continuously variable
transmission device that is provided integrated with the output
member of the friction type continuously variable transmission
device in a rotating direction, wherein the intermediate gear and
the output gear of the continuously variable transmission device
are disposed so as to overlap the output gear and the differential
ring gear in the axial direction.
[0016] Referring to FIG. 1, for example, the output gear and the
intermediate gear are toothed gears, and power is transmitted
between the toothed gears through a toothed idler gear.
[0017] Referring to FIG. 3, for example, the output gear and the
intermediate gear are sprockets, and power is transmitted between
the sprockets through a chain wound between the sprockets.
[0018] The toothed idler gear is disposed overlapping the electric
motor in a radial direction.
[0019] The friction type continuously variable transmission device
is a cone ring type continuously variable transmission device, with
the input member and the output member formed from conical friction
wheels that are disposed such that axes of the friction wheels are
mutually parallel and large diameter portions and small diameter
portions of the friction wheels are respectively opposite each
other in the axial direction, and a ring provided interposed
between opposing inclined surfaces of the friction wheels and moved
in the axial direction to steplessly change a speed.
[0020] The input shaft and the input member of the friction type
continuously variable transmission device are drivingly connected
by a spline.
[0021] According to a first aspect of the present invention, a case
includes a first space that is filled with traction oil and a
second space that is filled with lubricant oil, which are defined
in an oil-tight manner. In addition, a friction type continuously
variable, transmission device is housed in the first space, and a
gear transmission device is housed in the second space. Therefore,
an oil film of the traction oil, which has a large shear force
particularly in an extreme pressure condition, is present on
contact positions of the friction type continuously variable
transmission device, and torque is transmitted by the shear force.
A desired torque can thus be transmitted without early wear
occurring on friction transmission members such as an input member
and an output member, and swift and smooth shifting achieved.
Further, the gear transmission device can achieve smooth power
transmission with high transmission efficiency in the presence of
the lubricant oil without generating a large power loss.
[0022] Accordingly, the present invention is a hybrid drive system
capable of handling a large shift region spanning from start off to
high speeds and large torque fluctuations including acceleration,
deceleration, and slope roads. Power from an electric motor is
transmitted with high efficiency to a differential device, and a
rotation of an engine is steplessly changed in speed in a swift and
smooth manner and then transmitted to the differential device. A
control is performed such that the electric motor appropriately
assists while the engine achieves a swift and suitable output. It
is thus possible to provide a hybrid drive system that enables a
sufficient fuel economy improvement and carbon dioxide reduction
effect with a relatively inexpensive configuration that uses a
friction type continuously variable transmission device having a
simple constitution.
[0023] According to a second aspect of the present invention, an
input shaft that moves in accordance with the engine is disposed
coaxial with an input shaft of the continuously variable
transmission device, and the electric motor is disposed on a first
shaft different from a second shaft, whereby installation space for
the electric motor can be secured and the electric motor can be
employed with space remaining in the axial direction. In addition,
gears of the gear transmission device are respectively disposed on
the shafts. The electric motor and the continuously variable
transmission device are disposed on a first side in the axial
direction of the gear transmission device, and a second side of the
gear transmission device is connected to the engine. Therefore, the
overall layout of the hybrid drive system can be made compact and
mounted in a vehicle, even a small passenger vehicle with strict
space restrictions, while also using the friction type continuously
variable transmission device that is relatively long in the axial
direction.
[0024] According to a third aspect of the present invention, a
rotation of the electric motor is transmitted to the differential
device through the continuously variable transmission device.
Therefore, a lower capacity electric motor can be used.
[0025] According to fourth aspect of the present invention, the
case is formed by combining (dividing the case into) a first case
member and a second case member. A partition defines the first
space and the second space in an oil-tight manner. Therefore, the
shafts of the friction type continuously variable transmission
device and the like, which are subject to a relatively large thrust
force, are suitably supported, a case that surely defines the first
and second spaces in an oil-tight manner can be obtained with a
robust and compact configuration.
[0026] According to a fifth aspect of the present invention, an
output gear of the electric motor and a differential ring gear are
disposed so as to overlap in the axial direction. According to a
sixth aspect of the present invention, an intermediate gear and an
output gear of the continuously variable transmission device are
also disposed so as to overlap in the axial direction. Therefore,
the gear transmission device can be made more compact, particularly
in the axial direction. Thus, the overall hybrid drive system can
be made more compact, and the second space can be narrowed (reduced
in capacity) so as to decrease the amount of lubricant oil filling
the second space. At the same time, oil can be surely scooped up by
the differential ring gear and lubricant oil can be reliably
supplied to the other overlapping gears.
[0027] According to a seventh aspect of the present invention, a
toothed idler gear is provided. Therefore, a toothed gear with a
small diameter such as a pinion can be used for the motor output
gear, which increases a reduction ratio with the intermediate gear
and enables the use of a low-capacity, small electric motor. Thus,
the hybrid drive system can be made even more compact.
[0028] According to an eighth aspect of the present invention,
sprockets are used for the motor output gear and the intermediate
gear, and the rotation of the electric motor is transmitted through
a chain. Therefore, the degree of design freedom regarding an
inter-axial distance among the electric motor, the input shaft, and
the input member of the continuously variable transmission device
can be increased.
[0029] According to a ninth aspect of the present invention, the
toothed idler gear is disposed so as to overlap the electric motor
in a radial direction. Therefore, the input member of the
continuously variable transmission device and the electric motor
can be disposed closer together without interfering with a
shaft-supporting portion of a partition of an idler shaft. Thus,
the hybrid drive system can be made even more compact.
[0030] According to a tenth aspect of the present invention, the
friction type continuously variable transmission device is a cone
ring type continuously variable transmission device formed of two
conical friction wheels and a ring. Therefore, a desired gear ratio
can be obtained in a prescribed space (dimension), and the traction
oil effectively functions at friction contact-separation positions
in an extreme pressure condition. In addition, an input-side
friction wheel and an output-side friction wheel are disposed
mutually parallel, and shafts (a second shaft and a third shaft)
thereof are mounted with gears to configure the gear transmission
device compact. By narrowing the width of the second space, it is
possible to use the cone ring type continuously variable
transmission device that is relatively long in the axial direction,
and an overall sensible hybrid drive system can be achieved.
[0031] According to an eleventh aspect of the present invention,
vibrations of the input shaft that moves in accordance with the
engine are absorbed by a spline and not transmitted to the input
member of the continuously variable transmission device, so that
the input member can be supported with high precision. Thus, a
friction type continuously variable transmission device that
applies a large contact pressure with high precision to contact
positions to transmit engine power can be used in the hybrid drive
system, while also achieving smooth and reliable power transmission
and shifting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a front cross-sectional view that shows a hybrid
drive system to which the present invention is applied;
[0033] FIG. 2 is a side view of the hybrid drive system; and
[0034] FIG. 3 is a front cross-sectional view that shows a hybrid
drive system according to a partially modified embodiment.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0035] A hybrid drive system to which the present invention is
applied will be described below with reference to the attached
drawings. As shown in FIGS. 1 and 2, a hybrid drive system 1
includes an electric motor 2, a cone ring type continuously
variable transmission device (a friction type continuously variable
transmission device) 3, a differential device 5, an input shaft 6
that moves in accordance with an output shaft of an engine (not
shown), and a gear transmission device 7. The above devices and
shafts are housed in a case 11 that is formed by two case members,
that is, a case member 9 and a case member 10. Further, the case 11
includes a first space A and a second space B divided by a
partition 12 in an oil-tight manner.
[0036] The electric motor 2 includes a stator 2a fixed to the first
case member 9, and a rotor 2b provided on an output shaft 4. A
first end portion of the output shaft 4 is rotatably supported by
the first case member 9 through a bearing 13, and a second end
portion of the output shaft 4 is rotatably supported by the second
case member 10 through a bearing 15. An output gear 16 consisting
of a toothed gear (pinion) is formed on a second side of the output
shaft 4, and meshes with an intermediate gear (toothed gear) 19
provided on the input shaft 6 through a toothed idler gear 17.
[0037] A shaft 17a of the toothed idler gear 17 includes a first
end portion that is rotatably supported by the partition 12 through
a bearing 20, and a second end portion that is rotatably supported
by the second case member 10 through a bearing 21. The toothed
idler gear 17 is disposed partially overlapping with the electric
motor 2 in a radial direction when viewed from the side (that is,
when viewed in an axial direction). Specifically, the output gear
16 consisting of a pinion has a small diameter and the intermediate
gear 19 of the input shaft 6 has a large diameter, which increases
the gear ratio transmitted from the output gear (toothed gear) 16
to the intermediate gear 19 via the toothed idler gear 17 (obtains
a large reduction ratio). In addition, the bearing 20 that supports
the first end portion of the toothed idler gear shaft 17a can be
disposed closer to the output shaft 2a of the electric motor 2.
Thus, the cone ring type continuously variable transmission device
3 can be disposed closer to the electric motor 2 without a bearing
support portion of the partition 12 interfering with a support
portion of the continuously variable transmission device 3.
[0038] The cone ring type continuously variable transmission device
3 includes a conical friction wheel 22 serving as an input member,
a conical friction wheel 23 serving as an output member, and a ring
25 made of metal. The friction wheels 22, 23 are disposed so as to
be mutually parallel, and a small diameter portion and a large
diameter portion of the friction wheel 22 is disposed axially
opposite to a small diameter portion and a large diameter portion
of the friction wheel 23. The ring 25 is interposed between
opposing inclined surfaces of the friction wheels 22, 23 and
surrounds one of the friction wheels, for example, the input-side
friction wheel 22. A large thrust force acts on at least one of the
friction wheels, and therefore the ring 25 is interposed between
the inclined surfaces by a relatively large clamping force based on
this thrust force. Specifically, a cam mechanism is formed between
the output-side friction wheel 23 and an output shaft 23a on
surfaces opposed to each other in the axial direction. The thrust
force in a direction shown by an arrow D in the drawing is
generated in accordance with the transferred torque, and a large
clamping force is generated to act on the ring 25 between the
output-side friction wheel 23 and the input-side friction wheel 22
that is supported in a direction that counters the thrust
force.
[0039] The input-side friction wheel 22 includes a first end
portion (large diameter portion side) supported by the first case
member 9 through a roller bearing 26, and a second end portion
(small diameter portion side) supported by the partition 12 through
a tapered roller bearing 27. The output-side friction wheel 23
includes a first end portion (small diameter portion side)
supported by the first case member 9 through a roller bearing 29,
and a second end portion (large diameter portion side) supported by
the partition 12 through a roller (radial) bearing 30. The output
shaft 23a, which applies to the output-side friction wheel 23 the
thrust force acting in the direction shown by the arrow D as
described above, includes a second end supported by the second case
member 10 through a tapered roller bearing 31. An inner race of the
bearing 27 is interposed between a stepped portion and a nut 32 on
the second end portion of the input-side friction wheel 22, and the
thrust force that acts on the input-side friction wheel 22 through
the ring 25 in the direction shown by the arrow D from the
output-side friction wheel 23 is supported by the tapered roller
bearing 27. On the other hand, a reaction force of the thrust force
acting on the output-side friction wheel 23 acts on the output
shaft 23a in a direction opposite to the direction shown by the
arrow D, and the reaction force of the thrust force is supported by
the tapered roller bearing 31.
[0040] The ring 25 moves in the axial direction by an axial moving
mechanism, such as a ball screw, and changes the positions of
contact between the ring 25 and the input-side friction wheel 22
and between the ring 25 and the output-side friction wheel 23, so
as to steplessly change the speed by steplessly changing a rotation
ratio between the input member 22 and the output member 23. The
reaction force and the thrust force D corresponding to the
transferred torque are canceled out by the tapered roller bearings
27, 31 in the integrated case 11, and an equilibrant force such as
a hydraulic pressure is not required.
[0041] The differential device 5 includes a differential case 33,
and the differential case 33 includes a first end portion supported
by the first case member 9 through a bearing 35, and a second end
portion supported by the second case member 10 through a bearing
36. A shaft that is perpendicular to the axial direction is
attached to the inside of the differential case 33, and bevel gears
37, 37, which serve as differential carriers, are engaged with the
shaft. Left and right axle shafts 39l, 39r are supported by the
shaft, and bevel gears 40, 40 that mesh with the differential
carriers are fixed to the axle shafts. Further, a differential ring
gear (toothed gear) 41 having a large diameter is attached to the
outside of the differential case 33.
[0042] The output shaft 23a of the continuously variable
transmission device is formed with a toothed gear (pinion) 44, and
the toothed gear 44 meshes with the differential ring gear 41. The
motor output gear (pinion) 16, the toothed idler gear 17, the
intermediate gear (toothed gear) 19, the output gear (pinion) 44 of
the continuously variable transmission device, and the differential
ring gear (toothed gear) 41 constitute the gear transmission device
7. The motor output gear 16 and the differential ring gear 41 are
disposed overlapping each other in the axial direction, and the
intermediate gear 19 and the output gear 44 of the continuously
variable transmission device are disposed overlapping the motor
output gear 16 and the differential ring gear in the axial
direction. Note that, a gear 45, which is engaged with the output
shaft 23a of the continuously variable transmission device through
a spline, is a parking gear that locks the output shaft when a
shift lever is in a parking position. Further, the term "gear"
refers to a meshing rotary transmission mechanism including toothed
gears and sprockets. In this embodiment, however, the gear
transmission device refers to a toothed gear transmission device
that is formed by toothed gears only.
[0043] The input shaft 6 includes a first end that is engaged
(drivingly connected) with the input member 22 of the continuously
variable transmission device 3 through a spline S, and a second end
side of the input shaft 6 is linked with the output shaft of the
engine through a clutch (not shown) housed in a third space C
defined by the second case member 10, so that the input shaft 6
moves in accordance with the output shaft of the engine. The second
case member 10 is open and connected to the engine (not shown) on a
third space C side.
[0044] The gear transmission device 7 is housed in the second space
B. The second space B is a space between the third space C, and the
electric motor 2 and the first space A, in the axial direction. The
second space B is defined by the second case member 10 and the
partition 12. The shaft-supporting portions (27, 30) of the
partition 12 are placed in an oil-tight state by oil seals 47, 49,
respectively, and the shaft-supporting portions of the second case
member 10 and the first case member 9 are shaft-sealed by oil seals
50, 51, 52. The second space B is configured to be oil-tight, and
is filled with a predetermined amount of a lubricant oil such as
ATF. The first space A defined by the first case member 9 and the
partition 12 is similarly configured to be oil-tight, and is filled
with a predetermined amount of a traction oil having a shear force,
and a large shear force under an extreme pressure condition in
particular.
[0045] Referring to FIG. 2, the output shaft 4 of the electric
motor 2 is a first shaft I; the coaxially disposed input shaft 6
and the input member 22 of the continuously variable transmission
device form a second shaft II; the output member 23 of the
continuously variable transmission device and the output shaft 23a
thereof form a third shaft III; the left and right axle shafts 39l,
39r form a fourth shaft IV; and the toothed idler gear shaft 17a is
a fifth shaft V. These shafts are all arranged parallel and
supported by the case 11, and the gears (toothed gears) 16, 17, 19,
44, 41 of the gear transmission device 7 are disposed thereon. The
electric motor 2 and the continuously variable transmission device
3 are disposed on a first side in the axial direction of the gear
transmission device 7, and a second side of the gear transmission
device 7 is connected to the engine. Further, the electric motor 2
and the coaxial first shaft I are positioned the highest, while the
differential device 5 and the coaxial fourth shaft IV are
positioned the lowest. A portion of the ring gear 41 of the
differential device 5 lies within the lubricant oil pooled inside
the second space B.
[0046] Next, the operation of the hybrid drive system 1 as
described above will be explained. The hybrid drive system 1 is
connected to an internal combustion engine on the third space C
side of the case 11, and the output shaft of the engine is
connected to the input shaft 6 through a clutch. The power from the
engine is transmitted to the input shaft 6, and the rotation of the
input shaft 6 is transmitted to the input-side friction wheel 22 in
the cone ring type continuously variable transmission device 3
through the spline S. The power is further transmitted to the
output-side friction wheel 23 through the ring 25.
[0047] During this transmission, a large contact pressure acts
between the friction wheels 22, 23 and the ring 25 due to the
thrust force acting on the output-side friction wheel 23 in the
direction shown by the arrow D. Because the first space A is filled
with the traction oil, an oil film of the traction oil is formed
between the friction wheels and the ring, bringing about the
extreme pressure condition. In this condition, the traction oil has
a large shear force, and thus the power is transmitted between the
friction wheels and the ring by the shear force of the oil film.
This allows the transfer of a predetermined torque in a non-slip
manner without causing wear on the friction wheels and the ring,
even though the torque transfer is made through contact between
metal members. Moreover, the ring 25 moves in the axial direction
smoothly to change the positions of contact between both friction
wheels and the ring, whereby the speed is steplessly changed.
[0048] The rotation of the output-side friction wheel 23 whose
speed has been steplessly changed is transmitted to the
differential case 33 of the differential device 5 through the
output shaft 23a, the output gear 44, and the differential ring
gear 41. The power is then distributed to the left and right axle
shafts 39l, 39r so as to drive the vehicle wheels (front
wheels).
[0049] On the other hand, the power from the electric motor 2 is
transmitted to the input shaft 6 through the output gear 16, the
toothed idler gear 17, and the intermediate gear 19. Similar to the
description above, the speed of the rotation of the input shaft 6
is steplessly changed by the cone ring type continuously variable
transmission device 3, and the rotation is transmitted to the
differential device 5 through the output gear 44 and the
differential ring gear 41. The gear transmission device 7 formed by
the gears 16, 17, 19, 44, 41, 37, 40 is housed in the second space
B filled with the lubricant oil, and therefore the power is
smoothly transmitted through the lubricant oil when the gears mesh.
At such time, because the differential ring gear 41 (see FIG. 2)
disposed at a lower position in the second space B is formed of a
large diameter gear, the differential ring gear 41 scoops up the
lubricant oil so that a sufficient amount of lubricant oil is
reliably supplied to the other gears (toothed gears) 16, 17, 19,
44.
[0050] Various operation modes of the engine and the electric
motor, that is, operation modes as the hybrid drive system 1, may
be employed as necessary. As an example, when the vehicle starts
off, the clutch is disconnected and the engine stopped so that the
vehicle is started using only the torque from the electric motor 2.
Once the vehicle speed reaches a predetermined speed, the engine is
started and the vehicle is accelerated by the power from the engine
and the electric motor. When the vehicle speed becomes a cruising
speed, the electric motor goes into free rotation or is placed in a
regeneration mode, and the vehicle travels using only the power
from the engine. During deceleration or braking, the electric motor
regenerates to charge a battery. Further, the vehicle may be
started by the power from the engine using the clutch as a starting
clutch, with the torque from the motor used as an assisting
power.
[0051] The electric motor 2 is disposed on the first shaft, which
is different from the second shaft II formed of the input shaft 6
and the like, and also disposed at a position that axially overlaps
with the continuously variable transmission device 3. In addition,
the gear transmission device 7 is disposed in a relatively narrow
space among the continuously variable transmission device 3, the
electric motor 2, and the engine. Accordingly, even if the
continuously variable transmission device is a friction wheel type
continuously variable transmission device that requires relative
space in the axial direction, such as the cone ring type
continuously variable transmission device, the hybrid drive system
1 can be made compact overall and mounted even in the relatively
narrow installation space of a small passenger vehicle or the like,
for example. The gears 16, 17, 19, 44, 41 in particular overlap in
the axial direction and match the arrangement of the electric motor
2, which reduces the axial dimension. Further, the toothed idler
gear 17 overlaps the electric motor 2 in the radial direction.
Thus, the electric motor and the continuously variable transmission
device can be adjacently arranged to achieve a configuration with a
reduced radial dimension.
[0052] The toothed idler gear 17 is interposed between the motor
output gear 16 and the intermediate gear 19, which enables power
transmission at a large reduction ratio from the output gear 16 to
the intermediate gear 19. A required torque can thus be obtained
using the small motor 2, which contributes to a more compact
configuration and a reduction in cost.
[0053] Next, a partially modified embodiment will be explained with
reference to FIG. 3. Note that the present embodiment differs only
with regard to a form of transmission from the motor output gear to
the intermediate gear, and other portions are identical to the
previous embodiment. Like reference numerals are used for like
portions and will not be described again here. In the present
embodiment, a motor output gear 16' and an intermediate gear 19'
are formed of sprockets, and a silent chain 17' is wound between
the sprockets 16', 19'. The output gear 16' is in spline engagement
with the motor output shaft 4.
[0054] Therefore, the rotation of the electric motor 2 is
transmitted to the input shaft 6 through the output gear 16' formed
of a sprocket, the silent chain 17', and the intermediate gear 19'
formed of a sprocket. Note that, in place of the silent chain,
another chain such as a roller chain may be used. In the present
embodiment, the toothed idler gear used in the previous embodiment
is not required, and the shaft-supporting structure is
correspondingly simplified (the fifth shaft V is omitted). There is
an increased degree of layout design freedom regarding the electric
motor 2 and the continuously variable transmission device 3
(especially the input member 22), which is limited only by the
extent to which the diameter of the output gear sprocket 16' can be
reduced.
[0055] A friction type, that is, a cone ring type, continuously
variable transmission device is used as the continuously variable
transmission device in the embodiments described above. However,
the present invention is not limited to this, and another friction
type continuously variable transmission devices may be used,
including: a (ring cone type) continuously variable transmission
device that disposes a ring so as to encircle two conical friction
wheels; a continuously variable transmission device that interposes
a friction wheel between two conical friction wheels such that the
friction wheel contacts both friction wheels and moves in the axial
direction; a continuously variable transmission device that uses a
friction wheel with a spherical shape such as a toroidal shape; and
a continuously variable transmission device that is provided with
pulley-shaped friction wheels of which each is formed of a pair of
sheaves that biases input-side and output-side friction discs
toward each other so as to sandwich a belt, wherein the
pulley-shaped friction wheels move so as to change an inter-axial
distance between the friction discs.
[0056] The transmission path of the gear transmission device is
formed so as to pass through the continuously variable transmission
device. However, the transmission path is not limited to this, and
the rotation of the electric motor may be transmitted to the
differential ring gear 41 without passing through the continuously
variable transmission device. In such case, the intermediate gear
19 is rotatably supported by the input shaft 6, and the rotation of
the intermediate gear is directly transmitted or transmitted
through the idler gear to the output shaft 23a of the continuously
variable transmission device.
[0057] The present invention relates to a hybrid drive system that
incorporates an electric motor and a friction type continuously
variable transmission device such as a cone ring continuously
variable transmission device, and is utilized installed in an
automobile.
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