U.S. patent application number 12/216421 was filed with the patent office on 2009-01-15 for gear shift system for vehicle, control method and control device for automatic transmission.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. Invention is credited to Masato Kaigawa, Seiji Kuwahara.
Application Number | 20090018738 12/216421 |
Document ID | / |
Family ID | 40121740 |
Filed Date | 2009-01-15 |
United States Patent
Application |
20090018738 |
Kind Code |
A1 |
Kuwahara; Seiji ; et
al. |
January 15, 2009 |
Gear shift system for vehicle, control method and control device
for automatic transmission
Abstract
A parameter .alpha.(OUT) having an accelerator pedal position, a
vehicle speed and a drive force as components is set according to
information representing a driver's operation and information
representing running environment of a vehicle. A gear is set
according to the parameter .alpha.(OUT) and a map determining the
gear based on the accelerator pedal position, the vehicle speed and
the drive force. A gear shift line is defined such that a rate of
increase of the drive force with respect to the vehicle speed is
zero or more. A down-shift line is defined such that the drive
force decreases with increase in accelerator pedal position.
Down-shift after up-shift as well as the up-shift after the
down-shift are inhibited when both a condition that an amount of
change of the accelerator pedal position after last gear shift is
larger than a threshold and a condition that an amount of change of
the drive force after the last gear shift is larger than the
threshold are satisfied.
Inventors: |
Kuwahara; Seiji;
(Toyota-shi, JP) ; Kaigawa; Masato; (Toyota-shi,
JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 320850
ALEXANDRIA
VA
22320-4850
US
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
TOYOTA-SHI
JP
|
Family ID: |
40121740 |
Appl. No.: |
12/216421 |
Filed: |
July 3, 2008 |
Current U.S.
Class: |
701/65 |
Current CPC
Class: |
F16H 59/14 20130101;
F16H 59/44 20130101; Y10T 477/60 20150115; F16H 59/66 20130101;
Y10T 477/677 20150115; F16H 61/0213 20130101; Y10T 477/675
20150115; Y10T 477/647 20150115; Y10T 477/692 20150115; Y10T
477/693754 20150115; Y10T 477/6333 20150115; F16H 61/10 20130101;
Y10T 477/6934 20150115; Y10T 477/6422 20150115 |
Class at
Publication: |
701/65 |
International
Class: |
G06F 19/00 20060101
G06F019/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 10, 2007 |
JP |
2007-180575 |
Claims
1. A gear shift system for a vehicle comprising: an automatic
transmission; and a control unit, said control unit detecting a
vehicle speed, detecting first information representing a driver's
operation, detecting second information representing running
environment of said vehicle, setting a parameter having one of an
accelerator pedal position and a throttle position as well as the
vehicle speed and a drive force as components according to said
detected vehicle speed, said first information and said second
information, setting a gear ratio according to said parameter and a
map determining the gear ratio based on one of the accelerator
pedal position and the throttle position as well as the vehicle
speed and the drive force, and having a gear shift line defined
such that a rate of increase of the drive force with respect to the
vehicle speed is zero or more, and controlling said automatic
transmission to shift the gear according to said set gear
ratio.
2. A gear shift system for a vehicle comprising: an automatic
transmission; and a control unit, said control unit detecting a
vehicle speed, detecting first information representing a driver's
operation, detecting second information representing running
environment of said vehicle, setting a parameter having one of an
accelerator pedal position and a throttle position as well as the
vehicle speed and a drive force as components according to said
detected vehicle speed, said first information and said second
information, setting a gear ratio according to said parameter and a
map determining the gear ratio based on one of the accelerator
pedal position and the throttle position as well as the vehicle
speed and the drive force, and having a down-shift line defined
such that the drive force differs based on one of the accelerator
pedal position and the throttle position, and controlling said
automatic transmission to shift the gear according to said set gear
ratio.
3. The gear shift system for the vehicle according to claim 2,
wherein said down-shift line is defined such that the drive force
decreases with increase in one of the accelerator pedal position
and the throttle position.
4. A gear shift system for a vehicle comprising: an automatic
transmission; and a control unit, said control unit detecting a
vehicle speed, detecting first information representing a driver's
operation, detecting second information representing running
environment of said vehicle, setting a parameter having one of an
accelerator pedal position and a throttle position as well as the
vehicle speed and a drive force as components according to said
detected vehicle speed, said first information and said second
information, setting a gear ratio according to said parameter and a
map determining the gear ratio based on one of the accelerator
pedal position and the throttle position as well as the vehicle
speed and the drive force, controlling said automatic transmission
to shift the gear according to said set gear ratio, allowing
down-shift after up-shift as well as the up-shift after the
down-shift when at least one of a first condition that an amount of
change of one of the accelerator pedal position and the throttle
position after last change of the gear ratio is larger than a
threshold and a second condition that an amount of change of the
drive force after the last change of the gear ratio is larger than
the threshold is satisfied, and inhibiting the down-shift after the
up-shift as well as the up-shift after the down-shift when both
said first and second conditions are not satisfied.
5. A control method for an automatic transmission mounted on a
vehicle, comprising the steps of; detecting a vehicle speed;
detecting first information representing a driver's operation;
detecting second information representing running environment of
said vehicle; setting a parameter having one of an accelerator
pedal position and a throttle position as well as the vehicle speed
and a drive force as components according to said detected vehicle
speed, said first information and said second information; setting
a gear ratio according to said parameter and a map determining the
gear ratio based on one of the accelerator pedal position and the
throttle position as well as the vehicle speed and the drive force,
and having a gear shift line defined such that a rate of increase
of the drive force with respect to the vehicle speed is zero or
more; and controlling said automatic transmission to shift the gear
according to said set gear ratio.
6. A control method for an automatic transmission mounted on a
vehicle, comprising the steps of; detecting a vehicle speed;
detecting first information representing a driver's operation;
detecting second information representing running environment of
said vehicle; setting a parameter having one of an accelerator
pedal position and a throttle position as well as the vehicle speed
and a drive force as components according to said detected vehicle
speed, said first information and said second information; setting
a gear ratio according to said parameter and a map determining the
gear ratio based on one of the accelerator pedal position and the
throttle position as well as the vehicle speed and the drive force,
and having a down-shift line defined such that the drive force
differs based on one of the accelerator pedal position and the
throttle position; and controlling said automatic transmission to
shift the gear according to said set gear ratio.
7. The control method for the automatic transmission according to
claim 6, wherein said down-shift line is defined such that the
drive force decreases with increase in one of the accelerator pedal
position and the throttle position.
8. A control method for an automatic transmission mounted on a
vehicle, comprising the steps of; detecting a vehicle speed;
detecting first information representing a driver's operation;
detecting second information representing running environment of
said vehicle; setting a parameter having one of an accelerator
pedal position and a throttle position as well as the vehicle speed
and a drive force as components according to said detected vehicle
speed, said first information and said second information; setting
a gear ratio according to said parameter and a map determining the
gear ratio based on one of the accelerator pedal position and the
throttle position as well as the vehicle speed and the drive force;
controlling said automatic transmission to shift the gear according
to said set gear ratio; allowing down-shift after up-shift as well
as the up-shift after the down-shift when at least one of a first
condition that an amount of change of one of the accelerator pedal
position and the throttle position after last change of the gear
ratio is larger than a threshold and a second condition that an
amount of change of the drive force after the last change of the
gear ratio is larger than the threshold is satisfied; and
inhibiting the down-shift after the up-shift as well as the
up-shift after the down-shift when both said first and second
conditions are not satisfied.
9. A control device for an automatic transmission mounted on a
vehicle, comprising: means for detecting a vehicle speed; means for
detecting first information representing a driver's operation;
means for detecting second information representing running
environment of said vehicle; means for setting a parameter having
one of an accelerator pedal position and a throttle position as
well as the vehicle speed and a drive force as components according
to said detected vehicle speed, said first information and said
second information; means for setting a gear ratio according to
said parameter and a map determining the gear ratio based on one of
the accelerator pedal position and the throttle position as well as
the vehicle speed and the drive force, and having a gear shift line
defined such that a rate of increase of the drive force with
respect to the vehicle speed is zero or more; and means for
controlling said automatic transmission to shift the gear according
to said set gear ratio.
10. A control device for an automatic transmission mounted on a
vehicle, comprising: means for detecting a vehicle speed; means for
detecting first information representing a driver's operation;
means for detecting second information representing running
environment of said vehicle; means for setting a parameter having
one of an accelerator pedal position and a throttle position as
well as the vehicle speed and a drive force as components according
to said detected vehicle speed, said first information and said
second information; means for setting a gear ratio according to
said parameter and a map determining the gear ratio based on one of
the accelerator pedal position and the throttle position as well as
the vehicle speed and the drive force, and having a down-shift line
defined such that the drive force differs based on one of the
accelerator pedal position and the throttle position; and means for
controlling said automatic transmission to shift the gear according
to said set gear ratio.
11. The control device for the automatic transmission according to
claim 10, wherein said down-shift line is defined such that the
drive force decreases with increase in one of the accelerator pedal
position and the throttle position.
12. A control device for an automatic transmission mounted on a
vehicle, comprising: means for detecting a vehicle speed; means for
detecting first information representing a driver's operation;
means for detecting second information representing running
environment of said vehicle; means for setting a parameter having
one of an accelerator pedal position and a throttle position as
well as the vehicle speed and a drive force as components according
to said detected vehicle speed, said first information and said
second information; means for setting a gear ratio according to
said parameter and a map determining the gear ratio based on one of
the accelerator pedal position and the throttle position as well as
the vehicle speed and the drive force; means for controlling said
automatic transmission to shift the gear according to said set gear
ratio; means for allowing down-shift after up-shift as well as the
up-shift after the down-shift when at least one of a first
condition that an amount of change of one of the accelerator pedal
position and the throttle position after last change of the gear
ratio is larger than a threshold and a second condition that an
amount of change of the drive force after the last change of the
gear ratio is larger than the threshold is satisfied; and means for
inhibiting the down-shift after the up-shift as well as the
up-shift after the down-shift when both said first and second
conditions are not satisfied.
Description
[0001] This nonprovisional application is based on Japanese Patent
Application No. 2007-180575 filed on Jul. 10, 2007 with the Japan
Patent Office, the entire contents of which are hereby incorporated
by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a gear shift system for a
vehicle as well as a control method and a control device for an
automatic transmission, and particularly to a technique for
controlling a gear ratio of an automatic transmission.
[0004] 2. Description of the Background Art
[0005] A vehicle equipped with an automatic transmission has been
known. In general, a gear ratio of the automatic transmission is
determined according to an accelerator pedal position and a vehicle
speed. For setting the gear ratio more finely, it is preferable to
give consideration to running environment (a gradient of a road
surface, a curvature of the road surface, a friction coefficient of
the road surface, a degree of traffic jam and a type of the road)
of the vehicle and the like as well as an accelerator pedal
position and a vehicle speed.
[0006] Japanese Patent Laying-Open No. 9-126307 has disclosed a
gear shift control device of an automatic transmission including a
deceleration state determining unit determining a deceleration
state of a vehicle, a deceleration gear setting unit for setting
gears within gear selection ranges of different drive state
parameters, respectively, based on the plurality of drive state
parameters when deceleration determination is performed, and a gear
shift control unit performing gear shift control by determining, as
the gear, a lowest gear among the plurality of gears that are set
by the deceleration gear setting unit.
[0007] According to the gear shift control device described in the
above publication, the selection range of the gear for each
parameter is different from those for the other parameters in the
deceleration state. Therefore, such a structure is employed, e.g.,
that a second gear is selected for one parameter, but a third gear
is selected as the lowest gear for another parameter. Thereby, it
is possible to reduce the number of times that the second gear is
finally selected, and the excessive engine braking can be
avoided.
[0008] However, the gear shift control device disclosed in Japanese
Patent Laying-Open No. 9-126307 finally selects the gear that is
set based on one of the drive state parameters. Therefore, the gear
may not be selected in view of mutual effects of the plurality of
parameters. For example, the second gear may not be selected in the
case where it is appropriate to select the third gear when
consideration is given only to a road surface gradient, to select
the third gear when consideration is given to only an accelerator
pedal position and to select the second gear when consideration is
given to both the road surface gradient and the accelerator pedal
position. Therefore, there is a room for further improvement for
setting the gear, i.e., the gear ratio that is optimum in
connection with the drive state, running environment and the like
of the vehicle.
SUMMARY OF THE INVENTION
[0009] An object of the invention is to provide a gear shift system
of a vehicle as well as a control method and a control device of an
automatic transmission that can implement a more appropriate gear
ratio.
[0010] A gear shift system for a vehicle according to an aspect
comprises an automatic transmission; and a control unit. The
control unit detects a vehicle speed, detects first information
representing a driver's operation, detects second information
representing running environment of the vehicle, sets a parameter
having one of an accelerator pedal position and a throttle position
as well as the vehicle speed and a drive force as components
according to the detected vehicle speed, the first information and
the second information, sets a gear ratio according to the
parameter and a map determining the gear ratio based on one of the
accelerator pedal position and the throttle position as well as the
vehicle speed and the drive force, and having a gear shift line
defined such that a rate of increase of the drive force with
respect to the vehicle speed is zero or more, and controls the
automatic transmission to shift the gear according to the set gear
ratio.
[0011] This structure sets the parameter having one of the
accelerator pedal position and the throttle position as well as the
vehicle speed and the drive force as components according to the
vehicle speed, the first information representing the driver's
operation and the second information representing the running
environment of the vehicle. Thereby, the predetermined parameter
can be obtained in view of both the driver's operation and the
running environment of the vehicle. The gear ratio is set according
to the parameter and the map determining the gear ratio based on
one of the accelerator pedal position and the throttle position as
well as the vehicle speed and the drive force, and having the gear
shift line defined such that the rate of increase of the drive
force with respect to the vehicle speed is zero or more. The
automatic transmission is controlled to shift the gear according to
the gear ratio thus set. Thereby, the gear ratio can be set with
consideration given to the mutual effects of the driver's operation
and the running environment of the vehicle. Therefore, the gear
ratio of can be set more appropriately with respect to the driver's
operation and the running environment of the vehicle, as compared
with the case where the gear ratio is set with consideration given
to the driver's operation and the running environment of the
vehicle independently of each other. Further, in the map, the gear
shift line is defined such that the rate of increase of the drive
force with respect to the vehicle speed is zero or more. Thereby,
the locus of the parameter that is obtained when the drive force
decreases with increase in vehicle speed while the accelerator
pedal position is in a constant state can easily cross an up-shift
line. This facilitates setting of the vehicle speed at which the
up-shift is to be performed with the constant accelerator pedal
position or the throttle position. Consequently, the gear ratio
that is further appropriate with respect to the vehicle speed can
be set. Also, the down-shift line hardly crosses the locus of the
parameter that is obtained when the vehicle speed increases while
the drive force is substantially constant. Therefore, when the
vehicle speed is increasing with the drive force kept substantially
constant, it is difficult to perform unnecessary down-shift. This
facilitates maintaining of the gear ratio that is set appropriately
with respect to the vehicle speed. Consequently, the more
appropriate gear ratio can be implemented.
[0012] A gear shift system for a vehicle according to another
aspect comprises an automatic transmission; and a control unit. The
control unit detects a vehicle speed, detects first information
representing a driver's operation, detects second information
representing running environment of the vehicle, sets a parameter
having one of an accelerator pedal position and a throttle position
as well as the vehicle speed and a drive force as components
according to the detected vehicle speed, the first information and
the second information, sets a gear ratio according to the
parameter and a map determining the gear ratio based on one of the
accelerator pedal position and the throttle position as well as the
vehicle speed and the drive force, and having a down-shift line
defined such that the drive force differs based on one of the
accelerator pedal position and the throttle position, and controls
the automatic transmission to shift the gear according to the set
gear ratio.
[0013] This structure sets the parameter having one of the
accelerator pedal position and the throttle position as well as the
vehicle speed and the drive force as components according to the
vehicle speed, the first information representing the driver's
operation and the second information representing the running
environment of the vehicle. Thereby, the predetermined parameter
can be obtained in view of both the driver's operation and the
running environment of the vehicle. The gear ratio is set according
to the parameter and the map determining the gear ratio based on
one of the accelerator pedal position and the throttle position as
well as the vehicle speed and the drive force, and having the
down-shift line defined such that the drive force differs based on
one of the accelerator pedal position and the throttle position.
The automatic transmission is controlled to shift the gear
according to the gear ratio thus set. Thereby, the gear ratio can
be set with consideration given to the mutual effects of the
driver's operation and the running environment of the vehicle.
Therefore, the gear ratio of can be set more appropriately with
respect to the driver's operation and the running environment of
the vehicle, as compared with the case where the gear ratio is set
with consideration given to the driver's operation and the running
environment of the vehicle independently of each other. Further, in
the map, the down-shift line is defined such that the drive force
differs based on one of the accelerator pedal position and the
throttle position. For example, the down-shift line is defined such
that the drive force decreases with increase in one of the
accelerator pedal position and the throttle position. Thereby, the
down-shift can be performed owing to the increase in accelerator
pedal position even when the amount of increase of the drive force
is small with respect to the amount of increase of the accelerator
pedal position or the throttle position. Therefore, the more
appropriate gear ratio can be set with respect to the accelerator
pedal position or the throttle position. Consequently, the more
appropriate gear ratio can be implemented.
[0014] Preferably, the down-shift line is defined such that the
drive force decreases with increase in one of the accelerator pedal
position and the throttle position.
[0015] This structure can perform the down-shift owing to the
increase in accelerator pedal position even when the amount of
increase of the drive force is small with respect to the amount of
increase of the accelerator pedal position or the throttle
position. Therefore, the more appropriate gear ratio can be set
with respect to the accelerator pedal position and the throttle
position.
[0016] A gear shift system for a vehicle according to still another
aspect comprises an automatic transmission; and a control unit. The
control unit detects a vehicle speed, detects first information
representing a driver's operation, detects second information
representing running environment of the vehicle, sets a parameter
having one of an accelerator pedal position and a throttle position
as well as the vehicle speed and a drive force as components
according to the detected vehicle speed, the first information and
the second information, sets a gear ratio according to the
parameter and a map determining the gear ratio based on one of the
accelerator pedal position and the throttle position as well as the
vehicle speed and the drive force, controls the automatic
transmission to shift the gear according to the set gear ratio,
allows the down-shift after the up-shift as well as the up-shift
after the down-shift when at least one of a first condition that
the amount of change of one of the accelerator pedal position and
the throttle position after the last change of the gear ratio is
larger than a threshold and a second condition that an amount of
change of the drive force after the last change of the gear ratio
is larger than the threshold is satisfied, and inhibits the
down-shift after the up-shift as well as the up-shift after the
down-shift when both the first and second conditions are not
satisfied.
[0017] This structure sets the parameter having one of the
accelerator pedal position and the throttle position as well as the
vehicle speed and the drive force as components according to the
vehicle speed, the first information representing the driver's
operation and the second information representing the running
environment of the vehicle. Thereby, the predetermined parameter
can be obtained in view of both the driver's operation and the
running environment of the vehicle. The gear ratio is set according
to the parameter and the map determining the gear ratio based on
one of the accelerator pedal position and the throttle position as
well as the vehicle speed and the drive force. The automatic
transmission is controlled to shift the gear according to the gear
ratio thus set. Thereby, the gear ratio can be set with
consideration given to the mutual effects of the driver's operation
and the running environment of the vehicle. Therefore, the gear
ratio of can be set more appropriately with respect to the driver's
operation and the running environment of the vehicle, as compared
with the case where the gear ratio is set with consideration given
to the driver's operation and the running environment of the
vehicle independently of each other. If an interval between the
up-shift line and the down-shift line is small in the map
determining the gear ratio, the up-shift and the down-shift may be
repeated frequently. In view of this, the structure allows the
down-shift after the up-shift as well as the up-shift after the
down-shift when the first condition that the amount of change of
one of the accelerator pedal position and the throttle position
after the last change of the gear ratio is larger than a threshold
or the second condition that the amount of change of the drive
force after the last change of the gear ratio is larger than the
threshold is satisfied. Also, the structure inhibits the down-shift
after the up-shift as well as the up-shift after the down-shift
when both the first and second conditions are not satisfied.
Thereby, the number of times of unnecessary gear shift can be
reduced. Therefore, the gear that is appropriately set can be
easily maintained. Consequently, the appropriate gear ratio can be
implemented.
[0018] The foregoing and other objects, features, aspects and
advantages of the present invention will become more apparent from
the following detailed description of the present invention when
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic view showing a structure of a
vehicle.
[0020] FIG. 2 is a functional block diagram of an ECU in a first
embodiment of the invention.
[0021] FIG. 3 is a diagram (first) illustrating a manner of
mediating parameters.
[0022] FIG. 4 shows a parameter .alpha.(OUT).
[0023] FIG. 5 is a diagram (first) showing a shift map.
[0024] FIG. 6 is a diagram (first) showing gear shift lines in a
shift map in the first embodiment of the invention.
[0025] FIG. 7 is a diagram (second) showing the shift map.
[0026] FIG. 8 is a flowchart showing a control structure of a
program executed by the ECU in the first embodiment of the
invention.
[0027] FIG. 9 shows gear shift lines having portions in which a
drive force lowers with increase in vehicle speed.
[0028] FIG. 10 is a diagram (second) showing the gear shift lines
in the shift map in the first embodiment of the invention.
[0029] FIG. 11 is a diagram (second) showing the manner of
mediating the parameters.
[0030] FIG. 12 is a diagram (third) showing the manner of mediating
the parameters.
[0031] FIG. 13 shows a relationship between an accelerator pedal
position and the drive force.
[0032] FIG. 14 is a diagram (first) showing gear shift lines in a
shift map in a second embodiment of the invention.
[0033] FIG. 15 is a diagram (second) showing the gear shift lines
in the shift map in the second embodiment of the invention.
[0034] FIG. 16 is a functional block diagram of an ECU in a third
embodiment of the invention.
[0035] FIG. 17 is a flowchart showing a control structure of a
program executed by the ECU in the third embodiment of the
invention.
[0036] FIG. 18 is a diagram showing gear shift lines in a shift map
in the third embodiment of the invention.
[0037] FIG. 19 is a timing chart showing changes of the drive
force, the gear and the accelerator pedal position.
[0038] FIG. 20 is a timing chart (first) showing changes of the
drive force and the gear.
[0039] FIG. 21 is a timing chart (second) showing changes of the
drive force and the gear.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
[0040] A vehicle equipped with a control device according to the
first embodiment of the present invention will be described with
reference to FIG. 1. The vehicle is an FF (Front engine Front
drive) vehicle. It is noted that the vehicle may be a vehicle such
as a FR (Front engine Rear drive) vehicle other than the FF
vehicle.
[0041] The vehicle includes an engine 1000, a torque converter
2000, an automatic transmission 3000, a differential gear 4000, a
drive shaft 5000, front wheels 6000 and an ECU (Electronic Control
Unit) 7000.
[0042] Engine 1000 is an internal combustion engine that burns a
mixture consisting of fuel injected from an injector (not shown)
and air, inside a combustion chamber of a cylinder. A piston in the
cylinder is pushed down by the combustion, whereby a crankshaft is
rotated. An amount of fuel injected from the injector is determined
in accordance with an amount of air taken into engine 100 such that
a desired air-fuel ratio (for example, stoichiometric air-fuel
ratio) is attained.
[0043] Automatic transmission 3000 is coupled to engine 1000 with
torque converter 2000 being interposed. Therefore, an output shaft
revolution speed of torque converter 2000 (a turbine speed NT) is
equal to an input shaft revolution speed of automatic transmission
3000.
[0044] Automatic transmission 3000 is an automatic transmission
having a planetary gear unit. Automatic transmission 3000 converts
the revolution speed of the crankshaft to a desired revolution
speed for speed change by implementing a desired gear. Instead of
the automatic transmission implementing the gear, a CVT
(Continuously Variable Transmission) that continuously varies a
gear ratio may be mounted. Alternatively, an automatic transmission
including constant mesh gears shifted by means of a hydraulic
actuator may be mounted.
[0045] An output gear of automatic transmission 3000 meshes with
differential gear 4000. Drive shaft 5000 is coupled to differential
gear 4000 by spline-fitting or the like. A motive power is
transmitted to left and right front wheels 6000 via drive shaft
5000.
[0046] Wheel speed sensors 8002, a position sensor 8006 of a shift
lever 8004, an accelerator pedal position sensor 8010 of an
accelerator pedal 8008, a stroke sensor 8014 of a brake pedal 8012,
a throttle position sensor 8018 of an electronic throttle valve
8016, an engine speed sensor 8020, an input shaft speed sensor 8022
and an output shaft speed sensor 8024 are connected to ECU 7000 via
a harness and the like. Further, a navigation system 9000 is
connected to ECU 7000 via a harness and the like.
[0047] Wheel speed sensors 8002 detect the wheel speeds of the four
wheels of the vehicle, respectively, and transmit signals
representing the detected results to ECU 7000. ECU 7000 calculates
a friction coefficient .mu. of a road surface according to a map
using a speed difference between the wheels and others. The
friction coefficient .mu. of the road surface can be calculated in
a manner utilizing a well-known technology, and therefore
description thereof is not repeated.
[0048] The position of shift lever 8004 is detected by position
sensor 8006, and a signal representing the detected result is
transmitted to ECU 7000. A gear of automatic transmission 3000 is
automatically implemented corresponding to the position of shift
lever 8004. Additionally, such a configuration may be employed that
the driver can select a manual shift mode for arbitrarily selecting
a gear according to the driver's operation.
[0049] Accelerator pedal position sensor 8010 detects the position
(press-down degree) of accelerator pedal 8008 operated by the
driver, and transmits a signal representing the detected result to
ECU 7000. Stroke sensor 8014 detects the stroke amount of brake
pedal 8012 operated by the driver, and transmits a signal
representing the detected result to ECU 7000.
[0050] Throttle position sensor 8018 detects the position (degree
of throttle opening) of electronic throttle valve 8016 of which
position is adjusted by the actuator, and transmits a signal
representing the detected result to ECU 7000. Electronic throttle
valve 8016 regulates the amount of air (output of engine 1000)
taken into engine 1000. The amount of air taken into engine 1000
increases with the degree of throttle opening. Thus, the throttle
position or the degree of throttle opening can be used as a value
representing the output of engine 1000. The amount of air may be
regulated in accordance with a lift amount or an angle of action of
an intake valve (not shown) provided in the cylinder. Here, the
amount of air increases with the lift amount and/or the angle of
action.
[0051] Engine speed sensor 8020 detects a speed (engine revolution
speed NE) of the output shaft (crankshaft) of engine 1000, and
transmits a signal representing the detected result to ECU 7000.
Input shaft speed sensor 8022 detects an input shaft revolution
speed NI (turbine speed NT) of automatic transmission 3000, and
transmits a signal representing the detected result to ECU
7000.
[0052] Output shaft speed sensor 8024 detects an output shaft
revolution speed NO of automatic transmission 3000, and transmits a
signal representing the detected result to ECU 7000. ECU 7000
detects the vehicle speed based on output shaft revolution speed
NO, a radius of the wheel and the like. The vehicle speed can be
detected in a manner utilizing a well-known technology, and
therefore description thereof is not repeated. Output shaft
revolution speed NO may be used instead of the vehicle speed, as it
is.
[0053] Navigation system 9000 detects the position of the vehicle
by a GPS (Global Positioning System). Also, navigation system 9000
stores information representing a part of running environment of
the vehicle such as gradients of road surfaces, curvatures of road
surfaces, types of roads (freeways or general roads) and the like.
To ECU 7000, navigation system 9000 transmits the information
representing the surface gradient, surface curvature and type of
the road on which the vehicle is currently running.
[0054] Navigation system 9000 receives VICS (Vehicle Information
and Communication System) information representing a part of the
current running environment of the vehicle. As the VICS
information, navigation system 9000 receives a length (or degree)
of traffic jam and others. Navigation system 9000 transfers the
received VICS information to ECU 7000.
[0055] ECU 7000 controls equipment such that the vehicle is in a
desired running state, based on signals sent from the foregoing
sensors and the like as well as a map stored in an ROM (Read Only
Memory), a program stored therein and the information transmitted
from navigation system 9000. ECU 7000 may be formed of a plurality
of divided ECUs.
[0056] In the present embodiment, when shift lever 8004 is in a D
(drive) position and thereby a D (drive) range is selected as the
shift range in automatic transmission 3000, ECU 7000 controls
automatic transmission 3000 to implement one of the first to sixth
gears. Since one of the first to sixth gears is implemented,
automatic transmission 3000 can transmit a drive force to front
wheels 6000. It is noted that the number of gears to be implemented
is not limited to six, and may be seven or eight.
[0057] In this embodiment, a target value of the drive force of the
vehicle is determined according to the accelerator pedal position,
the stroke amount of the brake pedal and the running environment of
the vehicle. For determining the target value of the drive force of
the vehicle, consideration is also given to the drive force
required by VSC (Vehicle Stability Control) for stabilizing
behaviors of the vehicle, TRC (TRaction Control) for suppressing
skids of the wheels, cruise control for keeping a set vehicle speed
and the like. The throttle position and the like are determined to
implement the target value of the determined drive force.
[0058] Referring to FIG. 2, the function of ECU 7000 will be
described below. The following function of ECU 7000 may be
implemented by either hardware or software.
[0059] ECU 7000 includes a vehicle speed detecting unit 7002, an
operation detecting unit 7010, a running environment detecting unit
7020, a first setting unit 7031, a second setting unit 7032, a
third setting unit 7040, a gear setting unit 7050 and a control
unit 7060.
[0060] Vehicle speed detecting unit 7002 detects the vehicle speed
based on output shaft revolution speed NO of automatic transmission
3000 detected by output shaft speed sensor 8024.
[0061] Operation detecting unit 7010 detects information
representing the operation of the driver. More specifically, it
detects the accelerator pedal position based on the signal provided
from accelerator pedal position sensor 8010. Also, operation
detecting unit 7010 detects the stroke amount of brake pedal 8012
based on the signal transmitted from stroke sensor 8014. The
information representing the driver's operation is not restricted
to the above.
[0062] Running environment detecting unit 7020 detects the
information representing the running environment of the vehicle.
More specifically, running environment detecting unit 7020 detects
the road surface gradient, the road surface curvature, the road
type and the length (degree) of traffic jam based on the signals
transmitted from navigation system 9000. Further, running
environment detecting unit 7020 calculates friction coefficient
.mu. of the road surface based on the signal transmitted from wheel
speed sensors 8002. The information representing the running
environment of the vehicle is not restricted to the above.
[0063] First setting unit 7031 sets a parameter that has the
accelerator pedal position and the drive force as components,
according to the information representing the driver's operation.
More specifically, first setting unit 7031 detects the drive force
(target drive force) of the vehicle from the accelerator pedal
position according to the map that is prepared in advance. The
accelerator pedal position thus detected is used as it is. Thereby,
the parameter (vector) according to the detected accelerator pedal
position is set as represented by alternate long and short dash
line in FIG. 3.
[0064] Also, the parameter that has the accelerator pedal position
and the drive force according to the stroke amount of brake pedal
8012 as the components is set according to the predetermined map as
represented by alternate long and two short dashes line. It is
noted that the detected accelerator pedal position may be used as
it is.
[0065] First setting unit 7031 provides a parameter .alpha.(1)
obtained by mediating the two parameters obtained from the
accelerator pedal position and the stroke amount. For example, it
outputs a parameter prepared by collecting the maximum values of
respective components of the two parameters as represented by solid
line in FIG. 3. The manner of mediating the parameters is not
restricted to the above.
[0066] Second setting unit 7032 sets the parameter that has the
accelerator pedal position and the drive force as components,
according to the information representing the environment in which
the vehicle runs. More specifically, second setting unit 7032 sets
the parameter (vector) that has the accelerator pedal position and
the drive force corresponding to each of the road surface gradient,
the road surface curvature, the road type, the length of traffic
jam and friction coefficient .mu. of the road surface, according to
the map that is prepared in advance. Second setting unit 7032
outputs a parameter .alpha.(2) obtained by mediating these
parameters. For example, it outputs the parameter obtained by
collecting the maximum values of the respective components of the
plurality of obtained parameters.
[0067] The detected accelerator pedal position may be used as it
is. Also, consideration may be given to the drive force that is set
by the VSC, TRC, cruise control and the like.
[0068] Third setting unit 7040 sets one parameter .alpha.(OUT)
obtaining by mediating parameters .alpha.(1) and .alpha.(2)
provided from first and second setting units 7031 and 7032,
respectively. For example, as shown in FIG. 4, third setting unit
7040 sets parameter .alpha.(OUT) by collecting the maximum values
of the respective components of parameters .alpha.(1) and
.alpha.(2). The manner of mediating the parameters is not
restricted to the above.
[0069] Each parameter thus set includes the accelerator pedal
position and the drive force as well as the vehicle speed as the
components. Each parameter includes the vehicle speed detected by
vehicle speed detecting unit 7002 as the component, as it is.
[0070] Gear setting unit 7050 sets the gear, i.e., the gear ratio
corresponding to parameter .alpha.(OUT) set by third setting unit
7040. As shown in FIG. 5, the gear is set according to a shift map
using the accelerator pedal position, the drive force and the
vehicle speed. A gear shift line represented by a solid line in
FIG. 5 is an up-shift line. A gear shift line represented by an
alternate long and short dash line in FIG. 5 is a down-shift
line.
[0071] The manner of setting the gear by using the gear shift lines
(up- and down-shift lines) in the shift map can be implemented by
utilizing a well-known technology, and therefore description
thereof is not repeated.
[0072] The shift map is determined for each type of vehicle.
Therefore, the gear shift characteristics can be changed by
changing only the shift map. The gear shift line defined in the
shift map continuously changes according to changes in accelerator
pedal position. The gear shift lines may be set at intervals that
are predetermined in the direction of change of the accelerator
pedal position, and a gear shift line at an accelerator pedal
position between these lines may be obtained by linear
interpolation.
[0073] In the shift map, as shown in FIG. 6, the gear shift lines
are defined such that an increasing rate of the drive force with
respect to the vehicle speed is zero or more. Thus, the gear shift
lines are defined such that the drive force increases with the
vehicle speed. In other words, the gear shift lines are defined to
extend toward the upper right.
[0074] Control unit 7060 controls automatic transmission 3000 to
shift the gear according to the set gear. More specifically,
automatic transmission 3000 is controlled to implement the gear
that is set by gear setting unit 7050.
[0075] When automatic transmission 3000 is a CVT, the gear ratio
may be set by the gear shift line as shown in FIG. 7 instead of
setting the gear by the gear shift line.
[0076] Referring to FIG. 8, description will now be given on the
control structure of the program executed by ECU 7000 that is the
control device according to the embodiment. Execution of the
program described below is repeated at predetermined cycles. The
program to be executed by ECU 7000 may be stored on CDs (Compact
Discs), DVDs (Digital Versatile Discs) and the like for
distribution on the market.
[0077] In step (which will be abbreviated as "S" hereinafter) 100,
ECU 7000 detects the vehicle speed based on output shaft revolution
speed NO of automatic transmission 3000 that is detected by output
shaft speed sensor 8024.
[0078] In S102, ECU 7000 detects the information representing the
driver's operation. Thus, it detects the accelerator pedal position
based on the signal transmitted from accelerator pedal position
sensor 8010. Further, it detects the stroke amount of brake pedal
8012 based on the signal transmitted from stroke sensor 8014. In
S104, ECU 7000 sets the parameter having the accelerator pedal
position and the drive force according to the information
representing the driver's operation.
[0079] In S106, ECU 7000 detects the information representing the
running environment of the vehicle. More specifically, it detects
the road surface gradient, the road surface curvature, the road
type and the length (degree) of traffic jam based on the signals
transmitted from navigation system 9000. Also, ECU 7000 detects
friction coefficient .mu. of the road surface based on the signal
transmitted from wheel speed sensor 8002. In S108, ECU 7000 sets
the parameter having the accelerator pedal position and the drive
force as components according to the information representing the
running environment of the vehicle.
[0080] In S110, ECU 7000 sets one parameter .alpha.(OUT) by
mediating parameter .alpha.(1) obtained from the information
representing the driver's operation and parameter .alpha.(2)
obtained from the information representing the running environment
of the vehicle.
[0081] In S112, ECU 7000 sets the gear according to parameter
.alpha.(OUT) thus set according to the shift map. In S114, ECU 7000
controls automatic transmission 3000 to shift the gear according to
the gear thus set.
[0082] Description will now be given on the operation of ECU 7000
based on the foregoing structure and the flowchart.
[0083] During the running of the vehicle, the vehicle speed is
detected (S100). Further, the information representing the driver's
operation, i.e., the accelerator pedal position and the stroke
amount of brake pedal 8012 are detected (S102). According to the
information representing the driver's operation, the parameter
having the accelerator pedal position and the drive force as
components is set (S104).
[0084] In addition to the information representing the driver's
operation, the information representing the running environment of
the vehicle, i.e., the road surface gradient, the road surface
curvature, friction coefficient .mu. of the road surface, the road
type, the length (degree) of traffic jam are detected (S106).
Similarly to the information representing the driver's operation,
the parameter having the accelerator pedal position and the drive
force as components is set according to the information
representing the running environment of the vehicle (S108).
Thereby, the driver's operation and the running environment of the
vehicle can be represented with unified parameters having the same
kinds of components.
[0085] One parameter .alpha.(OUT) is set by mediating parameter
.alpha.(1) obtained from the information representing the driver's
operation and parameter .alpha.(2) obtained from the information
representing the running environment of the vehicle (S110).
Thereby, parameter .alpha.(OUT) that is determined in view of both
the driver's operation and the running environment of the
vehicle.
[0086] The gear corresponding to parameter .alpha.(OUT) is set
according to the shift map (S112). Automatic transmission 3000 is
controlled to shift the gear according to the gear thus set (S114).
Thereby, the gear can be set in view of the mutual effects of both
the driver's operation and the running environment of the vehicle.
Therefore, the gear can be set appropriately for the driver's
operation and the running environment of the vehicle, as compared
with the case where the gear ratio is set with consideration given
to the driver's operation and the running environment of the
vehicle independently of each other.
[0087] In the shift map, the gear shift lines are defined such that
an increase rate of the drive force with respect to the vehicle
speed is zero or more. The reason for this is as follows.
[0088] When the accelerator pedal position is constant, the drive
force decreases with increase in vehicle speed, and then becomes
substantially constant as shown in FIG. 9. Therefore, as shown in
FIG. 9, in the case where the up-shift line is defined to lower the
drive force with increase in vehicle speed near V(A), a locus of
the parameter (drive force) obtained when the accelerator pedal
position is constant hardly crosses the up-shift line. Therefore,
it is difficult to set the vehicle speed at which the up-shift is
performed when the accelerator pedal position is constant.
[0089] In the case where a down-shift line is defined to lower the
drive force with increase in vehicle speed near V(B), the locus of
the parameter may cross the down-shift line when the vehicle speed
increases while the drive force is substantially constant. Thus,
unnecessary down-shift may be performed as the vehicle speed
increases, in spite of the fact that the increase in drive force is
not required.
[0090] Accordingly, for facilitating setting of the vehicle speed
at which the up-shift is performed and reducing the number of times
of unnecessary down-shift, the gear shift line is set such that the
increase rate of the drive force with respect to the vehicle speed
may be zero or more in the shift map.
[0091] Thereby, as shown in FIG. 10, the locus of the parameter
obtained with the accelerator pedal position kept in a constant
state can easily cross the up-shift line. Therefore, it becomes
easy to set the vehicle speed at which the up-shift is to be
performed with the accelerator pedal position kept in a constant
state. Consequently, the gear ratio can be set finely.
[0092] Further, as shown in FIG. 10, a locus of the parameter
obtained when the vehicle speed increases with the drive force kept
substantially constant hardly crosses the down-shift line.
Therefore, when the vehicle speed is increasing with the drive
force kept substantially constant, it is difficult to perform
unnecessary down-shift.
[0093] In the control device according to the embodiment, as
described above, the parameter .alpha.(OUT) having the vehicle
speed, the accelerator pedal position and the drive force as the
components is set according to the vehicle speed, the information
representing the driver's operation and the running environment of
the vehicle. Thereby, parameter .alpha.(OUT) determined in view of
both the driver's operation and the running environment of the
vehicle can be obtained. The gear according to this parameter
.alpha.(OUT) is set according to the shift map. The automatic
transmission is controlled to shift the gear according to the set
gear. Thereby, the gear can be set in view of the mutual effects of
the driver's operation and the running environment of the vehicle.
Therefore, the gears of the automatic transmission can be set
appropriately for the driver's operation and the running
environment of the vehicle, as compared with the case where the
gear ratio is set with consideration given to the driver's
operation and the running environment of the vehicle independently
of each other. In the shift map, the gear shift line is defined
such that the increase rate of the drive force with respect to the
vehicle speed may be zero or more. Thereby, the locus of the
parameter obtained when the drive force lowers according to
increase in vehicle speed while the accelerator pedal position is
constant can easily cross the up-shift line. This facilitates
setting of the vehicle speed at which the up-shift is to be
performed with the constant accelerator pedal position.
Consequently, the gear ratio that is further appropriate with
respect to the vehicle speed can be set. Further, the locus of the
parameter obtained when the vehicle speed increases with a
substantially constant drive force hardly crosses the down-shift
line. Therefore, when the vehicle speed is increasing while the
drive force is constant, it is difficult to perform unnecessary
down-shift. Thus, the gear ratio that is set appropriately with
respect to the vehicle speed can be maintained easily.
Consequently, the further appropriate gear ratio can be
implemented.
[0094] The parameter having the components other than the vehicle
speed, the accelerator pedal position and the drive force may be
set in addition to them.
[0095] Instead of the manner of mediating the plurality of
parameters by collecting the maximum values of the respective
components of the parameters, the parameters may be mediated by
adding each type of components of the plurality of parameters
independently of the other types, as represented by solid line in
FIG. 11. Thus, the parameters may be mediated by adding the
vectors. Further, as shown in FIG. 12, the mediation of the
parameters may be performed by collecting the minimum values of the
respective components of the plurality of parameters. Further, the
parameters may be represented as coordinates.
[0096] Further, the throttle position may be used instead of the
accelerator pedal position because the accelerator pedal position
is substantially proportional to the throttle position.
Second Embodiment
[0097] A second embodiment of the invention will now be described.
This embodiment differs from the foregoing first embodiment in that
the down-shift line is defined to decrease the drive force with
increase in accelerator pedal position. Structures other than the
above as well as the functions thereof are the same as those of the
foregoing first embodiment. Therefore, description thereof is not
repeated.
[0098] As shown in FIG. 13, the rate of change of the vehicle's
drive force decreases with the accelerator pedal position
increases. When the accelerator pedal position is in a region (A)
where the accelerator pedal position is equal to or lower than
PA(0), the rate of change of the vehicle's drive force with respect
to the accelerator pedal position is equal to or higher than the
threshold. In a region (B) where the accelerator pedal position is
larger than PA(0), the rate of change of the vehicle's drive force
with respect to the accelerator pedal position is smaller than the
threshold. In FIG. 13, F(1) indicates a maximum value of the
vehicle's drive force. F(2) indicates a minimum value of the
vehicle's drive force in the region (B) where the increase rate of
the vehicle's drive force with respect to the accelerator pedal
position is smaller than the threshold.
[0099] In the region (A) where the rate of change of the vehicle's
drive force with respect to the accelerator pedal position is equal
to or higher than the threshold, the amount of change of the
vehicle's drive force with respect to the amount of change of the
accelerator pedal position is sufficiently large. Therefore, the
gear can be easily set according to the shift map using the drive
force.
[0100] Conversely, in the region (B) where the increase rate of the
vehicle's drive force with respect to the accelerator pedal
position is smaller than the threshold, the amount of change of the
vehicle's drive force with respect to the amount of change of the
accelerator pedal position is small. Therefore, it is difficult to
set the gear according to the shift map using the drive force.
[0101] In this embodiment, therefore, the down-shift line is
defined to lower the drive force with increase in accelerator pedal
position. The down-shift line will now be described. For the sake
of simplicity, the following description will be given on the case
where the vehicle speed is V(1), V(2) or (V3)
(V(1)<V(2)<V(3)).
[0102] In the region (B) where the increase rate of the vehicle's
drive force with respect to the accelerator pedal position is
smaller than the threshold, and particularly in a region where the
accelerator pedal position is PA(1) (PA(1)>PA(0)), the drive
force that defines the down-shift line when the vehicle speed is
V(1), V(2) or V(3) is smaller than maximum value F(1) of the
vehicle's drive force.
[0103] As shown in FIG. 15, in the region where the accelerator
pedal position is equal to or lower than PA(1), the drive force
that defines the down-shift line when the vehicle speed is V(1),
V(2) or V(3) is larger than the maximum value F(1) of the vehicle's
drive force.
[0104] Thereby, when the vehicle speed is V(1), V(2) or V(3), the
down-shift can be performed by increasing the accelerator pedal
position above PA(1). Therefore, even when the rate of change of
the drive force with respect to the accelerator pedal position is
small, the accelerator pedal position that implements the
down-shift can be easily set. Consequently, the gear can be set
appropriately with respect to the accelerator pedal position.
Third Embodiment
[0105] A third embodiment of the invention will now be described.
This embodiment differs from the foregoing first embodiment in that
the third embodiment inhibits the down-shift after the up-shift as
well as the up-shift after the down-shift when both the condition
that the amount of change of the accelerator pedal position after
the last gear shift (i.e., after the determination that the gear
shift is to be performed) is larger than a threshold and the
condition that the amount of change of the drive force after the
last gear shift is larger than a threshold are not satisfied.
Structures other than the above as well as the functions thereof
are the same as those of the foregoing first and second
embodiments. Therefore, description thereof is not repeated.
[0106] Referring to FIG. 16, the functions of ECU 7000 will be
described below. The same functions as those in the first
embodiment bear the same numbers. Accordingly, description thereof
is not repeated.
[0107] ECU 7000 further includes an allowing unit 7070 and an
inhibiting unit 7072. Allowing unit 7070 allows the down-shift
after the up-shift as well as the up-shift after the down-shift
when the condition that the amount of change of the accelerator
pedal position after the last gear shift (i.e., after the
determination that the gear shift is to be performed) or the
condition that the amount of change of the drive force after the
last gear shift is larger than the threshold is satisfied.
[0108] Inhibiting unit 7072 inhibits the down-shift after the
up-shift as well as the up-shift after the down-shift when neither
of the condition that the amount of change of the accelerator pedal
position after the last gear shift is larger than the threshold and
the condition that the amount of change of the drive force after
the last gear shift is larger than the threshold is satisfied.
[0109] In this embodiment, an absolute value of the difference
between the accelerator pedal position at the time of the last gear
shift (i.e., at the time of the determination that the change of
the gear is to be performed) and the present accelerator pedal
position is detected as the amount of change of the accelerator
pedal position after the last gear shift. Likewise, an absolute
value of the difference between the drive force at the time of the
last gear shift and the present drive force is detected as the
amount of change of the drive force.
[0110] Referring to FIG. 17, description will now be given on the
control structure of the program executed by ECU 7000 , i.e., the
control device according to this embodiment. Execution of the
program described below is repeated at predetermined cycles. The
same processing as that of the first embodiment already described
bears the same step number. Therefore, description thereof is not
repeated.
[0111] In S200, ECU 7000 determines whether the condition that the
amount of change of the accelerator pedal position after the last
gear shift is larger than the threshold or the condition that the
amount of change of the drive force after the last gear shift is
larger than the threshold is satisfied or not.
[0112] When the condition that the amount of change of the
accelerator pedal position after the last gear shift is larger than
the threshold or the condition that the amount of change of the
drive force after the last gear shift is larger than the threshold
is satisfied (YES in S200), the process proceeds to S202. Otherwise
(NO in S200), the process proceeds to S204.
[0113] In S202, ECU 7000 allows the down-shift after the up-shift
or the up-shift after the down-shift. In S204, ECU 7000 inhibits
the down-shift after the up-shift and the up-shift after the
down-shift (S204).
[0114] Based on the structures and flowcharts described above, ECU
7000 operates as follows.
[0115] As illustrated in portions surrounded by broken line in FIG.
18, the shift map may have portions in which a distance between the
up- and down-shift lines, i.e., a hysteresis is small. In the state
where the accelerator pedal position is larger, i.e., the rate of
change of the drive force with respect to the accelerator pedal
position is small, it is difficult to perform the up-shift and the
down-shift even when the hysteresis is small.
[0116] Conversely, during execution, e.g., of the cruise control
that maintains the vehicle speed already set by the driver when the
driver does not operate the accelerator pedal 8008, the drive force
(target drive force) of the vehicle may increase or decrease as
shown in FIG. 20. Therefore, the up-shift and the down-shift may be
repeated frequently.
[0117] Therefore, the down-shift after the up-shift as well as the
up-shift after the down-shift are inhibited (S204) when both the
condition that the amount of change of the accelerator pedal
position after the last gear shift is larger than the threshold and
the condition that the amount of change of the drive force after
the last gear shift is larger than the threshold are not satisfied
(NO in S200).
[0118] When the condition that the amount of change of the
accelerator pedal position after the last gear shift is larger than
the threshold or the condition that the amount of change of the
drive force after the last gear shift is larger than the threshold
is satisfied (YES in S200), the down-shift after the up-shift and
the up-shift after the down-shift are allowed (S202).
[0119] Thereby, the number of times of unnecessary gear shift can
be reduced. Therefore, the gear that is appropriately set can be
easily maintained. Consequently, the gear ratio of the automatic
transmission can be finely controlled.
[0120] Although the present invention has been described and
illustrated in detail, it is clearly understood that the same is by
way of illustration and example only and is not to be taken by way
of limitation, the scope of the present invention being interpreted
by the terms of the appended claims.
* * * * *