U.S. patent application number 09/737556 was filed with the patent office on 2001-08-16 for apparatus for controlling an automatic transmission.
This patent application is currently assigned to HONDA GIKEN KOGYO KABUSHIKI KAISHA. Invention is credited to Hagiwara, Kenji, Konnno, Kazuyuki, Morita, Yukio, Shimada, Takamichi.
Application Number | 20010014640 09/737556 |
Document ID | / |
Family ID | 18559669 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010014640 |
Kind Code |
A1 |
Morita, Yukio ; et
al. |
August 16, 2001 |
Apparatus for controlling an automatic transmission
Abstract
An automatic gear change controller, having a constant speed
travel mode, which can transmit torque to wheels of a vehicle
according to changes in the travel load of the vehicle even though
a gear shift mode is changed to the manual gear shift mode. When
the gear shift mode is set in the manual gear shift mode and the
travel mode is set in a constant speed travel mode, a constant
speed travel controller generates a downshift command signal. In
this case, when the accelerator pedal is depressed beyond a
predetermined amount, the gear shift stage of the automatic
transmission is downshifted.
Inventors: |
Morita, Yukio; (Wako-shi,
JP) ; Konnno, Kazuyuki; (Wako-shi, JP) ;
Hagiwara, Kenji; (Wako-shi, JP) ; Shimada,
Takamichi; (Wako-shi, JP) |
Correspondence
Address: |
ARENT FOX KINTNER PLOTKIN & KAHN, PLLC
Suite 600
1050 Connecticut Avenue, N.W.
Washington
DC
20036-5339
US
|
Assignee: |
HONDA GIKEN KOGYO KABUSHIKI
KAISHA
|
Family ID: |
18559669 |
Appl. No.: |
09/737556 |
Filed: |
December 18, 2000 |
Current U.S.
Class: |
477/121 ;
180/170 |
Current CPC
Class: |
B60W 30/143 20130101;
B60W 2710/0605 20130101; F16H 2059/0239 20130101; B60K 31/04
20130101; B60W 10/06 20130101; B60W 2710/1005 20130101; B60W 10/11
20130101; B60W 2540/10 20130101; F16H 59/0204 20130101 |
Class at
Publication: |
477/121 ;
180/170 |
International
Class: |
B60K 041/04; B60K
031/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 14, 2000 |
JP |
2000-35476 |
Claims
What is claimed is:
1. An apparatus for controlling an automatic transmission,
comprising: transmission driving means for determining a gear shift
stage of an automatic transmission which transmits rotational
torque of an internal combustion engine of a vehicle to drive
wheels of said vehicle in response to a gear change control signal;
gear change control means for selectively setting either of two
gear shift modes, an automatic gear shift mode to determine the
gear shift stage according to a travel speed of the vehicle, a
depressed amount of an accelerator pedal and engine throttle valve
opening, and a manual gear shift mode to determine the gear shift
stage corresponding to a shift position of a transmission operating
lever, and for determining control characteristics of said gear
change control signal according to a set gear shift mode; travel
mode selecting means for selecting whether a travel state of said
vehicle is to be in a constant speed travel mode corresponding to
manual operation; and constant speed travel control means for
transmitting a command signal for changing the gear shift stage to
said gear change control means so as to make said travel speed
substantially constant, and for transmitting a command signal for
changing the throttle valve opening to a throttle valve control
means when said gear shift mode is set in said automatic gear shift
mode and said travel mode is set in said constant speed travel
mode, wherein when said gear shift mode is set in said manual gear
shift mode and said travel mode is set in said constant speed
travel mode, said constant speed travel control means transmits a
downshift command signal and, when the accelerator pedal is
depressed beyond a predetermined amount, said gear change control
means shifts down the gear shift stage.
2. An apparatus for controlling automatic transmission according to
claim 1, wherein said gear change control means shifts up the gear
shift stage when the throttle valve opening designated by said
command signal for changing the throttle valve opening is less than
a predetermined value.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an apparatus for
controlling an automatic transmission of a vehicle and, more
particularly, to an apparatus for controlling an automatic
transmission which selectively sets either of two gear shift modes,
an automatic gear shift mode and a manual gear shift mode, and
controls the automatic transmission according to the set gear shift
mode.
[0003] 2. Description of the Related Art
[0004] An apparatus for controlling an automatic transmission of a
vehicle is disclosed in Japanese patent application laid-open No.
8-193656. The device has a gear change controller, which
selectively sets either of two gear shift modes, an automatic gear
shift mode and a manual gear shift mode. The device controls the
automatic transmission according to the set gear shift mode and a
constant speed travel controller controls the travel speed so as to
be substantially constant when the travel mode of a vehicle is set
in constant speed travel mode. With the gear shift mode being set
in the manual gear shift mode and the travel mode being set in a
constant speed travel mode, when the constant speed travel
controller gives a gear change command, the conventional automatic
gear change controller ignores the given gear change command and
maintains the previously set gear shift stage.
[0005] Such a conventional automatic gear change controller,
however, has a problem in maintaining a constant travel speed. That
is, even though the travel load of a vehicle is changed, for
example, when the road elevation changes from being level to an
uphill, no control is carried out for changing the gear shift
stage, causing difficulty in maintaining constant vehicle
speed.
OBJECT AND SUMMARY OF THE INVENTION
[0006] The present invention was developed in consideration of the
aforementioned problems. An object of the present invention is to
provide an automatic gear change controller which can maintain
constant travel speed with the travel mode being set in a constant
speed travel mode even though the gear shift mode is changed to the
manual gear shift mode or the travel load of a vehicle changes.
[0007] An apparatus for controlling an automatic transmission
according to the present invention comprises a transmission driving
means for determining the gear shift stage of an automatic
transmission which transmits rotational torque of an internal
combustion engine to drive wheels of a vehicle in response to a
gear change control signal; a gear change control means for
selectively setting either of two gear shift modes, an automatic
gear shift mode to determine the gear shift stage according to the
travel speed, the amount of depression of the accelerator pedal and
the throttle valve opening, and a manual gear shift mode to
determine the gear shift stage corresponding to a shift position of
the operating lever, and for determining the contents of said gear
change control signal according to the set gear shift mode; a
travel mode setting means for setting whether or not the travel
state of the vehicle is to be a constant speed travel mode
corresponding to manual operation; and a constant speed travel
control means for giving a command signal for changing the gear
shift stage to the gear change control means so as to make said
travel speed substantially constant, and for giving a command
signal for changing the valve opening to a throttle valve control
means when said gear shift mode is set in the automatic gear shift
mode and the travel mode is set in the constant speed travel mode,
characterized in that, when the gear shift mode is set in manual
gear shift mode and the travel mode is set in constant speed travel
mode, the constant speed travel control means gives a downshift
command signal and, when the accelerator pedal is depressed beyond
a predetermined amount, the gear change control means shifts down
the gear shift stage.
[0008] That is, according to the present invention, with the travel
mode being set to the constant speed travel mode, torque can be
transmitted to the wheels according to changes in the travel load
of a vehicle even though the gear shift mode is changed to manual
gear shift mode.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a block diagram showing an apparatus for
controlling an automatic transmission and an internal combustion
engine installed in a vehicle;
[0010] FIG. 2 is a flow chart showing a subroutine for
discriminating whether or not the travel state of a vehicle is in
constant speed travel mode;
[0011] FIG. 3 is a flow chart showing a subroutine for determining
the gear shift stage of an automatic transmission when the travel
state of a vehicle is in constant speed travel mode; and
[0012] FIG. 4 is a flow chart showing a subroutine for gear change
control carried out in step S24 in manual gear shift mode.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0013] Referring to the accompanying drawings, embodiments of the
present invention will be described below.
[0014] FIG. 1 shows an outline of an apparatus for controlling an
automatic transmission and the gear shift stage thereof.
[0015] An inlet pipe or intake manifold 12 of an internal
combustion engine 10 is provided with a throttle valve 14 for
controlling the volume of intake air sucked from the outside of a
vehicle. The throttle valve 14 is provided with a throttle valve
running gear (not shown) for switching and running the throttle
valve 14 in response to a throttle valve switching control signal
as described later. The throttle valve 14 is further provided with
a throttle valve opening sensor 16 for detecting the opening of the
throttle valve 14. The inlet pipe 12 is also provided with an
intake pipe pressure sensor for detecting the pressure of intake
air and an intake-air temperature sensor (not shown) for detecting
the temperature of intake air. The inlet pipe 12 is further
provided with a fuel injector (not shown) for injecting fuel. The
internal combustion engine 10 sucks a mixture of intake air and
fuel injected from the fuel injector and rotatively drives a
crankshaft (not shown) by burning the air-fuel mixture. The
internal combustion engine 10 is provided with a temperature sensor
18 for detecting the temperature of the internal combustion engine
10. In the vicinity of the crankshaft, a crank angle sensor 20 is
provided for detecting the angle of the crankshaft. The air-fuel
mixture burned in the internal combustion engine 10 is discharged
to an exhaust pipe or exhaust manifold (not shown) as exhaust
gases. The exhaust pipe is provided with an oxygen concentration
sensor (not shown) for detecting the concentration of oxygen in the
exhaust gases. In the vicinity of the internal combustion engine
10, an atmospheric pressure sensor (not shown) is also provided for
detecting atmospheric pressure.
[0016] A speed sensor 30 for detecting the speed of a vehicle is
provided in the vicinity of drive wheels (not shown) of the
vehicle. The device wheels are driven by rotational torque
transmitted from the internal combustion engine 10. The speed
sensor 30 gives an output signal corresponding to the detected
vehicle speed. Also provided in the interior of the vehicle are an
accelerator pedal 32, with which an operator controls the travel
speed of the vehicle, and an accelerator pedal sensor (not shown)
arranged near the accelerator pedal 32. The accelerator pedal
sensor detects the amount of depression of the accelerator pedal 32
which is depressed by the operator and gives an output signal
corresponding to the depressed amount.
[0017] The output signals generaged from various sensors such as
the throttle valve opening sensor 16 and the accelerator pedal
sensor are amplified to predetermined voltage signals by an
amplifier circuit (not shown) and supplied to an electronic control
unit (hereinafter referred to as ECU) 40. The ECU 40 comprises a
central processing unit (hereinafter referred to as CPU) (not
shown), a read only memory (hereinafter referred to as ROM) (not
shown), a random access memory (hereinafter referred to as RAM)
(not shown), a multiplexer (hereinafter referred to as MPX) (not
shown) and an analog-to-digital converter (hereinafter referred to
as A/D converter) (not shown). Output signals generated from the
sensors are supplied to the MPX. The MPX is a switch which
selectively supplies one of the output signals generated by the
sensors to the A/D converter in response to a command transmitted
from the CPU at a predetermined timing. A supplied sensor output
signal is converted to a digital signal by the A/D converter and
supplied to an input/output bus (not shown). The input/output bus
is designed such that data signals or address signals are input to
and/or output from the CPU, and connected with the ROM and RAM. A
digital signal converted by the A/D converter is supplied to the
RAM. Data designated by the supplied digital signal are stored in
the RAM as sensor output data.
[0018] Furthermore, connected with the above-mentioned input/output
bus is a drive circuit (not shown) for driving a fuel injector and
the throttle valve 14. The CPU supplies a fuel injection control
signal to a fuel injector, and the fuel injector drives a fuel
injection valve (not shown) in response to the fuel injection
control signal to control the supply volume of fuel. The CPU also
supplies a throttle valve switching control signal to a throttle
valve drive unit, and the throttle valve drive unit controls
opening and closing of the throttle valve 14 in response to the
throttle valve switching control signal.
[0019] The above-described internal combustion engine 10 is
provided with an automatic transmission 50. The automatic
transmission 50 comprises a torque converter 52, a transmission
main unit 54 and a hydraulic controller 56. The transmission main
unit 54 has multiple pairs of planetary gears (not shown), and
hydraulic actuated friction engaging members (not shown) such as
hydraulic clutches and hydraulic brakes. The hydraulic controller
56 has an electromagnetic valve for controlling hydraulic circuits
and oil pressure. The automatic transmission 50 changes the
rotational frequency of the internal combustion engine 10 to a
predetermined rotational frequency in response to a gear change
control signal to be described, and transmits torque of the
internal combustion engine 10 to the drive wheels of the vehicle. A
rotational frequency sensor 58 is provided in the vicinity of the
axis of rotation (not shown) of the transmission main unit 54. The
rotational frequency sensor 58 detects the rotational frequency
changed by the automatic transmission 50 and generates an output
signal corresponding to the detected rotational frequency. The
output signal generated from the rotational frequency sensor 58 is
supplied to a transmission control unit (hereinafter referred to as
TCU) 42. The TCU 42 has a CPU (not shown), a ROM (not shown), a RAM
(not shown), an MPX (not shown) and an A/D converter (not shown).
The output signal generated from the rotational frequency sensor 58
is processed in a similar manner to the signal processing carried
out in the ECU 40 and the output value designated by the output
signal is stored in the RAM as data of rotational frequency.
[0020] A shift unit 70 is connected with the TCU 42. The shift unit
70 is provided in the vicinity of the operator's seat in a vehicle.
The shift unit 70 has shift positions designated as `P`, `R`, `N`,
`D`, `2`, `1` and `M`. The shift unit 70 generates an output signal
corresponding to the shift position where an operator positions the
operating lever 72, and the output signal is supplied to the TCU
42. When the operating lever 72 is positioned at a shift position
`P`, `R`, `N`, `D`, `2` or `1`, the automatic gear shift mode is
set, and when the operating lever 72 is positioned at the shift
position `M`, the manual gear shift mode is set. When the operating
lever 72 is positioned at the shift position `M` and the manual
gear shift mode is set, the operating lever 72 is always energized
so as to make the shift position `M` the home position thereof.
With such configuration, even though the operator depresses the
operating lever 72 to positions `+` or `-`, the operating lever 72
returns to the shift position `M` when the operator releases the
operating lever 72. With the gear shift mode being set in manual
gear shift mode, the shift unit 70 gives an output signal to the
TCU 42 so that one gear shift stage of the transmission is shifted
up when the operating lever 72 is depressed once to the `+`
position, and one gear shift stage of the transmission is shifted
down when the operating lever 72 is depressed once to the `-`
position.
[0021] The TCU 42 is connected to an auto cruise control unit
(hereinafter referred to as ACU) 44. The ACU 44 has a CPU (not
shown), a ROM (not shown), a RAM (not shown), an MPX (not shown)
and an A/D converter (not shown). A cruise control switch 34 is
connected with the ACU 44. The cruise control switch 34, which is
provided in the vicinity of the steering wheel, is a switch for
setting or selecting whether or not the travel state of a vehicle
is to be in constant speed travel mode in response to the
operator's manual operation. When the cruise control switch 34 is
changed to the constant speed travel mode, the travel speed at the
time of the operation of the cruise control switch 34 is stored in
the RAM of the ACU 44 as a target speed.
[0022] The above-mentioned ECU 40, TCU 42 and ACU 44 are connected
with each other by communication signal cables. Each of the
processing units of the ECU 40, TCU 42 and ACU 44 transmits and
receives each other's data obtained by each processing unit and
data obtained through operating processing carried out by each of
the processing units. For example, the ECU 40 supplies the speed,
the depressed amount of the accelerator pedal and the opening of
the throttle valve detected by the throttle valve opening sensor 16
to the TCU 42, and the speed to the ACU 44. The TCU 42 also
supplies the throttle valve opening obtained through operating
processing to the ECU 40.
[0023] With the configuration described above, the TCU 42 transmits
a gear change control signal to the hydraulic controller 56
according to supplied information, and determines the gear shift
stage of the automatic transmission 50 by actuating the hydraulic
friction engaging members of the transmission main unit 54. The ACU
44 calculates the deviation between the speed detected by the speed
sensor 30 (hereinafter referred to as detected speed) and the
target speed, and calculates the target throttle valve opening and
the gear shift stage based on the detected speed so as to generate
command signals so as to eliminate any deviation; a command signal
for changing the valve opening for controlling the throttle valve
opening and a command signal for changing the gear shift stage for
controlling the gear shift stage. Hereinafter, the calculated
throttle valve opening will be referred to as the calculated
throttle valve opening, and the calculated gear shift stage will be
referred to as the calculated gear shift stage. The ACU 44
generates a command signal for changing the valve opening in
response to the calculated throttle valve opening and transmits a
command signal for changing the valve opening to the ECU 40. The
ACU 44 generates a command signal for changing the gear shift stage
in response to the calculated gear shift stage, and transmits a
command signal for changing the gear shift stage to the TCU 42. The
command signal for changing the gear shift stage comprises a
downshift command signal generated when the ACU 44 determines that
the gear shift stage should be downshifted, and an upshift command
signal generated when the ACU 44 determines that the gear shift
stage should be upshifted.
[0024] The travel mode setting means is configured from the
above-mentioned cruise control switch 34, the gear change control
means is configured from the TCU 42 and the shift unit 70, the
constant speed travel control means is configured from the ACU 44,
and the transmission driving means is configured from the hydraulic
controller 56.
[0025] Hereinafter, the description is premised on the completion
of initialization of variables and flags used in the CPU of each of
the ECU 40, TCU 42 and ACU 44. The description is given also on the
premise that driving units and controllers of the internal
combustion engine or the automatic transmission have undergone
processing at starting and has been operating constantly.
Furthermore, it is a premise that programs composed of subroutines
shown in FIGS. 2, 3 and 4 are stored in the ROM of the TCU 42
beforehand, and the CPU of the TCU 42 calls and carries out these
programs at a predetermined timing.
[0026] FIG. 2 shows a subroutine for discriminating whether or not
the travel state of a vehicle is in constant speed travel mode.
This determination processing is called and carried out every
predetermined time while the main routine (not shown) is being
carried out.
[0027] First, the state of the cruise control switch 34 is detected
and a determination is made whether it is in the constant speed
travel mode or not (step S11). When the state is determined as
being in the constant speed travel mode, the subroutine is
terminated immediately after the value of flag F_ACR is set to 1
(step S12). When the state is determined as not being in the
constant speed travel mode in step S11, the subroutine is
terminated immediately after the value of flag F_ACR is set to 0
(step S13).
[0028] The subroutine for determining the gear shift stage of an
automatic transmission when the travel state of a vehicle is in the
constant speed travel mode is shown in FIG. 3. This processing is
called and carried out every predetermined time while the main
routine (not shown) is being carried out when the value of flag
F_ACR is 1, that is, when the travel state of a vehicle is in the
constant speed travel mode.
[0029] First, it is detected whether or not the operating lever 72
of the shift unit 70 is positioned at the shift position `M` (step
S21). When the operating lever 72 is determined as being positioned
at the shift position `M`, the gear shift mode is determined as
being in the manual gear shift mode, and, whether the operating
lever 72 is depressed to the shift position `+` or not is detected
(step S22). When it is determined that the operating lever 72 is
not depressed to the shift position `+`, whether the operating
lever 72 is depressed to the shift position `-` or not is detected
(step S23). When it is determined that the operating lever 72 is
not depressed to the shift position `-` either, the gear change
control routine in manual gear shift mode shown in FIG. 4 is
carried out (step S24).
[0030] In step S22 as described above, when the operating lever 72
is determined to be depressed to the shift position `+`, the TCU 42
gives a gear change control signal to the hydraulic controller 56
so as to shift up one gear shift stage of the automatic
transmission (step S25), and the changed gear shift stage is stored
as the gear shift stage in the manual mode (step S26), terminating
the subroutine. In step S23, when it is determined that the
operating lever 72 is depressed to the shift position `-`, the TCU
42 gives a gear change control signal to the hydraulic controller
56 so that one gear shift stage of the automatic transmission is
shifted down (step S27). The subroutine is terminated after the
step S26 is carried out.
[0031] In step S21, when the gear shift mode is determined as being
in the automatic gear shift mode, it is determined whether the ACU
44 has generated a downshift command signal or not (step S28). When
it is determined that a downshift command signal has been generated
from the ACU 44, a gear change control signal is transmitted to the
hydraulic controller 56 so as to shift down one gear shift stage of
the automatic transmission in response to the downshift command
signal (step S29) and the subroutine is terminated. Meanwhile, when
it is determined that no downshift command signal has been
generated from the ACU 44 in step S28, a gear shift stage is
retrieved according to the throttle valve opening and the travel
speed from the shift map stored in advance in the ROM of the TCU
42, and a gear change control signal corresponding to the retrieved
gear shift stage is transmitted to the hydraulic controller 56
(step S30) and the subroutine is terminated.
[0032] FIG. 4 shows a subroutine for controlling a gear change in
the manual gear shift mode carried out in step S24.
[0033] First, it is decided determined whether the ACU 44 has
generated a downshift command signal or not (step S31). When it is
determined that the ACU 44 has generated a downshift command
signal, it is determined whether the depressed amount of the
accelerator pedal is greater than the predetermined amount .alpha.
or not (step S32). When it is determined that the depressed amount
of the accelerator pedal is less than the predetermined amount
.alpha., it is determined whether a timer value to be described is
greater than 0 or not (step S33). When the timer value is
determined as being less than 0, the subroutine is immediately
terminated. The case described above occurs when the operator is
determined as having no intention of accelerating even though a
command signal requiring downshift has been generated from the ACU
44. In such a case, the subroutine is terminated without changing
the gear shift stage.
[0034] When the depressed amount of the accelerator pedal is
determined as being greater than the predetermined amount .alpha.
in step S32, the timer is activated (step S34). The timer starts
the counting operation, setting the predetermined positive value as
a timer value, reduces the timer value as time passes and stops the
counting operation when the timer value becomes 0. Then, a gear
change control signal is transmitted to the hydraulic controller 56
so as to shift down one stage from the manual gear shift stage
stored in step S26 (step S35) and the subroutine is terminated. The
case described above occurs when the ACU 44 generates a command
signal requiring downshift and the operator is determined as having
an intention of accelerating the vehicle. In such a case, one stage
is shifted down from the gear shift stage in the manual mode.
[0035] When the operator reduces the depressed amount of the
accelerator pedal after the timer was started in step S34, it is
determined that the depressed amount of the accelerator pedal is
less than the predetermined amount .alpha. in step S32, and that
the timer value is greater than 0 in step S33. In this case, it is
determined whether the calculated throttle valve opening is greater
than the predetermined value .beta. or not (step S36). When the
calculated throttle valve opening is determined as being greater
than the predetermined value .beta., the subroutine is terminated
after the timer is started again in step S34 and then step S35 is
carried out. In this case, as one gear shift stage has already been
shifted down from the gear shift stage in manual mode as described
above, the subroutine is terminated without changing the gear shift
stage in step S35.
[0036] Meanwhile, when the calculated throttle valve opening is
determined as being less than the predetermined value .beta. in
step S36, the subroutine is immediately terminated. In this case,
it is determined that the operator has no intention of increasing
the speed because of the reduced depressed amount of the
accelerator pedal even though a command signal for requiring
downshift is generated from the ACU 44 after downshift of the gear
shift stage. In such a case, the subroutine is terminated without
changing the gear shift stage until the predetermined time passes,
that is, until the timer value becomes 0.
[0037] In step S31, when it is determined that no downshift command
signal has been generated from the ACU 44, it is determined whether
the timer value is greater than 0 or not (step S37). When the timer
value is determined as being greater than 0, the subroutine is
immediately terminated. This case occurs when it is determined that
no command signal for requiring downshift has been transmitted from
the ACU 44 after downshift of the gear shift stage and that the
operator has no intention of increasing the speed because of the
reduced depressed amount of the accelerator pedal. In such a case,
too, the subroutine is terminated without changing the gear shift
stage until the timer value becomes 0.
[0038] In step S37, when the timer value is determined as being
zero (0) or below 0, a gear change control signal for shifting up
the gear shift stage is transmitted to the hydraulic controller 56
so as to return the gear shift stage to the stage in the manual
mode (step S38) and the subroutine is terminated. This case occurs
when the predetermined time is determined as having passed because
the timer value becomes 0. In such a case, the gear shift stage is
returned to the stage in manual mode.
[0039] As described above, an apparatus for controlling an
automatic transmission according to the present invention can
transmit torque to drive wheels of a vehicle corresponding to
changes in the travel load of a vehicle with the travel mode being
set in constant speed travel mode even though the gear shift mode
is changed to the manual gear shift mode. In this manner, stable
travel of the vehicle is achieved.
* * * * *