JPH05118435A - Creep controller for automatic transmission - Google Patents

Abstract

PURPOSE:To improve durability by preventing the input of the excessive torque into a forward clutch which forms a neutral state and carries out creep preventing control, by prohibiting the creep preventing control when the reduc tion of the engine output is impossible. CONSTITUTION:In the state where the shift range of an automatic transmission installed on an engine is set in an advance traveling range, a creep control condition judging means judges that a prescribed condition is established on the basis of the car speed, brake signal, throttle opening degree, shift position, etc. When the establishment of the condition is judged, a creep control means forms a neutral state and carries out creep preventing control. In this device, a judging means judges if the reduction of the engine output is permitted or not. When it is judged that the reduction of engine output can not be reduced, the creep preventing control is prohibited by a prohibiting means. Accordingly, the input of the excessive torque is prevented from being inputted into a forward clutch which forms a neutral state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an automatic transmission for a vehicle, and more particularly to a creep control device for an automatic transmission which performs creep prevention control when a predetermined condition is satisfied.

[0002]

2. Description of the Related Art An automatic transmission for a vehicle is generally constructed by combining a hydraulic torque converter for transmitting power from an engine and a gear transmission mechanism such as a planetary gear. In such an automatic transmission, a so-called creep phenomenon occurs in which the vehicle gradually moves forward while the vehicle is stopped in the drive range at the shift position. This is because when the shift position is set to the drive range, the gear shift mechanism is in the first speed state,
In addition, since the engine is rotating at the idle speed, some torque is transmitted to the vehicle side via the torque converter. Such a phenomenon can be suppressed by manually shifting the shift position to the neutral range, but in a driving state in which start and stop are frequently performed, the shift position remains in the drive range and the brake is depressed to prevent the creep phenomenon. Hold down is done. Further, in order to prevent such a creep phenomenon, a technique has been proposed in which a neutral state is formed when a predetermined condition is satisfied. Then, specifically, in order to form the neutral state, the forward clutch is slipped. By performing such creep prevention control, it is possible to prevent the occurrence of creep, reduce vibration during idling, and prevent the fuel efficiency from being deteriorated during idling due to dragging of the torque converter. The creep prevention control is disclosed, for example, in Japanese Patent Laid-Open No. 62-244725. The technique disclosed in this publication is characterized in that the engine output is temporarily reduced when the creep control is released. As a result, when the creep control is released, that is, the engine output is reduced during the engagement process of the forward clutch, the energy absorption amount of the friction material of the forward clutch during engagement of the forward clutch can be reduced, The reduction of durability of the forward clutch is said to be avoided.

[0003]

However, it is conceivable that the engine output may not be reduced even when a command to reduce the engine output is actually sent when the creep control is released. For example, in the case of reducing the output by ignition retard or fuel cut of the engine, the exhaust temperature or the catalyst temperature is a high temperature above a predetermined value, the sensor such as an air flow meter or an oxygen sensor fails, or the actuator such as an injector or an igniter fails. When it happened. Further, when the output is reduced by air control, it is when the frequency of operation of an actuator such as a throttle sensor failure or a throttle motor is high or a failure occurs. Due to the reasons described above, it becomes impossible to reduce the engine output, and the creep prevention control ends with the engine output still high. In such a case, a large torque is applied to the forward-stage forming clutch, which may reduce the durability of the forward-stage forming clutch.

In view of the above, an object of the present invention is to take into consideration the above-mentioned problems and to determine whether or not the engine output can be actually reduced before shifting to the creep prevention control. This is to prevent excessive torque input to the forward clutch when the prevention control is released.

[0005]

According to the present invention, when the shift range of an automatic transmission is set to a forward drive range and a predetermined condition is satisfied, a neutral state is formed to perform creep prevention control. In the creep control device, there is provided means for determining whether or not the engine output can be reduced, and means for inhibiting the creep prevention control when the means determines that the engine output cannot be reduced. A creep control device for an automatic transmission characterized by:

[0006]

The creep prevention control is performed after it is judged that the output of the engine can be reduced by the above means. When it is determined that the engine output cannot be reduced, the creep prevention control is prohibited.

[0007]

Next, an embodiment of the present invention will be described with reference to FIG. This is an overall schematic diagram of an automatic transmission combined with an intake air amount sensing type electronic fuel injection engine. The air sucked from the air cleaner 10 includes an air flow meter 12, a sub-throttle valve 14B, a main throttle valve 14A, a surge tank 16, and an intake manifold 18.
To be sent to. This air is mixed with fuel injected from the injector 22 near the intake port 20 and is further sent to the combustion chamber 26A of the engine body 26 via the intake valve 24. The exhaust gas generated as a result of the combustion of the air-fuel mixture in the combustion chamber 26A includes an exhaust valve 28, an exhaust port 30,
It is released to the atmosphere through the exhaust manifold 32 and the exhaust pipe 34. An exhaust temperature sensor 34 is provided in the exhaust pipe 34. The air flow meter 12 is provided with an intake air temperature sensor 100 for detecting the intake air temperature. In addition, the exhaust manifold 32 is provided with an oxygen sensor 106 for detecting the amount of oxygen in the exhaust gas of the engine. The main throttle valve 14A rotates in conjunction with an accelerator pedal (not shown) provided in the driver's seat. The sub-throttle valve 14B is for controlling engine torque when the engine computer 40 controls the engine and the automatic transmission 60. The main throttle valve 14A and the sub throttle valve 14B
Are provided with throttle sensors 102A and 102B for detecting the respective opening degrees.

The cylinder block 26B of the engine body 26 is provided with a water temperature sensor 104 for detecting the engine cooling water temperature. Further, the engine body 26
A distributor 38 having a shaft rotated by the crank shaft is provided with a crank angle sensor 108 for detecting a crank angle from the rotation of the shaft, thereby detecting an engine speed and an engine rotation fluctuation amount. .. Further, the automatic transmission has a vehicle speed sensor 110 for detecting the vehicle speed from the rotational speed of its output shaft, and a rotational speed sensor 1 for the clutch C0 which is one of the rotary members of the automatic transmission.
13 and a shift position sensor 112 for detecting the shift position.

The intake air temperature sensor 100, the main throttle valve throttle sensor 102A, the sub throttle valve throttle sensor 102B, the water temperature sensor 104, the oxygen sensor 106, the crank angle sensor 108, and the vehicle speed sensor 1
10, shift position sensor 112, clutch C0 rotation speed sensor 113, pattern select switch 12
0, the output of the brake lamp switch 122, and the output of the overdrive switch 124 are input to the engine computer 40 or the automatic transmission computer 50. The engine computer 40 calculates the fuel injection amount and the optimum ignition timing using the input signals from the respective sensors as parameters, and controls the injector 22 so as to inject the fuel for a predetermined time corresponding to the fuel injection amount. An output for controlling the ignition coil 44 is provided so that the optimum ignition timing is obtained. Also, the main throttle valve 14A
An idle speed control valve 42 driven by a step motor is provided in a bypass passage connecting the upstream side of the engine and the surge tank 16, and the idle speed is controlled by a signal output from the engine computer 40.

The automatic transmission in this embodiment performs predetermined processing according to the automatic transmission computer 50 to which signals from the throttle sensors 102A and 102B, the vehicle speed sensor 110, the rotation speed sensor 113 of the clutch C0, etc. are input. Done, and the automatic transmission 60
The movement of unillustrated solenoids therein is controlled, and engagement of each clutch, brake, etc. is combined to perform shift control. The creep prevention control is executed based on the engine speed signal detected by the shift position sensor 112, the main throttle valve 14A, the brake lamp switch 122, the vehicle speed sensor 110, and the crank angle sensor 108. Controlled by. In such a device, the engine computer 40 controls the engine torque by receiving a shift signal from the automatic transmission computer 50 such as a shift determination, a shift command, a lock-up clutch engagement permission, and a creep prevention control. Further, the engine computer 40 determines whether or not it is possible to reduce the engine torque, and sends the determination result to the automatic transmission computer 50.
The determination as to whether or not the engine torque can be reduced is used as one of the conditions for determining the shift to the creep prevention control. When the creep prevention control is released, the sub-throttle valve 14B executes engine torque reduction control.

FIG. 3 shows a control flow specifically executed by the apparatus of the above embodiment. Step 201
The steps from 206 to 206 are steps for determining the condition for establishing the creep control according to the present invention. In step 201, it is determined whether the shift position is in the drive range. In step 202, it is determined whether the idle contact signal is in the on state. In step 203, it is determined whether the foot brake signal is in the on state by using the signal from the brake lamp switch 122. Vehicle speed V in step 204
Is determined to be equal to or less than the set value V0 close to zero.
In step 205, it is determined whether the engine torque can be reduced. The judgment that the torque cannot be reduced is made under the following conditions. Sub throttle sensor 102
When the fluctuation amount of the signal sent from B to the engine computer 40 is abnormally large, when the signal remains an abnormal value, when the signal is not input, when the signal remains at a constant value, When the condition appears, it is determined that the engine torque cannot be reduced. This is because the abnormality in the signal value as described above may be because the sub-throttle sensor 102B is out of order, or the path from the sub-throttle sensor 102B to the engine computer 40 is broken or short-circuited. Similarly, the failure of the main throttle can be detected. Also, the motor driving the sub-throttle has failed, for example, the wiring to the step motor is broken,
It is possible to determine that the torque cannot be reduced even if the sub-throttle is out of step or the return spring is damaged. Further, it may be possible to detect a failure of the traction solenoid relay or the like. The above judgment can be made in the engine control computer. When the phenomenon described above appears, it is determined that the torque reduction condition is not satisfied, and the transition to the creep prevention control is prohibited. In step 206, it is determined whether the engine speed Ne is less than or equal to a predetermined value Ne ₀ . This is when the engine speed is higher than normal,
This is because a shock will occur when returning, and the durability of the forward clutch will decrease. When all of these conditions are satisfied, the routine proceeds to step 207, where the opening degree of the sub throttle valve 14B is closed to the predetermined value Θ _s1 . Since a qualitative tendency that the engine torque hardly changes in the range where the sub-throttle valve 14B is a specific predetermined value or more is generally recognized, the sub-throttle up to Θ _S1 set as a value immediately before the engine torque is not reduced. By closing the valve, it becomes possible to promptly reduce the torque when a request for reducing the torque is made at the time of returning from the creep prevention control. Thereafter, the routine proceeds to step 208, where a forward clutch (not shown) is released, a neutral state is formed by a conventionally known method, and a creep prevention state is set. Here, the creep prevention control is executed when all the conditions of steps 201 to 206 are satisfied. Here, the conditions from steps 201 to 205 correspond to the substantial conditions for the creep prevention control. The condition of step 206 is detected for confirmation from a failsafe point of view.

On the other hand, if any of the steps 201 to 206 determines that the condition is not satisfied, the creep prevention control is prohibited or the transition to the creep prevention control is not performed. The case where the creep prevention control is not performed will be described below.

For example, when the idle contact is turned off in step 202, the sub-throttle valve is closed during the full engagement of the forward clutch or during the full engagement to reduce the torque of the engine. And step 20
At 9, it is determined whether the timing for ending the torque reduction by the opening / closing control of the sub-throttle valve 14B has come.
This determination is made by specifically determining whether or not the expression (1) is satisfied. N _T <Ne × i + D (1) where N _T is the turbine rotation speed of the torque converter of the automatic transmission (input shaft rotation speed of the automatic transmission), Ne is the output shaft rotation speed of the automatic transmission, and i is the First gear ratio, D
Is a constant. Initially, the forward clutch is still slipping greatly, so this judgment is based on (1) above.
It is determined that the expression is not satisfied, and the process proceeds to step 210. In step 210, the sub-throttle valve 1 is operated in order to execute the torque down control when the creep prevention control is released.
The opening of 4B is closed with a predetermined value Θ _S2 . As a result, the torque reduction is promptly executed. In step 212, a command is issued to engage the forward clutch to form the first gear. Eventually, the engagement of the forward clutch progresses. If it is determined in step 209 that the above equation (1) is satisfied, the routine proceeds to step 211, the sub throttle valve 14B is fully opened, and the torque reduction control is ended. As described above, in the present invention, the creep prevention control is entered after it is determined that the engine torque can be reduced, so that the engine torque to the forward clutch is reliably reduced when the creep prevention control is released. Since it can be engaged in a state, it can be quickly and completely engaged with a small shock. Moreover, since the engine torque is returned immediately before the complete engagement, it is possible to start the vehicle immediately upon completion of the engagement. Further, since the engine torque is surely reduced, the durability of the forward clutch is improved.

Further, step 201, step 213,
If it is determined in step 216 that the shift position is in the 2 range or the L range, and if any of the conditions in steps 203 to 206 is not satisfied, the process proceeds to step 214, and the forward clutch is completely engaged. It is determined whether or not the matching has been completed. Step 214
When it is determined that the forward clutch is engaged, the process proceeds to step 217, the sub-throttle valve 14B is fully opened, and the forward clutch is completely engaged in step 218. At this time, in step 218, the increase in the engagement pressure to the forward clutch is
Full engagement is achieved while licking. When the engagement is completed, the flow is step 214, step 209, step 2
11, the sequence proceeds in the order of step 212, and the complete engagement of the forward clutch is maintained.

Further, step 201 and step 21
3. If it is determined in step 216 that the shift position is neither the drive range, the 2 range nor the L range, the process proceeds to step 219 and the sub-throttle valve 14B is fully opened. The forward clutch is completely released.

According to this embodiment, when the creep prevention state is set, the sub-throttle valve 14B is closed in advance to a predetermined value Θ _S1 which does not affect the engine torque to form a so-called standby state. By releasing the control and further closing the sub-throttle valve to the predetermined value Θ _S2 , the engine torque can be reduced with good responsiveness. The specific values of Θ _S1 and Θ _S2 (Θ _S2 ≤ Θ _S1 ) and their closing speeds can be determined so that the engine torque can be reduced sufficiently and without any trouble. Although it is determined in step 205 whether the engine torque can be reduced, step 207
There may be a method of detecting whether the sub-throttle valve 14B is actually closed up to Θ _{S1 in} response to a signal that the sub-throttle valve 14B is closed up to Θ _S1 .

In the present embodiment, it is judged whether the engine torque can be reduced or not, whether the combustion of the engine is stable or not, and whether the engine control is normal or not, the engine is unstable. Sometimes the transition to creep prevention control is not performed. In the above embodiment, the sub throttle valve 14B is provided in addition to the main throttle valve 14A,
The device for electronically controlling the sub-throttle valve 14B has been described, but the present invention can be applied to a system for electronically controlling only one main throttle valve depending on the accelerator opening degree. The determination as to whether the engine can be reduced can be detected in the same manner as the method using the sub throttle valve. Further, the present invention can be applied to a method of retarding engine ignition and a method of fuel cut as a method of reducing engine torque. In this case, when the exhaust temperature or the catalyst temperature is higher than a predetermined value, when an abnormal signal of the air flow meter or oxygen sensor is detected, when the injector or igniter failure is detected, the ignition timing cannot be controlled. It is conceivable to use the time when it is detected as a criterion for judging the impossibility of reducing the engine torque. Furthermore, if there is a method of detecting the torque reduction other than the method of judging that the torque reduction is impossible as shown in the present embodiment, it may be used.

[0018]

According to the present invention, when the means for determining whether or not the engine output can be reduced determines that the engine output cannot be reduced, the transition to the creep prevention control is prohibited and the forward clutch is applied. Since the input of a large torque can be prevented, the durability of the forward clutch is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing the gist of the present invention.

FIG. 2 is a schematic diagram of an integrated control device for an automatic transmission and an engine to which an embodiment of the present invention is applied.

FIG. 3 is a flowchart of control executed in this embodiment.

[Explanation of symbols]

 14B Sub-throttle valve 14A Main throttle valve 22 Injector 24 Intake valve 34 Exhaust pipe 36 Exhaust temperature sensor 40 Engine computer 42 Idle rotation control valve 50 Automatic transmission computer 102A Main throttle valve throttle sensor 102B Sub-throttle valve throttle sensor 104 Water temperature sensor 106 Oxygen sensor 108 Crank angle sensor 110 Vehicle speed sensor 112 Shift position sensor 122 Brake lamp switch

Claims (1)

[Claims] 1. A creep control device for an automatic transmission, wherein a shift range of the automatic transmission is set to a forward traveling range, and a neutral state is formed to perform creep prevention control when a predetermined condition is satisfied, an engine output is provided. Of the automatic transmission, and means for determining whether or not the engine output can be reduced, and for prohibiting the creep prevention control when the means determines that the engine output cannot be reduced. Creep control device.