JP3310992B2 - Acceleration slip control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration slip control method.

[0002]

2. Description of the Related Art Conventionally, an acceleration slip control device for suppressing the rotation of a driving wheel when an acceleration slip occurs has been proposed in order to prevent an acceleration slip of the driving wheel when starting or accelerating on a snowy road. As a control method, a fixed control method is generally used in which engine output control including cutting of the number of cylinders, ignition timing is retarded, and brake control for controlling brake fluid pressure are combined (for example, Japanese Patent Application Laid-Open No. Sho 62-62).
No. 157851).

[0003]

In the conventional apparatus as described above, the initial stage of the acceleration slip when the number of braking times K is less than 5, or
A conventional braking device which does not have particularly high durability can be obtained by performing the braking main slip control only when the rotation of the driving wheels is immediately suppressed, such as when the slip ratio is high or when the vehicle speed is higher than 10 km / hr. While the present invention aims to be able to use it, the present invention weights in the opposite way to the above and mainly performs independent brake control of each driving wheel with good response at low speeds, so that a split μ road or the like can be used. It is an object of the present invention to provide an acceleration slip control method capable of improving the starting performance of the vehicle and improving the operability by mainly controlling the engine output with little imbalance at a high speed.

[0004]

SUMMARY OF THE INVENTION The present invention provides an acceleration control method for reducing the slip ratio by reducing the output of an engine and supplying brake fluid pressure to a brake device for each driving wheel with respect to the amount of depression of an accelerator pedal. In the slip control device, when the vehicle speed is medium to high speed where the vehicle speed is equal to or higher than a predetermined speed, the drive wheels when the engine torque is reduced by a predetermined amount are reduced.
Observe the amount of change in the slip ratio to determine the amount of decrease in engine torque.
Mainly the operation of the engine control unit for feedback control
Brake control unit that applies a predetermined amount of brake fluid pressure
The acceleration slip of the engine
When the vehicle speed is low and the vehicle speed is lower than a predetermined speed, the vehicle speed of each drive wheel when a predetermined amount of brake fluid pressure is applied is controlled.
Observe the amount of change in the slip ratio and adjust the predetermined amount of each brake fluid pressure.
It mainly operates the brake control unit that performs feedback control.
To reduce the engine torque by a predetermined amount.
Brake control subject to operation of engine control unit
The acceleration that to perform the slip control of the first feature, the engine braking the vehicle speed as the main operation of the brake control unit a time of low-speed traveling below a predetermined speed
When the slip ratio of the drive wheels becomes less than a predetermined value during the acceleration slip control mainly performed by the brake control that is based on the operation of the control unit, the operation of the brake control unit is stopped, and only the operation of the subordinate engine control unit is performed. The second feature is that the switching is performed.

[0005]

According to the above, the driving stability is improved when running at medium to high speeds, the wear of the brake pads and the like is reduced, and the phenomenon such as fade due to frictional heat does not occur. Not only can the characteristics and the durability of the axle system be improved, but also the steering stability can be further improved.

[0006]

FIG. 2 shows an embodiment of the present invention.
Reference numerals 1 and 2 denote left front wheel speed sensors and right front wheel speed sensors which detect wheel speeds of the left front wheel and right front wheel, which are not shown, and generate wheel speed signals, respectively. A left rear wheel speed sensor that detects wheel speeds of the left rear wheel and the right rear wheel and generates a wheel speed signal.
The right rear wheel speed sensor 5 is a control circuit for acceleration slip control. The control circuit 5 includes a left rear wheel speed sensor 3 and a right rear wheel speed sensor 4 on the driven wheel side where acceleration slip cannot occur. A vehicle speed V estimating circuit 5a for estimating the vehicle speed V from the average value of the wheel speed indicated by the emitted wheel speed signal
And the respective wheel speeds indicated by the wheel speed signals emitted from the left front wheel speed sensor 1 and the right front wheel speed sensor 2 on the driving wheel side, and the vehicle speed V estimated by the vehicle speed V estimation circuit 5a.
A front wheel slip ratio S calculating circuit 5b for calculating each front wheel slip ratio S from the above, a traction control necessity determining circuit 5c for determining the necessity of traction control operation accordingly, and each front wheel slip ratio S calculating circuit 5b
In accordance with the calculated front wheel slip ratio S and the vehicle speed V estimated by the vehicle speed V estimating circuit 5a as to which of the later-described engine control unit 6 and brake control unit 8 is to be controlled. It is composed of a traction control control method selection circuit 5d that issues signals, an engine-based traction control command circuit 5e and a brake control-based traction control command circuit 5f selected by the selection circuit 5d.

Reference numeral 6 denotes an engine control unit. The engine control unit 6 reduces the throttle valve opening, reduces the number of cylinders, or delays ignition timing based on a control signal from the control circuit 5 for controlling acceleration slip. The slip of the engine 7 is prevented by lowering the output of the engine 7 by means such as conversion, and the control mode of the engine control unit 6 as described above is conventionally known as described above.

Reference numeral 8 denotes a brake control unit. The brake control unit 8 operates a hydraulic pump and a switching valve based on a control signal from the control circuit 5 for controlling the acceleration slip, and is sucked from the reservoir into the hydraulic pump. The brake hydraulic pressure generated by the hydraulic pump is added to the brake device 9 of the driving wheel to prevent the acceleration slip, and the control mode of the brake control unit 8 as described above is conventionally known as described above. Therefore, detailed description is omitted.

In the above, the control circuit 5 for acceleration slip control performs a wheel speed calculation S1 based on the wheel speed signals output from the wheel speed sensors on the driving wheel side and the driven wheel side during acceleration as shown in FIG. Emitted from the left front wheel and right front wheel speed sensors 1 and 2 on the driving wheel side with respect to the average value of the wheel speed indicated by the wheel speed signals emitted from the left rear wheel and right rear wheel speed sensors 3 and 4 on the driven wheel side. The respective slip ratios S are calculated S2 from the ratios of the wheel speeds indicated by the wheel speed signals. The traction control is performed based on whether the slip ratio S is equal to or greater than a first predetermined value (for example, 10%). S3, when it is determined that the above traction control is to be performed, from the wheel speed sensors 3 and 4 of the left rear wheel and the right rear wheel which are on the driven wheel side and cannot cause acceleration slip. The vehicle speed V estimation S4 is performed from the average value of the wheel speeds indicated by the wheel speed signals to be given, and it is determined whether the vehicle speed V is lower than a predetermined speed V0 (for example, 50 km / h). When the vehicle is running at a speed higher than V0, the engine control unit 6 mainly performs the operation of the engine control unit 6 for feedback-controlling the amount of decrease in engine torque by observing the amount of change in the slip ratio S of the drive wheels when the engine torque is decreased by a predetermined amount. When the vehicle speed V is lower than the predetermined speed V0, the vehicle is running at a low speed. Mainly and auxiliaryly, the operation of the brake control unit 8 for feedback-controlling a predetermined amount of each brake hydraulic pressure based on the amount of change in the slip ratio S of each drive wheel when a fixed amount of brake hydraulic pressure is applied The engine control unit decreases the Njintoruku predetermined amount 6
The acceleration slip control of the brake control main body S7 is performed, and the slip ratio S of the drive wheel is smaller than the second predetermined value S0 (for example, 20%) during the acceleration slip control of the brake control main body S7. A determination is made as to whether or not there is any. If the value is less than the second predetermined value S0, the main brake control of the acceleration slip control of the brake control main body S7 is stopped, and the acceleration slip control of S9 in which only the subordinate engine control is performed. It is supposed to do.

As described above, when the vehicle speed V is higher than the predetermined speed V0, the acceleration slip control of the engine control main body S6, in which the imbalance between the left and right drive wheels hardly occurs, can improve the running stability. At the same time, it is possible to improve the wear durability of the friction material such as the brake pad and the like, and to improve the brake durability such that the instability such as fade due to frictional heat is not caused.

When the vehicle speed V is lower than the predetermined speed V0 at low speeds, the acceleration control is performed by the brake control main unit S7 having good response, so that the left and right wheels have different friction coefficients μ between the tires and the road surface on the split μ road. The starting performance can be improved, and the steering stability can be improved.

Further, when the slip rate S at the time of low speed running in which the acceleration slip control of the brake control subject S7 is performed becomes less than the second predetermined value S0, the main brake control is stopped and only the subordinate engine control is performed. By adopting the acceleration slip control in step S9, the durability of the axle system can be improved, and vibration and noise due to output fluctuations in a low-speed range where the output torque is large can be reduced.

[0013]

As described above, according to the present invention, the running stability is improved by performing the acceleration slip control mainly by the engine control at the time of middle to high speed running, the wear of the brake pads and the like is reduced, and the friction heat is reduced. In addition, by preventing the phenomenon such as fade due to the above, and at the time of low-speed traveling, by performing acceleration slip control mainly by the brake control, it is possible to not only improve the starting characteristics and traveling stability on the split μ road, but also to improve the braking control When the slip ratio of the drive wheel during acceleration slip control is less than a predetermined value, brake control is stopped and only engine control is performed to improve the durability of the axle system, which can have a great effect in practical use. It is.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an embodiment of the present invention.

FIG. 2 is a block diagram showing an acceleration slip control device to which the present invention is applied.

[Explanation of symbols]

Reference Signs List 1 left front wheel speed sensor 2 right front wheel speed sensor 3 left rear wheel speed sensor 4 right rear wheel speed sensor 5 control circuit 5a body speed V estimation circuit 5b front wheel slip ratio S calculation circuit 5c traction control necessity determination circuit 5d Traction control control system selection circuit 5e Traction control command circuit for engine control main body 5f Traction control command circuit for brake control main body 6 Engine control unit 7 Engine 8 Brake control unit 9 Each brake device

Continuation of the front page (56) References JP-A-63-34270 (JP, A) JP-A-64-12961 (JP, A) JP-A-63-31867 (JP, A) JP-A-3-14757 (JP) JP-A-63-166649 (JP, A) JP-A-62-157851 (JP, A)

Claims (2)

(57) [Claims] An acceleration slip control device adopting a control method for reducing a slip ratio by lowering the output of an engine and supplying brake fluid pressure to a brake device of each drive wheel with respect to a depression amount of an accelerator pedal, wherein the vehicle speed is reduced. When the vehicle is running at a speed higher than the specified speed , the engine torque is
Check the amount of change in the slip ratio of the drive wheels when the
Engine that feedback controls the amount of engine torque reduction
A predetermined amount of brake fluid
An engine that depends on the operation of the brake control unit that applies pressure
When the vehicle is running at a low speed where the vehicle speed is lower than a predetermined speed , a predetermined amount of brake fluid pressure is applied.
The amount of change in the slip ratio of each drive wheel when
A brake that feedback-controls a predetermined amount of each brake fluid pressure
Mainly the operation of the control unit and auxiliary engine torque
Operation of the engine control unit to reduce the
An acceleration slip control method characterized by performing acceleration slip control mainly by a brake control . 2. The method of claim 1, wherein the vehicle is running at a low speed where the vehicle speed is lower than a predetermined speed and the operation of the brake control unit is mainly performed.
When the slip ratio of the drive wheels becomes less than a predetermined value during the acceleration slip control mainly performed by the brake control that is based on the operation of the control unit, the operation of the brake control unit is stopped, and only the operation of the subordinate engine control unit is performed. An acceleration slip control method, wherein the method is switched.