JPH03281439A - Slip control device of vehicle - Google Patents

Abstract

PURPOSE:To prevent the over heating due to the increasing in the load of brake control by providing a brake control regulating means to regulate brake control when the throttle opening control in a control blind sector area was continuously done for a specified time and also when brake control was done in this time. CONSTITUTION:A control blind sector area is added to a throttle opening control range. In the next step, when the throttle opening control in this control blind sector area is continued for a specified time, and also when brake control is done for this time, brake control is restricted by a slip control restriction means UTR. When the throttle opening control in the control blind sector area and brake control were thus continuously done for the specified time, the over heating of brakes caused by excessive brake applying can be prevented by regulating brake control.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is a slip control device that performs slip control of drive wheels by traction control, and in particular uses throttle opening control and brake control together to control the slip. Concerning things that perform control.

(Prior art) Conventionally, in order to prevent the drive wheels from slipping due to excessive drive torque during acceleration and reducing acceleration performance, the slip rate of the drive wheels is detected and the slip rate is set to a predetermined target. Traction control is known that controls the driving force transmitted to the drive wheels to adjust the slip ratio.

As a method for controlling the driving force transmitted to the drive wheels, a method is known in which throttle opening control and brake control are used in combination, as described in, for example, Japanese Patent Laid-Open No. 83-38081.

In addition, when performing the above throttle opening control,
It is conceivable to provide a control dead zone in the throttle opening control. Here, the control dead zone refers to the range in which the throttle opening cannot be controlled by the above-mentioned throttle opening control (throttle opening control does not work) out of the entire throttle opening range (0 to 100%). Range from opening to fully closed throttle, e.g. throttle opening 25
The range from 0% to 0% is defined as the control dead zone.

Depending on the throttle opening control, the control dead band may be set such that the throttle opening cannot be within the range of the control dead band, or depending on the throttle opening control, the throttle opening may be set to However, if the accelerator pedal is fully depressed, the throttle opening can be increased at least up to the upper limit of the control deadband (25% in the above example). However, the throttle opening degree may be freely adjusted within the dead zone by operating the accelerator pedal or the like.

If the throttle opening is fully closed (
If the control system malfunctions while the throttle opening is at or near 0%, the throttle opening will be fixed at the substantially fully closed state, and it is conceivable that the vehicle will no longer be able to be driven. The purpose of setting the dead zone is to avoid such a situation from occurring.

(Problems to be Solved by the Invention) However, when a control dead zone is provided in throttle opening control as described above, the following problems arise in a type that uses both throttle opening control and brake control.

In other words, if the throttle opening control enters the control dead band region, in other words, although the throttle opening degree should normally be reduced to a certain value (target value), the target value is within the dead band region and is actually the target value. If the throttle opening can only be reduced to a value greater than , the brake control will be burdened by the inability to reduce the throttle opening to the target value, and if this condition continues for a certain amount of time, the brakes may be overused. The problem arises that the brakes overheat.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a slip control device for a vehicle that can prevent brake heating when throttle opening control enters a control dead zone.

(Means for Solving the Problems) In order to achieve the above object, a slip control device for a vehicle according to the present invention controls the slip of a drive wheel by throttle opening control and brake control, and includes the following steps: A control dead zone is provided in the opening control, and slip control management means is provided for suppressing the brake control when the throttle opening control is continued in the control dead zone region for a predetermined period of time and the brake control is performed during that time. It is characterized by

In a preferred embodiment of the slip control device, the slip control management means may cause another slip control to be performed in place of the brake control when the brake control is stopped. Of course, in this case, it is necessary to be able to perform other slip control in addition to the throttle opening control and brake control, and other slip control may include, for example, engine ignition timing control. .

Suppressing the brake control mentioned above means reducing the brake fluid pressure, increasing the target slip rate for brake control,
Alternatively, it means stopping brake control, etc. Also,
Performing another slip control means starting another slip control anew or increasing the control amount of another slip control.

(Function) In the device according to claim 1, the brake control is suppressed when the throttle opening control and the brake control are continuously performed in the control dead zone for a predetermined period of time, so that the brake control is suppressed due to overuse of the brake. Overheating can be prevented.

Further, in the device according to the second aspect of the present invention, since the brake control is not only suppressed but also other slip control is performed at that time, it is possible to avoid an adverse effect on the slip control due to brake control suppression.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an overall system diagram showing an embodiment of a slip control device according to the present invention.

In this embodiment, slip control, which is traction control, is performed on the drive wheels, and in the slip control, throttle opening control and brake control are mainly performed, and ignition timing control is also performed.

In FIG. 1, A is an automobile equipped with a slip control device according to this embodiment. Car A has left and right front wheels IFL.
and IFR are the driven wheels, and the left and right rear wheels IRL and IRR are
is considered to be the driving wheel.

That is, the torque generated by the engine 2 mounted at the front of the vehicle body is transmitted to the automatic transmission 3. After passing through the propeller shaft 4° differential gear 5, the left rear wheel I via the left drive shaft 6L.
while being transmitted to the right rear wheel I via the right drive shaft 6R.
It is transmitted to RR.

Structure of Automatic Transmission The automatic transmission 3 includes a torque converter 11 and a multi-speed gear mechanism 12. Shifting is performed by a plurality of solenoids 13 built into the hydraulic circuit of the speed change gear mechanism 12.
This is done by changing the combination of excitation and demagnetization of a. Further, the torque converter 11 has a hydraulically operated lock-up clutch liA, and by switching between energization and demagnetization of a solenoid 13b incorporated in the hydraulic circuit of the clutch, the lock-up clutch IIA
The conclusion and cancellation of the agreement are carried out.

The solenoids 13a and 13b are controlled by an automatic transmission control unit UAT. As is known, this control unit UAT stores shift characteristics and lock-up characteristics in advance, and performs shift control and lock-up control based on these characteristics. For this control,
The control unit UAT receives a main throttle opening signal from a main throttle opening sensor 61 that detects the opening of the main throttle valve 43, which will be described below, and a sub-throttle opening sensor that detects the opening of the sub-throttle valve 45. A sub-throttle opening signal from 62 and a vehicle speed signal from a vehicle speed sensor 63 that detects the vehicle speed (in the embodiment, the rotational speed signal of propeller shaft 4) are input.

Structure of brake fluid pressure adjustment mechanism Each wheel IFR to IRR has brakes 21FR to 21R.
R is provided. Each of these brakes 21FR~21R
R caliper (brake cylinder) 22FR~22RR
Brake fluid pressure is supplied to the brake cylinders through pipes 23FR to 23RR.

The configuration for supplying brake fluid pressure to each of the brakes 21FR to 21RR is as follows.

First, the force applied to the brake pedal 25 is boosted by a booster 26 using a hydraulic booster and transmitted to a tandem mask cylinder 27 . The hydraulic pressure transmitted to the mask cylinder 27 is
Brake pipe 23 connected to 7ml discharge port 27a
It is transmitted to the left front wheel brake 21FL via FL, and to the right front wheel brake 21FH via a brake pipe 23FR connected to the second discharge port 27b of the mask cylinder 27.

The booster 26 is supplied with working fluid pressure from a pump 29 via a pipe 28, and excess working fluid is removed from the return pipe 3.
0 to the reservoir tank 31.

A branch pipe 28a branches off from the pipe 28, and an electromagnetic on-off valve 32 is connected to the branch pipe 28a.

Further, a pipe 33 branches from the booster 2G, and an electromagnetic on-off valve 34 and a one-way valve 35 arranged in parallel with the on-off valve 34 are connected to the pipe 33.

The branch pipe 28a and the pipe 33 meet at a confluence part a,
Brake pipe 23R for the left and right rear wheels is connected to the confluence part a.
L, 23RR are connected. This piping 23RL, 2
Electromagnetic on-off valves 36A and 37A are connected to 3RR, respectively, and electromagnetic on-off valves 36B and 37B are connected to relief passages 38L and 38R, which are connected downstream of the valves 38A and 37A, respectively.

Answers 32.34.36A, 37A, 38B mentioned above.
, 37B is a control unit UT for traction control.
Controlled by R. That is, when slip control, which is brake control, is not performed, valve 32 is closed, valve 34 is opened, valves 38B and 37B are closed, and valves 36A and 87A are opened, as shown. As a result, when the brake pedal 25 is depressed, the front wheel brake 21FR
, 21FL are supplied with brake fluid pressure via a mask cylinder 27. Or rear wheel brake 21RR
, 21RL, the hydraulic pressure of the booster 2B is
8 as brake fluid pressure.

As described later, the rear wheel IRR serves as a driving wheel.

When the slip rate of the IRL with respect to the road surface becomes large and slip control, which is brake control, is performed, the valve 34 is closed and the valve 32 is opened. And valves 36A, 38B,
The duty control of 37A and 37B maintains, increases, and decreases the brake fluid pressure.

More specifically, assuming that the valve 32 is closed, the brake fluid pressure is maintained when the response valves 36A, 36B, 37A, and 37B are closed, and the valves 3BA and 3 are closed.
Pressure increases when valve 7A is open and valves 36B and 37B are closed, and valves 88B and 37 are closed and valves 88B and 37 are closed.
When B is open, the pressure drops. The brake fluid pressure passing through the branch pipe 28a is prevented from acting as a reaction force against the brake pedal 25 by the action of the one-way valve 35.

When the brake pedal 25 is depressed during slip control by such brake control, the hydraulic pressure of the booster 26 corresponding to this depression is applied to the rear wheels via the one-way valve 35 as brake hydraulic pressure. Brake 2LRR, 2
1RL is supplied.

Configuration of the throttle opening adjustment mechanism The control unit UTR for traction control controls the driving wheel I.
In order to perform slip control by reducing the torque applied to RL and IRR, brake control is performed by applying brakes to drive wheels IRL and IRR, and at the same time, the throttle opening is reduced to reduce the torque generated by the engine 2 by reducing the throttle opening degree. It also performs temperature control. For this reason, the engine intake passage 4
1 includes a main throttle valve 43 connected to an accelerator pedal 42 and an actuator 4 for adjusting throttle opening.
A sub-throttle valve 45 connected to the engine 4 is provided, and the sub-throttle valve 45 is controlled by the traction control control unit UTR via the actuator 44.

The throttle opening degree control is performed by adjusting the opening degree of the sub-throttle valve 45 via the actuator 44. In this control of the sub-throttle valve opening degree, a control dead zone (0 to 25%) is provided. In other words, the control lower limit value (
25%) and is configured not to close any further.

The method for setting the control lower limit value for the sub-throttle valve opening is as follows:
For example, the sub-throttle valve 45 itself may be provided with a regulating means so as not to exceed the lower control limit, the actuator 44 may be provided with a regulating means so as not to exceed the lower control limit, or the control unit UTR The program may be stored so that the error does not exceed the control lower limit value.

As described above, by providing a control dead zone that prevents the sub-throttle valve opening from falling below the control lower limit value, even if a failure occurs in the sub-throttle valve opening control system, the main throttle valve 43 can be fully opened and at least The throttle opening can be maintained at the lower control limit (25%), making it possible to drive the car.

The traction control unit UTR, which constitutes the ignition timing adjustment mechanism, performs ignition timing control in addition to the brake control and throttle opening control described above. The engine 2 is provided with an ignition timing adjustment section 46, and the ignition timing adjustment section 4B is controlled by the control unit UTR to adjust the ignition timing of the engine.

Structure of Control Unit The traction control control unit UTR controls the brake control, the throttle opening control by controlling the throttle opening adjustment actuator 44, and the ignition timing adjustment section 46 during slip control. ignition timing control. control unit UT
In addition to inputting signals from the wheel speed sensors 64 to 67 that detect the respective wheel speeds, R receives a main throttle opening signal from the main throttle opening sensor 61 and a subthrottle opening signal from the subthrottle opening sensor B2. signal, vehicle speed signal from vehicle speed sensor 63, accelerator opening signal from accelerator opening sensor 68, yaw rate signal from yaw rate sensor 69, shift position signal from shift position sensor 70, steering wheel steering angle from steering wheel steering angle sensor 71 A signal and a traction control mode signal from a manually operated traction control mode selection switch 72 are input.

Furthermore, the control unit UTR has an input interface for receiving each signal from each sensor, and a CPU and RO.
A microcomputer consisting of M and RAM, an output interface, and valves 32.34° 36A, 37A, 8
8B, 37B and a drive circuit that drives the actuator 44, the ROM stores control programs and various maps necessary for traction control, and the RA
M is provided with various memories necessary for executing control.

The control unit UTR also functions as a slip control management means for managing slip control as described below.

Contents of slip control Next, we will explain the contents of slip control using both throttle opening control and brake control by the control unit UTH in the second section.
This will be explained based on the diagram.

In FIG. 2, the target slip rate for throttle opening control of the drive wheels is indicated by SET, and the target slip rate for brake control of the drive wheels is indicated by SBT.

Note that SBT is set to a larger value than SET.

Now, until time t1, no large slip has occurred in the drive wheels, so throttle opening control is not being performed, and therefore the sub-throttle valve 47 is fully open.
The throttle opening (the composite opening of both throttle valves 43.45, which matches the opening of the smaller throttle valve) Tn corresponds to the main throttle opening TH-M, and it is the accelerator opening. (The opening degree of the accelerator pedal, which is fully open when the accelerator pedal is fully depressed).

At time t1, when the slip rate of the driving wheels reaches the target slip rate SET for throttle opening control, slip control by throttle opening control is started, and the actuator 4
4 to close the sub-throttle valve 45, the throttle opening degree Tn is reduced all at once to the lower limit control value SM. After the throttle opening degree Tn is once set to SM, the opening degree TH-S of the sub-throttle valve 45 is feedback-controlled so that the slip rate of the drive wheels becomes the target slip rate SET for throttle opening degree control. When the throttle opening control is started in this way, the sub-throttle valve opening TH-8 is smaller than the main throttle valve opening TH-M (therefore, the throttle opening Tn is the sub-throttle valve opening TH-8). Become S.

If a sufficient slip ratio reduction effect cannot be obtained only by the throttle opening control, the slip ratio continues to increase and becomes equal to or higher than the brake control target slip ratio SBT at time tz.

When the slip rate of the drive wheel becomes equal to or higher than the target slip rate for brake control at time tz, the brake 21R of the drive wheel
Brake fluid pressure is supplied to R and 2LRL, and slip control using both throttle opening control and brake control is started. The brake fluid pressure is feedback-controlled so that the slip rate of the driving wheels becomes the brake control target slip rate SBT.

At time t3, when the slip ratio of the drive wheels becomes less than the target slip ratio for brake control SBT, the brake fluid pressure is reduced, and eventually the brake fluid pressure becomes zero, and the slip control by brake control ends.

However, the slip control based on throttle opening control is still continued.

Note that the target slip ratios SBT and SET may be determined as appropriate, for example, depending on the road surface μ.

It is determined by the control unit UTR based on the vehicle speed, the accelerator opening, the steering angle, the selected mode such as sport or hard, and the above-mentioned SM is also appropriately determined by the control unit UTR based on, for example, the road surface μ.

The above-mentioned brake control is performed independently on the left and right wheels, for example, based on the slip ratios SL and SR of the left and right drive wheels. Also,
The throttle opening control is performed, for example, based on the slip ratio S of the left and right drive wheels, which is the larger of the slip ratios SL and SR.

Note that the slip ratios SL and SR are calculated in the control unit UTR according to the following formula based on wheel speed signals from the respective wheel speed sensors 63 to θ6.

V) J However, vKL: Rotational speed of the left driving wheel VKR: Rotational speed of the right driving wheel JV: Average value of the rotational speed of the left and right driven wheels Note that the slip ratio is not necessarily calculated based on the above formula. It is not necessary to have a value, and any value that substantially indicates the slip state of the wheels may be used. For example, a value simply obtained by subtracting the driven wheel speed from the driving wheel speed may also be used.

Slip control management The above-mentioned slip control is carried out by the control units T and JTR described above.
It is managed by a slip control management means constituted by.

When the slip control management means performs slip control using both throttle opening control and brake control, the throttle opening control enters the control dead zone region, that is, the slip control management means does not normally control the opening of the sub-throttle valve 45. I would like to make the control value even smaller than the control lower limit value, but because a control dead zone is provided, it enters a state where it is stopped at the control lower limit value, and such a state in the control dead zone region continues for a predetermined period of time. When the brake control is continued for the predetermined time, the brake control is stopped after the predetermined time has elapsed, and instead of the brake control, the amount of slip control by ignition timing control is increased, that is, the ignition timing is changed. This increases the amount of delay. The suspension period of the brake control may be determined as appropriate, and may be, for example, a predetermined period of time set in advance, or may be until the throttle opening control exits the control dead zone.

FIG. 3 is a flowchart showing the flow of the management of the slip control, but since this shows the flow of the above-mentioned management as it is, the explanation will be omitted.

In the above embodiment, a sub-throttle valve is provided separately and the opening degree of the sub-throttle valve is adjusted to control the throttle opening degree. However, for example, only one throttle valve is provided and the accelerator pedal and the throttle valve are connected An appropriate throttle opening adjustment mechanism may be provided in the middle of the connecting member, and the throttle opening may be controlled by the adjustment mechanism, and in this case, a control dead zone may be provided as appropriate.

(Effects of the Invention) As described above, in the vehicle slip control device according to the present invention, when the throttle opening control enters the control dead zone and the brake control continues for a predetermined period of time, the brake control is performed. Therefore, it is possible to prevent overheating of the brake due to an increase in the burden of brake control.

Further, by performing another slip control when the brake control is suppressed, it is possible to prevent an adverse effect on the slip control due to suspension of the brake control.

[Brief explanation of drawings]

Fig. 1 is an overall system diagram of an embodiment of the present invention, Fig. 2 is a time chart showing an aspect of slip control using both throttle opening control and brake control, and Fig. 3 is a flow chart showing an example of slip control management. be. UTA...Slip control management means 64...Other slip control units Fig. 2 Fig. 3

Claims (2)

[Claims] (1) In a slip control device that controls drive wheel slip by throttle opening control and brake control, a control dead zone is provided in the throttle opening control, and the throttle opening control is performed in the control dead zone region for a predetermined period of time. A slip control device for a vehicle, comprising slip control management means for suppressing the brake control when the brake control continues and the brake control is continued. (2) The slip control device for a vehicle according to claim 1, wherein the slip control management means, when suppressing the brake control, causes another slip control to be performed in place of the brake control. slip control device.