JP2884789B2 - Vehicle anti-skid control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for correcting a turning trajectory at the time of turning braking, particularly at the time of sudden braking during turning at a high lateral acceleration, using an anti-skid control device of a vehicle.

[0002]

2. Description of the Related Art A hydraulic brake system for a vehicle brakes each wheel by operating a wheel cylinder of each wheel with a hydraulic pressure from a master cylinder corresponding to a brake pedal depression force.

At the time of braking, the load on the front wheel increases due to the movement of the vehicle body, and the load on the rear wheel decreases. Therefore, if the front and rear wheel brake fluid pressures are the same, the rear wheel locks before the front wheel, and Causes course instability. Conversely, when the front wheels lock before the rear wheels, at least there is no instability in the course of the vehicle, which is advantageous for safety.

[0004] From this point of view, in a general hydraulic brake device, a hydraulic control valve for limiting an increase in the rear wheel brake hydraulic pressure in a region above a certain brake hydraulic pressure is inserted into the rear wheel brake hydraulic system. ing. Therefore, in a general vehicle, the front wheels tend to lock before the rear wheels.

[0005]

Therefore, at the time of braking turning,
In particular, during sudden braking during high lateral acceleration turning, the front wheel cornering force is reduced with respect to the rear wheel cornering force due to the front wheel locking, and the vehicle follows a turning trajectory that expands outward in the turning direction and tends to understeer. Becomes

[0006] On the other hand, an anti-skid control device for preventing a brake lock of a wheel may be provided in a brake device of a vehicle. When the slip ratio of the wheel exceeds a set slip ratio, the braking force of the wheel is reduced. There is a configuration in which anti-skid actuators for limiting brake fluid pressure) are individually provided in at least a pair of left and right wheel brake systems.

In this case, from the viewpoint that a difference in the braking force between the left and right wheels can be generated if the start of operation of the anti-skid actuator is made different between the left and right wheels, the present invention utilizes this to prevent the understeer tendency. The purpose is to do.

[0008]

SUMMARY OF THE INVENTION To this end, an anti-skid control device for a vehicle according to the present invention is provided with an anti-skid actuator for increasing the brake fluid pressure of a wheel when the slip rate of the wheel exceeds a set slip rate. A rear wheel brake fluid that is individually provided in at least a pair of left and right wheel brake systems to limit a rear wheel brake fluid pressure from rising above a set fluid pressure and to prevent a rear wheel from locking before a front wheel. In a vehicle provided with a pressure control valve, a front wheel is locked before a rear wheel by a lateral acceleration detecting means for detecting a lateral acceleration applied to the vehicle and a rear wheel brake fluid pressure control valve restricts an increase in rear wheel brake fluid pressure. In order to reduce the tendency of the vehicle to understeer, which occurs when the vehicle is turned, the larger the lateral acceleration is in response to the signal from the lateral acceleration detecting means, the more the set scan related to the outer wheel in the turning direction is. Tsu in which up rate was constructed and a set slip ratio changing means for changing the manner set slip ratio becomes smaller than the set slip ratio according to the turning direction inside wheel.

[0009]

[Function] The rear wheel brake fluid pressure control valve prevents the rear wheel from locking before the front wheel by restricting the rear wheel brake fluid pressure from rising above the set fluid pressure. It tends to lock before the ring. For this reason, at the time of braking turning, especially at the time of sudden braking during turning at high lateral acceleration, the front wheel cornering force is lowered first with respect to the rear wheel cornering force due to the front lock of the front wheel, and the vehicle expands outward in the turning direction. Such an understeer tendency occurs. On the other hand, when the slip rate of the corresponding wheel exceeds the set slip rate, the anti-skid actuator limits the brake fluid pressure of the corresponding wheel so that the wheel slip rate does not exceed the set slip rate. Performs anti-skid control to independently prevent brake locking of wheels.

By the way, the set slip ratio changing means sets the anti-skid actuator for the outer wheel in the turning direction to have a smaller slip ratio for the inner wheel in the turning direction as the lateral acceleration increases in accordance with the lateral acceleration detected by the lateral acceleration detecting means. The set slip ratio is changed so as to be smaller than the set slip ratio of the skid actuator. Therefore, during braking during turning with large lateral acceleration, the anti-skid actuator makes it easier to perform anti-skid control of the outer wheels than anti-skid control of the inner wheels by changing the set slip ratio, and the brake fluid pressure (braking force) of the outer wheels ) Is lower than that of the inner wheels to give the vehicle a yaw moment that increases the turning performance of the vehicle.

Accordingly, the tendency of the vehicle to understeer caused by the operation of the rear wheel brake hydraulic pressure control valve during braking during turning at a large lateral acceleration can be alleviated as described above. , The turning locus of the vehicle can be properly maintained. And the understeer tendency becomes stronger as the lateral acceleration is larger, but in the present invention, as the lateral acceleration is larger, the set slip rate of the anti-skid actuator for the outer wheel is larger than the set slip rate of the anti-skid actuator for the inner wheel. Since it is made smaller to make the braking force of the outer wheels smaller than the braking force of the inner wheels, the understeering tendency can be appropriately and appropriately reduced under any lateral acceleration.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an embodiment of an anti-skid control device according to the present invention, wherein 1 is a brake pedal, 2 is a brake master cylinder, 3L and 3R are left and right front wheels, 4L and 4R are left and right rear wheels, 5 is an engine, 6 is a transmission, Reference numeral 7 denotes a propeller shaft, and 8 denotes a differential gear. The engine 5 drives the rear wheels 4L, 4R via the transmission 6, the propeller shaft 7, and the differential gear 8 to drive the vehicle, and depresses the brake pedal 1 when braking the vehicle.

In response to the depression of the brake pedal 1, the master cylinder 2 outputs a master cylinder hydraulic pressure corresponding to the pedal depression force to the two systems 9F and 9R. The front wheel brake pedal system 9F branches to 9FL and 9FR to actuate the left and right front wheel cylinders 10L and 10R to brake the left and right front wheels, and the rear wheel brake system 9R branches to 9RL and 9RR and the right and left rear wheel cylinders 11L. , 11R to brake the left and right rear wheels.

The above is an ordinary hydraulic brake device.
Even though not shown, the rear wheel brake system 9R is further provided with a front wheel, which is more normal than a rear wheel, in order to prevent the rear wheel from locking before the front wheel due to load movement during braking and causing the vehicle to become unstable in course. It is assumed that a rear wheel brake fluid pressure control valve for limiting the rear wheel brake fluid pressure in a region above a certain brake fluid pressure so as to lock first is inserted. Therefore, the vehicle tends to lock the front wheels before the rear wheels, and when braking and turning, particularly during sudden braking during turning with high lateral acceleration, the front wheels are locked so that the front wheel cornering force is higher than the rear wheel cornering force. First, the vehicle tends to understeer such that the vehicle inflates outward in the turning direction. Moreover, the understeer tendency naturally increases as the lateral acceleration of the vehicle increases.

The brake systems 9FL, 9FR, and 9R have anti-skid actuators 12FL, 12FR, and 12FR, respectively.
12R are inserted, and the left front wheel 3L and the right front wheel 3R are individually controlled, and the left and right rear wheels 4L and 4R are commonly subjected to anti-skid control. These actuators all have a common configuration as shown in FIG. 2, and control the hydraulic pressure (brake hydraulic pressure) from the master cylinder 2 to the wheel cylinders 10L, 10R, 11L, 11R. For this reason, each of the actuators is a normally open inflow valve (EV valve) 21 that supplies hydraulic pressure from the master cylinder to the wheel cylinder to increase the brake hydraulic pressure.
A normally closed outflow valve (AV valve) 23 for appropriately reducing the pressure of the wheel cylinder to the accumulator 23 to reduce the pressure, and a pump 25 for returning the pressure in the accumulator 22 to the master cylinder 2 via the check valve 24. Constitute.

The EV valve 21 is closed while being turned on by the EV signal to stop the increase of the brake fluid pressure, and the AV valve 23 is opened while being turned on by the AV signal to reduce the brake fluid pressure.
The pump 25 is driven while the MR signal is supplied. Thus, each actuator is driven by an EV signal
When the valve 21 is turned on and closed, the brake fluid pressure is maintained at the value at this time in conjunction with the normally closed state of the AV valve 23. In this state, when the AV valve 23 is turned on and opened by the AV signal, the pump 25 is turned on by the MR signal. In conjunction with the drive, the brake fluid pressure is reduced and the AV valve 23 is turned off.
, And opening the valve by turning off the EV valve 21 can increase the brake fluid pressure toward the fluid pressure from the master cylinder 2.

Next, the controller 30 of each actuator will be described with reference to FIG. 1. The controller includes wheel speed calculation circuits 31FL, 31FR, 31R. The circuit 31FL is
The front left wheel speed (peripheral speed) V _FL is obtained based on the pulse signal from the left front wheel rotation sensor 32FL. The circuit 31FR obtains the right front wheel speed V _FR based on the pulse signal from the right front wheel rotation sensor 32FR.
Circuit 32R calculates an average circumferential speed V _R of the left and right rear wheels based on the pulse signal from the propeller shaft rotation sensor 32R.

The controller 30 further includes a select high switch 33, a pseudo vehicle speed calculation circuit 34, a buffer amplifier 35,
A threshold setting circuit 36FL, 36FR, 36R and a brake fluid pressure control circuit 37 are provided. Select-high switch 33 is set to select high wheel speed V _H and select the highest wheel speed closest to the vehicle speed of the wheel speeds _{V FL, V FR, V R} , and inputs it to the pseudo vehicle speed computing circuit 34. The simulated vehicle speed calculation circuit 34 selects the high wheel speed _VH , the deceleration _{xg of the} vehicle detected by the longitudinal acceleration sensor 38, and the actuators 12FL and 12F.
R, creating a pseudo vehicle speed V _i imitating the actual vehicle speed from the MR signals ORing MR signals to 12R, the threshold setting circuit 36FL it as a vehicle speed signal, 36FR, input to 36R.
The buffer amplifier 35 receives a signal Y relating to the lateral acceleration of the vehicle detected by a lateral acceleration sensor 39 as a lateral acceleration detecting means.
_g (see FIG. 3) and threshold setting circuits 36FL, 36FR
To enter.

The threshold value setting circuits 36FL, 36FR, 36R respectively provide target values S _FL , S for the left front wheel speed, the right front wheel speed, and the left and right rear wheel average speed.
_FR, and requests S _R, when the wheel speed of each is less than the corresponding target value, since the slip rate with respect to the vehicle speed V _i of the corresponding wheel exceeds the set slip rate, to anti-skid control the wheel Can be considered to be. Incidentally, the threshold value setting circuit 36R calculates the target value S _{R of the} average speed of the left and right rear wheels.
As usual, S _R = V _i × 0.95-4 such that the coefficient of friction between the wheel and the road surface is maximized (braking efficiency is maximized) and becomes a value near the wheel speed value corresponding to the ideal slip ratio.
Although determined by miles / h, the threshold setting circuit 36FL, 36FR are respectively the target value S _FR target value S _FL and the right front wheel value of the left front wheel speed
In the light of the object of the present invention, S _FL = V _i × 0.95−4 km / h + MAX is made to vary according to the lateral acceleration signal y _g.
(Y _g × 2.0,0) km / h and S _FR = V _i × 0.95-4km
/ H-MIN (y _g × 2.0, 0) km / h. Here, as shown in FIG. 3, the lateral acceleration signal y _g has a positive polarity when turning right and a negative polarity when turning left as shown in FIG.
Considering the polarity of _g , MAX (y _g × 2.0,0) is y _g
× 2.0 and the larger value of 0 is selected, and MIN (y _g
× 2.0, 0) means to select the smaller value of y _g × 2.0 and 0.

The left and right front wheel speed target values S _FL , S _FR are given by the polarity shown in FIG. 3 according to the turning direction of the lateral acceleration signal y _g , so that S _FL > S when turning right. _FR, when the vehicle is making a left turn is next to S _FL <S _FR, even when turning in either direction the target wheel speed in the turning direction outer front wheel becomes greater than the target wheel speed of the inner front wheel. This means that the set slip ratio of the outer front wheel is smaller than that of the inner front wheel, and the difference between the two becomes larger as the vehicle turns to a larger lateral acceleration based on the lateral acceleration signal (y _g ) characteristics shown in FIG. Therefore, the threshold setting circuit 36F
L and 36FR constitute the set slip ratio changing means in the present invention. Therefore, the threshold setting circuit 36F
[+ MAX (y _g × 2.0,
0)] and [−MIN (y _g × 2.0, 0)]. More specifically, (y _g × 2.0) indicates an understeer tendency (lateral acceleration y _g) caused by the operation of the above-described rear wheel brake hydraulic pressure control valve. represents the correction amount of the left and right front wheel speed target value for mitigating becomes significant) with increasing (set slip ratio of left and right front wheels), the coefficient of the lateral acceleration signal y _g "2.0" to the extent to be relaxed the understeer Accordingly, it can be arbitrarily determined by an experiment, a simulation, or the like.

The brake fluid pressure control circuit 37 determines the wheel speeds V _FL , V
_FR, V _R and their target values S _FL, S _FR, an input interface circuit 37a for taking the S _R, V _FL, left front wheel from S _FL is also V _FR, right front wheel from S _FR, further V _R, processor 37b and a storage device 37c the left and right rear wheels from S _R is determined whether it is the wheel speed to be anti-skid individually
And an EV signal, an AV signal, and an MR signal according to the determination result.
Constituted by an output interface circuit 37d which outputs a signal to each the actuator _{12 FL, 12 FR, 12 R} .

[0022] The brake fluid pressure control circuit 37 in accordance with the actuator 12 _FL, 12 _FR, 12 left through the front wheel _R 3L, right front wheel 3R
And the rear two wheels 4L and 4R are commonly subjected to anti-skid control. At this time, target wheel speeds S _FL , S _FR and S _R (set slip ratio) for determining whether or not to perform anti-skid control Is obtained as in the above equations, the following effects are obtained. That is, when the lateral acceleration y _g is 0, or when the vehicle is traveling straight or on a very low friction road, the target wheel speeds S _FL , S _FR , S
_R are all approximately the same as is apparent from the above equation;
Each wheel is anti-skid controlled as usual. By the way, in the turning state where the lateral acceleration y _g is large, a difference corresponding to the magnitude of the lateral acceleration y _g occurs between the target wheel speeds S _FL and S _FR of the left and right front wheels, and the target wheel speed of the front wheel outside the turning direction (right turning). (The time S _FL and the left turn S _FR ) are larger than the target wheel speed of the inner front wheel (in terms of slip ratio, the set slip ratio of the outer front wheel is smaller than the set slip ratio of the inner front wheel).

Therefore, at the time of braking during turning with large lateral acceleration, the actuator 12FL of the front wheel outside the turning direction (at the time of turning right) or
In 12FR (when turning left), the anti-skid control of the corresponding front wheel is easier to perform than the actuator of the inner front wheel, and the brake fluid pressure (braking force) of the outer front wheel is made lower than the brake fluid pressure (braking force) of the inner front wheel. . The difference between the left and right front wheel braking forces gives the vehicle a yaw moment that enhances the turning performance of the vehicle, and cancels the understeer tendency generated due to the operation of the rear wheel brake hydraulic pressure control valve during braking during turning with large lateral acceleration. Work like that. Then, it becomes stronger As this understeer tendency naturally increases the lateral acceleration y _g, left and right target wheel speed S _FL As increase of the lateral acceleration y _g as mentioned above, the difference in S _FR, i.e. increasing the lateral front wheel braking force difference Therefore, understeering tendency can be eliminated under any lateral acceleration and the turning trajectory of the vehicle can be properly maintained.

FIG. 4 shows an anti-skid actuator for each of the brake systems 9 _RL and 9 _RR of the left and right rear wheels so that the left and right rear wheels as well as the left and right front wheels are independently anti-skid controlled.
An application example of the present invention to a 4-channel anti-skid control device including 12RL and 12RR will be described. In this example, the rotation sensors 32RL and 32RR individually detect the rotation of the left and right rear wheels.
And the wheel speed calculation circuits 31RL and 31RR determine the rotational peripheral speeds V _RL and V _RR of the left and right rear wheels. These left and right rear wheel speeds are input to the select high switch 33 to be used as data of the select high wheel speed _VH , and are also input to the brake fluid pressure control circuit 37 via the lateral acceleration response changeover switch 40 and / or the select low switch 41. . Also provided are threshold setting circuits 36RL, 36RR for the left and right rear wheels, which are similar to the threshold setting circuits 36FL, 36FR for the left and right front wheels, and have no set slip ratio changing means for the rear wheels. The target values S _RL and S _RR are set so as to match the gist of the present invention based on the same logic as when calculating the left and right front wheel speed target values S _FL and S _{FR.
RL = V i × 0.95-4km / h} + MAX (y g × 2.0, 0)
km / h and S _RR = V _i × 0.95-4 km / h-MIN (y _g
× 2.0, 0) Calculated by km / h.

The changeover switch 40 responds to the lateral acceleration y _g detected by the sensor 39 and sets the position to the one-dot chain line while it is less than a set value, for example, 0.4 g, and determines the lower one of the left and right rear wheel speeds V _RL and V _RR. enter the left and right rear wheel speed signal to the brake fluid pressure control circuit 37 after selecting a select-low switch 41, the lateral acceleration y _g is 0.4 g or more right rear wheel speed becomes between the solid line position of V
_RL and _VRR are directly input to the brake fluid pressure control circuit 37 as left and right rear wheel speed signals.

Thus, in the present embodiment, the brake fluid pressure control circuit 37 controls the rear two wheels individually via the actuators 12RL and 12RR during anti-skid control in the same manner as the front two wheels during the turning of the changeover switch 40 at the solid line position. In addition, since the left and right rear wheel speed target values S _RL and S _RR are given as described above, the left and right rear wheels also have the same braking force difference between the left and right wheels as the left and right front wheels during braking during turning with large lateral acceleration. As a result, the inner rear wheel in the turning direction is more strongly braked than the outer rear wheel. After this
The wheels also provide the vehicle with a yaw moment that cancels the understeer tendency of the vehicle caused by the operation of the rear wheel brake fluid pressure control valve during braking during turning at a large lateral acceleration, thereby maintaining a proper turning trajectory. Can be. Further, the braking force can be effectively generated by independent anti-skid control of the left and right rear wheels, and the braking efficiency of the entire vehicle can be increased.

During the low lateral acceleration turning, the changeover switch 40
Becomes the one-dot chain line position, and the smaller one of V _RL and V _RR selected by the select low switch 41 is commonly used as the left and right rear wheel speeds to contribute to anti-skid control of the rear two wheels. When the lateral acceleration is reduced due to the road surface with different friction coefficients, the braking force of the left and right rear wheels can be kept almost the same. It is possible to prevent the vehicle from spinning when it is controlled.

This operation and effect is achieved by the left and right rear wheel speed target values S _RL ,
If S _RR is determined by the above equation, it is achieved to some extent. However, by providing the changeover switch 40 and the select low switch 41, this operation and effect is further ensured.

For the left and right rear wheel speed target values S _RL , S _RR ,
In place of the lateral acceleration y _g in each of the above-described calculation formulas, a variable A of the lateral acceleration y _g as illustrated in FIG.
(Up to the lateral acceleration ± 0.3 g and the dead zone) using, S _RL
= V _i × 0.95-4km / h + MAX (A × 2.0,0) km /
h and S _RR = V _i × 0.95-4 km / h-MIN (A × 2.0
, 0) km / h to obtain the left and right rear wheel speed target values S _RL , S _RR . In this case, in the small region where the lateral acceleration y _g is within 0.3 g, the variable A is 0 in the dead zone, so that the left and right rear wheel speed target values S _RL and S _RR can be made completely the same. While preventing the unnecessary left and right rear wheel braking force difference from occurring during the small lateral acceleration traveling and making traveling unstable,
It is possible to achieve the effect of reducing the understeer tendency generated due to the operation of the rear wheel brake hydraulic pressure control valve during braking during turning with the large lateral acceleration and maintaining the turning locus appropriately.

Although not shown as an alternative to the changeover switch 40 and the select low switch 41 in FIG. 4, the left and right rear wheel speeds V _RL and V _RR are processed as follows, respectively, to control the brake fluid pressure control circuit. A similar purpose can be achieved by providing a circuit for inputting to 37. That is, the lateral acceleration y _g variable B (value of 0 to 1) as shown in FIG. 6, the left and right rear wheel speed V _RL, V _RR
And the lower one (select low) is used as a weighting coefficient. For the rear left wheel speed V _RL , B · V _RL
+ (1-B) MIN (V _RL , V _RR ), and the right rear wheel speed V _RR is _calculated as B · V _RR + (1-B) MIN (V
_RL, and processed as V _RR), contribute to the anti-skid control V _RL after these processes, the V _RR as the actual value of the respective left and right rear wheel speed.

Here, MIN (V _RL , V _RR ) is the sensor 31
RL and 31RR indicate the smaller of the left and right rear wheel speed detection values V _RL and V _RR (select low). When the lateral acceleration y _g is 0, the weighting coefficient B is also 0, and the V after the above processing is performed. _RL ,
V _RR are both MIN (V _RL, V _RR), and the change-over switch
This corresponds to the right and left rear wheel speed information from the select low switch 41 to the brake fluid pressure control circuit 37 when 40 is at the position indicated by the one-dot chain line in FIG. By the way, when the lateral acceleration y _g becomes equal to or larger than the value that sets the weighting coefficient B to 1 (for example, the above-described 0.4 g for the changeover switch 40), V _RL and V _RR after performing the above-described processing become the sensors 31RL and 31RR, respectively. , And corresponds to left and right rear wheel speed information from the changeover switch 40 to the brake fluid pressure control circuit 37 when the changeover switch 40 is at the solid line position in FIG.

When the lateral acceleration y _g sets the weighting coefficient B to a value between 0 and 1, when the lateral acceleration y _g increases, the weighting coefficient B increases continuously between 0 and 1; As the lateral acceleration y _g increases, V _RL and V _RR after the above processing are gradually increased from MIN (V _RL , V _RR ), respectively, until they become the same values as the left and right rear wheel speed detection values of the sensors 31RL and 31RR. I do. Here, when the switches 40 and 41 are used as shown in FIG.
Left and right rear wheel speed information to 37 are left and right rear wheel speed detection values V _RL , V _RR
Smaller (select low) and sensors 31RL, 31RR
Abrupt change between the left and right rear wheel speed detection values
As described above, the left and right rear wheel speed information V _RL , V _RR is obtained by calculation using the weighting coefficient B that continuously changes between 0 and 1 according to the lateral acceleration y _g , and this is used for anti-skid control. Such a sudden change can be eliminated, and a sense of incongruity accompanying this can be avoided.

[0033]

As described above, the anti-skid control device of the present invention reduces the set slip rate of the anti-skid actuator for the outer wheel as compared to that for the inner wheel (in the illustrated example, the target wheel speed of the outer wheel) as the vehicle turns with a large lateral acceleration. Is larger than that of the inner wheel).
At the time of braking during the turn, the braking force of the outer wheel becomes smaller than the braking force of the inner wheel, and a yaw moment can be given to the vehicle to cancel the understeer tendency of the vehicle caused by the operation of the rear wheel brake hydraulic pressure control valve. In addition, the turning locus during the traveling can be appropriately maintained.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of an anti-skid control device according to the present invention.

FIG. 2 is a configuration diagram of an anti-skid actuator in FIG. 1;

FIG. 3 is an output signal diagram of a lateral acceleration sensor.

FIG. 4 is a system diagram showing another example of the anti-skid control device of the present invention.

FIG. 5 is a characteristic diagram of variables used by threshold setting circuits for left and right rear wheels in FIG. 4;

FIG. 6 is a characteristic diagram of variables used in the processing of left and right rear wheel speeds.

[Explanation of symbols]

 1 Brake pedal 2 Brake master cylinder 3L Left front wheel 3R Right front wheel 4L Left rear wheel 4R Right rear wheel 10L Left front wheel cylinder 10R Right front wheel cylinder 11L Left rear wheel cylinder 11R Right rear wheel cylinder 12FL Anti-skid actuator 12FR Anti-skid Actuator 12RL Anti-skid actuator 12RR Anti-skid actuator 31FL Wheel speed calculation circuit 31FR Wheel speed calculation circuit 31R Wheel speed calculation circuit 31RL Wheel speed calculation circuit 31RR Wheel speed calculation circuit 32FL Rotation sensor 32FR Rotation sensor 32R Rotation sensor 32RL Rotation sensor 32RR Rotation sensor 34 Simulated vehicle speed calculation circuit 36FL threshold setting circuit (setting slip rate changing means) 36FR threshold setting circuit (setting slip rate changing means) 36RL threshold setting circuit (setting slip rate changing means) 36R threshold setting circuit (setting slip rate changing) Means) 37 Brake fluid pressure control circuit 39 Lateral acceleration sensor (lateral acceleration detecting means) 40 Lateral acceleration response changeover switch 41 Select low switch

Claims (1)

(57) [Claims] An anti-skid actuator is provided in each of at least one pair of left and right wheel brake systems for limiting a brake fluid pressure of the wheel when the slip ratio of the wheel exceeds a set slip ratio. Lateral acceleration that detects the lateral acceleration applied to the vehicle in a vehicle equipped with a rear wheel brake hydraulic pressure control valve that limits the pressure in the range above the set hydraulic pressure and prevents the rear wheels from locking before the front wheels Detecting means for reducing the tendency of the vehicle to understeer which occurs when the front wheels are locked before the rear wheels due to the increase in the rear wheel brake fluid pressure by the rear wheel brake fluid pressure control valve. As the lateral acceleration increases in response to the signal, the setting slip ratio is set so that the set slip ratio of the outer wheel in the turning direction is smaller than the set slip ratio of the inner wheel in the turning direction. An anti-skid control device for a vehicle, comprising: a set slip ratio changing means for changing a slip ratio.