JPH08337162A - Braking device for vehicle - Google Patents

Abstract

PURPOSE: To converge the wheel speed of right and left driving wheels by applying the first braking hydraulic pressure to a driving wheel with larger acceleration slip condition when this driving wheel reaches the prescribed acceleration slip condition, and applying the second braking hydraulic pressure related to the first braking hydraulic pressure to the other driving wheel. CONSTITUTION: A master cylinder 3 is provided with two pressure chambers to discharge the brake oil of same pressure, and the respective pressure chambers are connected to feed tubes 20, 30. The feed tube 20 is connected to a brake tube 21 communicated with a wheel cylinder 5 of a left front wheel and a brake tube 22 communicated with a wheel cylinder 6 of a right rear wheel through a first switch valve 101. The feed tube 30 is similarly connected to a brake tube 31 communicated with a wheel cylinder 4 of a right front wheel and a brake tube 32 communicated with a wheel cylinder 7 of a left rear wheel through a first switch valve 102. The first braking hydraulic pressure is applied in the prescribed acceleration slip and further the second braking hydraulic pressure is applied to the wheel cylinders 4-7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle brake device for improving acceleration performance and safety by preventing acceleration slip due to excessive driving force at the time of starting and accelerating left and right drive wheels of a vehicle.

[0002]

2. Description of the Related Art Conventionally, devices of this type are known, for example, those disclosed in JP-A-57-22948 and JP-A-58-16948. In the former, a multistage pump driven by a motor supplies pressure to an auxiliary pressure conduit, and a 3-port two-position directional control valve operates according to brake pressure to supply pressure to a return conduit when not braking. . When the valve operates according to the acceleration slip of the wheels, pressure is supplied to the brake cylinders of the left and right wheels through the valve,
Braking force is being applied to the slipping drive wheels.

In the latter case, an electronic evaluation circuit is provided, and the driven rear wheels and the like are controlled based on the signals from the wheel sensors. Further, the circuit is provided with signal processing means,
A signal characteristic of the slip value of the rear wheels and a signal proportional to the vehicle speed are output. This slip value is compared with the maximum threshold value at which the slip of the drive wheel is allowed by a comparator, the application of the braking force is controlled, and the drive torque of the drive wheel is reduced.

[0004]

However, in this prior art, when the slip states of the left and right drive wheels are different, for example, when starting and accelerating on a cross road where the left and right road surfaces are uneven, each drive wheel is independent. When the control is performed in the above manner, the action of the differential device interposed between the drive shafts connecting the left and right drive wheels alternately increases and decreases the braking force to the left and right drive wheels alternately on the left and right, and the fluctuations in the wheel speeds increase. Therefore, there is a problem in that the fluctuation is transmitted to the steering wheel, and the operation feeling and the acceleration performance are deteriorated.

Therefore, in the present invention, the left and right drive wheels are provided so that the drive force on the drive wheels on the high friction road side can be sufficiently secured when an acceleration slip state occurs due to an excessive drive force when the underside of the left and right drive wheels is uneven. The purpose of the present invention is to make the wheel speed of the driving wheels converge to achieve both steering operation feeling and acceleration.

[0006]

According to the present invention, when the left and right driving wheels having a larger acceleration slip state reach a predetermined acceleration slip state, the wheel braking force of the driving wheels is generated. A first brake fluid pressure applied to the means, and a first brake fluid set to the wheel braking force generation means of the other drive wheel in accordance with the wheel behavior difference between the left and right drive wheels. There is an application means for applying a second brake fluid pressure related to the pressure.

Therefore, the second brake fluid is added to the drive wheel whose acceleration slip state is small and has not reached the predetermined acceleration slip state. For example, the road surface under the drive wheel is a high friction road. , Even when this drive wheel has almost no acceleration slip,
Brake fluid pressure is applied. At this time, the second brake fluid is supplied in accordance with a wheel behavior difference such as a wheel speed difference between the left and right driving wheels.
It is set based on the first brake hydraulic pressure.

Next, the wheel behavior when the first brake fluid pressure and the second brake fluid pressure are applied to each drive wheel will be described. When the first brake fluid pressure is applied to the wheel braking force generating means of the drive wheel that has reached the predetermined acceleration slip state, the wheel speed of the drive wheel is reduced by the wheel braking force to cause the slip state. Will recover. At this time, the driving force reduced in this drive wheel is increased to the other drive wheel via the actuating device. Since the other drive wheel is the drive wheel with the smaller slip state, the road surface state under the drive wheel originally has a high friction coefficient. Therefore,
The other drive wheel can receive a large road surface reaction force and can obtain a large vehicle body propulsion force. However, as described above, if almost all of the driving force for the above-mentioned reduction is added to the other driving wheel, the slip state may increase even on this driving wheel on the high friction road side, and the vehicle body propulsion force will decrease. There is a possibility that However, by applying the second brake hydraulic pressure to the other driving wheel as well, the driving force for the reduction can be adjusted, and the vehicle body propulsion force at this driving wheel can be adjusted. Can be accurately secured.

As described above, the slip of the drive wheel having the larger slip state can be accurately reduced and the vehicle propulsion force can be sufficiently secured. A traction control pump and a wheel cylinder can be cited as specific examples of the brake fluid pressure generation source and the wheel braking force generation means.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on embodiments shown in the drawings. FIG. 1 shows an embodiment of the present invention, which is a vehicle brake having a simple configuration and a function of performing anti-skid control and traction control. This embodiment is an example in which the present invention is applied to a so-called FF (front wheel drive) vehicle,
As is well known, the brake system has X piping, and brake fluid is supplied to the wheel cylinder 4 for the right front wheel and the wheel cylinder 7 for the left rear wheel from the pipeline of the same system, and to the wheel cylinder 5 for the left front wheel. Brake oil is supplied to the wheel cylinder 6 of the right rear wheel from a pipeline of the same system. The brake pedal 1 is connected to the master cylinder 3 via a vacuum booster 2, and the brake pedal 1
The hydraulic pressure generated in the master cylinder 3 by stepping on is transmitted to the wheel cylinders 4, 5, 6, 7 of the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel through the pipelines as described later. , The braking action is performed. As is conventionally known, the vacuum booster 2 guides a negative pressure generated in the intake manifold of the engine and urges a push rod connected to the piston of the master cylinder 3 in response to the depression of the brake pedal 1 to drive the vehicle. Reduce the pedal effort on the brake pedal.

The master cylinder 3 has two pressure chambers (not shown) for discharging the brake fluid of the same pressure, and supply pipes 20 and 30 are connected to the respective pressure chambers. The supply pipe 20 is connected to a brake pipe 21 that communicates with the wheel cylinder 5 for the left front wheel and a brake pipe 22 that communicates with the wheel cylinder 6 for the right rear wheel via the large 1 switching valve 101. The first switching valve 101 is a 3-port 2-position valve,
In the illustrated first position, the supply pipe 20 is connected to each of the technique tubes 21,
22 and disconnects the supply pipe 20 from the respective technique tubes 21 and 22 at a second position different from that shown in the drawing.

Similarly, the supply pipe 30 is also connected via a first switching valve 102 to a brake pipe 31 communicating with the wheel cylinder 4 for the right front wheel and a brake pipe 32 communicating with the wheel cylinder 7 for the left rear wheel. . The first switching valve 102 is the first
Like the switching valve 101, it is a three-port two-position valve, in which the supply pipe 30 communicates with the technique tubes 31 and 32 at the first position shown, and the supply pipe 30 at the second position different from that shown.
Is cut off from each of the technique tubes 31 and 32.

A conventionally known proportioning valve 103 is provided in the middle of the brake pipes 22, 32 connected to the wheel cylinders 6, 7 for the rear wheels, and when the hydraulic pressure exceeds a certain value, the master cylinder 3 Brake oil having a pressure lower than the discharge pressure is supplied to the wheel cylinders 6 and 7 of the rear wheels. With the above-described configuration, the normal braking action is performed, and the hydraulic pressure generated in the master cylinder 3 by the depression of the brake pedal 1 is supplied to the wheel cylinder 5 of the left front wheel via the supply pipe 20 and the brake pipe 21, and to the supply pipe 20 and the brake. To the wheel cylinder 6 of the right rear wheel via the pipe 22, to the wheel cylinder 4 of the right front wheel via the supply pipe 30 and the brake pipe 31, to the wheel cylinder 7 of the left rear wheel via the supply pipe 30 and the brake pipe 32. , Respectively transmitted.

Next, the antiskid control system will be described. The pumps 8 and 9 are rotatably driven by the motor 10, suck the brake oil from the branch pipes 51 and 61 of the hydraulic pipes 50 and 60 communicating with the reservoir 11, respectively, and supply the oil to the supply pipe 7
Supply to each wheel cylinder 4, 5, 6, 7 via 9, 80. The branch pipe 71 of the supply pipe 70 can communicate with the technical pipe 33 of the brake pipe 31 via the second switching valve 104,
A diaphragm 91 is provided in the middle of the branch pipe 71. The second switching valve 104 is a three-port two-position valve, one discharge port is connected to the branch pipe 33, and the other discharge port is the oil pipe 50.
Is connected to the branch pipe 35 of the. Then, the second switching valve 104
Causes the branch pipe 71 to communicate with the branch pipe 33 at the illustrated first position, and allows the branch pipe 33 to communicate with the branch pipe 55 at a second position different from the illustrated position. Therefore, the second switching valve 104
Is in the first position, the brake fluid discharged from the pump 8 passes from the supply pipe 70 through the branch pipe 33 to the wheel cylinder 4
When the second switching valve 104 is in the second position, the brake oil in the wheel cylinder 4 is supplied from the branch pipe 33 to the oil pipe 50.
To the reservoir 11 through.

Similarly, the branch pipe 72 of the supply pipe 70 can be communicated with the branch pipe 34 of the brake pipe 32 through the second switching valve 105, and the branch pipe 72 is provided with a carving 92. One discharge port of the second switching valve 105 is connected to the technique tube 34,
The other discharge port is connected to the branch pipe 52 of the oil pipe 50.
Therefore, the second switching valve 105 connects the branch pipe 72 to the branch pipe 34 at the first position shown in the drawing to guide the brake oil discharged from the pump 8 to the wheel cylinder 7, and the second position different from that shown in the drawing. The branch pipe 34 is communicated with the branch pipe 52 to release the brake fluid in the wheel cylinder 7 to the reservoir 11.

The branch pipe 81 of the supply pipe 80 is the second switching valve 106.
Through the branch pipe 27 of the brake pipe 21,
The branch pipe 81 is provided with a diaphragm 93. Second switching valve 106
One discharge port is connected to the branch pipe 27, and the other discharge port is connected to the branch pipe 62 of the oil pipe 60. Thus, the second switching valve 106 is provided with the time branch pipe 8 in the illustrated first position.
1 to communicate with the branch pipe 27 to guide the brake fluid discharged from the pump 9 to the wheel cylinder 5, and
When in the position, the branch pipe 27 communicates with the branch pipe 62 to release the brake fluid in the wheel cylinder 5 to the reservoir 11.

The branch pipe 81 of the supply pipe 80 is the second switching valve 106.
Through the branch pipe 27 of the brake pipe 21,
The branch pipe 81 is provided with a diaphragm 93. Second switching valve 106
One discharge port is connected to the branch pipe 27, and the other discharge port is connected to the branch pipe 62 of the oil pipe 60. Thus, the second switching valve 106 is provided with the time branch pipe 8 in the illustrated first position.
1 to communicate with the branch pipe 27 to guide the brake fluid discharged from the pump 9 to the wheel cylinder 5, and
When in the position, the branch pipe 27 communicates with the branch pipe 62 to release the brake fluid in the wheel cylinder 5 to the reservoir 11.

Similarly, the branch pipe 82 of the supply pipe 80 is connected to the branch pipes 28 and 63 via the second switching valve 107, and the second switching valve 107 is in the first position when the wheel cylinder 6 is in the first position. The brake fluid is guided to the second position, and when the brake fluid is in the second position, the brake fluid in the wheel cylinder 6 is released to the reservoir 11. The supply pipe 20, the first switching valve 101, and the branch pipe 21
A pressure switch 41, which is a pressure detection means for observing the pressure before and after the first switching valve 101, is arranged in a pipe line connecting the two. The pressure switch 41 simultaneously detects the pressure PM in the supply pipe 20 under the pressure of the master cylinder 3 and the pressure PW in the branch pipe 21 under the pressure of the wheel cylinder 3, and PW is a predetermined value. When it becomes larger than PM, it closes and sends a close signal to the ECU 130. Upon receiving this signal, the ECU 130 opens the first switching valve 101 at a very end time.

Further, the supply pipe 30 and the first switching valve 10
A pressure switch 43 for detecting the pressure before and after the first switching valve 1-2 is arranged in a pipe line connecting the branch pipe 2 and the branch pipe 31.
This pressure switch 43 also simultaneously detects the pressure PM in the supply pipe 30 under the pressure of the master cylinder 3 and the pressure PW in the branch pipe 31 under the pressure of the wheel cylinder 4, and PW is a predetermined value. When the value is larger than the value and larger than PM, it is closed and a closing signal is sent to the ECU 130. Upon receiving this signal, the ECU 130 opens the first switching valve 102 in an extremely short time.

The suction side and the discharge side of the pumps 8 and 9 are connected by relief pipes 73 and 83, respectively, and the control valves 111 and 11 are connected to the relief pipes 73 and 83, respectively.
2, Relief valves 109 and 110 are provided. Control valve 1
Reference numerals 11 and 112 respectively connect the relief pipes 73 and 83 when in the first position shown, and shut off the relief pipes 73 and 83 when in the second position different from the shown position. Relief valve 1
The pressures of the supply pipes 30 and 20 are guided to the pressure pipes 09 and 110 via the conduits 14 and 15, respectively, and the relief pipes 73 and 83 are communicated in accordance with the pressures to control the discharge pressures of the pumps 8 and 9. That is, when the control valves 111 and 112 are in the first position, the discharge pressure of the pumps 8 and 9 is substantially equal to the pressure inside the supply pipes 30 and 20.

The anti-skid control is performed when it is determined that one of the wheels is locked, in other words, when it is determined that the wheel deceleration or the slip ratio is too large. The wheel deceleration and slip rate are controlled by an electric control unit (EC
U) 130 and for this reason wheel speed sensors 121, 122, 123, 124 are provided in the vicinity of each wheel. When the ECU 130 determines to start the anti-skid control, it switches the first switching valves 101, 102 from the first position to the second position. When the anti-skid control device is used, the second switching valves 104, 105, 106, 107 are set to the wheel positions. It is switched by duty control according to the deceleration and slip ratio of.

Next, the acceleration slip prevention control of the left and right drive wheels which occurs when the vehicle is suddenly started will be described. The wheel speed sensors 121, 122, 123, and 124 simultaneously detect the driving wheel speed and the driven wheel speed, and when the driving wheel speed exceeds the driven wheel speed by a predetermined value or more, the ECU 130 determines that the driving wheel is slipping. First, the first switching valves 101, 102 are switched to the second position, and the supply pipes 20, 3
Cut off 0. Along with that, pressure switches 41, 43
The return control function by is prohibited. Then, the motor 10 is rotated to drive the pumps 8 and 9, and at the same time, the control valve 11
1, 112 to the second position and the relief pipes 73, 83
Shut off. At the same time, the second switching valves 105, 107
To prevent the braking force from being applied to the driven wheels.
Therefore, the pumps 8 and 9 can send out pressure oil having a pressure higher than the pressure of the master cylinder 3 to the supply pipes 70 and 80. Then, the second switching valves 104 and 106 are duty-controlled according to the slip state of the drive wheels, and the pressure oil from the pumps 8 and 9 is used to drive the wheel cylinders 4 of the left and right front wheels.
5 to suppress slip. In this embodiment, the driving wheels are the left and right front wheels, but in the case of driving the rear wheels, the second switching valves 105 and 107 are switched to suppress the slip of the left and right rear wheels.

When the left and right drive wheels have different slip states, the pressure applied to the wheel cylinder on the low friction road surface side and the wheel on the high friction road surface side depend on the magnitude of the slip ratio between the drive wheel speed and the driven wheel speed. The difference between the pressure applied to the cylinders is initially zero, and the hydraulic pressures of both wheel cylinders are set so as to have a certain difference as the slip of the wheels on the low friction road surface side becomes smaller. Then, the second switching valves 104 and 106 are duty-controlled so that the set value is obtained,
The braking hydraulic pressure is controlled by reducing or increasing the hydraulic pressure of the wheel cylinders 4, 6.

By performing such control, the starting and acceleration of the vehicle in which the driving force on the high friction road surface is larger than the driving force on the low friction road surface are improved. Next, the duty control will be described. The hydraulic pressure by duty control is shown in FIG. 2, wherein the characteristic line A in FIG. 2 shows the actual braking hydraulic pressure value of the wheel cylinder, and the characteristic line B shows the calculated braking hydraulic pressure value inside the computer. In the figure, a certain time T
The duty control is performed (for example, 32 msec) by variably controlling the time d _0, d _1, ... For increasing the hydraulic pressure. Therefore, if the time d _1, d _2, ... Is set to be long, it can be variably controlled to the pressure-increasing side, and if it is set to be short, the pressure-decreasing side can be variably controlled.

In this control, the pressure increase shows a substantially constant gradient due to the characteristics of the hydraulic pump, while the pressure reduction is determined by the squeeze and the oil viscosity, and exhibits an exponential pressure reduction characteristic. As can be seen from the figure, the difference between the braking oil pressure value P _XO inside the computer, which is set to the maximum oil pressure value of the hydraulic pump as an initial value, and the actual braking oil pressure value P _XO ^′ gradually decreases, and Since the braking hydraulic pressure of 1 converges to a value that is substantially the same as the actual braking hydraulic pressure, it is possible to detect the braking hydraulic pressure. This is for the following reason. That is, if the hydraulic pressure characteristics are both linear and decrease at the same rate, the differential pressure between the two is constant, the error between the two is not narrowed, and the hydraulic pressure in the computer does not approach the actual braking hydraulic pressure. However, due to the characteristic of the exponential function, the rate of decrease of the hydraulic pressure value increases as the hydraulic pressure value increases, so even if the calculated hydraulic pressure inside the computer is set to a large value, it decreases exponentially and both This is because the hydraulic pressure values of 1 will approach each other in a short time. The hydraulic pressure of the left and right wheel cylinders is controlled by the hydraulic device.

When the road frictions on the left and right sides are different, in order to prevent the wheels from slipping alternately due to the differential device to make the traveling unstable, it is necessary to reduce the fluctuation of the driving torque on the wheels which do not slip. The braking force is applied to the non-slip wheel side in association with the slipping wheel. That is, FIG. 3 (a), (b), (c)
As shown in Fig. 5, when slip occurs on one of the wheels and the braking pressure is started, the braking pressure is started to be applied to the wheel on the side where the slip is not generated at the same time, and thereafter, overbraking is prevented. Further, in order to effectively use the driving force on the high friction road surface side and improve the acceleration performance, a difference is provided so that the braking pressure becomes lower than that of the wheel side on which the slip has occurred earlier. The oil pressure value on the so-called low friction road surface side is taken in, and the oil pressure difference between the oil pressure value on the high friction road surface side is controlled to enable stable start-up and acceleration with good acceleration.

Next, the flowchart of FIG. 4 for executing the above control will be described. This flowchart shows a fixed cycle,
For example, it is performed every 32 msec. The processing operation for one cycle will be sequentially described below. First, in step 100, the wheel speed Vw from each wheel speed sensor 5-9 is read, and it is determined based on this wheel speed Vw that the difference between the speed of the driven wheel and the speed of the driven wheel reaches a predetermined level. Then, the acceleration slip of at least one of the left and right driving wheels is detected, and the target hydraulic pressure is calculated.

Next, at step 120, it is detected that the speed difference between the left and right driving wheels has reached a predetermined level, and it is detected that the road surfaces of the left and right driving wheels are uneven.
Next, at step 130, the setting difference of the target hydraulic pressure to be applied to the wheel cylinders of the left front wheel and the right front wheel is calculated by the following equation (1). ΔK = Ka−kb · | WP high μ−WP low μ | (1) After that, in step 140, the setting condition is subtracted from the target hydraulic pressure on the high μ road side and the target hydraulic pressure on the low road side. Make a comparison. When it is determined in this step that the target hydraulic pressure is larger than the one with the set difference, that is, because the road surface μs of the left and right wheels are different, the target hydraulic pressure obtained by the calculation is more than that with the set difference. When it becomes smaller, in step 150, the calculated value obtained by taking the setting difference from the target oil pressure on the low μ road side is set as the target oil pressure on the high μ side by the following equation (2).

P high μ = maximum value · (P low μ−ΔK, P high μ) (2) The target hydraulic pressure set in the above step 150 ′, 160 or 170 is duty controlled in step 190 and below. . That is, in step 190, P _{MAX and} P _MIN are obtained from the current estimated hydraulic pressure value Px. P _NAX is an estimated hydraulic pressure value that is expected to be reached at the end of the cycle when the duty ratio is 100%, that is, when the command signal including only the pressure increase command portion is output to the second switching valves 104 and 106, P _MIN
Is an estimated hydraulic pressure value that is expected to be reached at the end of the cycle when a duty ratio of 0%, that is, a command signal including only the pressure reduction command portion is output to the second switching valves 104 and 106.

Next, at step 200, the target hydraulic pressure value Py is compared with P _MAX, P _MIN . If Py ≦ P _MIN, the duty ratio D is 0% in step 210,
That is, the duty ratio D for creating the command signal consisting only of the pressure reduction command portion is set, and P _MIN is set to Px, that is, the next current hydraulic pressure value (step 220).

On the other hand, when Py ≧ P _NAX , in step 230, the duty D is set to 100%, that is, the duty ratio for creating the command signal consisting of only the pressure increase command component, and P _NAX is set to Px. (Step 240). If P _MIN <Py <P _MAX , step 250
The duty ratio D is obtained from the map of FIG. 5 showing the relationship between Px and Py (interpolation calculation is added if necessary), and Py set in step 260 is set as Px.

Here, an arithmetic expression instead of the map is expressed by the following equation. Py = (Px + 0,344d) * 0.5e-0.0021 (32-d) (3) (e is a natural logarithm) In this formula, d is a parameter representing the pressure increasing time in one cycle of 32 _msec . .

An exciting current pulse based on the duty ratio D set in steps 230, 240 and 260 is output to the second switching valves 104 and 106 (step 27).
0). Traction control is performed by repeating this process, which is shown in a time chart of FIG. In the figure, after the brake pressure has started to rise (T ₂ ) and after the same pressure (T ₃ ), duty control is performed so that the braking hydraulic pressure value independently produces a predetermined hydraulic pressure difference between the left and right wheels. Recognize.

Although the above-described embodiment is applied to a vehicle driven by front wheels, it can be similarly applied to a vehicle driven by rear wheels, in which case the control of the rear wheels to be the driving wheels is performed. Acceleration slip control can be performed by power control. In addition, although a vehicle braking system that is used for both anti-skid control and traction control is shown, any other type of braking system can be used as long as it can independently adjust the braking force to the left and right driving wheels by a control signal. It may be one.

Further, as the slip detecting means, a means for comparing the driving wheel speed and the driven wheel speed is shown, but a means for comparing the driving wheel speed and the vehicle body speed of the vehicle obtained by radar or the like, or the driving wheel acceleration. It may be one that compares the set value. Further, as the control means, the one in which the brake system is duty-controlled is shown, but if the braking force of each of the left and right driving wheels is controlled to a target value, the simple ON,
It may be off-controlled or continuously controlled.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing the hydraulic characteristic of FIG.

3 (a), (b) and (c) are characteristic diagrams showing the operation of traction control.

FIG. 4 is a flowchart showing a calculation process of an ECU in FIG.

FIG. 5 is a characteristic diagram showing a duty ratio of a target hydraulic pressure value to a control hydraulic pressure value.

FIG. 6 is a waveform diagram showing a traction control state.

[Explanation of symbols]

8, 9 Pump (corresponding to brake fluid pressure generation source) 4 to 7 Wheel cylinder (corresponding to wheel braking force generating means) 104, 106 Second switching valve (corresponding to applying means)

Claims (3)

[Claims] 1. A brake fluid pressure generation source for generating a brake fluid pressure for applying a wheel braking force to each wheel of a vehicle, and a brake fluid pressure from the brake fluid pressure generation source for receiving left and right drive wheels. Wheel braking force generating means capable of independently applying a wheel braking force to each, wheel speed detecting means for detecting respective rotation speeds of the left and right driving wheels, and a wheel speed signal from the wheel speed detecting means. ,
When the acceleration slip state detection means for detecting the acceleration slip state of each of the left and right drive wheels, and the drive wheel of the larger acceleration slip state in the left and right drive wheels has reached a predetermined acceleration slip state,
The first brake hydraulic pressure is applied to the wheel braking force generating means of the drive wheel, and the wheel braking force generating means of the other drive wheel is subjected to the wheel behavior difference between the left and right drive wheels. An application means for applying a second brake fluid pressure related to the set first brake fluid pressure, and a vehicle brake device. 2. The vehicle brake device according to claim 1, wherein the applying unit uses a wheel speed difference between the left and right driving wheels as the wheel behavior difference. 3. A valve provided between the brake fluid pressure generation source and the wheel braking force generation means when the second braking fluid pressure is applied to the wheel braking force generation means. The brake device for a vehicle according to claim 1, wherein the pressure is adjusted by performing duty control on the disconnection and communication of the vehicle.