JPH10310045A - Vehicle brake system - Google Patents

Abstract

(57) [Summary] [PROBLEMS] The first in one piping system during vehicle braking
And by adjusting the brake fluid pressure of the second wheel,
To provide a vehicle brake device capable of improving braking performance. In step 230, a wheel slip amount Xs is calculated for each wheel. In step 250, it is determined whether or not the wheel is approaching the road surface limit by determining the wheel slip amount Xs
Is greater than or equal to a predetermined reference value KXs. In step 260, for example, since it is determined that the right front wheel FR is approaching the road surface limit, the first pressure reducing control valve 1
5 is communicated, the brake fluid is released from the first wheel cylinder 9 to the reservoir 17, and the first wheel cylinder pressure is reduced. In step 270, the pump 23 is driven to pump up the brake fluid from the reservoir 17, increase the second wheel cylinder pressure, and increase the braking force of the left rear wheel RL.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake device for a vehicle, and more particularly to a brake device for a vehicle in which a braking force is adjusted by an occupant operating a brake pedal.

[0002]

[Prior art]

a) Conventionally, as a control at the time of vehicle braking, a slip state of a wheel is detected, and when the slip state of the wheel becomes a predetermined value or more (for example, when a slip ratio becomes a reference value or more), the slip state is determined. For optimal control,
A so-called anti-skid control that adjusts a braking force by reducing a wheel cylinder pressure is known.

A brake device for performing the above-described anti-skid control and the like is provided with a pipe for supplying brake fluid pressure to wheel cylinders of four wheels, and this pipe is formed from the viewpoint of safety and the like. For example, two pipes extending from the master cylinder, such as X pipes and front and rear pipes, are employed. That is, two cylinders of wheel cylinders are connected to each piping system.

B) Japanese Patent Laid-Open Publication No. 61-20296
An anti-skid control device described in Japanese Patent Laid-Open Publication No. 5 is also known. In this anti-skid control device, the pump discharge is connected to a wheel cylinder, and the pressure of the hole cylinder is increased by the pump during anti-skid control. Therefore, during the anti-skid control, unless the wheel cylinder pressure becomes higher than the master cylinder pressure, the brake fluid due to the pump discharge does not flow to the master cylinder side,
ぺ Dull feeling is improved.

[0005]

However, in the technique a), in the brake device for performing anti-skid control with the above-described structure having the piping, for example, at the time of turning, one of the piping systems, for example, the inside of the piping system is used. When a wheel approaches the road surface limit, it may simply prevent the master cylinder pressure of the wheel from being reduced, so the wheel lock of the wheel may be prevented. Since the hydraulic pressure is reduced, there is a problem that the braking force is reduced as a whole.

Accordingly, the present invention provides a vehicle brake device capable of improving braking performance by adjusting brake hydraulic pressures of first and second wheels in one piping system during vehicle braking. As a first object. b) In the technique a), as shown in FIG. 1 of the above-mentioned publication, in the conventional anti-skid device, the pipe 21 and the check valve 31, the pipe 30 and the check valve 3
4, the brake fluid pressure higher than the master cylinder pressure could not be applied to the wheel cylinders.

Therefore, for example, when the anti-skid control is started in one wheel and the wheel cylinder pressure is reduced, the suction and discharge by the pump can only be performed by discharging the brake fluid corresponding to the reduced pressure flowing into the reservoir. , The brake fluid for the reduced pressure is not used effectively.

In view of such a point, in the present invention, the brake fluid depressurized in one wheel is effectively used to increase the pressure of the other wheel, for example, higher than the master cylinder pressure, thereby improving the stability of the vehicle body behavior, or A second object is to shorten the braking distance.

[0009]

[Means for Solving the Problems]

a) Therefore, the following first to eighth aspects of the present invention are employed to achieve the first object. In other words, according to the first aspect of the present invention, the pedaling force of the occupant is transmitted from the brake pedal to a brake fluid pressure generating means (for example, a master cylinder) to generate brake fluid pressure. This brake fluid pressure is applied to first and second wheel braking force generating means (for example, a wheel cylinder) via the first pipe line, and a braking force is generated at the first and second wheels.

When the determining means determines that the first wheel has approached the road surface limit, the first control means causes the brake fluid pressure generating means and the first hydraulic pressure generator to pass through the first conduit. The brake fluid in the wheel braking force generating means is simultaneously stored in the storing means (for example, a reservoir). Further, when the first control means is executed, the brake fluid stored in the storage means is discharged into the first conduit by the suction and discharge means (for example, a pump) substantially simultaneously.

That is, according to the present invention, for example, when one wheel (first wheel) of two wheels of one piping system reaches a road surface limit, it is communicated with the wheel cylinder of the first wheel. The brake fluid is allowed to escape from the first pipeline to the reservoir to temporarily reduce the wheel cylinder pressure of the first wheel, thereby preventing the first wheel from reaching the road surface limit. At the same time, the brake fluid is sucked from the reservoir by the pump and supplied to the first conduit, so that the wheel cylinder pressure of the other wheel (second wheel) can be increased. As a result, the braking force of the second wheel increases, so that the braking force as a whole in one piping system and, consequently, the braking force in the entire vehicle are improved.

That is, in the present invention, for example, the brake fluid of the wheel cylinder of the first wheel approaching the road surface limit is
Since it is possible to simply move to the wheel cylinder of the second wheel (far from the road surface limit), the braking force can be increased as a whole.

When the brake fluid is stored in the reservoir, the master cylinder pressure is also temporarily reduced, so that the pedal reaction force is reduced. Therefore, even if the occupant's stepping state is constant, the brake pedal moves in the pressing direction, and at the same time, the pump is pumped up. Therefore, the wheel cylinder pressure of the second wheel is increased by the pressing amount. It will increase further, which will increase the braking force.

When the pump is discharged while the brake pedal is depressed, almost no pedal reaction force (feeling of plate pressure) is given to the occupant, so that there is no influence of the pedal reaction force (for example, a feeling of pushing back the brake pedal). . According to the second aspect of the present invention, when the determining means determines that the first wheel approaches the road surface limit, the first control means generates the brake fluid pressure via the first conduit. Means and the brake fluid in the first wheel braking force generating means are simultaneously stored in the storing means. Similarly, when the determining means determines that the second wheel is approaching the road surface limit, the second control means causes the brake fluid pressure generating means and the second wheel to be connected via the first conduit. The brake fluid in the braking force generating means is simultaneously stored in the storing means.

When the first control means or the second control means is executed, the suction and discharge means discharges the brake fluid stored in the storage means into the first conduit substantially simultaneously. . In other words, in the present invention, when each wheel reaches the road surface limit, for example, the brake fluid is released from the wheel cylinder of each wheel to the reservoir, and the wheel cylinder pressure is reduced. Can be prevented. At the same time, the first
Since the brake fluid is discharged to the pipeline of the first control means or the second control means, it is possible to increase the wheel cylinder pressure of the wheel on the side on which the first control means or the second control means is not executed.
Since the braking force of the wheels can be increased, the braking force of the vehicle can be improved as a whole.

According to the third aspect of the present invention, when the determining means determines that the first wheel has approached the road surface limit, the first control means connects the first regulating valve from the shut-off state. The state is controlled to open the first return line, and the brake fluid in the brake fluid pressure generating means and the first wheel braking force generating means is simultaneously stored in the storage means. Similarly, if the determination means determines that the second wheel has approached the road surface limit, the second control means
By controlling the second regulating valve from the shut-off state to the communicating state,
And the brake fluid in the brake fluid pressure generating means and the second wheel braking force generating means is simultaneously stored in the storing means.

When the first control means or the second control means is executed, the suction and discharge means discharges the brake fluid stored in the storage means into the first conduit substantially simultaneously. . That is, according to the present invention, when each wheel reaches the road surface limit, the first adjusting valve or the second adjusting valve is driven, for example, the brake fluid is released from the wheel cylinder of each wheel to the reservoir, Since the cylinder pressure is reduced, it is possible to prevent the wheels from being locked for each wheel. At the same time, the brake fluid is discharged to the first pipeline by the pump, so that the wheel cylinder pressure of the wheel on which the first control means or the second control means is not executed can be increased, and Since the braking force of the wheels can be increased, the braking force of the vehicle can be improved as a whole.

According to the fourth aspect of the present invention, the determination by the determining means can be performed based on the wheel slip amount. Therefore, when the wheel slip amount is equal to or more than the predetermined value, it can be determined that the vehicle has approached the road surface limit. According to the fifth aspect of the invention, the determination by the determination means can be performed based on the wheel slip integrated value. Therefore, when the wheel slip integrated value is equal to or larger than the predetermined value, it can be determined that the vehicle has approached the road surface limit.

According to the sixth aspect of the present invention, the judgment by the judging means can be made based on the slip ratio. Therefore, when the slip ratio is equal to or more than the predetermined value, it can be determined that the vehicle is approaching the road surface limit. According to the seventh aspect of the present invention, the determination by the determining means can be performed based on the wheel cylinder pressure. Therefore, when the wheel cylinder pressure is equal to or higher than the predetermined value, it can be determined that the vehicle is approaching the road surface limit.

The invention according to claim 8 is provided with anti-skid control means for adjusting the brake fluid pressure in the wheel braking force generating means to keep the braking state optimal. Therefore, since the anti-skid control can be performed on the wheel that has reached the road surface limit, there is an advantage that the braking force is improved. In particular, as described above, this is effective in a case where it is not possible to prevent the wheel from being locked by merely moving the brake fluid from the wheel cylinder of one wheel to the wheel cylinder of the other wheel.

B) In order to achieve the second object, the constitutions of the following claims 9 to 18 are adopted. According to the ninth aspect of the present invention, at the time of vehicle braking, the first wheel braking force generating means receives the brake fluid pressure from the brake fluid pressure generating means via the pipeline to generate wheel braking force on the first wheel. Then, the second wheel braking force generating means receives the brake fluid pressure from the brake fluid pressure generating means via the pipeline, and generates the wheel braking force on the second wheel. Also, the first decompression means,
Suction fluid discharging means for reducing the brake fluid pressure applied to the first wheel braking force generating means while interrupting the flow of brake fluid between the first wheel braking force generating means and the second wheel braking force generating means; Sucks the brake fluid depressurized by the first pressure reducing means and discharges the brake fluid toward the second wheel braking force generating means.

[0022] The maintaining means is adapted to operate when the brake fluid pressure in the second wheel braking force generating means becomes the second brake fluid pressure higher than the first brake fluid pressure with the execution of the suction and discharge means. Then, the second brake fluid pressure is maintained.
In other words, in the present invention, the brake fluid of the reduced pressure is sucked in, for example, a wheel cylinder on one wheel side,
It is supplied to, for example, a wheel cylinder on the other wheel side. As a result, even if the occupant does not step on the brake pedal, the brake fluid pressure on one wheel is effectively increased to increase the brake fluid pressure on the other wheel higher than, for example, the master cylinder pressure, thereby stabilizing the vehicle behavior. Performance and braking distance can be shortened.

According to the tenth aspect of the present invention, at the time of vehicle braking, the first wheel braking force generating means receives the brake fluid pressure from the brake fluid pressure generating means via the pipe, and applies the wheel control to the first wheel. The power is generated, and the second wheel braking force generating means receives the brake fluid pressure from the brake fluid pressure generating means via the pipeline, and generates the wheel braking force on the second wheel. The first pressure reducing unit is configured to block the flow of the brake fluid between the first wheel braking force generating unit and the second wheel braking force generating unit, and to reduce a brake fluid pressure applied to the first wheel braking force generating unit. Is reduced, and the second pressure reducing means interrupts the flow of the brake fluid between the first wheel braking force generating means and the second wheel braking force generating means, and controls the second wheel braking force generating means. Although the brake fluid pressure is reduced, the control means executes one of the first and second pressure reducing means according to the vehicle body behavior.

The suction / discharge means sucks the reduced pressure brake fluid from one of the wheel braking force generating means, which is depressurized by the decompression means to be controlled by the control means, when the control means executes the control means, and The brake fluid is discharged toward the wheel braking force generating means, and the maintaining means performs the second brake hydraulic pressure at which the brake fluid pressure at the other wheel braking force generating means is higher than the first brake hydraulic pressure with the execution of the suction / discharge means. , The second brake fluid pressure is maintained.

That is, in the present invention, the execution of the first and second pressure reducing means is switched by the control means according to the vehicle behavior such as a deceleration state and a turning state. Therefore, for example, according to the vehicle behavior such as a deceleration state and a turning state,
Appropriate braking force distribution can be achieved, and a high braking force can be realized in each wheel, so that the braking force can be effectively reduced even in various driving states.

According to the eleventh aspect of the present invention, the control means includes a load movement detecting means for detecting a load movement during vehicle braking as a vehicle body behavior. That is, since the vehicle behavior can be accurately detected by detecting the load movement, more precise control can be performed.

In the twelfth aspect of the invention, the control means reduces the brake fluid pressure applied to the wheel braking force generating means of the wheel from which the ground load is released, based on the detection result of the load movement detecting means, and the maintaining means reduces the brake fluid pressure. The brake fluid pressure applied to the wheel braking force generating means of the wheel whose contact load increased to the second brake fluid pressure by the minute brake fluid increases is maintained.

In the present invention, the brake fluid pressure on the wheel side where one load is reduced is reduced, and the brake fluid pressure on the other wheel side is increased and maintained, so that a favorable braking force distribution can be achieved. According to the invention of claim 13, as the load movement detecting means, for example, a vehicle body deceleration detecting means for detecting a vehicle body deceleration at the time of vehicle braking, such as a front and rear G sensor, can be used. It can be easily and accurately detected.

According to the fourteenth aspect of the present invention, as the load movement detecting means, a turning state detecting means such as a steering sensor for detecting a steering angle or a lateral G sensor for detecting a turning state of the vehicle during braking can be used.
When these sensors are used, load movement can be easily and accurately detected.

According to the fifteenth aspect, at the time of vehicle braking, the first wheel braking force generating means receives the brake fluid pressure from the brake fluid pressure generating means via the pipeline, and applies the wheel control to the first wheel. The power is generated, and the second wheel braking force generating means receives the brake fluid pressure from the brake fluid pressure generating means via the pipeline, and generates the wheel braking force on the second wheel.

Further, when the slip state detecting means detects the slip state of the first wheel and the second wheel, the anti-skid control means sets the first state in accordance with the slip state.
And increasing and decreasing the brake fluid pressure applied to the second wheel braking force generating means. Then, when the anti-skid control means reduces the brake fluid pressure applied to the first or second wheel braking force generating means by the anti-skid control means, the suction / discharge means sucks the brake fluid corresponding to the reduced pressure and causes the anti-skid control means to reduce the brake fluid pressure in the pipeline. And the maintaining means maintains the second brake fluid pressure higher than the first brake fluid pressure formed with the execution of the suction / discharge means.

In other words, according to the present invention, when the anti-skid control is not performed on a wheel that is not currently controlled in the same piping system, there is a margin in the wheel braking force that this wheel can exert. By using the brake fluid for the reduced pressure, the braking force of the wheel on the side not subjected to the anti-skid control is improved. As a result, the braking force of the entire vehicle is improved, and the braking distance is shortened.

In the invention of claim 16, as the maintenance means,
When the first brake fluid pressure in the brake fluid pressure generating means is higher than a predetermined breaking point pressure, a predetermined pressure is applied when the brake fluid flows from at least one of the wheel braking force generating means to the brake fluid pressure generating means. By damping the pressure at the damping ratio, the brake fluid pressure of the wheel braking force generating means is increased to the second
And when the brake fluid flows from the brake fluid pressure generating means to at least one of the wheel braking force generating means and the first brake fluid pressure in the brake fluid pressure generating means is at a predetermined break point. When the brake fluid flows from the wheel braking force generating means side to the brake fluid pressure generating means when the pressure is equal to or less than the pressure, means for flowing the brake fluid substantially without pressure attenuation can be adopted.

This is what is called a proportional control valve, whereby a function for holding a differential pressure can be effectively realized. In the seventeenth aspect of the invention, a two-position valve for communicating and blocking the flow of the brake fluid between the brake fluid pressure generating means and at least one of the wheel braking force generating means can be used as the maintaining means.

That is, the same function as that of the sixteenth aspect can be realized by a two-position control valve that is not a proportional control valve. According to the eighteenth aspect of the present invention, a two-position valve that allows or blocks the flow of the brake fluid between the brake fluid pressure generating means and at least one of the wheel braking force generating means can be employed as the maintaining means. In particular, this two-position valve
When the pressure increasing / decreasing control is performed on the wheel braking force generating means of the first wheel or the second wheel by the anti-skid control means, the pressure between the brake fluid pressure generating means and the wheel braking force generating means is reduced. When the pressure increasing / decreasing control is being performed on the wheel braking force generating means for the first wheel and the second wheel, or when the anti-skid control means is being performed. If not,
A communication state is established in which the flow of the brake fluid between the brake fluid pressure generating means and the wheel braking force generating means is allowed.

That is, this two-position valve is shut off when pressure increase / decrease control by anti-skid control is performed on one of the first and second wheels. Therefore, for example, the wheel cylinder pressure in the pressure increase / decrease control wheels can be held. In addition, since the communication state is established when the pressure increase / decrease control is executed for both wheels, the anti-skid control performance can be improved on a low μ road such as on ice, for example. Further, when the anti-skid control is not executed, the communication state is established, so that a normal brake operation is possible.

By controlling the operation of the two-position valve in this manner, a necessary brake fluid pressure can be appropriately secured according to the state of the anti-skid control, and a high braking force can be realized.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a vehicle brake system according to the present invention will be described below in detail with reference to the drawings by way of examples (embodiments). (First Embodiment) This embodiment relates to a four-wheeled front-wheel drive vehicle capable of performing anti-skid control, which is an X-pipe having respective piping systems of right front wheel-left rear wheel and left front wheel-right rear wheel. This is an example in which the vehicle brake device according to the present invention is applied to a vehicle.

A) First, the basic structure of the brake device will be described with reference to a brake piping model diagram shown in FIG.
For simplicity of description, the following description will be made using a specific piping system (for example, a right front wheel and a left rear wheel) as an example. In FIG. 1, a brake pedal 1 depressed by a driver when applying a braking force to a vehicle is connected to a booster 3, and the pedaling force and pedal stroke applied to the brake pedal 1 are transmitted to the booster 3. Is done.

The master cylinder (M / C) 5 applies the brake fluid pressure boosted by the booster 3 to the entire brake pipe. The master cylinder 5 has a master reservoir for storing brake fluid. 7 is provided. The master cylinder pressure (M
/ C pressure) is applied to the master cylinder 5, a first wheel cylinder (W / C) 9 disposed on the right front wheel FR to apply a braking force to the wheel, and a wheel cylinder disposed on the left rear wheel RL. The first connecting the second wheel cylinder 11 that applies braking force to the
To the brake fluid in the piping system A. Similarly, the master cylinder pressure is also transmitted to a second piping system connecting each wheel cylinder disposed on the left front wheel and the right rear wheel and the master cylinder 5, but the same as in the first piping system A. Since the configuration can be adopted, it will not be described in detail.

As a configuration of the brake piping of the first piping system A, the master cylinder 5 and the first cylinder
A1a that communicates with the wheel cylinder 9 of the vehicle, and an electromagnetic valve (first pressure increase control valve) 13 that controls opening and closing of the pipeline A1a.
A check valve 19 provided in parallel with the first pressure increasing control valve 13, and a branch point B 1 between the first pressure increasing control valve 13 and the first wheel cylinder 9 and branching to the reservoir 17. A pipeline A2a is provided, and an electromagnetic valve (first pressure reduction control valve = first regulating valve) 15 that controls opening and closing of the pipeline A2a is provided.

Similarly, on the left rear wheel RL side, a pipeline A1b for communicating the master cylinder 5 and the second wheel cylinder 11, and an electromagnetic valve (second solenoid valve) for opening and closing the pipeline A1b.
Pressure increase control valve) 14, a check valve 21 provided in parallel with the second pressure increase control valve 14, and a branch point B2 between the second pressure increase control valve 14 and the second wheel cylinder 11. And a solenoid valve (second pressure-reducing control valve = second regulating valve) 16 for controlling the opening and closing of the pipeline A2b. The pipelines A1a and A1b are collectively referred to as a pipeline A1.

Further, a pipeline A3 extending from the reservoir 17 to the branch point B3 of the pipeline A1 (communicating with the master cylinder 5) in parallel with the control valves 13 to 16 and a brake provided from the reservoir 17 provided in the pipeline A3. The pump 23 includes a pump 23 that pumps the liquid toward the pipeline A1 and check valves 25 and 27 provided upstream and downstream of the pump 23.

In the above-described brake piping, when anti-skid control is performed on the right front wheel FR and the left rear wheel RL, the respective wheel cylinder pressures are increased by well-known pressure control by opening and closing the control valves 13 to 16. The braking force is adjusted by setting the state of holding or pressure reduction.

In particular, in this embodiment, the brake fluid is moved between the first and second wheel cylinders 9 and 11 by driving the pressure reducing control valves 15 and 16 and the pump 23 as described later. The control for adjusting the wheel cylinder pressures (hereinafter, referred to as first and second wheel cylinder pressures) (hereinafter, referred to as adjustment control) is performed. In that case, the pressure increase control valves 13 and 14 are off and the line A1 is in communication, and the pressure reduction control valves 15 and 16 on one of the wheels closer to the road surface limit are turned on and the line A2 is in communication. At the same time, control for driving the pump 23 is performed.

B) Next, the electrical configuration of this embodiment will be described. The anti-skid control and the adjustment control are performed by an electronic control unit (ECU) 30 shown in FIG. The ECU 30 includes a well-known CPU 30a, a ROM 30b,
RAM 30c, input / output unit 30d, and bus line 30e
And the like.

The input / output section 30d includes a stop switch 31 for detecting that the brake pedal 1 has been depressed and the vehicle has been substantially braked, a wheel speed sensor 33 for detecting the wheel speed of each wheel, A W / C pressure sensor 35 for detecting each wheel cylinder pressure is connected.
The first and second pressure increase control valves 13 and 14, the first and second pressure decrease control valves 15 and 16, and the pump 23 are connected to the input / output unit 30d.

C) Next, control processing performed by the ECU 30 will be described. First, a control process for starting the anti-skid control will be described based on the flowchart of FIG. In step 100 of FIG. 3, a known state initialization process such as clearing a flag is performed.

In the following step 110, the wheel speed VW of each wheel is calculated based on the signal from the wheel speed sensor 33 of each wheel. In the following step 120, an estimated vehicle speed Vs is obtained by applying a predetermined guard, for example, based on the maximum one of the wheel speeds VW.

In the following step 130, the estimated vehicle speed V
Based on s and each wheel speed VW, from the following equation (1),
The slip ratio SW is calculated for each wheel. SW = (Vs-VW) / Vs (1) In the following step 140, it is determined whether or not the stop switch 31 is on, that is, whether or not the brake pedal 1 is depressed. Here, if a positive determination is made, the process proceeds to step 150, while if a negative determination is made, the present process is temporarily terminated.

In step 150, it is determined whether the slip ratio SW of the wheel to be controlled is equal to or greater than a predetermined value, that is, whether anti-skid control is to be performed.
Here, if an affirmative determination is made, the process proceeds to step 160, while if a negative determination is made, the present process is temporarily terminated.

In step 160, since the condition for starting the anti-skid control is satisfied, the flag ABSF indicating that the anti-skid control is being performed is set to 1.
In the following step 170, the pressure increase control valves 13, 14 and the pressure decrease control valves 15, 16 are set according to the wheels to be controlled.
To perform a well-known anti-skid control for controlling the wheel cylinder pressure, and once terminates the present process.

Next, adjustment control, which is a main part of this embodiment, will be described with reference to the flowchart of FIG. Here, an example in which the adjustment control is performed based on the wheel slip amount Xs will be described. In step 200 of FIG. 4, a known state initialization process is performed.

In the following step 210, the wheel speed VW of each wheel is calculated based on the signal from the wheel speed sensor 33 of each wheel. The wheel speed VW obtained in step 110 may be used as it is. In the following step 220, an estimated vehicle speed Vs is obtained by applying a predetermined guard, for example, based on the maximum one of the wheel speeds VW. It should be noted that the estimated vehicle speed Vs obtained in step 120 may be used as it is.

In the following step 230, the estimated vehicle speed V
s and each wheel speed VW, from the following equation (2),
The wheel slip amount Xs is calculated for each wheel. Xs = (Vs−VW) (2) In the following step 240, it is determined whether or not the anti-skid control is currently being performed, based on whether or not the flag ABSF is “1”. If it is determined that there is, the process returns to step 210, whereas if it is not, the process proceeds to step 250. The determination as to whether or not the anti-skid control is being performed may be omitted. In step 250, it is determined in step 230 whether the target wheel is approaching the road surface limit.
The determination is made based on whether or not the wheel slip amount Xs obtained in the step is not less than a predetermined reference value KXs. Here, if it is determined that the vehicle is approaching the road surface limit, the process proceeds to step 260, while if it is determined that it is not, the process returns to step 210.

The reference value KXs is set to a value at which the timing for performing the adjustment control is earlier than the timing for performing the anti-skid control. Therefore, since the adjustment control is performed prior to the anti-skid control, the anti-skid control may not be started in some cases.

At step 260, at step 250
In this case, it is determined that the relevant wheel (the right front wheel FR will be described as an example in the following description) is approaching the road surface limit, so that the first pressure reduction control valve 15 is set in the communicating state, and the line A1 The brake fluid is released from the first wheel cylinder 9 and the like to the reservoir 17 via the branch point B1 to reduce the first wheel cylinder pressure. Thereby, the right front wheel FR moves away from the road surface limit.

In the following step 270, the pump 23 is driven to pump up the brake fluid from the reservoir 17 and supply it to the pipeline A1 via the branch point B3.
Return to At this time, the second pressure increase control valve 1 on the left rear wheel RL side
4 is in a communicating state and the second pressure-reducing control valve 16 is in a shut-off state, so that the brake fluid supplied to the pipe A1 side is supplied to the second wheel cylinder 11 through the pipe A1b. As a result, the second wheel cylinder pressure increases, so that the braking force of the left rear wheel RL increases.

The brake fluid supplied to the pipeline A1 by the pump 23 is supplied not only to the second wheel cylinder 11 but also to the first wheel cylinder 9, but the brake fluid is supplied to the first wheel cylinder 9 A certain pressure difference is generated in a state where the pressure is released to the reservoir 17 from the pressure, and as a result, the first wheel cylinder pressure decreases and the second wheel cylinder pressure increases.

D) Next, the operation such as the fluctuation of the brake fluid pressure by the adjustment control will be described with reference to the explanatory diagram of FIG. As shown in FIG. 5, when the brake pedal 1 is depressed at a certain timing (time t1), the wheels are braked, and the master cylinder pressure, the first wheel cylinder pressure, and the second wheel cylinder pressure are gradually increased. , And the braking force of both wheels in the piping system A increases. Along with this, although not shown, the wheel speed VW decreases and the wheel slip amount Xs gradually increases.

Then, for example, when the wheel slip amount Xs exceeds the reference value KXs in the right front wheel FR (at time t)
2) When the first and second pressure increasing control valves 13 and 14 are in communication with each other and the second pressure reducing control valve 16 is in the shut off state,
Only the pressure reduction control valve 15 is driven to be in a communicating state, so that the brake fluid flows out from the first wheel cylinder 9 side, and the first wheel cylinder pressure is rapidly reduced.

At this time (time t2), the pump 23 is driven and the brake fluid is supplied from the reservoir 17 to the pipeline A1, so that a considerable amount of the brake fluid is supplied to the second wheel cylinder 11, The second wheel cylinder pressure increases. Accordingly, the total braking force of both wheels temporarily decreases due to the reduction of the first wheel cylinder pressure, but thereafter increases as the second wheel cylinder pressure increases.

As described above, in this embodiment, the wheel slip amount Xs of each wheel is obtained, and when the wheel slip amount Xs becomes equal to or more than the reference value KXs, for example, it is considered that the right front wheel FR has approached the road surface limit, and By driving the first pressure reduction control valve 15 to release the brake fluid from the first wheel cylinder 9 side to the reservoir 17, and driving the pump 23,
The second wheel cylinder pressure is increasing.

As a result, the right front wheel FR moves away from the road surface limit, so that it does not fall into wheel lock.
Since the braking force of the left rear wheel RL (still far from the road surface limit) is increased, the braking force of the entire vehicle is increased as a result. Conventionally, in such a case, the anti-skid control of the right front wheel FR is immediately started, and the operability by the occupant is impaired correspondingly, but in the present embodiment, by moving the brake fluid, However, since the vehicle is once away from the state where the anti-skid control is started, the operability by the occupant is improved, and there is an advantage that the drive feeling is improved.

Note that the anti-skid control referred to here means that when it is determined that the wheel to be controlled has a locking tendency in comparison with a reference value set to a value larger than the reference value KXs, From the master cylinder 5 to the wheel cylinder 9 so that the cylinder pressure can be sufficiently reduced.
And after the control to reduce the wheel cylinder pressure by prohibiting the flow of brake fluid during

In the anti-skid control that inhibits the flow from the master cylinder 5 to the wheel cylinder 9, the pedal feeling of the occupant is only a kickback feeling due to the discharge of the pump. Since the master cylinder pressure is reduced as the pressure is reduced, a kickback feeling occurs due to the pump discharge and the shutoff of the second pressure reduction control valve 16 after the brake pedal 1 is pulled. In other words, in the anti-skid control, since the flow of the brake fluid from the master cylinder 5 to the wheel cylinder 9 is inhibited during pressure reduction, a feeling of plate pressure is generated. In this state, kickback occurs due to pump discharge. In the later kickback, the inertia of pedal retraction acts on the brake pedal 1 and the occupant's foot, and the kickback feeling is reduced. Therefore, such an adjustment control has an effect that the occupant's pedal feeling can be improved as compared with the normal anti-skid control.

In such adjustment control, in step 260, the communication cutoff of the first pressure reducing control valve 15 may be switched every predetermined time (for example, 20 mm / s). In this way, it is possible to suppress the brake pedal 1 from entering more than a predetermined amount, and it is possible to minimize the possibility that the master piston (the piston in the master cylinder 5) bottoms out due to the pedal stroke exceeding the predetermined value. it can. In this way, for example, if the slip state deteriorates even during the execution of the control of repeating the communication cutoff of only the first pressure reducing control valve 15 at predetermined time intervals, the anti-skid The control is executed, the first and second pressure increase control valves 13 and 14 are shut off, and a sufficient pressure reduction amount can be obtained.

Further, the pump drive in step 270 may be performed prior to the setting of the first pressure reducing control valve 15 to the communicating state in step 260. That is, in consideration of the fact that there is a predetermined time lag in the pump drive,
A command to drive the pump 23 may be output first. Even if, for example, a communication command for the first pressure-reducing control valve 15 is issued prior to the pump discharge command as in this embodiment, there is practically no temporal difference in the command timing. There is no problem with the control of the control itself.

Further, the present embodiment can be implemented without being limited to when the vehicle is traveling straight or turning. In the present embodiment, whether or not the anti-skid control is being performed is determined.
The adjustment control may be performed without performing the determination of the anti-skid control, that is, separately from the anti-skid control. (Second Embodiment) Next, a second embodiment will be described.

The present embodiment is significantly different from the first embodiment in that a configuration for performing anti-skid control is not provided. The description of the same parts as those in the first embodiment is omitted or simplified, and the same components in the hardware configuration are denoted by the same reference numerals. a) As shown in FIG. 6, in the first piping system A of the brake piping of the present embodiment, the first and second wheel cylinders 9 and 11, the first and second pressure reducing control valves 15 and 16, A reservoir 17, a pump 23, check valves 25 and 27, and the like are arranged. In particular, in this embodiment, since the anti-skid control is not performed, the pressure increase control valve of the first embodiment is not provided.

Accordingly, in this embodiment, as described later, in the case of the adjustment control, the control for driving the pump 23 is performed when the respective pressure reduction control valves 15 and 16 are in the communicating state. b) Next, the adjustment control of this embodiment will be described with reference to the flowchart of FIG. Here, an example in which the wheel slip integrated value AXs is used as a criterion for adjustment control will be described.

In step 300 of FIG. 8, a well-known state initialization process is performed. In the following step 310, the wheel speed VW of each wheel is calculated based on the signal from the wheel speed sensor 33 of each wheel. In the following step 320,
For example, based on the largest of each wheel speed VW,
An estimated vehicle speed Vs is obtained by applying a predetermined guard.

In the following step 330, the estimated vehicle speed V
s and each wheel speed VW, from the above equation (2),
The wheel slip amount Xs is calculated for each wheel. In the following step 340, the wheel slip amount Xs is integrated, and the wheel slip integrated value AXs (after the stop switch 21 is turned on) is calculated.

In the following step 350, it is determined whether or not the wheel slip integrated value AXs is equal to or larger than a predetermined reference value KAXs indicating that the wheel (for example, the front right wheel FR) has approached the road surface limit. If an affirmative decision is made here, step 360
The procedure returns to step 310 if a negative determination is made.

At step 360, for example, since it is determined that the right front wheel FR has approached the road surface limit, the first pressure reduction control valve 15 is set to the communicating state. Thereby, the brake fluid is released from the first wheel cylinder 9 to the reservoir 17, so that the first wheel cylinder pressure is reduced. Thereby, the right front wheel FR moves away from the road surface limit.

In the following step 370, the pump 23 is driven to pump up the brake fluid from the reservoir 17 and supply it to the pipeline A1 through the branch point B3.
Return to At this time, the brake fluid supplied to the pipe A1 is supplied not only to the pipe A1a but also to the second wheel cylinder 11 via the pipe A1b. Since the second pressure reducing control valve 16 is in the shut-off state, the second wheel cylinder pressure increases, thereby increasing the braking force of the left rear wheel RL.

As described above, in this embodiment, the wheel slip integrated value AXs of each wheel is obtained, and the wheel slip integrated value A
When Xs becomes equal to or more than the reference value KAXs, the first pressure reduction control valve 15 and the pump 23, for example, on the right front wheel FR, which are near the road surface limit, are driven, thereby reducing the first wheel cylinder pressure. , The second wheel cylinder pressure is increased.

Therefore, also in this embodiment, as in the first embodiment, there is an effect that the total braking force of the left and right wheels in the piping system A is improved. In particular, in this embodiment, the wheel slip integrated value A
Since Xs is employed, there is an advantage that the accuracy is higher than when the wheel slip amount Xs is employed.

It is to be noted that, in place of the configuration of this embodiment, it is also effective to configure only one of the first pressure reduction control valve 15 and the line A2a or the second pressure reduction control valve 16 and the line A2b. There is. For example, when the first pressure reduction control valve 15 and the pipeline A2a are provided, the braking force of the left rear wheel RL is improved and the right front wheel F
R can be prevented from being locked. On the other hand, when the second pressure reducing control valve 16 and the pipeline A2b are provided, the right front wheel F
It is possible to improve the braking force of R, prevent the left rear wheel RL from being locked, and improve the stability. Third Embodiment Next, a third embodiment will be described with reference to FIGS.

FIG. 8 shows the configuration of the brake system in this embodiment. The brake system includes wheel cylinders 41 and 42 for a front right wheel FR and a rear left wheel RL.
Constitute the first piping system A, and the left front wheel FL-the right rear wheel R
This is a diagonal piping system that constitutes a second piping system (not shown) with each wheel cylinder of R.

In this system, there is provided a vacuum booster 44 which boosts the pedal stroke of the brake pedal 43 operated by the occupant or the pedaling force of the occupant by using an intake manifold negative pressure of the engine or the like. A master cylinder pressure PM is generated in master cylinder 46 according to the output of 44. The brake pedal 43 and the master cylinder 46 constitute a brake fluid pressure generating means.

The master cylinder 46 has its own master reservoir 47, from which a first piping system A and a second piping system extend independently. Since the first piping system A and the second piping system can adopt the same configuration, illustration and description of the second piping system are omitted.

The first piping system A branches midway, and a pipeline A1 connected to the (second) wheel cylinder 42 on the left rear wheel RL side and a (first) wheel cylinder on the right front wheel FR side 41 is connected to the pipeline A2. The first piping system A is provided with an anti-skid actuator B surrounded by a dotted line. The anti-skid actuator B includes a pump 49 arranged to discharge the brake fluid sucked from the reservoir 48 to the pipeline A2,
It comprises (first and second) pressure increasing control valves 51 and 52 and (first and second) pressure decreasing control valves 53 and 54.
In the following description, the first and second distinctions between the wheel cylinders 41 and 42, the pressure increase control valves 51 and 52, and the pressure decrease control valves 53 and 54 are omitted.

The pressure increase control valves 51, 52 are connected to the pipelines A1, A
2, and the valve body positions of the pressure increase control valves 51 and 52 are set to the communicating positions shown in the drawing at the time of general braking. Each of the pressure increase control valves 51 and 52 is supplied from a predetermined power supply source according to a control signal from the ECU 60 (see FIG. 11).
Receives power supply, the pressure increase control valves 51 and 52 are turned on, and the valve positions are set to the shutoff positions.

On the other hand, the pressure-reducing control valves 53 and 54 are arranged in a pipe connecting the wheel cylinders 41 and 42 and the reservoir 48. The valve position of each of the pressure-reducing control valves 53 and 54 is set to the shut-off position shown in FIG. It has been. The valve positions of these pressure reduction control valves 53 and 54 are shut off positions in the ON state where power is supplied. Each of these valves 51, 52, 53,
Numeral 54 denotes a two-port two-position valve, which is constituted by an electromagnetic valve whose valve body moves by the magnetomotive force of an electromagnetic solenoid.

The proportional control valve 5 is located on the master cylinder 46 side of the connection point of the pump discharge in the pipe A2.
6 are arranged. The proportional control valve 56 may have a well-known structure that is conventionally disposed in a pipeline on the rear wheel side.
Conventionally, the proportional control valve 56 is used when the master cylinder pressure PM becomes equal to or higher than a predetermined break point pressure P as shown in FIG.
The master cylinder pressure PM which is the base pressure as shown by the one-dot broken line
Is attenuated at a predetermined damping ratio and the wheel cylinders 41, 42
Is to flow.

In the present embodiment, the proportional control valve 56 having such an operation is connected in reverse so that the base pressure is on the side of the wheel cylinder 41 as compared with the related art. That is, as shown by the solid line in FIG. 9, the master cylinder pressure PM and the wheel cylinder pressure PW
Is higher than the breaking point pressure P, the wheel cylinder 41
When the pressure on the pressure side becomes higher than the master cylinder pressure PM, the pressure decreases and flows toward the master cylinder 46 at a predetermined damping ratio. The proportional control valve 56 causes the wheel cylinder 4
It is possible to maintain the pressure on the one side higher than the master cylinder pressure PM.

As shown in FIG. 10, an ECU (electronic control unit) 60 includes a well-known CPU 60a and a ROM 60.
b, a RAM 60c, an input / output unit 60d, etc., and receives signals from a stop switch 61, a wheel speed sensor 62, a steering sensor 64 for detecting a rotation angle ω of a steering 63 (see FIG. 8), and the like to perform various calculations. And the pressure increase control valves 51, 52 and the pressure decrease control valves 53, 5
4 and a signal for driving the pump 49 and the like.

Next, a control flow performed by the ECU 60 will be described with reference to the flowchart of FIG. The control flow starts in response to an ON operation of an ignition switch (not shown) and the like.

In step 410, the wheel speed sensor 63
Calculates the wheel speed VW of each wheel based on the output signal from. In step 420, the vehicle speed VB is calculated based on the wheel speed VW of each wheel. As the vehicle speed VB, for example, the maximum value of the wheel speed VW may be employed, or the estimated vehicle speed Vs obtained by applying a predetermined guard to the maximum value of the wheel speed VW as in the first embodiment. May be adopted.

In step 430, the wheel acceleration dVW of the wheel to be controlled is calculated. In step 440, based on the wheel speed VW and the vehicle speed VB, the slip ratio S of the wheel to be controlled in the current flow is calculated using, for example, the equation (1).
Calculate W. In step 450, the stop switch 61 is controlled based on the output signal from the stop switch 61.
Is determined to be in the ON state. If a negative determination is made here, the process returns to step 410, while if an affirmative determination is made, the process proceeds to step 460.

In step 460, the slip rate SW of the wheel to be controlled is set to a predetermined slip rate KS (for example, 15 to 20%).
It is determined whether or not this is the case. If a negative determination is made here, the process returns to step 410, while if an affirmative determination is made, the process proceeds to step 470.

At step 470, it is determined whether or not the wheel acceleration dVW of the wheel to be controlled is a positive value (whether or not it is greater than 0). Here, if the determination is affirmative, the process proceeds to step 480, whereas if the determination is negative, the process proceeds to step 490. In step 480, assuming that the slip of the control target wheel tends to recover, the pulse pressure is increased for a predetermined time or a predetermined number of times from this point in consideration of the moment of inertia of the wheel, and the process returns to step 410.

The pulse pressure increase means that, for example, when the wheel cylinder 42 is pulse-intensified, the pressure-reducing control valve 54
In the cutoff position in the FF state, the power supply to the pressure increase control valve 52 is turned ON / OFF at predetermined intervals to repeat the communication / cutoff position. Further, a so-called holding control for holding the pressure before the pulse pressure increase may be performed for a predetermined time.

On the other hand, in step 490, it is determined that the slip state of the control target wheel is excessive, and the brake fluid pressure applied to the wheel cylinder of the control target wheel is reduced, and thereafter, the process returns to step 410. For example, the control target wheel is the right front wheel F
R, and if the slip state of the right front wheel FR is excessive, the pressure increase control valve 51 is turned on in the anti-skid control.
The pressure-reducing control valve 53 is turned on to reach the communication position. As a result, the brake fluid pressure applied to the wheel cylinder 41 decreases and flows toward the reservoir 48. In this step 490, the anti-skid control is started, and at the same time, the pump 49 is energized and driven, and the driving is continued until the end of the anti-skid control.

Next, the operation and effect of the above control will be described with reference to FIGS. In the time chart shown in FIG. 12, when the wheel slip ratio SW becomes equal to or higher than the predetermined slip ratio KS and the anti-skid control (ABS control) is started at the time t1 at the time of vehicle braking, the wheel to be controlled by the anti-skid control is moved to the time t2. Pressure reduction is controlled until At this time, the distribution of the braking force of the front and rear wheels is shown in FIG.
If the vehicle standard is set as shown by the one-dot broken line in FIG. 3, the front wheels tend to lock first.

A solid line shown in FIG. 13 is an ideal braking force distribution line. That is, if the distribution of the wheel braking force on the front and rear wheels is on this distribution line, the braking force distribution is such that the front and rear wheels lock simultaneously. Incidentally, the wheel braking force of the front wheel and the rear wheel differs depending on the wheel cylinder diameter or the brake pad area, etc., even if the same brake fluid pressure is applied to the wheel cylinder. The wheel braking force of the front and rear wheels exerts the same wheel braking force as long as the brake fluid pressures applied to the wheel cylinders of the front and rear wheels are equal.

With respect to this ideal braking force distribution line (solid line),
In a normal vehicle, the longitudinal braking force distribution is set as shown by the dashed line in FIG. 13 using the action of the proportional control valve as shown by the dashed line in FIG. That is, within the range of realistic wheel cylinder pressures PW, if the horizontal axis is the front wheel braking force (front wheel cylinder pressure PW) and the vertical axis is the rear wheel braking force (rear wheel cylinder pressure PW), the front and rear wheels are exerted. Is set on the front-wheel-advance lock side, which is below the ideal braking force distribution line.

In such a configuration, the front-rear braking force distribution is set so that the front wheels are locked at the time of vehicle braking. That is, the braking force distribution is set to the one indicated by the dashed line in FIG. In this case, if the right front wheel FR is started to perform the anti-skid control and the pressure is reduced, the brake fluid corresponding to the reduced pressure is added to the rear wheel side.
The second brake fluid pressure becomes the second brake fluid pressure higher than the master cylinder pressure PM.

That is, the region β in FIG. 13 is a region where the rear-wheel-side wheel braking force is insufficient compared with the ideal braking force distribution. Can be compensated for by the brake fluid amount corresponding to the reduced pressure of the front wheels, and the distribution can be made closer to the ideal braking force distribution. (Fourth Embodiment) Next, a fourth embodiment will be described with reference to FIG.

The brake system shown in FIG. 14 is constituted by diagonal piping as in the third embodiment.
Note that components having the same functions and effects as those of the components in the brake system shown in FIG. 8 are denoted by the same reference numerals, and description thereof will be omitted. Further, the configuration and control flow of the ECU and the like of this embodiment can be substantially the same as those described with reference to FIGS.

In the brake system shown in FIG.
A conduit A2 extending from between the master cylinder 46 and the reversely connected proportional control valve 56 is connected to the wheel cylinder 4 of the left rear wheel RL.
2 are connected. Further, the proportional control valve 56 and the pump 4
The pipe A1 extending from the discharge port 9 is connected to the wheel cylinder 41 of the right front wheel FR.

As described above, in the present embodiment, the proportional control valve 56 is different from the brake system of the third embodiment shown in FIG.
Is configured to act oppositely on the front and rear wheels. That is, the wheel cylinder 42 of the left rear wheel RL receives only the master cylinder pressure, and the brake fluid of the wheel cylinder 41 of the right front wheel FR is reduced by the pump cylinder 49 in addition to the master cylinder pressure. Enjoy the brake fluid pressure according to the brake fluid volume at the time. Thus, the proportional control valve 56 changes the brake fluid pressure applied to the front wheel side wheel cylinder 41 to the master cylinder pressure P.
It is arranged to have a holding action of holding the second brake fluid pressure higher than M.

In the present embodiment, the front and rear braking force distribution is set as shown by the dotted line in FIG. At this time, the wheel cylinder pressure PW = K at which the wheel braking force of the front and rear wheels becomes equal to or more than a predetermined value
When P (= master cylinder pressure PM), the wheel braking force on the rear wheel side exceeds the front wheel side. Therefore, when the wheel braking force is exerted at the brake fluid pressure KP or more, the rear wheel locks ahead of the front wheel in accordance with the road surface condition (corresponding to the area α).

Therefore, if such a braking force distribution setting is performed on the vehicle, the anti-skid control is executed in the wheel cylinder 42 on the rear wheel side at a predetermined master cylinder pressure PM = KP or more, and the pressure reduction control is performed. You. Assuming that this time is time t1 in FIG. 12, the right front wheel FR
It is assumed that anti-skid control is not being executed near time t1.

From time t1, pressure reduction control of the wheel cylinder 42 is performed. At time t2, the wheel acceleration d
Assuming that VW has become a positive value, the pressure reduction control is terminated and the pulse pressure is increased. If the anti-skid control is not performed on the wheel cylinder 41 side during the time t1 to t2, the brake fluid corresponding to the reduced pressure of the wheel cylinder 42 is sucked by the pump 49 via the reservoir and discharged toward the wheel cylinder 41. . At this time, the wheel cylinder 41 originally provided with the master cylinder pressure PM
In this case, the brake fluid amount corresponding to the reduced pressure is added, so that a second brake fluid pressure higher than the master cylinder pressure PM is formed. If the master cylinder pressure is equal to or higher than the break point pressure P, the second brake fluid pressure is maintained by the action of the proportional control valve 56, and the pressure of the wheel cylinder 41 becomes higher than the master cylinder pressure PM.

Further, after the wheel cylinder 42 of the anti-skid control target wheel is pulse-pressurized during the time t2 to t3, the pressure reduction control is performed again at the time t3 when the slip state becomes equal to or more than a predetermined value. At this time, the brake fluid amount corresponding to the reduced pressure is also discharged to the wheel cylinder 41 on the front wheel side where the anti-skid control is not performed, and the second brake fluid pressure on the wheel cylinder 41 side is further increased. In addition, time t2
Even when the wheel cylinder 42 is pulse-intensified using the master cylinder pressure PM during the period from to t3, the proportional control is performed at a position where the pressure holding action of the proportional control valve 56 acts only on the front wheel cylinder 41. Due to the arrangement of the valve 56, the second brake fluid pressure is kept unchanged.

As described above, the front wheel side wheel cylinder pressure PW is sequentially increased to the second brake fluid pressure in accordance with the rear wheel side pressure reduction control. Also, the braking force on the front wheels can be increased, and the braking distance can be shortened.

Further, if the front wheel side wheel cylinder is made higher than the master cylinder pressure PM by using the brake fluid corresponding to the pressure reduction of the rear wheel side, the possibility that the front wheel can also enter the anti-skid control increases. . Further, when the rear wheel enters the anti-skid control, the rear wheel substantially exerts the maximum wheel braking force.

At this time, if the front wheels can also enter the anti-skid control with the reduced brake fluid amount, the front wheels can also exert the maximum wheel braking force, and the front and rear wheel braking forces Can be improved. Therefore, the road surface reaction force and the side force in the front-rear direction of the vehicle body in the front-rear direction can be kept within a certain range, so that understeer and oversteer can be avoided, and the vehicle body behavior can be stabilized.

When the wheel braking force distribution is set as shown by the dotted line in FIG. 13, if the wheel cylinder pressure PW on the rear wheel side is reduced by the anti-skid control in the region α, the braking force distribution of the front and rear wheels is ideal. As much as possible on the braking force distribution line, the shortening of the braking distance and the improvement of the stability of the vehicle body behavior are also achieved.

The above-described proportional control valve 56 is used to hold the second wheel cylinder pressure. The proportional control valve 56 is moved from the wheel cylinder side to the master cylinder side in accordance with the master cylinder pressure PM. Brake fluid flow can be mechanically enabled at any time, so that wheel cylinder pressure control according to the occupant's operation intention, represented by the fluctuation state of the master cylinder pressure PM, can be realized without applying an extra control burden. Is provided. That is, when the pedal is returned by the occupant, each wheel cylinder pressure is mechanically reduced in response to this.

[0113] Normally, the rear wheel leading lock is avoided because the stability of the vehicle body is deteriorated. However, if the anti-skid control is provided, the vehicle body stability can be ensured. The braking force distribution can be set. (Fifth Embodiment) Next, a fifth embodiment will be described with reference to FIGS.
An example will be described. Note that components having the same functions and effects as those of the components in the brake system shown in FIG. 8 are denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, when the wheel cylinder pressure PW becomes the second brake fluid pressure higher than the master cylinder pressure PM, the master cylinder 46 and the wheel cylinder 4
Instead of the proportional control valve, a control valve 71 having two positions of communication and shut-off is adopted as a device for holding the differential pressure of the brake fluid pressure between the first and second brake fluids.

The control valve 71 is in the communicating position, which is the position shown in the drawing, in the normal brake state. The pump discharge destination is connected to a brake pipe on the wheel cylinder 41, 42 side of the control valve 71. In addition, in the first piping system A, a point branched into the wheel cylinder 41 side and the wheel cylinder 42 side is provided closer to the wheel cylinders 41 and 42 than the control valve 71.

Further, a check valve 72 is provided in parallel with the control valve 71, and the check valve 72 is connected in a direction allowing only the flow of the brake fluid from the master cylinder 46 to the wheel cylinders 41 and 42. Have been. Further, the control valve 71
And a differential pressure valve 73 is provided in parallel. This differential pressure valve 43 is
Only when the brake fluid pressure on the wheel cylinder side becomes higher than the master cylinder pressure PM by a predetermined pressure (for example, 50 kgf / cm ² ) or more, the flow of the brake fluid from the wheel cylinders 41 and 42 to the master cylinder 46 side is permitted. Things.

The non-return valve 72 compensates at least the normal brake when the control valve 71 has a trouble such as a shut-down failure or a blockage. The differential pressure valve 73 is
When the brake fluid pressure in the pipeline on the side of the wheel cylinders 41 and 42 exceeds the allowable pressure, the brake fluid is released to the master cylinder 46 side to protect the pipeline. still,
The check valve 72 and the differential pressure valve 73 can be omitted depending on the performance of the control valve 71, the pressure resistance of the pipeline, and the like.

Next, an example of a control flow for a system having such a configuration will be described with reference to the flowchart of FIG. As shown in FIG. 16, when the control flow starts, the same processing as that described in detail in FIG. 11 is performed from step 500 to step 560.

If it is determined in step 550 that the stop switch 61 is not in the ON state, or if it is determined in step 560 that the slip ratio SW is not excessive, the process proceeds to step 630, where the flag F is set. Set to 0 indicating that the anti-skid control is not being performed.

Thereafter, at step 640, control valve 7
A signal for turning off 1 is output. That is, the control valve 71 is maintained at the communication position. Then, returning to step 510, the control flow is repeated. On the other hand, if an affirmative determination is made in step 560, it is determined that the vehicle is in an excessive slip state.
In step 570, 1 is set to a flag F indicating that anti-skid control is performed on the current control target wheel.

In the following step 580, it is determined whether or not the flag F of the same piping system which is not the current wheel to be controlled is set to 1. For example, if the current control target wheel is the right front wheel FR, it is determined whether the left rear wheel RL is under the anti-skid control. And step 5
If an affirmative determination is made at 80, the process proceeds to step 600, whereas if a negative determination is made, the process proceeds to step 590.

At step 590, the control valve 71 is turned on to set the valve position to the shutoff position, and the routine proceeds to step 600. In step 600, it is determined whether or not the wheel acceleration dVW of the control target wheel has become a positive value. If the determination is affirmative, the process proceeds to step 610, while if the determination is negative, the process proceeds to step 620.

In step 620, pressure reduction control is performed on the control target wheel. On the other hand, in step 610, pulse pressure increase control for the control target wheel is executed for a predetermined time or a predetermined number of pulses, and the process returns to step 510. Note that, before the wheel cylinder pressure is increased by the pulse pressure increase, the holding control in which both the pressure increase control valve and the pressure reduction control valve are set to the cutoff position may be executed for a predetermined time. Further, in the initial output of the pulse pressure increase, control may be performed so as to obtain the same result as the holding control. This is because there is a time difference between the pressure reduction of the wheel cylinder pressure PW of the wheel to be controlled and the pressure increase of the other wheel due to the discharge of the pump. There is a possibility that the brake fluid may not be discharged toward the wheel cylinders of the other wheels.However, if the wheel cylinder pressure is maintained after the pressure reduction control of the control target wheel, the pressure increase control valve will remain This is because, in the cutoff state, the brake fluid due to the pump suction and discharge is applied to the wheel cylinder on the non-control target wheel side.

When the above control is performed, the above-described third
The same operation and effect as those of the fourth embodiment can be obtained.
In the case of this embodiment, the braking force distribution between the front and rear wheels is determined according to FIG.
The effect can be obtained by setting either the dotted line or the dashed line in 3. In this embodiment, if the wheel that is not the current control target wheel is not subjected to anti-skid control in the same piping system, there is a margin in the wheel braking force that can be exerted by this wheel. The pressure is increased to be higher than the master cylinder pressure PM by the liquid amount.

Further, the control valve 71 is set to the shut-off position only when the wheel which is not the current control target wheel in the same piping system is not subjected to the anti-skid control, and the pressure on the wheel cylinder side can be maintained. Further, when both wheels in the same piping system enter the anti-skid control, the control valve 71 remains OFF, so that the anti-skid control performance can be improved. For example, on low μ roads such as on ice, if the base pressure for increasing the wheel cylinder pressure in the pressure increase control (pulse pressure increase) during anti-skid control is high, depending on the pressure increase control method, the vehicle tends to lock immediately and the pressure reduction control time Becomes longer. In this case, it is conceivable that the braking distance is extended. However, as in the present embodiment, when both wheels enter the anti-skid control, the control valve 71 that shuts off the master cylinder side and the wheel cylinder side can be connected to each other. However, such a problem does not occur. (Sixth Embodiment) Next, a sixth embodiment will be described with reference to FIGS. As an example of the brake system that realizes the control flow of the present embodiment and the electrical configuration thereof, the configuration detailed in FIGS. 15 and 10 can be adopted.

As shown in FIG. 17, when the control flow starts, the state is initialized in step 700. In step 710, the steering angle ω is detected based on the output signal from the steering sensor 63. This steering angle ω is adopted as corresponding to the turning angle of the wheel.

In the following step 720, master cylinder pressure PM is detected. The master cylinder pressure PM may be detected from a master cylinder pressure sensor (not shown) or the like. Note that a predetermined sensor may be used as a parameter equivalent to the master cylinder pressure PM to detect a pedal stroke value, a pedal depression force value, or the like.

At the next step 730, it is determined whether or not the master cylinder pressure PM is higher than a predetermined pressure KPM.
If a negative determination is made here, the process returns to step 710,
On the other hand, if an affirmative determination is made, the process proceeds to step 740 assuming that the vehicle has been braked at a predetermined level or more by depressing the pedal of the occupant.

In step 740, it is determined whether the absolute value of the steering angle ω is larger than a predetermined angle Kω.
The turning direction of the vehicle is determined by the sign of the steering angle ω. If a negative determination is made in step 740, the process returns to step 710.
Go to 50.

In step 750, the pump 49 is started, assuming that the swing braking state is equal to or greater than a predetermined value. still,
As the turning braking state equal to or more than a predetermined value, for example, in the vehicle body behavior operation by the occupant pedal operation, the freedom of the vehicle body behavior does not work,
Sharp turning braking that makes the vehicle body behavior unstable may be mentioned. This pump drive may be canceled until a negative determination is made in step 730 or 740, or in a state where the vehicle body speed VB is equal to or lower than a predetermined speed (for example, a stopped state).

In step 760, the control valve 71 is turned on to set the shut-off position, and the flow of the brake fluid between the master cylinder 46 and the wheel cylinders 41 and 42 is prohibited.
In step 770, the pressure of the rear wheel on the inner wheel side is reduced in pulse in the turning direction determined by the sign of the steering angle ω. This pulse pressure reduction may be controlled based on a relationship map between the steering angle ω and the pressure reduction pulse ratio shown in FIG. That is, when the steering angle is larger than the predetermined angle Kω, the pressure reduction pulse ratio is increased as the steering angle ω increases. The pressure reduction pulse ratio may be controlled by adding the vehicle speed VB and the vehicle deceleration dVB. For example, as the vehicle deceleration dVB or the vehicle speed VB increases, the pressure reduction pulse ratio is increased.

The pressure-reducing pulse ratio is, as shown in FIG. 19, the OFF (cut-off position) of the pressure-reducing valve per unit time T1.
Is a ratio of the ON (communication position) state with respect to, and is OFF during a unit time when the pressure reduction pulse ratio is 0%, and is ON during a unit time when the pressure reduction pulse ratio is 100%.

Next, the time change of each wheel cylinder pressure during such control will be described with reference to FIG. As shown in FIG. 20, at time t1, the brake pedal 43 is depressed, and the master cylinder pressure PM starts to be applied to each of the wheel cylinders 41 and 42. Time t2
, The steering 63 is started to rotate, and at time t3, the steering angle ω becomes larger than the predetermined angle Kω. Then, at time t4, the master cylinder pressure P
If M has become greater than the predetermined pressure KPM, the control valve 71 is turned on to set the cutoff position. At the same time, the wheel cylinder pressure on the turning inner wheel side is controlled to be reduced, and the brake fluid corresponding to this reduced pressure is applied to the wheel cylinder on the turning outer wheel side. Accordingly, the brake fluid pressure on the turning outer wheel side is a second brake fluid pressure higher than the master cylinder pressure PM indicated by the dashed line, and the brake fluid pressure on the turning inner wheel side is lower than the master cylinder pressure indicated by the dashed line. Become.

As a result, each wheel can exert the wheel braking force along the turning braking state. In other words, the turning inner and outer wheels are set based on the master cylinder pressure PM so that the brake fluid pressure applied to the turning inner wheel whose ground contact load is reduced by the load transfer is reduced and the turning outer wheel side where the contact load increases is higher than the master cylinder pressure PM. By increasing or decreasing the wheel cylinder pressure, the balance between the front-rear road surface reaction force and the side force exerted by each wheel can be improved as a whole.

Further, the feed-forward control can be realized before the pressure reduction by the anti-skid control on the rear wheel inside the turning which is most likely to enter the anti-skid control, and the execution of the antiskid control can be delayed. (Seventh Embodiment) Next, a seventh embodiment will be described with reference to FIGS.
An example will be described. The control flow in the seventh embodiment can also employ the brake system and its electrical configuration described in detail in FIGS.

As shown in FIG. 21, when the control flow starts, in step 800, state initialization is performed.
In the following step 810, the wheel speed VW is detected.
In the following step 820, the vehicle speed VB is calculated.

At the next step 830, a master cylinder pressure PM is detected based on the output of a master cylinder pressure sensor (not shown). In the following step 840, the vehicle speed V
The vehicle deceleration dVB is calculated based on the time change of B or the output from a vehicle longitudinal acceleration sensor (not shown).
In the following step 850, it is determined whether or not the master cylinder pressure PM is higher than the predetermined pressure KPM. If a negative determination is made, the process returns to step 810, while if an affirmative determination is made, the process proceeds to step 860.

In step 860, it is determined whether the vehicle body deceleration dVB is greater than a predetermined vehicle body deceleration KdVB (for example, 0.3 G). This predetermined vehicle deceleration KdVB
May be set in consideration of a state in which the occupant is required to apply a somewhat large vehicle braking state or a state in which the load movement of the vehicle body in the front-rear direction is large to some extent.
If a negative determination is made in step 860, the process returns to step 810, while if a positive determination is made, the process proceeds to step 870.

In step 870, the wheel cylinder pressure on the rear wheel is reduced by a pulse for a predetermined time. This pulse pressure reduction ratio may be set so as to increase with the magnitude of the vehicle body deceleration dVB, for example, as shown in FIG.
Further, the pump driving is started at the same time as the start of the pulse reduction on the rear wheel side. This pump drive is performed until a negative determination is made in step 850 or 860, or the vehicle speed VB
The drive may be released in a state where the speed becomes equal to or lower than a predetermined speed (for example, a stop state).

When such control is executed, the brake fluid pressure on the front wheel side is used by using the brake fluid amount removed by the reduction in the contact load on the rear wheel side due to the load movement in the front-rear direction of the vehicle. Is increased to the second brake fluid pressure. In addition, the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes within the scope of the present invention.

(1) For example, in the first embodiment, the wheel slip amount Xs
In the second embodiment, the wheel slip integrated value AXs
However, the following means can also be adopted. For example, the slip ratio of each wheel can be used as a criterion.

For example, the wheel cylinder pressure of each wheel can be used as a criterion. In this case, W
When the wheel cylinder pressure detected by the / C pressure sensor 27 is equal to or higher than the reference value, it is considered that the wheel has approached the road surface limit, and adjustment control is performed.

For example, the vehicle body deceleration can be used as a criterion. For example, if the vehicle deceleration is 0.5G
In the case as described above, that is, when the adjustment control (for example, the communication control for bringing the first pressure reduction control valve 15 into the communication state) is performed in a case where the high braking force is applied, the pumping becomes a pseudo pumping. It is possible to delay that the wheel falls into the locked state.

(2) Instead of the proportional control valve 56 in the third and fourth embodiments, the control valve 71 in the fifth embodiment may be employed for control. Conversely, the proportional control valve 56 in the third and fourth embodiments may be adopted instead of the control valve 71 in the fifth embodiment.

When the control valve 71 is used, the ON of the control valve 71 is released in response to a decrease in the master cylinder pressure PM or the pedal stroke, and the wheel cylinder pressure according to the intention of the occupant to reduce the pressure is adjusted. Control may be realized. (3) Further, the turning state may be detected according to the output from the lateral acceleration sensor instead of the steering sensor in the sixth embodiment.

(4) The third to fifth embodiments and the sixth and seventh embodiments may be controlled in any combination. (5) In each of the above embodiments, the X pipe has been described as an example. However, any pipe that can move the brake fluid from one wheel side to the other wheel side, such as front and rear pipes, may be used for various pipes. Applicable. For example, the sixth embodiment is changed to the right front wheel FR.
The present invention may be applied to a vehicle with front and rear pipes having respective piping systems of a left front wheel FL, a right rear wheel RR and a left rear wheel RL.

(6) In the above-described embodiments, the present invention is applied to the system in which the master cylinder pressure PM is directly generated by the occupant's brake pedal via the vacuum booster. Instead of the electric signal, the present invention may be applied to a so-called brake-by-wire system in which a brake hydraulic pressure is generated as a master cylinder pressure PM at a brake hydraulic pressure generation source by the electric signal.

(7) The present invention may be applied to an automatic brake for avoiding danger. In this automatic braking, the master cylinder pressure may be generated by controlling the vacuum booster.

[Brief description of the drawings]

FIG. 1 is a model diagram of a brake pipe according to a first embodiment.

FIG. 2 is a block diagram showing an electrical configuration of the first embodiment.

FIG. 3 is a flowchart illustrating an anti-skid control process according to the first embodiment.

FIG. 4 is a flowchart illustrating an adjustment control process according to the first embodiment.

FIG. 5 is an explanatory diagram showing an operation by control of the first embodiment.

FIG. 6 is a model diagram of a brake pipe according to a second embodiment.

FIG. 7 is a flowchart illustrating an adjustment control process according to the second embodiment.

FIG. 8 is a model diagram of a brake pipe according to a third embodiment.

FIG. 9 is a graph showing the operation of the proportional control valve of the third embodiment.

FIG. 10 is a block diagram showing an electrical configuration of a third embodiment.

FIG. 11 is a flowchart illustrating a control process according to a third embodiment.

FIG. 12 is an explanatory diagram showing a state under the control of the third embodiment.

FIG. 13 is an explanatory diagram showing a braking force distribution of wheels according to a third embodiment.

FIG. 14 is a model diagram of a brake pipe according to a fourth embodiment.

FIG. 15 is a model diagram of a brake pipe according to a fifth embodiment.

FIG. 16 is a flowchart illustrating a control process according to a fifth embodiment.

FIG. 17 is a flowchart illustrating a control process according to a sixth embodiment.

FIG. 18 is a graph showing the relationship between the steering angle and the pressure reduction pulse ratio in the sixth embodiment.

FIG. 19 is an explanatory diagram showing ON / OFF states of a pressure reduction control valve according to a sixth embodiment.

FIG. 20 is an explanatory diagram showing a state under the control of the sixth embodiment.

FIG. 21 is a flowchart illustrating a control process according to a seventh embodiment.

FIG. 22 is a graph showing the relationship between the vehicle deceleration and the pressure reduction pulse ratio according to the seventh embodiment.

[Explanation of symbols]

 1, 43 brake pedal 5, 46 master cylinder 9, 41 first wheel cylinder 11, 42 second wheel cylinder 13, 51 first pressure increase control valve 14, 52 second pressure increase Control valves 15, 53 ... first pressure reducing control valves 16, 54 ... second pressure reducing control valves 17, 48 ... reservoirs 23, 49 ... pumps 30, 60 ... electronic control units (ECU) 31, 61 ... stop switches 33, 62 wheel speed sensor 63 steering sensor 71 control valve A first piping system A1, A1a, A1b, A2a, A2b, A3 pipeline B1, B2, B3 branch point

Claims (18)

[Claims] 1. A brake pedal operated by an occupant during braking of a vehicle, a brake fluid pressure generating means for generating a brake fluid pressure in accordance with the operation of the brake pedal, and a brake fluid pressure from the brake fluid pressure generating means. A first wheel braking force generating means for transmitting a braking force to the first wheel; and a brake fluid pressure from the brake fluid pressure generating means for transmitting a braking force to the second wheel. Second wheel braking force generating means; a first conduit communicating the brake fluid pressure generating means with the first and second wheel braking force generating means; and a brake fluid in the first conduit. Storing means capable of housing the first wheel and the second wheel, each of which determines whether or not each of the first wheels and the second wheel has approached the road surface limit; and that the first wheel has approached the road surface limit by the determining means. If it is determined, Through the conduit,
First control means for simultaneously storing the brake fluid in the storage means in the brake fluid pressure generating means and the first wheel braking force generating means, and when the first control means is executed, substantially simultaneously, And a suction / discharge means for discharging the brake fluid stored in the storage means into the first conduit. 2. A brake pedal operated by an occupant during vehicle braking, a brake fluid pressure generating means for generating a brake fluid pressure in accordance with the operation of the brake pedal, and a brake fluid pressure from the brake fluid pressure generating means. A first wheel braking force generating means for transmitting a braking force to the first wheel; and a brake fluid pressure from the brake fluid pressure generating means for transmitting a braking force to the second wheel. Second wheel braking force generating means; a first conduit communicating the brake fluid pressure generating means with the first and second wheel braking force generating means; and a brake fluid in the first conduit. Storing means capable of housing the first wheel and the second wheel, each of which determines whether or not each of the first wheels and the second wheel has approached the road surface limit; and that the first wheel has approached the road surface limit by the determining means. If it is determined, Through the conduit,
A first control unit that simultaneously stores the brake fluid in the brake fluid pressure generation unit and the first wheel braking force generation unit in the storage unit; and the determination unit determines that the second wheel approaches a road surface limit. When it is determined, a second control means for simultaneously storing the brake fluid in the brake fluid pressure generating means and the second wheel braking force generating means in the storage means via the first conduit. Suction and discharge means for discharging the brake fluid stored in the storage means into the first conduit substantially simultaneously when the first control means or the second control means is executed; A vehicle brake device, comprising: 3. A brake pedal operated by an occupant during braking of a vehicle, a brake hydraulic pressure generating means for generating a brake hydraulic pressure in accordance with the operation of the brake pedal, and a brake hydraulic pressure from the brake hydraulic pressure generating means. A first wheel braking force generating means for transmitting a braking force to the first wheel; and a brake fluid pressure from the brake fluid pressure generating means for transmitting a braking force to the second wheel. A second wheel braking force generating means; a first wheel braking force generating means extending from the brake fluid pressure generating means, branching on the way, and having respective ends connected to the first and second wheel braking force generating means. A pipe, a storage means capable of storing brake fluid in the first pipe, one end connected to the first wheel braking force generating means via the first pipe, and A first reflux line connected to the housing means, one end of which is forward A second return line connected to the second wheel braking force generating unit via a first line and the other end connected to the housing unit; and a second return line connected to the first return line. A first regulating valve that communicates and shuts off the first reflux line; and a second regulating valve that is disposed on the second reflux line and communicates and shuts off the second reflux line. Determining means for determining whether the first wheel and the second wheel have each approached a road surface limit; and when the determination means determines that the first wheel has approached a road surface limit, First control means for controlling the first regulating valve from a shut-off state to a communicating state; and if the determining means determines that the second wheel has approached a road surface limit, the second adjusting means A second control unit for controlling the valve from a shut-off state to a communication state, and the first control unit or the second control unit. A suction / discharge means for discharging the brake fluid stored in the storage means into the first conduit substantially simultaneously when the second control means is executed. apparatus. 4. The method according to claim 1, wherein the determination by the determination unit is performed based on a wheel slip amount.
4. The vehicle brake device according to any one of claims 1 to 3. 5. The vehicle brake device according to claim 1, wherein the determination by the determination unit is performed based on a wheel slip integrated value. 6. The method according to claim 1, wherein the determination by the determination unit is performed based on a slip ratio.
The brake device for a vehicle according to any one of the above. 7. The vehicle brake device according to claim 1, wherein the determination by the determination unit is performed based on a wheel cylinder pressure. 8. The anti-skid control means according to claim 1, further comprising an anti-skid control means for adjusting a brake fluid pressure in said wheel braking force generation means to keep a braking state optimal. Vehicle brake equipment. 9. A brake hydraulic pressure generating means for generating a first brake hydraulic pressure during braking of a vehicle, and receiving a brake hydraulic pressure from the brake hydraulic pressure generating means to generate a wheel braking force on a first wheel. First wheel braking force generation means; second wheel braking force generation means for receiving a brake fluid pressure from the brake fluid pressure generation means to generate a wheel braking force on a second wheel; Means, a pipe communicating the first and second wheel braking force generating means, and a flow of brake fluid between the first wheel braking force generating means and the second wheel braking force generating means. A first pressure reducing means for reducing the brake fluid pressure applied to the first wheel braking force generating means while shutting off the brake fluid; Sucked toward the wheel braking force generating means Discharge means, when the brake fluid pressure in the second wheel braking force generating means becomes a second brake fluid pressure higher than the first brake fluid pressure with execution of the suction and discharge means, And a maintenance means for maintaining the second brake fluid pressure. 10. A brake hydraulic pressure generating means for generating a first brake hydraulic pressure during vehicle braking, and receiving a brake hydraulic pressure from the brake hydraulic pressure generating means to generate a wheel braking force on a first wheel. First wheel braking force generation means; second wheel braking force generation means for receiving a brake fluid pressure from the brake fluid pressure generation means to generate a wheel braking force on a second wheel; A pipe communicating the means with the first and second wheel braking force generating means, and a flow of brake fluid between the first wheel braking force generating means and the second wheel braking force generating means. A first pressure reducing means for reducing the brake fluid pressure applied to the first wheel braking force generating means while shutting off; and between the first wheel braking force generating means and the second wheel braking force generating means. While blocking the flow of brake fluid at A second pressure reducing means for reducing the brake fluid pressure applied to the second wheel braking force generating means; a control means for executing one of the first and second pressure reducing means in accordance with the vehicle body behavior; Suction, the suction is performed by suctioning the brake fluid corresponding to the reduced pressure from one of the wheel braking force generating means, which has been reduced in pressure by the pressure reducing means to be controlled by the control means, and discharging the brake fluid to the other wheel braking force generating means. When the brake fluid pressure in the other wheel braking force generating means becomes a second brake fluid pressure higher than the first brake fluid pressure in accordance with the execution of the suction means and the suction means. 2
And a maintaining means for maintaining the brake fluid pressure of the vehicle. 11. The vehicle brake device according to claim 10, wherein the control unit includes a load movement detection unit that detects a load movement during vehicle braking as the vehicle body behavior. 12. The control means reduces the brake fluid pressure applied to the wheel braking force generating means of a wheel from which a ground load is released, based on the detection result of the load movement detecting means, and the maintaining means reduces the brake pressure. 12. The brake fluid pressure according to claim 11, wherein the brake fluid pressure applied to the wheel braking force generating means of the wheel whose ground contact load is increased to the second brake fluid pressure by the minute brake fluid is maintained. Vehicle brake system. 13. The vehicle brake device according to claim 11, further comprising a vehicle body deceleration detecting unit that detects a vehicle body deceleration at the time of vehicle braking as the load movement detecting unit. 14. The vehicle brake device according to claim 11, further comprising a turning state detecting means for detecting a turning state of the vehicle during braking of the vehicle as the load movement detecting means. 15. A brake hydraulic pressure generating means for generating a first brake hydraulic pressure during braking of a vehicle, and receiving a brake hydraulic pressure from the brake hydraulic pressure generating means to generate a wheel braking force on a first wheel. First wheel braking force generation means; second wheel braking force generation means for receiving a brake fluid pressure from the brake fluid pressure generation means to generate a wheel braking force on a second wheel; A pipe communicating the means with the first and second wheel braking force generating means; a slip state detecting means for detecting a slip state of the first wheel and the second wheel; Anti-skid control means for increasing and decreasing the brake fluid pressure applied to the first and second wheel braking force generating means; and the first or second wheel braking force generating means by the anti-skid control means. Blur When the brake fluid pressure is reduced, suction and discharge means for sucking the brake fluid corresponding to the reduced pressure and discharging the brake fluid into the conduit, A vehicle brake device, comprising: a maintaining means for forming a second brake hydraulic pressure higher than the first brake hydraulic pressure and maintaining the second brake hydraulic pressure. 16. The maintenance means is disposed in the pipeline, and when the first brake fluid pressure in the brake fluid pressure generation means is higher than a predetermined break point pressure, at least one of the wheels is provided. When the brake fluid flows from the braking force generating means to the brake fluid pressure generating means, the brake fluid pressure of the wheel braking force generating means is maintained at the second brake fluid pressure by attenuating the pressure at a predetermined damping ratio. When the brake fluid flows from the brake fluid pressure generating means to at least one of the wheel braking force generating means and when the first brake fluid pressure in the brake fluid pressure generating means is lower than a predetermined break point pressure, When the brake fluid flows from the wheel braking force generating means to the brake fluid pressure generating means at a certain time, the brake fluid flows substantially without pressure attenuation. Brake system according to any one of Motomeko 9-15. 17. The maintenance means is provided in the pipeline, and communicates the flow of brake fluid between the brake fluid pressure generation means and at least one of the wheel braking force generation means.
10. The valve according to claim 9, wherein the valve is a two-position valve that shuts off.
16. The vehicle brake device according to any one of claims 15 to 15. 18. The maintenance means is disposed in the pipeline, and allows and blocks the flow of brake fluid between the brake fluid pressure generation means and at least one of the wheel braking force generation means. When the anti-skid control means is performing the pressure increase / decrease control on the wheel braking force generation means of the first wheel or the second wheel, the two-position valve is provided with the brake fluid. The flow of the brake fluid between the pressure generating means and the wheel braking force generating means is interrupted. On the other hand, the pressure of the wheel braking force generating means of the first wheel and the second wheel is increased or decreased. When the control is being executed or when the anti-skid control unit is not being executed, a communication allowing the flow of the brake fluid between the brake fluid pressure generating unit side and the wheel braking force generating unit side To be in a state Brake system according to claim 15, symptoms.