JPH06329007A - Vehicle brake pressure control device - Google Patents

Abstract

PURPOSE:To provide a brake pressure control device capable of obtaining a natural pedal feeling within a short period of time without feeling any delay in the braking action when the brake pedal is stepped during the traction control. CONSTITUTION:An SOR valve 6 is arranged between a tube 30 to connect pressure reducing valves 9,10 to a reservoir 16 and a tube 31 to connect a pressure regulating valve 17 to a master cylinder 2, and the brake fluid is returned from the reservoir 16 to a reservoir tank 18 by setting the valve 6 to the communication mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling a brake pressure of a vehicle, and more particularly to a device for controlling a brake pressure in drive slip control (hereinafter referred to as traction control).

[0002]

2. Description of the Related Art Conventionally, a method of performing traction control by supplying brake fluid to a wheel cylinder of driving wheels has been known, but in order to realize this with a simple structure, for example, Japanese Patent Laid-Open No. 2-18150. As disclosed in Japanese Patent Publication No. JP-A-2003-264, there is considered a device that utilizes a pump or a switching valve for antiskid control in an antiskid control unit during traction control.

The above-mentioned device is characterized in that the pump is capable of self-priming, and is provided with a self-priming route, a relief discharge route, and a master cylinder disconnecting means for generating pressure.
At the time of traction control, the brake fluid sucked by the pump through the self-suction path is supplied to the wheel cylinders to apply the braking force to the drive wheels. Then, the traction control is ended when the drive slip is settled or when the brake pedal is depressed.

[0004]

However, in the above-mentioned conventional apparatus, if the control is immediately stopped when the brake pedal is depressed during the traction control, the brake fluid sucked from the self-suction path is stored in the anti-skid control unit. However, there is a problem that the brake fluid returns to the master cylinder due to the hydraulic pressure of the brake fluid remaining in the pipeline at this time, and the brake pedal feeling such as kickback is deteriorated. Further, if the brake fluid remaining in the pipe is discharged by the pump without immediately stopping the traction control, there is a problem that the braking effectiveness is delayed while the pump is discharging the brake fluid.

Therefore, the present invention has been made in view of the above problems, paying attention to the fact that the brake fluid in the control unit is the high pressure discharged from the pump during the traction control, and this high-pressure brake fluid is quickly supplied. An object of the present invention is to provide a brake pressure control device that can obtain a natural pedal feeling within a short time without feeling a delay in braking by discharging to the low pressure side.

[0006]

In order to achieve the above object, a vehicle brake pressure control device of the present invention comprises a pressure generating means for discharging high pressure brake fluid when a drive slip occurs on a wheel, and a master. Brake pressure control means for controlling the brake pressure of the wheel cylinder, which is provided in a pipe connecting the cylinder and the wheel cylinder, adjusts the high-pressure brake fluid discharged by the pressure generating means in accordance with the drive slip state of the wheel, and , Switching means for connecting or disconnecting between the master cylinder and the brake pressure control means, and at the end of the drive slip control, the brake fluid remaining in the pipeline from the switching means to the wheel cylinder is released to atmospheric pressure. And opening means.

[0007]

When the drive slip occurs on the wheel, the switching means disconnects the master cylinder and the brake pressure control means and the pressure generating means discharges the brake fluid in order to start the drive slip control. Then, the brake pressure control means adjusts the high-pressure brake fluid discharged from the pressure generating means so as to control the drive slip of the wheel, and controls the brake pressure of the wheel cylinder. At this time, the pressure of the brake fluid that acts on the brake pressure control means is substantially equal to the pressure generated by the pressure generation means, and thus is considerably higher than the atmospheric pressure. After that, when the drive slip control is completed, the opening means releases the brake fluid remaining in the pipe line from the switching means to the wheel cylinder to the atmospheric pressure, so that the pressure acting on the brake pressure control means or the wheel cylinder is It decreases due to its own pressure energy.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The vehicle brake pressure control system of the first embodiment shown in FIG. 1 has the functions of anti-skid control and traction control for preventing excessive wheel slip during braking and driving of a rear-wheel drive vehicle (FR vehicle). The figure shows a state in which neither control is performed (hereinafter referred to as an OFF state).

In FIG. 1, 1 is a brake pedal,
Reference numeral 35 is a brake switch for detecting depression of the brake pedal, and 2 is a master cylinder. 18 is a reservoir tank that is connected to the master cylinder 2 and stores brake fluid,
Reference numerals 11 and 12 are wheel cylinders that receive brake pressure from the master cylinder 2 or another pressure source to apply a braking force to the rear wheels RR and RL. Reference numerals 19 and 20 receive brake pressure from the master cylinder 2 and front wheels FR and FL. It is a wheel cylinder that gives a braking force to. 25 is the master cylinder 2
It is a proportioning valve that adjusts the brake pressure from the wheel cylinders 11 and 12.

Master cylinder 2 and wheel cylinder 1
1, 12, 19, 20 and between the wheel cylinders 11, 12, 19, 20 and the reservoir tank 18 during traction control.
A control unit 100 that adjusts the brake pressure of the wheel cylinders 11, 12, 19, 20 is arranged inside the control unit 100 during anti-skid control.
A control unit 50 for adjusting the brake pressure of the vehicle is arranged.

The control unit 100 and the control unit 50 will be described below. Switching valve 3, 4, 5, 6,
7,8,9,10,21,22,23,24 take 2 port 2 position, and can switch to either the communication mode which connects the upstream side and the downstream side, or the cutoff mode which cuts off. . The switching valve 3 (hereinafter referred to as the SM valve 3) and the switching valves 7 and 8 (hereinafter referred to as the holding valves 7 and 8) are arranged between the proportioning valve 25 and the wheel cylinders 11 and 12, and both are arranged. By setting the communication mode, it is possible to supply the brake fluid from the master cylinder 2 to the wheel cylinders 11 and 12, and by setting one of them in the cutoff mode, the supply of the brake fluid is cut off. The switching valves 9, 10 (hereinafter referred to as pressure reducing valves 9, 10) are wheel cylinders 11,
The brake fluid is discharged from the wheel cylinders 11 and 12 to the reservoir 16 through the pipe 30 by being arranged between the wheel cylinders 11 and 12 and in the communication mode.

The check valve 15 is arranged between the reservoir 16 and the pump 14, and allows only the flow of the brake fluid from the reservoir 16 to the suction side of the pump 14. Switching valve 5
The SRI valve 5 (hereinafter referred to as the SRI valve 5) is arranged between the reservoir tank 18 and the downstream side of the check valve 15, and the brake fluid stored in the reservoir tank 18 is sucked into the pump 14 by setting the communication mode. It is possible to supply to the side. Pump 14
When the motor 13 is driven, the brake fluid is sucked through the check valve 25, and the brake fluid is discharged through the check valve 26. These check valves 25 and 26 prevent the backflow to the suction and discharge of the pump 14.

The switching valve 4 (hereinafter referred to as the SPR valve 4) and the pressure regulating valve 17 are connected to the discharge side of the pump 4 and the reservoir tank 18.
And the pressure regulating valve 17 is opened when the discharge pressure of the pump 14 rises above a predetermined value when the SPR valve 4 is in the communication mode, and a part of the brake fluid is stored in the reservoir via the pipe 31. It is released to the tank 18 and the discharge pressure of the pump 14 is limited to a predetermined value. Further, a check valve 27 is arranged between the pipe 28 connecting the check valve 26 and the SPR valve 4 and the pipe 29 connecting the SM valve 3 and the holding valves 7 and 8, and Tube 2
Only allow brake fluid flow to 9.

Further, a switching valve 6 (hereinafter referred to as an SRO valve 6), which is a feature of the present invention, is disposed between the pipe 30 and the pipe 31, and the inside of the pipe 30 is set by setting the communication mode. The brake fluid can be returned to the reservoir tank 18. The switching valves 21 and 22 are similar to the holding valves 7 and 8 in that
3, 24 are the same as the pressure reducing valves 9, 10, check valves 28, 29 are the same as the check valves 25, 26, the pump 32 is the same as the pump 14, and the reservoir 36 is the same as the reservoir 16. To do. However, the pump 32 does not suck the brake fluid from the reservoir tank 18 (not self-priming).

Of the control unit 100 and the control unit 50 described above, the SM valve 3, the SPR valve 4, the SRI
The valve 5, the SRO valve 6, and the pressure regulating valve 17 are the control unit 1.
00, and other components are common. Although not shown, the brake pressure control device of the present embodiment is a wheel speed sensor that detects the wheel speed of each of the front wheels FR, FL and the rear wheels RR, RL, the signal from the brake switch 35, and the wheel speed. The control unit 100 detects the slip state of each wheel by inputting the signal of the sensor.
Also, an electronic control device for outputting a control signal to the switching valve in the control unit 50 and the motor 13 is provided.

Next, the operation of the brake pressure control device for an FR vehicle constructed as described above will be described with reference to the time charts of FIGS. 2 and 3, focusing on the traction control of the rear wheels RR, RL. Further, in contrast to the OFF state, a state in which the above-mentioned switching valves are switched and a state in which the motor 13 is driven are referred to as an ON state (the same applies to the following embodiments).

FIG. 2 shows the operation when the traction control is shifted to the normal brake control (normal brake). In FIG. 2, first, from the state in which each directional control valve is in the OFF state and the traction control is not performed,
When excessive driving slip occurs on the rear wheels RR and RL at = t1, traction control is started. At this time, first, the motor 13, the SM valve 3, the SPR valve 4, the SRI valve 5, and the SRO valve 6 are all turned on to shut off the master cylinder 2 and the wheel cylinders 11 and 12, and
The brake fluid stored in the reservoir tank 18 is sucked into the pump 14 via the SRI valve 5 and the check valve 25. Then, the brake fluid discharged from the pump 14 passes through the check valve 26 and then is branched into two systems, and the brake fluid passing through one is passed through the check valve 27 and the holding valves 7 and 8 to the wheel cylinder 1
Brake fluid supplied to the SPR valve 4 is supplied to
Is supplied to the pressure regulating valve 17 via. Station, pressure regulating valve 17
The brake pressure set by the wheel cylinder 11,
12 to generate braking force on the rear wheels RR and RL.
After that, depending on the drive slip state of the rear wheels RR and RL,
By appropriately switching the holding valves 7 and 8 and the pressure reducing valves 9 and 10, the brake fluid is supplied to or discharged from the wheel cylinders 11 and 12. At this time, the wheel cylinders 11, 1
The brake fluid discharged from No. 2 returns to the reservoir tank 18 at atmospheric pressure via the SRO valve 6, so that even if the brake fluid has a low temperature and a large viscosity, it does not accumulate in the reservoir 16.

When the brake pedal 1 is depressed at t = t2, the traction control is ended. At this time,
It is necessary to discharge all the brake fluid used for traction control from the control unit 50. Therefore, the motor 1
3, the SRI valve 5, and the holding valves 7 and 8 are turned off. As a result, the path from the reservoir tank 18 to the pump 14 is blocked and the operation of the pump 14 is stopped, so that the supply of the brake fluid to the wheel cylinders 11 and 12 is stopped. Further, since the holding valves 7 and 8 are in the OFF state and the pressure reducing valves 9 and 10 are in the ON state, it is possible to communicate between the SM valve 3 and the wheel cylinders 11 and 12 with the reservoir tank 18 via the SRO valve 6. Then, the brake fluid having the brake pressure set by the pressure regulating valve 17 returns to the reservoir tank 18 at atmospheric pressure from the pressure balance due to its own pressure energy.

Then, from t = t2, a predetermined time (100-
200 ms later, when t = t3, SM valve 3, SPR
The valve 4, the SOR valve 6, and the pressure reducing valves 9 and 10 are also turned off. As described above, in this embodiment, even if the driver depresses the brake pedal 1 during the traction control, all the high pressure brake fluid set by the pressure regulating valve 17 remaining in the control unit 50 is passed through the SRO valve 6. Since it can be quickly discharged to the atmospheric pressure reservoir tank 18, even if the traction control is immediately stopped when the brake is depressed,
You can get a natural pedal feeling within a short time without feeling the delay in braking.

In this embodiment, the traction control is terminated when the brake pedal is depressed. However, as a matter of course, the traction control is terminated when the slip of the driving wheels is stopped before the brake pedal is depressed. You can Further, the brake switch 35 is omitted, and when the brake pedal is depressed, excessive braking force is generated in the front wheels FR and FL, and the electronic control unit terminates the traction control when it determines that antiskid control is required. Good.

Then, the operation when the traction control is changed to the anti-skid control will be described with reference to FIG. During t4 <t <t5, the traction control is performed in the same manner as in FIG. 2. During this time, when the brake pedal 1 is depressed and an excessive braking force is generated on the front wheels FR, FL, the electronic control unit at t = t5. Determines that the anti-skid control has started. Then, the SRI valve 5 and the holding valves 7 and 8 are turned off. As a result, the path from the reservoir tank 18 to the pump 14 is shut off, the supply of the brake fluid in the reservoir tank 18 to the high pressure is stopped from being supplied to the wheel cylinders 11 and 12, and the holding valves 7 and 8 are turned off. Since the pressure reducing valves 9 and 10 are in the ON state, all of the portions between the SM valve 3 and the wheel cylinders 11 and 12 can communicate with the reservoir tank 18 via the SRO valve 6. Then, the brake fluid having the brake pressure set by the pressure regulating valve 17 returns to the reservoir tank 18 at atmospheric pressure from the pressure balance due to its own pressure energy. In addition, during this period, since it is necessary to perform the anti-skid control on the front wheels FR and FL, the motor 13 continues to be driven to operate the pump 32, and the holding valves 21 and 22 and the pressure reducing valves 23 and 24 are switched. The brake pressure of the wheel cylinders 19 and 20 is controlled.

Then, from t = t5, a predetermined time (100 to
200 ms later, when t = t6, SM valve 3, SPR
The valve 4, the SRO valve 6, and the pressure reducing valves 9 and 10 are also turned off. Alternatively, when anti-skid control is required for the rear wheels, the holding valves 7 and 8 and the pressure reducing valves 9 and 10 are appropriately switched. Note that the SPR valve 4 may be turned off by tamping slightly earlier than t = t5.

In the first embodiment, the pump 14
And the SPR valve 4 and the pressure regulating valve 17 correspond to pressure generating means,
The holding valves 7 and 8 and the pressure reducing valves 9 and 10 correspond to brake pressure control means, the SM valve 3 corresponds to switching means, and the SRO valve 6
Corresponds to the opening means. Next, a second embodiment will be described. The vehicle brake device of FIG. 4 is a front-wheel drive vehicle (FF
The vehicle has anti-skid control and traction control functions, and the figure shows the OFF state. It should be noted that the same components as those in FIG. 1 are denoted by the same reference numerals. Further, since the present embodiment is applied to the FF vehicle, one of the two brake fluid supply systems extending from the master cylinder is the FR wheel and the RL wheel, and the other is the FL wheel and the R wheel.
It is connected to the R wheel (so-called X pipe).

The differences between FIG. 4 and FIG. 1 will be described below. The switching valves 33 and 34 (hereinafter referred to as SM valves 33 and 34) take the 3-port-2 position and are arranged between the master cylinder 2 and the holding valves 21 and 22. These SM valves 33 and 34 are in the ON state or OFF at the same time.
Switch to the state. When the SM valve 34 is in the OFF state, the SM valve 34 connects the master cylinder 2 and the holding valve 22 so that the brake fluid from the master cylinder 2 can be supplied to the holding valve 22.
In the state, the master cylinder 2 and the holding valve 22 are shut off, and the brake fluid discharged from the pump 14 can be supplied to the SM valve 33 side. The SM valve 33 allows the master cylinder 2 and the holding valve 21 to communicate with each other in the OFF state to supply the brake fluid from the master cylinder 2 to the holding valve 21, and when the SM valve 33 is in the ON state, the master cylinder 2 and the holding valve 21 are connected to each other. Brake fluid discharged from the pump 14 via the SM valve 34 can be supplied to the holding valve 21 side while being blocked.
In addition, when the SM valves 33 and 34 are in the ON state, the pump 14
The pressure of the brake fluid discharged from the pressure control valve 17 is adjusted by the pressure control valve 17.

The downstream side of the pressure regulating valve 17 is connected to the SRO valve 6
Connected to the downstream side of the SM valve 33, 34
And when the brake fluid leaks through the pressure regulating valve 17,
This is to prevent the brake fluid from coming out of the control unit 100. However, SM33, 34 and pressure regulating valve 17
When there is no risk of brake fluid leaking from the pressure regulating valve 17
The downstream side of the SRO valve 6 may be connected to the upstream side of the SRO valve 6.

Next, the operation of the brake pressure control device for an FF vehicle constructed as described above will be described with reference to the time charts of FIGS. 5 and 6, the motor 1
3, SM valves 33, 34, SRI valve 5, and SRO valve 6
Performs the same operation as in the first embodiment shown in FIGS. The holding valve 21 and the pressure reducing valve 23 also operate similarly to the holding valves 7 and 8 and the pressure reducing valves 9 and 10 of the first embodiment.

FIG. 5 shows the operation when the traction control is shifted to the normal brake control. In FIG. 5, first, at the time t = t1, the front wheel F is turned off from the state where the brake pressure control is not performed, in which each switching valve is in the OFF state.
When excessive drive slip occurs in R and FL, traction control is started. At this time, first, the motor 13, the SM valves 33 and 34, the SRI valve 5, and the SRO valve 6 are all turned on.
State, master cylinder 2 and wheel cylinder 1
The valves 9 and 20 are shut off, and the brake fluid stored in the reservoir tank 18 is sucked into the pump 14 via the SRI valve 5 and the check valve 25. Then, the brake fluid discharged from the pump 14 passes through the check valve 26 and then branches into two systems, and the brake fluid passing through one is supplied to the wheel cylinder 20 via the holding valve 22, and the brake fluid passing through the other is supplied. SM
Supply to the wheel cylinder 19 through the valve 34, the SM valve 33, and the holding valve 22. At this time, the pressure of the brake fluid supplied to the wheel cylinders 19 and 20 is set by the pressure regulating valve 17, and the braking force according to the set pressure is generated in the front wheels FR and FL. After that, front wheels FR, F
Depending on the drive slip state of L, the holding valves 21 and 22 and the pressure reducing valves 23 and 24 are appropriately switched to supply or discharge the brake fluid to the wheel cylinders 19 and 20. At this time, the brake fluid discharged from the wheel cylinder 19 is returned to the reservoir tank 18 at atmospheric pressure via the SRO valve 6, so that the brake fluid does not accumulate in the reservoir 26 even when the brake fluid has a low temperature and a large viscosity. The brake fluid discharged from the wheel cylinder 20 is stored in the reservoir 16.

When the driving slip of the front wheels FR and FL is settled at t = t2, it is necessary to discharge all the brake fluid used for the traction control from the control unit 50.
Therefore, the motor 13, the SRI valve 5, the holding valves 21 and 22,
And the pressure reducing valve 24 is turned off, and the pressure reducing valve 23 is turned on.
Put in a state. As a result, the path from the reservoir tank 18 to the pump 14 is cut off, and the operation of the pump 14 is stopped, so that the supply of the brake fluid to the wheel cylinders 19 and 20 is stopped. Further, the holding valves 21, 2
Since 2 and the pressure reducing valve 24 are in the OFF state and the pressure reducing valve 23 is in the ON state, all of the SM valves 33, 34 to the wheel cylinders 11, 12 can communicate with the reservoir tank 18 via the SRO valve 6. Then, the brake fluid having the brake pressure set by the pressure regulating valve 17 returns to the reservoir tank 18 at atmospheric pressure from the pressure balance due to its own pressure energy.

Then, from t = t2, a predetermined time (100-
200 ms later, when t = t3, SM valves 33, 3
4, the SRO valve 6 and the pressure reducing valve 23 are also turned off. As described above, also in the second embodiment, even if the driver depresses the brake pedal 1 during the traction control, all the high pressure brake fluid set by the pressure regulating valve 17 remaining in the control unit 50 is passed through the SRO valve 6. Since it can be quickly discharged to the reservoir tank 18 at atmospheric pressure, even if the traction control is immediately stopped when the brake pedal is depressed as in the first embodiment, a natural pedal feel is felt within a short time without feeling a delay in the braking effect. You can get the ring.

In the present embodiment, the traction control is terminated when the brake pedal is depressed, but as a matter of course, the traction control is terminated when the slip of the driving wheels is stopped before the brake pedal is depressed. You can Further, the brake switch 35 is omitted, and when the brake pedal is depressed, excessive braking force is generated in the rear wheels RR, RL, and the traction control is terminated when the electronic control unit determines that antiskid control is necessary. May be.

Then, the operation when the traction control is changed to the anti-skid control will be described with reference to FIG. During t4 <t <t5, traction control is performed in the same manner as in FIG. 2. During this time, when the brake pedal 1 is depressed and excessive braking force is generated on the rear wheels RR and RL, electronic control is performed at t = t5. The device determines that anti-skid control has started. Then, the SRI valve 5, the holding valves 21 and 22, and the pressure reducing valve 24 are turned off.
As a result, the path from the reservoir tank 18 to the pump 14 is shut off to stop supplying the brake fluid in the reservoir tank 18 to the high pressure and supplying the brake fluid to the wheel cylinders 19 and 20, and the holding valves 21 and 22 and the pressure reducing valve. 24
Is in the OFF state and the pressure reducing valve 23 is in the ON state, so that the pressure reducing valve 23 and the SRO valve are all between the wheel cylinder 20 and the holding valve 22, the SM valve 34, the SM valve 33, and the holding valve 21 to the wheel cylinder 19. It becomes possible to communicate with the reservoir tank 18 via 6. Then, the brake fluid having the brake pressure set by the pressure regulating valve 17 returns to the reservoir tank 18 at atmospheric pressure from the pressure balance due to its own pressure energy. During this period, the anti-skid control needs to be performed on the rear wheels RR and RL, so the motor 13 continues to be driven and the pumps 14 and 3 are driven.
2 is operated, the holding valves 7, 8 and the pressure reducing valve 9,
10 is switched to control the brake pressure of the wheel cylinders 11 and 12.

Then, from t = t5, a predetermined time (100 to
200 ms) later, when t = t6, SM valves 33, 3
4, the SRO valve 6 and the pressure reducing valve 23 are also turned off. Alternatively, when anti-skid control is required for the front wheels FR, RL, the holding valves 21, 22 and the pressure reducing valve 2
Switch 3 and 24 appropriately. In the second embodiment, the pump 14 and the pressure regulating valve 17 correspond to pressure generating means, the holding valves 21 and 22 and the pressure reducing valves 23 and 24 correspond to brake pressure controlling means, and the SM valves 33 and 34. Corresponds to the switching means, and the SOR valve 6 corresponds to the opening means.

[0033]

As described above, according to the present invention, when the drive slip control is completed, the opening means releases the brake fluid remaining in the pipe line from the switching means to the wheel cylinder to the atmospheric pressure, so that the brake is applied. The pressure acting on the pressure control means or the wheel cylinder decreases due to its own pressure energy. Therefore, after the drive slip control is completed, there is an excellent effect that a natural pedal feeling can be obtained within a short period of time without feeling a delay in braking effectiveness.

[Brief description of drawings]

FIG. 1 is a diagram showing a brake system of a first embodiment.

FIG. 2 is a time chart for explaining the operation when the traction control is switched to the normal brake control in the first embodiment.

FIG. 3 is a time chart for explaining the operation when the traction control is switched to the anti-skid control in the first embodiment.

FIG. 4 is a diagram showing a brake system of a second embodiment.

FIG. 5 is a time chart for explaining the operation when the traction control is switched to the normal brake control in the second embodiment.

FIG. 6 is a time chart for explaining the operation when the traction control is switched to the anti-skid control in the second embodiment.

[Explanation of symbols]

 2 master cylinder 3,33,34 SM valve 4 SPR valve 5 SRI valve 6 SRO valve 7,8,21,22 holding valve 9,10,22,24 pressure reducing valve 14,32 pump 17 pressure regulating valve 18 reservoir tank

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayoshi Takeda 1-1-1, Showa-cho, Kariya city, Aichi prefecture Nihon Denso Co., Ltd.

Claims (1)

[Claims] 1. When a drive slip occurs on a wheel,
Pressure generating means for discharging high-pressure brake fluid, provided in the pipe line connecting the master cylinder and the wheel cylinder, adjusting the high-pressure brake fluid discharged by the pressure generating means according to the drive slip state of the wheel, Brake pressure control means for controlling the brake pressure of the wheel cylinder, switching means for connecting or disconnecting the master cylinder and the brake pressure control means, and a pipe from the switching means to the wheel cylinder at the end of the drive slip control. A brake pressure control device for a vehicle, comprising: an opening device that releases the brake fluid remaining in the road to atmospheric pressure.