JPH06286601A - Brake pressure controller - Google Patents

Abstract

PURPOSE:To provide a brake pressure controller which does not worsen control accuracy even if an abnormality occurs in a ground car speed sensor. CONSTITUTION:When a ground car speed sensor is normal, a target slip rate alphais set to 12% (S4), and a target wheel speed VR is operated based on ground car speed VGS and the target slip rate alpha (S5). If the ground car speed sensor is abnormal, the target slip rate alpha is set at 5% (S7), and the target wheel speed VR is operated based on assumed car body speed VSO (S8). Since shift amount of the assumed car body speed VSO is smaller than that when the ground car speed sensor is normal, the assumed car body speed VSO is lower than ground car speed VGS, but the target wheel speed VR is not deviated largely from running speed of a vehicle. Delay in start of an antilock control becomes small, fluctuation of brake pressure is reduced, and wheel speed is reduced and its fluctuation is reduced to avoid deterioration of control accuracy.

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 brake that suppresses wheel rotation, and more particularly to improvement of control accuracy.

[0002]

Brake pressure control devices include, for example, an anti-lock control device for shortening the braking distance and improving running stability during vehicle braking, and for improving the starting performance and acceleration performance of the vehicle. Acceleration slip control device. The brake pressure control device controls the brake pressure in order to suppress an excessive slip that occurs on the wheels. Conventionally, generally, the target wheel speed is set by shifting the traveling speed of the vehicle, and the target wheel speed and the actual wheel speed are set. The control is performed based on the relationship with. Slip is a phenomenon in which a wheel slips on a road surface and the actual wheel speed becomes larger or smaller than the traveling speed of the vehicle. The actual wheel speed can be brought closer to the traveling speed of the vehicle to reduce the slip. Then, in order to perform the best braking and driving, it is necessary to set an appropriate amount of slip, so the traveling speed is shifted to set the target wheel speed. The target wheel speed is determined by multiplying the traveling speed of the vehicle with a coefficient smaller than 1, or subtracting a constant value.
The target wheel speed is obtained by multiplying by a larger coefficient or by adding a constant value, and the brake pressure is controlled so that the actual wheel speed becomes the target wheel speed.

One type of such a brake pressure control device is
(A) A ground vehicle speed sensor that detects a ground vehicle speed, which is a relative speed to the road surface of the vehicle, (b) a wheel speed sensor that detects an actual wheel speed of the wheel, and (c) electrically controls the brake pressure of the wheel. An electromagnetic valve, and (d) an electromagnetic valve control means for controlling the electromagnetic valve based on the relationship between the target wheel speed obtained by shifting the ground vehicle speed detected by the ground vehicle speed sensor and the actual wheel speed detected by the wheel speed sensor. There are devices including and.

The vehicle traveling speed can also be obtained by estimation from a plurality of actual wheel speeds. For example, during control during straight traveling, the actual wheel speed of the wheel having the highest actual wheel speed among the plurality of wheels of the vehicle is closest to the traveling speed of the vehicle, and therefore the traveling speed of the vehicle is estimated based on this. Is done. However, even the wheel with the maximum actual wheel speed has slip, and since the wheel has less inertia and a larger speed change than the vehicle body, it is difficult to accurately estimate the traveling speed of the vehicle. Since the controllability of the antilock control is reduced, the ground vehicle speed is used.

As described above, when the vehicle traveling speed is acquired by the ground vehicle speed sensor, control cannot be performed if the ground vehicle speed sensor becomes abnormal and the ground vehicle speed cannot be obtained. Therefore, in the anti-skid control device disclosed in Japanese Patent Laid-Open No. 63-149251, when an abnormality occurs in the ground vehicle speed sensor, the control is performed based on the estimated vehicle speed estimated from the actual wheel speed. Has been done. The brake pressure is controlled so that the actual wheel speed becomes the target wheel speed obtained by shifting the estimated vehicle speed.

[0006]

However, when the brake pressure control is performed using the estimated vehicle body speed instead of the ground vehicle speed, there is a problem that the control accuracy is reduced. For example, in the anti-lock control device, instead of multiplying the ground vehicle speed by a coefficient smaller than 1 to set the target wheel speed, the estimated vehicle speed is multiplied by the same coefficient to set the target wheel speed. At times, wheels slip and the estimated vehicle speed becomes lower than the ground vehicle speed, so the target wheel speed also becomes lower, the start of antilock control is delayed, the brake pressure is greatly changed, and the actual wheel speed fluctuates greatly. The control accuracy deteriorates. An object of the present invention is to reduce deterioration of control accuracy when the estimated vehicle speed is used instead of the ground vehicle speed when the ground vehicle speed sensor is abnormal.

[0007]

In order to solve this problem, according to the present invention, as shown in FIG. 1, (a) ground vehicle speed sensor 1, (b) wheel speed sensor 2 and (c) electromagnetic valve 3 are provided. When the ground vehicle speed sensor is normal, an electromagnetic valve is set based on the relationship between the target wheel speed obtained by shifting the ground vehicle speed detected by the ground vehicle speed sensor and the actual wheel speed detected by the wheel speed sensor. If the ground speed sensor is abnormal, the solenoid valve that controls the solenoid valve based on the relationship between the target wheel speed and the actual wheel speed obtained by shifting the estimated vehicle speed estimated based on the actual wheel speed In the brake pressure control device including the control means 4, when the electromagnetic valve control means 4 has an abnormality in the ground vehicle speed sensor 1, the absolute value of the shift amount of the estimated vehicle speed is used as the ground vehicle speed sensor 1.
The gist is that the shift amount changing means 5 is provided to make the shift amount smaller than in the normal case.

[0008]

In the brake pressure control device according to the present invention,
When the ground vehicle speed sensor is abnormal, the target wheel speed obtained by shifting the estimated vehicle body speed is used for control, but the absolute value of the estimated vehicle body speed shift amount is made smaller than when the ground vehicle speed sensor is normal. Therefore, even if the estimated vehicle speed becomes low or high due to wheel slip, the target wheel speed is set to a value close to the target wheel speed set when the ground vehicle speed sensor is normal.

When the actual wheel speed becomes lower than the traveling speed of the vehicle due to wheel slip and the target wheel speed is set to a value lower than the traveling speed of the vehicle as in the case of the antilock control, the target wheel speed is set to a lower value. The amount of speed reduction to obtain is reduced, and the actual wheel speed becomes higher than the traveling speed of the vehicle due to the slip of the driving wheels, as in the acceleration slip control, and the target wheel speed becomes higher than the traveling speed of the vehicle. When set, the amount of increase in speed for obtaining the target wheel speed is reduced.

The "shift amount" is determined from the target slip ratio or the target slip amount, and is also determined by a combination of the target slip ratio and the target slip amount, or the like.

[0011]

Therefore, according to the present invention, even if an abnormality occurs in the ground speed sensor, the start delay of the control can be reduced, and the fluctuation of the brake pressure and the fluctuation of the actual wheel speed can be reduced, and the control accuracy can be reduced. Can be improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An antilock type brake device including an antilock control device according to an embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 2, reference numeral 10 indicates a brake pedal as a brake operating member. The brake pedal 10 is linked to a master cylinder 14 via a booster 12. The master cylinder 14 is a tandem type in which two pressurizing chambers are arranged in series with each other, and one pressurizing chamber passes through each electromagnetic valve 20 and the left and right front wheels 2 are connected.
It is connected to a front wheel cylinder 26 that operates brakes 2 and 24, and the other pressurizing chamber is also connected to each electromagnetic valve 28.
Through the rear wheel cylinders 34 of the left and right rear wheels 30 and 32.

The electromagnetic valves 20 and 28 are always in a pressure increasing state in which the wheel cylinders 26 and 34 are communicated with the master cylinder 14 and are cut off from the reservoirs 36 and 38. , 34 is switched from a holding state in which both the master cylinder 14 and the reservoirs 36, 38 are shut off, and a depressurized state in which the wheel cylinders 26, 34 are connected to the reservoirs 36, 38 and shut off from the master cylinder 14.

Although the solenoid valves 20 and 28 are illustrated as three-position valves in the figure, this is merely done for the sake of convenience. In reality, the solenoid valves 20 and 28 are normally open type electromagnetic on-off valves such as a booster valve and a normally closed valve. Type electromagnetic on-off valve. In the electromagnetic valves 20 and 28 thus configured, the pressure increasing state is realized by making the pressure increasing valve and the pressure reducing valve non-energized, and the holding state is realized by making only the pressure increasing valve electrically conductive. The depressurized state is realized by energizing both the pressure increasing valve and the pressure reducing valve. That is, the brake pressure of each wheel is selectively realized by a combination of two electromagnetic opening / closing valves, that is, a pressure increasing state, a holding state, and a pressure reducing state.
Hereinafter, the signals supplied to the solenoids of the electromagnetic valves 20 and 28 for realizing the pressure increasing state, the holding state and the pressure reducing state will be referred to as a pressure increasing signal, a holding signal and a pressure reducing signal, respectively.

The reservoirs 36 and 38 are connected to the master cylinder 14 via pumps 40 and 42, respectively, so that the hydraulic fluid in the reservoirs 36 and 38 is pumps 40 and 42.
Is pumped up and is returned to the master cylinder 14. That is, this anti-lock type brake device is a recirculation type. The pumps 40 and 42 are driven by a common motor 44.

The electromagnetic valves 20 and 28 are controlled by a controller 50. The controller 50 is a CPU,
It is mainly composed of a computer including a ROM, a RAM, an input interface and an output interface, and a solenoid drive circuit, and the solenoids of the electromagnetic valves 20 and 28 are connected to the solenoid drive circuit, respectively. A brake switch 54, four wheel speed sensors 56, and a ground vehicle speed sensor 58 are connected to the input interface, respectively. The brake switch 54 is always in the OFF state, and is turned on when the brake pedal 10 is depressed. The wheel speed sensor 56 detects left and right front wheels 22, 24 and left and right rear wheels 30, 32 by detecting the rotational speed of a rotating body that rotates with each wheel.
The actual wheel speed V _W of each of the above is detected. The ground vehicle speed sensor 58 detects the ground vehicle speed V _GS by, for example, an ultrasonic Doppler type or a spatial filter type.

The controller 50 has an antilock control routine, a brake pressure control routine, etc. stored in advance in its ROM, and the CPU executes the antilock control routine and the brake pressure control routine, whereby the antilock control is executed. Also, RA
In M, as shown in FIG. 3, the target slip ratio memory 6
0, a ground vehicle speed memory 62, a target wheel speed memory 64, a target wheel acceleration memory 66, an actual wheel speed memory 68, an actual wheel acceleration memory 70 and the like are provided.

Next, the above antilock control routine is shown in FIG.
A description will be given based on the flowchart. The antilock control routine is repeatedly executed at regular intervals. At the time of each execution, first, step S1 (hereinafter, simply "S1"
It is represented by. The same applies to the other steps), initial processing such as clearing various memories of the RAM and resetting various flags is performed, and subsequently, in S2, it is determined whether or not the ground vehicle speed sensor 58 is abnormal. Be seen. The abnormality diagnosis of the ground vehicle speed sensor 58 is performed by a computer other than the computer that performs the antilock control. For example, when an output signal is not obtained from the ground vehicle speed sensor 58, it is determined that the ground vehicle speed has changed rapidly. If it continues for a set time or longer, it is determined to be abnormal.
In S2, the result of the abnormality diagnosis is read and it is determined whether or not there is an abnormality.

If the ground vehicle speed sensor 58 is normal, the determination result in S2 is NO, S3 is executed, the ground vehicle speed V _GS is calculated based on the output signal from the ground vehicle speed sensor 58, and stored in the ground vehicle speed memory 62. To be done. Next, S4 is executed, and the target slip ratio α is set to 12% and stored in the target slip ratio memory 60. After setting the target slip ratio α, the target wheel speed V _R is calculated based on the ground vehicle speed V _GS and the target slip ratio α in S5, and the target wheel speed V
_R is set to 12% lower than the ground vehicle speed V _GS . In this embodiment, the shift amount is determined from the target slip ratio, and the calculated target wheel speed V _R is stored in the target wheel speed memory 64.

On the other hand, if the ground vehicle speed sensor 58 is abnormal, the determination result in S2 is YES and S6 is executed to calculate the estimated vehicle speed V _SO . During non-braking and when antilock control is not started even during braking, the maximum value of the four actual wheel speeds V _W detected by the wheel speed sensor 56 is the estimated vehicle body speed V _{W. SO} . After the start of the antilock control, the maximum value of the actual wheel speeds V _W of the four wheels whose deceleration does not exceed the set value is set as the estimated vehicle speed V _SO . If the deceleration of all wheels exceeds the set value, the actual wheel speed and the set value of the deceleration when the deceleration last exceeded the set value of the wheel Then the vehicle speed is estimated. If wheel slip recovers and there is no wheel whose speed exceeds the values estimated based on the set values of the actual wheel speed and deceleration, the actual wheel speed of the wheel is set as the estimated vehicle body speed V _SO .

Next, in S7, the target slip ratio α is set to 5% and stored in the target slip ratio memory 60. When the ground vehicle speed sensor 58 is abnormal, the shift amount of the estimated vehicle speed V _SO is reduced. Subsequently, S8 is executed, and the target wheel speed V _R is calculated based on the estimated vehicle speed and the target slip ratio α and stored in the target wheel speed memory 64.

After setting the target wheel speed V _R , S9 is executed, and the target wheel acceleration G _R is calculated by differentiating the target wheel speed V _R with respect to time. The target wheel acceleration G _R is specifically calculated by subtracting the previous value (previously stored in RAM) from the current value of the target wheel speed V _R , and the calculated value is the target wheel acceleration memory. Stored in 66.

After that, S10 to 14 are executed, and these S10 to 14 are the right front wheel 24 and the left front wheel 2.
2. Since the right rear wheel 32 and the left rear wheel 30 are executed once in this order, first, in S10, the execution target wheel of this four wheels is determined. Subsequently, in S11, the actual wheel speed V _W of the execution target wheel is calculated based on the output signal from the wheel speed sensor 56 corresponding to the execution target wheel, and is stored in the actual wheel speed memory 68. afterwards,
In S12, the actual wheel acceleration G _W is calculated by differentiating the actual wheel speed V _W with respect to time. The actual wheel acceleration G _W is specifically calculated by subtracting the previous value (previously stored in RAM) from the current value of the actual wheel speed V _W , and the calculated value is stored in the actual wheel acceleration memory 70. To be done.

Then, S13 is executed, and the process is executed for the control execution target wheel. The processing is the determination of the start of antilock control, the determination of the control mode of the electromagnetic valves 20, 28 and the determination of the duty control time of the electromagnetic valves 20, 28, which are the applications of the present applicant.
Since the same operation is performed in principle as the antilock control device described in the specification of No. 3212288, it will be briefly described.

It is determined that the antilock control should be started when the actual wheel speed V _W falls below the target wheel speed V _R.

The brake pressure control mode is determined as follows. When the actual wheel speed V _W is lower than the target wheel speed V _R , the pressure reducing mode is executed. As a result, the actual wheel speed V _W becomes higher than the target wheel speed V _R , and the vehicle speed V
_If it becomes too close to _GS , boost mode is executed. That is, the mode is determined with reference to the speed deviation ΔV, which is the deviation of the actual wheel speed V _{W from} the target wheel speed V _R. However, the actual wheel speed V _W is the target wheel speed V
Even when the actual wheel acceleration G _W is equal to or higher than the target wheel acceleration G _R even in the state where the pressure is lower than _R , the pressure reducing mode is stopped and the holding mode is executed.

The solenoid valves 20, 28 are used to increase and decrease pressure.
The duty control is performed. "Duty control"
In this embodiment, the Japanese Patent Application No. 4-32128
Unlike the anti-lock controller of No. 8, the electromagnetic valve 2
Outputting the pressure-increasing signal or the pressure-decreasing signal and the holding signal to the solenoid drive circuits 0 and 28 once in that order is one duty cycle, and
Once the duration of the pressure-increase signal or the pressure-reduction signal in the one duty cycle is the invariable transformation time and the duration of the holding signal is the variable holding time (hereinafter, referred to as “duty time”), Controlling the duty ratio, which is the ratio of the duration of the transformed signal to the occupied duty cycle time.

The duty time is determined so that it becomes shorter as the speed deviation or the acceleration deviation becomes larger, and as a result, the larger the speed deviation or the acceleration deviation becomes, the steeper the gradient of increasing or decreasing the brake pressure becomes. The speed deviation is a deviation from the target wheel speed V _R of the actual wheel speed V _W, the acceleration deviation which is a deviation from the target wheel acceleration G _R of the actual wheel acceleration G _R. Specifically, the actual wheel speed V _W is not less target wheel speed V _R above, and the pressure increase actual wheel acceleration G _W is the target wheel acceleration G _R above, the duty time DUTY is speed deviation ΔV and acceleration The brake pressure is suddenly increased by being determined by both the deviation ΔG, and the actual wheel speed V _W is equal to the target wheel speed V _{W.
When the} pressure is equal to or higher than _R and the actual wheel acceleration G _W is lower than the target wheel acceleration G _R , the duty time DUTY is determined only by the speed deviation ΔV and the brake pressure is gradually increased. The speed V _W is the target wheel speed V
_During depressurization, which is less than _R and the actual wheel acceleration G _W is less than the target wheel acceleration G _R , the duty time DUTY is determined only by the acceleration deviation ΔG.

Although not shown, the control mode determined by the antilock control routine is instructed by turning on and off a flag provided in the RAM, and the duty time is also stored in the RAM and stored in the ROM. The brake pressure control routine outputs signals to the solenoid drive circuits of the electromagnetic valves 20 and 28 so that the command and the duty time are realized by sequentially monitoring the command and the duty time via the RAM.

When the control mode and the duty time are determined as described above, the target wheel speed V _R and the target wheel acceleration G _R are used. These target wheel speed V _R and the target wheel acceleration G _R, if ground vehicle velocity sensor 58 is normal, is calculated based on the ground speed V _GS and 12% target slip rate set in the alpha, the control mode and the duty time By controlling the electromagnetic valves 20 and 28 in accordance with the above, the brake pressure gently changes and the actual wheel speed V _W follows the target wheel speed V _R , as shown representatively for the front wheels in FIGS. 5 and 6. Can be changed.

On the other hand, when the ground vehicle speed sensor 58 is abnormal, the target wheel speed V _R is calculated based on the estimated vehicle body speed V _SO , not the ground vehicle speed V _GS , but the target slip ratio α is the ground vehicle speed. The sensor 58 is set to 5%, which is smaller than that in the normal case, and the estimated vehicle body speed V _SO is shifted by a small amount. Therefore, although the estimated vehicle speed V _SO estimated by actual wheel speed including a slip below ground speed V _GS, as shown in FIG. 8, the target wheel speed V _R is ground vehicle velocity sensor 58 is obtained if the normal It is set without significantly deviating from the ground vehicle speed V _GS .

The abnormality occurs in the ground vehicle velocity sensor 58, even when calculating the target wheel speed V _R on the basis of the estimated vehicle speed V _SO, same city as if the target slip ratio α ground vehicle velocity sensor 58 is normal, the shift amount Since the estimated vehicle body speed V _SO is low unless the value is decreased, the target wheel speed V _R is reduced as shown in FIG.
However, if the ground vehicle speed sensor 58 is normal, it greatly deviates from the ground vehicle speed V _GS obtained. Therefore, a delay occurs in the start of the antilock control, the brake pressure is rapidly changed as shown in FIGS. 9 and 10, and the actual wheel speed V _W is rapidly changed and reduced, resulting in deterioration of control accuracy. . On the other hand, even when the estimated vehicle body speed V _SO is used when the ground vehicle speed sensor 58 is abnormal as in the present embodiment, the start delay of the antilock control is reduced by reducing the shift amount, and as shown in FIG. As shown in FIG. 8, the fluctuation of the brake pressure is reduced, the actual wheel speed V _W is reduced with a rapid fluctuation, and the deterioration of the control accuracy is reduced.

The above effect can be obtained by providing the antilock control routine with a step of setting the target slip ratio to a different magnitude depending on whether or not the ground vehicle speed sensor 58 is abnormal. In preparation for the case where the sensor 58 is abnormal, a routine is provided for performing antilock control without depending on the ground vehicle speed V _GS , and in the case of abnormality, the program capacity is not increased as compared with the case where the execution routine is switched. The effect of reducing the deterioration of control accuracy can be obtained.

As is apparent from the above description, in this embodiment, the ROM of the computer of the controller 50 is used.
Of S1 to S3, S5, S6, S8 to S14 and the part of the CPU that executes those steps constitute the electromagnetic valve control means 4, and the part of the ROM that executes S4 and S7 and the steps of the CPU are The part to be executed constitutes the shift amount changing means 5.

Although one embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be implemented in other modes.

For example, in the above embodiment, the target slip ratios are set to 12% and 5%, respectively, when the ground vehicle speed sensor 58 is normal and when it is abnormal. Set to the value of.

Further, the target slip ratio, the target slip amount, etc. for obtaining the shift amount are not limited to one kind, and may be stepwise or linear depending on the traveling speed of the vehicle when an excessive slip occurs. , It may be changed in a curve.

Further, in the above-described embodiment, whether or not the ground speed sensor 58 is abnormal is determined by a computer different from the computer that performs antilock control. May perform an abnormality diagnosis.

Further, in the above-mentioned embodiment, the electromagnetic valves 20 and 28 are composed of a combination of two two-position valves, but may be composed of one three-position valve, for example. it can. In addition, all of them are state switching type that switches the flow state of the hydraulic fluid between the hydraulic pressure source, the wheel cylinder, and the reservoir to a plurality of states. It is also possible to adopt a linear control type in which the height of the hydraulic pressure is changed linearly with respect to the magnetic force by balancing the force based on the hydraulic pressure.

Furthermore, the present invention can be applied not only to the antilock control device but also to another brake pressure control device such as an acceleration slip control device. When applied to an acceleration slip control device, it is suitable for an acceleration slip control device provided in a vehicle in which all wheels are drive wheels. Since the estimated vehicle speed becomes higher than the traveling speed of the vehicle due to the slip of the drive wheels, when the ground speed sensor is abnormal, the estimated vehicle speed is set to the target vehicle speed in order to obtain the target wheel speed, contrary to the case of the antilock control device. The coefficient to be multiplied is reduced, or the speed added to the estimated vehicle speed is reduced to reduce the shift amount.

In addition, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art without departing from the scope of the claims.

[Brief description of drawings]

FIG. 1 is a block diagram conceptually showing the structure of the present invention.

FIG. 2 is a system diagram showing an antilock brake device including an antilock control device according to an embodiment of the present invention.

FIG. 3 is a diagram conceptually showing a configuration of a RAM of a computer of a controller of the antilock control device.

FIG. 4 is a flowchart showing an antilock control routine stored in a ROM of the computer.

FIG. 5 is a graph showing a relationship between time and brake pressure during antilock control performed when the ground speed sensor is normal in the antilock control device.

FIG. 6 is a graph showing the relationship between the time during antilock control performed when the ground speed sensor is normal in the antilock control device, and ground speed, estimated vehicle speed, target wheel speed, and actual wheel speed.

FIG. 7 is a graph showing a relationship between time and brake pressure during antilock control performed when the ground speed sensor is abnormal in the antilock control device.

FIG. 8 is a graph showing the relationship between the time of antilock control performed when the ground vehicle speed sensor is abnormal in the antilock control device, and the ground vehicle speed, estimated vehicle body speed, target wheel speed, and actual wheel speed.

FIG. 9 is a graph showing the relationship between the brake pressure and the time of antilock control performed when the ground speed sensor is abnormal in the conventional antilock control device.

FIG. 10 is a graph showing the relationship between the time of antilock control performed when the ground vehicle speed sensor is abnormal in the conventional antilock control device, and the ground vehicle speed, estimated vehicle body speed, target wheel speed, and actual wheel speed. .

[Explanation of symbols]

 20 Electromagnetic Valve 22 Left Front Wheel 24 Right Front Wheel 28 Electromagnetic Valve 30 Left Rear Wheel 32 Right Rear Wheel 50 Controller 56 Wheel Speed Sensor 58 Ground Vehicle Speed Sensor

Claims (1)

[Claims] 1. A ground vehicle speed sensor for detecting a ground vehicle speed, which is a relative speed to a road surface of a vehicle, a wheel speed sensor for detecting an actual wheel speed of a wheel, and an electromagnetic valve for electrically controlling a brake pressure of the wheel. When the ground vehicle speed sensor is normal, the electromagnetic valve is based on the relationship between the target wheel speed obtained by shifting the ground vehicle speed detected by the ground vehicle speed sensor and the actual wheel speed detected by the wheel speed sensor. When the ground speed sensor is abnormal, the electromagnetic valve that controls the electromagnetic valve based on the relationship between the target wheel speed and the actual wheel speed obtained by shifting the estimated vehicle speed estimated based on the actual wheel speed is controlled. In a brake pressure control device including valve control means, in the electromagnetic valve control means, when the ground vehicle speed sensor is abnormal, an absolute value of a shift amount of the estimated vehicle speed is Brake pressure control device, characterized in that the earth vehicle speed sensor is provided the shift amount changing means be smaller than the normal case.