JP2000127950A - Brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an uncomfortable feeling to a driver when power assist control is ended. SOLUTION: This brake device comprises a master cylinder 10; wheel cylinder 50; reservoir 72; three-way valve 57 connected to the master cylinder, wheel cylinder and reservoir to make the master cylinder 10 selectively communicate with any of the other members; pump 82 capable of forcedly supplying a brake fluid in the reservoir to a wheel cylinder side; normally-closed pressure reducing valve 70 switching a communicated condition of the wheel cylinder and the reservoir; power assist control means switching the three-way valve to make the master cylinder communicate with the reservoir when a fixed condition is materialized to supply the brake fluid by the pump to the wheel cylinder also to change a supply amount thereof in accordance with brake operation; and a pressure reducing valve control means switching the pressure reducing valve to an opened condition for a fixed time before switching the three-way valve so as to make the master cylinder communicate with the wheel cylinder, in the case of ending power assist control.

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 capable of generating a higher fluid pressure in a wheel cylinder than in a master cylinder.

[0002]

2. Description of the Related Art As a brake control device capable of generating a hydraulic pressure higher than that of a master cylinder in a wheel cylinder, a device which performs power assist control in which a brake operation force is assisted by a pump at the time of vehicle braking has already been disclosed in Japanese Patent Application No. 10-3009.
No. 8 has been proposed by the present applicant.

[0003] This brake device is intended to suppress a decrease in the effectiveness of the brake after the well-known assist of the brake booster and to reduce the brake operating force. The pump is operated to generate a higher hydraulic pressure than the master cylinder in the wheel cylinder. At the same time, the level of the hydraulic pressure of the brake cylinder at that time is controlled so as to continuously change in accordance with the brake operating force.

The hydraulic pressure output passage from the master cylinder is of a diagonal type comprising two systems, a first system for the left front wheel FL and the right rear wheel RR, and a second system for the right front wheel FR and the left rear wheel RL. Each main passage from the master cylinder is branched and connected to a wheel cylinder of two wheels of each system.

An electromagnetic three-way valve is provided in the middle of the main passage, and the three-way valve is also connected to a reservoir described later. The three-way valve has a function of switching between a state in which the master cylinder communicates with the reservoir and a state in which the master cylinder communicates with the wheel cylinder. In addition,
In a normal state, the three-way valve is in a state of communicating the master cylinder and the wheel cylinder.

The reservoir communicates with the wheel cylinder via a pressure reducing valve during the pressure reduction control of the wheel cylinder pressure, stores the brake fluid, and can also communicate with the master cylinder via a three-way valve. Further, the reservoir is provided with a piston that strokes according to the liquid storage volume, and a shutoff valve that shuts off a connection passage between the three-way valve and the reservoir when the stroke of the piston exceeds a set value.

[0007] The reservoir is connected to the suction side of the pump, and the brake fluid contained in the reservoir is pumped out by the pump. The pump discharge side is connected to a passage between the three-way valve and the branch portion, and pressurizes the brake fluid pumped from the reservoir to supply the brake fluid to the wheel cylinder.

When the hydraulic pressure of the master cylinder exceeds a predetermined level, the three-way valve is switched from a normal state to a state in which the master cylinder communicates with the reservoir, and the pump is operated. (Power assist control).

[0009]

However, in this brake device, when each of the three-way valves is switched at once with the end of the power assist control, the pressure of all the wheel cylinders controlled to a pressure higher than the master cylinder pressure is obtained. Are released at once. At this time, a strong impact is applied to the master cylinder and eventually to the brake pedal due to the pressure propagation, which gives the driver an uncomfortable feeling.

[0010] The present invention has been made in view of such a point, and an object of the present invention is to provide a brake device that reduces a sense of discomfort to a driver when power assist control ends.

[0011]

In order to achieve the above object, a brake device according to the present invention comprises: a master cylinder for generating a hydraulic pressure according to a brake operation; A cylinder connected to the wheel cylinder through a passage filled with brake fluid and capable of storing brake fluid, and a master cylinder, a wheel cylinder and a reservoir connected respectively to the reservoir and the master cylinder being either a wheel cylinder or a reservoir. A switching valve for selectively communicating with the pump, a pump capable of forcibly supplying the brake fluid in the reservoir to the wheel cylinder side, and a wheel cylinder and the reservoir disposed in the middle of a passage between the wheel cylinder and the reservoir. A normally closed pressure reducing valve that switches the communication state of the The power assist control means for supplying the pressurized brake fluid to the wheel cylinder and changing the supply amount in accordance with the brake operation, and the power in the power assist control means. At the end of the assist control, a pressure reducing valve control means for switching the pressure reducing valve to an open state for a predetermined time before switching the switching valve so as to connect the master cylinder to the wheel cylinder is provided.

According to the present invention, at the end of the brake assist control, before the switching valve is switched so that the wheel cylinder and the master cylinder communicate with each other, the pressure reducing valve disposed between the wheel cylinder and the reservoir is kept constant. By keeping the wheel cylinder and the reservoir open for a time,
The brake fluid can flow into the reservoir from the wheel cylinder to reduce the fluid pressure in the wheel cylinder to some extent. For this reason, the hydraulic pressure difference between the wheel cylinder and the master cylinder can be reduced, and the hydraulic pressure of the master cylinder can be prevented from sharply increasing when the wheel cylinder and the master cylinder are subsequently connected. Therefore, it is possible to prevent the driver from feeling uncomfortable through the brake pedal when the brake is released. Further, it is possible to reduce noise generated when the hydraulic pressure of the master cylinder increases when the brake is released.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of the present invention will be described below with reference to the accompanying drawings. In the drawings, the same elements are denoted by the same reference numerals, and the description is omitted. Also, the dimensional ratios in the drawings do not always match those described.

FIG. 1 shows a configuration of a brake system to be controlled by a brake control device according to this embodiment.

As shown in FIG. 1, the master cylinder 10
Has two pressurizing pistons (master cylinder pistons) fitted in series and slidably in a housing (master cylinder housing), and each pressurizing piston in front of each pressurizing piston in the housing. The chambers are of a tandem type formed independently of each other. The master cylinder 10 is linked via a vacuum booster (hereinafter simply referred to as a booster) 12 to a brake pedal 14 which is a brake operating member. Therefore, the brake operation force F, which is the depression force of the brake pedal 14, is assisted by the booster 12 and transmitted to the master cylinder 10. The booster 12 performs a brake operation through a power piston operated by a differential pressure between a negative pressure chamber connected to a negative pressure source such as an engine intake pipe and a variable pressure chamber selectively communicated with the negative pressure chamber and the atmosphere. Help force F. Therefore, when the pressure in the variable pressure chamber reaches the atmospheric pressure, the booster 12 reaches the assisting limit.

The main passage 40 of the first brake system for the left front wheel FL and the right rear wheel RR is connected to one pressurizing chamber of the master cylinder 10, and the right front wheel FR and the left rear wheel are connected to the other pressurizing chamber. The main passage 41 of the second brake system for RL is connected. That is, in this brake device, the output passage from the master cylinder 10 is constituted by two diagonal passage systems. Since these brake systems have a common configuration, only the first brake system will be representatively described below, and the description of the second brake system will be omitted.

In the first brake system, a master cylinder 10 is operated by a main cylinder 40 to operate a wheel cylinder 50 that operates a brake 42 for suppressing the rotation of the left front wheel FL.
And the wheel cylinder 50 of the brake 44 of the right rear wheel RR. The main passage 40 is branched in a forked shape after extending from the master cylinder 10, and one of the branch passages becomes a main passage 54, and the main passage 5
4 also branches into a forked shape and is connected to two branch passages 56. The wheel cylinder 50 is connected to the downstream side of each branch passage 56.

In the middle of the main passage 54, an electromagnetic three-way valve 57 as a switching valve is provided. The three-way valve 57
This is a port 2 position valve and is also connected to the reservoir 72. When the solenoid is off, it is in a first state in which the master cylinder 10 communicates with the wheel cylinder 50, and when the solenoid is on, it switches to a second state in which the master cylinder 10 communicates with the reservoir 72.

The main passage 54 is provided with a check valve 58 and a relief valve 59 for bypassing the three-way valve 57, respectively. The check valve 58 is for always allowing the flow of the brake fluid from the master cylinder 10 to the wheel cylinder 50. On the other hand, the relief valve 59 is for preventing the hydraulic pressure on the wheel cylinder 50 side from the three-way valve 57 from becoming excessive due to the pressurization of a pump 82 described later.

In the middle of each branch passage 56, a holding valve 60 which is an electromagnetic normally-open valve is provided. The holding valve 60 is
When the solenoid is off, that is, open, the master cylinder 1
The bidirectional flow of the brake fluid between the wheel cylinder 0 and the wheel cylinder 50 is allowed, and the flow is blocked in the ON state, that is, in the closed state. Each branch passage 56 is provided with a check valve 64 that bypasses each holding valve 60. A proportioning valve 65 is provided in the middle of the two branch passages 56 corresponding to the right rear wheel RR.

Each reservoir passage 66 extends from a portion of each branch passage 56 between the holding valve 60 and the wheel cylinder 50 and reaches a reservoir 72. In the middle of each reservoir passage 66, a pressure reducing valve 70, which is an electromagnetic type normally closed valve, is provided. The pressure reducing valve 70 prevents the flow of the brake fluid from the wheel cylinder 50 toward the reservoir 72 when the solenoid is off, that is, when the solenoid is closed, and allows the flow when the solenoid is on, that is, when the solenoid is open.

The reservoir 72 includes a reservoir housing 73
The reservoir piston 74 is fitted substantially slidably and airtightly, and the brake fluid is stored in a reservoir chamber 76 formed by the fitting. The reservoir piston 74 is constantly urged by a spring 78 as an elastic member in a direction in which the volume of the reservoir chamber 76 decreases, and as a result, the reservoir piston 74 is normally in contact with the reservoir housing 73 at its distal end.

The reservoir 72 is connected to a portion of the main passage 40 between the three-way valve 57 and each holding valve 60 through the pump passage 80. In the middle of the pump passage 80,
A pump 82 for pumping the brake fluid from the reservoir 72 is provided. The suction side of the pump 82 is provided with a suction valve 84 as a check valve, and the discharge side is provided with a discharge valve 86 as a check valve. The pump 82 is driven by a pump motor 240 described later.

The reservoir 72 is connected to the three-way valve 57 through the supply passage 90, and is connected to the master cylinder 10 via the three-way valve 57. When the three-way valve 57 switches from the illustrated first state to the second state, the brake fluid is introduced from the master cylinder 10 into the reservoir 72,
The brake fluid is sucked by the pump 82 from the master cylinder 10 via the reservoir 72.

A shutoff valve 92 is provided in the supply passage 90 to prevent the brake fluid of the master cylinder 10 from being unnecessarily consumed by the reservoir 72 and the pump 82 during the power assist control. That is, the shut-off valve 92
Is opened when the supply of the brake fluid from the master cylinder 10 to the reservoir 72 is required, and the flow of the brake fluid from the master cylinder 10 to the reservoir 72 is allowed. On the other hand, when it is not necessary to supply the brake fluid from the master cylinder 10 to the reservoir 72, the shut-off valve 92 is closed and the master cylinder 10
Block the flow of brake fluid to the This shut-off valve 92
This is a mechanical valve, and the control of the flow of the brake fluid into the reservoir 72 is realized by the reservoir piston 74.

The shutoff valve 92 includes a check valve member 100 and a valve opening member 102. Check valve member 100
Has a valve 96 and a valve seat 98, allows the flow of the brake fluid from the reservoir to the master cylinder 10, and prevents the flow in the opposite direction. The valve opening member 102 includes a valve 96
Is separated from the valve seat 98 to forcibly open the check valve member 100. The check valve member 100 is connected to the reservoir piston 74 and moves with the sliding of the reservoir piston 74 to move the valve element 9
Move 6.

As shown in FIG. 2, the reservoir piston 74
Is in a normal position (a position where the reservoir chamber 76 is empty), the valve opening member 102 comes into contact with the valve 96 to open the check valve member 100. As a result, the check valve member 100 does not function as a check valve, and the brake fluid is
It is allowed to be introduced into the reservoir 72 from zero. On the other hand, as shown in FIG.
When a stroke exceeds a certain distance from the normal position,
The valve opening member 102 moves in a direction away from the valve element 96 to allow the check valve member 100 to close. When the check valve member 100 is closed, the check valve member 100 functions as a check valve, and the brake fluid is supplied from the master cylinder 10 to the reservoir 7.
2 is prevented.

FIG. 4 shows the electrical configuration of the brake device.

As shown in FIG. 4, the brake device includes a controller 200. The controller 200
It is mainly configured by a computer 208 including a CPU 202, a ROM 204, and a RAM 206. The controller 200 is designed to execute power assist control. In addition, if necessary, various applications such as antilock control and traction control can be provided.

Here, the "power assist control" means that, after the boosting limit of the booster 12, the braking effect caused by the boosting limit is suppressed and the brake operating force F is reduced. By operating the pump 82 in a situation that requires a large braking force to reach the wheel cylinder 50, a higher hydraulic pressure than the master cylinder 10 is generated in the wheel cylinder 50, and the hydraulic pressure of the wheel cylinder 50 at that time is reduced. This means that control is performed so as to be continuously changed according to the operation force F.

As shown in FIG. 4, a wheel speed sensor 21 provided for each wheel is provided on the input side of the controller 200.
0 and the master cylinder pressure sensor 216 are connected. Each wheel speed sensor 210 detects a wheel speed that is a rotation speed of each wheel. Master cylinder pressure sensor 216
Detects the hydraulic pressure generated in the master cylinder 10. The master cylinder pressure sensor 216 does not need to be provided in each of the two brake systems described above, but may be provided in either one of the brake systems.

On the other hand, on the output side of the controller 200,
A brake actuator 230 is connected for each brake system. Each brake actuator 230
It includes one three-way valve 57, two holding valves 60 and two pressure reducing valves 70. The two holding valves 60 and the two pressure reducing valves 70 are brake fluid pressure control valve devices 232 in the sense that the pressure of the wheel cylinder 50 is controlled.
Is configured. A pump motor 240 for driving the pump 82 is connected to the output side. Although one pump motor 240 is provided commonly to the two brake systems, it is naturally possible to provide the pump motor 240 for each brake system. Various control routines including a power assist control routine are stored in the ROM 204.

Next, the operation of the brake device will be described.

FIG. 5 is a flowchart showing a main routine of the power assist control in the brake device. Power assist control turns on the ignition of the vehicle
At step S100 (hereinafter simply referred to as “S1
00 ”. The same applies to other steps. )
Then, the values of the variables stored in the RAM 206 are initialized. Next, the flow shifts to S200, where a control calculation process is executed. Then, the flow shifts to S300, where a system abnormality check is performed. The result of the abnormality check is S4
00, and when it is determined that there is an abnormality, S5
00 to S200 when it is determined that there is no abnormality
Return to

In S500, an abnormality notification process is executed. As the abnormality notification processing, for example, lighting of a brake system abnormality indicator lamp or the like is performed. Then
The flow shifts to S600, where fail-safe processing is performed. After the fail-safe processing is completed, the process returns to S200, and S200
The processing up to S600 is repeatedly performed. When the abnormal mode is fatal, the control execution in S200 may be prohibited in the fail-safe processing in S600.

FIG. 6 shows a flowchart of the control calculation process executed in S200.

First, in S210 of FIG. 6, the wheel speed Vw of each wheel detected by the wheel speed sensor 210 is read, and the vehicle speed Vw is determined based on the largest wheel speed among the wheel speeds Vw. Is calculated, and the vehicle speed V
The vehicle acceleration G is calculated by the differentiation of Further, the master cylinder pressure Pm detected by the master cylinder pressure sensor 216 is AD-converted and read as a physical value [MPa].

Then, the flow shifts to S220, where it is determined whether a start condition or an end condition of the power assist control is satisfied. If the start condition or the end condition of the power assist control is satisfied, the process shifts to S230, and an output process described later is performed. If neither the start condition nor the end condition is satisfied, the control calculation process ends. Here, terminating the control calculation process means that if the power assist control is being performed, the current state of the power assist control is continued as it is.

Here, the conditions for starting the power assist control are as follows:
As the end condition, for example, the following condition may be set. The condition for starting the power assist control is that the master cylinder hydraulic pressure is equal to or higher than a predetermined value or the vehicle body deceleration is equal to or higher than a predetermined value, that is, Pm ≧ A [MPa] or G
It is assumed that the start condition is satisfied when any of ≦ −B [g] becomes true. Here, A and B are both positive constants.

On the other hand, as conditions for ending the power assist control, the master cylinder hydraulic pressure is less than a predetermined value, and
The vehicle speed is less than a predetermined value, that is, Pm <C [MP
It is assumed that the termination condition is satisfied when a] is true and V <D [Km / h] is true. Here, C and D are both positive constants, and A ≧ C.

FIG. 7 shows a flowchart of the output process executed in S230.

In the output process, first, in S231 of FIG.
It is determined whether a condition for starting the power assist control is satisfied. If it is determined that the start condition is satisfied,
The process proceeds to 232, and the power assist control is started. That is, the solenoid operates based on the control signal from the controller 200, and the three-way valve 57 is switched to the second state. As a result, the master cylinder 10
It becomes a state communicating with 2. Further, the pump motor 240 is started based on a control signal from the controller 200,
The pump 82 starts driving. The drive of the pump 82 changes according to the driver's brake operation, and the hydraulic pressure applied to the wheel cylinder 50 changes according to the discharge amount due to the drive of the pump 82.

On the other hand, if it is determined in S231 that the start condition is not satisfied, it is determined that the end condition has been satisfied, and the flow shifts to S233, where power assist control end processing is performed. The power assist control end processing is performed based on a control signal from the controller 200 based on the pump motor 2.
This is a process of stopping the operation of the pump 40 and the pump 82, operating the solenoid, switching the three-way valve 57, and connecting the master cylinder 10 to the wheel cylinder 50.

FIG. 8 is a time chart of the power assist control end processing.

As shown in FIG. 8 (a), the power assist control ending process is performed by the controller 200 using the rear wheels (the right rear wheel RR and the left rear wheel R) in the first system and the second system.
A control signal is output to the L) side pressure reducing valve 70, and the rear wheel side pressure reducing valve 70 is switched from the closed state to the open state based on the control signal. Thus, the wheel cylinder 50 and the reservoir 72 are in communication with each other, and the wheel cylinder 50
From above flows into the reservoir 72. Accordingly, as shown in FIG. 8D, the hydraulic pressure of the wheel cylinder 50 decreases. At this time, the pressure reducing valve 70 on the front wheel side of the first system and the second system remains closed, and each holding valve 60 in the first system and the second system remains open.

After a predetermined time T from the time when the pressure reducing valve 70 is opened, the pressure reducing valve 70 is switched to the closed state based on a control signal from the controller 200. Here, a predetermined time T during which the pressure reducing valve 70 is in the open state.
May be set as appropriate according to the state of decrease in the hydraulic pressure of the wheel cylinder 50, and is set to, for example, about 10 to several 100 ms.

After the elapse of the predetermined time T, as shown in FIG. 8B, a control signal is output from the controller 200 to the second three-way valve 57, and based on the control signal, the second three-way valve 57 is controlled. The valve 57 is switched and the wheel cylinder 50
And a first state in which the master cylinder 10 and the master cylinder 10 communicate with each other. Therefore, the brake fluid flows into the master cylinder 10 from the wheel cylinder 50, and the hydraulic pressure applied to the wheel cylinder 50 further decreases as shown in FIG.

After a certain period of time from the time when the second system three-way valve 57 is set to the first state, the three-way valve 57 is switched based on a control signal from the controller 200,
The second state is established in which the master cylinder 10 and the reservoir 72 communicate with each other. Here, the fixed time during which the three-way valve 57 is in the first state may be appropriately set according to the state of decrease in the hydraulic pressure of the wheel cylinder 50 and the like.

Next, when the three-way valve 57 of the second system is changed from the first state to the second state, as shown in FIG.
A control signal is output from the controller 200 to the first system three-way valve 57 based on a control signal from the controller 200, and the first system three-way valve 57 is moved from the second state to the wheel cylinder 50 and the master based on the control signal. The first state in which communication with the cylinder 10 is established is switched. For this reason, the brake fluid flows into the master cylinder 10 from the wheel cylinder 50, and the hydraulic pressure applied to the wheel cylinder 50 further decreases.

After a certain period of time from the time when the first system three-way valve 57 is set to the first state, the three-way valve 57 is switched based on a control signal from the controller 200,
The second state is established in which the master cylinder 10 and the reservoir 72 communicate with each other. Here, the fixed time during which the three-way valve 57 is in the first state may be appropriately set according to the state of decrease in the hydraulic pressure of the wheel cylinder 50 and the like.

Further, as shown in FIGS. 8B and 8C, the three-way valve 57 of the second system and the three-way valve 57 of the first system are alternately brought into the first state. For this reason, the wheel cylinder 5
The hydraulic pressure of 0 gradually decreases.

As described above, according to the brake device of the present embodiment, the wheel cylinder 50 and the master cylinder 10 communicate with the first and second three-way valves 57 when the power assist control ends. Prior to the first state, the pressure reducing valve 70 disposed between the wheel cylinder 50 and the reservoir 72 is opened for a certain period of time to allow the wheel cylinder 50 and the reservoir 72 to communicate with each other. As a result, the brake fluid flows from the wheel cylinder 50 into the reservoir 72, so that the hydraulic pressure of the wheel cylinder 50 can be reduced to some extent, and the hydraulic pressure difference between the wheel cylinder 50 and the master cylinder 10 can be reduced. Therefore, even if the three-way valves 57 of the first system and the second system are thereafter switched to the first state to allow the wheel cylinder 50 to communicate with the master cylinder 10, the hydraulic pressure of the master cylinder 10 may suddenly increase. This can prevent the driver from feeling uncomfortable through the brake pedal when the brake is released.

After the pressure reducing valve 70 has been opened for a certain period of time, the three-way valves 57 of the first system and the three-way valves 57 of the second system are alternately brought into the first state, so that the wheel cylinder 50
Can be gradually reduced. For this reason,
Furthermore, the driver's discomfort that may occur when the brake is released can be reduced.

Further, it is possible to reduce the noise generated when the hydraulic pressure of the master cylinder 10 rises when the brake is released.

Further, when the brake is released, since the hydraulic pressure of the wheel cylinder 50 drops slowly, the deceleration change can be made smooth.

In the brake device according to the present embodiment, only the pressure reducing valve 70 on the rear wheel side is opened for a certain period of time at the end of the power assist control. Is not limited to
Open the pressure reducing valve 70 on the front wheel side or reduce the pressure reducing valve 7 on all wheels.
0 may be an open state.

[0057]

As described above, according to the present invention, at the end of the brake assist control, before switching the switching valve so that the wheel cylinder and the master cylinder communicate with each other, the switching valve is disposed between the wheel cylinder and the reservoir. The brake fluid is allowed to flow from the wheel cylinder into the reservoir by opening the pressure reducing valve provided for a certain period of time to allow the wheel cylinder to communicate with the reservoir, so that the fluid pressure of the wheel cylinder can be reduced to some extent. For this reason, the hydraulic pressure difference between the wheel cylinder and the master cylinder can be reduced, and the hydraulic pressure of the master cylinder can be prevented from sharply increasing when the wheel cylinder and the master cylinder are subsequently connected. Therefore, it is possible to prevent the driver from feeling uncomfortable through the brake pedal when the brake is released.

Further, it is possible to reduce the noise generated when the hydraulic pressure of the master cylinder increases when the brake is released.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a mechanical structure of a brake device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a shutoff valve of the brake device according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram of a shutoff valve of the brake device according to the embodiment of the present invention.

FIG. 4 is a block diagram showing an electrical configuration of the brake device according to the embodiment of the present invention.

FIG. 5 is a flowchart illustrating a main routine of power assist control of the brake device according to the embodiment of the present invention.

FIG. 6 is a flowchart illustrating a control calculation process of the brake device according to the embodiment of the present invention.

FIG. 7 is a flowchart showing output processing of the brake device according to the embodiment of the present invention.

FIG. 8 is a diagram showing a time chart of a control signal and a change in hydraulic pressure of a wheel cylinder when power assist control of the brake device according to the embodiment of the present invention ends.

[Explanation of symbols]

10 Master cylinder, 50 Wheel cylinder, 57
3-way valve (switching valve), 70: pressure reducing valve, 72: reservoir, 8
2. Pump.

Claims (1)

[Claims] 1. A master cylinder that generates a hydraulic pressure according to a brake operation, a wheel cylinder that operates according to a hydraulic pressure generated in the master cylinder, and a wheel cylinder that is connected to the wheel cylinder through a passage filled with brake fluid, A reservoir capable of containing the brake fluid, a switching valve connected to the master cylinder, the wheel cylinder, and the reservoir, respectively, for selectively communicating the master cylinder to either the wheel cylinder or the reservoir; A pump capable of forcibly supplying the brake fluid in the reservoir to the wheel cylinder side, and a pump disposed in the middle of a passage between the wheel cylinder and the reservoir, in a communication state between the wheel cylinder and the reservoir. A normally-closed pressure-reducing valve that switches between Power assist control means for switching a valve to communicate the master cylinder with the reservoir, operating the pump to supply pressurized brake fluid to the wheel cylinder, and changing the supply amount according to the brake operation And at the time of ending the power assist control in the power assist control means, before switching the switching valve so as to connect the master cylinder to the wheel cylinder, the pressure reducing valve control means for switching the pressure reducing valve to the open state for a predetermined time; ,
Brake device equipped with.