JP2001171510A - Hydraulic pressure braking device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic pressure braking device for a vehicle, provided with negative pressure assisting means and hydraulic pressure assisting means for performing brake control such as traction control, braking and steering control, brake assist control, etc., while efficiently using an output hydraulic pressure of pump means by properly controlling the output hydraulic pressure with a simple constitution. SOLUTION: This device is provided with a negative pressure booster VB, a hydraulic pressure booster HB, and valve means VM for controlling assistance by the hydraulic pressure booster. A solenoid valve device PV is interposed in a reduced pressure side hydraulic pressure path AO which connects and makes communicate a power chamber with a reservoir RV through the valve means to thereby control a flow in the reduced pressure side hydraulic pressure path in accordance with an operation state of a brake pedal BP and/or a vehicle state. At that time, when an output hydraulic pressure of a hydraulic pressure pump HP exceeds a predetermined relief pressure, the relief valve RL is opened, so that the output hydraulic pressure is easily and securely controlled to the pressure lower than the predetermined one.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic brake system for a vehicle, and more particularly, to a hydraulic brake system for driving a master cylinder in response to operation of a brake pedal, comprising both negative pressure boosting means and hydraulic pressure boosting means. The present invention relates to a hydraulic brake device that performs braking control such as traction control, braking steering control, and brake assist control.

[0002]

2. Description of the Related Art A hydraulic brake system having a negative pressure assisting means and a hydraulic assisting means is disclosed, for example, in Japanese Patent Laid-Open No. 52-496.
In Japanese Patent Application Publication No. 9-2006, there is proposed a vehicle brake booster in which the boosting ratio of the booster can be increased by combining a vacuum booster (negative pressure assisting means) and a hydraulic booster (hydraulic pressure assisting means).
In addition, the publication discloses that the boost ratio in the high pressure stage of the brake hydraulic pressure is different from the boost ratio in the low brake hydraulic stage by providing a reaction force mechanism for each of the vacuum booster and the hydraulic booster. Brake boosters that can be set to a boost ratio have also been proposed. The hydraulic boosters provided to these brake boosters use the discharge brake hydraulic pressure of a power steering pump.

In the specification of US Pat. No. 3,976,536, there is disclosed a pneumatic power brake device (negative pressure assisting means) and a hydraulic power brake device (hydraulic pressure) utilizing a discharge brake hydraulic pressure of a power steering pump. It has been proposed to use an auxiliary hydraulic pressure source in a brake device having assisting means) to cope with a case such as when the engine is stopped. Specifically, an electric pump is provided as an auxiliary hydraulic pressure source, a pressure responsive switch is arranged between the pump and the power steering gear, and the electric pump is driven by the pressure responsive switch.

On the other hand, with respect to a brake fluid pressure generating device having a fluid pressure assisting means, a linear solenoid valve is interposed in an output side fluid pressure passage of an electric pump as an auxiliary fluid pressure source so that automatic operation of a brake can be performed. An apparatus has been proposed. For example, German Patent No. 197070376A1 discloses a master cylinder, a hydraulic booster mechanism having a booster piston, a motor-driven pump, and a pressure control valve for controlling boosted hydraulic pressure applied to the booster piston. There is disclosed a brake fluid pressure generating device which is configured to control the pressure control valve by a proportioning solenoid to perform traction control and stability control.

While the vehicle is running, for example, during emergency braking, the brake pedal is depressed at a rapid speed. However, the pedaling force may be insufficient or the pedaling force may be difficult to maintain, and an appropriate braking force may not be obtained. . Further, even in a vehicle provided with an anti-skid control device (ABS), the anti-skid control does not start due to insufficient pedaling force of the brake pedal, and the function of turning angle cannot be sufficiently exhibited. . In view of such a point, it has recently been proposed to add a brake assist control function, and it has already been provided in some commercial vehicles. As described above, the brake assist control automatically increases the braking force and assists the driver's operation of the brake pedal when the brake pedal is depressed at a rapid speed or when the brake pedal is depressed deeply. In general, the voltage boosting function of the vacuum booster is controlled.

[0006]

As described above, various proposals have been made for performing braking control such as traction control and braking steering control (stability maintaining control) by the pump means. In addition to these control functions, There is a demand for a brake device having a brake assist control function. However, in the apparatus described in the above-mentioned Japanese Patent Application Laid-Open No. 52-4969 or U.S. Pat.
Although it is possible to increase the boost ratio, it cannot be said that it has the above-mentioned various braking control functions. In the latter device,
Since the brake fluid pressure is not supplied to the power steering when the engine is stopped, it is configured to drive the electric pump.However, in addition to problems such as complicated piping, a new electric pump is arranged and appropriate fluid pressure control is performed. Required. In particular,
Control of the output hydraulic pressure of the electric pump is not easy, and complicated control is required. For this reason, it is undeniable that the brake device as a whole becomes an expensive device.

On the other hand, according to the device described in German Patent No. 197070376A1, traction control and stability control can be performed by controlling the pressure control valve with a proportioning solenoid. However, the assisting means is only the hydraulic assisting means and does not include the negative pressure assisting means, but temporarily includes both means, and masters the hydraulic assisting means between the two means until the assisting limit of the negative pressure assisting means is reached. The following problem is caused by providing a valve means that prohibits the assistance of the cylinder piston and allows the assistance by the hydraulic assistance means when the assistance limit is exceeded. That is, when the booster chamber is in communication with the reservoir by the valve means, the pressure in the booster chamber cannot be increased even if the booster pump is driven and the proportioning solenoid is closed, so that the master cylinder piston is assisted. Can not do. Therefore, in this case, various types of braking control such as traction control, braking steering control, brake assist control, and automatic brake control cannot be performed.

Accordingly, the present invention provides a hydraulic brake device for a vehicle having a negative pressure assisting means and a hydraulic pressure assisting means as assisting means for driving a master cylinder in response to a brake pedal operation. While appropriately restricting the output hydraulic pressure of the means, it is possible to effectively utilize the output hydraulic pressure of the pump means, perform traction control, brake control such as brake steering control, and when the brake pedal is depressed at a rapid speed, Another object is to make it possible to automatically increase the braking force even when the brake pedal is depressed deeply.

[0009]

In order to solve the above-mentioned problems, the present invention, as described in claim 1, drives a master cylinder piston forward in response to operation of a brake pedal,
A master cylinder that boosts the brake fluid in the reservoir and outputs the brake fluid pressure, negative pressure assisting means that assists the master cylinder piston with a negative pressure according to the operation of the brake pedal, and is independent of the master cylinder. Pump means for increasing the brake fluid in the reservoir to output brake fluid pressure; and a power chamber formed behind the master cylinder piston, wherein the output fluid pressure of the pump means is increased in response to operation of the brake pedal. Hydraulic assisting means for supplying to the chamber and assisting the master cylinder piston, valve means for controlling the assisting of the master cylinder piston by the hydraulic assisting means, and the power chamber being connected to the output side of the pump means. A pressure increasing side hydraulic pressure path, a pressure reducing side hydraulic pressure path connecting the power chamber to the reservoir via the valve means, A solenoid valve device interposed in a hydraulic passage for limiting a flow rate of the pressure reducing hydraulic passage in accordance with an operation state of the brake pedal and / or a vehicle state; and an output side of the pump means in the pressure increasing hydraulic passage. And a relief valve that is interposed between the input side of the solenoid valve device in the pressure reducing hydraulic pressure path, is normally closed, and communicates when the output hydraulic pressure of the pump means exceeds a predetermined relief pressure. Is provided.

The negative pressure assisting means includes a housing defining a constant pressure chamber communicating with a negative pressure source via a movable wall and a variable pressure chamber communicating with the atmosphere, and moves with the movable wall with respect to the housing. And a control valve mechanism for controlling the communication between the variable pressure chamber and the atmosphere and the communication between the variable pressure chamber and the constant pressure chamber in accordance with the operation of the brake pedal. A drive member for driving the master cylinder piston in accordance with the pressure difference between the variable pressure chamber and the constant pressure chamber, wherein the valve member is provided between the brake pedal and the master cylinder piston via the valve means. A first transmitting member disposed between the driving member and the master cylinder piston, and actuating the driving member according to a pressure difference between the variable pressure chamber and the constant pressure chamber. Master syringe A second transmission member for transmitting to a piston, wherein the valve means is controlled in accordance with a relative displacement of the first transmission member with respect to the second transmission member, and a difference between the variable pressure chamber and the constant pressure chamber is provided. When the pressure is equal to or less than a predetermined value, the valve means is set to the first position, and when the differential pressure between the variable pressure chamber and the constant pressure chamber exceeds a predetermined value, the valve means is set to the second position, and It is preferable that the brake pedal and the master cylinder piston are engaged so as to be able to transmit force via a valve means and the first transmission member. Furthermore,
It is preferable that an elastic member is provided between the second transmitting member and the driving member, and the first transmitting member is connected to the brake pedal without the elastic member.

The solenoid valve device may be configured such that the solenoid valve device communicates with the power chamber side and communicates with an output side of the relief valve. A valve seat formed on the input side of the valve device, a valve body seated on the valve seat from the side opposite to the input side of the solenoid valve device toward the input side, and the valve body is connected to the valve seat when not energized. A biasing means for biasing the valve body in a direction to be seated on the valve seat at the time of excitation, wherein a hydraulic pressure on the power chamber side is larger than the predetermined relief pressure. When the pressure exceeds the pressure, the valve may be separated from the valve seat against an urging force in a direction in which the valve is seated on the valve seat at the time of excitation.

Further, as described in claim 3, between the output side of the pump means and the input side of the relief valve, a one-way for allowing a flow to the power chamber and prohibiting a flow in the opposite direction. It is preferable that a valve is interposed.

The detecting means includes a pedal operation amount sensor for detecting an operation amount of the brake pedal. The detection output of the pedal operation amount sensor is compared with a predetermined operation amount, and is smaller than a predetermined operation amount. In some cases, the pump means may be stopped, and the pump means may be driven when a predetermined operation amount is exceeded. The pedal operation amount sensor that detects the operation amount of the brake pedal includes a stroke sensor that detects the stroke of the brake pedal, a tread force sensor that detects the tread force on the brake pedal, and a pressure sensor that detects the output brake fluid pressure of the master cylinder. It is possible to determine the drive start of the pump means by using the stroke output, the pedal effort, the master cylinder hydraulic pressure, and / or the differential value of these detection outputs. In this case, the criterion is desirably set to a value immediately before the negative pressure assisting unit reaches the assisting limit in order to ensure a smooth transition when the assisting by the hydraulic assisting unit is added.

Alternatively, the detecting means includes a pressure sensor for detecting a pressure in the variable pressure chamber of the negative pressure assisting means, and compares a detection output of the pressure sensor with a predetermined pressure. The pump means may be stopped and the pump means may be driven when a predetermined pressure is exceeded. The drive start of the pump means can be determined using the detection output of the pressure sensor and / or its differential value. In this case, the criterion is a smooth operation when the assistance by the hydraulic assist means is added. In order to secure the transition, it is desirable to set a value immediately before the negative pressure assisting unit reaches the assisting limit.

[0015]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. First, an outline of an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the hydraulic brake device of the present embodiment has a master cylinder MC, a negative pressure booster VB and a hydraulic pressure booster HB, and the master cylinder piston MP is driven forward in response to the operation of the brake pedal BP. The brake fluid introduced from the reservoir RV is compressed, and the brake fluid pressure is output from the pressure chambers R1 and R2. The negative pressure booster VB and the hydraulic pressure booster HB assist the operation of the master cylinder piston MP in response to the operation of the brake pedal BP, and constitute the negative pressure assisting means and the hydraulic pressure assisting means of the present invention, respectively. The output brake fluid pressure of the master cylinder MC is supplied to a wheel cylinder (not shown) mounted on each wheel of the vehicle.

The negative pressure booster VB has a housing HS defining a constant pressure chamber CP and a variable pressure chamber VP via a movable wall MW.
And a driving member AM supported by the pressure chamber CP.
Is connected to a negative pressure source such as an intake manifold (not shown). The drive member AM is movably supported with the movable wall MW with respect to the housing HS, and communicates with the variable pressure chamber VP and the atmosphere in response to the operation of the brake pedal BP, and the variable pressure chamber V
And a control valve mechanism CV for controlling the communication between the pressure control chamber CP and the constant pressure chamber CP. The MP is configured to be boosted.

In this embodiment, the power piston PP is disposed so as to abut the rear end of the master cylinder piston MP. The power piston PP is provided with a communication passage communicating with the liquid chambers formed before and after the power piston PP. The communication passage is opened until the negative pressure booster VB reaches the assisting limit. First transmission member TM1
Constitutes valve means VM to be closed. That is,
As shown in FIG. 1, a first transmission member TM1 is disposed between a brake pedal BP and a master cylinder piston MC via a valve means VM, and further, a negative pressure booster is provided so as to surround the first transmission member TM1. A second transmission member TM2 is disposed between the VB drive member AM and the master cylinder piston MC, and in this embodiment, a power piston P is provided at the front end thereof.
P is formed integrally.

The valve means VM is controlled in accordance with the relative displacement of the first transmission member TM1 with respect to the second transmission member TM2. Specifically, the transformation chamber VP
When the pressure difference between the pressure chamber CP and the constant pressure chamber CP is equal to or less than a predetermined value, the valve means VM is set to the first position, and when the pressure difference between the variable pressure chamber VP and the constant pressure chamber CP exceeds the predetermined value, the valve means VM To the second position, the valve means VM and the first transmission member TM1
, The brake pedal BP and the master cylinder piston MC are engaged so as to be able to transmit a force. Further, between the second transmission member TM2 and the driving member AM,
The reaction force elastic member RD is interposed, and the first transmission member T
M1 is arranged so as to be connected to the brake pedal BP without passing through the reaction force elastic member RD (through the reaction force elastic member RD).

On the other hand, a hydraulic pump HP driven by an electric motor M is provided as the pump means of the present invention, and the brake hydraulic pressure is output independently of the master cylinder MC. The input side of the hydraulic pump HP is the reservoir RV.
And the output side is connected to a liquid chamber (power chamber RP) on the rear side of the power piston PP via a one-way valve (check valve) CH, and the output hydraulic pressure of the hydraulic pump HP is connected to this liquid chamber. When (power hydraulic pressure) is supplied, the power piston PP is driven forward and the master cylinder piston MP is assisted.

As shown in FIG. 1, a power chamber RP formed on the rear side of the master cylinder MC is provided with a pressure-increasing hydraulic pressure line AI.
And the output side of the hydraulic pump HP is connected to the reservoir RV via the pressure-reducing hydraulic passage AO. A solenoid valve device PV is interposed in the pressure-reducing hydraulic passage AO, and the pressure-reducing hydraulic passage AO depends on the operation state of the brake pedal BP and / or the vehicle state.
Is configured to limit the flow rate. The solenoid valve device PV is a proportional control valve, which controls the pressure difference before and after the valve so as to change in proportion to the solenoid drive current, and the structure thereof will be described later with reference to FIG.

Further, the hydraulic pressure line AC between the output side of the hydraulic pump HP in the pressure increasing hydraulic pressure line AI and the input side of the solenoid valve device PV in the pressure reducing hydraulic pressure line AO is normally closed. A relief valve RL that communicates when the output hydraulic pressure of the pressure pump HP exceeds a predetermined relief pressure is provided.
The structure of the relief valve RL will be described later with reference to FIG.
Therefore, the one-way valve CH is interposed between the output side of the hydraulic pump HP and the input side of the relief valve RL.

In the present embodiment, a pressure sensor DT1 for detecting the pressure in the variable pressure chamber VP is provided as first detecting means for detecting the operating state of the negative pressure booster VB, and the output signal thereof is transmitted to an electronic control unit. It is configured to be supplied to the ECU. Alternatively or together with this, a stroke sensor DT2 for detecting the stroke of the brake pedal BP is provided as second detection means for detecting the operation amount of the brake pedal BP, as indicated by a broken line in FIG. May be supplied to the electronic control unit ECU.

The electronic control unit ECU includes a brake switch (not shown) which is turned on when the brake pedal BP is depressed, a wheel speed sensor (not shown) as a vehicle state detecting means, An acceleration sensor YG, a hydraulic pressure sensor PS, and the like are connected, and these output signals are configured to be input to the electronic control unit ECU. The electronic control unit ECU of the present embodiment is a microcomputer including a CPU (not shown), a ROM, a RAM (not shown), an input port, an output port (not shown), and the like, which are interconnected via a bus. The output signals of the above-described sensors and the like are configured to be input to the CPU from input ports via an amplifier circuit (not shown).

When the electronic control unit ECU determines that at least one of the detection outputs of the pressure sensor DT1 and the stroke sensor DT2 exceeds a predetermined reference value, the electric motor M is driven and the hydraulic pressure is increased. The output hydraulic pressure of the pump HP is supplied to the power chamber RP behind the power piston PP. Then, when the assisting limit of the negative pressure booster VB is reached and the operation of the drive member AM reaches the limit, the second transmission member TM2 is at a predetermined position, whereas the first transmission is performed in response to the operation of the brake pedal BP. The member TM1 moves forward, the valve means VM operates according to the relative displacement, and the communication path of the power piston PP is closed. As a result, the liquid chamber behind the power chamber RP is sealed, so that the hydraulic pump HP
The master cylinder piston MP is assisted by the output hydraulic pressure.

The solenoid valve device PV is controlled by the electronic control unit ECU so that the differential pressure before and after the brake pedal BP changes in proportion to the solenoid drive current in accordance with the operation state of the brake pedal BP and / or the vehicle state. Is done. Thus, the operation state of the brake pedal BP and / or the vehicle state is determined based on the detection output of each of the above sensors, and the solenoid valve device PV is appropriately controlled in accordance with these states, and the pressure-reducing hydraulic pressure path AO And various braking controls such as traction control, braking steering control, and brake assist control are performed as described later.

Here, the drive start determination of the hydraulic pump HP will be described. First, the pressure (Pv) in the variable pressure chamber VP detected by the pressure sensor DT1 is equal to the predetermined pressure K.
The electric motor M is started when it is larger than p, and the brake hydraulic pressure is output from the hydraulic pump HP.
In other words, power is not supplied to the electric motor M until the pressure Pv (negative pressure) in the transformation chamber VP reaches the predetermined pressure Kp.
Therefore, the hydraulic pump HP is in a stopped state. Predetermined pressure Kp
Is set based on the assist limit of the negative pressure booster VB. In order to ensure a smooth transition when the assist of the hydraulic booster HB is added by the hydraulic pump HP, the pressure in the variable pressure chamber VP must be equal to the atmospheric pressure. (That is, immediately before the negative pressure booster VB reaches the assisting limit).

Further, the pressure Pv in the transformation chamber VP is differentiated,
The change amount DPv of the pressure Pv may be obtained, and the change amount DPv may be compared with a predetermined value Kdp. In this case, the predetermined value Kdp is also set to the pressure change amount immediately before the negative pressure booster VB reaches the assisting limit. Is desirable. Then, as a determination condition, the comparison result of the above-described pressure Pv and the predetermined pressure Kp may be combined, and the electric motor M may be started when both conditions are satisfied. Further, in addition to these conditions, the output of an existing brake switch (not shown) for detecting that the brake pedal BP has been operated is added, the brake switch is turned on, and the pressure P
The electric motor M may be configured to be activated when v and / or the change amount DPv exceeds a predetermined pressure Kp and / or a predetermined value Kdp.

Alternatively, a stroke sensor DT2 indicated by a broken line in FIG. 1 is used as a means for detecting the operation amount of the brake pedal BP, and the stroke (St) of the brake pedal BP, which is the detection output, is determined by a predetermined stroke KS.
The configuration may be such that the electric motor M is activated when it becomes larger than the value t. Even in this case,
The predetermined stroke KSt is desirably set to a value immediately before the negative pressure booster VB reaches the assist limit in order to ensure a smooth transition when the assist by the hydraulic pressure booster HB is added. Further, the stroke St is differentiated, and the change amount D is obtained.
St may be obtained and compared with a predetermined value Kds. In this case, it is preferable that the predetermined value Kds is also set to the stroke change amount immediately before the negative pressure booster VB reaches the assisting limit. Further, the configuration may be such that the electric motor M is started when both the conditions of the stroke St and the change amount DSt are satisfied.

As means for detecting the operation amount of the brake pedal BP, a pedaling force sensor (not shown) for detecting a pedaling force on the brake pedal BP, and a master cylinder MC
Pressure sensor (not shown) for detecting output brake fluid pressure
The driving start of the hydraulic pump HP can also be determined using the pedaling force or the master cylinder hydraulic pressure, which are the detection results, and / or their differential values. Further, a vehicle speed sensor (not shown) may be provided to drive and control the electric motor M according to the output signal thereof, and control the operation of the hydraulic pump HP according to the vehicle speed.

According to the hydraulic brake device of the present embodiment having the above configuration, the input / output characteristics shown in FIG. 2 can be obtained according to the operation of the brake pedal BP. FIG. 2 shows FIG.
(Depressing force on brake pedal 2) and output (output brake fluid pressure of master cylinder MC) in the embodiment of FIG.
The solid line indicates the assisting operation by the negative pressure booster VB, the broken line (MB) indicates the assisting limit of the negative pressure booster VB, and the two-dot chain line (DB) indicates the assisting by the negative pressure booster VB. The characteristics when the assistance by the hydraulic booster HB is added are shown below. A two-dot chain line (FL) in the lower part of FIG. 2 indicates that the negative pressure booster VB has failed and the hydraulic pressure booster HB has failed.
The characteristic when only the assisting operation is performed is indicated by a broken line (F
M) shows the hydraulic characteristics of only the master cylinder.

First, during normal brake operation,
When the brake pedal BP is operated, the state shown in FIG. 1 at the time of non-operation is changed to the state shown in FIG. 3, and the atmosphere is introduced into the variable pressure chamber VP as indicated by an arrow, and assist is performed by the negative pressure booster VB. 2 shows the characteristics indicated by the solid line and the broken line (MB). Further, the brake pedal BP is operated, and the pressure Pv in the variable pressure chamber VP detected by the pressure sensor DT1 becomes a predetermined pressure K.
When it becomes larger than p, the electric motor M is started, and the discharge brake fluid of the hydraulic pump HP is supplied to the power chamber RP behind the power piston PP. Then, as shown in FIG. 4, the pressure in the variable pressure chamber VP becomes substantially the atmospheric pressure, and the constant pressure chamber CP and the variable pressure chamber VP
When the pressure difference between the first transmission member TM1
When the valve means VM is closed, the power piston PP is driven forward by the output hydraulic pressure of the hydraulic pump HP. Thus, in addition to the assisting by the negative pressure booster VB, the assisting by the hydraulic booster HB is performed, and the characteristic shown by the two-dot chain line (DB) in FIG. 2 is obtained.

In this case, even if the rotation speed of the hydraulic pump HP is increased to a predetermined value or more, when the output hydraulic pressure of the hydraulic pump HP exceeds a predetermined relief pressure, the relief valve RL is opened and communicates. Therefore, the upper limit of the power hydraulic pressure in the power chamber RP, that is, the maximum pressure at the time of hydraulic pressure assist is set.
It should be noted that when the negative pressure booster VB fails, only the hydraulic booster HB assists, and the two-dot chain line (FL) in FIG.
The characteristic shown by.

Further, for example, when the brake pedal is depressed at a rapid speed, a braking force is automatically applied by the brake assist control, and the characteristic is indicated by a one-dot chain line (BA) in FIG. Further, according to the hydraulic brake device of the present embodiment, the braking force on each wheel can be controlled irrespective of the operation of the brake pedal BP, and for example, braking steering control can be performed to ensure stable running of the vehicle. In this case, a brake fluid pressure larger than the relief pressure (two-dot chain line DB) may be required.
The characteristic (AB) that matches the vertical axis is obtained by the function of (1).

Next, in various braking controls such as braking steering control, when an ignition switch (not shown) is closed, execution of a program corresponding to the flowchart of FIG. 11 is started, and the electronic control unit ECU executes the program. A series of processes such as braking steering control and brake assist control are performed. FIG. 11 shows the whole braking control operation. Initially, in step 101, initialization is performed, and various calculated values are cleared. Next, in step 102, a detection signal of a wheel speed sensor (not shown) and the like are read, a detection signal of the lateral acceleration sensor YG (actual lateral acceleration Gya) and a detection signal of the hydraulic pressure sensor PS (master cylinder hydraulic pressure Pmc). ) Is read. In the present embodiment, the detected master cylinder hydraulic pressure Pmc of the hydraulic pressure sensor PS is used as the brake operation amount, but a brake pedal stroke, which is a detection output of the stroke sensor DT2 shown by a broken line in FIG. 1, may be used.

Then, the program proceeds to a step 103, wherein the master cylinder pressure Pmc is differentiated to obtain a master cylinder pressure change ratio DPmc. Then, in step 104, the wheel speed Vw ** (** represents each wheel FR etc.) of each wheel is calculated, and these are differentiated to obtain the wheel acceleration DV of each wheel.
w ** is required. Subsequently, in step 105, the maximum value of the wheel speed Vw ** of each wheel is calculated as the estimated vehicle speed Vso at the position of the center of gravity of the vehicle (Vso = MAX (Vw *
*)). Further, an estimated vehicle speed Vso ** is obtained for each wheel based on the wheel speed Vw ** of each wheel, and if necessary, normalization is performed to reduce an error based on a difference between the inner and outer wheels when the vehicle turns. . Further, the estimated vehicle speed Vso is differentiated, and the estimated vehicle acceleration DVso at the position of the vehicle center of gravity is calculated.

In step 106, the actual slip ratio of each wheel is determined based on the wheel speed Vw ** of each wheel and the estimated vehicle speed Vso ** (or the normalized estimated vehicle speed) obtained in steps 104 and 105. Sa ** is Sa **
= (Vso **-Vw **) / Vso **. Next, in step 107, based on the estimated vehicle body acceleration DVso at the position of the center of gravity of the vehicle and the actual lateral acceleration Gya detected by the lateral acceleration sensor YG, the road surface friction coefficient μ is approximately (DV
so ² + Gya ² ) ^1/2 . Further, as means for detecting the road surface friction coefficient, various means such as a sensor for directly detecting the road surface friction coefficient can be used.

Subsequently, at step 108, brake assist control is performed, and the drive of the solenoid valve device PV and the electric motor M is controlled. That is, when the electric motor M is started and the hydraulic pump HP is driven, the discharge brake fluid is supplied to the power chamber RP behind the power piston PP. In this state, by controlling the solenoid valve device PV, the flow rate of the brake fluid discharged from the power chamber RP through the pressure-reducing hydraulic pressure path AO is limited, so that the pressure in the power chamber RP is increased. Brake fluid pressure (power fluid pressure)
Drives the master cylinder MP.

Specifically, a target value (target differential pressure Pd) of the pressure difference before and after (upstream and downstream) of the solenoid valve device PV.
Is set according to a predetermined target differential pressure map (not shown). This target differential pressure map is set so as to match the characteristic shown by the one-dot chain line (BA) in FIG. 2. For example, when the master cylinder hydraulic pressure Pmc becomes the predetermined hydraulic pressure P1, the target differential pressure map becomes the target hydraulic pressure. If the differential pressure Pd is gradually increased and the target differential pressure Pd is set to a constant value after reaching a predetermined value, smooth brake assist control can be performed. According to the target differential pressure Pd set in this way,
The drive current of the solenoid valve device PV is set, and the solenoid valve device PV is driven.

Then, the routine proceeds to step 109, where various control modes including the brake steering control mode are set, target slip ratios to be used for the various control modes are set, and the electric pump M and each The braking force on the wheels is controlled. In the brake steering control, regardless of whether or not the brake pedal BP is operated, a braking force is automatically applied to each wheel to apply a braking force, and oversteer suppression control and / or understeer suppression control is performed. Is superimposed on the control in all the control modes. In this braking steering control (and traction control), the solenoid valve device PV is fully closed.

As another control mode, in the anti-skid control mode, a braking force applied to each wheel is controlled so as to prevent locking of the wheel when the vehicle is braked. In the front / rear braking force distribution control mode, the distribution of the braking force applied to the rear wheels to the braking force applied to the front wheels is controlled so as to maintain stability of the vehicle during braking of the vehicle. And in the traction control mode,
A braking force is applied to the drive wheels so as to prevent the drive wheels from slipping when the vehicle is driven, and throttle control is performed as necessary. The drive force to the drive wheels is controlled by these controls. Then, after performing hydraulic servo control in step 110 based on these control modes, the process returns to step 102. If the brake steering control start condition is not satisfied in step 109 and no control mode is set, the process returns to step 102.

In the normal braking operation, the control of the electric motor M is performed, for example, when the pressure Pv in the variable pressure chamber VP detected by the pressure sensor DT1 becomes larger than a predetermined pressure Kp, the electric motor M is started. Thus, the hydraulic pump HP is stopped until the negative pressure booster VB reaches the assisting limit, and the negative pressure booster VB is stopped.
The electric motor M is started at an appropriate time before reaching the assisting limit, and the discharge brake fluid of the hydraulic pump HP is supplied to the power chamber RP on the rear side of the power piston PP. Then, when the negative pressure booster VB reaches the assisting limit, the valve means VM is closed by the first transmission member TM1, and the assisting by the hydraulic booster HB is immediately added. Thereby, the operation frequency of the electric motor M and the hydraulic pump HP can be minimized. Further, since the hydraulic pump HP is started before the negative pressure booster VB reaches the assisting limit, the mode changes from assisting only by the negative pressure booster VB to assisting by both the negative pressure booster VB and the hydraulic pressure booster HB. On the other hand,
The transition can be made smoothly with good responsiveness. Therefore, it is also effective in ensuring responsiveness in an emergency.

Further, by monitoring the detection output of the pressure sensor DT1 and the like, it is possible to detect the absolute pressure shortage of the negative pressure source connected to the negative pressure booster VB. In this case, the hydraulic pressure booster HB assists. Since a necessary braking force can be secured, it is effective in securing a so-called partial braking force. Further, the negative pressure booster V can be provided with a simple structure such as the valve means VM without a complicated control device.
The assistance by the hydraulic booster HB after B reaches the assistance limit can be smoothly added. In addition, the hydraulic pump H
Since P is connected to the power chamber RP on the rear side of the power piston PP via the one-way valve CH, the hydraulic pump HP
Is stopped, the brake fluid does not flow out of the power chamber RP via the hydraulic pump HP, so that a smooth operation can be maintained.

Next, another embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIGS. FIG. 5 shows a specific structure of a hydraulic brake device according to another embodiment, FIG. 6 shows an enlarged view of the master cylinder section 10, and FIG. 7 shows an enlarged view of the hydraulic booster section 20 and the negative pressure booster 40. Is shown. The present embodiment is different from the embodiment of FIG. 1 in the structure of the part constituting the hydraulic pressure assisting means. In other words, the specific configuration of the master cylinder MC and the negative pressure booster VB in the above-described embodiment of FIG. 1 is the same as the structure shown in FIG. 5, but the hydraulic pressure booster HB and the first and second transmission members TM
1 and TM2 are different. Other configurations of the electronic control unit ECU, the solenoid valve device PV, and the like are the same as those in the embodiment of FIG. 1, and therefore, the same components are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 5, a master cylinder section 10 and a hydraulic booster section 20 are provided on the front side (left side in FIG. 5) of the vehicle, and a negative pressure booster 40 is provided behind the master cylinder section 10 and a hydraulic pressure booster section 40, and further behind the same. Is provided with a brake pedal BP (omitted in FIG. 5). The depressing force applied to the brake pedal BP is transmitted as a brake operating force via the input rod 3 and is assisted by the negative pressure booster 40. When the negative pressure booster 40 reaches the assisting limit, the hydraulic pressure is further increased. The brake fluid pressure is output from the master cylinder unit 10 by being assisted by the booster unit 20. The output brake fluid pressure of the master cylinder unit 10 is supplied to a wheel cylinder (not shown) mounted on each wheel of the vehicle.

As shown in FIG. 6, the master cylinder unit 10 has a first piston 11a in a cylinder body including a first cylinder 1a and a second cylinder 1b and a third cylinder 1c housed therein. And the second piston 12 is accommodated. The first cylinder 1a is a bottomed cylindrical body, and is formed with a stepped hole so that the inner diameter increases gradually toward the opening. The second cylinder 1b is a substantially cylindrical body and a cylinder bore 1d is formed. The third cylinder 1c is a bottomed cylindrical body having a flange, and a cylinder bore 1e having an inner diameter larger than the inner diameter of the cylinder bore 1d is formed. A communication hole 1f (FIG. 7) having a diameter smaller than the inner diameter of the cylinder bore 1d is formed at the bottom. Also, the first cylinder 1
a, liquid supply ports 1g and 1h, output ports 1j and 1k, and a discharge port 1r are formed.
An input port 1p (FIG. 7) is formed at c.

The second cylinder 1b is provided with a communication hole 1 in the radial direction.
The third cylinder 1c is housed in the first cylinder 1a via an annular member 17 on which 7a is formed and a cup-shaped sealing member (represented by S1) disposed on both sides thereof. An annular member 1 having a communication hole 18a formed in a radial direction.
8 and a seal member S1 disposed on both sides of the first cylinder 1a.

A first piston 11 of a bottomed cylinder is slidably housed in the cylinder bore 1d in a liquid-tight manner, and a pressure chamber R1 is formed between the first cylinder 1a and the first piston 11. Have been. When the first piston 11 is not operated, the communication hole 11 a formed in the skirt portion thereof is
The pressure chamber R1 is configured to communicate with the reservoir 4 via the liquid supply port 1g.

The second piston 12 has concave portions 12b and 12c formed at both ends thereof, and as shown in FIG.
The rear end is enlarged in diameter to form a large diameter portion 12e. As shown in FIG. 6, the front end of the second piston 12 is slidably housed in the cylinder bore 1d in a liquid-tight manner.
A pressure chamber R2 is defined between the first piston 11 and the second piston 12 in the cylinder bore 1d. When the second piston 12 is not operated, the communication hole 12a formed in the skirt portion of the second piston 12 faces the communication hole 18a of the annular member 18, and the pressure chamber R2 communicates with the reservoir 4 via the liquid supply port 1h. Is configured. The valve seat member 21 is housed in the concave portion 12c behind the second piston 12,
The distal end of the valve member 31v is configured to be able to be seated, which will be described later.

In the cylinder bore 1e of the third cylinder 1c, a power chamber RP is formed between the rear end surface of the large diameter portion 12e and the bottom of the concave portion of the third cylinder 1c. Are configured to communicate with each other. A liquid chamber R3 is defined between the outer peripheral surface of the second piston 12 on the front side of the large-diameter portion 12e and the inner peripheral surface of the cylinder bore 1e, and the liquid chamber R3 always communicates with the discharge port 1r. Is configured. A communication hole 12f is formed in the radial direction on the front side of the large diameter portion 12e of the second piston 12, and the recess 12c communicates with the liquid chamber R3.

In FIG. 6, a spring 13 is stretched between the bottom of the recess in the first cylinder 1a and the bottom of the recess of the first piston 11 so that the first piston 11 moves in the direction of the second piston 12. Being energized. Further, one end of a rod 14 is fixed to the bottom surface of the concave portion 12b in front of the second piston 12, and the distal end of the retainer 16 is disposed on the head at the other end so as to be locked. The retainer 16 is disposed such that the bottom thereof abuts the rear end surface of the first piston 11, and the bottom of the retainer 16 and the second piston 1
A spring 15 is stretched between the bottom of the recess 12b and the front of the second piston 12 and is urged in a direction in which the space between the first piston 11 and the second piston 12 expands.

Next, the hydraulic booster section 20 is formed at the rear end of the second piston 12, as shown in FIG.
That is, in the present embodiment, the master cylinder piston includes the first piston 11 and the second piston 12,
Is configured such that the large diameter portion 12e functions as a power piston of the hydraulic booster.
Of course, the power piston may be formed separately from the rear end of the second piston 12 including the large-diameter portion 12e. The valve seat member 21 is accommodated in the concave portion 12c formed on the large diameter portion 12e side. This valve seat member 21
Has a valve seat 21a formed at one end, and an axial communication hole 21b opening to the valve seat 21a and a radial communication hole 21c communicating with the axial communication hole 21b. Therefore, the valve member 31
When the leading end of the valve seat v is separated from the valve seat 21a, the power chamber RP
Communicates with the liquid chamber R3.

Communication hole 1 formed in third cylinder 1c
f, a second transmission member 32 to be described later is slidably housed in a liquid-tight manner, and a hollow portion 32a of the second transmission member 32 houses a valve member 31v slidably in a liquid-tight manner. . An annular groove is formed on the inner surface of the communication hole 1f, and an annular groove is also formed on the inner surface separated from the inner surface by a predetermined distance in the axial direction. S3) is accommodated, and the sealing performance with respect to the power chamber RP is ensured.

Next, in the negative pressure booster 40, container-shaped housings 41a and 41b called shells are superimposed via a movable wall 42, a constant pressure chamber (negative pressure chamber) CP is formed in front, and the pressure is changed in rear. A chamber VP is defined. The constant pressure chamber CP is connected to a negative pressure source such as an intake manifold (not shown) via an inlet 41c (FIG. 5), and the negative pressure is maintained. The movable wall 42 is composed of a pressure receiving plate 42a and a diaphragm 42b. One opening end of a cylindrical driving member 43, also called a power piston, is air-tightly fixed to the center of the pressure receiving plate 42a and the other opening end of the driving member 43. Extends rearward through the housing 41b.

The drive member 43 is slidably supported by the opening of the housing 41b via a seal member S4, and is further surrounded by a boot BT. Although the boot BT is fixed to the input rod 3, the driving member 4
A communication hole BTa is formed at the opening end of the opening 3. The front end of the drive member 43 and the front housing 41a
A spring 44 is disposed between the movable wall 4 and the inner surface of the movable wall 4.
2 is urged toward the rear housing 41b.

The input rod 3 is disposed so as to be located on the central axis in the driving member 43, and the plunger 45 is connected to the tip of the input rod 3 via a ball joint. This plunger 45
Is an axial communication hole 43a formed in the driving member 43.
Slidably supported by A valve seat 43b is formed around the communication hole 43a, and surrounds the valve seat 43b, and an annular valve body 46 is in contact with the valve seat 43b.
a of the first control valve mechanism 46 by urging the
Is configured within. The first control valve mechanism 46 is called a control valve.
A second control valve mechanism 47 formed by forming a valve seat 45b at the rear end of the valve 5 and urging an annular valve body 47a so as to abut the valve seat 45b is connected. The second control valve mechanism 47 is called an air valve. A valve body 47a is formed at a front end of a cylindrical elastic member, and is arranged so as to be biased in a direction of a valve seat 43b by a spring 48a supported at a rear end. ing. The rear end of the elastic member constituting the second control valve mechanism 47 is also arranged so as to be urged in the direction of the valve seat 43b by a spring 48b, and a step 43c formed inside the drive member 43 by this urging force. It is locked to.

An annular reduced diameter portion 45a is formed behind the sliding portion formed at the tip of the plunger 45, and a key member is provided so as to be able to move a predetermined distance in the axial direction with respect to the reduced diameter portion 45a. 49 are fitted. The key member 49 protrudes from the outer periphery of the driving member 43 and is arranged so as to engage with the housing 41b so as to restrict the axial movement of the plunger 45 rearward, whereby the return position of the movable wall 42 is defined. .

A recess 43d is formed in front of the driving member 43, and a plug member 34 for supporting the intermediate member 31t, the reaction rubber disc 33 and the rear end 32b of the second transmission member 32 is provided in the recess 43d. Mated. Intermediate member 3
1t, together with the valve member 31v, constitutes the first transmission member of the present invention, and has a projection 31a at its tip extending through the reaction rubber disc 33 and extending forward. The rear end of the intermediate member 31t contacts the rear end surface of the plunger 45 at the rear end of the valve member 31v, and is supported movably in the axial direction by a predetermined distance. Therefore, the intermediate member 31t and the valve member 31v correspond to the first transmission member TM1 in the embodiment of FIG. In other words, in this embodiment, the first transmission member TM1 is divided into two parts. The reaction rubber disc 33 is substantially the same as the reaction elastic member RD in the embodiment of FIG.

On the other hand, the second transmission member 32 has a hollow portion 32a.
And a flange 32b at the rear end.
2b is provided so as to be fitted to the plug member 34. An axial communication hole 32c communicating with the hollow portion 32a is formed in the flange portion 32b, and the intermediate member 31t extends into the hollow portion 32a through the communication hole 32c, and the protrusion 3
1a is disposed so as to be able to contact the valve member 31v. A communication hole 32d is formed in the front end portion of the second transmission member 32 in the radial direction, and the hollow portion 32a communicates with the power chamber RP at the front end portion.

When the pressure of the movable wall 42 reaches a predetermined value due to a rise in the pressure in the variable pressure chamber VP during the assisting by the negative pressure booster 40, the portion where the reaction rubber disc 33 faces the intermediate member 31t is removed. The intermediate member 31t swells backward.
And a rearward reactive force proportional to the pressing force of the movable wall 42 is applied to the intermediate member 31t and the plunger 45, and the difference between the reactive force and the operating force applied to the input rod 3 is increased. , The first control valve mechanism 46 and the second control valve mechanism 47 are controlled. Also, the hydraulic booster section 20
At the time of assisting, the power hydraulic pressure of the integral of the cross section is transmitted to the input rod 3 as a reaction force of the hydraulic booster section 20 to the valve member 31v accommodated in the second transmission member 32.

As shown in FIG. 5, in this embodiment, a hydraulic pump HP driven by an electric motor M is provided similarly to the above-described embodiment.
Has an input side connected to the reservoir 4 and an output side connected to the power chamber RP via the one-way valve CH. Thus,
When the output hydraulic pressure of the hydraulic pump HP is supplied to the power chamber RP, the negative pressure booster 40 reaches the assisting limit and the valve seat member 2
When the valve member 31v is seated on the first piston 12, the second piston 12
Is further assisted by the output hydraulic pressure of the hydraulic pump HP. Further, a pressure sensor DT1 for detecting the pressure in the variable pressure chamber VP of the negative pressure booster 40 is provided, and the start of driving the hydraulic pump HP is determined based on the detected output. As in the embodiment of FIG. 1, a pedal operation amount sensor or the like for detecting the operation amount of the brake pedal BP is provided instead of or together with the pressure sensor DT1, and the hydraulic pump HP May be determined.

The overall operation of the hydraulic brake device having the above configuration will be described. First, when the brake pedal BP is in a non-operation state, each component is in a state shown in FIGS. Accordingly, the negative pressure booster 40 is in a non-operating state, the second control valve mechanism 47 is in a closed state with the valve body 47a abutting against the valve seat 45b, and the air is introduced into the variable pressure chamber VP. Has been blocked. At this time, only the negative pressure in the constant pressure chamber CP is acting on the first control valve mechanism 46.

When the brake pedal BP is operated and an operating force is applied to the input rod 3, the valve body 47a of the second control valve mechanism 47 of the negative pressure booster 40 is separated from the valve seat 45b,
If the sum of the operating force on the input rod 3 and the force for urging the input rod 3 forward by the pressure difference between the pressure in the variable pressure chamber VP and the pressure in the constant pressure chamber CP exceeds the urging force of the spring 48b, The input rod 3 and the plunger 45 move forward,
A first control valve mechanism 46 is provided for the valve seat 43b of the drive member 43.
Of the variable pressure chamber VP and the constant pressure chamber CP are cut off. Then, the valve body 47a of the second control valve mechanism 47 separates from the valve seat 45b, and the communication hole B of the boot BT.
The atmosphere is introduced into the transformation chamber VP through Ta, and the transformation chamber V
The pressure in P increases. As a result, a force for pressing the movable wall 42 forward is generated, and the second piston 12 is driven forward via the plug member 34, the reaction rubber disc 33, the second transmission member 32, and the valve seat member 21. Further, the first piston 11 is driven forward.

Further, when the brake pedal BP is operated and it is determined that the negative pressure booster 40 is immediately before the assist limit based on the output signal of the pressure sensor DT1, the electric motor M is started and the hydraulic pump HP is driven. Specifically, for example, when the pressure Pv in the variable pressure chamber VP detected by the pressure sensor DT1 becomes larger than a predetermined pressure Kp, the electric motor M is started, so that the negative pressure booster 40
Starts to operate just before reaching the assisting limit, and the hydraulic pump H
The output hydraulic pressure of P is supplied to the power chamber RP via the input port 1p.

Then, when the negative pressure booster 40 reaches the assisting limit, assisting by the hydraulic pressure booster section 20 is added. That is, when the valve member 31v is driven according to the operation of the brake pedal BP and seats on the valve seat member 21, the communication between the power chamber RP and the liquid chamber R3 is cut off. As a result, in the hydraulic booster section 20, the output hydraulic pressure of the hydraulic pump HP, that is, the power hydraulic pressure is applied to the rear end face of the large diameter portion 12e,
Is pushed forward. At this time, the power hydraulic pressure of the sectional integral of the valve member 31v is changed to the hydraulic pressure booster section 20.
Is transmitted to the rear input rod 3 as a reaction force.

Thus, also in this embodiment, the operation frequency of the electric motor M and the hydraulic pump HP can be minimized, and the hydraulic pump HP is started before the negative pressure booster 40 reaches the assisting limit. Therefore, assistance by the hydraulic booster unit 20 can be smoothly added with good responsiveness. In addition, by monitoring the detection output of the pressure sensor DT1, it is possible to detect an absolute pressure shortage of the negative pressure source connected to the negative pressure booster 40. Since power can be secured, it is also effective in securing so-called partial braking force. In particular, in the present embodiment, since the valve seat member 21 is configured to be accommodated in the concave portion 12c of the second piston 12, the valve means of the present invention can be easily configured.

FIG. 8 shows the structure of the relief valve RL used in the embodiment shown in FIGS. 1 and 5, in which a valve seat 201 provided on the input side thereof and a spring 203 in a direction for closing the valve seat 201 are provided. The hydraulic pump HP has an energized valve body 202, the input side of which is connected to the pressure-increasing hydraulic path AI on the output side of the hydraulic pump HP, and the output side of which is connected to the pressure-reducing hydraulic path AO.
In FIG. 8, white arrows indicate the flow of the brake fluid. Thus,
Normally, the valve body 202 is seated on the valve seat 201 by the urging force of the spring 203, and when the discharge brake fluid pressure of the hydraulic pump HP exceeds a predetermined relief pressure, the valve body 202 is moved to the valve seat 2.
01, and the discharge brake fluid of the hydraulic pump HP is released from the reservoir RV, 4 via the solenoid valve device PV in the open position.
Is returned to. In this way, the upper limit of the power hydraulic pressure in the power chamber RP when assisted by the hydraulic pump HP is set.

FIG. 9 shows the structure of the solenoid valve device PV used in the embodiment shown in FIGS. 1 and 5, in which a valve seat 204 provided on the input side thereof and a plunger 207 are provided.
And a valve body 205 which is normally urged by a spring 206 in a direction in which it is opened,
Its input side is connected to the discharge port 1r (FIG. 5), and its output side is connected to the reservoir RV, 4. In FIG. 9, white arrows indicate the flow of the brake fluid. Thus, the solenoid valve device PV is provided with the solenoid coil 2 as the urging means of the present invention.
08 is energized, the plunger 207 is driven, and the valve body 205 provided at the tip of the plunger 207 is seated or unseated on the valve seat 204, and the valve body 205 is moved in proportion to the drive current to the solenoid coil 208. It is controlled so that the pressure difference before and after changes. The relief valve RL and the solenoid valve device PV may be formed integrally with a housing or the like.

FIG. 10 is an enlarged view of the valve element 205 of the solenoid valve device PV shown in FIG.
The valve body 205 is disposed so as to be seated on the valve seat 204 from the side communicating with the discharge port 1r, that is, the side opposite to the side communicating with the power chamber RP (upper side in FIG. 10). It is biased in the seating direction.
Then, by energizing the solenoid coil (208 in FIG. 9), the valve body 205 is driven in a direction to be seated on the valve seat 204, and the spring 206 is compressed, and the valve body 205 is compressed.
Is seated on the valve seat 204.

As described above, the pressure applied to the valve body 205 by the hydraulic pressure of the power chamber RP is applied to the solenoid valve device PV in which the valve body 205 is seated on the valve seat 204 and is in the closed position when the solenoid coil is energized ( When the urging force is larger than the urging force in the seating direction (at the time of excitation), the valve body 205 is driven in a direction away from the valve seat 204. By setting the urging force in the direction in which the valve element 205 is seated on the valve seat 204 during excitation to an appropriate value larger than the relief pressure of the relief valve RL, FIG.
As shown by a dashed line (AB) in FIG.
Can be set to an upper limit pressure larger than the relief pressure by Thus, for example, during braking steering control, a large braking force can be applied irrespective of brake pedal operation. When the pressure exceeds the upper limit pressure larger than the relief pressure, the valve body 205 is separated from the valve seat 204, so that the hydraulic pump HP can be prevented from being overpressurized.

[0070]

The present invention has the following effects because it is configured as described above. That is, according to the first aspect of the present invention, there is provided a valve means for controlling the assistance of the master cylinder piston by the hydraulic pressure assisting means, and the pressure chamber is connected to the pressure-reducing hydraulic passage which connects the power chamber to the reservoir via the valve means. , A solenoid valve device that restricts the flow rate of the pressure-reducing hydraulic passage in accordance with the operation state of the brake pedal and / or the vehicle state;
And between the output side of the pump means in the pressure-increasing hydraulic pressure path and the input side of the solenoid valve device in the pressure-reducing hydraulic pressure path, which is normally closed and the output hydraulic pressure of the pump means exceeds a predetermined relief pressure. The relief valve communicating with the reservoir is interposed, so that the communication between the power chamber and the reservoir is cut off regardless of the state of the valve means by shutting off the pressure-reducing hydraulic passage by the solenoid valve device. Can be. Therefore, even when the assisting of the master cylinder piston by the hydraulic pressure assisting means is prohibited by the valve means, if the pump means is driven and the pressure reducing side hydraulic passage is shut off by the solenoid valve device, the pressure in the power chamber increases. As a result, the master cylinder piston can be reliably assisted.

Further, when the output hydraulic pressure of the pump means exceeds a predetermined relief pressure, the relief valve communicates.
The output hydraulic pressure is easily and reliably limited. Thus, even if the pump means is over-rotated, the power chamber can always be maintained at a constant pressure, and a stable assisting operation can be performed.

By constructing the solenoid valve device as described in claim 2, the power chamber is further pressurized by the pump means in a state where the solenoid valve device is in the closed position, so that the power hydraulic pressure becomes higher than the relief pressure. Become. By driving the pump means and the solenoid valve device in accordance with the operation state of the brake pedal and / or the vehicle state, various types of traction control, brake steering control, brake assist control, automatic brake control, etc. are performed. Can be reliably performed. Then, in a state where the pressure-reducing hydraulic passage is shut off by the solenoid valve device, when the pressure exceeds a predetermined pressure larger than the relief pressure, the valve body is separated from the valve seat, and the predetermined pressure is set as the upper limit pressure. Therefore, it is possible to reliably prevent excessive pressurization without separately controlling the pump means.

Further, by interposing a one-way valve between the output side of the pump means and the input side of the relief valve, the brake can be easily operated even when the pump means stops. The outflow of liquid can be prevented, and various types of braking control can be reliably performed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a hydraulic brake device according to an embodiment of the present invention.

FIG. 2 is a graph showing input / output characteristics according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a state in which assistance by a negative pressure booster is performed in one embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a state in which assistance is performed by a negative pressure booster and a hydraulic pressure booster in one embodiment of the present invention.

FIG. 5 is a sectional view of a hydraulic brake device according to another embodiment of the present invention.

FIG. 6 is an enlarged sectional view of a master cylinder part of the hydraulic brake device of FIG. 5 according to another embodiment of the present invention.

FIG. 7 is an enlarged sectional view of a hydraulic booster section and a negative pressure booster of the hydraulic brake device of FIG. 5 according to another embodiment of the present invention.

FIG. 8 is an enlarged sectional view of a relief valve provided to the hydraulic brake device shown in FIGS. 1 and 5;

FIG. 9 is an enlarged sectional view of a solenoid valve device provided for the hydraulic brake device of FIGS. 1 and 5;

FIG. 10 is an enlarged sectional view of a valve body of the solenoid valve device of FIG. 9;

FIG. 11 is a flowchart showing a braking control operation by the hydraulic brake device according to one embodiment of the present invention.

[Explanation of symbols]

BP brake pedal, MC master cylinder, V
B negative pressure booster, HB hydraulic booster, AM driving means, CP constant pressure chamber, VP variable pressure chamber, VM valve means, TM1 first transmission member, TM2 second transmission member, HP hydraulic pump, M electric motor, RV Reservoir, DT1 pressure sensor, DT2 stroke sensor, AI pressure-increasing hydraulic pressure path, AO pressure-reducing hydraulic pressure path,
CH one-way valve, PV solenoid valve device, RL
Relief valve

Continued on the front page (72) Inventor Riji Nishii 2-1-1 Asahi-cho, Kariya-shi, Aichi F-term (reference) in Aisin Seiki Co., Ltd. 3D048 BB21 BB38 CC11 CC26 CC39 EE28 GG05 GG11 GG17 GG29 HH15 HH18 HH26 HH32 HH37 HH55 HH66 HH75 HH77 QQ08 RR00 RR01 RR06 RR11 RR25 RR35

Claims (3)

[Claims] 1. A master cylinder for driving a master cylinder piston forward in response to operation of a brake pedal to increase brake fluid in a reservoir to output brake fluid pressure, and a negative pressure in response to operation of the brake pedal. Negative pressure assisting means for assisting the master cylinder piston, pump means for increasing the brake fluid in the reservoir and outputting the brake fluid pressure independently of the master cylinder, and forming a power chamber behind the master cylinder piston A hydraulic pressure assisting means for supplying the output hydraulic pressure of the pump means to the power chamber in response to the operation of the brake pedal to assist the master cylinder piston; and assisting the master cylinder piston by the hydraulic pressure assisting means. Valve means for controlling the pressure chamber, a pressure-increasing-side hydraulic passage for connecting the power chamber to an output side of the pump means, A pressure-reducing hydraulic passage connecting the power chamber to the reservoir via valve means; and a pressure-reducing fluid connected to the pressure-reducing hydraulic passage in accordance with an operation state of the brake pedal and / or a vehicle state. A solenoid valve device for restricting the flow rate of the pressure path, and interposed between an output side of the pump means in the pressure-increasing-side hydraulic pressure path and an input side of the solenoid valve device in the pressure-reducing-side hydraulic pressure path; And a relief valve which is closed and communicates when the output hydraulic pressure of said pump means exceeds a predetermined relief pressure. A valve seat formed on an input side of the solenoid valve device in the pressure reducing hydraulic pressure passage communicating with the power chamber side and communicating with an output side of the relief valve; A valve seat that is seated from a side opposite to an input side of the solenoid valve device toward an input side with respect to a valve seat, and the valve body is held away from the valve seat when not energized; Biasing means for biasing a body in a direction to be seated on the valve seat, wherein when the hydraulic pressure on the power chamber side exceeds a predetermined pressure larger than the predetermined relief pressure, the valve body during excitation is provided. 2. The hydraulic brake device for a vehicle according to claim 1, wherein the valve body is separated from the valve seat against a biasing force in a direction in which the valve seat is seated on the valve seat. 3. A one-way valve interposed between the output side of the pump means and the input side of the relief valve, the one-way valve permitting flow to the power chamber and prohibiting reverse flow. 3. The hydraulic brake device for a vehicle according to claim 1, wherein