JP2000095089A - Brake fluid pressure control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake fluid pressure control device excellent in operating responsiveness and braking feeling with such constitution that boost pressure more intensified than the normal time is obtained in one of two brake systems when a failure is generated to the other brake system. SOLUTION: In a brake fluid pressure control device with a braking device actuated by the control fluid pressure of a control valve 3 provided to control the fluid pressure of a fluid pressure source in proportion to fluid pressure acting upon a control piston 70, a fluid pressure generating chamber 2b is formed between the control piston 70 and a master piston 2a, and the pressure receiving area B of the control piston 70 is made smaller than the pressure receiving area A of the master piston 2a facing the fluid pressure generating chamber 2b. In the case of fluid pressure not being generated in the fluid pressure generating chamber 2b, the master piston 2a presses the control piston 70 to make the control valve 3 output control fluid pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake fluid pressure control device for a vehicle, and more particularly to a brake fluid pressure control device for a vehicle, in which when one of two brake systems fails, the other brake system is controlled. The system provides a boost pressure that is higher than normal, resulting in excellent brake operation responsiveness and brake feeling, as well as excellent safety brake fluid pressure with a jump-up function during normal brake operation. The present invention relates to a control device.

[0002]

2. Description of the Related Art Conventionally, there has been known a brake fluid pressure control device which performs a boosting function by switching a flow path by a pressure generated in a master cylinder and transmitting a fluid pressure from a fluid pressure source to a fluid pressure transmitting device. (Japanese Patent Laid-Open No. 4-38259)
issue).

This device is configured so that a plurality of brake devices mounted on each wheel, a hydraulic pressure supply source, and a hydraulic pressure from the hydraulic pressure supply source can be controlled in accordance with an operation amount of a brake operation member. And a hydraulic pressure supply source hydraulic pressure control means connected to the brake device, wherein when the brake operation member is operated, the hydraulic pressure supply source hydraulic pressure control means is operated in accordance with the operation amount. Switches the internal flow path so that the hydraulic pressure from the hydraulic pressure supply source can be output according to the operation amount of the braking operation member, and between the left and right wheel brake devices of one set and the left and right of the other set. Between the wheel brake devices,
It is characterized in that a boosting function at the time of a brake operation can be achieved by connecting each through a separation valve capable of switching between communication and cutoff.

[0004]

However, in the brake fluid pressure control device described in the above publication, the fluid pressure from the fluid pressure supply source is controlled by the fluid pressure generated in the master cylinder in the early stage of the brake operation. It is not supplied to the brake device until the control means switches the flow path. That is,
When the brake pedal is depressed and there is a loss stroke of the brake pedal until the hydraulic pressure is generated in the master cylinder, the rise of the brake fluid pressure is delayed in the initial stage of the brake operation (no jump-up function is provided). There is a shortage of braking force in the early stage, and there is still room for improvement in terms of brake responsiveness and feeling. Further, there is a problem that X pipes must be used as brake pipes from the viewpoint of fail-safe in order to be able to cope with FF vehicles with a large front load distribution.

[0005] Therefore, the present invention, by setting the pressure receiving area A of the master piston in the master cylinder and the pressure receiving area B of the control piston so that A> B, when any failure occurs in the front wheel hydraulic pressure transmission system, By boosting the brake pedal, the boost pressure can be increased by A / B with respect to the axial force of the master cylinder with respect to the normal state, so that a sufficient braking force can be secured even in the event of a failure. Front and rear piping can be adopted even for front-wheel drive vehicles with large front load distribution.

The present invention further comprises a control valve capable of outputting a hydraulic pressure of a pressure source which is increased in proportion to a hydraulic pressure generated in the master cylinder, and further comprising a control valve which outputs the hydraulic pressure from the control valve. In a brake fluid pressure control device equipped with a hydraulic pressure transmission device for the left and right front wheels that can generate hydraulic pressure, when the master cylinder piston starts moving the spool piston in the control valve in the initial stage of brake operation, it is linked to the movement of this piston The hydraulic pressure from the pressure source is supplied to the wheel cylinder and the hydraulic pressure transmitting device in a short period of time at the initial stage of the brake operation (ie, a jump-up function is provided). In this way, the brakes are applied to resolve the shortage of braking force at the beginning of braking, An object of the present invention is to solve.

According to the present invention, when the piston in the master cylinder moves by operating the brake pedal, the spool piston in the control valve moves in conjunction with this movement, and the movement of the spool piston switches the flow path in the control valve. Then, the hydraulic pressure from the pressure source is directly supplied to the wheel cylinder and the hydraulic pressure transmitting device via the control valve to operate the brake. Therefore, when you operate the brake pedal,
Immediately thereafter, the hydraulic pressure from the pressure source is supplied to the wheel cylinder and the hydraulic pressure rises (jump-up function), so that the shortage of the braking force at the beginning of the braking operation can be resolved. In the subsequent brake operation, the spool piston is controlled by the hydraulic pressure generated in the master cylinder, the hydraulic pressure of the pressure source increased in proportion to the hydraulic pressure generated in the master cylinder is output from the control valve, and the normal braking is performed. Perform the operation.

[0008]

The technical solution adopted by the present invention comprises a control piston for receiving a hydraulic pressure generated in a master cylinder, and a hydraulic pressure source in proportion to the hydraulic pressure acting on the control piston. In a brake fluid pressure control device having a control valve for controlling pressure and having a brake device operated by a control fluid pressure of the control valve, a control valve is provided opposite to a master cylinder, and a control piston and a master piston of the master cylinder are provided. In the case where the pressure receiving area B of the control piston is made smaller than the pressure receiving area A of the master piston facing the hydraulic pressure generating chamber and the hydraulic pressure generating chamber is formed between Control by the master piston pressing the control piston Valve is a brake fluid pressure control device and outputs the control hydraulic pressure.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram of the brake fluid pressure control device, and FIG. 2 is a master cylinder used in the brake fluid pressure control device. FIG. 3 is an enlarged cross-sectional view of a control valve integrated with the hydraulic pressure transmission device. Less than,
After describing the overall configuration of the brake fluid pressure control device, the components of the control valve and the fluid pressure transmission device will be described in detail.

In FIG. 1, 1 is a brake pedal, 2 is a master cylinder, 3 is a control valve disposed adjacent to the master cylinder, 4 is a front wheel hydraulic pressure transmitting device, 6
Is a left and right front brake device, 8 is a left and right rear brake device, 9F and 9R are hold valves corresponding to each wheel, 1
0F, 10R are decay valves corresponding to each wheel, 11
Is an accumulator as a pressure source, 12 is a pressure sensor,
13 is a hydraulic pump, 14 is a relief valve, 15 is a normally open first switching valve, 16 is a normally closed second switching valve, 17
Is a flow path switching valve disposed in the piping system of the left and right front wheels;
Are reservoirs, which are connected by a flow path as shown in the figure.

The hold valves 9F, 9R, the decay valves 10F, 10R, the hydraulic pump 13, the normally open first switching valve 15, the normally closed second switching valve 16, and the piping system for the left and right front wheels are arranged. The flow path switching valve 17 is connected to an electronic control unit (ECU) shown in the figure, and based on information from sensors such as a speed sensor S and an inter-vehicle distance sensor, the electronic control unit according to a brake operation state (described later). (EC
The brake is controlled by opening / closing and driving in accordance with a command from U). The pressure of the accumulator 11 is constantly monitored by the pressure sensor 12, and the hydraulic pump 13 is driven by a command from an electronic control unit (ECU) so that the pressure of the accumulator 11 falls within a predetermined range. The second switching valve 16 is used for automatic braking or traction control. When the second switching valve 16 is operated (described later), the second switching valve 16 is opened and closed little by little by a signal from the electronic control unit, and the brake device or the front wheel hydraulic pressure is transmitted from the accumulator 11. It has a function of adjusting the hydraulic pressure supplied to the device 4.

The operation of the brake fluid pressure control device constructed as described above will be described briefly. In the initial stage of the operation of the brake pedal, the master in the master cylinder 2 which moves by depressing the brake pedal 1 will be described later. The spool piston 22 in the control valve 3 moves via the spring 35 in conjunction with the piston 2a, and the control valve 3
The fluid flow from the pressure source 11 is supplied to the rear brake device 8 (rear brake system) as it is from the input port 3c to the output port 3d of the control valve 3, and the rear brake is immediately activated. Thus, a jump-up function at the beginning of the brake operation can be obtained.
The hydraulic pressure from the output port 3d also acts on the second input chamber 63 of the front wheel hydraulic pressure transmitting device 4, so that the front brake device 6 also operates.

Thereafter, when the brake pedal 1 is further depressed, the first port 2f communicating the reservoir 18 with the hydraulic pressure generation chamber in the master cylinder is closed, and hydraulic pressure is generated in the hydraulic pressure generation chamber 2b. I do. The hydraulic pressure controls the spool piston of the control valve 3 (details will be described later), and the control valve 3 outputs a hydraulic pressure proportional to the hydraulic pressure of the master cylinder 2 from the output port 3d. This hydraulic pressure is directly transmitted to the left and right rear brake devices 8 and transmitted to the front wheel hydraulic pressure transmitting device 4 via a flow path described later.
Is supplied to the left and right front brake devices 6, 6 via the flow path switching valve 17 from the output port 4a.

If the wheels are likely to be locked during the braking operation, a signal from the wheel speed sensor S causes the electronic control unit (ECU) to switch the flow path switching valve 17, and the output port 4 a of the hydraulic pressure transmitting device 4. The left and right front brake device 6,
6, and the output port 3d of the control valve 3 is directly connected to the left and right front brake devices 6, 6. At this time, the control valve 3 and the hydraulic pressure transmitting device 4 are maintained in the state at the time of the brake operation. When the hold valve 9 is closed in this state, the brake pressure is maintained, and when the decay valve 10 is opened with the hold valve 9 closed, the pressure fluid in the brake devices 6, 8 is discharged from the decay valve 10 to the first discharge of the control valve 3. Port 3a → returns to the reservoir 18 through the control valve passage and reduces the brake pressure. When it is necessary to re-pressurize, when the decay valve 10 is closed and the hold valve 9 is opened, the hydraulic pressure of the accumulator 11 is changed from the input port 3c to the control valve 3 via the control valve 3 in both front and rear wheel systems.
It is supplied to the brake devices of the front and rear wheels via the internal flow path → output port 3d, and repressurized.

In this manner, the hydraulic pressure in the brake devices 6, 8 is maintained, reduced,
The antilock control is executed while repressurizing. The hydraulic pump 13 operates according to a signal from the pressure sensor 12 when the hydraulic pressure in the accumulator 11 decreases as well as during the antilock control, and can accumulate a predetermined pressure in the accumulator 13 as necessary. I have. In addition, when the pressure is reduced during the antilock control, the hydraulic pressure from the brake device is recirculated from the decay valve 10 to the reservoir 18 through the first discharge port 3a of the control valve. In such antilock control, a hydraulic pump for recirculating the brake fluid to the master cylinder 2 can be dispensed with, and the size and weight of the device can be reduced.

Further, when slippage occurs in the driving wheels when the vehicle starts, or when the brake is automatically applied by shortening the inter-vehicle distance, furthermore, in order to ensure the stability of the vehicle body during turning, yaw moment control or the like is used. When executing the automatic brake control, the first switching valve 15 is closed, the second switching valve 16 is opened by a command from the electronic control unit ECU based on a signal from the following distance sensor or the yaw moment sensor, and the hydraulic pressure is supplied from the accumulator 11. Is supplied directly to the rear wheel brake device 8 and also to the front wheel hydraulic pressure transmission device 4, and the hydraulic pressure generated in the output chamber 64 of the front wheel hydraulic pressure transmission device 4 is output through the output port 4 a → the flow path switching valve 17. To the left and right front wheels to apply appropriate braking force to the left and right front wheels. The adjustment of the hydraulic pressure at this time is performed by opening and closing the hold valve 9 and the decay valve 10 as in the case of the antilock control.

The details of the main components constituting the present hydraulic pressure control device will be described below. [Master Cylinder 2 and Control Valve 3] In FIG. 2, the master cylinder cylinder 2 includes a master piston 2a for partitioning a hydraulic pressure generation chamber 2b and a liquid chamber 2d in a main body. The master piston 2a is provided with a push rod 2c. It is connected to the brake pedal 1 via Seal members 2 are provided at both ends of the master piston 2a.
e, 2i are arranged, a first port 2f communicating the reservoir 18 and the hydraulic pressure generating chamber 2b is provided on the left side of the seal member 2e in the figure, and a liquid chamber is provided on the right side of the seal member 2e in the figure. 2d
A second port 2g is formed for communication between the second port and the reservoir 18. In the master cylinder 2, when the brake pedal 1 is operated and the push rod 2c moves leftward in the drawing, the master piston 2a moves leftward, and the seal member 2
e cuts off the communication between the reservoir 18 and the hydraulic pressure generating chamber 2b and generates hydraulic pressure in the hydraulic pressure generating chamber 2b. The basic structure of the master cylinder 2 is the same as that of the conventionally known master cylinder 2. It is.

The control valve 3 has a control piston 70 and a spool piston 22 in the arrangement shown in the figure. The control piston 70 includes the diaphragm piston 21 and the piston member 25, which are integrally connected by a nut 21b. The piston member 25 is slidable within the fixed support member 71. The diaphragm piston 21 is disposed inside the hydraulic pressure generating chamber 2b of the master cylinder 2 so as to face the master piston 2a, and the diaphragm 36 partitions the hydraulic pressure generating chamber 2b in a liquid-tight manner. A first spring 34 and a second spring 35 are disposed in the hydraulic pressure generation chamber 2b. The first spring 34 is provided between the master piston 2a and a spring seat 34a attached to the main body side. It is biased to the middle right. The second spring 35 is disposed between the master piston 2a and a spring seat 35a disposed on the diaphragm piston 21 side, and urges the diaphragm piston 21 leftward in the figure. The spring seat 35a attached to the diaphragm piston 21 is formed in a cylindrical shape, and a pressing rod 2h attached to the master piston 2a is arranged at the center thereof so as to be freely inserted.
The hydraulic pressure generation chamber 2b communicates with a first input chamber 62 in the front wheel hydraulic pressure transmission device 4 described later via the flow path 50.

The above-described diaphragm 36 has its inner peripheral portion sandwiched between the diaphragm piston 21 and the piston member 25, and the outer peripheral portion of the diaphragm 36 is fixed to the support member 71 and the support member 72 on the master cylinder 2 side. An engagement protrusion 38 is formed on the left end surface of the diaphragm piston 21 in the drawing to contact the spool piston 22. The liquid chamber 37 defined by the left end surface of the control piston 70 in the drawing is connected to the reservoir 3 via a port 3e. 18 as well as through the first discharge port 3a to the liquid chamber 65 and the decay valves 10 in the front wheel hydraulic pressure transmitting device. Diaphragm piston 21
Is biased toward the spool piston 22 by the biasing force of the second spring 35, and the engagement projection 38 of the diaphragm piston 21 is in contact with the spool piston 22.

The spool piston 22 is slidably disposed in the cylinder 26 of the fixed port member 27, and a flow path 42 is formed at the center of the spool piston 22.
2 communicates with a groove 41 formed on the outer periphery of the spool piston 22. On the other hand, the first passage 39,
A second passage 40 is formed, and the second passage 40 communicates with the accumulator 11 via the input port 3c. The port member 27 is fixed to the main body of the control valve 3 by appropriate means, and the pressure receiving areas B and C of the diaphragm piston 21 and the spool piston 22 are respectively set.
Is B> C.

The groove 41 of the spool piston 22 communicates with the reservoir 18 via the first passage 39 of the port member 27, the second discharge port 3b, and the first switching valve 15 when not operating. When the spool piston 22 moves to the left from the illustrated state (that is, at the time of operation), the groove 41 communicates with the accumulator 11 via the second passage 40 of the port member 27 and the input port 3c. The width L of the groove 41 is set slightly smaller than the distance between the first passage 39 and the second passage 40 formed in the port member 27. Therefore, the flow path 42 at the center of the spool piston 22 A slight time lag occurs when the spool 41 moves from the state communicating with the first passage 39 on the port member 27 side to switch the groove 41 into communication with the second passage 40 on the port member 27 side. It is like that. In addition, the spool piston 22
Is positioned by the urging force of the return spring 43 hitting the wall surface of the support member 71 at the right end face in the figure. The return spring 43 and the second spring 3
The load relationship with 5 is as follows: return spring 43> second spring 35.

The flow passage 42 at the center of the spool piston 22 communicates with a boost chamber 46 formed in the control valve 3. The boost chamber 46 is connected to the rear brake device 8 via the output port 3d, the flow path 45a and the hold valve 9R, and communicates with a second input chamber 63 of the front wheel hydraulic pressure transmission device 4 described later via the flow path 45b. are doing. Further, the flow path 45a is connected to the flow path switching valve 17, but in the illustrated state, the communication between the flow path 45a and the front brake device 6 is shut off. For this reason, in this control valve 3, the boost chamber 4
6 is a flow path 42 at the center of the spool piston 22 → a groove 41 of the spool piston → a first passage 39 of the port member 27 →
The second discharge port 3b communicates with the reservoir 18 via the normally open first switching valve 15, and further includes a boost chamber 46
Is the accumulator 11 by the normally closed second switching valve 16.
, The boost chamber 46 is in a non-pressure state. Therefore, when not operating, the rear brake device 8
No hydraulic pressure is generated in the front brake device 6, and no hydraulic pressure is generated in the first and second input chambers 62 and 63 of the front wheel hydraulic pressure transmitting device 4.

[Hydraulic pressure transmitting device 4] In FIG. 3, the front wheel hydraulic pressure transmitting device 4 includes a first piston 51, a second piston 52,
A third piston 53 is slidably provided in the main body in the arrangement shown in the figure, and a small-diameter portion 51a of the first piston 51 is slidably fitted to the right central portion of the second piston 52 in the drawing. ing. A first input chamber 62 is defined at the right end of the first piston 51, and a liquid chamber 58 is formed between the first piston 51 and the second piston 52. A spring 90 is disposed in the first input chamber 62 and urges the first piston 51 leftward in the drawing. A third piston 53 is fitted around the outer periphery of the second piston 52 as shown in FIG.
An output chamber 64 is defined on the left side of the drawing and the third piston 53 in the drawing, and a liquid chamber 65 is defined between the second piston 52 and the third piston 53. The liquid chamber 65 communicates with a liquid chamber 58 formed between the first piston 51 and the second piston 52 via a passage 57 formed in the second piston 52 and a passage 58a formed in the first piston. . Further, the second piston 52 and the third piston 53 are arranged to face each other with a gap S therebetween. Further, a second input chamber 63 is defined between the second piston 52 and the main body, and a second input chamber 63 is provided.
The input chamber 63 communicates with the boost chamber 46 of the control valve 3 via a flow path 45b as shown in the figure.

The first input chamber 62 of the front wheel hydraulic pressure transmitting device 4
It communicates with the hydraulic pressure generation chamber 2b of the master cylinder 2 via a passage 50, and when not in operation, communicates with an output chamber 64 in the front wheel hydraulic pressure transmission device via a passage 59a of a poppet valve 59 described later. . The poppet valve 59 is shown in FIG.
As shown in the enlarged view of the part D in the figure, the guide member 80 is slidably supported by the guide member 80, and the projection 59b is urged by the poppet spring 60 to abut on the first piston 51. Open the passage 59a as shown to open the first input chamber 62 and the output chamber 6
And 4. When the first piston 51 moves to the left in the drawing, the poppet valve 59 moves to the left in the drawing due to the urging force of the poppet spring 60, and the valve body 61 is seated on the valve seat 61a and the first input chamber 62 and The communication with the output chamber 64 is cut off. Reference numeral 82 denotes a screw member for fixing the guide member 80.

In the output chamber 64, a spring 55 is disposed between the third piston 53 and the sealing member 81, and a spring holder 54 is provided between the second piston 52 and the third piston 53. A spring 56 is disposed via the spring 56, and is configured to exert an urging force f against the urging force F of the spring 55. The urging force F of the spring 55
Urges the second piston 52 and the first piston 51 rightward in the figure via the third piston 53 and the spring holder 54. The third piston 53 is in contact with the stopper 66 provided at the right end of the sealing member 81 because the spring holder 54 is pressed rightward in the figure by the spring 55.

The load relationship between the poppet spring 60 of the poppet valve 59, the springs 90, 55 and 56 in the first input chamber 62 and the output chamber 64 is as follows: poppet spring 60 + spring 90 <spring 56 spring 56 <spring 55. The pressure receiving area of the first piston 51 is A
1, the annular pressure receiving area of the second piston 52 is defined as A2, and the pressure receiving area of the third piston 53 is defined as A3. The spring forces of the springs 55 and 56 are F and f, and the hydraulic pressure of the master cylinder 2 is Pm. , The second acting on the pressure receiving area A2
Assuming that the hydraulic pressure on the input chamber 63 side is Pr and the hydraulic pressure on the output chamber 64 acting on the pressure receiving area A3 (output hydraulic pressure) is Pf, the balance equation after the passage 59a of the poppet valve 59 is closed is f + Pm A1 + Pr · A2 = Pf · A3 + F From the equation, the pressure receiving area and the spring force are set so that Pr and Pf have an appropriate relationship. The output chamber 64 of the front wheel hydraulic pressure transmitting device 4 communicates with the flow path switching valve 17 via the output port 4a.

[Hydraulic Pump 13] FIG.
Eccentric cam 13a rotated by a motor as shown in FIG.
And two plungers 13b reciprocating in the left-right direction in the figure by the rotation of the eccentric cam 13a. The plunger 13b is rotated by the rotation of the eccentric cam 13a.
Reciprocates, the brake fluid in the reservoir 18 is sucked from the suction port 13c, and the brake fluid is discharged from the discharge port 13d. This structure is similar to that of a conventional hydraulic pump, and a motor for driving the hydraulic pump is operated by a command signal from an electronic control unit.

[Decay valve, hold valve] Hold valves 9F, 9R and decay valves 10F, 1
The control valve device composed of the OR valve has the same configuration as the conventional liquid circulation type anti-lock control device, and the hold valves 9F, 9R
The opening and closing of the decay valves 10F and 10R are performed by commands from an electronic control unit (ECU) shown in FIG.
This hold valve 9F, 9R, decay valve 10
F and 10R open and close not only during antilock control but also during automatic braking such as traction control and yaw moment control according to commands from the electronic control unit, as described in the operation section described later, and adjust the brake pressure. Execute In addition, the electronic control unit can take in information from other sensors and the like as needed in addition to the above-mentioned sensors, and can also control opening and closing of each valve.

The operation of the brake fluid pressure control device configured as described above will be described. When the brake pedal 1 is released and no hydraulic pressure is generated in the hydraulic pressure generating chamber 2b of the master cylinder 2, the diaphragm piston 21 of the control valve 3 is not operated.
Since the hydraulic pressure does not act on, the control valve 3 does not operate and the state of FIG. 2 is maintained. As a result, the pressure fluid from the accumulator 11 is cut off by the spool piston 22 in the control valve 3 and the first and second input chambers 62 and 63 of the front wheel hydraulic pressure transmitting device are pressureless, so that the brake is not applied. No hydraulic pressure is generated in the device.

[Operation] When the driver steps on the brake pedal 1, the piston in the master cylinder 2 moves leftward in the figure via the push rod 2c. In this initial movement, the first port 2f for communicating the reservoir 18 with the hydraulic pressure generating chamber 2b is still in a communication state, and no hydraulic pressure is generated in the hydraulic pressure generating chamber 2b. However, since the first spring 34 bends due to the movement of the master piston 2a and the second spring 35 directly moves the diaphragm piston 21 to the left in the drawing, this causes the spool piston 22 in the control valve 3 to move to the left in the drawing. And the central flow passage 42 in the spool piston 22 is moved from the groove 41 to the port member 2.
7, the second passage 40 communicates with the accumulator 11 via the input port 3c, and the pressure fluid in the accumulator 11 is supplied from the central passage 42, the boost chamber 46, and the output port 3d to the rear brake device 8 for braking. Work. Further, the accumulator pressure flowing into the boost chamber 46 by the above operation is introduced into the second input chamber 63 of the front wheel hydraulic pressure transmitting device via the flow path 45b, and the second piston in the front wheel hydraulic pressure transmitting device 4 is operated by this hydraulic pressure. 52 during the gap S.
During the movement during the gap S, the poppet valve 59
9a is closed, and the communication between the first input chamber 62 and the output chamber 64 is cut off. Then, when the second and third pistons 52 and 53 move integrally to the left, a hydraulic pressure is generated in the output chamber 64 and transmitted to the front brake device 6. In this way, the front and rear brake devices 6, 8 can be operated immediately after the brake pedal is depressed (so-called jump-up function), and the response of the brake is improved. In addition, since the diaphragm piston 21 moves while deforming the diaphragm 36, the sliding resistance of the diaphragm piston 21 can be reduced and the responsiveness is improved as compared with the conventional case where a seal is arranged around the piston.

Thereafter, when the brake pedal 1 is further depressed and the hydraulic pressure generating chamber 2b and the reservoir 18 are shut off by the seal member 2e of the master piston 2a, hydraulic pressure is generated in the hydraulic pressure generating chamber 2b in the master cylinder 2. This hydraulic pressure acts on the diaphragm piston 21 to control the spool piston to generate a hydraulic pressure proportional to the hydraulic pressure of the master cylinder 2 in the boost chamber 46 in the control valve 3.

Since the hydraulic pressure generated in the hydraulic pressure generating chamber 2b of the master cylinder 2 acts on the first input chamber 62 of the front wheel hydraulic pressure transmitting device 4, the first piston 51 in the front wheel hydraulic pressure transmitting device 4 also has the second piston. By moving to the left as viewed in FIG.
It is transmitted to. The spool piston 2 is adjusted so that the hydraulic pressure of the boost chamber 46 acting on the left end of the spool piston 22 and the hydraulic pressure of the master cylinder acting on the right end of the diaphragm piston 21 are balanced.
2 moves left and right, the hydraulic pressure in the boost chamber 46 is increased (boosted) in proportion to the master cylinder hydraulic pressure. The boost ratio is determined by the ratio B / C of the area C at the left end of the spool piston 22 and the pressure receiving area B at the right end of the diaphragm piston 21. Increase in this way (boost)
The brakes work on both the front and rear wheels by the applied hydraulic pressure.

When the brake is released, the spool piston 22 in the control valve 3
The brake fluid in the second input chamber 63 of the front wheel hydraulic pressure transmitting device is returned to the reservoir 18 via the boost chamber 46 of the spool piston 22 → the flow path 42 → the first passage 39 of the port member 27. Then, the first to third pistons 51 to 53 in the front wheel hydraulic pressure transmitting device 4 also return to the initial position, the brake fluid in the output chamber 64 is released, and the front wheel brake is released. The rear wheel brake is also released because the hydraulic pressure in the boost chamber 46 of the spool piston 22 is released to the reservoir 18. As described above, when the brake is operated, the first piston 51 in the front wheel hydraulic pressure transmitting device 4 moves to the left by the hydraulic pressure from the master cylinder 2 and the volume of the first input chamber 62 increases. Can be absorbed in the first input chamber 62, and the amount of depression of the brake pedal increases as the depression force of the brake pedal increases, so that a suitable operation feeling can be obtained.

[At the time of anti-lock control] If there is a possibility that the wheels may be locked during the brake operation, the signal of the wheel speed sensor S switches the flow path switching valve 17 according to a command from an electronic control unit (ECU). As a result, the output chamber 64 of the front wheel hydraulic pressure transmitting device 4 is provided with the hold valves 9 of the left and right front wheel piping system.
On the other hand, the hold valve 9F is connected to the boost chamber 46, and the control valve 3 and the front wheel hydraulic pressure transmitting device 4 are maintained at the time of the brake operation.

When the hold valves 9F and 9R are closed, the brake pressure is maintained, and then the decay valve 10
When F and 10R are opened, the pressure fluid in the brake devices 6 and 8 returns to the reservoir 18 to reduce the brake pressure. Also,
When it is necessary to repressurize, decay valve 10F,
When the 10R is closed and the hold valves 9F and 9R are opened, the hydraulic pressure from the boost chamber 46 in both the front and rear wheel systems becomes the output port 3d.
Is supplied to the brake devices 6 and 8 via the controller and repressurized. When the pressure is reduced during the antilock control, the fluid pressure from the brake device can be directly returned to the reservoir from the decay valves 10F and 10R. This eliminates the need for a hydraulic pump dedicated to anti-lock control for returning to the hydraulic pressure source.

[Automatic Brake] When slippage occurs in the rear wheels, which are driving wheels, when the vehicle starts moving, the electronic control unit (ECU) activates the normally open first switching valve 15 in response to a signal from the wheel speed sensor S. Close and open the normally closed type second switching valve 16. As a result, the hydraulic pressure in the accumulator 11 is reduced via the second switching valve 16 to the rear brake device 6.
To directly apply the brake force to eliminate the slip. At this time, the adjustment of the hydraulic pressure in the brake device is performed by the hold valve 9 and the decay valve 1 similarly to the antilock control.
0 is opened and closed. For example, when it is necessary to apply a braking action to the front and rear wheels because the inter-vehicle distance has been abnormally shortened, the second switching valve 16 is opened and the flow path switching valve 17 is switched to switch the accumulator 11 and the front and rear brake devices 6. , 8 can be realized. When one or more of the four wheels are operated to secure the stability of the vehicle when the vehicle is turning, the second switching valve 16 is opened and the flow path is switched in the same manner as described above. Switch the valve 17,
In addition, by closing the hold valves 9F and 9R belonging to the brake device that does not require the braking action during control, the hydraulic pressure of the accumulator is transmitted only to the brake device that requires the braking action. By the way, if the first and second pistons 51 and 52 are integrally formed, the first input chambers 6 of the front wheel hydraulic pressure transmission devices 4 and 5 at the time of automatic braking operation.
2, the pressure in the first input chamber 62 and the piping system connected to the first input chamber 62 may temporarily become negative pressure, and air may flow into the input chamber or the like. However, in the present control device, since the first and second pistons 51 and 52 are formed separately so as to be relatively movable with each other, the first piston 51 does not move and the first and second pistons 51 and 52 do not move as described above. No negative pressure is generated in the input chamber 62 or the like.

[Fail] In the present apparatus, when any failure occurs in the hydraulic pressure generating chamber 2b of the master cylinder 2 or the piping system connected thereto, the master piston 2a of the master cylinder 2 is depressed by depressing the brake pedal. The first and second springs 34 and 35 are bent to move to the left, and the load of the second spring 35 moves the diaphragm piston 21 to the left, whereby the spool piston 22 in the control valve 3 moves to the left in the figure. Move toward The movement of the spool piston 22 causes the central passage 42 in the spool piston 22 to move from the groove 41 to the port member 27.
The second passage 40 communicates with the accumulator 11 via the input port 3c to generate a hydraulic pressure in the boost chamber 46.
At this time, the hydraulic pressure in the boost chamber 46 is maintained in balance with the load of the second spring 35. The hydraulic pressure in the boost chamber 46 flows into the rear brake device 6 to operate the rear brake. Further, the master piston 2a in the master cylinder 2 moves to the left, the first port 2f communicating the reservoir 18 with the hydraulic pressure generating chamber 2b is closed, and the hydraulic pressure generating chamber 2b
The hydraulic pressure is generated in the master cylinder 2, but no hydraulic pressure is generated in the hydraulic pressure generating chamber 2b of the master cylinder 2.

The hydraulic pressure in the boost chamber 46 gradually rises while the second spring 35 is flexed, and when the pressing rod 2h integral with the master piston 2a strikes the diaphragm piston 21, the boost pressure of the master piston 2a increases. The hydraulic pressure inside is controlled. At this time, since the pressure receiving area A of the master piston 2a in the master cylinder 2 and the pressure receiving area B of the diaphragm piston 21 satisfy A> B, the boosting ratio increases by A / B with respect to the normal state,
Deactivate the front brake device 6 with the rear brake device 8
Can compensate. Therefore, a sufficient braking force can be secured even at the time of a failure. In this way, even if a failure occurs in one of the two brake systems, the other brake system can obtain a boost pressure that is higher than usual, so that the brake operation response Excellent in braking and brake feeling.

[0039]

As described above in detail, according to the present invention, 1) the pressure receiving area B of the control piston (diaphragm piston) 70 is made smaller than the pressure receiving area A of the master piston facing the hydraulic pressure generating chamber of the master cylinder. By doing so, even in the event of a failure, the boost pressure can be increased by A / B with respect to the axial force of the master cylinder 2 as compared with the normal case, and the responsiveness and brake feeling of the brake operation are improved. 2) Conventionally, FF vehicles and the like having a large front load distribution had to use X pipes on the fail-safe side. However, this structure can cope with front and rear pipes. 3) Boosters having the same structure can be used for both FF and FR vehicles, and parts can be shared. 4) In order to quickly increase the brake fluid pressure at the beginning of the brake operation (because of the jump-up function),
Brake responsiveness is improved. 5) The front wheel hydraulic system is not provided in the rear wheel piping system, and the hydraulic pressure from the accumulator in the brake hydraulic pressure control device can be supplied directly to the wheel cylinders. Can be. 6) Since the first and second pistons in the front wheel hydraulic pressure transmitting device are configured separately, the first piston in the front wheel hydraulic pressure transmitting device does not move during automatic braking operation, and the first piston and the second piston in the front wheel hydraulic pressure transmitting device do not move into the input chamber or the like. No negative pressure is generated. 7) When the pressure is reduced during the antilock control, the hydraulic pressure from the wheel cylinder can be directly returned to the reservoir from the decay valve, thereby eliminating the need for the conventional hydraulic pump for antilock control. Is simplified. Excellent effects can be achieved.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a brake fluid pressure control device according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a master cylinder 2 and a control valve 3 in the brake fluid pressure control device.

FIG. 3 is an enlarged sectional view of a front wheel hydraulic pressure transmission device in the brake hydraulic pressure control device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Brake pedal 2 Master cylinder 2a Master piston 2b Hydraulic pressure generation chamber 2e Seal member 2h Press rod 3 Control valve 4 Front wheel hydraulic pressure transmission device 6 Front brake device 8 Rear brake device 9 Hold valve 10 Decay valve 11 Accumulator 12 Pressure sensor 13 Hydraulic pump 14 Relief valve 15 First switching valve 16 Second switching valve 17 Flow path switching valve 18 Reservoir 21 Diaphragm piston 22 Spool piston 27 Port member 34 First spring 35 Second spring 35a, 34a Spring seat 36 Diaphragm 37, 58 , 65 Liquid chamber 38 Engagement projection 39 First passage 40 Second passage 41 Groove formed in spool piston 42 Flow passage formed in center of spool piston 43 Return spring 45 Flow passage 46 Boost chamber 51 First piston 52 Second piston 53 Third piston 54 Spring holder 55, 56 Spring 57 Passage 59 Poppet valve 60 Poppet spring 61 Valve body 62 Input chamber 63 Second input chamber 64 Output chamber 66 Stopper 70 Control piston 81 Sealing member

Claims (1)

[Claims] A control valve for receiving a hydraulic pressure generated by a master cylinder, and a control valve for controlling a hydraulic pressure of a hydraulic pressure source in proportion to a hydraulic pressure acting on the control piston; In the brake fluid pressure control device having the brake devices 6 and 8 operated by the control fluid pressure of 3, a control valve 3 is provided opposite to the master cylinder 2 and formed between the control piston 70 and the master piston 2a of the master cylinder. Hydraulic chamber 2
b, the master piston 2a facing the hydraulic pressure generation chamber 2b
The pressure receiving area B of the control piston 70 is made smaller with respect to the pressure receiving area A, and when the hydraulic pressure is not generated in the hydraulic pressure generation chamber 2b, the control valve 3 is controlled by the master piston 2a pressing the control piston 70. A brake fluid pressure control device for outputting fluid pressure.