JPH10297459A - Brake hydraulic control device with automatic brake function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply an automatic brake by providing a selector valve device for applying the pressure of a pressure source to a pilot piston. SOLUTION: A pilot piston 20 is slidably arranged in the first cylinder 24, and the first liquid chamber 25, the second liquid chamber 26, and the third liquid chamber 27 are partitioned. The second liquid chamber 26 is communicated with the third selector valve 16 and the second selector valve 15. When such a case occurs that a brake is automatically applied in this brake hydraulic control device, an electronic control device opens the normally closed second selector valve 15 and closes the normally opened third selector valve 16. The pressure fluid in an accumulator is introduced into the second liquid chamber 26 via the second selector valve 15, and the pilot piston 20 is moved to the left. A diaphragm piston 21 is also moved by this shift, a spool piston 22 is moved to the left, the accumulator is communicated with a boost chamber 142, and a hydraulic transmission device is operated to apply a brake.

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 having an automatic braking function such as traction control and yaw moment control in addition to antilock control.

[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. Yes (JP-B 61-53265)
issue).

[0003] The hydraulic brake system described in the above publication will be briefly described with reference to FIG. 5. In this system, when a driver operates a brake pedal 301, a hydraulic pressure is generated in a master cylinder 302. Reaches the modulator cylinder 303 through the branch pipes 304a and 306a, and the pistons 307 and 308
And displaces the pistons 307, 308 to the left, and by the conical end 310 of the shutoff valve 309,
The hole 311 of the piston 308 is closed and the flow path 312 is closed.
Is closed, and a servo hydraulic pressure is generated in the chamber 313.

The hydraulic pressure generated in the chamber 313 causes the shut-off valve 309 to be displaced against the force of the return spring 314, so that the pressurized hydraulic oil flows into the distribution chamber 315, from which the pipe 316 is passed. Through the respective chambers 317 of both servo cylinders. The pressure generated in the chamber 317 displaces the servo piston 318, and accordingly the stem 31
9 is displaced to the right in the figure, so that the end flange 330 of each stem engages with each auxiliary piston 321 and closes the hole 322 of each auxiliary piston 321. In this way, the hydraulic oil in the chamber 323 is pressurized by the thrust of the servo piston 318, transmitted from the master cylinder 302, and
3 is further increased proportionally, the auxiliary piston 321 receives the servo force and the brake is operated, and the depression force of the brake pedal 301 can be reduced.

[0005]

However, the brake fluid pressure control device described in the above publication does not have an automatic braking function, and seals the partition walls of the pistons 307 and 308 on which fluid pressure from the master cylinder acts. However, it is difficult to realize an automatic braking operation using these pistons 307 and 308 effectively. Further, adding an automatic braking function to a conventional brake fluid pressure control device requires a complicated structure. There were problems such as becoming.

In view of the above, the present invention provides an automatic piston hydraulic control system in which the piston in the brake hydraulic pressure control device is formed as a stepped piston, and the hydraulic pressure from a pressure source (accumulator) can be directly applied to this step. An object of the present invention is to provide a brake fluid pressure control device having a brake function and an automatic brake function capable of realizing a multifunctional brake operation with one brake system, and to solve the above problems.

According to the present invention, at the time of automatic braking, the fluid pressure from the fluid pressure source is directly supplied to the fluid chamber defined by the stepped balance valve in the control valve via the switching valve, and the flow path in the control valve is controlled. And the hydraulic pressure from the accumulator is transmitted to the hydraulic pressure transmission device via the boost chamber to perform the braking action. For this reason, this brake fluid pressure control device only switches the solenoid valve according to a command from the electronic control device, and automatically brakes (traction control,
Yaw moment control, etc.).

[0008]

For this reason, the technical solution adopted by the present invention is to control the pressure of the pressure source by applying the pressure generated in the master cylinder 2 to the pilot piston to apply the control pressure to the wheel cylinder. In a brake fluid pressure control device provided with a control valve that applies
A brake fluid pressure control device having an automatic braking function, comprising a switching valve device for applying a pressure of a pressure source to the pilot piston.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of the brake fluid pressure control device, FIG. 2 is an enlarged sectional view of a control valve, and FIG.
FIG. 4 is an enlarged sectional view of a hydraulic pressure transmitting device, and FIG. 4 is an enlarged sectional view of a pump used in the present control device. Hereinafter, after describing the overall configuration of the brake fluid pressure control device, the components such as the control valve, the fluid pressure transmission device, and the pump will be described in detail.

In FIG. 1, 1 is a brake pedal, 2 is a tandem master cylinder, 3 is a control valve,
4 is a front wheel side hydraulic pressure transmitting device, 5 is a rear wheel side hydraulic pressure transmitting device, 6
Is a pump, 7 is a front wheel cylinder, 8 is a rear wheel cylinder, 9 is a hold valve, 10 is a decay valve, 11 is an anti-lock reservoir, 12 is a proportioning valve, 13 is an accumulator as a pressure source, and 14 is normally closed. A first switching valve of a type, 15 is a normally closed second switching valve (switching valve device), 16 is a normally opened third switching valve (switching valve device), 17 is a pressure sensor,
Reference numeral 18 denotes a relief valve, and reference numeral 19 denotes a reservoir, which are connected by a flow path as shown.

When the brake pedal 1 is operated and a hydraulic pressure (hydraulic pressure) is generated in the tandem master cylinder 2, the control valve 3 is actuated by this hydraulic pressure, and the hydraulic pressure of the master cylinder is reduced. On the other hand, the hydraulic pressure proportionally increased is transmitted from the output port 144 of the control valve 3 to the hydraulic pressure transmitting devices 4 and 5. The hydraulic pressure generated by the hydraulic pressure transmission devices 4 and 5 is supplied to the wheel cylinders 7 and 8 and a brake is applied. Further, if a possibility of locking of the wheel occurs during the braking operation, the hold valve 9 and the decay valve 10 are opened and closed by an output signal from an electronic control unit (not shown) according to a signal from a wheel speed sensor (not shown). The pressure fluid in the cylinders 7 and 8 is discharged to the anti-lock reservoir 11, and the pressure fluid in the wheel cylinders 7 and 8 is controlled by pumping the pressure fluid from the anti-lock reservoir 11 by the pump 6 that operates at the same time. Execute antilock control. When the pump 6 is operated, a booster pump (detailed configuration will be described later) incorporated in the pump is also operated, and the booster pump draws up a pressure fluid from the hydraulic pressure transmission devices 4 and 5 and accumulators 13.
To accumulate pressure.

That is, in this hydraulic pressure control apparatus, during kickback on the master cylinder side during antilock control, the wheel cylinder is depressurized while consuming the hydraulic pressure of the accumulator. Since the accumulator can accumulate pressure while pumping the fluid from the hydraulic pressure transmission device side, the pressure fluid in the wheel cylinder is once discharged to the reservoir at atmospheric pressure, and pumped again from the reservoir at atmospheric pressure, as in the past. As a result, the load on the pump can be reduced as compared with a configuration in which the pressure fluid is pumped up and accumulated in the accumulator. In addition, when the vehicle slips when the vehicle starts, or when the brake is automatically applied due to the approaching distance between the vehicles, automatic braking control such as yaw moment is performed to ensure the stability of the vehicle body when turning. In this case, the piston in the control valve can be actuated by the hydraulic pressure from the accumulator to exert an appropriate braking force on the wheels.

The details of the main components constituting the present hydraulic pressure control device will be described below. [Control Valve 3] In FIG. 2, the control valve 3 includes a pilot piston 20, a diaphragm piston 21, a spool piston 22, and a flow absorption piston 23 in a main body 3A in the arrangement shown in the drawing. It is slidably disposed in the formed first cylinder 24, second cylinder 34, and third cylinder 40. The diameter of each cylinder is 1st cylinder> 2nd as shown
Cylinder> third cylinder.

The pilot piston 20 is a first cylinder 2
4 and is formed as a stepped piston composed of a large-diameter portion 20a and a small-diameter portion 20b.
A first liquid chamber 25, a second liquid chamber 26, and a third liquid chamber 27 are defined in the cylinder 24. The first hydraulic chamber 25 of the control valve 3 is connected to the first hydraulic pressure generating chamber 2a of the tandem master cylinder 2 via the first input port 28, and the rear wheel side hydraulic pressure transmitting device 5 via the first output port 29. The second liquid chamber 26 in the valve 3 is connected to a third input port 32.
The third liquid chamber 27 communicates with the third switching valve 16 and the second switching valve 15 through the second input port 3.
0 and the second hydraulic pressure generating chamber 2b of the tandem master cylinder 2 and the second output port 31 to the front wheel side hydraulic pressure transmitting device 4. The pilot piston 20 is normally urged rightward in the figure by a spring 33 disposed in the third liquid chamber 27.

A diaphragm piston 21 arranged opposite to the pilot piston 20 is slidably provided in a second cylinder 34 formed in the main body, and is formed as a stepped piston having a large diameter portion 21a and a small diameter portion 21b. And
A diaphragm 35 is provided on the end surface of the large diameter portion, and is partitioned from the third liquid chamber 27 in a liquid-tight manner by the diaphragm 35. On the end face of the small diameter portion 21b of the diaphragm piston 21 is formed an engagement protrusion 36 which is in contact with the spool piston 22, and a groove 37 is formed around the small diameter portion of the diaphragm piston 21. The groove 37 and the small-diameter end surface side liquid chamber 39 defined in the second cylinder by the diaphragm piston 21 communicate with the reservoir 19 via a passage 38 in the cylinder body.

The engagement projection 36 of the diaphragm piston 21
The spool piston 22 which is in contact with the spool piston is slidably disposed in the third cylinder 40 in the main body, and a flow path 41 is formed in the center of the spool piston. Communicating. This groove 4
2 communicates with the reservoir 19 through a passage 38 in the main body when not in operation, and is connected to the accumulator 13 through a passage 44 in the main body when the spool piston 22 moves leftward from the state shown in the drawing (that is, when it is activated). Communicate. The width of the groove 42 is set slightly smaller than the distance L between the passage 38 and the passage 44 formed in the main body, so that the flow passage 41 at the center of the spool piston 22 is
When the spool piston moves from the state communicating with the main body and the flow path 41 switches to the state communicating with the passage 44 on the main body side, a slight time lag occurs. Also,
The second switching valve 15 communicates with a second liquid chamber 26 formed at the step of the pilot piston 20 as shown in FIG.

The flow path 41 at the center of the spool piston 22 communicates with the flow path 45 of the flow absorption piston 23 disposed in the third cylinder 40. The flow path 45 of the flow absorption piston 23 is It communicates with a boost chamber 142 formed at an intermediate portion in the three cylinders 40. Boost room 1
Reference numeral 42 is connected to the first switching valve 14 as shown, and is directly connected to the front-wheel-side hydraulic pressure transmitting device 4 and to the rear-wheel-side hydraulic pressure transmitting device 5, for example, a proportion known in Japanese Patent Publication No. 58-57333. It is connected via a ning valve 12. The flow rate absorption piston 23 is urged toward the spool piston 22 by a flow rate absorption spring 43, and both are in contact with each other in the boost chamber 142. The spool piston 22 is urged by this urging force at the right end face in the drawing. Positioning is performed by the main body 3A.
The periphery of the flow absorption spring 43 is a passage 14 in the main body.
6 communicates with the reservoir 19 and the front and rear wheel side hydraulic pressure transmitting devices 4 and 5.

Therefore, when the control valve 3 is not operated, the boost chamber 1 formed in the main body 3A is not operated.
Reference numeral 42 denotes a hole 46 of the flow absorption piston 23 → a flow path 45 of the flow absorption piston 23 → a central flow path 41 of the spool piston 22 → a groove 42 of the spool piston 22 → communicate with the reservoir 19 via a passage 38 on the main body side. And is isolated from the accumulator 13. When the brake is operated, the hydraulic pressure is generated in the tandem master cylinder 2 and the hydraulic pressure in the first hydraulic chamber 25 and the third hydraulic chamber 27 in the control valve 3 rises. The piston 20 does not move. In addition, the diaphragm piston 21 moves leftward in the drawing due to the liquid pressure in the third liquid chamber 27, and the spool piston 22 moves leftward in the drawing. As a result, the groove 42 of the spool piston 22 is
4, the pressurized fluid from the accumulator 13 flows into the boost chamber 142 via the flow path 41, and the pressurized fluid flows into a hydraulic transmission device described later. And
Boost chamber 14 acting on the left end of spool piston 22
When the spool piston 22 moves left and right so that the hydraulic pressure due to the hydraulic pressure in the hydraulic cylinder 2 and the hydraulic pressure due to the master cylinder hydraulic pressure acting on the right end of the diaphragm piston 21 are balanced, the hydraulic pressure in the boost chamber 142 becomes the master cylinder. It is increased (boosted) in proportion to the hydraulic pressure. The boost ratio is determined by the ratio of the area of the left end of the spool piston 22 to the area of the right end of the diaphragm piston 21.

Furthermore, when the vehicle slips when starting the vehicle, when the distance between the vehicles is abnormally close, or when it is necessary to operate the brake in order to secure the stability of the vehicle body when turning (during automatic braking). The electronic control unit opens the normally-closed second switching valve 15 and closes the normally-opened third switching valve 16 in response to a signal from a sensor (not shown) (a wheel speed sensor, an inter-vehicle distance sensor, or the like). The pressure fluid in the accumulator 13 １３ the passage 44 in the control valve 3 → the second switching valve 14 → is introduced into the second liquid chamber 26 in the control valve 3 and
Is moved to the left in the figure, whereby the diaphragm piston 21 also moves to move the spool piston 22 to the left in the figure, and the accumulator 13 and the boost chamber 142 are communicated with each other. The transmission can be activated to activate the brake.

The control valve is configured so that the hydraulic pressure from the master cylinder simultaneously acts on both end surfaces of the pilot piston.
Even if one of the third hydraulic chambers 27 is eliminated, the same automatic braking action can be realized. Further, in the control valve, when the brake is operated, the spool piston 22 is moved by the pressing force from the diaphragm piston 21 and immediately after the hydraulic fluid from the accumulator 13 flows into the boost chamber 142, the flow absorbing piston 23 is moved by the flow absorbing spring 43. The spool chamber 22 is deflected to move to the left in the drawing, thereby absorbing the liquid amount. At the time of the initial operation of the spool piston 22, the boost chamber 142 is maintained at an extremely low pressure. A quick boost action can be started.

[Hydraulic pressure transmitting devices 4 and 5]
Since the front wheel side 5 and the rear wheel side 5 have the same structure and function, the rear wheel side hydraulic pressure transmitting device 5 will be described here with reference to FIG. In FIG. 3, the hydraulic pressure transmitting device
A piston 51, a second piston 52, and a third piston 53 are slidably provided in the main body 50 in the arrangement shown in FIG.
The pressure receiving area of the piston 51 is L, and the first area of the second piston 52 is
The pressure receiving area of the small diameter portion on the side of the piston 51 is J ′, the pressure receiving area of the large diameter portion of the second piston 52 is M, and the pressure receiving area of the second piston 52 is the third.
The pressure receiving area on the side of the piston 53 is formed as J, and among the pressure receiving areas, the pressure receiving areas J ′ and J of the second piston 52 and the respective pressure receiving areas M, L and J are set as J ′ = J M>L> J. .

At the lower central portion of the first piston 51 in the drawing,
The small diameter portion of the second piston 52 is slidably fitted,
The first piston 51 is urged downward by a first spring 54 disposed in the main body 50 so as to be in contact with a stopper 55 in the cylinder. First piston 51
A second spring 57 is interposed between the first piston 52 and the second piston 52 through a cylindrical spring seat 56.
Are urged downward in the figure by the urging force of the second spring 57. A gap S is formed between the first piston 51 and the second piston 52, and the gap S is formed by the cut valve 59 (described in detail later) when the brake is operated.
After the communication between the pressure chamber 61 and the pressure chamber 61 is interrupted, the gap S becomes zero.

The pressurizing chamber 61 defined by the first piston 51 is connected to the rear wheel-side wheel cylinder 8 via an output port 62 and a hold valve 9 formed in the main body, and via a cut valve 59. Body 50
Is connected to the flow path 60. The flow path 60 communicates with the first hydraulic pressure generation chamber 2 a of the tandem master cylinder 2 via the first output port 29 of the control valve 3 and an input liquid chamber 63 described later that is partitioned by a third piston 53. Is communicated to. The cut valve 59 is urged upward in the figure by a third spring 64 provided in the pressurizing chamber 61, and the lower shaft end of the cut valve 59 is connected to a cylindrical spring seat 56 provided on the second piston 52 side. It is slidably engaged, and communication between the flow path 60 and the pressurizing chamber 61 is maintained when not operating.

A liquid chamber 65 is defined in the main body 50 between the first piston 51 and the second piston 52, and the liquid chamber 65 is connected to the reservoir 19 via the control valve 3. The pressure introduction chamber 66 partitioned in the main body by the large diameter portion of the second piston 52 communicates with the boost chamber 142 of the control valve 3 via the proportioning valve 12. The pressure introduction chamber 66 of the front wheel side hydraulic pressure transmitting device 4 is directly connected to the control valve 3.
Is connected to the boost chamber 142. Third piston 53
Is slidably fitted to the center of the second piston,
In the illustrated state, the urging force of the second spring 57 urges the lower portion of the drawing through the second piston 52, and
The end face of the piston 53 abuts on a cylinder end face 58 formed on the main body 50, and defines an input liquid chamber 63 between the cylinder end face and the end face of the third piston 53. The input liquid chamber 63 communicates with the first hydraulic pressure generation chamber 2 a of the tandem master cylinder 2 and the flow path 60 via the first output port 29 of the control valve 3.

When the hydraulic pressure transmitting device 5 is not operated, the cut valve 59 maintains the illustrated state and the flow path 60 is open. When the brake pedal is actuated and the diaphragm piston 21 of the control valve 3 moves due to the fluid pressure in the third fluid chamber 27 by the tandem master cylinder and the flow path is switched, the pressure fluid in the accumulator 13 is released by the main body 3A of the control valve 3. Passage 44 → spool piston 22
Flows into the pressure introduction chamber 66 via the flow path 41 → the boost chamber 142 → the output port 144 → the proportioning valve 12 to move the second piston 52 upward in the figure between the gaps S. The movement during the gap S causes the cut valve 59 to close the channel 60 first, and then the second piston 52 comes into contact with the first piston 51, and the first piston 51 moves upward. On the other hand, the third piston 53 moves upward while maintaining the contact state with the second piston 52 by the hydraulic pressure of the first hydraulic pressure generation chamber 2 a of the tandem master cylinder that has flowed into the input liquid chamber 63. As a result, the first piston 51 is acted upon by the control valve 3 to increase the hydraulic pressure of the master cylinder and the hydraulic pressure of the master cylinder, and the pressurized fluid in the pressurizing chamber 61 is released via the hold valve 9. The brake is supplied to the wheel cylinder 8 on the wheel side to operate the brake. Also, the pressure fluid in the pressurized chamber on the front wheel side hydraulic pressure transmission device 4 side is similarly supplied to the front wheel side wheel cylinder 7 to operate the brake. Supplying a large amount of brake fluid to the wheel cylinder by increasing the boost ratio of the control valve 3 and increasing the pressure receiving area of the first piston 51 to the wheel cylinder. Can be.

Since the pressure-receiving areas J 'and J of the small-diameter portion provided across the large-diameter portion of the second piston 52 are equal, the cut valve 59 is provided at the initial stage of the brake operation.
Until the valve closes the flow path 60, there is no change in the flow rate of the brake pipe diameter, and the uncomfortable feeling when the brake pedal is depressed can be eliminated. In the early stage of the braking operation, the hydraulic pressure generated by the tandem master cylinder is also transmitted to the flow path 60 of the hydraulic pressure transmitting device 5 through the first output port 29 of the control valve 3. Since the cut valve 59 is closed as described above, the communication between the tandem master cylinder and the wheel cylinder is cut off.

In the present hydraulic pressure transmitting device, when the pressure fluid from the accumulator 13 is not supplied for some reason and the boosting function is not performed (during a failure), the second and third pistons 52 and 53 move. Therefore, the pressure fluid generated in the tandem master cylinder is not supplied to the first output port 29 of the control valve 3 → the main body passage 60 of the hydraulic pressure transmission device 5 →
It is directly transmitted to the open cut valve 59 → the pressurizing chamber 61 → the output port 62 → the wheel cylinder 8 to perform the braking action. Since the diameter of the hydraulic piston (not shown) of the tandem master cylinder 2 is set relatively small and the boost ratio is set large as described above,
During a failure, the hydraulic pressure generated by the hydraulic piston having a small diameter of the master cylinder can be increased, and a sufficient braking force can be ensured. Further, when the hydraulic pressure from the accumulator is introduced into the pressure introduction chamber 66 via the control valve during automatic braking (traction control or yaw moment control, etc.), the present hydraulic pressure transmitting device uses The two-piston 52 and the first piston 51 can move upward in the drawing to operate the brake. If the second and third pistons 52 and 53 are integrally formed, the volume of the input liquid chamber 63 increases when the automatic brake is activated, and the input liquid chamber 63 and the piping system connected to the input liquid chamber 63 are temporarily connected. The pressure may become negative and air may flow into the input liquid chamber 63 or the like. However, in the present control device, the second and third pistons 5
2, 53 are formed separately so as to be relatively movable with respect to each other. When the automatic brake is activated, the input liquid chamber 63
Since the hydraulic pressure from the tandem master cylinder 2 does not act on the inside, the third piston 53 does not move upward in the drawing, and no negative pressure is generated in the input liquid chamber 63 or the like as described above. .

[Pump 6] The pump 6 is characterized in that a booster pump 73 for pumping a pressure fluid from the hydraulic pressure transmitting device side during antilock control is added to the conventional antilock control pumps 71 and 72. . In FIG. 4, the pump 6 includes two anti-lock control pumps 71,
72 and one booster pump 73 for pumping a pressure fluid from the hydraulic pressure transmitting device. The plungers 71a and 72a of the anti-lock control pump are symmetrically arranged with respect to a common cam 74, and The plunger 73a of the booster pump is in axial contact with the plungers 71a and 72a (FIG. 4).
) Is in contact with a cam 74a separate from the cam 74 of the anti-lock control pump. When the cams 74, 74a are rotated by motors (not shown), the respective plungers 71a, 72a, 73a reciprocate by the cams, and open and close ball valves to perform a pumping operation. The discharge port 73 b of the booster pump 73 is connected to the accumulator 13, and the first suction port 73 c is connected to the reservoir 19.
The second suction port 73d is connected to the first switching valve 14, respectively. Since the pump structure itself is well known in the art, a detailed description thereof will be omitted.

In this pump, the pressure receiving area D of the plunger 73a of the booster pump 73 is equal to the respective plungers 71a, 72a of the antilock control pumps 71, 72.
The pressure receiving areas E and E ′ are set to have the following relationship. D ≧ E + E ′ This is because the booster pump 7
This is to ensure a sufficient pump capacity so that the pressure fluid does not flow out of the boost chamber 142 to the reservoir when the pressure fluid is pumped from the pressure introduction chamber 66 of each of the hydraulic pressure transmission devices 4 and 5 by 3. That is, the discharge amount of the anti-lock control pumps 71 and 72 is
If the suction amount is larger than 3, the pressure fluid in the boost chamber 142 will push back the spool piston 22 and flow out to the reservoir, so that such a state must be avoided.

[Wheel Cylinder, Decay Valve and Hold Valve] The control valve device including the decay valve 9 and the hold valve 10 has the same configuration as the conventional recirculation type anti-lock control device. This is performed by a command from an electronic control unit (not shown). The hold valve 9 and the decay valve 10 are opened and closed not only during the antilock control but also during the automatic braking such as the traction control and the yaw moment control by the command from the electronic control device as described in the operation section described later. And adjust the brake pressure.

The operation of the brake fluid pressure control device configured as described above will be described. [Non-operation] When the driver does not step on the brake pedal 1 and no hydraulic pressure is generated in the tandem master cylinder 2, the first and third fluid chambers 25, 2 in the control valve 3
Since no hydraulic pressure is generated in the control valve 7, the control valve 3 does not operate and the state of FIG. 2 is maintained. As a result, the pressure fluid from the accumulator 13 is shut off by the spool piston 22 in the control valve 3, and the input fluid chamber 63 and the pressure introduction chamber 66 of the fluid pressure transmission device are pressureless, so that the pressure fluid is supplied to the wheel cylinder. Does not generate hydraulic pressure.

[Operation] When the driver depresses the brake pedal 1 and hydraulic pressure is generated in the tandem master cylinder 2, the hydraulic pressure in the second hydraulic pressure generation chamber 2b is increased by the second input port 30 of the control valve 3 and the second hydraulic pressure generation chamber 2b. It acts on the diaphragm 35 in the control valve 3 via the three fluid chambers 27 and is transmitted to the input fluid chamber 63 of the front wheel side hydraulic pressure transmitting device 4 via the second output port 31. On the other hand, the fluid pressure in the first fluid pressure generation chamber 2 a of the tandem master cylinder 2 is transmitted to the first fluid chamber 25 of the control valve 3 and the input fluid chamber 63 of the fluid pressure transmission device 5. At this time, the hydraulic pressure in the first liquid chamber 25 and the third liquid chamber 27 increases, but the pilot piston 2
Pilot piston 20 does not move because the hydraulic pressures at both ends of zero are equal. When hydraulic pressure acts on the diaphragm piston 21 in the control valve 3, the piston 21
Moves to the left in FIG. 2, and the spool piston 22 also moves to the left in FIG. At this time, the spool piston 22
Enters the boost chamber 142 and the spool piston 22
The pressure in the boost chamber 142 is increased by the stroke of the control valve 3.
Is configured to be able to absorb the liquid amount corresponding to the stroke of the spool piston 22 by flexing the flow absorption spring 43 and moving to the left in the drawing. Since the pressure at 142 is maintained at an extremely low pressure, a rapid boosting operation can be started from a low hydraulic pressure state. Further, the third liquid chamber 27 and the reservoir 19 are partitioned by the diaphragm 35, and the sliding resistance of the diaphragm 35 can be reduced as compared with a case where a seal is arranged around the piston, and a hydraulic pressure is generated in the wheel cylinder. When the brake pedal depressing force is reduced.

By further movement of the spool piston 22, the central flow passage 41 in the spool piston 22 communicates with the passage 44 in the main body, the boost chamber 142 in the control valve 3 communicates with the accumulator 13, and the pressure fluid is When introduced into the pressure introduction chambers 66 of the pressure transmitting devices 4 and 5 (introduced into the hydraulic pressure transmitting device 5 via the proportioning valve 12), the second piston 5 in the hydraulic pressure transmitting device
2 moves between the gaps S upward in the figure. By the movement between the gaps S, the cut valve 59 first closes the flow path 60, and then the second piston 52 comes into contact with the first piston 51, and the first piston 51 moves upward to move inside the pressurizing chamber 61. The pressure in the pressurizing chamber 61 is increased,
Is supplied to the front and rear wheel cylinders 8 via
Apply the brake. Then, in this state, in the boost chamber 142, a hydraulic pressure proportional to the hydraulic pressure of the tandem master cylinder acting on the diaphragm piston 21 is generated.

On the other hand, the first and second control valves 3
The master cylinder pressure transmitted from the output ports 29, 31 to the hydraulic pressure transmitting devices 4, 5 acts on the input liquid chamber 63 of the hydraulic pressure transmitting devices 4, 5, and the third piston 53 causes the second piston 52 To rise with. The fluid in the liquid chamber 65 of the hydraulic pressure transmitting devices 4 and 5 is controlled by the control valve 3.
Is discharged to the reservoir 19 via the When the brake is released, the spool piston 22 in the control valve 3 returns to the initial position, and the pressure introduction chamber 6 of the hydraulic pressure transmission device is released.
The pressure fluid of No. 6 is boost chamber 142 → spool piston 2
2 passage 41 → reservoir 19 via passage 38 in the main body
Then, the pressure fluid in the pressurizing chamber 61 is also released, and the brake is released. As described above, when the wheel cylinder is pressurized, the third piston 53 moves upward by the hydraulic pressure of the master cylinder, and the volume of the input liquid chamber 63 increases, so that the liquid discharged from the master cylinder is absorbed. Therefore, as the depression force of the brake pedal is increased, the depression amount of the brake pedal is increased, and a suitable operation feeling can be obtained.

[At the time of anti-lock control] When there is a fear that the wheels may be locked during the brake operation, a signal from a wheel speed sensor (not shown) is used to issue a command from the electronic control unit to the hold valve 9 and the decay as conventionally known. Valve 10,
And the pump 6 is driven to avoid the locked state of the wheels, and the first switching valve 14 is opened to connect the suction port of the booster pump 73 to the boost chamber 14 of the control valve 3.
2 and the pressure introduction chamber 66 of the hydraulic pressure transmission device.

More specifically, when there is a risk of locking of the wheels, the hold valve 9 is closed and the wheel cylinder pressure is maintained with the decay valve valve 10 closed, and then the decay valve 10 is opened and the wheel cylinder 8 is opened. , 9 is absorbed by the reservoir 11 to reduce the wheel cylinder pressure. At the time of pressure reduction, the anti-lock control pumps 71 and 72 pump up the pressure fluid flowing from the wheel cylinder into the anti-lock control reservoir 11 and return it to the pressurizing chamber 61 of the hydraulic pressure transmission device. As a result, the first piston 51, the second piston 52, and the third piston 53 retreat, and the pressure introduction chamber 6
The pressure fluid of No. 6 is pumped up by the booster pump 73 and returned to the accumulator 13. When the volume of the input liquid chamber 63 is reduced by the retreat of the third piston 53, the driver can know that kickback has occurred in the master cylinder and the antilock control has been started. Further, during the antilock control, when it is necessary to pressurize, the decay valve closes, the halt valve opens, and the pressure introduction chamber 66 is opened.
And the hydraulic pressure of the input fluid chamber 63, the first piston 5
The first and second pistons 52 and the third piston 53 rise to pressurize the pressurizing chamber 61 to repressurize the wheel cylinder pressure.

In the booster pump 73 driven at the same time as the start of the antilock control, the pressure fluid in the pressure introduction chamber 66 of the hydraulic pressure transmission device is pumped through the first switching valve 14 which is kept open during the antilock control. Reflux to the accumulator 13. At this time, the hydraulic pressure in the pressure introducing chamber 66 is always proportional to the hydraulic pressure generated in the master cylinder. In other words, the hydraulic pressure in the pressure introducing chamber 66 acts on the diaphragm piston 21 in the control valve 3. Since a hydraulic pressure proportional to the hydraulic pressure of the master cylinder is generated, the booster pump 73 pumps up the fluid that has increased to a predetermined pressure, and can reduce the load as compared with the case where the fluid in the reservoir is pumped up. Thus, in the present control device, while kickback occurs on the master cylinder side during the antilock control, the wheel cylinder is pressurized while consuming the hydraulic pressure of the accumulator 13, while the booster pump 73 is operated by the hydraulic pressure transmission device. Since the pressure fluid is pumped up from the side to accumulate pressure in the accumulator 13, the load on the booster pump 73 can be reduced.

[Automatic Brake] When a slip occurs on the wheels when the vehicle starts moving, or when the brake is automatically applied due to the approach of the inter-vehicle distance, furthermore, in order to ensure the stability of the vehicle body during turning, a yaw moment or the like is used. When executing the automatic brake control, an appropriate braking force is applied to the wheels to execute control for avoiding such a situation. In the present brake fluid pressure control device, when any of these conditions occurs, the electronic control device opens the normally closed second switching valve 15 by a signal from a sensor (not shown) (wheel speed sensor, headway distance sensor, etc.). At the same time, the normally open third switching valve 16 is closed.

As a result, the pressure fluid in the accumulator 13 flows through the second switching valve 15 to the control valve 3.
Into the second liquid chamber 26 in the
To the left in the figure. Due to the movement of the pilot piston 20, the diaphragm piston 21 also moves while being pushed by the pilot piston 20, and the spool piston 22 moves to the left in the drawing, and the accumulator 13 and the boost chamber 1 move.
42, and the brake can be operated by operating the hydraulic pressure transmitting device in the same manner as in the above-described brake operation. By closing the second switching valve 15, the wheel cylinder pressure is kept constant, and by opening the third switching valve 16, the second liquid chamber 26 communicates with the reservoir 19, the pressure decreases, and the wheel cylinder pressure also decreases. I do. Further, in the present hydraulic pressure transmission device, the second piston 52 is separated from the third piston 53, and only the second piston 52 moves independently during the automatic braking operation. As described above, the third piston 53 does not move, and as a result, the inside of the input liquid chamber 63 does not become a negative pressure.

[Fail] When the pressure fluid from the accumulator 13 is not supplied for some reason and the hydraulic pressure transmitting device does not perform the hydraulic pressure transmitting function, the pressure fluid generated in the master cylinder is supplied to the control valve 3. The first and second output ports 29, 30 are transmitted directly to the cut valves 59 of the hydraulic pressure transmitting devices 4, 5 → the pressurizing chamber 61 → the output ports 62 → the wheel cylinders 7, 8 to perform a braking action. be able to. In the present hydraulic pressure transmitting device, as described above, the diameter of the hydraulic piston of the tandem master cylinder can be made relatively small, so that a sufficient braking force can be secured even when the accumulator 13 fails. Further, when the system of the first hydraulic pressure generation chamber 2a of the tandem master cylinder 2 fails, the hydraulic pressure of the second hydraulic pressure generation chamber 2b of the tandem master cylinder 2 flowing into the third hydraulic chamber 27 of the control valve 3 is increased and decreased. Hydraulic pressure is generated in the wheel cylinders 7 and 8 of the wheels as in the normal state. On the other hand, the tandem master cylinder 2
When the system of the second hydraulic pressure generation chamber 2b fails, the pilot piston 20 moves by the hydraulic pressure of the first hydraulic pressure generation chamber 2a and abuts on the diaphragm piston 20, and the diaphragm piston 20 moves to the left. By the movement, hydraulic pressure is generated in the front and rear wheel cylinders 7 and 8 as in the normal state.

[0041]

As described in detail above, according to the present invention, 1) the automatic braking function can be realized only by changing the shape of the piston in the control valve of the brake fluid pressure control device, and the size of the device can be reduced. This is advantageous for cost reduction and cost reduction. 2) If a slip occurs when the vehicle starts, or if the brakes are automatically activated due to the approach of the following distance,
Further, during automatic braking such as executing yaw moment control in order to secure the stability of the vehicle body during a turn, an appropriate braking force is applied to the wheels to reliably avoid such a situation. 3) Since the hydraulic pump and various valves can be controlled by the electronic control device based on information from various sensors, various braking modes can be realized only by changing the program in the electronic control device. 4) Re-pressurization, depressurization, holding, etc. of the brake fluid pressure at the time of antilock control, traction control, etc. can be realized with high accuracy, and the feeling of the brake can be improved. Since the third piston is configured separately, the third piston in the hydraulic pressure transmitting device does not move during the automatic braking operation, and no negative pressure is generated in the input liquid chamber or the like in the device. , Etc., can be obtained.

[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 control valve in the brake fluid pressure control device.

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

FIG. 4 is an enlarged sectional view of a pump in the brake fluid pressure control device.

FIG. 5 is an overall configuration diagram of a conventional brake fluid pressure control device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 brake pedal 2 tandem master cylinder 3 control valve 4 front wheel side hydraulic pressure transmitting device 5 rear wheel side hydraulic pressure transmitting device 6 pump 7,8 wheel cylinder 9 hold valve 10 decay valve 11 antilock reservoir 12 proportioning valve 13 pressure Source (accumulator) 14 First switching valve 15 Second switching valve 16 Third switching valve 17 Pressure sensor 18 Relief valve 20 Pilot piston 21 Diaphragm piston 22 Spool piston 23 Flow absorption piston 51 First piston (booster piston) 52 Second piston 53 Third piston 59 Cut valve 61 Pressurizing chamber 63 Input liquid chamber 66 Pressure introducing chamber 71, 72 Antilock control pump 73 Booster pump

Claims (3)

[Claims] A brake fluid pressure control device having a control valve for applying pressure generated by a master cylinder 2 to a pilot piston 20 to control the pressure of a pressure source and applying the control pressure to wheel cylinders 7 and 8. 3. The brake fluid pressure control device having an automatic brake function, comprising: switching valve devices 15 and 16 for applying the pressure of a pressure source to the pilot piston 20. 2. The pilot valve according to claim 1, wherein the pilot piston is formed in a stepped shape, and the switching valve device is provided in a passage connecting the liquid chamber formed in the stepped portion and a pressure source. 2. A brake fluid pressure control device having the automatic brake function according to 1. 3. The pressure of the first hydraulic pressure generation chamber 2a of the tandem master cylinder 2 is applied to one end of the pilot piston 20, and the pressure of the second hydraulic pressure generation chamber 2b of the tandem master cylinder 2 is applied to the other end. The brake fluid pressure control device having an automatic brake function according to claim 1, wherein: