JPH0569807A - Brake fluid pressure regulating device - Google Patents

Abstract

PURPOSE:To lower cost with an orifice eliminated as well as to restrain the stroke fluctuation of an master cylinder by providing a relief valve which restricts communication between a pump communication port and a master cylinder communication port at the time of moving a spool so as to set pressure free to the suction side of a pump, for a bypass path. CONSTITUTION:When anti-skid control is pressurized again and so on, brake fluid is to be discharged from the discharge side of a pump 10 to a flow valve 5 in a state that communication between a master cylinder 2 and the pump 10 is restricted. And when pressure between the pump 10 and the flow valve 5 becomes higher than specified one, a relief valve 32 provided for a bypass path is to relieve excess pressure to the suction side of the pump 10. The pump 10 therefore will never be subjected to loading pressure greater than a definite value, and it can also keep the rotation of a motor constant. Furthermore, there is no need for an orifice between the master cylinder communication port 6 and the pump communication port 12.

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 adjusting device for anti-skid control used in a brake device of a vehicle or the like.

[0002]

2. Description of the Related Art Among brake fluid pressure adjusting devices for anti-skid control adopted in a vehicle brake device for the purpose of preventing a tire from falling into a locked state during braking, as shown in FIG. Master cylinder 51
The master cylinder communication port 52 communicating with the wheel brake communication port 5 and the wheel brake communication port 5 communicating with the wheel brake 53.
4, a casing 59 having a reservoir 56 via a normally closed valve 55 and a reservoir communication port 58 communicating with the suction side of a pump 57 for sucking and discharging the brake fluid in the reservoir 56, and a casing 59 that is movable in the casing 59. Some of them employ a flow valve 61 having a spool 60 provided in the same (Japanese Patent Laid-Open No. 1-297350).

This flow valve 61 has its spool 6
0 makes the master cylinder communication port 52 and the wheel brake communication port 54 communicate with each other when the anti-skid control is not activated, and the master cylinder communication port 52 is connected to the master cylinder communication port 52 by the negative pressure by opening the normally closed valve 55 when the anti-skid control is depressurized. Wheel brake communication port 54
The communication with the wheel brake communication port 54 is cut off.
And the reservoir communication port 58 are communicated with each other, and the normally closed valve 55 is closed when the brake fluid returned by the pump 57 is re-pressurized.
Is supplied to.

Here, this brake fluid pressure adjusting device 50
In order to prevent the pulsation of the pump 57 and the stroke fluctuation (so-called kickback) of the master cylinder 51 from occurring when the brake fluid pressure of the anti-skid control is re-pressurized, the brake fluid discharged from the pump 57 is supplied to the master cylinder 51. A pump communication port 62 that communicates with the discharge side of the pump 57 is separately provided in the casing 59 in order to flow out toward the wheel brake 53 via the flow valve 61 at a constant flow rate independently of each other, and the pump communication port 62 and the master are connected by the spool 60. It is constructed so as to limit communication with the cylinder communication port 52, and moreover, the pump 5
In order to return the brake fluid from the 7 side to the master cylinder 51 side at a constant flow rate, a passage 63 is provided between the master cylinder communication port 52 and the pump communication port 62 separately from the flow valve 61, and communication is performed with an orifice 64 interposed. I am letting you.

[0005]

However, in the brake fluid pressure adjusting device 50 having the above structure, if the orifice 64 between the master cylinder communication port 52 and the pump communication port 62 is large, a large pump pulsation is transmitted to the master cylinder. Further, if the orifice 64 is too small, there is a problem in manufacturing such as an increase in processing cost and a problem that a rubber or the like mixed in the brake fluid is clogged. Further, the orifice 64 is a pump 57.
The flow rate of the brake fluid returned to the master cylinder 51 side slightly fluctuates due to the fluctuation of the discharge pressure of the master cylinder 51
Therefore, there is a need for further improvement in this respect.

Therefore, an object of the present invention is to eliminate the orifice between the master cylinder communication port and the pump communication port so that the master cylinder can be manufactured at a low cost and does not cause rubber clogging or the like. An object of the present invention is to provide a brake fluid pressure adjusting device that can suppress fluctuations.

[0007]

In order to achieve the above object, a brake fluid pressure adjusting device according to claim 1 of the present invention comprises:
A master cylinder communication port that communicates with the master cylinder, a wheel brake communication port that communicates with the wheel brake, and a reservoir communication port that communicates with the reservoir and a suction side of a pump that suctions and discharges the brake fluid in the reservoir via a normally closed valve. And a flow valve having a casing movably provided in the casing and urged in one direction by a spring, the spool of the flow valve being provided in the one direction by the spring. In the stationary state biased to, the master cylinder communication port and the wheel brake communication port are communicated with each other, and the master cylinder communication port is connected to the master cylinder communication port by a differential pressure generated on both sides of the spool by opening the normally closed valve. The communication with the wheel brake communication port is cut off and the wheel is The rake communication port and the reservoir communication port are communicated with each other, and the brake fluid returned by the pump is supplied to the wheel brake at a substantially constant flow rate with the normally closed valve closed, and the casing is a pump. A pump communication port communicating with the discharge side of the pump, limiting the communication between the pump communication port and the master cylinder communication port during movement of the spool, and providing a bypass path that bypasses the suction side and the discharge side of the pump, The bypass path is characterized by having a relief valve for releasing the pressure to the suction side of the pump when the pressure between the discharge side of the pump and the flow valve becomes high.

Further, in the brake fluid pressure adjusting device according to a second aspect of the present invention, in addition to the above, the set pressure of the relief valve is set to be a predetermined pressure higher than the pressure of the master cylinder. It is characterized by

[0009]

According to the brake fluid pressure adjusting apparatus of the first aspect of the present invention, the pump communication ports are individually communicated with the pump so that the discharge pressure of the pump is not directly applied to the master cylinder by the spool when the spool is moved. Restrict the communication between the pump communication port and the master cylinder communication port. In this way, while the communication between the master cylinder and the pump is restricted, the brake fluid is discharged from the pump toward the flow valve, but bypasses between the suction side and the discharge side of the pump. A bypass path is provided, and the relief valve provided in the bypass path releases the residual pressure to the suction side of the pump when the pressure between the discharge side of the pump and the flow valve becomes higher than a predetermined pressure. .. Therefore, the brake fluid is always discharged from the pump side at a substantially constant flow rate, and this brake fluid passes through the flow valve and becomes, for example, all brake fluid supplied to the wheel brakes at a constant flow rate. Brake fluid will not be returned to the cylinder side. Moreover, in this brake fluid pressure adjusting device, it is not necessary to communicate the master cylinder communication port and the pump communication port with each other via an orifice provided in a path different from the flow valve.

According to the brake fluid pressure adjusting device of the second aspect of the present invention, in addition to the above, the set pressure of the relief valve is set to be higher than the pressure of the master cylinder by a predetermined pressure. Further, the influence on the master cylinder side can be further reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A brake fluid pressure adjusting device according to a first embodiment of the present invention will be described below with reference to FIG.

In the figure, reference numeral 1 is a brake fluid pressure adjusting device for anti-skid control, reference numeral 2 is a master cylinder which is connected to a brake pedal 3 and generates a fluid pressure in response to an input of the brake pedal 3, and reference numeral 4 is a brake fluid. The wheel brakes that brake the wheels by pressure are shown respectively.

The brake fluid pressure adjusting device 1 is provided with a flow valve 5 which is a flow control valve. The flow valve 5 is connected to the master cylinder communication port 6 communicating with the master cylinder 2 and the wheel brake 4. A wheel brake communication port 7 that communicates with the reservoir 9, a reservoir communication port 11 that communicates with a reservoir 9 via a solenoid normally closed valve 8 and a suction side of a pump 10 that suctions and discharges the brake fluid in the reservoir 9, and a discharge side of the pump 10. A casing 13 having a pump communication port 12 communicating with the casing 13 is provided, and a spool 14 is movably provided in the casing 13. Here, the reservoir 9 has a piston 16 slidably accommodated in the cylinder 15 so that the capacity thereof is variable.
And a spring 17 for urging the same with a predetermined urging force, and the pump 10 has an intake valve 20 and a discharge valve 21.

In the spool 14, one end 22 has a large-diameter hole 23 that opens to the upper side in FIG. 1, and the other end 24 has a hole 25 that opens to the reservoir communication port 11 side (lower side in FIG. 1). And a small diameter hole 26 having a smaller diameter than these is communicated with each other. The hole 25 is provided with a spring 27 that biases the spool 14 toward the pump communication port 12 with a predetermined biasing force. Further, the spool 14 has a hole 28a for communicating the large diameter hole 23 with the master cylinder communication port 6, and a large diameter hole 23.
And a hole 28b for communicating the pump communication port 12 with each other, a hole 29 for communicating the large diameter hole 23 with the wheel brake communication port 7, and a hole 30 for communicating the hole portion 25 with the wheel brake communication port 7.

In the state shown in FIG. 1, the spool 14 is connected to the master cylinder 2 and the wheel brake 4 via the master cylinder communication port 6, the hole 28a, the large diameter hole 23, the hole 29 and the wheel brake communication port 7. And the wheel brake 4 is pressurized according to the normal operation, that is, the depression of the brake pedal 3 or the like.

Further, when the antiskid control is depressurized, that is, when the electromagnetic normally closed valve 8 is opened, the electromagnetic normally closed valve 8 is
The brake fluid in the hole 25 flows into the reservoir 9 by opening the valve, and the spool 14
1 is moved downward by the differential pressure on both sides of the wheel cylinder 4 to limit the communication between the master cylinder communication port 6 and the wheel brake communication port 7, that is, minute communication or block, and the wheel brake 4 and the reservoir 9 to the wheel brake. The communication fluid is communicated through the communication port 7 and the hole 30 so that the brake fluid in the wheel brake 4 flows into the reservoir 9 to reduce the brake fluid pressure of the wheel brake 4.
Then, at this time, the brake fluid sucked and discharged from the reservoir 9 by the pump 10 in the driven state is caused to flow from the pump communication port 12 to pass through the flow valve 5 and be circulated to the reservoir 9. In this state, the communication between the master cylinder communication port 6 and the pump communication port 12 is restricted by the spool 14. This prevents the discharge pressure of the pump 10 from being directly applied to the master cylinder 2.

Further, when the anti-skid control is re-pressurized, the electromagnetic normally closed valve 8 is closed, so that the outflow of the brake fluid to the reservoir 9 is stopped, and the pressure in the hole 25 causes the spool 14 to move up and down in FIG. The brake fluid that has been slightly moved in the direction and circulated by the pump 10 is supplied to the wheel brake 4 through the large diameter hole 23, the small diameter hole 26 and the hole 30, and the amount thereof is the holes 28a and 28b and the master cylinder communication port. The amount of communication with 6 and the pump communication port 12 provides a substantially constant flow rate.

In the first embodiment, the pump 1
Bypass path 31 bypassing the suction side and the discharge side of 0
The bypass passage 31 is provided with a relief valve 32 for releasing the residual pressure to the suction side of the pump 10 when the pressure between the pump 10 and the flow valve 5 becomes higher than a predetermined pressure. ..

Brake fluid pressure adjusting device 1 having such a structure
According to the above, when repressurizing the anti-skid control, etc., as described above, the master cylinder 2 and the pump 1 are
Although the brake fluid is discharged from the discharge side of the pump 10 toward the flow valve 5 in a state where the communication with 0 is restricted, the relief valve 32 provided in the bypass path 31 is provided.
However, when the pressure between the pump 10 and the flow valve 5 becomes higher than a predetermined pressure, the residual pressure is released to the suction side of the pump 10. Therefore, the brake fluid having a constant pressure is constantly discharged from the pump 10 side toward the pump communication port 12, and the brake fluid passes through the flow valve 5 and is supplied to the wheel brake 4 at a constant flow rate. The supplied brake fluid is less likely to be returned to the master cylinder 2 side. In addition, the relief valve 32 allows the pump 10
Since the load pressure above a certain value does not act on the pump 10, the rotation of the pump 10 and the motor (not shown) that drives the pump 10 can be maintained constant. Further, it becomes unnecessary to communicate the master cylinder communication port 6 and the pump communication port 12 with each other through an orifice provided on a path different from that of the flow valve 5.

The valve opening pressure of the relief valve 32 may be set to the maximum braking hydraulic pressure in the vehicle.

Next, a brake fluid pressure adjusting device according to a second embodiment of the present invention will be described. The second embodiment is the first
Since the relief valve is mainly different from the embodiment, this portion will be mainly described. Therefore, the part of which description is omitted has substantially the same configuration as that of the first embodiment.

Brake fluid pressure adjusting device 1 of the first embodiment
Has set the valve opening pressure of the relief valve 32 to a constant value, which is the maximum braking fluid pressure of the corresponding vehicle, but in the above structure, some brake fluid may return to the master cylinder side when the pressure on the master cylinder side is low. Therefore, the second embodiment further improves this point.

As shown in FIG. 2, the relief valve 32 of the second embodiment is connected with a branch path 34 branched from a path 33 between the master cylinder 2 and the flow valve 5. As shown in FIG. 3, the relief valve 32 includes a pump discharge side port 35 connected to the discharge side of the pump 10 and the pump 10.
Has a valve chamber 37 having a pump suction side port 36 connected to the suction side of the control chamber 38, and a control chamber 38 provided in parallel with and spaced from the valve chamber 37. Branch path communication port 39 communicating with 34
Is provided. Then, in the valve chamber 37, when the seating portion 40 at the boundary between the pump discharge side port 35 and the valve chamber 37 is seated, it is closed and the brake fluid pressure from the pump discharge side port 35 in FIG. A valve 41 is provided which moves to the left and opens to allow the brake fluid to flow to the pump suction side port 36. The valve 41 biases the valve 41 to the right in FIG. One end 42a of the spring 42 is housed on the side opposite to the pump discharge side port 35. In addition,
The chamber of the control chamber 38 in which the spring 45 is provided is in communication with the atmosphere.

A control piston 43 slidable in the left-right direction in FIG. 3 is housed in the control chamber 38.
The control piston 43 has an end surface 44 on the valve chamber side of the control chamber 38.
A spring 45 provided between and is urged to the left in FIG. The shaft portion 46 of the control piston 43 penetrates a through hole 47 provided between the valve chamber 37 and the control chamber 38, and a tip end portion 48 thereof has
The other end 42b of the spring 42 in the valve chamber 37 is seated.

In the relief valve 32 having such a structure, when the brake fluid pressure generated between the master cylinder 2 and the flow valve 5 and transmitted from the branch passage 34 (hereinafter referred to as master cylinder side fluid pressure) increases, The control piston 43 moves a predetermined amount in accordance with the magnitude of the brake fluid pressure against the biasing force of the spring 45, and the spring 42 is contracted to increase the valve opening pressure of the valve 41 by a predetermined amount.

In the second embodiment, the spring constants of both springs 42 and 45 are appropriately set so that the pump discharge pressure is always slightly higher than the master cylinder side hydraulic pressure.

By controlling the valve opening pressure of the relief valve 32 as described above, the pump discharge pressure becomes a pressure commensurate with the master cylinder side hydraulic pressure, so that the load applied to the pump 10 and the motor for driving the pump 10 is further increased. The pressure can be reduced, and the returning of the brake fluid to the master cylinder 2 side can be further reduced.

[0028]

As described in detail above, the first aspect of the present invention
According to the described brake fluid pressure adjusting device, since the brake fluid is constantly discharged from the pump side at a substantially constant flow rate, the brake fluid is not returned to the master cylinder side, and the stroke fluctuation of the master cylinder is eliminated. be able to. In addition, since it is not necessary to communicate the master cylinder communication port and the pump communication port with each other through an orifice of a different route from the flow valve, it is natural that the orifice such as rubber clogged in the brake fluid is blocked. It is possible to improve reliability without causing a trouble as a cause. Furthermore, since the load pressure above a certain level does not act on the pump, the fluctuations in the operating noise of the pump and the motor that drives it are eliminated, and these noises are less annoying. Since it becomes unnecessary to generate a large pressure in the pump unnecessarily, the driving force of the motor for driving the pump can be set to the necessary minimum, and the cost and weight of the motor can be reduced.

Further, according to the brake fluid pressure adjusting device of the second aspect of the present invention, the pump discharge pressure becomes a pressure commensurate with the master cylinder side fluid pressure by controlling the valve opening pressure of the relief valve. In addition to the above effects, the load pressure applied to the pump and the motor that drives the pump can be further reduced, and the return of the brake fluid to the master cylinder side can be further reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a brake fluid pressure adjusting device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a brake fluid pressure adjusting device according to a second embodiment of the present invention.

FIG. 3 is a sectional view schematically showing a relief valve of a brake fluid pressure adjusting device according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram schematically showing an example of a conventional brake fluid pressure adjusting device.

[Explanation of symbols]

 1 Brake Hydraulic Pressure Adjusting Device 2 Master Cylinder 4 Wheel Brake 5 Flow Valve 6 Master Cylinder Communication Port 7 Wheel Brake Communication Port 8 Electromagnetic Normally Closed Valve (Normally Closed Valve) 9 Reservoir 10 Pump 11 Reservoir Communication Port 12 Pump Communication Port 13 Casing 14 Spool 31 Bypass path 32 Relief valve

Claims (2)

[Claims] 1. A master cylinder communication port communicating with a master cylinder, a wheel brake communication port communicating with a wheel brake, a reservoir and a suction side of a pump for sucking and discharging a brake fluid in the reservoir via a normally closed valve. A flow valve having a casing having a reservoir communication port communicating with the casing and a spool movably provided in the casing and biased in one direction by a spring is provided, and the spool of the flow valve is In a stationary state in which the spring is biased in one direction, the master cylinder communication port and the wheel brake communication port are communicated with each other, and the differential pressure generated on both sides of the spool by opening the normally closed valve causes Blocks the communication between the master cylinder communication port and the wheel brake communication port And in the brake fluid pressure adjusting device for communicating the wheel brake communication port and the reservoir communication port, further supplying the brake fluid returned by the pump to the wheel brake at a substantially constant flow rate in the state where the normally closed valve is closed, The casing has a pump communication port communicating with the discharge side of the pump, restricts communication between the pump communication port and the master cylinder communication port during movement of the spool, and bypasses the suction side and the discharge side of the pump. A brake fluid pressure having a path provided with a relief valve for releasing the pressure to the suction side of the pump when the pressure between the discharge side of the pump and the flow valve becomes high in the bypass path. Adjustment device. 2. The brake fluid pressure adjusting device according to claim 1, wherein the set pressure of the relief valve is set to be higher than the pressure of the master cylinder by a predetermined pressure.