JPH0143339Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a brake fluid pressure control device used in a vehicle equipped with a hydraulic vehicle height adjustment device, and in particular, the invention relates to a brake fluid pressure control device used in a vehicle equipped with a hydraulic vehicle height adjustment device. The present invention relates to a device that is disposed in a passage and controls brake fluid pressure that is transmitted to a rear wheel cylinder.

In vehicles equipped with brakes on the front and rear wheels, by maintaining an appropriate distribution ratio between the front and rear wheels, the front and rear wheels can be safely and efficiently prevented from locking up. A hydraulic control device is provided to stop the vehicle. and,
As this hydraulic pressure control device, one equipped with a valve piston is widely used. The valve piston is provided in the valve housing with one end exposed to the outside, and when pushed into the housing and in an inoperative position, allows the hydraulic pressure of the master cylinder to be directly transmitted to the rear wheel cylinder, At the operating position where the hydraulic pressure inside the valve housing pushes the valve out of the housing a certain distance, the hydraulic pressure transmitted to the rear wheel cylinder is prevented from increasing beyond a certain limit, or the hydraulic pressure in the master cylinder is kept constant. This function suppresses hydraulic pressure by reducing the pressure in proportion and transmitting it to the rear wheel cylinder. Various means are known for urging the valve piston to the non-operating position, but in vehicles equipped with a hydraulic vehicle height adjustment device, the valve piston is applied directly or to another member in response to vehicle height adjustment pressure. An actuator is provided with a piston such as a diaphragm type that acts indirectly through the
It is advantageous for this actuator to bias the valve piston into a non-actuated position.

The vehicle height adjustment pressure of the hydraulic vehicle height adjustment device increases or decreases in response to changes in the rear wheel load. Therefore, according to the hydraulic control device equipped with the actuator as described above, when the rear wheel load is large, It allows high brake fluid pressure to be transmitted to the rear wheel cylinder when the rear wheel load is low, and suppresses the fluid pressure transmitted to the rear wheel cylinder to a relatively low level when the rear wheel load is low. A type hydraulic pressure control valve can be obtained.

However, in such a hydraulic pressure control device, if vehicle height adjustment pressure is no longer supplied due to a malfunction of the vehicle height adjustment device, etc., the valve piston is biased to the non-operating position. There is a risk that the force will be insufficient and the hydraulic pressure transmitted to the rear wheel cylinder will be suppressed to an unexpectedly low level.

The present invention solves these problems and ensures that sufficient hydraulic pressure is transmitted to the rear wheel cylinders even if sufficient vehicle height adjustment pressure cannot be obtained due to a malfunction of the vehicle height adjustment device, etc. This was developed with the purpose of providing a load-sensing hydraulic pressure control device, and its gist is that a second actuator is provided in addition to the actuator described above. In other words, it is urged to the active position by the elastic force of the spring, but when vehicle height adjustment pressure is applied, it is kept in the non-active position against the elastic force of the spring, and the vehicle height adjustment pressure An actuator is provided which moves to the operating position when the valve is lowered or disappears, acts on the valve piston directly or indirectly through another member, and urges the valve piston to the non-operating position by the elastic force of the spring. be.

In this way, while normal vehicle height adjustment pressure is supplied, the first actuator applies a biasing force to the valve piston toward the non-operating position, and the braking increases or decreases in response to an increase or decrease in the rear wheel load. It is possible to supply hydraulic pressure to the rear wheel cylinder, and in the event that the vehicle height adjustment pressure decreases or disappears, the second actuator, which was kept in the non-operating position by the vehicle height adjustment pressure, will be activated. The second piston moves to the operating position, and the elastic force of the spring applies a biasing force to the valve piston toward the non-operating position, suppressing the braking fluid pressure transmitted to the rear wheel cylinder to an unexpectedly low level. It is possible to prevent this. Since the elastic force of the spring of the second actuator is fixed in advance, the hydraulic pressure control device is no longer a load-sensing hydraulic pressure control device, but it is necessary to adjust the elastic force of the spring of the second actuator to an appropriate value. By setting this, it is possible to ensure that appropriate braking fluid pressure is transmitted to the rear wheel cylinders even when the vehicle height adjustment pressure is lost. The elastic force of the spring of the second actuator can be set so that the control characteristic of the hydraulic pressure control device is suitable for the constant volume state of the vehicle when the vehicle height adjustment pressure is lost; It is also possible to set so as to obtain control characteristics suitable for a half-loaded state or a light-loaded state.

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

In the figure, 10 is a master cylinder, which generates hydraulic pressure of the same height in the first pressurizing chamber 14 and the second pressurizing chamber 16 when the brake pedal 12 is depressed. The hydraulic pressure generated in the first pressurizing chamber 14 is transmitted to the front wheel cylinders 18 of the left and right front wheel brakes via the liquid passage 17. In addition, the hydraulic pressure generated in the second pressurizing chamber is transmitted through a liquid passage 19, a proportioning valve (hereinafter referred to as P valve) 20, which is a type of hydraulic pressure control valve, and a liquid passage 21 to the left and right rear wheel brakes. The signal is transmitted to the rear wheel cylinder 22.

The P valve 20 includes a housing body 26 in which a stepped hole 24 is formed, and a sleeve 28 is screwed into the opening of the stepped hole 24 to constitute a valve housing together with the housing body 26. The valve piston 3 is located in the center hole of the sleeve 28.
0 is slidably inserted through the valve piston 30, and one end of the valve piston 30 is exposed to the outside of the valve housing. The valve piston 30 is integrally provided with a valve element 32 at its inner end, and forms an on-off valve together with a cup-shaped rubber valve seat member 34 provided at the stepped portion of the stepped hole 24. The valve piston 30 also includes a flange 36 proximate to the valve head 32;
The valve element 3 is fixed to the housing body 26 by the sleeve 28, and a spring 40 is installed to apply a certain preload between the seat plate 38 and the valve body 38.
2 is biased toward the inoperative position away from the valve seat member 34. The space inside the valve housing is
2 is seated on the valve seat member 34, the first hydraulic pressure chamber 44 communicates with the input port 42, and the output port 4
6 and a second hydraulic pressure chamber 48 communicating with the hydraulic pressure chamber 6. Note that 50 is an O-ring and 52 is a piston cup.

On the side of the P valve 20 from which the valve piston 30 protrudes, a first actuator 54 and a second actuator 56 are both provided concentrically with the valve piston. Both actuators 5
Reference numeral 4, 56 denotes a single housing member consisting of a first housing member 58 screwed onto the housing body 26 of the P valve 20, and a second housing member 62 and a third housing member 64 fixed thereto by bolts 60. They are installed in a state where they share a housing.
The first actuator 54 includes a diaphragm-type first piston 70 whose outer periphery is made up of a rubber sheet 66 sandwiched between a first housing member 58 and a second housing member 62, and a metal plate 68 that is brought into close contact with the rubber sheet 66. It is equipped with Similarly, the outer peripheral edge of the second actuator 56 is connected to the second housing member 6.
A diaphragm-type second piston 76 is provided, which is composed of a rubber sheet 72 sandwiched between a rubber sheet 72 and a third housing member 64, and a metal cup-shaped member 74 that is brought into close contact with the rubber sheet 72. These first pistons 70
The space formed between the first piston 70 and the second piston 76 is a pneumatic chamber 78, and the air pressure supplied to the pneumatic chamber 78 acts on the first piston 70 and the second piston 76, causing them to be compressed by a spring 80. It is designed to operate against the elastic forces of and 82. The spring 80 has a weak elastic force and merely acts to bias the first piston 70 in one direction, that is, in the direction away from the exposed end of the valve piston 30, whereas the spring 82 has a weak elastic force. It is said to have a strong elastic force, and when air pressure is not supplied to the air pressure chamber 78, the second piston 76 is moved toward the first piston 70 side and brought into close contact with the surface of the second piston 76 on the air pressure chamber side. The first piston 70 is brought into contact with the first piston 70 through the operating protrusion 86 of the operating member 84, which acts to apply an urging force to the valve piston 30 toward the non-operating position. The elastic force of the spring 82 can be set to a desired value, but in this embodiment, it is set so that the P valve 20 performs a hydraulic pressure control operation suitable for when the vehicle is in a half-loaded state. has been done.

The air pressure chamber 78 is connected to a controller 92 of a vehicle height adjustment device through an air passage 90. The controller 92 is equipped with a leveling valve (not shown) for detecting the height of the vehicle body.
The air pressure (vehicle height adjustment pressure) necessary to maintain the vehicle height at a predetermined constant height regardless of the size of the carrying load is supplied to the absorber 94 connected between the vehicle body and the unsprung member. However, the same vehicle height adjustment pressure passes through the air passage 90 to the air pressure chamber 78.
It is now being transmitted to

Next, the operation will be explained.

When the vehicle height adjustment device is in the non-operating state, vehicle height adjustment pressure is not supplied to the pneumatic chamber 78, and therefore, the second piston 76 is moved against the first piston 70 by the elastic force of the spring 82. The second piston 76 is pressed against the spring 80.
contacts the valve piston 30 against the elastic force of
It is held in the inactive position.

When the vehicle height adjustment device is activated, the air pressure chamber 78
The second piston 76 resists the elastic force of the spring 82 and moves the cup-shaped member 7
4 is pushed back until it abuts the third housing member 64 and leaves the first piston 70. At the same time, the first piston 70 is pressed against the valve piston 30 by the vehicle height adjustment pressure in the pneumatic chamber 78, and is urged toward the non-operating position.

In this state, when the brake pedal 12 is depressed and brake fluid pressure is generated in the master cylinder 10, the P valve 2 is directly applied to the front wheel cylinder 18 and the P valve 2 is applied to the rear wheel cylinder 22.
Braking fluid pressure is supplied through 0 respectively. While this braking fluid pressure is low, the valve piston 30 is kept in the non-operating position, and the fluid pressure in the master cylinder 10 is directly transmitted to the wheel cylinder 22. However, when the fluid pressure increases, the valve piston 30 The force pushing the valve housing outward overcomes the force urging the valve piston 30 to the non-operating position, that is, the sum of the elastic force of the spring 40 and the operating force of the first piston 70, and the valve piston 3
0 is pushed out of the valve housing a certain distance until the valve element 32 is seated on the valve seat member 34. After this, the hydraulic pressure in the first hydraulic pressure chamber 44 and the hydraulic pressure in the second hydraulic pressure chamber 48 act on the valve piston 30, thereby causing the valve piston 30 to perform a well-known control operation. The hydraulic pressure of the master cylinder 10 is reduced at a constant ratio and transmitted to the wheel cylinder 22.

Incidentally, although the preload of the spring 40 is always constant, the operating force of the first piston 70 increases as the air pressure in the air pressure chamber 78, that is, the vehicle height adjustment pressure, increases. The higher the vehicle height adjustment pressure, the higher the hydraulic pressure within the valve housing when the valve 30 moves from the non-operating position to the operating position as described above. and,
Since the vehicle height adjustment pressure has a one-to-one correspondence with the rear wheel load of the vehicle, the turning point hydraulic pressure of the P valve will eventually increase or decrease as the rear wheel load increases or decreases, and the P valve 20 of this embodiment It will act as a load sensing type P valve.

The above is the operation of the hydraulic pressure control device when the vehicle height adjustment device is operating normally, but in the unlikely event that the vehicle height adjustment device malfunctions, sufficient vehicle height adjustment pressure is not supplied to the pneumatic chamber. 78, the operating force of the first piston 70 decreases or disappears, resulting in insufficient force to bias the valve piston 30 to the non-operating position. However, in the device of this embodiment, at the same time, the downward force exerted on the second piston 76 by the vehicle height adjustment pressure also decreases or disappears, so that the second piston 76
is moved to the operating position by the elastic force of the first piston 7 through the operating projection 86 of the operating member 84.
It comes into contact with 0. This causes spring 8
2 is transmitted to the valve piston 30, but in this embodiment, the spring 82
The elastic force of is set so that the valve piston 30 performs an optimal hydraulic control operation when the vehicle is half loaded, so the P valve 20 acts as an optimal non-load-sensing P valve when the vehicle is half loaded. .

One embodiment of the present invention has been described in detail above, but
The present invention is not limited to this embodiment.
For example, it is possible to use a limit valve instead of the proportioning valve as the hydraulic pressure control valve, and the spring 4 in the above embodiment can also be used as a hydraulic control valve.
It is also possible to omit 0 and/or 80.
Furthermore, it is effective to arrange the first piston and the second piston concentrically with the valve piston in order to simplify the structure of the entire device. It is also possible to provide these actuating forces to the valve piston 30 through other members such as a lever. Furthermore, the vehicle height adjustment device is not limited to the one described in the above embodiment, and as long as the vehicle height is adjusted using fluid pressure such as air pressure or oil pressure, the method and structure of the vehicle height adjustment may be changed. No question.

In addition, although no specific examples will be given, it goes without saying that the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art.

[Brief explanation of the drawing]

The figure is a front sectional view of a hydraulic pressure control device that is an embodiment of the present invention, and is also a system diagram showing the state in which it is installed. 10: Master cylinder, 19, 21: Liquid passage,
20: Proportioning valve (P valve),
22: Rear wheel cylinder, 26: Housing body, 28: Sleeve, 30: Valve piston,
32: valve element, 34: valve seat member, 54: first actuator, 56: second actuator, 58: first housing member, 62: second housing member,
64: third housing member, 70: first piston, 76: second piston, 78: pneumatic chamber, 8
2: Spring, 84: Acting member.

Claims (1)

[Scope of claim for utility model registration] In a vehicle equipped with a hydraulic vehicle height adjustment device,
A device that is installed in a fluid passage connecting a brake master cylinder and a wheel cylinder of a rear wheel brake and controls the braking fluid pressure transmitted to the wheel cylinder, with one end exposed to the outside of the valve housing. When the master cylinder is in the inoperative position pushed into the housing, the hydraulic pressure of the master cylinder is directly transmitted to the wheel cylinder, and the hydraulic pressure within the housing allows a hydraulic pressure control valve having a valve piston that suppresses hydraulic pressure transmitted to the wheel cylinder in an operating position pushed out a certain distance outside the housing; and a hydraulic pressure control valve that receives vehicle height adjustment pressure from the vehicle height adjustment device. a first actuator that acts on the valve piston directly or indirectly through another member to bias the valve piston toward the non-operating position; Although it is biased, it is kept in a non-acting position against the elastic force of the spring when it receives the vehicle height adjusting pressure, and moves to the working position when the vehicle height adjusting pressure decreases or disappears. a second actuator that acts on the valve piston directly or indirectly through another member, and includes a second piston that biases the valve piston to the non-operating position by the elastic force of the spring. A brake fluid pressure control device for a vehicle equipped with a fluid pressure vehicle height adjustment device.