JPH077236Y2 - Proportioning valve - Google Patents

Description

[Detailed Description of the Invention] a. Field of Industrial Application The present invention relates to a proportioning valve capable of changing the starting point for changing the pressure reduction ratio.

b. Conventional technology and its problems Proportioning valves that change the starting point for changing the pressure reduction ratio are used in load-responsive brake fluid pressure control devices. And, in such a proportioning valve, the air pressure corresponding to the vehicle load is used as the control pressure,
There is one in which the starting point for changing the pressure reduction ratio of the brake hydraulic pressure (hereinafter referred to as the hydraulic pressure break point) is changed. Such a valve is provided with a control piston in a cylinder housing, and a compressed air pressure such as an air suspension is applied to the piston so that the piston having a valve element is pushed by the piston.

c. Problems to be Solved by the Invention By the way, a valve having such a structure generally includes a control section and a valve main section in the same cylinder housing. Therefore, if the packing installed on the peripheral surface of the piston is damaged, the compressed air may flow out to the plunger side and be mixed in the brake fluid.

Therefore, an object of the present invention is to provide a proportioning valve in which air is not likely to be mixed in the brake fluid even if the seal of the packing is broken.

d. Means for Solving the Problems In the proportioning valve of the present invention, the valve main portion that opens and closes the hydraulic fluid passage between the inlet port and the outlet port by operating the plunger that operates the valve body, and as a control pressure medium Same as a control unit that uses compressed air and causes the pressure of the compressed air to act on the plunger through a piston, thereby changing the pressure reduction ratio change start point of the hydraulic fluid supplied from the inlet port to the outlet port. In a proportioning valve provided in a cylinder housing, packings are provided at two positions with a gap in the axial direction between the peripheral surface of the piston and the inner peripheral surface of the cylinder housing, and between the packings at the two locations. At the position between the peripheral surface of the piston and the inner peripheral surface of the cylinder housing. The gap is provided, one end opening into the gap, and the other end is formed with holes opening to the atmosphere.

e. Function In the proportioning valve of the present invention, even if the packing of the control piston is damaged and compressed air leaks toward the valve main part through the packing, the compressed air is released to the atmosphere through the ventilation hole. It

f. Embodiment The figure shows a proportioning valve according to the present invention. This proportioning valve includes a valve main portion A and a control portion B inside a cylinder housing 1.

The valve main part A decompresses the hydraulic fluid flowing from the inlet port 2 and causes it to flow out from the outlet port 3. In the cylinder housing 1, an input chamber 4 communicating with the inlet port 2 and an output chamber 5 communicating with the outlet port 3 are provided. And are formed. These input chamber 4 and output chamber 5
Are communicated with each other via a hydraulic fluid passage 6, and a plunger 7 is inserted into this passage 6. The plunger 7 has a valve body 7a at its lower end, and the valve body 7a faces a valve seat 8 arranged at the end of the passage 6 on the input chamber side. The upper portion of the plunger 7 is supported by the cylinder housing 1 via a guide 9.

On the other hand, the control section B is for changing the hydraulic pressure break point of the hydraulic fluid by the valve main section A described later.
A control piston 10 is provided therein. Two O-rings 11 and 12 as packings are fitted on the peripheral surface of the piston 10 at intervals in the axial direction, and a control pressure chamber 13 is defined on the upper surface of the piston 10. The piston 10 has a rod 14 on the lower surface, and the downward biasing force of the piston 10 is transmitted to the plunger 7 via the ball 15 and the connecting member 16. Further, an annular gap 17 is formed between the cylinder housing 1 and the peripheral surface of the piston 10 between the O-rings 11 and 12. The gap 17 is communicated with the atmosphere by a vent hole 18 formed in the cylinder housing 1.
One end of the vent hole 18 is opened in the gap, and the other end of the vent hole 18 on the atmosphere side is closed by an O-ring 19 which is in circumferential contact with the cylinder housing 1 with a weak pressure. In the drawings, reference numeral 20 is a port of the control pressure chamber 13, and reference numeral 21 is a piston.
Reference numeral 22 denotes a return spring for urging 10 upward, and reference numeral 22 denotes a spring for constantly pressing the ball 15 against the connecting member 16.

Then, this proportioning valve is load-responsive by connecting its inlet port 2 to the master cylinder 23, connecting the outlet port 3 to the wheel cylinder 24, and connecting the port 20 of the control pressure chamber 13 to the air suspension 25. A brake fluid pressure control device is configured.

In the load-responsive brake hydraulic pressure control device configured as described above, compressed air corresponding to the vehicle load is supplied from the air suspension 25 to the control pressure chamber 13. Then, this air pressure acts on the upper surface of the piston 10 to push down the plunger 7, so that the input chamber 4 and the output chamber 5 communicate with each other through the passage 6.

Now, when the master cylinder 23 is operated, a brake operating hydraulic pressure is generated in the input chamber 4, and this hydraulic pressure is transmitted to the rear wheel cylinder 24 through the output chamber 5. At this time, the plunger 7 tends to be pushed up by the differential pressure acting on it. When this force overcomes the force acting on the piston 10, the plunger 7 rises and its valve body 7a contacts the valve seat 8 to close the passage 6 (a so-called hydraulic pressure break point is reached). . When the hydraulic pressure in the input chamber 4 further rises, the plunger 7 moves up and down as described above, and the hydraulic pressure in the input chamber 4 is reduced at a predetermined rate and supplied to the output chamber 5.

In such a load-responsive brake hydraulic pressure control device, the pressure corresponding to the loaded load is transmitted to the control pressure chamber 13, so that the plunger 7 is urged downward by the force corresponding to the pressure. The magnitude of the biasing force of the plunger 7 determines the hydraulic pressure break point.

By the way, in the proportioning valve having such a structure, even if the upper packing 11 is broken, the control pressure chamber
The compressed air in 13 is discharged to the atmosphere through the gap 17 and the ventilation hole 18 and does not flow out below the piston 10.

In the above embodiment, the proportioning valve applied to the load-responsive brake fluid pressure control device has been described, but the proportioning valve of the present invention is applied to the load-responsive brake fluid pressure control device. Not exclusively.

Further, in the above embodiment, the O-ring 19 is provided at the opening of the vent hole 18 on the atmosphere side to prevent dust and the like from entering the vent hole 18, and at the same time, the compressed air is discharged from the vent hole 18 to the atmosphere. The O-ring 19 is not necessary if it is not necessary to consider the prevention of intrusion of dust and the like. Furthermore, in the above embodiment, the O-ring 12 is arranged on the piston 10 to ensure that compressed air is prevented from entering the lower portion of the piston 10.

e. Effect of the Invention According to the present invention, even if the seal of the packing provided on the piston is broken, the packing is also arranged at a position closer to the valve main part with respect to the gap communicating with the ventilation hole, and the control pressure chamber Since the air in the cylinder is reliably discharged into the atmosphere through the ventilation holes of the cylinder housing, there is no possibility that air will be mixed into the working fluid of the valve main part, and the peripheral surface of the piston and the cylinder housing Since a gap is provided between the inner peripheral surface and the inner peripheral surface, the structure is simplified.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a proportioning valve according to the present invention. 1 ... Cylinder housing, 2 ... Inlet port, 3 ...
Outlet port, 4 ... Input chamber, 5 ... Output chamber, 6 ... Hydraulic fluid passage, 7 ... Plunger, 7a ... Valve body, 8 ... Valve seat, 10 ...
Control pistons, 11, 12 ... O-rings, 13 ... Control pressure chambers, 17
… Gap, 18… Vent hole, 19… O ring, 20… Port, A…
Valve main part, B ... Control part.

Claims (1)

[Scope of utility model registration request] 1. A valve main part for opening and closing a hydraulic fluid passage between an inlet port and an outlet port by operating a plunger for operating a valve body, and compressed air is used as a control pressure medium. A proportioning valve provided with a control unit that acts on the plunger via a piston, thereby changing the decompression ratio change start point of the hydraulic fluid supplied from the inlet port to the outlet port, in the proportioning valve The packing is arranged at two locations spaced apart in the axial direction between the circumferential surface of the piston and the inner circumferential surface of the cylinder housing, and the circumferential surface of the piston and the cylinder housing are located between the two packings at the two locations. A gap is provided between the inner peripheral surface and the inner peripheral surface, one end of which is open to the gap and the other end of which is open to the atmosphere. Proportioning valve, characterized in that the formation of the vent holes.