JP2000097369A - Relief valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To be opened by a pressure except for a set pressure and to secure a stable relief characteristics by providing a pressure chamber applying a fluid pressure in the valve opening direction against an energizing means of a valve element and by providing an orifice in a pressure introduction port to the pressure chamber. SOLUTION: This relief valve has an inlet port 12 connected to a tank which is, for example, to be held at a prescribed pressure or less, and a valve element receiver 21 is seated on a valve seat 15 by a force of a compression spring 29 at all times so as to intercept the communication between the inlet port 12 and an outlet port 13. When a tank internal pressure exceeds a prescribed value, a pilot pressure is applied on a pressure chamber 30 via a fluid pressure introduction port 31. The pilot pressure moves a valve stem 20 in the valve opening direction against the force of the compression spring 29 so that the valve element receiver 21 is separated from the valve seat 15 and the tank internal pressure is relieved from the outlet port 13. Then, an orifice 32 is provided in the fluid pressure introduction port 31 of the pressure chamber 30 so that the vibration phenomena of the valve stem 20 is prevented and accurate relief characteristics are provided, even if the tank internal pressure or the pilot pressure is fluctuated in a narrow range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a relief valve that opens when a fluid pressure exceeds a certain value.

[0002]

2. Description of the Related Art A relief valve has a basic structure in which a flow path between an inlet port and an outlet port is always closed by a valve body urged in a valve closing direction. Overcomes the biasing force, the valve moves to open the flow path between the inlet and outlet ports, releasing pressure.

A relief valve having such a basic structure cannot discharge fluid except at a set pressure, and may generate vibration depending on a flow rate range. A relief valve having a low pressure has a stable relief characteristic. There was a problem that it could not be obtained.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a relief valve which can be opened at a pressure other than a set pressure, can obtain a stable relief characteristic irrespective of pressure and flow rate, and does not generate vibration.

[0005]

SUMMARY OF THE INVENTION The present invention comprises a housing having an inlet port on which fluid pressure acts and an outlet port; a valve body movably supported on the housing to open and close a flow path between the inlet port and the outlet port. And a biasing means for biasing the valve body in the valve closing direction; and a closed pressure chamber for exerting a fluid pressure in the valve opening direction on the valve body against the biasing means. And an orifice is provided at the fluid pressure inlet to the pressure chamber.

According to this relief valve, not only can the valve be freely opened by an independent pilot pressure, but also an orifice is provided at a fluid pressure inlet to the pressure chamber, thereby restricting the flow of fluid into and out of the pressure chamber. Therefore, accurate relief characteristics can be obtained without the valve body vibrating.

The orifice may be formed in the wall of the housing that defines the pressure chamber, through which the inlet port pressure or a pilot pressure independent of the inlet port pressure may be exerted. Alternatively, the inlet port and the pressure chamber may be communicated via a communication passage provided in the valve shaft of the valve body, and an orifice may be formed in this communication passage.

The pressure chamber can be constituted by using a diaphragm, a rolling diaphragm, a metal diaphragm, a packing piston, etc. According to the metal diaphragm, the pressure chamber also serves as an urging means for urging the valve in the valve closing direction. It is also possible.

[0009]

1 and 2 show a first embodiment of a relief valve according to the present invention. Housing 1
1 comprises a main body 11a and a cap body 11b, and an inlet port 12 and an outlet port 13 are formed in the housing main body 11a.
3 are communicated via a communication path 14. Communication passage 1
Reference numeral 4 penetrates through the housing body 11a and also serves as a valve shaft sliding hole, and the valve shaft 20 is slidably fitted in the communication passage.

The valve shaft 20 has a valve body receiver 21 corresponding to the valve seat 15 between the inlet port 12 and the outlet port 13 thereof.
An O-ring 22 is fitted in the valve body receiver 21 as a valve body that comes into contact with and separates from the valve seat 15. An end of the valve shaft 20 opposite to the valve body receiver 21 protrudes from the housing body 11a, and a diaphragm assembly 24 is fixed to the protruding portion. The diaphragm assembly 24 includes a piston body 25, a rolling diaphragm 2
6, a retainer plate 27 and a lock nut 28. Between the diaphragm assembly 24 and the housing main body 11a, a compression spring 29 for urging the valve shaft 20 to move in a direction in which the valve body O-ring 22 is seated on the valve seat 15 (valve closing direction) is inserted. .

The peripheral bead portion 26a of the rolling diaphragm 26 is sandwiched between the end face of the housing body 11a and the cap body 11b, and a pressure chamber 30 is formed between the diaphragm assembly 24 and the cap body 11b. I have. The cap body 11b is provided with a fluid pressure inlet 31 for communicating the pressure chamber 30 with the pilot pressure passage, and the fluid pressure inlet 31 is provided with an orifice 32 for narrowing the flow path.

The relief valve having the above-described structure is used by connecting the inlet port 12 to, for example, a tank to be kept at a predetermined pressure or less. The user sits on the valve seat 15 and cuts off the communication between the inlet port 12 and the outlet port 13. When it is detected that the pressure in the tank exceeds a predetermined value, a pilot pressure is applied to the pressure chamber 30 via the fluid pressure inlet 31. The pilot pressure moves the valve shaft 20 in the valve opening direction against the force of the compression spring 29 in consideration of the pressure receiving area of the diaphragm assembly 24, the pressure on the tank side, and the pressure receiving surface of the valve body receiver 21. As a result, the valve body receiver 21 (O-ring 22) is separated from the valve seat 15 to release the pressure in the tank from the outlet port 13 to the outside. As a result, when the pressure in the tank decreases, the pressure is detected, the pilot pressure decreases, and the valve body receiver 2
1 (O-ring 22) is again seated on the valve seat 15 by the force of the compression spring 29, and the communication between the inlet port 12 and the outlet port 13 is cut off. As a result of the opening and closing operations being performed continuously, the pressure in the tank is maintained at a constant value. Further, if the pilot pressure is obtained from an independent circuit, it is possible to discharge the fluid regardless of the pressure in the tank.

According to this embodiment, the pressure chamber 30
Since the orifice 32 is provided in the fluid pressure inlet 31 of the above, even if the pressure in the tank rises and falls in a narrow range or the pilot pressure rises and falls in a narrow range, the valve shaft 20 (the valve body receiver 21) is No vibration phenomenon occurs. That is,
Even if the pilot pressure changes according to the sensor output for detecting the pressure fluctuation in the tank, it takes time for the pressure to appear as the pressure fluctuation in the pressure chamber 30 as compared with the case where the orifice 32 does not exist. . That is, a damper effect is obtained for the movement of the valve shaft 20. Therefore, the vibration phenomenon of the valve shaft 20 (the valve body receiver 21) can be prevented, and as a result, accurate relief characteristics can be obtained.

The pressure applied to the fluid pressure inlet 31 may be the pressure at the inlet port 12, that is, the pressure at the tank side, instead of the pilot pressure. In this case, FIG.
, The inlet port 12 and the fluid pressure introduction port 31 may be connected by a communication pipe 33.

FIG. 3 shows another embodiment of the present invention. This embodiment is characterized in that the pressure of the inlet port 12 is applied to the pressure chamber 30, and the inlet port 12 and the pressure chamber 30 are connected to the valve shaft 20.
A communication passage 40 and an orifice 41 for communicating
A point where an elastic valve element 42 is used in place of the O-ring 22 of the valve element receiver 21 and a point where the metal diaphragm 43 is used for the diaphragm assembly 24 and the valve shaft 20 is urged in the valve closing direction by the elastic restoring force (compression) This embodiment differs from the first embodiment in that the spring 29 is omitted. One end of the diaphragm assembly 24 is fixed to a flange 20f provided at an end of the valve shaft 20, and the other end is a ring hermetically sandwiched between the main body 11a and the cap body 11b via a packing 44. It is fixed to a member 45. Another point is that
This is the same as the first embodiment, and the same components are denoted by the same reference numerals.

According to this embodiment, the relief action can be performed by directly detecting the pressure of the inlet port 12, that is, the pressure of the tank, and, similarly to the first embodiment,
The vibration phenomenon of the valve shaft 20 (the valve body receiver 21) can be prevented, and an accurate relief pressure can be obtained.

[0017]

As described above, according to the present invention, an accurate relief characteristic can be obtained even when the opening pressure is small, and a relief valve which does not generate vibration even in a vibration region can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a relief valve according to an embodiment of the present invention in a closed state.

FIG. 2 is a sectional view of the relief valve in FIG. 1 in an open state.

FIG. 3 is a cross-sectional view of a relief valve according to another embodiment of the present invention in a closed state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Housing 12 Inlet port 13 Outlet port 14 Communication passage 15 Valve seat 20 Valve shaft 21 Valve body reception 22 O-ring 24 Diaphragm assembly 29 Compression spring 30 Pressure chamber 31 Fluid pressure introduction port 32 41 Orifice 33 Communication conduit 40 Communication passage 43 Metal Diaphragm

Claims (4)

[Claims] 1. A housing having an inlet port on which fluid pressure acts and an outlet port; a valve body movably supported by the housing to open and close a flow path between the inlet port and the outlet port; A biasing means for biasing the body in the valve closing direction; a closed pressure chamber for exerting fluid pressure in the valve opening direction on the valve body against the biasing means; and a fluid pressure inlet to the pressure chamber. A relief valve provided with an orifice; 2. The relief valve according to claim 1, wherein the orifice is formed in a wall surface of a housing defining a pressure chamber, and through the orifice, the inlet port pressure or a pilot pressure independent of the inlet port pressure. Is exerted on the relief valve. 3. The relief valve according to claim 1, wherein the inlet port communicates with the pressure chamber through a communication passage provided in a valve shaft of the valve body, and the orifice is formed in the communication passage. Relief valve. 4. The relief valve according to claim 1, wherein the pressure chamber is formed by a metal diaphragm, and the metal diaphragm includes an urging means for urging the valve body in a valve closing direction. Relief valve that doubles.