JPS63255713A - Piston structure for pressure reducing valve - Google Patents

Abstract

PURPOSE:To uniformize the gap between a piston and the inside peripheral wall of a cylinder by forming the side face of the piston of a pressure reducing valve into a spherical surface. CONSTITUTION:A piston 101 of the pressure reducing valve is provided with a hole 106 which is extended downward to the center from the top of a spherical body having a diameter slightly smaller than the inside diameter of a cylinder 22, and a piston rod 103 is provided under the spherical body on the same axis as the hole 106. Annular grooves 107 and 108 are worked on upper and lower parts of the outside peripheral surface of the spherical body with the hole 106 as the center, and piston rings 69 and 70 are arranged in these grooves and are elastically energized to the inside peripheral wall of the cylinder from inside by elastic members 71 and 72. A recessed part 10 is provided on the upper end of an upper projecting part 109 of a main valve body 102, and the lower end of said piston rod 103 is fitted to this recessed part 110. Thus, even if the main valve body 102 and the piston rod 103 are guided to the exit side by the fluid passing a valve hole 14 and the piston 101 is inclined, the gap around the inside peripheral wall of the cylinder is always uniformized and the piston is slided in this state because a piston side face 111 is formed into a spherical surface.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to the construction of a piston portion of a pilot-operated pressure reducing valve that is attached to piping for steam, compressed air, etc. and maintains the pressure on the secondary side at a predetermined set pressure. .

2. Description of the Related Art Conventionally, as shown in FIG. 2, a piston was generally disposed in a cylinder so as to be slidable therein.

The operation as a pressure reducing valve will be explained below.

The pressure reducing valve shown here consists of a pressure reducing valve part 1, a steam/water molecule part 2, and a drain valve part 3. The main body 10 has an entrance 12. Valve port 14. An outlet 16 is formed. The inlet is connected to a high-pressure fluid source on the primary side, and the outlet is connected to a low-pressure region on the secondary side. The valve port is formed by a valve seat member.

The main valve body 18 is placed on the valve seat at the inlet side end of the valve port 14 and is elastically biased by a coil spring.

The piston 20 is slidably disposed within the cylinder 22, and the piston rod is brought into contact with the central protruding rod of the main valve body 18 through the valve port 14. The lower surface of the piston and the piston rod 12 are connected by a substantially hemispherical surface. A pilot valve 26 is disposed in a primary pressure passage 24 that communicates the inlet 13 with the upper space of the piston 20, that is, the piston chamber. The diaphragm 28 is mounted with its outer peripheral edge sandwiched between the flanges 30,32. The space below the diaphragm 28 passes through the secondary pressure passage 34 to the outlet 1.
It connects to 6.

The head end surface of the valve stem 36 of the pilot valve 26 abuts against the central lower surface of the diaphragm 28 .

A pressure setting coil spring 40 is brought into contact with the upper surface of the diaphragm 28 via a spring seat 38. The adjustment screw 44 is screwed and attached to the main body 10.

By turning the adjustment screw 44 left and right, the elastic force of the pressure setting spring 40 that pushes down the diaphragm 28 changes.

Using the elastic force of the pressure setting spring 40 as a reference value, the diaphragm 28 curves in response to the secondary pressure acting on its lower surface, displacing the valve rod 36 and opening and closing the pilot valve 26. As a result, the next side fluid pressure is introduced into the piston chamber, the piston 20 is driven, the main valve body 18 is displaced, and the fluid at the inlet 12 passes through the valve port 14 to the outlet 16.
flows to

This is because when the fluid pressure on the secondary side decreases, the valve port 14 opens.
It automatically closes when the top is raised.

A cylindrical partition member 46 is attached below the valve port 14 (length), forming an annular space 48 between it and the main body 10 surrounding it.
Its upper part communicates with the inlet 12 through a horn-shaped screen 50, and its lower part communicates with the upper part of the drain valve chamber 52.

Further, the upper part of the drain valve 52 communicates with the valve port 14 through the central opening of the partition member 46. A swirl vane 54 made of an inclined wall is arranged in the annular space 48.

Therefore, when the valve port 14 opens and the fluid in the inlet 12 passes through the annular space 48, its direction is bent by the swirl vanes 54 and the fluid is swirled. The liquid is taken out to the outside, hits the surrounding inner wall of the main body, and flows down into the drain valve chamber 52, while the light gas swirls around the center and flows from the central opening of the partition member 46 to the valve port 1.
4, through which it flows away to exit 16.

A drain valve port 58 communicating with the drain port 56 is formed at the bottom of the drain valve chamber 52 . Covered with a float cover 62, a spherical valve float 60 is movably accommodated. A ventilation hole 64 is opened in the upper part of the float cover 62.

Therefore, the valve float 60 floats up and down with the water level in the drain valve chamber 52 to open and close the drain valve port 58, and automatically removes water accumulated in the drain valve chamber 52.

Problems to be Solved by the Invention It is desirable that the gap between the piston and the cylinder be as small as possible in order to receive the pressure from the pilot valve sufficiently efficiently. , it becomes inoperable. Therefore, a certain amount of clearance must be provided between the piston and the cylinder.

With the above background, when high-speed fluid flows from the valve port to the outlet side, the piston column becomes resisted by the fluid and tilts, causing the entire piston to tilt and the diagonal portion of the piston to catch on the inner wall of the cylinder. For this reason, the piston and cylinder do not open smoothly, and stable secondary pressure cannot be maintained.

In addition, because the screws 1 to 1 are caught, the main valve, which is in contact with the lower part of the piston, cannot make complete contact with the valve seat surface, and the shutoff pressure increase, which is one of the test items that indicates the performance of the pressure reducing valve, becomes high.

The technical problem of the present invention is to allow the piston to always remain upright and open the inner wall of the cylinder without being affected by the flow of fluid.

Means for Solving the Problems The technical means of the present invention taken to solve the above problems is to apply the elastic force of the pressure setting spring to the upper surface of the diaphragm and the secondary side pressure to the lower surface to balance the two. In pilot-operated pressure reducing valves, the pilot valve opens and closes depending on the situation, controlling the amount of fluid on the primary side to operate the piston, and keeping the secondary pressure constant. This is what I did.

Even if the piston is tilted by the fluid flowing through the main valve port, the side surface of the piston is spherical, so the gap between it and the inner circumferential wall of the cylinder always remains constant, eliminating any stuck parts. Therefore, no matter how much the piston tilts, it slides smoothly inside the cylinder.

Effects of the Invention Accordingly, good results can be obtained in specific test items showing the performance of a pressure reducing valve, such as shut-off back pressure, pressure-flow characteristics, etc.

By eliminating the unstable opening movement caused by the piston getting stuck, chattering and hunting can be prevented, and damage to equipment and equipment attached to the secondary side of the pressure reducing valve can be prevented.

Furthermore, even when the main valve is closed, the piston remains vertical and stands upright, so the main valve is completely closed and erosion due to valve leakage is eliminated.

4. Example An example showing the above-mentioned specific means will be described below. (
(See FIG. 1) Portions corresponding to FIG. 2 are given the same reference numerals as in FIG. 2, and a detailed description of the pressure reducing valve will be omitted as it is the same as in the prior art section.

The piston 101 of the non-embodiment has a hole 1 extending downward from the upper surface of the sphere having a diameter slightly smaller than the inner diameter of the cylinder.
06, and insert the piston rod 1 at the bottom of the ball coaxial with the hole.
03 will be provided. Therefore, the piston side surface 111 forms a spherical surface. Reference numeral 112 indicates a pore communicating the lower surface of the sphere with the hole 106.

An annular groove "!07.1 around the hole 106 at the top and bottom of its outer circumference
08, a piston ring 69.70 made of tetrafluoroplastic ethylene is placed in it, and an elastic member 71 is inserted from the inside.
．． At 72, the inner peripheral wall of the cylinder is elastically biased.

A recess 110 is provided at the upper end of the upper projection 109 of the main valve body 102, into which the lower end of the piston rod 103 is fitted. The fitting depth is such that the piston is in the uppermost position and the main valve body is in the lowermost position.

The main valve body '102 and the piston rod 103 are guided toward the outlet side by the fluid passing through the valve port 14, and the piston is tilted. However, since the piston side surface 111 is spherical, the gap between the inner circumferential walls of the cylinder does not always remain constant, so there is some movement. Fluid attempting to pass through the gap between the piston ring and the cylinder is blocked by the piston ring 69.70, which is biased by the elastic member 71.72. Even if the piston tilts, the movement force of the piston ring is absorbed by the gap between the annular groove and the elastic member, so the tilting is not hindered.

The piston side surface 111 does not have to be a true spherical surface, but may be an elliptical surface.

In addition, a hollow or rigid ball having a diameter slightly smaller than the inner diameter of the cylinder is arranged as a piston, and the main valve body 102
The protrusion 109 may be extended upward and brought into contact with the protrusion 109 .

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of a main part of an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional pressure reducing valve. 10: Main body 12 Two-man row 14: Valve port 16: Outlet 20: Piston 22 Niji cylinder 26: Pilot valve 69.70: Piston ring 71.72: Elastic member 111: Side surface of piston

Claims (1)

[Claims] 1. The elastic force of the pressure setting spring is applied to the top surface of the diaphragm, and the secondary side pressure is applied to the bottom surface, and the pilot valve is opened and closed depending on the balance state, controlling the amount of fluid on the primary side to operate the piston, and A piston structure for a pressure reducing valve, which is a pilot-operated pressure reducing valve that maintains a constant side pressure, and is characterized in that the side surface of the piston that makes sliding contact with the inner circumferential wall of the cylinder is made into a spherical surface.