JPH0452810A - Pressure reducing valve - Google Patents

Abstract

PURPOSE:To remove chattering phenomenon by applying the flexure force of a diaphragm receiving the elastic force of a pressure setting spring by one face and secondary pressure by the other face to a main valve and a pilot valve. CONSTITUTION:The diaphragm 48 is curved in accordance with secondary side pressure applied to its lower face, displaces a main valve stem 24 and a pilot stem 46 and opens the 1st main valve 16 and the pilot valve 42. When a flow rate is low and the main value 16 and the pilot valve 42 of a direct type pressure reducing valve 12 are slightly opened, the valve 16 is opened, high pressure fluid on the primary side is directly allowed to flow into the secondary side through a secondary pressure detecting passage 50 so as to maintain the secondary side pressure, and when the valve 42 is in a slightly opened state, fluid flowing into a piston room 32a is little and almost all the fluid flows out from an orifice 32c formed on a piston 32. Thereby, no driving force is generated on the piston 32 and the 2nd main valve 30 is not opened. In said status, a small flow rate area is covered by the valve 12, so that the valve 12 can suppress the generation of chattering and execute stable pressure reducing action. Even when load on the secondary side is increased and the main valve 16 and the pilot valve 42 of the valve 12 are sharply opened, the chattering phenomenon can be similarly removed.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a pressure reducing valve that is attached to a fluid piping system to reduce the fluid pressure on the primary side and maintain the fluid pressure on the secondary side at a predetermined set pressure. Must have.

<Prior art> There are two types of pressure reducing valves: one is a direct-acting type in which the secondary side pressure detection part itself acts as an operating part that directly operates the valve body, and the other is a direct-acting type that operates by detecting the secondary side pressure. The pressure reducing valve is used as a pilot valve part, and the main valve body is operated by adjusting the five forces of the main valve body operating part.In general, when a flow rate is required, the method disclosed in Utility Model Application Publication No. 63-48211 is used. A pilot operated pressure reducing valve such as that disclosed in . This is because the high-pressure fluid supplied from the inlet connected to the downstream side flows out to the secondary side and the secondary side due to the pressure drop on the secondary side connected to the outlet, which causes the main valve to move downward and open. It is designed to compensate for the drop in side pressure. The main valve is opened by the lowering of the piston, which is controlled by an upper pilot valve, a diaphragm associated with the pilot valve, a pressure setting spring, etc., and closed by the higher piston.

<Problems to be Solved by the Invention> However, the above-mentioned pilot type pressure reducing valve cannot be used when the set pressure (secondary side pressure) is smaller than the -outlet side pressure, that is, when the pressure reduction ratio is large, or when the main valve is opened. There is a problem in that a significant chattering phenomenon tends to occur when the flow rate is small or small.

The pressure reduction ratio is, for example, when reducing the pressure on the downstream side from 10 kg/car to about 2 KI/ci or less on the secondary side, and movable parts such as the main valve and piston vibrate, causing a chattering phenomenon. In other words, when the pressure reduction ratio is large or the flow rate is small, the pilot valve is slightly open, and the primary fluid passing through it provides driving force to the piston, which pushes down the main valve and opens the valve port. The valve is operated to supply the primary fluid to the secondary side. However, at this time, since the pressure difference between the downstream side and the secondary side is large, the secondary side pressure rises instantaneously, and this pressure suddenly closes the slightly open pilot valve via the diaphragm. If the pilot valve suddenly closes, the fluid to the top of the piston is suddenly cut off, causing the piston to rise rapidly and the main valve to close suddenly. When the main valve suddenly closes, the secondary pressure also drops rapidly, causing the pilot valve to suddenly open again via the diaphragm. The above process is performed at an accelerated rate, resulting in a large photographic state.

In this way, the pilot type pressure reducing valve has the advantage of having a large maximum flow rate, but it has the disadvantage of having a large pressure reduction ratio and being prone to chattering when the flow rate is low. Therefore, the above-mentioned direct acting pressure reducing valve has the advantage that chattering is less likely to occur due to its structure having fewer movable parts such as hysterons and a small phase delay in the control surface. However, it has the disadvantage that the maximum flow rate is small. Therefore, it may be possible to install both pressure reducing valves in parallel and use them depending on the usage conditions, but this is not actually done because of problems such as piping, location, and installation time.

Therefore, the technical problem of the present invention is to provide a pressure reducing valve that can handle a small flow rate to a large flow rate without causing the chattering phenomenon.

Means for Solving the Problems> The technical means of the present invention taken to solve the above technical problems is to incorporate a direct acting pressure reducing valve mechanism and a pilot type pressure reducing valve mechanism in the same main body, The elastic force of the pressure setting spring is applied to one side of the diaphragm, and the secondary impression force is applied to the other side, and the deflection force of the diaphragm generated by the balance between the two forces is applied to the main valve in the direct acting pressure reducing valve mechanism. , which acts on the pilot valve in a pilot operated pressure reducing valve mechanism.The elastic force of the pressure setting spring is too small, or the flow rate is low, causing the main valve and pilot valve of a direct acting pressure reducing valve to fail. When in a slightly open state,
In a direct acting pressure reducing valve, the main valve opens and the high pressure fluid on the downstream side directly flows out to the secondary side, acting to maintain the pressure on the secondary side. If the pilot valve of the pilot type pressure reducing valve is slightly open, the fluid on the negative side will not generate any driving force from the driving part such as a piston, and the main valve of the pilot type pressure reducing valve will not open. In other words, in this state, the low flow rate range is covered by the direct acting type pressure reducing valve, and as mentioned above, the direct acting type pressure reducing valve is less likely to cause chattering, so it performs a stable pressure reducing action.

When the main valve and pilot valve of a direct acting pressure reducing valve are opened wide by increasing the elastic force of the pressure setting spring or by increasing the load on the secondary side, the amount of fluid supplied from the pilot valve to the piston will decrease. In order to increase the flow rate, a driving force is generated to open the larger main valve of the pilot type pressure reducing valve, and the overall flow rate increases. At this time, even if the larger main valve of the pilot type pressure reducing valve opens and the high pressure fluid on the primary side flows out to the secondary side, the fluid is already flowing to the secondary side through the direct acting pressure reducing valve. There is no significant pressure fluctuation, and no chattering phenomenon occurs.

Example> A specific example of the above technical means will be described. (
(See Figure 1) Hero 8. Main body 2 with outlet 10, pilot body 4
, a spring case 6 forms a valve housing, and a direct acting pressure reducing valve section 12 and a pilot type pressure reducing valve section 14 are respectively built therein. The direct-acting pressure reducing valve section 12 has a first valve port 20 and is opened and closed by a first valve body 16 which is biased in the valve closing direction by a first main valve spring 18. It is formed by being screwed to the valve 4. A main valve stem 24 for opening the first main valve 16 by pushing is fixedly disposed in the center of the main valve kite 22.

The pilot type pressure reducing valve 14 is configured as follows. A main valve seat 28 forming a second valve port 26 is arranged so as to communicate the inlet 8 and the outlet 10, and the second main valve 30 is elastically biased at the inlet side end by a second main valve spring 28. Deploy. Here the second
The valve port 26 has a sufficiently larger diameter than the first valve port 20.

The piston 32 corresponding to the second main valve 30 is connected to the cylinder 34.
A piston rod 32b formed at the lower part of the piston is brought into contact with the central upper surface of the second main valve 30 through the second valve port 26. Part number 36ab is a piston ring for maintaining airtightness between the piston and the cylinder, and is made of resin such as fluorinated ethylene resin. Reference number 32c is an orifice that communicates between the upper and lower surfaces of the piston. The techniques mentioned here either maintain airtightness between the piston and the cylinder and allow a certain amount of fluid to escape using an orifice, or other common techniques do not form an orifice, but instead create one on the circumferential side of the piston. It may also have a labyrinth structure.

The upper space between the inlet 8 and the piston 32, that is, the piston ¥32
A stem kite 44 in which a pilot valve 42 biased in the valve closing direction by a biasing spring 40 is disposed in a primary pressure passage 38 communicating with the valve a is screwed to the small pilot day 4. A pilot (~ stem 46) is slidably arranged on the stem kite 44 to open the pilot valve 42 by pushing it. Connect it to the communication hole for introducing it to the primary side.

Install the tire flam 48 by sandwiching its outer peripheral edge between the spring case 6 and the flange of the small pilot day 4,
The space below the diaphragm 48 communicates with the outlet 10 through the secondary pressure detection passage 50, and the lower surface of the diaphragm 48 abuts the head end surfaces of the main valve stem 24 and the pilot stem 46.

A pressure setting spring 54 is brought into contact with the upper surface of the diaphragm 48 via a spring seat 52, and its upper end is biased by an adjusting screw 56 screwed to the spring case 6.

The action is as follows. When the adjusting screw 56 is turned left and right, the elastic force of the pressure setting spring 54 that pushes down the diaphragm 48 changes. Using the elastic force of the pressure setting spring 54 as a reference value, the diaphragm 48 curves in response to the secondary side pressure acting on its lower surface, displacing the main valve stem 24 and the pilot stem 46, and causing the first main valve 16 and the pilot stem to displace. valve 42
to open the door.

The elastic force of the pressure setting spring 54 is small, or the flow rate is low and the main valve 16 and pilot valve 42 of the direct acting pressure reducing valve 12
In the direct acting pressure reducing valve, when the main valve 16 is opened, the high pressure fluid on the downstream side directly flows out to the secondary side via the secondary pressure detection passage 50, and the act to maintain the pressure. If the pilot valve 42 of the pilot pressure reducing valve is slightly open, less fluid will flow into the piston chamber 32a.
Most of the orifice 3 is formed in the piston 32.
It flows out from 2C. As a result, no driving force is generated in the piston 32, and the second main valve 30 does not open. In other words, in this state, the direct-acting pressure reducing valve 12 covers the low flow rate range, and as described above, the direct-acting pressure reducing valve is less likely to cause chattering, so it performs a stable pressure reducing action.

When the elastic force of the pressure setting spring 56 is strengthened or the load on the secondary side is increased and the main valve 16 and pilot valve 42 of the direct acting pressure reducing valve 12 are opened wide, the direct acting pressure reducing valve In this case, the main valve [6] is further opened to allow the fluid on the primary side to pass to the secondary side. In the pilot pressure reducing valve 14, the amount of fluid supplied from the pilot valve 42 to the piston chamber 32a increases, so a driving force is generated in the piston 32, causing the second main valve 30 to open, and the overall flow rate increases. do. At this time, even if the large main valve 30 of the pilot type pressure reducing valve 14 opens and the high pressure fluid on the primary side flows out to the secondary side, the fluid has already flowed through the direct acting pressure reducing valve 12 to the secondary side. Because of this, there is no significant pressure fluctuation and no chattering phenomenon occurs.

In this embodiment, the reason why the pilot-operated pressure reducing valve 14 operates a little later than the direct-acting pressure reducing valve 12 is to utilize the delay in the time for the primary fluid to accumulate in the piston chamber 32a. A gap may be provided between the upper end surface of the stem 46 and the lower surface of the diaphragm 48, or the pilot valve 42 may be
The elastic force of the biasing spring 40 may be increased, the orifice 32c of the piston 32 may be made large, or the biasing force of the second king valve spring 28 may be increased.

<Effects of the Invention> According to the uninvented technical means, the chattering phenomenon is eliminated, so that the pressure reduction action can be performed in a stable state without damaging the piston main valve and other members. Furthermore, since the chattering phenomenon is eliminated, the minimum adjustable flow rate can be set to a small value, and a pressure reducing valve that can be used over a wide range can be provided.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a pressure reducing valve showing an embodiment of the present invention. Main body 8. entrance Direct acting pressure reducing valve part 14 1st main valve piston diaphragm 10, Exit Pilot operated pressure reducing valve section 30, 2nd main valve 42, Pilot valve 54, pressure setting spring

Claims (1)

[Claims] 1. A direct-acting pressure reducing valve mechanism and a pilot-type pressure reducing valve mechanism are built into the same body, and the elastic force of the pressure setting spring is applied to one side of the diaphragm, and the secondary side pressure is applied to the other side. A pressure reducing valve characterized in that the deflecting force of the diaphragm that is generated is applied to a main valve in the direct acting pressure reducing valve mechanism and a pilot valve in the pilot type pressure reducing valve mechanism.