JPH01234907A - Pressure reducing valve - Google Patents

Abstract

PURPOSE:To prevent the generation of chuttering even if a flow rate is reduced by fully opening a secondary pressure detecting passage at the time of setting up pressure, and when secondary pressure is stabilized, converging the passage. CONSTITUTION:A throttle valve 78 for reducing the aperture area of the secondary pressure detecting passage 34 is arranged on the passage 34 for leading the secondary side pressure into the lower face of a diaphragm 28. At the time of adjusting the elastic force of a pressure setting spring in order to change a set pressure, the throttle valve 78 is fully opened, and when the secondary side pressure is stabilized, the throttle valve 78 is converged so that the aperture area of the passage 34 is reduced. Consequently, the pressure reducing valve having high responsiveness at the time of setting up pressure and preventing the generation of chuttering even at the time of reducing a flow rate can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a pressure reducing valve that is attached to a piping system for steam, compressed air, etc. to maintain fluid pressure on the secondary side at a constant set pressure.

2. Description of the Related Art A conventional pressure reducing valve is as shown in FIG.

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 main valve 18 is disposed 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 20b is brought into contact with the central protruding rod 18a of the main valve 18 through the valve port 14. The lower surface of the piston 20 and the piston rod 20b are connected by a substantially hemispherical surface. A pilot valve 26 is disposed in a secondary pressure passage 24'' that communicates between the inlet 12 and the upper chamber of the piston 20, that is, the piston 20a.A diaphragm 28 is attached with its outer peripheral edge sandwiched between flanges 30 and 32.Diaphragm The space below 28 communicates with the outlet 16 through a secondary pressure detection passage 34 .

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 spring case 66.

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 increases to the piston chamber 20.
a, the piston 20 is driven to displace the main valve 18, and the fluid at the inlet 12 flows through the valve port 14 to the outlet 16. This automatically operates so that the valve port 14 opens when the fluid pressure on the secondary side decreases and closes when it increases.

A cylindrical partition member 46 is attached below the valve port 14,
An annular space 48 is formed between the main body 10 surrounding the annular space 48, and the upper part of the annular space 48 is passed through a cone-shaped screen 50 to the inlet 12.
The lower part communicates with the upper part of the drain valve chamber 52. Further, the upper part of the drain valve chamber 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 shaken 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 in 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 5B, and automatically removes water accumulated in the drain valve chamber 52.

Problems to be Solved by the Invention In all existing pressure reducing valves, including the conventional pressure reducing valve having the structure described above, there is a chattering phenomenon that causes significant vibration and noise, which cannot be eliminated. This may occur when the pressure is set at an appropriate flow rate and the operation is normal, but when the load on the secondary side decreases and the flow rate decreases, or when the set pressure is lower than the secondary pressure. It also occurs when the next pressure) is small, that is, when the decompression ratio is large.

As mentioned above, in general, the smaller the flow rate of a pressure reducing valve, the lower the
That is, when the main valve 18 attempts to maintain a slightly open state, unstable operation phenomena such as chattering occur. This is main valve 18
When the main valve 18 is operating for a certain period of time, even if its opening changes slightly, the flow rate is large and the outlet pressure does not change much. In this state, a slight change in the pressure on the secondary side is transmitted through the secondary pressure detection passage 34, and the pilot valve 26 opens.

However, at that time, the valve opens to a level greater than the pressure drop and then returns to the valve closing direction repeatedly, exhibiting a vibration state, and approximately following this, the piston chamber 20a in the upper space of the piston 20
One of the causes is considered to be the activation of the pilot valve 26, which causes a sudden pressure change and causes the main valve 18 to also exhibit an activated state. As the main valve 18 opens and closes, the secondary pressure pulsates, and the vibration acts again on the lower surface of the diaphragm via the secondary pressure detection passage 34, causing the pilot valve 26 to open and close. This process occurs at an accelerated rate, creating a state of large vibration.

In addition, the vibration is caused by the sudden opening of the main valve 18, which causes a jet of steam heading toward the secondary side to act on the lower surface of the piston 20, rapidly pushing up the piston 20 and colliding with its upper wall, resulting in the rise of the piston 20. It is thought that this is because the main valve 18- cannot follow the piston 20 and collides with it when the piston 20 descends again. Re-contact is shocking, and such movement of the main valve 18 and piston 20 may cause damage to the shaft portion 20b of the piston 20, or
There is a problem that the valve seat of the main valve 18 may be damaged. Damage to these members may make it impossible to set the outlet pressure, or
Its life as a pressure reducing valve will be shortened.

Here, one possible way to eliminate this chattering is to reduce the opening area of the secondary pressure detection passage.
If this passage is narrowed down, there is a problem in that the responsiveness during pressure setting becomes worse.

Therefore, the technical problem of the present invention is to provide a pressure reducing valve that has good responsiveness during pressure setting and does not cause chattering even when the flow rate decreases.

Technical 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 a pressure setting spring to the upper surface of the diaphragm, and apply secondary pressure to the lower surface of the diaphragm. By controlling the flow rate by opening and closing the valve port provided between the inlet connected to the primary side and the outlet connected to the secondary side by the balance of both forces, the secondary side pressure is reduced. In a pressure reducing valve that maintains the pressure at the set pressure, a throttle valve is placed in the secondary pressure detection passage that introduces the secondary pressure to the bottom surface of the diaphragm to reduce the opening area of the passage, and the pressure is maintained at the set pressure. When the elastic force of the pressure setting spring is being adjusted to change the pressure setting spring, the throttle valve is fully opened, and when the secondary pressure is stabilized, the throttle valve is narrowed down to reduce the opening area of the secondary pressure detection passage. It is characterized by the following.

When setting the working pressure, the secondary pressure detection passage is fully open, and changes in the secondary pressure are accurately introduced to the lower surface of the diaphragm without delay, and the secondary pressure is set. - Once the secondary side pressure is stabilized, it does not fluctuate greatly, so the passage 34 does not need to have such a large area, and there is no problem even if it is narrowed down.

Therefore, even if the flow rate decreases and the set pressure becomes unstable, the secondary pressure detection passage is constricted, so the pressure fluctuation is difficult to be transmitted to the bottom surface of the diaphragm, and the diaphragm, pilot valve, piston, and main valve are then photographed. does not become a state.

Example An example showing a specific example of the above technical means will be described.

The following embodiment is an improvement of the secondary pressure detection passage section of a conventional pressure reducing valve, and parts corresponding to those in FIG. 3 are given the same reference numerals, and a detailed explanation of the pressure reducing valve will be omitted.

First Embodiment (See Figures 1 and 3) A communication hole 72 that divides the secondary pressure detection passage 34 of the pilot body 70 of the pressure reducing valve into two is opened. A holder 74 having an insertion hole 74a in the center of the side wall of the pilot body 70
is attached with screws 76, and its insertion hole 74a and communication hole 72
The throttle valve 78 is slidably inserted into. Holder 74
The insertion hole 74a has a female thread, and the base of the throttle valve 78 has a male thread.By screwing them together, the throttle valve 78 is displaced within the communication hole 72, and the secondary pressure detection passage 34
The opening area of the opening 35 is changed. Reference number 80.8
1 is a sealing member.

The action is as follows. When starting the steam-using equipment or changing the set pressure, the throttle valve 78 is moved back to fully open the opening 35, so that the pressure can be set accurately without delay.

Next, when the secondary pressure becomes stable, operate the throttle valve 78 to
2 and narrow down the opening area of the opening 35 with a small comb. Therefore, even if the flow rate decreases and the set pressure becomes unstable, the transmission of the pressure fluctuation to the lower surface of the diaphragm 28 is reduced by the constricted portion of the opening 35. As a result, the diaphragm 28 is no longer activated, and the pilot valve 26, piston 20, and main valve 18 are no longer activated.

Second Embodiment (See Figure 2.3) In the first embodiment, a person manually adjusted the throttle valve, but in this embodiment, the throttle valve is adjusted automatically.

A throttle passage 72 that divides the secondary pressure detection passage 34 of the pilot body 70 of the pressure reducing valve into two is opened. Then, the solenoid valve 90 is attached to the side wall of the pilot body 70 with screws 92, and the valve shaft 94 of the solenoid valve 90 is slidably inserted into the communication hole 72.
By displacing the valve shaft 94, the opening area of the opening 35 is changed.

The solenoid valve 90 is operated by a switch 96. Reference number 80
- 81 is a sealing member.

The operation is almost the same as in the first embodiment, and when setting the pressure, the switch 96 is closed, the valve shaft 94 is retracted, and the opening 35 is fully opened. When the pressure becomes stable, the switch is opened to allow the valve shaft 94 to protrude and narrow the passage 72.

Although a solenoid valve is used in this embodiment, an electric valve may be used as another means.

Third Embodiment (not shown) Another pressure reducing valve is a self-IFl setting pressure reducing valve. In this system, the pressure adjusting screw of the pressure reducing valve described above is moved forward and backward by an actuator, for example, an electric motor, and the set pressure of the pressure reducing valve is changed by remote control. The technique of the second embodiment can also be combined with this pressure reducing valve. In other words, when changing the set pressure, the electric motor operates, and even if this operation is detected mechanically or electrically and the solenoid valve installed in the secondary pressure detection passage is operated based on this signal, the purpose is achieved. can.

Effects of the Invention As described above, according to the present application, chattering is eliminated, so there is no imaging, and each member is not damaged, and the pressure reducing valve can continue to maintain the set pressure in a stable state.

In addition, by eliminating chattering, it becomes possible to set pressure in a minute flow rate range that could not be set conventionally, and the range of use as a pressure reducing valve is widened.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of an embodiment of the present invention, FIG. 2 is a sectional view of a main part of another embodiment, and FIG. 3 is a sectional view of a conventional pressure reducing valve. 1: Pressure reducing valve part 2: Steam water separator part 3: Drain valve part 10: Main body 12: Inlet 14: Valve port 16: Outlet 20: Piston 26: Pilot valve 2B-Diaphragm 34: Secondary pressure detection passage 7
2: Communication hole 78: Throttle valve 90: Solenoid valve 94: Valve stem

Claims (1)

[Claims] 1. The elastic force of the pressure setting spring is applied to the upper surface of the diaphragm, and the secondary side pressure is applied to the lower surface of the diaphragm, and the balance between the two forces causes the inlet connected to the primary side and the outlet connected to the secondary side to In a pressure reducing valve, the outlet pressure is maintained at a set pressure by controlling the flow rate by opening and closing the valve port provided between the two. A throttle valve is arranged in the next pressure detection passage to reduce the frontage area of the passage, and when the elastic force of the pressure setting spring is being adjusted to change the set pressure, the throttle valve is fully opened. 1. A pressure reducing valve characterized in that when the downstream pressure becomes stable, the throttle valve is throttled down to reduce the opening area of the secondary pressure detection passage.