JPS63172315A - Pressure reducing valve - Google Patents

Abstract

PURPOSE:To prevent the occurrence of chattering despite a pressure reduction ratio is large by using a bellows which is compressed by the rise of pressure in a pressure room when a primary side pressure fluid is led into the pressure room with opening of a pilot valve. CONSTITUTION:A 1st bellows 31 is compressed by the rise of pressure in a pressure room 34 when a primary side pressure fluid is led into the room 34 with opening of a pilot valve 4. Thus the liquid in the bellows 31 expands a 2nd bellows 32 through a small hole 35 and opens a main valve 3. When the difference is large between the primary side pressure and the secondary side pressure, the primary side fluid flows suddenly into the room 34 via the valve 4. In such a case, a damper function works owing to the hole 35 formed between both bellows 31 and 32 so that the bellows 32 has a slow expanding action. As a result, the valve 3 is also gradually opened and closed, therefore no chattering phenomenon occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention mainly relates to a pressure reducing valve for steam, and more particularly to an improvement in a pressure-responsive mechanism for opening and closing the main valve.

<Prior art> As shown in Fig. 2, in a conventional pressure reducing valve, high pressure steam supplied from the primary side port 1 causes the main valve 3 to move downward due to a decrease in pressure on the secondary side connected to the outlet 2. The flow is caused to flow to the secondary side by being moved and opened. The main valve 3 is opened by the lowering of the piston 7, which is controlled by the pilot valve 4 in the upper part of the figure, the pressure setting spring 6, etc. that acts on the pilot valve 4 via the diaphragm 5, and the piston 7 is opened. It closes by rising.

This opening/closing operation is performed to keep the pressure on the secondary side constant, and the outline thereof is as follows. When the pressure on the secondary side is low, the decrease in the secondary pressure acting on the lower surface of the diaphragm 5 through the passage 8 causes the pilot valve 4 to
Opens due to the pressing force. A part of the high-pressure steam at the inlet l is led to the valve chamber of the pilot valve 4 through the passage 9, so when the pilot valve 4 is opened, this high-pressure steam passes through the pilot valve 4 and the passage 37 to the upper part of the piston 7. The main valve 3 is guided into the space and moved downward against the acting force of the piston 7 and the spring 10 to open. When the main valve 3 is opened, high pressure steam flows from the inlet 1 to the outlet 2. When the pressure on the secondary side increases and reaches the set pressure, the spring 6 is pushed up by the pressure on the secondary side acting on the lower surface of the diaphragm 5, so the pilot valve 4 is closed by the action of the spring 11. and piston 7
The high-pressure steam is gradually discharged to the secondary side through the pore 12 provided in the high-pressure steam piston 7 in the upper space of the cylinder, and the piston 7 rises together with the main valve 3 under the action of the spring 10, and the main valve 3 closes.

<Problems to be Solved by the Invention> The conventional pressure reducing valve having the above-described structure causes a significant chattering phenomenon when the set pressure (secondary pressure) is small compared to the negative pressure, that is, when the pressure reducing ratio is large. The pressure reduction ratio is, for example, primary pressure 10 kg/c2, secondary pressure 2 kg/c
This is the case when the pressure is reduced to cm'< 1, and the main valve causes a chattering phenomenon each time it operates. This chattering phenomenon occurs when the pilot valve opens due to a drop in the pressure on the secondary side, and then repeats the state in which the valve opens and then returns to the valve closing direction as the pressure drops, creating a vibration state. Approximately in accordance with this, a sudden pressure fluctuation occurs in the upper space of the piston 7, and the main valve also exhibits a vibrating state. According to experiments, in the pressure reducing valve shown in Fig. 2, when the spring 6 side is gradually lowered from not in contact with the diaphragm 5 to contacting it, and then further lowered, the pilot valve 4 opens or the primary side When the pressure on the secondary side is toKg/C112 and the pressure on the secondary side is atmospheric pressure, that is, at the time of starting, the primary side steam pressure passes through the pilot valve 4 and suddenly increases to the −L space of the piston 7. It was confirmed that the piston 7 and the main valve 3 repeatedly opened and closed rapidly due to the inflow into the main valve 3, and each time, the contact between the piston 7 and the main valve 3 was momentarily separated and they came into contact again. This is because when the main valve 3 suddenly opens, a jet of steam toward the secondary side acts on the lower surface of the piston 7 and rapidly pushes the piston 7 up, making it impossible for the main valve 3 to follow the rise of the piston 7. it is conceivable that. Re-contact is shocking, and such movement of the main valve 3 and piston 7 may cause problems such as bending or breakage of the shaft portion of the piston 7 and damage to the main valve seat. Also, the set pressure of the spring 6 is I Kg/cta2.2 Kg/c
m2.3 Kg/cm2. ...and as you raise it,
In other words, if you reduce the pressure reduction ratio, 3 Kg/c+s
It was also confirmed that the chattering phenomenon hardly occurs from 2 (leprosy).In addition, the secondary pressure is changed from 2 to 8 by the spring 6.
When the distance is set to 70 m2, the above-mentioned main valve 3 and piston 7 rarely come out of contact with each other, but the chattering phenomenon of the main valve 3 still occurs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a pressure reducing valve equipped with a pressure response mechanism that does not cause chattering even when the pressure reducing ratio is high.

<Means for Solving the Problems> The means of the present invention is provided to open and close the main valve hole provided between the inlet connected to the primary side and the outlet connected to the secondary side. A main valve having an action spring, a pilot valve provided to open based on the pressure difference between the primary side pressure and the secondary side pressure, and a primary side pressure fluid so as to be introduced by opening the pilot valve. a pressure chamber provided in the pressure chamber and communicating with the outlet side through a pore; a first rosette provided in the pressure chamber and containing a liquid;
A second bellows is provided in a secondary action area so as to communicate with the inside of the bellows through a small hole and to open the main valve against the valve closing action spring by the extension action. be.

<According to the above means, when the primary side pressure fluid is introduced into the pressure chamber by opening the pilot valve, the first bellows is compressed by the pressure increase in the pressure chamber, so that the liquid in the first bellows is compressed. is sent through the small hole into the second bellows, causing the second rose in the secondary action area to expand. This extension action causes the main valve to open. When the pressure difference between the primary side pressure and the secondary side pressure is large, the primary side pressure fluid introduced into the pressure chamber via the pilot valve will suddenly flow into the gap between the first bellows and the second bellows. Because the two bellows are in communication through small holes, the liquid sent from the first bellows to the second bellows is compressed, and due to the damper action generated by the resistance, the second bellows expands over a short period of time. Therefore, the main valve also gradually opens, and when the main valve closes, it also gradually closes in substantially the same way. Therefore, no chattering phenomenon occurs.

Note that if the pilot valve closes after the main valve opens, the primary pressure fluid will be sealed in the pressure chamber, or the pressure chamber will gradually reach the secondary pressure due to the presence of pores. The bellows shortens and the main valve closes. Therefore, the main valve will not be locked in an open state.

<Example> FIG. 1 shows an example. In the figures, parts that are equivalent to those shown in FIG. 2 are designated by the same reference numerals, and their explanations will be omitted. The main difference from the pressure reducing valve in FIG. 2 is that the piston 7 is replaced by a first bellows 31. The second bellows 32 is provided.

In order to provide the first and second bellows 31, 32, a partition wall 33 is provided which divides the upper space of the main valve 3 into upper and lower sections.

The first and second bellows 31, 32 have approximately the same size, have one end open, and as shown in the figure, the open end is connected to the surface of the partition wall 33, respectively. The first bellows 31 is connected to the upper surface of the partition wall 33, is formed above the partition wall 33, and is arranged within the pressure chamber 34 with a margin. The second hemlock 32 is connected to the lower surface of the partition wall 33, and is arranged in a space (secondary pressure acting castle) formed on the lower side of the partition wall 33 that communicates with the outlet 2, and its lower end surface is connected to the main valve 33. It is in contact with a shaft portion 3a that protrudes upward from the center. The first bellows 31 and the second bellows 32 communicate with each other through a small hole 35 formed in the partition wall 33, and oil 36 is sealed inside the small hole 35.

The inside of the pressure chamber 34 is connected to the inlet l side via a passage 37, a pilot valve 4, and a passage 9. In addition, the pressure chamber 34
communicates with the passageway 8 via the pore 38. In the figure, 39
is a main valve hole, and 40 is a screen.

Note that the portion below the main valve 3 in the figure is a steam trap portion, and is not directly related to the present invention, so a description thereof will be omitted.

This pressure reducing valve does not cause the chatter link phenomenon even when used at a set pressure where the pressure reduction ratio of the steam pressure on the secondary side connected to the outlet 2 is large relative to the steam pressure on the primary side connected to the inlet 1. As described above, when the pressure on the secondary side decreases, the pilot valve 4 opens and the steam on the primary side is introduced from the passage 9 through the pilot valve 4 and the passage 37 into the pressure chamber 34. Even if the inflow state at this time is sudden, the first bellows 31 is compressed and the oil inside passes through the small hole 35 when flowing into the second bellows 32, so there is a damping effect and the pilot valve 4 vibrates. Even if the condition occurs, the second bellows 3
The valve opening force transmitted to the main valve 3 via the main valve 2 does not exhibit a vibration state, and the jet force ejected from the main valve hole 39 when the main valve 3 opens acts on the second bellows 32. Even when the second bellows 32 is compressed, there is a damping effect, and the lower end of the second bellows 32 does not come out of contact with the shaft portion 3a of the main valve 3.

Therefore, the main valve 3 always opens and closes smoothly, no chattering phenomenon occurs, and no damage occurs to the main valve 3, its valve seat, the shaft portion 3a, the contact surface of the shaft portion 3a of the second bellows 32, etc. Also,
The stability of the pressure on the secondary side is also good.

<Effects of the Invention> According to the present invention, it is possible to provide a pressure reducing valve that does not cause chattering even when the pressure reduction ratio is large, always operates smoothly, and has good stability of the secondary side pressure.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view of one embodiment of the present invention, and FIG. 2 is a longitudinal sectional front view of a conventional pressure reducing valve. l...Inlet, 2...Outlet, 3...Main valve, 4
...Pilot valve. 5...Diaphragm, 6...
... Spring (pressure setting spring), 10 ... Valve closing spring, 31 ... First diaphragm, 32 ... Second
Diaphragm, 34...pressure chamber, 35...small hole, 36...oil (liquid), 38...pore.

Claims (1)

[Claims] (1) A main valve provided between an inlet connected to the primary side and an outlet connected to the secondary side, which is provided to open and close the main valve hole and has a valve-closing spring; a pilot valve that is provided to open when the pilot valve opens; a pressure chamber that is provided so that the primary side pressure fluid is introduced when the pilot valve opens, and that communicates with the outlet side through a pore; A first bellows containing liquid is provided in the pressure chamber, and the first bellows containing liquid is communicated with the inside of the first bellows through a small hole, and the main valve is opened by an extension action against the valve closing spring. A pressure reducing valve comprising a second bellows provided in a secondary pressure area so as to open the valve.