JPH02186413A - Reducing valve - Google Patents

Abstract

PURPOSE:To prevent the generation of a chattering phenomenon in a used condition at a large decompression ratio by providing a pressure operation member at a pilot system which drives a pilot valve at a reducing valve, applying primary side pressure on one surface of the member, closing the pilot valve, and applying secondary side pressure on the other surface of the member. CONSTITUTION:When set pressure is substantially smaller than the primary pressure, a pilot valve 26 is closed, a main valve 18 is closed as well, and when the secondary side pressure is decreased lower than the set pressure, a pressure setting spring 44 exceeds the pressure applying on the underside of a diaphragm 28, drops the diaphragm 28, and opens the valve 26. At such a time a pressure plate 88 upward pulls a pilot stem 72 by the pressure corresponding to the difference between the primary side pressure and the secondary side pressure, the valve 26 is pushed to a pilot seat 82 by force more than the force of a pilot spring 27, and the quantity of fluid on the primary side is restricted, a shock in a piston chamber 20a is reduced, and the chattering can be prevented.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention applies to piping systems for steam, compressed air, etc.
This relates to a pressure reducing valve that reduces fluid pressure on the secondary side and maintains it at a constant set pressure.

<Prior Art> A conventional pressure reducing valve is as shown in FIG. 2, and consists of a pressure reducing valve section 1, a steam/moisture preparator section 2, and a drain valve section 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 main valve 18 is disposed at the inlet side end of the valve port 4 while being elastically biased by a main valve spring 19.

The piston 20 is slidably disposed within the cylinder 22, and the piston rod 20b is brought into contact with the central protrusion 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 through a substantially hemispherical surface, and a communication port 20C is opened to communicate the upper surface and the lower surface. A pilot valve 26 is disposed in a primary pressure passage 24 that communicates the inlet 12 with the upper space of the piston 20, that is, the piston chamber 20a. diaphragm 28
is attached by sandwiching its outer peripheral edge between 7 flange 30 and 32. The space below the diaphragm 28 is the secondary pressure detection passage 3
4 to the outlet 16. The head end surface of the valve stem 36 of the pilot valve 26 abuts against the central lower surface of the diaphragm 28 . Further, the pilot valve 26 is biased in the valve closing direction by a pilot spring 27.

A pressure setting coil spring 40 is brought into contact with the upper surface of the diaphragm 28 via a spring seat 38. Adjustment screw 448
It is attached by screwing 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 piston side fluid pressure horn is
0a, 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 when the fluid pressure on the secondary side decreases, the valve port 14 opens and closes when the upper wall reaches the upper wall.

A cylindrical partition member 46@ is installed 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 . In the annular space 48, a swirling vane 54 consisting of an inclined wall is arranged.

Therefore, when the fluid in the inlet 12 passes through the annular space 48 through the valve port 14, 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, the spherical valve 7a-toro 0 is housed in a freely displaceable manner. A ventilation hole 64 is opened in the upper part of the float cover 62.

Therefore, the valve float 60 (along with the water level in the drain valve chamber 52)
, 7 to open and close the drain valve port 58 and automatically remove 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 with the above-mentioned configuration, a problem that cannot be solved is the problem of unnatural photography and chittering that generates noise. There is. - Occurs when the set pressure (secondary pressure) is smaller than the next pressure, that is, when the pressure reduction ratio is large.

The pressure reduction ratio is, for example, the primary side pressure 'l0K9/c/rt
In this case, the secondary side pressure is reduced to about 2 Kl/ctrt or less, and movable parts such as the main valve 18 and the piston 20 vibrate, causing chattering. This is because when the secondary pressure decreases and the pressure change causes the pilot valve 26 to open via the secondary pressure detection passage 34, even though the main valve 18 is slightly opened, the primary and secondary Due to the large pressure difference between the two sides, the high-pressure primary fluid undergoes volumetric expansion on the secondary side, causing the secondary pressure to rise instantly. Then, the pressure is again transmitted to the pilot valve 26 via the secondary side pressure detection passage 34.
close the valve suddenly. This causes fluid to flow into the piston chamber 20a, causing the piston 20 and the main valve 18 to close quickly.

When the main valve 18 suddenly closes, the pressure on the secondary side also drops rapidly, and the diaphragm 28 is pushed by the pressure setting spring 44 to suddenly open the pilot valve 26. The above process is performed at an accelerated rate to create a large imaging state? do.

In addition, when the main valve 18 suddenly opens, a jet of steam toward the secondary side acts on the lower surface of the piston 2Q, rapidly pushing up the piston 20 and colliding with its upper wall. It is thought that this is because the main valve 18 cannot follow the rise of the piston 20 and collides with the piston 20 when it descends again. Re-contact is shocking, and such operation of the main valve 18 and piston 20 may cause damage to the piston rod 20b or damage to the main valve 18.
This can cause problems such as damage to the valve seat. Damage to these members may make it impossible to set the secondary pressure or shorten the life of the pressure reducing valve.

In order to prevent this zigzag phenomenon from occurring, it is conceivable to open and close the pilot valve 26 and reduce the amount of primary fluid supplied from there to the piston chamber 20a. Although this method is effective when the differential pressure between the next pressure and the set pressure is large, another problem arises in that the fluid characteristics deteriorate when the differential pressure is small.

Therefore, the technical problem of the present invention is to provide a pressure reducing valve that does not cause chattering even when used with a large pressure reduction ratio, and whose flow Φ characteristics do not deteriorate even when used with a small pressure reduction ratio.

<Technical means for solving the problems> The technical means of the present invention taken to solve the above problems are as follows:
In the conventional pressure reducing valve as described above, a pressure responsive member is provided on the pilot stem that drives the pilot valve, and primary pressure is applied to one surface of the pressure responsive member so as to close the pilot valve. A secondary side pressure is applied to the other surface of the responsive member.

<Operation> In this invention, since the pressure responsive member must be configured to change the closing force of the pilot valve approximately in proportion to the pressure difference between the primary side pressure and the secondary side pressure, The flow rate of pressurized fluid introduced into the piston chamber is small when the pressure reduction ratio is large because the pilot valve acts more in the valve closing direction, and when the pressure reduction ratio is small, the pressure difference is small. The amount increases because it does not act much in the direction of closing the pilot valve.

Therefore, in operating conditions where the pressure reduction ratio is high, which is likely to cause chattering, the flow rate from the pilot valve to the piston chamber is reduced, thereby creating a chattering prevention effect, and in operating conditions, where the pressure reduction ratio is low, which is less likely to cause chattering, the flow rate increases. This prevents deterioration of the piston's operational response and prevents deterioration of the flow characteristics of the main valve.

<Example> An example showing a specific example of the above technical means will be described. (
(See Figures 1 and 2) This embodiment is an improved pilot valve part of a conventional pilot-operated pressure reducing valve. Parts corresponding to those in Figure 2 are given the same reference numerals, and details of the pressure reducing valve are shown below. Further explanation will be omitted.

The pilot valve section 70 is composed of a pilot stem 72, a stem kite 74, and a pilot valve 26. A pilot valve seat 8 having a stem guide hole 78 passed through 11 in the center of the stem guide 74 and having a pilot valve port 80 at its lower end.
form 2. In addition, 84 which intersects with the stem guide hole 78
The opening communicates with the piston chamber 20a. The circumferential side of the stem guide 74 is male-threaded, and the pilot body 7
Connect to 4 with screws. The pilot valve 26 is arranged so as to abut the pilot valve seat 82 from below, and is biased in the valve closing direction by a pilot spring 27.

The upper part of the stem guide 74 has a larger diameter than the lower part and forms a cylindrical collar part 86 on the inside. The pilot stem 72 is slidably inserted into the stem guide hole 78 so as to protrude from the cylindrical portion, and a pressure receiving plate 88 is formed on the protruding portion, the uppermost end of which is brought into contact with the lower surface of the diaphragm 28 . Although not shown, the pilot stem 72 and the pilot valve body 26 are screwed together and are integrally formed. An O-ring 90 is interposed on the outer periphery of the pressure receiving plate 88 for airtightness with the cylindrical inner surface, thereby making the cylindrical inner surface movable.

A communication port 94 is passed upward from the primary pressure passage 24 of the pilot body 76, the upper end of which communicates with an annular groove 92 carved in the lower surface of the flange 86, and a through hole 96 is further opened to connect the primary pressure passage 24. pressure fluid is introduced into the lower surface of the pressure receiving plate 88. On the other hand, a secondary pressure detection passage 34 is provided on the upper surface of the acceptance plate 88.
Due to this, secondary pressure is acting.

The action is as follows.

When used with a large pressure reduction ratio, that is, when the set pressure is considerably smaller than the primary pressure, the pilot valve 26 is closed and the main valve 18 is also closed, as shown in the diagram. If the side pressure drops and becomes lower than the set pressure,
The pilot valve 26 opens because the pressure setting spring 44 overcomes the pressure acting on the lower surface of the diaphragm 28 and lowers it. At this time, the pressure receiving plate 88 tries to pull the pilot stem 72 upward with a force corresponding to the pressure difference between the pressure on the primary side and the pressure on the secondary side. That is, the pilot valve body 26 is also pressed against the pilot valve seat 82 with a force greater than the biasing force of the pilot spring 27. Therefore, the fluid on the primary side from the pilot valve 26 is introduced into the piston chamber 20aG with its flow restricted, so that the impact on the piston is much smaller than in the past, and chattering does not occur.

When used with a small pressure reduction ratio, the pilot valve 2
Since the force that closes the valve 6 is almost exclusively the force of the pilot spring 27, when the pilot valve 26 tries to open due to a drop in secondary pressure, the valve opens much more than when the pressure reduction ratio is high and the primary side is closed. Pressure fluid is introduced into the piston chamber 20a.

However, as described above, when the pressure reduction ratio is small, the chattering phenomenon is unlikely to occur, so the chattering phenomenon does not occur in this case as well, and furthermore, deterioration of the meteor characteristics of the main valve 18 is prevented.

Therefore, this pressure reducing valve introduces the primary side pressure fluid into the piston chamber 20a in response to the pressure difference between the primary side pressure and the set pressure in each usage state with different pressure reducing ratios, thereby preventing the occurrence of chattering phenomenon. This can be prevented and also prevent deterioration of flow characteristics.

<Effects of the Invention> As described above, according to the present application, chattering is eliminated, so there is no vibration, and the pressure reducing valve can continue to maintain the set pressure in a stable state without causing damage to each member. Furthermore, by eliminating chattering, it becomes possible to maintain a constant pressure δ2 in the low pressure range, which could not be set conventionally, and the range of use as a pressure reducing valve is widened.

In addition, it is possible to prevent the chattering phenomenon, and at the same time, it is possible to improve the flow rate characteristics, which had deteriorated under usage conditions where the pressure reduction ratio is small, to be close to the ideal flow rate characteristics.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the pilot valve part of the embodiment of the present invention;
The figure is a sectional view of a conventional pressure reducing valve. No. 118 Inlet/outlet piston pilot valve pilot stem stem guide 0b valve port main valve piston rod diaphragm communication port pressure receiving plate

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 opens and closes the main valve port and has a valve-closing spring, and a reduction in secondary side pressure. A pilot valve is provided to open based on the pilot valve, and a piston is provided to open the main valve by introducing primary side pressure fluid into the pressure chamber when the pilot valve opens and moving due to the pressure. A pressure-responsive member is provided in the pilot stem that drives the pilot valve, and a primary side pressure is applied to one surface of the pressure-responsive member so as to close the pilot valve, and the pressure-responsive member A pressure reducing valve characterized in that a secondary side pressure is applied to the other side of the valve.