JP5140400B2 - Valve structure - Google Patents

Description

  The present invention relates to a valve structure. More specifically, the present invention relates to a valve seat structure such as a metal diaphragm type shut-off valve suitable for general industrial use, particularly various fluids used in semiconductor manufacturing equipment, liquid crystal manufacturing equipment, etc., particularly high pressure fluid supply or discharge systems. .

JP-A-8-189574

Currently, metal diaphragm type shut-off valves for high pressure fluids used in semiconductor manufacturing equipment, liquid crystal manufacturing equipment, etc., have a valve seat made of resin, there are a caulking method (FIG. 6) and a seat holder method (FIG. 7). .
A primary side passage 4 and a secondary side passage 5 are formed inside the valve box 3. A mouth 4 a is formed at the inner side end of the primary side passage 4, and a mouth 5 a is formed at the inner side end of the secondary side passage 5.
A valve seat 1 is arranged around the mouth 4a so as to surround the mouth 4a.
In the case of the caulking method, the portion around the mouth 4a of the valve box 3 rises above the height of the mouth 4a, and a groove that opens upward is formed in that portion. The valve seat 1 is caulked and fitted inside the groove.
When the diaphragm 6 contacts the head 1a of the valve seat 1, the primary side passage 4 and the secondary side passage 5 are blocked. When the diaphragm 6 is detached et al of the head 1a seat 1 via the mouth 4a and mouth 5a, a communication with the primary side passage 4a and the secondary side passage 5a.

However, in the case of the caulking method, a minute gap is formed between the resin valve seat 1 and a groove formed in the valve box 3 for inserting it. The gap is called dead space. Atmospheric components at the time of assembly exist in the dead space, and when moisture or oxygen is released into the flow path (primary side passage 4, secondary side passage 5) for some reason, it reacts in the flow path. When a special gas is easily present, the semiconductor manufacturing process is affected, for example, a reaction occurs and a product is generated.
Further, when the resin valve seat 1 is caulked into the groove of the metal valve box 3, the metal is deformed. Therefore, a flaw is left on the metal surface of the caulking portion corresponding to the gas contact portion. Additionally, although the particles are generated from the metal when fitting Te Ca shea main, it is impossible to perform washing. Therefore, it becomes a cause of entraining particles in the film forming raw material.
On the other hand, in the seat holder system shown in FIG. 7, the periphery of the mouth 4a of the valve box 3 is flat, and the valve seat 1 is disposed so as to surround the mouth 4a. The valve seat 1 has a flat bottom surface and has a step between the bottom surface and the head 1a. The holder 2 is a means for fixing the valve seat 1 to a predetermined position of the valve box in a state where the valve seat 1 is disposed in the center. The holder 2 has a step corresponding to the step of the valve seat 1 on the outside. The valve seat 1 is arranged in the center of the valve box 3 and the step of the valve seat 1 and the step of the holder 2 are engaged. The holding part 2 receives a pressing force from above at the peripheral end of the diaphragm and is fixed to the valve box 3, and applies force to the valve seat 1 from the step to fix the valve seat 1 to the valve box 3.
The holder 2 has a plurality of openings 10. A space is formed below the holder 2, and the space 9 communicates with the secondary side passage 5 through the mouth 5 a.
When the diaphragm 6 is detached from the head of the valve seat 1, the primary side passage 4a and the secondary side passage 5a communicate with each other through the port 4a, the opening 10, the space 9, and the port 5a. That is, the valve is opened.

  However, in the case of a seat holder type shut-off valve, the following problem occurs when the diaphragm 6 is in contact with the head of the resin valve seat 1.

  That is, as shown in FIG. 8, when the fluid is a gas having a high pressure and a low molecular weight (for example, He gas), the gas penetrates into the valve seat 1 made of resin. Next, the gas diffuses inside the valve seat 1 and permeates outside the valve seat 1. Therefore, as shown by the arrow in FIG. 8, the downstream pressure gradually increases even when the valve is closed. Even when the thickness of the valve seat 1 (thickness in the lateral direction in the drawing) is large, the same phenomenon occurs even though it takes time until permeation occurs.

  Further, a drive device that generates a sufficient valve seat pressing force F that can close the valve seat even when the maximum operating pressure is sealed in the valve must be provided. Even when the internal pressure of the valve is low (for example, atmospheric pressure), a sufficient valve seat pressing force F is applied to the valve seat so that the valve seat can be closed. In this case, all the valve seat pressing force is applied to the valve seat. Then, the pressing force applied to the valve seat becomes excessive. For this reason, the resin valve seat buckles, which causes a decrease in flow rate and valve seat leakage.

  An object of the present invention is to provide a valve structure in which the downstream pressure does not increase in a closed state.

  An object of the present invention is to provide a valve seat structure that does not buckle even if an excessive pressing force is applied, and that does not cause a decrease in flow rate or leakage of the valve seat.

The invention according to claim 1 is a resin valve seat, a diaphragm that contacts and separates from the head of the valve seat, a metal valve seat reinforcing member that covers the valve seat, the valve seat, and the valve seat A valve structure comprising a valve seat holder for pressing and holding the reinforcing member against the valve box, and the valve seat is surrounded by the valve seat reinforcing member and the valve seat holder except for the valve seat portion in contact with the metal diaphragm This is a valve seat structure configured .
The invention according to claim 2, the valve seat reinforcement member has a groove, a valve seat structure according to claim 1 Symbol mounting the valve seat in the groove is fitted.
The invention according to claim 3 is the valve structure according to claim 2 , wherein the valve seat reinforcing member has a gasket structure at a contact portion between the bottom surface and the valve box.
The invention according to claim 4 is the valve structure according to claim 2 , wherein gas does not enter between the bottom of the groove of the valve seat reinforcing member and the bottom surface of the valve seat.
The invention according to claim 5 is the valve structure according to claim 4 , wherein the valve seat is fitted into the groove such that distortion occurs in the bottom surface of the valve seat.

The invention according to claim 6 is the valve structure according to claim 5 , wherein a slope is provided at the bottom of the groove, and a valve seat having a flat bottom surface is fitted into the groove.

The invention according to claim 7 is the valve structure according to claim 5 , wherein the bottom of the groove is flattened, an inclined or raised portion is provided on the bottom surface of the valve seat, and the valve seat is fitted into the groove.

(Claim 1)
Since the valve seat is surrounded by the valve seat reinforcement member and the valve seat holder except for the valve seat portion that contacts the metal diaphragm, the gas does not contact the valve seat, and the gas can be surely penetrated and permeated. It becomes possible to prevent.

  Therefore, even in the case of a gas having a low molecular weight, it is possible to prevent an increase in pressure on the downstream side when the valve is closed.

  Further, since the valve seat reinforcing member bears a strong valve seat pressing force by the diaphragm, the valve seat is less likely to buckle.

It is possible to provide a valve structure (for example, a structure of a metal diaphragm type shut-off valve) that has a minimum dead space, does not impair cleanliness during assembly, and can be easily repaired or replaced.
(Claim 2 )
The valve seat reinforcing member has a groove, and when the valve seat is fitted in the groove, the portion other than the valve seat portion contacting the metal diaphragm is isolated from the gas to prevent the gas from entering the valve seat. Can do.
In addition, the entire valve seat reinforcing member bears the pressing force of the diaphragm, which is effective in preventing the occurrence of buckling.
(Claim 3 )
When a contact portion between the bottom surface of the valve seat reinforcing member and the valve box has a gasket structure, leakage through the bottom surface of the valve seat reinforcing member between the primary side passage and the secondary side passage is prevented. Can do.
(Claim 4 )
Gas is prevented from entering between the bottom of the groove of the valve seat reinforcing member and the bottom surface of the valve seat, so that when the high pressure gas flows into the bottom of the valve seat and then the internal pressure of the valve decreases, the valve seat It is possible to prevent the valve seat from being damaged due to a pressure difference between the bottom and the top of the tube and the shearing force.
(Claim 5 )
When the valve seat is fitted in the groove so that the bottom surface of the valve seat is distorted, a region where the stress is high between the bottom inner diameter side of the groove portion of the valve seat reinforcing member and the valve seat pressing portion of the valve seat holder It is possible to hold the valve seat by distributing it. This increases the close contact between the bottom inner diameter side of the groove portion of the valve seat reinforcing member and the valve seat bottom portion, so that high pressure gas can be prevented from flowing into the valve seat bottom portion, and the ideal valve seat holding state can be achieved. realizable. As a result, when a high-pressure gas flows into the valve seat bottom, and then the internal pressure of the valve decreases, a pressure difference is generated between the bottom and top of the valve seat, and the valve seat can be prevented from being damaged by the shearing force.
(Claim 6 )
When an inclination is provided at the bottom of the groove and a valve seat having a flat bottom surface is fitted into the groove, the bottom surface of the valve seat that hits the inclined surface is compressed, and the portion receives compressive stress. Adhesion between the bottom of the groove and the bottom surface of the valve seat is enhanced, and gas inflow between the valve seat reinforcing member and the valve seat can be prevented.
(Claim 7 )
Even when the bottom of the groove is made flat and an inclined or raised portion is provided on the bottom surface of the valve seat, the same effect as in the case of claim 6 is produced.
The inclination is preferably an inclination that rises toward the center of the mouth 4a of the primary passage 4. Accordingly, it is possible to form a sealing surface having high sealing performance between the inner diameter side surface of the valve seat and the groove side surface of the inner diameter side wall of the valve seat reinforcing member.

  1 and 2 show a valve structure according to an embodiment of the present invention.

The valve structure of this example is made of a resin valve seat 1, a diaphragm 6 that contacts and separates from the head 1a of the valve seat 1, and a metal valve seat reinforcement that covers the inner surface, the outer surface, and the bottom surface of the valve seat 1. The member 7 includes a valve seat holder 2 for holding the valve seat 1 and the valve seat reinforcing member 7 in the valve box 3.

This will be described in more detail below.
The valve seat 1 in this example is made of resin. As the resin, PCTFE (ethylene trifluoride chloride), PBI (polybenzimidazole), PFA (Arfluoroalkoxylate) and other resins are used. This is more effective than the present invention when using a resin having higher gas permeability.
The valve seat 1 has a head 1a on which the diaphragm 6 abuts and is detached. The shape of the valve seat 1 is not particularly limited as long as it can be fitted in the groove of the valve seat reinforcing member 7. However, in order to fix to the valve box 3 with the holder 2, the step part 1d is provided in the part lowered from the head part 1a. The stepped portion 1d is fixed to the valve box 3 by being pressed against the holder 2 and pressed.
Further, when the valve seat 1 is fitted in the groove of the valve seat reinforcing member 7, the head 1 a is made higher than the height of the wall on the inner diameter side of the valve seat reinforcing member 7. Further, the height of the step 1d is higher than the height of the wall on the outer diameter side of the valve seat reinforcing member 7.
After fitting the valve seat 1 in the groove, the holder 2 is pressed against the surface of the step 1d. The step surface of the valve seat 1 is compressed to the height of the outer diameter side wall of the valve seat reinforcing member 7, and the pressing force is the top surface of the step 1 d surface of the valve seat 1 and the outer diameter side wall of the valve seat reinforcing member 7. And bear. Therefore, even if a valve seat having a large aspect ratio is used, buckling is less likely to occur.
When the valve seat 1 is fitted into the groove of the valve seat reinforcing member 7 and pressed by the holder 2, the valve seat 1 is distorted to generate internal stress. In particular, in FIG. 3, the compressive stress is increased in the portion surrounded by ABCD, and each of points A, B, C, and D has high sealing performance.
By adopting the valve seat reinforcing member 7, when the valve is closed, a gas having a small molecular weight can be transmitted only from the vicinity of the valve seat portion in contact with the metal diaphragm on the upper portion of the valve seat, so that the permeation amount can be reduced. In addition, the resin valve seat is less likely to buckle against a strong valve seat pressing force.
The valve seat reinforcement 7 is a metal (including an alloy). A metal having corrosion resistance is preferred. For example, SUS316L, nickel alloy (for example, Hastelloy (registered trademark)), nickel copper alloy (for example, Monel (registered trademark)) is used.
A gasket 7 a is formed on the bottom surface of the valve seat reinforcing member 7. In the present invention, the valve seat reinforcing member 7 is made of metal. Therefore, the contact with the valve box becomes metal, and the sealing performance is not good compared to the case of resin. Therefore, it is preferable to form a gasket on the bottom surface of the valve seat reinforcing member 7 to enhance the city sealing performance.
The shape of the protrusion that becomes the gasket is not particularly limited. The illustrated example cross-section is provided with a collision force Ru triangular der.
As shown in FIG. 3, in the valve seat structure of the present invention, the valve seat is distributed by distributing a high stress area between the bottom inner diameter side of the groove portion of the valve seat reinforcing member and the valve seat pressing portion of the valve seat holder. By holding, the degree of close contact between the bottom inner diameter side of the groove of the valve seat reinforcing member and the valve seat bottom becomes high, so that high-pressure gas can be prevented from flowing into the valve seat bottom, and ideal valve seat retention The state can be realized. As a result, when a high-pressure gas flows into the valve seat bottom, and then the internal pressure of the valve decreases, a pressure difference is generated between the bottom and top of the valve seat, and the valve seat can be prevented from being damaged by the shearing force. FIG. 4 shows an example of a combination of a valve seat shape and a valve seat reinforcing member shape for obtaining an ideal stress distribution in the valve seat.
In FIG. 4A, the bottom of the groove of the valve seat reinforcing member 7 is inclined upward from the center thereof. The bottom surface of the valve seat 4 is flat.
In FIG.4 (b), the bottom part of the groove | channel of the valve seat reinforcement member 7 inclines upwards over the whole. The bottom surface of the valve seat 4 is flat.
In FIG.4 (c), the bottom part of the groove | channel of the valve seat reinforcement member 7 is flat. The bottom surface of the valve seat 4 is inclined downward.
In FIG.4 (d), the bottom part of the groove | channel of the valve seat reinforcement member 7 is flat. The bottom surface of the valve seat 4 has a bulge at the inner diameter side, and the other part is flat.
A combination of the bottom shape of the valve seat 1 and the groove shape of the valve seat reinforcing member 7 has a structure having an internal stress distribution as shown in FIG. 3, and a structure with high sealing performance can be obtained.

FIG. 5 shows an example in which the permeation amount of the valve seat of high pressure helium is measured. In this example, high pressure helium was connected upstream of the valve, and a helium leak detector was connected downstream of the valve, and the amount of helium permeated was measured while the valve was closed. The helium pressure at this time was 14 MPaG. Although the valve diameter of the valve seat structure of the present invention used for measurement is twice the valve diameter of the caulking type valve seat structure used for comparison, the high-pressure helium permeation amount of the valve seat structure of the present invention is the caulking type. The result was less than that of the valve seat structure.
An example of 14MPaG, but the pressure rise is not observed in the downstream in the more.

It is sectional drawing of the valve | bulb which concerns on Example 1 of this invention. It is an enlarged view of the valve seat vicinity of FIG. It is an expanded sectional view of the valve seat structure concerning Example 1 of the present invention. It is sectional drawing which shows the combination of the valve seat and valve seat holder which concern on the modification of this invention. It is a graph which shows the leak characteristic of the valve seat structure which concerns on the Example of this invention. It is sectional drawing of the valve seat structure which concerns on a prior art example. It is sectional drawing of the valve seat structure which concerns on another prior art example. FIG. 8 is an enlarged view of FIG. 7.

Explanation of symbols

1 Valve seat 1a head
1d Step 2 Holder 2s Stopper 3 Valve box 4 Primary side passage 4a Port 4b Port 5 Secondary side passage 5a Port 5b Port 6 Diaphragm 7 Reinforcing member 7a Gasket 9 Space 10 Opening

Claims (7)

A resin valve seat, a diaphragm that comes into contact with and disengages from the head of the valve seat, a metal valve seat reinforcement member that covers the valve seat, and the valve seat and the valve seat reinforcement member are pressed against the valve box A valve structure comprising a valve seat holder for holding
A valve seat structure configured such that the valve seat is surrounded by a valve seat reinforcing member and a valve seat holder except for the valve seat portion in contact with the metal diaphragm . Valve seat reinforcement member has a groove, the valve seat structure according to claim 1 Symbol mounting the valve seat in the groove is fitted. The valve structure according to claim 2, wherein the valve seat reinforcing member has a gasket structure at a contact portion between a bottom surface and the valve box. The valve structure according to claim 2 , wherein gas does not enter between a bottom portion of the groove of the valve seat reinforcing member and a bottom surface of the valve seat. The valve structure according to claim 4 , wherein the valve seat is fitted into the groove such that distortion occurs in the bottom surface of the valve seat. 6. The valve structure according to claim 5, wherein a slope is provided at the bottom of the groove, and a valve seat having a flat bottom surface is fitted into the groove. 6. The valve structure according to claim 5, wherein the bottom of the groove is flattened, an inclined or raised portion is provided on the bottom surface of the valve seat, and the valve seat is fitted into the groove.

Images