JP2024157208A - Diaphragm Valve - Google Patents

Abstract

To provide a diaphragm valve capable of preventing electrostatic charge on a diaphragm caused by flow of controlled flow.SOLUTION: A diaphragm valve of the present invention has an inflow passage 11 into which controlled fluid flows, an outflow passage 12 from which the controlled fluid flows out, a flow rate control passage 13 located between the inflow passage 11 and the outflow passage 12, a valve body 21 arranged in the flow rate control passage 13, and a diaphragm 22 that deforms with the displacement of the valve body 21, where the diaphragm 22 is formed from a resin material, the inflow passage 11 is formed on one side of the diaphragm 22, a conductive sheet 51 is arranged on the other side of the diaphragm 22 in contact with the diaphragm 22, and the conductive sheet 51 is connected to an earth 60.SELECTED DRAWING: Figure 1

Description

The present invention relates to a diaphragm valve in which the diaphragm is made of a resin material.

Semiconductor manufacturing processes continue to scale, increasing the purity of the controlled fluids.
As the purity of the controlled fluid increases, static electricity is more likely to be generated due to friction between the controlled fluid and the flow path of the resin valve.
Static electricity builds up and eventually causes corona discharge, resulting in electrostatic damage to the plastic valve.
Electrostatic breakdown can cause the chemical liquid to leak out of the resin valve, and if the controlled fluid is an organic solvent, it can cause spark discharge, resulting in ignition or fire, which must be taken into consideration.
Among resin valves, diaphragm valves are particularly problematic because they often use a thin fluororesin diaphragm, making them prone to electrostatic damage. Even if antistatic measures are taken outside the diaphragm valve, it is not possible to prevent electrostatic damage inside the diaphragm valve.
In addition, diaphragm valves used in distribution systems for high-purity chemicals cannot be made of metal because they are required to reduce dust generation and achieve high levels of cleanliness.
For example, Patent Document 1 discloses a method of extruding a conductive material integrally onto the non-liquid-contacting outer peripheral portion of a PFA tube, which is a piping material.
Moreover, in Patent Document 2, a conductive member is inserted into a valve box (valve body) and the fluid is earthed to intentionally cause corona discharge, thereby reducing external leakage due to electrostatic breakdown.
Moreover, Patent Document 3 proposes preventing external leakage due to corona discharge at the valve by using a material to which carbon nanotubes are added as the material for the valve box (valve body).

JP 2003-4176 A JP 2007-78019 A JP 2017-75696 A

However, although the method disclosed in Patent Document 1 can reduce the charge on the piping material, it cannot prevent the charge inside the valve, and when the corona critical voltage is exceeded, the fluororesin diaphragm is destroyed due to electrostatic discharge. Thus, even if antistatic measures are taken outside the diaphragm valve, electrostatic destruction cannot be prevented.
Furthermore, in Patent Document 2, materials near the conductive member may be damaged by corona discharge, which may result in the generation of minute dust (particles).
In addition, in the method disclosed in Patent Document 3, external leakage caused by corona discharge can be prevented, but the carbon nanotubes and dispersant are eluted into the controlled fluid, thereby contaminating the controlled fluid.

The present invention aims to provide a diaphragm valve that can prevent the diaphragm from becoming electrically charged due to the flow of the controlled fluid.

The diaphragm valve of the present invention described in claim 1 has an inflow passage 11 through which a controlled fluid flows in, an outflow passage 12 through which the controlled fluid flows out, a flow rate control passage 13 located between the inflow passage 11 and the outflow passage 12, a valve body 21 arranged in the flow rate control passage 13, and a diaphragm 22 that deforms with the displacement of the valve body 21, wherein the diaphragm 22 is formed of a resin material, the inflow passage 11 is formed on one side of the diaphragm 22, and a conductive sheet 51 is arranged on the other side of the diaphragm 22 in contact with the diaphragm 22, and the conductive sheet 51 is connected to earth 60.
The diaphragm valve of the present invention as set forth in claim 2 comprises an inflow passage 11 through which a controlled fluid flows in, an outflow passage 12 through which the controlled fluid flows out, a flow rate control passage 13 located between the inflow passage 11 and the outflow passage 12, a valve body 21 disposed in the flow rate control passage 13, a shaft body 31 that presses the valve body, and a diaphragm 32 that deforms with the displacement of the valve body 21 or the shaft body 31, and the diaphragm 32 comprises a valve body side diaphragm 22 that deforms with the displacement of the valve body 21, and a shaft body side diaphragm 32 that deforms with the displacement of the shaft body 31, a valve body side pressure chamber 14 formed on the other side of the valve body side diaphragm 22, an outlet flow path 12 formed on one side of the shaft body side diaphragm 32, and a shaft body side pressure chamber 15 formed on the other side of the shaft body side diaphragm 32, wherein a conductive sheet 52 is arranged in contact with the valve body side diaphragm 22 or the shaft body side diaphragm 32 on the other side of the valve body side diaphragm 22 or the other side of the shaft body side diaphragm 32, and the conductive sheet 52 is connected to earth 60.
The present invention described in claim 3 is characterized in that, in the diaphragm valve described in claim 2, the valve body side diaphragm 22 has a thin-walled portion 22a connected to the valve body 21 and a fixing portion 22b formed on the outer periphery of the thin-walled portion 22a, and the conductive sheet 51 is arranged on at least the thin-walled portion 22a.
The present invention described in claim 4 is characterized in that, in the diaphragm valve described in claim 2, the shaft side diaphragm 32 has a thick portion 32a connected to the shaft 31, a thin portion 32a formed on the outer periphery of the thick portion 32a, and a fixing portion 32c formed further on the outer periphery of the thin portion 32a, and the conductive sheet 52 is arranged on at least the thin portion 32a.
The present invention described in claim 5 is characterized in that, in the diaphragm valve described in claim 2, the shaft side diaphragm 32 has a thick portion 32a connected to the shaft 31, a thin portion 32a formed on the outer periphery of the thick portion 32a, and a fixed portion 32c formed further on the outer periphery of the thin portion 32a, and the conductive sheet 52 is arranged at least on the thin portion 32a and the fixed portion 32c.
The present invention as set forth in claim 6 is characterized in that in the diaphragm valve as set forth in any one of claims 1 to 5, the diaphragms 22, 32 and the conductive sheets 51, 52 are welded together.
The present invention described in claim 7 is characterized in that, in the diaphragm valve described in any one of claims 1 to 5, small holes 23 are formed in the diaphragms 22, 32, the small holes 23 cause the controlled fluid to come into contact with the conductive sheets 51, 52, and the conductive sheets 51, 52 prevent the controlled fluid from flowing out of the small holes 23.
The present invention described in claim 8 is characterized in that, in the diaphragm valve described in any one of claims 1 to 5, the conductive sheets 51, 52 are resin sheets containing carbon nanoparticles, carbon microcoils, or conductive material.
The present invention as set forth in claim 9 is characterized in that, in the diaphragm valve as set forth in any one of claims 1 to 5, the leakage resistance of the conductive sheet 51 is set to 10 ⁴ Ω to 10 ¹¹ Ω.
A tenth aspect of the present invention is the diaphragm valve according to the seventh aspect, wherein the leakage resistance of the conductive sheet 52 is set to 10 ² Ω to 10 ⁹ Ω.

The diaphragm valve of the present invention uses a conductive sheet to prevent the diaphragm from becoming electrically charged due to the flow of the controlled fluid, eliminating corona discharge caused by charging.

FIG. 1 illustrates a diaphragm valve according to an embodiment of the present invention. FIG. 1 shows a diaphragm valve according to another embodiment of the present invention. FIG. 13 shows a diaphragm valve according to yet another embodiment of the present invention.

The diaphragm valve according to the first embodiment of the present invention has a conductive sheet placed in contact with the other side of the diaphragm and connected to earth. According to this embodiment, the conductive sheet can prevent the diaphragm from becoming electrically charged due to the flow of the controlled fluid, and corona discharge caused by the charging can be eliminated.

The diaphragm valve according to the second embodiment of the present invention has a conductive sheet disposed on the other side of the valve body side diaphragm or the other side of the shaft body side diaphragm in contact with the valve body side diaphragm or the shaft body side diaphragm, and the conductive sheet is connected to earth. According to this embodiment, the conductive sheet can prevent the valve body side diaphragm and the shaft body side diaphragm from being charged by the flow of the controlled fluid, and corona discharge due to charging can be eliminated.

The third embodiment of the present invention is a diaphragm valve according to the second embodiment, in which the valve body side diaphragm has a thin-walled portion connected to the valve body and a fixing portion formed on the outer periphery of the thin-walled portion, and a conductive sheet is disposed at least on the thin-walled portion. According to this embodiment, it is possible to prevent destruction of the thin-walled portion, which is susceptible to damage caused by electrostatic discharge.

The fourth embodiment of the present invention is a diaphragm valve according to the second embodiment, in which the shaft-side diaphragm has a thick portion connected to the shaft, a thin portion formed on the outer periphery of the thick portion, and a fixing portion formed on the outer periphery of the thin portion, and a conductive sheet is disposed on at least the thin portion. According to this embodiment, it is possible to prevent destruction of the thin portion, which is susceptible to damage caused by electrostatic discharge.

The fifth embodiment of the present invention is a diaphragm valve according to the second embodiment, in which the shaft-side diaphragm has a thick portion connected to the shaft, a thin portion formed on the outer periphery of the thick portion, and a fixed portion formed on the outer periphery of the thin portion, and a conductive sheet is disposed at least on the thin portion and the fixed portion. According to this embodiment, it is possible to prevent destruction of the thin portion, which is susceptible to damage caused by electrostatic discharge, and an earth connection can be made at the fixed portion.

The sixth embodiment of the present invention is a diaphragm valve according to the first to fifth embodiments, in which the diaphragm and the conductive sheet are welded together. According to this embodiment, the welding can reliably prevent static electricity.

In the seventh embodiment of the present invention, in the diaphragm valve according to the first to fifth embodiments, small holes are formed in the diaphragm, the controlled fluid comes into contact with the conductive sheet through the small holes, and the conductive sheet prevents the controlled fluid from flowing out through the small holes. According to this embodiment, the controlled fluid comes into contact with the conductive sheet through the small holes, thereby eliminating static electricity, and the conductive sheet also prevents the controlled fluid from flowing out through the small holes.

The eighth embodiment of the present invention is a diaphragm valve according to the first to fifth embodiments, in which the conductive sheet is a resin sheet containing carbon nanoparticles, carbon microcoils, or a conductive material. According to this embodiment, the leakage resistance value of the conductive sheet can be adjusted by changing the compounding ratio of the carbon nanoparticles, carbon microcoils, or conductive material.

A ninth embodiment of the present invention is a diaphragm valve according to the first to fifth embodiments, in which the leakage resistance of the conductive sheet is set to 10 ⁴ Ω to 10 ¹¹ Ω. According to this embodiment, charging can be prevented.

A tenth embodiment of the present invention is such that in the diaphragm valve according to the seventh embodiment, the leakage resistance of the conductive sheet is set to 10 ² Ω to 10 ⁹ Ω. According to this embodiment, static electricity can be easily removed.

A diaphragm valve according to an embodiment of the present invention will now be described.
FIG. 1 shows a diaphragm valve according to this embodiment, with FIG. 1(a) being a side cross-sectional view of the entire diaphragm valve, FIG. 1(b) being a side cross-sectional view of a valve body and a valve body-side diaphragm, and FIG. 1(c) being a plan view of a conductive sheet.

The diaphragm valve of this embodiment has an inlet flow passage 11 through which the controlled fluid flows in, an outlet flow passage 12 through which the controlled fluid flows out, a flow rate control flow passage 13 located between the inlet flow passage 11 and the outlet flow passage 12, a valve body 21 arranged in the flow rate control flow passage 13, a shaft body 31 that presses the valve body 21, a valve body side diaphragm 22 that deforms with the displacement of the valve body 21, and a shaft body side diaphragm 32 that deforms with the displacement of the shaft body 31.
The valve body 21 and the valve body side diaphragm 22 are integrally molded from resin as the valve body side member 20. The shaft body 31 and the shaft body side diaphragm 32 are integrally molded from resin as the shaft body side member 30.
The valve body side member 20 and the shaft body side member 30 can be formed, for example, from PTFE (polytetrafluoroethylene resin), cross-linked PTFE, modified PTFE, PFA (polytetrafluoroethylene-perfluoroalkoxyethylene copolymer resin), or ETFE (polytetrafluoroethylene-ethylene copolymer resin).
Crosslinked PTFE is PTFE made by a reaction that bridges independent molecules together, and is produced by crosslinking methods such as chemical crosslinking and radiation crosslinking. Crosslinked PTFE has abrasion resistance 1,000 times higher than PTFE in terms of sliding properties, and is less likely to damage the material it slides against. Crosslinked PTFE also has high resistance to denaturation and is less likely to deform under load, and is more resistant to denaturation than PTFE at both room temperature and high temperatures. Crosslinked PTFE also has the same processability as PTFE, such as cutting, welding, and pasting, as well as chemical resistance, non-adhesiveness, and electrical properties.
Modified PTFE is a material in which the main chain of PTFE is partially modified, with a small amount of perfluoroalkyl vinyl ether as a comonomer. Modified PTFE has improved flexural and creep properties compared to PTFE, and when used for diaphragms, the flexural life is several times longer.

In the diaphragm valve of this embodiment, an inlet flow passage 11 is formed on one side of the valve body side diaphragm 22, a valve body side pressurized chamber 14 is formed on the other side of the valve body side diaphragm 22, an outlet flow passage 12 is formed on one side of the shaft body side diaphragm 32, and a shaft body side pressurized chamber 15 is formed on the other side of the shaft body side diaphragm 32.
A pressing member 14a that presses the valve body side diaphragm 22 is disposed in the valve body side pressurizing chamber 14. The pressing member 14a is biased by an elastic member 14b toward the valve body side diaphragm 22. A washer 14c is disposed on the end of the elastic member 14b.
Pressurized gas is introduced into the shaft side pressurizing chamber 15, and the shaft side diaphragm 32 is pressed by the introduced pressurized gas.
In this embodiment, the valve body side pressurizing chamber 14 is provided with the elastic member 14b, but it may be biased by a fluid together with the elastic member 14b or in place of the elastic member 14b.
In addition, in this embodiment, pressurized gas is introduced into the shaft side pressurizing chamber 15, but a spring material may be provided together with or instead of the pressurized gas.

The body 40 has a flow passage forming body 41 , a valve body side body 42 , and a shaft body side body 43 .
The flow passage forming body 41 forms an inflow passage 11 , an outflow passage 12 , and a flow rate control passage 13 .
The valve body 42 defines the valve pressurizing chamber 14. The valve pressurizing chamber 14 may be formed with a breathing hole.
The valve body side member 20 is fixed to the flow passage forming body 41 by the valve body side body 42 .
The shaft body side body 43 forms a shaft body side pressurizing chamber 15 and a set air port 15 a communicating with the shaft body side pressurizing chamber 15 .
The shaft side member 30 is fixed to the flow passage forming body 41 by the shaft side body 43 .
The flow passage forming body 41 is made of a fluororesin such as PTFE, crosslinked PTFE, modified PTFE, PFA, etc. The valve body side body 42 and the shaft body side body 43 are made of an engineering plastic such as PP (polypropylene) or PPS (polyphenylene sulfide), or a fluororesin such as PTFE, modified PTFE, PVDF (polyvinylidene fluoride), or ETFE.

The valve body 21 has a connection portion 21a that is connected to the valve body side diaphragm 22, and a contact portion 21b that is pressed by the shaft body 31 and contacts the valve seat 40a.
The connecting portion 21a has a cylindrical shape, one end of which is connected to the valve body side diaphragm 22, and the other end of which is connected to the contact portion 21b. The contact portion 21b has a truncated cone shape.

The valve body side diaphragm 22 has a thin portion 22a connected to the valve body 21 and a fixing portion 22b formed on the outer periphery of the thin portion 22a. The valve body side diaphragm 22 is connected to the connection portion 21a at the center of the thin portion 22a.

The controlled fluid flowing in from the inflow passage 11 passes through the flow rate control passage 13 and flows out from the outflow passage 12 .
The shaft-side diaphragm 32 is deformed by the gas pressure in the shaft-side pressurizing chamber 15 in a direction in which the shaft 31 presses the valve body 21. The set pressure of the shaft-side pressurizing chamber 15 is adjusted by introducing or discharging pressurized gas from the set air port 15a.
The valve element side diaphragm 22 is deformed by the pressing force of the valve element side pressurizing chamber 14 in a direction in which the valve element 21 presses the shaft body 31. The pressing force of the valve element side pressurizing chamber 14 is set by the elastic member 14b.
When a controlled fluid is flowing through the flow control passage 13, the shaft 31 presses against the valve body 21 via the shaft side diaphragm 32, and the valve body 21 presses against the shaft 31 via the valve body side diaphragm 22, so that the valve body 21 and the shaft 31 are in contact with each other.

When the inlet pressure due to the controlled fluid flowing in from the inlet passage 11 increases and becomes higher than the set pressure, the shaft side diaphragm 32 is deformed by the inlet pressure in a direction in which the shaft 31 moves away from the valve body 21 .
As the shaft body 31 is displaced in a direction away from the valve body 21, the valve body 21 is displaced together with the shaft body 31. That is, the valve body 21 is displaced in a direction approaching the valve seat 40a, so that the flow control flow passage 13 is narrowed.
By narrowing the flow rate control flow passage 13, it is possible to prevent an increase in the outflow side pressure caused by the controlled fluid flowing out from the outflow flow passage 12.
On the other hand, when the inlet pressure due to the controlled fluid flowing in from the inlet passage 11 decreases and becomes lower than the set pressure, the shaft-side diaphragm 32 deforms in the direction in which the shaft 31 presses the valve body 21 .
The shaft 31 is displaced in a direction pressing the valve element 21, thereby displacing the valve element 21. That is, the valve element 21 is displaced in a direction away from the valve seat 40a, so that the flow rate control flow passage 13 expands.
By expanding the flow rate control flow passage 13, it is possible to prevent a decrease in the outlet side pressure caused by the controlled fluid flowing out from the outlet flow passage 12.
In this way, in the diaphragm valve according to this embodiment, even if the inlet pressure due to the controlled fluid flowing in from the inlet passage 11 fluctuates, the shaft-side diaphragm 32 deforms, so that the outlet pressure due to the controlled fluid flowing out from the outlet passage 12 can be maintained constant. Note that, in order to displace the valve element 21 together with the shaft 31, the valve element-side diaphragm 22 also deforms with the fluctuation in the inlet pressure.

When the outlet side pressure increases, the shaft side diaphragm 32 is deformed by the outlet side pressure in a direction in which the shaft 31 moves away from the valve body 21 .
As the shaft body 31 is displaced in a direction away from the valve body 21, the valve body 21 is displaced together with the shaft body 31, and the valve body 21 comes into contact with the valve seat 40a.
Even when the valve body 21 is in contact with the valve seat 40 a, if the outflow side pressure is higher than the set pressure, the shaft body 31 moves away from the valve body 21 .
Therefore, even if the outflow pressure increases and the valve body 21 abuts against the valve seat 40a, the valve body 21 is subjected to only the pressing force of the elastic member 14b, and no load due to the outflow pressure is applied to the valve body 21.

A conductive sheet 51 is disposed on the other side of the valve body side diaphragm 22 in contact with the valve body side diaphragm 22 .
The conductive sheet 51 is connected to the earth 60 via an elastic member 14b and a washer 14c made of a metallic material.
In this embodiment, the conductive sheet 51 is disposed on the thin portion 22a. By disposing the conductive sheet 51 on at least the thin portion 22a in this manner, it is possible to prevent damage to the thin portion 22a, which is susceptible to damage caused by electrostatic discharge.
According to this embodiment, by placing the conductive sheet 51 in contact with the valve body side diaphragm 22, the conductive sheet 51 can prevent charging of the valve body side diaphragm 22 and the shaft side diaphragm 32 caused by the flow of the controlled fluid, and corona discharge caused by charging can be eliminated.
Also, as shown in the figure, small holes 23 may be formed in the valve body side diaphragm 22, and the small holes 23 may allow the controlled fluid to come into contact with the conductive sheet 51. The conductive sheet 51 prevents the controlled fluid from flowing out through the small holes 23.
In this manner, the controlled fluid can be brought into contact with the conductive sheet 51 through the small holes 23, thereby eliminating static electricity, and the conductive sheet 51 can also prevent the controlled fluid from flowing out through the small holes 23.

Figure 2 shows a diaphragm valve according to another embodiment of the present invention, where Figure 2(a) is a side cross-sectional view of the entire diaphragm valve, Figure 2(b) is a side cross-sectional view of the shaft side member and conductive sheet, Figure 2(c) is a bottom view of the shaft side member, and Figure 2(d) is a plan view of the conductive sheet. Note that the same functional members as those in Figure 1 are given the same reference numerals and their explanations are omitted.

The shaft body 31 has a cylindrical shape and has a contact portion 31 a that presses the valve body 21 .
The shaft-side diaphragm 32 has a thick portion 32a connected to the shaft 31, a thin portion 32b formed on the outer periphery of the thick portion 32a, and a fixing portion 32c formed on the further outer periphery of the thin portion 32b. The shaft-side diaphragm 32 is connected to the shaft 31 at the center of the thick portion 32a.

A conductive sheet 52 is disposed on the other side of the shaft body side diaphragm 32 in contact with the shaft body side diaphragm 32 .
In addition, the conductive sheet 52 is connected to a ground 60 .
In this embodiment, the conductive sheet 52 is disposed on the thick portion 32a, the thin portion 32b, and the fixed portion 32c.
By disposing the conductive sheet 52 at least on the thin portion 32b in this manner, it is possible to prevent destruction of the thin portion 32b, which is susceptible to damage caused by electrostatic discharge.
Furthermore, by disposing the conductive sheet 52 at least on the thin portion 32b and the fixed portion 32c, it is possible to prevent destruction of the thin portion 32b, which is susceptible to damage caused by electrostatic discharge, and it is also possible to make a connection to earth 60 using the fixed portion 32c.
According to this embodiment, by placing the conductive sheet 52 in contact with the shaft side diaphragm 32, the conductive sheet 52 can prevent charging of the valve body side diaphragm 22 and the shaft side diaphragm 32 caused by the flow of the controlled fluid, and corona discharge caused by charging can be eliminated.
Similarly to the valve body side diaphragm 22, small holes 23 may be formed in the shaft body side diaphragm 32 so that the controlled fluid comes into contact with the conductive sheet 52 through the small holes 23. The conductive sheet 52 prevents the controlled fluid from flowing out through the small holes 23.
In this manner, the small holes 23 allow the controlled fluid to come into contact with the conductive sheet 52, thereby eliminating static electricity, and the conductive sheet 52 can also prevent the controlled fluid from flowing out through the small holes 23.
In addition, in this embodiment, the conductive sheet 51 is arranged in contact with the valve body side diaphragm 22, and the conductive sheet 52 is arranged in contact with the shaft body side diaphragm 32, but it is also possible to not provide the conductive sheet 51 in contact with the valve body side diaphragm 22, and to only have the conductive sheet 52 in contact with the shaft body side diaphragm 32.

FIG. 3 shows a diaphragm valve according to yet another embodiment of the present invention.
FIG. 3 is a cross-sectional view of the diaphragm valve. In the diaphragm valve 1 according to this embodiment, a flow path side body 44 and a drive side body 45 form a body 40 .
The flow path side body 44 has an inlet flow path 11 through which the controlled fluid flows, an outlet flow path 12 through which the controlled fluid flows out, a flow rate control flow path 13 located between the inlet flow path 11 and the outlet flow path 12, a valve body 21 arranged in the flow rate control flow path 13, and a diaphragm 22 that deforms with the displacement of the valve body 21.

The valve body 21 and the valve body side diaphragm 22 are integrally molded from resin as the valve body side member 20 .
The valve body side member 20 can be formed from, for example, PTFE, cross-linked PTFE, modified PTFE, PFA, or ETFE.
Crosslinked PTFE is PTFE made by a reaction that bridges independent molecules together, and is produced by crosslinking methods such as chemical crosslinking and radiation crosslinking. Crosslinked PTFE has abrasion resistance 1,000 times higher than PTFE in terms of sliding properties, and is less likely to damage the material it slides against. Crosslinked PTFE also has high resistance to denaturation and is less likely to deform under load, and is more resistant to denaturation than PTFE at both room temperature and high temperatures. Crosslinked PTFE also has the same processability as PTFE, such as cutting, welding, and pasting, as well as chemical resistance, non-adhesiveness, and electrical properties.
Modified PTFE is a material in which the main chain of PTFE is partially modified, with a small amount of perfluoroalkyl vinyl ether as a comonomer. Modified PTFE has improved flexural and creep properties compared to PTFE, and when used for diaphragms, the flexural life is several times longer.

The driving side body 45 defines therein a piston cylindrical space 46 in which a piston 70 is disposed. The piston 70 has a valve body 21 disposed at one end thereof.
The piston cylindrical space 46 includes a piston biasing means 71 that biases the piston 70. The piston biasing means 71 biases the piston 70 in a direction in which the valve body 21 abuts against the valve seat 40a.
The piston 70 is formed with a piston enlarged portion 72. The piston biasing means 71 biases the piston 70 by pressing the piston enlarged portion 72. The piston biasing means 71 can be, for example, a coil spring.
The diaphragm 22 is held by the flow path side body 44 and a diaphragm holder 73. The piston 70 is displaced at the center of the diaphragm holder 73.
The driving side body 45 has air flow passages 47a and 47b formed therein.
The air flow passage 47a communicates with the piston cylindrical space 46a between the diaphragm holder 73 and the piston enlarged portion 72, and the air flow passage 47b communicates with the piston cylindrical space 46b in which the piston biasing means 71 is disposed.
A piston cylindrical space 46c is formed between the diaphragm holder 73 and the diaphragm 22. The piston cylindrical space 46c communicates with the outside of the diaphragm valve through a communication passage 46d.
The diaphragm 22 separates the flow control passage 13 from the piston cylindrical space 46. Therefore, the inflow passage 11 is formed on one side of the diaphragm 22.
The diaphragm 22 may be held by the flow path side body 44 and the drive side body 45 without providing the diaphragm holder 73. In the present embodiment, the diaphragm holder 73 has a function of supporting the piston 70, but the diaphragm holder 73 does not have to have a function of supporting the piston 70.

The valve body 21 is displaced in accordance with the movement of the piston 30 , and the diaphragm 22 is deformed in accordance with the displacement of the valve body 21 .
The diaphragm 22 has a thin portion 22a connected to the valve body 21, and a fixing portion 22b formed on the outer periphery of the thin portion 22a.
A conductive sheet 53 is disposed on the other side of the diaphragm 22 in contact with the diaphragm 22 .
In addition, the conductive sheet 53 is connected to the earth 60 .
In this embodiment, the conductive sheet 53 is disposed on the thin portion 22a and the fixed portion 22b.
By disposing the conductive sheet 53 at least on the thin portion 22a in this manner, it is possible to prevent destruction of the thin portion 22a, which is susceptible to damage caused by electrostatic discharge.
Furthermore, by disposing the conductive sheet 53 at least on the thin portion 22a and the fixed portion 22b, it is possible to prevent destruction of the thin portion 22a, which is susceptible to damage caused by electrostatic discharge, and connection to earth 60 can be made using the fixed portion 22b.
According to this embodiment, by disposing the conductive sheet 53 in contact with the diaphragm 22, the conductive sheet 53 can prevent the diaphragm 22 from becoming electrically charged due to the flow of the controlled fluid, and corona discharge due to charging can be eliminated.
1, small holes 23 may be formed in the diaphragm 22 so that the controlled fluid comes into contact with the conductive sheet 53 through the small holes 23. The conductive sheet 53 prevents the controlled fluid from flowing out through the small holes 23.
In this manner, the controlled fluid can be brought into contact with the conductive sheet 53 through the small holes 23, thereby eliminating static electricity, and the conductive sheet 53 can also prevent the controlled fluid from flowing out through the small holes 23.

The flow path side body 44 is made of fluororesin such as PTFE, cross-linked PTFE, modified PTFE, or PFA. The drive side body 45 is made of engineering plastics such as PP (polypropylene) and PPS (polyphenylene sulfide), or fluororesins such as PTFE, modified PTFE, PVDF (polyvinylidene fluoride), and ETFE.

FIG. 3 shows the valve body 21 in a fully closed state.
By supplying gas from the air flow passage 47a to the piston cylindrical space 46a, pressure is applied to the piston 70 in a direction opposite to the bias of the piston biasing means 71. Therefore, the piston 70 moves in a direction that separates the valve body 21 from the valve seat 40a.
When the valve body 21 separates from the valve seat 40a, the controlled fluid flows in from the inflow passage 11, and the pressure of the controlled fluid is applied to the diaphragm 22. The gas in the piston cylindrical space 46b is exhausted from the air flow passage 47b.
To change the valve body 21 from the fully open state to the closed state, gas in the piston cylindrical space 46a is discharged from the air flow passage 47a. By discharging the gas from the piston cylindrical space 46a, the pressure in the piston cylindrical space 46a decreases, and the piston 70 moves in a direction approaching the valve seat 40a due to the biasing force of the piston biasing means 71. Gas is drawn into the piston cylindrical space 46b from the air flow passage 47a.
When the valve body 21 is in the closed state, the piston biasing means 71 biases the valve body 21 to abut against the valve seat 40 a.

It is preferable that the valve body side diaphragm 22 and the conductive sheet 51 are at least partially welded together, and it is more preferable that they are welded together over the entire surface.
It is also preferable that the shaft-side diaphragm 32 and the conductive sheet 52 are at least partially welded together, and it is even more preferable that they are welded together over the entire surface.
Also, it is preferable that the diaphragm 22 and the conductive sheet 53 are at least partially welded together, and it is more preferable that they are welded together over the entire surface.
By welding the diaphragms 22, 32 and the conductive sheets 51, 52, 53, static electricity can be reliably prevented.
The conductive sheets 51, 52, and 53 are resin sheets containing carbon nanoparticles, carbon microcoils, or a conductive material, and the leakage resistance value of the conductive sheets 51, 52, and 53 can be adjusted by adjusting the compounding ratio of the carbon nanoparticles, carbon microcoils, or the conductive material. For the conductive sheets 51, 52, and 53, fluororesins (PTFE, modified PTFE, PFA, ETFE, fluororubber, etc.) are suitable.

When the diaphragms 22 and 32 are not provided with the small holes 23, the leakage resistance of the conductive sheets 51, 52, and 53 is set to 10 ⁴ Ω to 10 ¹¹ Ω, thereby making it possible to prevent charging.
Furthermore, when the small holes 23 are provided in the diaphragms 22 and 32, the leakage resistance of the conductive sheets 51, 52, and 53 is set to 10 ² Ω to 10 ⁹ Ω, so that static electricity can be easily removed.

As described above, conductive sheets 51, 52, 53 are arranged on the other side of diaphragms 22, 32 in contact with diaphragms 22, 32, and the conductive sheets 51, 52, 53 are connected to earth 60, thereby preventing the conductive sheets 51, 52, 53 from charging the diaphragms 22, 32 due to the flow of the controlled fluid, and eliminating corona discharge due to charging.
In addition, earth 60 is not limited to earth, but may be any member having a larger electrostatic capacitance than conductive sheets 51, 52, and 53, such as a metal casing, a conductive drain pipe, or a conductive member.

The present invention is suitable for diaphragm valves in the semiconductor manufacturing field, where precise flow control and high cleanliness are required.

REFERENCE SIGNS LIST 11 inflow flow passage 12 outflow flow passage 13 flow rate control flow passage 14 valve body side pressurizing chamber 14a pressing member 14b elastic member 14c washer 15 shaft body side pressurizing chamber 15a set air port 20 valve body side member 21 valve body 21a connection portion 21b contact portion 22 valve body side diaphragm (diaphragm)
22a Thin wall portion 22b Fixed portion 23 Small hole 30 Shaft side member 31 Shaft 31a Contact portion 32 Shaft side diaphragm (diaphragm)
32a: thick portion 32b: thin portion 32c: fixed portion 40: body 40a: valve seat 41: flow passage forming body 42: valve body side body 43: shaft body side body 44: flow passage side body 45: drive side body 46, 46a, 46b, 46c: piston cylindrical space 46d: communication passage 47a, 47b: air flow passage 51, 52, 53: conductive sheet 60: earth 70: piston 71: piston biasing means 72: piston enlarged portion 73: diaphragm holder

Claims (10)

an inflow flow path into which a controlled fluid flows;
an outlet flow path through which the controlled fluid flows;
a flow control flow passage located between the inlet flow passage and the outlet flow passage;
A valve body disposed in the flow rate control flow path;
a diaphragm that deforms with the displacement of the valve body,
The diaphragm is formed of a resin material,
A diaphragm valve in which the inlet flow passage is formed on one side of the diaphragm,
a conductive sheet is disposed on the other side of the diaphragm in contact with the diaphragm;
A diaphragm valve characterized in that the conductive sheet is connected to earth. an inflow flow path into which a controlled fluid flows;
an outlet flow path through which the controlled fluid flows;
a flow control flow passage located between the inlet flow passage and the outlet flow passage;
A valve body disposed in the flow rate control flow path;
A shaft body that presses the valve body;
a diaphragm that deforms with the displacement of the valve body or the shaft body,
The diaphragm may include
a valve body side diaphragm that deforms with the displacement of the valve body;
a shaft-side diaphragm that deforms with the displacement of the shaft;
the inlet flow passage is formed on one side of the valve body side diaphragm, and a valve body side pressurizing chamber is formed on the other side of the valve body side diaphragm,
a diaphragm valve in which the outflow passage is formed on one side of the shaft-side diaphragm and a shaft-side pressure chamber is formed on the other side of the shaft-side diaphragm,
a conductive sheet is disposed on the other one of the valve body side diaphragms or the other one of the shaft body side diaphragms in contact with the valve body side diaphragm or the shaft body side diaphragm,
A diaphragm valve characterized in that the conductive sheet is connected to earth. The valve body side diaphragm is
A thin-walled portion connected to the valve body and a fixing portion formed on an outer periphery of the thin-walled portion,
3. The diaphragm valve according to claim 2, wherein the conductive sheet is disposed at least in the thin portion. The shaft side diaphragm is
a thick portion connected to the shaft body, a thin portion formed on an outer periphery of the thick portion, and a fixing portion formed on an outer periphery of the thin portion,
3. The diaphragm valve according to claim 2, wherein the conductive sheet is disposed at least in the thin portion. The shaft side diaphragm is
a thick portion connected to the shaft body, a thin portion formed on an outer periphery of the thick portion, and a fixing portion formed on an outer periphery of the thin portion,
3. The diaphragm valve according to claim 2, wherein the conductive sheet is disposed at least on the thin portion and the fixed portion. 6. The diaphragm valve according to claim 1, wherein the diaphragm and the conductive sheet are welded together. The diaphragm is provided with a small hole,
the small holes allow the controlled fluid to contact the conductive sheet;
6. The diaphragm valve according to claim 1, wherein the conductive sheet prevents the controlled fluid from flowing out of the small hole. 6. The diaphragm valve according to claim 1, wherein the conductive sheet is a resin sheet containing carbon nanoparticles, carbon microcoils, or a conductive material. 6. The diaphragm valve according to claim 1, wherein the conductive sheet has a leakage resistance of 10 ⁴ Ω to 10 ¹¹ Ω. 8. The diaphragm valve according to claim 7, wherein the conductive sheet has a leakage resistance of 10 ² Ω to 10 ⁹ Ω.