constant pressure valve

Abstract

To provide a constant-pressure valve which is excellent in bending performance of a diaphragm and can reduce the generation of particles.SOLUTION: A valve-body side abutment face 21x which is vertical to a moving direction of a valve body 21 and a shaft 31 is formed at the valve body 21, a shaft-side abutment face 31x vertical to the moving direction of the valve body 21 and the shaft 31 is formed at the shaft 31, a valve-seat side abutment face 41x vertical to the moving direction of the valve body 21 and the shaft 31 is formed at a flow rate control flow passage 13, a valve-closing abutment part 41y protruding in a ring shape is formed at the valve-body side abutment face 21x or the valve-seat side abutment face 41x, a valve body pressing abutment part 31y protruding in a ring shape is formed at the valve-body side abutment face 21x or the shaft-side abutment face 31x, the shaft 31 and a shaft-side diaphragm 32 are formed of composite materials obtained by joining PTFE and bridged PTFE, the shaft-side diaphragm 32 is formed of PTFE, and the shaft-side abutment face 31x is formed of bridged PTFE.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a constant pressure valve that maintains a constant outlet pressure of a controlled fluid flowing out of an outlet flow path even when the inlet pressure of the controlled fluid flowing in from an inlet flow path fluctuates.

Background Art

[0002] In the cleaning and stripping processes in the silicon wafer process for semiconductor device manufacturing, highly corrosive chemicals such as strong acids and strong alkalis are used. Also, metals and organic solutes from the valve are not allowed, and the chemicals used in the cleaning and stripping processes are required to have extremely high cleanliness. Therefore, fluororesin, which is excellent in acid resistance and alkali resistance and is a low-elution material, is adopted for the valve through which the chemical flows. The mixing of particles into the fluid flow path in the semiconductor manufacturing process greatly affects the product yield, so the generation of particles from the valve is not allowed. Therefore, as a valve for supplying high-purity chemicals and ultrapure water, a structure is adopted in which a diaphragm isolates the drive part and the liquid contact part so that the generation of dust from the sliding part does not affect the liquid contact part of the valve. For example, in Patent Document 1, there are provided an inlet flow path into which a controlled fluid flows, an outlet flow path from which the controlled fluid flows out, a flow rate control flow path located between the inlet flow path and the outlet flow path, a valve body disposed in the flow rate control flow path, a valve body side diaphragm that displaces the valve body, a shaft that presses the valve body, and a shaft side diaphragm that displaces the shaft. One side of the valve body side diaphragm communicates with the inlet flow path, a valve body side pressure chamber is formed on the other side of the valve body side diaphragm, one side of the shaft side diaphragm communicates with the outlet flow path, and a shaft side pressure chamber is formed on the other side of the shaft side diaphragm. A constant pressure valve is proposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] PTFE (polytetrafluoroethylene resin) is a material that offers excellent chemical resistance and flexibility, as well as a long service life. However, with the recent development of further miniaturization of semiconductor manufacturing processes (10nm process or less), improvements are now required in terms of dust generation from the machined surface, and it is becoming increasingly difficult to adequately meet these requirements even with the use of PTFE. Cross-linked PTFE has chemical resistance and flexibility equivalent to PTFE, and is even more abrasion-resistant than PTFE. However, it is more expensive because the manufacturing process is more complex than that of PTFE, making it difficult to construct the entire valve body from cross-linked PTFE.

[0005] Therefore, the present invention aims to provide a constant pressure valve that offers excellent diaphragm flexibility and reduces particle generation. [Means for solving the problem]

[0006] The constant pressure valve of the present invention as described in claim 1 comprises an inlet passage 11 through which a controlled fluid flows in, an outlet passage 12 through which the controlled fluid flows out, a flow control passage 13 located between the inlet passage 11 and the outlet passage 12, a valve body 21 disposed in the flow control passage 13, a valve body side diaphragm 22 that displaces the valve body 21, a shaft 31 that presses the valve body 21, and a shaft side diaphragm 32 that displaces the shaft 31, wherein one side of the valve body side diaphragm 22 is in communication with the inlet passage 11, the other side of the valve body side diaphragm 22 has a valve body side pressurizing chamber 14, one side of the shaft side diaphragm 32 is in communication with the outlet passage 12, and the shaft side diaphragm A constant pressure valve is provided in which a shaft-side pressurizing chamber 15 is formed on the other side of the diaphragm 32, and even if the inflow-side pressure due to the controlled fluid flowing in from the inflow passage 11 fluctuates, the valve body-side diaphragm 22 and the shaft-side diaphragm 32 deform to maintain a constant outflow-side pressure due to the controlled fluid flowing out from the outflow passage 12, wherein the valve body 21 has a valve body-side contact surface 21x perpendicular to the direction of movement of the valve body 21 and the shaft 31, and the shaft 31 has a shaft-side contact surface 31x perpendicular to the direction of movement of the valve body 21 and the shaft 31, and the flow control passage 13 has the valve body 21 and the shaft 31 The aforementioned A valve seat side contact surface 41x perpendicular to the direction of movement is formed, a ring-shaped valve closing contact portion 41y protruding from the valve body side contact surface 21x or the valve seat side contact surface 41x is formed, and a ring-shaped valve body pressing contact portion 31y protruding from the valve body side contact surface 21x or the shaft side contact surface 31x is formed. The body 40 is composed of a flow path forming body 41, a valve body side body 42, and a shaft side body 43. The flow path forming body 41 forms the inlet flow path 11, the outlet flow path 12, and the flow rate control flow path 13. The valve body side body 42 forms the valve body side pressurizing chamber 14. The shaft side body 43 forms the shaft side pressurizing chamber 15. The valve body side diaphragm 22 is fixed to the flow path forming body 41 by the valve body side body 42, and the shaft side diaphragm 32 is fixed to the flow path forming body 41 by the shaft side body 43. The shaft 31 and the shaft-side diaphragm 32 are formed from a composite material formed by joining PTFE and cross-linked PTFE, the shaft-side diaphragm 32 is formed from PTFE, and the shaft-side contact surface 31x is formed from cross-linked PTFE. The valve body side body 42 and the shaft side body 43 are formed from PTFE, the flow path forming body 41 is formed from PFA, and the cross-linked PTFE bonded to the flow path forming body 41 by resistance heating is used as the valve seat side contact surface 41x. It is characterized by the following. The present invention as described in claim 2 is characterized in that, in the constant pressure valve described in claim 1, the valve body 21 and the valve body side diaphragm 22 are formed of the composite material, the valve body side diaphragm 22 is formed of PTFE, and the valve body side contact surface 21x is formed of crosslinked PTFE. The present invention as described in claim 3 is characterized in that, in the constant pressure valve described in claim 1, the valve body side contact surface 21x is formed of the cross-linked PTFE. The present invention as described in claim 4 is characterized in that, in the constant pressure valve described in claim 1, the valve closing contact portion 41y and the valve body pressing contact portion 31y are formed of the cross-linked PTFE. Claim 5 The present invention described herein is Claim 1 The constant pressure valve described above is characterized in that the valve seat side contact surface 41x is formed by the sheet-like cross-linked PTFE, and the valve closing contact portion 41y is formed on the valve body side contact surface 21x. [Effects of the Invention]

[0007] According to the constant pressure valve of the present invention, the valve body side contact surface, the shaft side contact surface, and the valve seat side contact surface are perpendicular to the direction of movement of the valve body and shaft. The valve body side contact surface and the valve seat side contact surface are brought into contact by a ring-shaped protruding valve closing contact portion, and the valve body side contact surface and the shaft side contact surface are brought into contact by a ring-shaped protruding valve body pressing contact portion, thereby reducing the generation of particles due to contact. Furthermore, by forming the shaft and the shaft side diaphragm from a composite material, the generation of particles can be reduced compared to when the shaft and the shaft side diaphragm are formed from separate components. In addition, forming the shaft side diaphragm from PTFE provides excellent flexibility, and forming the shaft side contact surface from cross-linked PTFE further reduces the generation of particles. [Brief explanation of the drawing]

[0008] [Figure 1] Cross-sectional view showing a constant pressure valve according to one embodiment of the present invention. [Figure 2] Cross-sectional view showing the operating state of the identification pressure valve. [Figure 3] Cross-sectional view showing a constant pressure valve according to another embodiment of the present invention. [Figure 4] Cross-sectional view showing a constant pressure valve according to yet another embodiment of the present invention. [Modes for carrying out the invention]

[0009] The constant pressure valve according to the first embodiment of the present invention has a valve body side contact surface formed on the valve body perpendicular to the direction of movement of the valve body and shaft, a shaft side contact surface formed on the shaft perpendicular to the direction of movement of the valve body and shaft, a valve seat side contact surface formed on the flow control passage perpendicular to the direction of movement of the valve body and shaft, a ring-shaped protruding valve closing contact portion formed on the valve body side contact surface or the valve seat side contact surface, and a ring-shaped protruding valve body pressing contact portion formed on the valve body side contact surface or the shaft side contact surface. The body consists of a flow path forming body, a valve body side body, and a shaft side body. The flow path forming body forms an inlet flow path, an outlet flow path, and a flow control flow path. The valve body side body forms a valve body side pressurizing chamber. The shaft side body forms a shaft side pressurizing chamber. The valve body side diaphragm is fixed to the flow path forming body by the valve body side body, and the shaft side diaphragm is fixed to the flow path forming body by the shaft side body. The shaft and the shaft-side diaphragm are formed from a composite material formed by joining PTFE and cross-linked PTFE, the shaft-side diaphragm is formed from PTFE, and the shaft-side contact surface is formed from cross-linked PTFE. The valve body and shaft body are formed from PTFE, the flow path forming body is formed from PFA, and the cross-linked PTFE bonded to the flow path forming body by resistance heating is used as the valve seat contact surface. This invention provides a valve body side contact surface, a shaft side contact surface, and a valve seat side contact surface that are perpendicular to the direction of movement of the valve body and shaft. The valve body side contact surface and the valve seat side contact surface are brought into contact by a ring-shaped protruding valve closing contact portion, and the valve body side contact surface and the shaft side contact surface are brought into contact by a ring-shaped protruding valve pressing contact portion, thereby reducing the generation of particles due to contact. Furthermore, by forming the shaft and the shaft side diaphragm from a composite material, the generation of particles can be reduced compared to the case where the shaft and the shaft side diaphragm are formed from separate components. Additionally, forming the shaft side diaphragm from PTFE provides excellent flexibility, and forming the shaft side contact surface from cross-linked PTFE further reduces the generation of particles. Furthermore, by placing cross-linked PTFE on the flow path forming body and pressing a heating block, which is directly heated by resistance heating, against the cross-linked PTFE side, the valve seat contact surface can be joined. By directly heating the cross-linked PTFE with the heating block above its melting point, the cross-linked PTFE softens or partially melts, and the flow path forming body, made of PFA, is heated and melted at the contact interface with the cross-linked PTFE due to the heating from the cross-linked PTFE, thus enabling a strong bond. In addition, by directly heating the cross-linked PTFE with resistance heating, temperature control at the contact interface can be easily performed, and temperature control with high responsiveness to the melting surface temperature can be achieved. Therefore, because heating is limited to the contact interface, deformation of the flow path forming body does not occur, and the cross-linked PTFE can be flattened.

[0010] The second embodiment of the present invention is a constant pressure valve according to the first embodiment, in which the valve body and the valve body side diaphragm are formed of a composite material, the valve body side diaphragm is formed of PTFE, and the valve body side contact surface is formed of cross-linked PTFE. According to this embodiment, by forming the valve body and the valve body side diaphragm of a composite material, the generation of particles can be reduced as compared with the case where the valve body and the valve body side diaphragm are formed of separate members. Further, by forming the valve body side diaphragm of PTFE, excellent flexibility can be obtained, and by forming the valve body side contact surface of cross-linked PTFE, the generation of particles can be reduced.

[0011] The third embodiment of the present invention is a constant pressure valve according to the first embodiment, in which the valve body side contact surface is formed of cross-linked PTFE. According to this embodiment, by forming the valve body side contact surface of cross-linked PTFE, the generation of particles can be reduced.

[0012] The fourth embodiment of the present invention is a constant pressure valve according to the first embodiment, in which the contact portion for closing the valve and the contact portion for pressing the valve body are formed of cross-linked PTFE. According to this embodiment, by forming the contact portion for closing the valve and the contact portion for pressing the valve body of cross-linked PTFE, the generation of particles can be reduced.

[0013] The Fifth embodiment of the present invention is, 1 in a constant pressure valve according to the embodiment of, a valve seat side contact surface is formed of sheet-like cross-linked PTFE, and a contact portion for closing the valve is formed on the valve body side contact surface. According to this embodiment, by forming the valve seat side contact surface of sheet-like cross-linked PTFE, variations in melt flow rate are unlikely to occur, the shape can be maintained and welded and joined, and a uniform joining strength can be obtained.

Example

[0014] Hereinafter, a constant pressure valve according to an embodiment of the present invention will be described. FIG. 1 is a cross-sectional view showing a constant pressure valve according to this embodiment. FIG. 1(a) shows the entire constant pressure valve, FIG. 1(b) shows the shaft and the shaft-side diaphragm, FIG. 1(c) shows the valve body and the valve body-side diaphragm, and FIG. 1(d) shows the body.

[0015] The constant pressure valve according to this embodiment includes an inflow passage 11 into which a 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 disposed in the flow rate control passage 13, a valve body-side diaphragm 22 that displaces the valve body 21, a shaft 31 that presses the valve body 21, and a shaft-side diaphragm 32 that displaces the shaft 31. In the constant pressure valve according to this embodiment, the inflow passage 11 communicates with one side of the valve body-side diaphragm 22, a valve body-side pressure chamber 14 is formed on the other side of the valve body-side diaphragm 22, the outflow passage 12 communicates with one side of the shaft-side diaphragm 32, and a shaft-side pressure chamber 15 is formed on the other side of the shaft-side diaphragm 32. A pressing member 14a that presses the valve body-side diaphragm 22 is disposed in the valve body-side pressure chamber 14. The pressing member 14a is biased in the direction of the valve body-side diaphragm 22 by an elastic member 14b. Pressurized gas is introduced into the shaft-side pressure chamber 15, and the shaft-side diaphragm 32 is pressed by the introduced pressurized gas. In this embodiment, an elastic member 14b is provided in the valve body-side pressure chamber 14, but it may be biased by a fluid together with or instead of the elastic member 14b. Also, in this embodiment, pressurized gas is introduced into the shaft-side pressure chamber 15, but a spring material may be provided together with or instead of the pressurized gas.

[0016] Note that in the figure, the black color indicates cross-linked PTFE. As shown in Figure 1(b), the shaft 31 and the shaft-side diaphragm 32 are integrally molded from resin as the shaft-side member 30. The shaft-side member 30 is formed from a composite material formed by joining PTFE (polytetrafluoroethylene resin) and cross-linked PTFE (polytetrafluoroethylene-perfluoroalkoxyethylene copolymer resin). Crosslinked PTFE is a type of PTFE produced by a reaction that bridges independent molecules, and is manufactured using crosslinking methods such as chemical crosslinking or radiation crosslinking. In terms of sliding properties, crosslinked PTFE has more than 1,000 times the wear resistance of PTFE, and is less likely to damage the material it slides against. Furthermore, crosslinked PTFE has high deformation resistance and is less likely to deform under load, and is superior to PTFE in deformation resistance at both room temperature and high temperatures. In addition, crosslinked PTFE has the same processability as PTFE, including cutting, welding, and bonding, as well as chemical resistance, non-stick properties, and electrical properties. The joining of PTFE and crosslinked PTFE is performed by pressure and heat bonding.

[0017] The shaft 31 has a connecting portion 31a that connects to the shaft-side diaphragm 32 and a contact portion 31b that presses against the valve body 21. The connecting portion 31a has a frustoconical shape, with its bottom surface connected to the shaft-side diaphragm 32 and its top surface connected to the contact portion 31b. The contact portion 31b is cylindrical in shape, with one end face connected to the top surface of the connecting portion 31a, and the other end face becoming the shaft-side contact surface 31x. The shaft-side contact surface 31x is a surface perpendicular to the direction of movement of the valve body 21 and the shaft 31. A ring-shaped valve body pressing contact portion 31y is formed on the shaft-side contact surface 31x. It is preferable that the valve body pressing contact portion 31y is formed on the outer circumference of the shaft-side contact surface 31x. That is, it is preferable that the outer diameter of the valve body pressing contact portion 31y be the same as the outer diameter of the contact portion 31b.

[0018] The shaft-side diaphragm 32 has a thickened portion 32a connected to the shaft 31, a thinned portion 32b formed on the outer circumference of the thickened portion 32a, and a fixed portion 32c formed on the outer circumference of the thinned portion 32b. The shaft-side diaphragm 32 is connected to the thickened portion 32a at its center. The shaft-side diaphragm 32 is made of PTFE, and the shaft-side contact surface 31x and the valve body pressing contact portion 31y are made of cross-linked PTFE. In this embodiment, the shaft-side diaphragm 32, the connecting portion 31a, and the contact portion 31b are formed from PTFE on the connecting portion 31a side, while the shaft-side contact surface 31x of the contact portion 31b is formed from cross-linked PTFE.

[0019] As shown in Figure 1(c), 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 is formed from a composite material formed by joining PTFE and cross-linked PTFE. The valve body 21 has a connecting portion 21a that connects to the valve body side diaphragm 22, and a contact portion 21b that is pressed by the shaft 31 and contacts the valve seat side contact surface 41x. The connecting portion 21a is cylindrical in shape, with one end face connected to the valve body side diaphragm 22 and the other end face connected to the contact portion 21b. The contact portion 21b is cylindrical in shape, with one end face connecting to the other end face of the connecting portion 21a, and the other end face becoming the valve body side contact surface 21x. The contact portion 21b is formed with a larger outer diameter than the connecting portion 21a. The valve body side contact surface 21x is a surface perpendicular to the direction of movement of the valve body 21 and the shaft 31.

[0020] The valve body-side diaphragm 22 has a thin-walled portion 22a connected to the valve body 21 and a fixed portion 22b formed on the outer circumference of the thin-walled portion 22a. The valve body-side diaphragm 22 is connected to the thin-walled portion 22a at its central portion. The valve body side diaphragm 22 is made of PTFE, and the valve body side contact surface 21x is made of cross-linked PTFE. In this embodiment, the valve body side diaphragm 22, the connecting portion 21a, and the contact portion 21b are formed from PTFE on the connecting portion 21a side, while the valve body side contact surface 21x of the contact portion 21b is formed from cross-linked PTFE.

[0021] As shown in Figure 1(d), the body 40 includes a flow path forming body 41, a valve body side body 42, and a shaft side body 43. The flow path forming body 41 forms an inflow flow path 11, an outflow flow path 12, and a flow rate control flow path 13. The valve body 42 forms a valve body pressurizing chamber 14 and a breathing hole 14c that communicates with the valve body pressurizing chamber 14. The valve body side member 20 is fixed to the flow path forming body 41 by the valve body side body 42. The shaft-side body 43 forms a shaft-side pressurizing chamber 15, and a setting air port 15a and an exhaust port 15b that communicate with the shaft-side pressurizing chamber 15. The shaft-side member 30 is fixed to the flow path forming body 41 by the shaft-side body 43.

[0022] The valve seat side contact surface 41x is formed in the flow control channel 13 as a surface perpendicular to the direction of movement of the valve body 21 and the shaft 31. A ring-shaped valve-closing contact portion 41y is formed on the valve seat side contact surface 41x. Preferably, the valve-closing contact portion 41y is formed on the inner circumference of the valve seat side contact surface 41x. That is, it is preferable that the inner diameter of the valve-closing contact portion 41y is the same as the inner diameter of the valve seat side contact surface 41x. The valve seat side contact surface 41x and the valve closing contact portion 41y are formed of cross-linked PTFE, while the flow path forming body 41 other than the valve body side contact surface 41x, the valve body side body 42, and the shaft side body 43 are formed of PTFE.

[0023] Furthermore, the valve seat side contact surface 41x and the valve closing contact portion 41y are formed of cross-linked PTFE, the flow path forming body 41 other than the valve seat side contact surface 41x is formed of PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin), and the valve body side body 42 and the shaft side body 43 are formed of PTFE. By using low-viscosity PFA for the channel-forming body 41, the channel-forming body 41 can be injection molded. To join a valve seat-side contact surface 41x made of cross-linked PTFE to a flow channel forming body 41 made of PFA, the cross-linked PTFE is placed on the flow channel forming body 41, and a heating block, which is directly heated by resistance heating, is pressed against it from the cross-linked PTFE side. By directly heating the cross-linked PTFE with the heating block above its melting point, the cross-linked PTFE is softened or partially melted, and the flow channel forming body 41 made of PFA is heated and melted at the contact interface with the cross-linked PTFE due to the heating from the cross-linked PTFE, thus enabling a strong bond. Furthermore, by directly heating the cross-linked PTFE with resistance heating, temperature control at the contact interface can be easily performed, and temperature control with high responsiveness to the melting surface temperature can be achieved. Therefore, because the heating is limited to the contact interface, deformation of the flow channel forming body 41 does not occur, and the cross-linked PTFE can be flattened. To form the valve seat side contact surface 41x, it is preferable to use sheet-shaped cross-linked PTFE with a thickness of 0.05 mm to 0.5 mm. If the sheet-shaped cross-linked PTFE is thinner than 0.05 mm, PFA may penetrate and reach the sealing surface, and if the sheet-shaped cross-linked PTFE is thicker than 0.5 mm, the melting time will be longer, which may cause deformation of the flow path forming body 41.

[0024] In this way, by joining the valve seat side contact surface 41x made of cross-linked PTFE to the flow path forming body 41 made of PFA, the valve seat side contact surface 41x can be joined to the flow path forming body 41 with a bonding strength that exceeds the strength of friction bonding due to polymer entanglement. Furthermore, by forming the valve seat side contact surface 41x with sheet-like cross-linked PTFE, variations in melt flow rate are less likely to occur, allowing for welding while maintaining the shape, and enabling the acquisition of uniform joint strength. In this case, as shown in Figure 4, the valve closing contact portion 41y is formed on the valve body side contact surface 21x.

[0025] Figure 2 is a cross-sectional view showing the operating state of the constant pressure valve according to this embodiment. Figure 2(a) shows the state in which the controlled fluid is flowing, and Figure 2(b) shows the state in which the outlet pressure has increased. As shown in Figure 2(a), the controlled fluid flowing in from the inflow channel 11 passes through the flow control channel 13 and flows out from the outflow channel 12. The shaft-side diaphragm 32 deforms in a direction that causes the shaft 31 to press against the valve body 21 due to the gas pressure in the shaft-side pressurizing chamber 15. The set pressure in the shaft-side pressurizing chamber 15 is adjusted by introducing pressurized gas from the set air port 15a or discharging pressurized gas from the exhaust port 15b. The valve body-side diaphragm 22 deforms in a direction that causes the valve body 21 to press against the shaft 31 due to the pressing force of the valve body-side pressurizing chamber 14. The pressing force of the valve body-side pressurizing chamber 14 is set by the elastic member 14b. As shown in Figure 2(a), when the fluid to be controlled is flowing through the flow control channel 13, the shaft 31 presses against the valve body 21 by the shaft-side diaphragm 32, and the valve body 21 presses against the shaft 31 by the valve body-side diaphragm 22, so the valve body 21 and the shaft 31 are in contact with each other.

[0026] In the state shown in Figure 2(a), when the inflow side pressure due to the controlled fluid flowing in from the inflow channel 11 increases and becomes higher than the set pressure, the shaft side diaphragm 32 is displaced in a direction that causes the shaft 31 to move away from the valve body 21 due to the inflow side pressure. As the shaft 31 is displaced in a direction away from the valve body 21, the valve body 21 is displaced together with the shaft 31. That is, the valve body 21 is displaced in a direction closer to the valve seat side contact surface 41x, so the flow control passage 13 is narrowed. By narrowing the flow control channel 13, it is possible to prevent the outflow side pressure from rising due to the controlled fluid flowing out from the outflow channel 12. On the other hand, in the state shown in Figure 2(a), when the inflow side pressure due to the controlled fluid flowing in from the inflow channel 11 decreases and falls below the set pressure, the shaft side diaphragm 32 is displaced in the direction in which the shaft 31 presses against the valve body 21. The valve body 21 is displaced as the shaft 31 is displaced in a direction that presses against it. In other words, the valve body 21 is displaced in a direction that moves away from the valve seat side contact surface 41x, so the flow control passage 13 expands. By expanding the flow control channel 13, it is possible to prevent a decrease in the outlet pressure due to the controlled fluid flowing out from the outlet channel 12. Thus, in this embodiment, even if the inflow pressure due to the controlled fluid flowing in from the inflow passage 11 fluctuates, the constant pressure valve can maintain a constant outflow pressure due to the controlled fluid flowing out from the outflow passage 12 by deforming the shaft-side diaphragm 32. In addition, in order to displace the valve body 21 together with the shaft 31, the valve body-side diaphragm 22 also displaces in accordance with the fluctuations in the inflow pressure.

[0027] Figure 2(b) shows the state where the outflow pressure has increased. When the outflow pressure increases, the shaft-side diaphragm 32 is displaced by the outflow pressure in a direction that causes the shaft 31 to move away from the valve body 21. As the shaft 31 is displaced in a direction that moves it away from the valve body 21, the valve body 21 is displaced together with the shaft 31, and the valve body 21 comes into contact with the valve seat side contact surface 41x. Even when the valve body 21 is in contact with the valve seat side contact surface 41x, if the outflow side pressure is higher than the set pressure, the shaft 31 will move away from the valve body 21, as shown in Figure 2(b). Therefore, even if the outflow pressure increases and the valve body 21 comes into contact with the valve seat contact surface 41x, the valve body 21 is not subjected to any load from the outflow pressure, only the pressing force from the elastic member 14b.

[0028] Figure 3 is a cross-sectional view showing a constant pressure valve according to another embodiment of the present invention. Functional components identical to those in the above embodiments are denoted by the same reference numerals, and their descriptions are omitted. In this embodiment, the channel-forming body 41 is formed from cross-linked PTFE, which is different from the above embodiment, but the other components are the same. As in this embodiment, by forming the entire flow path-forming body 41 from cross-linked PTFE, the generation of particles in the inflow flow path 11, outflow flow path 12, and flow control flow path 13 can be reduced.

[0029] Figure 4 is a cross-sectional view showing a constant pressure valve according to yet another embodiment of the present invention. Functional components identical to those in the above embodiments are denoted by the same reference numerals, and their descriptions are omitted. In this embodiment, the valve body pressing contact portion 31y and the valve closing contact portion 41y are provided on the valve body side contact surface 21x, which is different from the above embodiment, but the other configurations are the same. As in this embodiment, the valve body pressing contact portion 31y may be formed on the valve body side contact surface 21x instead of the shaft side contact surface 31x, and the valve closing contact portion 41y may be formed on the valve body side contact surface 21x instead of the valve seat side contact surface 41x. Furthermore, the embodiment shown in Figure 3 may be applied to the embodiment shown in Figure 4.

[0030] As described above, according to this embodiment, the valve body side contact surface 21x, the shaft side contact surface 31x, and the valve seat side contact surface 41x are surfaces perpendicular to the direction of movement of the valve body 21 and the shaft 31. The valve body side contact surface 21x and the valve seat side contact surface 41x are brought into contact by the ring-shaped protruding valve closing contact portion 41y, and the valve body side contact surface 21x and the shaft side contact surface 31x are brought into contact by the ring-shaped protruding valve pressing contact portion 31y, thereby reducing the generation of particles due to contact. Furthermore, by forming the shaft 31 and the shaft side diaphragm 32 from a composite material, the generation of particles can be reduced compared to the case where the shaft 31 and the shaft side diaphragm 32 are formed from separate components. In addition, forming the shaft side diaphragm 32 from PTFE provides excellent flexibility, and forming the shaft side contact surface 31x from cross-linked PTFE further reduces the generation of particles. Furthermore, according to this embodiment, by forming the valve body 21 and the valve body side diaphragm 22 from a composite material, particle generation can be reduced compared to the case where the valve body 21 and the valve body side diaphragm 22 are formed from separate components. In addition, forming the valve body side diaphragm 22 from PTFE provides excellent flexibility, and forming the valve body side contact surface 21x from cross-linked PTFE further reduces particle generation. Furthermore, according to this embodiment, particle generation can be reduced by forming the valve body side contact surface 21x with cross-linked PTFE. Furthermore, according to this embodiment, particle generation can be reduced by forming the valve closing contact portion 41y and the valve body pressing contact portion 31y with cross-linked PTFE. Furthermore, according to this embodiment, particle generation can be reduced by forming the channel-forming body 41 with cross-linked PTFE.

[0031] For the constant pressure valves shown in Figures 1 and 2, a comparative experiment was conducted to verify the amount of particles generated when all components were made of PTFE. As a result, the constant pressure valve according to this embodiment reduced the amount of particles smaller than 15 nm to 1 / 10 in a steady-state control state compared to the comparative example. [Industrial applicability]

[0032] This invention is suitable for constant pressure valves in the semiconductor manufacturing field where precise flow control and high cleanliness are required. [Explanation of Symbols]

[0033] 11 Inflow channel 12 Outlet channel 13 Flow control channel 14 Valve body side pressurization chamber 14a Pressing member 14b Elastic member 14c breathing hole 15 Shaft-side pressurized chamber 15a Configuration Airport 15b Exhaust port 21 Valve body 21a Connection part 21b Contact part 21x Valve body side contact surface 22 Valve body side diaphragm 22a Thin wall part 22b Fixed part 30 Shaft-side member 31 shafts 31a Connection part 31b Contact part 31x Shaft-side contact surface 31y Valve body pressing contact part 32 Shaft-side diaphragm 32a Thick part 32b Thin wall part 32c Fixed part 40 Body 41 Body for forming flow channels 41x Valve seat side contact surface 41y Valve closure contact part 42 Valve body side 43 Shaft-side body

Claims

1. An inflow channel through which the fluid to be controlled flows, The outflow channel through which the controlled fluid flows out, A flow control channel located between the inflow channel and the outflow channel, A valve body arranged in the flow control channel, A valve body side diaphragm that displaces the valve body, A shaft that presses the valve body, A shaft-side diaphragm that displaces the aforementioned shaft and It has, The inflow passage is connected to one side of the valve body side diaphragm, and a valve body side pressurizing chamber is formed in the other side of the valve body side diaphragm. The outflow channel is connected to one side of the shaft-side diaphragm, and a shaft-side pressurizing chamber is formed in the other side of the shaft-side diaphragm. A constant pressure valve that maintains a constant outlet pressure due to the controlled fluid flowing out of the outlet passage, even when the inflow pressure due to the controlled fluid flowing in from the inflow passage fluctuates, by deforming the valve body side diaphragm and the shaft side diaphragm, The valve body has a valve body side contact surface formed perpendicular to the direction of movement of the valve body and the shaft. The shaft has a shaft-side contact surface formed perpendicular to the direction of movement of the valve body and the shaft. The flow control channel has a valve seat side contact surface formed perpendicular to the direction of movement of the valve body and the shaft. The valve body side contact surface or the valve seat side contact surface has a ring-shaped protruding valve closing contact portion formed therein. The valve body side contact surface or the shaft side contact surface has a ring-shaped protruding contact portion for pressing the valve body. The body is composed of a flow path forming body, a valve body side body, and a shaft side body. The flow path forming body forms the inflow flow path, the outflow flow path, and the flow rate control flow path. The valve body side body forms the valve body side pressurizing chamber, The shaft-side body forms the shaft-side pressurizing chamber, The valve body side diaphragm is fixed to the flow path forming body by the valve body side body, The shaft-side diaphragm is fixed to the flow path forming body by the shaft-side body, The shaft and the shaft-side diaphragm are formed from a composite material formed by joining PTFE and cross-linked PTFE. The shaft-side diaphragm is formed from the PTFE, The shaft-side contact surface is formed by the cross-linked PTFE, The valve body and the shaft body are formed from PTFE. The flow path forming body is formed by PFA, The cross-linked PTFE, which was bonded to the flow path forming body by resistance heating, was used as the valve seat side contact surface. A constant pressure valve characterized by the following features.

2. The valve body and the valve body side diaphragm are formed from the composite material, The valve body side diaphragm is formed from the PTFE, The valve body side contact surface is formed from the cross-linked PTFE. The constant pressure valve according to feature 1.

3. The valve body side contact surface is formed from the cross-linked PTFE. The constant pressure valve according to feature 1.

4. The valve closing contact portion and the valve body pressing contact portion are formed from the cross-linked PTFE. The constant pressure valve according to feature 1.

5. The valve seat side contact surface is formed by the sheet-like crosslinked PTFE. The valve closing contact portion is formed on the valve body side contact surface. The constant pressure valve according to feature 1.

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