JPH0566376U - Metal diaphragm valve - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a metal diaphragm valve which can obtain good sealing characteristics with a small driving force. A vertex angle θ of a conical surface 23 whose top is a point contact portion 21 between a drive shaft 18 and a pressing member 8 and whose bottom is a circular contact portion 22 between a metal diaphragm 6 and a valve seat 5 is 40 degrees. It is characterized by the above setting. Since the apex angle of the conical surface having the point-shaped abutting portion as the top and the circular-shaped abutting portion as the bottom is set to 40 ° or more, the alignment of the drive system is improved and the output of the operating portion is enhanced. The sealing characteristics are improved without the need.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a metal diaphragm valve used in a distribution system for ultra-high purity gas or strongly corrosive gas in the semiconductor industry, for example.

[0002]

[Prior Art]

 The valves provided in the above-mentioned flow system are designed so that the valve seat, which is made of a metal material, and the valve box are in direct contact with the metal diaphragm, and the fluid contact surfaces are all mirror finished to a submicron level. However, in order to further improve the sealing characteristic between the valve seat and the metal diaphragm, the applicant of the present invention proposed an improvement measure in Japanese Patent Application No. 61-258515. This proposal is characterized in that it is provided with a means for bringing the metal diaphragm into pressure contact with the valve seat with a uniform sealing surface pressure in cooperation with the valve drive member material. As shown in FIGS. 5A, 5B, and 5C, the pressing member b that contacts the metal diaphragm a is configured to be elastically deformable, and the spring member that biases the pressing member b in the closing direction. A device provided with c and a device provided with an automatic centering mechanism d linked with the pressing member b are disclosed.

[0003]

[Problems to be solved by the device]

 The above-mentioned conventional example is gradually put into practical use, but according to the subsequent research, those having the above-mentioned elastically deformable pressing member and spring member have a limited amount of deformation, and the above-mentioned automatic centering mechanism. Has a linear contact portion between a conical concave surface and a spherical convex surface, it has been clarified that the operation is not smooth. All of these had an adverse effect on the centering function, and therefore there were many variations in the amount of leakage, and a larger driving force was required for stable and good sealing.

The present invention has been made to solve the above problems, and provides a metal diaphragm valve which can obtain a good sealing characteristic with a small driving force and can be driven by a small operating portion. With the goal.

[0005]

[Means for Solving the Problems]

 The present invention relates to a metal diaphragm valve provided with a pressing member that presses a metal diaphragm against a valve seat in cooperation with a drive shaft, and a point-shaped contact portion is provided between the drive shaft and the pressing member. The apex angle of the conical surface having the contact portion as the top and the circular contact portion between the metal diaphragm and the valve seat as the bottom is set to 40 degrees or more.

[0006]

[Action]

 In the above structure, the point-like contact portion is provided between the drive shaft and the pressing member to improve the aligning property, and the point-like contact portion serves as the apex of the metal diaphragm and the valve seat. Since the apex angle of the conical surfaces whose bottoms are the circular abutting portions that abut each other, the apex angle is set to 40 degrees or more, so that the sealing characteristics are improved without increasing the operating portion output.

[0007]

【Example】

 The present invention will be described below with reference to an embodiment shown in FIGS.

In FIG. 1, a main body 1 of a metal diaphragm valve is provided with an inflow passage 2, an outflow passage 3, and a recess 4 in which the inner ends of both of these flow passages 2 and 3 open to the bottom. ing. An annular valve seat 5 is integrally provided on the bottom of the recess 4 at the periphery of the opening of the inflow passage 2. In the free state, the dish-shaped metal diaphragm 6 has a concave central portion that faces the valve seat 5 so that it can come into contact with and separate from the valve seat 5, and the peripheral edge portion is sandwiched between the bottom portion of the concave portion 4 and the support member 7. In the through hole (see FIG. 2) of the support member 7, a pressing member 8 whose one end abuts against the metal diaphragm 6 is fitted so as to be displaceable within a predetermined axial range. A ball 9 is supported on the other end of the pressing member 8. Both the main body 1 and the metal diaphragm 6 are made of a corrosion-resistant metal material, and the entire surface in contact with the fluid is mirror-finished on the submicron level.

The operation unit 10 also includes a case 11 having one end screw-engaged with the recess 4 and a cover 12 having one end fluid-tightly connected to the other end of the case 11. An air supply port 13 is opened at the other end of the cover 12 and a piston 14 is fluid-tightly and slidably fitted therein. A pressure chamber 15 is formed on one side (the case 11 side) in the axial direction of the piston 14, and a compression spring 16 is internally provided on the other side (the cover 12 side). The piston 14 integrally includes a stem 17 and a drive shaft 18, which are concentric and extend in opposite directions. The stem 17 and the drive shaft 18 are fluid-tightly and slidably fitted to the cover 12 and the case 11, respectively. The stem 17 has a communication hole 19 that connects the air supply port 13 and the pressure chamber 15. The drive shaft 18 supports a spacer 20 having a plane contact surface with the ball 9. The contact surface of the spacer 20 may be a concave surface having a small curvature.

Then, as shown in FIG. 2, a cone having a point-shaped contact portion 21 between the ball 9 and the spacer 20 as a top and a circular contact portion 22 between the valve seat 5 and the metal diaphragm 6 as a bottom. Assuming the surface 23, each part is set so that the apex angle θ is 40 degrees or more. Next, the operation of the above embodiment will be described.

When the pressure of the operating air supplied from the air supply port 13 to the pressure chamber 15 through the communication hole 19 rises, the piston 14 is displaced in the compression direction of the compression spring 16. As a result, the pressing force in the closing direction applied through the drive shaft 18, the spacer 20, the ball 9 and the pressing member 8 is reduced, so that the metal diaphragm 6 is separated from the valve seat 5 by the self-restoring force. The inflow passage 2 and the outflow passage 3 communicate with each other, so that the valve is opened.

When the air pressure in the pressure chamber 15 decreases, the restoring force of the compression spring 16 moves the piston 14, and hence the drive shaft 18, in the closing direction, and the metal diaphragm 6 is moved through the ball 9 and the pressing member 8 to the valve seat. When the valve is pressed against 5, the valve is closed as shown.

In this case, since the dot-shaped contact portion 21 is provided between the drive shaft 18 and the pressing member 8 as described above, the elastically deformable member or the linear contact portion is provided in the aligning mechanism. Compared with the conventional example, the centering property is significantly improved, and the apex angle θ of the conical surface 23 is set to 40 degrees or more, so that the sealing characteristics are improved without increasing the output of the operating section 10. Be improved.

That is, according to the experiments conducted by the present inventors, in FIG. 3, the apex angle θ of the conical surface 23 and the valve seat pressing force applied to the diaphragm 6 by the operating section 10 via the pressing member 8 are shown. As shown by the relationship with F, the pressing force F required to obtain the desired sealing characteristics is stable and greatly reduced in the region of θ ≧ 40. Further, it is not necessary to make the operating unit 10 larger than the above-mentioned conventional example, and the leakage rate is 2 × 10 ⁻¹¹ with good reproducibility even in the leakage test with He. It could be maintained below Torr.l / sec.

The present invention is not limited to the above-described embodiment, and a projection 24 may be provided on the pressing member 8 instead of the ball 9 as shown in FIG. 4 (A), for example. Alternatively, the ball 9 may be provided on the spacer 20 side instead of being provided on the pressing member 8 as shown in FIG. Other various modifications and applications are possible within the scope of the gist of the present invention.

[0016]

[Effect of the device]

 As described above, according to the present invention, it is possible to provide a metal diaphragm valve which can obtain good sealing characteristics with a small driving force and can be driven even by a small operating portion.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing an enlarged main part of the embodiment.

FIG. 3 is a diagram illustrating an experimental result of the example.

FIG. 4A and FIG. 4B are enlarged partial cross-sectional views showing different modifications of the main part of the same embodiment.

5 (A), (B) and (C) are partial cross-sectional views showing different main parts of a conventional example.

[Explanation of symbols]

5 ... Valve seat, 6 ... Metal diaphragm, 8 ... Pressing member, 9
... Ball, 18 ... Drive shaft, 20 ... Spacer, 21 ... Spotted contact portion, 22 ... Circular contact portion, 23 ... Cone surface, θ ... Apex angle

Claims (1)

[Scope of utility model registration request] 1. A metal diaphragm valve provided with a pressing member for pressing a metal diaphragm against a valve seat in cooperation with a drive shaft, wherein a dot-shaped contact portion is provided between the drive shaft and the pressing member. The apex angle of the conical surface having the contact portion as the top and the circular contact portion between the metal diaphragm and the valve seat as the bottom is 40.
A metal diaphragm valve characterized by being set more than once.