JPH09217845A - Diaphragm valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a shock of a valve element on a valve seat without impairing response so as to press a valve element softly against a valve seat in order to suppress particles from producing by reducing the acceleration of a piston by a spring using a damper spring when the valve is closed so as to damp a pressing force. SOLUTION: A diaphragm 21 of a diaphragm valve is made of PTFE, and forms and annular thin film part 23 formed in an upward spherical shape integrally with it around a valve element 22 located at the center of it and also forms a cylindrical holding part 24 integrally with it around the annular thin film part 23. Also the diaphragm valve is of the normally closed type, and its piston 11 is excited downward by a spring 14 installed into the upper chamber 9a of a cylinder 9 so as to brought a valve element 22 connected to a lower side rod 12 in contact with a valve seat 5. In addition, a damper spring 20 is provided in the lower chamber 9b of the cylinder 9. Thus, when the valve is closed, the valve element 22 can be pressed softly against the valve seat 5 so as to suppress particles from producing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin diaphragm valve used in a wet station such as a silicon wafer cleaning device or an etching device in a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art An example of a conventional resin diaphragm valve for the above-mentioned use will be described with reference to FIG. 3, in which a valve box 1 is provided with a fluid inflow passage 2 on one side and a fluid outflow passage 3 on the other side. There is. The outlet side of the fluid inflow passage 2 is opened perpendicularly to the center of the valve box 1, the opening periphery is expanded to form a protrusion 4, and the tip of the protrusion 4 forms a valve seat 5 having a small arc-shaped cross section. ing. Reference numeral 6 denotes a PTFE diaphragm, which has a valve body 6a to be crimped to the valve seat 5 in the center as shown in FIG. 4, and an annular thin film portion 6b integrally formed around the lower end of the valve body 6a.
And a cylindrical holding portion 6c integrally formed around the annular thin film portion 6b. In FIG. 3, reference numeral 7 is a diaphragm retainer for retaining the cylindrical holding portion 6c of the diaphragm 6 fitted in the groove 8 around the inside of the valve box 1, and this diaphragm retainer 7 is below the case 10 of the cylinder 9 of the valve drive portion. Since the case 10 is integrally provided on the end face and the case 10 is fastened and fixed to the upper surface of the opening of the valve box 1, the tubular holding portion 6c is provided with the groove 8a.
It is pressed and fixed inside. The valve body 6 a at the center of the diaphragm 6 is connected to the lower rod 12 of the piston 11. A spring 14 is installed in the upper chamber 9a between the piston 11 of the cylinder 9 and the cap 13, and
1 is biased downward. Reference numeral 15 is an air inlet to the lower chamber 9b of the cylinder 9, and 16 is the upper chamber 9a of the cylinder 9.
And the air communication port to the outside.

The diaphragm valve thus constructed is
When air is introduced into the lower chamber 9b of the cylinder 9, the piston 11 rises against the spring 14 and the lower rod 1
The valve body 6a in the center of the diaphragm 6 connected to 2 is opened apart from the valve seat 5, and when the air is removed from the lower chamber 9b of the cylinder 9, the piston 11 is urged by the spring 14 to descend, The valve body 6a at the center of the diaphragm 6 connected to the lower rod 12 is a normally closed type in which the valve body 6a is crimped to the valve seat 5 to close the valve.

By the way, the above-mentioned conventional diaphragm valve is
Although the diaphragm 6 is made of PTFE in consideration of chemical resistance, the pressing force of the piston 11 when the valve is closed is transmitted to the valve body 6a as it is, a large impact is generated, and particles are easily generated. Further, since the fluid pressure is not applied to the annular thin film portion 6b at the moment of closing the valve body 6a, the valve body 6a
The axial thrust of the valve is increased and the variable load is increased, so that the valve seat 5 is suddenly subjected to a force and particles are generated. Furthermore, when the valve is opened and closed several tens of times, the valve body 6a
It follows that the root of the inner peripheral portion of the annular thin film portion 6b is subjected to a bending test due to the vertical movement of the annular thin film portion 6b, and bending stress is concentrated on this portion.
The root portion of the inner circumference of b is pulled, whitening is likely to occur from the initial state, and particles are generated from here.

On the other hand, with the recent progress of high integration of semiconductors, a wet station such as a particle-free cleaning device for LSI manufacturing and an etching device is required more and more, and the diaphragm valve made of resin used for this is also a particle station. As a free valve is required, a resin diaphragm valve in which particles are generated each time the valve is opened and closed cannot be handled.

[0006]

SUMMARY OF THE INVENTION Therefore, the present invention is to provide a resin diaphragm valve capable of suppressing the generation of particles each time the valve is opened and closed.

[0007]

A diaphragm valve of the present invention for solving the above-mentioned problems has a PTFE seat on a valve seat surface of a valve box.
In the normal-closed type resin diaphragm valve that shuts off the fluid flowing inside the valve box by pressing the made diaphragm with the piston biased by the spring loaded in the upper chamber of the cylinder, A damper spring is installed in the lower chamber, and the diaphragm has a central valve body, an annular thin film portion integrally formed around the valve body, and a cylindrical holding portion integrally formed around the annular thin film portion. And the annular thin film portion is curved in a spherical shape upward in cross section, and the root portion of the inner periphery is connected substantially perpendicularly to the upper surface of the valve body, and the root portion of the outer periphery is the inner peripheral surface of the cylindrical holding portion. It is characterized in that it is connected almost vertically to the upper edge.

In this diaphragm valve, the diameter of the root portion of the outer periphery of the annular thin film portion curved upward in section of the diaphragm is A, the diameter of the root portion of the inner periphery is C, and the diameter of the valve body is It is preferable that B is A>B> C, and it is preferable that the ratio of A and B is as small as possible.

In the diaphragm valve constructed as described above, since the damper spring is installed in the lower chamber of the cylinder of the valve drive unit, when the valve is closed, the acceleration of the piston is reduced by the damper spring and the pressing force is reduced. Is dampened, and the impact of the valve body on the valve seat can be reduced without impairing the response. Therefore, the valve body can be softly pressed onto the valve seat and the generation of particles can be suppressed. In addition, the annular thin film portion of the diaphragm is curved in a spherical shape upward in cross section,
The root part of the inner circumference is connected almost vertically to the upper surface of the valve body, and the root part of the outer circumference is connected almost perpendicularly to the upper edge of the inner peripheral surface of the cylindrical holding part. Is elastically deformed only in the spherically curved part, and the root parts of the inner and outer circumferences remain almost vertical. Therefore, no bending stress is generated, the root portion is not whitened at all, and the generation of particles is prevented.

Further, the diameter A of the root portion of the outer periphery of the annular thin film portion curved upward in the spherical shape of the diaphragm, the diameter C of the root portion of the inner periphery, and the diameter B of the valve body are given by A>B> In the case where the ratio is set to C and the ratio of A and B is made as small as possible, the fluctuating load when the valve is closed becomes small, the pressing force of the valve body against the valve seat becomes small, and Is suppressed. Moreover, when the valve is opened, the repulsive force when deforming the annular thin film portion that is curved upward in cross section is offset by the force that pulls up the valve body, and the axial thrust of the valve body is reduced.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the diaphragm valve of the present invention will be described with reference to FIG. In FIG. 1, the same parts as those in FIG. 3 are designated by the same reference numerals. Further, in FIG. 1, the left half is in the valve closed state and the right half is in the valve open state. The diaphragm valve of the present invention is different from the conventional diaphragm valve in that a damper spring 20 is loaded in the lower chamber 9b of the cylinder 9.
The conventional diaphragm 6 directly involved in opening and closing the valve is replaced with the diaphragm 21.

The diaphragm 21 in the diaphragm valve of the present invention is made of PTFE, and has a central valve body 22, an annular thin film portion 23 integrally formed around the valve body 22, and the surrounding of the annular thin film portion 23. Cylindrical holding portion 24 formed integrally with the
2, the annular thin-film portion 23 is bent in a spherical shape upward in cross section as shown in FIG. 2, and the root portion 25 of the inner circumference is connected almost vertically to the upper surface of the valve body 22, and the root portion 2 of the outer circumference is formed.
6 is connected substantially vertically to the upper edge of the inner peripheral surface of the cylindrical holding portion 24.

Further, in this embodiment, in particular, FIG.
The diameter of the root portion 26 on the outer periphery of the annular thin film portion 23 is A, and the diameter of the root portion 25 on the inner periphery is C, as shown in FIG.
As the diameter B of A is such that A>B> C,
The ratio of A and B, that is, A / B, is set to be small.

The diaphragm valve of the embodiment constructed as described above is a normal / close type, and the piston 11 is normally driven by a spring 14 inserted in the upper chamber 9a of the cylinder 9 as shown in the left half of FIG. Urged downwards,
The valve body 22 at the center of the diaphragm 21 connected to the lower rod 12 is crimped to the valve seat 5 to close the valve. When air is supplied to the lower chamber 9b of the cylinder 9, the piston 11 rises against the spring 14 as shown in the right half of FIG. 1, and the central valve body 22 of the diaphragm 21 connected to the lower rod 12 Is opened apart from the valve seat 5.

In the diaphragm valve of the embodiment for performing such a valve opening / closing operation, since the damper spring 20 is inserted in the lower chamber 9b of the cylinder 9 of the valve drive portion, the piston 11 by the spring 14 is closed when the valve is closed. The acceleration of is reduced by the damper spring 20 and the pressing force is attenuated, and the impact of the valve body 22 on the valve seat 5 can be reduced without impairing the response. Therefore, the valve body 22 can be softly crimped to the valve seat 5. Therefore, the generation of particles can be suppressed.

Further, the annular thin film portion 23 of the diaphragm 21
Is curved in a spherical shape with an upward cross section, the root portion 25 of the inner circumference is connected substantially vertically to the upper surface of the valve body 22, and the root portion 26 of the outer circumference is connected substantially vertically to the upper edge of the inner peripheral surface of the cylindrical holding portion 24. Therefore, when the valve is opened / closed, the annular thin film portion 23 is elastically deformed only in the spherically bent portion, and the root portions 25, 2 of the inner and outer circumferences are formed.
No. 6 remains in a substantially vertical state as shown in FIG. Therefore, no bending stress is generated and the root portions 25, 2
In No. 6, whitening does not occur at all, and generation of particles is prevented.

Further, as in the above embodiment, the diameter A of the root portion 26 on the outer circumference of the annular thin film portion 23 curved upward in cross section of the diaphragm 21 and the diameter C of the root portion 25 on the inner circumference thereof.
And the diameter B of the valve body 22 as shown in FIG.
In the case where B> C is set and the ratio of A and B is set small, the variable load when the valve is closed is small, and the pressing force of the valve body 22 against the valve seat 5 is small. Generation of particles is suppressed. Moreover, when the valve is opened, the repulsive force P ₁ ′ when deforming the annular thin film portion 23 bent in an upward arc-shaped cross section is canceled by the force P ₁ for pulling up the valve body 22, and the axial thrust of the valve body 22 is reduced. To be done.

[0018]

As can be seen from the above description, in the diaphragm valve of the present invention, when the valve is closed, the acceleration of the piston due to the spring is reduced by the damper spring so that the pressing force is attenuated, and the impact of the valve element on the valve seat is reduced. Can be reduced without impairing the response, so that the valve body can be softly pressed against the valve seat, and the generation of particles can be suppressed.
Also, when the valve is opened and closed, the annular thin film part elastically deforms only in the spherically curved part, and the root parts of the inner and outer peripheries remain almost vertical, so bending stress does not occur and the root part does not Generation of particles is prevented without any whitening. Further, the diameter A of the root portion of the outer periphery of the annular thin film portion
And the diameter C of the root portion of the inner circumference and the diameter B of the valve body, A>B>
With C and A / B reduced, the fluctuating load when the valve is closed is small, the pressing force of the valve body against the valve seat is small, particle generation is suppressed, and when the valve is open. The repulsive force when deforming the annular thin film part,
This is offset by the force of pulling up the valve body, and the axial thrust of the valve body is reduced.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a diaphragm valve of the present invention, in which a left half portion is in a valve closed state and a right half portion is in a valve open state.

FIG. 2 is an enlarged vertical sectional view showing a diaphragm in the diaphragm valve of FIG.

FIG. 3 is a vertical cross-sectional view showing a closed state of a conventional diaphragm valve.

FIG. 4 is an enlarged vertical sectional view showing a diaphragm in the diaphragm valve of FIG.

[Explanation of symbols]

 1 Valve box 2 Fluid inflow passage 3 Fluid outflow passage 5 Valve seat 9 Cylinder 9a Cylinder upper chamber 9b Cylinder lower chamber 11 Piston 14 Spring 20 Damper spring 21 Diaphragm 22 Central valve body 23 Annular thin film part 24 Cylindrical holding part 25 Annular thin film Root part of the inner circumference of the part 26 Root part of the outer circumference of the annular thin film part A Diameter of the root part of the outer circumference of the annular thin film part B Diameter of the central valve body C Diameter of the root part of the inner circumference of the annular thin film part

Claims (2)

[Claims] 1. A normally closed type in which a PTFE diaphragm is pressed against a valve seat surface of a valve box by a piston urged by a spring loaded in the upper chamber of a cylinder to shut off a fluid flowing inside the valve box. In the resin diaphragm valve of, a damper spring is inserted in the lower chamber of the cylinder, the diaphragm is a central valve body, and an annular thin film portion integrally formed around the valve body,
Consisting of a tubular holding portion integrally formed around the annular thin film portion, wherein the annular thin film portion is bent in a spherical shape upward in cross section,
A diaphragm valve characterized in that the root portion of the inner circumference is connected to the upper surface of the valve body substantially vertically, and the root portion of the outer circumference is connected to the upper edge of the inner peripheral surface of the cylindrical holding portion substantially vertically. . 2. The diameter of the root portion of the outer periphery of the annular thin film portion curved upward in a spherical section of the diaphragm is A, the diameter of the root portion of the inner periphery is C, the diameter of the valve element is B, and A> B
2. The diaphragm valve according to claim 1, wherein the diaphragm valve is set to be> C and the ratio of A and B is set to be as small as possible.