JPH0627552B2 - Diaphragm valve - Google Patents

Description

The present invention relates to a diaphragm valve used in a piping line of an IC manufacturing apparatus.

(Prior Art) Instead of a diaphragm valve of the type that pushes the valve seat of the valve box with the tip of the valve stem to close the valve, the dead space in the valve box has recently been reduced to improve the ability to replace the gas flowing inside. In order to do so, a diaphragm valve that eliminates the valve rod and closes the valve by directly pressing the back surface of the diaphragm against the valve seat of the valve box has been developed and put into use.

In this type of diaphragm valve, as shown in FIG. 4, the upper surface of the diaphragm 3 is connected to the piston rod 5 of the air cylinder 7.
Or push the top of the diaphragm 3 onto the piston rod 5 of the air cylinder 7 as shown in FIG.
Push it in with the separated diaphragm push rod 4,
The back surface of the diaphragm 3 is pressed against the valve seat 2, and the diaphragm 3 and the tip of the piston rod 5 and the tip of the diaphragm 3 and the diaphragm push rod 4 are separated from each other. Due to the restoration of the piston 8, the piston 8 stops pushing the diaphragm 3 away from the upper surface of the diaphragm 3 and at the same time, the diaphragm 3 separates from the valve seat 2 by the spring force of the diaphragm 3 itself.

(Problems to be Solved by the Invention) By the way, since the diaphragm valve is mainly used in the piping line of the IC manufacturing apparatus, it is extremely strict against leakage of gas from the valve seat 2 when the valve is closed. Yes 10
^-8 Torrl / sec or less leakage is required to be suppressed.

Under such conditions, in the conventional diaphragm valve, the piston rod 5 or the diaphragm push rod 4 does not have a degree of freedom of rotation when the valve is closed, and for example, the valve seat sheet 2 cannot be horizontally processed during processing. If the inclination occurs, the tip end surface of the piston rod 5 or the diaphragm push rod 4 is parallel to the valve seat 2 and the diaphragm 3 is not pushed in, so that the valve seat 2 and the back surface of the diaphragm 3 can be sufficiently adhered. Therefore, the above-mentioned strict gas leakage value cannot be protected.

Therefore, in order to protect the above-mentioned strict gas leakage value, the conventional diaphragm valve requires strictness in the horizontalness of the upper surface when the valve seat sheet 2 of the valve box 1 is processed, and the center hole of the bonnet 6 and the piston rod 5 are required. Alternatively, a strict sliding tolerance with the diaphragm push rod 4 is required, and high processing accuracy is required. Furthermore, since the clearance between the bonnet 6 and the piston rod 5 or the diaphragm pushing rod 4 becomes smaller, a malfunction due to sticking or seizing occurs with the bonnet 6 when the piston rod 5 or the diaphragm pushing rod 4 operates, and smooth operation cannot be expected. .

Further, since the diaphragm 3 is simply formed in a dish-down shape, when the diaphragm 3 is crimped to the valve seat sheet 2 when the valve is closed, the outer peripheral side of the crimped portion is wavy (wrinkled). (Close to) occurred. That is, the outer peripheral side, which was in the inclined state when the valve was opened, was inevitably wavy (wrinkled) because it was deformed flat when the valve was closed.

Therefore, the present invention can uniformly press the back surface of the diaphragm against the upper surface of the valve seat, and can prevent sticking or seizure of the diaphragm pushing rod to the bonnet, and further corrugate the outer peripheral side of the diaphragm. It is intended to provide a diaphragm valve that does not cause (crease).

(Means for Solving the Problems) A diaphragm valve of the present invention for solving the above problems is
A diaphragm valve of the type that keeps the inside of the valve box clean by separating the inside of the valve box and the air cylinder for valve opening / closing operation with a diaphragm made of a thin metal plate, and the piston of the air cylinder abuts the lower end of the piston rod In the diaphragm valve that closes the valve by pressing the back surface of the diaphragm against the valve seat seat surface inside the valve box through the diaphragm push rod that slides on the hood inside, flatten the central part of the diaphragm. And an annular protrusion having an arcuate cross-section whose lower surface is upwardly projected and whose upper surface is upwardly projected on the outer peripheral side of the flat portion, and a spring for pushing up the diaphragm pushing rod when the valve is opened is built in the bonnet, and It is characterized in that a pivot is provided between the upper end of the diaphragm push rod and the end of the piston rod.

[Action]

In the diaphragm valve of the present invention configured as described above, the pivot is provided between the upper end of the diaphragm push rod and the end of the piston rod, and between the outer peripheral surface of the diaphragm push rod and the inner peripheral surface of the bonnet. Has a relatively large gap, the diaphragm push rod descends as the piston rod descends, and when the flat part of the diaphragm is pushed into the valve seat seat, the upper surface of the valve seat seat is Even if the diaphragm push rod is not assembled so that it is at a right angle to the valve seat, the diaphragm push rod presses the flat portion of the diaphragm against the valve seat seat within the gap between the diaphragm push rod and the bonnet. Allow to rotate along the slope,
The flat part of the diaphragm is pressed uniformly against the valve seat. Also, the bonnet inside the valve box has a built-in spring that pushes up the diaphragm push rod, so the diaphragm push rod is pushed up by the spring when the valve is opened, and the diaphragm push rod's own weight does not ride on the diaphragm, so the diaphragm is slightly restored. It will surely be restored by force. Furthermore, since the diaphragm push rod moves straight up and down when the valve is operating, the bonnet that guides the diaphragm push rod can have a large clearance with the diaphragm push rod, and therefore the sticking of the diaphragm push rod to the bonnet and the failure due to seizure can be prevented. Can be avoided. Further, when the flat portion of the diaphragm is pressed uniformly against the valve seat seat, the width of the annular protrusion having the arcuate cross section in which the lower surface is recessed upward and the upper surface is protruded upward is substantially horizontal in the radial direction. Wrinkling (wrinkling) does not occur on the outer peripheral side of the flat portion. In addition, since the elastic restoring force is stored in the annular protruding portion whose width is narrowed, the width of the annular protruding portion is rapidly expanded when the valve is opened, so that the diaphragm can be smoothly and reliably returned to the ascended state.

〔Example〕

An embodiment of the diaphragm valve of the present invention will be described with reference to FIG. 1. Reference numeral 1 is a valve box having a fluid inlet passage 1a and a fluid outlet passage 1b, and a valve seat 2 is provided at the inlet periphery of the fluid outlet passage 1b. Is provided. Reference numeral 3 is a diaphragm, and the central portion of the diaphragm 3 is made flat, and the lower surface of the flat portion is inclined upward on the outer peripheral side (inclined when the valve is open) and the upper surface of the diaphragm is projected upward in an arcuate annular shape. 3a is provided, and the peripheral portion is clamped and clamped between the bonnet 6 and the seal ring 9 inserted in the cylindrical vertical portion 1'of the valve box 1. 4 is a diaphragm push rod, a recess 6a of the bonnet 6
Is inserted in the center hole 6b at the bottom of the. A flange 4a is provided around the upper tip of the diaphragm pushing rod 4,
A spring 10 is fitted around the diaphragm pushing rod 4 between the flange 4 a and the bottom of the recess 6 a of the bonnet 6. Reference numeral 7 denotes an air cylinder, the cylinder cover 7a of which is screwed onto the outer periphery of the cylindrical vertical portion 1'of the valve box 1, whereby the peripheral edge portion of the diaphragm 3 is fastened to the seal ring 9 via the bonnet 6. Reference numeral 8 denotes a piston of the air cylinder 7, the piston rod 5 of which penetrates the center hole 7b of the cylinder cover 7a. The O-ring 11 is provided in the groove on the outer periphery of the piston 8 and the O-ring is provided in the groove of the outer periphery of the piston rod 5. 12 are fitted into each other and the sliding portions are sealed. The upper rod 13 of the piston 8 is a hole 1 communicating with the inlet port 14 of the air cylinder 7.
5, the air passage 16 is provided in the center of the upper rod 13 and the piston 8, and the lower chamber 1 of the air cylinder 7 is inserted.
It is connected to 7. A spring 19 for urging the piston 8 downward is installed in the upper chamber 18 of the air cylinder 7. A pivot 20 is provided between the upper end of the diaphragm push rod 4 and the end of the piston rod 5. In the case of this example, the pivot 20 is configured by providing a hemispherical convex portion 21 in the center of the upper end surface of the diaphragm push rod 4, and is in point contact with the front end surface of the piston rod 5.
As a result, the degree of freedom of rotation is given to the diaphragm push rod 4 within the range of the fitting clearance between the diaphragm push rod and the center hole 6b of the bonnet 6.

In the diaphragm valve constructed in this way, the piston 8 is normally urged downward by the spring 19, and the piston rod 5 pushes down the diaphragm pushing rod 4 against the spring 10 via the pivot 20. The lower end surface uniformly presses the back surface of the flat portion of the diaphragm 3 against the upper surface of the valve seat seat 2 to close the valve.
When the valve is closed, the width of the annular protruding portion 3a having an arcuate cross section whose upper surface projects upward and whose upper surface projects upward is narrowed substantially horizontally in the radial direction, so that waviness (wrinkling) occurs on the outer peripheral side of the flat portion. It never happens. And the piston 8 is O
Even if the piston rod 5 is tilted by the restraining force received from the air cylinder 7 and the cylinder cover 7a via the rings 11 and 12, the pivot 20 prevents the diaphragm push rod 4 from pushing the diaphragm 3 obliquely.

To open the closed valve, the lower port 17 of the air cylinder 7 is passed through the air passage 16 by the inlet port 14.
Pressure air is introduced to push the piston 8 upward against the spring 19. By doing so, the diaphragm pushing rod 4 which is in contact with the tip end surface of the piston rod 5 via the pivot 20 is pushed upward by the spring 10, and the weight of the diaphragm pushing rod 4 does not ride on the diaphragm 3 as a result. Is smoothly and surely lifted and restored by the elastic restoring force of the annular protrusion 3a whose width is narrowed when the valve is closed, and the valve is opened.

However, since the bonnet 6 that guides the diaphragm push rod 4 has a large clearance with the diaphragm push rod 4 when the valve is opened and closed, the diaphragm push rod 4 is
It is possible to avoid a failure due to sticking or seizing on the hood 6 of

In the above embodiment, the pivot 20 provided between the upper end of the diaphragm pushing rod 4 and the tip of the piston rod 5 is constituted by the hemispherical convex portion 21 at the center of the upper end face of the diaphragm pushing rod 4. , Not limited to this,
On the contrary, as shown in FIG. 2, the upper end surface of the diaphragm push rod 4 may be made flat, and the hemispherical convex portion 22 may be provided at the center of the front end surface of the piston rod 5 to form the pivot 20 '. . Further, as shown in Fig. 3, a steel ball 23 may be arranged between the upper end surface of the diaphragm pushing rod 4 and the front end surface of the piston rod 5 to form the pivot 20 ". In this case, the diaphragm is used. A peripheral wall 24 is provided around the top end of the push rod 4 to surround the end of the piston rod 5, and the conical groove 2 is formed in the center of the end face of the piston rod 5.
5 is provided to prevent the steel ball 23 from being fitted and moved.

〔The invention's effect〕

As can be seen from the above description, the diaphragm valve of the present invention does not push the diaphragm obliquely, and the back surface of the diaphragm can be pressed uniformly against the upper surface of the valve seat sheet so that the diaphragm seats sufficiently. The strict gas leakage value required as a valve of the piping line can be protected. Further, the diaphragm valve of the present invention can avoid the sticking of the diaphragm pushing rod to the bonnet, the obstruction due to seizure, etc., and the opening / closing operation of the valve can be always smooth.
Further, when the flat portion of the diaphragm is pressed uniformly against the valve seat seat, the width of the annular protrusion having the arcuate cross section in which the lower surface is recessed upward and the upper surface is protruded upward is substantially horizontal in the radial direction. Wrinkling (wrinkling) does not occur on the outer peripheral side of the flat portion. In addition, since the elastic restoring force is stored in the annular protruding portion whose width is narrowed, the width of the annular protruding portion is rapidly expanded when the valve is opened, so that the diaphragm can be smoothly and reliably returned to the ascended state.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the diaphragm valve of the present invention, FIG. 2 and FIG. 3 are longitudinal sectional views of essential parts showing partially modified examples, and FIGS. 4 and 5 are conventional drawings. FIG. 3 is a vertical sectional view showing the diaphragm valve of FIG. 1 ... Valve box, 2 ... Valve seat, 3 ... Diaphragm,
3a ... annular protrusion, 4 ... diaphragm push rod, 5 ...
... Piston rod, 6 ... bonnet, 7 ... air cylinder, 8 ... piston, 10 ... spring, 2
0,20 ', 20 "... pivot

Claims (1)

[Claims] 1. A diaphragm valve of a type for keeping the inside of the valve box clean by isolating the inside of the valve box and the air cylinder portion for valve opening / closing operation by a diaphragm made of a thin metal plate, and a piston rod by a piston of the air cylinder. In a diaphragm valve that closes the valve by pressing the back surface of the diaphragm against the valve seat seat surface inside the valve box through a diaphragm push rod that contacts the lower end and slides on the bonnet inside the valve box, A flat central portion of the diaphragm is provided with an annular protrusion with an arcuate cross section in which the lower surface projects upward and the upper surface projects upward on the outer peripheral side of the flat portion, and a spring that pushes up the diaphragm push rod when the valve is opened. It is built in the bonnet, and a pivot is provided between the tip of the upper portion of the diaphragm push rod and the tip of the piston rod. Iyafuramu valve.