JPH0160712B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to the improvement of a diaphragm seal type valve, which is mainly used in supply and discharge pipelines for high-purity gas in semiconductor manufacturing equipment, nuclear power plants, etc. It is something that

(Prior Art) Diaphragm seal type valves are often used in pipelines handling high-purity gas in semiconductor manufacturing equipment and the like, which are designed to eliminate gas leakage from spindle gland packings.

FIG. 3 shows an example of a conventional diaphragm seal type valve, in which a plug 3 is inserted into the plug chamber 2 of the housing 1, and the periphery of the diaphragm 4 disposed above the plug 3 is inserted into the bonnet nut 5. The stopper chamber 2 is sealed by tightening the stopper. Further, the valve is closed by moving the spindle 6 downward, pushing down the diaphragm 4, and placing the stopper 3 on the stopper seat 7. Also, by moving the spindle 6 upward, the elastic force of the spring 8 closes the valve. When the stopper 3 is removed from its seat, the valve becomes open.

The above-mentioned diaphragm seal type valve can completely eliminate fluid leakage from the stopper chamber 2, and the spindle can be operated very smoothly, so it has excellent practical utility.

(Problems to be Solved by the Invention) However, this type of diaphragm seal type valve still has problems that need to be improved. For example, as shown in FIG. 3, since a spring 8 is disposed in the stopper chamber 2 to bias the stopper 3 in the opening direction, a dead space inevitably occurs in the stopper chamber 2. do.

However, if a dead space exists in the stopper chamber 2, fluid gas tends to remain therein, and in particular, since a bag-shaped dead space is formed above the fluid passage 9, once light gas is trapped, It is almost impossible to eliminate this naturally. Furthermore, if there is a dead space within the stopper chamber 2, unavoidable impurities mixed into the fluid will be accumulated therein.

Therefore, if gas remains in the dead space, gas purity will inevitably decrease in the pipe line through which different gases pass. Furthermore, even if the pipe line is dedicated to one type of gas, purge gas from when the pipe line is repaired will remain, reducing the purity of the gas that flows thereafter. Furthermore, if impurities accumulate in the dead space, they may be released into the gas at once for some reason, causing a significant drop in gas purity.

In addition, in the diaphragm seal type valve, metal parts such as the metal diaphragm 4 and the stopper 3, and the stopper 3 and the spring 8, etc., are in contact with each other, so that metal particles generated by these sliding contacts may enter the fluid. This can lead to a decrease in gas purity.

On the other hand, for example, in recent semiconductor manufacturing,
The purity and mixing precision of the gases used are now required to be close to the ultimate value, and as a result, valves with structures that cause a decrease in gas purity, such as the conventional diaphragm seal type valves, in other words, plug chambers. It is not preferable to use a valve with a structure in which there is a dead space within the valve 2 or a structure in which metal parts come into contact with each other.

The present invention aims to solve the above-mentioned problem with the conventional diaphragm seal type valve, namely, the problem that due to the structure, a dead space is inevitably created in the stopper chamber 2, which results in a decrease in gas purity. This eliminates all dead space in the valve chamber to prevent residual gas and accumulation of impurities inside the valve, and eliminates contact between metal parts in the valve chamber to prevent the generation of metal particles. However, it is an object of the present invention to provide a diaphragm seal type fluid cut-off device that does not cause any gas leakage.

(Structure for Solving the Problems) The present invention includes a housing in which a plastic stopper is provided in a stopper chamber communicating with a fluid inlet and a fluid outlet; A diaphragm made of a shape memory alloy that seals the opening and, due to pseudo-elastic deformation due to pressure, rests against the stopper seat and blocks fluid; a plastic diaphragm that is disposed above the diaphragm so as to be able to rise and fall freely, and that abuts the diaphragm at the lower end. or rubber, and a spindle for seating the diaphragm against the stopper seat, and the restoring force due to the pseudoelastic properties of the shape memory alloy diaphragm causes the diaphragm to be released from the stopper seat when opened. This is the basic structure of the invention.

(Function) By lowering the spindle and pressing the diaphragm against the stopper seat with its tip, the shutoff opener is brought into a closed state.

Further, when the spindle is raised, the diaphragm is automatically unseated due to the restoring force due to the pseudo-elastic properties of the diaphragm itself, that is, the restoring force in the unseating direction, and the fluid cut-off/opening device becomes open.

(Example) Hereinafter, details will be explained based on an example of the present invention shown in the drawings.

FIG. 1 is a longitudinal sectional view of the first embodiment of the present invention, and in the figure, reference numeral 10 indicates a stainless steel housing;
11 is a fluid inlet, 12 is a fluid outlet, 13 and 14
15 is a fluid passage, 15 is a stopper seat, and 16 is a shallow recess forming a stopper chamber.

In addition, 17 is a Ni-
It is a diaphragm made of a so-called shape memory alloy made of Ti alloy, 18 is a spindle, and 19 is a piston for driving the spindle.

The plug seat 15 is made of synthetic resin, such as tetrafluoroethylene resin, and is fitted into the mounting hole 20. In this embodiment, the stopper seat 15 is made of synthetic resin and is formed separately from the housing 10.
Of course, it may be formed integrally with the housing 10.

The diaphragm 17, which also serves as an airtight material for the plug body and the plug chamber, is made of a Ni-Ti alloy. 20mmφ, thickness 0.19mm~0.21
mm, Af transformation temperature approximately 5°C) is used. The diaphragm 17 exhibits so-called pseudo-elastic properties at temperatures exceeding the set Af transformation temperature of 5° C., and undergoes pseudo-elastic deformation into the shape shown in FIG. 1 when pressed by the spindle 18. Also, spindle 1
8 by pulling up the stopper 15.
It generates a restoring force of about 20 to 25 kg in the direction of separating from the seat.
For example, at a restoring position of 1 mm, that is, at a point where the opening stroke of the spindle 18 is 1 mm, a restoring force of about 20 to 25 kg is exerted. In this example,
Although Ni-Ti alloy is used, Cu-Zn-Al
Of course, alloys such as Cu-Al-Be, Cu-Al-Ni, and Cu-Al-Ni may also be used. In addition, the transformation point temperature of the alloy used is -80℃, depending on the temperature of the fluid being handled.
The temperature is set at ~70℃.

The diaphragm 17 placed on the stopper seat 15 is
By tightening the cap nut 21, its outer periphery is attached to the housing 1 via the gasket 22 and presser foot 23.
It is pressed toward the 0 side, thereby maintaining the airtightness within the stopper chamber 16.

The spindle 18 is above the diaphragm 17,
It is arranged to be able to move up and down in the vertical direction, and a pressing body 24 made of synthetic resin, rubber, etc. is fitted to the lower end thereof. Further, a piston 25 is fixedly installed above the spindle 17, and by supplying operating air from an air inlet 26, the spindle 18 is pressed downward against the elastic force of a spring 27.

FIG. 2 is a longitudinal sectional view showing a second embodiment of the present invention, in which the pneumatic actuation method of the spindle in the first embodiment is replaced with a screw actuation method.

Next, the operation of the fluid cut-off device according to each of the embodiments described above will be explained.

When closing the shut-off device, actuating air is supplied into the piston cylinder 28 to press the spindle 18 downward, and the diaphragm 17 is pushed toward the stopper seat 15 via the pressing body 24 attached to its tip. press against. Diaphragm 17 made of Ni-Ti alloy
is used at a temperature slightly higher than the set Af transformation temperature (5℃), so
Due to the pseudo-elastic properties of the Ti alloy, it is deformed into a downwardly bulging state and rests on the stopper seat 15.

On the other hand, when opening, the piston cylinder 2
Release the air pressure inside 8. By releasing the air pressure,
The spindle 18 is pulled upward by the elastic force of the spring 27, and the diaphragm 17 is
Due to the pseudo-elastic properties of the Ni-Ti alloy, the depression shrinks and restores its shape to a flat plate, and is separated from the stopper seat 15 and opened. The temperature of the diaphragm 17 is
Although the temperature may be maintained at a temperature exceeding the Af transformation temperature using the heat quantity of the fluid itself, it is also possible to provide a heater (not shown) on the upper surface side of the diaphragm 17 and use this to heat the diaphragm 17. .

The operation of the second embodiment of the present invention is substantially the same as that of the first embodiment, and by pushing down the spindle 18 by rotating the handle 29, the diaphragm 17 is deformed into the state shown in FIG. 2 due to its pseudoelastic property. Then, it comes into contact with the stopper seat 15 and enters the closed state. Further, when the spindle 18 is pulled up, the recessed portion of the diaphragm 17 returns to its flat shape due to the pseudo-elasticity of the material itself, and the valve becomes open.

(Effects of the Invention) As described above, the present invention utilizes a diaphragm made of a shape memory alloy, and uses the restoring force of the diaphragm itself due to its pseudo-elastic properties to release the diaphragm from the stopper seat. The spring for returning the diaphragm as in the diaphragm seal type valve is completely unnecessary, and the dead space for the stopper chamber is significantly reduced.

As a result, there is no residual gas in the stopper chamber, making it possible to prevent a decrease in the purity of the fluid and to downsize the device.

Also, in the valve chamber, the shape memory alloy diaphragm and the plastic stopper are configured to sit against each other, so unlike previous diaphragm seal type valves, the metal parts do not touch each other in the valve chamber. There is no need to say that metal particles are generated by sliding contact.
As a result, the shutoff/opening device of the present invention does not cause metal particles to flow into the fluid, and is optimal when used in a pipe line that handles ultra-high purity gas.

Furthermore, since the alloy diaphragm rests on the plastic stopper, the two come into good and reliable contact when the valve is closed, greatly improving sealing performance.

However, since the diaphragm has a structure in which a plastic stopper and a plastic or rubber pressing body are in contact with each other on both sides of the diaphragm, the diaphragm is strongly held between the stopper and the pressing body when the valve is closed. In addition, the impact generated when opening and closing the valve is alleviated, and there is no possibility that the ultra-thin diaphragm will be damaged.

As mentioned above, the present invention has excellent practical utility.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a fluid cut-off/opening device according to a first embodiment of the present invention, and FIG. 2 is a longitudinal cross-sectional view of a fluid cut-off/opening device according to a second embodiment of the present invention. FIG. 3 is a longitudinal sectional view of a conventional diaphragm seal type valve. 10... Housing, 11... Fluid inlet, 12... Fluid outlet, 15... Stopper seat, 16... Stopper chamber, 17...
Shape memory alloy diaphragm, 18... spindle, 24... pressing body.

Claims (1)

[Claims] 1. A housing 1 in which a plastic stopper seat 15 is provided in a stopper chamber 16 that communicates with a fluid inlet 11 and a fluid outlet 12.
0; disposed above the stopper seat 15 and said stopper chamber 16;
A diaphragm 17 made of a shape-memory alloy that seals the upper opening and blocks fluid by abutting against the stopper seat 15 through pseudo-elastic deformation due to pressure; It has a press body 24 made of plastic or rubber that comes into contact with the diaphragm 17, and a spindle 18 that brings the diaphragm 17 into contact with the stopper seat 15. A fluid cut-off/opening device characterized in that the diaphragm 17 is unseated from the stopper seat 15 at certain times. 2. The fluid cutoff/opener according to claim 1, wherein the diaphragm 17 is made of a Ni-Ti alloy. 3. The fluid cutoff/opening device according to claim 1, wherein the diaphragm 17 is heated by a heater and maintained at a predetermined temperature.