JPS5917302B2 - Double seal valve for ultra-high vacuum - Google Patents

Description

Detailed Description of the Invention The present invention is applicable to particle accelerators and ultra-LSI devices that require ultra-high vacuum.
The present invention relates to a double seal type valve for ultra-high vacuum suitable for use in manufacturing equipment, nuclear fusion devices, etc.

As conventional all-metal valves for ultra-high vacuum, the first to
There are some as shown schematically in Figure 4.

In the valve shown in FIG. 1, a soft copper piece 1a is attached to the tip of a valve body 1 made of hard stainless steel, and the peripheral edge of the opening of a valve seat 2 made of hard stainless steel bites into this copper piece 1a. It looks like this.

In addition, in the valve shown in FIG. 2, a gold plate member 3a is wrapped around the distal end of the valve body 3 made of hard stainless steel, and this soft plate member 3a is wrapped around the tip of the valve body 3 made of hard stainless steel. It is pressed against the opening periphery of the valve seat 4.

Furthermore, in the valve shown in FIG. 3, a gold plate member 5a is attached to the springy stainless steel valve body 5, and this soft plate member 5a is attached to the opening peripheral edge of the hard stainless steel valve seat 6. It is designed to be pressed against the

The valve shown in Fig. 4 differs from the above three examples in that a springy copper ring 9 is interposed between the hard stainless steel valve body 7 and the valve seat 8, and each contact point is The engagement between the hard metal surface and the soft metal edge is made.

Considering the four types of valves mentioned above, all of them are combinations of soft metal and hard metal, and when the valve body and valve seat come into contact, a slight permanent deformation of the soft metal occurs. This fact is now used to seal the area.

However, such permanent deformation of soft metals tends to reach a limit in the narrow annular contact area between the valve body and the valve seat, thus shortening the life of the valve and
Even if minute dust is present in the contact area, it may cause leakage.
A further disadvantage is that the contact portion requires a movement mechanism that can be accurately reproduced for repeated movements.

On the other hand, it is known that if a highly elastic rubber-like elastomer is used as a sealing material in the contact area between the valve body and the valve seat, the above-mentioned drawbacks of metal sealing materials can be eliminated. However, when such an elastomer is used as a sealing material for an ultra-high vacuum valve, there is a drawback that hydrocarbon-based gas due to evaporation of the sealing material causes a decrease in the degree of vacuum.

The present invention aims to solve the above-mentioned problems in ultra-high vacuum valves by providing double sealing with a metal sealing material and an elastomer sealing material, and exhausting air from the space between them. The object of the present invention is to provide a double seal type valve for ultra-high vacuum, which improves sealing performance and durability, and can treat evaporated gas from an elastomer under ultra-high vacuum conditions.

Therefore, in the double seal type valve for imperial vacuum of the present invention, at the contact portion between the valve body and the valve seat, the metal surface along the periphery of the valve seat opening and the valve body metal surface in contact with the metal surface are superimposed. A metal seal for the high vacuum space is formed, and an elastomer seal of an elastomer material is formed between the valve body and the valve seat at a position spaced outwardly from the metal seal, and the metal seal and the elastomer seal are formed between the valve body and the valve seat. The feature is that an exhaust pump is provided which is connected to the intermediate space between.

Hereinafter, a double seal type valve for ultra-high vacuum as an embodiment of the present invention will be explained with reference to the drawings. Fig. 5 is a longitudinal sectional view showing its overall structure, and Fig. 6 is a diagram showing the valve body and valve seat. It is a partial sectional view which expands and shows a contact state.

As shown in FIG. 5, a flange portion 1 of an opening 10a formed in a container wall 10 whose interior is to be an ultra-high vacuum space 24.
0b, an L-shaped ultra-high vacuum valve 11 according to the present invention is attached, and the circular opening 12a of the valve seat 12 is aligned with the opening 10a of the container wall 10.

Further, a disc-shaped valve body 16 is attached to the tip of a valve stem 15 that is coaxially inserted into the cylindrical valve body 13 via a bearing 14.
is fixed, and a bellows-type sealing member 17 is provided between the valve body 15 and the inner wall of the valve body 13 to cover the bearing 14 so that the internal space of the valve body 13 does not communicate with the outside through the bearing 14. There is.

Furthermore, an opening 18 having a connecting flange 18a is provided in the side wall of the valve box 13.

As shown in FIG. 6, the contact portion between the valve body 16 and the valve seat 12 when the valve 11 is closed includes a flat metal surface 19a along the periphery of the valve seat opening 12a, and a flat metal surface 19a that is in contact with the metal surface 19a. A metal seal 19 for the ultra-high vacuum space 24 is formed with the flat metal surface 19b of the valve body 16, and at a position spaced outward from this metal seal 19,
An elastomer seal 20 made of a resilient elastomer material 20a such as polyimide or rubber is formed between the valve body 16 and the valve seat 12.

In the example shown in FIG. 6, the elastomer material 20a is attached to the valve body 16 so that the elastomer material 20a is pressed against the flat metal surface 20b of the valve seat 12. It is also possible to attach an elastomer sealant to the side.

An annular intermediate space 21 is formed between the cholera metal seal 19 and the elastomer seal 20 , and a passage 22 communicating with this intermediate space 21 is bored inside the valve seat 12 . An exhaust pump 23 such as an ion pump is connected to the outer open end.

Since the valve 11 of the present invention is configured as described above, when the valve stem 15 is in the open state by moving upward one time, the opening 18
A space 24 inside the container wall 10 is brought into an ultra-high vacuum state by a vacuum pump (not shown) connected to the container wall 10 .

Next, the valve body 15 is driven once to close the valve 11 as shown in FIG.
The intermediate chamber 21 between the metal seal 19 and the elastomer seal 20 at the contact point with the metal seal 20 is evacuated by the exhaust pump 23, and the vacuum pump connected to the opening 18 stops operating.

In this state, organic gas is generated from the elastomer material 20a in the elastomer seal 20 by evaporation into the vacuum intermediate space 21, but this organic gas is constantly exhausted from the intermediate space 21 by the exhaust pump 23. , even if the metal seal 19 is insufficient, the container wall 10
Therefore, the ultra-high vacuum state of this space 24 can be sufficiently maintained.

In addition, the elastomer seal 20 can withstand repeated use due to its properties, and the metal seal 19 can also withstand repeated use because contact between flat surfaces is sufficient, so this valve can withstand repeated use. The overall durability of 11 will be greatly improved.

Furthermore, metal seal 19 and elastomer seal 20
Both have the advantage that they do not require a movement mechanism that can accurately reproduce contact with repeated motions.

As described in detail above, according to the double seal type valve for ultra-high vacuum of the present invention, in addition to the elastomer seal, which originally has good sealing performance and is suitable for repeated use, an auxiliary metal seal is added. In addition, since the exhaust pump is connected to the intermediate space between the elastomer seal and the metal seal, organic gas generated from the elastomer seal material is prevented from entering the ultra-high vacuum space, and
This has the advantage of improving durability against repeated use, which can contribute to improving the performance of particle accelerators, nuclear fusion devices, and the like.

[Brief explanation of the drawing]

Figures 1 to 4 are partial cross-sectional views showing the contact area between the valve body and valve seat of a conventional valve, and Figures 5 and 6 are double seals for ultra-high vacuum as an embodiment of the present invention. Fig. 5 is a vertical sectional view showing the overall structure of the valve, and Fig. 6 is a partial sectional view showing the state of contact between the valve body and the valve seat on an enlarged scale. DESCRIPTION OF SYMBOLS 10... Container wall, 10a... Opening, 10b... Flange part, 11... L-shaped valve, 12... Valve seat, 1
2a...Opening, 13...Valve box, 14...Bearing, 1
5... Valve stem, 16... Valve body, 17... Bellows seal material, 18... Opening, 18a... Connection flange, 19... Metal seal, 19a, 19b...・Flat metal surface, 20... Elastomer seal, 20a・
... Elastomer material, 20b... Metal surface, 21...
Intermediate space, 22... passage, 23... exhaust pump, 24...-ultra high vacuum space.

Claims (1)

[Claims] 1. At the contact portion between the valve body and the valve seat, a metal surface along the periphery of the valve seat opening and a metal surface of the valve body in contact with the metal surface form a metal seal against the ultra-high vacuum space, and
An elastomer seal made of an elastomer material is formed between the valve body and the valve seat at a position spaced outwardly from the metal seal, and an exhaust pump is connected to the intermediate space between the metal seal and the elastomer seal. A double seal type valve for ultra-high vacuum, which is characterized by being equipped with.