JPH041348Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a vibration isolating device for a cryopump.

Conventionally, this type of pump has been known to generate low temperature by adiabatic expansion of high-pressure helium, condense or adsorb gas molecules on the cooled cryopanel, and exhaust the gas molecules. 1. As shown in the figure, a refrigerator unit c equipped with a motor b and a piston d is generally attached to a pump case a, so vibrations occur due to the operation of the refrigerator unit b, which causes damage to the vacuum chamber. If this is transmitted to other vacuum equipment e, it may cause damage to the equipment or defective vacuum processing, which is undesirable. It is possible to absorb such vibrations transmitted to the vacuum device e by attaching a cryopump via a metal bellows f as shown in the figure.
Not only is the bellows large and expensive, but the conductance is also reduced by the amount of the bellows f, resulting in a disadvantage that the pump's pumping performance is degraded.

In addition, in order to prevent the bellows from becoming larger and the conductance from decreasing, a small-diameter insertion hole is provided in the pump case of the cryopump, and the first and second stage cylinders of the refrigerator unit are inserted into the insertion hole. The pump case and the refrigerator unit are airtightly attached together via a small-diameter bellows surrounding the first and second stage cylinders, and a single coil spring is wound around the bellows. A vibration isolating device provided with the above is also known from Japanese Utility Model Application Publication No. 57-158162. Cryopumps are sometimes installed horizontally, and in such cases, if a single coil spring supports the refrigerator unit, the bending of the spring causes the refrigerator unit to tilt relative to the pump case, changing the conductance of the pump. As a result, the desired exhaust performance cannot be obtained.

The purpose of the present invention is to provide a cryopump vibration isolator that combines a bellows and a spring so that the refrigerator unit can be installed in a predetermined direction. 3, and the first part of the refrigerator unit 2 is provided in the insertion opening 3.
The stage cylinder 5 and the second stage cylinder 8 are inserted, and the pump case 1 and the refrigerator unit 2 are integrally and airtightly attached via a small diameter bellows 4 that surrounds the first stage cylinder 5. In this device, a plurality of coil springs 12 of two types of strong and weak are interposed between the pump case 1 and the refrigerator unit 2 and positioned outside the bellows 4.

An embodiment of the present invention will be explained based on FIG. 2 of the drawings.
is formed along the shield 6 attached to the first stage cylinder 5 of the refrigerator unit 2 with a relatively narrow interval 7, and has a diameter large enough to allow the first stage cylinder 5 to be inserted into the bottom part 1a. A small-diameter insertion opening 3 is provided, through which the first-stage cylinder 5 and the second-stage cylinder 8 extending further therefrom are inserted. 9 is the second
The condensing panel 10 attached to the stage cylinder 8 is a baffle provided at the front opening of the shield 6.

The bellows 4 is preferably made of stainless steel, and has one end attached to the periphery of the insertion hole 3 and the other end attached to the front surface of the main body 11 of the refrigerator unit 2.
It was made to surround the surrounding area. The bellows 4 functions to isolate vibrations of the refrigerator unit 2, but
It is advantageous to provide the bellows 4 not at the inlet of the pump, but between the pump case 1 and the refrigerator unit 2 as shown in the second figure, since deterioration in pump exhaust performance due to a decrease in conductance can be prevented.

When the pressure inside the cryopump changes, the bellows 4 expands and contracts, and if the expansion and contraction is large, the pump needs to be fixed to the floor, but as shown in the second figure, the bellows 4 expands and contracts. By interposing the coil spring 12 between them, the expansion and contraction can be suppressed, the load on the bellows 4 is reduced, a flexible and small diameter bellows 4 can be used, and there is no need to fix the pump to the floor.
In this case, the spring 12 is selected to have a spring constant such that the amount of expansion and contraction of the bellows 4 due to pressure fluctuations of the pump is kept within an allowable value.

A cryopump may be installed horizontally, and in such a case, with one coil spring 12, the refrigerator unit 2 is tilted with respect to the pump case 1, causing the inconvenience that the conductance inside the pump becomes uneven. Further, even if a plurality of coil springs 12 having the same strength are used, the same result will be obtained. Therefore, in the present invention, a plurality of springs of two types, strong and weak, are used as the coil springs 12. For example, when the pump is installed horizontally as shown in the second figure, the strong spring 12 is placed on the lower side.
By providing a weak spring 12b on the upper side in addition to the spring 12b, the refrigerator unit 2 can be mounted while maintaining a predetermined substantially horizontal position.

Two types of strong and weak springs are used for the coil spring 12,
There is no problem when the cryopump is placed vertically, and even if the load distribution on the refrigerator unit 2 is unbalanced, it can be installed without tilting with respect to the pump case 1.

As described above, in the present invention, the pump case 1 and refrigerator unit 2 of the cryopump are connected to the bellows 4.
In the vibration isolating device of the type connected by a coil spring 12, a plurality of springs of two types, strong and weak, are used for the coil spring 12, so that the refrigerator unit 2 can be moved in a predetermined direction with respect to the pump case using only the springs. The cryopump can be installed horizontally without sacrificing pumping performance, which is advantageous.

[Brief explanation of the drawing]

FIG. 1 is a cutaway side view of a conventional example, and FIG. 2 is a partially cutaway side view of an embodiment of the present invention. 1... Pump case, 2... Refrigerator unit,
3...Insertion port, 4...Bellows, 5...First stage cylinder, 8...Second stage cylinder, 12...Coil spring, 12a...Strong spring, 12b...Weak spring.

Claims (1)

[Scope of utility model registration request] A small-diameter insertion port 3 is provided in the pump case 1 of the cryopump, and the first stage cylinder 5 and second stage cylinder 8 of the refrigerator unit 2 are inserted into the insertion port 3, and the pump case 1 and the refrigerator unit are connected to each other. 2, the first
In the case where the stage cylinder 5 is integrally and airtightly attached via a small diameter bellows 4 surrounding it,
Between the pump case 1 and the refrigerator unit 2, a plurality of strong and weak 2
A vibration isolating device for a cryopump that includes a coil spring 12 of different types.