JPH07139700A - Method and device for vacuum connection having vibration insulation - Google Patents

Abstract

PURPOSE:To provide a method and a device for mutually connecting vacuum units by vacuum without transmitting any mechanical vibration. CONSTITUTION:In a device constructed by connecting by cryopump having a freezer 1 which is a source of vibration generation, to a chamber 100, the the freezer 1 is set on a pump canister 4 via a bellow 10, the bellow 10 and the freezer 1 are housed in a second pump canister 5 and vibration insulation is provided between the cyropump and the chamber 100.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum device for creating a vacuum state, and more particularly to a method and a device for vacuum connection without transmitting mechanical vibration. For example, it is used in a connection part of a low vibration type cryopump.

[0002]

2. Description of the Related Art In the construction of a vacuum system, it is often the case that it is desired to realize a vacuum connection (to establish a common vacuum state) for a plurality of vacuum units without transmitting mechanical vibration. Meeting this requirement has been very difficult. The simplest method and device for connecting in vacuum is to connect the units with bellows (bellows), but in this case a strong pulling force acts due to atmospheric pressure, and mechanical vibration is transmitted. Resulting in. In particular, it is necessary to reduce the vacuum resistance by making the diameter of the connecting portion as large as possible in order to meet the vacuum requirements. For this reason, this pulling force became very large, and there was little point in using bellows.

In the following, an example in which such a problem appears most clearly, that is, an example in which a cryopump is connected to the chamber will be described.

In recent years, STM (Scanning Tunnel Microsco
In shape observation and microfabrication at the atomic level represented by the pe scanning tunnel current microscope), it is strongly demanded that the environment be not only a good vacuum state but also almost no mechanical vibration. Although the cryopump can easily obtain a good vacuum state, it has a drawback that it causes a large mechanical vibration. Therefore, conventionally, the following improvement methods have been devised.

FIG. 4 shows a first conventional example. 1 is a refrigerator,
2 is a cooling head, 3 is a cooling panel, 4 is a pump container, 10 is a bellow, 20 is a support, 21 is rubber, 100 is a chamber, and 101 is a roughing pump.

First, the cryopump will be described. The refrigerator 1 adiabatically expands the helium gas by the internal piston. Therefore, the refrigerator 1 constantly vibrates and serves as a vibration source. The cooling head 2 is cooled to minus 260 degrees by this adiabatic expansion. In the cooling panel 3, activated carbon or the like is attached to the surface of a metal plate having good heat conduction, and a large amount of gas particles can be adsorbed. First, after the gas particles inside the chamber 100 are exhausted (preliminarily exhausted) to some extent by the roughing pump 101, the gas particles remaining due to the adsorption action of the cooling panel 3 are exhausted to create a vacuum state.

The above is the basic principle and structure of the cryopump, and this is the same in the second conventional example and the present invention described later. However, there is a difference in the method of attaching the refrigerator 1, the cooling head 2, and the cooling panel 3 to the pump container 4, and thereby the transmission of mechanical vibration to the chamber 100 is greatly different.

In the first conventional example shown in FIG. 4, the refrigerator 1 is attached to the pump container 4 via the bellows 10. If the interiors of the pump container 4 and the bellows 10 are not vacuum (at atmospheric pressure), the refrigerator 1 and the pump container 4 are elastically connected by a soft spring, and the refrigerator 1
The mechanical vibration generated at 1 is not so much transmitted to the pump container 4.

A second conventional example is shown in FIG. 5 (actual Kaihei 5-4).
2681). 1 is a refrigerator, 2 is a cooling head, 3 is a cooling panel, 4 is a pump container, 11 is a first bellows, 1
2 is a second bellows, 30 is a first support, 31 is a second support, 32 is a roller, and 100 is a chamber,
101 is a roughing pump.

The operations of the refrigerator 1, the cooling head 2 and the cooling panel 3 are different only in that the mounting directions are partially different.
The structure is exactly the same as the first conventional example. However, the cooling head 2 is connected to the first support body 30, and the first support body 30 is connected to the pump container 4 via the second bellows 12. First bellows 11 and second bellows 12
Have the same shape, size, and mounting height so that the atmospheric pressure applied in the left-right direction is offset. However, in the vertical direction, the refrigerator 1 and the first support 3
0 is mounted on the second support 31 via the rollers 32. In this way, it is expected that mechanical vibration is not transmitted to the chamber 100 by making the refrigerator 1 free in the left-right direction and by making the moving direction of the internal piston the left-right direction.

[0011]

However, in the case of actually operating as a vacuum pump in the first conventional example, the inside of the pump container 4 and the bellows naturally becomes a vacuum, so that the bellows 10 is external. Will be subject to atmospheric pressure. Normally, the cooling head 2 needs to have a diameter of at least about 7 cm, and therefore the bellows 10 needs to have a diameter of about 12 cm. Since the atmospheric pressure of 1 kgw is applied to 1 cm ² , the bellows 10 receives a force of 100 kgw or more.

Therefore, when operating as a vacuum pump,
The refrigerator 1 and the pump container 4 are half elastically connected by a hard spring having a pulling force of 100 kgw, and the mechanical vibration generated in the refrigerator 1 is almost transmitted to the pump container 4. Become. In actual application,
In order to prevent the bellows 10 from contracting more than is allowed, a rubber 21
Although the support body 20 sandwiching the above is installed, the easiness of transmitting mechanical vibration is the same as long as there is a tensile force of 100 kgw.

Incidentally, in this first conventional example, the bellows 1
The position of 0 is a place that can be made relatively thin without causing a problem in vacuum (without reducing the exhaust capacity). If the bellows is installed between the pump container 4 and the chamber 100 in the simplest form, the diameter becomes 20 cm or more,
The pulling force will exceed 300 kgw.

In the second conventional example, in actual application, the shapes, sizes, and mounting heights of the first bellows 11 and the second bellows 12 are always (in any state),
And it is difficult to make them exactly the same. Therefore, a certain amount of tensile force remains, and the transmission of mechanical vibration does not completely disappear even with respect to parallel vibration in the left-right direction.

Further, even if the pulling force becomes completely zero, vibration components other than the parallel vibration in the left-right direction (parallel vibration in the front-rear direction, vertical vibration, and rotational vibration about the left-right, front-rear direction, and vertical direction) Mechanical vibrations will be transmitted for a total of 5 degrees of freedom). In fact, even if the piston moves in the left-right direction, a 5-DOF component is generated from the moving parts of the piston, and even if only parallel vibration in the left-right direction occurs, the refrigerator 1 itself disperses the vibration. Since it is regarded as a system, the vibration that finally occurs is 6
It becomes a degree of freedom. That is, the chamber 100 has 5
The mechanical vibration of the degree of freedom will be transmitted.

As described above, in the second conventional example, although the transmission of mechanical vibration is improved to some extent as compared with the first conventional example, it is never sufficient for the requirement.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method and an apparatus for connecting vacuum units to each other in a vacuum without transmitting mechanical vibration.

[0018]

In order to achieve the above object, a vacuum connection method of the present invention having vibration isolation has a common structure in which two vacuum units are connected using a freely moving component such as a bellows. In the method of (1), the one vacuum unit and the freely movable component are placed in another vacuum state to provide vibration insulation between the two vacuum units.

The vacuum connection device having vibration isolation according to the present invention connects two vacuum units using a freely moving component such as a bellows, and creates a common vacuum state by using one vacuum unit. It is characterized in that a vibration insulation property is provided between the two vacuum units by setting a different vacuum state around the unit and the freely movable component.

[0020]

According to the present invention, two vacuum units (a vacuum unit having a vibration source and a vacuum unit not having a vibration source) are always connected in a state of having vibration insulation.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description will be made on the basis of an example in which a connecting portion of a cryopump is implemented as in the conventional example of the present invention.

FIG. 1 shows a first embodiment of the present invention.
1 is a refrigerator, 2 is a cooling head, 3 is a cooling panel, 4 is a pump container, 5 is a second pump container, 6 is a hose,
10 is a bellows, 40 is a first magnet, 41 is a second magnet, 42 is a floor, 100 is a chamber, 101 is a roughing pump, and 102 is a second roughing pump.

The inside of the second pump container 5 is evacuated by the second roughing pump 102. Therefore, the inside / outside of the bellows 10 is in a vacuum state, and no atmospheric pressure is generated. Strictly speaking, some force will be generated depending on the degree of vacuum. Certainly, the refrigerator 1 is made of a material that releases a large amount of gas, but according to a normal roughing pump, the inside of the second pump container 5 is about 1/10000 of the atmospheric pressure (10 ^-2 Torr). Is easy to do. In that case, the pulling force is about 10 gw, which is almost negligible. Also, hose 6
Can also be soft enough.

Further, the first magnet 40 and the second magnet 41 are oriented so that the magnetic force repels each other, and the force is applied to the refrigerator 1,
It is made larger than the total weight of the cooling head 2 and the cooling panel 3. The second magnet 41 is installed on the floor 42, and the second pump container 5 is made of a non-magnetic material. Therefore, the refrigerator 1 and the like are in a state of floating in the space (magnetic levitation), and although mechanical vibration of the refrigerator 1 is transmitted to the second magnet 41 and the floor 42 via this repulsive force, There is no transmission to the second pump container 5.

That is, the refrigerator 1 and the chamber 100 are elastically connected by the very soft spring by the bellows 10, and the mechanical vibration of the refrigerator 1 is hardly transmitted to the chamber 100.

FIG. 2 shows a second embodiment of the present invention. 1
Is a refrigerator, 2 is a cooling head, 3 is a cooling panel, 4 is a pump container, 5 is a second pump container, and 6 is a hose.
0 is a bellows, 42 is a floor, 50 is a support, 51 is a thin bellows, 52 is a valve, and 100 is a chamber.
01 is a roughing pump.

In order to bring the second pump container 5 into the vacuum state, the valve 52 is opened when the chamber 100 is pre-evacuated from the atmospheric pressure state. Chamber 100
When the preliminary exhaust of is completed, the valve 52 is closed and
The second pump container 5 is put into a closed state. If left as it is, the pressure inside the second pump container 5 gradually increases due to the released gas, but it takes one week or more to reach several Torr. Even when the pressure is several Torr, the tensile force due to the internal / external differential pressure is 1 kgw or less, which is 1/100 of the atmospheric pressure, so that the chamber 100 is connected to the refrigerator 1 and the bellows 10 by a considerably soft spring. Normally, the pre-evacuation of the chamber 100 is often performed once or more per week, and it is considered that this evacuation interval poses almost no practical problem. If necessary, it is possible to extend this period to about one month by using a material that releases less gas for the refrigerator 1.

The refrigerator 1 is supported on the floor 42 by a support 50, and the support 50 is connected to the second pump container 5 via a thin bellows 51. This thin bellows 5
In No. 1, the atmospheric pressure is directly applied, but since the diameter is small, the pulling force can be considerably reduced. For example, the diameter of the support 50 is 0.5 cm,
It is easy to set the diameter of the thin bellows 51 to 1 cm, and in this case, the pulling force per piece is 0.8 kgw, and even the three-point support is only 2.4 kgw. The tensile force is 1/50 of that of the first conventional example. Therefore, even if the pulling forces of the bellows 10 and the thin bellows 51 are combined, the transmission of mechanical vibration is significantly reduced as compared with the first conventional example.

FIG. 3 shows a third embodiment of the present invention. 1
Is a refrigerator, 2 is a cooling head, 3 is a cooling panel, 4 is a pump container, 5 is a second pump container, and 6 is a hose.
0 for bellows, 52 for valves, 60 for springs, and 100
Is a chamber, and 101 is a roughing pump.

The method for bringing the second pump container 5 into a vacuum state is the same as in the second embodiment.

The spring 60 is sufficient to support the total weight of the refrigerator 1, the cooling head 2 and the cooling panel 3. In this case, the refrigerator 1 and the second vacuum container 5 are connected with a pulling force corresponding to this weight. Therefore, when the weight is large, the tensile force is large, but if the exciting force of the same mechanical vibration is larger, the larger the weight is, the smaller the amplitude is, and thus the finally transmitted vibration is not so large.

Although all the embodiments have been described with reference to the connecting portion of the cryopump, the present invention is not limited to this, as a matter of course. A unit that generates mechanical vibration,
It can be applied to all cases where it is attached to a unit that dislikes mechanical vibration. Further, the reverse is also applicable.
That is, it is applicable to all of the method and apparatus for connecting a plurality of units in a vacuum with vibration isolation.

Although all the freely movable parts have been described as being connected using a bellows (bellows tube), other than this, those which are made of a soft material such as Teflon or vinyl and have an indefinite shape, an O-ring and a polishing rod. It can be carried out using all free-moving parts, such as those using the rub seals of.

The second pump container 5 may contain at least the refrigerator 1 which is a vibration source and the bellows 10 which is a freely moving component, and constitutes one vacuum unit. The pump container 4 may be accommodated.

[0035]

As described above, according to the present invention, it is possible to construct a vacuum atmosphere without mechanical vibration.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a connection structure of a conventional vacuum unit.

FIG. 5 is a configuration diagram of another connection structure of a conventional vacuum unit.

[Explanation of symbols]

 1 Refrigerator 2 Cooling Head 3 Cooling Panel 4 Pump Container 5 Second Pump Container 6 Hose 10 Bellow 40 First Magnet 41 Second Magnet 42 Floor 50 Support 51 Thin Bellow 52 Valve 60 Spring 100 Chamber 101 Roughing Pump 102 Second roughing pump

Claims (2)

[Claims] 1. A method of connecting two vacuum units using a freely moving component such as a bellows to establish a common vacuum state, wherein one vacuum unit and the periphery of the freely moving component are brought into another vacuum state. According to the vacuum connection method, vibration insulation is provided between the two vacuum units. 2. An apparatus for connecting two vacuum units using a freely movable component such as a bellows to establish a common vacuum state, wherein one vacuum unit and the periphery of the freely movable component are brought into another vacuum state. By virtue of the above, a vacuum connection device characterized in that vibration insulation is provided between the two vacuum units.