JPH0461196B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Industrial Application Field The present invention relates to a cryopump, which is a type of vacuum pump.

(b) Prior art A conventional cryopump has a cryopanel disposed inside a pump casing, cools the cryopanel with a cold head of a cryogenic refrigerator, and directs the gas that comes into contact with the cryopanel to the surface of the panel. The interior of the casing is brought into a high vacuum state by being liquefied and adsorbed in the casing. By the way, conventional cryopumps utilize a gas cycle such as a Solvay cycle or a Gifford-McMahon cycle, and are comprised of a small refrigerator having a piston-type expansion chamber. However, such a system requires a relatively large piston to reciprocate, resulting in problems such as large vibrations and the inability to increase the number of cycles to improve performance. Therefore, recently, a cryopump equipped with a small Claude cycle refrigerator having a rotary type expansion chamber has been considered. However, as shown in FIG. 1, this type of cycle refrigerator has, for example, an expansion formed around the outer periphery of the rotating body b connected to the energy absorbing generator a as the rotating body b rotates. A rotary expander c is configured to increase or decrease the volume of the chambers d1 to d4, and a high-pressure refrigerant gas A is supplied to the expansion chamber d1, whose volume is about to increase as the rotating body b rotates.
an air supply pipe e that introduces the gas, an exhaust pipe f that leads out the low-temperature, low-pressure refrigerant gas B from the expansion chambers d3 and d4 whose volume is about to decrease, and the gas B in the exhaust pipe f and the air supply pipe a cold head h provided at the starting end of the exhaust pipe f, etc.;
The cryopanel i is cooled. Therefore, in such a refrigerator, a high-capacity heat exchanger g is essential, and there is a problem in that this heat exchanger g occupies a considerable area of the volume inside the cryopump.

(c) Purpose The present invention has been made in view of the above circumstances, and aims to reduce the area occupied by the heat exchanger disposed inside the pump casing as much as possible to reduce the size and weight, and to cool the cryopanel. The purpose of the present invention is to provide a cryopump that can be used efficiently.

(d) Structure In order to achieve the above object, the present invention provides a cryopump comprising a Claude cycle refrigerator and a plurality of mutually separated cryopanels, in which high pressure is applied to the expansion chamber of the refrigerator. Each cryopanel is provided with an air supply pipe that introduces refrigerant gas and an exhaust pipe that brings out low-pressure gas from the expansion chamber. It is characterized by the fact that it consists of everything.

(E) Embodiment An embodiment of the present invention will be described below with reference to FIG.

As shown in FIG. 2, the cryopump according to the present invention includes cryopanels 2, 3, and 4 disposed inside a pump casing 1,
3 and 4. Cryopanel 2,
3 and 4 are thin plates with good heat conduction formed into a bottomed cylindrical shape, and accommodate the second-stage cryopanel 3 within the first-stage cryopanel 2;
A third stage cryopanel 4 is arranged within this cryopanel 3. The refrigerator 5 also includes a rotary expander 6 disposed inside the cryopanel 4, and an air supply pipe 8 for guiding high-pressure refrigerant gas A discharged from the compressor 7 to the expander 6. and,
An exhaust pipe 9 for returning the low-temperature, low-pressure refrigerant gas B discharged from the expander 6 to the compressor 7, and a gas B in the exhaust pipe 9 and gas A in the air supply pipe 8. It is equipped with a heat exchanger 11 for exchanging heat between the two. The expander 6 has the same configuration as the expander c, and has a rotating body (not shown).
is a motor (generator) 13 for absorbing rotational power through the shaft 12 and keeping the rotation constant.
It is connected to the.

The air supply pipe line 8 and the exhaust pipe line 9
The parts 8a and 9a located between the expander 6 and the heat exchanger 11 in the cryopanels 2, 3, and 4 are made of a material with good thermal conductivity.
These cryopanels 2, 3, and 4 constitute a part of the heat exchanger of the refrigerator 5. Note that 14 is an adsorbent such as activated carbon adhered to the surface of the cryopanel 4. Further, 15 is a chevron for preventing radiant heat from entering.

With such a configuration, the air supply pipe 8 can also be connected to the cryopanels 2, 3, and 4.
Since heat exchange is performed between the gas A in the exhaust path 9 and the gas B in the exhaust path 9, the dedicated heat exchanger 11 can be downsized. That is, in this refrigerator 5, the combination of the cryopanels 2, 3, 4 and the heat exchanger 11 functions equivalent to the conventional heat exchanger g, and in this case, the cryopanels 2, 3, and , 4 are provided with a sufficient heat exchange area, the heat exchanger 11 can be made much smaller than the conventional heat exchanger g, and the entire cryopump can be made more compact and lighter. I can do it. However, if this is done, a thermal gradient will occur between the portions of the cryopanels 2, 3, and 4 closer to the expander and the portions closer to the heat exchanger 11, but the nitrogen gas present in the pump casing 1 will , oxygen gas, carbon dioxide gas, etc. have different liquefaction temperatures. Therefore, it is necessary to set the cryopanels 2, 3, and 4 so that the lowest temperature part can adsorb the gas with the lowest liquefaction temperature, and the highest temperature part can adsorb the gas with the highest liquefaction temperature. Cryopanel 2,
There is no problem with the gas adsorption effect of 3 and 4. Moreover, according to this configuration, there is no need to take the trouble to provide a cold head for the expansion chamber or the gas led out from the expansion chamber, and it is also possible to eliminate the need for a heat shield plate that is often provided to block radiant heat. Another advantage is that the structure can be further downsized and simplified.

Note that the number of stages of cryopanels is not limited to three stages as in the above embodiment.

Furthermore, the shape of the cryopanel is of course not limited to the above-mentioned shape, and in short, both the cryopanel and the high-pressure gas supplied to the expander are heated by the low-temperature gas discharged from the expander. Any material that can effectively cool the air is sufficient.

Furthermore, the refrigerator is not limited to one having only one stage of an expander, but may be one having another stage of expander between the second stage cryopanel and the third stage cryopanel, for example. Various modifications are possible.

(f) Effects Since the present invention has the above-described configuration, the area occupied by the heat exchanger disposed inside the pump casing is minimized to reduce the size and weight, and
It is possible to provide a cryopump that can efficiently cool a cryopanel. That is, in the present invention, the cryopanel, which acts as a gas adsorption plate, is provided with an air supply pipe line and an exhaust pipe line to play the role of a heat exchanger, so that a sufficient heat exchange area is ensured in the cryopanel. This has the effect of making the original heat exchanger smaller or unnecessary. At this time, since there are no restrictions on the shape of the cryopanel, it is easy to avoid interference with other components and ensure a large heat exchange area. In addition, although a temperature gradient occurs between each cryopanel, each cryopanel can be set to adsorb gases with different liquefaction temperatures, and in that case, all cryopanels can efficiently function as condensation plates. This results in the effect of improving pump efficiency. Furthermore, since the cryopanel functions as a cold head or a heat shield plate, it is possible to further promote miniaturization by omitting these component parts.

[Brief explanation of the drawing]

FIG. 1 is an explanatory circuit diagram showing a conventional example, and FIG. 2 is a schematic sectional view showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Pump casing, 2, 3, 4... Cryopanel, 5... Freezer, 6... Expander, 8... Air supply pipe line, 9... Exhaust pipe line, 11... Heat exchanger, A, B... Refrigerant gas.

Claims (1)

[Claims] 1 Equipped with a plurality of mutually separated cryopanels arranged in a pump casing for liquefying and adsorbing gas in the casing, and a Claude cycle refrigerator for cooling these cryopanels. In the cryopump, each cryopanel is provided with an air supply pipe for introducing high-pressure refrigerant gas into the expander of the refrigerator, and an exhaust pipe for extracting low-pressure gas from the expander. A cryopump, characterized in that the cryopanel constitutes part or all of the heat exchanger of the refrigerator.