JPS61229979A - Exhaust surface of cryo-adsorptive pump - Google Patents

Abstract

PURPOSE:To make an adsorptive material to be cooled down easily as well as to be prevented from coming off despite certain effect of vibration and/or shock by sticking said small-grained shaped adsorptive material firmly onto a cryo-surface through direct adhesion of said material to said cryo-surface according to a metallurgical adhesion method. CONSTITUTION:A metal-sprayed layer 15 is formed by spraying a metallic material of the same quality as a cryo-surface 5, for example, copper, according to a plasmad spraying method or the like on one end of an adsorptive material. And, the said adsorptive material 6 is stuck to the cryo-surface 5 by the metal- sprayed layer 15 according to the metallurgical adhesion method such as silver brazing, soldering or the like.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a cryopump used in ultra-high vacuum equipment, nuclear fusion equipment, etc. This article relates to the exhaust surface of a cryo-adsorption pump.

[Technical background of the invention and its problems]

FIG. 5 shows a conventional vacuum evacuation system using a cryo-adsorption pump, in which an evacuation target 1, such as a vacuum vessel of a nuclear fusion device, is connected to a cryopump chamber 3 via an evacuation pipe 2. . The cryo-adsorption pump 4 housed in the cryopump chamber 3 has a metal surface 5 (hereinafter referred to as the cryo-surface) that is cooled to an extremely low temperature with a refrigerant liquid such as liquid helium, and a cryo-adsorption pump 4 that An adsorbent 6 such as activated carbon or molecular sieve attached with an adhesive such as epoxy resin, a chevron baffle 7 placed in front of the cryo surface 5 and cooled with a cooling liquid such as liquid nitrogen, and the cryo surface 5 are adsorbed. The radiation shield plate 8 surrounds the material 6 and is cooled by the cooling liquid. The cryopump chamber 3 is connected to an auxiliary vacuum pump 10 via another exhaust pipe 9. As this auxiliary vacuum pump 10, a mechanical pump such as a turbo molecular pump or an oil rotary pump is generally used.

In advance, the inside of the cryopump chamber 3 is brought into a high vacuum state by the auxiliary vacuum pump 10 for vacuum insulation, and then the refrigerant liquid is supplied to the cryo-adsorption pump 4, and the molecules of the gas to be pumped from the object to be pumped 1 are absorbed by the adsorbent 6. Adsorb and exhaust. When the operation of the object to be evacuated 1 is stopped, the cryo-adsorption pump is regenerated. That is, the supply of refrigerant liquid is cut off, the temperature of the cryosurface 5 and the adsorbent 6 is increased, and the adsorbed gas molecules are separated from the adsorbent 6.
This is evacuated to the outside by the auxiliary vacuum pump 10.

FIG. 6 is an enlarged view of the cryoplane 5 and adsorbent 6 in FIG. 5, and the adsorbent 6 is bonded to the cryoplane 5 with an organic adhesive 11 such as epoxy resin. In this figure, the outer surface of the bottom of the refrigerant reservoir 14 containing the refrigerant liquid 13 is used as the cryo surface 5, and the refrigerant liquid piping, chevron baffle, radiation shield plate, etc. are omitted from illustration.

However, when a cryo-adsorption pump is used in a nuclear fusion device, it receives high-energy neutrons generated by the fusion reaction, and the fuel gas it adsorbs and exhausts contains tritium, a radioactive substance. Adhesives made of organic materials such as epoxy resins whose performance deteriorates when exposed to radiation are unsuitable as adhesives for adsorbents.

Therefore, instead of an organic adhesive, this adsorbent is attached to an alloy of silver and tin, which are low melting point metals, and this alloy is attached to the cryo surface.
m 5science and Technology
Vol, 1B No, 3April 1981-11
As stated in the middle groove of the left column on page 33, it is difficult to reliably attach adsorbents to low-melting point metals, and even if they do, they are likely to come off due to some vibration or impact. There were drawbacks. In addition, in order to attach the adsorbent to a low-melting point metal, it is necessary to embed a part of the adsorbent in the low-melting point metal, which increases the thickness of the low-melting point metal (approximately 5 to 10 JIIm), which increases the thickness of the exhaust surface. As the weight increases, the contact resistance between the cryosurface and the adsorbent increases, resulting in a disadvantage that the adsorbent is difficult to cool.

[Purpose of the invention]

Therefore, in view of the above-mentioned points, an object of the present invention is to provide an exhaust surface of a cryo-adsorption pump that is lightweight and has good adsorption and exhaust performance by adhering an adsorbent material to the cryo-adsorption surface reliably and firmly. be.

[Summary of the invention]

In order to achieve this purpose, the exhaust surface of the cryo-adsorption pump according to the present invention is made by spraying a metal material of the same quality as the cryo-surface or the adsorbent mounting plate onto one end surface of the small-sized adsorbent. The metal sprayed adsorbent layer and the cryo surface are directly bonded together using a metallurgical bonding method. In this way, the adsorbent adheres to the cryo surface reliably and firmly, and since the thickness of the metal inclusions (metallic sprayed layer and metallurgical bond) between the adsorbent and the cryo surface is thin, it is lightweight, and the cryo surface can be adsorbed. The contact resistance between the materials is reduced, the adsorbent is easily cooled, and the adsorption/exhaust performance is improved.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. Parts having the same functions as those in FIGS. 5 and 6 are given the same numbers and their explanations will be omitted. As shown in FIGS. 1 and 2, a metal sprayed layer 15 is deposited on one end surface of the adsorbent 6 by spraying a metal material, such as copper, of the same quality as the cryosurface 5 in advance using a plasma sword method or the like. Form. The metal sprayed layer 15 interlocks with the porous structure of the adsorbent 6 to form a dense coating with strong bonding strength.

Further, the appropriate thickness of the metal sprayed layer 15 is on the order of 0.3 to 0.5. The metal sprayed layer 15 and the cryosurface 5 can be easily and reliably bonded together by a metallurgical bonding method (general term for silver brazing, soldering, welding, etc.). 16
indicates a metallurgical bond.

In this way, the adsorbent 6 is bonded to the cryosurface 5 via the metal sprayed layer 15 by metallurgical bonding, so it is reliable and strong. In addition, the metal spray layer 15 and the metallurgical adhesive part 16
Because it only needs to be thin, it is lightweight, and the cryoplane 5
Since the adsorbent 6 and the adsorbent 6 are metallurgically bonded via the metal spray layer 15, the contact resistance between the cryosurface 5 and the adsorbent 6 is reduced, the adsorbent 6 is easily cooled, and the adsorption and exhaust performance is improved. will improve.

3 and 4 show other embodiments of adhesion for forming a metallurgical bond 16 on an adsorbent mounting plate 11 made of the same metal material as the metal sprayed layer 15 of the adsorbent 6. A material (silver brazing material, solder material, etc.) is placed and a metal spray layer 15 is placed on it.
Place the adsorbent 6 with the side facing down. Then, by placing a metal weight plate 18 thereon and heating it to a predetermined temperature in a heating furnace 19, the adsorbent 6 can be easily adhered to the adsorbent mounting plate 17.

The adsorbent mounting plate 17 is provided with a convex portion 17a around the periphery to prevent the adhesive material for forming the metallurgical bond 16 from flowing out to the periphery during heating. Further, bolt holes 17b for attaching to the cryosurface 5 are pre-drilled in the adsorbent mounting plate 17. After the inside of the heating furnace 19 has been cooled to room temperature in this way, the weight plate 18 is removed, the adsorbent mounting plate 17 to which the adsorbent 6 is adhered is taken out, and attached to the cryo surface 5 with bolts 20, and the cryoadsorption Forms the exhaust surface of the pump.

In this way, the adsorbent 6 can be attached to the cryo surface 5 more easily and reliably.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a metal sprayed layer is formed on one end surface of a small adsorbent by thermal spraying a metal material of the same quality as the cryo surface or the adsorbent mounting plate,
Since the exhaust surface is formed by bonding the metal sprayed layer and the cryo surface using a metallurgical bonding method, the adsorbent adheres to the cryo surface reliably and firmly, and even when subjected to some vibration or shock, the adsorbent There is no fear that it will come off.

In addition, since the thickness of the metal inclusions (metallic sprayed layer and metallurgical bond) between the adsorbent and the cryosurface is thin, it is lightweight.
In addition, since the adsorbent and the cryo surface are metallurgically bonded via the metal spray layer, the contact resistance between the adsorbent and the cryo surface is reduced, making it easier to cool the adsorbent and improving the adsorption and exhaust performance. improves.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the exhaust surface of a cryo-adsorption pump according to an embodiment of the present invention, FIG. 2 is an enlarged view of the adsorbent portion of FIG. 1, and FIG. A cross-sectional view showing how to attach the adsorbent of the adsorption pump, Fig. 3
Figure 5 is a schematic diagram showing a vacuum evacuation device using a conventional cryo-adsorption pump; Figure 6 is a conventional cryo-adsorption pump using an organic adhesive. FIG. 5... Cryo surface, 6... Adsorbent, 15... Metal sprayed layer, 16... Metallurgical adhesive part, 17... Adsorbent mounting plate, 18... Weight plate, 19...・Heating furnace, 20・
··bolt. Agent: Patent attorney Noriyuki Chika (and 1 other person) Figure 3 Figure 4

Claims (1)

[Claims] A metal plate cooled to an extremely low temperature, and a small adsorbent having a metal sprayed layer formed on a part of its surface and bonded to the metal plate by metallurgical bonding through the metal sprayed layer. The exhaust surface of the cryo-adsorption pump.