JPS60249678A - Cryopump - Google Patents

Abstract

PURPOSE:To perform the cohesion of an adsorbent to a metal plate so rigidly as well as to improve its durability, by attaching the low melting point metal plate, provided with a lot of holes, to one side of a cooling part to be cooled to cryo- temperature by a refrigerant, while embedding granular adsorbents inside these holes. CONSTITUTION:A cryopump is made up of additionally installing a low melting point metal plate 10 composed of an alloy comprising silver and tin, to one side part of a cooling part to be cooled to cryo-temperature by a refrigerant of liquid helium or the like, and activated carbon 14 acting as an adsorbent is installed on a surface of this metal plate 10. In this case, the metal plate 10 is bored with a lot of circular through holes 11 for activated carbon embedding use with the specified pattern, while it is made up of boring a bolt hole 12 in the center. And, this metal plate 10 is set up inside a templet 13 installing a frame part 13a around it, and after the activated carbon 14 being granulated in the cylindrical form uniformed in height is embedded inside each hole 11 so as to cause almost half parts of them to be exposed, the metal plate 10 is additionally installed in the cooling part via the templet 13.

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. Regarding the cryopump.

[Technical background of the invention and its problems]

Figure 1 is a schematic diagram of a conventional cryopump.
A low melting point metal plate 2 made of an alloy of silver and tin is closely fixed with bolts or the like to a cooling part 1 that is cooled to an extremely low temperature with a refrigerant such as liquid helium. On the surface of this low melting point metal plate 2, small pieces of activated carbon 3, which act as an adsorbent, are adhered by affinity with the low melting point metal 2. The activated carbon 3 and the low melting point metal 2 constitute a gas adsorption panel 4.

The radiation shield 5 includes the cryogenic cooling unit 1 and the gas adsorption panel 4.
and is cooled with liquid nitrogen to reduce radiant heat from the room temperature area. A chevron-shaped baffle 6 disposed in front of the gas adsorption panel 4 is blackened so that its emissivity is approximately 1, and acts to guide the exhausted gas into the inside of the radiation shield 5. The cryo-adsorption pump having the above configuration is housed in a vacuum container 7, and an auxiliary vacuum pump 8 is connected to this vacuum container 7.

As this auxiliary vacuum pump, a mechanical pump such as a turbo molecular pump or an oil rotary pump is used.

After making the vacuum container 7 into a high vacuum state in advance for vacuum insulation using the auxiliary vacuum pump 8, a refrigerant such as liquid helium is supplied to the cryogenic cooling section 1, and the cooling section 1 and the gas adsorption panel 4 are heated.
is cooled to an extremely low temperature, and the exhaust gas molecules are adsorbed by an adsorbent, that is, activated carbon 3, and then exhausted.

The cryo-adsorption pump that has sufficiently adsorbed and exhausted the exhaust gas molecules is regenerated as follows. When the operation of the object to be evacuated is stopped, the supply of refrigerant liquid is cut off, the temperature of the gas adsorption panel 4 is increased, the adsorbed gas molecules are separated from the panel 4, and the gas molecules are evacuated to the outside by the auxiliary vacuum pump.

The gas adsorption panel 4 itself in such a conventional cryo adsorption pump ki13 is firmly attached to the cryogenic cooling unit 1 with bolts 9, as shown in enlarged form in FIGS. 2 and 3. The activated carbon 3 is only bonded and fixed to the low melting point metal plate 2 mainly by mutual affinity on its surface. Since this affinity is relatively weak, the activated carbon 3 not only easily peels off from the low-melting point metal plate 2 during the manufacturing process of the gas adsorption panel 4, but also when the panel 4 is cooled by the supply of refrigerant liquid during the operation of the cryo-adsorption pump. It is easily peeled off because it is repeatedly subjected to heating during pump regeneration. This peeling off of the activated carbon naturally leads to a decrease in the adsorption/exhaust capacity of the pump. Furthermore, the activated carbon that has peeled off within the vacuum container 7 may enter vacuum components such as the auxiliary vacuum pump 8, causing failure of these devices.

In addition, although the activated carbon 3 is sorted into a specific mesh size, the shape is not particularly shaped and is irregular, and it is only sprinkled appropriately on the low melting point metal plate 2. As shown in FIG. 2, the exposed areas and mutual spacing of the activated carbons 3 attached to the low-melting metal plate were irregular, and the activated carbon distribution state was not necessarily optimal.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned points, an object of the present invention is to provide a cryo-adsorption pump that can firmly adhere an adsorbent such as activated carbon to a low-melting point metal plate in an optimal distribution state and improve gas adsorption efficiency. It is in.

(Summary of the Invention) In order to achieve this object, the first invention of the present application includes a cooling section that is cooled to an extremely low temperature by a refrigerant liquid, and a cooling section that is attached to the cooling section on one surface and on the opposite side of this surface. It is characterized by comprising a low melting point metal plate with a large number of holes bored on its surface, and a small particulate adsorbent partially embedded in the holes of the low melting point metal plate. The second invention also provides a cooling unit that is cooled to an extremely low temperature by a refrigerant liquid, a template that is attached to the cooling unit and has a frame around the periphery, and a template that is welded to the template on one surface and that is connected to the template. It is characterized by comprising a low melting point metal plate with a large number of holes bored on the opposite surface, and a small particulate adsorbent partially embedded in the holes of the low melting point metal plate. be.

(Embodiment of the invention) An embodiment of the cryo-adsorption pump according to the present invention will be described below.
The description will be made with reference to FIGS. 4 to 19, in which the same members as in FIGS. 1 to 3 are denoted by the same reference numerals.

4 and 5, a low melting point metal plate 10 has a large number of circular through holes 11 for embedding activated carbon. The activated carbon burying hole 11 has a two-dimensional close-packed hole area. They are distributed at predetermined intervals and patterns such as 1, plus intervals such that there is sufficient low melting point metal to hold the activated carbon firmly in place. Further, a bolt hole 12 is bored in the center of the low melting point metal plate 10. This low melting point metal plate 10 is placed in a template 13 having a frame 13a around it, as shown in FIGS. 6 and 7. Activated carbon 14, which has been granulated and shaped into a columnar shape with a constant height, is placed in the activated carbon embedding hole 11 of the placed low melting point metal plate 10. As clearly shown in FIG. 6, the height of the activated carbon 14 is determined so that when it is placed in the activated carbon burying hole 11, nearly the upper half of the activated carbon 14 is exposed, and the diameter of the burying hole 11 is , is set to be slightly larger than the diameter of the activated carbon 14.

A bolt dummy 15 is inserted into the bolt hole 12 at the center of the low melting point metal plate 10, as shown in FIGS. 7 and 8. This dummy 15 prevents the bolt hole 12 from being significantly deformed when the low melting point metal plate 10 is melted.

The low melting point metal plate 10 in the state shown in FIG. 6 is heated and melted. This low melting point metal plate 10 contains, for example, 3.5% silver with a melting point of 232
When using a silver-tin alloy at ℃, the fluidity is not very good in the molten state, and the outer shape is held by the template, so this melting has little effect on the mutual spacing and pattern of the activated carbon 14. . After this molten low melting point metal plate 10 is infiltrated into the gap within the template 13, it is cooled and
Once solidified, each activated carbon 14 is embedded and firmly fixed in the low melting point metal plate 10 with one end exposed to the outside.

After removing the low melting point metal plate 10 to which the activated carbon 14 is fixed from the template 13 and removing the bolt dummy 15, the bolt holes of the low melting point metal plate 10 are opened as shown in FIGS. 9 and 10. The bolts 9 are inserted into the holes 12 and fixed to the cryogenic cooling section 1.

The gas adsorption panel 16 tightly fixed to the cryogenic cooling section 1 in this manner is cooled to a cryogenic temperature by the cryogenic section 1, and the exposed activated carbon 14 adsorbs and exhausts the gas to be exhausted.

Note that the template 13 and the bolt dummy 15 are made of a material that is difficult to weld to the molten low melting point metal plate 10 so that they can be easily removed from the solidified low melting point metal plate 10.

FIG. 11 shows an example in which activated carbon 14 is placed in the activated carbon embedding hole 11 of the low melting point metal plate 10 in the template 13 and then covered with a restraining plate 17. Four parts 17a are formed into which the upper end of the activated carbon 14 protruding from the plate 10 enters. In this state, the low melting point metal plate 10
When the activated carbon 14 is heated and melted, the activated carbon 14 forms the concave portion 17 of the holding plate 17.
Since the position is regulated by a, an extremely highly accurate distribution pattern of activated carbon can be obtained. Furthermore, when the low melting point metal plate 10 is in a molten state, activated carbon having a small specific gravity is inserted into the holes 1.
However, since the suppressing plate 17 suppresses the activated carbon 14 from above, it prevents the activated carbon 14 from rising.

- In the above embodiment, the template 13 was removed after the activated carbon 14 was embedded and fixed in the low melting point metal plate 10, but next, the low melting point metal plate on which the activated carbon was embedded and fixed was used as a template. An example of integration will be explained using FIGS. 12 and 13.

In FIGS. 12 and 13, the template 18 is made of a material that has a strong affinity with the low melting point metal plate 10 and easily welds it. As such a material, when a silver-tin alloy containing 3.5% silver is used for the low melting point metal plate 10, copper or aluminum is suitable. In exactly the same way as in the case of FIG. 6, the low melting point metal plate 10 is housed in the mold plate 18 made of steel or aluminum, and the activated carbon 14 is placed in the burial hole 11, heated, melted, and cooled. is embedded and fixed in the low melting point metal plate 10, and at the same time, this low melting point metal plate 10 is firmly welded to the template 18.

The gas adsorption panel 19 composed of the activated carbon 14, the low melting point metal plate 10, and the template 18 integrated in this way has the back side of the template 18 placed in the cryogenic cooling section 1, as shown in FIGS. 12 and 13. It is fixed to the cooling part 1 with bolts 9 in a tight state.

By integrating the low melting point metal plate 10 and the template 18 in this way, the low melting point metal plate 10 can be reinforced with the template 18, so the suction panel 19, which has a large contact area with the cryogenic cooling section 1, can be reduced to a small number. It has the advantage that it can be fixed to the cryogenic cooling part 1 with good adhesion using the bolts 9.

The embodiment shown in FIGS. 14 to 16 shows an example in which cylindrical activated carbon is placed horizontally on a low-melting point metal plate. As shown in FIG. 14, the low melting point metal plate 10 is provided with grid-like holes 20 for embedding activated carbon.
Store it horizontally. Thereafter, when the low melting point metal plate 1o is heated and melted and then cooled, the activated carbon 14 is transferred to the low melting point metal plate 10.
It is buried and fixed. This low melting point metal plate 10 is attached to the cryogenic cooling section 1 with bolts 9, as shown in FIGS. 15 and 16.
is fixed by

The embodiments shown in FIGS. 17 and 18 are examples in which the adhesion strength of activated carbon is further increased. In both figures, the activated carbon 21 and 22 are each embedded in the low melting point metal plate 10 so that the diameter of the lower end is larger than the diameter of the center.

The embodiment shown in FIG. 19 is an example in which the outer shape of the low melting point metal plate 10 is an equilateral triangle.

In each of the above embodiments, the activated carbon embedding hole was a through hole, but the present invention is not limited thereto, and may be a hole with a bottom. Furthermore, the adsorbent is not limited to activated carbon, but other materials can also be used.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, since the adsorbent such as activated carbon is embedded and fixed in the holes drilled in advance in the low-melting point metal plate, the adsorbent can be firmly fixed to the low-melting point metal plate. . Therefore, the adsorbent can be prevented from peeling off despite the heat cycle of cooling and heating the adsorption panel, and the durability of the cryo-adsorption pump can be increased. Furthermore, since the adsorbent is embedded, heat conduction is good, and the entirety of each adsorbent is efficiently cooled by the cryogenic cooling section, thus making it possible to increase and stabilize the pumping speed and adsorption capacity for adsorbing and exhausting gas. Furthermore, since the distribution pattern of the adsorbent can be determined by the distribution pattern of the holes for embedding the adsorbent in the low-melting point metal plate, it is possible to obtain cloth with the ideal amount of adsorbent.
Wear.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional cryo-adsorption pump!
2 is an enlarged view of the configuration of the gas adsorption panel taken along the line II-II in FIG. 1, and FIG. 3 is a sectional view taken along the line T1 in FIG.
FIG. 4 and FIG. 5 are a sectional view showing a low melting point metal plate of a cryo-adsorption pump according to an embodiment of the present invention, and its v
-V line view, Figures 6 and 7 are cross-sectional views showing the relationship between the low melting point metal plate, activated carbon, and template just before heating, its ■-VI line arrow view, and Figure 8 shows the bolt dummy. Figures 9 and 10 are a plan view showing the gas adsorption panel of the above embodiment attached to the cryogenic cooling unit, and its
-X-ray cross-sectional view; Figure 11 is a cross-sectional view showing a holding plate used when heating and melting a low-melting point metal plate; Figures 12 and 13 are plan views showing different embodiments. and its xm
-xm line sectional view, Figure 14 is a plan view showing another example of a low melting point metal plate, and Figures 15 and 16 are plan views showing a gas adsorption panel using the low melting point metal plate shown in Figure 14, respectively. The figure and its cross-sectional view taken along the line X Vl - FIG. DESCRIPTION OF SYMBOLS 1...Cryogenic temperature cooling part, 10...Low melting point metal plate, 11
゜20... Hole for embedding activated carbon, 13.18... Template, 14.21.22... Activated carbon. Applicant's agent Kiyoshi Inomata Figure 2 Figure 6 - A Figure 14 Brown 17 Figure R! 6 Figure E

Claims (1)

[Claims] 1. A cooling unit that is cooled to an extremely low temperature by a refrigerant liquid, and a low melting point unit that is attached to the cooling unit on one surface and has a number of holes drilled in the opposite surface of the cooling unit. A cryopump comprising a metal plate and a small particulate adsorbent partially embedded in the pores of the low melting point metal plate. 2. The cryopump according to claim 1, wherein the low-melting point metal plate is heated and melted with a portion of the adsorbent embedded in its pores. 3. Claims characterized in that the adsorbent is activated carbon shaped into a shape corresponding to the shape of the pores, and the pores are distributed almost uniformly in the low melting point metal plate. The cryopump according to item 1. 4. The cryopump according to claim 1, wherein the diameter of the lower end of the portion embedded in the hole of the adsorbent is set larger than the diameter of the upper end. . 5. The cryopump according to claim 1, wherein the hole is one of a through hole and a bottomed hole. 6. A cooling part that is cooled to an extremely low temperature by a refrigerant liquid, a template that is attached to this cooling part and has a frame around it, and one surface of which is welded to this template and a surface that is opposite to this surface that is welded to the template. A cryopump 7 characterized by comprising a low melting point metal plate with a large number of holes bored therein, and a small particulate adsorbent partially embedded in the holes of the low melting point metal plate; 7. The cryopump according to claim 6, wherein the metal plate is heated and melted after being placed on the template with part of the adsorbent embedded in the holes. 8. Claims characterized in that the adsorbent is activated carbon shaped into a shape corresponding to the shape of the pores, and the pores are almost uniformly distributed in the low melting point metal plate. The cryopump according to item 6. 9. The cryopump according to claim 6, wherein the diameter of the lower end of the portion embedded in the hole of the adsorbent is set larger than the diameter of the upper end. 10. The cryopump according to claim 6, wherein the hole is one of a through hole and a bottomed hole.