JPH0633872A - Regeneration of cryopump and device therefor - Google Patents

Abstract

PURPOSE:To shorten the regeneration time of a cryopump. CONSTITUTION:One edge of a gas introducing pipe 11a for introducing nitrogen gas is arrgaged, penetrating through the bottom part of the pump container 2 of a cryopump 1 and the bottom part of a first stage cryopanel 4. A gas introducing valve 13 is connected at the other edge side of the gas introducing pipe 11a, and nitrogen gas is inrroduced into the pump container 2 through opening and closing the gas introducing valve 13. Further, one edge of a gas leading-out pipe 12a for leading out the gas introduced into the pump container 2 is arranged on the bottom part of pump container 2. At the edge part on the discharge side of the gas leading-out pipe 12a, a gas leading-out valve 14 is connected, and further on the discharge side of the gas leading-out valve 14, a moisture detector 10 is installed, having a pipe 12b interposed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for regenerating a cryopump.

[0002]

2. Description of the Related Art A cryopump having a high temperature side cooling section and a low temperature side cooling section cooled by a small helium refrigerator is used for many vacuum exhaust operations. As shown in FIG. 5, in this type of cryopump 20, the tubular pump container 2 is attached to the helium refrigerator 3 and the pump container 2
The cooling section on the high temperature side, that is, the first-stage cryopanel 4 is provided in the inside of
A step cryopanel 5 is provided.

With such a structure, the cryopump condenses various gases to be exhausted on the surfaces of the cryopanels 4 and 5 or adsorbs the adsorbent 9 provided inside the second-stage cryopanel 5. Since it is a vacuum pump that exhausts by storing it, if the amount of stored gas increases,
Since the amount of exhaust decreases and the ultimate pressure cannot be obtained, a regeneration operation is required in order to discharge the stored gas so that the gas can be exhausted again. Cryopump regeneration is
This is carried out by returning the temperature of the cryopump to room temperature, turning the gas stored by condensation or adsorption into a gas or liquid (especially in the case of water), and leading it out of the pump and removing it.

As a method of raising the temperature of the cryopump to room temperature, a heater or the like is attached to the outer surface of the pump container of the cryopump to heat the cryopump from the outside, or an inert gas such as nitrogen is introduced into the cryopump, and a gas is supplied. A method of heating and raising the temperature by the amount of heat and a combination of the heating of these heaters and the introduction of gas are performed as a more efficient regeneration.

Among these methods, the gas introduction method is shown in FIG. 5 in which a gas introduction pipe 11a and a gas derivation pipe 12a are attached to the inside of the pump container 2 of the cryopump 20 to remove nitrogen or the like heated from the gas introduction pipe 11a. When the inert gas is introduced into the pump container 2 and the temperature inside the container 2 is increased, the condensed gas is vaporized and is discharged together with nitrogen to the outside of the pump through the gas discharge pipe and removed. Gases with a high vapor pressure, such as argon, nitrogen, and hydrogen, have been completely vaporized if the temperature inside the pump container 2 has risen to room temperature, and are therefore discharged outside the pump container 2 together with the introduced nitrogen gas. It

[0006]

However, the most difficult to remove from the cryopump is water. Since water is mostly liquid at room temperature and has a low vapor pressure, it takes time to evaporate and dry by the flow of nitrogen gas. Also, it is difficult to determine whether all the water has evaporated, so it is empirically determined how long the nitrogen introduction time will be required after the pump has returned to room temperature. Further, since the exhaust amount of water changes with each regeneration, it is necessary to expect a considerable safety factor in the gas introduction time. For this reason, there is a problem in that the gas introduction time takes longer than necessary and the operating rate of the apparatus is lowered.

The present invention has been made in view of the above problems, and by introducing an inert gas such as nitrogen gas into and out of the pump container, the regeneration time of the cryopump can be extended to a greater extent than before. An object of the present invention is to provide a regenerating method and a regenerating device for a cryopump that can be shortened.

[0008]

The above object is to introduce a heated inert gas into the pump container in a method for regenerating a cryopump having a cooling section cooled by a refrigerator in the pump container. When the pressure in the pump container reaches atmospheric pressure due to the inert gas, a step of introducing the heated inert gas to the outside from the pump container and introducing the heated inert gas into the outside A step of detecting the water content when the introduction of the active gas is started, a step of detecting a change in the water content in the pump container after the derivation of the inert gas, and the water content becomes the water content when the introduction of the inert gas is started. It is achieved by a method for regenerating a cryopump.

Further, the above-mentioned object is to carry out the regeneration of the cryopump while introducing the heated inert gas into the pump container of the cryopump having the cooling section cooled by the refrigerator. The regenerating apparatus of the cryopump described above is provided with a moisture detector for detecting a change in moisture in the pump container.

[0010]

[Function] Since the change in the water content in the pump container is detected, if water remains in the pump container during the introduction and discharge of the inert gas, the water content in the discharged gas is Changes in water content can be detected. The water concentration after the introduction of the inert gas once rises, the inside of the pump container begins to dry, and decreases to the same level as the water content when it was introduced. By detecting the change in water content in the pump container during the introduction and introduction of the inert gas, it is possible to know when the inside of the pump container is dried, and the introduction of the inert gas is stopped at this point.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A cryopump regenerating method and a regenerating apparatus according to a first embodiment of the present invention will be described below with reference to the drawings. The same components as those of the conventional example will be described with the same reference numerals.

In FIG. 1, the cryopump according to the present embodiment is indicated by 1 as a whole, and a cylindrical pump container 2 having a flange portion 2a is attached to a helium refrigerator 3 which has a low temperature expansion chamber. First stage freezing stage 7 and second stage freezing stage 8 provided adjacent to each other
Is attached so as to be inserted inside the pump container 2. Further, inside the pump container 2, there is provided a cooling unit that is cooled by the freezing stages 7 and 8 by heat conduction. To briefly explain the structure of this cooling unit, a first-stage cryopanel 4 and a second-stage cryopanel 5 made of a thin plate of oxygen-free copper or a metal plate made of aluminum are provided in the pump container 2. The outer first-stage cryopanel 4 is formed in a cup shape, is disposed upward on the first-stage freezing stage 7, and a baffle 6 is provided at the upper end thereof.

Further, a second-stage cryopanel 5 is formed in a cup shape inside the first-stage cryopanel 4, and is arranged downward on the second-stage freezing stage 8. An adsorbent 9 such as activated carbon or molecular sieves is provided inside the second-stage cryopanel.

The structure of the regenerator F for regenerating the cryopump 1 will be described. Nitrogen gas is introduced through the left bottom portion of the pump container 2 in the drawing and the left bottom portion of the first-stage cryopanel 4. One end of the gas introduction pipe 11a is arranged. The gas introduction pipe 11a is arranged at the bottom of the pump container 2 in an airtight manner with the outside air, and is connected to a heating nitrogen supply source (not shown) via a pipe 11b and a gas introduction valve 13. The gas introduction valve 13 controls the supply and stop of the nitrogen gas introduced into the pump container 2 by opening and closing the valve. Further, a gas outlet pipe 12a for leading out the gas introduced into the pump container 2 is provided on the bottom right side of the pump container 2.
Has one end penetrating through the bottom portion, and the bottom portion and the gas outlet pipe 12a are arranged airtight with the outside air. A gas outlet valve 14 is connected to the discharge side end of the gas outlet pipe 12a, and a pipe 12b is interposed on the outlet side of the gas outlet valve 14 to connect the moisture detector 10 (herein, referred to in this specification). In, the moisture detector includes a humidity detector and the like, which are equivalent thereto. The gas outlet valve 14 controls the discharge and stop of nitrogen gas by opening and closing the valve. Further, an atmospheric pressure checker PS for checking whether the inside of the pump container 2 is at atmospheric pressure is connected to the gas outlet pipe 12a.

In the cryopump 1 thus constructed, the flange portion 2a of the pump container 2 is connected to a vacuum device (not shown) through the main valve, and a refrigeration cycle is circulated outside the cryopump 1. A compressor is connected that allows it.

The cryopump 1 according to the first embodiment of the present invention is constructed as described above, and its operation will be described below.

After depressurizing (rough evacuation) to a predetermined pressure in a vacuum device (not shown) to which the cryopump 1 is attached, the refrigeration cycle of the cryopump 1 is started. As a result, the first stage freezing stage 7 and the second stage freezing stage 8 are each cooled to a predetermined temperature. Desirable temperatures of the respective cryopanels 4 and 5 are 70K to 90K for the first-stage cryopanel 4 and 10K to 20K for the second-stage cryopanel 5.

When the cryopump 1 operates, the baffle 6 and the first-stage cryopanel 4 condense and solidify water vapor, carbon dioxide, etc., which have a high condensation temperature, out of the gas molecules flowing in from this opening, and the condensation temperature is higher than this. Condensable gases such as low-oxygen oxygen, nitrogen, and argon are used in the second-stage cryopanel 5
Is condensed and solidified. Since hydrogen and helium, which have the lowest condensation temperature than these condensable gases, cannot be condensed by the cryopanels 4 and 5, they are adsorbed by the adsorbent 9.

In this way, the cryopump 1 operates,
When the gas is condensed and solidified or adsorbed on each of the cryopanels 4 and 5 and the adsorbent 9 and the amount of these is increased, the exhaust speed of the gas may be decreased or the ultimate pressure may not be obtained, and the cryopump 1 is regenerated. Work is required. Less than,
The reproducing procedure will be described.

When the operation of the cryopump 1 is stopped and the gas introduction valve 13 is opened, the heated nitrogen gas is introduced into the pump container 2 which is a substantially vacuum space. At this point, the gas outlet valve 14 remains closed, so
The pump container 2 and the gas outlet pipe 12a have the same pressure. When it is confirmed by the atmospheric pressure checker PS that the inside of the pump container 2 has reached the atmospheric pressure, the gas outlet valve 14 is opened and nitrogen gas is led out of the pump container 2 through the gas outlet pipe 12a. The nitrogen gas is exhausted through the gas outlet valve 14 and the moisture detector 10. The amount of water at this time, that is, the humidity detected by the water detector 10 is the humidity of nitrogen gas, in which the condensed gas is not yet vaporized.

The inside of the pump container 2 is heated by the introduction of nitrogen gas, and further, the end of the gas introduction pipe 11a penetrates the bottom of the cup-shaped first-stage cryopanel 4 and the gas discharge pipe 12a pumps the nitrogen gas. Since it is arranged between the inner wall of the container 2 and the bottom surface of the first-stage cryopanel 4, the nitrogen gas flows through the panel surfaces of the first-stage and second-stage cryopanels 4 and is condensed and solidified there. Alternatively, a gas such as water adsorbed by the adsorbent is vaporized by the heat quantity of the nitrogen gas and is combined with the nitrogen gas and exhausted from the gas outlet pipe 12a to the outside of the pump container 2.

The amount of water vaporized with the nitrogen gas and vaporized outside the pump container 2 will be described in detail with reference to FIG. 2. Regeneration of A to B immediately after the gas introduction valve 13 and the gas derivation valve 14 are opened. In the starting state, the temperature rise in the pump container 2 is small, and the humidity detected by the moisture detector 10 is the amount of nitrogen gas humidity. When the inside of the pump container 2 begins to exceed 0 ° C (point B) due to the heat of nitrogen gas,
The evaporation of water begins and the amount of evaporation increases. As a result, as shown between B and C, the humidity detected by the moisture detector 10 becomes higher than the humidity level of the introduced nitrogen gas, and gradually reaches the high level. In this high level state, as shown between C and D, by continuing the introduction and derivation of nitrogen into the pump container 2, the pump container 2
Moisture inside is also discharged together with nitrogen gas. Eventually, as the water content in the pump container 2 decreases, the humidity of the discharged nitrogen gas decreases as indicated by D to E, and the humidity detection amount of the water content detector 10 becomes the initial nitrogen humidity level. It is detected that the same level of E is reached. Pump container 2 at this point
Since the removal of water from the inside has been completed, the gas introduction valve 1
3 and the gas outlet valve 14 are closed.

As described above, in the present embodiment, the water content in the nitrogen gas to be released can be detected by the water content detector 10, and the introduction and delivery of the nitrogen gas is continued to completely evaporate the water content in the pump container 2. After the removal, the water concentration in the derivation gas of nitrogen decreases to the same level as the water concentration of the introduced nitrogen gas, so that it can be known that the inside of the pump is completely dried. By stopping the introduction of nitrogen gas at this point, it is not necessary to take a safety factor for the gas introduction time, the introduction time of nitrogen gas, that is, the regeneration time of the cryopump can be shortened, and the moisture content in the pump container 2 can be shortened. The removal can be performed efficiently and reliably.

After the above work is completed, the pump container 2
The inside is roughly pumped to a predetermined pressure by a not-shown roughing pump, and when the roughing is completed, the cryopump 1 is started to cool the inside of the pump container 2. When the cooling is completed, the cryopump 1 is ready to exhaust the gas, and the regeneration of the cryopump 1 is completed.

Next, a method and apparatus for regenerating a cryopump according to the second embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 3, the cryopump according to this embodiment is designated by 21 as a whole.
Explaining the configuration of the regenerating device G for regenerating the water, a hole 16 penetrating the peripheral wall of the pump container 15 is provided, and the detecting portion of the water detector 10a faces the hole 16 to detect the water content. The container 10a is attached. In the first embodiment, the humidity of the nitrogen gas introduced into the hole 16 from the inside of the pump container 2 is detected instead of detecting the humidity of the nitrogen gas by connecting to the conduit of the gas outlet pipe.
The regenerator G for the cryopump 21 according to the present embodiment is configured as described above, but other configurations such as the cooling portion of the cryopump 21 are the same as those in the first embodiment, and the regenerating process is also performed. Is also the same.

Although it is most efficient to attach the moisture detector to the conduit on the gas outlet pipe side as in the first embodiment, it can be known that the interior of the pump container 15 is completely dry even with the structure according to this embodiment. It is possible to shorten the introduction time of nitrogen gas, that is, the regeneration time of the cryopump 21, without removing the safety factor for the gas introduction time, and to efficiently and surely remove the water in the pump container 15. It is obvious that

Next, a method and apparatus for regenerating a cryopump according to a third embodiment of the present invention will be described with reference to FIG. The cooling unit of the cryopump has the same configuration as that of the first embodiment, and detailed description thereof will be omitted.

Referring to FIG. 4, the structure of the regenerator H for regenerating the cryopump 22 according to this embodiment will be described. The regenerator H is attached to the vacuum device 25 with the manifold 27 and the vacuum valve 26 interposed therebetween. Manifold 27
One end of a gas introduction pipe 29a for introducing the heated nitrogen gas is connected to the peripheral wall 27a. Gas introduction pipe 29a
Is connected to the peripheral wall 27a of the manifold 27 in an airtight manner with the outside air, and is connected to a heating nitrogen supply source (not shown) through a pipe 29b and a gas introduction valve 31. The gas introduction valve 31 is opened and closed to open the pump container 24.
The supply and stop of the nitrogen gas introduced into the inside is controlled. In addition, the peripheral wall 27 facing the peripheral wall 27 a of the manifold 27.
In b, one end of a gas lead-out pipe 30a for leading the gas introduced into the pump container 24 from the manifold 27 and returned to the manifold 27 to the outside is disposed in the peripheral wall 27b in an airtight manner with the outside air. A gas outlet valve 32 is connected to the discharge side end of the gas outlet pipe 30a, and a moisture detector 28 is attached to the outlet side of the gas outlet valve 32 with a pipe 30b interposed.

Although the configuration of the third embodiment of the present invention has been described above, it can be known that the inside of the pump container 24 is completely dried by the same regeneration process as in the first embodiment in the third embodiment. Therefore, it is not necessary to take a safety factor with respect to the gas introduction time, the introduction time of nitrogen gas can be shortened, that is, the regeneration time of the cryopump 22 can be shortened, and the water in the pump container 24 can be removed efficiently and reliably. Is clear.

Although the respective embodiments of the present invention have been described above, the present invention is not limited to these, and various modifications can be made based on the technical idea of the present invention.

For example, although nitrogen gas was used as the inert gas to be introduced into the pump container in each of the above-described embodiments, this is not limited to nitrogen gas, and other inert gas may be used. Further, of course, the invention can be applied to the case where the cryopump is regenerated by using the heater heating and the gas in combination as described in the conventional example.

Although the moisture detector is mounted on the discharge side of the gas outlet valve in the first and third embodiments, it may be mounted between the cryopump and the gas outlet valve.

Further, in the second embodiment, the gas detector is attached by forming a hole in the peripheral wall of the pump container, but this may be installed in the pump container. For example, the detection part of the moisture detector may be installed in the pump container. You may attach to other positions in a pump container, such as a wall part and a 2nd freezing stage. In this case, the moisture detection signal may be derived from the lead wire by hermetically inserting the lead wire into the pump container.

[0035]

As described above, according to the regenerating method and the regenerating apparatus of the cryopump of the present invention, the change in the water content of the inert gas in the pump container of the cryopump is detected to detect the change in the inside of the pump container. It can be known that the water has been removed, and the gas introduction can be stopped when the water disappears from the pump container. As a result, the regeneration time of the cryopump can be greatly shortened and the operating rate can be improved.

[Brief description of drawings]

FIG. 1 is a schematic partially cutaway front view of a main part of a cryopump according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a change in humidity of nitrogen gas introduced into and discharged from the pump container.

FIG. 3 is a schematic partially cutaway front view of a main part of a cryopump according to a second embodiment of the present invention.

FIG. 4 is a schematic front view of a main part of a cryopump according to a third embodiment of the present invention.

FIG. 5 is a schematic partially cutaway front view of a main part of a conventional cryopump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cryo pump 2 Pump container 3 Refrigerator 4 1st stage cryo panel 5 2nd stage cryo panel 6 Baffle 10 Moisture detector 10a Moisture detector 15 Pump container 21 Cryo pump 22 Cryo pump 24 Pump container 28 Moisture detector F Regeneration device G playback device H playback device

Claims (2)

[Claims] 1. A method for regenerating a cryopump having a cooling section cooled by a refrigerator in a pump container,
A step of introducing a heated inert gas into the pump container; and, when the pressure in the pump container reaches atmospheric pressure due to the inert gas, while the heated inert gas is being introduced, the outside of the pump container And a step of detecting moisture when starting to introduce the heated inert gas into the pump container, and a step of detecting a change in moisture in the pump container after the inert gas is introduced. And a step of detecting that the water content has become the water content at the time of starting the introduction of the inert gas. 2. A cryopump regenerator in which a heated inert gas is introduced into a pump container of a cryopump having a cooling section cooled by a refrigerator while the heated inert gas is introduced and regenerated. A regenerating apparatus for a cryopump, comprising a moisture detector for detecting a change in moisture in the pump container.