JPH11182956A - Cold storage type refrigerating machine and evacuating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a refrigerating machine suitable for a cryopump capable of effecting efficient condensing of gas by a method wherein the refrigerating machine is provided with a heat resistant member having a low heat conductivity and a cooling panel, arranged so as to surround the periphery of a cooling stage. SOLUTION: Cold heat transferred to a cooling panel 41 through a heat resistant member 40 and, therefore, the temperature of the cooling panel 41 becomes slightly higher than that of a cooling stage 10. The cooling stage 10 and the cooling panel 41 can be heated by adiabatic compression heat generated in the internal cavities of a first heating unit 50 and a second heating unit 52 when cooling gas is introduced. According to the temperature rise, gas, adsorbed to the cooling stage 10 and the cooling panel 4, is released. The regenerative treatment of a cryopump can be effected while operating a refrigerating machine as it is in such a manner. When the refrigerating machine is operated under an environment where H2 gas, condensed on the surface of the cooling state 10, is discharged or, especially, under an environment wherein a big among of H2 gas is condensed, a big effect can be expected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a regenerative refrigerator. The regenerator refrigerator is used, for example, as a cryopump for condensing gas in a vacuum vessel and increasing the degree of vacuum.

[0002]

2. Description of the Related Art In a conventional cryopump, an adsorbent such as activated carbon is adhered to a surface of a metal panel thermally connected to a cooling section of a refrigerator in order to adsorb a low-boiling gas such as helium gas. It had been. This cryopump is connected to a vacuum vessel, and the gas in the vacuum vessel is adsorbed by the adsorbent on the surface of the metal panel, thereby increasing the degree of vacuum.

[0003]

The adsorbent adhered to the surface of the metal panel is easily peeled off, and the peeled adsorbent sometimes contaminates the inside of the cryopump. In addition, since the adsorbent is fixed to the surface of the metal panel with the adhesive, the temperature of the adsorbent becomes higher than the temperature of the metal panel due to the finite thermal conductivity of the adhesive. As the temperature of the adsorbent rises,
The gas adsorption capacity is reduced.

Further, the exhaust capacity by low-temperature adsorption using an adsorbent is smaller than the exhaust capacity of condensing and exhausting gas, and is about 1/100. Therefore, it is necessary to frequently perform the adsorbent regeneration process. For example, when a cryopump is used in a semiconductor manufacturing apparatus, it is necessary to frequently stop the apparatus and perform a regeneration process.

[0005] Further, in order to regenerate activated carbon, it is necessary to supply heated nitrogen gas around the activated carbon to promote the replacement with the adsorbed moisture. For this reason, the reproduction time becomes longer and the reproduction cost becomes higher. In addition, in order to increase the regeneration efficiency, a metal panel to which activated carbon is bonded
The temperature is raised until the regeneration process. This high temperature treatment causes damage to the refrigerator.

[0006] An object of the present invention is to provide a regenerator-type refrigerator suitable for a cryopump capable of efficiently condensing gas.

[0007]

According to one aspect of the present invention, a cylinder having one open end, a displacer reciprocating in the cylinder along an axis thereof, and the one end of the cylinder are provided. A cooling stage that is airtightly coupled to the part and exposes the inner surface to the space inside the cylinder,
A cooling stage including a thin plate-shaped portion projecting from an outer surface of the cooling stage, wherein a portion of the cooling stage exposed to a space in the cylinder and the thin plate-shaped portion are inseparably connected to each other; A refrigerant gas flow path communicating with the cooling cavity defined by the displacer and the cooling stage, introducing refrigerant gas into the cooling cavity, and recovering the refrigerant gas from the cooling cavity; and disposed in the refrigerant gas flow path. And a regenerator-type refrigerator having a refrigerant gas flowing in the refrigerant gas flow path and a regenerator material for performing heat exchange.

When the displacer is reciprocated, and the introduction and recovery of the refrigerant gas into the cooling cavity are repeated in synchronism with the reciprocating movement, cold occurs in the cooling cavity. Since the bottom surface and the inner peripheral surface of the cooling stage are exposed to the cooling cavity, and the cooling stage is made integral, the cold generated inside is efficiently transmitted to the cooling stage.

According to another aspect of the invention, a cylinder having one open end, a displacer reciprocating within the cylinder along an axis thereof, and an airtight connection to the one end of the cylinder A cooling stage having an inner surface exposed in a space inside the cylinder, and communicating with a cooling cavity defined by the cylinder, the displacer, and the cooling stage; introducing a refrigerant gas into the cooling cavity; A refrigerant gas flow path for recovering gas, a cold storage material arranged in the refrigerant gas flow path and performing heat exchange with the refrigerant gas flowing in the refrigerant gas flow path, and attached to the cooling stage; A heat resistance member made of a material having a low thermal conductivity; and a heat resistance member attached to the heat resistance member and arranged so as not to contact the cooling stage and to surround the periphery of the cooling stage. Regenerator refrigerator is provided having a cooling panel.

According to another aspect of the present invention, a cylinder having one open end, a displacer reciprocating in the cylinder along an axis thereof, and an airtight connection to the one end of the cylinder A cooling stage having an inner surface exposed in a space inside the cylinder, and communicating with a cooling cavity defined by the cylinder, the displacer, and the cooling stage; introducing a refrigerant gas into the cooling cavity; A refrigerant gas flow path for recovering a gas, a regenerator material disposed in the refrigerant gas flow path and exchanging heat with the refrigerant gas flowing in the refrigerant gas flow path, and a thermal storage material located at an intermediate position between both ends of the cylinder. And a cooling panel arranged so as to surround the periphery of the cooling stage.

The cooling panel acts as a radiation shield,
The cooling stage can be cooled efficiently.

According to another aspect of the present invention, a step of disposing a metal cooling stage of a regenerator refrigerator in a cavity communicating with a vacuum chamber to be evacuated, and starting the regenerator refrigerator A vacuum evacuation method comprising: cooling the cooling stage to a temperature equal to or lower than the boiling point of helium; and condensing gas in the vacuum chamber directly on the surface of the cooling stage.

By cooling the cooling stage to a temperature lower than the boiling point of helium, a low-boiling gas such as H ₂ gas or Ne gas can be directly condensed on the surface of the cooling stage without using an adsorbent such as activated carbon. it can.

[0014]

FIG. 1 is a sectional view showing the basic structure of a cryopump using a regenerator according to an embodiment of the present invention. A displacer 2 is inserted into an internal cavity of a cylinder 1 whose lower end (low temperature end) is open. The displacer 2 is driven by the displacer driving means 3.
It reciprocates along the axis of the cylinder 1. Cylinder 1 is
For example, it is formed of a rigid material having low thermal conductivity and high airtightness, such as stainless steel. The displacer 2 is formed of, for example, cloth-containing phenol.

A cooling stage 10 is connected to the cold end of the cylinder 1 and defines a space in which the displacer 2 reciprocates together with the cylinder 1. The cooling stage 10 is formed of, for example, oxygen-free copper (JIS C1020) having high thermal conductivity. The joint between the cooling stage 10 and the cylinder 1 is kept airtight by, for example, silver brazing.

The cooling stage 10 has an inner peripheral surface 10 a surrounding the axis of the cylinder 1 and a bottom surface 10 b intersecting the axis of the cylinder 1. The inner peripheral surface 10a and the bottom surface 10b
The displacer 2 is exposed to a space in which the displacer reciprocates.
The inner peripheral surface 10a of the cooling stage 10 substantially coincides with a surface extending from the inner peripheral surface of the cylinder 1 in the axial direction.

The cooling cavity 15 is defined by the displacer 2 and the cooling stage 10. FIG. 1 shows a cooling cavity 15.
The case where all the side surfaces of the cooling stage 10 are defined by the cooling stage 10 is shown.
The height of “a” may be reduced so that a part of the inner peripheral surface of the cylinder 1 is exposed on the side surface of the cooling cavity 15. in this case,
Cylinder 1, displacer 2, and cooling stage 10
Thereby, the cooling cavity 15 is defined.

A refrigerant gas flow path 20 is formed in the displacer 2. The coolant gas passage 20 communicates with the cooling cavity 15 through a communication hole 21 provided at an end of the displacer 2 on the cooling cavity 15 side. Also, the refrigerant gas flow path 20
Communicates with the external gas flow path 25 through a communication hole 22 provided at the high-temperature end of the displacer 2. The external gas passage 25 is connected to the gas discharge side of the gas compressor 30 via an air supply valve V _1, and is connected to the gas compressor 30 via an exhaust valve V _2.
Is connected to the gas supply side.

[0019] to close the exhaust valve V _2, when you open the intake valve V _1,
The high-pressure refrigerant gas passes through the refrigerant gas flow path 20 and passes through the cooling cavity 1.
5 is introduced. Close supply valve V _1, refrigerant gas in the exhaust valve and the cooling cavity 15 opening the V ₂ is recovered in the gas compressor 30 through a refrigerant gas flow path 20. As a refrigerant gas,
For example, helium gas is used.

The refrigerant gas flow path 20 is filled with a cold storage material 23. When the refrigerant gas passes through the refrigerant gas flow path 20, heat exchange is performed between the refrigerant gas and the cold storage material 23.

When the opening and closing of the supply valve V ₁ and the exhaust valve V ₂ are alternately performed at appropriate timing in synchronization with the reciprocating movement of the displacer 2, cold occurs due to adiabatic expansion of the refrigerant gas in the cooling cavity 15. I do.

The cooling stage 10 has a plurality of fins 10c made of, for example, oxygen-free copper on its outer peripheral surface. The fins 10c may be attached to the outer peripheral surface by welding such as silver brazing, or the cylindrical portion of the cooling stage 10 and the fins 10c may be formed simultaneously by shaving one lump of oxygen-free copper. Cooling cavity 15 of cooling stage 10
The fin 10c may be integrally formed with the exposed portion. Here, “integrally inseparable” means a configuration in which removal and attachment cannot be performed repeatedly. For example, the connection by bolting or the like is not inseparable here, but the connection by welding is included in the integral insemination. By integrally forming the cooling stage 10 as an integral unit, the entire cooling stage 10 can be efficiently cooled.

Instead of the fin 10c, a thin plate portion other than the fin may be attached. The thickness of the thin plate is 3
mm or less, more preferably 2 mm or less. In order to enhance the reflectance and corrosion resistance, the outer wall surface of the cooling stage 10 and the surface of the fin 10c may be plated with gold or nickel to reflect radiant heat from the outside.

A heat resistance member 40 is attached to an end of the cooling stage 10 remote from the cooling cavity 15. The thermal resistance member 40 is formed of, for example, stainless steel having a lower thermal conductivity than the cooling stage 10. Thermal resistance member 40
Further, a cooling panel 41 made of, for example, oxygen-free copper is attached. The cooling panel 41 is arranged so as not to contact the cooling stage 10 and to surround the periphery of the cooling stage 10.

It should be noted that the cooling panel 41 may be directly and thermally coupled to an intermediate position between the high temperature end and the low temperature end of the cylinder 1.

The cooling stage 10 is separated from the cooling cavity 15.
The hollow first heating section 50 is thermally coupled to the
I have. The first heating unit 50 is formed of, for example, oxygen-free copper or the like.
Is done. The internal cavity of the first heating unit 50 is used for the first regeneration.
Gas flow path 51 and on-off valve V _ThreeThrough the external gas flow path
25.

A hollow tubular second heating section 52 is mounted on the outer peripheral surface of the cooling panel 41. The second heating unit 52 spirally surrounds the cooling panel 41 and is fixed to the cooling panel 41 by soldering.
1 and thermally coupled. By making the second heating section 52 helical, a large thermal coupling can be obtained.

One end of the second heating section 52 is closed, and a second regeneration gas channel 53 is connected to the other end. Second
The internal cavity of the heating section 52 is provided with a second regeneration gas flow path 53.
And via an on-off valve V _4, communicates with the outer gas flow passage 25.

The cylinder 1, the cooling stage 10, the heat resistance member 40, the cooling panel 41, the first heating unit 50, and the second heating unit 52 are inserted into the vacuum vessel 60, and the high temperature end of the cylinder 1 and the vacuum vessel 60 are hermetically sealed. The outer peripheral surface of the cylinder 1, the outer wall surface of the cooling stage 10,
The vacuum chamber 61 is defined by the vacuum container 60 and the vacuum chamber 61.

By causing the displacer 20 to reciprocate and repeating the introduction and recovery of the refrigerant gas into the cooling cavity 15 in synchronization with the reciprocating movement, cold occurs in the cooling cavity 15. The cooling stage 10 is formed of a material having a higher thermal conductivity than the cylinder 1, and its inner peripheral surface and bottom surface are exposed to the cooling cavity 15. It can be cooled efficiently. The gas in the vacuum chamber 61 is condensed on the outer wall surface of the cooling stage 10 and the surface of the fin 10c,
The degree of vacuum inside can be increased.

The cold generated in the cooling stage 10 is transmitted to the cooling panel 41 through the heat resistance member 40. The cooling panel 41 is arranged so as to surround the cooling stage 10. Since the cold is transmitted to the cooling panel 41 via the heat resistance member 40, the temperature of the cooling panel 41 is slightly higher than the temperature of the cooling stage 10. For example, when the cooling stage 10 is cooled to 4.2K or less, the temperature of the cooling panel 41 becomes about 10 to 20K. Therefore, N
Gases having a relatively high boiling point, such as ₂ gas, O ₂ gas, and Ar gas, are condensed on the surface of the cooling panel 41.

Next, a method of desorbing the gas condensed in the cooling stage 10 and regenerating the cryopump will be described.

The displacer driving means 3 is operated with the on-off valves V ₃ and V ₄ opened, and the supply valve V ₁ and the exhaust valve V
Open and close ₂ . In synchronization with the cycle of introducing and collecting the refrigerant gas into the cooling cavity 15, the introduction and collection of the refrigerant gas into the internal cavities of the first heating unit 50 and the second heating unit 52 are performed. When the refrigerant gas is introduced, the first heating unit 5
The cooling stage 10 and the cooling panel 41 can be heated by the adiabatic compression heat generated in the internal cavities of the zero and second heating units 52. Due to this temperature rise, the gas adsorbed by the cooling stage 10 and the cooling panel 41 is desorbed. Thus, the cryopump can be regenerated while the refrigerator is operating.

H ₂ condensed on the surface of the cooling stage 10
If the temperature is raised to a temperature at which the gas is released and the Ar gas is not released, the regeneration time can be further reduced. In particular, when operating in an environment where a large amount of H ₂ gas is condensed, a great effect can be expected.

Since the heating section 52 is spirally wound around the cooling panel 41, the contact area between them increases, and the cooling panel 41 can be heated more efficiently. The heating unit 50 also has a cooling stage 1 like the heating unit 52.
0 may be wound around the outer wall.

[0036] In the case of performing playback processing of only cooling stage 10 opens the opening and closing valve V _3, can be operated to close the on-off valve V _4.

FIG. 2 shows a configuration example using a two-stage Gifford McMahon (GM) refrigerator as a refrigerator having a basic configuration of the cryopump according to the above embodiment. The cryopump shown in FIG. 2 includes a pump housing 70, a vacuum vessel 71, and a two-stage GM refrigerator 72.

The pump housing 70 has a GM inside.
A refrigerator 72 is housed. Also, the pump housing 7
0 and the vacuum container 71 are hermetically connected at their openings, and a vacuum chamber 74 is defined. The pump housing 70 is provided with an atmosphere release valve (safety valve) 73 for releasing the atmosphere into the vacuum chamber 74.

The vacuum chamber 74 accommodates, for example, a semiconductor manufacturing apparatus. The processing gas such as argon gas is supplied to the on-off valve 7.
5. Flow controller 76, on-off valve 77, gas inlet 7
8 and into the vacuum chamber 74 via the gas introduction pipe 79. The inside of the vacuum chamber 74 is roughly evacuated to a predetermined degree of vacuum by a vacuum pump 81 via a vacuum valve 80. Vacuum chamber 74
The internal pressure is measured by a vacuum gauge 82.

The GM refrigerator 72 has a two-stage structure including the cylinder 1 and the displacer 2 of the refrigerator shown in FIG. That is, the first-stage cylinder 1B and the second-stage cylinder 1A are connected in series, and the first-stage displacer 2B and the second-stage displacer 2
A is inserted. The first-stage and second-stage displacers 2B, 2A are first-stage and second-stage cylinders 1A, 1A by a displacer driving means 3 having a crank mechanism.
Reciprocate in B. First stage displacer 2B and first stage
The gap with the step cylinder 1B is sealed by a seal member 13 near the high temperature end.

First and second stage displacers 2B, 2B
A includes first and second stage refrigerant gas passages 20 respectively.
B and 20A are formed, and cold storage materials 23B and 23A are loaded in these channels, respectively.

FIG. 3 is a detailed partially cutaway front view of the second stage displacer 2A. An abrasion-resistant resin member 92 made of cloth-containing phenol is fixed on the surface of a cylindrical stainless steel tube 91 to form a cylindrical member 90.
The internal space of the tubular member 90 corresponds to the second-stage refrigerant gas flow path 20A shown in FIG. By arranging the stainless steel tube having high mechanical strength inside, heat shrinkage of the wear-resistant resin member 92 during cooling is suppressed. Therefore, the thermal deformation characteristics of the stainless steel cylinder and the displacer are similar.

The cylindrical member 90 has a cylindrical shape whose upper and lower ends are open. At the lower end of the tubular member 90, a cover member 94 formed of phenol containing cloth or the like is inserted and adhered, and a wire mesh 95 is disposed thereon, and a felt plug 96 is disposed thereon.

The felt plug 96 is filled with a regenerator material 23A made of, for example, lead balls and a magnetic material. A felt plug 97 is arranged on the cold storage material 23A filled in the stainless steel tube 91, and a punching metal 98 is arranged on the felt plug 97. Punching metal 98
Is fixed by an annular lid member 93 inserted into the open upper end portion of the tubular member 90. At the upper end of the tubular member 90, a coupling mechanism 99 for coupling to the first-stage displacer 2B shown in FIG. 2 is attached.

On the side wall of the tubular member 90, an opening 100 for forming a gas flow path is provided at a height of the wire mesh 95. On the outer peripheral surface above the opening 100 of the tubular member 90,
A helical gas flow path 101 composed of one helical groove connecting the position of the opening 100 and the upper end is formed. This groove has, for example, a width of about 2 mm, a depth of about 0.6 mm, and a pitch of about 4 mm.

Instead of the spiral groove 101, a groove pattern including a groove in a direction intersecting the axial direction of the first stage displacer 2B may be formed. Also in this case, compared with the case where the refrigerant gas flows in parallel to the axial direction of the displacer,
More heat exchange could be performed.

The outer diameter of the tubular member 90 below the opening 100 is slightly smaller than the outer diameter of the portion above it. Therefore, a gap is formed between the tubular member 90 and the second-stage cylinder in a portion below the opening 100. The gap and the opening 100 are connected to the communication hole 21 shown in FIG.
A.

As shown in FIG. 2, a first-stage cooling cavity 15B is defined at the lower end of the drawing of the first-stage cylinder 1B, and a second-stage cooling cavity 15A is defined at the lower end of the drawing of the second-stage cylinder 1A. ing. The first-stage refrigerant gas flow path 20B communicates with the cavity at the upper end of the first-stage cylinder 1B through a communication hole 22B provided at the upper end of the first-stage displacer 2B in the drawing, and through the communication hole 21B. To the first stage cooling cavity 15B. The first-stage cooling cavity 15B communicates with the second-stage refrigerant gas flow path 20A through a communication hole 22A provided at the upper end of the second-stage displacer 2A in the drawing, and the second-stage refrigerant gas flow path 20A It communicates with the second stage cooling cavity 15A via the communication hole 21A.

Around the first cooling cavity 15B, a first cooling stage 10B is thermally coupled to the first cylinder 1B. 2nd stage cylinder 1A, 2nd stage displacer 2A, cooling stage 10, heat resistance member 40, cooling panel 41, first heating unit 50, second heating unit 52
Has the same configuration as that of FIG. The gas compressor 30, the air supply valve V _1, the exhaust valves V ₂ and the external gas channel 25
Has the same configuration as that of FIG.

The cooling panel 1 is mounted on the first cooling stage 10B.
1 is attached. The cooling panel 11 is arranged so as to surround the second-stage cylinder 1A, the second-stage cooling stage 10A, and the periphery of the cooling panel 41, and the baffle plate 12 is attached to an opening at a tip end thereof. The cooling panel 11 functions as a radiation shield plate.

A third heating section 54 having the same configuration as the first heating section 50 is thermally coupled to the first cooling stage 10B. Third internal cavity of the heating unit 54, the third external gas channel 25 through the regeneration gas flow path 55 and the on-off valve V ₅
Is in communication with

[0052] Opening the intake valve V _1, the compressed refrigerant gas,
The gas is introduced into the first-stage cooling cavity 15B through the external gas passage 25, the communication hole 22B, the first-stage refrigerant gas passage 23B, and the communication hole 21B. Furthermore, the second-stage cooling cavity 15 through the communication hole 22A, the second-stage refrigerant gas flow path 23A, and the communication hole 21A.
A is introduced into A. Opening the exhaust valve V _2, the refrigerant gas in the second stage cooling cavity 15A is collected in the gas compressor 30 through the introduction time and reverse path.

By repeating the opening and closing of the supply valve V ₁ and the exhaust valve V ₂ and the reciprocating motion of the first and second stage displacers 2 B and 2 A while maintaining a predetermined phase relationship,
Cold occurs in the first stage cooling cavity 15B and the second stage cooling cavity 15A. Actually, the vacuum chamber 7 is controlled by the vacuum pump 81.
4 is roughly evacuated to about 1 Pa, and after closing the vacuum valve 80, the GM refrigerator 72 is started.

First stage cooling cavity 15B and second stage cooling cavity 1
5A, most of the refrigerant gas is stored in the cold storage material 23.
A flows through the refrigerant gas flow path 20A in which A is disposed. Some of the refrigerant gas flows along the spiral groove 101 shown in FIG.
It flows between the outer peripheral surface of the stage displacer 2A and the inner peripheral surface of the second stage cylinder 1A. The refrigerant gas flowing along the spiral groove 101 performs more heat exchange with the displacer or the cylinder than when the refrigerant gas flows linearly in the axial direction of the displacer. Therefore, the second-stage refrigerant gas flow path 20
The heat loss due to the refrigerant gas branching off from A can be reduced.

Further, since there is no need to provide a seal member between the displacer and the cylinder, it is possible to prevent a decrease in cooling capacity due to incomplete sealing.

The outer peripheral surface of the second stage displacer 2A and the second
The gap between the inner peripheral surface of the step cylinder 1A is preferably 0.01 mm or more in order to stably drive the displacer back and forth, and in order to prevent the leakage gas from flowing linearly in the axial direction, It is preferably 0.03 mm or less.

The two-stage GM refrigerator shown in FIG.
For example, if the first cooling stage 10B is
The second cooling stage 10A can be cooled to 4.2K or less. At this time, the cooling panel 41 is
It is cooled down to about 20K.

The cold generated in the first cooling cavity 15B is transmitted to the baffle plate 12 through the first cooling stage 10B and the cooling panel 11. High-boiling gas such as water vapor or carbon dioxide in the vacuum chamber 74 is condensed on the surface of the baffle plate 12. Gases with the lowest boiling points, such as Ne, H ₂ and He,
It is condensed on the surfaces of the second cooling stage 10 and the fins 10c. Gases having a moderate boiling point, such as N ₂ , O ₂ , and Ar, are condensed on the surface of the cooling panel 41.

FIG. 4 shows the cryopon shown in FIGS. 2 and 3.
H_TwoThe measurement results of gas exhaust speed are
H of pump_TwoShown in comparison with the gas pumping speed. The horizontal axis of the figure is true
The pressure in the vacant chamber 74 is represented by the unit Pa, and the vertical axis represents the exhaust speed.
Expressed in the unit “liter per second”. The symbol ○ in the figure is
And the pumping speed of the cryopump shown in FIG.
5 shows the pumping speed of a conventional cryopump. The implementation
The second cooling stage 10 of the cryopump according to the example and
The surface area of the outer wall surface of the fin 10c is about 500 cm ^TwoIn
You. Of the cryopump of the embodiment during the measurement of the pumping speed
The temperature of the second cooling stage 10A is 3.5K, the first cooling stage
The temperature of the recycle stage 10B was 65K.

FIG. 5 schematically shows the structure of the second cooling stage of the conventional cryopump. The low-temperature end of the second stage cylinder 150 is closed, and the second stage cooling stage 1
51 are not directly exposed to the cooling cavity 152. A cylindrical cooling panel 1 having one end closed is provided on the second cooling stage 151.
53 are connected at the bottom surface. The side wall is
It surrounds the vicinity of the cylinder 150 near the low-temperature end.
Activated carbon 154 is bonded on the inner peripheral surface of cooling panel 153.

The cryopump used for the measurement was an ANSI 6 inch (bore diameter 200 m) in both the embodiment and the conventional example.
m) Standard.

As shown in FIG. 4, in the entire pressure range from 3 × 10 ⁻⁴ Pa to 1 × 10 ⁻² Pa, the pumping speed of the cryopump according to the embodiment is higher than that of the conventional cryopump. Was also big. It is considered that this is because the second stage cooling stage 10A is directly exposed to the second stage cooling cavity 15A without passing through a cylinder as shown in FIG. 2, so that the cooling efficiency is high. Further, it is considered that the cooling efficiency was increased by arranging the cooling panel 41 so as to surround the periphery of the second cooling stage 10A.

As described above, since the cooling stage 10 can be efficiently cooled to a temperature lower than the boiling point of helium gas (temperature: 4.2 K), the cooling stage 10 can be used without using an adsorbent such as activated carbon.
For example, a low-boiling gas such as H ₂ gas can be condensed on the surfaces of the cooling stage 10 and the fins 10c. For this reason, contamination in the cryopump due to separation of the adsorbent can be prevented.

In the above embodiment, the case where the GM refrigerator is used has been described as an example. However, the present invention can be applied to a refrigerator having a cylinder and a displacer other than the GM refrigerator. For example, it can be applied to a Stirling refrigerator.

The present invention has been described in connection with the preferred embodiments.
The present invention is not limited to these. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0066]

As described above, according to the present invention,
Since the cooling stage is exposed to the cooling cavity and the cooling stage is made integral, the cold generated in the cooling cavity is directly transmitted to the cooling stage. Therefore, the cooling stage can be efficiently cooled. When this refrigerator is used for a cryopump, a low-boiling gas such as H ₂ gas can be condensed without using an adsorbent such as activated carbon.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a basic configuration of a regenerative refrigerator according to an embodiment of the present invention.

FIG. 2 is a sectional view of a cryopump in which the basic configuration shown in FIG. 1 is applied to a two-stage GM refrigerator.

FIG. 3 is a sectional view showing details of a second stage displacer of the GM refrigerator shown in FIG. 2;

FIG. 4 is a graph showing the pumping speed of the cryopump according to the embodiment in comparison with the pumping speed of the conventional cryopump.

FIG. 5 is a sectional view schematically showing a cooling stage of a conventional cryopump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder 2 Displacer 3 Displacer driving means 10 Cooling stage 11 First stage cooling panel 12 Baffle plate 13 Seal member 15 Cooling cavity 20 Refrigerant gas flow path 21, 22 Communication hole 25 External gas flow path 30 Gas compressor 40 Heat resistance member 41 Cooling panel 50 First heating unit 51 First regeneration gas channel 52 Second heating unit 53 Second regeneration gas channel 54 Third heating unit 55 Third regeneration gas channel 60 Vacuum container 61 Vacuum chamber 70 Pump housing 71 Vacuum container 72 GM refrigerator 73 Atmospheric discharge valve 74 Vacuum chamber 75 On-off valve 76 Flow controller 77 On-off valve 78 Gas inlet 79 Gas inlet pipe 80 Vacuum valve 81 Vacuum pump 82 Vacuum gauge 90 Cylindrical member 91 Stainless steel pipe 92 Abrasion resistant resin member 93, 94 Lid member 95 Wire mesh 96, 97 Eruto plug 98 punched metal 99 binding mechanism 100 opening 101 helical groove

Claims (14)

[Claims] A cylinder having an open end; a displacer reciprocating in the cylinder along an axis thereof; an airtight connection to the one end of the cylinder; A cooling stage having an inner surface exposed, wherein the cooling stage includes a thin plate portion protruding from an outer surface thereof, and a portion of the cooling stage exposed to a space in the cylinder and the thin plate portion are integrally formed. A cooling stage coupled to a cooling cavity defined by the cylinder, displacer, and cooling stage, for introducing refrigerant gas into the cooling cavity, and for recovering the refrigerant gas from the cooling cavity. A regenerator having a path and a regenerator material that is disposed in the refrigerant gas flow path and exchanges heat with the refrigerant gas flowing in the refrigerant gas flow path. 2. The regenerator according to claim 1, wherein the thickness of the thin plate portion is 3 mm or less. 3. The regenerator according to claim 1, wherein the thin plate portion includes a plurality of fins. A first heating unit having an internal cavity and thermally coupled to the cooling stage; and a first heating unit synchronized with a cycle of introducing and recovering the refrigerant gas into the cooling cavity. A first regeneration gas passage for introducing and recovering the refrigerant gas into the internal cavity of the first heating unit; and a first on-off valve provided in the first regeneration gas passage. A regenerator according to any one of claims 1 to 3. 5. A second panel having an internal cavity and thermally coupled to said cooling panel.
And a second regeneration unit for introducing and recovering the refrigerant gas into the internal cavity of the second heating unit in synchronization with the cycle of introducing and recovering the refrigerant gas into the cooling cavity. The regenerator according to any one of claims 1 to 4, further comprising: a gas flow path; and a second on-off valve provided in the second regeneration gas flow path. 6. An auxiliary gas flow path connecting both ends of the outer peripheral surface is formed on the outer peripheral surface of the displacer, and at least a part thereof is formed in a direction intersecting the axial direction of the displacer. The regenerator according to any one of claims 1 to 5, further comprising a groove pattern including grooves along the groove. 7. A cylinder having an open end, a displacer reciprocating in the cylinder along an axis thereof, and a hermetically coupled to the one end of the cylinder, and a space in the cylinder. A cooling stage having an inner surface exposed, a refrigerant gas flow communicating with a cooling cavity defined by the cylinder, the displacer, and the cooling stage, introducing a refrigerant gas into the cooling cavity, and recovering the refrigerant gas from the cooling cavity. A passage, a regenerator material disposed in the refrigerant gas flow path and performing heat exchange with the refrigerant gas flowing in the refrigerant gas flow path, a material attached to the cooling stage and having a lower thermal conductivity than the cooling stage And a cooling panel attached to the heat resistance member and arranged so as not to contact the cooling stage and to surround the periphery of the cooling stage. Regenerator refrigerator. 8. A cylinder having one open end, a displacer reciprocating in the cylinder along an axis thereof, and a hermetically coupled to the one end of the cylinder, and a space in the cylinder. A cooling stage having an inner surface exposed, a refrigerant gas flow communicating with a cooling cavity defined by the cylinder, the displacer, and the cooling stage, introducing a refrigerant gas into the cooling cavity, and recovering the refrigerant gas from the cooling cavity. A path, a regenerator material disposed in the refrigerant gas flow path and performing heat exchange with refrigerant gas flowing through the refrigerant gas flow path, and thermally coupled to an intermediate position between both ends of the cylinder; And a cooling panel disposed so as to surround the periphery of the regenerator. 9. A first heating unit having an internal cavity and thermally coupled to the cooling stage, wherein the first heating unit is configured to synchronize with a cycle of introducing and recovering the refrigerant gas into the cooling cavity. A first regeneration gas passage for introducing and recovering the refrigerant gas into the internal cavity of the first heating unit; and a first on-off valve provided in the first regeneration gas passage. A regenerator according to claim 7. 10. A second panel having an internal cavity and thermally coupled to said cooling panel.
And a second regeneration unit for introducing and recovering the refrigerant gas into the internal cavity of the second heating unit in synchronization with the cycle of introducing and recovering the refrigerant gas into the cooling cavity. The regenerator according to any one of claims 7 to 9, further comprising: a gas flow path; and a second on-off valve provided in the second regeneration gas flow path. 11. An auxiliary gas flow path is formed on an outer peripheral surface of the displacer so as to connect both ends of the outer peripheral surface, and at least a part thereof is formed in a direction intersecting an axial direction of the displacer. The regenerator-type refrigerator according to any one of claims 7 to 10, having a groove pattern including a groove along the groove. 12. A step of disposing a metal cooling stage of a regenerative refrigerator in a cavity communicating with a vacuum chamber to be evacuated, activating the regenerator, and setting the cooling stage to helium. A vacuum evacuation method comprising: a step of cooling to a temperature equal to or lower than a boiling point; and a step of condensing gas in the vacuum chamber directly on the surface of the cooling stage. 13. The cooling stage is further heated to a temperature at which H ₂ gas condensed on the surface of the cooling stage is released and Ar gas remains condensed. 13. The vacuum evacuation method according to claim 12, further comprising the step of discharging gas condensed on the surface. 14. The regenerator-type refrigerator according to claim 1, wherein
13. The regenerative refrigerator according to any one of claims 1 to 12.
Or the evacuation method according to item 13.