JP2010043762A - Pulse tube refrigerating machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a refrigerating machine having high cooling performance and stable quality by securely preventing entry of molten solder to a cooling storage medium and a high temperature side heat exchanger, enabling easy determination of treatment conditions of brazing and reducing heat inflow to a cooling storage device, during brazing of the pulse tube refrigerating machine. <P>SOLUTION: After one end of a cooling storage tube and the high temperature side heat exchanger are jointed to each other by perimeter welding, brazing of a radiator and the cooling storage device and high temperature side heat exchanger is performed. Since the cooling storage medium is arranged outside the radiator, heat inflow from the radiator to the cooling storage device is reduced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pulse tube refrigerator, and more particularly to a pulse tube refrigerator in which a heat exchanger and a regenerator are brazed to a radiator.

A pulse tube refrigerator or the like is well known as a small cryogenic refrigerator that generates an extremely low temperature such as liquid nitrogen temperature.
FIG. 13 is a block diagram of a conventional return type pulse tube refrigerator. The pulse tube refrigerator is composed of a compressor 710, a radiator 720, a regenerator 740, a cold head 750, a pulse tube 760, and a phase control mechanism 770, and the principle of generating the refrigeration action is understood as follows. Yes.

  The working gas (for example, helium gas) sealed in the refrigerator is repeatedly compressed and expanded by a compressor 710 that reciprocates at a predetermined frequency. First, the working gas that has generated compression heat by the compression process of the compressor 710 releases the compression heat to the outside through the high-temperature side heat exchanger 730 by the radiator 720 (adiabatic compression process). The compressed working gas flows into the pulse tube 760 through the regenerator 540 and the cold head 750 (isothermal stroke). In the pulse tube 760, the working gas expands to generate cold (adiabatic expansion process). At this time, the phase between the pressure of the working gas and the flow velocity is adjusted by the phase control mechanism 770. The phase control mechanism 770 includes an inertance tube 771 and a buffer tank 772, and the working gas flows therethrough with a substantially sinusoidal pressure amplitude. In an electric circuit, inertance tube 771 corresponds to an impedance component of inductance and resistance, and buffer tank 772 corresponds to a capacitance component. Heat is absorbed from the cold head 750 by the cold generated as described above. Next, in the expansion process of the compressor 710, the working gas cooled by the pulse tube 760 returns to the compressor 710 through the radiator 720 while performing quasi-static heat exchange with the regenerator 740 (isothermal). Process). By repeating the above four steps, the cold head 750 is cooled to a very low temperature.

  The high temperature side heat exchanger 730 has a cylindrical shape and is provided with a large number of through holes in the axial direction as a flow path for the working gas. The material is mainly copper having high thermal conductivity. The regenerator 740 is configured by loading a regenerator material 742 made of a metal mesh or fine metal balls into a regenerator tube 741 made of a thin-walled pipe. Since the regenerator tube 741 is intended to increase the thermal resistance to the cold head 750, stainless steel having a low thermal conductivity is mainly used as a material.

  For joining the radiator 720, the regenerator 740, the cold head 750, and the pulse tube 760, brazing is often used from the viewpoint of joining different materials, reducing thermal resistance, and ensuring airtightness of the working gas. In FIG. 13 and FIG. 14, a portion indicated by a thick line is a portion joined by brazing. Since there is a part using copper as a material for brazing, vacuum atmosphere brazing is used for the purpose of preventing oxidation.

In particular, for the bonding at the contact interface between the high temperature side heat exchanger 730 and the radiator 720, it is important to reduce the thermal resistance, ensure the bonding strength, and ensure the airtightness of the working gas.
FIG. 14 is an enlarged view of a portion B shown in FIG. FIG. 15 is an enlarged view of a portion B shown in FIG. 13 before brazing.
As shown in FIG. 15, the radiator 720 includes a groove 721 for installing a wire-like brazing material 722, and a brazing groove 723 near the boundary between the regenerator 740 and the high temperature side heat exchanger 730. , Is formed. The brazing groove 723 allows the brazing material to enter the working gas flow paths of the regenerator 740 and the high temperature side heat exchanger 730 when the brazing material melted in the vacuum furnace flows out to the boundary surface by capillary action. It is provided to prevent this. Therefore, when an appropriate brazing process is performed, the thick line portions in FIG. 14 are joined by brazing.

Patent Document 1 discloses a method for joining heat exchangers in this type of refrigerator.
JP 2002-257428 A

In general, in order to perform appropriate brazing, it is necessary to adjust many conditions such as a set temperature of a vacuum furnace and a heating time. This optimum condition is determined by multiple parameters such as the heat capacity, thermal conductivity, emissivity of the brazing parts and jigs installed in the furnace, and the position and number of placement in the furnace. Determined by trial and error through experiments and the like.
In the structure as shown in FIG. 14, when the set temperature is low and the heating time is short, the molten brazing does not sufficiently flow into the contact interface between the high temperature side heat exchanger 730 and the regenerator tube 741 and the radiator 720, which is caused by brazing. Functions such as bonding strength, reduction in thermal resistance, and sealing of working gas cannot be exhibited.

On the other hand, when the set temperature is high and the heating time is long, as shown in FIG. 16, the molten wax does not stop at the wax accumulation groove 723 and enters the cold storage material 742 and the through hole of the high temperature side heat exchanger 730, It will block the road. When the working gas flow path becomes narrow in this way, the performance as a refrigerator is significantly reduced.
However, in carrying out brazing having a complicated structure as shown in FIG. 14, it is very possible to obtain stable brazing quality even if various conditions for brazing are searched and determined by a plurality of trial experiments or the like. Therefore, brazing defects are likely to occur. Further, in order to confirm the brazing quality after the brazing is completed, it is necessary to observe the internal state, but a special apparatus capable of inspecting the inside in a non-destructive manner such as an X-ray inspection apparatus is required.

Furthermore, as shown in FIG. 13, since a part of the regenerator 740 is located inside the radiator 720, the heat of the radiator 720 easily flows into the regenerator 740, resulting in a decrease in cooling efficiency.
Therefore, in view of the above problems, the present invention has a structure that reliably prevents molten solder from entering the cold storage material 742 and the high temperature side heat exchanger 730 during brazing, and the contact between the high temperature side heat exchanger 730 and the radiator 720. The purpose is to realize a refrigerator with high cooling performance and stable quality by reducing thermal resistance at the interface, making it possible to easily determine the brazing processing conditions, and reducing heat inflow to the regenerator. To do.

  In order to solve the above-mentioned problem, the invention according to claim 1 is composed of a compressor, a radiator having a high temperature side heat exchanger, a regenerator in which a regenerator is loaded with a regenerator, a cold head, a pulse tube, and a phase controller. In the pulse tube refrigerator, the high-temperature side heat exchanger and the regenerator tube are formed in a cylindrical shape with the same outer diameter, and the end face of the high-temperature side heat exchanger and the end face of the regenerator are butt-matched , The boundary is joined as a whole by welding all around, and the high-temperature side heat exchanger and the regenerator are integrally formed in the hole of the radiator formed equal to the outer diameter of the high-temperature side heat exchanger and the regenerator tube And is joined by brazing.

  The invention according to claim 2 is a pulse tube refrigerator constituted by a compressor, a radiator having a high-temperature side heat exchanger, a regenerator in which a regenerator is loaded with a regenerator, a cold head, a pulse tube, and a phase controller. The high temperature side heat exchanger has at least a first cylindrical portion equal to the outer diameter of the cylindrical regenerator tube and a second cylindrical portion equal to the inner diameter of the regenerator tube, The cylindrical part of 2 was inserted into the regenerator tube, and the boundary between the high temperature side heat exchanger and the regenerator tube was joined by all-around welding to form a single unit, which was formed equal to the outer diameter of the high temperature side heat exchanger and the regenerator tube A high-temperature side heat exchanger and a regenerator that are integrally formed are inserted into the holes of the radiator and joined by brazing.

  The invention according to claim 3 is the pulse tube refrigerator according to claim 2, wherein the high temperature side heat exchanger has an outer diameter between the first cylindrical portion and the second cylindrical portion than the second cylindrical portion. Has a small third cylindrical portion, the second and third cylindrical portions of the high temperature side heat exchanger are inserted into the regenerator tube, and a part of the regenerator tube located in the third cylindrical portion has a small outer diameter. The boundary between the high temperature side heat exchanger and the deformed portion of the regenerator tube is joined by all-around welding to form an integral body.

According to a fourth aspect of the present invention, in the pulse tube refrigerator of the second aspect, the high temperature side heat exchanger has a first cylindrical outer diameter between the first cylindrical portion and the second cylindrical portion. It has the 4th cylindrical part smaller than a part and larger than a 2nd cylindrical part, It is characterized by the above-mentioned.
According to a fifth aspect of the present invention, in the pulse tube refrigerator of the third aspect, the high temperature side heat exchanger has a first cylindrical outer diameter between the first cylindrical portion and the third cylindrical portion. It has the 5th cylindrical part smaller than a part and larger than a 2nd cylindrical part, It is characterized by the above-mentioned.

The invention according to claim 6 is the pulse tube refrigerator according to any one of claims 2 to 5, characterized in that the regenerator material of the regenerator is disposed outside the radiator.
The invention according to claim 7 is the pulse tube refrigerator according to any one of claims 1 to 6, wherein the pulse tube refrigerator is a coaxial pulse tube refrigerator, and the pulse tube is disposed at a central axis of a column of the high temperature side heat exchanger. A through-hole for inserting is provided.

  In the present invention, one end of the regenerator tube and the high-temperature side heat exchanger are joined together by welding all around, so that in the joining by brazing between the radiator, the regenerator and the high-temperature side heat exchanger, molten brazing is performed during brazing. Intrusion into cold storage materials or high-temperature heat exchangers can be reliably prevented. In addition, since the brazing groove can be eliminated, the thermal resistance at the contact interface between the high temperature side heat exchanger and the heat radiating body can be reduced. When determining the brazing processing conditions, it is possible to determine an appropriate brazing processing condition without performing a trial experiment because the structure is simple.

  In addition to the above, by disposing the regenerator material so as to be located outside the radiator, the heat inflow from the radiator to the regenerator is reduced, and the thermal resistance in the columnar axial direction of the regenerator is increased. As a result, the amount of heat flowing from the high temperature portion to the low temperature end is reduced, and the cooling efficiency is improved.

An embodiment of a pulse tube refrigerator according to the present invention will be described with reference to FIGS. The basic operation principle is the same as that of the prior art, and detailed description thereof is omitted.
FIG. 1 is a sectional view of a pulse tube refrigerator according to the first embodiment of the present invention. In addition, FIG. 1 is a figure at the time of applying to a U-shaped return type pulse tube refrigerator. FIG. 2 is an enlarged view of a portion A shown in FIG. FIG. 3 is an enlarged view of portion A shown in FIG. 1 before brazing.

The U-shaped return type pulse tube refrigerator includes a compressor 110, a radiator 120, a regenerator 140, a cold head 150, a pulse tube 160, and a phase control mechanism 170. The phase control mechanism 170 includes an inertance tube 171 and a buffer tank 172.
The high temperature side heat exchanger 130 has a cylindrical shape, and its outer diameter is formed to be equal to the outer diameter of the regenerator tube 141 of the regenerator. The end face of the high temperature side heat exchanger 130 and the end face of the regenerator 140 are abutted so that the outer diameters coincide with each other, and the boundary 136 is joined by all-around welding to constitute an integrated unit. For welding, it is desirable to employ a welding method such as laser beam welding or electron beam welding that generates less thermal distortion. Laser beam welding is performed in an inert gas atmosphere such as argon or helium. In addition, when the welding part 136 becomes larger than the outer diameter of the cool storage tube 141, it makes it smaller than the outer diameter of the cool storage tube 141 by cutting or grinding | polishing. If possible, it is better to conduct a helium leak test.

Brazing is used to join the radiator 120, the high temperature side heat exchanger 130, the regenerator 140, the cold head 150, and the pulse tube 160. In the figure, the part indicated by the bold line is the part joined by brazing.
The brazing of the radiator 120, the high temperature side heat exchanger 130, and the regenerator 140 will be described in detail. A hole equal to the outer diameter of the high temperature side heat exchanger 130 and the regenerator tube 141 is formed in the radiator 120. Furthermore, a groove 121 for installing a wire-like brazing material 122 is also formed. In addition, the wax accumulation groove is unnecessary.

A wire-shaped brazing material 122 is installed in the groove 121, an integrated unit of the high-temperature side heat exchanger 120 and the regenerator tube 140 is inserted into the hole of the radiator, and other components are assembled. Join by attaching. The processing conditions in the furnace are that the heating time is longer and the heating temperature is higher.
By adopting this configuration, the brazing heating time can be made sufficiently long and the heating temperature can be made sufficiently high, so that the molten brazing sufficiently flows into the contact interface, resulting in high bonding strength and low thermal resistance. It is possible to realize a bonding that is small and does not leak working gas. Further, since the welded part 136 is welded all around, the boundary surface between the regenerator tube 141 and the high temperature side heat exchanger 130 is completely sealed, and the molten solder penetrates the regenerator material 142 and the high temperature side heat exchanger. It does not reach the hole and does not block the working gas flow path. Furthermore, since the wax retaining groove is not required, the contact interface between the high temperature side heat exchanger 130 and the radiator 120 is increased, so that the thermal resistance at the contact interface is reduced.

FIG. 4 is an enlarged view of a portion A shown in FIG. 1 of the pulse tube refrigerator according to the second embodiment of the present invention. FIG. 5 is a diagram showing the shape of the high temperature side heat exchanger 230. The through hole is omitted.
The difference between the first embodiment and the second embodiment is only the shape of the high-temperature side heat exchanger and the positioning method of the high-temperature side heat exchanger and the regenerator tube, and the other partial explanations are omitted.

The high temperature side heat exchanger 230 has a first cylindrical portion 231 equal to the outer diameter of the regenerator tube 141 and a second cylindrical portion 232 equal to the inner diameter of the regenerator tube. The second cylindrical portion 232 of the high temperature side heat exchanger is inserted into the regenerator tube 141, and the boundary portion 136 between the first cylindrical portion 231 of the high temperature side heat exchanger and the regenerator tube 141 is joined by welding all around. It is configured as a unit.
For welding, it is desirable to employ laser beam welding, electron beam welding, or the like, as described above. Moreover, when the welding part 136 becomes larger than the outer diameter of the cool storage pipe 141, it makes it smaller than the outer diameter of the cool storage pipe 141 by cutting or grinding | polishing.

With the above configuration, positioning during welding of the high temperature side heat exchanger 230 and the regenerator 140 is facilitated, and the cold storage tube 141 is inserted into the high temperature side heat exchanger 230 so that the welding joint 136 is moment-weighted. Become stronger against.
Furthermore, when the integrated unit of the regenerator 140 and the high temperature side heat exchanger 230 is inserted into the radiator 120 and brazed and joined, the second cylindrical portion so that the regenerator material 142 is located outside the radiator 120. The axial length of 232 may be determined. With such a configuration, the heat inflow from the radiator 120 to the regenerator material 142 is reduced, so that the thermal resistance in the columnar axial direction of the regenerator is increased and the inflow heat amount from the high temperature part to the low temperature end is reduced, and the cooling efficiency is improved. improves.

FIG. 6 is an enlarged view of a portion A shown in FIG. 1 of the pulse tube refrigerator according to the third embodiment of the present invention. FIG. 7 is a diagram showing the shape of the high temperature side heat exchanger 330. The through hole is omitted.
The difference between the first embodiment and the third embodiment is only the shape of the high-temperature side heat exchanger and the positioning method of the high-temperature side heat exchanger and the regenerator tube, and the other partial explanations are omitted.

  The high temperature side heat exchanger 330 includes a first cylindrical portion 331 equal to the outer diameter of the regenerator tube 141, a second cylindrical portion 332 equal to the inner diameter of the regenerator tube, the first cylindrical portion 331, and the second cylindrical portion. And a third cylindrical portion 333 having an outer diameter smaller than that of the second cylindrical portion. The second cylindrical portion 332 and the third cylindrical portion 333 of the high temperature side heat exchanger are inserted into the regenerator tube 141, and a part of the regenerator tube 141 located in the third cylindrical portion is deformed so that the outer diameter becomes small. The boundary portion 136 between the first cylindrical portion 231 and the cold storage tube 141 of the high temperature side heat exchanger is joined by all-around welding to constitute an integrated unit.

For welding, it is desirable to employ laser beam welding, electron beam welding, or the like, as described above. Since the welded portion 136 corresponds to a portion where the outer diameter of the regenerator tube 141 is reduced, an integrated unit of the high temperature side heat exchanger 330 and the regenerator 140 is inserted into the radiator 120 without cutting or polishing. it can.
FIG. 8 is an enlarged view of a portion A shown in FIG. 1 of a pulse tube refrigerator according to the fourth embodiment of the present invention. FIG. 9 is a diagram showing the shape of the high temperature side heat exchanger 430. The through hole is omitted.

The difference between the first embodiment and the fourth embodiment is only the shape of the high-temperature side heat exchanger and the positioning method of the high-temperature side heat exchanger and the regenerator tube, and the description of the other parts is omitted. To do.
The high temperature side heat exchanger 430 includes a first cylindrical portion 431 equal to the outer diameter of the regenerator tube 141, a second cylindrical portion 432 equal to the inner diameter of the regenerator tube, the first cylindrical portion 431, and the second cylindrical portion. And a fourth cylindrical portion 434 having an outer diameter smaller than that of the first cylindrical portion and larger than that of the second cylindrical portion. The second cylindrical portion 432 of the high temperature side heat exchanger is inserted into the regenerator tube 141, and the boundary portion 136 between the fourth cylindrical portion 434 of the high temperature side heat exchanger and the regenerator tube 141 is joined by welding all around. It is configured as a unit.

For welding, it is desirable to employ laser beam welding, electron beam welding, or the like, as described above. Since the welded portion 136 corresponds to a portion where the outer diameter of the fourth cylindrical portion 434 is reduced, the radiator 120 is integrated with the high-temperature side heat exchanger 430 and the regenerator 140 without cutting or polishing. Unit can be inserted.
FIG. 10 is an enlarged view of a portion A shown in FIG. 1 of the pulse tube refrigerator according to the fifth embodiment of the present invention. FIG. 11 is a diagram showing the shape of the high temperature side heat exchanger 530. The through hole is omitted.

The difference between the first embodiment and the fourth embodiment is only the shape of the high-temperature side heat exchanger and the positioning method of the high-temperature side heat exchanger and the regenerator tube, and the description of the other parts is omitted. To do.
The high temperature side heat exchanger 530 includes a first columnar portion 531 equal to the outer diameter of the regenerator tube 141, a second columnar portion 532 equal to the inner diameter of the regenerator tube, a first columnar portion 331, and a second columnar portion. Between the first columnar portion 531 and the third columnar portion 533, and between the first columnar portion 531 and the third columnar portion 533. And a fifth cylindrical portion 535 having an outer diameter smaller than that of the first cylindrical portion and larger than that of the second cylindrical portion. The second cylindrical portion 532 and the third cylindrical portion 533 of the high temperature side heat exchanger are inserted into the regenerator tube 141, and a part of the regenerator tube 141 located in the third cylindrical portion is deformed so that the outer diameter becomes small. The boundary part 136 between the fifth cylindrical part 535 of the high temperature side heat exchanger and the regenerator tube 141 is joined by all-around welding to constitute an integrated unit.

For welding, it is desirable to employ laser beam welding, electron beam welding, or the like, as described above. Since the welded portion 136 corresponds to a portion where the outer diameter of the fourth cylindrical portion 535 is reduced, the radiator 120 is integrated with the high-temperature side heat exchanger 530 and the regenerator 140 without cutting or polishing. Unit can be inserted.
FIG. 12 is a sectional view of a coaxial return type pulse tube refrigerator according to the sixth embodiment of the present invention.

Although the arrangement of the regenerator and the pulse tube is different between the U-shaped return type pulse tube refrigerator and the coaxial return type pulse tube refrigerator, the basic operation principle is the same. Moreover, since the difference in the part regarding this invention is a shape of a heat exchanger, description of another part is abbreviate | omitted.
The difference between the heat exchanger 630 of the coaxial return type pulse tube refrigerator and the heat exchanger of the U-shaped return type pulse tube refrigerator is only the presence or absence of a hole into which the pulse tube 160 is inserted, and other parts are common. It is.

  Therefore, in FIG. 12, although the through hole for pulse tubes is formed in the shape of the heat exchanger corresponding to the said 2nd Embodiment, it is not limited to this shape. Even if any heat exchanger in which a through hole for a pulse tube is formed in the shape of the heat exchanger corresponding to the first to fifth embodiments is adopted for a heat exchanger of a coaxial return type pulse tube refrigerator, The same effect as that of the U-shaped return type pulse tube refrigerator can be obtained.

  In addition, the heat radiator, the regenerator, and the heat exchanger in the series type pulse tube refrigerator can have the same structure as the U-shaped return type pulse tube refrigerator. Therefore, by applying the present invention to the series-type pulse tube refrigerator, the same effect as that of the U-shaped return-type pulse tube refrigerator can be obtained.

It is sectional drawing of the pulse tube refrigerator which concerns on the 1st Embodiment of this invention. It is the A section enlarged view concerning a 1st embodiment of the present invention. It is the A section enlarged view before brazing in FIG. It is the A section enlarged view concerning a 2nd embodiment of the present invention. It is the figure which described the shape of the high temperature side heat exchanger which concerns on the 2nd Embodiment of this invention. It is the A section enlarged view concerning a 3rd embodiment of the present invention. It is the figure which described the shape of the high temperature side heat exchanger which concerns on the 3rd Embodiment of this invention. It is the A section enlarged view concerning a 4th embodiment of the present invention. It is the figure which described the shape of the high temperature side heat exchanger which concerns on the 4th Embodiment of this invention. It is the A section enlarged view concerning a 5th embodiment of the present invention. It is the figure which described the shape of the high temperature side heat exchanger which concerns on the 5th Embodiment of this invention. It is sectional drawing of the pulse tube refrigerator which concerns on the 6th Embodiment of this invention. It is sectional drawing of the pulse tube refrigerator of a prior art. It is the B section enlarged view of the pulse tube refrigerator of a prior art. It is the B section enlarged view before brazing in FIG. It is a figure which shows a state when the brazing defect generate | occur | produces in a prior art.

Explanation of symbols

110,710 Compressor 120,720 Radiator 130,230,330,430,530,630,730 Heat exchanger 140,740 Cold storage 150,750 Cold head 160,760 Pulse tube 170,770 Phase control mechanism

Claims (7)

In a pulse tube refrigerator composed of a compressor, a radiator having a high temperature side heat exchanger, a regenerator loaded with a regenerator material in a regenerator tube, a cold head, a pulse tube, and a phase control unit,
The high temperature side heat exchanger and the regenerator tube are formed in a cylindrical shape with the same outer diameter,
The end face of the high-temperature side heat exchanger and the end face of the regenerator are abutted so that the outer diameters match, and the boundary is joined as a whole by welding all around,
The high-temperature side heat exchanger and the regenerator that are configured as a single piece are inserted into the holes of the radiator that is formed to be equal to the outer diameter of the high-temperature side heat exchanger and the regenerator tube, and joined by brazing,
A pulse tube refrigerator characterized by In a pulse tube refrigerator composed of a compressor, a radiator having a high temperature side heat exchanger, a regenerator loaded with a regenerator material in a regenerator tube, a cold head, a pulse tube, and a phase control unit,
The high temperature side heat exchanger has at least a first cylindrical portion equal to the outer diameter of the cylindrical regenerator tube, and a second cylindrical portion equal to the inner diameter of the regenerator tube,
Inserting the second cylindrical part of the high temperature side heat exchanger into the regenerator tube, joining the boundary between the high temperature side heat exchanger and the regenerator tube by welding all around, and configuring as one piece,
The high-temperature side heat exchanger and the regenerator that are configured as a single piece are inserted into the holes of the radiator that is formed to be equal to the outer diameter of the high-temperature side heat exchanger and the regenerator tube, and joined by brazing,
A pulse tube refrigerator characterized by The high temperature side heat exchanger has a third cylindrical part having an outer diameter smaller than that of the second cylindrical part between the first cylindrical part and the second cylindrical part,
The second and third cylindrical portions of the high temperature side heat exchanger are inserted into the regenerator tube, and a part of the regenerator tube located in the third column portion is deformed so that the outer diameter becomes small, and the high temperature side heat exchanger And the boundary between the cold storage tube and the deformed part of the regenerator is joined together by welding all around,
The pulse tube refrigerator according to claim 2. The high temperature side heat exchanger has a fourth cylindrical portion having an outer diameter smaller than the first cylindrical portion and larger than the second cylindrical portion between the first cylindrical portion and the second cylindrical portion,
The pulse tube refrigerator according to claim 2. The high temperature side heat exchanger has a fifth cylindrical portion between the first cylindrical portion and the third cylindrical portion, the outer diameter of the fifth cylindrical portion being smaller than the first cylindrical portion and larger than the second cylindrical portion;
The pulse tube refrigerator according to claim 3. Arranging the regenerator material of the regenerator outside the radiator,
The pulse tube refrigerator according to any one of claims 2 to 5, wherein:   The coaxial pulse tube refrigerator is provided with a through hole for inserting a pulse tube in a central axis of a cylinder of a high temperature side heat exchanger. The pulse tube refrigerator as described.