Pre-cooling device and whole pulse tube refrigerator

Abstract

The invention relates to the technical field of profound hypothermia, and provides a pre-cooling device and a pulse tube refrigerator complete machine, the pre-cooling device comprises a first cooling module used for cooling a compressor, the first cooling module comprises a first support base and a plurality of cooling blocks, the plurality of cooling blocks wrap the periphery of the compressor, and liquid nitrogen is stored in the cooling blocks; the first supporting base is arranged at the bottom of the cold block and used for fixing the cold block and insulating the cold block and the vacuum box. The second cooling module is used for cooling the hot end flange and the phase modulation mechanism, the second cooling module comprises a liquid nitrogen tank and a second supporting base, the liquid nitrogen tank is used for cooling the hot end flange and the phase modulation mechanism, and the second supporting base is used for insulating heat of the liquid nitrogen tank and the vacuum box. The whole pulse tube refrigerator can be pre-cooled to a liquid nitrogen temperature zone, and the laser displacement sensor can monitor the running state of the compressor.

Description

Technical Field

[0001] The present invention relates to the field of deep cryogenic technology, and in particular to a precooling device and a pulse tube refrigerator. Background Art

[0002] High-frequency pulse tube refrigerators have no moving parts at the low-temperature end, and can maintain low vibration, low interference, no wear, and long service life. These significant advantages make high-frequency pulse tube refrigerators an ideal choice for space refrigerators in recent years, and are widely used in remote sensing detection, space science and other fields. With the rapid development of space exploration, high-frequency pulse tube refrigerators and their main driving source linear compressors need to face a more severe space environment, and the reduction of space heat dissipation temperature also puts a test on the operating stability of linear compressors.

[0003] At present, there are few studies on high-frequency pulse tube refrigerators at low-temperature heat dissipation temperatures. With the rapid development of high-temperature superconducting materials, the superconducting transition temperature of some high-temperature superconducting materials is already higher than the liquid nitrogen temperature zone. Applying superconducting materials to linear compressors to achieve stable operation of motors in a superconducting state and reduce the input power of compressors is a major research hotspot for high-frequency pulse tube refrigerators. Therefore, it is very necessary to study high-frequency pulse tube refrigerators that operate directly in the liquid nitrogen temperature zone to improve the efficiency of refrigerators.

[0004] In the prior art, the compressor, hot end flange and phase adjustment mechanism of the pulse tube refrigerator are immersed in liquid nitrogen. However, the piston displacement parameter monitoring of the compressor requires a laser displacement sensor, which needs to be placed on both sides of the compressor. The emitted laser passes through the glass window of the container storing liquid nitrogen, through the liquid nitrogen, through the glass windows on both sides of the compressor, and reaches the piston to measure the displacement of the piston. However, the compressor releases heat during operation, so the liquid nitrogen may boil when cooling the compressor. At the same time, the refractive index of the laser in the glass and the liquid nitrogen is not the same, which will cause the laser displacement sensor to have a large error in measurement. Therefore, the liquid nitrogen immersion method cannot monitor the piston displacement and other data of the compressor. Summary of the invention

[0005] The present invention provides a precooling device and a pulse tube refrigerator, which are used to solve the defect that the displacement and other parameters of the compressor cannot be monitored by the liquid nitrogen immersion method for precooling in the prior art, and achieve close contact with the pulse tube refrigerator to achieve a good precooling effect, ensuring that the refrigerator operates in the liquid nitrogen temperature range. Moreover, since the laser displacement sensor is not directly immersed in the liquid nitrogen, it can monitor the displacement parameters of the compressor.

[0006] The present invention provides a precooling device for cooling a pulse tube refrigerator. The precooling device is arranged in a vacuum box and comprises: A first cooling module, used for cooling the compressor, comprising a first support base and a plurality of cold blocks, wherein the plurality of cold blocks are coated on the periphery of the compressor, and liquid nitrogen is stored inside the cold blocks; the first support base is arranged at the bottom of the cold blocks, and the first support base is used for fixing the cold blocks and insulating the cold blocks and the vacuum box; A second cooling module, used for cooling the hot end flange and the phase adjustment mechanism, the second cooling module comprises a liquid nitrogen tank and a second support base, the liquid nitrogen tank is used for cooling the hot end flange and the phase adjustment mechanism, and the second support base is used for thermally insulating the liquid nitrogen tank and the vacuum box; A liquid nitrogen delivery pipe, one end of which is connected to the liquid nitrogen Dewar, and the other end of which penetrates the side wall of the vacuum box and is respectively connected to the cold block and the liquid nitrogen tank.

[0007] According to a precooling device provided by the present invention, the liquid nitrogen delivery pipe comprises a metal hose, a liquid nitrogen sleeve and a plurality of bellows, the liquid nitrogen sleeve comprises an inner tube and an outer tube, the liquid nitrogen Dewar is connected to the adapter through the metal hose and enters the inner tube, the inner tube and the outer tube are both welded to the adapter flange, and the outer tube is fixed to the vacuum box; the inner tube is sleeved inside the outer tube; the inner tube has a plurality of outlets, and each of the outlets is correspondingly connected to a bellows, and the bellows are correspondingly connected to the liquid nitrogen inlets of the first cooling module and the second cooling module.

[0008] According to a precooling device provided by the present invention, the liquid nitrogen sleeve and the metal hose are sealed by a ball head; the bellows and the liquid nitrogen sleeve, the bellows and the first cooling module, and the bellows and the second cooling module are all sealed by a ball head; the adapter flange and the vacuum box, and the outer tube and the vacuum box are all sealed by a sealing ring.

[0009] According to a pre-cooling device provided by the present invention, the second cooling module further includes a cold screen, the cold screen is arranged on the inner side of the second supporting base, and the cold screen is fixed on the hot end flange.

[0010] According to a precooling device provided by the present invention, the cold blocks include four, and the cold blocks are in pairs, and a receiving hole corresponding to the compressor is provided on the opposite side of each pair of the cold blocks.

[0011] According to a precooling device provided by the present invention, the first supporting base comprises: A pair of support plates, respectively disposed on two sides of the bottom of the cold block; A heat insulation board is arranged at the bottom of the support board, and the heat insulation board is used to insulate the cold block and the vacuum box.

[0012] According to a precooling device provided by the present invention, the heat insulation plate is a polytetrafluoroethylene plate.

[0013] According to a precooling device provided by the present invention, the phase adjustment mechanism includes a gas reservoir and an inertia tube, and the side of the liquid nitrogen tank is provided with an open groove with rounded corners, the open groove is for the inertia tube to pass through, and the inertia tube is coiled around the outer periphery of the liquid nitrogen tank and connected to the gas reservoir.

[0014] According to a precooling device provided by the present invention, the gas reservoir is a waist-shaped hole gas reservoir, which is fixed on the top of the liquid nitrogen tank, and the gas reservoir is in contact with the liquid nitrogen tank through a pre-tightening force.

[0015] The precooling device provided by the present invention is used for cooling a pulse tube refrigerator. The first cooling module includes a first supporting base and a plurality of cold blocks. The plurality of cold blocks are coated on the outer periphery of the compressor, and liquid nitrogen is stored in the cold blocks. The first supporting base is arranged at the bottom of the cold blocks, and the first supporting base is used to fix the cold blocks and insulate the cold blocks and the vacuum box. The hot end flange and the phase adjustment mechanism are cooled by a liquid nitrogen tank, and the second supporting base insulates the liquid nitrogen tank and the vacuum box. The entire pulse tube refrigerator can be precooled to the liquid nitrogen temperature zone, and the laser displacement sensor can monitor the operating status of the compressor. In addition, the existence of the vacuum environment reduces the heat leakage of the pulse tube refrigerator.

[0016] Another aspect of the present invention provides a pulse tube refrigerator, which includes a pulse tube refrigerator body and the precooling device as described above. The pulse tube refrigerator body is cooled by the precooling device, and the operating status of the compressor can also be monitored. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic diagram of the structure of the precooling device provided in an embodiment of the present invention.

[0019] Figure 2 is a cross-sectional view of a first cooling module provided in an embodiment of the present invention.

[0020] Figure 3 is a cross-sectional view of a second cooling module provided in an embodiment of the present invention.

[0021] Figure 4 It is a cross-sectional view of a liquid nitrogen delivery pipe provided in an embodiment of the present invention.

[0022] Figure 5 It is a structural schematic diagram of the precooling device provided in an embodiment of the present invention from another angle.

[0023] Reference numerals: 1. First cooling module; 11. First supporting base; 12. Cold block; 2. Second cooling module; 21. Liquid nitrogen tank; 22. Second supporting base; 23. Cold screen; 3. Vacuum box; 4. Liquid nitrogen delivery pipe; 41. Inner pipe; 42. Outer pipe; 5. Hot end flange; 6. Gas reservoir; 7. Opening slot. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0026] Combine the following Figure 1-Figure 5 A precooling device of the present invention is described.

[0027] See also Figure 1 As shown, the precooling device provided in the embodiment of the present invention is used to cool the pulse tube refrigerator. The precooling device is arranged in a vacuum box 3 and includes a first cooling module 1 and a second cooling module 2.

[0028] Among them, see Figure 2As shown, the first cooling module 1 is used to cool the compressor. The first cooling module 1 includes a first support base 11 and a plurality of cold blocks 12. The plurality of cold blocks 12 are coated on the periphery of the compressor so that the plurality of cold blocks 12 can fix the compressor from the side. Screws can be screwed to ensure that the cold block 12 is in close contact with the compressor. Liquid nitrogen is stored inside the cold block 12. Liquid nitrogen is used as a cooling medium. The extremely low temperature of the liquid nitrogen can quickly cool the compressor. The first support base 11 is arranged at the bottom of the cold block 12, and the first support base 11 is used to support and fix the cold block 12 on the one hand to prevent the cold block 12 from sliding, and on the other hand to insulate the cold block 12 and the vacuum box 3 to reduce heat leakage.

[0029] In order to improve the cooling system, the cold block 12 may be a hollow device supported by copper material.

[0030] like Figure 3 As shown, the second cooling module 2 is used to cool the hot end flange 5 and the phase adjustment mechanism. The second cooling module 2 includes a liquid nitrogen tank 21 and a second support base 22. The liquid nitrogen tank 21 is used to cool the hot end flange 5 and the phase adjustment mechanism. The hot end flange 5 and the phase adjustment mechanism are often prone to heat accumulation in the pulse tube refrigerator. The temperature of these components can be significantly reduced by direct cooling of liquid nitrogen. The second support base 22 is used to insulate the liquid nitrogen tank 21 and the vacuum box 3.

[0031] The first support base 11 and the second support base 22 not only provide stable support for the cold block 12 and the liquid nitrogen tank 21, but also play a role in heat insulation. Through effective heat insulation design, the low temperature of the cold block 12 and the liquid nitrogen tank 21 can be prevented from causing adverse effects on the components inside the vacuum box 3, while avoiding the interference of external heat on the cooling module, ensuring the stability and durability of the cooling effect.

[0032] The precooling device provided by the present invention, through the above structural setting, stores liquid nitrogen through a hollow device of copper material, and the precooling device is in close contact with the cooling pulse tube refrigerator, which can achieve a good precooling effect and ensure that the refrigerator operates in the liquid nitrogen temperature zone. On the one hand, the laser displacement sensor that measures the displacement parameters of the compressor can reach the compressor piston for monitoring without passing through liquid nitrogen; on the other hand, the entire precooling device is placed in a vacuum box 3, and liquid nitrogen is introduced into the precooling device. The final operating ambient temperature of the refrigerator is around 80K, and the existence of the vacuum environment makes the pulse tube refrigerator less heat leaking.

[0033] See again, Figure 2 and Figure 3As shown, in a feasible embodiment of the present invention, in order to pass liquid nitrogen from the Dewar to the liquid nitrogen tank 21 and the cold block 12, a liquid nitrogen delivery pipe 4 is also included, one end of the liquid nitrogen delivery pipe 4 is connected to the liquid nitrogen Dewar, and the other end of the liquid nitrogen delivery pipe 4 passes through the side wall of the vacuum box 3 and is connected to the cold block 12 and the liquid nitrogen tank 21 respectively. An inserted male and female joint can be used, and a sealing device in the form of a clamp lock or a flange lock can be provided to ensure the stability and sealing of the connection. The liquid nitrogen delivery pipe 4 adopts a high vacuum insulation design, which can effectively reduce the heat loss of liquid nitrogen during the transmission process and improve the transmission efficiency.

[0034] In a feasible embodiment of the present invention, the cold blocks 12 include four cold blocks 12, and the cold blocks 12 are paired in pairs, which not only improves the cooling effect, but also ensures the stability and reliability of the system. The opposite side of each pair of cold blocks 12 is provided with a receiving hole corresponding to the compressor, and the cold blocks 12 can fit the compressor tightly, so as to perform heat exchange more effectively. The cold blocks 12 quickly transfer the heat generated by the compressor through their good thermal conductivity, thereby ensuring the normal operation of the compressor.

[0035] In a feasible embodiment of the present invention, the first support base 11 includes a pair of support plates and a heat insulation plate (not shown in the figure), the pair of support plates are respectively arranged on both sides of the bottom of the cold block 12, and the pair of support plates fix the four cold blocks 12 to prevent left and right sliding. The heat insulation plate is arranged at the bottom of the support plate, and the heat insulation plate is used to insulate the cold block and the vacuum box.

[0036] Among them, the heat insulation board is a polytetrafluoroethylene board, which has an extremely low thermal conductivity. Therefore, the polytetrafluoroethylene board has excellent heat insulation performance, can effectively reduce heat transfer and improve cooling efficiency.

[0037] More specifically, the liquid nitrogen delivery pipe 4 includes a metal hose, a liquid nitrogen sleeve and a plurality of bellows (not shown in the figure). Figure 4 As shown, the liquid nitrogen sleeve includes an inner tube 41 and an outer tube 42. The liquid nitrogen dewar is connected to the adapter through a metal hose and enters the inner tube 41. The inner tube 41 and the outer tube 42 are welded to the adapter flange, and the outer tube 42 is fixed on the vacuum box 3; the inner tube 41 is sleeved inside the outer tube 42; the inner tube 41 passes through the inside of the outer tube 42 and does not contact the inside of the vacuum box 3, reducing the impact on the wall temperature of the vacuum box 3. When doing the vacuum pumping experiment, the air between the inner tube 41 and the outer tube 42 of the liquid nitrogen sleeve is evacuated together by reserving a gap. Among them, the length of the outer tube 42 should be longer to minimize the impact of liquid nitrogen passing through the outer tube 42 on the vacuum box 3.

[0038] Furthermore, the inner tube 41 has a plurality of outlets, and each outlet is connected to a corresponding bellows, and the bellows are connected to the liquid nitrogen inlet of the first cooling module 1 and the second cooling module 2. The liquid nitrogen sleeve is transported between the cold block 12 and the liquid nitrogen tank 21 through a bellows. Because liquid nitrogen needs to be passed to the cold block 12 and the liquid nitrogen tank 21 at the same time, two pipelines are separated at the outlet of the inner tube 41, one of which is directly connected to the liquid nitrogen inlet of the liquid nitrogen tank 21, and the other pipeline is connected to the liquid nitrogen inlet of the cold block 12. However, since the first cooling module 1 includes four cold blocks 12, it is necessary to connect this pipeline to the five-way through a bellows, convert it into four pipelines, and then connect the four pipelines to the liquid nitrogen inlets of the four cold blocks 12 respectively.

[0039] It should be noted that the discharge route of liquid nitrogen is also arranged in the same manner, and when the bellows pipeline is connected, the wall surface of the vacuum box 3 cannot be touched.

[0040] When conducting a test with liquid nitrogen, the test device must be isolated from the air during the process of cooling from room temperature to near the temperature of liquid nitrogen, otherwise the water vapor in the air will be frozen by the cold, so the vacuum seal design must be done when transporting liquid nitrogen. The sealing ring structure at room temperature loses its function at the temperature of liquid nitrogen. Therefore, in a feasible embodiment of the present invention, the liquid nitrogen sleeve is welded and sealed, and the liquid nitrogen sleeve and the metal hose are sealed by a ball head; the bellows and the liquid nitrogen sleeve, the bellows and the first cooling module 1, and the bellows and the second cooling module 2 are all sealed by a ball head; the adapter flange and the vacuum box 3, and the outer tube 42 and the vacuum box 3 are all sealed with a sealing ring.

[0041] See again Figure 3 As shown, in a feasible embodiment of the present invention, the second cooling module 2 further includes a cold shield 23, which is arranged on the inner side of the second supporting base 22 and contacts the hot end flange 5, and is used to reduce the radiation heat exchange of the cold finger.

[0042] See also Figure 5 As shown, in a feasible embodiment of the present invention, the phase adjustment mechanism includes a gas reservoir 6 and an inertia tube, and the side of the liquid nitrogen tank 21 is provided with an opening groove 7 with rounded corners, and the rounded corners are made at a certain angle so that the inertia tube can be safely coiled out (if the opening groove is a right angle, the inertia tube may be damaged when it is coiled). In order to facilitate sealing and later replacement of the inertia tube, the sections of the inertia tube are connected by welding, and the inertia tube is coiled around the outer periphery of the liquid nitrogen tank 21 and connected to the gas reservoir 6.

[0043] The gas reservoir 6 is fixed on the top of the liquid nitrogen tank 21 and is a waist-shaped hole gas reservoir. The purpose of this arrangement is that if the inertia tube is not tightly coiled after being coiled on the liquid nitrogen tank, the waist-shaped hole gas reservoir can be rotated to make the inertia tube as tight as possible, and then the gas reservoir can be fixed to the liquid nitrogen tank 21. In addition, the pre-tightening force of the screw makes the gas reservoir 6 fully contact with the liquid nitrogen tank 21, and the inertia tube can be slightly rotated when fixed to make it more closely attached to the wall of the liquid nitrogen tank 21.

[0044] The precooling device provided in the embodiment of the present invention can cool the compressor, the phase adjustment mechanism, and the hot end to about 80K after 1.5 hours by continuously introducing liquid nitrogen into the first cooling module 1 and the second cooling module 2. At the same time, the temperature can be kept relatively stable at around 80K during the test. Compared with the direct liquid nitrogen immersion method, the present invention can better evaluate the changes in various parameters of the compressor during the operation of the refrigerant, and provides conditions for designing and testing low-temperature compressor components.

[0045] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0046] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "mode", "specific mode", or "some modes" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or mode are included in at least one embodiment or mode of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or mode. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or modes in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or modes described in this specification and the features of the different embodiments or modes, without contradiction.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A precooling device for cooling a pulse tube refrigerator, the precooling device being arranged in a vacuum box, characterized in that: include: A first cooling module (1) is used to cool the compressor, the first cooling module (1) comprising a first support base (11) and a plurality of cold blocks (12), the plurality of cold blocks (12) being wrapped around the outer periphery of the compressor, and liquid nitrogen being stored inside the cold blocks (12); the first support base (11) is arranged at the bottom of the cold blocks (12), and the first support base (11) is used to fix the cold blocks (12) and to thermally insulate the cold blocks (12) and the vacuum box (3); The second cooling module (2) is used to cool the hot end flange (5) and the phase adjustment mechanism, the second cooling module (2) comprising a liquid nitrogen tank (21) and a second support base (22), the liquid nitrogen tank (21) being used to cool the hot end flange (5) and the phase adjustment mechanism, and the second support base (22) being used to thermally insulate the liquid nitrogen tank (21) and the vacuum box (3). A liquid nitrogen delivery pipe (4), one end of the liquid nitrogen delivery pipe (4) being connected to the liquid nitrogen dewar, and the other end of the liquid nitrogen delivery pipe (4) penetrating the side wall of the vacuum box (3) and being connected to the cold block (12) and the liquid nitrogen tank (21) respectively.

2. The precooling device according to claim 1, characterized in that: The liquid nitrogen delivery pipe (4) comprises a metal hose, a liquid nitrogen sleeve and a plurality of bellows; the liquid nitrogen sleeve comprises an inner tube (41) and an outer tube (42); the liquid nitrogen dewar is connected to an adapter through the metal hose and enters the inner tube (41); the inner tube (41) and the outer tube (42) are both welded to an adapter flange; the outer tube (42) is fixed to the vacuum box (3); the inner tube (41) is sleeved inside the outer tube (42); the inner tube (41) has a plurality of outlets, and each of the outlets is correspondingly connected to one of the bellows; the bellows are correspondingly connected to liquid nitrogen inlets of the first cooling module (1) and the second cooling module (2).

3. The precooling device according to claim 2, characterized in that: The liquid nitrogen sleeve and the metal hose are sealed by a ball head; the bellows and the liquid nitrogen sleeve, the bellows and the first cooling module (1), and the bellows and the second cooling module (2) are all sealed by a ball head; the adapter flange and the vacuum box (3), and the outer tube (42) and the vacuum box (3) are all sealed by a sealing ring.

4. The precooling device according to any one of claims 1 to 3, characterized in that: The second cooling module (2) further comprises a cold shield (23), wherein the cold shield (23) is arranged on the inner side of the second supporting base (22), and the cold shield (23) is fixed on the hot end flange (5).

5. The precooling device according to claim 1, characterized in that: The cold blocks (12) include four cold blocks (12), and the cold blocks (12) are arranged in pairs, and a receiving hole corresponding to the compressor is provided on the opposite side of each pair of the cold blocks (12).

6. The precooling device according to claim 5, characterized in that: The first supporting base (11) comprises: A pair of support plates, respectively arranged on two sides of the bottom of the cold block (12); A heat insulation board is arranged at the bottom of the support board, and the heat insulation board is used to insulate the cold block (12) and the vacuum box (3).

7. The precooling device according to claim 6, characterized in that: The heat insulation board is a polytetrafluoroethylene board.

8. The precooling device according to claim 1, characterized in that: The phase adjustment mechanism comprises an air reservoir (6) and an inertia tube, and a side surface of the liquid nitrogen tank (21) is provided with an opening groove (7) with rounded corners, the opening groove (7) is used for the inertia tube to pass through, and the inertia tube is coiled around the outer circumference of the liquid nitrogen tank (21) and connected to the air reservoir (6).

9. The precooling device according to claim 8, characterized in that: The gas reservoir (6) is a waist-shaped hole gas reservoir, which is fixed on the top of the liquid nitrogen tank (21), and the gas reservoir (6) is in contact with the liquid nitrogen tank (21) through a pre-tightening force.

10. A pulse tube refrigerator, characterized in that: include: A pulse tube refrigerator body and a precooling device as claimed in any one of claims 1 to 9, wherein the precooling device is used to cool the pulse tube refrigerator body.

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