A gas phase modulation integrated device for a thermally coupled multi-stage pulse tube refrigerator

Abstract

The application relates to a gas phase modulation integrated device for a thermal coupling type multistage pulse tube refrigerator, which comprises a high-temperature stage inertance tube, a gas reservoir assembly, a room-temperature piston and a leaf spring assembly; the gas reservoir assembly comprises a first gas reservoir and a second gas reservoir; the high-temperature stage inertance tube comprises a first inertance tube and a second inertance tube, the first inertance tube is located outside the gas reservoir assembly, and the second inertance tube is located inside the first gas reservoir; one end of the first inertance tube is connected with a high-temperature stage heat end gas distribution seat of the refrigerator, and the other end is connected with the second inertance tube; the leaf spring assembly is installed in the second gas reservoir; one end of the room-temperature piston extends into the second gas reservoir and is connected with the leaf spring assembly, and the other end is connected with a low-temperature stage heat end gas distribution seat of the refrigerator. The phase modulation mode of the leaf spring support + room-temperature piston not only greatly improves the phase modulation capacity, improves the performance and efficiency of the refrigerator, but also reduces the space occupied by the phase modulation device in the periphery of the refrigerator, makes the structure of the refrigerator more compact, and improves the reliability of the whole machine.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of low-temperature refrigeration, and particularly relates to a gas phase modulation integrated device for a heat-coupled multistage pulse tube refrigerator. BACKGROUND

[0002] With the continuous development of science and technology in various industries, the application range of the low-temperature refrigerator is continuously expanded, and the low-temperature refrigerator has important applications in the fields of aerospace, national defense and military industry, low-temperature superconducting, medical treatment, transportation and the like, and meanwhile, higher requirements are put forward for the performance, service life, mechanical vibration and the like of the refrigerator.

[0003] The traditional regenerative low-temperature refrigerator has poor reliability and large vibration because of the moving parts at the cold end, which limits the application of the refrigerator in many occasions. The pulse tube refrigerator has high reliability and small mechanical vibration because of no moving parts in the low-temperature zone, and has a wide application prospect. In order to reach the liquid hydrogen or lower temperature zone, the pulse tube refrigerator needs to adopt a multistage coupling structure arrangement mode. At present, the common coupling modes are gas coupling and heat coupling. The gas coupling is generally that the pulse tubes of each stage are coaxially arranged and coupled by the internal gas. The gas coupling structure is relatively compact, but because the gas is connected, the gas flow distribution exists in the pulse tubes of each stage, which is difficult to control and quantify, and the pre-cooling stage cannot take cold under this structure, and the efficiency is low. The heat coupling is to connect the high-temperature stage pulse tube and the low-temperature stage pulse tube through a cold chain, and to transfer the cold quantity by the metal heat conduction. The gas flow between the stages of the heat coupling type pulse tube is independent of each other, the parameters of each stage can be designed and optimized independently, and the pulse tube structure is more flexible, which is suitable for U-shaped, linear and the like layout forms, and can realize the coupling connection between the stages of the three-stage or four-stage pulse tube, so as to reach a lower refrigeration temperature, but the disadvantage is that the weight and volume of the system are increased.

[0004] The research on the phase modulation mechanism is of great significance to the development of the pulse tube refrigerator. The multistage pulse tube refrigerator has multiple phase modulation mechanisms, and the research on the multistage phase modulation technology is crucial to improve the performance of the refrigerator. At present, the developed phase modulation modes mainly include small hole phase modulation, inertance tube phase modulation, two-way gas inlet, multi-path bypass and the like. Among them, the inertance tube and gas reservoir cooperative phase modulation is to use the inertial action of the alternating flow of the working gas in the slender tube to adjust the phase difference between the pressure wave and the mass flow, so as to improve the cold end enthalpy flow, has the advantages of simple structure, wide phase modulation range and no increase of the compressor power consumption, and is the preferred phase modulation mode for the high-temperature stage of the pulse tube refrigerator. For the low-temperature stage phase modulation, the inertance tube and gas reservoir cooperative phase modulation mode can also be adopted. However, higher requirements are put forward for the parameters such as the inertance tube specification and the gas reservoir volume, and the phase modulation capacity is difficult to meet the actual needs.

[0005] The high-temperature stage of the existing heat-coupled multi-stage pulse tube refrigerator needs to be individually phased. The inertia tube + gas reservoir cooperative phasing mode is mostly used for the high-temperature stage, which can meet the phasing requirement, but the inertia tube generally has a length of about 3 meters, and the gas reservoir also needs to ensure a certain volume, so the overall structure occupies a large space, and the peripheral layout of the refrigerator is difficult. The inertia tube + gas reservoir cooperative phasing mode can also be used for the low-temperature stage, but the phasing capacity is slightly insufficient, which is not conducive to further reducing the lowest temperature of the pulse tube refrigerator and affects the efficiency of the refrigerator. Moreover, this method further increases the space occupied by the periphery, resulting in a large structure size of the whole machine, and the inertia tubes and gas reservoirs of each stage need to be fixed additionally, otherwise the inertia tube may be twisted or broken, which is not conducive to the transportation of the refrigerator or the use of the refrigerator with other systems.

[0006] Therefore, it is urgent to realize a gas phasing integrated device for a heat-coupled multi-stage pulse tube refrigerator, which can improve the phasing capacity and the performance and efficiency of the refrigerator. SUMMARY

[0007] The purpose of the present application is to provide a gas phasing integrated device for a heat-coupled multi-stage pulse tube refrigerator, which can solve the problems in the prior art, adopt a phasing mode of plate spring support + room temperature piston, greatly improve the phasing capacity, and improve the performance and efficiency of the refrigerator; meanwhile, the integrated structure reduces the space occupied by the phasing device in the periphery of the refrigerator, makes the structure of the refrigerator more compact, and improves the reliability of the whole machine.

[0008] To achieve the above purpose, the following technical solutions are adopted in the present application:

[0009] A gas phasing integrated device for a heat-coupled multi-stage pulse tube refrigerator, which comprises: a high-temperature stage inertia tube, a gas reservoir assembly, a room temperature piston and a plate spring assembly; the gas reservoir assembly comprises a first gas reservoir and a second gas reservoir which are sequentially arranged and connected; the high-temperature stage inertia tube comprises a first inertia tube and a second inertia tube which are sequentially connected, wherein the first inertia tube is located outside the gas reservoir assembly, and the second inertia tube is located inside the first gas reservoir; one end of the first inertia tube is connected with a high-temperature stage heat end gas distribution seat of the refrigerator, and the other end is connected with the second inertia tube; the plate spring assembly is installed in the second gas reservoir; one end of the room temperature piston extends into the second gas reservoir and is connected with the plate spring assembly, and the other end is connected with a low-temperature stage heat end gas distribution seat of the refrigerator.

[0010] As a further improvement of the above technical solution, the high-temperature level inertance tube adopts a total length of 3m of red copper pipe, wherein the outer diameter of the first inertance tube is 3mm, the inner diameter is 2mm, and the length is 1.5m; the outer diameter of the second inertance tube is 4mm, the inner diameter is 3mm, and the length is 1.5m; the first inertance tube and the second inertance tube are connected by vacuum brazing welding; the second inertance tube is spiral-shaped, and the spiral outer diameter size and height can be placed inside the first gas reservoir.

[0011] As a further improvement of the above technical solution, the first gas reservoir and the second gas reservoir are connected by laser welding to form a gas reservoir assembly; the first gas reservoir and the second gas reservoir are both made of stainless steel.

[0012] As a further improvement of the above technical solution, the first gas reservoir includes a first gas reservoir body; a first via hole is formed in the top of the first gas reservoir body, a first support platform is arranged at the bottom of the first gas reservoir body, and a second via hole is formed in the first support platform; a stepped connecting portion is arranged at the lower end of the first gas reservoir body; the second gas reservoir includes a second gas reservoir body; a stepped opening is arranged at the top of the second gas reservoir body; a second support platform is arranged on the inner side of the middle section of the second gas reservoir body; the leaf spring assembly is placed on the second support platform; an extension portion is arranged below the second gas reservoir body; an outlet is formed in the extension portion; the connecting portion and the opening are matched with each other and used for welding connection of the first gas reservoir and the second gas reservoir; the connecting portion is overlapped at the opening, and laser welding is performed at the contact surface of the two, so that the first gas reservoir and the second gas reservoir are connected as a whole by laser welding.

[0013] As a further improvement of the above technical solution, the high-temperature level inertance tube and the high-temperature level heat end gas distribution seat of the refrigerator are connected by flame brazing.

[0014] As a further improvement of the above technical solution, a part of the high-temperature level inertance tube is processed into a spiral shape, placed on the first support platform of the first gas reservoir after passing through the first via hole of the first gas reservoir, and the connection between the high-temperature level inertance tube and the first gas reservoir is sealed by flame brazing.

[0015] As a further improvement of the above technical solution, gap sealing is adopted between the room temperature piston and the second gas reservoir, and the gap therebetween is 0.02mm; the other end of the room temperature piston extends into the low-temperature level pulse tube of the refrigerator, and gap sealing is adopted therebetween, and the gap is 0.02mm.

[0016] As a further improvement of the above technical solution, the plate spring assembly includes a cushion block and a first plate spring and a second plate spring respectively installed on the upper and lower sides of the cushion block; the first plate spring and the second plate spring are the same in structure and each include two washers and a plate spring between the two washers; the cushion block includes an inner cushion block and an outer cushion block. One plate spring is installed in the two washers and placed on a second support platform inside a second gas reservoir and the cushion block, which includes an inner cushion block and an outer cushion block, and then screws are passed through the washers, the plate spring, the washers, the cushion block, the washers, the plate spring, and the washers, respectively, with the outer screws installed on the threaded holes of the second gas reservoir internal step and the inner screws installed on the threaded holes of the connecting seat.

[0017] As a further improvement of the above technical solution, the plate spring assembly is placed on the second support platform of the second gas reservoir and connected with the upper end of the room temperature piston through the screws and the connecting seat.

[0018] As a further improvement of the above technical solution, the extension of the second gas reservoir is inserted into a low-temperature stage hot end gas distribution seat, and the second gas reservoir and the low-temperature stage hot end gas distribution seat are connected by vacuum brazing welding; the low-temperature stage hot end gas distribution seat is installed on the hot end flange of the refrigerator.

[0019] Compared with the prior art, the advantages of the present application are:

[0020] (1) The gas phase modulation integrated device for the hot-coupled multi-stage pulse tube refrigerator can solve the deficiencies in the prior art, integrate the high-temperature stage inertia tube and the gas reservoir, actively modulate the phase of the low-temperature stage using the room temperature piston, and place it in the high-temperature stage gas reservoir, and finally weld the whole on the high-temperature stage hot end of the refrigerator. The low-temperature stage of the integrated phase modulation device uses a phase modulation method of plate spring support + room temperature piston, which greatly improves the phase modulation capability and improves the performance and efficiency of the refrigerator; at the same time, the integrated structure reduces the space occupied by the phase modulation device in the periphery of the refrigerator, makes the structure of the refrigerator more compact, and also improves the reliability of the whole machine.

[0021] (2) The gas phase modulation integrated device for the heat-coupled multi-stage pulse tube refrigerator according to the application integrates the high-temperature stage and the low-temperature stage phase modulation device together to form a component, effectively reduces the size of the whole machine, makes the whole machine structure more compact, improves the reliability of the whole machine, and at the same time, the device and the refrigerator are welded as a whole to improve the stability of the whole machine. At the same time, the low-temperature stage phase modulation adopts a room temperature piston phase modulation device, which improves the phase modulation capacity and greatly improves the performance and efficiency of the refrigerator. Compared with the traditional two-way gas inlet phase modulation method, the calculation shows that under the same pressure ratio, the room temperature piston phase modulation needs to consume nearly 50% less sound power, and the efficiency is more than doubled. The experimental results show that compared with the traditional phase modulation mechanism, the refrigeration efficiency is improved by nearly 70% under the same input power. The application is suitable for heat-coupled two-stage pulse tube refrigerators, and can also provide a reference for the design of phase modulation devices for three-stage and four-stage pulse tube refrigerators.

[0022] (3) The gas phase modulation integrated device for the heat-coupled multi-stage pulse tube refrigerator according to the application adopts a plate spring support, compared with the traditional column spring, the plate spring can provide a larger radial stiffness for the room temperature piston, ensuring that the room temperature piston cooperates with the gap of the pulse tube and the outlet of the gas reservoir during movement; at the same time, the axial stiffness adjustment of the plate spring support can be realized by changing the thickness and the number of the plate spring, which is relatively convenient and easy to realize, and the assembly of the component is also simpler. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 FIG. 1 is a structural schematic diagram of the gas phase modulation integrated device for the heat-coupled multi-stage pulse tube refrigerator according to the application;

[0024] Figure 2 FIG. 2 is a cross-sectional structural schematic diagram of the gas phase modulation integrated device for the heat-coupled multi-stage pulse tube refrigerator according to the application;

[0025] Figure 3 FIG. 3 is a first gas reservoir structure schematic diagram in the application;

[0026] Figure 4 FIG. 4 is a second gas reservoir structure schematic diagram in the application;

[0027] Figure 5 FIG. 5 is a cross-sectional structural schematic diagram of the gas phase modulation integrated device for the heat-coupled multi-stage pulse tube refrigerator according to the application and the coupling connection of the refrigerator hot end flange;

[0028] Figure 6 FIG. 6 is a curve diagram of the lowest temperature and refrigeration capacity corresponding to different phase modulation mechanisms.

[0029] Wherein:

[0030] 1. High-temperature inertial tube, 2. Gas storage assembly, 3. Room temperature piston, 4. Leaf spring, 5. Connecting seat, 6. Washer, 7. Pad, 8. High-temperature stage hot end gas distribution seat of the refrigerator, 9. Low-temperature stage hot end gas distribution seat of the refrigerator, 10. Hot end flange of the refrigerator, 11. First gas storage, 12. Second gas storage, 13. Flame brazing welding point A, 14. Flame brazing welding point B, 15. Laser welding welding point C, 16. Vacuum brazing welding point D. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings:

[0032] Cryogenic refrigeration technology is widely used in aerospace, exploration, and other scientific and technological fields. It generally places high demands on the vibration, lifespan, and reliability of the cryogenic compressor, and pulse tube cryogenic compressors have certain advantages over traditional Stirling cryogenic compressors in these aspects. Currently, commonly used phase-tuning structures have limited phase-tuning ranges, resulting in suboptimal sound field distribution and significant losses. Furthermore, the considerable expansion acoustic energy at the hot end of the pulse tube in the higher temperature range is not recovered, limiting the efficiency improvement of pulse tube cryogenic compressors. The phase-tuning mechanisms surrounding the compressor (inertial tubes, cryogenic gas chambers, etc.) occupy a large volume and are also heavy. Therefore, for thermally coupled multi-stage pulse tube cryogenic compressors, it is necessary to further improve the performance and reliability of pulse tube cryogenic compressors and maximize product integration.

[0033] This invention proposes a thermally coupled, multi-stage pulse tube refrigerator with integrated gas phase adjustment device. This device effectively solves the technical problem of insufficient phase adjustment capability in the low-temperature stage of the pulse tube refrigerator, overcoming the inherent bias of traditional pulse tube refrigerators that use an inertial tube + gas reservoir for phase adjustment. Simultaneously, it also features hot-end expansion work recovery and the function of the high-temperature stage driving the low-temperature stage for joint phase adjustment, further improving the pulse tube expansion efficiency and thus enhancing the refrigerator's performance. This invention employs a room-temperature piston + leaf spring structure to provide radial support for piston movement, solving the technical problems of wear and short lifespan during operation. In terms of the external structure, this invention integrates the two-stage phase adjustment mechanism and fixes it by welding, solving the technical problems of complex and space-consuming external structures, difficult layout, and easy breakage and bending of the inertial tube in pulse tube refrigerators. This improves the reliability of the mechanism while reducing the overall size and weight of the machine.

[0034] like Figure 1 The gas phase-adjusting integrated device for a thermally coupled multi-stage pulse tube refrigerator shown includes a high-temperature inertial tube 1, a gas storage assembly 2, a room-temperature piston 3, and a leaf spring assembly.

[0035] The gas phase modulation integrated device of the thermal coupling type multi-stage pulse tube refrigerator can be applied to a thermal coupling type two-stage pulse tube refrigerator. The high-temperature stage of the refrigerator adopts a combined phase modulation mode of a high-temperature stage inertance tube 1 and a gas reservoir assembly 2. The inertance tube and the gas reservoir cooperate to modulate the phase difference by using the inertial effect of the alternating flow of the working gas in the slender tube, which has the advantages of simple structure, wide phase modulation range and no increase in compressor power consumption. It is the preferred phase modulation mode in the pulse tube refrigerator, which can greatly improve the phase modulation capability and improve the performance and efficiency of the refrigerator.

[0036] As shown in Figure 2 and Figure 5 , the high-temperature stage inertance tube 1 includes two sections of first and second inertance tubes arranged in sequence and connected in communication, wherein the first inertance tube is located outside the gas reservoir assembly 2, and the second inertance tube extends into the interior of the gas reservoir assembly 2. The second inertance tube is spiral. The high-temperature stage inertance tube 1 uses a total length of 3m of red copper pipe, wherein the inner diameter of the first inertance tube is 2mm, and the length is 1.5m, the inner diameter of the second inertance tube is 3mm, and the length is 1.5m, and the first inertance tube and the second inertance tube are connected by vacuum brazing welding. The size of the first and second inertance tubes is obtained by creative labor. First, based on theoretical analysis, the phase angle and mass flow required for the inertance tube are obtained, then the DeltaEC software based on the thermoacoustic theory is used to simulate the design of the inertance tube, and on the basis of the design, different inertance tube diameters, lengths and related experimental verification are carried out, and finally the inertance tube combination form of the size combination is obtained.

[0037] As shown in Figure 2 and Figure 5 , the gas reservoir assembly 2 includes first and second gas reservoirs 11 and 12 arranged in sequence. The first and second gas reservoirs 11 and 12 are made of stainless steel. The first and second gas reservoirs 11 and 12 are connected by laser welding to form the gas reservoir assembly 2. The first and second gas reservoirs are made into a communication form, which can simplify the internal structure, and can make the movement of the room temperature piston cause the flow of the low temperature stage gas to be synchronized to affect the gas phase modulation of the high temperature stage, further improving the phase modulation capability.

[0038] As a further improvement of the above technical solution, as shown in Figure 3As shown, the first gas reservoir 11 comprises a first gas reservoir body; a first through hole is formed in the top of the first gas reservoir body; a first support platform is arranged at the bottom of the first gas reservoir body, and a second through hole is formed in the first support platform; and a stepped connecting portion is arranged at the lower end of the first gas reservoir body. The outer diameter of the second inertia tube is 4 mm, and the second inertia tube is formed in a spiral shape by a bent tube. The size of the first inertia tube is matched with the first through hole at the top of the first gas reservoir body. After the first inertia tube is passed through the first through hole, the first inertia tube is flame brazed with the second inertia tube. At this time, the first inertia tube and the second inertia tube have formed an integral whole. Then, the second inertia tube is placed on the first support platform. Finally, the first through hole and the first inertia tube are welded by flame welding, so as to ensure the airtightness of the gas reservoir assembly. The inertia tube is arranged in the gas reservoir in this structure, so as to effectively reduce the space occupied by the peripheral phase modulation assembly. Meanwhile, the spiral-shaped second inertia tube further reduces the occupied volume. In addition, the second inertia tube is placed on the step inside the first gas reservoir, so that the stress of the copper tube itself is removed. The two ends of the first inertia tube are also fixed by welding, so as to reduce the distortion and fracture phenomenon of the inertia tube caused by transportation and testing, and the reliability of the structure is improved.

[0039] As a further improvement of the above technical solution, as shown in the drawings, Figure 4 As shown, the second gas reservoir 12 comprises a second gas reservoir body; a stepped opening is arranged at the top of the second gas reservoir body, and the opening is used for matched welding with the opening of the first gas reservoir. A second support platform is arranged on the inner side of the middle section of the second gas reservoir body, and a mounting threaded hole is arranged on the second support platform; the leaf spring assembly is placed on the second support platform, and the leaf spring assembly is fixed with the second support platform and the connecting seat by screws. The upper side of the connecting seat is connected with the leaf spring assembly by screws, so that the room temperature piston moves back and forth while driving the leaf spring assembly to move along with it through the connecting seat. The stiffness of the leaf spring assembly affects the displacement and phase modulation capacity of the room temperature piston. An extension portion is arranged below the second gas reservoir body. An outlet is formed in the extension portion, and the outlet leads to the low-temperature stage pulse tube side. The size of the outlet is matched with the gap of the room temperature piston 3, so as to ensure the reciprocating movement while adjusting the phase and recovering the work.

[0040] As a further improvement of the above technical solution, the connecting portion and the opening are matched with each other, and stepped grooves matched with each other are formed in the connecting portion and the opening for positioning during welding, so as to connect the first gas reservoir 11 and the second gas reservoir 12 by welding. The connecting portion is overlapped on the opening, and laser welding is performed at the contact surface of the two, so that the first gas reservoir 11 and the second gas reservoir 12 are connected as a whole by laser welding. The laser welding point between the first gas reservoir 11 and the second gas reservoir 12 is Figure 5Laser welding point C15 is used in the stainless steel gas storage unit. Laser welding results in high weld strength, is easy to operate, and the stepped groove effectively ensures welding precision and stability.

[0041] like Figure 5 As shown, one end of the high-temperature stage inertial tube 1 is connected to the hot-end gas distribution seat 8 of the high-temperature stage of the refrigerator. The high-temperature stage inertial tube 1 and the hot-end gas distribution seat 8 of the high-temperature stage of the refrigerator are connected by flame brazing. The connection point between the high-temperature stage inertial tube 1 and the hot-end gas distribution seat 8 of the high-temperature stage of the refrigerator is... Figure 5 The flame brazing welding point A13 is shown. The other end of the high-temperature inertial tube 1 extends into the first gas reservoir 11, and the high-temperature inertial tube 1 located in the first gas reservoir 11 is spiral-shaped. The high-temperature inertial tube extending into the gas reservoir assembly 2 is placed on the first support platform. A certain length of inertial tube 1 is formed into a spiral shape through a tube bending process, passes through the first through hole on the first gas reservoir 11, and is placed on the first support platform of the first gas reservoir 11. The connection between the high-temperature inertial tube 1 and the first gas reservoir 11 is sealed by flame brazing. Figure 5 The flame brazing in the image refers to welding point B14.

[0042] As a further improvement to the above technical solution, one end of the room temperature piston 3 extends into the second gas reservoir 12; the other end of the room temperature piston 3 passes through the outlet and extends into the interior of the second gas reservoir 12. A gap seal is used between the room temperature piston 3 and the second gas reservoir 12, with a gap of 0.02 mm; the other end of the room temperature piston 3 extends into the low-temperature stage pulse tube of the refrigerator, and a gap seal is also used between them, with a gap of 0.02 mm.

[0043] As a further improvement of the above technical solution, the plate spring assembly comprises a cushion block 7 and a first plate spring and a second plate spring respectively installed on the upper and lower sides of the cushion block 7; the first plate spring and the second plate spring are the same in structure and each comprises two gaskets 4 and a plate spring 4 located between the two gaskets 4; the cushion block 7 comprises an inner cushion block and an outer cushion block. One plate spring 4 is loaded in the two gaskets 4 and is respectively placed on a second support platform inside a second gas reservoir 12 and on the cushion block 7, the cushion block 7 comprises an inner cushion block and an outer cushion block, and then screws are respectively passed through the gasket 6, the plate spring 4, the gasket 6, the cushion block 7, the gasket 6, the plate spring 4 and the gasket 6, the outer screw is installed on the threaded hole of the step inside the second gas reservoir 12, and the inner screw is installed on the threaded hole of the connecting seat 5. The specifications of each part in the plate spring assembly, such as the plate spring stiffness and the gasket height, need to be determined through preliminary tests. The assembled plate spring assembly is placed on the second support platform of the second gas reservoir 12 and is connected with the connecting seat 5 and the upper end of the room temperature piston 3 through the screws. The extension part of the second gas reservoir 12 is inserted into the low-temperature stage hot end gas distribution seat 9, and the second gas reservoir 12 and the low-temperature stage hot end gas distribution seat 9 are connected at the vacuum brazing welding point D16 in the Figure 5 The vacuum brazing welding point D16 is coated with solder, and the second gas reservoir 11 and the low-temperature stage hot end gas distribution seat 9 are welded and connected together through vacuum brazing. Finally, the low-temperature stage hot end gas distribution seat 9 is installed on the refrigerator hot end flange 10, thereby completing the assembly.

[0044] The working principle of the gas phase adjustment integrated device for the thermal coupling type multi-stage pulse tube refrigerator according to the present application is as follows:

[0045] After the thermal coupling type two-stage pulse tube refrigerator is started, the refrigerator performs compression movement, and the working gas in the interior flows into the gas reservoir assembly 2 from the high-temperature stage hot end through the inertia tube 1, thereby changing the movement state of the hot end gas and completing the phase adjustment function. At the same time, since the first gas reservoir and the second gas reservoir are connected, a part of the gas can assist the phase adjustment of the low-temperature stage gas. Then, when the refrigerator performs expansion movement, the internal gas flows back to the high-temperature stage hot end from the gas reservoir assembly 2, thereby completing one working cycle. The gas at the low-temperature stage hot end also undergoes the compression and expansion processes, and the gas after the pulse tube drives the room temperature piston 3 to move. The plate spring assembly has a certain mechanical stiffness and can control the reciprocating movement of the room temperature piston 3, complete the phase adjustment, and recover a part of the expansion work. The device can adjust the phase angle of the working gas pressure wave and mass flow at different temperature zones and improve the performance of the refrigerator.

[0046] In the application, the phase modulation mode of the commonly used low-temperature stage inertia tube + gas reservoir is removed, and the phase modulation is performed by using the structure of room temperature piston + leaf spring. The structure of inertia tube + first gas reservoir can meet the phase modulation demand of high-temperature stage gas, and the first and second gas reservoirs are connected, and the high-temperature stage gas can also play the role of auxiliary phase modulation for the low-temperature stage. The inertia tube is bent and placed on the first support platform in the first gas reservoir, and the first and second gas reservoirs are welded by laser to form a single gas reservoir assembly, which integrates the phase modulation structure. The phase modulation mode of room temperature piston + leaf spring solves the problem of insufficient phase modulation capacity of the low-temperature stage of the multi-stage pulse tube refrigerator, and improves the efficiency and performance of the refrigerator. The leaf spring structure can provide appropriate radial stiffness support for the movement of the room temperature piston, ensure the long-term gap movement of the piston at the outlet of the second gas reservoir, and improve the service life of the phase modulation mechanism.

[0047] The application solves the technical problems of large size and layout of the two-stage phase modulation mechanism of the multi-stage pulse tube refrigerator, reduces the occupied space outside the refrigerator, and reduces the volume of the whole machine. At the same time, the first and second gas reservoirs are integrated, the long low-temperature stage inertia tube structure is removed, and the weight of the whole machine is also reduced. The high-temperature stage inertia tube is spirally placed in the gas reservoir, which further reduces the volume occupied by the phase modulation mechanism. At the same time, the inertia tube is placed on the support platform, and the connection positions are all fixed by welding, which reduces the stress of the phase modulation mechanism itself, reduces the bending, breaking and other phenomena caused by the free state of the inertia tube, and further improves the reliability of the phase modulation mechanism.

[0048] The specific assembly steps of the thermal coupling type multi-stage pulse tube refrigerator gas phase modulation integrated device before use are as follows:

[0049] S1, select a high-temperature stage inertia tube 1 with appropriate length, bend a part of the tube into a spiral shape and place it in the first gas reservoir 11, and the remaining straight tube passes through the first through hole above the first gas reservoir 11. The spiral part of the high-temperature stage inertia tube 1 is placed on the first support platform in the first gas reservoir 11.

[0050] S2, place a piece of leaf spring 4 between two pieces of gasket 6, then place it on the upper side of pad 7, and then place two pieces of gasket 6 and a piece of leaf spring 4 between the two pieces of gasket 6 on the lower side of pad 7, forming a leaf spring assembly, and finally connecting the leaf spring 4, gasket 6 and pad 7 through screws, and assembling them into the threaded holes of the connecting seat 5 and the second support platform in the second gas reservoir 12. The position degree of the leaf spring assembly needs to be ensured during assembly, and the relative positions of the parts can be determined by laser welding after assembly is completed to improve the stability of the assembly.

[0051] S3, vacuum brazing the second gas reservoir 12 and the low-temperature stage hot-end gas distribution seat 9 at the vacuum brazing joint D16 to form an assembly, and then inserting the room-temperature piston 3 into the low-temperature stage pulse tube through the outlet on the second gas reservoir 12; placing a leaf spring assembly on the second support platform of the second gas reservoir 12, and assembling the leaf spring assembly and the room-temperature piston 3 together through the connecting seat 5, and ensuring the coaxiality of the room-temperature piston 3, the pulse tube and the outlet below the second gas reservoir 12 during the assembly; and then loading the overall structure into the cryogenic machine hot-end flange 10 through the low-temperature stage hot-end gas distribution seat 9.

[0052] S4, assembling the first gas reservoir 11 provided with the high-temperature stage inertance tube 1 and the second gas reservoir 12 provided with the room-temperature piston 3 and the leaf spring assembly together, and laser welding at the side welding joint (i.e. the laser welding joint C15 in Figure 6 ) to form a sealed gas reservoir assembly 2.

[0053] S5, loading the high-temperature stage hot-end gas distribution seat 8 into the cryogenic machine hot-end flange 10, and inserting the other end of the high-temperature stage inertance tube 1 into the high-temperature stage hot-end gas distribution seat 8, and then performing flame brazing at the flame brazing joint A13 and the flame brazing joint B14 to fix the positions of the parts.

[0054] After the step S5 is completed, the assembly, welding and coupling with the heat-coupled two-stage pulse tube refrigerator of the gas phase modulation integrated device for the heat-coupled multi-stage pulse tube refrigerator are completed, and the complete refrigerator is formed.

[0055] With the same pulse tube refrigerator parameters (total power, frequency, charging pressure, etc.), different phase modulation mechanisms are used respectively, and the lowest temperature and cold capacity experimental results are obtained as shown in Figure 6 , and the comparison of the related design parameters and experimental results is shown in Table 1.

[0056] Table 1 Comparison of design parameters and experimental results of different phase modulation mechanisms

[0057]

[0058] From ​ and the experimental results shown in Table 1, it can be seen that, under the premise of the total electric power being 440W and other operating parameters being the same, the use of the integrated device for phase modulation can obtain a no-load temperature of 10.23K, and the cold capacity at 20K is also increased from the previous 0.5W to 0.95W. Compared with the traditional inertance tube + gas reservoir phase modulation method, the relative Carnot efficiency of the new structure is increased by nearly 90%, and the experiment can prove that the integrated phase modulation device can better improve the efficiency of the refrigerator and improve the performance of the refrigerator.

[0059] The above-described embodiments are merely intended to describe the preferred embodiments of the present application, and are not intended to limit the scope of the present application. Various modifications and improvements to the present application made by those skilled in the art are intended to fall within the scope of the present application defined in the claims.

Claims

1. A gas phase modulation integrated device for a thermally coupled multi-stage pulse tube refrigerator, characterized in that, The integrated gas phase modulation device includes: a high-temperature inertial tube (1), a gas storage assembly (2), a room-temperature piston (3), and a leaf spring assembly; The gas storage assembly (2) includes a first gas storage (11) and a second gas storage (12) arranged sequentially and connected to each other; The high-temperature stage inertial tube (1) includes a first inertial tube and a second inertial tube connected in sequence. The first inertial tube is located outside the gas storage assembly (2), and the second inertial tube is located inside the first gas storage (11). One end of the first inertial tube is connected to the hot end gas distribution seat (8) of the high-temperature stage of the refrigeration machine, and the other end is connected to the second inertial tube. The leaf spring assembly is installed inside the second gas chamber (12); one end of the room temperature piston (3) extends into the second gas chamber (12) and is connected to the leaf spring assembly, and the other end is connected to the hot end gas distribution seat (9) of the low temperature stage of the refrigerator.

2. The integrated gas phase-changing device for a thermally coupled multi-stage pulse tube refrigerator according to claim 1, characterized in that, The high-temperature inertial tube (1) is a copper tube with a total length of 3m. The first inertial tube has an outer diameter of 3mm, an inner diameter of 2mm, and a length of 1.5m. The second inertial tube has an outer diameter of 4mm, an inner diameter of 3mm, and a length of 1.5m. The first inertial tube and the second inertial tube are connected by vacuum brazing. The second inertial tube is spiral.

3. The integrated gas phase-changing device for a thermally coupled multi-stage pulse tube refrigerator according to claim 1, characterized in that, The first gas storage unit (11) and the second gas storage unit (12) are connected by laser welding to form a gas storage unit assembly (2); both the first gas storage unit (11) and the second gas storage unit (12) are made of stainless steel.

4. The integrated gas phase-changing device for a thermally coupled multi-stage pulse tube refrigerator according to claim 1, characterized in that, The first gas storage unit (11) includes a first gas storage body; a first through hole is provided at the top of the first gas storage body, a first support platform is provided at the bottom of the first gas storage body, and a second through hole is provided on the first support platform; a stepped connecting part is provided at the lower end of the first gas storage body. The second gas storage unit (12) includes a second gas storage body; a stepped opening is provided at the top of the second gas storage body; a second support platform is provided on the inner side of the middle section of the second gas storage body; the leaf spring assembly is placed on the second support platform; an extension is provided below the second gas storage body; an outlet is provided on the extension. The connecting part cooperates with the opening to weld the first gas reservoir (11) and the second gas reservoir (12) together; the connecting part overlaps the opening and laser welding is performed at the contact surface of the two, thereby connecting the first gas reservoir (11) and the second gas reservoir (12) into one unit by laser welding.

5. The integrated gas phase-changing device for a thermally coupled multi-stage pulse tube refrigerator according to claim 1, characterized in that, The high-temperature stage inertial tube (1) and the high-temperature stage hot end gas distribution seat (8) of the refrigeration machine are connected by flame brazing.

6. The integrated gas phase-changing device for a thermally coupled multi-stage pulse tube refrigerator according to claim 4, characterized in that, After a portion of the high-temperature inertial tube (1) is processed into a spiral shape, it passes through the first through hole on the first gas reservoir (11) and is placed on the first support platform of the first gas reservoir (11). The connection between the high-temperature inertial tube (1) and the first gas reservoir (11) is sealed by flame brazing.

7. The integrated gas phase-changing device for a thermally coupled multi-stage pulse tube refrigerator according to claim 1, characterized in that, The room temperature piston (3) and the second gas reservoir (12) are sealed with a gap of 0.02 mm; the other end of the room temperature piston (3) extends into the low temperature stage pulse tube of the refrigerator, and the two are sealed with a gap of 0.02 mm.

8. The integrated gas phase-changing device for a thermally coupled multi-stage pulse tube refrigerator according to claim 4, characterized in that, The leaf spring assembly includes a pad (7) and a first leaf spring and a second leaf spring respectively installed on the upper and lower sides of the pad (7); the first leaf spring and the second leaf spring have the same structure, each including two washers (6) and a leaf spring (4) located between the two washers (6); the pad (7) includes an inner pad and an outer pad.

9. The integrated gas phase-changing device for a thermally coupled multi-stage pulse tube refrigerator according to claim 1, characterized in that, The leaf spring assembly is placed on the second support platform of the second air chamber (12) and connected to the upper end of the room temperature piston (3) by screws and connecting seat (5).

10. The integrated gas phase-changing device for a thermally coupled multi-stage pulse tube refrigerator according to claim 1, characterized in that, The extension of the second gas reservoir (12) is inserted into the low-temperature stage hot end gas distribution seat (9), and the second gas reservoir (12) and the low-temperature stage hot end gas distribution seat (9) are welded together by vacuum brazing; the low-temperature stage hot end gas distribution seat (9) is installed on the hot end flange (10) of the refrigeration unit.

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