Low-temperature phase modulation method and structure of GM pulse tube refrigerator

Abstract

The present invention provides a low-temperature phase adjustment method and structure for a GM pulse tube refrigerator, belonging to the technical field of pulse tube refrigerators. The low-temperature phase adjustment structure of the refrigerator includes a pressure wave generating system, a pulse tube pre-cooling stage refrigeration system, and a pulse tube low-temperature stage refrigeration system, and a transition end is provided between the pulse tube pre-cooling stage refrigeration system and the pulse tube low-temperature stage refrigeration system. By providing a transition end between the pre-cooling stage and the low-temperature stage, the present invention can further achieve a low-temperature phase adjustment effect similar to "multi-path bypass". In addition, the transition end can also simultaneously realize the functions of the cold-end heat exchanger of the pre-cooling stage regenerator, the cold-end deflector of the pre-cooling stage pulse tube, the hot-end heat exchanger of the low-temperature stage regenerator, the low-temperature stage pulse tube pre-cooling heat exchanger, and the low-temperature stage pulse tube middle deflector. Therefore, the present invention can effectively improve the refrigeration efficiency and structural compactness of the refrigerator.

Description

Technical Field

[0001] The present invention relates to the technical field of pulse tube refrigerators, and in particular to a low-temperature phase modulation method and structure of a GM pulse tube refrigerator. Background Art

[0002] GM pulse tube refrigerators in the liquid helium temperature range, due to their outstanding advantages such as high cooling capacity, low vibration, and long life, have important and irreplaceable applications in fields such as quantum computing and condensed matter physics research. However, their market is currently dominated by the United States and Japan. US commercial GM pulse tube refrigerators in the liquid helium temperature range rely on a "small-hole gas reservoir" + "two-way air inlet" structure at the hot end of the system, while Japanese commercial GM pulse tube refrigerators in the liquid helium temperature range rely on a "four-valve" mechanism at the hot end of the system. Both use room temperature phase modulation to improve the refrigerator's cooling performance.

[0003] Room temperature phase modulation indirectly adjusts the phase relationship of the high-density working fluid gas at the low-temperature end by passively changing the impedance of the low-density working fluid gas at the room temperature end. The phase adjustment capability is limited, and the phase relationship within the system is still far from the ideal phase relationship. This greatly limits the further improvement of the refrigeration efficiency of commercial GM pulse tube refrigerators in the liquid helium temperature range (currently, the lowest temperature and cooling capacity of commercial GM pulse tube refrigerators in the liquid helium temperature range are comparable to those of GM refrigerators, but their refrigeration efficiency is still far lower than that of GM refrigerators).

[0004] Low-temperature phase modulation is currently a key method for improving the cooling efficiency of high-frequency pulse tube refrigerators. However, high-frequency pulse tube refrigerators often utilize a "multi-stage thermal coupling" or "coaxial" layout. This structure inherently offers advantages for utilizing low-temperature phase modulation mechanisms such as "low-temperature bidirectional" or "multi-path bypass." Commercial GM pulse tube refrigerators in the liquid helium temperature range often utilize a "two-stage gas coupling" or "U-shaped" layout, making it difficult to utilize existing low-temperature phase modulation technology within this existing structure. Summary of the Invention

[0005] The present invention provides a low-temperature phase adjustment method and structure for a GM pulse tube refrigerator, which is used to solve the bottleneck problem that the conventional commercial liquid helium temperature range GM pulse tube refrigerator has insufficient phase adjustment capability in the existing refrigeration structure and is difficult to further improve the refrigeration efficiency.

[0006] The present invention provides a low-temperature phase modulation method for a GM pulse tube refrigerator, comprising the following steps:

[0007] Compression stage: The high-pressure gas delivered from the compressor is divided into three parts. One part flows directly into the pre-cooling stage regenerator, one part passes through the pre-cooling stage two-way air intake, and one part passes through the low-temperature stage two-way air intake.

[0008] The working gas coming from the precooling stage regenerator is divided into three parts. One part flows into the precooling stage pulse tube through the transition end, and then passes through the precooling stage small hole together with the working gas from the precooling stage two-way air intake after passing through the precooling stage hot end guide, and finally flows into the precooling stage gas reservoir; one part flows into the low-temperature stage regenerator through the transition end, and then passes through the low-temperature stage regenerator cold end heat exchanger and the low-temperature stage pulse tube cold end guide to flow into the cold end of the low-temperature stage pulse tube; one part flows directly into the middle part of the low-temperature stage pulse tube through the transition end, and then passes through the transition end together with the working gas from the cold end of the low-temperature stage pulse tube to be guided and cooled, and then passes through the low-temperature stage hot end guide, together with the working gas from the low-temperature stage two-way air intake, through the low-temperature stage small hole, and finally flows into the low-temperature stage gas reservoir;

[0009] Expansion stage: The gas comes out from the pre-cooling stage gas reservoir and the low-temperature stage gas reservoir and returns to the compressor in the opposite direction of the gas path in the compression stage.

[0010] The present invention also provides a low-temperature phase modulation structure of a GM pulse tube refrigerator, comprising:

[0011] a pressure wave generating system including a compressor and a rotary valve;

[0012] Pulse tube pre-cooling stage refrigeration system, including pre-cooling stage regenerator, pre-cooling stage pulse tube, pre-cooling stage two-way air inlet, pre-cooling stage orifice and pre-cooling stage air reservoir;

[0013] Pulse tube cryogenic refrigeration system, including cryogenic regenerator, cryogenic pulse tube, cryogenic two-way air inlet, cryogenic orifice and cryogenic gas reservoir;

[0014] A transition end is provided between the pulse tube pre-cooling stage refrigeration system and the pulse tube low temperature stage refrigeration system;

[0015] In which, the compressor is connected to one end of the pre-cooling stage regenerator through the rotary valve, the other end of the pre-cooling stage regenerator is connected to the pre-cooling stage pulse tube and one end of the low-temperature stage regenerator respectively through the transition end, the other end of the pre-cooling stage pulse tube is connected to the pressure wave generating system and the pre-cooling stage air reservoir respectively through the pre-cooling stage two-way air intake and the pre-cooling stage small hole; the other end of the low-temperature stage regenerator is connected to the cold end of the low-temperature stage pulse tube through a connecting pipe, and the hot end of the low-temperature stage pulse tube is connected to the pressure wave generating system and the low-temperature stage air reservoir respectively through the low-temperature stage two-way air intake and the low-temperature stage small hole; the low-temperature stage pulse tube is divided into two sections and connected by the transition end, and the pre-cooling stage regenerator is also connected to the middle part of the low-temperature stage pulse tube through the transition end.

[0016] According to a low-temperature phase adjustment structure of a GM pulse tube refrigerator provided by the present invention, the compressor, the rotary valve and the pre-cooling stage regenerator are connected through a gas transmission pipeline, the pre-cooling stage pulse tube, the pre-cooling stage two-way air intake, the pre-cooling stage small hole and the pre-cooling stage gas reservoir are connected through a connecting pipeline, and the low-temperature stage pulse tube, the low-temperature stage two-way air intake, the low-temperature stage small hole and the low-temperature stage gas reservoir are connected through a connecting pipeline.

[0017] According to a low-temperature phase-adjusting structure of a GM pulse tube refrigerator provided by the present invention, the pulse tube pre-cooling stage refrigeration system further includes a pre-cooling stage regenerator hot-end heat exchanger and a pre-cooling stage pulse tube hot-end flow deflector. The pre-cooling stage regenerator hot-end heat exchanger is located at an end of the pre-cooling stage regenerator away from the transition end, and the pre-cooling stage pulse tube hot-end flow deflector is located at an end of the pre-cooling stage pulse tube away from the transition end.

[0018] According to a low-temperature phase-adjusting structure of a GM pulse tube refrigerator provided by the present invention, the pulse tube low-temperature stage refrigeration system also includes a low-temperature stage pulse tube hot end deflector, a low-temperature stage regenerator cold end heat exchanger and a low-temperature stage pulse tube cold end deflector. The low-temperature stage regenerator cold end heat exchanger is located at the end of the low-temperature stage regenerator away from the transition end.

[0019] According to a low-temperature phase modulation structure of a GM pulse tube refrigerator provided by the present invention, the transition end includes a transition plate, and a first annular groove, a second annular groove and a third annular groove are arranged on one end surface of the transition plate at intervals;

[0020] There are a plurality of first annular grooves, each having different diameters and coaxially arranged, and one end of the pre-cooling stage regenerator is connected to the end surface of the transition plate and communicates with the first annular groove;

[0021] There are a plurality of second annular grooves, each having different diameters and coaxially arranged, and one end of the pre-cooling stage pulse tube is connected to the end surface of the transition plate and communicates with the second annular groove;

[0022] There are a plurality of third annular grooves, each of which has different diameters and is coaxially arranged.

[0023] A pre-cooling connection channel and a low-temperature phase adjustment channel are provided inside the transition plate, wherein two ends of the pre-cooling connection channel are respectively connected to the first annular groove and the second annular groove, and two ends of the low-temperature phase adjustment channel are respectively connected to the first annular groove and the third annular groove;

[0024] One end of the low-temperature stage regenerator is connected to the end surface of the transition plate away from the first annular groove and communicates with the pre-cooling connection channel and the low-temperature phase adjustment channel;

[0025] The low-temperature stage pulse tube is separated from the middle into a first part and a second part, one end of the first part is connected to the hot end deflector of the low-temperature stage pulse tube, the other end of the first part is connected to the transition plate and communicated with the third annular groove, one end of the second part is connected to the cold end deflector of the low-temperature stage pulse tube, the other end of the second part is connected to the end surface of the transition plate away from the third annular groove and communicated with the low-temperature phase adjustment channel.

[0026] The present invention provides a low-temperature phase-shifting structure for a GM pulse-tube refrigerator. By providing a transition end between the precooling stage and the cryogenic stage, the transition end further implements a low-temperature phase-shifting function similar to a "multi-path bypass." Furthermore, the transition end simultaneously functions as a precooling stage regenerator cold-end heat exchanger, a precooling stage pulse-tube cold-end flow guide, a cryogenic stage regenerator hot-end heat exchanger, a cryogenic stage pulse-tube precooling heat exchanger, and a cryogenic stage pulse-tube mid-section flow guide. Therefore, the present invention builds upon the existing room-temperature phase-shifting structure of conventional commercial liquid helium temperature-range GM pulse-tube refrigerators by further utilizing low-temperature phase-shifting, effectively improving the refrigerator's refrigeration efficiency and enhancing its structural compactness. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to 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 any creative work.

[0028] Figure 1 Schematic diagram of the low-temperature phase modulation structure of the GM pulse tube refrigerator provided by the present invention;

[0029] Figure 2 is a top view of the transition end provided by the present invention;

[0030] Figure 3 It is a cross-sectional view of the internal structure of the transition end provided by the present invention.

[0031] Reference numerals:

[0032] 100. Pressure wave generating system; 101. Compressor; 102. Rotary valve;

[0033] 200. Pulse tube precooling stage refrigeration system; 201. Precooling stage regenerator; 202. Precooling stage pulse tube; 203. Precooling stage two-way air inlet; 204. Precooling stage orifice; 205. Precooling stage air reservoir; 206. Precooling stage regenerator hot end heat exchanger; 207. Precooling stage pulse tube hot end deflector;

[0034] 300. Pulse tube cryogenic refrigeration system; 301. Cryogenic regenerator; 302. Cryogenic pulse tube; 303. Cryogenic two-way air inlet; 304. Cryogenic orifice; 305. Cryogenic gas reservoir; 306. Cryogenic pulse tube hot-end deflector; 307. Cryogenic regenerator cold-end heat exchanger; 308. Cryogenic pulse tube cold-end deflector;

[0035] 400, transition end; 401, transition plate; 402, first annular groove; 403, second annular groove; 404, third annular groove; 405, pre-cooling connecting channel; 406, low-temperature phase adjustment channel. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0037] The following combination Figure 1-Figure 3 The present invention describes a low-temperature phase modulation method and structure of a GM pulse tube refrigerator.

[0038] A low-temperature phase modulation method for a GM pulse tube refrigerator comprises the following steps:

[0039] Compression stage: The high-pressure gas delivered from the compressor 101 is divided into three parts. One part flows directly into the pre-cooling stage regenerator 201 through the pre-cooling stage regenerator hot end heat exchanger 206, one part flows through the pre-cooling stage two-way air intake 203, and one part flows through the low-temperature stage two-way air intake 303. During this process, the main flow path of the high-pressure gas is to flow into the pre-cooling stage regenerator 201.

[0040] The gas passing through the pre-cooling stage bidirectional air inlet 203 is divided into two parts. One part flows into the pre-cooling stage pulse tube 202 through the pre-cooling stage pulse tube hot end deflector 207, and the other part flows into the pre-cooling stage gas reservoir 205 through the pre-cooling stage orifice 204. During this process, the main flow path of the gas is to flow into the pre-cooling stage gas reservoir 205.

[0041] The gas passing through the low-temperature bidirectional air inlet 303 is divided into two parts. One part flows into the low-temperature pulse tube 302 through the low-temperature pulse tube hot end deflector 306, and the other part flows into the low-temperature gas reservoir 305 through the low-temperature orifice 304. During this process, the main flow path of the gas is to flow into the low-temperature gas reservoir 305.

[0042] The working gas coming from the pre-cooling stage regenerator 201 is divided into three parts. One part flows into the pre-cooling stage pulse tube 202 through the transition end 400, and then flows through the pre-cooling stage pulse tube hot end guide 207, together with the working gas from the pre-cooling stage two-way air inlet 203, through the pre-cooling stage small hole 204 and finally flows into the pre-cooling stage gas reservoir 205; the other part flows into the low-temperature stage regenerator 301 through the transition end 400, and then flows into the low-temperature stage regenerator cold end heat exchanger 307 and the low-temperature stage pulse tube cold end guide 308. The cold end of the low-temperature pulse tube 302; a part of it flows directly into the middle of the low-temperature pulse tube 302 through the transition end 400, and then together with the working fluid gas from the cold end of the low-temperature pulse tube 302, it passes through the transition end 400 to be guided and cooled, and then passes through the hot end guide 306 of the low-temperature pulse tube together with the working fluid gas from the low-temperature two-way air inlet 303 through the low-temperature small hole 304 and finally flows into the low-temperature gas reservoir 305; in this process, the mainstream path of the gas is to flow into the low-temperature regenerator 301.

[0043] Expansion stage: The gas comes out from the pre-cooling stage gas reservoir 205 and the low-temperature stage gas reservoir 305 and returns to the compressor 101 in the opposite direction of the gas path in the compression stage.

[0044] like Figure 1 As shown, a low-temperature phase modulation structure of a GM pulse tube refrigerator includes: a pressure wave generating system 100, a pulse tube pre-cooling stage refrigeration system 200, a pulse tube low-temperature stage refrigeration system 300 and a transition end 400.

[0045] The pressure wave generating system 100 includes a compressor 101 and a rotary valve 102;

[0046] The pulse tube pre-cooling stage refrigeration system 200 mainly includes a pre-cooling stage regenerator 201, a pre-cooling stage pulse tube 202, a pre-cooling stage two-way air inlet 203, a pre-cooling stage orifice 204 and a pre-cooling stage air reservoir 205;

[0047] The pulse tube low-temperature refrigeration system 300 mainly includes a low-temperature regenerator 301, a low-temperature pulse tube 302, a low-temperature two-way air inlet 303, a low-temperature orifice 304 and a low-temperature gas reservoir 305;

[0048] A transition end 400 is provided between the pulse tube pre-cooling stage refrigeration system 200 and the pulse tube low temperature stage refrigeration system 300;

[0049] The compressor 101 is connected to one end of the pre-cooling stage regenerator 201 through the rotary valve 102, and the other end of the pre-cooling stage regenerator 201 is connected to one end of the pre-cooling stage pulse tube 202 and the low-temperature stage regenerator 301 through the transition end 400.

[0050] The other end of the pre-cooling stage pulse tube 202 is connected to the pressure wave generating system 100 and the pre-cooling stage air reservoir 205 through the pre-cooling stage two-way air inlet 203 and the pre-cooling stage small hole 204, respectively. That is, the other end of the pre-cooling stage pulse tube 202 is connected to the rotary valve 102 through the pre-cooling stage two-way air inlet 203, and at the same time, the other end of the pre-cooling stage pulse tube 202 is connected to the pre-cooling stage air reservoir 205 through the pre-cooling stage small hole 204.

[0051] The other end of the low-temperature stage regenerator 301 is connected to the cold end of the low-temperature stage pulse tube 302 through a connecting pipe, and the hot end of the low-temperature stage pulse tube 302 is connected to the pressure wave generating system 100 and the low-temperature stage gas reservoir 305 through the low-temperature stage two-way air inlet 303 and the low-temperature stage small hole 304, respectively. That is, the hot end of the low-temperature stage pulse tube 302 is connected to the rotary valve 102 through the low-temperature stage two-way air inlet 303, and at the same time, the hot end of the low-temperature stage pulse tube 302 is connected to the low-temperature stage gas reservoir 305 through the low-temperature stage small hole 304.

[0052] The low-temperature stage pulse tube 302 is divided into two sections and connected by a transition end 400 . The pre-cooling stage regenerator 201 is also connected to the middle portion of the low-temperature stage pulse tube 302 through the transition end 400 .

[0053] Furthermore, the compressor 101, rotary valve 102, and precooling stage regenerator 201 are connected via a gas transmission pipeline. The precooling stage pulse tube 202, precooling stage two-way air inlet 203, precooling stage orifice 204, and precooling stage air reservoir 205 are connected via a connecting pipeline. The low-temperature stage pulse tube 302, low-temperature stage two-way air inlet 303, low-temperature stage orifice 304, and low-temperature stage air reservoir 305 are connected via a connecting pipeline. In other words, the aforementioned connections are all connected via corresponding connecting pipelines, and duplicate pipelines can be combined into a single pipeline for connection.

[0054] The pulse tube precooling stage refrigeration system 200 also includes a precooling stage regenerator hot-end heat exchanger 206 and a precooling stage pulse tube hot-end flow guide 207. The precooling stage regenerator hot-end heat exchanger 206 is located at the end of the precooling stage regenerator 201 away from the transition end 400, and the precooling stage pulse tube hot-end flow guide 207 is located at the end of the precooling stage pulse tube 202 away from the transition end 400. Theoretically, the pulse tube precooling stage refrigeration system 200 should also include a precooling stage regenerator cold-end heat exchanger and a precooling stage pulse tube cold-end flow guide. However, in this application, the functions of the precooling stage regenerator cold-end heat exchanger and the precooling stage pulse tube cold-end flow guide are both achieved through the integrated processing of the transition end 400.

[0055] The pulse tube low-temperature refrigeration system 300 further includes a low-temperature pulse tube hot-end flow guide 306, a low-temperature regenerator cold-end heat exchanger 307, and a low-temperature pulse tube cold-end flow guide 308. The low-temperature regenerator cold-end heat exchanger 307 is located at the end of the low-temperature regenerator 301 away from the transition end 400. Theoretically, the pulse tube low-temperature refrigeration system 300 should also include a low-temperature regenerator hot-end heat exchanger. However, in this application, the function of the low-temperature regenerator hot-end heat exchanger is realized by the integrated processing of the transition end 400. At the same time, in order to further improve the refrigeration efficiency of the system, the present invention also adds a low-temperature pulse tube pre-cooling heat exchanger and a low-temperature pulse tube middle flow guide. The functions of the low-temperature pulse tube pre-cooling heat exchanger and the low-temperature pulse tube middle flow guide are also realized by the integrated processing of the transition end 400.

[0056] The hot end of the low-temperature regenerator 301 and the middle position of the low-temperature pulse tube 302 are connected through the transition end 400, which plays a low-temperature phase adjustment role that is different from "low-temperature bidirectional" or "multi-path bypass".

[0057] The transition end 400 includes a transition plate 401 , and a first annular groove 402 , a second annular groove 403 and a third annular groove 404 are provided on one end surface of the transition plate 401 ;

[0058] There are several first annular grooves 402, and the diameters of the several first annular grooves 402 are different and they are coaxially arranged. One end of the pre-cooling stage regenerator 201 is connected to the end face of the transition plate 401 and is connected to the first annular groove 402; the several first annular grooves 402 serve as the cold end heat exchanger of the pre-cooling stage regenerator and the hot end heat exchanger of the low-temperature stage regenerator.

[0059] There are multiple second annular grooves 403 , each having different diameters and coaxially arranged. One end of the pre-cooling stage pulse tube 202 is connected to the end surface of the transition plate 401 and communicates with the second annular groove 403 . The multiple second annular grooves 403 serve as deflectors for the cold end of the pre-cooling stage pulse tube.

[0060] There are a plurality of third annular grooves 404 , each of which has different diameters and is coaxially arranged.

[0061] A pre-cooling connection channel 405 and a low-temperature phase adjustment channel 406 are provided inside the transition plate 401. The two ends of the pre-cooling connection channel 405 are respectively connected to the first annular groove 402 and the second annular groove 403. The above-mentioned connection method is achieved by directly punching a single hole on the transition plate 401. The shape of the small hole can be circular, or it can be processed into a square or trapezoidal groove by milling. The number of grooves is preferably 3-5. The pre-cooling connection channel 405 is respectively connected to the first annular groove 402 and the second annular groove 403, thereby connecting the pre-cooling stage regenerator 201 and the pre-cooling stage pulse tube 202, ensuring normal cooling of the pulse tube pre-cooling stage refrigeration system 200;

[0062] The two ends of the low-temperature phase adjustment channel 406 are respectively connected to the first annular groove 402 and the third annular groove 404 ; the communication method here is to open at least one ventilation hole on the transition plate 401 to achieve corresponding communication.

[0063] One end of the low-temperature stage regenerator 301 is connected to the end face of the transition plate 401 away from the first annular groove 402 and is communicated with the pre-cooling connection channel 405 and the low-temperature phase adjustment channel 406; the communication method here can be achieved by opening at least one ventilation hole, or by evenly opening more holes, and the number of holes is preferably 6-24. In addition, the ventilation holes here can be replaced with slits processed by wire cutting; this structure connects the low-temperature stage regenerator 301 and the pre-cooling stage regenerator 201, which can further enhance the heat exchange between the working gas and the transition plate 401, and additionally plays the role of a heat exchanger at the hot end of the low-temperature stage regenerator.

[0064] The low-temperature pulse tube 302 is separated from the middle into a first part and a second part. One end of the first part is connected to the low-temperature pulse tube hot end deflector 306, and the other end of the first part is connected to the transition plate 401 and connected to the third annular groove 404.

[0065] One end of the second portion is connected to the cold-end flow guide 308 of the low-temperature pulse tube, and the other end of the second portion is connected to the end face of the transition plate 401 away from the third annular groove 404 and is connected to the low-temperature phase adjustment channel 406. This connection can be achieved by providing at least one ventilation hole. The hole in the low-temperature phase adjustment channel 406 can have a variable cross-section to achieve structural asymmetry, thereby introducing direct currents of different sizes and directions. The hole shape can be circular, or it can be milled into a square or trapezoidal groove. This structure connects the hot end of the low-temperature regenerator and the middle position of the low-temperature pulse tube. It can also be connected to the middle position of the low-temperature pulse tube by capillaries of different diameters or a combination of capillaries from the outside of the transition plate 401, thereby achieving a low-temperature phase adjustment function that is different from "low-temperature bidirectional" (connecting the hot end of the low-temperature regenerator and the hot end of the low-temperature pulse tube) and "multi-path bypass" (connecting the middle position of the low-temperature regenerator and the middle position of the low-temperature pulse tube). This structure also connects the first and second parts of the low-temperature pulse tube 302, so that the several third annular grooves 404 act as a flow guide in the middle of the low-temperature pulse tube; the several third annular grooves 404 are connected to the low-temperature phase adjustment channel 406, and can also act as a pre-cooling heat exchanger for the low-temperature pulse tube, which can effectively reduce the heat transfer temperature difference of the system and further improve the cooling efficiency.

[0066] In summary, transition end 400 can further achieve a low-temperature phase adjustment effect similar to a "multi-path bypass." Furthermore, transition end 400 can simultaneously perform the functions of the cold-end heat exchanger of the pre-cooling regenerator, the cold-end flow guide of the pre-cooling pulse tube, the hot-end heat exchanger of the low-temperature regenerator, the pre-cooling heat exchanger of the low-temperature pulse tube, and the mid-port flow guide of the low-temperature pulse tube. Therefore, building upon the existing structure of a conventional commercial liquid helium temperature range GM pulse tube refrigerator, namely, the "bidirectional air inlet + small-hole gas reservoir" room-temperature phase adjustment structure, the present invention further achieves low-temperature phase adjustment through transition end 400, effectively improving the refrigerator's refrigeration efficiency. This transition end 400 also serves to divert gas flow and enhance heat exchange at multiple locations. Furthermore, the pre-cooling heat exchanger, pre-cooling flow guide, low-temperature heat exchanger, and low-temperature flow guide are at the same temperature, significantly reducing the heat transfer temperature difference between components and further improving refrigeration efficiency. The entire transition end 400 is processed as a whole, ensuring that the refrigerator structure is compact and easy to use. In addition, the three annular grooves on the transition end 400 can also be changed into circular holes or slits. The annular grooves can be formed and processed as an integral whole with the transition plate 401, or they can be processed separately and then connected to the transition plate 401 by screw fastening, welding, bonding, etc.

[0067] 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 various embodiments of the present invention.

Claims

1. A low-temperature phase modulation method for a GM pulse tube refrigerator, characterized in that: The steps include: Compression stage: The high-pressure gas delivered from the compressor is divided into three parts. One part flows directly into the pre-cooling stage regenerator, one part passes through the pre-cooling stage two-way air intake, and one part passes through the low-temperature stage two-way air intake. The working gas coming from the precooling stage regenerator is divided into three parts. One part flows into the precooling stage pulse tube through the transition end, and then passes through the precooling stage small hole together with the working gas from the precooling stage two-way air intake after passing through the precooling stage hot end guide, and finally flows into the precooling stage gas reservoir; one part flows into the low-temperature stage regenerator through the transition end, and then passes through the low-temperature stage regenerator cold end heat exchanger and the low-temperature stage pulse tube cold end guide to flow into the cold end of the low-temperature stage pulse tube; one part flows directly into the middle part of the low-temperature stage pulse tube through the transition end, and then passes through the transition end together with the working gas from the cold end of the low-temperature stage pulse tube to be guided and cooled, and then passes through the low-temperature stage hot end guide, together with the working gas from the low-temperature stage two-way air intake, through the low-temperature stage small hole, and finally flows into the low-temperature stage gas reservoir; Expansion stage: The gas comes out from the pre-cooling stage gas reservoir and the low-temperature stage gas reservoir and returns to the compressor in the opposite direction of the gas path in the compression stage.

2. A low-temperature phase modulation structure of a GM pulse tube refrigerator, characterized in that: include: a pressure wave generating system including a compressor and a rotary valve; Pulse tube pre-cooling stage refrigeration system, including pre-cooling stage regenerator, pre-cooling stage pulse tube, pre-cooling stage two-way air inlet, pre-cooling stage orifice and pre-cooling stage air reservoir; Pulse tube cryogenic refrigeration system, including cryogenic regenerator, cryogenic pulse tube, cryogenic two-way air inlet, cryogenic orifice and cryogenic gas reservoir; A transition end is provided between the pulse tube pre-cooling stage refrigeration system and the pulse tube low temperature stage refrigeration system; In which, the compressor is connected to one end of the pre-cooling stage regenerator through the rotary valve, the other end of the pre-cooling stage regenerator is connected to the pre-cooling stage pulse tube and one end of the low-temperature stage regenerator respectively through the transition end, the other end of the pre-cooling stage pulse tube is connected to the pressure wave generating system and the pre-cooling stage air reservoir respectively through the pre-cooling stage two-way air intake and the pre-cooling stage small hole; the other end of the low-temperature stage regenerator is connected to the cold end of the low-temperature stage pulse tube through a connecting pipe, and the hot end of the low-temperature stage pulse tube is connected to the pressure wave generating system and the low-temperature stage air reservoir respectively through the low-temperature stage two-way air intake and the low-temperature stage small hole; the low-temperature stage pulse tube is divided into two sections and connected by the transition end, and the pre-cooling stage regenerator is also connected to the middle part of the low-temperature stage pulse tube through the transition end.

3. The low-temperature phase modulation structure of the GM pulse tube refrigerator according to claim 2, characterized in that: The compressor, the rotary valve and the pre-cooling stage regenerator are connected through a gas transmission pipeline, the pre-cooling stage pulse tube, the pre-cooling stage two-way air intake, the pre-cooling stage small hole and the pre-cooling stage gas reservoir are connected through a connecting pipeline, and the low-temperature stage pulse tube, the low-temperature stage two-way air intake, the low-temperature stage small hole and the low-temperature stage gas reservoir are connected through a connecting pipeline.

4. The low-temperature phase modulation structure of the GM pulse tube refrigerator according to claim 2, characterized in that: The pulse tube pre-cooling stage refrigeration system also includes a pre-cooling stage regenerator hot end heat exchanger and a pre-cooling stage pulse tube hot end deflector. The pre-cooling stage regenerator hot end heat exchanger is located at the end of the pre-cooling stage regenerator away from the transition end, and the pre-cooling stage pulse tube hot end deflector is located at the end of the pre-cooling stage pulse tube away from the transition end.

5. The low-temperature phase modulation structure of the GM pulse tube refrigerator according to claim 4, characterized in that: The pulse tube low-temperature refrigeration system also includes a low-temperature pulse tube hot end deflector, a low-temperature regenerator cold end heat exchanger and a low-temperature pulse tube cold end deflector. The low-temperature regenerator cold end heat exchanger is located at the end of the low-temperature regenerator away from the transition end.

6. The low-temperature phase modulation structure of the GM pulse tube refrigerator according to claim 5, characterized in that: The transition end includes a transition plate, and a first annular groove, a second annular groove and a third annular groove are arranged on one end surface of the transition plate at intervals; There are a plurality of first annular grooves, each having different diameters and coaxially arranged, and one end of the pre-cooling stage regenerator is connected to the end surface of the transition plate and communicates with the first annular groove; There are a plurality of second annular grooves, each having different diameters and coaxially arranged, and one end of the pre-cooling stage pulse tube is connected to the end surface of the transition plate and communicates with the second annular groove; There are a plurality of third annular grooves, each of which has different diameters and is coaxially arranged. A pre-cooling connection channel and a low-temperature phase adjustment channel are provided inside the transition plate, wherein two ends of the pre-cooling connection channel are respectively connected to the first annular groove and the second annular groove, and two ends of the low-temperature phase adjustment channel are respectively connected to the first annular groove and the third annular groove; One end of the low-temperature stage regenerator is connected to the end surface of the transition plate away from the first annular groove and communicates with the pre-cooling connection channel and the low-temperature phase adjustment channel; The low-temperature stage pulse tube is separated from the middle into a first part and a second part, one end of the first part is connected to the hot end deflector of the low-temperature stage pulse tube, the other end of the first part is connected to the transition plate and communicated with the third annular groove, one end of the second part is connected to the cold end deflector of the low-temperature stage pulse tube, the other end of the second part is connected to the end surface of the transition plate away from the third annular groove and communicated with the low-temperature phase adjustment channel.

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