A vacuum cryogenic transfer tube

Abstract

The present invention discloses a vacuum cryogenic transfer pipe, which includes a cryogenic transition pipe, a top head structure, an intermediate bellows structure, a transition flange pipe, an insulating flange, and a bottom vacuum cylinder. The structure of the present invention is simple, and the installation and disassembly are convenient. Compared with other cryogenic infusion pipelines, it has strong vacuum tightness, can be connected to a vacuum chamber, thus having an ultra-high vacuum degree, and can provide strong heat insulation performance to meet the cryogenic liquid transfer with small flow rate and long time; it is convenient to connect and can be directly docked with an infusion pipe; it has strong insulation and can isolate the potential difference of the liquid supply device; it adopts a segmented structure design, which is convenient for operation and maintenance, and can be quickly disassembled, assembled and maintained according to the working needs.

Description

Technical Field

[0001] The present invention relates to the field of low-temperature fluid medium transmission technology and vacuum machinery, and in particular to a vacuum low-temperature transmission tube. Background Art

[0002] Nuclear fusion research requires an ultra-high clean vacuum environment, and cryopumps are essential for maintaining this ultra-high vacuum environment in experimental equipment. Cryopumps operate in conjunction with cryogenic media, such as liquid nitrogen (boiling point 77K at atmospheric pressure) and liquid helium (boiling point 4.2K at atmospheric pressure). Because the cryogenic media constantly absorbs heat from the outside world and eventually evaporates and depletes, a cryogenic transfer device (cryogenic transfer pipe) is required to circulate and recycle the cryogenic media to the cryopump during operation to save costs.

[0003] The transportation of cryogenic liquids is an important component in achieving a cryogenic refrigeration cycle and providing a cryogenic environment. It is widely used in scientific and technological production fields such as cryogenic pumps, air separation, natural gas liquefaction, rare gas development, and low-temperature superconductivity research. A cryogenic transmission pipe is essentially a pipe with good thermal insulation capabilities. It allows a cryogenic medium to flow through the pipe. An insulating layer (such as a vacuum layer) is provided between the outer wall of the pipe and the inner wall of the pipe through which the medium flows, thereby maintaining a low temperature of the medium and preventing it from absorbing too much heat and vaporizing. Currently, cryogenic transmission pipes mainly adopt a double-layer infusion pipe structure. The outer pipe is a vacuum isolation pipe. The outside of the pipe is in the atmospheric environment while the inside of the pipe is in a vacuum state. The inner pipe is a cryogenic liquid transmission pipe. The two are fixed by a shielded pipe bracket made of low thermal conductivity material.

[0004] Nuclear fusion experimental devices generally have electrical equipment, which will cause the ground potential to rise suddenly when working. Common low-temperature transmission pipelines are mostly made of metal materials with high electrical conductivity. They cannot isolate the potential on both sides of the low-temperature fluid transmission pipes, so the rise in ground potential affects the normal operation of the low-temperature cooling production system.

[0005] Common cryogenic transmission pipelines lack strong thermal insulation, making them inadequate for low-flow, long-duration cryogenic liquid transmission. Due to the low flow rate required, a significant portion of the cryogenic liquid vaporizes before reaching the target area, resulting in low cooling efficiency. Furthermore, this vaporization creates bubbles, impacting the stable operation of cryogenic equipment. These issues become more pronounced with longer transmission pipelines.

[0006] In addition, in order to ensure thermal insulation, the outer layer of common low-temperature transmission pipes is generally an integral pipe. Once the internal pipe fails, maintenance must destroy the outer pipe, which is very difficult to operate.

[0007] When the inner tube of a cryogenic transmission pipe cools, it contracts, generating significant thermal stress between it and the outer tube. A bellows compensator is typically added to compensate for the length difference between the inner and outer tubes after cooling. However, the bellows structure of the inner tube can cause flow instability, vibration, and noise. Furthermore, the bellows structure increases welding and leak detection workload, and the presence of multiple welds can reduce the reliability and durability of the cryogenic transmission pipe. Summary of the Invention

[0008] The purpose of this invention is to address the shortcomings of existing technologies by providing a vacuum cryogenic transfer tube to meet the needs of circulating cryogenic media in cryogenic devices used in nuclear fusion research. It features strong vacuum sealing, allowing connection to a vacuum chamber to achieve an ultra-high vacuum and reduce thermal conductivity. It also possesses strong thermal insulation, enabling low-flow, long-term cryogenic liquid transfer. It is easily connected and can be directly connected to a liquid infusion tube. Its strong insulation properties can isolate potential differences at the liquid supply point. It can be operated in sections for easy maintenance, allowing for quick disassembly and repair as needed.

[0009] The present invention is achieved through the following technical solutions:

[0010] A vacuum low-temperature transmission tube comprises a low-temperature transition tube, a top end cap structure, an intermediate bellows structure, a transition flange tube, an insulating flange, and a bottom vacuum cylinder. The low-temperature transition tube comprises a clamping ring nut, a transition tube male head, a transition tube, a transition tube joint, and an electrical isolation portion. The clamping ring nut is a copper nut, the top opening of the clamping ring nut is small and matches the caliber of an external infusion tube, the bottom opening is slightly larger and matches the transition tube male head and the sealing ring, and a Wilson sealing structure is adopted internally. The transition tube male head is welded to the top of the transition tube, and the tail of the transition tube is welded to the transition tube joint, so that the transition tube forms a closed cavity. The electrical isolation portion at the bottom end of the transition tube is metal at both ends and ceramic in the middle. The top of the electrical isolation portion is welded to the transition tube joint, and the bottom end is directly welded to the low-temperature infusion tube. The metal infusion tube has a matching bend at the turning point of the bottom vacuum cylinder. Except for the fixed connection at the top, the other parts of the entire low-temperature transition tube, including the transition tube, the transition tube joint, the electrical isolation portion, and the tail metal infusion tube, are all in a suspended state.

[0011] Furthermore, the top head structure is composed of a head and a top plate, wherein the top of the head is a clamping flange with a larger opening in the middle for inserting the low-temperature transition pipe, and through holes are opened around it for installing fastening bolts; the middle of the head is a cylindrical part, with a connecting flange connected to the bottom, and a sealing groove is opened in the connecting flange, and the connecting flange is connected to the middle bellows structure; the top plate has four through holes for welding the low-temperature transition pipe, a sealing groove is opened on the outer ring, and threaded holes are opened around it, and the threaded holes are located in the sealing groove.

[0012] Furthermore, the intermediate corrugated pipe structure consists of an adjusting flange, a connecting pipe section, a corrugated pipe, a fixing rod, and a locking nut. First, both ends of the corrugated pipe are welded to the connecting pipe, and then the connecting pipe is welded to the adjusting flange to form an integral body. Four ears with fixing holes extend outward from the outer side of the adjusting flange, and the fixing rods with threads at both ends pass through the ears. The intermediate corrugated pipe structure is adjusted through the locking nut, so as to achieve a certain deflection of the vertical part of the vacuum low-temperature transmission pipe. A sealing groove and bolt holes are provided on the end face of the adjusting flange. The adjusting flange includes an upper adjusting flange and a lower adjusting flange. The upper adjusting flange is connected to the top head structure, and the lower adjusting flange is connected to the transition flange pipe and is connected by fastening bolts.

[0013] Furthermore, for the transition flange pipe, the upper and lower ends are connecting flanges, and sealing grooves are provided on the end faces of the connecting flanges. The middle part is a connecting well pipe. The transition flange pipe plays a role in transitional connection, which is beneficial for disassembly, installation, and maintenance.

[0014] Furthermore, both sides of the insulating flange are smooth. One side is connected to the transition flange pipe, and the other side is connected to the bottom vacuum cylinder body. It is fastened through bolts and sealing rings to seal the vacuum. The insulating flange and bolts are made of insulating materials, which play a role in isolating the potential.

[0015] Furthermore, the bottom vacuum cylinder body is a tee structure. The bottom is a straight barrel structure, and the two ends of the straight barrel structure are interface flanges. One end of the interface flange is connected to the blind plate through bolts to form a vacuum seal. The blind plate is removed for maintenance of the transmission pipe inside the cylinder body. The other interface flange at the other end of the straight barrel structure is connected to the main vacuum chamber through bolts. The top of the bottom vacuum cylinder body is a flared flange, and the flared flange is welded to the flared well pipe, and the tail of the flared well pipe is connected to the straight barrel. A sealing groove is provided on the end face of the flared flange, which is connected to the insulating flange. The insulating flange and the transition flange pipe are directly connected through fastening bolts, thus forming an integral structure. Both the fastening bolts and the insulating flange are made of insulating materials, and together with the ceramic insulating part of the low-temperature transition pipe, the potential isolation between the bottom and the upper end of the vacuum low-temperature transmission pipe is achieved.

[0016] Furthermore, the low-temperature transition pipe is welded to the metal infusion pipe at the bottom, and its surface is wrapped with multiple layers of heat insulation layers.

[0017] Furthermore, the vacuum low-temperature transmission pipe adopts a segmented structure, which is convenient for disassembly and maintenance.

[0018] Furthermore, when the external metal infusion pipe is inserted from the top of the retaining ring nut, a sealing ring is sleeved on the external metal infusion pipe. Then, as the retaining ring nut and the male head of the transition pipe are continuously tightened, the sealing ring is squeezed and deformed, thus fixing and sealing the metal infusion pipe.

[0019] Furthermore, a heat insulation layer is wrapped on the surface of the low-temperature transition pipe, which can further reduce heat conduction and enhance low-temperature transmission performance.

[0020] The outer tube of the vacuum low-temperature transfer tube adopts a segmented structure design, which is convenient for installation and disassembly. Without damaging the structure of the outer tube, the inner tube structure can be maintained, and the maintenance performance is stronger compared with traditional low-temperature transfer tubes. The corrugated pipe part in the segmented structure enables the low-temperature transfer tube to adjust the angular position of the transfer tube according to the installation needs, with strong applicability.

[0021] The size specifications of the vacuum low-temperature transfer tube of the present invention can be customized according to user needs, and the material of the transfer tube can also be selected according to needs, with strong applicability. The number of internal transfer tubes can be customized according to needs, and the simultaneous transfer of multiple low-temperature liquids can be realized. The outer tube of the vacuum low-temperature transfer tube adopts a segmented structure design, which is convenient for installation and disassembly and facilitates the maintenance of the internal transfer tube. The corrugated pipe part in the segmented structure enables the low-temperature transfer tube to adjust the angular position of the transfer tube according to the installation needs, with strong applicability. Compared with other low-temperature transfer tubes, the design of the adiabatic layer connected to the main vacuum chamber and wrapped inside the low-temperature transfer tube further enhances the low-temperature transfer performance. In addition, the materials of the insulating flange and the electrically isolated part of the low-temperature transition tube can be selected according to the user's needs and can be applied to various potential isolation requirement environments.

[0022] Furthermore, the advantages of the present invention are:

[0023] (1) The structure of the present invention is simple, and the installation and disassembly are convenient. Compared with other low-temperature transfer tubes, the outer tube adopts a segmented structure design. Without damaging the structure of the outer tube, the inner tube structure can be maintained, and the maintenance performance is strong. The corrugated pipe part in the segmented structure enables the low-temperature transfer tube to adjust the angular position of the transfer tube according to the installation needs, with strong applicability. And it can be disassembled and used repeatedly, with stable performance, and still can maintain the low-temperature transfer performance after being disassembled multiple times.

[0024] (2) The present invention adopts the design of the adiabatic layer connected to the main vacuum chamber and wrapped inside the low-temperature transfer tube, which further enhances the low-temperature transfer performance.

[0025] (3) The outer tube of the present invention adopts a segmented structure design in cooperation with the insulation design of the inner tube, enabling it to work in environments with different potential differences. In addition, the suspension of the internal low-temperature transition tube and the bending design of the tail metal infusion tube can play a role in compensating for low-temperature deformation, reducing the thermal stress with the outer tube, and enhancing the overall sealing performance and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is the assembly drawing of the present invention;

[0027] Figure 2 is the cross-sectional view of the present invention;

[0028] Figure 3 The following are the assembly drawing and cross-sectional view of the low-temperature transition tube;

[0029] Figure 4 It is the assembly drawing and cross-sectional view of the top head structure;

[0030] Figure 5 This is a partial enlarged view of the top seal of the top head structure;

[0031] Figure 6 This is a partial enlarged view of the bottom seal of the top head structure;

[0032] Figure 7 It is the structural diagram and cross-sectional view of the intermediate bellows structure;

[0033] Figure 8 It is the structural diagram and cross-sectional view of the transition flange pipe;

[0034] Figure 9 It is the structural diagram and cross-sectional view of the insulating flange;

[0035] Figure 10 It is the structural diagram and cross-sectional view of the bottom vacuum cylinder.

[0036] The meanings of the reference numerals in the figure are as follows: 1 is a low-temperature transition pipe, 2 is a top head structure, 3 is an intermediate bellows structure, 4 is a transition flange pipe, 5 is an insulating flange, 6 is a bottom vacuum cylinder, 7 is a clamping nut, 8 is a transition pipe male head, 9 is a transition pipe, 10 is a transition pipe joint, 11 is an electrical isolation part, 12 is a head, 13 is a top plate, 14 is a top sealing ring of the top head structure, 15 is a bottom sealing ring of the top head structure, 16 is an adjusting flange, 17 is a connecting pipe, 18 is a bellows, 19 is a fixing rod, 20 is a locking nut, 21 is a first sealing groove, 22 is a connecting flange, 23 is a connecting well pipe, 24 is a second sealing groove, 25 is a flared flange, 26 is a flared well pipe, 27 is a straight tube structure, 28 is a sealing ring, 29 is a blind flange, and 30 is an interface flange. DETAILED DESCRIPTION

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0038] like Figures 1-10As shown in the figure, the vacuum low-temperature transfer tube of the present invention includes a low-temperature transition tube 1, a top head structure 2, an intermediate bellows structure 3, a transition flange tube 4, an insulating flange 5, and a bottom vacuum cylinder 6. The low-temperature transition tube 1 passes through the reserved opening at the top of the top head structure 2 and is welded to the top head structure 2. The top head structure 2 is connected to the adjusting flange 16 at the upper end of the intermediate bellows structure 3 by bolts. The adjusting flange 16 at the lower end of the intermediate bellows structure 3 is connected to the connecting flange 22 at the upper end of the transition flange tube 4 by bolts. The connecting flange 22 at the lower end of the transition flange tube 4 is connected to the flared flange 25 at the top end of the bottom vacuum cylinder 6 through the insulating flange 5 by insulating bolts, thus forming an integral cavity. The low-temperature transition tube 1 passes through the top head structure 2 and the intermediate bellows structure 3 until the transition flange tube 4. The metal infusion tube welded to the low-temperature transition tube 1 passes through the transition flange tube 4 and the insulating flange 5, and then enters the low-temperature device in the vacuum chamber through the docking port of the bottom vacuum cylinder 6 and the vacuum chamber.

[0039] The low-temperature transition tube 1 described above includes a snap ring nut 7, a transition tube male head 8, a transition tube 9, a transition tube joint 10, and an electrical isolation part 11. Among them, the snap ring nut 7 is a copper nut. The opening at the top of the nut is smaller and matches the diameter of the infusion tube. The opening at the bottom is slightly larger and cooperates with the transition tube male head 8 and the sealing ring. The internal Wilson sealing structure is adopted. When the external metal infusion tube is inserted from the top of the snap ring nut 7, a sealing ring is sleeved on the external metal infusion tube. Then, as the snap ring nut 7 and the transition tube male head 8 are continuously tightened, the sealing ring is squeezed and deformed, thereby fixing and sealing the infusion tube. The transition tube male head 8 is welded to the top of the transition tube 9. The inner wall of the transition tube 9 is smooth and has a suitable size, which can closely adhere to the external metal infusion tube. The tail of the transition tube 9 is welded to the transition tube joint 10, making the transition tube 9 form a closed cavity. The two ends of the electrical isolation part 11 at the bottom end of the transition tube 9 are made of metal, and the middle is made of ceramic, which can well isolate the potential difference between the infusion part and the main vacuum chamber. The top end of the electrical isolation part 11 is welded to the transition tube joint 10, and the bottom end is directly welded to the low-temperature infusion tube. The metal infusion tube has a matching bend at the turning point of the cylinder. Except for the top fixed connection, other parts of the entire low-temperature transition tube 1, including the transition tube 9, the transition tube joint 10, the electrical isolation part 11, and the metal infusion tube at the tail, are in a suspended state. Such a structural design can not only reduce heat conduction but also play a certain role in compensating for low-temperature deformation and reducing the thermal stress with the outer tube. In addition, a heat insulation layer is wrapped on the surface of the low-temperature transition tube 1, which can further reduce heat conduction and enhance low-temperature transmission.

[0040] The described top head structure 2 includes a head 12 and a top plate 13. The top of the head 12 is a compression flange with a relatively large opening in the middle for passing through the low-temperature transition pipe 1, and through holes are opened around it for installing fastening bolts; the middle part of the head 12 is a cylindrical part, and the bottom is connected with a connecting flange which has a sealing groove. The connecting flange is butted with the middle bellows structure 3, and the bottom sealing ring 15 of the top head structure is used to seal the vacuum in the cavity; four through holes are opened in the top plate 13 for welding the low-temperature transition pipe 1, a sealing groove is opened on the outer ring, and threaded holes are opened around it, and the threaded holes are located in the sealing groove. In this way, the bolts pass through the through holes at the top of the head 12 and enter the threaded holes of the top plate. As the bolts are tightened, the inner surface of the top flange of the head 12 fits with the upper surface of the top plate 13, tightly pressing the top sealing ring 14 of the top head structure in the sealing groove of the top plate 13, thus sealing the vacuum.

[0041] The described middle bellows structure 3 is composed of parts such as an adjusting flange 16, a connecting pipe 17, a bellows 18, a fixing rod 19, and a locking nut 20. First, both ends of the bellows 18 are welded to the connecting pipe 17, and the connecting pipe 17 is then welded to the adjusting flange 16 to form a whole. Four ears with fixing holes extend outwards from the outside of the adjusting flange 16, and the fixing rod 19 with threads at both ends passes through the ears, and the middle bellows structure 3 is adjusted through the locking nut 20, so as to realize a certain deflection of the vertical part of the vacuum low-temperature transmission pipe. The end face of the adjusting flange 16 is provided with a sealing groove and bolt holes, including an upper adjusting flange and a lower adjusting flange. The upper adjusting flange is connected to the top head structure 2, and the lower adjusting flange is connected to the transition flange pipe 4, and they are connected by fastening bolts.

[0042] For the described transition flange pipe 4, the upper and lower ends are connecting flanges 22. The end faces of the upper and lower connecting flanges 22 are provided with a first sealing groove 21 and a second sealing groove 24. Both the first sealing groove 21 and the second sealing groove 24 are rectangular sealing grooves. The middle is a connecting well pipe 23, and the upper and lower connecting flanges 22 are directly welded to the connecting well pipe 23. The transition flange pipe 4 plays a role in transitional connection, which is more conducive to disassembly, installation and maintenance.

[0043] The described insulating flange 5 has smooth surfaces on both sides. One side is connected to the transition flange pipe 4, and the other side is connected to the bottom vacuum cylinder 6 of the tee structure. It is fastened through bolts and sealing rings to seal the vacuum. It should be emphasized that the insulating flange 5 is made of insulating material, and the connecting bolts are also made of insulating material, which plays a role in isolating the potential.

[0044] The bottom vacuum cylinder 6 is a tee structure. The bottom is a straight cylinder structure 27. At both ends of the straight cylinder structure 27 are interface flanges 30. The sealing ring 28 is an O-ring, which is arranged in the sealing groove on the end face of the interface flange 30. The blind flange 29 is connected to one end of the interface flange 30 and the sealing ring 28 through bolts to form a vacuum seal. When necessary, the blind flange 29 can be removed to repair the internal transfer pipe of the bottom vacuum cylinder 6. The other flange interface of the straight cylinder structure 27 can be connected to the main vacuum chamber through bolts, so as to obtain a higher vacuum degree and reduce heat transfer. The top of the bottom vacuum cylinder 6 is a flared flange 25, which is welded to the flared well pipe 26. The tail of the flared well pipe 26 is connected to the straight cylinder structure 27. A sealing groove is opened on the end face of the flared flange 25, which is connected to the insulating flange 5. The insulating flange 5 and the transition flange pipe 4 are directly connected through fastening bolts to form an integral structure. The fastening bolts and the insulating flange 5 are both made of insulating materials, and together with the ceramic insulating part of the low-temperature transition pipe, the potential isolation between the bottom and the upper end of the vacuum low-temperature transfer pipe is realized.

[0045] In this example, the cryogenic liquids to be transported are liquid nitrogen and liquid helium. Therefore, there are four circulation pipelines, and there are four cryogenic transition pipes 1 in the vacuum cryogenic transmission pipe, with two inlets and two returns, forming the liquid nitrogen and liquid helium circuits. The sealing ring material is fluororubber, the material of the insulating flange 5 is G10, the material of the insulating bolt is polytetrafluoroethylene, the middle insulating part of the electrical isolation part 11 is ceramic material, and the main material of the cryogenic transmission pipe is 304 stainless steel. First, the male head 8 of the transition pipe is welded to the top of the transition pipe 9, the snap ring nut 7 is tightened on the male head 8 of the transition pipe, and the transition pipe joint 10 is welded to the tail of the transition pipe 9, so that the transition pipe forms a closed cavity. The bottom end of the transition pipe joint 10 is welded to the electrical isolation part 11. The electrical isolation part 11 adopts a structural design with ceramic in the middle and metal at both ends, so as to realize the potential isolation treatment between the upper and lower parts of the cryogenic transition pipe 1. The other end of the electrical isolation part 11 is welded to the metal infusion pipe, thus forming the entire structure of the cryogenic transition pipe 1. The metal infusion pipe leads directly to the cryogenic device inside the vacuum chamber and is bent at the turning point of the cylinder body to form a buffer structure for cryogenic deformation. The upper and lower surfaces of the cryogenic transition pipe 1 are wrapped with a heat insulation layer, which further reduces heat conduction and enhances cryogenic transmission. The head of the cryogenic transition pipe 1 is welded to the top plate 13 of the top head structure 2, passes through the head 12, and is suspended inside the pipe cylinder body as a whole. Secondly, the inner surface of the top flange of the top head structure 2 fits with the upper surface of the top plate 13. The bolt passes through the through hole at the top of the head 12 and enters the threaded hole of the top plate 13. As the bolt is tightened, the top flange of the top head structure 2 tightly presses the sealing ring in the sealing groove of the top plate 13, thus sealing the top vacuum of the transmission pipe. The bottom flange of the head 12 fits with the upper adjusting flange end face of the middle bellows structure 3. As the bolt is tightened, the two flange end faces continuously squeeze the sealing ring in the sealing groove, thus sealing the vacuum. The lower adjusting flange end face is connected to the upper end face of the transition flange pipe 4. The middle part of the middle bellows structure 3 is a bellows structure, which can be bent and twisted. By adjusting the lock nut 20 of the screw in the adjusting flange ear, the entire middle bellows structure 3 is fixed and shaped, so as to realize the deflection of the vertical part of the vacuum cryogenic transmission pipe. Again, the lower end face of the transition flange pipe 4 is connected to the upper end face of the insulating flange 5, and the lower end face of the insulating flange 5 is connected to the end face of the flared flange 25 at the top of the bottom vacuum cylinder 6. Sealing grooves are provided on the end faces of the transition flange pipe 4 and the flared flange 25, and sealing rings are placed in the sealing grooves. The fastening bolt passes through the lower flange end face of the transition flange pipe 4, the insulating flange 5 and the flared flange 25. As the bolt is tightened, the end face of the flared flange 25 and the end face of the insulating flange 5 continuously squeeze the sealing ring, thus realizing the sealing of the contact surfaces of the transition flange pipe 4, the insulating flange 5 and the bottom vacuum cylinder 6. The bottom of the bottom vacuum cylinder 6 is a straight cylinder, and one end is sealed with a blind flange 29, thus forming a vacuum sealing structure for the outer pipe part of the entire cryogenic transmission pipe. The other end of the straight cylinder is connected to the vacuum chamber through the interface flange 30, so as to obtain a high vacuum, reduce the heat conduction of the cryogenic transition pipe, and enhance cryogenic transmission.The cryogenic medium inside the external metal infusion tube also enters the cryogenic device inside the vacuum chamber through this. In addition, the fastening bolts passing through the lower flange end face of the transition flange tube 4, the insulating flange 5, and the cylinder body flared flange 25 are made of insulating materials, thus achieving the potential isolation between the upper and lower parts of the outer tube of the cryogenic transfer tube. Cooperating with the ceramic insulating part of the cryogenic transition tube 1, the potential isolation between the bottom and the upper end of the vacuum cryogenic transfer tube is thus achieved.

[0046] When the vacuum cryogenic transfer tube is working, first, loosen the snap ring nut 7 at the top of the cryogenic transition tube 1, insert the external metal infusion tube into the inside of the cryogenic transition tube 1 from the top until it reaches the tail of the cryogenic transition tube 1; then tighten the snap ring nut 7 at the top of the cryogenic transition tube 1. The inside of the snap ring nut 7 adopts a structure similar to the Wilson seal. As the snap ring nut 7 and the transition tube male head 8 are continuously tightened, the sealing ring is extruded and deformed, thus fixing and sealing the infusion tube. The main vacuum chamber starts to be evacuated. When the main vacuum chamber reaches a certain vacuum degree, that is, when the cryogenic transfer tube reaches the corresponding vacuum degree. At this time, the cryogenic transfer tube enters the normal working state. The cryogenic liquid enters the cryogenic device inside the main vacuum chamber through the cryogenic transfer tube. After completing the circulation in the cryogenic device, it then returns to the liquid supply place through the cryogenic transfer tube. With the continuous transportation and circulation of the cryogenic liquid, the cryogenic device starts to work, the vacuum state of the main vacuum chamber becomes better and better, and the transfer performance of the vacuum cryogenic transfer tube also becomes better and better.

[0047] In the actual use process, the vacuum cryogenic transfer tube can not only transport liquid nitrogen and liquid helium, but also other cryogenic liquids. The size specifications of the transfer tube can be selected according to one's own needs. The number of cryogenic transition tubes, the insulating material, and the sealing ring material can also be selected according to the use environment. It has a simple structure, is convenient for installation and disassembly. The outer tube adopts a segmented structure design, and the inner tube structure can be maintained without damaging the outer tube structure, with strong maintenance performance. The bellows part in the segmented structure enables the cryogenic transfer tube to adjust the angular position of the transfer tube according to the installation needs, with strong applicability. And it can be disassembled and used repeatedly, with stable performance, and still can maintain the cryogenic transfer performance after being disassembled many times. It works safely, stably and reliably, has good vacuum tightness, and can provide strong support for experiments.

[0048] Although the present invention takes liquid nitrogen and liquid helium as the conveying medium and takes connecting the liquid supply end and the main vacuum chamber as an example, it is not limited to the conveyance of liquid nitrogen and liquid helium, and is equally applicable to the conveyance of other cryogenic liquids or even other liquids that need to be isolated from the external environment. The above are only the embodiments of the present invention, and do not limit the scope of the present invention accordingly. Any implementation or change that does not depart from the present invention is included within the protection scope of the present invention.

Claims

1. A vacuum cryogenic transfer tube, characterized in that: It includes a low-temperature transition pipe, a top head structure, an intermediate bellows structure, a transition flange pipe, an insulating flange, and a bottom vacuum cylinder; the top head structure is connected to the adjusting flange at the upper end of the intermediate bellows structure by bolts, the adjusting flange at the lower end of the intermediate bellows structure is connected to the connecting flange at the upper end of the transition flange pipe by bolts, and the connecting flange at the lower end of the transition flange pipe is connected to the flared flange at the top end of the bottom vacuum cylinder through insulating bolts passing through the insulating flange, forming an integral cavity; the low-temperature transition pipe passes through the top head structure and the intermediate bellows structure until the transition flange pipe, and the metal infusion pipe welded to the low-temperature transition pipe passes through the transition flange pipe and the insulating flange, and then enters the low-temperature device in the main vacuum chamber through the docking port of the bottom vacuum cylinder and the main vacuum chamber; The low-temperature transition pipe mentioned above includes a snap ring nut, a transition pipe male head, a transition pipe, a transition pipe joint, and an electrical isolation part; among them, the snap ring nut is a copper nut, the top opening of the snap ring nut is small, the snap ring nut matches the diameter of the external metal liquid delivery pipe, the bottom opening of the snap ring nut is slightly larger than the transition pipe male head and matches the sealing ring of the transition pipe male head, and the Wilson sealing structure is adopted inside the snap ring nut; the transition pipe male head is welded to the top of the transition pipe; the tail of the transition pipe is welded to the transition pipe joint to form a closed cavity for the transition pipe; both ends of the electrical isolation part at the bottom end of the low-temperature transition pipe are metal and the middle is ceramic, the top end of the electrical isolation part is welded to the transition pipe joint, and the bottom end is directly welded to the metal infusion pipe, and the metal infusion pipe has a matching bend at the turning point of the bottom vacuum cylinder; except for the top fixed connection, other parts of the low-temperature transition pipe are in a suspended state, and the other parts include the transition pipe, the transition pipe joint, and the electrical isolation part; the metal infusion pipe is in a suspended state.

2. The vacuum cryogenic transfer tube according to claim 1, wherein: The top head structure mentioned above consists of a head and a top plate. Among them, the top of the head is a compression flange, there is an opening in the middle of the compression flange for passing through the low-temperature transition pipe, and through holes are opened around the compression flange for installing fastening bolts; the middle of the head is a cylindrical part, and a connecting flange is connected at the bottom, and a sealing groove is opened on the connecting flange, and the connecting flange is butted against the intermediate bellows structure; four through holes are opened on the top plate for welding the low-temperature transition pipe, a sealing groove is opened on the outer circle, and threaded holes are opened around; the inner surface of the top flange of the head fits with the upper surface of the top plate.

3. A vacuum cryogenic transfer tube according to claim 1, characterized in that: The intermediate bellows structure mentioned above consists of an adjusting flange, a connecting pipe part, a bellows, a fixing rod, and a locking nut. First, both ends of the bellows are welded to the connecting pipe part, and the connecting pipe part is then welded to the adjusting flange to form an integral body; four ears with fixing holes extend out from the outside of the adjusting flange, and the fixing rod with threads at both ends passes through the ears, and the intermediate bellows structure is adjusted through the locking nut, so as to realize the deflection of the vertical part of the vacuum low-temperature transmission pipe; a sealing groove and bolt holes are opened on the end face of the adjusting flange, and the adjusting flange includes an upper adjusting flange and a lower adjusting flange; the upper adjusting flange is connected to the top head structure, and the lower adjusting flange is connected to the transition flange pipe.

4. The vacuum cryogenic transfer tube according to claim 3, characterized in that: The upper and lower ends of the transitional flange pipe are connecting flanges. The end faces of the connecting flanges are provided with a first sealing groove and a second sealing groove. The middle of the transitional flange pipe is a connecting well pipe. The transitional flange pipe plays a role in transitional connection, which is beneficial to disassembly, installation and maintenance.

5. A vacuum cryogenic transfer tube according to claim 1, characterized in that: The bottom vacuum cylinder is a tee structure. The bottom is a straight cylinder structure. The two ends of the straight cylinder structure are interface flanges. One interface flange is connected to a blind plate by bolts to form a vacuum seal. By removing the blind plate, the internal metal infusion pipe of the cylinder can be repaired. The other interface flange at the end of the straight cylinder structure is connected to the main vacuum chamber by bolts. The top of the bottom vacuum cylinder is a flared flange, which is welded to the flared well pipe, and the tail of the flared well pipe is connected to the straight cylinder. The end face of the flared flange is provided with a sealing groove, which is connected to the insulating flange. The insulating flange and the transitional flange pipe are directly connected by insulating bolts, thus forming an integral structure. The insulating bolts and the insulating flange are both made of insulating materials, which cooperate with the ceramic insulating part of the low-temperature transition pipe to realize the potential isolation between the bottom and the upper end of the vacuum low-temperature transmission pipe.

6. The vacuum cryogenic transfer tube according to claim 1, wherein: When the external metal liquid delivery pipe is inserted from the top of the snap ring nut, a sealing ring is sleeved on the external metal liquid delivery pipe. Then, as the snap ring nut and the male head of the transition pipe are continuously tightened, the sealing ring is squeezed and deformed, so as to fixedly seal the external metal liquid delivery pipe.

7. A vacuum cryogenic transfer tube according to claim 1, characterized in that: The surface of the low-temperature transition pipe is wrapped with a heat insulation layer.

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