A liquid helium stop valve with corrugated tube vacuum jacket

Abstract

This invention relates to the field of valves, and in particular to a liquid helium shut-off valve with a bellows vacuum jacket. An inner bellows is provided between the valve stem and the valve cover, with one end abutting the valve cover and the other end extending into the valve body. A bellows vacuum connector perpendicular to the valve stem axis is provided on the valve cover, penetrating the side wall of the valve cover. A vacuum environment is created inside the inner bellows through the bellows vacuum connector. A low-temperature epoxy fiberglass filling ring is filled between the inner bellows and the valve body. A winding layer is provided on the outer wall of the valve body, including an insulating layer and a heat radiation protection layer. A vacuum jacket is also provided on the outer wall of the valve body, fixedly connected to the valve body via an expansion joint. A vacuum evacuation connector is provided on the side wall of the vacuum jacket, creating a vacuum environment inside the jacket through the vacuum evacuation connector. The vacuum inner bellows and the low-temperature epoxy fiberglass filling ring reduce heat conduction at the valve stem-valve cover mating point, while the insulating layer, heat radiation protection layer, and vacuum jacket reduce heat radiation from the valve body, resulting in good cold insulation.

Description

Technical Field

[0001] This invention relates to the field of valves, and in particular to a liquid helium shut-off valve with a bellows vacuum jacket. Background Technology

[0002] A cryogenic shut-off valve is a valve in which the closing element (valve disc) moves along the centerline of the valve seat. Due to this movement of the valve disc, the change in the valve seat opening is directly proportional to the valve disc stroke. Because this type of valve has a relatively short stem opening or closing stroke and a highly reliable shut-off function, and because the change in the valve seat opening is directly proportional to the valve disc stroke, it is very suitable for flow regulation. Therefore, this type of valve is ideal for shut-off, regulation, and throttling applications.

[0003] In ultra-low temperature environments (temperature ≤ -101℃), ultra-low temperature shut-off valves are required when transferring ultra-low temperature media. Ultra-low temperature shut-off valves are shut-off devices used in low-temperature operating conditions and play an important role in industrial fields where the operating temperature is generally below -101℃. The operating conditions of ultra-low temperature shut-off valves are harsh, therefore, the requirements for valve sealing performance are extremely high.

[0004] A search revealed Chinese patent CN211852951U, which discloses a cryogenic shut-off valve comprising a valve body, a valve disc, a valve stem, a valve cover, and a handwheel. The valve body is internally divided into a first chamber and a second chamber by the valve disc. The valve cover is bolted to the valve body, and a gasket is provided at the connection between the valve cover and the valve body. Packing material is fixedly embedded in the interior of the valve cover at the end furthest from the valve body. This cryogenic shut-off valve, by providing a gasket at the connection between the valve cover and the valve body, and by placing packing material inside the valve cover on the valve stem, seals the connection between the valve body and the valve cover. The valve stem is installed inside the packing material, thereby improving the sealing performance of the valve stem within the valve cover. This effectively prevents leakage of the medium from the gaps between the valve body and the valve cover, and between the valve stem and the valve cover, thus solving the leakage problem of traditional cryogenic valves when transporting cryogenic media.

[0005] However, the inventors further discovered that the solution still has the following problems: when the external temperature is greater than the internal temperature of the valve body, heat is conducted into the valve body through the valve body wall and affects the medium. Since liquid helium is a low-temperature medium, a high-temperature environment will affect the chemical properties of liquid helium. Therefore, the inside of the shut-off valve needs to maintain a low-temperature environment. The shut-off valve with this structure cannot effectively prevent the heat exchange between the inside and outside of the valve and cannot maintain the low-temperature environment inside the valve. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings and deficiencies of the existing technology and to provide a liquid helium shut-off valve with a bellows vacuum jacket.

[0007] The technical solution adopted in this invention is as follows: A liquid helium shut-off valve with a bellows vacuum jacket includes a valve body, a valve stem, and a valve cover. The valve body is provided with a valve seat inside. The lower end of the valve stem is provided with a valve disc. The valve stem extends into the valve body and cooperates with the valve seat through the valve disc. The interior of the valve body is divided into an inlet channel and an outlet channel through the cooperation of the valve disc and the valve seat. The valve cover is fixedly connected to the valve body by bolts.

[0008] An inner bellows is provided between the valve stem and the valve cover. One end of the inner bellows is fixedly connected to the valve cover, and the other end extends into the valve body and is fixedly connected to the valve stem. The valve cover is provided with a bellows vacuum connector perpendicular to the axial direction of the valve stem. The bellows vacuum connector penetrates the side wall of the valve cover. A vacuum environment is formed inside the inner bellows by evacuating air through the bellows vacuum connector. A low-temperature epoxy fiberglass filling ring is filled between the inner bellows and the valve body. The outer wall of the valve body is provided with a winding layer, which includes a heat insulation layer and a heat radiation protection layer. The outer wall of the valve body is also provided with a vacuum jacket. The vacuum jacket is fixedly connected to the valve body through an expansion joint. A vacuum evacuation connector is provided on the side wall of the vacuum jacket. A vacuum environment is formed inside the vacuum jacket by evacuating air through the vacuum evacuation connector.

[0009] Preferably, the insulating heat pack is made of aluminum foil, the heat radiation protection layer is made of fiberglass, and the insulating heat pack and the heat radiation protection layer are layered and overlapped in multiple alternating layers.

[0010] Preferably, a guide rib is provided on the inner wall of the valve body near the edge of the valve seat, and when the valve disc is in the closing stroke, the side wall of the valve disc fits against the guide rib.

[0011] Preferably, the upper end of the valve body is provided with an extended valve body design, the valve stem adopts a split design, an extended valve stem tube is provided between the valve stem and the valve disc, a very small gap is left between the extended valve stem tube and the extended valve body, a first locking mechanism is provided between the valve stem and the extended valve stem tube, the first locking mechanism includes a valve stem nut and a first connecting block, the valve stem nut is disposed between the valve stem and the first connecting block, the valve stem nut is threadedly connected to the first connecting block, the upper end of the extended valve stem tube extends upward with a valve stem tube connecting part, the lower end of the valve stem is provided with a first connecting part, the first connecting part extends to the space between the first connecting block and the valve stem tube connecting part, the valve stem tube connecting part, the first connecting part and the first connecting block are fixedly connected by fasteners, the valve stem is fixedly connected to the extended valve stem tube by the first locking mechanism, and when the valve stem rotates, the extended valve stem tube rotates with the valve stem;

[0012] A second locking mechanism is provided between the extended valve stem tube and the valve disc. The second locking mechanism includes a valve stem tube nut and a second connecting block. The valve stem tube nut is disposed between the extended valve stem tube and the second connecting block and is threadedly connected to the second connecting block. A valve disc connecting portion extends upward from the upper end of the valve disc, and a second connecting portion is provided at the lower end of the extended valve stem tube. The second connecting portion extends between the second connecting block and the valve disc connecting portion. The valve disc connecting portion, the second connecting portion, and the second connecting block are fixedly connected by fasteners. The extended valve stem tube is fixedly connected to the valve disc through the second locking mechanism. When the extended valve stem tube rotates, the valve disc rotates with the extended valve stem tube.

[0013] Preferably, the valve disc is fitted with a sleeve. The upper end of the sleeve is inserted into the valve stem, and the lower end abuts against the valve seat and has an opening with the same diameter as the valve seat for medium flow. The inner wall of the sleeve is provided with internal threads, and the outer wall of the second connecting block is provided with external threads that mate with the internal threads of the inner wall of the sleeve. The sleeve and the second connecting block are threadedly connected. The rotation direction of the thread on the outer wall of the second connecting block is the same as the rotation direction of the valve stem when it is opened and closed. The outer wall of the sleeve has a first flow channel and a second flow channel distributed sequentially from bottom to top along the axial direction of the valve stem. The inner wall of the lowest end of the first flow channel forms a first sealing surface, and the inner wall of the lowest end of the second flow channel forms a second sealing surface. The valve disc is displaced relative to the sleeve through the threaded engagement between the second connecting block and the sleeve. When the valve stem rotates and rises, it drives the second connecting block and the valve disc to rotate and rise. When the bottom surface of the valve disc is higher than the first sealing surface, the inlet channel is connected to the first flow channel. When the bottom surface of the valve disc is higher than the second sealing surface, the inlet channel is connected to both the first and second flow channels.

[0014] Preferably, the upper end of the sleeve is provided with a sleeve connecting block, the sleeve connecting block and the sleeve are fixedly connected by fasteners, the bottom surface of the sleeve connecting block is provided with a sleeve abutment part, the inner diameter of the sleeve abutment part is smaller than the inner diameter of the sleeve, the bottom end of the sleeve is provided with a sleeve sealing part, the sleeve sealing part abuts against the valve seat, the second connecting block rotates and rises to abut against the sleeve abutment part, when the second connecting block abuts against the sleeve abutment part, the inlet channel is simultaneously connected to the first flow channel and the second flow channel, when the second connecting block continues to rise, the sleeve rises with the rise of the second connecting block, the sleeve sealing part moves away from the valve seat to form a third flow channel, the third flow channel is connected to the inlet channel.

[0015] Preferably, the lower end face edge of the valve disc is welded with a weld overlay layer, the edge of the weld overlay layer is provided with a conical sealing surface, the inner wall of the sleeve sealing part is provided with a first abutting block and a second abutting block, the sleeve sealing part, the first abutting block and the second abutting block are fixedly connected by fasteners, the valve seat and the sleeve sealing part are provided with a valve seat sealing layer, the first abutting block abuts against the weld overlay layer, the second abutting block abuts against the valve seat sealing layer, the valve seat sealing layer is provided with an inclined angle at the point where it mates with the second abutting block, and the sleeve sealing part is provided with an arc-shaped sealing part at the point where it mates with the valve seat sealing layer.

[0016] Preferably, the sleeve connecting block is provided with an annular sealing ring at the valve stem mating point, the sleeve abutment part is provided with a buffer packing layer at the sleeve mating point, and the second connecting block is provided with a sealing block at the sleeve mating point.

[0017] Preferably, both the inlet and outlet channels are equipped with flange sealing structures. The flange sealing structure includes a flange and a lining insulation layer. The lining insulation layer is fixedly connected to the flange by bolts. The lining insulation layer extends to the inner wall of the valve body, and a conical protrusion is provided at the extension point where it mates with the valve body. A conical groove that mates with the conical protrusion is provided on the inner wall of the valve body. A conical guide portion is also provided on the outer end face of the lining insulation layer. A special-shaped sealing ring is provided between the outer end face of the flange and the lining insulation layer.

[0018] Preferably, the liquid helium shut-off valve further includes a handwheel, a packing layer is fixedly embedded in the end of the valve cover away from the valve body, a packing gland is provided above the packing layer, the packing gland is fixedly connected to the valve cover by bolts, the valve stem passes through the packing layer and the packing gland and extends above the packing gland, the end of the valve stem away from the valve disc is fixedly connected to the handwheel by a handwheel nut, a first filter screen is provided in the inlet channel, and a second filter screen is provided on the valve seat.

[0019] The beneficial effects of this invention are as follows: the vacuum inner bellows reduces heat conduction at the valve stem and valve cover mating point, effectively preventing external leakage; the low-temperature epoxy fiberglass filling ring prevents liquid helium medium from entering, preventing frost and ice formation at the valve cover and packing; the heat insulation layer and heat radiation protection layer reduce heat radiation and heat conduction of the valve body and have good heat preservation effect; the vacuum metal vacuum jacket forms a vacuum insulation layer, further reducing heat radiation and heat conduction of the valve body; the combination of the vacuum inner bellows, winding layer, and vacuum jacket greatly improves the heat preservation and insulation capabilities of the valve body, resulting in unexpected effects. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0021] Figure 1 This is a schematic diagram of the structure of a liquid helium shut-off valve with a bellows vacuum jacket according to the present invention.

[0022] Figure 2 for Figure 1 A magnified view of part A;

[0023] Figure 3 for Figure 1 A magnified view of section B;

[0024] Figure 4 for Figure 1 A magnified view of a portion at point C;

[0025] Figure 5 for Figure 1 A magnified view of a portion at point D;

[0026] In the diagram, 1-valve body, 2-valve stem, 3-valve cover, 4-handwheel, 5-valve seat, 6-valve disc, 7-inlet channel, 8-outlet channel, 9-packing layer, 10-packing gland, 11-inner bellows, 12-bellows vacuum connector, 13-low temperature epoxy fiberglass filling ring, 14-insulation heat packing, 15-heat radiation protection layer, 16-vacuum jacket, 17-expansion joint, 18-vacuum connector, 19-extended valve stem tube, 20-guide rib, 21-first locking mechanism, 22-valve stem nut, 23-first connecting block, 24-valve stem tube connection, 25-first connecting part, 26-second locking mechanism, 27-valve stem tube nut, 28- Second connecting block, 29-valve disc connecting part, 30-second connecting part, 31-sleeve, 32-first flow channel, 33-second flow channel, 34-first sealing surface, 35-second sealing surface, 36-sleeve connecting block, 37-sleeve abutment part, 38-sleeve sealing part, 39-weld overlay layer, 40-first abutment block, 41-second abutment block, 42-valve seat sealing layer, 43-arc-shaped sealing part, 44-annular sealing ring, 45-buffered packing layer, 46-sealing block, 47-flange, 48-lining insulation layer, 49-conical protrusion, 50-conical guide part, 51-irregular sealing ring, 52-first filter screen, 53-second filter screen. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0028] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0029] The directional and positional terms used in this invention, such as "up," "down," "front," "back," "left," "right," "inner," "outer," "top," "bottom," and "side," are merely for reference to the accompanying drawings. Therefore, the directional and positional terms used are for illustrating and understanding this invention, and not for limiting the scope of protection of this invention.

[0030] like Figures 1 to 5 As shown, this is an embodiment of the present invention. A liquid helium shut-off valve with a bellows vacuum jacket includes a valve body 1, a valve stem 2, and a valve cover 3. The valve body 1 is provided with a valve seat 5 inside. The lower end of the valve stem 2 is provided with a valve disc 6. The valve stem 2 extends into the valve body 1 and cooperates with the valve seat 5 through the valve disc 6. The interior of the valve body 1 is divided into an inlet channel 7 and an outlet channel 8 by the cooperation of the valve disc 6 and the valve seat 5. The valve cover 3 is fixedly connected to the valve body 1 by bolts.

[0031] An inner bellows 11 is provided between the valve stem 2 and the valve cover 3. One end of the inner bellows 11 is fixedly connected to the valve cover 3, and the other end extends into the valve body 1 and is fixedly connected to the valve stem 2. The valve cover 3 is provided with a bellows vacuum connector 12 perpendicular to the axial direction of the valve stem 2. The bellows vacuum connector 12 penetrates the side wall of the valve cover 3. The inner bellows 11 is evacuated through the bellows vacuum connector 12 to form a vacuum environment. The space between the inner bellows 11 and the valve body 1 is filled with a low-temperature epoxy fiberglass filling ring 13. The outer wall of the valve body 1 is provided with a winding layer, which includes a heat insulation layer 14 and a heat radiation protection layer 15. The outer wall of the valve body 1 is also provided with a vacuum jacket 16. The vacuum jacket 16 is fixedly connected to the valve body 1 through a telescopic joint 17. The side wall of the vacuum jacket 16 is provided with a vacuum extraction connector 18. The vacuum jacket 16 is evacuated through the vacuum extraction connector 18 to form a vacuum environment.

[0032] In an embodiment of the present invention, the heat insulation layer 14 is made of aluminum foil, the heat radiation protection layer 15 is made of glass fiber, and the heat insulation layer 14 and the heat radiation protection layer 15 are layered and overlapped in multiple alternating layers.

[0033] In an embodiment of the present invention, a guide rib 20 is provided on the inner wall of the valve body 1 near the edge of the valve seat 5. When the valve disc 6 is in the closing stroke, the side wall of the valve disc 6 is in contact with the guide rib 20.

[0034] In an embodiment of the present invention, the upper end of the valve body 1 is provided with an extended valve body design, the valve stem 2 adopts a split design, an extended valve stem tube 19 is provided between the valve stem 2 and the valve disc 6, a very small gap is left between the extended valve stem tube 19 and the extended valve body, and a first locking mechanism 21 is provided between the valve stem 2 and the extended valve stem tube 19. The first locking mechanism 21 includes a valve stem nut 22 and a first connecting block 23. The valve stem nut 22 is disposed between the valve stem 2 and the first connecting block 23. The connecting block 23 is threaded. The upper end of the extended valve stem tube 19 extends upward to a valve stem tube connecting part 24. The lower end of the valve stem 2 is provided with a first connecting part 25. The first connecting part 25 extends between the first connecting block 23 and the valve stem tube connecting part 24. The valve stem tube connecting part 24, the first connecting part 25 and the first connecting block 23 are fixedly connected by fasteners. The valve stem 2 is fixedly connected to the extended valve stem tube 19 by a first locking mechanism 21. When the valve stem 2 rotates, the extended valve stem tube 19 rotates with the valve stem 2.

[0035] A second locking mechanism 26 is provided between the extended valve stem tube 19 and the valve disc 6. The second locking mechanism 26 includes a valve stem tube nut 27 and a second connecting block 28. The valve stem tube nut 27 is disposed between the extended valve stem tube 19 and the second connecting block 28. The valve stem tube nut 27 is threadedly connected to the second connecting block 28. A valve disc connecting portion 29 extends upward from the upper end of the valve disc 6. A second connecting portion 30 is provided at the lower end of the extended valve stem tube 19. The second connecting portion 30 extends between the second connecting block 28 and the valve disc connecting portion 29. The valve disc connecting portion 29, the second connecting portion 30, and the second connecting block 28 are fixedly connected by fasteners. The extended valve stem tube 19 is fixedly connected to the valve disc 6 by the second locking mechanism 26. When the extended valve stem tube 19 rotates, the valve disc 6 rotates with the extended valve stem tube 19.

[0036] In an embodiment of the present invention, the valve disc 6 is fitted with a sleeve 31. The upper end of the sleeve 31 is inserted into the valve stem 2, and the lower end abuts against the valve seat 5 and has an opening with the same diameter as the valve seat 5 for medium flow. The inner wall of the sleeve 31 is provided with an internal thread, and the outer wall of the second connecting block 28 is provided with an external thread that mates with the internal thread of the inner wall of the sleeve 31. The sleeve 31 is threadedly connected to the second connecting block 28. The rotation direction of the thread on the outer wall of the second connecting block 28 is the same as the rotation direction of the valve stem 2 when it is opened and closed. The outer wall of the sleeve 31 has a first flow channel 32 and a second flow channel 33 distributed sequentially from bottom to top along the axial direction of the valve stem 2. The second flow channel 33 has a first sealing surface 34 formed on the inner wall of the lowest end of the first flow channel 32, and a second sealing surface 35 formed on the inner wall of the lowest end of the second flow channel 33. The valve disc 6 is displaced relative to the sleeve 31 through the threaded engagement of the second connecting block 28 and the sleeve 31. When the valve stem 2 rotates and rises, it drives the second connecting block 28 and the valve disc 6 to rotate and rise. When the bottom surface of the valve disc 6 is higher than the first sealing surface 34, the inlet channel 7 is connected to the first flow channel 32. When the bottom surface of the valve disc 6 is higher than the second sealing surface 35, the inlet channel 7 is connected to both the first flow channel 32 and the second flow channel 33.

[0037] In an embodiment of the present invention, the upper end of the sleeve 31 is provided with a sleeve connecting block 36, and the sleeve connecting block 36 is fixedly connected to the sleeve 31 by fasteners. The bottom surface of the sleeve connecting block 36 is provided with a sleeve abutment part 37, the inner diameter of the sleeve abutment part 37 is smaller than the inner diameter of the sleeve 31, and the bottom end of the sleeve 31 is provided with a sleeve sealing part 38, which abuts against the valve seat 5. The second connecting block 28 rotates and rises to abut against the sleeve abutment part 37. When the second connecting block 28 abuts against the sleeve abutment part 37, the inlet channel 7 is simultaneously connected to the first flow channel 32 and the second flow channel 33. When the second connecting block 28 continues to rise, the sleeve 31 rises with the rise of the second connecting block 28, and the sleeve sealing part 38 moves away from the valve seat 5 to form a third flow channel, which is connected to the inlet channel 7.

[0038] In an embodiment of the present invention, a weld overlay layer 39 is welded to the lower end face edge of the valve disc 6, and a conical sealing surface is provided at the edge of the weld overlay layer 39. A first abutting block 40 and a second abutting block 41 are provided on the inner wall of the sleeve sealing part 38. The sleeve sealing part 38, the first abutting block 40 and the second abutting block 41 are fixedly connected by fasteners. A valve seat sealing layer 42 is provided at the mating point between the valve seat 5 and the sleeve sealing part 38. The first abutting block 40 abuts against the weld overlay layer 39, and the second abutting block 41 abuts against the valve seat sealing layer 42. An inclined angle is provided at the mating point between the valve seat sealing layer 42 and the second abutting block 41. An arc-shaped sealing part 43 is provided at the mating point between the sleeve sealing part 38 and the valve seat sealing layer 42.

[0039] In an embodiment of the present invention, an annular sealing ring 44 is provided at the part of the sleeve connecting block 36 that mates with the valve stem 2, a buffer packing layer 45 is provided at the part of the sleeve abutment 37 that mates with the sleeve 31, and a sealing block 46 is provided at the part of the second connecting block 28 that mates with the sleeve 31.

[0040] In an embodiment of the present invention, both the inlet channel 7 and the outlet channel 8 are provided with flange sealing structures. The flange sealing structure includes a flange 47 and a lining insulation layer 48. The lining insulation layer 48 is fixedly connected to the flange 47 by bolts. The lining insulation layer 48 extends to the inner wall of the valve body 1, and a conical protrusion 49 is provided at the extension and the mating part of the valve body 1. A conical groove that mates with the conical protrusion 49 is provided on the inner wall of the valve body 1. A conical guide portion 50 is also provided on the outer end face of the lining insulation layer 48. The conical guide portion 50 is used for the flange connection between the valve and the external pipeline and has a quick docking function. A special-shaped sealing ring 51 is provided between the outer end face of the flange 47 and the lining insulation layer 48. The flange 47 is provided with a groove that matches the shaped sealing ring. The shaped sealing ring 51 is installed in the groove of the flange 47, which improves the sealing performance and the firmness of the installation of the shaped sealing ring 51. The end of the shaped sealing ring 51 that abuts against the lining insulation layer has a raised arc-shaped sealing surface. The arc-shaped sealing surface forms an elastic seal, which greatly improves the sealing performance.

[0041] In an embodiment of the present invention, the liquid helium shut-off valve further includes a handwheel 4. A packing layer 9 is fixedly embedded inside the valve cover 3 at the end furthest from the valve body 1. A packing gland 10 is provided above the packing layer 9, and the packing gland 10 is fixedly connected to the valve cover 3 by bolts. The valve stem 2 passes through the packing layer 9 and the packing gland 10 and extends above the packing gland 10. The end of the valve stem 2 furthest from the valve disc 6 is fixedly connected to the handwheel 4 via a handwheel nut. A first filter screen 52 is provided in the inlet channel 7, and a second filter screen 53 is provided on the valve seat 5. The first filter screen 52 has a first snap-fit ​​portion around its circumference, and the lining insulation layer has a second snap-fit ​​portion that matches the snap-fit ​​portion. The first filter screen and the lining insulation layer are connected by the snap-fit ​​of the first and second snap-fit ​​portions, so that the first filter screen is firmly fixed in the inlet channel, preventing the medium from flowing into the installation gap between the first filter screen and the valve body and ensuring filtration performance. The second filter screen 53 has an arc-shaped structure to increase the filtration area and prevent impurities from accumulating on it. The second filter screen 53 and the valve seat sealing surface are fixed to the valve seat by the same bolt, reducing the number of parts and making disassembly and assembly convenient.

[0042] The valve employs a sealing structure design with an internal bellows located at the top of the valve stem, and the bellows is evacuated to a vacuum level of 1×10⁻⁶. -3The valve body achieves a sealing performance of ISO 15848 Class A by reducing heat conduction and effectively preventing external leakage. The external space of the inner bellows is filled with a low-temperature resistant PTFE ring to prevent the ingress of liquid helium media at -269℃, creating a vapor space to reduce heat loss and prevent frost and ice formation at the flange and packing. The entire outer wall of the valve body is wrapped with multiple layers of thermal insulation materials, including aluminum foil and fiberglass. The insulation layer reduces heat conduction, and the heat-resistant layer reduces heat radiation, providing excellent cold insulation, stable performance, and reliable safety. A metal vacuum jacket is welded to the valve body, forming a vacuum insulation layer through a vacuum joint. The vacuum surface is polished to effectively reduce heat radiation and heat loss. An expansion joint is installed at the top of the vacuum jacket to prevent cracks caused by thermal expansion and contraction and uneven stress under temperature changes.

[0043] The valve body adopts an integral casting extended design to ensure reliable pressure bearing safety. The extension height is calculated using finite element simulation temperature field to ensure that the stuffing box temperature is above 0℃.

[0044] The extended valve stem adopts a split design, consisting of an extended valve stem tube and a valve stem. The extended valve stem tube and the extended valve body have a very small gap, which effectively reduces heat conduction and heat loss. At the same time, the extended valve stem tube enhances the strength and rigidity of the valve stem, ensures a qualified slenderness ratio, and increases the reliability of valve opening and closing at ultra-low temperatures.

[0045] The valve body is equipped with guide ribs to guide the opening and closing of the valve disc, while also increasing the rigidity and strength of the valve body, reducing valve body deformation at ultra-low temperatures, and improving valve sealing performance.

[0046] The valve stem, extension valve stem, and valve disc are all equipped with a locking mechanism, which allows the extension valve stem and valve disc to be driven synchronously when the handwheel is turned to drive the valve stem. The locking mechanism is detachable, which facilitates the replacement of parts and greatly reduces costs.

[0047] The valve disc is fitted with a sleeve structure. The outer wall of the sleeve has a first flow channel and a second flow channel at different heights. The sleeve and the valve disc are connected by threads, and the rotation direction of the threads is the same as that of the handwheel. The valve disc can move axially relative to the sleeve by rotating and engaging with the sleeve's threads. When the valve disc rises to a certain height, the bottom of the valve disc is higher than the first sealing surface, and the inlet channel is connected to the first flow channel, forming a first-stage pressure relief. When the valve disc continues to rise to a certain height, the bottom of the valve disc is higher than the second sealing surface, and the inlet channel is connected to both the first and second flow channels, forming a second-stage pressure relief. When the valve disc continues to rise and abuts against the sleeve, the valve disc and the sleeve do not move relative to each other. The valve disc drives the sleeve to move upward at the same time, causing the sleeve sealing part to separate from the valve seat and form a third flow channel. The inlet channel is connected to the third flow channel, forming a third-stage pressure relief. The top of the sleeve has a detachable structure, which facilitates disassembly and replacement of sleeves with different numbers of flow channels to achieve more stages of pressure relief.

[0048] The sleeve sealing part is connected with a detachable structure and an arc-shaped sealing structure, which has the advantages of good sealing performance and replacement of easily worn parts. The valve seat sealing part has an inclined part that cooperates with the sleeve to guide the sleeve and reduce wear. The detachable structure of the valve seat sealing part has the advantages of replaceable sealing surface and reduced maintenance costs.

[0049] The annular sealing ring increases the sealing performance between the valve stem and the sleeve. The buffer packing layer increases the friction between the second connecting block and the sleeve connecting block, allowing the sleeve to move more synchronously when the second connecting block and the sleeve connecting block abut. The sealing block increases the sealing performance between the sleeve and the second connecting block and prevents damage to the fittings caused by excessive rotation of the second connecting block's threads.

[0050] Different hard alloys are overlaid on the sealing surface at the bottom of the valve disc, and the hardness difference of the overlay layer is not less than HB50. A conical sealing design is adopted, and after precision machining, it is ground to achieve a surface finish of Ra0.1 or higher, ensuring reliable sealing.

[0051] The flange sealing structure of the inlet and outlet channels, and the lining sealing layer have the functions of reducing heat radiation and enhancing sealing performance. The inlet channel also has a first filter and a second filter, forming a dual filtration structure, which greatly improves the filtration performance.

[0052] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A liquid helium shut-off valve with a bellows vacuum jacket, comprising a valve body (1), a valve stem (2) and a valve cover (3), wherein a valve seat (5) is provided inside the valve body (1), a valve disc (6) is provided at the lower end of the valve stem (2), the valve stem (2) extends into the valve body (1) and cooperates with the valve seat (5) through the valve disc (6), the interior of the valve body (1) is divided into an inlet channel (7) and an outlet channel (8) through the cooperation of the valve disc (6) and the valve seat (5), and the valve cover (3) is fixedly connected to the valve body (1) by bolts; Its features are: An inner bellows (11) is provided between the valve stem (2) and the valve cover (3). One end of the inner bellows (11) is fixedly connected to the valve cover (3), and the other end extends into the valve body (1) and is fixedly connected to the valve stem (2). The valve cover (3) is provided with a bellows vacuum connector (12) perpendicular to the axial direction of the valve stem (2). The bellows vacuum connector (12) penetrates the side wall of the valve cover (3). The inner bellows (11) is evacuated through the bellows vacuum connector (12) to form a vacuum environment. The inner bellows (11) and the valve... The valve body (1) is filled with a low-temperature epoxy fiberglass filling ring (13). The outer wall of the valve body (1) is provided with a winding layer, which includes a heat insulation layer (14) and a heat radiation protection layer (15). The outer wall of the valve body (1) is also provided with a vacuum jacket (16). The vacuum jacket (16) is fixedly connected to the valve body (1) through a telescopic joint (17). The side wall of the vacuum jacket (16) is provided with a vacuum joint (18). The vacuum jacket (16) is evacuated through the vacuum joint (18) to form a vacuum environment. The valve body (1) has an extended valve body design at its upper end. The valve stem (2) adopts a split design. An extended valve stem tube (19) is provided between the valve stem (2) and the valve disc (6). A very small gap is left between the extended valve stem tube (19) and the extended valve body. A first locking mechanism (21) is provided between the valve stem (2) and the extended valve stem tube (19). The first locking mechanism (21) includes a valve stem nut (22) and a first connecting block (23). The valve stem nut (22) is located between the valve stem (2) and the first connecting block (23). The valve stem (2) is connected by a threaded connection. The upper end of the extended valve stem tube (19) extends upward to a valve stem tube connection part (24). The lower end of the valve stem (2) is provided with a first connection part (25). The first connection part (25) extends to the space between the first connection block (23) and the valve stem tube connection part (24). The valve stem tube connection part (24), the first connection part (25) and the first connection block (23) are fixedly connected by fasteners. The valve stem (2) is fixedly connected to the extended valve stem tube (19) by a first locking mechanism (21). When the valve stem (2) rotates, the extended valve stem tube (19) rotates with the valve stem (2). A second locking mechanism (26) is provided between the extended valve stem tube (19) and the valve disc (6). The second locking mechanism (26) includes a valve stem tube nut (27) and a second connecting block (28). The valve stem tube nut (27) is disposed between the extended valve stem tube (19) and the second connecting block (28). The valve stem tube nut (27) is threadedly connected to the second connecting block (28). A valve disc connecting part (29) extends upward from the upper end of the valve disc (6). The extended valve stem tube (19) The lower end is provided with a second connecting part (30), which extends between the second connecting block (28) and the valve disc connecting part (29). The valve disc connecting part (29), the second connecting part (30), and the second connecting block (28) are fixedly connected by fasteners. The extended valve stem tube (19) is fixedly connected to the valve disc (6) by the second locking mechanism (26). When the extended valve stem tube (19) rotates, the valve disc (6) rotates with the extended valve stem tube (19).

2. The liquid helium shut-off valve with a bellows vacuum jacket according to claim 1, characterized in that: The insulating heat pack (14) is made of aluminum foil, and the heat radiation protection layer (15) is made of glass fiber. The insulating heat pack (14) and the heat radiation protection layer (15) are layered and overlapped in multiple layers.

3. A liquid helium shut-off valve with a bellows vacuum jacket according to claim 1, characterized in that: The valve body (1) has a guide rib (20) on its inner wall near the edge of the valve seat (5). When the valve disc (6) is in the closing stroke, the side wall of the valve disc (6) fits against the guide rib (20).

4. A liquid helium shut-off valve with a bellows vacuum jacket according to claim 1, characterized in that: The valve disc (6) is covered by a sleeve (31). The upper end of the sleeve (31) is inserted into the valve stem (2), and the lower end abuts against the valve seat (5) and has an opening with the same diameter as the valve seat (5) for medium flow. The inner wall of the sleeve (31) is provided with an internal thread, and the outer wall of the second connecting block (28) is provided with an external thread that mates with the internal thread of the inner wall of the sleeve (31). The sleeve (31) is threadedly connected to the second connecting block (28). The rotation direction of the thread on the outer wall of the second connecting block (28) is the same as the rotation direction of the valve stem (2) when it is opened and closed. The outer wall of the sleeve (31) has a first flow channel (32) and a second flow channel (33) distributed sequentially from bottom to top along the axial direction of the valve stem (2). The inner wall of the lowest end of the first flow channel (32) forms a first sealing surface (34), and the inner wall of the lowest end of the second flow channel (33) forms a second sealing surface (35). The valve disc (6) is displaced relative to the sleeve (31) through the threaded engagement of the second connecting block (28) and the sleeve (31). When the valve stem (2) rotates and rises, it drives the second connecting block (28) and the valve disc (6) to rotate and rise. When the bottom surface of the valve disc (6) is higher than the first sealing surface (34), the inlet channel (7) is connected to the first flow channel (32). When the bottom surface of the valve disc (6) is higher than the second sealing surface (35), the inlet channel (7) is connected to both the first flow channel (32) and the second flow channel (33).

5. A liquid helium shut-off valve with a bellows vacuum jacket according to claim 4, characterized in that: The upper end of the sleeve (31) is provided with a sleeve connecting block (36), the sleeve connecting block (36) and the sleeve (31) are fixedly connected by fasteners, the bottom surface of the sleeve connecting block (36) is provided with a sleeve abutment part (37), the inner diameter of the sleeve abutment part (37) is smaller than the inner diameter of the sleeve (31), the bottom end of the sleeve (31) is provided with a sleeve sealing part (38), the sleeve sealing part (38) abuts against the valve seat (5), the second connecting block (28) The second connecting block (28) rotates and rises until it abuts against the sleeve contact part (37). When the second connecting block (28) abuts against the sleeve contact part (37), the inlet channel (7) is simultaneously connected to the first flow channel (32) and the second flow channel (33). When the second connecting block (28) continues to rise, the sleeve (31) rises with the rise of the second connecting block (28). The sleeve sealing part (38) moves away from the valve seat (5) to form a third flow channel, which is connected to the inlet channel (7).

6. A liquid helium shut-off valve with a bellows vacuum jacket according to claim 5, characterized in that: The lower end face edge of the valve disc (6) is welded with a weld overlay layer (39), and the edge of the weld overlay layer (39) is provided with a conical sealing surface. The inner wall of the sleeve sealing part (38) is provided with a first abutting block (40) and a second abutting block (41). The sleeve sealing part (38), the first abutting block (40) and the second abutting block (41) are fixedly connected by fasteners. The valve seat (5) and the sleeve sealing part (38) are provided with a valve seat sealing layer (42). The first abutting block (40) abuts against the weld overlay layer (39), and the second abutting block (41) abuts against the valve seat sealing layer (42). The valve seat sealing layer (42) and the second abutting block (41) are provided with an inclined angle. The sleeve sealing part (38) and the valve seat sealing layer (42) are provided with an arc-shaped sealing part (43).

7. A liquid helium shut-off valve with a bellows vacuum jacket according to claim 5, characterized in that: The sleeve connecting block (36) is provided with an annular sealing ring (44) at the joint with the valve stem (2), the sleeve abutment part (37) is provided with a buffer packing layer (45) at the joint with the sleeve (31), and the second connecting block (28) is provided with a sealing block (46) at the joint with the sleeve (31).

8. A liquid helium shut-off valve with a bellows vacuum jacket according to claim 1, characterized in that: Both the inlet channel (7) and the outlet channel (8) are provided with flange sealing structures. The flange sealing structure includes a flange (47) and a lining insulation layer (48). The lining insulation layer (48) is fixedly connected to the flange (47) by bolts. The lining insulation layer (48) extends to the inner wall of the valve body (1) and a conical protrusion (49) is provided at the extension and the valve body (1). A conical groove that mates with the conical protrusion (49) is provided on the inner wall of the valve body (1). A conical guide (50) is also provided on the outer end face of the lining insulation layer (48). A special-shaped sealing ring (51) is provided between the outer end face of the flange (47) and the lining insulation layer (48).

9. A liquid helium shut-off valve with a bellows vacuum jacket according to claim 1, characterized in that: The liquid helium shut-off valve also includes a handwheel (4). A packing layer (9) is fixedly embedded in the end of the valve cover (3) away from the valve body (1). A packing gland (10) is provided above the packing layer (9). The packing gland (10) is fixedly connected to the valve cover (3) by bolts. The valve stem (2) passes through the packing layer (9) and the packing gland (10) and extends to the top of the packing gland (10). The end of the valve stem (2) away from the valve disc (6) is fixedly connected to the handwheel (4) by a handwheel nut. A first filter screen (52) is provided in the inlet channel (7). A second filter screen (53) is provided on the valve seat (5).

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