Rotary sealing device for low-temperature medium
By combining the magnetic fluid sealing unit and the vacuum jacket structure, the sealing and energy consumption problems of the low-temperature rotary sealing device are solved, achieving efficient low-temperature sealing and long service life, and significantly reducing media loss and energy consumption.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-16
- Publication Date
- 2026-04-03
AI Technical Summary
Existing rotary sealing devices are prone to failure in low-temperature environments, have short service life, and lack thermal insulation design, resulting in sealing and energy consumption problems.
It adopts a magnetic fluid sealing unit and a vacuum jacket structure, combined with cold air circulation, to achieve non-contact dynamic sealing and heat preservation design, avoiding solid friction and heat exchange.
It achieves high sealing performance, long service life and low energy consumption in low temperature environments, with low leakage rate, lifespan extended by 5-8 times, and reduction of medium evaporation loss caused by heat exchange by more than 70%.
Smart Images
Figure CN121782439A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of cryogenic equipment, containers, and pipeline sealing technology, and specifically relates to a cryogenic medium rotary sealing device. Background Technology
[0002] In cryogenic equipment (superconducting magnets, cryogenic pumps, spacecraft propulsion systems, liquefied natural gas transportation equipment), it is necessary to transfer cryogenic media between rotating and stationary components while maintaining good sealing. Rotary sealing devices are used to prevent fluid leakage from the gap between rotating and stationary components. Common types include slip rings and sliding seals. Existing rotary sealing devices (such as mechanical seals, packing seals, or slip ring seals) have the following problems in cryogenic media environments: 1. Low-temperature seal failure: Traditional seals rely on sealing materials. Sealing materials (such as rubber and polymers) undergo glass transition at low temperatures, becoming brittle and hardening, losing their elastic sealing ability, and leading to seal failure. Secondly, mechanical seals with contact friction pairs may experience abnormal clearance due to material contraction at low temperatures, increasing the risk of leakage. 2. Short service life: The lubrication conditions of the sealing material deteriorate under low temperature conditions, which accelerates friction and wear. Its continuous working life is usually less than 1 / 5 of that under normal temperature conditions, which greatly shortens the sealing life. 3. Lack of insulation design: The existing device does not have an effective insulation structure, which leads to intense heat exchange between the low-temperature medium and the outside environment. This not only causes the valuable low-temperature medium to be lost through vaporization, but also increases the extra energy consumption required to maintain the system's low temperature.
[0003] Therefore, there is an urgent need for a rotary sealing device that can operate reliably for a long time in cryogenic environments and has good thermal insulation performance. Summary of the Invention
[0004] The purpose of this invention is to solve the problems in the background art and provide a low-temperature medium rotary sealing device. This rotary sealing device can achieve reliable dynamic sealing under low-temperature conditions, significantly extend its service life, and effectively reduce medium loss and equipment energy consumption caused by heat exchange.
[0005] The objective of this invention is achieved through the following technical solution: A cryogenic medium rotary sealing device includes a shell, an inner shell, a liquid inlet flange straight pipe, a rotary sealing assembly, a hollow shaft, and a magnetic fluid sealing unit. The shell has sealing flanges at both ends. The liquid inlet flange straight pipe is coaxially mounted inside the sealing flange at one end of the shell. The hollow shaft is rotatably mounted inside the shell via the magnetic fluid sealing unit. A drain pipe is installed inside the hollow shaft. The ends of the hollow shaft and the drain pipe are rotatably connected to the liquid inlet flange straight pipe via the rotary sealing assembly. The hollow shaft can rotate within the shell via the magnetic fluid sealing unit and the rotary sealing assembly. The inner shell is fitted onto the outer wall of the liquid inlet flange straight pipe. A sealing ring assembly and a bellows are sequentially installed at one end of the inner shell. The sealing ring assembly is aligned with the end of the hollow shaft. The end of the bellows away from the sealing ring assembly has an intermediate flange that is fixedly connected to the sealing flange at the other end of the shell. A vacuum layer exists between the shell, the inner shell, and the bellows.
[0006] The magnetic fluid sealing unit is fixedly connected to the intermediate flange. The magnetic fluid filling the magnetic fluid sealing unit is low-temperature resistant perfluoropolyether, and the internal dispersed nanoparticles are iron oxide magnetic particles.
[0007] The rotary sealing assembly includes a support ring, a pressure ring, a first plug seal, a threaded sleeve, and a magnetic sealing bearing. The inner and outer walls of the support ring are fixedly connected to the drain pipe and the hollow shaft, respectively. The first plug seal is installed between the support ring and the outer wall of the inlet flange straight pipe through the pressure ring. The threaded sleeve is threadedly connected to the outer wall of the support ring at the end away from the hollow shaft. The magnetic sealing bearing is connected between the threaded sleeve and the inlet flange straight pipe, and works with the magnetic fluid sealing unit to support the rotation of the hollow shaft.
[0008] The hollow shaft has a support edge extending toward the drain pipe on the inner wall of the end near the sealing ring assembly. A first sleeve and a second sleeve, fixedly connected to the support edge, are installed sequentially from the outside to the inside of the hollow shaft on one side of the support edge. The inner wall of the second sleeve is flush with the inner wall of the support edge. A first sealing plate is provided at the end of the hollow shaft away from the support edge, which is sealed to the side wall of the first sleeve. A second sealing plate is provided at the end of the first sleeve away from the support edge, which is sealed to the side wall of the second sleeve. A third sealing plate is provided at the end of the second sleeve away from the support edge, which is sealed to the side wall of the drain pipe, forming a first vacuum jacket, a circulating gas jacket, and a second vacuum jacket from the outside to the inside. A cold air inlet pipe communicating with the circulating gas jacket is connected to the side wall of the first sleeve. Several exhaust holes communicating with the circulating gas jacket are machined on the support edge.
[0009] The sealing ring assembly includes a collar, ring plates, and a second plug seal. The collar is located outside several exhaust holes. A guide groove on the inner wall of the collar mates with several exhaust holes. A second plug seal mates with a hollow shaft is symmetrically installed on the end faces of both ends of the collar. The two ring plates fix the second plug seal to the end of the collar with bolts. Several exhaust pipes are installed on the collar and communicate with the guide grooves. A cold air outlet pipe is connected in parallel to the end of the exhaust pipe away from the collar.
[0010] The beneficial effects of the cryogenic medium rotary sealing device provided by this invention are: (1) The magnetic fluid sealing unit uses a low-temperature adaptable magnetic fluid to achieve non-contact dynamic sealing, maintaining high elasticity and sealing performance even in cryogenic environments, with a leakage rate of less than 10%. ﹣7 Pa·m 3 / s, fundamentally avoids the wear and jamming problems of solid friction pairs at low temperatures. The magnetic fluid designed for low temperatures can maintain excellent fluidity in cryogenic environments, completely solving the problem of low-temperature embrittlement and leakage of traditional seals, and ensuring that it does not fail in cryogenic environments; (2) The integrated vacuum layer and vacuum interlayer, combined with the cold air circulation structure, can effectively isolate the external heat source under the condition of ensuring normal rotation, greatly reduce the environmental heat leakage, reduce the evaporation loss of the low temperature medium caused by heat exchange by more than 70%, significantly reduce the frequency of low temperature medium replenishment and system cooling energy consumption, and have excellent economic efficiency in operation. (3) The low-temperature weather-resistant structural design combined with no solid contact wear greatly extends the operating life of the device under continuous operation in low-temperature and ultra-low-temperature environments. The actual measurement can reach more than 5000 hours, which is 5 to 8 times the life of traditional mechanical seals. (4) The device has a compact structure and its sealing performance is not sensitive to changes in rotation speed. It is suitable for various working conditions from low speed to high speed and can be widely used in rotary transmission scenarios of various cryogenic media such as liquid nitrogen, liquid hydrogen, and liquefied natural gas. (5) It can achieve rotary cold sealing of one or more low-temperature media to ensure stable delivery of multi-channel, multi-fluid media. Attached Figure Description
[0011] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0012] Figure 1 This is a structural schematic diagram provided for an embodiment of the present invention.
[0013] Figure 2This is a schematic diagram of the internal structure of the outer shell provided in an embodiment of the present invention.
[0014] Figure 3 This is a schematic diagram of the external structure of the outer shell provided in an embodiment of the present invention.
[0015] Figure 4 This is a schematic diagram illustrating the installation and connection of the inlet flange straight pipe and the hollow shaft provided in an embodiment of the present invention.
[0016] Figure 5 This is a schematic diagram of the installation of the rotary sealing assembly provided in an embodiment of the present invention.
[0017] Figure 6 This is a schematic diagram of the structure of the vacuum shaft end provided in an embodiment of the present invention.
[0018] The diagram shows the following markings: 1. Outer shell; 11. Sealing flange; 12. Intermediate flange; 13. Vacuum layer; 2. Inner shell; 3. Sealing ring assembly; 31. Collar ring; 32. Ring plate; 33. Second plug seal; 34. Guide groove; 35. Exhaust pipe; 36. Cold air outlet pipe; 4. Bellows; 5. Liquid inlet flange straight pipe; 6. Rotary seal assembly; 61. Support ring; 62. Pressure ring; 63. First plug seal; 64. Threaded sleeve; 65. Magnetic seal bearing; 7. Hollow shaft; 701. Support edge; 702. Exhaust hole; 703. First sleeve; 704. Second sleeve; 705. First sealing plate; 706. Second sealing plate; 707. Third sealing plate; 708. First vacuum jacket; 709. Circulating gas jacket; 710. Second vacuum jacket; 711. Cold air inlet pipe; 8. Drain pipe; 9. Magnetohydrodynamic sealing unit. Detailed Implementation
[0019] like Figures 1-6 As shown, the cryogenic medium rotary sealing device provided in this embodiment includes: The outer casing 1 has sealing flanges 11 at both ends. A liquid inlet flange straight pipe 5 is installed inside the sealing flange 11 at one end of the outer casing 1. This section of the sealing flange 11 is also connected to external equipment or pipelines. An intermediate flange 12 is installed on the outer wall of the sealing flange 11 at the other end of the outer casing 1.
[0020] Inlet flange straight pipe 5, such as Figure 1 , Figure 4 As shown, the inlet flange straight pipe 5 is coaxially mounted on the inner side of the sealing flange 11 at one end of the outer shell 1 via a bracket. A flange is machined on the outer wall of the inlet flange straight pipe 5, and the flange is fixedly connected to the bracket on the sealing flange 11 by bolts. A straight pipe section extending into the outer shell 1 is machined on the inlet flange straight pipe 5.
[0021] Inner shell 2, such as Figure 5As shown, the inner shell 2 is fitted onto the outer wall of the flange of the inlet flange straight pipe 5. A sealing ring assembly 3 and a bellows 4 are sequentially installed at one end of the inner shell 2. The sealing ring assembly 3 is aligned with the end of the hollow shaft 7. The bellows 4 has an intermediate flange 12 at the end away from the sealing ring assembly 3, which is fixedly connected to the intermediate flange 12 on the sealing flange 11 at the other end of the outer shell 1. There is a vacuum layer 13 between the outer shell 1, the inner shell 2, and the bellows 4. The vacuum layer 13 is used to block heat conduction / convection to reduce the heat exchange between the low-temperature medium and the outside, thereby achieving heat preservation and energy saving. In addition, the bellows 4 can compensate for the displacement during the cooling and contraction process to avoid the generation of internal stress, thereby improving the stability of the vacuum layer 13.
[0022] Hollow shaft 7, such as Figure 1 As shown, the hollow shaft 7 is rotatably installed inside the housing 1 via the magnetic fluid sealing unit 9. The drain pipe 8 is installed inside the hollow shaft 7. The ends of the hollow shaft 7 and the drain pipe 8 are rotatably connected to the inlet flange straight pipe 5 via the rotary sealing assembly 6. The hollow shaft 7 can rotate inside the housing 1 via the magnetic fluid sealing unit 9 and the rotary sealing assembly 6. The inner shell 2 is fitted onto the outer wall of the inlet flange straight pipe 5.
[0023] Rotary sealing assembly 6, such as Figure 4 As shown, the rotary sealing assembly 6 includes a support ring 61, a pressure ring 62, a first plug seal 63, a threaded sleeve 64, and a magnetic sealing bearing 65. The inner and outer walls of the support ring 61 are fixedly connected to the drain pipe 8 and the hollow shaft 7, respectively. The first plug seal 63 is installed between the support ring 61 and the outer wall of the inlet flange straight pipe 5 via the pressure ring 62. The threaded sleeve 64 is threadedly connected to the outer wall of the support ring 61 at the end away from the hollow shaft 7. The magnetic sealing bearing 65 is connected between the threaded sleeve 64 and the inlet flange straight pipe 5. The fixed end of the magnetic sealing bearing 65 is connected to the inlet flange straight pipe 5, and the rotating end of the magnetic sealing bearing 65 is fixedly connected to the threaded sleeve 64, which rotates with the hollow shaft 7. The first plug seal 63 and the magnetic sealing bearing 65 form a two-stage composite seal and cooperate with the magnetic fluid sealing unit 9 to support the rotation of the hollow shaft 7.
[0024] like Figure 6As shown, a support edge 701 extending toward the drain pipe 8 is machined on the inner wall of the hollow shaft 7 near the sealing ring assembly 3. A first sleeve 703 and a second sleeve 704, fixedly connected to the support edge 701, are sequentially installed on one side of the hollow shaft 7 from the outside in. The inner wall of the second sleeve 704 is flush with the inner wall of the support edge 701. A first sealing plate 705 is provided at the end of the hollow shaft 7 away from the support edge 701, sealingly connected to the side wall of the first sleeve 703. The first sleeve 703 is located away from the support edge 701. One end is provided with a second sealing plate 706 which is sealed to the side wall of the second sleeve 704. The end of the second sleeve 704 away from the support edge 701 is provided with a third sealing plate 707 which is sealed to the side wall of the drain pipe 8, forming a first vacuum jacket 708, a circulating gas jacket 709 and a second vacuum jacket 710 from the outside to the inside. The side wall of the first sleeve 703 is connected to a cold air inlet pipe 711 that communicates with the circulating gas jacket 709. Several exhaust holes 702 that communicate with the circulating gas jacket 709 are machined on the support edge 701.
[0025] Sealing ring assembly 3; such as Figure 5 As shown, the sealing ring assembly 3 includes a collar 31, an annular plate 32, and a second sealing plug 33. The collar 31 is located outside several exhaust holes 702. The inner wall of the collar 31 has a guide groove 34 that cooperates with several exhaust holes 702. The end faces of both ends of the collar 31 are symmetrically equipped with second sealing plugs 33 that cooperate with the hollow shaft 7. The two annular plates 32 are fixed to the ends of the collar 31 with bolts. Several exhaust pipes 35 are installed on the collar 31 and communicate with the guide groove 34. The exhaust pipes 35 are connected in parallel to a cold air outlet pipe 36 at the end of the exhaust pipes 35 away from the collar 31. The two second sealing plugs 33 fit against the outer wall of the hollow shaft 7 to prevent the circulating air from flowing out.
[0026] The magnetic fluid sealing unit 9 includes a dynamic seal, a fixed seal, and a magnetic fluid filling the space between the dynamic and fixed seals. The dynamic seal is fixedly connected to the hollow shaft 7, and the fixed seal is fixedly connected to the intermediate flange 12 on the housing. The magnetic fluid filling the magnetic fluid sealing unit 9 is a low-temperature resistant perfluoropolyether, and the internally dispersed nanoparticles are iron oxide magnetic particles. The magnetic fluid sealing unit 9 is existing technology. The magnetic fluid sealing assembly also includes a permanent magnet and pole shoes. The magnetic fluid, together with the permanent magnet and pole shoes, forms a focused magnetic field, which enables the magnetic fluid to form a stable "liquid sealing ring" between the dynamic and fixed seals, achieving a non-contact, multi-stage dynamic seal.
[0027] The method of using this invention is as follows: During assembly: Assemble the outer shell 1, install the inner shell 2, sealing ring assembly 3 and bellows 4 inside the outer shell 1, then install the rotary sealing assembly 6 at the end of the hollow shaft 7, then install the magnetohydrodynamic sealing unit 9 between the hollow shaft 7 and the outer shell 1, and install the hollow shaft 7 into the inner shell 2 to connect the liquid inlet flange straight pipe 5. Subsequently, evacuate the vacuum layer 13, the first vacuum interlayer 708 and the second vacuum interlayer 710 to a vacuum, and connect the pipeline for the cryogenic liquid medium and the pipeline for the cryogenic gas medium.
[0028] In use, the hollow shaft 7 rotates, and the dynamic seal of the magnetic fluid sealing unit 9 and the rotating end of the magnetic sealing bearing 65 rotate synchronously. Under the magnetic field constraint of the permanent magnet and magnetic shoe, the magnetic fluid forms a stable sealing ring, which adheres to the fixed seal 4. The magnetic fluid sealing unit 9 does not rotate as a whole; only a very weak viscous shear flow exists inside it, thus achieving a near-zero wear dynamic seal and blocking the leakage of cryogenic media. The vacuum layer 13, the first vacuum interlayer 708, and the second vacuum interlayer 710 maintain a vacuum state, isolating most of the heat conduction and heat convection, significantly reducing the frequency of cryogenic media replenishment and system cooling energy consumption, resulting in superior economic efficiency. The cryogenic medium enters from the inlet flange straight pipe 5 and exits from the drain pipe 8. The circulating cryogenic medium is prevented from leaking and escaping through the first plug seal 63 on the rotary sealing assembly 6 and the magnetic sealing bearing 65. The second plug seal 33 on the sealing ring assembly 3 provides thermal insulation within the inner shell 2.
[0029] Based on data using liquid nitrogen as the cryogenic medium, and through experimental verification, the performance comparison and specific experimental data of the rotary sealing device of this patent with existing mechanical sealing devices are shown in Tables 1 and 2: Table 1: Performance Comparison of the Rotary Sealing Device of this Patent with Existing Mechanical Sealing Devices index Rotary sealing device Mechanical seal device <![CDATA[Leakage rate (Pa·m 3 / s)]]> <![CDATA[≤1×10 ﹣7 ]]> <![CDATA[≥1×10 ﹣4 ]]> Continuous low-temperature operating life (h) ≥5000 ≤800 heat loss reduction ratio ≥70% No thermal insulation structure Cryogenic dielectric replenishment frequency Reduced by approximately 75% Frequent replenishment Table 2: Comparison of specific experimental data between the rotary sealing device of this patent and existing mechanical sealing devices Test Project Rotary sealing device Mechanical seal device Increase <![CDATA[Liquid nitrogen seal leakage rate (Pa·m 3 / s)]]> <![CDATA[8.3×10 ﹣8 Pa·m3 / s]]> <![CDATA[2.1×10 ﹣4 Pa·m3 / s]]> Reduced by 3 orders of magnitude Continuous operation time at -196℃ (h) 5200h leak-free 750h leak Lifespan extended by approximately 6 times <![CDATA[Heat flow after vacuum insulation (W / m 2 )]]> <![CDATA[15W / m 2 ]]> <![CDATA[50 W / m 2 ]]> Reduced by 70% Annual operating energy consumption (under the same operating conditions) ≈1200kWh ≈4000kWh Energy saving of approximately 70% As shown in Tables 1 and 2, the rotary sealing device disclosed in this patent achieves highly reliable dynamic sealing under low-temperature conditions, significantly extends service life, and effectively reduces media loss and equipment energy consumption caused by heat exchange.
[0030] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications and substitutions based on the technical solutions and inventive concepts provided by the present invention should be covered within the scope of protection of the present invention.
Claims
1. A rotary sealing device for cryogenic media, characterized in that: The device includes an outer shell (1), an inner shell (2), an inlet flange straight pipe (5), a rotary sealing assembly (6), a hollow shaft (7), and a magnetic fluid sealing unit (9). The outer shell (1) has sealing flanges (11) at both ends. The inlet flange straight pipe (5) is coaxially installed inside the sealing flange (11) at one end of the outer shell (1). The hollow shaft (7) is rotatably installed inside the outer shell (1) through the magnetic fluid sealing unit (9). A drain pipe (8) is installed inside the hollow shaft (7). The ends of the hollow shaft (7) and the drain pipe (8) are rotatably connected to the inlet flange straight pipe (5) through the rotary sealing assembly (6). The hollow shaft (7) can rotate inside the outer shell (1) through the magnetic fluid sealing unit (9) and the rotary sealing assembly (6). The inner shell (2) is fitted on the outer wall of the liquid inlet flange straight pipe (5). A sealing ring assembly (3) and a bellows (4) are installed in sequence at one end of the inner shell (2). The sealing ring assembly (3) is aligned with the end of the hollow shaft (7). The bellows (4) is provided with an intermediate flange (12) at the end away from the sealing ring assembly (3) and is fixedly connected to the sealing flange (11) at the other end of the outer shell (1). There is a vacuum layer (13) between the outer shell (1), the inner shell (2), and the bellows (4).
2. The cryogenic medium rotary sealing device according to claim 1, characterized in that: The magnetic fluid sealing unit (9) is fixedly connected to the intermediate flange (12). The magnetic fluid filling the magnetic fluid sealing unit (9) is low-temperature resistant perfluoropolyether, and the internally dispersed nanoparticles are iron oxide magnetic particles.
3. The cryogenic medium rotary sealing device according to claim 1 or 2, characterized in that: The rotary sealing assembly (6) includes a support ring (61), a pressure ring (62), a first plug seal (63), a threaded sleeve (64), and a magnetic sealing bearing (65). The inner and outer walls of the support ring (61) are fixedly connected to the drain pipe (8) and the hollow shaft (7), respectively. The first plug seal (63) is installed between the support ring (61) and the outer wall of the inlet flange straight pipe (5) through the pressure ring (62). The threaded sleeve (64) is threadedly connected to the outer wall of the support ring (61) at the end away from the hollow shaft (7). The magnetic sealing bearing (65) is connected between the threaded sleeve (64) and the inlet flange straight pipe (5).
4. The cryogenic medium rotary sealing device according to claim 1, characterized in that: The hollow shaft (7) has a support edge (701) extending toward the drain pipe (8) on the inner wall of one end near the sealing ring assembly (3). A first sleeve (703) and a second sleeve (704) are sequentially installed on one side of the hollow shaft (701) from the outside in, and are fixedly connected to the support edge (701). The inner wall of the second sleeve (704) is flush with the inner wall of the support edge (701). A first sealing plate (705) is provided at the end of the hollow shaft (7) away from the support edge (701), and is sealed to the side wall of the first sleeve (703). The first sleeve (703) is located away from the support edge (701). One end of the sleeve (703) is provided with a second sealing plate (706) which is sealed to the side wall of the second sleeve (704). The end of the second sleeve (704) away from the support edge (701) is provided with a third sealing plate (707) which is sealed to the side wall of the drain pipe (8), forming a first vacuum jacket (708), a circulating gas jacket (709), and a second vacuum jacket (710) from the outside to the inside. The side wall of the first sleeve (703) is connected to a cold air inlet pipe (711) which communicates with the circulating gas jacket (709). Several exhaust holes (702) that communicate with the circulating gas jacket (709) are machined on the support edge (701).
5. The cryogenic medium rotary sealing device according to claim 4, characterized in that: The sealing ring assembly (3) includes a collar (31), a ring plate (32), and a second plug seal (33). The collar (31) is located outside several exhaust holes (702). The guide groove (34) on the inner wall of the collar (31) cooperates with several exhaust holes (702). The second plug seal (33) that cooperates with the hollow shaft (7) is symmetrically installed on the end faces of both ends of the collar (31). The two ring plates (32) fix the second plug seal (33) to the end of the collar (31) with bolts. Several exhaust pipes (35) are installed on the collar (31) and communicate with the guide groove (34). The exhaust pipes (35) are connected in parallel to the end of the exhaust pipes (35) away from the collar (31) with a cold air outlet pipe (36).