A high speed dynamic seal rotary union suitable for use with ultra-low temperature fluids

Abstract

The application belongs to the technical field of seal component design, and discloses a high-speed dynamic seal rotary joint suitable for super-low-temperature fluid, which mainly comprises a static shaft, a rotary shell, a super-low-temperature seal ring, a guide ring and a check ring. The high-speed dynamic seal rotary joint suitable for super-low-temperature fluid is used to realize the integration of the blocking flow, the labyrinth and the multi-stage lip seal structure in the limited space. The shrinkage deformation of the super-low-temperature seal ring in the super-low-temperature environment can be obviously inhibited by optimizing the base material of the super-low-temperature seal ring and additionally arranging the anti-shrinkage ring structure. The interference amount of the matching surface of the super-low-temperature seal ring is reasonably adjusted, so that the close contact of the lip seal interface in the super-low-temperature environment is ensured.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sealing component design, and particularly relates to a high-speed dynamic sealing rotary joint suitable for ultra-low temperature fluid. BACKGROUND

[0002] Liquid nitrogen internal spraying type electric spindles, swing heads and the like are core functional components of ultra-low temperature cooling machining machines, and the reliability of liquid nitrogen transmission is a key to determining the comprehensive performance and technical maturity of the machines. However, in the process of transmitting ultra-low temperature medium to rotating tools or working ends, only the end face sealing or single lip sealing structure of the conventional rotary joint is difficult to maintain effective sealing, and the conventional material lip sealing ring and spring compensation element are extremely prone to hardening and embrittlement in the ultra-low temperature environment, accompanied by significant low-temperature deformation, resulting in sealing interface failure and high risk of medium leakage. The maximum axial extension length of the stationary end conveying pipe in the rotating channel is increased, and a multi-stage sealing mode combining labyrinth sealing and lip sealing is adopted, which increases the medium leakage resistance and significantly improves the overall sealing performance of the rotary joint. By optimizing the cross-sectional configuration and fitting tolerance of the lip sealing ring, the sealing interface can be effectively guaranteed to be complete in the ultra-low temperature working condition, thereby enhancing the sealing reliability.

[0003] Therefore, the ultra-low temperature high-speed dynamic sealing rotary joint becomes one of the key elements for reliable transmission of liquid nitrogen in functional components of ultra-low temperature equipment. However, the development of the ultra-low temperature high-speed dynamic sealing rotary joint faces many difficulties. For example, the space for installing the rotary joint in functional components such as liquid nitrogen internal spraying type electric spindles and swing heads is limited, and how to integrate the multi-stage sealing structure without changing the original structure of these functional components; since the rotary joint in the liquid nitrogen internal spraying type electric spindle not only needs to work at high speed, but also needs to withstand the axial displacement caused by the loose and tension tool action of the spindle, under the combined motion conditions, it is significantly more difficult to ensure the continuous and complete sealing of the lip sealing interface under the conditions of ultra-low temperature and high speed. Therefore, overcoming the above difficulties is extremely important for the development of the ultra-low temperature high-speed dynamic sealing rotary joint.

[0004] At present, for low temperature resistant rotary joint and sealing ring, domestic and foreign institutions have invented several structural forms. In 2022, Beijing Hanghua Energy Saving and Environmental Protection Technology Co., Ltd. disclosed "a hydrogen rotary joint applicable to low temperature environment" in invention patent 202210946231.6. The device sets O-ring and gleece ring between the bearings and configures bidirectional oil seal outside the bearing, realizes high sealing transportation of hydrogen in low temperature working condition, but the transmission medium is hydrogen at-20℃, and O-ring is easy to fail due to material embrittlement in liquid nitrogen environment at-196℃. In 2024, Lianyungang Huatai Petroleum Chemical Machinery Co., Ltd. disclosed "a rotary joint special for super low temperature fluid loading and unloading arm" in utility model patent 202422442348.8. The device sets a drive mechanism containing a ball in the mounting hole of the two flanges, realizes compression and retraction of the ball through the inclined channel, realizes super low temperature fluid transmission, and improves the installation and disassembly rate of the joint, but its volume is large and it cannot be installed in the liquid nitrogen inside the spray type electric spindle and swing head. In 2024, Hangzhou Haihong Sealing Element Co., Ltd. disclosed "a sealing ring with low temperature resistance and high sealing performance" in utility model patent 202421580909.4. The device forms a threefold pre-tightening support structure by setting mutually repulsive first and second magnets on the inner side, filling inert gas cavity and reinforcing ring at the bottom, which significantly improves the sealing performance and stability of the sealing ring in low temperature working condition, but it has the risk of sealing failure in-196℃ super low temperature environment, and it is difficult to adapt to complex working conditions such as high speed rotation and axial reciprocating motion. SUMMARY

[0005] The present application proposes a high-speed dynamic sealing rotary joint applicable to super low temperature fluid, which overcomes the problems of single sealing level of rotary joint, easy embrittlement and hardening of sealing ring material in super low temperature environment, and leakage gap of sealing interface due to low temperature deformation.

[0006] The technical scheme of the present application is as follows:

[0007] A high-speed dynamic sealing rotary joint applicable to super low temperature fluid mainly consists of a stationary shaft, a rotating shell, a super low temperature sealing ring, a guide ring and a check ring.

[0008] The center of the stationary shaft is processed with a through axial flow channel as a transmission channel of super low temperature fluid. The circumferential surface of the stationary shaft is sequentially provided with a lip-shaped sealing mating surface, a labyrinth sealing profile and a flow resistance surface from the end to the end, which together constitute a multi-stage sealing structure. The lip-shaped sealing mating surface is a smooth cylindrical surface for interference fit with the super low temperature sealing ring. The labyrinth sealing profile is a non-contact sealing surface with at least one annular groove. The flow resistance surface is a cylindrical surface with constant diameter. The flow resistance surface extends into the delivery flow channel in the center of the rotating shell, and a narrow gap is formed between the flow resistance surface and the delivery flow channel to increase the resistance of super low temperature fluid leakage.

[0009] The inner cavity structure of the rotating shell cooperates with the stationary shaft;

[0010] The guide ring is in the shape of a ring sheet and is installed in a sealing ring installation groove in the rotating shell, and is used for realizing radial support and guidance to the stationary shaft, so as to maintain the coaxiality between the stationary shaft and the rotating shell.

[0011] The blocking ring is an open C-shaped ring and is installed in an annular clamping groove in the rotating shell, and is used for axially limiting and fixing the ultra-low temperature sealing ring and the guide ring, so as to prevent axial displacement of the ultra-low temperature sealing ring under working pressure.

[0012] Further, an annular groove for embedding an anti-shrinkage ring is arranged on the outer periphery of the axial end surface of the base body of the ultra-low temperature sealing ring, and the anti-shrinkage ring can inhibit radial shrinkage of the base body in an ultra-low temperature environment; an annular groove for embedding an O-shaped spring is arranged on the inner periphery of the axial end surface of the base body, and the O-shaped spring is used for providing continuous radial compression force to the sealing lip, so as to ensure that the sealing lip and the lip-shaped sealing surface of the stationary shaft are in close contact; the number of the sealing lips is three.

[0013] Further, four counterbores are uniformly distributed on the circumferences of the end portions of the stationary shaft, and are used for connecting with the fixed end of the device.

[0014] Further, the material of the base body of the ultra-low temperature sealing ring is polytrifluoroethylene.

[0015] Further, the material of the guide ring is polyether ether ketone.

[0016] Further, the material of the blocking ring is 65Mn spring steel.

[0017] Based on a numerical analysis method, the interference amount of the lip-shaped sealing surface c of the stationary shaft 1 and the ultra-low temperature sealing ring 3 is optimized and designed, and the optimized interference amount is obtained. The value is different from the interference amount recommended in the conventional sealing design manual. Through simulation and experimental verification, under the ultra-low temperature working condition, the traditional interference amount will lead to a sealing gap due to material shrinkage and will fail; and the optimized interference amount of the present application can compensate for the material shrinkage and form six good sealing contact bands under the ultra-low temperature, effectively solving the sealing failure problem caused by the ultra-low temperature.

[0018] The present application has the following advantages: through the design of the high-speed dynamic sealing rotary joint of the ultra-low temperature fluid, the integration of the flow blocking, labyrinth, and lip-shaped multi-stage sealing structure is successfully realized in a limited space; by optimizing the base body material of the ultra-low temperature sealing ring and adding the anti-shrinkage ring structure, the shrinkage deformation of the ultra-low temperature sealing ring in the ultra-low temperature environment can be significantly inhibited; and by reasonably adjusting the interference amount of the ultra-low temperature sealing ring, the tight contact of the lip-shaped sealing interface in the ultra-low temperature environment is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Structure diagram of ultra-low temperature high-speed dynamic sealing rotary joint;

[0020] Figure 2 Sectional configuration diagram of ultra-low temperature sealing ring;

[0021] Figure 3 Comparison diagram of sealing gap before and after interference amount optimization of lip-shaped sealing mating surface;

[0022] Figure 4 Schematic diagram of ultra-low temperature sealing ring, wherein (a) is an axonometric view, and (b) is a sectional axonometric view;

[0023] In the figure: 1 - stationary shaft; 2 - rotating shell; 3 - ultra-low temperature sealing ring; 4 - guide ring; 5 - retaining ring; 6 - countersunk hole; 7 - axial flow channel; 8 - lip-shaped sealing mating surface; 9 - labyrinth sealing profile; 10 - flow resistance surface; 11 - conveying flow channel; 12 - narrow gap; 13 - base body; 14 - anti-shrinkage ring; 15 - O-shaped spring; 16 - sealing lip; 17 - sealing gap; 18 - sealing contact band; 19 - sealing ring mounting groove. DETAILED DESCRIPTION

[0024] The specific embodiments of the present application will be described in detail below in combination with the drawings and technical solutions.

[0025] EMBODIMENT

[0026] The ultra-low temperature medium is liquid nitrogen, and the lowest temperature thereof is -196°C; the materials of the stationary shaft 1 and the rotating shell 2 are carburizing steel 20CrMnTi; the material of the ultra-low temperature sealing ring 3 is modified polytrifluoroethylene; and the material of the O-shaped spring 15 is 316 stainless steel.

[0027] As shown in Figure 1 , 2 , the four countersunk holes 6 are uniformly distributed on the end portion of the stationary shaft 1, and are used for connecting with the fixed end of the device; the axial flow channel 7 is processed in the center of the stationary shaft 1, and is used as a transmission channel of the ultra-low temperature fluid; the circumferential surface of the stationary shaft 1 is sequentially provided with the lip-shaped sealing mating surface 8, the labyrinth sealing profile 9 and the flow resistance surface 10 from the end portion to the end, and collectively constitutes a multi-stage sealing structure; wherein the lip-shaped sealing mating surface 8 is a smooth cylindrical surface used for interference fit with the ultra-low temperature sealing ring 3; the labyrinth sealing profile 9 is a non-contact sealing surface with at least one annular groove; and the flow resistance surface 10 is a cylindrical surface with constant diameter, the flow resistance surface 10 extends into the conveying flow channel 11 in the center of the rotating shell 2, and the narrow gap 12 is formed between the flow resistance surface 10 and the conveying flow channel 11, thereby increasing the resistance of the ultra-low temperature fluid leakage;

[0028] The ultra-low temperature sealing ring 3 has an annular groove on the outer circumference of the axial end face of the base 13 for embedding an anti-shrinkage ring 14. The anti-shrinkage ring 14 can suppress the radial shrinkage of the base 13 in the ultra-low temperature environment. The inner circumference of the axial end face of the base 13 has an annular groove for embedding an O-ring spring 15. The O-ring spring 15 is used to provide a continuous radial clamping force for the sealing lip 16 to ensure that the sealing lip 16 and the lip sealing mating surface 8 of the stationary shaft 1 are in close contact. There are three sealing lips 16.

[0029] like Figure 3 As shown, based on numerical analysis, the interference fit between the lip seal mating surface 8 of the stationary shaft 1 and the cryogenic sealing ring 3 is optimized and set to 0.05 mm. This value differs from the 0.02 mm interference fit in conventional sealing designs. Simulation and experimental verification show that under cryogenic conditions, the traditional 0.02 mm interference fit will cause sealing gaps 17 and fail due to material shrinkage; however, the 0.05 mm interference fit described in this invention can compensate for material shrinkage, forming six good sealing contact zones 18 under cryogenic conditions, effectively solving the sealing failure problem caused by cryogenic temperatures.

[0030] The assembly process of the ultra-low temperature high-speed dynamic sealing rotary joint is as follows: First, push the two sets of ultra-low temperature sealing rings 3 and guide rings 4 into the sealing ring mounting groove 19 at the end of the rotating housing 2 in sequence. The ultra-low temperature sealing ring 3 and the sealing ring mounting groove 19 are in an interference fit, and the guide ring 4 and the sealing ring mounting groove 19 are in a clearance fit. Then, use the retaining ring 5 for axial fixation. Finally, press the stationary shaft 1 into the inner hole of the ultra-low temperature sealing ring 3 in an interference fit manner to complete the assembly.

[0031] This invention employs a structure where the stationary end is axially deeply embedded in the flow channel of the rotating end. Combining labyrinth seals and lip seals to form a multi-stage seal significantly improves the dynamic sealing capability in cryogenic media. By selecting cryogenically resistant sealing materials, adding an anti-shrinkage ring structure, adopting a three-lip seal, and rationally designing the interference fit of the sealing surfaces, effective contact of the sealing interface under extreme working conditions is achieved, thus ensuring the dynamic sealing reliability of the cryogenic high-speed rotary joint under complex working conditions. This cryogenic high-speed dynamic sealing rotary joint provides technical support for the reliable operation of functional components such as liquid nitrogen internal spray electric spindles and liquid nitrogen internal spray oscillating heads.

[0032] Obviously, the embodiments described above are only some, not all, of the embodiments in this application. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort should fall within the scope of protection of this application. In summary, the content of this specification should not be construed as a limitation of this application.

Claims

1. A high-speed dynamic sealing rotary joint suitable for cryogenic fluids, characterized in that, The high-speed dynamic sealing rotary joint is mainly composed of a stationary shaft (1), a rotating housing (2), an ultra-low temperature sealing ring (3), a guide ring (4), and a retaining ring (5); The stationary shaft (1) has a through axial flow channel (7) machined in the center, which serves as a transmission channel for cryogenic fluid. The circumferential surface of the stationary shaft (1) consists of a lip seal mating surface (8), a labyrinth seal profile (9), and a flow-blocking surface (10) from end to end, which together form a multi-stage sealing structure. Among them, the lip seal mating surface (8) is a smooth cylindrical surface used for interference fit with the cryogenic sealing ring (3). The labyrinth seal profile (9) is a non-contact sealing surface with at least one annular groove. The flow-blocking surface (10) is a cylindrical surface with a constant diameter. The flow-blocking surface (10) extends into the conveying flow channel (11) in the center of the rotating shell (2). A narrow gap (12) is formed between the flow-blocking surface (10) and the conveying flow channel (11), which increases the resistance to cryogenic fluid leakage. The internal cavity structure of the rotating shell (2) is fitted with the stationary shaft (1); The guide ring (4) is in the shape of annular thin sheet and is installed in the sealing ring mounting groove (19) inside the rotating housing (2) to provide radial support and guidance for the stationary shaft (1) in order to maintain the coaxiality between the stationary shaft (1) and the rotating housing (2); The retaining ring (5) is an open C-shaped ring, which is installed in the annular groove inside the rotating housing (2) to axially limit and fix the cryogenic sealing ring (3) and the guide ring (4) to prevent them from axially displacing under working pressure. The ultra-low temperature sealing ring (3) has an annular groove on the outer circumference of the axial end face of the base (13) for embedding an anti-shrinkage ring (14). The anti-shrinkage ring (14) inhibits the radial shrinkage of the base (13) in the ultra-low temperature environment. The inner circumference of the axial end face of the base (13) has an annular groove for embedding an O-type spring (15). The O-type spring (15) is used to provide a continuous radial clamping force for the sealing lip (16) to ensure that the sealing lip (16) and the lip-shaped sealing mating surface (8) of the stationary shaft (1) are in close contact. There are three sealing lips (16). When assembling the high-speed dynamic sealing rotary joint, firstly, push the two sets of cryogenic sealing rings (3) and guide rings (4) into the sealing ring mounting groove (19) at the end of the rotating housing (2). The cryogenic sealing ring (3) and the sealing ring mounting groove (19) are in an interference fit, and the guide ring (4) and the sealing ring mounting groove (19) are in a clearance fit. Then, the retaining ring (5) is used for axial fixation. Finally, the stationary shaft (1) is pressed into the inner hole of the cryogenic sealing ring (3) in an interference fit manner to complete the assembly.

2. The high-speed dynamic sealing rotary joint suitable for cryogenic fluids according to claim 1, characterized in that, The stationary shaft (1) has four countersunk holes (6) evenly distributed around its end circumference for connection with the fixed end of the device.

3. A high-speed dynamic sealing rotary joint suitable for cryogenic fluids according to claim 1, characterized in that, The substrate (13) of the ultra-low temperature sealing ring (3) is made of polytrifluoroethylene.

4. A high-speed dynamic sealing rotary joint suitable for cryogenic fluids according to claim 1, characterized in that, The guide ring (4) is made of polyether ether ketone.

5. A high-speed dynamic sealing rotary joint suitable for cryogenic fluids according to claim 1, characterized in that, The retaining ring (5) is made of 65Mn spring steel.

Images