Magnetic fluid sealing device with enhanced sealing performance

Abstract

The invention discloses a magnetofluid sealing device with enhanced sealing performance, which comprises a sealing body, the sealing body is provided with a hollow sealing shell, the sealing shell is sleeved on a rotating shaft, and a sealing cavity is formed between the inner wall surface of the sealing shell and the rotating shaft; a first sealing assembly, a static ring and a second sealing assembly are sequentially arranged in the sealing cavity in the axial direction, a pressure buffering cavity is formed in the contact face of the static ring and the rotating shaft, the radial section of the pressure buffering cavity is smoothly increased in the axial direction, and the large-diameter end of the pressure buffering cavity faces the first sealing assembly; the first sealing assembly and the second sealing assembly form a multi-sealing structure in the axial direction, the sealing performance of the magnetofluid sealing device can be remarkably improved, the application range of magnetofluid sealing is expanded, and the sealing device is further provided with a pressure buffering cavity to reduce damage caused by pressure to the magnetofluid sealing device under the complex working condition.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic fluid sealing, and in particular to a magnetic fluid sealing device with enhanced sealing performance. Background Art

[0002] In the mid-1960s, the United States developed the first stable magnetic fluid, which was used to solve the sealing problem of the movable part of the space suit. The stability of this magnetic fluid was maintained for 6 months, after which magnetic fluid sealing gradually came into people's view. Magnetic fluid sealing uses the characteristics of magnetic fluid's response to magnetic field. Under the action of the magnetic circuit, an "O-type liquid" sealing ring is formed in the sealing gap, thereby playing a sealing role. Magnetic fluid sealing has the characteristics of "zero leakage", long service life, high reliability, low maintenance cost, and strong anti-interference ability. It is currently widely used in aerospace, electronics, chemical industry, machinery, energy, environmental protection, medical and other fields. In recent years, with the continuous expansion of the field of magnetic fluid sealing, the working conditions faced are becoming more and more complex. For example, under complex working conditions such as high pressure, multi-media and micro-vibration, a single magnetic fluid sealing structure can no longer meet the current production applications, and the sealing performance of magnetic fluid decreases with the complexity of the working conditions. Summary of the invention

[0003] The purpose of the present invention is to provide a magnetic fluid sealing device with enhanced sealing performance. The present invention adopts a first sealing component and a second sealing component to form a multiple sealing structure in the axial direction, which can significantly improve the sealing performance of the magnetic fluid sealing device and expand the application scope of the magnetic fluid sealing. The sealing device also has a pressure buffer chamber to reduce the damage to the magnetic fluid sealing device caused by pressure under complex working conditions.

[0004] In order to achieve the above technical objectives, the present invention is implemented through the following technical solutions:

[0005] A magnetic fluid sealing device with enhanced sealing performance comprises a sealing body, wherein the sealing body has a hollow sealing shell, and the sealing shell is sleeved on a rotating shaft;

[0006] A sealing cavity is formed between the inner wall surface of the sealing shell and the rotating shaft, and a first sealing component, a stationary ring and a second sealing component are sequentially arranged in the sealing cavity along the axial direction;

[0007] A pressure buffer cavity is provided on the contact surface between the stationary ring and the rotating shaft, the radial cross section of the pressure buffer cavity increases smoothly along the axial direction, and the large diameter end of the pressure buffer cavity faces the first sealing assembly.

[0008] In the present solution, a sealing cavity is formed between the inner wall surface of the sealing shell and the rotating shaft, and a first sealing component, a static ring and a second sealing component are arranged in sequence along the axial direction in the sealing cavity. The first sealing component, the static ring and the second sealing component form a multiple sealing structure in the sealing cavity. Compared with the existing single magnetic fluid sealing structure, the overall sealing effect is greatly improved, the leakage risk is reduced, the sealing performance of the magnetic fluid sealing device is significantly improved, and the application scope of the magnetic fluid sealing is expanded.

[0009] At the same time, a pressure buffer chamber is provided between the static ring and the rotating shaft between the first sealing component and the second sealing component. The radial cross-section of the pressure buffer chamber increases smoothly along the axial direction. By utilizing the pressure difference principle, when the pressure increases, the pressure is squeezed from the narrow part of the pressure buffer chamber to the large space of the chamber, and the pressure is released instantly. Once one of the sealing structures fails, the impact of the instantaneous pressure on the magnetic fluid seal can be buffered, thereby minimizing the damage to the sealing performance of the sealing device.

[0010] As a further technical solution of the magnetic fluid sealing device, since the volume of the magnetic fluid has a great influence on the sealing performance of the magnetic fluid, in order to ensure the sealing performance of the magnetic fluid sealing device and extend the service life, a magnetic fluid storage cavity body is provided on the outside of the first sealing component, and a magnetic fluid storage cavity is formed between the magnetic fluid storage cavity body and the first sealing component. The outer wall of the magnetic fluid storage cavity is connected to a first compensation device, and magnetic fluid is injected into the magnetic fluid storage cavity through the first compensation device, so as to replenish the lost magnetic fluid in time.

[0011] As a further technical solution of the magnetic fluid sealing device, the outer end of the magnetic fluid storage cavity body abuts against the inner wall surface of the sealing shell, and the inner end of the magnetic fluid storage cavity body extends toward the rotating shaft and is in the shape of an inner groove facing the first sealing component;

[0012] Among them, balls are evenly arranged between the inner end of the magnetic fluid storage chamber body and the rotating shaft, and the balls rotate synchronously with the rotating shaft.

[0013] In the present embodiment, the inner end of the magnetic fluid storage chamber body extends toward the rotating shaft and is in the shape of an inner groove facing the first sealing component. The inner end of the magnetic fluid storage chamber body is close to the sealing gap of the first sealing component through a smooth transition surface. At the same time, balls are evenly arranged between the inner end of the magnetic fluid storage chamber body and the rotating shaft. The balls rotate synchronously with the rotating shaft. The rotating balls can not only reduce the friction with the rotating shaft, but also generate disturbances toward the sealing gap of the first sealing component, so as to facilitate the magnetic fluid to flow to the sealing gap, thereby achieving the purpose of actively replenishing the magnetic fluid.

[0014] As a further technical solution of the magnetic fluid sealing device, a rubber ring is arranged between the magnetic fluid storage cavity body and the end wall of the sealing cavity to buffer the squeezing force between the sealing shell and the magnetic fluid storage cavity body, thereby protecting the cavity wall of the magnetic fluid storage cavity.

[0015] As a further technical solution of the magnetic fluid sealing device, since oil substances will inevitably evaporate and flow away during the operation of the sealing device, affecting the sealing effect of the second sealing component, in order to ensure its sealing effect, the outer side of the second sealing component is connected to a second compensation device, and the second compensation device inputs oil substances into the sealing surface of the second sealing component.

[0016] As a further technical solution of the magnetic fluid sealing device, an oil accumulation groove for storing oil substances is provided on the side wall surface of the static ring close to the second sealing component to extend the sealing life of the second sealing component.

[0017] As a further technical solution of the magnetic fluid sealing device, a bearing group and a cover plate are sequentially arranged at one end of the second sealing component away from the static ring;

[0018] Wherein, the bearing group comprises angular contact ball bearings arranged in pairs, and inner and outer bearing spacers are arranged between the angular contact ball bearings arranged in pairs;

[0019] Wherein, an O-ring is arranged between the cover plate and the end surface of the sealing shell, and a stopper extending toward the sealing cavity is arranged on the cover plate, and the stopper presses the bearing group.

[0020] In this solution, inner and outer bearing spacers are arranged between the angular contact ball bearings arranged in pairs, and the inner and outer bearing spacers connect the grooves of the two angular contact ball bearings. When the second compensation device inputs oil substances into the second sealing component, it can also lubricate the angular contact ball bearings. The stopper arranged on the cover plate presses the bearing group, which also prevents the first sealing component and the second sealing component from moving in the axial direction.

[0021] As a further technical solution of the magnetic fluid sealing device, in order to improve the sealing performance, the first sealing assembly includes a plurality of laterally spaced pole shoes, the outer circumferential surfaces of the pole shoes are in contact with the inner wall surface of the sealing shell, and permanent magnets are sandwiched between adjacent pole shoes, and pole teeth are radially arranged on the inner circumferential surface of each pole shoe, and there is a gap between the pole teeth and the outer surface of the rotating shaft, and the gap is filled with magnetic fluid.

[0022] As a further technical solution of the magnetic fluid sealing device, in order to improve the sealing performance, the second sealing assembly includes a labyrinth sealing static ring and a labyrinth sealing dynamic ring arranged in pairs, and the labyrinth sealing dynamic ring moves synchronously with the rotating shaft;

[0023] The labyrinth seal static ring abuts against the inner wall surface of the sealing housing, and the labyrinth seal static ring and the labyrinth seal dynamic ring mesh with each other through meshing teeth and meshing grooves with different cross-sectional shapes;

[0024] Wherein, the meshing surface is a sealing surface, a felt is provided on the surface of the sealing surface, and oil substances are injected into the felt.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] 1. The present invention adopts a sealing structure in which multiple sealing components are arranged in parallel within a limited axial space to form a multiple sealing structure, which can significantly improve the sealing performance of the magnetic fluid sealing device and expand the application scope of the magnetic fluid sealing.

[0027] 2. A pressure buffer chamber is provided between the static ring and the rotating shaft of the present invention. The radial cross-section of the pressure buffer chamber increases smoothly along the axial direction. By utilizing the pressure difference principle, when the pressure increases, the pressure is squeezed from the narrow part of the pressure buffer chamber to the large space of the chamber, and the pressure is released instantaneously. Once one of the sealing structures fails, the impact of the instantaneous pressure on the magnetic fluid seal can be buffered, thereby minimizing the damage to the sealing performance of the sealing device.

[0028] 3. The first sealing component and the second sealing component of the present invention also have a magnetic fluid compensation structure, which can effectively improve the sealing failure of the traditional magnetic fluid sealing structure caused by the volatilization of the magnetic fluid-based carrier liquid and the loss of the magnetic fluid, and significantly extend the service life of the magnetic fluid sealing device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0030] Figure 1 It is a structural diagram of the present invention;

[0031] Figure 2 for Figure 1 An enlarged schematic diagram of a magnetic fluid compensation structure marked as A in FIG.

[0032] Figure 3 for Figure 1 An enlarged schematic diagram of the static ring marked as B in FIG.

[0033] Figure 4 for Figure 1 An enlarged schematic diagram of the oil adding device marked as C;

[0034] Figure 5 for Figure 1 An enlarged schematic diagram of the labyrinth seal static ring and labyrinth seal dynamic ring marked as D in the figure.

[0035] Marks and corresponding parts names in the attached drawings:

[0036] 1-rotating shaft, 2-rubber ring, 3-sealed housing, 4-first compensation device, 5-permanent magnet, 6-pole shoe, 7-magnetic fluid, 8-second compensation device, 9-angular contact ball bearing, 10-inner and outer bearing spacers, 11-nut, 12-stud, 13-cover plate, 14-O-ring, 15-labyrinth seal static ring, 16-labyrinth seal dynamic ring, 17-static ring, 18-first magnetic isolation ring, 19-second magnetic isolation ring, 20-magnetic fluid storage chamber body, 21-magnetic circuit, 22-pole teeth, 41-sealing nut, 42-injection port sealing gasket, 43-locking nut, 44-injection pipe, 81-sealing cover, 82-sealing gasket, 83-oil pipeline, 171-oil storage tank, 172-pressure buffer chamber, 201-ball, 1516-sealing surface. DETAILED DESCRIPTION

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0038] Example 1

[0039] This embodiment 1 provides a magnetic fluid sealing device with enhanced sealing performance, such as Figure 1 As shown, it includes a sealing body, which has a hollow sealing shell 3. The sealing shell 3 is a hollow columnar body. The sealing shell 3 is made of aluminum alloy as a whole, which has the effect of reducing leakage magnetic flux and reducing weight. The sealing shell 3 includes an outer wall and two through end faces, one end of the two through end faces is closed and the other end is open. A through hole is opened in the center of the closed end face of the sealing shell 3, and the rotating shaft 1 penetrates from the through hole to the inner cavity of the sealing shell 3. At the same time, a closed sealing cavity is formed between the outer surface of the rotating shaft 1 and the inner wall of the sealing shell 3. A first sealing component, a stationary ring 17 and a second sealing component are arranged in sequence from the inside to the outside along the axial direction in the sealing cavity. The first sealing component, the stationary ring 17 and the second sealing component form a multiple sealing structure in the sealing cavity.

[0040] Please refer to Figure 1As shown, the first sealing component includes three or more laterally spaced pole shoes 6, the outer circumferential surfaces of the pole shoes 6 are in contact with the inner wall surface of the sealing shell 3, and permanent magnets 5 are sandwiched between adjacent pole shoes 6. Pole teeth 22 are radially arranged on the inner circumferential surface of each pole shoe 6, and there is a gap between the pole teeth 22 and the outer surface of the rotating shaft 1, and the gap is filled with magnetic fluid 7. A sealing structure is formed between the sealing shell 3, the permanent magnets 5, the pole shoes 6, the magnetic fluid 7, the pole teeth 22, and the rotating shaft 1, and a plurality of magnetic circuits 21 are formed inside the sealing structure.

[0041] Please refer to Figure 1 As shown, the second sealing component includes a plurality of pairs of labyrinth seal static rings 15 and labyrinth seal dynamic rings 16. The labyrinth seal dynamic rings 16 move synchronously with the rotating shaft 1. The labyrinth seal static rings 15 abut against the inner wall surface of the sealing housing 3. The labyrinth seal static rings 15 and the labyrinth seal dynamic rings 16 mesh with each other through meshing teeth and meshing grooves with different cross-sectional shapes. The meshing surface at the meshing point is a sealing surface 1516. A felt is provided on the surface of the sealing surface 1516. The felt is injected with oil substances to form a sealing structure combining a labyrinth seal and a felt seal, which constitutes the first seal of this sealing device. In this part of the experiment, perfluoropolyether Fomblin YLVAC25 / 6 was injected into the felt surface to achieve a good sealing effect.

[0042] In order to compensate for the volatile magnetic fluid carrier fluid and the lost magnetic fluid 7 during the operation of the magnetic fluid sealing device, please refer to Figure 1 and Figure 2 As shown, a magnetic fluid storage chamber body 20 is also provided on the outside of the above-mentioned first sealing component, and the outer end of the magnetic fluid storage chamber body 20 abuts against the inner wall surface of the sealing shell 3, and the inner end of the magnetic fluid storage chamber body 20 extends toward the rotating shaft 1 and is an inner groove shape facing the first sealing component. A magnetic fluid storage chamber is formed between the inner groove shape and the first sealing component, and the outer wall of the magnetic fluid storage chamber is connected to a first compensation device 4, and a magnetic fluid 7 is injected into the magnetic fluid storage chamber through the first compensation device 4. In this embodiment, as Figure 2 As shown, the compensation device 4 includes a sealing nut 41, an injection port sealing gasket 42, a locking nut 43, and an injection pipe 44. One end of the injection pipe 444 is connected to the inner and outer walls of the sealing shell 3 and is connected to the hole in the magnetic fluid storage chamber. The other end of the injection pipe 44 is connected to the sealing nut 41. An injection port sealing gasket 42 is clamped between the sealing nut 41 and the injection pipe 44. A locking nut 43 is provided outside the sealing nut 41 to lock the sealing nut 41, so as to prevent liquid leakage from the first compensation device 4 during the fluid replenishment process.

[0043] Similarly, during the operation of the sealing device, the oil substances will inevitably volatilize and flow away, affecting the sealing effect of the second sealing component. To ensure its sealing effect, the outer side of the second sealing component is connected to the second compensation device 8, and the second compensation device 8 inputs the oil substances to the sealing surface 1516 of the second sealing component. In this embodiment, Figure 4 As shown, the second compensation device 8 includes a sealing cover 81, a sealing gasket 82, and an oil pipe 83. One end of the oil pipe 83 is embedded in the sealing housing 3, and the other end is tightly connected to the sealing cover 81. A sealing gasket 82 is sandwiched between the oil pipe 83 and the sealing cover 81.

[0044] In order to make the magnetic fluid 7 actively flow to the sealing gap of the first sealing component, please refer to Figure 2 As shown, the inner end of the magnetic fluid storage chamber body 20 is close to the sealing gap of the first sealing component through a smooth transition surface. At the same time, balls 201 are evenly arranged between the inner end of the magnetic fluid storage chamber body 20 and the rotating shaft 1. The balls 201 rotate synchronously with the rotating shaft 1. When the balls 201 rotate, they can not only reduce the friction with the rotating shaft 1, but also generate disturbances flowing to the sealing gap of the first sealing component, so as to facilitate the magnetic fluid 7 to flow to the sealing gap.

[0045] At the same time, this embodiment is to minimize the damage to the sealing performance of the sealing device. Figure 1 and Figure 3 As shown, a pressure buffer chamber 172 is provided on the contact surface between the stationary ring 17 and the rotating shaft 1 between the first sealing component and the second sealing component, and an oil accumulation groove 171 for storing oil substances is provided on the side wall surface of the stationary ring 17 close to the second sealing component. The radial cross-section of the pressure buffer chamber 172 increases smoothly along the axial direction, and the large diameter end of the pressure buffer chamber 172 faces the first sealing component. When the pressure increases, the pressure is squeezed from the narrow part of the pressure buffer chamber 172 to the large space of the cavity, and the pressure is released instantly. Once one of the sealing structures fails, the impact of the instantaneous pressure on the magnetic fluid seal can be buffered.

[0046] In this embodiment, in order to improve the sealing effect of the magnetic fluid sealing device, please refer to Figure 1As shown, a bearing group and a cover plate 13 are sequentially arranged at one end of the second sealing component away from the stationary ring 17; the bearing group includes angular contact ball bearings 9 arranged in pairs, the outer rings of the angular contact ball bearings 9 are in contact with the inner wall surface of the sealing housing 3, the inner rings of the angular contact ball bearings 9 rotate synchronously with the rotating shaft 1, and inner and outer bearing spacers 10 are arranged between the angular contact ball bearings arranged in pairs, so as to separate the adjacent bearing inner rings and bearing outer rings in sequence; at the same time, the cover plate 13 and the sealing housing 3 are fastened and connected by nuts 11 and studs 12, and the nuts 11 and studs 12 are evenly distributed along the axis, an O-ring 14 is arranged between the cover plate 13 and the end face of the sealing housing 3, and a stopper extending to the sealing cavity is arranged on the cover plate 13, and the bearing group is pressed by the stopper to prevent the first sealing component and the second sealing component from moving in the axial direction.

[0047] Example 2

[0048] In order to balance the slight vibration and imbalance caused by the labyrinth seal dynamic ring 16 during the rotation process and prevent friction and collision with the labyrinth seal static ring 15, this embodiment 2 provides another magnetic fluid sealing device with enhanced sealing performance, such as Figure 1-Figure 5 As shown, the sealing surface 1516 is provided with elastic and tough felt, and the elasticity and toughness of the felt are used to balance some small vibrations and imbalances caused by the labyrinth seal dynamic ring 16 during the rotation process.

[0049] At the same time, in this embodiment, in order to reduce the mutual interference of the magnetic field between adjacent components and make the magnetic field distribution more reasonable and concentrated, thereby improving the effect of magnetic fluid sealing, a first magnetic isolation ring 18 is arranged between the pole shoe 6 and the static ring 17, and a second magnetic isolation ring 19 is arranged between the magnetic fluid storage cavity body 20 and the pole shoe 6. The magnetic isolation ring can also play a buffering role, protect the surface of adjacent components, reduce wear and damage, and extend the service life of the components, thereby ensuring the normal operation and sealing performance of the sealing device.

[0050] In some embodiments, a rubber ring 2 is provided between the magnetic fluid storage chamber body 20 and the end wall of the sealed chamber. During the operation of the sealing device, due to temperature changes, thermal expansion of components, etc., an extrusion force may be generated between the sealed shell 3 and the magnetic fluid storage chamber body 20. The rubber ring 2 can absorb and buffer these extrusion forces, protect the cavity wall of the magnetic fluid storage chamber body 20, and prevent it from being damaged. The rubber ring 2 also has an auxiliary sealing function to prevent the magnetic fluid 7 from leaking from the gap between the sealed shell 3 and the magnetic fluid storage chamber body 20, thereby ensuring the sealing of the magnetic fluid storage chamber and thus ensuring the sealing performance of the entire sealing device.

[0051] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A magnetic fluid sealing device with enhanced sealing performance, characterized in that: It comprises a sealing body, the sealing body having a hollow sealing shell (3), the sealing shell (3) being sleeved on a rotating shaft (1); A sealing cavity is formed between the inner wall surface of the sealing housing (3) and the rotating shaft (1), and a first sealing component, a stationary ring (17) and a second sealing component are sequentially arranged in the sealing cavity along the axial direction; A pressure buffer chamber (172) is provided on the contact surface between the stationary ring (17) and the rotating shaft (1), the radial cross section of the pressure buffer chamber (172) increases smoothly along the axial direction, and the large diameter end of the pressure buffer chamber (172) faces the first sealing assembly.

2. A magnetic fluid sealing device with enhanced sealing performance according to claim 1, characterized in that: A magnetic fluid storage chamber body (20) is arranged on the outside of the first sealing component, a magnetic fluid storage chamber is formed between the magnetic fluid storage chamber body (20) and the first sealing component, and the outer wall of the magnetic fluid storage chamber is connected to a first compensation device (4), and magnetic fluid (7) is injected into the magnetic fluid storage chamber through the first compensation device (4).

3. A magnetic fluid sealing device with enhanced sealing performance according to claim 2, characterized in that: The outer end of the magnetic fluid storage chamber body (20) abuts against the inner wall surface of the sealed housing (3), and the inner end of the magnetic fluid storage chamber body (20) extends toward the rotating shaft (1) and is in the shape of an inner groove facing the first sealing component; Among them, balls (201) are evenly arranged between the inner end of the magnetic fluid storage chamber body (20) and the rotating shaft (1), and the balls (201) rotate synchronously with the rotating shaft (1).

4. A magnetic fluid sealing device with enhanced sealing performance according to claim 3, characterized in that: A rubber ring (2) is provided between the magnetic fluid storage chamber body (20) and the end wall surface of the sealing chamber.

5. A magnetic fluid sealing device with enhanced sealing performance according to claim 1, characterized in that: The outer side of the second sealing component is connected to a second compensation device (8), and the second compensation device (8) inputs oil substances to the sealing surface (1516) of the second sealing component.

6. A magnetic fluid sealing device with enhanced sealing performance according to claim 5, characterized in that: An oil accumulation groove (171) for storing oil substances is provided on the side wall surface of the stationary ring (17) close to the second sealing component.

7. A magnetic fluid sealing device with enhanced sealing performance according to claim 5, characterized in that: A bearing group and a cover plate (13) are sequentially arranged at one end of the second sealing assembly away from the stationary ring (17); The bearing group comprises angular contact ball bearings (9) arranged in pairs, and inner and outer bearing spacers (10) are arranged between the angular contact ball bearings (9) arranged in pairs; An O-ring (14) is provided between the cover plate (13) and the end surface of the sealing housing (3), and a stopper extending toward the sealing cavity is provided on the cover plate (13), and the stopper presses the bearing assembly.

8. A magnetic fluid sealing device with enhanced sealing performance according to any one of claims 1 to 7, characterized in that: The first sealing component comprises a plurality of laterally spaced pole shoes (6), the outer circumferential surfaces of the pole shoes (6) are in contact with the inner wall surface of the sealing housing (3), and a permanent magnet (5) is sandwiched between adjacent pole shoes (6). A pole tooth (22) is radially arranged on the inner circumferential surface of each pole shoe (6), a gap exists between the pole tooth (22) and the outer surface of the rotating shaft (1), and a magnetic fluid (7) is filled in the gap.

9. A magnetic fluid sealing device with enhanced sealing performance according to any one of claims 1 to 7, characterized in that: The second sealing assembly comprises a labyrinth sealing static ring (15) and a labyrinth sealing dynamic ring (16) arranged in pairs, wherein the labyrinth sealing dynamic ring (16) moves synchronously with the rotating shaft (1); The labyrinth seal static ring (15) abuts against the inner wall surface of the sealing housing (3), and the labyrinth seal static ring (15) and the labyrinth seal dynamic ring (16) mesh with each other through meshing teeth and meshing grooves having different cross-sectional shapes; The meshing surface is a sealing surface (1516), a felt is provided on the surface of the sealing surface (1516), and oil is injected into the felt.

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