Double end shield motor

Abstract

This utility model relates to the field of motor technology, specifically a double-end sealed motor, comprising a base, a first end cover, a second end cover, and a housing. The base has a first connecting end and a second connecting end at its two ends. The first end cover has a first inner connecting ring and a first outer connecting ring. The first inner connecting ring has a first rotating connecting element connected to the first connecting end. The second end cover has a second inner connecting ring and a second outer connecting ring. The second inner connecting ring has a second rotating connecting element connected to the second connecting end. The first outer connecting ring has a first positioning ring groove, and the second outer connecting ring has a second positioning ring groove. The two ends of the housing are respectively connected to the first and second positioning ring grooves. This utility model, through the cooperation of the sealing elements at both ends, forms a reliable double-end sealed structure. This effectively prevents dust, moisture, and other impurities from entering the motor, greatly extending the motor's service life.

Description

Technical Field

[0001] This utility model relates to the field of motor technology, and in particular to a double-end sealed motor. Background Technology

[0002] External rotor motors, as a type of power equipment widely used in many fields such as industry and home appliances, play an important role in modern production and life. However, current external rotor motors still face some problems that urgently need to be solved in practical applications. The assembly process of the end caps of existing external rotor motors is often quite inconvenient. Traditional assembly methods involve multiple complex steps, requiring workers to precisely align multiple components. Even slight deviations can affect the overall performance of the motor, resulting in low assembly efficiency and increased production cycle and cost.

[0003] The poor sealing of the end caps in existing external rotor motors presents a significant problem. This inadequate sealing allows dust, moisture, and other impurities to easily penetrate the motor's interior. This not only accelerates the wear of internal components but can also lead to electrical faults, severely impacting the motor's lifespan and stability. The problems caused by insufficient sealing are particularly pronounced in demanding environmental applications, such as outdoor robotics. Therefore, a new design for the existing motor sealing structure is necessary. Utility Model Content

[0004] To solve the above problems, this utility model forms a reliable double-end sealing structure through the cooperation of sealing elements at both ends. This effectively prevents dust, moisture, and other impurities from entering the motor, protecting the stator and rotor assemblies from corrosion by harsh external environments, greatly extending the motor's service life, and reducing the probability of failures caused by impurities.

[0005] The technical solution adopted by this utility model is as follows: a double-end-cap sealed motor, including a base, a first end cap, a second end cap, and a housing. The base has a first connecting end and a second connecting end respectively at its two ends. The first end cap has a first inner connecting ring and a first outer connecting ring. The first inner connecting ring has a first rotating connecting element connected to the first connecting end. The second end cap has a second inner connecting ring and a second outer connecting ring. The second inner connecting ring has a second rotating connecting element connected to the second connecting end. The first outer connecting ring has a first positioning ring groove, and the second outer connecting ring has a second positioning ring groove. The two ends of the housing are respectively connected to the first positioning ring groove and the second positioning ring groove.

[0006] A further improvement to the above solution is that the first connecting end is provided with a first inner step, the first connecting inner ring is provided with a first outer step, the first inner step and the first outer step are opposite to each other and form a first rotating connecting part, and the first rotating connecting element is disposed on the first rotating connecting part.

[0007] A further improvement to the above solution is that the first connecting outer ring is provided with a first sealing groove on the groove wall surface of the first positioning ring groove, and the first sealing groove is provided with a first sealing ring, which is used to abut against the inner diameter of the outer shell.

[0008] A further improvement to the above solution is that a first positioning block is provided on the outer side of the first connecting outer ring, and multiple first positioning blocks are provided. The multiple first positioning blocks are evenly distributed along the first positioning ring groove in the circumferential direction, and the ends of the first positioning blocks are provided with chamfers.

[0009] A further improvement to the above solution is that a fixing ring is provided on the outer side of the first connecting outer ring, the fixing ring is provided with a mounting countersunk hole, and multiple fixing rings are provided, with the multiple fixing rings spaced apart from the first positioning block.

[0010] A further improvement to the above solution is that the first end cap is provided with a plurality of first connecting holes, one end of which is connected to a first positioning ring groove and is used for screws to pass through and fix to the end of the outer shell.

[0011] A further improvement to the above scheme is that the second connecting end is provided with a second inner step, the second connecting inner ring is provided with a second outer step, the second inner step and the second outer step are opposite to each other and form a second rotating connecting part, and the second rotating connecting element is provided on the second rotating connecting part.

[0012] A further improvement to the above solution is that the second connecting outer ring is provided with a second sealing groove on the groove wall surface of the second positioning ring groove, and the second sealing groove is provided with a second sealing ring, which is used to abut against the inner diameter of the outer shell.

[0013] A further improvement to the above scheme is that a second positioning block is provided on the outer side of the second connecting outer ring, and multiple second positioning blocks are provided. The multiple second positioning blocks are evenly distributed along the second positioning ring groove in the circumferential direction, and the ends of the second positioning blocks are provided with chamfers.

[0014] A further improvement to the above solution is that the second end cap is provided with a plurality of second connecting holes, one end of which is connected to a second positioning ring groove and is used for screws to pass through and fix to the end of the housing.

[0015] The beneficial effects of this utility model are:

[0016] Compared to existing motors, this invention offers superior sealing performance. The first groove at the end of the first rotary connecting element mates with the first sealing element, and the second groove at the end of the second rotary connecting element mates with the second sealing element, forming a reliable double-end sealing structure. This effectively prevents dust, moisture, and other impurities from entering the motor, protecting the stator and rotor assemblies from harsh external environments, significantly extending the motor's lifespan, and reducing the probability of failures caused by impurities. The first end cover is connected to the first connecting end of the base via the first rotary connecting element, and the second end cover is connected to the second connecting end of the base via the second rotary connecting element, ensuring a stable mechanical connection between the end cover and the base. This allows the motor to better withstand vibration and impact during operation, ensuring the overall stability of the motor structure and preventing abnormal noise or performance issues caused by loose connections. The outer casing is connected to the outer sides of the first and second end covers respectively, and its inner wall faces the stator assembly, providing precise installation space for the rotor assembly. This optimizes the internal spatial layout of the motor, facilitating a compact design, improving space utilization, and enabling the motor to achieve higher performance within a limited space. Attached Figure Description

[0017] Figure 1 This is a three-dimensional schematic diagram of the double-end-cap sealed motor of this utility model;

[0018] Figure 2 for Figure 1 Explosion-proof diagram of a double-end sealed motor;

[0019] Figure 3 for Figure 1 An exploded view of a double-end sealed motor from another perspective;

[0020] Figure 4 for Figure 1 Front view schematic diagram of a double-end sealed motor;

[0021] Figure 5 for Figure 4 Sectional view of AA;

[0022] Figure 6 for Figure 4 Enlarged diagram of point A in the diagram;

[0023] Figure 7 for Figure 1 A schematic diagram of the structure of the first sealing element in a double-end sealed motor.

[0024] Figure 8 for Figure 1 A schematic diagram of the structure of the second sealing element of a double-end sealed motor.

[0025] Explanation of reference numerals in the attached drawings: Base 1, First connecting end 11, First inner step 111, Stator connecting part 12, Second connecting end 13, Second inner step 131, First rotary connecting element 14, First sealing element 15, First outer ring sealing ring 151, First sealing lip 1511, First annular buffer groove 1512, First inner ring contact ring 152, First shape fixing ring 1521, Second rotary connecting element 16, Second sealing element 17, Second outer ring sealing ring 171, Second sealing lip 1711, Second annular buffer groove 1712, Second... Inner ring contact ring 172, second shape fixing ring 1721, first end cap 2, first connecting inner ring 21, first outer step 211, first connecting outer ring 22, first positioning ring groove 221, first sealing ring 222, first positioning block 223, fixing mounting ring 224, first connecting hole 23, second end cap 3, second connecting inner ring 31, second outer step 311, second connecting outer ring 32, second positioning ring groove 321, second sealing ring 322, second positioning block 323, second connecting hole 33, stator assembly 4, rotor assembly 5, outer shell 6. Detailed Implementation

[0026] To facilitate understanding of this utility model, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of this utility model are shown in the drawings. However, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this utility model.

[0027] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Figures 1-8As shown, in one embodiment of this utility model, a double-end-cap sealed motor is disclosed, comprising a base 1, a first end cap 2, a second end cap 3, a stator assembly 4, a rotor assembly 5, and a housing 6. The base 1 is provided with a first connecting end 11, a stator connecting portion 12, and a second connecting end 13. The stator assembly 4 is disposed on the stator connecting portion 12. A first rotary connecting element 14 is provided between the first end cap 2 and the first connecting end 11, and a first groove is formed at the end of the first rotary connecting element 14. A first sealing element 15 is disposed in the first groove. A second rotary connecting element 16 is provided between the second end cap 3 and the second connecting end 13, and a second groove is formed at the end of the second rotary connecting element 16. A second sealing element 17 is disposed in the second groove. The two ends of the housing 6 are respectively connected to the outer sides of the first end cap 2 and the second end cap 3, and the inner wall of the housing 6 is opposite to the stator assembly 4. The rotor assembly 5 is disposed on the inner wall of the housing 6. In this embodiment, regarding sealing performance, the first groove at the end of the first rotary connecting element 14 cooperates with the first sealing element 15, and the second groove at the end of the second rotary connecting element 16 cooperates with the second sealing element 17, forming a reliable double-end sealing structure. This effectively prevents dust, moisture, and other impurities from entering the motor, protecting the stator assembly 4 and rotor assembly 5 from corrosion by harsh external environments, greatly extending the motor's service life, and reducing the probability of failures caused by impurities. The first end cover 2 is connected to the first connecting end 11 of the base 1 via the first rotary connecting element 14, and the second end cover 3 is connected to the second connecting end 13 of the base 1 via the second rotary connecting element 16, ensuring a stable mechanical connection between the end cover and the base 1. This allows the motor to better withstand vibration and impact during operation, ensuring the stability of the overall motor structure and preventing abnormal noise or impact on motor performance due to loose connections. The outer casing 6 is connected to the outer sides of the first end cover 2 and the second end cover 3 at both ends, and its inner wall is opposite to the stator assembly 4, providing a precise installation space for the rotor assembly 5, optimizing the internal spatial layout of the motor, which is conducive to the compact design of the motor, improving space utilization, and enabling the motor to perform more efficiently in a limited space.

[0029] The first end cover 2 is provided with a first connecting inner ring 21 and a first connecting outer ring 22. The first connecting end 11 is provided with a first inner step 111, and the first connecting inner ring 21 is provided with a first outer step 211. The first inner step 111 and the first outer step 211 are opposite to each other and form a first rotating connecting part. The first rotating connecting element 14 is provided on the first rotating connecting part. The first connecting outer ring 22 is provided with a first positioning ring groove 221, and one end of the outer shell 6 is connected to the first positioning ring groove 221. In this embodiment, the design of the first rotating connecting part, that is, the first inner step 111 and the first outer step 211 are opposite to each other and the first rotating connecting element 14 is provided, provides a stable and flexible rotating foundation for the operation of the motor. The first rotating connecting element 14 can accurately position and effectively transmit torque, ensuring smooth relative rotation between the motor and the first end cover 2, greatly reducing friction loss and vibration during operation, and improving the overall operating efficiency and stability of the motor. The first positioning ring groove 221 on the first connecting outer ring 22 is connected to one end of the outer shell 6, realizing a tight and precise positioning connection between the motor outer shell 6 and the end cover. This design enhances the overall structural stability of the motor, effectively preventing loosening and displacement between the end cover and the outer casing 6, and also optimizes the motor's sealing performance. Good sealing prevents the intrusion of external dust, moisture, and other impurities, extending the service life of the motor's internal components.

[0030] A first sealing groove is provided on the groove wall of the first positioning ring groove 221 of the first connecting outer ring 22. The first sealing groove is provided with a first sealing ring 222, which is used to abut against the inner diameter of the outer shell 6. A first positioning block 223 is provided on the outer side of the first connecting outer ring 22. Multiple first positioning blocks 223 are provided and are evenly distributed circumferentially along the first positioning ring groove 221. The ends of the first positioning blocks 223 are provided with chamfers. A fixing ring 224 is provided on the outer side of the first connecting outer ring 22. The fixing ring 224 is provided with mounting countersunk holes. Multiple fixing rings 224 are provided and are spaced apart from the first positioning blocks 223. In this embodiment, the first sealing ring 222 in the first sealing groove abuts against the inner diameter of the outer shell 6, which effectively enhances the sealing performance of the motor, prevents dust, moisture and other impurities from entering the motor, reduces electrical faults caused by impurity accumulation, and extends the service life of the motor. Multiple first positioning blocks 223, evenly distributed circumferentially along the first positioning ring groove 221, not only provide precise positioning for the first connecting outer ring 22 during installation, ensuring the accuracy and stability of its installation position, but also feature chamfered ends that facilitate installation, reduce installation difficulty, and improve assembly efficiency. Multiple fixing rings 224, spaced apart from the first positioning blocks 223, and their mounting countersunk holes provide reliable connection points for motor fixation. The mounting countersunk holes allow for easy and secure fixing of the motor in the desired position using bolts or other connectors, ensuring the motor's stability during operation and preventing vibration and other factors from affecting motor performance.

[0031] The second end cover 3 is provided with a second inner connecting ring 31 and a second outer connecting ring 32. The second connecting end 13 is provided with a second inner step 131, and the second inner connecting ring 31 is provided with a second outer step 311. The second inner step 131 and the second outer step 311 are opposite to each other and form a second rotary connecting part. The second rotary connecting element 16 is provided on the second rotary connecting part. The second outer connecting ring 32 is provided with a second positioning ring groove 321, and one end of the outer shell 6 is connected to the second positioning ring groove 321. In this embodiment, the structure formed by the second inner step 131 and the second outer step 311, in conjunction with the second rotary connecting element 16, greatly improves the rotational flexibility and stability between the second end cover 3 and the second connecting end 13 of the motor. This ensures that the second end cover 3 can move accurately during the operation of the motor rotor, reducing vibration and noise caused by unstable connection, and improving the smoothness and reliability of motor operation. The second positioning ring groove 321 on the second outer connecting ring 32 is connected to one end of the outer shell 6, realizing precise positioning and tight fit. It enhances the compactness of the overall motor structure, effectively prevents the decrease in sealing performance caused by loose end caps, ensures a good sealing environment inside the motor, and reduces the intrusion of external dust, moisture and other impurities.

[0032] The second connecting outer ring 32 has a second sealing groove on the groove wall of the second positioning ring groove 321. The second sealing groove contains a second sealing ring 322, which abuts against the inner diameter of the outer casing 6. Multiple second positioning blocks 323 are provided on the outer side of the second connecting outer ring 32, evenly distributed circumferentially along the second positioning ring groove 321. The ends of the second positioning blocks 323 are chamfered. In this embodiment, the second sealing ring 322 within the second sealing groove abuts against the inner diameter of the outer casing 6, effectively preventing external dust, moisture, and other impurities from entering the motor, improving the motor's protection level, reducing electrical faults caused by impurities, and extending the motor's service life. The multiple second positioning blocks 323 evenly distributed circumferentially along the second positioning ring groove 321 can accurately determine the position of the second connecting outer ring 32 in the motor, ensuring the accuracy and stability of component installation and optimizing the overall structural layout of the motor. The second positioning block 323 with a chamfered end plays a guiding role during installation, making component installation smoother, reducing installation difficulty, improving assembly efficiency, reducing the adverse effects of improper installation on motor performance, ensuring stable and efficient operation of the double-end-cover sealed motor, and improving the overall quality of the product.

[0033] The first end cover 2 is provided with multiple first connecting holes 23, one end of which connects to a first positioning ring groove 221 and is used for screws to pass through and fix it to the end of the outer casing 6. The second end cover 3 is provided with multiple second connecting holes 33, one end of which connects to a second positioning ring groove 321 and is used for screws to pass through and fix it to the end of the outer casing 6. In this embodiment, the multiple first connecting holes 23 of the first end cover 2 connect to the first positioning ring groove 221, and the screws pass through to achieve a fixed connection with the end of the outer casing 6, ensuring the mechanical connection between the first end cover 2 and the outer casing 6 is stable. Moreover, the design of the positioning ring groove helps to accurately position the end cover during installation, ensuring that the end cover is installed in the correct position and avoiding motor operation problems caused by installation deviations. Similarly, the multiple second connecting holes 33 of the second end cover 3 cooperate with the second positioning ring groove 321 and are fixed to the end of the outer casing 6 with screws, ensuring the reliability of the connection between the second end cover 3 and the outer casing 6. This connection method of the two end covers works together to effectively enhance the stability of the overall structure of the motor and reduce vibration and noise during operation. The sealing performance has also been improved to prevent external dust, moisture and other impurities from entering the motor.

[0034] See Figure 7As shown, the first sealing element 15 includes a first outer sealing ring 151 and a first inner contact ring 152. The first outer sealing ring 151 and the first inner contact ring 152 are integrally formed. The first outer sealing ring 151 is provided with a first sealing lip 1511, which is used to abut against the wall of the first groove. Specifically, the first outer sealing ring 151 is L-shaped and forms a first annular buffer groove 1512 with the first inner contact ring 152. The cross-sectional shape of the first inner contact ring 152 is S-shaped, and a first shape fixing ring 1521 is provided on the side of the first inner contact ring 152 facing the first outer sealing ring 151. The first shape fixing ring 1521 is used to keep the first inner contact ring 152 in contact with the wall of the first groove. In this embodiment, the L-shaped shape of the first outer sealing ring 151 and the first annular buffer groove 1512 formed therewith effectively enhance the stability and buffering performance of the sealing structure. The first sealing lip 1511 tightly abuts against the wall of the first groove, effectively blocking the intrusion of dust, moisture, and other impurities, preventing them from entering the motor and damaging critical components such as the windings and core, thus greatly improving the cleanliness of the motor's operating environment. The S-shaped cut design of the first inner ring contact ring 152, combined with the first shaped fixing ring 1521 on one side, ensures precise and stable contact with the wall of the first groove. This ensures reliable sealing, prevents media leakage, and improves the overall sealing performance of the motor. Stable sealing performance helps maintain stable internal air pressure, reduces performance fluctuations caused by external environmental factors, and thus extends the motor's service life.

[0035] See Figure 8As shown, the second sealing element 17 includes a second outer sealing ring 171 and a second inner contact ring 172. The second outer sealing ring 171 and the second inner contact ring 172 are integrally formed. The second outer sealing ring 171 is provided with a second sealing lip 1711, which is used to abut against the wall of the second groove. Specifically, the second outer sealing ring 171 is L-shaped and forms a second annular buffer groove 1712 with the second inner contact ring 172. The cross-sectional shape of the second inner contact ring 172 is S-shaped. A second shape fixing ring 1721 is provided on the side of the second inner contact ring 172 facing the second outer sealing ring 171. The second shape fixing ring 1721 is used to keep the second inner contact ring 172 abutting against the wall of the second groove. In this embodiment, the L-shaped second outer sealing ring 171 is integrally formed with the second inner contact ring 172, and together with the second sealing lip 1711, it abuts against the wall of the second groove, forming an effective first line of defense. This effectively prevents dust, moisture, and other external foreign objects from intruding from the motor, greatly improving the internal protection level of the motor and extending its service life. The presence of the second annular buffer groove 1712 not only buffers the vibration and impact generated during motor operation, reducing direct damage to the sealing elements, but also provides a certain degree of heat insulation, reducing the impact of internal temperature changes on sealing performance. The S-shaped cross-section design of the second inner contact ring 172, combined with the second shaped fixing ring 1721, ensures continuous and stable contact with the wall of the second groove. This enhances the reliability of the seal, effectively prevents leakage of lubricating oil inside the motor, and ensures the normal operation of the motor's internal lubrication system.

[0036] The above embodiments only illustrate several implementation methods of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A double-end sealed motor, characterized in that: The device includes a base, a first end cover, a second end cover, a stator assembly, a rotor assembly, and a housing. The base has a first connecting end, a stator connecting portion, and a second connecting end. The stator assembly is disposed in the stator connecting portion. A first rotary connecting element connects the first end cover and the first connecting end, and a first groove is formed at the end of the first rotary connecting element. A first sealing element is disposed in the first groove. A second rotary connecting element connects the second end cover and the second connecting end, and a second groove is formed at the end of the second rotary connecting element. A second sealing element is disposed in the second groove. The two ends of the housing are respectively connected to the outer sides of the first end cover and the second end cover, and the inner wall of the housing is opposite to the stator assembly. The rotor assembly is disposed on the inner wall of the housing.

2. The double-end-cap sealed motor according to claim 1, characterized in that: The first end cap is provided with a first connecting inner ring and a first connecting outer ring. The first connecting end is provided with a first inner step, and the first connecting inner ring is provided with a first outer step. The first inner step and the first outer step are opposite to each other and form a first rotating connecting part. The first rotating connecting element is provided on the first rotating connecting part. The first connecting outer ring is provided with a first positioning ring groove, and one end of the outer shell is connected to the first positioning ring groove.

3. The double-end sealed motor according to claim 2, characterized in that: The first connecting outer ring has a first sealing groove on the groove wall of the first positioning ring groove, and the first sealing groove has a first sealing ring for abutting against the inner diameter of the outer shell; a first positioning block is provided on the outer side of the first connecting outer ring, and multiple first positioning blocks are provided, which are evenly distributed circumferentially along the first positioning ring groove, and the ends of the first positioning blocks are provided with chamfers; a fixing mounting ring is provided on the outer side of the first connecting outer ring, and the fixing mounting ring has a mounting countersunk hole, and multiple fixing mounting rings are provided, which are spaced apart from the first positioning blocks.

4. The double-end sealed motor according to claim 1, characterized in that: The second end cap is provided with a second inner connecting ring and a second outer connecting ring. The second connecting end is provided with a second inner step. The second inner connecting ring is provided with a second outer step. The second inner step and the second outer step are opposite to each other and form a second rotating connecting part. The second rotating connecting element is provided on the second rotating connecting part. The second outer connecting ring is provided with a second positioning ring groove. One end of the outer shell is connected to the second positioning ring groove.

5. The double-end-cap sealed motor according to claim 4, characterized in that: The second connecting outer ring is provided with a second sealing groove on the groove wall of the second positioning ring groove. The second sealing groove is provided with a second sealing ring, which is used to abut against the inner diameter of the outer shell. A second positioning block is provided on the outer side of the second connecting outer ring. Multiple second positioning blocks are provided, and the multiple second positioning blocks are evenly distributed along the circumferential direction of the second positioning ring groove. The ends of the second positioning blocks are provided with chamfers.

6. The double-end-cap sealed motor according to claim 1, characterized in that: The first end cap is provided with a plurality of first connecting holes, one end of which is connected to a first positioning ring groove and is used for screws to pass through and fix to the end of the housing; the second end cap is provided with a plurality of second connecting holes, one end of which is connected to a second positioning ring groove and is used for screws to pass through and fix to the end of the housing.

7. The double-end sealed motor according to claim 1, characterized in that: The first sealing element includes a first outer sealing ring and a first inner contact ring. The first outer sealing ring and the first inner contact ring are integrally formed. The first outer sealing ring is provided with a first sealing lip, which is used to abut against the wall of the first groove.

8. The double-end-cap sealed motor according to claim 7, characterized in that: The first outer sealing ring is L-shaped and forms a first annular buffer groove with the first inner contact ring; the cross-sectional shape of the first inner contact ring is S-shaped, and a first shape fixing ring is provided on the side of the first inner contact ring facing the first outer sealing ring. The first shape fixing ring is used to keep the first inner contact ring in contact with the wall of the first groove.

9. The double-end-cap sealed motor according to claim 1, characterized in that: The second sealing element includes a second outer sealing ring and a second inner contact ring. The second outer sealing ring and the second inner contact ring are integrally formed. The second outer sealing ring is provided with a second sealing lip, which is used to abut against the wall of the second groove.

10. The double-end-cap sealed motor according to claim 9, characterized in that: The second outer sealing ring is L-shaped and forms a second annular buffer groove with the second inner contact ring; the cross-sectional shape of the second inner contact ring is S-shaped, and a second shape fixing ring is provided on the side of the second inner contact ring facing the second outer sealing ring. The second shape fixing ring is used to keep the second inner contact ring in contact with the wall of the second groove.

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