Submersible platform-lifting motor

Abstract

The application relates to the technical field of motor equipment, in particular to a submersible platform lifting motor which comprises a shell, an adjusting structure, a fixing structure, a compensation structure, a protection structure, a wear-resistant structure, a transmission shaft, a rotor and a stator; the adjusting structure is used in cooperation with the fixing structure, the circumferential angle and the radial distance of a limiting part can be adjusted as required, a replaceable blocking column is matched with various specifications of hexagonal cable joints, the torsion caused by water flow and cable pulling is shared by multiple points, cable joint loosening is avoided, the compensation structure can balance the water pressure inside and outside the shell, the shell is prevented from being deformed due to pressure, the wear-resistant structure is arranged to block the inward invasion of silt through concave-convex nested cooperation, the wear-resistant part bears the silt abrasion, the wear-resistant part can be replaced alone after being worn, and the overall service life of the motor is prolonged.

Description

Technical Field

[0001] This invention relates to the field of motor equipment technology, specifically a submersible platform lifting motor. Background Technology

[0002] Submersible platform lifting equipment is a load-bearing lifting device that can be submerged underwater for long-term operation. It can carry personnel, testing instruments and maintenance accessories to adjust the underwater height and position. It is widely used in aquatic operation scenarios such as underwater pile foundation maintenance of offshore wind power, operation and maintenance of aquaculture cages, underwater maintenance of river and lake gates, and near-shore marine scientific research sampling. The entire lifting equipment relies on the output rotational torque of the matching submersible motor to drive the platform to complete the lifting action through the linkage of scissor and winch transmission structure. As the power core of the entire lifting equipment, the submersible motor needs to maintain stable operation under high pressure conditions underwater for a long time.

[0003] However, while threaded connections allow for quick assembly and disassembly and axial locking through threaded engagement, and the internal sealing rings create a reliable waterproof seal, meeting the needs of underwater cable maintenance and replacement, prolonged immersion in water can lead to continuous water flow impacts that pull and shake the cables. Repeated alternating stress can cause the threaded connections to loosen. Simultaneously, the underwater equipment casing is continuously subjected to hydrostatic pressure. The air inside the casing is compressible, and as the water depth increases, a significant pressure difference forms between the inside and outside of the casing. Under unidirectional compressive loads, the casing wall undergoes elastic or plastic deformation. This deformation compresses the internal installation space and squeezes the motor, seals, and transmission components. Furthermore, during static periods, suspended sediment in the water gradually accumulates in the gaps between the casing and the shaft, hardening to form an abrasive layer. When the shaft rotates again during startup, these hard sediment particles become trapped between the shaft, seals, and casing, causing continuous abrasion and wear, ultimately leading to shaft end seal failure and shortening the overall lifespan of the motor. Summary of the Invention

[0004] To address the problems in the prior art, the present invention provides a submersible platform lifting motor.

[0005] The technical solution adopted by the present invention to solve its technical problem is: a submersible platform lifting motor, including a housing, a transmission component on the housing, and an adjustment structure on the housing; The adjustment structure includes a rotating component disposed on the housing, a sliding component disposed on the rotating component, the rotating component being used to adjust the position of the sliding component, a fixing structure disposed on the sliding component, the fixing structure including a fixing component disposed on the sliding component, the sliding component being used to drive the fixing component to move, and the fixing component being used to limit the hexagonal cable connector.

[0006] Specifically, the rotating assembly includes a rotating frame, a worm gear, and a worm. The rotating frame is rotatably connected to the housing, the worm gear is fixedly connected to the rotating frame, and the worm is rotatably connected to the housing, with the worm meshing with the worm gear.

[0007] Specifically, the sliding assembly includes a slip ring and a first lead screw. The slip ring is slidably connected to the rotating frame, and the first lead screw is rotatably connected to the rotating frame. The slip ring and the first lead screw are threadedly connected.

[0008] Specifically, the fixing component includes mounting posts, studs, and stop posts. Three mounting posts are fixedly connected to the slip ring. The mounting posts are slidably connected to the rotating frame. A stud is threaded onto the mounting post, and a stop post is fixedly connected to the stud.

[0009] Specifically, the fixing structure also includes a guide rod fixedly connected within the rotating frame, and the slip ring is slidably connected to the guide rod.

[0010] Specifically, the housing is provided with a compensation structure, which includes a connecting frame fixedly connected to the housing and a fixing frame installed on the connecting frame. A diaphragm is fixedly connected to the fixing frame, and an annular cavity is formed between the connecting frame and the housing. Oil can be added into the annular cavity. A threaded cap is threadedly connected to the connecting frame, and an arc-shaped reinforcing plate is fixedly connected to the fixing frame in a circumferential array.

[0011] Specifically, the connecting frame is provided with a protective structure, which includes a mounting frame detachably connected to the connecting frame and a protective net fixedly connected to the mounting frame. The mounting frame is provided with an annular groove.

[0012] Specifically, a second lead screw is threaded onto the connecting frame, and a limit rod is fixedly connected to the second lead screw. The limit rod cooperates with the annular groove to block and limit the mounting frame. A pull rod is fixedly connected to the mounting frame.

[0013] Specifically, the transmission assembly includes a transmission shaft, a rotor, and a stator. The transmission shaft is rotatably connected to the housing, the rotor is mounted on the transmission shaft, and the stator is mounted on the inner wall of the housing.

[0014] Specifically, a wear-resistant structure is provided between the housing and the drive shaft. The wear-resistant structure includes a protective ring installed on the housing and a plug ring fixedly connected to the protective ring. A wear-resistant ring is installed on the drive shaft, and the wear-resistant ring and the plug ring are rotatably connected. The cross-section of the plug ring is convex. A first sealing ring is fixedly connected to the wear-resistant ring and fits against the drive shaft. A second sealing ring is fixedly connected to the protective ring and fits against the housing. A positioning post is fixedly connected to the housing, and the protective ring and the positioning post are slidably connected.

[0015] The beneficial effects of this invention are: (1) The submersible platform lifting motor of the present invention has an adjustment structure on the housing and a fixing structure on the sliding component. The adjustment structure and the fixing structure are used together to adjust the circumferential angle and radial distance of the limiting component as needed. It is equipped with replaceable baffles to adapt to various specifications of hexagonal cable connectors. It relies on multi-point limiting to distribute the torque caused by water flow and cable pulling, and avoids the cable connector from loosening.

[0016] (2) The submersible platform lifting motor of the present invention has a compensation structure on the shell. The compensation structure can balance the water pressure inside and outside the shell and prevent the shell from deforming under pressure.

[0017] (3) The submersible platform lifting motor described in this invention has a wear-resistant structure between the housing and the transmission shaft. The wear-resistant structure is designed to prevent mud and sand from intruding by interlocking concave and convex parts. The wear-resistant parts bear the wear and tear of mud and sand and can be replaced separately after wear, thereby improving the overall service life of the motor. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Figure 1 A schematic diagram of the overall structure of a preferred embodiment of a submersible platform lifting motor provided by the present invention; Figure 2 This is a schematic diagram of the connection structure between the rotor and the drive shaft of the present invention; Figure 3 This is a schematic diagram of the connection structure between the worm gear and the worm of the present invention; Figure 4 This is a schematic diagram of the connection structure between the mounting post and the slip ring of the present invention; Figure 5 This is a schematic diagram of the connection structure between the mounting frame and the protective netting of the present invention; Figure 6 for Figure 5 The diagram shown is an enlarged view of the structure of part A. Figure 7 This is a schematic diagram of the connection structure between the connecting frame and the housing of the present invention; Figure 8 This is a schematic diagram of the connection structure between the second sealing ring and the protective ring of the present invention; Figure 9 for Figure 8 The diagram shown is an enlarged view of the structure of section B. Figure 10 This is a schematic diagram of the connection structure between the reinforcing plate and the connecting frame of the present invention.

[0020] In the diagram: 1. Housing; 2. Adjustment structure; 201. Rotating frame; 202. Slip ring; 203. Worm gear; 204. Worm; 205. First lead screw; 3. Fixing structure; 301. Mounting post; 302. Stud; 303. Stop post; 304. Guide rod; 4. Compensation structure; 401. Connecting frame; 402. Fixing frame; 403. Diaphragm; 404. Reinforcing plate; 405. Threaded cap; 5. Protective structure; 501. Mounting frame; 502. Protective net; 503. Second lead screw; 504. Limiting rod; 505. Annular groove; 506. Pull rod; 6. Wear-resistant structure; 601. Protective ring; 602. Insertion ring; 603. Wear-resistant ring; 604. First sealing ring; 605. Second sealing ring; 606. Positioning post; 7. Drive shaft; 8. Rotor; 9. Stator. Detailed Implementation

[0021] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0022] like Figure 1 and Figure 4 As shown, a submersible platform lifting motor of the present invention includes a housing 1, a transmission assembly on the housing 1, and an adjustment structure 2 on the housing 1. The adjustment structure 2 includes a rotating assembly on the housing 1, a sliding assembly on the rotating assembly, the rotating assembly being used to adjust the position of the sliding assembly, and a fixing structure 3 on the sliding assembly. The fixing structure 3 includes a fixing assembly on the sliding assembly, the sliding assembly being used to drive the fixing assembly to move, and the fixing assembly being used to limit the movement of the hexagonal cable connector.

[0023] Specifically, such as Figure 1 , Figure 3 and Figure 4As shown, the rotating assembly includes a rotating frame 201, a worm gear 203, and a worm 204. The rotating frame 201 is rotatably connected to the housing 1, and the worm gear 203 is fixedly connected to the rotating frame 201. The worm 204 is rotatably connected to the housing 1, and the worm 204 meshes with the worm gear 203. The sliding assembly includes a slip ring 202 and a first lead screw 205. The slip ring 202 is slidably connected to the rotating frame 201, and the first lead screw 205 is rotatably connected to the rotating frame 201. The slip ring 202 and the first lead screw... The 205 threaded connection includes a mounting post 301, a stud 302, and a stop post 303. Three mounting posts 301 are fixedly connected to the slip ring 202. The mounting posts 301 are slidably connected to the rotating frame 201. Using a hexagonal wrench, the worm gear 204 is rotated. The worm gear 204 drives the worm wheel 203 to rotate synchronously through meshing transmission. The worm wheel 203, in conjunction with the rotating frame 201, completes the overall circumferential rotation, thereby adjusting the placement angle between the slip ring 202 and the fixed structure 3. The worm wheel 202... The meshing transmission structure of 3 and worm gear 204 can maintain the angle state of the rotating frame 201 after adjustment by relying on its own locking characteristics, reducing the angle deviation caused by underwater water flow impact. After the circumferential angle adjustment is completed, the first lead screw 205 set on the rotating frame 201 is rotated with a hexagonal wrench. The first lead screw 205 drives the threaded slip ring 202 to slide axially along the guide rod 304. The guide rod 304 provides guidance support for the sliding action of the slip ring 202, and simultaneously drives the three sets of mounting posts 301, studs 302 and stop posts 303 on the slip ring 202 to move closer to the hexagonal cable connector. The three sets of stop posts 303 arranged circumferentially respectively fit the three sides of the hexagonal cable connector to realize the circumferential limit of the connector. The mounting post 301 is threaded with studs 302, and the studs 302 is fixedly connected with stop posts 303. The fixing structure 3 also includes a guide rod 304 fixedly connected in the rotating frame 201. The slip ring 202 is slidably connected to the guide rod 304.

[0024] Specifically, such as Figure 1 , Figure 7 and Figure 10 As shown, the shell 1 is provided with a compensation structure 4. The compensation structure 4 includes a connecting frame 401 fixedly connected to the shell 1 and a fixing frame 402 installed on the connecting frame 401. A diaphragm 403 is fixedly connected to the fixing frame 402. During underwater operation, the external water pressure squeezes the diaphragm 403 to produce inward deformation. The diaphragm 403 simultaneously squeezes the oil inside the annular cavity, so that the oil pressure inside the cavity and the water pressure outside the water body are kept at a similar level, making the overall force on the shell 1 more balanced and preventing the shell 1 from denting. An annular cavity is formed between the connecting frame 401 and the shell 1. Oil can be added into the annular cavity. A threaded cap 405 is threadedly connected to the connecting frame 401. An arc-shaped reinforcing plate 404 is fixedly connected to the fixing frame 402 in a circumferential array.

[0025] Specifically, such as Figure 1 , Figure 5 and Figure 6As shown, the connecting frame 401 is provided with a protective structure 5. The protective structure 5 includes a mounting frame 501 detachably connected to the connecting frame 401 and a protective net 502 fixedly connected to the mounting frame 501. The mounting frame 501 is provided with an annular groove 505. The mounting frame 501 with the protective net 502 is fastened to the outside of the connecting frame 401. Using a hexagonal wrench to turn the second screw 503, the limiting rod 504 is driven to extend into the annular groove 505 opened in the mounting frame 501, limiting... Positioning rod 504 and annular groove 505 cooperate to form an axial block against mounting frame 501, preventing mounting frame 501 from falling off. Protective net 502 can prevent underwater sand and debris from directly impacting diaphragm 403. A second threaded rod 503 is threaded onto connecting frame 401. Limiting rod 504 is fixedly connected to the second threaded rod 503. Limiting rod 504 cooperates with annular groove 505 to block and limit mounting frame 501. Pull rod 506 is fixedly connected to mounting frame 501.

[0026] Specifically, such as Figure 1 , Figure 2 and Figure 7 As shown, the transmission assembly includes a transmission shaft 7, a rotor 8, and a stator 9. After the equipment is powered on, the stator 9 installed on the inner wall of the housing 1 generates a rotating magnetic field. The magnetic field drives the rotor 8 mounted on the transmission shaft 7 to rotate synchronously. The transmission shaft 7 outputs torque outward, driving the external transmission components to complete the lifting action of the lifting platform. The transmission shaft 7 is rotatably connected to the housing 1, the rotor 8 is installed on the transmission shaft 7, and the stator 9 is installed on the inner wall of the housing 1.

[0027] Specifically, such as Figure 7 , Figure 8 and Figure 9 As shown, a wear-resistant structure 6 is provided between the housing 1 and the drive shaft 7. The wear-resistant structure 6 includes a protective ring 601 installed on the housing 1 and a plug ring 602 fixedly connected to the protective ring 601. A wear-resistant ring 603 is installed on the drive shaft 7. The wear-resistant ring 603 and the plug ring 602 are rotatably connected. The cross section of the plug ring 602 is convex. The wear-resistant ring 603 is fitted on the outside of the drive shaft 7. The convex cross section of the plug ring 602 and the wear-resistant ring 603 form a concave-convex nested rotatable fit structure to prevent mud and sand from getting stuck between the drive shaft 7 and the housing 1, thereby preventing wear and sealing failure caused by mud and sand grinding. A first sealing ring 604 is fixedly connected to the wear-resistant ring 603. The first sealing ring 604 fits against the drive shaft 7. A second sealing ring 605 is fixedly connected to the protective ring 601. The second sealing ring 605 fits against the housing 1. A positioning post 606 is fixedly connected to the housing 1. The protective ring 601 and the positioning post 606 are slidably connected.

[0028] In use, the external cable is first threaded into the hexagonal cable connector and the wiring is completed. After wiring, the adjustment structure 2 of the operating housing 1 limits and fixes the hexagonal cable connector. The operator uses a hexagonal wrench to rotate the worm 204 according to the placement of the hexagonal cable connector. The worm 204 drives the worm wheel 203 to rotate synchronously through meshing transmission. The worm wheel 203, in conjunction with the rotating frame 201, completes the overall circumferential rotation, thereby adjusting the placement angle of the slip ring 202 and the fixing structure 3. The meshing transmission structure of the worm wheel 203 and the worm 204 can maintain the angle state of the rotating frame 201 after adjustment by relying on its own locking characteristics, reducing the angle deviation caused by underwater water flow impact. After the circumferential angle adjustment is completed, the first lead screw 205 set on the rotating frame 201 is rotated using a hexagonal wrench. The first lead screw 205 drives the threaded slip ring. 202 slides axially along the guide rod 304. The guide rod 304 provides guidance and support for the sliding action of the slip ring 202. Simultaneously, it drives the three sets of mounting posts 301, studs 302, and stop posts 303 on the slip ring 202 to move closer to the hexagonal cable connector. The three sets of stop posts 303 arranged circumferentially fit the three sides of the hexagonal cable connector to achieve circumferential limiting of the connector. The operator can replace the stop posts 303 by unscrewing the studs 302 according to the different specifications of hexagonal cable connectors used on site, adapting to the fixing requirements of various specifications of connectors. The three sets of stop posts 303 can share the torsional load generated by cable pulling and water flow impact, disperse the external force borne by a single stop post 303, and extend the service life of the structure. After the limiting is completed, the circumferential movement space of the hexagonal cable connector is completely constrained, and the connector is not easy to loosen during underwater operation. Next, unscrew the threaded cap 405 installed on the side wall of the connecting frame 401 and add insulating hydraulic oil into the annular cavity formed by the connecting frame 401 and the housing 1. During the filling process, continuously expel the air remaining inside the cavity. After the oil is filled, tighten the threaded cap 405. The threaded cap 405, together with a sealing gasket, seals the oil filling opening to prevent water and sediment from entering the annular cavity. The end of the annular cavity is equipped with a fixing frame 402 and a diaphragm 403. Multiple arc-shaped reinforcing plates 404 are arranged around the outer periphery of the fixing frame 402. The arc-shaped reinforcing plates 404 can share the water pressure load applied to the surface of the fixing frame 402 by the external water. During underwater operations, the external water pressure squeezes the diaphragm 403 to produce inward deformation. The diaphragm 403 simultaneously squeezes the oil inside the annular cavity, keeping the oil pressure inside the cavity at a similar level to the external water pressure, making the overall stress on the housing 1 more even. To ensure balance and prevent dents in the shell 1, after the compensation structure 4 is assembled, the mounting frame 501 with the protective net 502 is fastened to the outside of the connecting frame 401. Using a hexagonal wrench, the second screw 503 is turned, causing the limiting rod 504 to extend into the annular groove 505 of the mounting frame 501. The limiting rod 504 and the annular groove 505 cooperate to form an axial block against the mounting frame 501, preventing the mounting frame 501 from falling off. The protective net 502 can isolate underwater sand and debris from directly impacting the diaphragm 403, preventing the diaphragm 403 from being scratched by hard debris. When carrying out maintenance work later, the second screw 503 is turned in the opposite direction to make the limiting rod 504 disengage from the annular groove 505. The mounting frame 501 and the protective net 502 can be removed by pulling the pull rod 506, making it convenient for staff to inspect and replace the diaphragm 403. Finally, the power supply to the transmission components inside the housing 1 is connected, and the motor is started to provide continuous power for the underwater lifting platform. After the equipment is powered on, the stator 9 installed on the inner wall of the housing 1 generates a rotating magnetic field. The magnetic field drives the rotor 8 mounted on the transmission shaft 7 to rotate synchronously. The transmission shaft 7 outputs torque outward, driving the external transmission components to complete the lifting action of the lifting platform. The positioning post 606 set on the housing 1 constrains the assembly position of the protective ring 601. The inner side of the protective ring 601 is fixed with the insertion ring 602. The wear-resistant ring 603 is fitted on the outside of the transmission shaft 7. The insertion ring 602 with a convex cross section and the wear-resistant ring 603 form a concave-convex nested rotational fit structure to prevent mud and sand from getting stuck between the transmission shaft 7 and the housing 1, thereby preventing mud and sand from grinding. Wear and tear can lead to seal failure. The wear-resistant ring 603 rotates synchronously with the drive shaft 7. The first sealing ring 604 is fitted inside the wear-resistant ring 603. The first sealing ring 604 is made of water-swellable rubber. When a small amount of water seeps in, the sealing ring expands slightly and fills the tiny gap between the wear-resistant ring 603 and the drive shaft 7. A second sealing ring 605 is installed at the contact position between the protective ring 601 and the housing 1 to prevent mud and sand from seeping into the housing 1 through the gaps on the outer wall of the protective ring 601. When the motor is running underwater for a long time, the plug ring 602 and the wear-resistant ring 603 bear the abrasion caused by mud and sand. After wear occurs, they can be disassembled and replaced separately without having to completely disassemble the housing 1 and the drive shaft 7, thus reducing the maintenance workload of the underwater equipment.

[0029] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0030] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A submersible platform lifting motor, comprising a housing (1), wherein a transmission assembly is provided on the housing (1), characterized in that, The housing (1) is provided with an adjustment structure (2); The adjustment structure (2) includes a rotating component disposed on the housing (1), a sliding component disposed on the rotating component, the rotating component being used to adjust the position of the sliding component, a fixing structure (3) disposed on the sliding component, the fixing structure (3) including a fixing component disposed on the sliding component, the sliding component being used to drive the fixing component to move, and the fixing component being used to limit the hexagonal cable connector.

2. The submersible platform lifting motor according to claim 1, characterized in that: The rotating assembly includes a rotating frame (201), a worm wheel (203), and a worm (204). The rotating frame (201) is rotatably connected to the housing (1), the worm wheel (203) is fixedly connected to the rotating frame (201), and the worm (204) is rotatably connected to the housing (1). The worm (204) meshes with the worm wheel (203).

3. The submersible platform lifting motor according to claim 2, characterized in that: The sliding assembly includes a slip ring (202) and a first lead screw (205). The slip ring (202) is slidably connected to the rotating frame (201), and the first lead screw (205) is rotatably connected to the rotating frame (201). The slip ring (202) and the first lead screw (205) are threadedly connected.

4. The submersible platform lifting motor according to claim 3, characterized in that: The fixing component includes mounting posts (301), studs (302) and stop posts (303). Three mounting posts (301) are fixedly connected to the slip ring (202). The mounting posts (301) are slidably connected to the rotating frame (201). The mounting posts (301) are threadedly connected to the studs (302). The studs (302) are fixedly connected to the studs (302).

5. A submersible platform lifting motor according to claim 4, characterized in that: The fixed structure (3) also includes a guide rod (304) fixedly connected to the rotating frame (201), and the slip ring (202) is slidably connected to the guide rod (304).

6. The submersible platform lifting motor according to claim 1, characterized in that: The housing (1) is provided with a compensation structure (4), which includes a connecting frame (401) fixedly connected to the housing (1) and a fixing frame (402) installed on the connecting frame (401). A diaphragm (403) is fixedly connected to the fixing frame (402). An annular cavity is formed between the connecting frame (401) and the housing (1). Oil can be added into the annular cavity. A threaded cap (405) is threadedly connected to the connecting frame (401). An arc-shaped reinforcing plate (404) is fixedly connected to the fixing frame (402) in a circumferential array.

7. A submersible platform lifting motor according to claim 6, characterized in that: The connecting frame (401) is provided with a protective structure (5), the protective structure (5) includes a mounting frame (501) detachably connected to the connecting frame (401) and a protective net (502) fixedly connected to the mounting frame (501), and the mounting frame (501) is provided with an annular groove (505).

8. A submersible platform lifting motor according to claim 7, characterized in that: The connecting frame (401) is threaded with a second lead screw (503), and a limit rod (504) is fixedly connected to the second lead screw (503). The limit rod (504) cooperates with the annular groove (505) to block and limit the mounting frame (501). A pull rod (506) is fixedly connected to the mounting frame (501).

9. A submersible platform lifting motor according to claim 4, characterized in that: The transmission assembly includes a transmission shaft (7), a rotor (8) and a stator (9). The transmission shaft (7) is rotatably connected to the housing (1), the rotor (8) is mounted on the transmission shaft (7), and the stator (9) is mounted on the inner wall of the housing (1).

10. A submersible platform lifting motor according to claim 9, characterized in that: A wear-resistant structure (6) is provided between the housing (1) and the drive shaft (7). The wear-resistant structure (6) includes a protective ring (601) installed on the housing (1) and a plug ring (602) fixedly connected to the protective ring (601). A wear-resistant ring (603) is installed on the drive shaft (7). The wear-resistant ring (603) and the plug ring (602) are rotatably connected. The cross section of the plug ring (602) is convex. A first sealing ring (604) is fixedly connected to the wear-resistant ring (603). The first sealing ring (604) fits against the drive shaft (7). A second sealing ring (605) is fixedly connected to the protective ring (601). The second sealing ring (605) fits against the housing (1). A positioning post (606) is fixedly connected to the housing (1). The protective ring (601) and the positioning post (606) are slidably connected.

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