Starter assembly for chain saw

Abstract

The starter assembly for the chain saw comprises a protective cover shell, a center shaft, a handle assembly and a ratchet wheel assembly, a connecting end plate is arranged at one end of the center shaft, and the protective cover shell wraps the outer side of the connecting end plate in an injection molding mode; the handle assembly comprises a handle, a traction rope and a rope wheel, the traction rope is wound on the rope wheel, one end of the traction rope is connected with the handle, and the other end of the traction rope is connected with the rope wheel; the ratchet wheel assembly is clamped with the rope wheel, and synchronous rotation of the ratchet wheel assembly and the rope wheel is achieved. The outer side of the connecting end plate of the center shaft is directly wrapped with the protective cover shell through the injection molding technology, so that the protective cover shell and the center shaft are formed into an integral structure through injection molding, the connecting stability is enhanced, the integral reliability and durability of the starter assembly are improved, the handle assembly facilitates operation of a user, and the service life of the starter assembly is prolonged. Due to the design of the ratchet wheel assembly, the starter can achieve one-way transmission in the starting process, reverse rotation is prevented, and stability and reliability in the starting process are ensured.

Description

Technical Field

[0001] This utility model belongs to the field of chainsaw technology, specifically relating to a chainsaw starter assembly. Background Technology

[0002] In forestry, horticulture, and related outdoor operations, chainsaws are widely used as efficient and convenient power tools for tasks such as tree felling and branch pruning. The starting performance of a chainsaw directly affects its ease of use and work efficiency; therefore, the starter is a crucial component. Traditional chainsaw starter assemblies often have an unstable connection between the central shaft and the protective housing. A common method is to connect the protective housing to the central shaft using additional fasteners, such as bolts and nuts. This connection method not only increases the number of installation steps and parts, leading to higher production costs, but also, during long-term use, due to the complexity of the chainsaw's working environment, such as vibration, dust, and humidity, the fasteners are prone to loosening or even falling off. This affects the protective housing's ability to protect internal components and reduces the reliability of the starter assembly. Utility Model Content

[0003] The purpose of this utility model is to solve the above-mentioned technical problems existing in the prior art and provide a starter assembly for chainsaws. The structure is ingenious and reasonable, and highly practical. The central shaft enables precise positioning and installation of the handle assembly and ratchet assembly, and is used for the rotation of the rope wheel and ratchet assembly. Furthermore, the protective cover is directly wrapped around the outside of the connecting end plate of the central shaft through injection molding, so that the protective cover and the central shaft are injection molded into an integral structure, which enhances the connection stability and improves the overall reliability and durability of the starter assembly. The handle assembly facilitates user operation, and the design of the ratchet assembly enables the starter to achieve unidirectional transmission during the start-up process, preventing reverse rotation and ensuring the stability and reliability of the start-up process.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] A chainsaw starter assembly includes a protective housing, a central shaft, a handle assembly, and a ratchet assembly. One end of the central shaft has a connecting end plate. The protective housing is injection-molded and wrapped around the connecting end plate to secure the central shaft to the protective housing. The handle assembly includes a handle, a traction rope, and a pulley. The traction rope is wound around the pulley, with one end connected to the handle and the other end connected to the pulley. The pulley is fitted onto the central shaft and rotates around it. The ratchet assembly is fitted onto the central shaft and rotates around it, engaging with the pulley. The system achieves synchronous rotation of the ratchet assembly and the pulley; its ingenious and reasonable structural design is highly practical. The central shaft enables precise positioning and installation of the handle assembly and ratchet assembly. Furthermore, the protective cover is directly wrapped around the outside of the connecting end plate of the central shaft through injection molding, making the protective cover and the central shaft an integral structure, enhancing the connection stability, improving the overall reliability and durability of the starter assembly, and facilitating user operation. The design of the ratchet assembly enables unidirectional transmission during the starter process, preventing reverse rotation and ensuring the stability and reliability of the starter process.

[0006] Furthermore, the connecting end plate and the central shaft are integrally formed. The connecting end plate has holes, and the integral forming facilitates actual processing, ensuring structural strength and overall stability. The holes and the injection molding material of the protective cover form an interlocking structure, enhancing the connection strength between the protective cover and the connecting end plate.

[0007] Furthermore, a reset spring is installed inside the protective cover. One end of the reset spring is fixed inside the protective cover, and the other end of the reset spring abuts against the rope wheel. The handle drives the rope wheel to rotate through the traction rope, and the rope wheel then drives the ratchet seat to rotate. The ratchet seat drives the ratchet to rotate through the drive spring. The ratchet starts the engine through the pawl and the snap ring. At the same time, the rope wheel also drives the abutting reset spring to store power. After starting, the rope wheel resets and retracts the winding traction rope under the action of the reset spring.

[0008] Furthermore, the ratchet assembly includes a ratchet seat and a ratchet. The ratchet is located in the cavity of the ratchet seat, and a drive torsion spring is installed in the cavity of the ratchet seat. One end of the drive torsion spring is fixed and limited in the ratchet seat. An abutment groove is provided on the outer side of the ratchet, and the other end of the drive torsion spring abuts and is limited in the abutment groove. The structure is ingeniously and reasonably designed. One end of the drive torsion spring is fixed and limited in the ratchet seat, and the other end abuts the abutment groove of the ratchet, forming a stable transmission connection. The drive torsion spring is used to store energy. When the drive torsion spring stores a certain amount of energy, the force at the end of the drive torsion spring that contacts the ratchet is large enough, and the ratchet will drive the flywheel to rotate through the pawl and the snap ring, thereby starting the engine. A cover plate is provided on the ratchet seat, and the cover plate is connected to the ratchet seat by bolts. Assembly is convenient, and the removal of the cover plate allows for convenient installation and removal of the drive torsion spring in the cavity.

[0009] Furthermore, the pulley is equipped with a pawl, and the ratchet seat is equipped with a shifting groove. The protrusion on the pawl is locked into the shifting groove, realizing the engagement between the ratchet seat and the pulley. When the pulley rotates, the pawl drives the ratchet seat to rotate synchronously. The protrusion is embedded in the shifting groove, realizing a rigid connection between the pulley and the ratchet seat. This ensures that the pawl immediately drives the ratchet seat to rotate synchronously through the shifting groove the instant the pulley rotates, ensuring starting efficiency. Preferably, there are at least two protrusions, which are evenly distributed on the outer side of the pawl and cooperate with multiple shifting grooves of the ratchet seat.

[0010] Furthermore, the ratchet is mounted on the central shaft, and two pawls are symmetrically arranged at the center of the ratchet. One end of each pawl is limited to rotation on the ratchet. In the initial state, one side of the pawl is attached to the corresponding side of the boss at the center of the ratchet, so that the pawl can only rotate in one direction. A retaining ring is provided between the two pawls. A limiting ring groove is provided at the end of the central shaft extending out of the ratchet. The retaining ring is locked in the limiting ring groove. When the ratchet rotates, the two pawls are restricted by the retaining ring to rotate intermittently on the ratchet. The flywheel is provided with a rotating tooth groove. During the intermittent rotation of the pawls, they are locked into the rotating tooth groove, driving the flywheel to rotate. The structure is compact and reasonable. The limiting ring groove is used for the locking and installation of the retaining ring. The design is ingenious, and the installation and disassembly are convenient, as are subsequent maintenance and replacement.

[0011] Furthermore, the pawl is provided with a protruding post, and adjustment gaps are provided on both sides of the retaining spring. The protruding post is located in the adjustment gap, and a limiting groove is provided on the adjustment gap. When the ratchet rotates, the protruding post on the pawl gradually moves into the limiting groove and abuts against the end side wall of the limiting groove. When the ratchet continues to rotate, the pawl rotates intermittently on the ratchet due to the abutment and restriction of the protruding post by the limiting groove.

[0012] Furthermore, shims are provided between the ratchet seat and the rope wheel, and between the snap ring and the ratchet. The shims are fitted onto the central shaft. The design of the shims can improve the structural stability and reliability of the assembled starter assembly.

[0013] Furthermore, the starter assembly also includes a flywheel cover, which is locked inside a protective cover. The flywheel cover has a protruding ring and an open slot, with a limiting groove on the protruding ring. The protective cover has a limiting protrusion and a locking post inside, with the limiting protrusion fitting into the limiting groove. The flywheel cover is locked onto the locking post through the open slot. The limiting groove and the limiting protrusion engage, and the open slot and the locking post engage, enabling quick positioning and stable connection between the flywheel cover and the protective cover. This also facilitates easy assembly and disassembly, improving assembly efficiency.

[0014] Furthermore, the flywheel housing is provided with an extension support section, which supports and limits the movement inside the protective housing. A reinforcing rib is provided between the extension support section and the flywheel housing. The extension support section is provided with a positioning protrusion, and the protective housing is provided with a positioning slot. The positioning protrusion and the positioning slot are inserted into each other in a one-to-one manner. The positioning protrusion and the positioning slot are engaged in a plug-in cooperation, which, combined with the plug-in cooperation between the limiting groove and the limiting protrusion, and the snap-fit ​​cooperation between the open slot and the snap-fit ​​post, achieves high-precision positioning between the flywheel housing and the protective housing. The extension support section also provides auxiliary support inside the protective housing, improving the overall structural stability after assembly. The design of the reinforcing rib improves the connection strength between the extension support section and the flywheel housing, making the structure more stable.

[0015] This utility model, by adopting the above-mentioned technical solution, has the following beneficial effects:

[0016] This utility model features a clever and reasonable structural design with strong practicality. The central shaft enables precise positioning and installation of the handle assembly and ratchet assembly. Furthermore, the protective cover is directly wrapped around the outside of the connecting end plate of the central shaft through injection molding, making the protective cover and the central shaft an integral structure, enhancing the connection stability, improving the overall reliability and durability of the starter assembly, facilitating user operation, and the design of the ratchet assembly enables unidirectional transmission during the starter process, preventing reverse rotation and ensuring the stability and reliability of the starter process. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings:

[0018] Figure 1 This is a schematic diagram of the structure of a starter assembly for a chainsaw according to the present invention;

[0019] Figure 2 for Figure 1 A structural diagram from another perspective;

[0020] Figure 3 This is a schematic diagram of the installation structure of the reset spring inside the protective cover in this utility model;

[0021] Figure 4 This is a schematic diagram of the structure of the rope pulley after installation in this utility model;

[0022] Figure 5 This is a schematic diagram of the ratchet seat after installation in this utility model;

[0023] Figure 6 This is a schematic diagram of the central shaft in this utility model;

[0024] Figure 7 This is a schematic diagram of the rope pulley structure in this utility model;

[0025] Figure 8This is a schematic diagram of the assembly structure between the pawl and the rope wheel in this utility model;

[0026] Figure 9 Exploded view of 8;

[0027] Figure 10 This is a schematic diagram of the positional state between the pawl and the ratchet seat in this utility model;

[0028] Figure 11 This is a schematic diagram of the ratchet seat in this utility model;

[0029] Figure 12 for Figure 11 A structural diagram from another perspective;

[0030] Figure 13 This is a schematic diagram of the installation structure of the drive spring in the ratchet seat in this utility model;

[0031] Figure 14 This is a schematic diagram of the ratchet structure in this utility model;

[0032] Figure 15 This is a schematic diagram showing the position of the abutment groove on the ratchet in this utility model;

[0033] Figure 16 This is a schematic diagram of the structure of the ratchet, pawl, and snap ring after installation in this utility model;

[0034] Figure 17 This is a schematic diagram of the installation structure between the snap ring and the central shaft in this utility model;

[0035] Figure 18 This is a schematic diagram of the flywheel housing in this utility model;

[0036] Figure 19 for Figure 18 A structural diagram from another perspective;

[0037] Figure 20 This is a schematic diagram of the structure of this utility model installed on a chainsaw;

[0038] Figure 21 This is a schematic diagram of the rotating tooth groove on the flywheel in this utility model.

[0039] In the diagram: 1-Starter assembly; 2-Chains saw; 3-Protective cover; 4-Connecting end plate; 5-Handle assembly; 6-Handle; 7-Rope pulley; 8-Ratchet assembly; 9-Hole; 10-Reset spring; 11-Ratchet seat; 12-Ratchet; 13-Drive spring; 14-Abutment groove; 15-Pawl; 16-Actuating slot; 17-Pawl; 18-Snap ring; 19-Limit ring groove; 20-Flying... 21-Rotating tooth groove; 22-Protruding post; 23-Adjusting clearance; 24-Limiting groove section; 25-Washer; 26-Flywheel cover; 27-Protruding ring; 28-Opening slot; 29-Limiting groove; 30-Limiting protrusion; 31-Snap-fit ​​post; 32-Extended support part; 33-Reinforcing rib; 34-Positioning protrusion; 35-Positioning slot; 36-Protrusion; 37-Central shaft; 38-Rope wheel groove. Detailed Implementation

[0040] like Figures 1 to 21 As shown, this utility model discloses a chainsaw starter assembly, including a protective cover 3, a central shaft 37, a handle assembly 5, and a ratchet assembly 8. One end of the central shaft 37 is provided with a connecting end plate 4. The protective cover 3 is injection molded and wrapped around the outside of the connecting end plate 4 to fix the central shaft 37 to the protective cover 3. The connecting end plate 4 and the central shaft 37 are integrally formed. The connecting end plate 4 is provided with holes 9. The integral forming facilitates actual processing and ensures structural strength and overall stability. The holes 9 and the injection molded material of the protective cover 3 form an interlocking structure, enhancing the connection strength between the protective cover 3 and the connecting end plate 4.

[0041] The handle assembly 5 includes a handle 6, a traction rope (not shown in the document), and a pulley 7. The traction rope is wound around the pulley groove 38 of the pulley 7. One end of the traction rope is connected to the handle 6, and the other end is connected to the pulley 7. The pulley 7 is fitted onto the central shaft 37 and rotates around the central shaft 37. The ratchet assembly 8 is fitted onto the central shaft 37 and rotates around the central shaft 37. The ratchet assembly 8 engages with the pulley 7 to achieve synchronous rotation between the ratchet assembly 8 and the pulley 7. The structure is ingeniously and reasonably designed, with strong practicality. The central shaft 37 enables precise positioning and installation of the handle assembly 5 and the ratchet assembly 8. Furthermore, the protective cover 3 is directly wrapped around the outside of the connecting end plate 4 of the central shaft 37 through injection molding, making the protective cover 3 and the central shaft 37 an integral structure, enhancing the connection stability, improving the overall reliability and durability of the starter assembly, and making the handle assembly 5 convenient for user operation. The design of the ratchet assembly 8 enables the starter to achieve unidirectional transmission during the starting process, preventing reverse rotation and ensuring the stability and reliability of the starting process.

[0042] A reset spring 10 is installed inside the protective cover 3. One end of the reset spring 10 is fixed inside the protective cover 3, and the other end of the reset spring 10 abuts against the rope wheel 7. The handle 6 drives the rope wheel 7 to rotate through the traction rope, and the rope wheel 7 drives the ratchet seat 11 to rotate. The ratchet seat 11 drives the ratchet 12 to rotate through the drive spring 13. The ratchet 12 starts the engine through the pawl 17 and the snap ring 18. At the same time, the rope wheel 7 also drives the abutting reset spring 10 to store power. After the start is completed, the rope wheel 7 resets and retracts the wound traction rope under the action of the reset spring 10.

[0043] The ratchet assembly 8 includes a ratchet seat 11 and a ratchet 12. The ratchet 12 is disposed within the cavity of the ratchet seat 11. A drive spring 13 is disposed within the cavity of the ratchet seat 11. One end of the drive spring 13 is fixedly positioned within the ratchet seat 11. An abutment groove 14 is provided on the outer side of the ratchet 12. The other end of the drive spring 13 abuts and is fixed within the abutment groove 14. The structure is cleverly and reasonably designed, with one end of the drive spring 13 fixedly positioned within the ratchet seat 11 and the other end abutting against the abutment groove 14 of the ratchet 12. 4. A stable transmission connection is formed. The drive spring 13 is used to store energy. When the drive spring 13 stores energy to a certain extent, the force at the end of the drive spring 13 that contacts the ratchet 12 is large enough. The ratchet 12 will then rotate the flywheel through the pawl 17 and the snap ring 18 to start the engine. A cover plate is provided on the ratchet seat 11. The cover plate is connected to the ratchet seat 11 by bolts. Assembly is convenient. Removing the cover plate can facilitate the installation and removal of the drive spring 13 in the cavity.

[0044] The pulley 7 is provided with a pawl 15, and the ratchet seat 11 is provided with a moving groove 16. The protrusion 36 on the pawl 15 is limited and engaged in the moving groove 16, realizing the engagement between the ratchet seat 11 and the pulley 7. When the pulley 7 rotates, the pawl 15 drives the ratchet seat 11 to rotate synchronously. The protrusion 36 is embedded in the moving groove 16, realizing the rigid connection between the pulley 7 and the ratchet seat 11. This ensures that the pawl 15 immediately drives the ratchet seat 11 to rotate synchronously through the moving groove 16 when the pulley 7 rotates, thus ensuring starting efficiency. The protrusion 36 is preferably designed to be at least two and evenly distributed on the outer side of the pawl 15, cooperating with the multiple moving grooves 16 of the ratchet seat 11.

[0045] Ratchet 12 is mounted on central shaft 37. Two pawls 17 are symmetrically arranged around the center of ratchet 12. One end of each pawl 17 is limited in rotation by the ratchet 12. Initially, one side of the pawl 17 is attached to the side corresponding to the central boss of the ratchet 12, allowing the pawl 17 to rotate only in one direction. Figure 14The middle arrow indicates the direction of unidirectional rotation of the pawl 17. Unidirectional rotation ensures the stability and reliability of the starting process. A retaining ring 18 is provided between the two pawls 17. The end of the ratchet 12 extending from the central shaft 37 is provided with a limiting ring groove 19. The retaining ring 18 is limited and engaged in the limiting ring groove 19. When the ratchet 12 rotates, the two pawls 17 are restricted by the retaining ring 18 and rotate intermittently on the ratchet 12. The flywheel 20 is provided with a rotating tooth groove 21. When the pawl 17 rotates intermittently, it engages in the rotating tooth groove 21 and drives the flywheel 20 to rotate. The structure is compact and reasonable. The limiting ring groove 19 is used for the engagement and installation of the retaining ring 18. The design is ingenious, easy to install and disassemble, and also convenient for subsequent maintenance and replacement.

[0046] The pawl 17 is provided with a protruding post 22, and the retaining spring 18 has adjustment gaps 23 on both sides. The protruding post 22 is located within the adjustment gap 23, and the adjustment gap 23 is provided with a limiting groove 24. When the ratchet 12 rotates, the protruding post 22 on the pawl 17 gradually moves into the limiting groove 24 and abuts against the end side wall of the limiting groove 24. When the ratchet 12 continues to rotate, the ratchet 17 rotates intermittently on the ratchet 12 due to the abutment and restriction of the protruding post 22 by the limiting groove 24. Shims 25 are provided between the ratchet seat 11 and the rope wheel 7, and between the retaining spring 18 and the ratchet 12. The shims 25 are sleeved on the central shaft 37. The design of the shims 25 can improve the structural stability and reliability of the assembled starter assembly.

[0047] The starter assembly also includes a flywheel cover 26, which is locked inside the protective cover 3. The flywheel cover 26 is provided with a protruding ring 27 and an open slot 28. The protruding ring 27 is provided with a limiting groove 29. The protective cover 3 is provided with a limiting protrusion 30 and a locking post 31. The limiting protrusion 30 is matched and inserted into the limiting groove 29. The flywheel cover 26 is locked onto the locking post 31 through the open slot 28. The limiting groove 29 and the limiting protrusion 30 are inserted and engaged, and the open slot 28 and the locking post 31 are locked and engaged, so as to realize the quick positioning and stable connection between the flywheel cover 26 and the protective cover 3, and the disassembly and assembly are convenient, improving the assembly efficiency. The flywheel cover 26 is provided with an extension support 32, which supports and limits the flywheel cover 3 inside. A reinforcing rib 33 is provided between the extension support 32 and the flywheel cover 26. A positioning protrusion 34 is provided on the extension support 32, and a positioning slot 35 is provided on the protective cover 3. The positioning protrusion 34 and the positioning slot 35 are inserted into each other in a one-to-one manner. The positioning protrusion 34 and the positioning slot 35 are engaged in a plug-in cooperation. Combined with the plug-in cooperation of the limiting groove 29 and the limiting protrusion 30, and the snap-fit ​​cooperation of the opening slot 28 and the snap-fit ​​post 31, high-precision positioning of the flywheel cover 26 and the protective cover 3 is achieved. The extension support 32 is also supported inside the protective cover 3, which improves the overall structural stability after assembly. The design of the reinforcing rib 33 improves the connection strength between the extension support 32 and the flywheel cover 26, making the structure more stable.

[0048] The above are merely specific embodiments of this utility model, but the technical features of this utility model are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on this utility model to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of this utility model.

Claims

1. A starter assembly for a chainsaw, characterized in that The utility model provides a kind of chain saw, including: Protective shell; Center shaft, one end of the center shaft is provided with connecting end plate, the protective shell injection wraps outside the connecting end plate, realize the fixation of the center shaft with the protective shell; Handle assembly, the handle assembly includes handle, traction rope and rope wheel, the traction rope is wound on the rope wheel, one end of the traction rope is connected with the handle, the other end of the traction rope is connected with the rope wheel, the rope wheel is sleeved on the center shaft, and the rope wheel rotates around the center shaft; Ratchet assembly, the ratchet assembly is sleeved on the center shaft, the ratchet assembly rotates around the center shaft, the ratchet assembly is clamped with the rope wheel, and the ratchet assembly and the rope wheel rotate synchronously.

2. A chain saw starter assembly according to claim 1, characterized in that The connecting end plate and the center shaft are integrally formed, and the connecting end plate is provided with a hole.

3. A chain saw starter assembly according to claim 1, characterized in that: The protective shell is provided with a reset coil spring, one end of the reset coil spring is limitedly fixed in the protective shell, and the other end of the reset coil spring abuts on the rope wheel.

4. A chain saw starter assembly according to claim 1, characterized in that: The ratchet assembly includes a ratchet seat and a ratchet, the ratchet is arranged in the cavity of the ratchet seat, a drive torsion spring is arranged in the cavity of the ratchet seat, one end of the drive torsion spring is limitedly fixed in the ratchet seat, the outer side of the ratchet is provided with an abutting groove, and the other end of the drive torsion spring is limitedly abutted in the abutting groove.

5. A chain saw starter assembly according to claim 4, characterized in that: The rope wheel is provided with a pawl, the ratchet seat is provided with a pushing clamping groove, the convex part on the pawl is limitedly clamped in the pushing clamping groove, the ratchet seat and the rope wheel are clamped, so that the rope wheel rotates, and the ratchet seat is driven by the pawl to rotate synchronously.

6. A chain saw starter assembly according to claim 4, characterized in that: The ratchet is symmetrically provided with two pawls, one end of the pawl is rotationally limited on the ratchet, a clamping spring is arranged between the two pawls, the center shaft is provided with a limiting ring groove at the end of the ratchet, the clamping spring is limitedly clamped in the limiting ring groove, and the two pawls are gap-rotated on the ratchet in the rotation of the ratchet, the flywheel of the chain saw is provided with a rotating tooth groove, and the pawl is clamped into the rotating tooth groove in the gap-rotation to drive the flywheel to rotate synchronously.

7. A chain saw starter assembly according to claim 6, characterized in that The pawl is provided with a protruding column, the clamping spring is provided with an adjusting gap on both sides, the protruding column is located in the adjusting gap, and a limiting groove section is arranged on the adjusting gap. When the ratchet rotates, the protruding column on the pawl gradually moves into the limiting groove section and abuts on the end side wall of the limiting groove section, and when the ratchet continues to rotate, the pawl is gap-rotated on the ratchet due to the abutting limitation of the limiting groove section on the protruding column.

8. A chain saw starter assembly according to claim 6, characterized in that: A gasket is arranged between the ratchet seat and the rope wheel and between the clamping spring and the ratchet, and the gasket is sleeved on the center shaft.

9. A chain saw starter assembly according to claim 1, characterized in that: The starter assembly further comprises a flywheel cover, which is clamped in the protective cover, and a convex ring and an open clamping groove are arranged on the flywheel cover, a limiting groove is arranged on the convex ring, a limiting convex column is arranged in the protective cover, and the limiting convex column is matched and inserted into the limiting groove, and the flywheel cover is clamped on the clamping column through the open clamping groove.

10. A chain saw starter assembly according to claim 9, characterized in that A supporting part is arranged on the flywheel cover, the supporting part is supported in the protective cover, a reinforcing rib is arranged between the supporting part and the flywheel cover, a positioning convex column is arranged on the supporting part, and a positioning insertion groove is arranged on the protective cover, and the positioning convex column and the positioning insertion groove are one-to-one matched and inserted.

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