Electric vehicle front fork with shock absorbing function

Abstract

This invention relates to the field of electric vehicle accessories, specifically to an electric vehicle front fork with shock absorption function. It includes a crossbeam, with inner sliding sleeves fixedly installed at both ends of the crossbeam. An outer sliding sleeve is slidably installed on the lower part of the outer surface of the inner sliding sleeve. An upper plate is fitted inside the inner sliding sleeve, and a guide shell is slidably installed at the lower end of the upper plate. A lower plate is screwed onto the lower edge of the outer surface of the guide shell, and the lower plate is fitted against the inner bottom surface of the outer sliding sleeve. The diameter of the lower plate is the same as that of the upper plate. A shock-absorbing spring is disposed between the opposing surfaces of the lower and upper plates. A threaded rod is rotatably installed at the upper center of the upper plate, and a threaded ring is screwed onto the lower part of the outer surface of the threaded rod. Multiple connecting blocks are slidably installed in a circular array at the upper end of the upper plate. This invention effectively facilitates maintenance and makes it easy to reinstall the shock-absorbing spring.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle accessories, specifically to an electric vehicle front fork with shock absorption function. Background Technology

[0002] Electric vehicles rely on onboard batteries to store electrical energy, which is then powered by an electric motor to drive the vehicle. They offer advantages such as energy efficiency, environmental friendliness, low operating noise, low operating costs, and ease of operation, making them a suitable green mode of transportation for daily commutes and short trips. The front fork, a key component of an electric vehicle, features internal shock-absorbing springs that effectively cushion road bumps and impacts, significantly improving riding comfort.

[0003] However, in actual use, the shock-absorbing springs inside existing electric vehicle front forks need to be replaced after their shock absorption performance deteriorates. Replacement requires first removing the entire front fork from the electric vehicle, then disassembling the fork to replace the springs. This cumbersome and complex process makes maintenance inconvenient. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the prior art by proposing a shock-absorbing electric vehicle front fork.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an electric vehicle front fork with shock absorption function, comprising a crossbeam, both ends of which are fixedly mounted with inner sliding sleeves, an outer sliding sleeve slidably mounted on the lower part of the outer surface of the inner sliding sleeve, an upper plate fitted inside the inner sliding sleeve, a guide shell slidably mounted on the lower end of the upper plate, a lower plate screwed onto the lower edge of the outer surface of the guide shell, the lower plate fitting against the inner bottom surface of the outer sliding sleeve, the diameter of the lower plate being the same as the diameter of the upper plate, a shock-absorbing spring being provided between the opposing surfaces of the lower plate and the upper plate, a threaded rod rotatably mounted on the upper middle part of the upper plate, a threaded ring screwed onto the lower part of the outer surface of the threaded rod, a plurality of connecting blocks slidably mounted in a ring array on the upper end of the upper plate, a retractable bracket rotatably mounted between the connecting blocks and the threaded ring, a plurality of connecting holes being opened in a ring array through the lower part of the inner wall of the inner sliding sleeve, the connecting blocks being inserted into the interior of the connecting holes, and a positioning element being provided on the inner sliding sleeve.

[0006] Preferably, an upper connecting column is fixedly installed through the middle of the crossbeam, a lower connecting lug extends from the lower part of the outer surface of the outer sliding sleeve, and a dust cover is inserted into the upper end of the inner sliding sleeve.

[0007] Preferably, the upper end of the upper plate has a ring array of multiple receiving slots, the connecting block fits into the inside of the receiving slots, the inner wall of the receiving slot has two symmetrically extending limiting strips, the front and rear end faces of the connecting block are provided with limiting slots, and the limiting strips are inserted into the inside of the limiting slots.

[0008] Preferably, a column cap is slidably installed inside the guide shell, and a guide post extends from the middle of the upper end of the column cap. The guide post passes through the upper end of the guide shell and slides with the guide shell. The upper end of the guide post is fixed to the upper plate. Two guide ridges extend symmetrically from the inner wall of the guide shell. Two sliding grooves are symmetrically opened on the outer surface of the column cap. The guide ridges are inserted into the sliding grooves. A slot is opened at the lower end of the lower plate. A locking block extends from the inner bottom surface of the outer sliding sleeve and is inserted into the slot.

[0009] Preferably, a limiting ring extends from the lower part of the outer surface of the inner sliding sleeve, and a limiting groove is formed on the upper part of the inner wall of the outer sliding sleeve, with the limiting ring slidably installed inside the limiting groove.

[0010] Preferably, a positioning groove is provided at the upper edge of the inner wall of the inner sleeve, and a positioning ring is coaxially rotatably installed on the upper part of the outer surface of the threaded rod, the positioning ring being inserted into the inside of the positioning groove.

[0011] Preferably, the positioning element includes a positioning ring fitted on the upper part of the outer surface of the inner sliding sleeve. The positioning ring has two symmetrically opened holes inside, and a strip is inserted into each of the two holes. The outer surface of the inner sliding sleeve has two sets of positioning notches, with two notches in each set. The two positioning notches are symmetrically arranged, and the strip is inserted into the upper positioning notch.

[0012] Preferably, an arc-shaped seat is fixedly installed between the rear ends of the two inserts, the arc-shaped seat is integrally formed with the inserts, the rear end of the positioning ring has a receiving cavity, the receiving cavity is connected to the insertion hole, the arc-shaped seat is inserted into the inside of the receiving cavity, and a magnet is fixedly installed at the front end of the insert.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. By rotating the threaded rod, the threaded ring can be moved upward, thereby driving the retractor frame to move and pull the connecting block out of the connecting hole on the inner sleeve. Then, by pulling the threaded rod upward, the upper plate, shock absorber spring, and lower plate between the inner and outer sleeves can be pulled out from the top of the inner sleeve. Then, by unscrewing the lower plate off the guide shell, the shock absorber spring sleeved on the outside of the guide shell can be removed and replaced. This process can be carried out while the front fork is on the electric vehicle, without having to remove the front fork, thus effectively facilitating maintenance.

[0015] 2. Before replacement, grasp the arc-shaped seat and pull the insert out of the positioning ring, allowing the insert to disengage from the upper positioning notch. Then push the positioning ring downwards until it slides on the inner sleeve to the lower positioning notch. Reinsert the insert into the positioning ring and into the lower positioning notch to restrain the positioning ring, ensuring it adheres to the upper end of the outer sleeve. When the subsequent shock absorber spring is removed from the top of the inner sleeve, the positioning ring will prevent the inner sleeve from sliding down. This avoids the inner sleeve from slipping to the bottom of the outer sleeve due to the weight of the electric vehicle without the support of the shock absorber spring, which would significantly reduce the space between the bottom of the inner and outer sleeves, making it difficult to install the subsequent shock absorber spring. This facilitates the smooth reinstallation of the shock absorber spring. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0017] Figure 2 This is an internal view of the outer sliding sleeve of the present invention;

[0018] Figure 3 This is an internal view of the inner sleeve of the present invention;

[0019] Figure 4 This is an exploded view of the lower plate and outer sliding sleeve of the present invention;

[0020] Figure 5 This is an internal view of the guide shell of the present invention;

[0021] Figure 6 For the present invention Figure 3 Enlarged view of A in the middle;

[0022] Figure 7 For the present invention Figure 3 Enlarged view of B in the middle;

[0023] Figure 8 This is an internal view of the positioning ring of the present invention;

[0024] Figure 9 This is an exploded view of the positioning ring and insert strip of the present invention.

[0025] The components represented by each number in the attached diagram are listed below: 1. Crossbeam; 2. Upper connecting column; 3. Dust cover; 4. Inner sliding sleeve; 5. Outer sliding sleeve; 6. Lower connecting ear; 7. Positioning ring; 8. Positioning notch; 9. Magnet; 10. Insert strip; 11. Arc-shaped seat; 12. Upper plate; 13. Guide post; 14. Guide shell; 15. Shock-absorbing spring; 16. Column cap; 17. Guide ridge; 18. Lower plate; 19. Threaded ring; 20. Threaded rod; 21. Retracting frame; 22. Receiving groove; 23. Limiting strip; 24. Limiting groove; 25. Connecting hole; 26. Connecting block; 27. Positioning ring; 28. Positioning groove; 29. ​​Locking block; 30. Slot; 31. Limiting ring; 32. Limiting groove; 33. Slide groove; 34. Insertion hole; 35. Receiving cavity. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] This invention provides a technical solution: such as Figures 1-9The electric vehicle front fork with shock absorption function shown includes a crossbeam 1. Inner sliding sleeves 4 are fixedly installed through both ends of the crossbeam 1. Outer sliding sleeves 5 are slidably installed on the lower part of the outer surface of the inner sliding sleeves 4. The inner and outer sliding sleeves 4 and 5 serve as guides. An upper plate 12 is fitted inside the inner sliding sleeve 4. A guide shell 14 is slidably installed at the lower end of the upper plate 12, serving as a guide. A lower plate 18 is screwed tightly onto the lower edge of the outer surface of the guide shell 14. The upper plate 12 and lower plate 18 support the shock-absorbing spring 15. The lower plate 18 is fitted to the outer sliding sleeve 5. The inner bottom surface has the same diameter as the upper plate 12, ensuring that the lower plate 18 smoothly enters the inner sliding sleeve 4 and is pulled out from the upper end of the inner sliding sleeve 4. A shock-absorbing spring 15 is provided between the opposing surfaces of the lower plate 18 and the upper plate 12 to absorb shock. A threaded rod 20 is rotatably installed at the upper middle part of the upper plate 12. A threaded ring 19 is screwed onto the lower part of the outer surface of the threaded rod 20. The threaded rod 20 controls the movement of the threaded ring 19. Rotating the threaded rod 20 can drive the threaded ring 19 to move upward, thereby driving the take-up and release frame 21. The movement allows the connecting block 26 to be pulled out from the connecting hole 25 on the inner sliding sleeve 4. Multiple connecting blocks 26 are slidably mounted in a ring array on the upper end of the upper plate 12. A take-up and release frame 21 is rotatably mounted between the connecting block 26 and the threaded ring 19. Multiple connecting holes 25 are perforated in a ring array on the lower part of the inner wall of the inner sliding sleeve 4. The cooperation between the connecting block 26 and the connecting hole 25 serves to connect the upper plate 12 and the inner sliding sleeve 4 together. The connecting block 26 is inserted into the inside of the connecting hole 25. A positioning element is provided on the inner sliding sleeve 4. By rotating the threaded rod 20, the threaded ring 19 can be driven. 9 moves upward, thereby driving the retraction frame 21 to move, so as to pull the connecting block 26 out of the connecting hole 25 on the inner sliding sleeve 4. Then, pull the threaded rod 20 upward to pull out the upper plate 12, shock absorber spring 15 and lower plate 18 between the inner sliding sleeve 4 and the outer sliding sleeve 5 from the top of the inner sliding sleeve 4. Then, unscrew the lower plate 18 from the guide shell 14 to remove the shock absorber spring 15 sleeved on the guide shell 14 for replacement. The process can be carried out directly with the front fork on the electric vehicle to replace the internal shock absorber spring 15 without removing the front fork, thus effectively facilitating maintenance.

[0028] The upper connecting column 2 is fixedly installed through the middle of the crossbeam 1. The lower connecting lug 6 extends from the lower part of the outer surface of the outer sliding sleeve 5. The upper connecting column 2 and the lower connecting lug 6 serve to assemble the front fork and the electric vehicle body. The upper end of the inner sliding sleeve 4 is fitted with a dust cover 3, which serves to block dust.

[0029] The upper end of the upper plate 12 has multiple receiving slots 22 arranged in a ring array. The connecting block 26 fits into the inside of the receiving slot 22. The receiving slot 22 serves to accommodate the connecting block 26. Two limiting strips 23 extend symmetrically from the inner wall of the receiving slot 22. The front and rear ends of the connecting block 26 are provided with limiting slots 24. The cooperation between the limiting strips 23 and the limiting slots 24 serves to guide the connecting block 26 horizontally. The limiting strips 23 are inserted into the inside of the limiting slots 24.

[0030] A column cap 16 is slidably mounted inside the guide housing 14. A guide post 13 extends from the middle of the upper end of the column cap 16. The column cap 16 prevents the guide housing 14 and the guide post 13 from separating. The guide post 13 extends through the upper end of the guide housing 14 and slides with the guide housing 14 to guide the upper plate 12 and the lower plate 18. The upper end of the guide post 13 is fixed to the upper plate 12. Two guide ribs 17 extend symmetrically from the inner wall of the guide housing 14. Two sliding grooves 33 are symmetrically formed on the outer surface of the column cap 16. The fit between the guide ribs 17 and the sliding grooves 33 ensures that the guide post 13 will not rotate, thereby ensuring that the upper plate 12 will not rotate. This prevents the threaded ring from rotating when the threaded rod 20 is rotated. 19 can move normally, thereby driving the take-up and take-down rack 21 to move normally, so as to control the movement of the connecting block 26. The guide rib 17 is inserted into the interior of the slide groove 33. The lower end of the lower plate 18 is provided with a slot 30. The inner bottom surface of the outer slide sleeve 5 extends with a locking block 29. The locking block 29 is inserted into the interior of the slot 30. The cooperation between the locking block 29 and the slot 30 can, on the one hand, ensure that the lower plate 18 will not rotate, thereby ensuring that the guide shell 14 will not rotate. On the other hand, it can position the angle of the lower plate 18, thereby positioning the orientation of the connecting block 26 on the upper plate 12, so that the connecting block 26 can be kept aligned with the connecting hole 25 on the inner slide sleeve 4, ready for insertion.

[0031] A limiting ring 31 extends from the lower part of the outer surface of the inner sliding sleeve 4, and a limiting groove 32 is formed on the upper part of the inner wall of the outer sliding sleeve 5. The fit between the limiting ring 31 and the limiting groove 32 can prevent the inner sliding sleeve 4 and the outer sliding sleeve 5 from separating. The limiting ring 31 is slidably installed inside the limiting groove 32.

[0032] A positioning groove 28 is provided at the upper edge of the inner wall of the inner sliding sleeve 4. A positioning ring 27 is coaxially rotatably installed on the upper part of the outer surface of the threaded rod 20. The positioning ring 27 is inserted into the inside of the positioning groove 28. When the shock-absorbing spring 15 is reinstalled, the positioning ring 27 on the threaded rod 20 will enter the positioning groove 28. At this time, the positioning groove 28 will obstruct the positioning of the height of the positioning ring 27, thereby positioning the height of the connecting block 26 on the upper plate 12, so that the connecting block 26 can be at the same height as the connecting hole 25 on the inner sliding sleeve 4, so as to facilitate subsequent connection.

[0033] The positioning component includes a positioning ring 7 fitted onto the upper part of the outer surface of the inner sliding sleeve 4. The positioning ring 7 prevents the inner sliding sleeve 4 from sliding down. Two symmetrical insertion holes 34 are formed inside the positioning ring 7, and insertion strips 10 are inserted into each of the two insertion holes 34. The insertion holes 34 accommodate the insertion strips 10. Two sets of positioning notches 8 are respectively formed on the upper part of the outer surface of the inner sliding sleeve 4. The cooperation between the insertion strips 10 and the positioning notches 8 can fix the positioning ring 7. Each set of positioning notches 8 consists of two notches, and the two positioning notches 8 are symmetrically arranged. The insertion strip 10 is inserted into the upper positioning notch 8. Before replacement, the insertion strip 10 can be pulled out of the positioning ring 7 by grasping the arc-shaped seat 11, allowing the insertion strip 10 to disengage from the upper positioning notch 8. Next, push the positioning ring 7 downwards. When the positioning ring 7 slides on the inner sliding sleeve 4 to the lower positioning notch 8, insert the insert 10 back into the positioning ring 7 and into the lower positioning notch 8 to restrict the positioning ring 7, so that the positioning ring 7 can be attached to the upper end of the outer sliding sleeve 5. When the shock absorber spring 15 is taken out from the top of the inner sliding sleeve 4, the positioning ring 7 can ensure that the inner sliding sleeve 4 will not slide down, so as to avoid the inner sliding sleeve 4 sliding down to the bottom of the outer sliding sleeve 5 due to the weight of the electric vehicle because it loses the support of the shock absorber spring 15. This would greatly reduce the space between the bottom of the inner sliding sleeve 4 and the bottom of the outer sliding sleeve 5, making it difficult to install the shock absorber spring 15. This facilitates the smooth reinstallation of the shock absorber spring 15.

[0034] An arc-shaped seat 11 is fixedly installed between the rear ends of the two inserts 10. The arc-shaped seat 11 is integrally formed with the insert 10. The arc-shaped seat 11 facilitates the extraction of the insert 10. The rear end of the positioning ring 7 has a receiving cavity 35, which is connected to the insertion hole 34. The receiving cavity 35 serves to accommodate the arc-shaped seat 11. The arc-shaped seat 11 is inserted into the inside of the receiving cavity 35. A magnet 9 is fixedly installed at the front end of the insert 10. The magnet 9 can fix the insert 10 in the inner sliding sleeve 4 by magnetic force.

[0035] In use, the front fork can be assembled onto the electric vehicle via the upper connecting post 2 and the lower connecting lug 6. If the shock absorption performance of the shock-absorbing spring 15 decreases during use, first grasp the arc-shaped seat 11 to pull the insert 10 out of the positioning ring 7, allowing the insert 10 to disengage from the upper positioning notch 8. Then push the positioning ring 7 downwards until it slides on the inner sleeve 4 to the lower positioning notch 8. Then reinsert the insert 10 into the positioning ring 7 and into the lower positioning notch 8 to restrict the positioning ring 7, allowing it to adhere to the upper end of the outer sleeve 5. When the shock-absorbing spring 15 is subsequently removed from the top of the inner sleeve 4, the positioning ring 7 will prevent the inner sleeve 4 from sliding down. Next, rotate the threaded rod 20 to move the threaded ring 19 upwards, thereby driving the retractor 21 to move and pull the connecting block 26 out of the connecting hole 25 on the inner sleeve 4. Then pull the threaded rod 20 upwards to retract the inner sleeve 4 and the outer sleeve 5. The upper plate 12, shock-absorbing spring 15, and lower plate 18 are pulled out from the top of the inner sliding sleeve 4. Then, the lower plate 18 is unscrewed from the guide shell 14, allowing the shock-absorbing spring 15, which is sleeved on the outside of the guide shell 14, to be removed and replaced. After replacement, the upper plate 12, shock-absorbing spring 15, and lower plate 18 are reinserted from the top of the inner sliding sleeve 4. Once the slot 30 at the lower end of the lower plate 18 and the locking block 29 on the inner bottom surface of the outer sliding sleeve 5 are engaged, the positioning ring 27 on the threaded rod 20 is fully inserted into the inner sliding sleeve 4. When the connecting block 26 on the upper plate 12 is aligned with the connecting hole 25 on the inner sliding sleeve 4, the threaded rod 20 is then rotated in the opposite direction to drive the threaded ring 19 to move down, thereby driving the take-up and release frame 21 to move and push the connecting block 26 back into the connecting hole 25 on the inner sliding sleeve 4, so that the replaced shock-absorbing spring 15 is assembled between the inner sliding sleeve 4 and the outer sliding sleeve 5. Then the insert 10 is pulled out and the positioning ring 7 is pushed back to its original position, and then it can be used again.

[0036] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A shock-absorbing electric vehicle front fork, comprising a crossbeam (1), characterized in that: Both ends of the crossbeam (1) are fixedly fitted with inner sliding sleeves (4). An outer sliding sleeve (5) is slidably installed on the lower part of the outer surface of the inner sliding sleeve (4). An upper plate (12) is fitted inside the inner sliding sleeve (4). A guide shell (14) is slidably installed at the lower end of the upper plate (12). A lower plate (18) is screwed onto the lower edge of the outer surface of the guide shell (14). The lower plate (18) fits against the inner bottom surface of the outer sliding sleeve (5). The diameter of the lower plate (18) is the same as the diameter of the upper plate (12). A gap is provided between the opposite surfaces of the lower plate (18) and the upper plate (12). The shock-absorbing spring (15) has a threaded rod (20) rotatably mounted on the upper middle part of the upper plate (12). A threaded ring (19) is screwed onto the lower part of the outer surface of the threaded rod (20). Multiple connecting blocks (26) are slidably mounted in an annular array on the upper end of the upper plate (12). A take-up and release frame (21) is rotatably mounted between the connecting block (26) and the threaded ring (19). Multiple connecting holes (25) are opened through the lower part of the inner wall of the inner sleeve (4) in an annular array. The connecting block (26) is inserted into the inside of the connecting hole (25). A positioning element is provided on the inner sleeve (4).

2. The electric vehicle front fork with shock absorption function according to claim 1, characterized in that: The upper connecting column (2) is fixedly installed through the middle of the crossbeam (1), the lower part of the outer surface of the outer sliding sleeve (5) has a lower connecting lug (6), and the upper end of the inner sliding sleeve (4) is fitted with a dust cover (3).

3. The electric vehicle front fork with shock absorption function according to claim 1, characterized in that: The upper end of the upper plate (12) has a ring array of multiple receiving slots (22). The connecting block (26) fits into the inside of the receiving slot (22). The inner wall of the receiving slot (22) has two symmetrically extending limiting strips (23). The front and rear end faces of the connecting block (26) are provided with limiting slots (24). The limiting strips (23) are inserted into the inside of the limiting slots (24).

4. The electric vehicle front fork with shock absorption function according to claim 1, characterized in that: A column cap (16) is slidably installed inside the guide shell (14). A guide post (13) extends from the middle of the upper end of the column cap (16). The guide post (13) passes through the upper end of the guide shell (14). The guide post (13) is slidably engaged with the guide shell (14). The upper end of the guide post (13) is fixed to the upper plate (12). Two guide ribs (17) extend symmetrically from the inner wall of the guide shell (14). Two sliding grooves (33) are symmetrically opened on the outer surface of the column cap (16). The guide ribs (17) are inserted into the sliding grooves (33). A slot (30) is opened at the lower end of the lower plate (18). A locking block (29) extends from the inner bottom surface of the outer sliding sleeve (5). The locking block (29) is inserted into the slot (30).

5. The electric vehicle front fork with shock absorption function according to claim 1, characterized in that: The lower part of the outer surface of the inner sliding sleeve (4) extends a limiting ring (31), and the upper part of the inner wall of the outer sliding sleeve (5) is provided with a limiting groove (32). The limiting ring (31) is slidably installed inside the limiting groove (32).

6. The electric vehicle front fork with shock absorption function according to claim 1, characterized in that: A positioning groove (28) is provided at the upper edge of the inner wall of the inner sleeve (4), and a positioning ring (27) is coaxially rotatably installed on the upper part of the outer surface of the threaded rod (20), and the positioning ring (27) is inserted into the inside of the positioning groove (28).

7. The electric vehicle front fork with shock absorption function according to claim 1, characterized in that: The positioning component includes a positioning ring (7) fitted on the upper part of the outer surface of the inner sliding sleeve (4). The positioning ring (7) has two symmetrically opened holes (34). Inserts (10) are inserted into the two holes (34). The outer surface of the inner sliding sleeve (4) has two sets of positioning notches (8). Each set of positioning notches (8) has two notches. The two positioning notches (8) are symmetrically arranged. The inserts (10) are inserted into the upper positioning notch (8).

8. The electric vehicle front fork with shock absorption function according to claim 7, characterized in that: An arc-shaped seat (11) is fixedly installed between the rear ends of the two inserts (10). The arc-shaped seat (11) is integrally formed with the insert (10). The rear end of the positioning ring (7) is provided with a receiving cavity (35). The receiving cavity (35) is connected to the insertion hole (34). The arc-shaped seat (11) is inserted into the inside of the receiving cavity (35). A magnet (9) is fixedly installed at the front end of the insert (10).

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