Gear shift mechanism for an electric drill

Abstract

The utility model discloses a gear shifting mechanism for electric drill, including host computer casing, be equipped with with its rotatory connection output shaft in host computer casing, and the both ends of output shaft are equipped with first bearing and shift bearing respectively, and the end of output shaft near first bearing installs dynamic impact tooth, and the end of host computer casing near shift bearing is equipped with static impact tooth, be equipped with gear adjusting assembly on host computer casing, and gear adjusting assembly includes shift ring, fixed rotary head and limit pin, and limit pin is inserted and is arranged in host computer casing, still be equipped with the blocking sliding part of limit output shaft movement in host computer casing, and limit pin moves relative blocking sliding part when shift ring drives fixed rotary head to rotate, be equipped with first spring between the outer layer of blocking sliding part and host computer casing, and be equipped with second spring between limit pin and host computer casing, the utility model discloses through shift ring drive limit pin telescopic, thereby convenient switching dynamic impact tooth's stroke, and gear shifting is smooth and reliable, and user experience is better.

Description

Technical Field

[0001] This utility model belongs to the field of power tool technology, specifically relating to a gear shifting mechanism for an electric drill. Background Technology

[0002] An electric drill is a common power tool. Electric drills generally have impact gears and drill gears, which can be easily switched by rotating a shift ring. A patent with publication number CN206415664U discloses an impact shifting mechanism for an electric drill, comprising an upper bearing, a moving ratchet, a fixed ratchet, a shifting wheel, and a lower bearing, which are sequentially mounted outside the rotating shaft and installed in an inner housing. A fixed ratchet limiting block slides up and down and is engaged in a circumferential limiting groove. The upper and lower bearings are respectively housed in upper bearing housing cavities and lower bearing housing cavities. The rotating shaft can slide relative to the upper and lower bearings. A shifting protrusion abuts against the shifting inclined surface. A return spring is sleeved outside the rotating shaft, with its upper end elastically connected to the moving ratchet spring housing groove and its lower end elastically connected to the fixed ratchet spring housing groove. A shifting hole is provided on the lower part of the side wall of the inner housing, and a shifting rod extends from the shifting hole and is accommodated in a slot. Existing gear shifting mechanisms have many components, making the shifting process complex; they are prone to jamming during gear changes, resulting in uneven shifting and a poor user experience. Therefore, a gear shifting mechanism for electric drills needs to be designed to overcome these difficulties. Summary of the Invention

[0003] This invention addresses the problems existing in the prior art by designing a shifting mechanism for electric drills. This invention uses a shifting ring to drive the extension and retraction of a limiting pin, thereby facilitating the switching of the stroke of the moving impact teeth. The shifting is smooth and reliable, resulting in a better user experience.

[0004] The objective of this invention is achieved through the following technical solution: a shifting mechanism for an electric drill, comprising a main housing, an output shaft rotatably connected thereto within the main housing, a first bearing and a shift bearing respectively at both ends of the output shaft, a moving impact tooth mounted on the end of the output shaft near the first bearing, and a static impact tooth mounted on the end of the main housing near the shift bearing; a gear adjustment assembly is provided on the main housing, comprising a shift ring, a fixed shift head, and a limiting pin, the limiting pin being inserted into the main housing; a blocking sliding member is also provided within the main housing to restrict the movement of the output shaft, the limiting pin moving relative to the blocking sliding member when the shift ring drives the fixed shift head to rotate; a first spring is provided between the outer layer of the blocking sliding member and the main housing, and a second spring is provided between the limiting pin and the main housing.

[0005] Preferably, the outer wall of the main housing is provided with an adjustment ring rotatably connected thereto, and a rotating component is provided inside the adjustment ring and threadedly connected thereto. The rotating component is slidably connected to the main housing. The adjustment ring is fitted with a shift ring, and a cover plate is fixedly installed at the open end of the main housing. The cover plate is adjacent to the open end of the adjustment ring.

[0006] Preferably, the main housing is provided with an output shaft and an intermediate connector; the output shaft is rotatably connected to the main housing via a first bearing, and an intermediate connector is provided between the first bearing and the main housing; the intermediate connector and the first bearing are both fitted onto the end face of the cover plate.

[0007] By setting an adjustment ring, the shift ring can be easily limited. Here, both the adjustment ring and the rotating part are existing standard parts. The adjustment ring is limited by the cover plate, and the cover plate also limits the first bearing and the intermediate connecting part axially. The first bearing and the moving impact tooth are tightly connected to the output shaft, so that the output shaft can only move in the direction of the static impact tooth.

[0008] Preferably, the gear adjustment assembly further includes a shim, which is fitted onto the outer wall of the main housing; both the shim and the fixed conversion head are sleeved on the outer layer of the main housing, and the fixed conversion head can rotate relative to the main housing; the shift ring is sleeved on the outer layer of both the fixed conversion head and the shim, and the main housing is provided with an adjustment ring rotatably connected to it; one end of the shift ring abuts against the adjustment ring, and the other end of the shift ring abuts against the main housing; a limiting locking pin is provided between the shift ring and the main housing to limit the rotation of the shift ring, and a return spring is provided between the limiting locking pin and the main housing.

[0009] Preferably, the main housing has a guide hole for inserting a limiting pin, and the limiting pin is positioned between the guide hole and the fixed conversion head; a second spring is sleeved on the limiting pin, one end of the second spring abuts against the protrusion of the limiting pin, and the other end of the second spring abuts against the outer wall of the main housing; the fixed conversion head has a guide surface for moving the limiting pin; the guide surface is fitted to the protrusion of the limiting pin.

[0010] Preferably, the outer wall of the fixed conversion head is provided with a plurality of evenly distributed first protrusions, and the shift ring is provided with a plurality of evenly distributed first grooves, with the first protrusions disposed in the first grooves; the outer contour of the first protrusions and the outer contour of the first grooves are adapted to each other.

[0011] Preferably, the end of the fixed conversion head facing the gasket is provided with a plurality of second protrusions, each of the second protrusions having the same thickness, and the second protrusions abut against and fit against the end face of the gasket; the main housing is provided with a plurality of evenly distributed third protrusions, the third protrusions being fitted against the end face of the fixed conversion head facing away from the gasket.

[0012] Preferably, the main housing has several evenly distributed first steps, on which a displacement bearing is installed; the main housing also has a fixedly installed static impact tooth, which is fitted to the displacement bearing; the outer ring of the static impact tooth has several fourth protrusions that are staggered vertically, and the main housing has several second grooves that match the fourth protrusions; the outer contour of the fourth protrusions and the outer contour of the second grooves are adapted to each other.

[0013] Preferably, the blocking sliding member is disposed between the first bearing and the static impact tooth, with the first bearing and the dynamic impact tooth being disposed adjacent to each other; the blocking sliding member is slidably mounted on the outer layer of the dynamic impact tooth; a first spring is provided between the blocking sliding member and the inner wall of the main housing, and in the default state, the end face of the blocking sliding member is fitted with the end face of the first bearing; a limit pin is inserted inside the main housing, and the limit pin is perpendicular to the blocking sliding member.

[0014] Preferably, the blocking sliding member is provided with an annular protrusion, one end of the first spring abuts against the annular protrusion, and the other end of the first spring abuts against the inner wall of the main body housing; the blocking sliding member is provided with a plurality of evenly distributed clearance slots, the number of clearance slots being the same as the number of limiting pins; the outer contour of the clearance slots is adapted to the outer contour of the limiting pins.

[0015] When the shift ring rotates, it drives the fixed conversion head to rotate. As the fixed conversion head rotates, the limiting pin can move along the guide hole on the main housing. By setting a limiting locking pin and a return spring, and by providing a hole in the main housing to lock the shift ring with the limiting locking pin, the shift ring will not rotate arbitrarily when adjusted to the corresponding gear. The fixed conversion head is axially limited by a shim and a third protrusion on the main housing, preventing axial movement relative to the main housing during rotation. A first step facilitates the limiting of the shift bearing, and the fourth protrusion and second groove cooperate to ensure the static impact teeth are stably installed within the main housing. One end of the output shaft is mounted on the first bearing, and the other end is mounted on the shift bearing, allowing the output shaft to move relative to the static impact teeth. In the default state, both the first and second springs are compressed, and the protrusion of the limit pin abuts against the arc surface of the guide surface. At this time, the limit pin does not penetrate deeply into the main housing. Thus, the limit pin does not limit the blocking sliding part, and the blocking sliding part has a stroke to move towards the static impact teeth. The blocking sliding part is fitted with the first bearing, and the first bearing also has a stroke to move towards the static impact teeth. The first bearing and the moving impact teeth are tightly fitted on the output shaft, so the output shaft can slide axially within the main housing. The moving impact teeth on the output shaft and the static impact teeth in the main housing impact each other, thereby achieving the impact effect. The moving impact teeth and the static impact teeth are always in a disengaged and engaged state, causing the output shaft to move back and forth axially to impact the object. At this time, the electric drill is in the impact gear.

[0016] When switching from impact mode to single drill mode, the shift ring drives the fixed conversion head to rotate. This causes the fixed conversion head to push the limit pin, which moves along the arc surface of the guide surface towards the inclined surface, thus extending into the main housing. Because the main housing has a limit locking pin, the shift ring remains in the corresponding mode after shifting. At this time, the limit pin is adjacent to the clearance groove on the blocking sliding part, preventing the blocking sliding part from moving close to the static impact teeth. The first bearing and output shaft cannot move axially at this time, and the moving and static impact teeth cannot be in an opposing state. At this time, the electric drill is in single drill mode.

[0017] Compared with the prior art, this utility model has the following advantages: 1. The shift ring can drive the fixed conversion head to rotate, and when the fixed conversion head rotates, it can switch the extension and retraction position of the limit pin, thereby facilitating the control of the stroke of the blocking sliding part, and the gear switching is convenient and reliable; 2. The static impact teeth and dynamic impact teeth adjust the stroke through the blocking sliding part, so that the electric drill has multiple gears and good versatility; 3. The shift ring drives the fixed conversion head to rotate, and the fixed conversion head pushes the limit pin to move through the guide surface. The process of the limit pin moving along the guide surface is smooth and stable, the gear shifting process is smoother, and the gear shifting speed is fast. Attached Figure Description

[0018] Figure 1 This is a perspective view of the present utility model;

[0019] Figure 2 This is a diagram of the internal structure of the present invention;

[0020] Figure 3 This is an exploded view of the present invention;

[0021] Figure 4 A 3D view of the fixed-state converter head;

[0022] Figure 5 A 3D view of the blocking sliding component;

[0023] Figure 6 A three-dimensional view of a static impact gear;

[0024] Figure 7 This is a 3D view of the main unit casing;

[0025] The markings in the diagram are as follows: 1. Main housing; 2. Output shaft; 3. First bearing; 4. Shift bearing; 5. Dynamic impact gear; 6. Static impact gear; 7. Gear adjustment assembly; 71. Shift ring; 72. Fixed shift head; 73. Limit pin; 74. Blocking sliding component; 75. First spring; 76. Second spring; 77. Washer; 78. Guide surface; 79. First protrusion; 710. First groove; 711. Second protrusion; 8. Adjusting ring; 9. Rotating component; 10. Cover plate; 11. Intermediate connecting component; 12. Guide hole; 13. Third protrusion; 14. First step; 15. Fourth protrusion; 16. Second groove; 17. Annular protrusion; 18. Clearance slot; 19. Limit locking pin; 20. Return spring. Detailed Implementation

[0026] The present invention will be further described below with reference to the embodiments shown in the accompanying drawings:

[0027] like Figures 1 to 7As shown, this embodiment discloses a gear shifting mechanism for an electric drill, including a main housing 1. An output shaft 2, rotatably connected to the main housing 1, is provided inside the main housing 1. A first bearing 3 and a shift bearing 4 are respectively provided at both ends of the output shaft 2. A moving impact tooth 5 is installed on the end of the output shaft 2 near the first bearing 3, and a static impact tooth 6 is provided on the end of the main housing 1 near the shift bearing 4. A gear adjustment assembly 7 is provided on the main housing 1, including a shift ring 71, a fixed shift head 72, and a limiting pin 73. The limiting pin 73 is inserted into the main housing 1. A blocking sliding member 74 is also provided inside the main housing 1 to restrict the movement of the output shaft 2. When the shift ring 71 drives the fixed shift head 72 to rotate, the limiting pin 73 moves relative to the blocking sliding member 74. A first spring 75 is provided between the outer layer of the blocking sliding member 74 and the main housing 1, and a second spring 76 is provided between the limiting pin 73 and the main housing 1.

[0028] An adjusting ring 8 is rotatably connected to the outer wall of the main housing 1. A rotating component 9, threadedly connected to the adjusting ring 8, is slidably connected to the main housing 1. The adjusting ring 8 is fitted against a shift ring 71. A cover plate 10 is fixedly installed at the open end of the main housing 1, adjacent to the open end of the adjusting ring 8. An output shaft 2 is located inside the main housing 1, as is an intermediate connecting component 11. The output shaft 2 is rotatably connected to the main housing 1 via a first bearing 3, with the intermediate connecting component 11 positioned between the first bearing 3 and the main housing 1. Both the intermediate connecting component 11 and the first bearing 3 are fitted against the end face of the cover plate 10.

[0029] The gear adjustment assembly 7 also includes a shim 77, which is fitted onto the outer wall of the main housing 1. The shim 77 and the fixed conversion head 72 are both sleeved on the outer layer of the main housing 1, and the fixed conversion head 72 can rotate relative to the main housing 1. The shift ring 71 is sleeved on the outer layer of both the fixed conversion head 72 and the shim 77. The main housing 1 is provided with an adjustment ring 8 that is rotatably connected to it. One end of the shift ring 71 abuts against the adjustment ring 8, and the other end of the shift ring 71 abuts against the main housing 1. A limiting locking pin 19 for limiting the rotation of the shift ring is provided between the shift ring 71 and the main housing 1, and a return spring 20 is provided between the limiting locking pin 19 and the main housing 1. The main housing 1 has a guide hole 12 for inserting a limiting pin 73. The limiting pin 73 is located between the guide hole 12 and the fixed conversion head 72. A second spring 76 is sleeved on the limiting pin 73. One end of the second spring 76 abuts against the protrusion of the limiting pin 73, and the other end abuts against the outer wall of the main housing 1. The fixed conversion head 72 has a guide surface 78 for moving the limiting pin 73. The guide surface 78 is fitted to the protrusion of the limiting pin 73. The outer wall of the fixed conversion head 72 has a plurality of evenly distributed first protrusions 79. The shift ring 71 has a plurality of evenly distributed first grooves 710. The first protrusions 79 are located in the first grooves 710. The outer contour of the first protrusions 79 matches the outer contour of the first grooves 710. The fixed conversion head 72 has a plurality of second protrusions 711 on the end facing the gasket 77, each second protrusion 711 having the same thickness, and the second protrusions 711 abut against and fit against the end face of the gasket 77; the main housing 1 has a plurality of evenly distributed third protrusions 13, and the third protrusions 13 are fitted against the end face of the fixed conversion head 72 facing away from the gasket 77.

[0030] The main housing 1 has several evenly distributed first steps 14 inside, and a displacement bearing 4 is installed on the first step 14. A static impact tooth 6 is also fixedly installed inside the main housing 1, and the static impact tooth 6 is fitted to the displacement bearing 4. The outer ring of the static impact tooth 6 has several fourth protrusions 15 arranged at different heights. The main housing 1 has several second grooves 16 that match the fourth protrusions 15. The outer contour of the fourth protrusions 15 is adapted to the outer contour of the second grooves 16. A blocking sliding member 74 is disposed between the first bearing 3 and the static impact tooth 6, and the first bearing 3 and the moving impact tooth 5 are arranged adjacent to each other. The blocking sliding member 74 is slidably installed on the outer layer of the moving impact tooth 5. A first spring 75 is provided between the blocking sliding member 74 and the inner wall of the main housing 1. In the default state, the end face of the blocking sliding member 74 is fitted to the end face of the first bearing 3. A limiting pin 73 is inserted inside the main housing 1, and the limiting pin 73 is perpendicular to the blocking sliding member 74. The blocking sliding member 74 is provided with an annular protrusion 17, one end of the first spring 75 abuts against the annular protrusion 17, and the other end of the first spring 75 abuts against the inner wall of the main body housing 1; the blocking sliding member 74 is provided with a plurality of evenly distributed clearance slots 18, the number of clearance slots 18 being the same as the number of limiting pins 73; the outer contour of the clearance slots 18 is adapted to the outer contour of the limiting pins 73.

[0031] The specific operation process of this embodiment is as follows: When the shift ring 71 rotates, it drives the fixed conversion head 72 to rotate. When the fixed conversion head 72 rotates, the limiting pin 73 can move along the guide hole 12 on the main housing 1. By setting the limiting locking pin 19 and the return spring 20, the main housing 1 has a hole that cooperates with the limiting locking pin to lock the shift ring 71, so that the shift ring 71 will not rotate arbitrarily when adjusted to the corresponding gear. The fixed conversion head 72 is axially limited by the shim 77 and the third protrusion 13 on the main housing 1 to prevent the fixed conversion head 72 from moving axially relative to the main housing 1 when rotating. By setting the first step 14, it is convenient to limit the displacement bearing 4. The fourth protrusion 15 and the second groove 16 cooperate with each other, so that the static impact tooth 6 can be stably installed in the main housing 1. One end of the output shaft 2 is installed on the first bearing 3, and the other end of the output shaft 2 is installed on the displacement bearing 4, so that the output shaft 2 can move relative to the static impact tooth 6. In the default state, both the first spring 75 and the second spring 76 are in a compressed state. At this time, the protrusion of the limiting pin 73 abuts against the arc surface of the guide surface 78. At this time, the limiting pin 73 does not penetrate deeply into the main housing 1. Thus, the limiting pin 73 will not limit the blocking sliding member 74, and the blocking sliding member 74 has a stroke to move towards the static impact tooth 6. The blocking sliding member 74 is fitted with the first bearing 3, and at this time, the first bearing 3 also has a stroke to move towards the static impact tooth 6. The first bearing 3 and the moving impact tooth 5 are tightly fitted on the output shaft 2, so the output shaft 2 can slide axially in the main housing 1. The moving impact tooth 5 on the output shaft 2 and the static impact tooth 6 in the main housing 1 impact each other, thereby achieving the impact effect. The moving impact tooth 5 and the static impact tooth 6 are always in a disengaged and engaged state, so that the output shaft 2 moves back and forth axially to impact the object. At this time, the electric drill is in the impact gear.

[0032] When switching from impact mode to single drill mode, the shift ring 71 drives the fixed conversion head 72 to rotate. This causes the fixed conversion head 72 to push the limit pin 73 to move. The limit pin 73 then moves along the arc surface of the guide surface 78 towards the inclined surface of the guide surface 78, thus extending into the main housing 1. Since the main housing 1 is equipped with a limit locking pin 19, the shift ring 71 can maintain the corresponding mode after shifting. At this time, the limit pin 73 is adjacent to the clearance groove 18 on the blocking sliding member 74, so the blocking sliding member 74 cannot move close to the static impact tooth 6. The first bearing 3 and the output shaft 2 cannot move axially at this time, and the moving impact tooth 5 and the static impact tooth 6 cannot be in an opposing state. At this time, the electric drill is in single drill mode.

[0033] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.

Claims

1. A gear shifting mechanism for an electric drill, comprising a main housing (1), wherein an output shaft (2) is rotatably connected thereto within the main housing (1), characterized in that, The output shaft (2) is provided with a first bearing (3) and a shift bearing (4) at both ends respectively. A moving impact tooth (5) is installed on the end of the output shaft (2) near the first bearing (3). A static impact tooth (6) is provided on the end of the main housing (1) near the shift bearing (4). A gear adjustment assembly (7) is provided on the main housing (1). The gear adjustment assembly (7) includes a shift ring (71), a fixed conversion head (72) and a limit pin (73). The limit pin (73) is inserted into the main housing (1). A blocking sliding member (74) is also provided in the main housing (1) to restrict the movement of the output shaft (2). When the shift ring (71) drives the fixed conversion head (72) to rotate, the limit pin (73) moves relative to the blocking sliding member (74). A first spring (75) is provided between the outer layer of the blocking sliding member (74) and the main housing (1). A second spring (76) is provided between the limit pin (73) and the main housing (1).

2. The gear shifting mechanism for an electric drill according to claim 1, characterized in that, The outer wall of the main housing (1) is provided with an adjustment ring (8) rotatably connected thereto. The adjustment ring (8) is provided with a rotating part (9) threadedly connected thereto. The rotating part (9) is slidably connected to the main housing (1). The adjustment ring (8) is fitted with a shift ring (71). A cover plate (10) is fixedly installed at the open end of the main housing (1). The cover plate (10) is adjacent to the open end of the adjustment ring (8).

3. The gear shifting mechanism for an electric drill according to claim 2, characterized in that, The main housing (1) is provided with an output shaft (2) and an intermediate connector (11). The output shaft (2) is rotatably connected to the main housing (1) through a first bearing (3). An intermediate connector (11) is provided between the first bearing (3) and the main housing (1). The intermediate connector (11) and the first bearing (3) are both fitted onto the end face of the cover plate (10).

4. The gear shifting mechanism for an electric drill according to claim 1, characterized in that, The gear adjustment assembly (7) also includes a gasket (77), which is fitted onto the outer wall of the main housing (1); the gasket (77) and the fixed conversion head (72) are both fitted onto the outer layer of the main housing (1), and the fixed conversion head (72) can rotate relative to the main housing (1); the shift ring (71) is fitted onto the outer layer of both the fixed conversion head (72) and the gasket (77), and the main housing (1) is provided with an adjustment ring (8) that is rotatably connected to it; one end of the shift ring (71) abuts against the adjustment ring (8), and the other end of the shift ring (71) abuts against the main housing (1); a limiting locking pin (19) for limiting the rotation of the shift ring is provided between the shift ring (71) and the main housing (1), and a return spring (20) is provided between the limiting locking pin (19) and the main housing (1).

5. The gear shifting mechanism for an electric drill according to claim 4, characterized in that, The main housing (1) is provided with a guide hole (12) for inserting a limiting pin (73). The limiting pin (73) is located between the guide hole (12) and the fixed conversion head (72). A second spring (76) is sleeved on the limiting pin (73). One end of the second spring (76) abuts against the protrusion of the limiting pin (73), and the other end of the second spring (76) abuts against the outer wall of the main housing (1). The fixed conversion head (72) is provided with a guide surface (78) for moving the limiting pin (73). The guide surface (78) is fitted to the protrusion of the limiting pin (73).

6. The gear shifting mechanism for an electric drill according to claim 4, characterized in that, The outer wall of the fixed conversion head (72) is provided with a plurality of evenly distributed first protrusions (79), and the shift ring (71) is provided with a plurality of evenly distributed first grooves (710). The first protrusions (79) are disposed in the first grooves (710); the outer contour of the first protrusions (79) and the outer contour of the first grooves (710) are adapted to each other.

7. The gear shifting mechanism for an electric drill according to claim 4, characterized in that, The fixed conversion head (72) has several second protrusions (711) at the end facing the gasket (77), each second protrusion (711) having the same thickness, and the second protrusions (711) abut against and fit against the end face of the gasket (77); the main housing (1) has several evenly distributed third protrusions (13), and the third protrusions (13) fit against the end face of the fixed conversion head (72) facing away from the gasket (77).

8. The gear shifting mechanism for an electric drill according to claim 1, characterized in that, The main housing (1) is provided with several evenly distributed first steps (14), and a displacement bearing (4) is installed on the first step (14); a static impact tooth (6) is also fixedly installed in the main housing (1), and the static impact tooth (6) is fitted with the displacement bearing (4); the outer ring of the static impact tooth (6) is provided with several fourth protrusions (15) that are staggered in height, and the main housing (1) is provided with several second grooves (16) that match the fourth protrusions (15); the outer contour of the fourth protrusion (15) and the outer contour of the second groove (16) are adapted to each other.

9. The gear shifting mechanism for an electric drill according to claim 1, characterized in that, The blocking sliding member (74) is disposed between the first bearing (3) and the static impact tooth (6), and the first bearing (3) and the dynamic impact tooth (5) are disposed adjacent to each other; the blocking sliding member (74) is slidably mounted on the outer layer of the dynamic impact tooth (5); a first spring (75) is provided between the blocking sliding member (74) and the inner wall of the main housing (1), and in the default state, the end face of the blocking sliding member (74) is fitted with the end face of the first bearing (3); a limit pin (73) is inserted inside the main housing (1), and the limit pin (73) is perpendicular to the blocking sliding member (74).

10. The gear shifting mechanism for an electric drill according to claim 9, characterized in that, The blocking slider (74) is provided with an annular protrusion (17), one end of the first spring (75) abuts against the annular protrusion (17), and the other end of the first spring (75) abuts against the inner wall of the main housing (1); the blocking slider (74) is provided with a plurality of evenly distributed clearance slots (18), the number of clearance slots (18) is the same as the number of limit pins (73); the outer contour of the clearance slots (18) is adapted to the outer contour of the limit pins (73).

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