CN111645803A - Internal differential speed variator for bicycle - Google Patents

Abstract

The invention provides an internal differential transmission for a bicycle, comprising a driving body for transmitting human driving force, a fixing member for fixing a shifting unit, a shifting unit and a control part, wherein the shifting unit shifts the motion input by the driving body After the output is output by the second rotating body or the fourth rotating body, the control part can move along the axial direction of the first fixed axis, and can control the connection and separation of the first rotating body and the second rotating body and the fixed part during the moving process , and the connection and separation of the first rotating body and the fourth rotating body and the driving body; the present invention takes the differential gear train composed of the first rotating body, the second rotating body, the third rotating body and the fourth rotating body as the main body The gear module can be increased while meeting the external dimensions, so that the bending strength is greatly enhanced and the service life of the transmission is increased.

Description

An internal differential transmission for bicycles

technical field

The invention belongs to the technical field of bicycle shifting equipment, and in particular relates to an internal differential transmission for bicycles.

Background technique

The appearance of bicycles has greatly facilitated people's travel. With the improvement of production technology, the development of science and technology and the development of humanistic spirit, human beings have higher requirements for bicycles. The design and manufacture of bicycles are constantly improving, their structure and craftsmanship are becoming more and more reasonable, and their performance is constantly improving. With the advent of bicycles, variable speed bicycles also began to develop. At present, the transmissions of bicycles are roughly divided into two categories: tower wheel outer transmissions and closed inner transmissions. The external derailleur is to install sprockets with different numbers of teeth on the rear wheel of the bicycle, and rely on the chain to cooperate with different sprockets to realize the change of the transmission ratio. However, the external derailleur is exposed to the outside of the bicycle and is easily corroded by rain, dust and grease, which makes maintenance more complicated, has a short service life and is not very beautiful in appearance. The speed change device of the inner transmission is hidden inside the shaft casing, and is protected by multiple layers of special sealing materials to avoid being exposed to the outside world, so rainwater, dust, grease, etc. cannot enter, and it also avoids sun exposure and wind and rain erosion, so regular maintenance is not required. It realizes the advantages of maintenance-free, precise, durable and lightweight.

The existing three-speed transmission in a bicycle is mainly based on a planetary gear train. Due to its structural design, the theoretical growth rate must be less than 2, and the reduction ratio must be greater than 0.5. In actual production, the cost and use are guaranteed. Under the premise of performance, the transmission ratio will be limited. The transmission ratio of the acceleration gear can only be 1.4, and the transmission ratio of the deceleration gear can only be 0.7. The consequence is that the sense of acceleration is not strong when accelerating, and it is difficult to climb at low speed. , the sense of acceleration and deceleration is not obvious when riding. Because the axis around the gears is parallel to the hub axle of the bicycle, the internal derailleur with the planetary gear train as the main body will be limited by the size of the design. Generally, the modulus of the gear is 0.8-1, so the bending strength is not high.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a bicycle inner differential transmission with a larger gear ratio and stronger bending strength.

In order to achieve the above-mentioned purpose, the technical solution adopted in the present invention is: an internal differential transmission for bicycles, comprising:

A driving body, which is connected with the bicycle frame and is used to transmit human driving force;

The speed change unit includes a first rotating body and a second rotating body rotating around a first fixed axis, a third rotating body rotating around the second fixed axis, and a fourth rotating body fixedly connected with the second fixed axis, the fourth rotating body The rotating body rotates around the first fixed axis, and the third rotating body is respectively connected with the first rotating body and the second rotating body. output;

a fixing piece for fixing the first rotating body and the second rotating body of the speed change unit;

a control part, the control part can move along the axial direction of the first fixed axis, and can control the connection and separation of the first rotating body and the second rotating body and the fixed part during the movement, and the first rotating body and the fourth rotating body The connection and separation of the rotating body and the driving body;

The central axes of the first fixed shaft and the second fixed shaft are not arranged in parallel.

Further, the fixing member includes a first fixed shaft fixed on the bicycle frame, a first connecting member for connecting the first fixed shaft and the first rotating body, and a first connecting member for connecting the first fixed shaft and the second rotating body. the second connecting part.

Further, both the first connecting member and the second connecting member are fixedly connected with the first fixed axis.

Further, a third connecting member is arranged between the driving body and the first rotating body, and a fourth connecting member is arranged between the driving body and the fourth rotating body, and the third connecting member is used to connect the driving body and the first rotating body. A rotating body, and the fourth connecting member is used for connecting the driving body and the fourth rotating body.

Further, between the first rotating body and the first connecting member, between the second rotating body and the second connecting member, between the third connecting member and the first rotating body, and between the fourth connecting member and the fourth rotating body A concave portion and a convex portion that cooperate with each other are arranged therebetween.

Further, the control part includes a trigger member that can move along the axial direction of the first fixed axis, and the trigger member is respectively connected with the first connecting member, the second connecting member, the third connecting member and the fourth connecting member during the movement process. The connecting members are in contact so that the first rotating body and the first connecting member, the second rotating body and the second connecting member, the third connecting member and the first rotating body, and the fourth connecting member and the fourth rotating body separated in between.

Further, the trigger part includes a cam surface matching the first connection part, the second connection part, the third connection part and the fourth connection part, when the first connection part, the second connection part, the third connection part When the member and the fourth connecting member are in contact with the cam surface, the first connecting member, the second connecting member, the third connecting member and the fourth connecting member are respectively separated from the corresponding rotating body.

Further, the connection between the third rotating body and the first rotating body and the second rotating body is a bevel gear connection mechanism.

Further, the first rotating body and the second rotating body are in direct contact.

Further, it also includes a casing, the speed change unit, the fixing part and the control part are all arranged inside the casing, and the two ends of the casing are respectively connected with the second rotating body and the fourth rotating body through a one-way connection structure, The one-way connection structure includes a clamping slot opened on the inner wall of the casing and a clamping claw arranged on the outside of the second rotating body and the fourth rotating body and matched with the clamping slot.

Compared with the prior art, the beneficial effects of the present invention are: the present invention takes the differential gear train composed of the first rotating body, the second rotating body, the third rotating body and the fourth rotating body as the main body, which can meet the external dimensions. At the same time, the gear module can be increased, the bending strength can be greatly enhanced, and the service life of the transmission can be increased.

Description of drawings

Fig. 1 is a disassembled perspective view of the internal structure of a bicycle internal differential transmission;

Fig. 2 is a disassembled perspective view of a fixed part and a control part in a bicycle internal differential transmission;

3 is a disassembled perspective view of a driving body in a bicycle internal differential transmission;

4 is a cross-sectional view of a speed change unit in a bicycle internal differential transmission;

Figure 5 is a disassembled perspective view of a speed change unit in a bicycle internal differential transmission;

Figure 6 is a sectional view of a bicycle inner differential transmission at one of the angles;

FIG. 7 is a cross-sectional view of an inner differential transmission for a bicycle from another angle.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are the present invention. Part of the embodiments of the invention, but not all of the embodiments, based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

Referring to FIG. 1 , an internal differential transmission for bicycles includes a fixed part 4 , a driving body 6 , a speed change unit 3 , a control part 5 , a casing 7 , a first connecting part 8 , a second connecting part 9 , and a third connecting part 10. The fourth connecting part 11 , the left fastener 12 , the right fastener 13 , the left dust cover 14 and the right dust cover 15 .

2, the fixing member 4 includes a first fixed shaft 41, a fixed sleeve 43 and a key 42. The fixed sleeve 43 is keyed to the first fixed shaft 41 through the key 42 to limit its radial rotation. There are two sides of the first fixed shaft 41. The screw thread 411 can make the first fixed shaft 41 and the bicycle frame fixed by screw connection.

Referring to FIGS. 3 and 7 , the driving body 6 is the power input of the inner differential transmission, which includes a sprocket retaining ring 61 , a sprocket 62 and a sprocket carrier 63 . The sprocket retaining ring 61 is fastened on the groove 632 opened in the circumferential direction on the sprocket carrier to block the sprocket 62 to prevent its axial movement. A convex portion 621 is provided on the sprocket 62 and a concave portion 633 is provided on the sprocket carrier. The engagement restricts its radial rotation, and this design can make the assembly of the sprocket 62 and the sprocket carrier 63 more convenient.

4, 5 and 6, the speed change unit 3 includes a first rotating body 31, a second rotating body 32, a third rotating body 33, a fourth rotating body 34 and a second fixed shaft for supporting the third rotating body 35.

The first rotating body 31 , the second rotating body 32 , and the fourth rotating body 34 rotate around the first fixed axis 41 , the third rotating body 33 rotates around the second fixed axis 35 , and the third rotating body 33 is restricted by the screw 36 in the second rotating body 33 . The fixed shaft 35 moves axially, a shaft hole 351 is arranged in the middle of the second fixed shaft 35 , the first fixed shaft 41 passes through the shaft hole 351 , and a shaft sleeve 37 is arranged between the first rotating body 31 and the second rotating body 32 , is used to control the distance between the first rotating body 31 and the second rotating body 32 to facilitate assembly. The axis of the second fixed shaft 35 is perpendicular to the axis 1 of the first fixed shaft 4 and intersects at one point.

The third rotating body 33 is arranged between the first rotating body 31 and the second rotating body 32, the second fixed shaft 35 is connected with the fourth rotating body 34 through the screw 36, the two are relatively stationary, and the rotation of the fourth rotating body 34 can drive the first rotating body 34. The second fixed shaft 35 rotates around the first fixed shaft 41 , thereby driving the third rotating body 33 to revolve.

The connection between the first rotating body 31 and the third rotating body 33 and the second rotating body 32 and the third rotating body 33 is a bevel gear meshing connection. The first rotating body 31 meshes with the third rotating body 33 and the second rotating body 32 Meshing with the third rotating body 33, the number of the third rotating body 33 is set to 2, which are arranged symmetrically along the axis of the second fixed shaft 35, so that the axial force borne by the second fixed shaft 35 can be more reasonable. .

The first rotating body 31 is in direct contact with the second rotating body 32 , the second rotating body 32 includes a second bevel gear 322 , a first fixed shaft cylinder 324 and a first nut 323 , and the second bevel gear 322 and the first fixed shaft cylinder 324 Connected by a special-shaped shaft, the radial rotation is restricted, the axial movement is restricted by the first nut 323, the first fixed shaft cylinder 324 extends along the first fixed shaft 41 to the first rotating body 31, and is in direct contact with it through the ball 38, In this way, the connection between the second rotating body 32 and the fixing member 4 can be controlled at one end of the first rotating body 31 , and the design of the shifting structure can be more reasonable.

Referring to FIG. 2 , the first connecting member 8 and the second connecting member 9 are arranged side by side in the fixing sleeve 43 , and the installation method is as follows: the fixing sleeve 43 has the first gap 432 for the first connecting member 8 and the second connecting member 9 in the fixing sleeve 43 . The second gap 433 is fixed by the rotating shaft 21 on the fixed sleeve 43 . The rotating shaft 21 passes through the first gap 432 and the second gap 433 , and its axis is parallel to the axis of the first fixed shaft 41 . A first connection hole 81 is provided, and a second connection hole 91 is provided on the second connection member, both of which are matched with the rotation shaft 21 , and the first connection member 8 and the second connection member 9 rotate around the rotation shaft 21 .

2 and 4, a return spring is provided on the side of the first connecting member 8, the return spring is connected with the first connecting member 8 on the one hand, and is connected with the fixing sleeve 43 on the other side, and the return spring makes the first end 83 of the second connecting member 8. In a state away from the first fixed axis 41, the first end 83 of the first connecting member 8 is in contact with the first convex portion 311 on the inner surface of the first rotating body 31. At this time, the first fixed axis 41 and the first rotation body 31 is connected. The second connecting member 9 is provided with a first groove 94 and the fixing sleeve 43 is provided with a second groove 434. The two grooves are jointly used to place the retaining spring 22, and the retaining spring 22 makes the front end of the second connecting member 9 93 moves closer to the second rotating body 32 so as to contact the second convex portion 321 on the outer side of the second rotating body 32, so that the first fixed shaft 41 is connected with the second rotating body 32. Here, the first connecting member 8 and the second rotating body 32 are connected. The number of the two connecting parts 9 is two, and they are symmetrically arranged on the fixing sleeve 43, and are also arranged on the other side of the fixing sleeve 43, so that the fixing sleeve 43 is uniformly and reasonably stressed.

3 and 4, the third connecting member 10 and the fourth connecting member 11 are arranged side by side in the sprocket carrier 63 of the driving body 6, and the arrangement is as follows: the sprocket carrier 63 is provided with a third connecting member 10. The three gaps 632 and the fourth gap 631 of the fourth connecting member 11 are fixed by the rotating shaft 20 on the sprocket carrier 63, and a third groove 634 is provided on the sprocket carrier 63, on which the retaining spring 23 is buckled; the rotating shaft 20 passes through the third gap 631 and the fourth gap 632, its axis is parallel to the axis of the first fixed shaft 41, the third hole 102 provided on the third connecting part 10, the fourth hole provided on the fourth connecting part 11 112 is matched with the rotating shaft 20 , and the third connecting member 10 and the fourth connecting member 11 both rotate around the rotating shaft 20 . The side surfaces of the third connecting member 10 and the fourth connecting member 11 are provided with return springs. While connecting with the third connecting member 10 and the fourth connecting member 11 , the restoring springs are connected with the sprocket carrier 63 . The first end 101 of the third connecting member 10 and the first end 111 of the fourth connecting member 11 are in a raised state, so that the first end 101 of the third connecting member is in contact with the first convex portion 311 on the inner surface of the first rotating body, thereby contacting the first The rotating body 31 is connected, and the first end 111 of the fourth connecting member 11 is in contact with the third convex portion 341 on the inner surface of the fourth rotating body, so as to be connected with the fourth rotating body 34 .

2 , the control part 5 includes a trigger member 51, a return spring 52, a traction rope and an elastic retaining ring 53. The trigger member 51 can be pulled by a traction rope (not shown in the figure) along the axis of the first fixed shaft 41. When moving upward, one end of the return spring 52 is fixed on the head end of the trigger member 51 through the elastic retaining ring 53, so as to realize the automatic return when there is no traction force. The trigger member 51 is provided with a first inclined surface 511 , a second inclined surface 513 , a third inclined surface 514 , a fourth inclined surface 516 , a first convex portion 512 , and a second convex portion 515 . The second end 84 interacts with the front end 93 of the second connecting member 9 , and the second protruding portion 515 interacts with the second end 104 of the third connecting member and the second end 114 of the fourth connecting member. The first, second, third and fourth connecting parts are all provided with inclined surfaces, and the inclined surfaces correspond to the inclined surfaces of the triggering part, wherein the corresponding relationship is: the first inclined surface 511 of the triggering part interacts with the inclined surface 92 of the second connecting part , the second inclined surface 513 of the triggering part interacts with the inclined surface 82 of the first connecting part, the third inclined surface 514 of the triggering part interacts with the inclined surface 103 of the third connecting part, the fourth inclined surface 516 of the triggering part acts with the inclined surface 113 of the fourth connecting part, and the contact of the inclined surfaces makes the triggering When the component 51 moves in the axial direction, the upper convex portion can smoothly act on each connecting component, the return spring acting on each connecting component connects the connecting component with each rotating body, and the convex portion on the triggering component 51 acts on each connecting component. The above connection can be released to achieve separation.

Referring to FIGS. 1 and 6 , a first one-way connection is provided between the second rotating body 32 and the housing 7 . 16 is provided with a first circlip 18, the circlip 18 rotates the front end of the claw 16 away from the first fixed axis 41, the casing 7 is provided with a first groove 71, the first claw 16 and the first groove 71 When the rotation speed of the second rotating body 32 is greater than the rotation speed of the casing 7, the one-way connection works. When the rotating speed of the second rotating body 32 is lower than the rotating speed of the casing 7, the one-way connection Connection does not work. A second one-way connection is provided between the fourth rotating body 34 and the housing 7, and the connection method is as follows: the fourth rotating body 34 is provided with a second claw 17, and the second claw is provided with a second retaining spring 19. The retaining spring 19 rotates the front end of the pawl 17 away from the first fixed axis 41. The housing 7 is provided with a second retaining slot 72, and the second retaining pawl 17 is engaged with the second retaining slot 72 to realize a one-way connection. When the rotational speed of the fourth rotating body 34 is greater than the rotational speed of the housing 7 , the one-way connection works, and when the rotational speed of the fourth rotating body 34 is lower than the rotational speed of the housing 7 , the one-way connection does not work.

1-6, when the trigger member 51 is farthest from the speed change unit 3, the second end 84 of the first connecting member 8 is in contact with the trigger member protrusion 512, and the fixing member 4 is not connected to the first rotating body 31 at this time. The front end 93 of the second connecting member 9 is not in contact with the trigger member protrusion 512, and under the action of the retaining spring 22, the front end 93 of the second connecting member moves closer to the second rotating body 32 and contacts the second convex portion on the outer side of the second rotating body 321, the fixing member 4 is connected with the second rotating body 32, and the second rotating body 32 is stuck; the second end 104 of the third connecting member is not in contact with the protruding part 515 of the triggering member, and at this time the first end 101 of the third connecting member In contact with the convex part 311 on the inner surface of the first rotating body, the driving body 6 is connected with the first rotating body 31; the second end 114 of the fourth connecting member 11 is in contact with the convex part 515 of the triggering part, and the driving body 6 is not in contact with the fourth rotating body at this time. 34 is connected; the power is transmitted from the driving body 6 to the third connecting part 10, the third connecting part 10 is transmitted to the first rotating body 31, and the first rotating body 31 drives the third rotating body 33 to rotate along the second fixed axis 35 and the first rotating body 33. The fixed axis 41 revolves, and the third rotating body 33 revolves to drive the fourth rotating body 34 to rotate around the first fixed axis 41 , and the fourth rotating body 34 outputs the motion to the casing 7 through the second jaw 17 . The rotating speed of the fourth rotating body 34 is the same as the revolution speed of the third rotating body 33 , and the rotating speed of the fourth rotating body 34 is half of the rotating speed of the first rotating body 31 , which is deceleration at this time.

1-6, when the trigger member 51 approaches the speed change unit 3 along the first fixed axis 41, the second end 84 of the first connecting member 8 is in contact with the trigger member protrusion 512, and the fixing member 4 is in contact with the first The rotating body 31 is not connected; the inclined surface 92 of the second connecting member is in contact with the inclined surface 511 of the trigger member, and as the trigger member 51 continues to approach the speed change unit, the front end 93 of the second connecting member is in contact with the trigger member protrusion 512, and the The front end 93 is far away from the second rotating body 32, at this time the fixing member 4 is not connected with the second rotating body 32; the third connecting member slope 103 is in contact with the trigger member slope 514, and as the trigger member 51 continues to approach the speed change unit, the third connection The second end 104 of the component is in contact with the trigger protrusion 515, the first end 101 of the third connecting component is away from the first rotating body 31, and the driving body 6 is not connected to the first rotating body 31 at this time; the second end of the fourth connecting component 34 114 As the trigger member 51 continues to approach the speed change unit 3, it is separated from the trigger member convex portion 515. At this time, the first end 111 of the fourth connecting member 11 is in contact with the inner side convex portion 341 of the fourth rotating body 34 under the action of the return spring, driving the The body 6 is connected with the fourth rotating body 34; at this time, the power is transmitted to the fourth connecting member 11 through the driving body 6, the fourth connecting member 11 is transmitted to the fourth rotating body 34, and the fourth rotating body 34 is connected by the second claw 17. The movement is output to the housing 7 . The rotational speed of the fourth rotating body 11 is the same as the rotational speed of the driving body 6 , which is a constant speed at this time.

1-6, when the trigger member 51 continues to approach the speed change unit 3 along the first fixed axis 41, the second end 84 of the first connection member is separated from the trigger member protrusion 512. One end 83 is in contact with the convex portion 311 on the inner side of the first rotating body 31 under the action of the return spring, the first rotating body 31 is connected with the fixing member 4, and the first rotating body is stuck; the front end 93 of the second connecting member is connected to the trigger. The second connecting part 9 is not connected with the second rotating body 32; the second end 104 of the third connecting part is in contact with the triggering part protrusion 515, and the third connecting part 10 is not connected with the first rotating body 31 ; The second end 114 of the fourth connecting member is separated from the trigger convex portion 515, and the first end 111 of the fourth connecting member 11 is in contact with the convex portion 341 on the inner side of the fourth rotating body 34 under the action of the return spring. At this time, the driving body 6 is connected with the fourth rotating body 34; the power is transmitted to the fourth connecting member 34 through the driving body 6, and the fourth rotating body 34 drives the third rotating body 33 to revolve along the first fixed axis 41 and the second fixed axis 35 to rotate, and the third The rotation of the rotating body 33 drives the second rotating body 32 to rotate, and the second rotating body 32 outputs the motion to the casing 7 through the second jaw 16 . The rotation speed of the second rotating body 32 is twice the speed of the fourth rotating body 34 . This is the speedup.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A bicycle inner differential transmission, characterized in that, comprising: A driving body, which is connected with the bicycle frame and is used to transmit human driving force; The speed change unit includes a first rotating body and a second rotating body rotating around a first fixed axis, a third rotating body rotating around the second fixed axis, and a fourth rotating body fixedly connected with the second fixed axis, the fourth rotating body The rotating body rotates around the first fixed axis, and the third rotating body is respectively connected with the first rotating body and the second rotating body. output; a fixing piece for fixing the first rotating body and the second rotating body of the speed change unit; a control part, the control part can move along the axial direction of the first fixed axis, and can control the connection and separation of the first rotating body and the second rotating body and the fixed part during the movement, and the first rotating body and the fourth rotating body The connection and separation of the rotating body and the driving body; The central axes of the first fixed shaft and the second fixed shaft are not arranged in parallel. 2 . The bicycle internal differential transmission according to claim 1 , wherein the fixing member comprises a first fixed shaft fixed on the bicycle frame, which is used for connecting the first fixed shaft and the first rotation. 3 . The first connecting part of the body and the second connecting part for connecting the first fixed shaft and the second rotating body. 3 . The bicycle internal differential transmission according to claim 2 , wherein the first connecting member and the second connecting member are both fixedly connected to the first fixed shaft. 4 . 4 . The bicycle internal differential transmission according to claim 1 , wherein a third connecting member is arranged between the driving body and the first rotating body, and a third connecting member is arranged between the driving body and the fourth rotating body. 5 . There is a fourth connecting member, the third connecting member is used to connect the driving body and the first rotating body, and the fourth connecting member is used to connect the driving body and the fourth rotating body. 5. An internal differential transmission for bicycles according to claim 4, characterized in that: between the first rotating body and the first connecting member, between the second rotating body and the second connecting member, the third rotating body and the second connecting member A concave portion and a convex portion that cooperate with each other are provided between the connecting member and the first rotating body and between the fourth connecting member and the fourth rotating body. 6 . The bicycle internal differential transmission according to claim 4 , wherein the control part comprises a trigger member that can move along the axial direction of the first fixed axis, and the trigger member is respectively connected with the trigger member during the movement process. 7 . The first connecting member, the second connecting member, the third connecting member, and the fourth connecting member are in contact with each other, so that between the first rotating body and the first connecting member, between the second rotating body and the second connecting member, and the third connecting member The connecting member and the first rotating body and the fourth connecting member and the fourth rotating body are separated successively. 7 . The internal differential transmission for bicycle according to claim 6 , wherein the triggering member comprises a connection with the first connecting member, the second connecting member, the third connecting member and the fourth connecting member. 8 . Matching cam surfaces, when the first connection part, the second connection part, the third connection part and the fourth connection part are in contact with the cam surface, the first connection part, the second connection part, the third connection part and the fourth connection part The connecting parts are separated from the corresponding rotating bodies, respectively. 8 . The bicycle internal differential transmission according to claim 7 , wherein the connection between the third rotating body and the first rotating body and the second rotating body is a bevel gear connection mechanism. 9 . 9 . The bicycle internal differential transmission according to claim 8 , wherein the first rotating body and the second rotating body are in direct contact. 10 . 10 . The bicycle internal differential transmission according to claim 1 , further comprising a casing, wherein the shifting unit, the fixing part and the control part are all arranged inside the casing, and the two parts of the casing are 10 . The ends are respectively connected with the second rotating body and the fourth rotating body through a one-way connection structure. slot to match the jaws.

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