Internal differential transmission for bicycle

Abstract

The present invention provides an internal differential transmission for a bicycle, comprising a driving body for transmitting human driving force, a fixing member for fixing the speed change unit, the speed change unit and a control unit, wherein the speed change unit changes the speed of the motion input by the driving body and outputs it through a second rotating body or a fourth rotating body, and the control unit can move along the axial direction of a first fixed axis, and can control the connection and separation of the first rotating body and the second rotating body with the fixing member, and the connection and separation of the first rotating body and the fourth rotating body with the driving body during the movement; the present invention takes the differential gear system composed of the first rotating body, the second rotating body, the third rotating body and the fourth rotating body as the main body, and can increase the gear module while meeting the external dimensions, so that the bending strength is greatly enhanced, and the service life of the transmission is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of bicycle speed changing equipment, and in particular relates to an internal differential transmission for a bicycle. Background Art

[0002] The emergence of bicycles has greatly facilitated people's travel. With the improvement of production technology, the development of science and technology and humanistic spirit, people have higher requirements for bicycles. The design and manufacture of bicycles are constantly improving, their structure and technology are becoming more and more reasonable, and their performance is also constantly improving. With the emergence of bicycles, variable-speed bicycles have also begun to develop. At present, the transmission of bicycles is roughly divided into two categories: tower wheel type external transmission and closed internal transmission. The external transmission 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 achieve the change of transmission ratio. However, the external transmission is exposed to the outside of the bicycle and is easily corroded by rain, dust, and grease, making maintenance more cumbersome, the service life is short, and the appearance is not very beautiful. The internal transmission speed change device is hidden inside the shaft barrel and is protected by multiple layers of special sealing materials to avoid exposure to the outside world. Therefore, rain, dust, grease, etc. cannot enter, and it also avoids the sun's exposure and wind and rain erosion. Therefore, regular maintenance is not required, achieving the advantages of maintenance-free, precision, durability, and lightness.

[0003] The existing three-speed transmission in bicycles is mainly based on planetary gear trains. Due to its structural design, the speed increase ratio must be less than 2 in theory, and the speed reduction ratio must be greater than 0.5. In actual production, the transmission ratio is limited to a greater extent under the premise of ensuring cost and performance. The speed increase ratio can only be 1.4, and the speed reduction ratio can only be 0.7. The consequence is that the speed increase is not strong when the speed increases, the climbing is difficult at low speed, and the acceleration and deceleration are not obvious when riding. The internal transmission with planetary gear train as the main body is limited by the size limit because the axis around which each gear revolves is parallel to the bicycle hub shaft. The module of the general gear is 0.8-1, resulting in low bending strength. Summary of the invention

[0004] The object of the present invention is to provide a bicycle internal differential transmission with a larger transmission ratio and greater bending strength.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: an internal differential transmission for a bicycle, comprising:

[0006] A driving body connected to the bicycle frame and used for transmitting human driving force;

[0007] A speed change unit comprises 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 to the second fixed axis, wherein the fourth rotating body rotates around the first fixed axis, the third rotating body is respectively connected to the first rotating body and the second rotating body in a transmission manner, and the speed change unit changes the speed of the motion input by the driving body and outputs the motion through the second rotating body or the fourth rotating body;

[0008] A fixing member, used for fixing the first rotating body and the second rotating body of the speed change unit;

[0009] A control unit, which 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 with the fixed member, and the connection and separation of the first rotating body and the fourth rotating body with the driving body during the movement;

[0010] The central axes of the first fixed axis and the second fixed axis are not arranged in parallel.

[0011] Furthermore, the fixing member includes a first fixed shaft fixed on the bicycle frame, a first connecting component for connecting the first fixed shaft and the first rotating body, and a second connecting component for connecting the first fixed shaft and the second rotating body.

[0012] Furthermore, the first connecting component and the second connecting component are both fixedly connected to the first fixed axis.

[0013] Furthermore, a third connecting component is provided between the driving body and the first rotating body, and a fourth connecting component is provided between the driving body and the fourth rotating body. The third connecting component is used to connect the driving body and the first rotating body, and the fourth connecting component is used to connect the driving body and the fourth rotating body.

[0014] Furthermore, mutually matching recesses and protrusions are provided 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.

[0015] Furthermore, the control part includes a trigger component that can move axially along the first fixed axis. During the movement, the trigger component contacts the first connecting component, the second connecting component, the third connecting component and the fourth connecting component respectively, so that the first rotating body and the first connecting component, the second rotating body and the second connecting component, the third connecting component and the first rotating body, and the fourth connecting component and the fourth rotating body are separated in sequence.

[0016] Furthermore, the trigger component includes a cam surface matching the first connecting component, the second connecting component, the third connecting component and the fourth connecting component. When the first connecting component, the second connecting component, the third connecting component and the fourth connecting component contact the cam surface, the first connecting component, the second connecting component, the third connecting component and the fourth connecting component are respectively separated from the corresponding rotating bodies.

[0017] Furthermore, the third rotating body is connected to the first rotating body and the second rotating body by a bevel gear connection mechanism.

[0018] Furthermore, the first rotating body is in direct contact with the second rotating body.

[0019] Furthermore, it also includes a shell, and the speed change unit, fixing part and control part are all arranged inside the shell, and the two ends of the shell are respectively connected to the second rotating body and the fourth rotating body through a one-way connection structure, and the one-way connection structure includes a slot opened on the inner wall of the shell and a claw arranged on the outside of the second rotating body and the fourth rotating body and matching the slot.

[0020] Compared with the prior art, the beneficial effects of the present invention are: the present invention, with the differential gear system composed of the first rotating body, the second rotating body, the third rotating body and the fourth rotating body as the main body, can increase the gear module while meeting the external dimensions, greatly enhance the bending strength, and increase the service life of the transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a disassembled stereoscopic diagram of the internal structure of an internal differential transmission for a bicycle;

[0022] Figure 2 It is a disassembled stereoscopic view of a fixing part and a control part in an internal differential transmission for a bicycle;

[0023] Figure 3 It is a disassembled stereoscopic view of a driving body in an internal differential transmission for a bicycle;

[0024] Figure 4 The present invention is a cross-sectional view of a speed change unit in an internal differential transmission for a bicycle;

[0025] Figure 5 The present invention is a disassembled stereoscopic diagram of a speed change unit in an internal differential transmission for a bicycle;

[0026] Figure 6 The present invention is a cross-sectional view of an internal differential transmission for a bicycle at one angle;

[0027] Figure 7 The present invention is a cross-sectional view of an internal differential transmission for a bicycle at another angle. DETAILED DESCRIPTION

[0028] In order to make the purpose, 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 in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0029] See also Figure 1 A bicycle internal differential transmission includes a fixing member 4, a driving body 6, a speed change unit 3, a control unit 5, a housing 7, a first connecting member 8, a second connecting member 9, a third connecting member 10, a fourth connecting member 11, a left fastener 12, a right fastener 13, a left dust cover 14 and a right dust cover 15.

[0030] See also Figure 2 The fixing member 4 includes a first fixed shaft 41, a fixing sleeve 43 and a key 42. The fixing sleeve 43 is key-connected with the first fixed shaft 41 through the key 42 to limit its radial rotation. There are threads 411 on both sides of the first fixed shaft 41, which can fix the first fixed shaft 41 to the bicycle frame through threaded connection.

[0031] See also Figure 3 , Figure 7 The driving body 6 is the power input of the internal differential transmission, and includes a sprocket retaining ring 61, a sprocket 62 and a sprocket carrier 63. The sprocket retaining ring 61 is engaged with a groove 632 provided on the sprocket carrier along the circumferential direction to block the sprocket 62 and prevent it from moving axially. The convex portion 621 provided on the sprocket 62 engages with the concave portion 633 provided on the sprocket carrier to limit its radial rotation. Such a design makes it more convenient to assemble the sprocket 62 and the sprocket carrier 63.

[0032] See also Figure 4 , Figure 5 and Figure 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 35 for supporting the third rotating body.

[0033] The first rotating body 31, the second rotating body 32, and the fourth rotating body 34 rotate around the first fixed axis 41, and the third rotating body 33 rotates around the second fixed axis 35. The third rotating body 33 is limited to axial movement on the second fixed axis 35 by a screw 36. An axial hole 351 is provided in the middle of the second fixed axis 35, and the first fixed axis 41 passes through the axial hole 351. A sleeve 37 is provided between the first rotating body 31 and the second rotating body 32 for controlling the distance between the first rotating body 31 and the second rotating body 32 for easy assembly. The axis of the second fixed axis 35 is perpendicular to the axis line of the first fixed axis 4 and intersects at one point.

[0034] The third rotating body 33 is arranged between the first rotating body 31 and the second rotating body 32. The second fixed axis 35 is connected to the fourth rotating body 34 by a screw 36. The two are relatively stationary. The rotation of the fourth rotating body 34 can drive the second fixed axis 35 to rotate around the first fixed axis 41, thereby driving the third rotating body 33 to revolve.

[0035] The connection between the first rotating body 31 and the third rotating body 33, and the connection between the second rotating body 32 and the third rotating body 33 are bevel gear meshing connections. The first rotating body 31 meshes with the third rotating body 33, and the second rotating body 32 meshes with the third rotating body 33. The number of the third rotating bodies 33 is set to 2, which are symmetrically arranged along the axis of the second fixed shaft 35, so that the axial force borne by the second fixed shaft 35 can be more reasonably borne.

[0036] The first rotating body 31 is in direct contact with the second rotating body 32, and the second rotating body 32 includes a second bevel gear 322, a first fixed shaft cylinder 324 and a first nut 323. The second bevel gear 322 is connected to the first fixed shaft cylinder 324 through a special-shaped shaft to limit its radial rotation, and the first nut 323 is used to limit its axial movement. The first fixed shaft cylinder 324 extends along the first fixed axis 41 to the first rotating body 31 and is in direct contact with it through a ball bearing. This is to control the connection between the second rotating body 32 and the fixed part 4 at one end of the first rotating body 31, so that the shifting structure design can be more reasonable.

[0037] See also Figure 2 The first connecting component 8 and the second connecting component 9 are arranged side by side in the fixed sleeve 43, and the placement method is: there are a first gap 432 for placing the first connecting component 8 and a second gap 433 for placing the second connecting component 9 in the fixed sleeve 43, and the fixed sleeve 43 is fixed by the rotating shaft 21. The rotating shaft 21 passes through the first gap 432 and the second gap 433, and its axis is parallel to the axis line of the first fixed shaft 41. The first connecting component 8 is provided with a first connecting hole 81, and the second connecting component is provided with a second connecting hole 91. Both cooperate with the rotating shaft 21, and the first connecting component 8 and the second connecting component 9 rotate around the rotating shaft 21.

[0038] See also Figure 2 , Figure 4, a return spring is arranged on the side of the first connecting member 8, and the return spring is connected to the first connecting member 8 on one side and to the fixing sleeve 43 on the other side. The return spring makes the first end 83 of the second connecting member 8 in a state away from the first fixed shaft 41, so that the first end 83 of the first connecting member 8 contacts the first convex portion 311 on the inner side of the first rotating body 31, and at this time, the first fixed shaft 41 is connected to the first rotating body 31. A first groove 94 is arranged on the second connecting member 9 and a second groove 434 is arranged on the fixing sleeve 43. The two grooves are used to place the retaining spring 22 together. The retaining spring 22 makes the front end 93 of the second connecting member 9 approach 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 to the second rotating body 32. Here, the number of the first connecting member 8 and the second connecting member 9 are both 2, which are symmetrically arranged on the fixing sleeve 43, and are arranged in the same way on the other side of the fixing sleeve 43, so that the force on the fixing sleeve 43 is uniform and reasonable.

[0039] See also Figure 3 and Figure 4 The third connecting component 10 and the fourth connecting component 11 are arranged side by side in the sprocket carrier 63 of the driving body 6, and the placement method is: a third gap 632 for accommodating the third connecting component 10 and a fourth gap 631 for accommodating the fourth connecting component 11 are opened in the sprocket carrier 63, and are fixed on the sprocket carrier 63 by the rotating shaft 20, and a third groove 634 is arranged on the sprocket carrier 63, and the retaining spring 23 is buckled on it; the rotating shaft 20 passes through the third gap 631 and the fourth gap 632, and its axis is arranged parallel to the axis of the first fixed shaft 41, and the third hole 102 provided on the third connecting component 10 and the fourth hole 112 provided on the fourth connecting component 11 cooperate with the rotating shaft 20, and the third connecting component 10 and the fourth connecting component 11 both rotate around the rotating shaft 20. A return spring is arranged on the side of the third connecting part 10 and the fourth connecting part 11. The return spring is connected to the third connecting part 10 and the fourth connecting part 11 on one side and is connected to the sprocket carrier 63 on the other side. The return spring can make the first end 101 of the third connecting part 10 and the first end 111 of the fourth connecting part 11 in a lifted state so that the first end 101 of the third connecting part contacts the first convex portion 311 on the inner side of the first rotating body, thereby connecting to the first rotating body 31, and the first end 111 of the fourth connecting part 11 contacts the third convex portion 341 on the inner side of the fourth rotating body, thereby connecting to the fourth rotating body 34.

[0040] See also Figure 2The control part 5 includes a trigger component 51, a reset spring 52, a traction rope and an elastic retaining ring 53. The trigger component 51 can be pulled by a traction rope (not shown) and then axially moved along the axis of the first fixed shaft 41. One end of the reset spring 52 is fixed to the head end of the trigger component 51 through the elastic retaining ring 53 to achieve automatic reset when there is no traction. The trigger component 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 first convex portion 512 acts on the second end 84 of the first connecting component 8 and the front end 93 of the second connecting component 9, and the second convex portion 515 acts on the second end 104 of the third connecting component and the second end 114 of the fourth connecting component. Inclined surfaces are provided on the first, second, third and fourth connecting parts, and the inclined surfaces correspond to the inclined surfaces of the triggering parts, wherein the corresponding relationship is: the first inclined surface 511 of the triggering part acts on the inclined surface 92 of the second connecting part, the second inclined surface 513 of the triggering part acts on the inclined surface 82 of the first connecting part, the third inclined surface 514 of the triggering part acts on the inclined surface 103 of the third connecting part, and the fourth inclined surface 516 of the triggering part acts on the inclined surface 113 of the fourth connecting part. The contact of the inclined surfaces enables the convex portion on the triggering part 51 to act smoothly on each connecting part when the triggering part 51 moves axially, and the reset spring acting on each connecting part connects the connecting part to each rotating body. When the convex portion on the triggering part 51 acts on each connecting part, this connection relationship can be released to achieve separation.

[0041] See also Figure 1 and Figure 6 A first one-way connection is provided between the second rotating body 32 and the housing 7, and the connection method is as follows: a first claw 16 is provided on the second rotating body 32, and a first clamping spring 18 is provided on the first claw 16. The clamping spring 18 makes the front end of the claw 16 rotate away from the first fixed axis 41. A first slot 71 is provided on the housing 7, and the first claw 16 engages with the first slot 71 to achieve a one-way connection. When the rotation speed of the second rotating body 32 is greater than the rotation speed of the housing 7, the one-way connection works. When the rotation speed of the second rotating body 32 is less than the rotation speed of the housing 7, the one-way 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: a second claw 17 is provided on the fourth rotating body 34, and a second clamping spring 19 is provided on the second claw. The clamping spring 19 makes the front end of the claw 17 rotate away from the first fixed axis 41. A second slot 72 is provided on the housing 7, and the second claw 17 engages with the second slot 72 to achieve a one-way connection. When the rotation speed of the fourth rotating body 34 is greater than the rotation speed of the housing 7 , the one-way connection acts, and when the rotation speed of the fourth rotating body 34 is less than the rotation speed of the housing 7 , the one-way connection does not act.

[0042] See also Figure 1-Figure 6When the trigger component 51 is farthest from the speed change unit 3, the second end 84 of the first connecting component 8 contacts the trigger component protrusion 512, and at this time, the fixing member 4 is not connected to the first rotating body 31; the front end 93 of the second connecting component 9 is not in contact with the trigger component protrusion 512, and under the action of the retaining spring 22, the front end 93 of the second connecting component moves closer to the second rotating body 32 and contacts the second protrusion 321 on the outer side surface of the second rotating body, the fixing member 4 is connected to the second rotating body 32, and the second rotating body 32 is stuck; the second end 104 of the third connecting component is not in contact with the trigger component protrusion 515, and at this time, the first end 101 of the third connecting component The driving body 6 is connected to the first rotating body 31 by contacting with the inner side convex part 311 of the first rotating body; the second end 114 of the fourth connecting part 11 is in contact with the triggering part convex part 515, and the driving body 6 is not connected to the fourth rotating body 34 at this time; the power is transmitted from the driving body 6 to the third connecting part 10, and 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 revolve around the first fixed axis 41, and the third rotating body 33 revolves around the first fixed axis 41, and the fourth rotating body 34 outputs the motion to the housing 7 through the second claw 17. The rotation speed of the fourth rotating body 34 is the same as the revolution speed of the third rotating body 33, and the rotation speed of the fourth rotating body 34 is half of the rotation speed of the first rotating body 31, which is a deceleration at this time.

[0043] See also Figure 1-Figure 6 When the trigger component 51 approaches the speed change unit 3 along the first fixed axis 41, the second end 84 of the first connecting component 8 contacts the trigger component protrusion 512, and at this time, the fixed component 4 is not connected to the first rotating body 31; the second connecting component inclined surface 92 contacts the trigger component inclined surface 511, and as the trigger component 51 continues to approach the speed change unit, the front end 93 of the second connecting component contacts the trigger component protrusion 512, and the front end 93 of the second connecting component moves away from the second rotating body 32, and at this time, the fixed component 4 is not connected to the second rotating body 32; the third connecting component inclined surface 103 contacts the trigger component inclined surface 514, and as the trigger component 51 continues to approach the speed change unit, the second end 84 of the third connecting component contacts the trigger component protrusion 512, and the front end 84 of the second connecting component moves away from the second rotating body 32, and at this time, the fixed component 4 is not connected to the second rotating body 32. 104 contacts with the trigger protrusion 515, and the first end 101 of the third connecting member is away from the first rotating body 31, and the driving body 6 is not connected with the first rotating body 31 at this time; the second end 114 of the fourth connecting member 34 is separated from the trigger protrusion 515 as the trigger member 51 continues to approach the speed change unit 3, and the first end 111 of the fourth connecting member 11 contacts with the inner side protrusion 341 of the fourth rotating body 34 under the action of the return spring, and the driving 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, and the fourth connecting member 11 is transmitted to the fourth rotating body 34, and the fourth rotating body 34 outputs the motion to the housing 7 through the second claw 17. The rotation speed of the fourth rotating body 11 is the same as the rotation speed of the driving body 6, which is a constant speed at this time.

[0044] See also Figure 1-Figure 6 When the trigger component 51 continues to approach the speed change unit 3 along the first fixed axis 41, the second end 84 of the first connecting component is separated from the trigger component protrusion 512. At this time, the first end 83 of the first connecting component 8 contacts the inner side protrusion 311 of the first rotating body 31 under the action of the return spring, and the first rotating body 31 is connected to the fixing member 4, and the first rotating body is stuck; the front end 93 of the second connecting component contacts the trigger component protrusion 512, and the second connecting component 9 is not connected to the second rotating body 32; the second end 104 of the third connecting component contacts the trigger component protrusion 515, and the third connecting component 10 is not connected to the first rotating body 31; the fourth connecting component The second end 114 disengages from the trigger member protrusion 515, and the first end 111 of the fourth connecting component 11 contacts the inner side protrusion 341 of the fourth rotating body 34 under the action of the return spring. At this time, the driving body 6 is connected to the fourth rotating body 34; the power is transmitted to the fourth connecting component 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 rotate along the second fixed axis 35. The rotation of the third rotating body 33 drives the second rotating body 32 to rotate, and the second rotating body 32 outputs the motion to the shell 7 through the second claw 16. The rotation speed of the second rotating body 32 is twice the speed of the fourth rotating body 34, which is an increase in speed at this time.

[0045] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An internal differential transmission for a bicycle, characterized in that: include: A driving body connected to the bicycle frame and used for transmitting human driving force; A speed change unit comprises 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 to the second fixed axis, wherein the fourth rotating body rotates around the first fixed axis, the third rotating body is respectively connected to the first rotating body and the second rotating body in a transmission manner, and the speed change unit changes the speed of the motion input by the driving body and outputs the motion through the second rotating body or the fourth rotating body; A fixing member, used for fixing the first rotating body and the second rotating body of the speed change unit; A control unit, which 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 with the fixed member, and the connection and separation of the first rotating body and the fourth rotating body with the driving body during the movement; The central axes of the first fixed axis and the second fixed axis are not arranged in parallel; the fixing member includes a first fixed axis fixed on the bicycle frame, a first connecting component for connecting the first fixed axis and the first rotating body, and a second connecting component for connecting the first fixed axis and the second rotating body; a third connecting component is arranged between the driving body and the first rotating body, and a fourth connecting component is arranged between the driving body and the fourth rotating body, the third connecting component is used to connect the driving body and the first rotating body, and the fourth connecting component is used to connect the driving body and the fourth rotating body.

2. The internal differential transmission for a bicycle according to claim 1, characterized in that: The first connecting component and the second connecting component are both fixedly connected to the first fixed shaft.

3. The internal differential transmission for a bicycle according to claim 1, characterized in that: Mutually matching recesses and protrusions are provided 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.

4. The internal differential transmission for a bicycle according to claim 1, characterized in that: The control part includes a trigger component that can move axially along the first fixed axis. During the movement, the trigger component contacts the first connecting component, the second connecting component, the third connecting component and the fourth connecting component respectively, so that the first rotating body and the first connecting component, the second rotating body and the second connecting component, the third connecting component and the first rotating body, and the fourth connecting component and the fourth rotating body are separated in sequence.

5. The internal differential transmission for a bicycle according to claim 4, characterized in that: The trigger component includes a cam surface matching the first connecting component, the second connecting component, the third connecting component and the fourth connecting component. When the first connecting component, the second connecting component, the third connecting component and the fourth connecting component contact the cam surface, the first connecting component, the second connecting component, the third connecting component and the fourth connecting component are respectively separated from the corresponding rotating bodies.

6. The internal differential transmission for a bicycle according to claim 5, characterized in that: The third rotating body is connected to the first rotating body and the second rotating body by a bevel gear connection mechanism.

7. The internal differential transmission for a bicycle according to claim 6, characterized in that: The first rotating body is in direct contact with the second rotating body.

8. The internal differential transmission for a bicycle according to claim 1, characterized in that: It also includes a shell, and the speed change unit, fixing part and control part are all arranged inside the shell. The two ends of the shell are respectively connected to the second rotating body and the fourth rotating body through a one-way connection structure. The one-way connection structure includes a slot opened on the inner wall of the shell and a claw arranged on the outside of the second rotating body and the fourth rotating body and matching the slot.

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