Flexible transmission structure of bicycle

Abstract

The invention relates to a flexible transmission structure of a bicycle, which comprises a stop block 2, a right crank 3, a pressure spring 5, a stress rod 6, a chain plate 7 and a middle shaft 8, the chain plate 7 is sleeved on the middle shaft 8 and can rotate on the middle shaft 8, the stress rod 6 and the stop block 2 are fixed on the chain plate 7, the stress rod 6 is arranged on the front side of the right crank 3, the stop block 2 is arranged on the rear side of the right crank 3, a stress block A is fixed on the stress rod 6, and the pressure spring 5 is fixed on the stress block A; the two ends of the compression spring 5 are arranged on spring seats on the upper portions of the stress rod 6 and the right crank 3 in a sleeved mode, the check block 2 blocks the right crank 3 to enable the compression spring 5 to have pre-tightening force, when the right pedal 4 rotates to the position close to an upper dead center, the compression spring 5 is compressed when the right pedal 4 is pedaled, the right pedal 4 can be pedaled to pass through the upper dead center with small force, the right pedal 4 rapidly enters a section with large driving torque, and therefore the driving torque is large. And after the right crank 3 is in contact with the stress block A, the increased force acts on the chain plate 7, and the left pedal 10 can be pedaled over an upper dead center by using smaller force according to the same principle, so that the problem that the legs are easily tired during riding of the bicycle is solved.

Description

Technical Field

[0001] The present invention relates to the field of pedal bicycles represented by bicycles, and a spring and a connecting auxiliary member are added between the transmission members of bicycles and other pedal bicycles to elastically connect the transmission members, so that the transmission system has a certain flexibility. When riding a bicycle uphill or accelerating and pedaling the pedal past the vicinity of the top dead center, the spring added to the transmission system is stressed and functions, and with a smaller force, the pedal can be pedaled past the vicinity of the top dead center, making it easier to ride the bicycle. Background Art

[0002] Currently, in the technical field of bicycles and other pedal bicycles, most are driven by circular pedaling. When the pedal rotates to the vicinity of the top dead center, it is not easy to exert force when pedaling forward, the driving torque is small, and at this time, the knee joint is bent to a large extent, and it is easy to feel leg fatigue when riding uphill. The transmission structure of existing bicycles and other pedal bicycles does not match well with the human pedaling driving method in the vicinity of the top dead center. Summary of the Invention

[0003] The purpose of the present invention is to provide a flexible transmission structure for bicycles. Springs and connecting auxiliary members are added in the links of the crank and chainring, chain and frame, freewheel and rear wheel of the bicycle to elastically connect the transmission members, so that the transmission system has a certain flexibility. When riding a bicycle uphill or accelerating and pedaling the pedal past the vicinity of the top dead center, the spring added to the transmission system is stressed and elastically deformed, and the resistance received when pedaling the pedal is a flexible elastic force. With a smaller force, the pedal can be pedaled past the section near the top dead center, making it easier to ride, thus improving the disadvantages existing in the prior art.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions: A flexible transmission structure for a bicycle, comprising: a spring, a connecting auxiliary member, and a transmission member, characterized in that: a spring and a connecting auxiliary member are added between the transmission members of the bicycle to elastically connect the transmission members, so that the bicycle transmission system has a certain flexibility.

[0005] The spring is a compression spring. The connecting auxiliary member includes a force-receiving rod and a stopper. The transmission member includes a right crank and a chainring. The left crank and the right crank are fixedly connected to the left and right ends of the bottom bracket. The chainring is sleeved on the bottom bracket or on the cylinder of the right crank and can rotate on the bottom bracket or the cylinder of the right crank. The force-receiving rod and the stopper are fixed on the chainring. The force-receiving rod is arranged on the front side of the right crank (when driving the crank to rotate on the bicycle, the front side of the crank is its front side, and the rear side is its rear side). The stopper is arranged on the rear side of the right crank. A force-receiving block is fixed on the force-receiving rod. Spring seats are respectively fixed on the upper part of the force-receiving rod and the upper part of the right crank. Both ends of the compression spring are sleeved on these two spring seats, and the stopper blocks the right crank to make the compression spring have a pre-tightening force.

[0006] The spring is a tension spring. The connection auxiliary member includes: a tension rod, a force-receiving block, and a stop block. The transmission member includes a right crank and a chainring. The chainring is sleeved on the central shaft or on the cylinder of the right crank and can rotate on the central shaft or the cylinder of the right crank. The tension rod and the force-receiving block are fixed on the chainring. The tension rod is arranged at the rear side of the right crank, and the force-receiving block is arranged at the front side of the right crank. The two ends of the tension spring are connected to the upper part of the right crank and the upper part of the tension rod. The stop block fixed on the right crank blocks the tension rod to make the tension spring have a pre-tightening force.

[0007] The spring is a tension spring. The connection auxiliary member includes: an upper swing rod, a tension wheel, a limit rod, a tensioning wheel, a lower swing rod, and a torsion spring. The transmission member includes: a chainring, a frame, a flywheel, and a chain. The chain is intentionally made longer so that it has a certain degree of slack in the free state. One end of the upper swing rod is hinged to the frame, and the other end is connected to the tension wheel. The tension spring is arranged below the upper swing rod. One end of the tension spring is connected to the upper swing rod, and the other end is connected to the frame. The tension wheel presses down on the upper side section of the chain that transmits power between the chainring and the flywheel from above. The lower end of the limit rod is fixed to the frame, and the upper end abuts against the lower surface of the upper swing rod. One end of the lower swing rod is also hinged to the frame, and the other end is connected to the tensioning wheel. The two arms of the torsion spring are respectively blocked by the frame and the lower swing rod. The tensioning wheel presses up on the lower side section of the chain from below, and the elastic force of the torsion spring keeps a certain tension on the lower side section of the chain to prevent the chain from loosening and dropping off.

[0008] The spring is a tension spring. The connection auxiliary member includes: an upper swing rod, a tension wheel, a limit rod, a tensioning wheel, a lower swing rod, and a torsion spring. The transmission member includes: a chainring, a frame, a flywheel, and a chain. The chain is intentionally made longer so that it has a certain degree of slack in the free state. One end of the upper swing rod is hinged to the frame, and the other end is connected to the tension wheel. The tension spring is arranged above the upper swing rod. One end of the tension spring is connected to the upper swing rod, and the other end is connected to the frame. The tension wheel pushes up on the upper side section of the chain that transmits power between the chainring and the flywheel from below. The lower end of the limit rod is fixed to the frame, and the upper end hooks downward on the upper swing rod. The two arms of the torsion spring are respectively blocked by the frame and the lower swing rod, so that the tensioning wheel pushes up on the lower side section of the chain from below, and the lower side section of the chain maintains a certain tension to prevent the chain from loosening and dropping off.

[0009] The spring is a tension spring. The connection auxiliary includes: a support sleeve, a retaining ring, a connection sleeve, a force-receiving block, a driven rod, and a tension rod. The connection member includes a flywheel and a rear wheel or a rear wheel hub. The support sleeve is fixed to the right side of the rear wheel hub of the bicycle. The connection sleeve is sleeved on the support sleeve and can rotate on the support sleeve. The retaining ring blocks the connection sleeve to prevent it from slipping out of the support sleeve. The flywheel is fixedly connected to the connection sleeve. The force-receiving block and the tension rod are fixed to the connection sleeve. The driven rod is fixed to the support sleeve. The driven rod is arranged at the rear side of the tension rod (when driving the flywheel and the tension rod to rotate on the bicycle, the front side of the tension rod is its front side, and the rear side is its rear side). The two ends of the tension spring are connected to the upper parts of the tension rod and the driven rod respectively. The block fixed to the tension rod blocks the driven rod to make the tension spring have a pre-tightening force. The force-receiving block is arranged at the rear side of the driven rod.

[0010] The spring is a compression spring. The connection auxiliary includes: a support sleeve, a retaining ring, a connection sleeve, a driving rod, a driven rod, and a block. The connection member includes a flywheel and a rear wheel or a rear wheel hub. The support sleeve is fixed to the right side of the rear wheel hub of the bicycle. The connection sleeve is sleeved on the support sleeve and can rotate on the support sleeve. The retaining ring blocks the connection sleeve to prevent it from slipping out of the support sleeve. The driving rod is fixed to the connection sleeve. The driven rod and the block are fixed to the support sleeve. The driven rod is arranged at the front side of the driving rod. The two ends of the compression spring are sleeved on the spring seats at the upper parts of the driving rod and the driven rod respectively. The block is arranged at the rear side of the driving rod. The block blocks the driving rod to make the compression spring have a pre-tightening force. The force-receiving block is fixed to the driven rod.

[0011] The flexible transmission structure of the bicycle adds a spring and a connection auxiliary in one of the links of the right crank and chainring, chain and frame, flywheel and rear wheel of the bicycle, so that the transmission parts are elastically connected, and the transmission system between the pedal and the rear wheel has a certain flexibility. When riding a bicycle uphill or accelerating, when pedaling the pedal past the vicinity of the top dead center, the spring added to the transmission system is elastically deformed under force. The resistance received when stepping on the pedal is a flexible elastic force. In this way, a smaller force can be used to pedal the pedal past the section near the top dead center, which can reduce the leg fatigue caused by stepping on the pedal near the top dead center, enable the pedal to quickly pass over the top dead center and enter the section with a larger driving torque, making uphill or accelerating riding easier. This type of flexible transmission structure of the bicycle can improve the deficiencies in the above-mentioned prior art. Brief Description of the Drawings

[0012] Figure 1 It is a schematic structural diagram of Embodiment 1 of the present invention; Figure 2 It is a schematic structural diagram of Embodiment 2 of the present invention: Figure 3 It is a schematic structural diagram of Embodiment 3 of the present invention; Figure 4 It is a schematic structural diagram of Embodiment 4 of the present invention; Figure 5It is a schematic structural diagram of the fifth embodiment of the present invention; Figure 6 It is a schematic structural diagram of the sixth embodiment of the present invention. Specific embodiments

[0013] See appendix Figure 1 For the first embodiment of the present invention, it includes: a stop block 2, a right crank 3, a compression spring 5, a force-receiving rod 6, a chain wheel 7, a central shaft 8, a left crank 9. The right crank 3 and the left crank 9 are fixedly connected to the left and right ends of the central shaft 8. The chain wheel 7 is sleeved on the central shaft 8 or on the cylinder of the right crank 3 and can rotate on the central shaft 8 or the cylinder of the right crank 3. The force-receiving rod 6 and the stop block 2 are fixed on the chain wheel 7. The force-receiving rod 6 is arranged on the front side of the right crank 3 (when driving the crank to rotate on a bicycle, the front side is the front side and the back side is the back side). The stop block 2 is arranged on the back side of the right crank 3. A force-receiving block A is fixed on the force-receiving rod 6. Spring seats are respectively fixed on the upper part of the force-receiving rod 6 and the upper part of the right crank 3. Both ends of the compression spring 5 are sleeved on these two spring seats. The stop block 2 blocks the right crank 3 to make the compression spring 5 have a pre-tightening force.

[0014] When going uphill or accelerating, when the right pedal 4 rotates to near the top dead center, when pedaling the right pedal 4 clockwise, the compression spring 5 is compressed. With a relatively small force, the right pedal 4 can be pedaled past the top dead center, so that the right pedal 4 quickly enters the section with a large driving torque, and the compression spring 5 is further compressed. After the right crank 3 contacts the force-receiving block A, the continuously increasing pedaling force on the right pedal 4 directly acts rigidly on the chain wheel 7. The force-receiving block A blocks the right crank 3 to prevent the compression spring 5 from being damaged. When the right pedal 4 rotates to near the bottom dead center, the driving torque decreases, the pressure on the compression spring 5 decreases. At this time, the bicycle travels by inertia, the compression spring 5 extends (the right crank 3 contacts the stop block 2), and the chain wheel 7 is pushed to rotate clockwise by a certain angle, preparing for the left pedal 10 to be easily pedaled past the top dead center. At this time, the left pedal 10 rotates to near the top dead center. When pedaling the left pedal 10, the compression spring 5 is compressed. With a relatively small force, the left pedal 10 can be pedaled past the top dead center, so that the left pedal 10 quickly enters the section with a large driving torque, and the compression spring 5 is further compressed. After the right crank 3 contacts the force-receiving block A, the continuously increasing pedaling force on the left pedal 10 directly acts rigidly on the chain wheel 7. When the left pedal 10 rotates to near the bottom dead center, the driving torque decreases, the pressure on the compression spring 5 decreases, and the compression spring 5 extends (the right crank 3 contacts the stop block 2), preparing for the right pedal 4 to be easily pedaled past the top dead center. At this time, the right pedal 4 rotates to near the top dead center. In this way, alternately pedaling the left and right pedals rotates half a circle each around the central shaft, driving the chain wheel 7 to rotate, pulling the upper section of the chain 1 to drive the bicycle forward. When the pedal rotates one circle, the compression spring 5 is compressed and extended twice in a cycle.

[0015] Self-lubricating bearings or needle bearings can be provided between the central shaft 8 (or the cylinder of the right crank 3) and the hole of the chain wheel 7 to reduce friction.

[0016] See the appendix Figure 2 For the second embodiment of the present invention, it includes: a tension rod 13, a tension spring 14, a right crank 15, a force-receiving block 16, a chain wheel 17, a central shaft 18. The left crank 19 and the right crank 15 are fixedly connected to the left and right ends of the central shaft 18. In the existing bicycle, the chain wheel is fixedly connected to the central shaft. The chain wheel 17 is sleeved on the central shaft 18 or on the cylinder of the right crank 15 and can rotate on the cylinder of the central shaft 18 or the right crank 15. The tension rod 13 and the force-receiving block 16 are fixed on the chain wheel 17. The tension rod 13 is arranged at the rear side of the right crank 15, and the force-receiving block 16 is arranged at the front side of the right crank 15. One end of the tension spring 14 is connected to the upper part of the right crank 15 and the upper part of the tension rod 13. The stop block B fixed on the right crank 15 blocks the tension rod 13 (the stop block can also be fixed on the tension rod 13 to block the right crank 15) so that the tension spring 14 has a pre-tightening force. When pedaling the pedal, the tension on the tension spring 14 increases and it elongates to a certain extent. Then, the right crank 15 contacts the force-receiving block 16, and the continuously increasing driving force directly acts on the chain wheel 17. The principle and process of making the pedal easily pedal past the top dead center in this embodiment are basically the same as those in the first embodiment.

[0017] The springs in the first embodiment and the second embodiment can also be leaf springs, etc.

[0018] In the first embodiment and the second embodiment, a self-lubricating bearing or a needle bearing, etc. can be arranged between the cylinder of the central shaft or the right crank and the hole of the chain wheel to reduce the friction force.

[0019] See the appendix Figure 3 For the third embodiment of the present invention, it includes: a flywheel 20, a frame 21, an upper swing rod 22, a tension spring 23, a limit rod 24, a tension pulley 25, a chain 26, a chain wheel 27, a tension wheel 28, a lower swing rod 29, and a torsion spring 30. It is intended to make the chain 26 longer so that it has a certain degree of slack in the free state. One end of the upper swing rod 22 is hinged to the frame 21, and the other end is connected to the tension pulley 25. The tension pulley 25 is a small sprocket or a small pulley. The tension spring 23 is arranged below the upper swing rod 22. One end of the tension spring 23 is connected to the upper swing rod 22, and the other end is connected to the frame 21. The tension pulley 25 presses downward from above on the upper side section of the chain 26 that transmits power between the chain wheel 27 and the flywheel 20. The lower end of the limit rod 24 is fixed to the frame, and the upper end abuts against the lower surface of the upper swing rod 22. One end of the lower swing rod 29 is also hinged to the frame 21, and the other end is connected to the tension wheel 28. The tension wheel 28 is also a small sprocket or a small pulley. The two arms of the torsion spring 30 are respectively blocked by the frame 21 and the lower swing rod 29. The tension wheel 28 presses downward from above on the lower side section of the chain 26. The elastic force of the torsion spring 30 keeps a certain tension on the lower side section of the chain 26 to prevent the chain from loosening and dropping off.

[0020] When cycling uphill or accelerating, when the left pedal L rotates to near the bottom dead center, the driving torque decreases, and the tension on the upper section of the chain 26 that transmits the driving force decreases. The tension spring 23 pulls the upper swing rod 22 to swing downward, and the idler wheel 25 presses down on the upper section of the chain 26. At this time, the bicycle travels by inertia. The upper section of the chain 26 pulls the flywheel 20 to rotate clockwise by a larger angle, causing the upper section of the chain 26 to form a curve and increasing its length. At this time, the right pedal R rotates to near the top dead center. Pedaling the right pedal R clockwise rotates it, pulling the upper section of the chain 26. The tension of the upper section of the chain 26 causes the tension spring 23 to stretch and the length of the upper section of the chain 26 to become shorter. At this time, the upper section of the chain 26 is elastic or flexible like a tension spring. The resistance encountered when pushing the right pedal R is the elastic or flexible resistance from the upper section of the chain 26. Therefore, with a smaller force, the right pedal R can be pedaled past the top dead center, enabling the right pedal R to quickly enter the section with a large driving torque. When the right pedal R rotates to near the bottom dead center, the tension on the upper section of the chain 26 decreases. The tension spring 23 pulls the idler wheel 25 downward to make the upper section of the chain 26 longer, preparing for the left pedal L to be easily pedaled past the top dead center. At this time, the left pedal L rotates to near the top dead center. Pedaling the left pedal L clockwise rotates it, and the upper section of the chain 26 is pulled. The tension of the upper section of the chain 26 causes the tension spring 23 to stretch and the upper side length of the chain 26 to become shorter. The upper section of the chain 26 is elastic or flexible like a tension spring. With a smaller force, the left pedal L can be pedaled past the top dead center, enabling the left pedal L to quickly enter the section with a large driving torque. By alternately pedaling the left and right pedals, each rotating half a circle, the bicycle is driven forward. When the pedal rotates one circle, the upper section of the chain 26 becomes longer and shorter twice in a cycle, and the idler wheel 25 and the tension wheel 28 swing up and down twice in a cycle.

[0021] The upper end of the limit rod 24 abuts against the bottom of the swing rod 22, which can control the increase in the length of the upper section of the chain 26. A screw can also be set at the upper end of the limit rod 24 to adjust the increase in the length of the upper section of the chain 26, thereby controlling and adjusting the angle of the section near the top dead center where the pedal can be easily pedaled past.

[0022] See attachment Figure 4, Embodiment 4 of the present invention includes: a flywheel 31, a frame 32, an upper swing rod 33, a tension spring 34, a tension pulley 35, a chain 36, a chainring 37, a limit rod 38, a tension wheel 39, a lower swing rod 40, and a torsion spring 41. It is intended to make the chain 36 longer so that it has a certain degree of slack in the free state. One end of the upper swing rod 33 is hinged to the frame 32, and the other end is connected to the tension pulley 35. The tension spring 34 is arranged above the upper swing rod 33. The tension pulley 35 presses upward against the upper section of the chain 36 from below, pulling upward the upper section of the chain 36 that transmits power between the chainring 37 and the flywheel 31 to increase its length. The lower end of the limit rod 38 is fixed to the frame 32, and its upper end hooks downward to control the increase in the length of the upper section of the chain. One end of the lower swing rod 40 is also hinged to the frame 32, and the other end is connected to the tension wheel 39. The two arms of the torsion spring 41 are blocked by the frame 32 and the lower swing rod 40, so that the tension wheel 39 presses upward against the lower section of the chain 36 to keep a certain tension on the lower section of the chain. The principle and process of making the pedal easily pedal past the top dead center in this embodiment are basically the same as those in Embodiment 3.

[0023] In Embodiments 3 and 4, the springs can also be compression springs, elastic ropes or rubber springs such as elastic bands, and the connecting auxiliary parts can be changed accordingly.

[0024] For a bicycle equipped with a transmission, the transmission applies an elastic force to the lower section of the chain through a guide wheel to give it tension, so the part that applies tension to the lower section of the chain in Embodiments 3 and 4 can be omitted.

[0025] See Appendix Figure 5 , Embodiment 5 of the present invention includes: a support sleeve 42, a retaining ring 43, a connecting sleeve 44, a flywheel 45, a force-bearing block 46, a driven rod 48, a tension spring 49, a tension rod 50, and a chain 51. The support sleeve 42 is fixed to the right side of the rear wheel hub of the bicycle. The connecting sleeve 44 is sleeved on the support sleeve 42 and can rotate on the support sleeve 42. The retaining ring 43 blocks the connecting sleeve 44 from disengaging from the support sleeve 42. The flywheel 45 is fixedly connected to the connecting sleeve 44. The force-bearing block 46 and the tension rod 50 are fixed to the flange of the connecting sleeve 44. The driven rod 48 is fixed to the flange of the support sleeve 42. The driven rod 48 is arranged behind the tension rod 50 (when driving the flywheel 45 and the tension rod 50 to rotate on the bicycle, the front side of the tension rod 50 is its front side, and the rear side is its rear side). The two ends of the tension spring 49 are connected to the upper parts of the tension rod 50 and the driven rod 48 respectively. The stop block C fixed to the tension rod 50 blocks the driven rod 48 to give the tension spring 49 a pre-tension. The force-bearing block 46 is arranged behind the driven rod 48.

[0026] When one of the two pedals rotates to near the bottom dead center, the driving torque decreases, the driving tension on the upper section of the chain 51 decreases, and the other pedal rotates to near the top dead center. When the pedal near the top dead center is pedaled clockwise, the chain 51 drives the flywheel to rotate clockwise, and the tension rod 50 pulls the tension spring 49 to make it elongate. When the pedal near the top dead center is pedaled past the top dead center, the resistance it receives is the elastic force, which is flexible, so it can be pedaled past the top dead center relatively easily, enabling this pedal to quickly enter the section with a large driving torque. After the driving torque increases and the tension spring 49 is stretched to a certain extent, the driven rod 48 contacts the force-receiving block 46, and the continuously increasing driving force directly acts on the rear wheel or the rear-wheel hub. This can protect the tension spring 49 from being damaged. The two pedals alternately pedal past the top dead center easily to drive the bicycle forward. When the pedal rotates one circle, the tension spring 49 is stretched and shortened twice in a cycle.

[0027] See attachment Figure 6 Embodiment Six of the present invention includes: a support sleeve 53, a retaining ring 54, a connecting sleeve 55, a flywheel 56, a stop block 57, a driving rod 58, a compression spring 59, and a driven rod 60. The support sleeve 53 is fixed to the right side of the rear-wheel hub of the bicycle. The connecting sleeve 55 is sleeved on the support sleeve 53 and can rotate on the support sleeve 53. The retaining ring 54 blocks the connecting sleeve 55 from disengaging from the support sleeve 53. The flywheel 56 is fixedly connected to the connecting sleeve 55. The driving rod 58 is fixed to the flange of the connecting sleeve 54. The driven rod 60 and the stop block 57 are fixed to the flange of the support sleeve 53. The driven rod 60 is arranged on the front side of the driving rod 58. The two ends of the compression spring 59 are sleeved on the spring seats at the upper parts of the driving rod 58 and the driven rod 60 respectively. The stop block 57 is arranged on the rear side of the driving rod 58. The stop block 57 blocks the driving rod to make the compression spring 59 have a pre-tightening force. After the driving torque increases, the compression spring 59 is compressed. When the driving rod 58 contacts the force-receiving block D fixed on the driven rod 60, the continuously increasing driving force directly acts on the rear wheel or the rear-wheel hub. This can protect the compression spring 59 from being damaged. The principle and process of the pedal being easily pedaled past the top dead center are basically the same as those in Embodiment Five.

[0028] In Embodiment Five and Embodiment Six, a self-lubricating bearing or a needle bearing can be arranged between the support sleeve and the connecting sleeve to reduce the friction force.

[0029] The flexible structures of the above embodiments can be used for pedal vehicles such as tricycles.

Claims

1. Flexible transmission structure for bicycle, comprising: Spring, connection auxiliary part, transmission part, characterized in that: a spring and a connection auxiliary part are added between the transmission parts of the bicycle to elastically connect the transmission parts, so that the bicycle transmission system has a certain flexibility.

2. The flexible transmission structure of a bicycle according to claim 1, wherein the transmission member includes a right crank and a chainring, and the left crank and the right crank are fixedly connected to the left and right ends of the bottom bracket, and is characterized in that: The chainring is sleeved on the bottom bracket spindle or on the cylinder of the right crank and can rotate on the bottom bracket spindle or the cylinder of the right crank.

3. The flexible bicycle transmission structure according to claim 1, wherein the transmission member comprises: Chainring, frame, flywheel, chain, characterized in that: the chain is intentionally made longer so that it has a certain degree of slack in the free state, and a spring and a connection auxiliary part are added between the frame and the upper side section of the chain for transmitting power, so that the upper side section of the chain is subjected to elastic force in the up and down directions, forming a curve to increase the length, and further making the connection between the chainring and the flywheel in the upper side section for transmitting power have a certain elasticity or flexibility.

4. The flexible transmission structure of a bicycle according to claim 1, characterized in that: The connection auxiliary part includes: a support sleeve, a retaining ring, a connection sleeve. The transmission part includes a flywheel and a rear wheel or a rear wheel hub. The support sleeve is fixed on the right side of the rear wheel hub of the bicycle. The connection sleeve is sleeved on the support sleeve and can rotate on the support sleeve. The retaining ring blocks the connection sleeve so that it does not come out of the support sleeve. The flywheel is fixedly connected to the connection sleeve.

5. The bicycle flexible transmission structure according to claim 1 or 2, wherein the spring is a compression spring, and is characterized in that: The connection auxiliary part includes a force-bearing rod and a stop block. The force-bearing rod and the stop block are fixed on the chainring. The force-bearing rod is arranged on the front side of the right crank. When the crank is driven to rotate on the bicycle, the front side of the crank is its front side and the rear side is its rear side. The stop block is arranged on the rear side of the right crank. A force-bearing block is fixed on the force-bearing rod. Spring seats are respectively fixed on the upper part of the force-bearing rod and the upper part of the right crank. The two ends of the compression spring are sleeved on these two spring seats. The stop block blocks the right crank so that the compression spring has a pre-tightening force.

6. The bicycle flexible transmission structure according to claims 1 and 2, wherein the spring is a tension spring, and is characterized in that: The connection auxiliary part includes: a tension rod, a force-bearing block, a stop block. The tension rod and the force-bearing block are fixed on the chainring. The tension rod is arranged on the rear side of the right crank. The force-bearing block is arranged on the front side of the right crank. The two ends of the tension spring are connected to the upper part of the right crank and the upper part of the tension rod. The stop block fixed on the right crank blocks the tension rod so that the tension spring has a pre-tightening force.

7. The flexible transmission structure of a bicycle according to claim 1 or 3, wherein the spring is a tension spring, characterized in that: The connection auxiliary part includes: an upper swing rod, a tension wheel, a limit rod, a tension pulley, a lower swing rod, a torsion spring. One end of the upper swing rod is hinged to the frame, and the other end is connected to the tension wheel. One end of the lower swing rod is also hinged to the frame, and the other end is connected to the tension pulley. The tension spring is arranged below the upper swing rod. One end of the tension spring is connected to the upper swing rod, and the other end is connected to the frame. The tension wheel presses down on the upper side section of the chain for transmitting power between the chainring and the flywheel from above. The lower end of the limit rod is fixed to the frame, and the upper end abuts against the lower surface of the upper swing rod. The two arms of the torsion spring are respectively blocked by the frame and the lower swing rod. The tension pulley presses down on the lower side section of the chain from above to keep a certain tension on the lower side section of the chain to prevent the chain from loosening and dropping off.

8. The flexible transmission structure of a bicycle according to claims 1 and 3, wherein the spring is a tension spring, and the connection auxiliary member includes: Upper swing rod, tension pulley, limit rod, tension wheel, lower swing rod, torsion spring. One end of the upper swing rod is hinged to the frame, and the other end is connected to the tension pulley. One end of the lower swing rod is also hinged to the frame, and the other end is connected to the tension wheel. It is characterized in that: the tension spring is arranged above the upper swing rod. One end of the tension spring is connected to the upper swing rod, and the other end is connected to the frame. The tension pulley presses against the upper side section of the chain that transmits power between the chainring and the freewheel from below. The lower end of the limit rod is fixed to the frame, and the upper end hooks downward on the upper swing rod. The two arms of the torsion spring are respectively blocked by the frame and the lower swing rod. The torsion spring force makes the tension wheel press against the lower side section of the chain from below, so that the lower side section of the chain maintains a certain tension.

9. The flexible transmission structure of a bicycle according to claims 1 and 4, wherein the spring is a tension spring, and is characterized in that: The connection auxiliary also includes: a force-receiving block, a driven rod, a tension rod. The force-receiving block and the tension rod are fixed on the connecting sleeve, and the driven rod is fixed on the supporting sleeve. The driven rod is arranged at the rear side of the tension rod. When driving the freewheel and the tension rod to rotate on the bicycle, the front side of the tension rod is its front side, and the rear side is its rear side. The force-receiving block is arranged at the rear side of the driven rod. The two ends of the tension spring are connected to the upper parts of the tension rod and the driven rod respectively. The block fixed on the tension rod blocks the driven rod to make the tension spring have a pre-tightening force.

10. The bicycle flexible transmission structure according to claims 1 and 4, wherein the spring is a compression spring, and is characterized in that: The connection auxiliary also includes: a driving rod, a driven rod, a block. The driving rod is fixed on the connecting sleeve, and the driven rod and the block are fixed on the supporting sleeve. The driven rod is arranged at the front side of the driving rod. The two ends of the compression spring are sleeved on the spring seats at the upper parts of the driving rod and the driven rod respectively. The block is arranged at the rear side of the driving rod. The block blocks the driving rod to make the compression spring have a pre-tightening force. A force-receiving block is fixed on the driven rod.

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