Rear derailleur with quadrilateral linkage

Abstract

The utility model discloses a rear derailleur with quadrilateral linkage mechanism, including quadrilateral linkage mechanism and setting on the guide chain wheel of quadrilateral linkage mechanism, be equipped with the mounting axis on the quadrilateral linkage mechanism, the mounting axis is the reference axis of quadrilateral linkage mechanism and bicycle frame connection, the quadrilateral linkage mechanism's four rotating pairs respectively correspond to a pivot axis, the included angle between the mounting axis and the pivot axis on the quadrilateral linkage mechanism is beta, wherein, 80 degree <= beta <= 90 degree, the quadrilateral linkage mechanism is non parallelogram linkage mechanism. This rear derailleur can gradually adjust its attitude when carrying out chain driving, thereby reducing the fitting angle when the guide chain wheel and the chain cooperate, reducing the resistance of riding, improve the use experience, and the rear derailleur greatly reduces or eliminates the component force of gravity on the mounting axis when riding in extreme road conditions, effectively reduces the automatic speed change condition of rear derailleur.

Description

Technical Field

[0001] This utility model relates to a bicycle speed control device, specifically to a rear derailleur with a quadrilateral linkage mechanism. Background Technology

[0002] In bicycles, the main function of the rear derailleur is to drive the chain to switch between different sprockets on the freewheel, thereby changing the bicycle's gear ratio and achieving shifting. See also Figure 1 and Figure 2 During riding, the pedals drive the crank, which in turn drives the chainring 8, which in turn drives the freewheel 7 via the chain, thus transmitting power to the bicycle. The freewheel 7 has sprockets of varying diameters, arranged sequentially according to diameter to facilitate shifting gears. The optimal chain drive configuration is when the rear derailleur's chain guide pulley 4 is on the chain centerline, meaning the chain is positioned on the sprocket corresponding to the chain centerline. When the chain is on other sprockets (not corresponding to the chain centerline), there is an angle θ between the chain and the chain centerline. This angle θ is largest when the chain is on the smallest or largest sprocket. During shifting, the rear derailleur's chain guide pulley 4 moves to the corresponding sprocket position.

[0003] See Figure 2 Existing rear derailleurs are usually parallel four-bar linkages. When driving the chain, they do not gradually adjust their own posture. That is, the posture of the sprocket 4 does not gradually adjust. When the sprocket 4 and the chain are engaged, there is a engagement angle b. When the chain is on the smallest or largest tooth, the engagement angle is the largest. This will increase the resistance and wear of riding, resulting in a very poor user experience.

[0004] See Figure 3 The existing rear derailleur is attached to the bicycle frame along the mounting axis S2. The rear derailleur uses a parallel four-bar linkage, with the pivot axis S3 of the linkage being the line connecting the rotation centers of the four rotating joints. Existing rear derailleurs are typically of an angled push structure, meaning the mounting axis S2 of the rear derailleur is not perpendicular to the pivot axis S3 of the parallel four-bar linkage; for example, the included angle is 42°. During extreme riding conditions, the weight F of the rear derailleur... 重 A component force F will be generated on the mounting axis. 水平 This causes the rear derailleur to automatically shift gears. Utility Model Content

[0005] The purpose of this invention is to overcome the aforementioned problems and provide a rear derailleur with a quadrilateral linkage mechanism. This rear derailleur can gradually adjust its own posture when the chain is driven, thereby reducing the engagement angle between the chain guide wheel and the chain, reducing riding resistance, and improving the user experience. Moreover, when riding in extreme road conditions, the rear derailleur greatly reduces or eliminates the component force of gravity generated on the mounting axis, effectively reducing the occurrence of automatic shifting of the rear derailleur.

[0006] The objective of this utility model is achieved through the following technical solution: A rear derailleur with a quadrilateral linkage mechanism includes a quadrilateral linkage mechanism and a guide sprocket disposed on the quadrilateral linkage mechanism. The quadrilateral linkage mechanism has a mounting axis, which is the reference axis connecting the quadrilateral linkage mechanism to the bicycle frame. Each of the four rotating joints of the quadrilateral linkage mechanism corresponds to a pivot axis. The angle between the mounting axis and the pivot axis on the quadrilateral linkage mechanism is β, where 80°≤β≤90°. The quadrilateral linkage mechanism is a non-parallelogram linkage mechanism.

[0007] The working principle of the rear derailleur with the quadrilateral linkage mechanism described above is as follows: During operation, the rider moves the shifters on the bicycle handlebars, which in turn drive the quadrilateral linkage mechanism via the chainring, causing the sprocket to move and thus the chain to move, thereby adjusting the gears of the rear derailleur. The angle between the mounting axis and the pivot axis on the quadrilateral linkage mechanism is 80°≤β≤90°. In extreme road conditions, the rear derailleur significantly reduces or eliminates the component of gravity on the mounting axis, effectively reducing the likelihood of automatic shifting. Because the quadrilateral linkage mechanism is a non-parallel quadrilateral linkage mechanism, it will tilt during the swing process. That is, the quadrilateral linkage mechanism does not move in a parallel posture, but rather with an angle of inclination. This causes the sprocket to also move with an angle of inclination, meaning the sprocket's posture also wobbles. At this time, the axis of the sprocket is not parallel to the axis of the sprocket teeth. When the quadrilateral linkage shifts from the gear corresponding to the chain centerline to the highest gear (chain switches to the smallest sprocket), the sprocket moves closer to the chain's tilted position. This drives the sprocket to deflect towards the chain's tilted position, reducing the engagement angle between the sprocket and the chain. This results in smoother chain operation, reduced riding resistance, less wear, and an improved user experience. Similarly, when the quadrilateral linkage shifts from the gear corresponding to the chain centerline to the lowest gear (chain switches to the largest sprocket), the sprocket deflects towards the chain's tilted position (the chain's tilt is opposite to its tilt in the highest gear), further reducing the engagement angle between the sprocket and the chain.

[0008] In a preferred embodiment of this invention, the angle between the mounting axis and the pivot axis on the quadrilateral linkage mechanism is 90°. In this structure, under extreme riding conditions (e.g., a 2-meter drop), the force generated by the weight of the rear derailleur will not have a component force in the direction of the mounting axis (horizontal direction). Therefore, it will not automatically shift gears without shifting the shifters. Conversely, if the mounting axis is not perpendicular to the pivot axis on the quadrilateral linkage mechanism, and the force generated by the weight of the rear derailleur in the direction of the mounting axis (horizontal direction) is greater than the force required to drive the derailleur, the rear derailleur will automatically shift gears.

[0009] Preferably, the quadrilateral linkage mechanism includes a base component, a movable component, a first link, and a second link. Both the first and second links are connected between the base component and the movable component via revolute joints. The base component is attached to the bicycle frame along the mounting axis. The sprocket is mounted on the movable component. In this structure, the quadrilateral linkage mechanism has four revolute joints and is a non-parallelogram linkage mechanism, meaning the quadrilateral formed by the four revolute joints is not a parallelogram. During gear shifting, the movable component moves relative to the base component, thereby driving the sprocket to move, which in turn moves the chain, achieving gear switching.

[0010] Preferably, the system further includes a chain guide plate and a tensioning wheel. The chain guide plate is rotatably connected to the movable component, and both the tensioning wheel and the chain guide plate are mounted on the chain guide plate. The tensioning wheel can tension the chain after gear shifting. During gear shifting, the chain guide plate, chain guide plate, and tensioning wheel move together with the movable component.

[0011] Compared with the prior art, the present invention has the following advantages: 1. In this utility model, the angle between the mounting axis and the pivot axis on the quadrilateral linkage mechanism of the rear derailleur is 80°≤β≤90°. When riding in extreme road conditions, the rear derailleur greatly reduces or eliminates the component force of gravity generated on the mounting axis, effectively reducing the automatic shifting of the rear derailleur.

[0012] 2. The rear derailleur in this utility model has a non-parallelogram linkage mechanism, which allows the rear derailleur to gradually adjust its posture when the chain is driven, thereby reducing the engagement angle between the chain guide wheel and the chain, reducing riding resistance, and improving the user experience. Attached Figure Description

[0013] Figure 1 This is a simplified diagram of the derailleur principle in existing technology.

[0014] Figure 2 This is a simplified diagram of the engagement between the guide sprocket and the chain in the prior art.

[0015] Figure 3 This is a force analysis diagram of a rear derailleur in the prior art.

[0016] Figure 4 This is a schematic diagram of the force analysis structure of a rear derailleur with a quadrilateral linkage mechanism according to the present invention.

[0017] Figure 5 This is a simplified diagram illustrating the working principle of the rear derailleur in different gear positions.

[0018] Figure 6 This is a simplified diagram illustrating the working principle of the rear derailleur in this invention at the gear position corresponding to the chain centerline.

[0019] Figure 7 This is a simplified diagram illustrating the working principle of the rear derailleur in the highest gear position of this utility model.

[0020] Figure 8 This is a simplified diagram illustrating the working principle of the rear derailleur in the lowest gear position of this utility model. Detailed Implementation

[0021] To enable those skilled in the art to fully understand the technical solution of this utility model, the present utility model will be further described below in conjunction with the embodiments and accompanying drawings, but the implementation of this utility model is not limited thereto.

[0022] See Figures 2-4 This embodiment discloses a rear derailleur with a quadrilateral linkage mechanism, including a quadrilateral linkage mechanism 1 and a guide wheel 4 disposed on the quadrilateral linkage mechanism 1. The quadrilateral linkage mechanism 1 is provided with a mounting axis S2, which is the reference axis connecting the quadrilateral linkage mechanism 1 to the bicycle frame. Each of the four rotating joints of the quadrilateral linkage mechanism 1 corresponds to a pivot axis S3. The included angle between the mounting axis S2 and the pivot axis S3 on the quadrilateral linkage mechanism 1 is β, wherein 80°≤β≤90°. The quadrilateral linkage mechanism 1 is a non-parallelogram linkage mechanism.

[0023] See Figures 2-4 The working principle of the aforementioned rear derailleur with a quadrilateral linkage mechanism is as follows: During operation, the rider moves the shifter on the bicycle handlebars, which drives the quadrilateral linkage mechanism 1 to swing via the chain cord, causing the guide wheel 4 to move, thereby moving the chain and adjusting the gears of the rear derailleur. The angle between the mounting axis S2 and the pivot axis S3 on the quadrilateral linkage mechanism 1 is 80°≤β≤90°. When riding in extreme road conditions, the rear derailleur greatly reduces or eliminates the component force of gravity generated on the mounting axis S2, effectively reducing the automatic shifting of the rear derailleur. Since the quadrilateral linkage mechanism 1 is a non-parallel quadrilateral linkage mechanism, it will deflect during the swing. That is, the quadrilateral linkage mechanism 1 does not move in a parallel posture, but moves with an angle of inclination, causing the guide wheel 4 to also move with an angle of inclination. In other words, the posture of the guide wheel 4 also deflects. At this time, the axis of the guide wheel 4 is not parallel to the axis of the sprocket 7. When the quadrilateral linkage 1 shifts from the gear corresponding to the chain centerline to the highest gear (the chain switches to the smallest sprocket), the sprocket 4 will move closer to the inclined position of the chain. This drives the sprocket 4 to deflect towards the inclined position of the chain, reducing the engagement angle b between the sprocket 4 and the chain. This allows the chain to drive more smoothly, reducing riding resistance, minimizing wear, and improving the user experience. Similarly, when the quadrilateral linkage 1 shifts from the gear corresponding to the chain centerline to the lowest gear (the chain switches to the largest sprocket), the sprocket 4 deflects towards the inclined position of the chain (the chain's tilt is opposite to its tilt in the highest gear), further reducing the engagement angle b between the sprocket 4 and the chain.

[0024] See Figure 5 When the sprocket 4 is positioned at the chain centerline, that is, when the chain is located on the tooth corresponding to the chain centerline, it represents the optimal posture for chain drive, with the chain centerline parallel to the bicycle's central reference plane. In this embodiment, there are 12 teeth. Counting from smallest to largest, the fifth tooth corresponds to the chain centerline. At this point, the chain centerline, the fifth tooth centerline, and the chainring centerline are all located in the same vertical plane.

[0025] See Figure 3 and Figure 4 The angle between the mounting axis S2 and the pivot axis S3 on the quadrilateral linkage mechanism 1 is 90°, meaning that the mounting axis S2 and the pivot axis S3 on the quadrilateral linkage mechanism 1 are perpendicular to each other. In the above structure, under extreme riding conditions (e.g., a 2-meter drop), the force generated by the weight of the rear derailleur will not have a component force in the direction of the mounting axis S2 (horizontal direction). Therefore, it will not automatically shift gears without shifting the shifters. Conversely, if the mounting axis S2 and the pivot axis S3 on the quadrilateral linkage mechanism 1 are not perpendicular, the force F generated by the weight of the rear derailleur will... 重 A component force F is generated in the direction of the installation axis S2 (horizontal).水平 When the force exceeds the force required to drive the rear derailleur, the rear derailleur will automatically shift gears (also known as ghost shifting).

[0026] See Figures 4-8 The quadrilateral linkage mechanism 1 includes a base component 1-1, a movable component 1-2, a first link 1-3, and a second link 1-4. Both the first link 1-3 and the second link 1-4 are connected between the base component 1-1 and the movable component 1-2 via revolute joints. The base component 1-1 is attached to the bicycle frame along the mounting axis S2. The sprocket 4 is mounted on the movable component 1-2. In this structure, the quadrilateral linkage mechanism 1 has four revolute joints and is a non-parallelogram linkage mechanism, meaning the quadrilateral formed by the connection of the four revolute joints is not a parallelogram. During gear shifting, the movable component 1-2 moves relative to the base component 1-1, thereby driving the sprocket 4 to move, which in turn moves the chain, achieving gear shifting. Because the quadrilateral is not a parallelogram, the first link 1-3 and the second link 1-4 swing, causing the movable component 1-2 to swing. Since the movable component 1-2 is connected to the first link 1-3 and the second link 1-4, in addition to moving, the movable component 1-2's own posture gradually deviates, causing the guide wheel 4 to also move with a tilt angle. That is, the posture of the guide wheel 4 also deviates, and at this time, the axis of the guide wheel 4 is not parallel to the axis of the sprocket of the freewheel 7. When the first link 1-3 changes from the gear corresponding to the chain centerline to the highest gear (the chain switches to the smallest sprocket) along with the second link 1-4, the guide wheel 4 will move closer to the tilted posture of the chain, thereby driving the guide wheel 4 to deviate towards the tilted posture of the chain, reducing the engagement angle b when the guide wheel 4 and the chain are engaged, making the chain drive more smoothly, reducing riding resistance, reducing wear, and improving the user experience. Similarly, when the first link 1-3 changes from the gear corresponding to the chain centerline to the lowest gear (the chain switches to the largest toothed gear) along with the second link 1-4, the guide sprocket 4 deflects towards the inclined posture of the chain (at this time, the inclined posture of the chain is opposite to that at the highest gear), reducing the engagement angle b between the guide sprocket 4 and the chain.

[0027] The rotating joint is a hinge, and the base component 1-1 is provided with mounting screws for mounting the base component 1-1 on the bicycle frame. The axis of the mounting screw is the mounting axis S2.

[0028] See Figures 4-8 It also includes a chain guide plate 5 and a tensioning wheel 6. The chain guide plate 5 is rotatably connected to the movable component 1-2, and the tensioning wheel 6 and the chain guide wheel 4 are both mounted on the chain guide plate 5. The tensioning wheel 6 can tension the chain after shifting gears. During the shifting process, the chain guide plate 5, the chain guide wheel 4, and the tensioning wheel 6 move together with the movable component 1-2.

[0029] The above are preferred embodiments of the present utility model, but the embodiments of the present utility model are not limited to the above content. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present utility model shall be considered equivalent substitutions and shall be included within the protection scope of the present utility model.

Claims

1. A rear derailleur with a quadrilateral linkage mechanism, characterized in that, The device includes a quadrilateral linkage mechanism and a guide sprocket mounted on the quadrilateral linkage mechanism. The quadrilateral linkage mechanism has a mounting axis, which is the reference axis connecting the quadrilateral linkage mechanism to the bicycle frame. Each of the four rotating joints of the quadrilateral linkage mechanism corresponds to a pivot axis. The angle between the mounting axis and the pivot axis on the quadrilateral linkage mechanism is β, where 80°≤β≤90°. The quadrilateral linkage mechanism is a non-parallelogram linkage mechanism.

2. The rear derailleur according to claim 1, characterized in that, The angle between the mounting axis and the pivot axis on the quadrilateral linkage is 90°.

3. The rear derailleur according to claim 1, characterized in that, The quadrilateral linkage mechanism includes a base component, a movable component, a first link, and a second link. The first link and the second link are both connected between the base component and the movable component via a revolute joint. The base component is attached to the bicycle frame along the mounting axis. The sprocket is disposed on the movable component.

4. The rear derailleur according to claim 3, characterized in that, It also includes a guide plate and a tensioning wheel, the guide plate being rotatably connected to the movable component, and both the tensioning wheel and the guide wheel being mounted on the guide plate.

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