TW202102400A - Bicycle transmission mechanism for providing non-circular motion trajectory - Google Patents

Abstract

The present invention discloses a bicycle transmission mechanism which comprises a chainring and a crank, wherein the outer edge of the chainring has a tooth portion. The crank connected to the chainring for driving thereof, and the motion trajectory of the chainring is non-circular. Each position of the crank rotation process can respectively make the tooth portion correspondingly form an equivalent treading teeth number, and the corresponding relationship between the of the equivalent treading teeth number and the crank rotation angle has only one peak and one valley value. The peak value represents the maximum of the equivalent tread tooth number, and the valley value represents the minimum of the equivalent tread tooth number. The invention can reduce the variation frequency of the rotation of the chainring, improve the stability, and provide a relatively gentle pedaling effect.

Description

Bicycle transmission mechanism providing non-circular motion track

The invention relates to the technical field of a bicycle transmission mechanism, in particular to a bicycle transmission mechanism that provides a non-circular motion track.

Generally, a bicycle is driven by the rotation of a rear wheel. The rotation of the rear wheel is achieved by a transmission mechanism. The transmission mechanism includes a combination of a front chainring and a pair of cranks, and a chain connecting the front chainring and a rear chainring group, and the rear chainring group combining a Rear wheel hub. When the user applies a stepping force on the pair of cranks, the crank drives the front chainring and the chain to rotate, and the chain drives the rear chainring assembly to rotate the rear wheel hub and the rear wheel.

The front toothed disc is mostly a circular disc and the crank is installed at the center of the disc. In this way, the rotation of the front sprocket can make the trajectory of the outer edge circular. It is worth noting that because the movement track of the outer edge of the front chainring is circular, the change in the position of the crank during the rotation of the front chainring will not cause the pedaling power to change.

In addition, there is a design that uses an elliptical chainring to drive the chain. The elliptical toothed disk can provide greater pedaling power, but the elliptical toothed disk has large fluctuations in the stepping process, which is prone to discomfort.

The purpose of the present invention is to provide a bicycle transmission mechanism with a non-circular motion track, which has a low frequency of fluctuations in the rotation of the chainring and high stability and high mobility, thereby providing a relatively gentle pedaling effect.

In order to achieve the above-mentioned objectives and effects, the transmission mechanism disclosed in the present invention includes a sprocket and a crank, wherein the outer edge of the sprocket has a tooth part; a crank is connected to the sprocket to drive the sprocket to rotate and make the tooth The movement trajectory of the disc is a non-circular movement trajectory; wherein each position of the crank rotation process can make the tooth corresponding to form an equivalent pedaling tooth number, and the corresponding relationship between each equivalent pedaling tooth number and the crank rotation angle is only There is a peak value and a valley value, the peak value represents the maximum value of the equivalent pedaling teeth, and the valley value represents the minimum value of the equivalent pedaling teeth.

In accordance with the objectives and effects of the present invention, a preferred embodiment is listed below, and the components and combinations of the present embodiment are described in detail in conjunction with the drawings.

Please refer to FIG. 1, which shows a transmission mechanism 10 of a bicycle. The transmission mechanism 10 includes a chainring 20 and a combination of two cranks 30 and 40. According to common knowledge, the outer edge of the chainring 20 is provided with a tooth portion 22 for coupling with a chain 24, and the two cranks 30 and 40 are coupled to the chainring 20, one of which is the crank 30 The crank 40 is used for pedaling with the right foot of the rider, and the other crank 40 is used for pedaling with the left foot of the rider. The rotation of the cranks 30 and 40 can drive the gear plate 20 to rotate.

Please refer to FIG. 2, when the toothed disk 20 rotates according to the embodiment of the present invention, the rotation track of the tooth 22 on the outer edge of the toothed disk 20 forms a non-circular track. In order to enable the outer edge of the toothed disc 20 to provide a non-circular movement track, the toothed disc 20 may have a rotation center 25, and the outer edge of the toothed disc 20 has a long axis 26 and a short axis corresponding to the rotation center 25. The axis 28, and the long axis 26 and the short axis 28 are on the same straight line.

Referring to Figures 3 and 4, the sprocket 20 of the present embodiment can be circular, which means that the outer edge of the sprocket 20 is circular, and the center 50 of the sprocket 20 is a distance from the center of rotation 25. The amount of displacement 52. One end of the crank 30 (take the right crank as an example) is installed at the rotation center 25, and the angle between the crank 30 and the long shaft 26 is between 80 degrees and 120 degrees. In this way, the ring gear 20 is driven by the crank 30 to rotate, and the outer edge movement track of the ring gear 20 is a non-circular track.

Since the outer edge of the non-circular motion track of the toothed disc disclosed in the present invention and the known elliptical toothed disc rotate in a non-original position (non-circular motion track) during the rotation process, the tooth disc and the elliptical During the rotation of the gear plate driven by the crank, each position of the crank can make the teeth corresponding to form an equivalent number of pedaling teeth.

Please refer to the following table. Take a chainring with 32 teeth on the outer edge as an example. Under the installation condition where the crank and the long axis are installed at an angle of 80 degrees, the outer edge of the chainring disclosed in the present invention is 80 degrees when the crank rotates 80 degrees from the starting position. The maximum equivalent number of pedaling teeth is 33.81 teeth; when the crank rotates 260 degrees from the starting position, the outer edge forms the minimum equivalent number of pedaling teeth 30.19 teeth; when the elliptical gear plate rotates 80 degrees and 260 degrees from the starting position, Its outer edge forms the maximum equivalent number of pedaling teeth of 33.81 teeth; when the crank rotates 170 degrees and 350 degrees from the starting position, its outer edge forms the minimum equivalent number of pedaling teeth of 30.00 teeth.

Under the installation condition where the angle between the crank and the long axis is 120 degrees, when the crank rotates 120 degrees from the starting position of the gear plate disclosed in the present invention, the outer edge forms the largest equivalent number of pedaling teeth of 33.81 teeth; at the starting position of the crank When rotating 300 degrees, its outer edge forms the minimum equivalent number of pedaling teeth 30.19 teeth; when the crank rotates 110 degrees, 290 degrees from the starting position, its outer edge forms the maximum equivalent number of pedaling teeth 33.81 teeth; When the starting position is rotated by 20 degrees or 200 degrees, its outer edge will form a minimum equivalent number of pedaling teeth of 30.00 teeth. Crank angle The crank-long axis included angle of the present invention is 80 degrees The crank-long axis included angle of the present invention is 120 degrees Elliptical chain crank-the major axis angle is 80 degrees Ellipse chain crank-the major axis angle is 120 degrees Perfect circle 0 32.27 31.06 30.10 30.38 32 10 32.58 31.34 30.38 30.10 32 20 32.87 31.64 30.84 30.00 32 30 33.13 31.95 31.42 30.10 32 40 33.37 32.27 32.07 30.38 32 50 33.56 32.58 32.73 30.84 32 60 33.70 32.87 33.29 31.42 32 70 33.78 33.13 33.68 32.07 32 80 33.81 33.37 33.81 32.73 32 90 33.78 33.56 33.68 33.29 32 100 33.70 33.70 33.29 33.68 32 110 33.56 33.78 32.73 33.81 32 120 33.37 33.81 32.07 33.68 32 130 33.13 33.78 31.42 33.29 32 140 32.87 33.70 30.84 32.73 32 150 32.58 33.56 30.38 32.07 32 160 32.27 33.37 30.10 31.42 32 170 31.95 33.13 30.00 30.84 32 180 31.64 32.87 30.10 30.38 32 190 31.34 32.58 30.38 30.10 32 200 31.06 32.27 30.84 30.00 32 210 30.81 31.95 31.42 30.10 32 220 30.59 31.64 32.07 30.38 32 230 30.42 31.34 32.73 30.84 32 240 30.29 31.06 33.29 31.42 32 250 30.21 30.81 33.68 32.07 32 260 30.19 30.59 33.81 32.73 32 270 30.21 30.42 33.68 33.29 32 280 30.29 30.29 33.29 33.68 32 290 30.42 30.21 32.73 33.81 32 300 30.59 30.19 32.07 33.68 32 310 30.81 30.21 31.42 33.29 32 320 31.06 30.29 30.84 32.73 32 330 31.34 30.42 30.38 32.07 32 340 31.64 30.59 30.10 31.42 32 350 31.95 30.81 30.00 30.84 32 360 32.27 31.06 30.10 30.38 32

It is worth noting that the toothed disc and the elliptical toothed disc disclosed in the present invention can form different equivalent pedaling teeth when the crank rotates to different positions; however, the tooth disc disclosed in the present invention rotates in a 360-degree process. Only one maximum equivalent pedaling tooth number and one minimum equivalent pedaling tooth number appear; on the other hand, an elliptical gear disc with non-circular motion trajectory is also provided. During a 360-degree rotation, there will be a second maximum equivalent pedaling tooth number and a second minimum, etc. Number of effective pedaling teeth.

Please refer to Figures 5 and 6, because the value of the number of teeth determines the position of the outer edge of the chainring, the interaction between the crank and the number of teeth, such as the product of the two, can constitute the power of the positional tooth number. According to the results disclosed in the above table and graphically represented, it can be clearly seen that in the same pedaling process at the angle between the crank and the major axis of 80 degrees and 120 degrees, the chain disc disclosed in this embodiment and the elliptical chain disc are produced The maximum position tooth number power and the minimum position tooth number power are quite the same; however, the sprocket disclosed in this embodiment only produces a maximum position tooth number function and a minimum position tooth number function. The elliptical sprocket produces a second maximum position tooth number function and a second The minimum number of teeth work; is the process of rotating 360 degrees of the gear disc disclosed in this embodiment from the graph, the outer edge position of the gear disc only produces a peak to valley change, while the elliptical gear disc produces a secondary peak In other words, under the condition of generating the power of the number of teeth at the same position, the rotation frequency of the gear disc disclosed in this embodiment is low, the stability is high, and the pedaling effect is relatively gentle.

Please refer to Figure 7, another embodiment of the present invention is that the outer edge (tooth) of the toothed disk 60 is non-circular. For example, the outer edge of the toothed disk 60 is a convex circle, so that the crank 30 is installed If the position corresponds to the center 62 of the gear plate 60, the crank 30 can drive the gear plate 60 to rotate, and the gear plate 60 has a long shaft 64 and a short shaft 66. The long shaft 64 and the short shaft 66 are in the same straight line. And through the center 62. In this way, the movement track of the chainring 60 is non-circular.

The above-mentioned embodiments are merely illustrative of the technology and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with this technology can modify and change the above-mentioned embodiments without violating the technical principle and spirit of the present invention. Therefore, the scope of protection of the rights of the present invention should be listed in the scope of patent application described later. .

10: Transmission mechanism 20: Sprocket 22: Teeth 24: Chain 25: Center of rotation 26: Long axis 28: short shaft 30: crank 40: crank 50: center of circle 52: displacement 60: chainring 62: center 64: long axis 66: short axis

Figure 1 is an external view of the combination of the present invention. Figure 2 is a schematic diagram of the motion trajectory of the present invention. Figure 3 is the first schematic diagram of the position where the crank of the present invention is installed on the chainring. Figure 4 is the second schematic diagram of the position where the crank of the present invention is installed on the chainring. Figure 5 is a diagram showing the number of teeth and power of the present invention, the elliptical toothed disc and the positive disc at an angle of 80 degrees between the crank and the major axis. Figure 6 is a diagram showing the number of teeth and power of the present invention, the elliptical toothed disc and the positive disc when the angle between the crank and the major axis is 120 degrees. Figure 7 is a schematic diagram of the structure of another chainring of the present invention.

20: chainring

25: Center of rotation

26: long axis

28: short axis

Claims (5)

A bicycle transmission mechanism that provides a non-circular motion track, which includes: A toothed disk with a tooth on its outer edge; A crank connected to the gear plate to drive the gear plate to rotate and make the movement track of the gear plate into a non-circular movement track; Wherein each position of the crank rotation process can make the tooth corresponding to form an equivalent number of pedaling teeth, and the corresponding relationship between each equivalent number of pedaling teeth and the crank rotation angle has only a peak value and a valley value, and the peak value represents The maximum value of the equivalent number of pedaling teeth, and the valley value represents the minimum value of the equivalent number of pedaling teeth. The bicycle transmission mechanism that provides non-circular motion trajectory as described in item 1 of the scope of patent application, wherein the chainring has a rotation center, and there is a long axis and a short axis from the rotation center to the outer edge of the chainring, and The long axis and the short axis are on the same straight line. For example, the bicycle transmission mechanism that provides a non-circular motion track as described in item 2 of the scope of patent application, wherein the crank corresponds to the twelve o'clock direction, the angle between the crank and the long axis is between 80 degrees and 120 degrees. The bicycle transmission mechanism that provides a non-circular motion track as described in the first item of the scope of patent application, wherein the tooth portion of the outer edge of the chainring is circular, and the installation position of the crank has a displacement relative to the center of the chainring . As described in the first item of the scope of patent application, the bicycle transmission mechanism that provides a non-circular motion track, wherein the tooth portion of the outer edge of the chainring is non-circular, and the installation position of the crank is correspondingly located in the center of the chainring.

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