JP2020138694A - Transmission mechanism for bicycle - Google Patents

Abstract

To provide a low-cost transmission mechanism for a bicycle, which enables smooth transmission with less resistance during transmission operation.SOLUTION: A follower-side rotary body 3 is rotatably and integrally mounted on a rear wheel of a bicycle 10. The rotary body 3 comprises a drive transmission unit 8 composed of annular non-eccentric transmission parts 5 and eccentric transmission parts 6, and an endless belt 2 is wound around the drive transmission unit 8. On the endless belt 2, multiple engagement claws 2a projecting inwards from the endless belt 2 are formed at equal intervals in a revolving direction. The plurality of non-eccentric transmission parts 5 and the plurality of eccentric transmission parts 6 are disposed one alternate the other along a rotation axis C1. Engagement recesses 3a respectively engageable with the engagement claws 2a are formed at equal intervals in a circumferential direction of an outer peripheral surface. In the non-eccentric transmission parts 5, a center axis 5a thereof coincides with the rotation axis C1. In the eccentric transmission parts 6, a center axis 6a thereof is deviated from the rotation axis C1 such that one of the engagement recesses 3a thereof matches one of the respective engagement recesses 3a of the non-eccentric transmission parts 5 adjacent to a side close to the rear wheel.SELECTED DRAWING: Figure 1

Description

The present invention relates to a transmission mechanism for a bicycle.

Conventionally, for example, the transmission mechanism for a bicycle disclosed in Patent Document 1 includes a multi-stage sprocket that is rotationally and integrally attached to the rear wheel of the bicycle, and the multi-stage sprockets are arranged side by side along the rotation axis. It has a plurality of disc-shaped gears. Each gear has a different outer diameter and is arranged so that it becomes smaller as the distance from the rear wheels increases. A chain is wound around one of the gears, and the orbital movement of the chain is transmitted to the multi-stage sprocket, so that the rear wheels are rotated via the multi-stage sprocket. Below the multi-stage sprocket, a rear derailleur that can move the chain in the direction along the rotation axis is arranged, and by operating the rear derailleur, the gear around which the chain winds is changed to another gear. I try to shift the bicycle.

Japanese Unexamined Patent Publication No. 8-40342

By the way, in the speed change mechanism as described above, since each tooth portion of the gear is inserted between the rollers inside the chain, when shifting the bicycle, the derailleur moves in the direction along the rotation axis while greatly loosening the chain. Need to move. Therefore, there is a problem that the mechanism is complicated, the cost is increased, and a large resistance is added during the shifting operation, so that smooth shifting cannot be performed.

The present invention has been made in view of these points, and an object of the present invention is to provide a low-cost bicycle transmission mechanism capable of smoothly shifting a bicycle with less resistance during shifting operation. To provide.

In order to achieve the above object, the present invention provides an annular portion in which the central axis is eccentric from the center of rotation in a part of a region around which the endless belt is wound in a rotating body that is integrally attached to the rear wheels. It is characterized by having made it.

Specifically, a rotating body having a drive transmitting means which is integrally attached to the rear wheels of a bicycle and set so that the outer diameter becomes smaller as the outer diameter becomes smaller as the distance from the rear wheels increases in the direction along the rotation axis, and the drive. A large number of engaging claws that are wound around the transmission means and project inward are formed at equal intervals in the circumferential direction, and the orbital movement motion is transmitted to the rotating body to transmit the orbiting movement to the rotating body and the rear wheels via the rotating body. A flexible endless belt to be rotated and a belt that shifts the bicycle by moving the endless belt in a direction along the rotation axis and changing the position of the drive transmission means around which the endless belt is wound. The following solutions have been taken in the transmission mechanism for bicycles equipped with the position changing means.

That is, in the first invention, in the drive transmission means, engaging recesses that can be engaged with the engaging claws are formed at equal intervals in the circumferential direction of the outer peripheral surface, and a plurality of engaging recesses are alternately arranged along the rotation axis. An annular non-eccentric transmission unit and an eccentric transmission unit are provided, and the central axis of the non-eccentric transmission unit coincides with the rotation axis, and the eccentric transmission unit engages with each of the eccentric transmission units. The central axis is eccentric from the center of rotation so that one of the recesses coincides with one of the engaging recesses of the non-eccentric transmission portion adjacent to the rear wheel side. ..

In the second invention, in the first invention, the eccentric transmission portion is the eccentric transmission in the non-eccentric transmission portion in which one of the engaging recesses of the eccentric transmission portion is adjacent to the side far from the rear wheel. It is characterized in that it is designed to match one of the engaging recesses located on the side opposite to the eccentric side of the portion.

In the third invention, in the first or second invention, the engaging claw opens at the apex of the engaging claw and extends in the width direction of the endless belt at both ends in the width direction of the endless belt. It is characterized in that a slit that opens to the surface is formed.

In the first invention, when the endless belt is wound around the non-eccentric transmission portion and orbits, when a force is applied to the endless belt in a direction away from the rear wheels by the belt position changing means, the non-eccentric belt is non-eccentric. Since one engaging recess of the transmission section and one engaging recess of the eccentric transmission section match, the engaging recess that matches one of the engaging recesses of the eccentric transmission section in the non-eccentric transmission section. When the endless belt is wound, the endless belt slides toward the eccentric transmission portion without being greatly loosened and is wound around the eccentric transmission portion. On the other hand, when the endless belt is wound around the eccentric transmission portion and is orbiting, when a force is applied to the endless belt in a direction approaching the rear wheels by the belt position changing means, one of the non-eccentric transmission portions. Since the engaging recess and one engaging recess of the eccentric transmission portion are aligned, the endless belt is wound around the engaging recess that matches one of the engaging recesses of the non-eccentric transmission portion in the eccentric transmission portion. When the belt is hung, the endless belt slides toward the non-eccentric transmission portion without being greatly loosened and is wound around the non-eccentric transmission portion. In this way, since the bicycle can be changed without significantly loosening the endless belt, resistance during shifting operation can be reduced, smooth shifting can be performed, and the endless belt can be greatly loosened. There is no need to install it in the derailleur, and a low-cost transmission mechanism can be used.

In the second invention, when the endless belt is wound around the eccentric transmission portion and orbits, when a force is applied to the endless belt in a direction away from the rear wheel by the belt position changing means, the non-eccentric transmission is performed. Since one engaging recess of the portion and one engaging recess of the eccentric transmission portion match, there is no end to the engaging recess that matches one of the engaging recesses of the non-eccentric transmission portion in the eccentric transmission portion. When the belt is wound, the endless belt slides toward the non-eccentric transmission portion without being significantly loosened and is wound around the non-eccentric transmission portion. On the other hand, when the endless belt is wound around the non-eccentric transmission portion and orbits around, when a force is applied to the endless belt in a direction approaching the rear wheels by the belt position changing means, the non-eccentric transmission portion 1 Since one engaging recess and one engaging recess of the eccentric transmission section match, an endless belt is placed in the engaging recess that matches one of the engaging recesses of the eccentric transmission section in the non-eccentric transmission section. When the belt is wound, the endless belt slides toward the eccentric transmission portion without being greatly loosened and is wound around the eccentric transmission portion. In this way, even when the rotating body has three or more transmission portions, the bicycle can be smoothly changed without loosening the endless belt.

In the third invention, the one-side portion and the other-side portion of the engaging claw sandwiching the slit are bent from each other so that they can approach and separate from each other. Therefore, when the endless belt moves between the non-eccentric transmission portion and the eccentric transmission portion, each engaging claw smoothly enters each engaging recess, and the outer surface of each engaging claw is formed on each engaging recess. Since it comes into close contact with the inner surface, it is possible to reliably prevent the endless belt from being accidentally detached from the rotating body.

It is a rear wheel side front view of the bicycle to which the bicycle speed change mechanism which concerns on Embodiment 1 of this invention is applied. It is a front view of the driven side rotating body in the bicycle transmission mechanism which concerns on Embodiment 1 of this invention. FIG. 3 is a view taken along the line III of FIG. 2 showing a partial cross section. It is an IV arrow view of FIG. 2 which showed a partial cross section. It is an enlarged view of V part of FIG. It is sectional drawing in the VI-VI line of FIG. FIG. 4 is a diagram corresponding to FIG. 4 in the second embodiment. It is sectional drawing which shows the internal structure of FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiment is essentially merely an example.
<< Embodiment 1 of the invention >>
FIG. 1 shows around the axle of a rear wheel (not shown) in a bicycle 10 to which the bicycle transmission mechanism 1 according to the first embodiment of the present invention is applied. The speed change mechanism 1 for a bicycle includes a flexible endless belt 2 made of a rubber material and having a rectangular cross section, and a driven side rotating body 3 around which the endless belt 2 is wound and rotationally and integrally attached to a rear wheel. The rear derailleur 4 (belt position changing means) for moving the endless belt 2 wound around the driven side rotating body 3 in the direction along the rotation axis C1 of the driven side rotating body 3 is provided.

As shown in FIGS. 5 and 6, the endless belt 2 includes a large number of engaging claws 2a protruding inward, and the engaging claws 2a are provided at equal intervals in the circumferential direction of the endless belt 2. Has been done.

The protruding side edge of each engaging claw 2a has a convex shape that curves smoothly, while the adjacent engaging claws 2a have a concave shape that curves smoothly, and the inner peripheral surface of the endless belt 2 Has a shape that extends in a wavy shape in the circumferential direction when viewed from the front.

The engaging claw 2a is formed with slits 2b that open at the protruding end of the engaging claw 2a and extend in the width direction of the endless belt 2, and the slits 2b are opened at both ends in the width direction of the endless belt 2. ing.

As shown in FIGS. 2 to 4, the driven-side rotating body 3 includes a drive transmission unit 8 (drive transmission means) obtained by aluminum die casting, and the drive transmission unit 8 gradually contracts as the distance from the rear wheels increases. It has a substantially truncated cone shape with a diameter, and a fixing hole 8A for fixing the freewheel 9 is formed in the center.

The drive transmission unit 8 includes a non-eccentric transmission unit 5 and an eccentric transmission unit 6 that form an annular shape when viewed from the direction along the rotation axis C1, and the endless belt 2 is wound around the non-eccentric transmission unit 5 or the eccentric transmission unit 6. It is supposed to be.

The non-eccentric transmission unit 5 and the eccentric transmission unit 6 have a large number of engaging recesses 3a to which the engaging claws 2a can engage, and the engaging recesses 3a are each of the non-eccentric transmission unit 5 and the eccentric transmission unit 6. They are formed at equal intervals in the circumferential direction of the outer peripheral surface.

Each engaging recess 3a has a concave shape corresponding to the outer shape of the engaging claw 2a, while the adjacent engaging recesses 3a have a convex shape corresponding to the outer shape between the adjacent engaging claws 2a. The outer peripheral surfaces of the non-eccentric transmission unit 5 and the eccentric transmission unit 6 have a shape extending in a wavy shape in the circumferential direction around the central axis thereof.

A plurality of non-eccentric transmission units 5 and eccentric transmission units 6 are alternately arranged along the rotation axis C1 and have different outer diameters, and the outer diameter is the rear wheel in the direction along the rotation axis C1. It is set to become smaller as the distance from is increased. In the case of the first embodiment of the present invention, three non-eccentric transmission units 5 are provided and two eccentric transmission units 6 are provided.

In each non-eccentric transmission unit 5, the central axis 5a coincides with the rotation axis C1.

On the other hand, in each eccentric transmission unit 6, one of the engagement recesses 3a of each eccentric transmission unit 6 (engagement recess 3A in FIG. 2) is adjacent to the non-eccentric transmission unit 5 on the side closer to the rear wheel. The central shaft 6a is eccentric from the rotation axis C1 so as to coincide with one of the engaging recesses 3a (engagement recess 3B in FIG. 2).

Further, each eccentric transmission unit 6 is a non-eccentric transmission unit 5 in which one of the engagement recesses 3a of each eccentric transmission unit 6 (engagement recess 3C in FIG. 2) is adjacent to the side far from the rear wheel. It is designed to coincide with one of the engaging recesses 3a (engagement recess 3D in FIG. 2) located on the side opposite to the eccentric side of the eccentric transmission portion 6.

Then, the endless belt 2 is wound around the non-eccentric transmission unit 5 in the drive transmission unit 8 or the eccentric transmission unit 6, and transmits the orbital movement motion to the driven side rotating body 3 to rotate the driven side. The rear wheels are rotated via the body 3.

The rear derailleur 4 shifts the bicycle by moving the endless belt 2 in the direction along the rotation axis C1 to change the position of the drive transmission unit 8 around which the endless belt 2 is wound. ..

Specifically, when the endless belt 2 is wound around the non-eccentric transmission portion 5 and orbits, when a force is applied to the endless belt 2 by the rear derailleur 4 in a direction away from the rear wheels, it is non-existent. Since the engaging recess 3A of the eccentric transmission portion 5 and the engaging recess 3B of the eccentric transmission portion 6 match, the engaging recess 3A that coincides with the engaging recess 3B of the eccentric transmission portion 6 in the non-eccentric transmission portion 5 When the endless belt 2 is wound, the endless belt 2 slides toward the eccentric transmission unit 6 without being significantly loosened and is wound around the eccentric transmission unit 6. On the other hand, when the endless belt 2 is wound around the eccentric transmission portion 6 and orbits around, when a force is applied to the endless belt 2 by the rear derailleur 4 in a direction approaching the rear wheels, the non-eccentric transmission portion 5 Since the engaging recess 3A of the eccentric transmission portion 6 and the engaging recess 3B of the eccentric transmission portion 6 coincide with each other, the endless belt 2 is formed in the engaging recess 3B corresponding to the engaging recess 3A of the non-eccentric transmission portion 5 in the eccentric transmission portion 6. When the belt is wound around the belt, the endless belt 2 slides toward the non-eccentric transmission unit 5 without being significantly loosened and is wound around the non-eccentric transmission unit 5. In this way, since the bicycle can be changed without significantly loosening the endless belt 2, the resistance at the time of shifting operation is reduced, smooth shifting can be performed, and the endless belt 2 is greatly loosened. It is not necessary to provide the structure in the rear derailleur 4, and a low-cost transmission mechanism can be obtained.

Further, when the endless belt 2 is wound around the eccentric transmission portion 6 and orbits around, when a force is applied to the endless belt 2 by the rear derailleur 4 in a direction away from the rear wheels, the non-eccentric transmission portion 5 Since the engaging recess 3C of the eccentric transmission portion 6 and the engaging recess 3D of the eccentric transmission portion 6 coincide with each other, the endless belt 2 is formed on the engaging recess 3D of the non-eccentric transmission portion 5 of the eccentric transmission portion 6 which coincides with the engaging recess 3C. The endless belt 2 slides toward the non-eccentric transmission unit 5 without being significantly loosened and is wound around the non-eccentric transmission unit 5. On the other hand, when the endless belt 2 is wound around the non-eccentric transmission unit 5 and orbits around, when a force is applied to the endless belt 2 by the rear derailleur 4 in a direction approaching the rear wheels, the non-eccentric transmission unit 2 Since the engaging recess 3C of 5 and the engaging recess 3D of the eccentric transmission portion 6 are aligned with each other, the endless belt is formed in the engaging recess 3C corresponding to the engaging recess 3D of the eccentric transmission portion 6 in the non-eccentric transmission portion 5. When the 2 is wound, the endless belt 2 slides toward the eccentric transmission unit 6 without being significantly loosened and is wound around the eccentric transmission unit 6. In this way, even when the driven side rotating body 3 has three or more non-eccentric transmission units 5 and eccentric transmission units 6 in total, the bicycle can be smoothly changed without significantly loosening the endless belt 2. be able to.

As described above, according to the first embodiment of the present invention, the resistance at the time of shifting operation is reduced, and the bicycle can be smoothly shifted. When the endless belt 2 is wound around the eccentric transmission portion 6, if the endless belt 2 is orbitally moved, the central axis 6a of the eccentric transmission portion 6 is eccentric with respect to the rotation axis C1. The shape belt 2 moves up and down, but the amount of eccentricity of the central shaft 6a is set so as not to cause a problem in running the bicycle.

Further, since the slit 2b is formed in each engaging claw 2a of the endless belt 2, one side portion and the other side portion of the engaging claw 2a sandwiching the slit 2b are bent from each other and can be approached and separated from each other. Therefore, when the endless belt 2 moves between the non-eccentric transmission portion 5 and the eccentric transmission portion 6, each engaging claw 2a smoothly enters each engaging recess 3a and the outer surface of each engaging claw 2a. Is firmly brought into close contact with the inner surface of each engaging recess 3a, so that it is possible to reliably prevent the endless belt 2 from being unexpectedly disengaged from the driven side rotating body 3.

<< 2nd Embodiment of the Invention >>
7 and 8 show the driven side rotating body 3 of the bicycle transmission mechanism 1 according to the second embodiment of the present invention. In the second embodiment, the structure of the endless belt 2 and the driven side rotating body 3 are different from those of the first embodiment, and the other parts are the same as those of the first embodiment. Therefore, only the parts different from the first embodiment are described below. To explain.

The endless belt 2 of the second embodiment has a substantially trapezoidal cross section.

Further, the drive transmission unit 8 of the second embodiment includes a transmission unit main body 8a having a substantially bowl shape obtained by press-molding an aluminum plate, and an annular plate 8b obtained by press-molding an aluminum plate. The annular plate 8b is fixed in the middle of the transmission portion main body 8a so that its central axis coincides with the central axis of the transmission portion main body 8a.

A first mounting hole 8c is formed in the center of the transmission portion main body 8a.

On the other hand, a second mounting hole 8d corresponding to the first mounting hole 8c is formed in the center of the annular plate 8b, and a freewheel 9 is provided in the first mounting hole 8c and the second mounting hole 8d. It is designed to fit.

A tapered surface 7 extending in an annular shape around the central axis is formed between the non-eccentric transmitting portion 5 and the eccentric transmitting portion 6 in the transmitting portion main body 8a of the second embodiment, and the tapered surface 7 is formed on the endless belt 2. It has a shape corresponding to one side surface.

From the above, according to the second embodiment of the present invention, the drive transmission unit 8 having less resistance at the time of shifting operation can be obtained by press molding.

In the first and second embodiments of the present invention, the drive transmission unit 8 has three non-eccentric transmission units 5 and two eccentric transmission units 6, but the present invention is not limited to this. The configuration may include four 5 and three eccentric transmission units 6, or the non-eccentric transmission unit 5 and the eccentric transmission unit 6 may each have other numbers.

The present invention is suitable for a bicycle transmission mechanism.

1 Bicycle transmission mechanism 2 Endless belt 2a Engagement claw 2b Slit 3 Driven side rotating body 3a Engagement recess 4 Rear derailleur (belt position changing means)
5 Non-eccentric transmission part 5a Central axis 6 Eccentric transmission part 6a Central axis 8 Drive transmission part (drive transmission means)
10 Bicycle C1 Rotation axis

Claims (3)

A rotating body having a drive transmission means that is integrally attached to the rear wheel of the bicycle and is set so that the outer diameter decreases as the distance from the rear wheel increases in the direction along the rotation axis.
A large number of engaging claws that are wound around the drive transmission means and project inward are formed at equal intervals in the circumferential direction, and the orbital movement motion is transmitted to the rotating body and after that through the rotating body. A flexible endless belt that rotates the ring,
A bicycle speed changer including a belt position changing means for shifting the bicycle by moving the endless belt in a direction along the rotation axis and changing the position of the drive transmission means around which the endless belt is wound. It ’s a mechanism,
In the drive transmission means, annular non-eccentric transmissions in which engagement recesses that can be engaged with the engagement claws are formed at equal intervals in the circumferential direction of the outer peripheral surface and a plurality of engagement recesses are alternately arranged along the rotation axis. Equipped with a part and an eccentric transmission part
The central axis of the non-eccentric transmission unit coincides with the rotation axis.
The central axis of the eccentric transmission portion is such that one of the engaging recesses of the eccentric transmission portion coincides with one of the engaging recesses of the non-eccentric transmission portion adjacent to the side closer to the rear wheel. Is eccentric from the center of rotation of the bicycle. In the bicycle transmission mechanism according to claim 1,
In the eccentric transmission portion, one of the engaging recesses of the eccentric transmission portion is located on the side opposite to the eccentric side of the eccentric transmission portion in the non-eccentric transmission portion adjacent to the side far from the rear wheel. A bicycle shifting mechanism designed to match one of the engaging recesses. In the bicycle transmission mechanism according to claim 1 or 2.
The bicycle is characterized in that the engaging claw is formed with slits that open at the apex of the engaging claw and extend in the width direction of the endless belt and open at both ends in the width direction of the endless belt. Speed change mechanism.