JPH0820376A - Speed change mechanism for bicycle - Google Patents

Abstract

PURPOSE:To surely prevent a chain from being removed from a guide pulley by forming a guide wall on a moving member constituting a pantograph mechanism, and forming extension sections preventing the removal of the chain from the guide pulley in cooperation with the guide wall on a chain guide. CONSTITUTION:A link base 8 is provided with inner and outer link members 9, 10 pivotally supported at the base end sections, and a moving member 11 is rockably connected to their tips to constitute a pantograph link mechanism 12. A chain guide 15 pivotally supporting a guide pulley 13 and a tension pulley 14 is supported between the inner and outer guide plates 16, 17 to be elastically excited in the tension applying direction to a chain C against the moving member. The moving member 11 is formed with a guide wall 28 facing the outer periphery of the guide pulley 13 to the outside in the radial direction, and the inner and outer guide plates 16, 17 are formed with extension sections 29a, 29b extended to face the side face of the chain C and preventing the removal of the chain C in cooperation with the guide wall 28.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bicycle speed change mechanism.

[0002]

2. Description of the Related Art For example, a rear derailleur as a speed change mechanism for a bicycle is provided with a chain guide that rotatably supports a guide pulley and a tension pulley, and this chain guide is attached to a bicycle frame by a so-called parallelogram. It is rotatably supported while being biased in a direction to give tension to the chain via a shift link mechanism such as a pantograph link mechanism. By operating a shift operation lever connected to the shift link mechanism via an operation cable, the shift link mechanism is deformed and the chain guide supported by the movable member of the shift link mechanism moves in the hub axial direction. And is configured to be translated into the desired sprocket of the multi-stage sprocket. The chain guide is supported by the movable member of the shift link mechanism so as to be swingable around an upper portion thereof, and its lower portion is elastically biased so as to rotate rearward. ing. The chain is hung around the tension pulley of the chain guide and the guide pulley in that order.
After the guide pulley is disengaged, the multi-stage sprocket can be run by hanging on one sprocket.

When the chain guide is moved in the axial direction of the hub, the guide pulley is also moved in the axial direction of the hub, and the chain before the guide pulley is hung on the multi-stage sprocket is displaced in the vehicle width direction. The chain can be replaced with the sprocket next to the sprocket that was previously hanging.

When the chain is hooked on sprockets having different diameters, the required effective length of the chain changes, but this is because the lower part of the chain guide is elastically rotated rearward. It is automatically adjusted depending on the situation. That is, the tension pulley is moved in the front-rear direction of the vehicle body by the rotation of the chain guide, so that the slack of the chain is removed and an appropriate tension is always applied to the chain.

[0005]

By the way, when the chain is changed over to the sprockets having different diameters as described above,
The chain is pressed in the vehicle width direction by the guide pulley and is slanted with respect to the plane of rotation of the guide pulley. Therefore, a large force in the vehicle width direction acts on the chain that is wound around the guide pulley, and the chain easily separates from the outer peripheral portion of the guide pulley. However, an appropriate tension is applied to the chain by the tension pulley, and the chain that is about to be separated from the guide pulley can be held on the guide pulley.

However, when the gear shift operation lever device is suddenly operated, or when some impact is applied to the chain and the tension of the chain given by the tension pulley is suddenly reduced, the chain is wound around the guide pulley. The force of the chain to move away from the guide pulley may overcome the tension of the chain and the chain may come off the guide pulley. Further, if the transmission is operated from the low speed running side to the high speed running side while the movement of the gear crank is stopped, that is, the pedal is not rotated, and then the pedal is rotated in the opposite direction to the driving direction, In the transmission, there was a problem that the chain came off the guide pulley. When the chain is disengaged from the guide pulley, not only can the bicycle not be run, but the disengaged chain may collide with the vehicle body frame or the like and cause damage.

The present invention has been devised under the above circumstances, and solves the above-mentioned problems of the prior art, and performs a sudden gear shift operation or a case where the tension of the chain is drastically reduced. Also in the above, it is an object of the invention to provide a bicycle speed change mechanism capable of effectively preventing the chain from coming off from the guide pulley.

[0008]

Means for Solving the Problems To solve the above problems, the present invention takes the following technical means. That is, the invention described in claim 1 of the present application is a link base attached to a bicycle frame, an inner link member and an outer link member swingably connected to the link base at their base ends, and tips of these link members. The pantograph link mechanism is configured by a movable member swingably connected to the inner guide plate and the outer guide plate, and a chain guide that rotatably supports a guide pulley and a tension pulley is provided between the guide plates. A bicycle speed change mechanism, which is rotatably supported about an axis parallel to the hub axis while elastically urging the movable member of the mechanism in a direction of applying tension to the chain,
A guide wall is formed on the movable member so as to face the outer peripheral portion of the guide pulley in a radially outward direction, while one or both of the inner guide plate and the outer guide plate are hung on the guide pulley. It is characterized in that an extension portion is formed that extends toward the side surface of the turned chain and cooperates with the guide wall to prevent the chain from being separated from the guide pulley.

The invention described in claim 2 of the present application is
In front of the multi-stage sprocket supported around the hub axle, a link base supported by the chain stay, an inner link member and an outer link member that are swingably supported at the base end of the link base, and extend rearward, and these. A pantograph link mechanism is configured by a movable member swingably connected to the tip of the link member, and an inner guide plate and an outer guide plate are provided, and a chain guide that rotatably supports a guide pulley and a tension pulley is provided between these guide plates. A movable member of the bicycle, wherein the movable member of the pantograph link mechanism is rotatably supported around an axis parallel to the hub axis while elastically urging the movable member in a direction to apply tension to the chain. Has
A guide wall is formed radially opposite to the outer peripheral portion of the guide pulley, and one or both of the inner guide plate and the outer guide plate has a side surface of a chain wound around the guide pulley. And an extension portion that extends in opposition to and that cooperates with the guide wall to prevent the chain from being separated from the guide pulley.

[0010]

In the bicycle speed change mechanism according to the present invention, the movable member constituting the pantograph link mechanism is formed with the guide wall facing the outer peripheral portion of the guide pulley in the radial direction, while the chain is formed. One or both of the inner and outer guide plates that make up the guide,
An extension portion is formed that extends toward the side surface of the chain that is wound around the guide pulley and that cooperates with the guide wall to prevent the chain from being separated from the guide pulley.

That is, in the speed change mechanism according to the present invention, the chain is allowed to travel in the space surrounded by the outer peripheral portion of the guide pulley, the guide wall, and the extension portion. Therefore, even if the chain floats from the outer peripheral portion of the guide pulley due to a sudden gear change operation or a sharp decrease in the tension of the chain, the chain is brought into contact with the guide wall or the extension portion, and thus the outer peripheral portion of the guide pulley is also contacted. Pushed back.

Further, since the chain can travel in the space surrounded by the guide wall and the extension, the transmission is operated from the low speed running side to the high speed running side with the gear crank stopped, and then the chain. Even when the gear is reversed, the chain does not come off from the guide pulley as in the conventional transmission mechanism. Therefore, in the speed change mechanism according to the present invention, the chain can be prevented from coming off the guide pulley in all traveling situations. As a result, the traveling safety of the bicycle is significantly improved. Furthermore, it is possible to cope with a sudden gear shift operation, and even when the road surface condition changes abruptly, a quick and reliable gear shift operation can be performed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments according to the present invention will be described below with reference to FIG.
It will be specifically described with reference to FIG. As shown in FIG. 1, in the rear part of the bicycle, a hub axle 4 that rotatably supports the multi-stage sprocket 2 and the hub 3 is supported by a rear end plate 6 of a bicycle frame 5 as in the conventional example. The rear transmission 1 to which the invention of the present application is applied is provided in front of the hub shaft 4 or the multi-stage sprocket 2, and is supported by a link base 8 which is supported at a lower middle portion of a chain stay 7 extending from the rear end plate 6 to the front of the vehicle body. An inner link member 9 and an outer link member 10 which are swingably connected to the link base 8 at their proximal ends and extend rearward, and swingably connected to the tips of the inner and outer link members 9, 10. The member 11 constitutes a pantograph link mechanism 12, and a chain guide 15 that rotatably supports the guide pulley 13 and the tension pulley 14 on the movable member 11 of the pantograph link mechanism 12 is elastic in a direction to apply tension to the chain C. While being biased, it is rotatably supported about an axis parallel to the hub shaft 4.

The chain guide 15 according to this embodiment is shown in FIG.
As shown in FIG. 3, an inner guide plate 16 and an outer guide plate 17 that are located inward in the vehicle width direction are provided, and the guide shafts 16 and 17 are rotated by rotating shafts 18 and 19 to guide the guides. The guide pulley 13 and the tension pulley 14 are rotatably supported between the plates,
The pantograph link mechanism 12 is swingably supported around the upper portion of the movable member 11 and its lower portion is elastically biased by a spring (not shown) so as to rotate rearward. There is. Chiang C
The tension pulley 14 and the guide pulley 13 of the chain guide 15 are wound around in this order, and after the guide pulley 13 is disengaged, the multi-stage sprocket 2 travels so as to hang on one sprocket.

In this embodiment, as shown in FIG.
An end portion of the outer cable t2 of the speed change operation cable T, which is composed of an inner cable t1 and an outer cable t2 inserted into the inner cable t1, is fixed to an appropriate portion of a frame (not shown), and extends from the outer cable t2. The inner cable t1 is connected to an operation wire connecting mechanism 20 provided above a connecting portion connecting the inner link member 9 and the link base 8. Then, the inner wire t1 connected to the operation wire connecting mechanism 20 is pulled by a gear shift lever device (not shown) provided on a handlebar or the like, so that the pantograph link mechanism 1 is operated.
2 is deformed and gear shifting is performed.

In the pantograph link mechanism 12 of this embodiment, as shown in FIG. 4, the outer peripheral surface 21 of which the radial distance changes is provided at the end of the inner link member 9 on the link base 8 side.
The outer link member 10 is actuated by providing a cam follower 22 that comes into contact with the cam surface of the speed change cam 21 while the speed change cam 21 having a is provided. The cam follower 22 uses the spring 22b to move the cam surface 21a.
Is configured to elastically abut. On the other hand, the cam 21 is elastically biased by a spring (not shown) so that the movable member 11 is located at the outer position in the vehicle width direction.

The operation wire connection mechanism 20 and the speed change cam 21 are rotatably supported above the connection pin 31 so as to be integrally rotated by pulling the inner wire t1. Then, by pulling the inner wire t1, the speed change cam 21 is rotated, and the change of the contact position between the speed change cam 21 and the cam follower 22 causes the inner and outer link members 9 and 10 to swing in the vehicle width direction. To shift gears. In addition, in this embodiment,
As shown in FIG. 1, the link base 8 is a bracket 23 joined to an appropriate portion of the chain stay 7 by welding.
Is installed through.

The cable connecting mechanism 20 according to the present embodiment.
As shown in FIG. 3, after winding the end portion of the inner cable t1 around the reel portion 25 formed on the outer periphery of the rotating member 24, the inner cable t1 is attached to the attaching means 26 provided on the outer peripheral portion of the rotating member 24. In addition, the remaining cable t3 extending from the fastening means 26 can be held in a state of being wound around the rotation axis on the upper surface of the rotating member 24.

The cable connecting mechanism 20 and the shift cam 21 are constructed so as to be integrally rotated by pulling the inner cable t1, and by pulling the shift operating cable t1, The speed change cam 21 is rotated, and the pantograph link mechanism 12 is deformed in the vehicle width direction by a change in the contact position between the speed change cam 21 and the cam follower 22.

When the movable member 11 is moved in the vehicle width direction by the pulling operation of the inner cable t1, the chain guide 15 is also moved in the hub axis direction. Then, the guide pulley 13 laterally presses the chain C before being hooked on one sprocket of the multi-stage sprocket 2, and thereby the chain C is hung on the sprocket next to the sprocket that has been hanging up to that time. When the chain C is sprocketed with a different diameter, the required effective length of the chain C changes, but this is configured so that the lower part of the chain guide 15 elastically rotates rearward. Is automatically adjusted. That is, the tension pulley 14 that first supports the chain introduced into the chain guide 15 is moved in the front-rear direction by the rotation of the chain guide 15, so that the slack of the chain C is removed.
Moreover, appropriate tension is always applied to the chain C.

In the transmission mechanism according to this embodiment, as shown in FIGS. 2 and 3, in front of the chain guide support portion 27 of the movable member 11, a radius relative to the outer peripheral portion of the guide pulley 13 is provided. A guide wall 28 is formed to face the outside in the direction. Further, as well shown in FIG. 2, the inner guide plate 16 and the outer guide plate 17 constituting the chain guide 15 are extended so as to face the left and right side surfaces of the chain wound around the guide pulley. The extending portions 29a and 29b are formed so as to extend. The edges of the extension portions 29a and 29b are formed so as to be positioned close to the guide wall 28 in a normal traveling state, that is, a state shown by a solid line in FIG.

Therefore, as shown in FIG. 3, the chain C, which is wound around the guide pulley 13, is located behind the pantograph link mechanism 12 in the outer peripheral portion of the guide pulley 13, the guide wall 28, and the inside and outside. It is made to travel in a space 30 surrounded by extension portions 29a and 29b formed on the guide plates 16 and 17.

Therefore, even if a large force is applied to the chain C in the vehicle width direction due to a sudden gear change operation, or the chain C is lifted from the outer peripheral portion of the guide pulley 13 due to a sharp decrease in tension of the chain C. , Abuts on the guide wall 28 or the extension portions 29a, 29b and is pushed back to the outer peripheral portion of the guide pulley 13. Further, since the chain C can travel in the space 30 surrounded by the guide wall 28 and the extension portions 29a and 29b, the transmission is operated from the low speed running side to the high speed running side with the gear crank stopped. After that, even when the chain is rotated in the reverse direction, the chain C does not come off from the guide pulley 13 unlike the conventional transmission mechanism.

Therefore, in the speed change mechanism according to the present embodiment, the chain C is not likely to come off the guide pulley 13 during traveling. Therefore, driving safety is significantly improved. Further, since it becomes possible to cope with a sudden gear shift operation, it becomes possible to perform a rapid gear shift operation when the road surface condition changes suddenly. Moreover, in the present embodiment, as shown by the phantom line in FIG. 2, when the chain guide 15 is rotated rearward of the vehicle body, the end edge of the extension portion 29a of the inner guide plate 16 causes the guide wall to move. 28
Away from the guide wall 28 and the inner guide plate 16
The gap between the extended portion 29a and the extended portion 29a formed on the upper side is widened, and the chain C can be easily removed from the guide pulley 13.
Therefore, the attachability of the chain C does not deteriorate.

The scope of the present invention is not limited to the above embodiments. In the embodiment, the present invention is applied to the bicycle transmission mechanism supported by the chain stay in front of the multi-stage sprocket, but it is also applicable to a normal transmission mechanism attached to the rear end plate 6 as described in the conventional example. it can.

Further, in the embodiment, the inner link member 9
The pantograph link mechanism 12 is configured to be deformed inward and outward in the vehicle width by the speed change cam 21 provided at the end of the link base and the cam follower 22 abutting against the speed change cam 21. It can also be applied to a speed change mechanism having a link mechanism.

Also, in the embodiment, the inner guide plate 16
Although the extension portions 29a and 29b are provided on both the outer guide plate and the outer guide plate, the extension portion may be formed on only one of the guide plates 16 and 17.

Further, in the embodiment, the operation cable connecting mechanism 20 is provided on the upper portion of the speed change cam 21 so that one end of the operation cable is held by the operation cable connecting mechanism 20, but the link member forming the pantograph link mechanism 12 is described. The present invention can also be applied to a speed change mechanism having a normal pantograph link mechanism that connects a cable end to a part of the.

Furthermore, in the embodiment, the present invention is applied to the speed change mechanism 1 having the pendulum type chain guide 15. However, other speed change mechanism having a chain guide such as a speed change mechanism having a so-called triangular balance type chain guide is used. It is also possible to apply the present invention to the mechanism.

[Brief description of drawings]

FIG. 1 is a side view of a speed change mechanism according to the present invention.

FIG. 2 is a rear view of the transmission mechanism according to FIG.

FIG. 3 is a plan view of the transmission mechanism according to FIG.

FIG. 4 is an explanatory diagram illustrating an operation of the pantograph link mechanism according to the present embodiment.

[Explanation of symbols]

 1 transmission mechanism 4 hub axle 7 chain stay 8 link base 9 inner link member 10 outer link member 11 movable member 12 pantograph link mechanism 13 guide pulley 14 tension pulley 15 chain guide 16 inner guide plate 17 outer guide plate 28 guide walls 29a, 29b extension Part C Chain

Claims (2)

[Claims] 1. A link base attached to a bicycle frame, an inner link member and an outer link member swingably connected to the link base at a base end, and swingably connected to tips of the link members. A pantograph link mechanism is constituted by a movable member, an inner guide plate and an outer guide plate are provided, and a chain guide that rotatably supports a guide pulley and a tension pulley is provided between these guide plates with respect to the movable member of the pantograph link mechanism. , A bicycle speed change mechanism supported rotatably around an axis parallel to the hub axis while elastically urging the chain in a direction to apply tension to the chain, wherein the movable member is attached to the outer peripheral portion of the guide pulley. One of the inner guide plate and the outer guide plate or On both sides, an extension portion is formed, which extends so as to face the side surface of the chain wound around the guide pulley and cooperates with the guide wall to prevent the chain from being separated from the guide pulley. A characteristic gearbox for bicycles. 2. A link base supported by a chain stay in front of a multi-stage sprocket supported around a hub axle, an inner link member swingably connected to the link base at a base end thereof, and extending rearward, and an outer member. A link member and a movable member swingably connected to the ends of these link members constitute a pantograph link mechanism, which includes an inner guide plate and an outer guide plate, and a guide pulley and a tension pulley can be rotated between these guide plates. A bicycle speed change mechanism in which a supporting chain guide is rotatably supported around the axis parallel to the hub axis while elastically biasing the chain guide in the direction of applying tension to the movable member of the pantograph link mechanism. In the above-mentioned movable member, While the wall is formed, one or both of the inner guide plate and the outer guide plate extend opposite to the side surface of the chain that is wound around the guide pulley, and cooperate with the guide wall to form the wall. A bicycle speed change mechanism, wherein an extension portion is formed to prevent the chain from being separated from the guide pulley.