JPH0224714B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a bicycle rear derailleur,
More specifically, the present invention relates to a rear derailleur for a bicycle that can have a much larger gear capacity than conventional rear derailleurs.

Some bicycles have a derailleur,
Select one of the different diameter sprockets of the multi-stage freewheel, use a combination of multiple different diameter sprockets as a chain wheel, select one of these different diameter sprockets, and replace the chain. Some vehicles are equipped with both a front derailleur and a front derailleur (hereinafter referred to as a front derailleur). In such a bicycle, it is possible to perform fine-grained gear shifting operations with a number of gears multiplied by the number of sprockets in the multi-stage freewheel multiplied by the number of sprockets in the crank gear.

As mentioned above, on a bicycle equipped with a derailleur that changes speed by replacing the chain with a sprocket of a different diameter, the amount of slack in the chain when it is hanging on a large-diameter sprocket and when it is hanging on a small-diameter sprocket is different. Although a difference occurs, this slack is absorbed by elastically biasing the tension roller of the rear derailleur in the direction of applying tension to the chain. The gear capacity of the rear derailleur is the number of sprocket teeth that indicates how many links the rear derailleur can absorb the slack of the chain as described above, and is usually the same as the teeth of the smallest diameter sprocket compared to the largest diameter sprocket in a multi-stage freewheel. The number of teeth is calculated by adding the number difference and the difference in the number of teeth between the largest diameter sprocket and the smallest diameter sprocket in the multi-stage chain wheel. Therefore, a rear derailleur that includes both a rear derailleur and a front derailleur is required to have a larger gear capacity.

By the way, so-called mountain bikes, such as the one shown in Figure 1 of this application, which have recently become popular, have multi-stage freewheels that allow them to climb steep slopes with relatively little pedal effort. By increasing the maximum diameter of the sprocket,
In addition, there is a tendency to make the minimum diameter sprockets of multi-stage chain wheels smaller and smaller. Therefore, a rear derailleur to be attached to such a bicycle is required to have a gear capacity far greater than that of a conventional rear derailleur. One way to increase the gear capacity of the rear derailleur is to extend the length of the so-called tensioner guard and lower the position of the tension roller, but this has been considered primarily for off-road driving. On a mountain bike like the one mentioned above, if the guard is extended too much, the guard may hit rocks or bumps on the road surface, damaging the rear derailleur. It may also make the rear derailleur look unsightly, and it may affect the rigidity of the rear derailleur's support to the body frame. Various problems arise, such as the need for consideration.

The present invention was conceived under the above circumstances, and its object is to provide a rear derailleur that can significantly increase gear capacity without significantly increasing the overall appearance.

In order to achieve such an object, the bicycle rear derailleur of the present invention employs the following configuration.

That is, the present invention provides a bicycle rear derailleur configured to move a tensioner that supports a guide roller and a tension roller vertically apart from each other in the direction of the hub axis or in a direction slightly inclined with respect to the hub axis. At least one auxiliary tension roller is provided in a portion of the tensioner closer to the tension roller than the guide roller, and the center of the guide roller, the center of the tension roller, and the center of the auxiliary tension roller are each polygonal. configured to form a vertex, and
It is characterized in that the chain is attached to the rear part of the multi-stage freewheel of the bicycle via the rear part of the tension roller and the auxiliary tension roller or the front part of the guide roller.

By doing so, the following effects occur.

That is, in the rear derailleur of the present invention, the chain connected to the tensioner passes through at least three rollers: a tension roller, an auxiliary tension roller, and a guide roller. This is because in the past, the chain could only be supported by a tensioner with a length corresponding to the distance between the guide roller and the tension roller, whereas in the present invention, for example, one auxiliary tension roller is provided. For example, this means that the tensioner can support a chain corresponding to the distance between the guide roller and the auxiliary tension roller plus the distance between the auxiliary tension roller and the tension roller, and as a result,
The gear capacity of the rear derailleur increases approximately by the distance between the auxiliary tension roller and the tension roller.

Preferred embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is an external view of a mountain bike to which the rear derailleur of the present invention is most suitable.
As is clear from the figure, this bicycle has thick tires 3 mounted on a sturdy frame 2 with the crankshaft 1 set higher than usual so that it can ride on uneven terrain without any trouble. It is equipped with both rear derailleur 4 and front derailleur 5. In addition, the outer diameter of the minimum diameter sprocket of the chain wheel 6 is quite small, so if the number of teeth of the maximum diameter sprocket of the multistage freewheel 7 is 34T, the number of teeth of the minimum diameter sprocket is 13T, and the number of teeth of the multistage freewheel 7 is 13T. Assuming that the number of teeth on the largest diameter sprocket of No.6 is 52T and the number of teeth on the smallest diameter sprocket is 28T, the rear derailleur 4 installed on this bicycle has (34-13) + (52-
28) = 45T gear capacity is required. The maximum gear capacity of typical rear derailleurs currently on the market is 37T, so conventional rear derailleurs like this cannot be used with the above bicycles.

The details of an example of the rear derailleur 4 of the present invention are shown in FIG. 2 and below.

The basic configuration of the rear derailleur 4 of the present invention is as follows:
The structure adopted in the conventional rear derailleur may be used as is. That is, the guide roller 8
Tensioner 1 equipped with and tension roller 9
0 may be configured to be movable parallel to the hub axis or diagonally with respect to the hub axis using a so-called pantograph link mechanism 11. This is explained in detail as follows.

The pantograph link mechanism 11 is attached to the rear end plate 12 of the bicycle frame 2 by screws 13.
The bases of a pair of ring plates 15 and 16 arranged laterally with respect to the base member 14 attached to the base member 14 are rotatably supported, and a movable member 17 is mounted at the tips of the pair of link plates 15 and 16. It is configured to be rotatably mounted. The above base member 1
4, the pair of ring plates 15 and 16, and the movable member 17 cooperate to form a deformable parallelogram. Therefore, when this parallelogram is deformed, the movable member 17 is attached to the base member 14. In contrast, it moves almost parallel to the hub axis direction. Although not shown, one of the four pins 18 for rotatably connecting the base member 14, the pair of link plates 15, 16, and the movable member 17 to each other is provided with a pantograph link. A spring is inserted in the sleeve to elastically deform the mechanism 11 in one direction. In addition, this pantograph link mechanism 11
As shown in FIG. 4, the operating cable W is attached so that the diagonal length of the parallelogram is forcibly shortened against the elasticity of the spring.
It is operated by towing with a gear shift control lever attached to the handlebar or appropriate part of the frame.

Movable member 1 of the pantograph link mechanism 11
7 is attached with a tensioner 10 that moves in the hub axis direction to replace the chain CH on one of the sprockets 22 of the multi-stage freewheel 7 and to remove slack from the chain CH. As clearly shown in FIGS. 2 and 3, the tensioner 10 in the examples shown in FIGS. A guide roller 8 is rotatably supported at the tip of the arm 20 via a guide roller 8, and a guard 23 is attached to the support shaft 21 of the guide roller 8.
Basically, the tension roller 9 is rotatably supported at the lower part of the tension roller 9. The arm 20 is urged in the direction of arrow A in FIG. 2 by a spring 25 built into a spring box 24 attached to the movable member 17, and
3 is moved by arrow B in FIG.
It is urged to rotate in the direction. By doing so, the tensioner 10 as a whole is always given a tendency to rotate clockwise in FIG. 2 approximately around the axis 19, and this tendency eliminates slack in the chain Chien
A predetermined tension is applied to CH.

Furthermore, in this example, a support arm 26 is extended from the middle part of the guard 23, and this support arm 26 is
An auxiliary tension roller 27 is rotatably supported at the tip of the tensioner 6, and the tensioner 10 supports a total of three rollers, the guide roller 8, the tension roller 9, and the auxiliary tension roller 27. Note that these three rollers 8, 9, 27
The mutual relationship between the centers of the respective rollers O1,
What is necessary is for O2 and O3 to form a triangle. In order to provide the above-mentioned auxiliary tension roller 27, as shown in the illustrated example, the guard 23 of the conventional rear derailleur must be
An arm 26 for supporting the auxiliary tension roller is attached to the middle part of the auxiliary tension roller 2.
In addition to mounting the auxiliary tension roller 7, the guard is formed into an integral form, such as an arm for the auxiliary tension roller and an arm for the tension roller, and the auxiliary tension is attached to each of the branched parts. The roller 27 and the tension roller 9 may be attached. Although not shown, if the support arm 26 or the auxiliary tension roller 27 is configured to be detachably attached to the guard 23 using, for example, screws, the rear derailleur can be attached to the gear capacity as needed. This is convenient because a large state and a small state can be selected. Note that the above-mentioned auxiliary tension roller 27 only assists the function of the tension roller 9, so when this rear derailleur is installed on the bicycle, the chain
The CH is routed around the rear of the tension roller 9 and the auxiliary tension roller 27 or the front of the guide roller 8 in a substantially inverted S-shape, and is routed around the rear of one sprocket 22 of the multi-stage freewheel 7.

Furthermore, as a guard for tensioner 10,
In addition to the special types shown in Figures 2 to 5, it is of course possible to adopt a so-called pendulum type, a balance type, or a triangular balance type as shown in Figure 6.

Next, the operation of the rear derailleur of the present invention will be explained with reference to FIGS. 2 and 5.

Figure 2 shows a state when the chain CH is applied to the smallest diameter sprocket of both the multistage chain wheel 6 and the multistage freewheel 7, that is, the state where the most slack in the chain CH is removed. There is. In this diagram,
Considering that the chain path indicated by the symbol CH' is a case in which chain slack is removed to the maximum extent possible with a conventional rear derailleur, the amount of chain slack that can be removed with the rear derailleur of the present invention is significantly increased. That should be obvious. That is, in the conventional rear derailleur, the tensioner can only support a chain with a length corresponding to approximately the distance between the guide roller and the tension roller, whereas in the rear derailleur of the present invention, the chain between the center O1 of the guide roller and the auxiliary tension roller can be supported by the tensioner. As a result of the center O2 of the tension roller and the center O3 of the tension roller working together to form the apex of the triangle, the distance between the guide roller 8 and the auxiliary tension roller 9 and the distance between the auxiliary tension roller 27 and the tension roller are approximately the same. A chain having a length corresponding to the sum of the distance of the tension roller 9 can be supported by the tensioner, and the upper length of the derailleur as a whole is not extended.

On the other hand, FIG. 5 shows a state in which the chain is replaced with the large diameter sprocket of the multistage freewheel 7 or the chain is replaced with the large diameter sprocket of the multistage chain wheel 6 in the example shown in FIG.
In other words, it shows the state when the amount of slack in the chain CH to be removed is small. In this case, the arm 20 of the tensioner 10 rotates a predetermined amount counterclockwise in the figure about the shaft 19, and the guard 23 rotates a predetermined amount counterclockwise in the figure about the shaft 21. In this case, although the tension roller 9 has already left the chain CH, the auxiliary tension roller 27 will play the role of the original tension roller.
There is no problem with the function of the derailleur.

It goes without saying that the above-mentioned effect is exactly the same in the example shown in FIG.

As explained above, the bicycle rear derailleur of the present invention has a derailleur that has the same vertical size as a conventional rear derailleur, but a derailleur that is incomparably larger than a conventional rear derailleur, for example, 45T.
It exhibits a special effect of being able to provide a gear capacity of more than 100%. As a result, the rear derailleur of the present invention is optimal as a rear derailleur for mountain bikes, which requires a large gear capacity. In addition, one auxiliary tensioner is installed so that it has the same vertical length as the previous rear derailleur with the largest gear capacity, that is, the one with the guard length extended to have a gear capacity of 40T. As a result of creating and experimenting with the rear derailleur of the present invention with additional rollers, we found that the gear capacity was
It has been found that it is possible to achieve 50T or more.

It goes without saying that the scope of the present invention is not limited to the above-mentioned embodiments, and that two or more auxiliary tension rollers are used, and the centers of the guide roller, tension roller, and auxiliary tension roller each correspond to a vertex of a rectangle. It may also be formed. Also,
As a mechanism for moving the tensioner in the hub axis direction, in addition to adopting a parallelogram pantograph link mechanism as shown in the example, a slide rod is inserted through a slide block attached to a fixed member, and the tensioner is attached to this slide rod. A sliding mechanism such as the one described above may also be adopted. Further, the object to which the rear derailleur of the present invention can be attached is not limited to mountain bikes, but can of course be used in place of a conventional rear derailleur on a normal bicycle with a transmission.

[Brief explanation of drawings]

The drawings show embodiments of the present invention; FIG. 1 is an overall view of an example of a bicycle to which the rear derailleur of the present invention is preferably installed; FIG. 2 is a front view of a rear derailleur according to an embodiment of the present invention; and FIG. FIG. 4 is a view taken in the direction of the arrow in FIG. 2, FIG. 5 is an explanatory view of the operation of the rear derailleur shown in FIG. 2, and FIG. 6 is a rear derailleur according to another embodiment of the present invention. FIG. 4...Rear derailleur, 8...Guide roller, 9...
Tension roller, 10...Tensioner, 27...
Auxiliary tension roller, O1... (guide roller) center, O2... (auxiliary tension roller) center, O3... (tension roller) center.

Claims (1)

[Claims] 1. In a bicycle rear derailleur configured to be able to move a tensioner that supports a guide roller and a tension roller vertically apart from each other in the direction of a hub axis or in a direction slightly inclined with respect to the hub axis, the guide roller of the tensioner At least one auxiliary tension roller is provided in a region closer to the tension roller, so that the center of the guide roller, the center of the tension roller, and the center of the auxiliary tension roller each form a vertex of a polygon. A rear derailleur for a bicycle, characterized in that the chain is connected to the rear of the multi-stage freewheel of the bicycle via the rear of the tension roller and the auxiliary tension roller or the front of the guide roller. .