JPH0140793Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

This invention relates to a bicycle rear derailleur for changing the chain to a selected sprocket of a multi-stage freewheel attached to the rear wheel of the bicycle.

[Prior art and its problems]

A rear derailleur for a bicycle rotates a guide pulley located above and a tension pulley located below between a pair of inner and outer guard plates facing each other at a predetermined distance from a movable member of a control mechanism such as a pantograph link mechanism. A so-called tensioner is rotatably supported while elastically biased in one direction with respect to a support shaft parallel to the wheels of the rear wheel. By moving the tensioner, which has a chain around the guide pulley and tension pulley, in the axle direction near the multi-stage freewheel, the chain can be replaced with a desired sprocket. By the way, the control mechanism is equipped with a stopper mechanism for regulating the movement range of the movable member, and by adjusting this stopper mechanism, the tensioner is prevented from moving excessively in the left-right direction. A multi-stage freewheel has two to seven sprockets of different diameters arranged in parallel, and the range of movement of the tensioner in the left and right direction is regulated by the stopper mechanism according to the total width of the sprockets of different diameters. This is how it has become. If the range of movement of the tensioner is incorrectly adjusted, for example, the tensioner may move too far toward the large-diameter sprocket of the multi-stage freewheel, causing the tensioner to jump between the spokes of the rotating wheel, which is extremely dangerous. Furthermore, when the vehicle falls over to the right, the rear derailleur itself contacts the ground and bends from its attachment point to the vehicle body toward the wheel, which may cause part of the tensioner to become caught in the spokes of the wheel. Usually, there is a gap or step between the pulley and the guard plate that supports it, so the spokes tend to get stuck or get caught in this gap or step. When the spoke gets caught in the tensioner,
The tensioner itself is pulled by the tensioned chain and cannot move backwards, so the spokes will break or the tensioner will be destroyed. Especially if a spoke breaks,
It is easy to imagine that this is extremely dangerous for passengers. Several methods have already been proposed that take measures to prevent the tensioner from catching or jumping into the spokes of the wheel as described above. In addition to the dust cover normally provided in this area, a pulley cap is provided in the gap between the pulley and the guard plate, and the peripheral edge of the pulley cap is extended to the vicinity of the teeth of the pulley, and the side edge of the guard plate is is configured to be continuous with the above pulley cap. By doing this, when the tensioner approaches the wheel side, the area where the spokes come into contact will be a smooth slope,
Any gaps or steps where the spokes might get caught are eliminated. However, with conventional means such as those mentioned above,
A pulley cap is added as a component of the pulley, which increases the number of parts and has the disadvantage that assembly workability becomes worse.

[Purpose of invention]

The present invention was devised under the above circumstances, and its purpose is to provide a means for preventing the tensioner from catching or jumping into the spokes of the wheel when the tensioner moves excessively. The purpose is to reduce the number of parts without increasing the number of parts, and at the same time to improve the workability of assembling the tensioner.

[Means to achieve the purpose]

In order to achieve the above object, the bicycle rear derailleur of the present invention employs the following means. That is, a tensioner is provided in which an outer guard plate and an inner guard plate are opposed to each other with a predetermined interval, and a guide pulley and a tension pulley are rotatably supported between them, and the tensioner is moved in a predetermined direction to tighten the chain. In a bicycle rear derailleur which can be replaced with a desired sprocket of a multi-stage freewheel, a dust cover part in the form of an inward annular projection that fits into an annular groove formed on the side surface of the pulley is integrally formed on the inner surface of the guard plate, and
The outer surface of the inner guard plate is provided with an inclined surface that bulges out toward the rear from the front edge of the dust cover section. In the case of a tension pulley support part, this inclined surface is provided at the front part of the outer surface of the inner guard plate, that is, at the part where the spokes collide if the tensioner moves too far toward the wheel.

[Functions and effects of the idea]

Since the bicycle rear derailleur of the present invention is constructed as described above, it exhibits the following functions and effects. That is, firstly, a disc was conventionally formed separately from the guard plate and interposed between the pulley and the guard plate so that its peripheral edge fit into an annular groove formed on the side surface of the pulley. A dust cover with a similar dust-proofing function is integrally formed on the inner surface of the inner guard plate, which eliminates the need for a dust cover.As a result, the number of parts for the tensioner is reduced, which is advantageous in terms of cost. Easy to assemble. Secondly, since the dust cover part in the form of an inward annular protrusion integrally formed on the inner surface of the inner guard plate is fitted into the annular groove on the side surface of the pulley, a part of the inner guard plate is attached to the side surface of the pulley. When the tensioner is viewed from the front, there is no gap between the pulley and the inner guard plate where the spokes could get caught. There is therefore no risk of the spokes getting caught even if the tensioner is over-traveled towards the wheel. Furthermore, the outer surface of the inner guard plate is provided with an inclined surface that swells toward the rear from the front edge of the dust cover, so even if the spokes of a rotating wheel collide with the front of the inner surface of the tensioner. However, since the inclined surface bounces the spokes, it is possible to effectively prevent the tensioner from jumping between the spokes. In this way, the present invention reduces the number of parts, simplifies assembly, and is unique in that it can effectively prevent the tensioner from getting caught on the spokes or jumping between the spokes when the tensioner moves excessively. It has the effect of

[Explanation of Examples]

Embodiments of the present invention will be specifically described below with reference to the drawings. Fig. 1 is a view of a bicycle rear derailleur 1 to which the present invention is applied, viewed from the wheel side, Fig. 2 is a view taken in the direction of Fig. 1, and Fig. 3 is an enlarged sectional view taken along the - line in Fig. 1. , FIG. 4 is an enlarged sectional view taken along the - line in FIG. 1, and FIG. 5 is an enlarged sectional view taken along the - line in FIG. 1. A pair of link members 4 are attached to the base member 3, which is attached to the rear end plate P of the bicycle frame, directly with bolts 2 or indirectly with a bracket (not shown), and which are swingable in the lateral direction. A movable member 5 is swingably connected to the link member 4 to form a parallelogram pantograph link mechanism 6. By deforming this pantograph link mechanism 6, the movable member 5 becomes movable in the direction of the rear axle X of the bicycle with a certain directionality.
When the movable member 5 moves in this manner, a chain C, which is attached to the movable member 5 and is wrapped around a tensioner 8 (to be described later), is replaced with a selected sprocket of the multi-stage freewheel.
The speed change operation by moving the movable member 5 is
One end of the control cable (not shown) is connected to the pantograph link mechanism, and the other end of the control cable (not shown) is connected to the pantograph link mechanism. The movable member 5 is provided with a tensioner 8 that is swingable and has a tendency to rotate in the direction of arrow A in FIG. However, it is supported. The tensioner 8 includes an outer guard plate 9, an inner guard plate 10 facing the outer guard plate 9 at a fixed interval, and a guide pulley 11 rotatably supported at the upper and lower portions between the inner and outer guard plates 9 and 10. and a tension pulley 12. The guide pulley 11 plays the role of swinging the chain C, which is separated from it and hooked onto the multi-stage freewheel, in the direction of the axle and replacing it with a desired sprocket, and the tension pulley 12 is always operated in the direction of the arrow A in FIG. Since the chain C has a tendency to rotate elastically, it serves to eliminate slack that occurs when the chain C is replaced with sprockets of various diameters. These pulleys 1
1 and 12, in this example, as shown in FIGS. 3 and 4, the male threaded end portion 13a of the bolt 13 inserted from the outer guard plate 9 side is connected to the female thread 14 made by opening it in the inner guard plate 10. By screwing the outer guard plate 9 and the inner guard plate 10 together so as to face each other, the center hole 16 of the pulleys 11 and 12 can be rotated through the intermediate shaft portion 13b of the bolt 13 via the bush 15. I'm wearing a cloak. In addition, in order to prevent dirt and dust from entering the sliding portion between the outer periphery of the bushing 15 and the center hole 16 and increasing the rotational resistance of the pulley,
An annular groove 17 is formed on the side surfaces of the pulleys 11 and 12, and a disk-shaped dust cover 18 is fitted into the annular groove 17 with a peripheral edge bent inward.
is interposed between the pulley and the guard plate, but in the bicycle rear derailleur 1 of the present invention,
As is clear from the figure, the dust cover 18 is interposed only between the outer guard plate 9 and the pulleys 11, 12, and the dust cover 18 is interposed only between the outer guard plate 9 and the pulleys 11, 12, and
There is no interposition between it and 0. In the present invention, in order to prevent dust from entering between the pulleys 11, 12 and the inner guard plate 10 into the sliding part of the pulleys, as clearly shown in FIGS. 3 and 4, , on the inner surface of the inner guard plate 10,
Inward annular protruding dust cover portions 19, 19 are integrally formed to fit into annular grooves 17a formed on the side surfaces of the pulleys 11, 12 on the inner guard plate side. Such dust cover parts 19, 19 are attached to the inner guard plate 1.
0 can be easily formed by die-casting using aluminum or an aluminum alloy as a material. Furthermore, in the present invention, as shown in FIG.
An inclined surface 20 is formed that bulges out toward the rear from the front edge 19a of 9. As described above, in the present invention, as is clear from FIG. 17a
Therefore, no gap is formed between the pulley 12 and the inner guard plate 10 in the front part of the tensioner 8, and the tensioner 8 moves too far toward the wheel and the inner guard plate 10 Even if it comes into contact with the spokes S of the rotating wheel, the spokes will not get caught between the pulley and the inner guard plate as in the conventional case. Moreover, in this invention,
Since an inclined surface 20 is formed on the outer surface of the inner guard plate 10 that bulges out toward the rear from the front edge 19a of the dust cover part 19, even if the spoke S collides with the guard plate 10 from the front, Since this spoke S is rebounded by the slope effect, there is no danger of the tensioner 8 jumping between the spokes. As shown in FIGS. 2 and 4, in this example, in particular, the outer surface of the inner guard plate 10 has a ridge that bulges downward, almost parallel to the slope of the spoke S. 21 is formed.
In this way, when the tensioner 8 moves excessively, the spokes S first come into contact with somewhere on the ridge 21, thereby increasing the effect of preventing the tensioner 8 from jumping between the spokes. Furthermore, in this example, as shown in FIGS. 2 and 5, the front edges 9a and 10a of the intermediate portions of both the inner and outer guard plates 9 and 10 are bent inwardly and brought into contact with each other, and the tensioner 8 is This prevents foreign objects from entering between the guide pulley 11 and the tension pulley 12 from the front, and reduces the fluid drag coefficient of the tensioner 8. It goes without saying that the scope of the present invention is not limited to the embodiments described above. For example, in the above description, the inclined surface portion 20 was mainly explained as being formed on the inner guard plate near the tension pulley support portion, but this also applies to the inner guard plate near the guide pulley support portion. can be formed. That is, 20' in Fig.
As shown in FIG. 1, the dust cover portion 19 formed on the inner guide plate 10 or the inner surface thereof near the guide pulley 11 can also be formed with a sloped portion. In Figure 1, the guide pulley 1
The tensioner 8 is positioned so that the tensioner 1 and the tension pulley 12 are vertically aligned with each other, but the tensioner 8 is largely rotated in the direction of the arrow A in FIG. 1, for example, by 90 degrees from the state shown in FIG. In some cases, the guide pulley 11 and tension pulley 12 may be lined up one after the other, and in such a case, the spokes S will first hit the area shown at 20' in Figure 4. be. in this case,
The upper part of FIG. 4 is the actual front part, and the lower part is the actual rear part.

[Brief explanation of the drawing]

FIG. 1 is a view of a bicycle rear derailleur 1 to which the present invention is applied, seen from the wheel side, FIG. 2 is a view taken in the direction of the arrow in FIG. 1, and FIG. 3 is an enlarged sectional view taken along the - line in FIG. 1. 4 is an enlarged sectional view taken along the - line in FIG. 1, and FIG. 5 is an enlarged sectional view taken along the - line in FIG. 1. 1... Bicycle rear derailleur, 8... Tensioner, 9... Outer guard plate, 10... Inner guard plate, 11... Guide pulley, 12... Tension pulley, 17... Annular groove, 19... Dust cover Part, 20... Inclined surface, C... Chain.

Claims (1)

[Scope of utility model registration request] A tensioner is provided in which an outer guard plate and an inner guard plate are opposed to each other at a predetermined interval, and a guide pulley and a tension pulley are rotatably supported between them, and the chain is multi-staged by moving this tensioner in a predetermined direction. In a bicycle rear derailleur that can be replaced with a desired freewheel sprocket, an inward annular protrusion-shaped dust cover part that fits into an annular groove formed on the side surface of the pulley is integrally formed on the inner surface of the guard plate. A rear derailleur for a bicycle, characterized in that the outer surface of the guard plate is provided with an inclined surface that swells toward the rear from the front edge of the dust cover section.