JPS6219517Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a sprocket for bicycles, more specifically, a large number of teeth are provided around the outer periphery of the sprocket body, and a chain is engaged with these teeth to transmit pedal force to the rear wheel. The present invention relates to a bicycle sprocket that constitutes a multi-stage sprocket on the rear side.

Generally, in a bicycle, a multi-stage sprocket constructed by combining two or more sprockets with different numbers of teeth is attached to the rear wheel hub, and a derailleur moves the chain in the axial direction of the sprocket. It is configured so that the force applied to the pedals is transmitted to the rear wheels at a predetermined gear ratio.

Incidentally, the sprocket is formed by punching a single steel plate with a punching die, and the portion of the punching die that forms the tooth tip surface of each tooth of the sprocket is Since the sprocket is an arcuate surface centered on the rotation center of the sprocket, the sprocket punched using this punching die has a tooth tip surface b of each tooth a that is similar to the tip of the tooth, as shown in Fig. 8. It is a smooth surface that curves outward with respect to a virtual flat plane d that connects both ends c and c in the circumferential direction.

Therefore, when changing the chain from a large-diameter sprocket with many teeth to a small-diameter sprocket with few teeth as a multi-stage sprocket, the chain that is away from the teeth of the large-diameter sprocket is lifted, and the link plate of the chain is moved to the large-diameter sprocket. After the chain rides on the tooth tip surface of the sprocket tooth, it meshes with the tooth of the small diameter sprocket, but the state in which the chain rides on the tooth tip surface of the large diameter sprocket tooth rides on the tooth tip surface. It became unstable, and the chain slipped to the side where it engaged with the teeth of the original large-diameter sprocket that was being replaced with the small-diameter sprocket, making it impossible to shift gears.

Furthermore, when replacing a chain from a small-diameter sprocket to a large-diameter sprocket, the link plate of the chain that has moved away from the teeth of the small-diameter sprocket and toward the large-diameter sprocket is pressed against the side surface of the teeth of the large-diameter sprocket, and the outer link in the chain The chain is lifted by the side edge of the plate catching on the edge c of the teeth of the large diameter sprocket, but slipping occurs between the tip edge of the teeth of the large diameter sprocket and the chain, causing the chain to The engagement with the tip edge of the tooth was poor, and the meshing with the large diameter sprocket tooth of the chain was delayed accordingly, resulting in poor gear shifting performance.

This invention was devised in view of the above-mentioned problems, and the purpose is to stably maintain the state in which the chain rides on the tooth tip surface of the large-diameter sprocket, especially when changing the chain from a large-diameter sprocket to a small-diameter sprocket. It is an object of the present invention to provide a sprocket which allows the chain to be satisfactorily caught on the tooth tip edges of the large-diameter sprocket teeth when changing the chain from a small-diameter sprocket to a large-diameter sprocket.

Therefore, the present invention is a bicycle sprocket comprising a large number of teeth arranged around the outer periphery of a sprocket body, and a resistor that engages with a chain and provides resistance to slippage of the chain on the tooth tip surface of each tooth. It is characterized by providing means.

An embodiment of the sprocket of the present invention will be described below with reference to the drawings.

In the figure, reference numeral 1 denotes a ring-shaped sprocket body having a center hole 1a, and a large number of teeth 2 are provided around the outer periphery of the sprocket body at predetermined intervals. still,
The sprocket main body 1 and the teeth 2 are formed by punching a metal plate using a punching die, but they may also be formed by die-casting, for example.

Therefore, the length l of the tooth tip surface 21 of each tooth 2 with respect to the rotation center O is set to be less than or equal to the virtual flat plane Rim 22, 22
In addition to forming an inwardly curved surface where the gap is curved toward the rotation center, the tooth tip surface 21 is provided with a resistance means that engages with the chain and provides resistance to slippage of the chain.

As shown in FIGS. 1 and 2, this resistance means is constructed by arranging a large number of minute protrusions 23 on the tooth tip surface 21 that extend in the axial direction of the sprocket body 1. Although it is preferable that this resistance means be provided on the tooth tip surface 21 which is an inwardly curved surface as explained above, it is also preferable to provide this resistance means on the tooth tip surface which is an outwardly curved surface that is curved outward with respect to the virtual flat plane X. Alternatively, as shown in FIG. 5, it may be provided on the tooth tip surface which is a flat surface parallel to the virtual flat surface X, or as shown in FIG.
3, for example, two V grooves extending in the axial direction of the sprocket body 1 are provided on the tooth tip surface 21 as shown in FIG. You can also
Further, as shown in FIG. 4, each tooth tip surface 21 is formed as an outer curved surface that curves outward with respect to the virtual flat plane 25, and its structure is not particularly limited. In the case of FIG. 3, the protrusion at the central position may be made to protrude outward from the virtual flat surface X, and in the case of FIG. Preferably, edge 22a is cut away.

The teeth 2 are provided parallel to the center line between one side and the other side in the thickness direction of the sprocket body 1, but are also provided at a predetermined angle with respect to the center line Y as shown in FIG. The tooth may be inclined so that one circumferential edge of the inclined tooth tip protrudes axially outward from the tooth bottom position. In this case, due to the protrusion of the edge, the engagement with the chain becomes even better. Further, the teeth protruding outward in the axial direction from the tooth bottom position have a front edge in the rotational direction,
Further, it is preferable that the ridge corner portion on the center line Y side is chamfered.

The sprocket constructed as described above is a set of two or more sprockets having different numbers of teeth and is attached to the rear wheel hub to be used as a multi-stage sprocket on the rear side.This case will be explained next. For convenience of explanation, the small diameter sprocket is indicated by the symbol A, and the large diameter sprocket is indicated by the symbol B.

Therefore, when changing the chain 3 from the large-diameter sprocket B to the small-diameter sprocket A, when the chain 3 is pushed in the direction of the small-diameter sprocket A by the derailleur, the chain 3 is lifted away from the teeth 2 of the large-diameter sprocket B. As a result, the link plate 31 of the chain 3 rides on the tooth tip surface 21 of the tooth 2 of the large diameter sprocket B. At this time, the tooth tip surface 21 of the tooth 2 is provided with resistance means, for example, a large number of minute protrusions 23, which engage with the chain 3 and provide resistance to the sliding of the chain 3. This makes it possible to stably hold the chain 3 that has climbed onto the ground. Therefore,
This allows the chain 3 to be quickly replaced with the small diameter sprocket A.

Further, the tooth tip surface 2 of the teeth of the large diameter sprocket B
1 is an inwardly curved surface that curves inward with respect to the virtual flat plane X as shown in FIG. 2, or a W-shaped uneven surface as shown in FIG. The raised chain 3 can be held even more stably.

Also, when changing the chain 3 from the small diameter sprocket A to the large diameter sprocket B, when the chain 3 is pressed in the direction of the large diameter sprocket B by the derailleur, it will move away from the teeth of the small diameter sprocket A and move to the large diameter sprocket B side. The link plate 31 of the chain 3 that has been moved to the tooth 2 of the large diameter sprocket B
The side edge of the outer link plate is pressed against the side edge of the tooth 2 of the large diameter sprocket B.
2, the chain 3 is lifted and meshes with the teeth 2 of the large diameter sprocket B. At this time, the tooth tip surface 2 of the tooth of the large diameter sprocket B
1, for example, by providing resistance means consisting of minute protrusions 23 as shown in Figs. 2 and 5, or by providing resistance means consisting of W-shaped chevron protrusions 24 as shown in Fig. 3. The engagement between the tooth tip edge 22 of the sprocket tooth and the chain 3 can be improved, and the chain can be engaged with the large-diameter sprocket tooth more quickly, thereby improving the speed change performance.

As described above, the present invention provides a resistance means on the tooth tip surfaces of a large number of teeth provided around the outer periphery of the sprocket body, which engages with the chain and provides resistance to the slippage of the chain. When changing the chain to a small diameter sprocket, the chain riding on the tooth tip surface of the large diameter sprocket can be suppressed from slipping against the tooth tip surface, and the state where the chain rides on the tooth tip surface can be stably maintained. It can be done. Therefore, it is possible to quickly change the chain to a small diameter sprocket.
This allows for improved shifting performance.

Moreover, due to the resistance means provided on the tooth tip surface,
When changing the chain from a small-diameter sprocket to a large-diameter sprocket, the chain can be properly caught on the tooth tip edges of the large-diameter sprocket teeth, so the chain can be quickly changed to the large-diameter sprocket. , speed change performance can be improved.

[Brief explanation of the drawing]

Figure 1 is a front view showing one embodiment of the sprocket of the present invention, Figure 2 is an enlarged view of only the teeth, Figures 3 to 6 are partially enlarged views of another embodiment, and Figure 7 is a chain. FIG. 8 is a partially enlarged view of a conventional sprocket. 1...Sprocket body, 2...Teeth, 21...
Tooth tip surface, 23, 24, 25...resistance means.

Claims (1)

[Scope of utility model registration request] A bicycle sprocket comprising a large number of teeth arranged around the outer periphery of a sprocket body, wherein a resistance means is provided on the tip surface of each tooth to engage with a chain and provide resistance to slippage of the chain. Bicycle sprockets with special features.