JPS6015745Y2 - sprocket - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a sprocket used in a front gear, rear gear, etc. of a bicycle.

A bicycle front gear uses a sprocket to transmit the rotation of the crankshaft to the rear axle via a chain, and is formed by stamping a 3rIrIIL sheet metal using a press process or the like.

In recent years, the rigidity of sheet metal has increased, making it suitable for use as a front gear.
It is known that even if a thin layer is used, the strength is sufficient.

However, since the chain itself has a width that corresponds to the conventional thick-walled front gear, if only the front gear is made thinner, the chain may oscillate sideways and make noise.
Or, the mesh may become defective.

In view of these problems, the present invention divides each tooth in the tooth thickness direction and shifts a pair of divided teeth in the tooth width direction to make the tooth width larger than the wall thickness. The purpose of the present invention is to provide a sprocket with good meshing.

Embodiments of the present invention will be described below with reference to the drawings.

In the first embodiment of the present invention shown in FIGS. 1 to 4,
Reference numeral 1 denotes a bicycle frame, and a crankshaft is rotatably supported by the frame, and a crank 2 is fixed to the end thereof.A sprocket 3 is attached to the head 2a of this crank 2, and is fixed to the crankshaft 1. It becomes.

Sprocket 3 is the front gear of the bicycle.
A fitting part 4 that is serrated connected to the head 2a and is prevented from coming out by caulking the end of the head 2a, and a plurality of support arms 5 that protrude radially outward from the fitting part 4. , and an annular portion 6 on the outside of this support arm 5, and are integrally formed of sheet metal.

However, the annular portion 6 may be formed separately for the fitting portion 4 and the support arm 5, and the annular portion 6 may be fixed to the support arm 5 with bolts or rivets.

A gear part 7 around which a chain (not shown) is wound, and a guard part 8 on the side of the gear part 7 are integrally formed in the annular part 6.

The gear part 7 is formed with a large number of teeth 10 that can mesh with the chain, and each tooth 10 is divided into three parts in the tooth thickness direction A, and is formed by divided teeth 10a and 10b at both ends, and the center part is divided into three parts in the tooth thickness direction A. It is bent toward the side to form a bent arm 11 for supporting the guard portion 8.

Each tooth 10 is divided into regular tooth thicknesses, or formed to be larger than the regular tooth thickness, and after division, the divided teeth 10 are
a, 10b are brought closer in the tooth thickness direction A to obtain a regular tooth thickness. According to the latter method, the width of each divided tooth 10a, 10b and the bent arm 11 is increased. be able to.

As is clear from FIG. 4, the pair of split teeth 10a and 10b of each tooth 10 are shifted from each other in the tooth width direction B, and the tooth tip portion tooth width is larger than the root bone width 1 (thickness of the sprocket 3). The tooth width is large, and the tooth width at the tip of the tooth is suitable for the chain.

5 and 6 show a second embodiment of the present invention,
The sprocket 3 is a double gear, and the fitting part 4, the support arm 5, and the gear part 7 of the annular part 6 are the same as in the first embodiment.
A second gear portion 12 is formed instead of the guard portion.

In this second gear part 12, each tooth 10 is divided into two parts in the tooth thickness direction A, and a pair of divided teeth 10a and 10b are in contact with each other and are offset from each other in the tooth width direction. A tooth width is formed at the tip of the tooth for meshing.

This second gear part 12 can also be applied to a single gear, in which case the guard part 8 is formed separately or the annular part 6
It is bent from the inner circumferential part and molded into one piece.

In both of the embodiments, a pair of split teeth 10a, 10b
are both bent and shifted in opposite directions by the same amount, but as shown in FIG. 7, the split teeth 10a, 10b
Only one of them may be bent laterally and shifted in the face width direction B with respect to the other.

According to the present invention described in detail above, the tooth 10 is divided in the tooth thickness direction A, and the pair of divided teeth 10a and 10b are shifted from each other in the tooth width direction B, so that the tooth width at the tip portion is reduced to the valley. The sprocket width is larger than the width 1 of the sprocket, and even if the sprocket 3 is made of a thin sheet metal, the tooth width is approximately the same as that of a thick-walled one, and the sprocket 3 can be made lightweight and inexpensive, and it can be easily meshed with a conventional chain. can be carried out well and generates little noise.

[Brief explanation of drawings]

1 to 4 show a first embodiment of the present invention,
Fig. 1 is an overall sectional view, Fig. 2 is a perspective view, Fig. 3 is an enlarged explanatory view of the main part, Fig. 4 is an enlarged front view of the main part, and Figs. 5 and 6 are the second part of the present invention. 5 is a perspective view, FIG. 6 is an enlarged front view of the main part, and FIG. 7 is an enlarged front view showing a modification of the teeth. 3...Sprocket, 7...Gear part,
10...teeth, 10a, 10b...divided teeth, 11...bent arm, A...tooth thickness direction, B... Tooth width direction, 1... Valley bone width (
Sprocket wall thickness), L...Tooth tip width.

Claims (1)

[Scope of utility model registration request] Each tooth 10 is divided into a pair of divided teeth 10 in the tooth thickness direction A.
A sprocket characterized in that atlOb are shifted from each other in the tooth width direction B.