JPH0141675Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is a bicycle sprocket used as a front or rear sprocket of a bicycle, specifically, the sprocket body is formed of a metal plate thinner than the inner plate spacing of the chain. This invention relates to a bicycle sprocket in which the tips of the teeth provided around the outer periphery of the sprocket body are bulged toward one side in the axial direction of the sprocket body.

(Prior Art) The applicant of the present invention has previously disclosed in Japanese Utility Model Publication No. 1989-19000, that is, as shown in FIG. By making the tips 4a of the teeth 4 disposed around the outer periphery of the sprocket body 1 bulge out to one side in the axial direction of the sprocket body 1, the strength of the sprocket body 1 is strengthened, and a thin metal plate can be Despite being lightweight and inexpensive,
He proposed a bicycle sprocket that was comparable to those using thick metal plates.

(Problems to be Solved by the Invention) However, in the conventional bicycle sprocket, if the chain line of the chain 5 that meshes with the teeth 4 of the sprocket body 1 is displaced in the axial direction, there is a problem that noise occurs. It was hot.

That is, when the longitudinal center of the bottom bracket and the center between the pair of back forks are displaced in the width direction, the chain line of the chain 5 suspended between the front sprocket and the rear sprocket may be out of order. When the chain 5 is running, the portion of the chain 5 that enters the front sprocket engages with the front sprocket in an inclined manner.

However, when the bicycle sprocket is applied to, for example, a front sprocket, if the chain line of the chain 5 is out of alignment as described above and the chain 5 meshes with the front sprocket in an inclined manner, the sprocket Main body 1
Since the tooth tips 4a of the teeth 4 disposed around the sprocket body 1 are bulged and displaced in the axial direction with respect to the sprocket body 1, as is clear from FIG. The inner end surface rides on the tooth bottom 4b portion of the tooth 4, that is, the roller 8 supported between the inner plates 6 does not fall into the tooth bottom 4b portion, and is once engaged in an incomplete state, and the chain 5 due to the pedal depression. With the tension of The noise occurred when the roller 8 fell into the tooth bottom 4b.

(Means for Solving the Problems) The present invention was devised in view of the above problems, and provides a bicycle in which the chain can be completely meshed with the teeth of the sprocket body without producing noise. The present invention provides a sprocket for use in a sprocket, in which a bulging side is provided on the outer circumference of the sprocket body and on a side surface opposite to the bulging side of the tooth, extending radially inward from the bottom portion of the tooth. A missing portion is provided to prevent interference with the tooth bottom portion of the inner plate.

(Function) However, if the chain line of the chain is displaced in the axial direction and the chain engages with the teeth of the sprocket body in an inclined manner, the inner plate of the chain can be inserted into the missing part. This is to prevent interference between the inner plate and the bottom portion of the tooth, and to prevent noise caused by interference between the inner plate and the bottom portion of the tooth.

(Embodiments) The bicycle sprocket according to the present invention will be explained below with reference to embodiments shown in the drawings.

In the figure, 1 is the sprocket body of a bicycle sprocket, which has a mounting hole 2 for the crank in the center, and a plurality of support holes for supporting the chain guard on the circumference line centered on the mounting hole 2. 3, and a large number of teeth 4 are formed on the outer periphery of the sprocket body 1.

Reference numeral 5 denotes a chain that meshes with the teeth 4, which connects a pair of inner plates 6 and outer plates 7 that face each other at a predetermined interval, and supports a roller 8 at this connected portion.

The sprocket body 1 is formed of a metal plate thinner than the interval between the inner plates 6 of the chain 5, for example, a metal plate with a thickness of 2 mm, whereas a metal plate with a thickness of 3 mm is generally used for a 1/8 inch chain. Therefore, although the tooth tips 4a of the teeth 4 provided on the sprocket body 1 are bulged to one side in the axial direction and are formed from a thin metal plate, they are formed from a thick metal plate. It seems to ensure the same strength.

In the illustrated embodiment, the sprocket main body 1 is recessed in the inner circumference near the tooth tip 4a over the entire circumference, thereby displacing the tooth tip 4a with respect to the recessed fitting portion 1a. That's what I do.

In the bicycle sprocket as described above, on the outer circumferential portion of the sprocket body 1, a bulge is formed on the side surface opposite to the bulging side of the tooth 4 from the bottom 4b of the tooth 4 inward in the radial direction. A missing portion 9 is formed on the exit side to prevent interference with the tooth bottom 4b portion of the inner plate 6 in the chain 5.

Specifically, the recessed fitting portion 1 of the sprocket body 1 is formed on the side surface opposite to the bulging side of the tooth 4.
A missing portion 9, which is roughly crescent-shaped in front view, is formed on a part of the protruding portion formed on the back surface side of the tooth, and is missing from the tooth bottom 4b portion radially inward and toward the bulging direction of the tooth 4. is formed by cutting or surface pressing, and the cutout 9 prevents interference between the inner plate 6 of the chain 5 and the bottom 4b of the tooth 4.

The missing portion 9 gradually becomes thinner as it goes inward in the radial direction of the sprocket body 1 from the tooth bottom 4b, and finally converges flush with the outer surface of the sprocket body 1. In this way, the inner plate 6 of the chain 5 is smoothly guided inward in the radial direction of the sprocket body 1 by the cutout 9.

The bicycle sprocket of the present invention is constructed as described above, and the chain line of the chain 5 that meshes with the sprocket body 1 is aligned with the tooth row of the teeth 4 provided around the sprocket body 1 as shown in FIG. When the rollers 7 of the chain 5 are positioned in a straight line, the rollers 7 of the chain 5 fall accurately onto the bottoms 4b of the teeth 4, and the chain 5 rotates in a normal state.

Further, the chain line of the chain 5 that meshes with the sprocket body 1 is inclined with respect to the row of teeth 4 provided around the sprocket body 1, as shown in FIG. When engaged in an inclined manner, conventionally the inner plate 6 of the chain 5 rides on the bottom 4b of the tooth 4, causing noise, but in the present invention, the inner plate 6 of the chain 5 rides on the bottom 4b of the tooth 4, causing noise. A notch 9 is formed extending radially inward from the chain 5, so that the inner plate 6 of the chain 5 is guided radially inward along the notch 9, and the inner plate 6 and the tooth bottom are guided radially inward along the notch 9. 4b, the roller 7 of the chain 5 falls smoothly onto the tooth bottom 4b, and the chain 5 rotates normally.

(Effect of the invention) As explained above, in the bicycle sprocket according to the invention, on the outer periphery of the sprocket body,
and on the side opposite to the bulging side of the tooth formed on the main body, a chip is formed radially inward from the bottom portion of the tooth to prevent interference with the bottom portion of the inner plate in the chain. Since the missing part is provided to prevent the inner plate from riding on the bottom of the teeth as in the conventional case, even if the chain line of the chain is displaced with respect to the dentition of the teeth, The inner plate can be guided radially inward along the missing portion with respect to the tooth bottom portion, and the roller of the chain can be smoothly lowered into the tooth bottom portion of the tooth, thereby eliminating noise. It is possible to reliably prevent this, and the chain can be reliably engaged with the teeth of the sprocket body, making it possible to ride the bicycle safely.

[Brief explanation of the drawing]

FIG. 1 is a front view of a bicycle sprocket according to the present invention, FIG. 2 is an enlarged sectional view taken along the line XX in FIG. FIG. 4 is a plan view showing the meshing state when the chain line is displaced, and FIG. 5 is a sectional view showing a conventional example. 1...Sprocket body, 4...Teeth, 4a...
Tooth tip, 4b... Tooth bottom, 5... Chain, 6... Inner plate, 7... Outer plate, 8...
...Laura, 9...missing part.

Claims (1)

[Scope of utility model registration request] A sprocket body is formed of a metal plate thinner than the interval between the inner plates in a chain formed by connecting a pair of inner plates and an outer plate, and the tips of teeth provided around the outer periphery of the sprocket body are connected to the sprocket body. A bicycle sprocket having a main body bulging toward one side in the axial direction, the sprocket having a sprocket radially extending from the bottom portion of the tooth on the outer periphery of the sprocket main body and on the side opposite to the bulging side of the tooth. A bicycle sprocket, characterized in that a missing portion is provided on an inwardly bulging side to prevent interference with the tooth bottom portion of the inner plate.