JPH0249412Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a pulley for a toothed belt, and particularly to a pulley for driving a rear wheel connected to a rear wheel of a motorcycle.

[Conventional technology]

In recent years, in order to reduce the noise emitted by motorcycles, it has been proposed to transmit power between the engine and the rear wheel using a toothed belt. In addition, in order to reduce the weight of the belt pulley and reduce the number of processing steps, it has been proposed that the belt pulley and gears be press-formed from steel sheet material instead of cast and forged products (for example,
(Japanese Patent Application Laid-Open No. 57-9356).

On the other hand, although press working can provide much better accuracy than cast and forged materials, the accuracy of the tooth profile is inferior to that of machined products. In power transmission by a belt, if the precision of the pulley is not good, that is, if the pulley has a tapered shape, the belt will easily move toward the large diameter portion of the pulley and come off.

[Problem that the invention attempts to solve]

In order to eliminate the low rigidity of the steel plate pulley and the above-mentioned uneven movement of the belt, a flange is provided at the end of the pulley to prevent the belt from coming off, but the edge of the belt comes into contact with the flange. As a result, there is a problem that the edges are easily damaged.

[Means to solve the problem]

This invention aims to solve the above-mentioned problems and obtain a press-made pulley with less damage to the pulley.The purpose of this invention is to press-form a steel plate and bend the cylindrical gear part 8 inward from one end with a draft angle. an inner peripheral part 9 and an outer peripheral part 1 extending in the circumferential direction from the other end.
A pair of half parts A forming a flange consisting of
0 is used as a disc to prevent the belt from coming off, and the diameter of the central portion in the width direction is made slightly smaller.

[Effect]

The half part A of each gear has a cylindrical gear part and two types of flanges, an inner circumferential part and an outer circumferential part, formed on both ends of the cylindrical gear part. is used to connect the two halves A, further increasing the rigidity of the gear.

Further, half part A is press-formed, and a slight draft angle is formed in the outer shape. When the draft angle overlaps the two half parts A, they face each other and create a small diameter part in the center of the gear, so the belt wound around this tends to move towards the center in the width direction of the pulley. be done.

〔Example〕

The present invention will be explained below with reference to illustrated embodiments. 1 is a motorcycle using this invention;
An engine 3 is suspended at the lower center of the vehicle body frame 2, and a rear wheel 5 is supported at the rear of the vehicle body frame 2 via a rear arm 4 so as to be vertically swingable. 6 is a toothed belt that transmits driving force from the engine 3 to the rear wheels 5, and 7 is a pulley provided on the rear wheels 5.

As shown in FIG. 2, the pulley 7 is formed by press-molding a steel plate, and has a cylindrical gear part 8, an inner peripheral part 9 bent inward from one end, and an outer peripheral part extending outward from the other end in the inner peripheral direction. The two halves A of the same shape forming the part 10 are superimposed back to back and bonded to each other at the inner peripheral part 9 by spot welding, gluing, or other methods to form a pulley. The flanges forming the outer peripheral portion 10 regulate both ends of the toothed belt 6 and function as a disc for preventing slippage.
11 is a boss connected to the rear wheel 5 via an axle.

As shown in FIG. 3, the gear portion 8 has a shape in which a steel plate as a material is alternately bent, and is formed when the steel plate is drawn. During press molding, the outer peripheral part 10 is trimmed into a circular shape to prevent wrinkles and is used as a disk for preventing the toothed belt 6 from slipping off. It has a function to firmly maintain the gear so that it does not deform in the circumferential direction and cause the tooth thickness and pitch to become out of order.

Thus, when the motorcycle is driven, pulley 7
engine 3 due to engagement with toothed belt 6
However, at this time, the toothed belt 6 is prevented from being displaced from side to side by the outer peripheral portion 10, so that it does not come off. Also, since the pulley 7 is made up of two halves A connected back to back,
Because the gear part of each half A has a small diameter on the inner peripheral part 9 side due to molding, the axial thrust generated on the belt is offset by the left and right half A. .

Note that if a synthetic resin or aluminum alloy rim (indicated by the two-dot chain line Y in FIG. 2) is bonded or cast on the inner peripheral surface of the gear portion 8, the rigidity of the pulley 7 will be improved, and the noise prevention effect will be further improved. . Furthermore, if only a noise prevention effect is required, it is also effective to bond an elastic material such as rubber.

[Effect of idea]

As described above, the toothed belt pulley 7 of this invention has two halves, each having an inner peripheral part 9 at one end of the gear part 8 and an outer peripheral part 10 at the other end, which overlap at the inner peripheral part 9. Since both halves A can be formed by a simple deep drawing process, manufacturing is easy and high rigidity can be obtained. Furthermore, due to the slight draft created by the press working of the gear portion 8, the toothed belt 6 does not move from side to side and tends to move toward the center in the width direction. Therefore, the chances that both edges of the toothed belt come into contact with the flanges of the outer circumferential portion 10 are reduced, and the durability of the belt can be significantly improved without taking any special measures.

[Brief explanation of the drawing]

The drawing shows an example of this invention.
FIG. 1 is a side view showing the main parts of the motorcycle, FIG. 2 is an enlarged cross-sectional view of the pulley 7, and FIG. 3 is a cross-sectional view. 7... Pulley, 8... Gear part, 9... Inner peripheral part,
10...Outer periphery.

Claims (1)

[Claims for Utility Model Registration] (1) A cylindrical gear part 8 formed by press-molding a steel plate, an inner peripheral part 9 bent inward with a draft angle from one end, and an outer peripheral part extending in the circumferential direction from the other end. 10
A pair of half parts A each having a flange formed from the above are stacked back to back and bonded to each other at the inner peripheral part 9, and the outer peripheral part 10 is used as a disc for preventing the belt from coming off. A pulley for a toothed belt that has a slightly smaller diameter at the center in the width direction. (2) The toothed belt pulley according to claim 1, wherein the pair of half parts A are welded to each other at the inner peripheral part 9.