Endless belt power transmission systems or components – Positive drive pulley or guide roll
Patent
1997-10-08
1999-11-09
Hannon, Thomas R.
Endless belt power transmission systems or components
Positive drive pulley or guide roll
745942, 74572, 188264A, F16H 5530, G05G 114, G05G 300
Patent
active
059804076
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a rotary member for transmitting a drive force or a braking force of a sprocket, a brake disc or the like.
In general, a mechanism having a pair of sprockets and a change laid therebetween has been widely used as a drive force transmission means in a motorcycle or a bicycle.
Usually, a sprocket is integrally formed of an annular hub portion arranged in the center thereof, an annular ring portion arranged in a circumferential portion thereof, and a plurality of arm portions extending radially and arranged between the hub portion and the ring portion for connecting the hub portion and the ring portion at a constant angular interval in the circumferential direction.
A carbon steel plate has been widely used as a material for the sprocket. In a manufacturing method, after the carbon steel plate has been machined to have a form of the sprocket by mechanical machining or pressing, a tooth portion is annealed to have a desired hardness. Thereafter, a finishing treatment is effected on the sprocket.
Also, in view of an aesthetic design demand, there is a sprocket 100, as shown in FIG. 15, in which a center PR of a distal end portion on a ring portion 102 side and a center PH of a proximal end portion on a hub 103 side of each arm portion 101 are offset at a constant angle in the circumferential direction.
On the other hand, a brake disc in which an annular braking portion is formed in its outer circumferential portion and the braking portion clamped by pad members to generate the braking force has been extensively used as a braking mechanism in a motorcycle or the like.
A so-called floating disc brake mechanism has been widely practically used, in which a braking portion against which pad members are to be pressed and a disc like hub portion externaly fixedly mounted on an axle or the like are formed of discrete members, respectively; a plurality of pin members are mounted between the hub portion and the braking member; the braking portion is floatingly supported to the hub portion; and the braking portion and hub portions are slit at their edge to thereby prevent a warpage of the disc brake caused by heat generated during the braking operation.
Also, in a brake disc 110 as shown in FIG. 16, a hub portion 111 and a braking portion 112 are integrally formed with each other; the hub portion 111 and the braking portion 112 are coupled with each other through a plurality of arm portions 113; and in view of the aesthetic design demand, a center PR of a distal end portion on a braking portion 112 side and a center PH of a proximal end portion on a hub 111 side of each arm portion are offset in the circumferential direction with constant regularity.
In the sprocket in which the arm portions are radially arranged, after the annealing treatment for the tooth portion, the ring portion tends to shrink inwardly, but the hardness of the ring portion per se is high by the annealing treatment so that the shrinkage force is applied to the arm portions and the hub portion as a compression stress. Then, due to the compression stress, such a phenomenon that portions, corresponding to the arm portions, of the hub portion are deformed inwardly is generated. For this reason, after the annealing treatment of the tooth portion, a machining is effected to the inner circumferential surface of the hub portion. A cutting step is required to keep the inner circumferential surface in an exact circle. Thus, there is a disadvantage that the manufacturing steps for the sprocket are complicated.
Also, in order to solve this problem, it is possible to try to form the ring portion and the hub portion from discrete members like the braking portion and the hub portion of the floating disc brake. However, in this case, the number of the components is increased to raise the manufacturing cost corresponding to the additional components.
The present application made and tested various changes in shape of the arm portions and weight reduction holes on the basis of the concept that the compressio
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Metsugi Fumihiko
Ohata Akihito
Takamori Norihiko
Hannon Thomas R.
Kaness Matthew A.
Sunstar Engineering Inc.
Uni-Sunstar B.V.
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