Patent ID: 9611903
Date: 2017-04-04
CPC Classifications: F16D,F16F,F16H

Claim:
1. A pulley structure comprising: a first rotatable body having a cylindrical shape, over which a belt is stretched; a second rotatable body that is provided inward of the first rotatable body so as to be rotatable relative to the first rotatable body; and a torsional coil spring that is accommodated in a space between the first rotatable body and the second rotatable body, wherein the torsional coil spring has one end region at one end side thereof, the outer circumferential surface of which is in contact with one rotatable body of the first rotatable body and the second rotatable body due to the self elastic restoring force of the torsional coil spring in a diameter increasing direction when the pulley structure is in a stopped state; the other end region at the other end side thereof, the inner circumferential surface of which is in contact with the other rotatable body when the pulley structure is in the stopped state; and a middle region, and wherein when the torsional coil spring is twisted in the diameter increasing direction due to a relative rotation between the two rotatable bodies, the inner circumferential surface of at least a circumferential portion of the other end region of the torsional coil spring separates from the other rotatable body.