Patent ID: 7588507

Claim:
An autotensioner comprising: a base that has a bottomed tubular shape; a rocking arm that has a tubular part rotatably supported at the inside of said base; a pulley that is attached to one end of said rocking arm, and abuts against a belt; a torsion coil spring that is housed in said base, and biases rotation of said rocking arm in a direction tensioning said belt with respect to said base; and a friction member that is interposed between an outer circumferential surface of said tubular part and an inner circumferential surface of said base; said torsion coil spring being attached eccentrically to the axial center of said base, one end of said torsion coil spring is connected to said base and the other end of said torsion coil spring is connected to said rocking arm, and said rocking arm being supported to be able to be displaced relative to said base, such that a first damping force acting on said rocking arm when said belt is tensioned is relatively larger than a second damping force acting on said rocking arm when said belt is slack.