Proportionally damped power transfer device using torsion spring force

A decoupler for transferring torque between a shaft and an endless power transmitting member, the decoupler comprising:

• a hub configured to couple to the shaft and to rotate with the shaft about a rotational axis;
• a pulley rotatably coupled to the hub and including a power transmitting surface configured to engage the endless power transmitting member;
• an isolation spring configured to transfer a rotational load from one of the pulley and the hub to the other of the pulley and the hub;
• a one-way clutch configured to permit overrunning of one of the pulley and the hub relative to the other of the pulley and the hub in a first rotational direction;
• a damping member positioned to be driven into frictional engagement with a friction surface on one of the pulley and the hub by a force acting on the damping member that varies based on the rotational load transferred by the isolation spring, such that a frictional damping force that is provided by the damping member varies based on the rotational load transferred by the isolation spring,
• wherein the damping member is radially between the isolation spring and the friction surface, and the force is a radial reaction force generated by the isolation spring in response to the rotational load being transferred, which urges the damping member into the friction surface;
• and
• a bearing member that is a bushing, and which is configured to support the pulley on the hub and the bearing member includes the damping member, wherein the friction surface is a radially inner surface of the pulley.