Tensioner with viscous coupled one way wrap spring anti-kickback clutch

摘要

A timing belt tensioner for a motor vehicle engine comprising a pivot that is fixed relative to the motor vehicle engine. A tensioner arm is mounted for pivotal movement on the pivot. The tensioner arm has a friction surface disposed in friction sliding relation with an adjacent surface during the pivotal movement. A belt engaging pulley is mounted for rotation on the tensioner arm. A spring coupled with the tensioner arm biases the arm in a direction tending to force the pulley into tensioning engagement with the belt when the tensioner is installed on the motor vehicle engine. The spring biasing the arm into a working position maintains a predetermined range of tension in the belt during dynamic operating equilibrium of the belt. An anti-kickback stop mechanism is coupled with the arm and stops instantaneous kickback movement of the arm against the belt tensioning direction beyond when the arm is instantaneously moved away from the working position against the belt-tensioning direction in response to instantaneous tightening of the belt. The anti-kickback mechanism adjusts a location of the stop position based upon the working position of the arm.