Belt tensioner with variably proportional damping

Abstract

In a belt tensioning device of the type including a fixed structure, a pivoted structure mounted with respect to the fixed structure for pivotal movement about a first axis between first and second limiting positions, a belt engaging pulley rotatably carried by the pivoted structure for rotational movement about a second axis parallel with the first axis and a torsional coil spring acting between the fixed and pivoted structures for resiliently biasing the pivoted structure to move in a direction away from the first limiting position toward the second limiting position with a spring force which decreases as the pivoted structure is moved in a direction away from the first position toward the second position. The device is provided either with an elastomeric damping body for (1) damping by elastomeric material displacement normal low amplitude operating movements of the pivoted structure and (2) damping sequentially by high friction surface sliding abnormal high amplitude movements of the pivoted structure beyond those which are damped by the elastomeric material displacement with a damping force which decreases as the pivoted structure is moved in a direction away from the first position toward the second position or a Zytel damping body for damping by friction surface sliding substantially all movements of said pivoted structure with a damping force which decreases as the pivoted structure is moved in a direction away from the first position toward the second position.