FREE-VIBRATION OF SERPENTINE BELT DRIVE SYSTEMS

The vibration of an automotive serpentine belt drive system greatly af fects the perceived quality and the reliability of the system. Accesso ry drives with unfavorable vibration characteristics transmit excessiv e noise and vibration to other vehicle structures, to the vehicle occu pants, and may also promote the fatigue and failure of system componen ts. Moreover, these characteristics are a consequence of decisions mad e early on in the design and arrangement of the accessory drive system . The present paper focuses on fundamental modeling issues that are ce ntral to predicting accessory drive vibration. To this end, a prototyp ical drive is evaluated, which is composed of a driven pulley, a drivi ng pulley, and a dynamic tensioner. The coupled equations of free resp onse governing the discrete and continuous elements are presented here in. A closed-form(1) solution method is used to evaluate the natural f requencies and modeshapes. Attention focuses on a key linear mechanism that couples tensioner arm rotation and transverse vibration of the a djacent belt spans. Modal tests on an experimental drive confirm the t heoretical predictions.