Abstract: A prototypical serpentine belt drive system, which includes a driving pulley, driven pulleys, one tensioner and belt, is taken as a research example for measuring and calculating the rotational vibration of pulley and belt transverse and tensioner arm motion in serpentine belt drive systems. A model for modeling the prototypical serpentine belt drive system to calculate the vibration of pulley and belt is presented. In the model, the belt is simplified as axially moving string, and the pulley is regarded as rotational rigid body. Garlerkin method is applied for discretizing the continuous equation of belt. The estimated and tested driven pulley rotational response, slip rate between driven pulley and belt, midpoint transverse deflection of span, belt natural frequency agree well, which validate the mathematical model. The method of measurement and calculation presented is useful for designing complex serpentine belt drive system, such as engine front end accessory drive system.

Key words: Belt transverse vibration, Pulley rotational motion, Serpentine belt drive system