Experimental and Calculation Analysis of Rotational Vibration for an Engine Front End Accessory Drive System

Experimental methods for measuring static and dynamic characteristics of an engine Frond End Accessory Drive System (FEADS) are presented. The static performance of a FEADS is the static tension of the belt, and the dynamic properties of a FEADS are transverse vibration of belt, and rotational vibration performances that include rotational response of pulleys and tensioner arm, dynamic tension of belt span, slip factor between belt and pulley. A mathematical model and calculation method for rotational vibration analysis of a 8 pulley-belt FEADS is established. In the model, creeping effect of a belt on pulley wrap arc, viscous damping and dry friction of a tensioner are considered. In calculation of dynamic performances of the FEADS, the excitation torques with multi-frequency components from crankshaft torsional vibration are obtained from the measurement. The static tension and steady-state tension in belt spans, natural frequency of a FEADS, rotational response of driven pulleys and tensioner arm, dynamic tension of belt span, slip factor between belt and pulley are estimated with the proposed method. The calculated and tested rotational response of driven pulley and tensioner arm, and tension of each belt span are compared well with experiment, which validate the presented model and calculation method. The modeling method and experimental procedure are instructive for designing a FEADS.