Two-layer engine front end accessory drive systems (TEFEADS) are adopted generally by commercial vehicles due to the characteristics of accessory pulleys, which have large torque and moment of inertia. Taking a TEFEADS with nine pulleys as an example, the mathematical model for rotation vibrations of the TEFEADS is established. In the modeling, based on the principle of equal energy dissipation, the equivalent stiffness and damping of tensioner arm are proposed. The dynamic characteristics, such as angular displacement of tensioner arm, dynamic tensions of belt spans, and slip rates between belt and pulleys, of the TEFEADS under steady and acceleration conditions are calculated by the established model and validated by the bench experiment.The established model provides a reference for prediction of dynamic performances of TEFEADS.
 

Two-layer engine front end accessory drive systems,Hysteresis characteristic,Rotation vibration,Dynamic response