Dynamic Analysis And Model Application Of Engine Front End Accessory Drive System

Front End Accessory Drive System(FEAD system)is an important subsystem of engine.The crankshaft is the power source of FEAD system,and its torsional vibration will cause the NVH(Noise,Vibration and Harshness)problem.A good layout of FEAD system can basically ensure the transmission of power,increase the life of the belt,reduce maintenance costs and reduce the NVH problem caused by crankshaft torsional vibration.The studies on the layout and dynamic calculation of single-layer FEAD system are relatively mature,but the related studies on multi-layer FEAD system are few.In this paper,the layout and calculation method of the multi-layer FEAD system will be proposed,based on the studies of single-layer FEAD system and the characteristics of diesel engine.The contents can be summarized as follows:(1)With reference to the design theory of single-layer FEAD system,the design method of multi-layer FEAD system is explained.It includes the overall layout design of the multi-layer FEAD system,the parameter design of the multi-ribbed belt and the parameter design of the automatic tensioner.(2)Establish a calculation method of the dynamic performances of FEAD system.Based on the calculation model of rotational vibration of the single-layer FEAD system under steady state condition,the calculation model of the single-layer FEAD system under accelerating condition is established.Combined with the characteristics of multi-layer FEAD system,the calculation method of the vibration response of multi-layer FEAD system is established.The Standard constitutive model is used to establish the string model of the transverse vibration of the belt.(3)Verify and apply the established calculation methods of FEAD system.The test of the dynamic performance of FEAD system is introduced and completed.The experimental data is used to verify the established calculation methods of single-layer FEAD system and multi-layer FEAD system.For the single-layer FEAD system,the similarities and differences in the dynamic performances of FEAD system under steady state condition and accelerating condition are compared.The model is further applied to analyze the influence of using different elastic multi-ribbed belts on the dynamic response of the single-layer FEAD system.(4)The calculation method of the dynamic performances of multi-ribbed FEAD system is used to analyze the dynamic performances of different layout of multi-ribbed FEAD system of the same engine model.From the perspective of dynamic performances,the characteristics of different layouts are explained.According to the design and calculation method proposed in this paper,it will provide theoretical and technical guidance for the design of multi-layer FEAD system,which has practical engineering application value.