Dynamics Analysis And Optimization For An Integrated Starter-generator Belt Drive System

The micro hybrid engine system with BSG (Belt Driven Starter and Generator) is beng more and more widely used in small vehicles. The front end accessory belt drive system of the engine is quite different from that of the traditional engine, i.e., the the integrated starter/generator has to start the engine via the transmission belt, by overcoming significant resistance torque. Computer-aided approach was used in this dissertation to design and optimize the parameters of an integrated starter/generator belt drive system.MBS model of the belt drive system was firstly established and validated using ADAMS platform. To overcome the drawback of constant assumption of the resistance torque during engine starting in traditional research works, this paper established a detailed mathematical model for the resistance torque estimation, on the basis of kinematic and dynamic analysis of the crank system, further simulation work was also conducted.Performance simulation of the BSG belt drive system was performed by use of the established MBS model and resistance torque model, under conditions of engine starting, vehicle cruise and braking, respectively. Dynamics analysis results show that the drive belt might slip during engine starting with the present parameters. Swing angle of the tensioner arm, dynamic tension force and lateral vibration of the drive belt, are larger than those in normal states, for example, the swing angle of the tensioner arm reaches12.5°during engine starting, dynamic tension force variation of the belt reaches1200N, and lateral vibration amplitude of the belt also reaches14mm or so.To tackle the above problems, parameters of the tensioner were optimized by using single-objective and muti-objective methods, respectively. Optimization and further simulation results indicate that the drive belt no longer slips during engine starting. The max swing angle of the tensioner arm drops to4.4°, the max dynamic tension force variation of the belt drops to809N, and the lateral vibration amplitude of the belt also declines to4.8mm. Thus, significant effects were achieved after the parameter optimization. By using the multi-objective optimization approach, progress was achieved not only in the initial tension force the drive belt, but also in other comprehensive performance. Therefore, the multi-objective optimization approach is more optional and suggested in engineering applications.There is no mature theory and method available for the design of BSG belt drive system up to now, the research work and pertinent results of this paper might be useful or as reference for the design and optimization of similar systems.