Study On Dynamic Response Characteristics Of BSG Belt Drive System

As the number of cars increases year by year,urban traffic congestion has become a common problem,leading to an increase in engine idle time.In order to solve this problem,micro hybrid technology has emerged,among which the BSG(Belt Driven Starter Generator)start-stop system is a commonly used technology.Compared with traditional engine modifications,it requires less modification and cost,and can reduce fuel consumption.The BSG system not only realizes the idle start-stop function,but also achieves energy recovery.However,the dynamic characteristics of the system change significantly,making it difficult to design the front-pulley drive layout and the matching of the tensioner structure parameters.This paper studies a BSG belt drive system with a double tension arm automatic tensioner,analyzes its dynamic response characteristics under various operating conditions,and seeks a more reasonable design solution.Using the Simdrive 3D Belt module and Crank Drive module,a multi-body dynamic model of the BSG belt transmission system is established.The model considers the longitudinal,radial,and bending stiffness of the multi-wedge belt,as well as the inertia forces of the reciprocating motion of the crank-connecting rod mechanism.At the same time,the changing excitation curve and load curve over time are taken into account to simulate the starting process more realistically.The rigid finite element method is used to discretize the multi-wedge belt,and the Galerkin method is used to spatially discretize the system to obtain the lateral vibration characteristics of the belt section of the transmission system.Using the Adams-Bashforth-Moulton predictor-corrector method,the dynamic response characteristics of the BSG belt drive system are solved.Under the startup condition,the response characteristics of the system,such as the rotating speed of the accessory pulley,belt tension,belt-pulley contact stress,and slip rate,are studied.The results show that the axial force on the second tensioner pulley reaches 3420 N,and the maximum slip rates of the motor pulley and crankshaft pulley are 20.7% and 17.2%,respectively.The maximum swing angles of tension arm 1 and tension arm 2 are 18.7deg and 17.0deg,respectively,indicating a high risk for the belt drive system.Under acceleration conditions,there is no risk factor for the system response characteristics due to the large initial load torque of the BSG motor and the power source switching process.Based on the dynamic simulation model of the BSG belt drive system under startup conditions,the control variable method is used to study the influence of automatic tensioner structural parameters and multi-wedge belt initial tension on the system’s dynamic response characteristics.By range analysis,it is found that the damping of the tensioner has the most significant effect,and the structural parameters of tensioner 1 have a greater influence than tensioner 2.A comprehensive analysis of the influence of the initial tension of the multiwedge belt on the system’s dynamic response characteristics shows that increasing the initial tension appropriately is beneficial for the system.In response to the existing risks of the system,the automatic tensioner’s structural parameters are optimized using the gradient projection method.The optimization scheme’s simulation results are compared with the original scheme,under the starting conditions,the maximum pulley pressing force of tensioner 2 decreases by 550 N.The maximum swing angles of tension arm 1 and tension arm 2 decrease by 9.8deg and 8.6deg,respectively,and the slip rates of the motor pulley and crankshaft pulley decrease by 10.4% and 12.5%,under accelerating conditions,the dynamic response characteristics of the system are basically unchanged,all of which meet the design requirements,thereby improving the stability and transmission efficiency of the BSG belt drive system.