| With the development of automobile technology,the problem of vibration and noise of automobile transmission system has become more and more prominent,and it has become one of the main sources of vibration and noise of the whole vehicle.The automotive powertrain consists of various components about the engine and transmission system.The vibration and noise problems of automotive powertrain depend not only on the characteristics of the transmission system,but also on the vibration of the engine’s power output characteristics.Therefore,based on the development requirements of a certain enterprise,this paper starts with the modeling of the main components of the engine,transmission and drive axle of the automotive powertrain system,establishes the simulation model of the transient impact characteristics of the automotive powertrain system,and analyzes the typical working conditions parameters and structural parameters affect the transient impact characteristics of the vehicle powertrain and its influence law,in order to provide theoretical guidance for the optimization and matching of the automotive powertrain.Firstly,taking a light commercial vehicle as the research object,based on the engine operating parameters and structural parameters,the crank linkage mechanism dynamics and the cylinder thermodynamic analysis,the theoretical analysis model of the simulated engine torque output characteristics was established,The dynamic torque simulation model of engine was built by Simulink simulation platform.And it used as the input excitation for the transient impact characteristics analysis of the automotive powertrain.Secondly,according to the principle of transmission system dynamics,a dynamic model of 15 degrees of freedom discretization transient impact characteristics considering the multi-gap problem of the transmission system was established.The calculation result of the engine dynamic torque model was used as its input excitation,and the driving resistance of the vehicle was used as the transmission system load.The AMEsim software was used to construct the simulation analysis model of the 15 degree of freedom transient impact characteristics of the automotive powertrain system,which lays a theoretical analysis foundation for the transient impact characteristics analysis of the automotive powertrain.Thirdly,according to the simulation analysis model of the 15 degree of freedom transient impact characteristics of the automotive powertrain,the transient impact characteristics of the transmission system under four typical torque abrupt conditions,such as clutch fast separation/engagement,emergency step on/loose accelerator pedal,were analyzed.The causes of transient shock characteristics was studied.and the simulation model and results were validated by real vehicle test.Finally,using the transient impact characteristic model of the automotive powertrain system,select the driven gear angular acceleration of the final as the evaluation index of the transient impact of the transmission system.The control variable method was used to compare and analyze the typical structural parameters of the transmission system such as transmission gear clearance,final gear clearance,torsional vibration damper stiffness and typical working conditions parameters such as clutch engagement speed and accelerator pedal change rate affect the transmission system transient impact characteristics. |
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