| Hybrid electric bus is an important part of new energy commercial vehicle in China.Among all kinds of new energy commercial vehicles,the market share of planetary hybrid electric bus is increasing gradually.Because of the excellent fuel economy of planetary hybrid electric bus,it has developed well in recent years.However,with the expansion of the promotion scope of planetary hybrid electric bus,the new system configuration gradually exposes the new torsional vibration problem,which reduces the comfort and ride experience of passengers.In addition,planetary hybrid electric power system is a kind of multi-power source coupling system,the nonlinear dynamics of planetary gear mechanism and the rapid response characteristics of the motor may worsen the torsional vibration of the transmission system,which is bound to affect the safety of the vehicle and the driving performance.It can be seen that the torsional vibration of planetary hybrid electric bus transmission system has become an important factor restricting its development and promotion.It will provide important guarantee for the development of planetary hybrid bus to deeply study the torsional vibration characteristics of the transmission system and explore the optimization method and rule to reduce the torsional vibration of the transmission system.Based on the dynamic modeling of the current driveline and response characteristics of torsional vibration in-depth investigation and analysis,this paper conducts the torsional vibration mechanical modeling of planetary hybrid electric bus transmission system,analyzes the torsional vibration characteristics of the driveline through the simulation of the inherent characteristics and forced vibration,and analyzes the optimization scheme of the driveline torsional vibration with the aim of vibration avoidance and reduction.The main research includes:Firstly,based on the configuration characteristics of planetary hybrid structure,the structural design of gears and other key components is completed by combining the design standards of parts size and structure.The centralized mass method is used to establish the mechanical model of torsional vibration of the transmission system,which provides an accurate model basis for the analysis of inherent characteristics and the simulation of forced vibration.Secondly,based on Alembert’s principle and Lagrange equation,the dynamic model of each component assembly is established to solve the non-damping free vibration equation of the transmission system.By means of natural frequency and mode shape,the inherent characteristics of torsional vibration are analyzed,and the relative degree of torsional vibration of each component under natural frequency is analyzed.The relationship between the main harmonic order of the engine torque and the resonant frequency is determined by solving the critical speed of the engine.Thirdly,based on the interactive modeling method,the driveline 3d model and the virtual prototype model are established.Through the forced vibration simulation,the vibration degree and vibration law of each component and assembly under different excitation are analyzed,and the resonance frequency of each degree of freedom is determined.Moreover,the paper analyzes the modal participation factors of each part of the driveline and explores the influence of the modal frequencies on the forced vibration of the driveline.Finally,aiming at the vibration absorption and vibration reduction,the sensitivity of the parameters based on response is studied.The influence of structural parameters on the natural frequency of the system is investigated by means of vibration isolation method.The torsional vibration amplitude of each component under the forced vibration of the drive train is analyzed by the vibration reduction method,and the parameter optimization direction of passive vibration damping is obtained. |
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