NVH Analysis And Optimization Of Power Coupling Mechanism Of Hybrid Electric Vehicle

As oil shortage and environmental issues are increasingly prominent,new energy vehicles become the inevitable trend of automobile industry.Due to limitation of battery technology and endurance mileage,electric vehicles can not be applied widespreadly.However,the hybrid electric vehicle(HEV)has become the best transition product because of its eco-friendly property and cruise duration.Power coupling mechanism is a key component of HEV,mainly responsible for power coupling,switching and delivering.Its dynamic performance has a great impact on powertrain and whole vehicle.This paper takes one type of power coupling mechanism as research object,dynamic characteristic and NVH performance in power switching process were discussed.The main research contents are as follows:1.Dynamic characteristics analysis.Based on the multi-body system dynamics theory and finite element method,rigid flexible coupling dynamic model of double planetary gear power coupling system was established according to constraint relation and contact relevant parameters.Then,time-frequency characteristics of gear meshing forces and bearing forces were analyzed.2.Vibration response analysis.Through the modal analysis by using ANSYS Workbench,natural frequency and mode shapes were obtained.By using bearing forces as boundary conditions,modal based vibration response of this housing was calculated,vibration displacement of housing surface was discussed.3.Radiated noise analysis.Based on acoustic theory and boundary element method,prediction model of noise radiation of housing was established by using LMS.Virtual.lab,which contained structure grid,acoustic grid and field point grid.Sound pressure levels of housing surface,filed point and sound power level were calculated.Then,acoustic transfer vector(ATV)method was used to identify the major acoustic panel contributor to sound power level.4.Optimal structural design for noise and vibration reduction.A new damping structure and stiffener structure was designed.Taking the thickness of basic layer,the thickness of damping layer and the height of stiffener as design variables,a new mathematical model with an objective of vibration acceleration level of housing surface was obtained by using K-S function and response surface methodology,which was solved by sequential quadratic programming stably,verified a good NVH performance of optimization structure.