Optimization Design And Reliability Analysis Of The Planetary Gear Mechanism For Automatic Transmission Of Electric Vehicles

In order to solve the problems of lack of oil resources and serious environmental pollution,people are stepping up the research and development of new cars with energy saving and environmental protection.Electric vehicle has become the direction of automobile industry because of its advantages of clean energy,zero pollution,simple structure and easy operation.In order to promote the long-term development of electric vehicles,electric vehicles need to install a new type of automatic transmission.Therefore,according to the design requirements of the automatic transmission for electric vehicles provided by the manufacturers,a new type of planetary gear type three gears automatic transmission is studied.Firstly,according to the electric vehicle parameters,dynamic performance parameters and the design requirements of three gear transmission ratios,the driving motor of electric vehicle is selected.Referring to the two gear NGW planetary gear train provided by the manufacturer,and according to the design requirements of a gear transmission ratio,referring to the machine design manual,one gear NGW planetary gear train parameters are selected and one gear transmission ratio is determined.Secondly,based on the parameters of the two gear planetary gear trains of the electric vehicle,the two gear planetary gear trains model was plotted by SolidWorks,and the static contact analysis was carried out by ABAQUS finite element software.The ADAMS software is used to simulate the drive of the two gear NGW planetary gear trains,and the load spectrum of the meshing of the two gear planetary gear trains is obtained.Based on the results of statics analysis and the load spectrum obtained from the ADAMS simulation,the fatigue life cycle number of the two gear planetary gear is calculated by the fatigue analysis software nCode DesignLife,and the fatigue life of the two gear planetary gear trains is verified to meet the design requirements.Then,Ansys Workbench software is used to check the torsional strength of the two gear planet carrier,which is in line with the design requirements.Meanwhile,taking the maximum equivalent stress and total mass of the two gear planetary carrier as the objective function,taking the structural parameters as design variables,the Ansys Workbench optimization toolbox is used to optimize the two gear planet carrier by response surface method,which saves material consumption.Finally,using the fmincon function in the Matlab toolbox,the objective function of the two gear planetary gear’s minimum volume and the coincidence degree is taken as the objective function,and the concentric condition of the planetary gear as the constraint condition,the multi-objective optimization of the two gear planetary gear train is carried out.The optimization results show that the automatic transmission of the electric vehicle is compact and the cost is reduced.In addition,The increase of the coincidence degree makes the load-carrying capacity of the automatic transmission higher and the transmission more stable.Based on the parameter design,reliability analysis,fatigue prediction and optimization design of the planetary gear mechanism of electric vehicle,this paper provides a theoretical basis for the design and manufacture of the new automatic transmission of the new electric vehicle in the future.