Design And Research Of Two Stages Planetary Automatic Transmission Of Electric Vehicle

The number of global traditional fuel cars continues to grow every year,which brings convenience to people's travel,but also brings severe challenges to energy,environment and transportation.In order to improve the global environmental problems and ease the energy crisis,lots of countries in the world are actively in promoting research on technology of pure electric vehicle.This paper develops a two-speed planetary gear transmission which based on the school-enterprise cooperation project to improve the vehicle's power and endurance as much as possible and reduce the requirements of the vehicle.First of all,it briefly describes the domestic and international development of pure electric vehicles and the status of the development of transmission.According to the basic parameters of the model,determine the model of the selected driving motor and then according to the characteristics and cost of this research model vehicle transmission system,initially determine to enhance the electric vehicle's power and economy through the two-speed transmission and determine the transmission line to meet the upper and lower limits of the transmission conditions.In order to improve the performance of the entire vehicle further,the gear ratio of the two gears of the planetary gear transmission is optimized.And the optimization objective of the optimization algorithm is established by optimizing the power and economy of the entire vehicle.A multi-objective optimization function of the optimization algorithm is established.In order to solve the problem that the genetic algorithm converges to the local optimal in the optimization process,a simulated annealing algorithm is proposed to adjust the coefficients in the optimization process to satisfy the optimal iteration results.The simulated annealing genetic algorithm optimization program is written in MATLAB.After iterative optimization,the optimal transmission ratio of each gear is finally obtained.The planetary gear-type two-speed transmission is designed based on the advantages of planetary gear transmission.The gear ratios of each gear of the planetary gearbox are designed and calculated based on the gear ratios optimized by simulated annealing genetic algorithm.In order to realize the automatic shift function of the transmission,a worm-gear automatic shift mechanism is designed on the transmission structure.Based on the determination of the transmission parameters,a three-dimensional model of the transmission is established,and the dimension parameters of the key components of the transmission are determined.The parameters and model basis are provided for the finite element analysis.On the basis of determining the structure and parameters of the transmission,the virtual prototype model of the transmission is established by using ADAMS software.At the same time,the longitudinal dynamics,the motor,the battery,the main decelerator and the shifting model of the transmission are established on the basis of the Matlab/Simulink environment,The simulation results of the transmission virtual prototype model and the whole vehicle model show that the selection of the parameters of the designed transmission and other parts can meet the dynamic and economic requirements of the whole vehicle,and the automobile transmission ratio is improved obviously after the optimization of the economic performance and the dynamic performance.The key components of the planetary gear transmission,planetary gear,planet carrier,and the main reduction gear finite element modeling.Determine the key components of planetary gear transmission processing materials,and then to determine the material properties of the parts to determine the finite element analysis of the boundary conditions.In order to check the root strength of transmission gear tooth,the finite element analysis of root flexural strength is carried out according to the maximum torque of the motor in actual work.According to the analysis results,the maximum bending stress of gear tooth root less than the maximum allowable material stress,is meeting the strength requirements.