| With the increasingly prominent world environment and energy problems,the speed of automobiles moving towards electrification,intellectualization and lightening is obviously accelerating.In the development of vehicle electrification,the hub motor driven electric vehicle has attracted the attention of automobile and academic sessions due to its advantages of high transmission efficiency,low space utilization and good dynamic controllability.However,the introduction of hub motor and deceleration mechanism increases the vehicle’s non sprung mass.Meanwhile the dynamic excitation of the transmission parts further worsens the vertical vibration of the whole vehicle,which makes the ride comfort and maneuverability of the vehicle worse.Therefore,the following research is carried out on the deceleration driven hub motor with deceleration mechanism:Firstly,a selection analysis of driving system of main components is finished.The nonlinear dynamics model equation for the planetary gear reduction mechanism has been established in order to analysis the load sharing transmission performance of different floating forms of speed reducer under the internal and external excitation.Furthermore,the 3D models of different floating forms reducer are built in UG and the gear meshing force are solved to calculate the load sharing coefficient combined with dynamic software ADAMS.Then,Some vehicle ride comfort indexs including motor body vertical acceleration,vertical acceleration,suspension dynamic deflection and relative dynamic load of wheel are definied based on the two degree of freedom 1/4 vehicle model according to the existing vehicle parameters.The systematic analysis about the the influence of design parameters on vehicle performance are made by means of the amplitude frequency characteristics and response RMS value of those indexs.In order to analysis the impact of planetary gear transmission components,a vertical vibration equation of 25 degrees of freedom considering the planetary gear transmission effect is established combined with planetary gear dynamics model.The the effects of different speeds,different road excitation,the backlash,the motor speed input on load performance of the planetary gear transmission is analyzed in detail.At the same time,the effects of related parameters on the vehicle ride comfort index is studied based on the vibration equation.Further,in order to improve the transmission stability and the service life and reduce the unsprung mass,the dynamic optimization and lightweight design of planetary reducer is carried out combined with genetic algorithm.The volume of multiobjective optimized reducer is reduced by 2.81%,the average load coefficient is decreased by 8.56% while the reduction ratio is increased to the 7.26.The simulation of reducer optimized under road excitation showed that it has better transmission load sharing properties.An active suspension fuzzy PID controller is designed for the further improvement of other indexes of ride comfort.The fuzzy rules are optimized by genetic algorithm.The simulation results showed that the optimized fuzzy PID control strategy can simultaneously make the peak value of the body vertical vibration acceleration,vertical vibration acceleration of the motor,suspension dynamic deflection and wheel dynamic load decrease 38.51%,38.63%,28.95% and 31.32% respectively,and the vertical RMS value of vehicle body and the motor is reduced by 36.24% and 37.74% respectively.The effectiveness of the control strategy is verified by simulation.The research results and theoretical analysis of this project have certain engineering reference value for the structural design and optimization of the hub motor drive system and the improvement of the vertical dynamics performance of the electric vehicle. |
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