Vibration Characteristic Analysis Of High Speed Helical Gear Transmission System In Electric Vehicle

With th,e increasingly serious energy and environment problems,new energy vehicles have attracted much attention.Electric vehicles(EVs)have broad development prospects due to they have great advantages in environmental protection and intellectualization.In the powertrains of EV,the form of single motor focus is most widely used.In this powertrain,the motor directly inputs the reducer at a higher speed,which brings many problems.Therefore,it has great significanc.e to systematically study the vibration characteristics of EVs gear transmission at high speed.This paper starts f-rom the following aspects:(1)The time-varying meshing stiffness of a high-speed helical gear drive of an EV was calculated by three method,the method of material mechanics,the method of finite element and the method of improved loaded tooth cont.act analysis(LTCA),and the results of th,e three method’s were compared and analyzed.(2)The impact time was obtained by using the geometry of out-of-line meshing impact,and the meshing impact velocity and the amplitude of meshing impact force were calculated according to the impact mechanics model.Finally,the impact force curve was obtained based on the above calculation results.(3)The bending-torsion-axis coupling dynamic model of single-stage helical gear transmission was established.The vibration characteristics of single-stage high-speed helical gear transmission were studied unde:r three kinds of excitation conditions,excitation of time-variable meshing stiffness,excitation of meshing impact and excitation of both of them.And the influence of two excitations on the system vibration at high speed was compared.(4)The dynamic analysis model of two-stage helical gear transmission was established.And the complex phenomenon that the vibration of the two gear pairs has mutual effect was analyzed in the two-stage helical gear transmission.The main difference of vibration characteristics between two-stage helical gear transmission and single-stage helical gear transmission was discussed.(5)The tooth surface modification of a high-speed helical gear transmission of an EV was carried out in Romax software.Then,the vibration reduction effect of tooth surface modification on single-stage helical gear transmission was analyzed.Finally,the vibration reduction effect of two-stage helical gear transmission was compared under two kinds of tooth surface modification,the modification of input gear pair and the modification of output gear pair.