| NW planetary gear transmission is used as a new type of reduction gear in electric wheel drive system,which greatly simplifies the driving form of the car.However,due to the limitation of the installation space of the hub and the force characteristics of the planetary transmission,it inevitably produces planets.The misalignment of the axle and the eccentric load of the gear directly affect the dynamic performance of the vehicle.In this paper,the NW planetary transmission of electric hub is taken as the research object.On the basis of analyzing its transmission principle and transmission system design,the meshing characteristics and dynamic characteristics of the transmission are studied to improve the meshing performance and reduce vibration noise of the transmission.Improving the service life has important theoretical significance and engineering application value.The main contents of the paper are as follows:(1)Based on the analysis of the structure of the electric hub system and the transmission principle of the NW planetary gear train,the transmission ratio relationship is derived.Considering the radial dimension limitation of the hub and the planetary transmission installation conditions,the planetary gear parameter limitation range is derived,the geometric parameter design and material selection of the gear transmission were carried out,and the static force analysis of the NW planetary transmission system was carried out,and the strength verification of the gear transmission system was completed.(2)Considering the structural flexibility of complex components,the meshing analysis model of the electric hub NW planetary transmission system is established by modern design method,and the gear meshing misalignment required for determining the micro-shaping parameters of the gear is calculated.A two-stage gear meshing sub-shaping scheme is proposed.The influence of working conditions and tooth shaping on the meshing characteristics of NW planetary transmission system is studied.The results show that the contact stress of the gear teeth is greatly reduced after the modification,the contact area is increased,the contact area is more reasonable,the peak-to-peak value of the transmission error is reduced,and the mean value of the meshing stiffness is reduced.As the load increases,the meshing impression increases and transmits.The peak-to-peak value of the error first decreases and then increases,and the stiffness of each mesh increases.(3)Considering the translation and the degree of freedom of the components around the axis,the finite element dynamics model of the NW planetary transmission is established by the system energy method,and the dynamic load sharing formula of the system is derived.Combined with the MASTA meshing analysis model,the system is solved.Dynamics input parameters,and the calculation of planetary axle torsion stiffness and damping and each meshing damping.(4)The influences of the dynamic meshing force,the load sharing characteristics,the offset between the planetary wheels and the bearing force of the planetary gears before and after the trimming and the peak torque load under the rated load and the peak torque load are studied.The results show that the modification improves the dynamic response of the system.The greater the torque load,the greater the fluctuation of the meshing force at medium and high speeds;the radial and tangential mean values of the offset between the planetary wheels increase,but the radial growth rate gradually slows down;the bearing force shows a linear increase trend.The degree of fluctuation first increases and decreases.When the medium-load is medium-speed,the bearing force fluctuates relatively. |
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