Research On Lightweight Of Electric Drive Axle Housing For City Logistics Vehicle

With the rapid development of new energy vehicles,the electric city logistics vehicle has become an important vehicle of pure electric vehicles.The market share of multi-speed electric drive axles is gradually increasing.In view of the current problems related to electric drive axles,it is extremely important to carry out structural design and lightweight design of electric drive axles to meet the needs of users.This article is based on the key technology research and development project of Jilin Province Science and Technology Development Plan "Urban Logistics Vehicle Electric Drive Axle Development and Intelligent Control Key Technology Research"(No.20180201060GX),Taking the electric drive axle of city logistics vehicle as the research object,the structure design,simulation analysis and lightweight research are carried out for the electric drive bridge.The main research is as follows:A new configuration of the three-speed electric drive axle is proposed,and the parameters of the components of the electric drive axle transmission system are matched and optimized.The design adopts an overall arrangement,and the three-speed transmission structure is designed by comparing the characteristics of each shifting mechanism.Parameter matching design needs to meet the requirements of vehicle dynamics,to define the parameters of various parts of the vehicle,to determine the motor parameters and to select the corresponding motor,to analyze the driving conditions and requirements of the urban logistics vehicle,and to match its transmission system parameters.In order to reduce the impact of shifting and take into account the needs of power and economy,the third gear transmission ratio is optimized on the basis of determining the maximum and minimum transmission ratios.Finally,according to the design parameters,the design of the transmission system and the electric drive axle is modeled,and the preliminary design of the electric drive axle housing structure is obtained.In four typical operating conditions,the stiffness and strength analysis and modal and fatigue analysis of the three-gear transverse integrated electric drive axle are carried out,and it is verified that the electric drive axle housing meets the design standards.Performing simulation pre-processing on the bridge shell,simplifying its chamfering,bolts and other structures,and using the combination of tetrahedral mesh and hexahedral mesh for mesh division.According to the overall driving conditions of the axle housing,the axle housing working conditions are simplified into four typical working conditions.Under these four typical working conditions,to combine with the parameters of urban logistics vehicles,the force analysis of the axle housing of the electric drive axle is carried out,and the structural reliability of the electric drive axle is verified for the four working conditions.Finally,the fatigue analysis of the three-gear transverse integrated electric drive axle is carried out through the cycle conditions,and its reliability is verified.This design combined response surface optimization analysis and topology optimization to carry out lightweight research on the electric drive axle.The lightweight method of the electric drive axle is analyzed,and different light-weight methods are adopted for different parts of the axle housing.Response surface optimization design is adopted for the half-shaft casing to constrain its minimum thickness,to constrain the maximum strain and maximum stress of the axle housing,so that the maximum value is not exceeded during the calculation process.The calculation results show that as the thickness decreases,the maximum stress and strain gradually increase,and the width of the rectangular section has a greater influence on the axle housing than the length on the axle housing.Finally,the optimal thickness of the semi-axial casing is obtained.The topological optimization design of the middle part of the electric drive axle housing is carried out,and the variable density method is used to optimize the method to reduce the weight of the housing.The structure of the middle part of the electric drive axle is improved according to the topology optimization results.The results of lightweight were analyzed and compared.According to the above lightweight design model,the stress concentration in some parts of the drive axle is improved and thickened appropriately in the larger stress area.A comparative analysis is made between the lightweight and optimized axle housing and the original threebaffle horizontal integrated electric drive axle housing.The weight of the axle housing is reduced by about 11%.