Development of Commercial Vehicle E-Axle System Based on NVH Performance Optimization

With the continuous development of various technologies in the field of electric vehicles, more and more mature products are put into the market. Among them, electric commercial vehicle has been supported by many preferential policies because of its wide use and high energy utilization and has developed rapidly in recent years. At present, the electric drive-train systems of commercial vehicles can be divided into motor direct drive, integrated el-axle and distributed e-wheel drive. The first type only uses motor to replace the engine, and the other parts have little change. This method has low transmission efficiency and loose structure, which is a temporary transition scheme. The drive types of integrated E-axle and distributed E-wheel have their own advantages and disadvantages, which way to become the mainstream of the future have not yet been decided.

This research is based on the development of an electric commercial vehicle integrated axle system, in which the NVH performance is the most important consideration index. Firstly, the dynamic vibration theory of gear system was studied. Then the systematic engineering analysis is carried out to determine the basic layout of E-axle according to the vehicle parameters. The key design issues such as transmission ratio, center distance and bearing types were determined and optimized according to the system emerging analysis. The NVH performance of the designed E-axle was first evaluated through simulation approach. The transmission error, natural frequency and vibration response of the designed E-axle were calculated and analyzed. Then the meshing performance of gears is optimized by micro-modification of gears. The design and development of housing is based on structural stiffness and modal optimization. After the optimization design, the dynamic response of the E-axle assembly under the actual working conditions is evaluated and analyzed, in which the whine and resonance are adopted as the risk aversion items. Finally, the designed sample is validated by bench test and vehicle test.

The results of this study, which have strong practical guiding significance, can be used as a reference for the design and development of E-axle.