Research On Interference Fit Between Motor Stator And Housing Used In Pure Electric Bus Based On Temperature Rise

In order to solve the problem of environmental pollution and energy shortage,the world tries its best to develop new energy automotive industry.As a low-carbon city bus,pure electric bus can relief the pressure of urban traffic,reduce carbon emissions and save energy to a certain extent.As one of the core components of pure electric buses,the temperature rise of the drive motor has been kept experts and academics concerned.At the same time,the complex temperature rise characteristic of the motor causes to increase or decrease the actual interference amount between the motor stator(ie,the stator core)and housing during the operation of the motor.Therefore,it is necessary to establish a method of the interference selecting between the motor stator and housing based on the temperature rise,to provide guidance for the structural connection design of the motor.In order to grasp the characteristics of temperature rise of motor,this paper took a permanent magnet synchronous motor used in pure electric bus as an example.The boundary condition of temperature field was determined,the thermal simulation model of the motor was established,and the transient temperature field of the motor under rated condition and peak condition was obtained.In order to verify the reliability of the simulation of the temperature field,the temperature rise experiment platform was built.The results show that the simulation errors of temperature field under rated condition and peak condition do not exceed 5%,which proves that the thermal simulation model is accurate and reliable.In order to study the effect of temperature rise on interference of stator and housing,firstly,the linear expansion coefficient of the stator and housing's material was measured,and the relationship between the linear expansion coefficient and temperature was obtained;secondly,this paper analyzed the characteristics of the interference between the stator and housing under the environment temperature,rated condition temperature and peak condition temperature,which shows that when the initial amount of interference is 0.355mm(25?),the maximum reduction effect of the amount of interference is-0.158 mm and the maximum increase effect is 0.220 mm during the operating of the motor.Through the simulation analysis of the interference fit between the stator and housing,the minimum amount of interference to meet the requirements of load transfer is determined to be 0.087 mm,and the maximum amount of interference to meet the strength requirements is determined to be 0.806 mm.Combined with the effect of temperature on the amount of interference,the maximum reduction effect on the amount of interference was compensated,and the maximum increase effect on the amount of interference was removed.Then the effective minimum interference amount is determined to be 0.245 mm,the maximum effective interference amount is determined to be 0.586 mm.The interference rule between stator and housing was chosen to be H7/u6,whose minimum interference amount is 0.297 mm and the maximum interference is 0.390 mm.Finally,simulation and experimental verification were carried out on the selected interference,and the results show that the selected interference amount is safe and reliable.