Research On Cooling Method Of In-wheel Motor Based On Impinging Jet

The development of high power density,high overload capacity and miniaturization of in-wheel motor is restricted by the temperature rise.Too high temperature rise will seriously affect the operation efficiency,reliability and service life of the motor.Therefore,it is urgent to find more effective heat dissipation methods and measures to suppress the temperature rise of the motor,so as to improve the operation stability and prolong the service life of the motor,the application of impinging jet cooling to the heat dissipation of in-wheel motor is proposed and preliminarily explored.(1)Analyzes the temperature field and heat transfer mode of the in-wheel motor,discusses the influence of the calculation parameters on the numerical simulation results of the impinging jet and select the best parameter.Several commonly used turbulence models are calculated respectively,and the most suitable turbulence model of the impinging jet is determined by comparing with the experimental data in the previous literature.The calculation results show that the k-kl-w three equation model is in the best agreement with the experimental results.Based on the correct numerical simulation of impinging jet,the effects of impinging Reynolds number,impinging height and nozzle shape on the heat transfer efficiency were studied by changing the flow parameters.The results show that the greater the impinging Reynolds number,the better the heat transfer effect on the wall,and the best heat transfer efficiency can be achieved when the impinging distance H/D = 2.(2)In this paper,the impinging jet cooling is applied to motor cooling and its temperature field is calculated.Firstly,the heat source is determined,the loss mechanism of motor is analyzed and the motor loss is calculated,and the heat generation rate of heat source is determined by selecting the appropriate operating point.Secondly,the equivalent and simplified motor model is used to determine the equivalent heat conduction and heat transfer coefficient of each part which can not be calculated directly.Finally,the calculation based on impinging jet is proposed.Taking the winding as an example,the calculation results show that the maximum temperature of the winding can reach 408 K under natural convection,355 K under impinging jet cooling condition,and the temperature rise is reduced by 53 K.(3)The influence of several parameters on the motor cooling effect is explored.The results show that with the increase of cooling gas mass flow,the winding temperature decreases continuously,but the decreasing trend area is gentle when it increases to a certain limit;when the impact Reynolds number is fixed,the cooling effect of different orifice nozzles on the motor is not significant.(4)Presents an integrated system of pneumatic mode switcher and impinging jet cooling for the prototype vehicle.The pressure reducing valve and the actuator of mode switching are modeled and analyzed.The results show that the actuator can complete the mode switching action in about 0.2s under the given pressure.The research shows that the cooling method based on impinging jet is expected to be used in the design of cooling system of in-wheel motor,but it needs to be further integrated with the structure design of in-wheel motor and further experimental verification.