Inlet Placement Influence on Thermal Performance of an Oil-Cooled Traction Motor

Direct oil cooling represents an enabling technology to increase the power density of electric motors and guarantee their integration with the transmission, ensuring a compact design of the electric drive unit. Oil feeding has an impact on oil distribution within the machine but also on packaging. In this paper, three inlet designs in two possible configurations are presented and compared, both in transient and steady state conditions, using Moving Particle Simulation (MPS) and finite element (FE) Computational Fluid Dynamics (CFD) approaches. In transient conditions, the flow distribution is affected by the specific design while, for all configurations, the position of the inlet affects the homogeneity of the oil filling. The steady state velocity analysis confirms the transient flow distribution trend. In addition, gravity has no effect on flow distribution. Pressure drop and HTC values are also reported for the completeness of the analysis. Finally, the paper provides some guidelines for the inlet design.