Analysis of flow field in the motor-reducer assembly with oil cooling under real driving conditions

The oil flow field in the motor-reducer assembly was investigated under real driving conditions to estimate the cooling performance and oil circulation. The flat, uphill, downhill, right-turn, and left-turn conditions were selected as driving conditions. First, to estimate cooling performance, the oil coverage on coil and churning phenomenon were analyzed. The downhill condition had the strongest effect of churning phenomenon, and the average temperature under this condition was 121.5 °C. Furthermore, to estimate oil circulation, oil transport between the motor and the reducer was analyzed. Under the left-turn condition, an insufficient amount of oil reached the outlet, and the flow rate of the oil pump was limited to 8.1 LPM at the oil temperature of 50 °C under the 10 LPM condition. This study provides important information about the oil flow field in the motor-reducer assembly under real driving conditions to improve cooling performance and oil circulation of EVs.