| 摘要 |
A stator core 510 of a motor 3 has a plurality of oil return passages 530 extending through one surface 510a and the other surface 510b of the core. On the other surface 510b of the stator core 510, a hydraulic diameter of each oil return passage 530 is 5 mm or larger, and a ratio of a total area of the oil return passages 530 to an area of a virtual circle having a diameter equal to a maximum outer diameter of the stator core 510 is 5 to 15%. Thereby, lubricating oil accumulated on the other surface 510b side of the stator core 510 is returned to an oil reservoir 9 through the oil return passages 530, and shortage of oil in the oil reservoir 9 is prevented. Furthermore, a cross sectional area of the stator core 510 can be securely kept, and motor efficiency is maintained. |
