| 摘要 |
The 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), the hydraulic diameter of each oil return passage (530) is 5 mm or larger, and the ratio of the total area of the oil return passages (530) to the area of the virtual circle having the diameter equal to the maximum outer diameter of the stator core (510) is 5 to 15%. Thereby, the lubricating oil accumulated on the other surface (510b) side of the stator core (510) can be returned to an oil reservoir (9) through the oil return passages (530), and it can be prevented that the oil reservoir (9) is short of oil. Furthermore, the cross sectional area of the stator core (510) can be securely kept, and the motor efficiency can be maintained. |
