Compressor

Abstract

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

1 . A compressor comprising:
 a closed container having an oil reservoir;   a compression element disposed within the closed container; and   a motor disposed within the closed container, the motor being arranged to drive the compression element via a shaft,   the motor including a stator core having a plurality of oil return passages extending through a first surface of the stator core located on a side closer to the oil reservoir than an opposite side and through a second surface of the stator core located on the opposite side, and   a hydraulic diameter of each of the oil return passages at the second surface of the opposite side of the stator core being 5 mm or larger, and a ratio of a total area of the plurality of oil return passages at the second surface of the opposite side of the stator core to an area of a virtual circle having a diameter equal to a maximum outer diameter of the stator core being 5 to 15%.   
   
   
       2 . The compressor as claimed in  claim 1 , wherein
 the stator core is disposed radially outside of a rotor of the motor, and   the oil return passages are located on an outer circumferential side of the stator core.   
   
   
       3 . The compressor as claimed in  claim 1 , wherein
 a refrigerant in the closed container is carbon dioxide.