Separation of lubricating oil from refrigerant gas in a reciprocating compressor

A motor compressor unit comprising:

• compressor means for compressing a vapor;
• motor means for driving the compressor means and including a rotatable rotor located thereabove;
• a vertical drive shaft disposed substantially along the vertical centerline of the rotor and connecting the rotor and the compressor means;
• a shell encapsulating the compressor and motor means;
• a reservoir of lubricating oil located at the bottom of the shell;
• means including an axial passage formed in the shaft for conducting oil from the reservoir to upper portions of the shaft;
• passage means for conducting compressed vapor upward from the compressor means through the motor means wherein lubricant from the shaft becomes entrained with vapor conducted therepast, and wherein rotation of the rotor throws entrained lubricant radially outward, forming a substantially oil free space extending upward from the rotor;
• a discharge tube extending through the top of the shell in communication with the oil free space for conducting vapor therefrom;
• and
• a substantially unrestricted vapor flow path extending upward within the oil free space from the top of the rotor to the discharge tube.