Abstract: In a high side, vertical, twin cylinder rolling piston hermetic compressor, a portion of the high pressure gas is diverted from the chamber defined by the lower muffler and the pump bearing to the axial bore of the crankshaft. The crankshaft extends into the oil sump such that rotation of the shaft produces a pumping action for pumping oil from the sump to structure requiring lubrication. Additionally, the flow diverted from the chamber to the axial bore produces a jet pump effect which supplements the pumping action produced by the rotating shaft, particularly at low speed.

Abstract: In a high side rotary compressor, interior shell pressure is used to force lubricant from the sump into the compression chamber. The lubricant is delivered only after the suction port has closed and before chamber pressure exceeds shell pressure.

Abstract: In a high side rotary compressor, liquid refrigerant is supplied to is to the compression chamber via a capillary tube and liquid injection port. The lubricant is delivered only after the suction port has closed and before chamber pressure exceeds the liquid injection supply pressure.

Abstract: The profile of the valve stop of a discharge valve conforms to the maximum bending stress or the maximum allowable fatigue stress whereby impact of the valve element with the valve stop occurs when the valve element has the least kinetic energy and highest potential energy such that the least possible kinetic energy is transferred to the valve stop.

Abstract: In a horizontal rotary compressor the gas path from the muffler is between the rotor and stator whereupon the flow direction is changed 180.degree. and the flow takes place between the stator and the upper shell. Oil drainage to the sump is in a flow path between the stator and the lower shell. The gas and oil paths serve to cool the rotor and the stator windings. Also, the gas flow reduces oil circulation from the compressor.