Oil pump for a hermetic compressor

Abstract

A hermetic motor compressor unit for household and similar refrigeration appliances, comprising a sealed casing having a bottom that forms a sump for holding lubricating oil. Inside of the casing is a compressor and driving motor that share a common hollow crankshaft that rotates about a vertical axis. To ensure effective lubricating oil flow into the hollow crankshaft, a means for providing suction comprising a sleeve is rigidly fixed to the lower end portion of the crankshaft. A fluted member made of a material with a lower thermal conductivity than the material from which the hollow crankshaft is made that is connected to the stator of the drive motor is inserted into the sleeve to draw the lubricating oil from the sump. The lubricating oil is drawn in from the oil sump into recesses in the fluted member when the sleeve is rotated into the position in which it allows the recesses to communicate with lower apertures in the sleeve. This occurs during the downstroke of the fluted member. When the sleeve is then rotated by an angle of approximately 90° with respect to the above mentioned position, the oil is able to flow from the recesses through the upper apertures into the hollow crankshaft during the upstroke of the fluted member.