HERMETIC SCROLL COMPRESSOR WITH PRESSURE DIFFERENTIAL CONTROL MEANS FOR A BACK-PRESSURE CHAMBER

摘要

A hermetic scroll compressor having a motor-driven compressor unit mounted in a hermetic housing and constituted by a scroll compressor section and a driving electric-motor section which are drivingly connected to each other through a rotary shaft supported by a bearing on a frame fixed in the housing. The scroll compressor section has a stationary scroll member and an orbiting scroll member having meshing wraps for defining compression chambers therebetween. The pressure of the fluid under compression is introduced into a back pressure chamber formed behind the orbiting scroll member so as to produce an axial thrust which presses the orbiting scroll member onto the stationary scroll member. A lubricating oil collected in the bottom portion of the hermetic housing is sucked up and delivered through a passage formed in the rotary shaft by the pressure differential between the high discharge pressure and the intermediate pressure acting in the back pressure chamber. In order to ensure the safe supply of the lubricating oil regardless of the operating condition of the compressor, a control valve device is provided for selectively establishing a communication between the suction side of the compressor and the back-pressure chamber.