Gas compressor of the scroll type having reduced starting torque

Abstract

A gas compressor of the scroll type is disclosed wherein means are provided for reducing its degree of compression as it starts from a standing start in order to reduce the initial starting torque required. To this end, passage means are provided which extend through the end plate means of the compressor from a location in communication with the closed moving volumes defined between the wrap elements to a second location in communication with working gas normally at discharge pressure during operation of the compressor. Valve means are associated with the passage means for permitting flow therethrough when the pressure within the closed moving volumes exceeds the discharge pressure at said second location as the compressor starts from a standing start, and for blocking flow therethrough during operation of the compressor when discharge pressure normally exceeds the pressure in the closed moving volumes. In the preferred embodiment, the valve means comprise pressure responsive valve means operative to permit flow through the passage means when the pressure within the closed moving volumes exceeds the discharge pressure at the second location, and to prevent flow therethrough when the discharge pressure at the second location exceeds that within the closed moving volume. Preferably, the passage means comprise first and second individual passages, each having its own associated valve means.