Rotary compressor with capacity modulation

Claim 1

In a rotary compressor of the type including a cylinder block having therein a cylinder having a vertical axis, upper and lower bearing members having flanges with radially extending surfaces closing upper and lower ends of said cylinder, a suction port opening into said cylinder for introducing therein gas to be compressed, a rotor mechanism rotatable within said cylinder for compressing said gas, a discharge port extending from said cylinder for discharging therefrom the compressed gas, and means for changing the compression capacity of said compressor, the improvement wherein said means comprises: an opening formed in said flange of one of said bearing members, said opening extending from the respective said radially extending surface into said flange in a depth direction parallel to said axis, and said opening facing a portion of the respective said end of said cylinder and a portion of a respective end surface of said cylinder block; a slide wall member mounted within said opening for sliding movement in opposite directions at right angles to said axis between a first position, whereat the slide wall member opens communication between said opening and said end portion of said cylinder, and a second position, whereat said slide wall member blocks communication between said opening and said end portion of said cylinder; spring means mounted within said opening for biasing said slide wall member in a first said direction to said first position; a control port extending into said opening at a location on a side of said slide wall member opposite said end portion of said cylinder; and valve means for selectively introducing into said control port compressed gas from said discharge port, thereby sliding said slide wall member in said opening in a second said direction opposite the force of said spring means to said second position, thus blocking communication between said cylinder end portion and said opening and providing a relatively larger compression capacity of said cylinder, and for selectively interrupting introduction into said control port of compressed gas from said discharge port, whereby said spring means slides said slide wall member in said opening in said first direction to said first position, thus opening communication between said cylinder end portion and said opening and providing a relatively smaller compression capacity of said cylinder.