Scroll type compressor

In a scroll type compressor having a stationary scroll member and a revolving scroll member, each of said scroll members having spiral elements which engage with one another to form a compression space having a volume which is reduced upon movement of said revolving scroll member around said stationary scroll member, said stationary scroll member having an end plate formed with a discharge port in communication with said compression space whereby fluid drawn into said compression space under suction from an inlet space of said compressor is compressed by a reduction in volume of said compression space and discharged through said discharge port, said end plate having a bypass hole in communication with said compression space for bypassing fluid under compression to said inlet space, and the opening of said bypass hole being adjusted by a piston valve to control the discharge quantity of said compressor, wherein the improvement comprises:

• a plurality of additional bypass holes for bypassing fluid under compression to said inlet space when said holes are open, said additional bypass holes being respectively at positions along the spiral element of said stationary scroll member for which the compression volumes in said compression space as related to the revolving angle of said revolving scroll are at predetermined percentages, one of said additional bypass holes being positioned substantially at the innermost point of said spiral element in the vicinity of said discharge port, and piston valve means operable to adjust the opening of said bypass holes thereby to control the capacity of said compressor by an amount within the range of 100% to 0% of discharge quantity and permit continuous operation of said compressor over load fluctuations.