Compressor having functions of discharge interruption and discharge control of pressurized gas

In a compressor including a housing formed therein with an internal space, a suction port and a discharge port;

• and a gas pressurizing member movably received within said internal space of said housing, wherein during moving said gas pressurizing member has at least part of surfaces thereof cooperating with inner wall surfaces of said internal space to define a pumping chamber in which said suction port and said discharge port open,
• the improvement wherein said housing further comprises:
• at least one volume control chamber having a substantial internal volume relative to the internal volume of said pumping chamber in said internal space of said housing, said at least one volume control chamber being located in the vicinity of said discharge port;
• first port means communicating said at least one volume control chamber with said pumping chamber;
• second port means communicating said at least one volume control chamber with said suction port;
• a valve received within each of said at least one volume control chambers;
• and
• control means coupled to and controlling said valve such that said valve selectively assumes any one of first, second and third predetermined positions in its respective volume control chamber irrespective of a driving state of said pressurizing member;
• wherein said valve at said first position thereof is disposed to close both said first port means and second port means so that said pressurizing member performs a compression action with a normal compression ratio, said valve at said second position thereof being disposed to open said first port means and close said second port means to increase by a substantial amount the compression volume of said pumping chamber, whereby said pressurizing member performs a compression action with a reduced compression ratio and a consequently reduced discharge flow rate, and said valve at said third position thereof being designed to open both said first port means and said second port means so that no compression action is performed by said pressurizing member.