Rotary displacement compressor having a check valve and a backflow control valve arranged in series through a discharge pipe

A rotary displacement compressor comprising:

• a compressor body that compresses a medium by reducing a volume of the medium using rotation;
• a discharge pipe through which a compressed medium, which is discharged through a discharge port of the compressor body, flows;
• a check valve that shuts off the compressed medium flowing backward to the compressor body;
• and
• a backflow control valve that allows a predetermined rate of the compressed medium to flow backward,
• wherein the check valve and the backflow control valve are disposed in series via the discharge pipe,
• wherein the backflow control valve is a ball type backflow control valve, and
• wherein the check valve is located closer to the compressor body than the backflow control valve;
• a first aftercooler disposed between the discharge port of the compressor body and the check valve to cool the compressed medium discharged through the discharge port;
• and
• a second aftercooler disposed between a discharge port of the check valve and the backflow control valve.