Patent ID: 8435017

Claim:
A hermetic type compressor comprising an electrical element and a compression element driven by the electrical element in an hermetic vessel, the compression element including a cylinder block with a compression chamber space, a piston that reciprocates in the compression chamber space, and a valve plate being arranged at an end of the compression chamber space and forming a compression chamber with the piston, the valve plate including a suction port to which gas to be compressed in the compression chamber flows in and a discharge port from which gas compressed in the compression chamber is discharged, wherein a projection that appears from the discharge port with the reciprocating movement of the piston is arranged at a distal end face of the piston and at a position facing the discharge port, the projection includes a flat surface formed at a side surface of the projection, extending substantially parallel to a reciprocating direction of the piston and facing an axial center side of the piston, the discharge port is formed as a circle, and a cross-sectional area of the discharge port becomes continuously greater from a surface of the valve plate on the compression chamber side towards an opposite surface of the valve plate on an outside of the compression chamber.