Rotary compressor including a plurality of recessed portions for retaining lubricating oil

A rotary compressor comprising:

• a compressor housing that is provided with a refrigerant discharge portion and a refrigerant suction portion;
• a compression unit that is arranged in the compressor housing and configured to compress a refrigerant, which is sucked from the suction portion, and discharge the refrigerant from the discharge portion;
• and
• a motor that is arranged in the compressor housing and configured to drive the compression unit, wherein
• the compression unit includes an annular cylinder;
• an upper end plate that closes an upper side of the cylinder;
• a lower end plate that closes a lower side of the cylinder;
• a rotating shaft that is rotated by the motor;
• a piston that is fitted to the rotating shaft and is configured to revolve along an inner peripheral surface of the cylinder and form a cylinder chamber in the cylinder;
• and a vane that projects from a vane groove provided on the cylinder into the cylinder chamber and brought into contact with the piston so as to section the cylinder chamber into a suction chamber and a compression chamber,
• at least one end face of both end faces of the piston in an axial direction of the rotating shaft has formed therein an oil-film retention region having an array of a plurality of recessed portions that are configured to retain lubricating oil, and
• each of the plurality of recessed portions is not connected to an inner peripheral surface and an outer peripheral surface of the piston and formed in a linear shape having a bend portion, and arranged in a radial direction of the piston with a projecting end of the bend portion oriented in a circumferential direction of the piston.