Rotary compressor with oil relief passage

摘要

A rotary compressor for helium gas has a cylinder defining a closed space therein, a rotor disposed in the closed space for eccentric rotary motion while making a sliding contact with the inner peripheral surface of the cylinder, and a blade slidably mounted on the cylinder and resiliently projected into the closed space for sliding contact with the rotor so as to divide the closed space into a suction chamber and a discharge chamber. The compressor further has an oil relief passage which is arranged to allow the discharge chamber to communicate with a space outside the discharge chamber in the final stage of the discharging stroke before the crank angle of the compressor reaches an angle corresponding to the position of a discharge port.