Abstract: A gas compressor includes a housing with suction and discharge ports, and a gas-compressing mechanism housed in the housing to compress a gas sucked through the suction port and discharge the compressed gas via the discharge port. The mechanism includes a cylinder defining a cylinder chamber with a circular or elliptical cross-sectional shape. The cylinder has a suction inlet and a discharge outlet. The suction inlet and the discharge outlet are opened in a peripheral wall of the cylinder chamber. A suction passage is formed along an outer periphery of the cylinder corresponding to a peripheral direction of the cylinder chamber. A discharge passage extends inside a thick portion of the cylinder along a center axis of the cylinder chamber. The suction inlet communicates with the suction port via the suction passage. The discharge outlet communicates with the discharge port via the discharge passage.

Abstract: To reduce an excessively high vane back pressure to an appropriate pressure to thereby relieve operational load, and to improve the vane projectability at the start and during low speed operation to thereby prevent chattering; There are provided back pressure spaces including the bottom portion of vane grooves and attaining a middle pressure between suction pressure and discharge pressure during normal operation of the compressor main body, a first high pressure oil passage establishing communication between an oil sump and the vane groove bottom portions when the vanes are in their discharge stroke positions, second high pressure oil passages establishing communication between the oil sump and the back pressure spaces, and an opening/closing valve for opening and closing the second high pressure oil passages.

Abstract: Disclosed is a gas compressor capable of preventing deformation of a filter used for separating oil contained in a compressed gas. The gas compressor includes a suction port, a suction chamber, a gas compressing portion, a compressed gas releasing portion provided in the gas compressing portion, a discharge chamber, and a discharge port. Provided in the discharge chamber is a filter for separating oil contained in the compressed gas. The filter is configured such that the outer peripheral portion of the filter is expanded peripherally upon its deformation caused when the force (dynamic pressure) of a jet stream formed by the flow of the compressed gas released from the compressed gas releasing portion and the force (static pressure) due to a difference in pressure between front and rear sides of the filter which is generated by the flow path resistance in the filter are applied to the filter whereby the force with which the filter is held in close contact with the filter installation portion is increased.