Rotary vane compressor having pressure-biased vanes

A rotary vane compressor comprising:

• a cylinder having a compartment therein defined at least in part by an inner wall of the cylinder, and a pair of end portions connected to and closing the opposite ends of the cylinder;
• a rotor rotationally driven during use of the compressor and mounted to undergo rotation within the cylinder compartment, the rotor having a plurality of angularly spaced radially extending slots, and shaft portions protruding axially outwardly from opposite ends of the rotor and extending into openings formed in the cylinder end portions, the rotor and rotor shaft portions being rotatable relative to the cylinder end portions;
• a plurality of vanes slidably disposed within respective ones of the rotor slots so as to slidably extend therefrom and retract thereinto during rotation of the rotor, the vanes having base portions slidably received within the rotor slots and tip portions which make slidable contact with the cylinder inner wall during rotation of the rotor thereby dividing the cylinder compartment into plural expansible working chambers which alternately increase in size as the vanes slidably extend from the rotor slots to define a suction stroke and decrease in size as the vanes slidably retract into the rotor slots to define a compression stroke during rotation of the rotor;
• means defining a gas inlet opening at the upstream end of each working chamber for admitting therein a gas to be compressed during the suction stroke;
• means defining a gas outlet opening at the downstream end of each working chamber for discharging therefrom gas compressed in the working chamber during the compression stroke;
• and means for applying hydraulic pressure at a relatively lower pressure level to the vane base portions whenever the vanes are rotated into the regions of the gas inlet openings and continuously thereafter throughout the suction stroke and for a major part of the compression stroke to urge the vanes radially outwardly and thereby urge the vane tip portions into sliding contact with the cylinder inner wall during rotation of the rotor and for applying hydraulic pressure at a relatively higher pressure level to the vane base portions whenever the vanes are rotated into the regions of the gas outlet openings and continuously thereafter at least until the vanes are fully retracted in the rotor slots to thereby more forcefully urge the vane tip portions into sliding contact with the cylinder inner wall to effectively prevent chattering of the vanes in the vicinity of the gas outlet openings, the means for applying hydraulic pressure comprising a high pressure port in one of the cylinder end portions for receiving pressurized hydraulic fluid during use of the compressor, first passage means connected to the high pressure port for flowing the hydraulic fluid to the radially inner ends of the vane slots, the first passage means having means for reducing the pressure of the pressurized hydraulic fluid to the relatively lower pressure level, and second passage means connected to the high pressure port for flowing the hydraulic fluid to the radially inner ends of the vane slots at the relatively higher pressure level.