Variable displacement pump

A variable displacement pump comprising:

• a pump body having an inner space and formed with a suction path and discharge paths communicating with said inner space;
• a cam ring having a swing fulcrum pin on part of an outer surface thereof to extend in an axial direction, and swingably supported in said inner space of said pump body through said swing fulcrum pin as a fulcrum;
• a rotor having vanes and arranged inside said cam ring to be eccentric on one side of said cam ring;
• a rotating shaft mounted on an axis of said rotor and axially supported by said pump body;
• a pump chamber having an opening for said suction path and an opening for said discharge path and formed between an inner surface of said cam ring and an outer surface of said rotor;
• first and second fluid pressure chambers divisionally formed between said inner space of said pump body and an outer surface of said cam ring through seal means including said swing fulcrum pin;
• biasing means for biasing said cam ring from said second fluid pressure chamber toward said first fluid pressure chamber;
• a metering restrictor provided between said discharge paths;
• and
• a control valve connected to said discharge paths formed upstream and downstream, respectively, of said metering restrictor and to said first and second fluid pressure chambers and driven by fluid pressures present upstream and downstream of said metering restrictor,
• wherein said control valve connects each of said first and second fluid pressure chambers to either one of said discharge paths formed upstream and downstream, respectively, of said metering restrictor, and selectively supplies one of the fluid pressures present upstream and downstream of said metering restrictor to said first and second fluid pressure chambers.