Patent ID: 6280150
Filing Date: 2001-08-28
Classification: F04C

Abstract:
A variable displacement pump comprising:a cam ring for forming a pump chamber from a rotor in a state where said rotor having a vane is moved to an eccentric position;a cam case mounted on a portion around said cam ring to swingably support said cam ring such that a swingable pin axially disposed in a portion of an outer periphery of said cam ring in a circumferential direction of said cam ring serves as a fulcrum so that the capacity of said pump chamber is changed, said cam case urging said cam ring in a direction in which the capacity of said pump chamber is maximized;front and rear bodies between which said cam case serving as an intermediate body is disposed and which are disposed on the two sides in the axial direction of said cam case so as to form a pump today;a rotational shaft pivotally supported by said front and rear bodies so as to rotate said rotor; anda pressure plate disposed on the inside of said front body at a position at which said pressure plate is in contact with a portion adjacent to said cam case so as to introduce pressurized oil in a discharge portion of the pump to a back surface of said pressure plate;wherein a low pressure chamber for introducing low level oil pressure is formed at a position opposite to a suction region of said pump chamber; andwherein said low pressure chamber is surrounded by a discharge chamber.