VARIABLE DISPLACEMENT PUMP

摘要

PROBLEM TO BE SOLVED: To provide a variable displacement pump capable of reducing power loss by setting a pump discharge pressure closer to a necessary hydraulic pressure.SOLUTION: At a high rotational speed of an engine, a solenoid selector valve 8 introduces a hydraulic pressure to a second control oil chamber 17 via first and second solenoid control ports 55 and 56 having an orifice effect. On the other hand, a pilot valve 7 cuts off a communication state between a hydraulic pressure introduction port 45 and a first pilot control port 46 at an initial position at which a first spool valve 42 is urged by a first valve spring 44 to move to a rightmost location. If a discharge pressure increases, the pilot valve 7 communicates the ports 45 and 46 with each other and communicates a second pilot control port 47 with a first drain port 48 to thereby control a hydraulic pressure of a first control oil chamber 16.