VARIABLE DISPLACEMENT PUMP

摘要

PROBLEM TO BE SOLVED: To form a variable metering orifice in a simple structure for relatively displacing a cam ring to a rotor in a variable displacement pump. SOLUTION: A cam ring 17 defining a pump chamber in a body 11 spaced from the rotor 15 is arranged in a displaceable manner and energized so as to keep the pump capacity of the pump chamber 18 to a maximum. A selector valve 30 is provided to be operated with a pressure difference between the upstream and downstream sides of a variable metering orifice 40 provided on the way of pump discharge side passages 20a, 28 for controlling fluid pressure in first and second fluid pressure chambers 43, 44. The variable metering orifice has a hole portion 29 made in a plate arranged on the side face of the cam ring for connecting a pump discharge side to an annular gap space between the cam ring and a rotor and a cam ring side portion for changing the opening area at the opening end of the hole portion with the movement of the cam ring.