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|1. (WO2017154438) VARIABLE DISPLACEMENT PUMP|
|Applicants:||HITACHI AUTOMOTIVE SYSTEMS, LTD.
|Title:||VARIABLE DISPLACEMENT PUMP|
Provided is a variable displacement pump comprising: a first control oil chamber 21 for applying force by internal oil pressure, to a cam ring 5 in the direction in which the amount of change in the volume of pump chambers 13 is reduced; a second control oil chamber 22 for applying force by internal oil pressure, to the cam ring in the direction in which the amount of change in the volume of the pump chambers is increased; first seal surfaces 44 formed on both end surfaces of the cam ring 5, which slide on the facing inner surfaces of a pump body 1 and a cover member 2, and sealing between the pump chambers and the first control oil chamber; and second seal surfaces 45 which, within a discharge-side region, seal between the pump chambers and the second control oil chamber. The radial width W2 of the second seal surfaces is configured to be greater than the radial width W1 of the first seal surfaces. As a result, an unintended increase in pump control pressure is prevented and an increase in the weight of the entire pump is prevented.