| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable displacement pump having reduced power loss by making pump discharge pressure approximate required hydraulic pressure. SOLUTION: The variable displacement pump comprises a pump structure for discharging lubricating oil which is introduced from a suction port 7 to a plurality of pump chambers 13 by being rotated and driven by a crank shaft, from a discharge port 8 to the inside of an engine and a variable valve gear with changes in the capacities of the pump chambers. The capacities of the pump chambers are changed with a cam ring 5 rocked by discharge pressure supplied into a control oil chamber 16. Two inside and outside first and second coil springs 20, 21 are provided in parallel for energizing the cam ring to increase the capacities of the pump chambers. Both coil springs have spring constants set to be greater as the rocking amount of the cam ring is greater in the direction of reducing the changes in the capacities of the pump chambers. COPYRIGHT: (C)2009,JPO&INPIT
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