| 摘要 |
PURPOSE:To prevent a diaphragm from being excessively displaced and broken by providing an overflow passage for overflowing an operating liquid from an operating liquid chamber, and providing a control valve for opening or closing the overflow passage on the overflow passage. CONSTITUTION:A plunger 14 is lowered to reduce the oil pressure in an oil chamber 12, and a diaphragm 10 is displaced downward. The fuel pressure in a pump chamber 11 is reduced by this displacement, a discharge quantity control valve 20 is opened, and the fuel pressurized by a feed pump 23 is fed into the pump chamber 11. The plunger 14 is lifted to increase the oil pressure in the oil chamber 12, and the diaphragm 10 is displaced upward. The discharge quantity control valve 20 is closed by this displacement, the fuel pressure in the pump chamber 11 is increased, a check valve 29 is opened, and fuel is discharged. When the fuel pressure detected by a feed fuel sensor 26 becomes lower than a preset value, an overflow control valve 18 is opened, the operating liquid in the oil chamber 12 is overflowed through an overflow passage 17, and the excessive displacement of the diaphragm 10 is prevented. |
