| 摘要 |
PROBLEM TO BE SOLVED: To improve injection stability of an injector for an internal combustion engine and to reduce the size of an actuator by reducing required driving energy. SOLUTION: In this injector 1, the pressure in a nozzle needle back pressure chamber 5 is lowered to inject a fuel supplied from a high pressure passage 12. In injection, a piezo stack 7 is driven to operate a small-diameter piston 74 through a large-diameter piston 72 and a displacement enlarged chamber 73, and a valve 4 is pressed down to open a leak passage 12. The lower tapered part 7b of the small-diameter piston 74 is elongated to enlarge the capacity of a small-diameter piston lower chamber 6 in the downstream of the valve 4 and function the same as a pressure attenuating chamber. The pressure peak of leak fuel flowing out of the valve upper seat 4c is reduced to lower the force of pushing up the small-diameter piston 74, whereby the energy required for driving can be reduced to heighten the stability. COPYRIGHT: (C)2005,JPO&NCIPI
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