| 摘要 |
PROBLEM TO BE SOLVED: To ensure high responsiveness at usual injection and controllability under reduced pressure in combination without enlarging a device or needing cost increase by enabling the control under reduced pressure by the idling drive in a fuel injection device using a piezo injector. SOLUTION: An injector 1 is opened or closed by a three-way valve 8 which is driven by a piezo actuator 2 between a control chamber 15 and a common rail 3 through a leak passage 43. ECU 5 performs a reduced pressure control of the common rail 3, when it is judged from the operation condition of the engine that the reduced pressure condition of the common rail 3 is effected, by setting the rising speed of output voltage applied to the piezo actuator 2 slower than that in usual injection driving, setting the invalid injection period until a nozzle needle 13 opens longer than that in the usual and then overflowing a high pressure fuel through the leak passage 43 by performing an idling drive in which the valve opening is driven in a time width shorter than the invalid injection period.
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