| 摘要 |
PURPOSE:To improve dynamic range (effective operating range) by providing an electrically driven fuel pump for supplying fuel from a fuel source to a fuel injection device, and controlling the fuel feed pressure of the pump according to the driving frequency of the fuel injection equipment. CONSTITUTION:In a system having a unit injector incorporating a pump member driven by a piezoelectric driving portion as a fuel injection device, there is provided an electrically driven fuel pump 98 for supplying fuel from a fuel tank 94 to the injector 10. The electrically driven pump 98 is controlled according to injection quantity computed from outputs of sensors 124, 128 for detecting intake pressure and engine speed. That is, a piezoelectric actuator is driven designated times by driving voltage calculated from the injection quantity. At this time, the target fuel feedback pressure to the driving frequency of the actuator is set. The larger the driving frequency is, the more the target fuel feedback pressure is increased, and the smaller it is, the more the target fuel feedback pressure is decreased.
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