| 摘要 |
PROBLEM TO BE SOLVED: To improve charging accuracy of a piezoelectric stack when a common rail pressure is reduced in a constitution escaping fuel supplied from a common rail and generating back pressure for driving a needle of an injector to low pressure by lifting a valve element by elongation of the piezoelectric stack and reducing common rail pressure in states of opening valve of the needle and seating of the needle. SOLUTION: Charging current is dispersed by turning on both of cylinder selection switches 25A and 25B and connecting two piezoelectric stacks 127A and 127B with charging routes 22a and 22b. A substantially charging current suppression effect is obtained without increasing a switching frequency of a switching element 24a for charging and unit time supply energy per each of piezoelectric stacks 127A and 127B is reduced.
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