| 摘要 |
PROBLEM TO BE SOLVED: To avoid secondary injection and noise from occurring due to impact at the time of opening and closing of a needle valve in a fuel injection valve having a mechanism to open and close a nozzle by converting the telescoping of a piezoactuator into the forward and backward movements of a valve element. SOLUTION: A piezoactuator 12 is formed with a plural of actuator parts 12a and 12b connected to each other in series and in axial direction, and one actuator part is driven in the valve closing direction immediately before a needle valve 13 is fully opened, or driven temporarily in the valve opening direction immediately before it is fully closed. By this, the lift and speed of the needle valve 13 at the opening and closing are suppressed so as to relieve impact. Also the piezoactuator comprises a first actuator part of L1 in length and a second one of L2 in length, and the lengths L1 and L2 of the actuator parts are set so that the requirement of L1>(a1/a2)s.δis satisfied where the piston part pressure receiving area of a back pressure chamber is a1, piston part pressure receiving area of a pressure differential chamber is a2, the necessary lift amount of a needle valve is (s), and the piezo displacement rate of the actuator part isδ(provided thatδis the overall length/displacement amount of the piezoactuator).
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