Fuel injection control device for internal combustion engine

摘要

An excess voltage applied to a piezoelectric element is detected and controlled to improve durability and reliability of the piezoelectric element. A fuel injection control device for an internal combustion engine in which a power source voltage is boosted by a dc-dc converter and the so-boosted output voltage is supplied via a first choke coil and a first thyristor to a piezoelectric element for charging the piezoelectric element for being subsequently discharged via a second thyristor and a second choke coil. The fuel injection control device includes a negative voltage detection unit for detecting the negative voltage at a cathode terminal of the second thyristor and a negative voltage control unit for controlling the voltage at the cathode terminal of the second thyristor to substantially a ground potential under control by an output signal of the negative voltage detection unit.