System and method for operating a piezoelectric fuel injector

摘要

A method of operating a fuel injector including a piezoelectric actuator having a stack of piezoelectric elements, comprises applying a discharge current (I_DISCHARGE) to the actuator for a discharge period so to discharge the stack from a first differential voltage level across the stack to a second, lower differential voltage level across the stack so as to initiate an injection event, and applying a charge current (I_CHARGE) to the actuator for a charge period (T 3 to T 4 ') so as to charge the stack from the second differential voltage level to a third differential voltage level so as to terminate the injection event. The method includes determining at least one engine parameter (e.g. common rail pressure) of the injection event prior to applying the charge current (I_CHARGE) to the actuator and selecting the third differential voltage level in dependence on the at least one engine parameter.