Patent ID: 7422005

Claim:
A drive arrangement for a fuel injector including a piezoelectric actuator having a stack of piezoelectric elements, the drive arrangement comprising: a first element or elements for applying a discharge current (I DISCHARGE ) to the actuator for a discharge period so as to discharge the stack from a first differential voltage level across the stack to a second differential voltage level across the stack so as to initiate an injection event, a second element or elements for 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, a third element or elements for determining at least one engine parameter prior to applying the charge current (I CHARGE ) to the actuator such that the third differential voltage level to which the stack is charged is selected in dependence on the at least one engine parameter.