Method and device for determining the drive voltage of a piezoelectric actuator of an injection valve

The method involves detecting a first maximum voltage set after charging the piezoelectric actuator and a second constant voltage just before discharging the piezoelectric actuator for different charging currents applied in the same time interval, evaluating the relationship between the first and second voltages and drawing conclusions re the voltage required by the piezoelectric actuator. An independent claim is also included for determining the drive voltage for a piezoelectric actuator of an injection valve.