Piezoelectric element e.g. directly controlled actuator, charging and discharging method for piezo-injector of internal-combustion engine, involves evaluating temporal gradient of voltage of element after discharging/charging process

摘要

The method involves providing a nozzle needle (15) of a piezo-injector (1) for monitoring a stroke (Hdn) by an actuating unit. The actuating unit is controlled by a piezoelectric element (3), and a temporal gradient of an electrical voltage of the piezoelectric element is evaluated after a discharging process or a charging process by the actuating unit. A local extreme value or a break in the temporal gradient of the electrical voltage is determined after the discharging or charging process. Controlling of the piezoelectric element is regulated depending on the increase of the gradient. Independent claims are also included for the following: (1) a computer program for controlling and/or regulating a piezoelectric element (2) a controller for controlling and/or regulating a piezoelectric element.