Abstract: A piezoelectric actuator, in particular for actuating control valves or injection valves in motor vehicles, having an actuator body embodied in the form of a multilayered laminate made up of stacked layers of piezoelectric material with intervening metallic or electrically conductive layers that function as electrodes. The piezoelectric actuator include end faces, between a bottom plate oriented toward the valve and an opposing top plate, which are elastically prestressed by two spring bands that are disposed in the longitudinal direction on opposite sides of the actuator body and whose prestressing force can be adjusted by an adjusting nut. The piezoelectric actuator is constituted so that the adjusting nut engages in screw fashion with an external thread provided on a central, axial extension bolt of the top plate and which, depending on a screwed position, adjusts the prestressing force of the spring bands.

Abstract: The invention describes a method and an apparatus for charging a piezoelectric element of a fuel injection system for, for example, an internal combustion engine. The apparatus is characterized in that the piezoelectric element is activated by an activation voltage having a value set as a function of measured fuel pressure in the fuel injection system.