Patent ID: 7595579

Claim:
In a piezoelectric actuator module having a piezoelectric actuator fastened between an actuator head and an actuator foot, and having a sheath, surrounding the piezoelectric actuator, for electrical passivation, the improvement wherein the sheath is an insulation guard layer joined by nonpositive and/or positive engagement by means of a mechanical attachment to attachment components in the region of the end faces of the piezoelectric actuator or of the actuator head and/or the actuator foot, wherein the sheath is a plastic sleeve as the insulation layer, which sheath rests firmly and in sealing fashion in annularly or helically extending indentations on the circumference of the cylindrical head and/or foot part of the piezoelectric actuator module, wherein the plastic sleeve comprises material that shrinks under the influence of temperature, wherein the indentations are helically extending indentations, the module further comprising a spiral spring mounted on the outside on the circumference of the plastic sleeve that rests on the head and/or foot part, the spiral spring pressing the plastic sleeve into these indentations.