Importance

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Abstract

In external electrodes on piezoceramic multi-layer actuators, high tensile stresses act during operation on the insulating region below the base metallic coating. Problems are caused by the linking of the electrode with a conductive connection, via which the electric voltage is to be supplied. The soldering or welding process reinforces the external electrode, which thus loses elasticity at the soldering or welding point. During operation, mechanical shear stresses then occur beneath said soldering or welding points, as the electrode region lying above no longer expands. After several million operating cycles, this causes the external electrode together with the base metallic coating to become detached, thus leading to the failure of the component. The invention is characterised in that the external electrode (23, 24; 26, 27) consists of alternating layers of conductive materials (19) and non-conductive materials (22, 25), located one on top of the other, that one of the two outer layers of conductive materials (19) is connected to the base metallic coating (11) of the actuator (1) and the other is connected to the supply conductor (6) for the voltage, and that the layers of conductive materials (19) are interconnected in a conductive manner.

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First Claim