Method for producing a monolithic piezo actuator with stack elements, monolithic piezo actuator with stack elements, and use of the piezo actuator

Abstract

A piezo actuator has a stack element and at least one further stack element, wherein each of the stack elements has stacked piezoceramic layers and electrode layers arranged between the piezoceramic layers, each of the electrode layers extends to at least one of at least two lateral surface sections of the stack element which have external metallizations on them, and are connected to the electrode layers such that adjacently stacked electrode layers can have different electrical potentials applied to them indirectly via the external metallizations, the stack elements are arranged above one another to form a monolithic total stack, and connected to one another by at least one connecting layer. The following steps are provided: a) provision of the total stack and b) production of a load-relieving crack in the connecting layer. An electrical connector in the form of a wire can be fitted on the relevant external metallization regions.

Description

TECHNICAL FIELDThe invention relates to a method for producing a monolithic piezo actuator featuring stack elements stacked one above the other. In addition a monolithic piezo actuator and a use of the piezo actuator are specified.BACKGROUNDPiezo actuators are known that consist of a plurality of stack elements arranged one above the other. Each of the stack elements features piezoceramic layers arranged above one another made of a piezoceramic material and electrode layers (internal electrodes) arranged between the piezoceramic layers. With monolithic, i.e. one-piece piezo actuators, the entire arrangement consisting of piezoceramic layers and electrode layers is obtained in a common sintering process. The result is a total monolithic stack consisting of stack elements.When such piezo actuators are electrically activated for the first time up into the high signal range (field strengths of several kV / mm) the piezoceramic material is polarized. This results in an irreversible length ...

AI Technical Summary

Benefits of technology

The method reduces the likelihood of crack formation and propagation, enhancing the reliability and longevity of the piezo actuator by distributing mechanical stresses effectively and maintaining structural integrity during operation.

Problems solved by technology

These tensile stresses lead, during the polarization or in the operation of the piezo actuator, to cracks (polarization cracks) occurring for example along a boundary surface between a piezoceramic layer and an electrode layer.

Cracks which form branches or propagate in the longitudinal direction of the total stack are especially damaging here.

Such cracks inevitably lead to the premature failure of the piezo actuator.

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