DE19928180B4 - piezo actuator - Google Patents

Abstract

It is a piezoelectric actuator, for example, for actuating a mechanical component, proposed in which a multi-layer structure of piezoelectric layers (2) and disposed therebetween internal electrodes (3, 4) are present. A mutual contacting of the inner electrodes (3, 4) with outer electrodes (5, 6) on one side of the piezoelectric actuator (1) is carried out, in each case on the piezoelectric layer (2), which carries no inner electrode (3, 4) to be contacted, a predetermined area (8; 9; 10; 11) of the inner electrode (3, 4) is recessed in the area of the contacting. Between the contacts of the outer electrodes (5, 6), a groove (12) can be provided on the piezoelectric layers (2).

Description

State of technology

The The invention relates to a piezoelectric actuator, for example for actuating a mechanical component such as a valve or the like.

It is well known that taking advantage of the so-called piezoelectric effect a piezoelectric element made of a material having a suitable crystal structure can be built. When applying an external electrical voltage there is a mechanical reaction of the piezoelectric element, depending on from the crystal structure and the plant areas of the electric Stress represents a pressure or train in a predeterminable direction.

Of the Construction of this piezoelectric actuator can be done here in several layers (Multilayer actuators), wherein the internal electrodes, over the the electrical voltage is applied, in each case between the layers, e.g. be applied with a printing process. In usual Way become the printed areas different polarity offset from each other, so here is a lateral contact with external electrodes possible is. Since each contacted on one side internal electrodes thus comb - like are integrated into the layer structure, the Internal electrodes outside be contacted so that when a DC voltage system between piezo capacities be formed. The contacted electrodes usually can not always complete to the opposite side guided Otherwise, flashovers will destroy the Lead piezoelectric actuator can.

In Scripture DE 41 05 997 A1 a piezoactuator is disclosed, which consists of a plurality of piezoelectric layers, between each of which an inner electrode is arranged. The inner electrodes cover only a partial area of the piezoelectric actuator, but a connection to the surface and thus to the outer electrode is always given.

Out WO 92/06510 A1, a piezoelectric actuator is known which in cross section U-shaped is trained. The piezoelectric actuator consists of a large number of piezo layers with internal electrodes in between, with the internal electrodes alternately guided in the extensions formed by the U-shape.

Advantages of invention

Of the initially described piezoelectric actuator, for example, for actuating a mechanical component can be used, is with a multi-layer structure composed of piezoelectric layers and arranged therebetween electrodes. Advantageously, according to the invention a mutual contacting of the internal electrodes with external electrodes provided only on one side of the piezoelectric actuator. Here is each at the piezoelectric layer, which carries no inner electrode to be contacted, a predetermined area of the inner electrode in the contact area spared. The example recessed by non-printing Area extends over a predetermined distance from that at the other piezoelectric layer attached contacting.

With the unilateral external contact according to the invention the piezoelectric actuator, the production of the piezoelectric actuator substantially be simplified because the contact for the plus and the negative pole the DC voltage to be applied in one step at a preferred for the outer terminals Side of the piezoelectric actuator can be made.

Of the recessed area can be e.g. to the nearest corner of the piezo actuator or up to the contact on the own piezoelectric layer or on the entire side of the piezoelectric actuator to which the external electrodes are attached, extend, with the exception of contacting at its own piezoelectric layer. The wider the area without the electrode layer, the wider is a contacting of the external electrodes possible; the narrower the range is, the larger the piezo effect is only between the internal electrodes can occur. It turns out with it for every application an optimized design of the internal electrodes with the recessed areas.

These and further features of preferred embodiments of the invention go out from the claims also from the description and the drawings.

drawing

embodiments the piezoelectric actuator according to the invention will be explained with reference to the drawing. Show it:

1 a view of a piezoelectric actuator with a multi-layer structure of layers of Pizokeramik mounted on one side outer electrodes;

2 a schematic plan view of two alternately stacked in the stack structure Piezolagen after 1 with recessed areas of the internal electrode layer according to a first embodiment;

3 a schematic plan view of two alternately in the stack structure superimposed piezo layers after the 1 with recessed areas of the internal electrode layer according to a second embodiment;

4 a schematic plan view of two alternately stacked in the stack structure Piezolagen after 1 with recessed areas of the inner electrode layer according to a third embodiment.

description the embodiments

In 1 is a piezoelectric actuator 1 shown, in a conventional manner from piezo layers 2 is constructed of a ceramic material having a suitable crystal structure, so that taking advantage of the so-called piezoelectric effect when applying an external DC electrical voltage to internal electrodes 3 and 4 via externally contacted electrodes 5 and 6 a mechanical reaction of the piezoelectric actuator 1 he follows.

In the 1 are just a few internal electrodes 3 and 4 schematically indicated and the outer electrodes 5 and 6 are designed as flat electrodes, each having an outer electrode 5 or 6 at contact points each with the, having the same polarity internal electrodes 2 or 3 , are contacted. The internal electrodes 3 and 4 are each alternating in the areas where they are not using an outer electrode 5 or 6 contacted, offset by a recessed area inward.

Based 2 is in the right part a piezo layer 2a to recognize in detail, in which a recessed area 8a the inner electrode 3 is arranged at the bottom corner. In a piezo situation 2 B in the left part of the 2 is a recessed area 8b at the top corner of the inner electrode 4 appropriate. The outer electrodes 5 and 6 are each with the internal electrodes 3 and 4 on the respective piezolayer 2 contacted, which has no recessed area there.

In 3 is a second embodiment of the internal electrodes 2 shown, where in the right part of a piezoelectric layer 2a with a semicircular recess 9a at the inner electrode 3 and a contact of the outer electrode 6 is shown. In a piezo situation 2 B in the left part of the 3 is a semi-circular recess 9b at the inner electrode 4 and a contact of the outer electrode 5 shown.

A third embodiment according to 4 shows a piezo layer 2 B in which the recessed area 10b down to the outer electrode 5 extends, via the contact on the own piezoelectric layer 2 B is made.

Claims (5)

Piezo actuator with a multilayer structure of piezo layers ( 2 ) and interposed internal electrodes ( 3 . 4 ) and with a mutual contacting of the internal electrodes ( 3 . 4 ) with external electrodes ( 5 . 6 ) on one side of the piezoelectric actuator ( 1 ), wherein the inner electrode ( 3 ) with the exception of a recessed area ( 8th . 9 . 10 . 11 ) around the non-contacted outer electrode ( 5 ) over the entire piezoelectric layer ( 2 ) and where the recessed area ( 8th . 9 . 10 . 11 ) only on the side of the piezo actuator ( 1 ), at which the outer electrodes ( 5 . 6 ) are attached with the exception of contacting the piezoelectric layer ( 2 ). Piezoelectric actuator according to claim 1, characterized in that the recessed area ( 8th . 9 . 10 . 11 ) over a predetermined distance to that at the other piezoelectric layer ( 2 ) attached contacting extends. Piezoelectric actuator according to claim 2, characterized in that the recessed area ( 8th ) to the nearest corner of the piezoelectric actuator ( 1 ). Piezoelectric actuator according to Claim 2 or 3, characterized in that the recessed area ( 10 ) extends to the contact on the own piezoelectric layer. Piezoelectric actuator according to one of Claims 1 to 4, characterized in that in the region between the contacts of the external electrodes ( 5 . 6 ) the piezo layers ( 2 ) are recessed inwardly a predetermined amount to form a groove ( 12 ).