DE102008012281B4 - Method for producing a piezoelectric actuator with piezo elements arranged on a carrier - Google Patents

Abstract

A method of making a piezo actuator module (15) having outwardly facing non-contact actuator surfaces for actuating rotor blade flaps (12) disposed on the trailing edge (11) of a helicopter rotor blade (10) comprising a plurality of regularly distributed one Composite assembled and flush abutting arranged planar, held by a fiber composite material carrier held piezo elements (14), wherein a surface of the piezo-element composite of electrically conductive metal existing contact strips are assigned, whose unilaterally projecting beyond the carrier ends as electrical connection contacts (24, 29) serve, wherein the carrier as a recess (21) exhibiting, the piezo elements (14) comprehensive frame (20) is formed and the piezo elements (14) via their end faces (17) by electrically conductive Adhesive connections (13) with each other and with the frame (20) are connected, and wherein under Zwischenfügu ng an electrically insulating, congruent to the frame (20) formed, an elastic core forming film (26) made of fiber composite a congruent to the first frame (20) formed, also equipped with piezo elements (14) and contact bands (27) exhibiting second frame (28) is arranged, wherein the frame (20, 28) and the interposed foil (26) are connected to the single-stage piezo-actuator module (15) with outwardly facing non-contact actuator surfaces, characterized by the following method steps: a) in the Recess (21) of a rectangular frame (20, 28) made of a fiber composite material planar rectangular piezo elements (14) are inserted flush abutting, b) between the mutually facing end faces (17) of piezo elements (14) and the recess (21 ) of the frame (20, 28) electrically conductive adhesive is inserted, c) on which a free side of the piezo-elements (14) equipped with frame (20) werd placed conductive metal strips on one side of the frame (20, 28) as electrical connection contacts (24, 29), d) two congruent trained and equipped with piezo elements (14) and provided with electrically conductive adhesive frame (20, 28) are combined with the interposition of an insulating flexurally elastic film (26) to form a module (15) whose bonds are cured under vacuum, e) the cured module (15) is ground until the desired module thickness is achieved and longitudinally ...

Description

The invention relates to a piezoelectric actuator with arranged on a support piezoelectric elements and a method for its preparation.

Piezo actuators are widely known and serve as drive means in different fields of application. So show the DE 20 2004 006 333 U1 and the DE 10 2005 061 751 A1 in each case applied to a support layer contacted with each other piezoelectric elements which are activated via a controllable electrical drive voltage for the operation of arranged at the trailing edge of a helicopter rotor blade rotor blade flaps. For this purpose, the piezoelectric actuators and their carrier layer are each adapted to the different receiving structure of the rotor blade configuration and covered by a flexible elastic protective skin on both sides.

The piezo actuator after the DE 20 2004 006 333 U1 is a thin elastically bendable bending plate element that penetrates the tread depth of the rotor blade. This is expensive to manufacture, requires special design of the rotor blades, is difficult to maintain and difficult, if any, to assemble and disassemble, as is necessary in case of failure of some or all of the piezo elements of the actuator.

The piezo actuator after the DE 10 2005 061 751 A1 is a reversible bendable bending actuator having an inclusion profile structure for insertion there by means of an insertion opening in the trailing edge of the rotor blade. The individual piezoelectric elements are arranged on a plate-shaped reversible bendable carrier layer and may have a varying thickness.

Such a construction is complicated to manufacture, requires elastic filling material and in its configuration depends on the configuration of the particular rotor blade to be equipped therewith. Again, a simple replacement or easy maintenance of the rotor blade flaps is not possible. In addition, the production of such piezoelectric actuators is difficult, as they take into account to be observed biasing the piezoelectric elements due to thermal biases and avoiding structurally induced distortion during the individual process steps in the production and the prevention of damage during manufacture and assembly has to be done.

In the DE 100 51 784 C1 is disclosed an electromechanical functional module with at least one transducer. The module has a plurality of frame-shaped, a cutout for receiving the transducer receiving fiber liners.

The invention is based on the object to provide a method for producing a new piezoelectric actuator, which is easier and better than heretofore manufactured and assembled and which is without the power losses caused during production.

This object is achieved according to the invention and for the method for producing the actuator by the features of patent claim 1.

Further features of the invention will become apparent from the dependent claims.

The invention provides a method for producing a well-built piezoelectric actuator in the form of a more or less standardized module with variable piezo thickness, which has significant advantages in terms of its mechanical properties, in terms of stiffness and active path, the simple and reproducible properties can be produced at any time and is protected against temporary damage during transport and assembly.

This is achieved in that planar piezoelectric elements are juxtaposed flush next to and behind each other, which are covered by a frame made of fiber composites, all facing end faces of piezo elements and frames are firmly connected by means of electrically conductive adhesive and through the one a total surface-forming surfaces of the individual piezoelectric elements associated are made of electrically conductive metal contact strips whose unilaterally projecting beyond the frame ends serve as electrical connection contacts and by a congruent to the frame formed an elastic core forming electrically insulating film, also made of fiber composite material, the one second congruent to the first frame trained equipped with piezo-elements and contact bands having second frame, for the purpose of forming an actuator module assigned.

The invention thus provides an easily installed piezoelectric actuator in the form of a more or less standardized module with variable piezoelectric thickness and with mechanical connection elements, which, independently of the shape and design of the respective rotor blades by its multiple arrangement, can be simply and quickly produced as rotor blades. Flap to assemble and disassemble is.

The invention is described below with reference to two more or less schematically illustrated embodiments.

Show it:

1 a preferred application of the piezoelectric actuator according to the invention in its training for the operation of the arranged at the trailing edge of a helicopter rotor blade rotor blade flap;

2 as an exploded view of the components of the piezoelectric actuator according to the invention according to a first embodiment;

3 the arrangement of the piezo elements of the piezo actuator after 2 ;

4 a manufacturing step for the production of the piezo actuator according to 2 ;

5 a further manufacturing step in the production of the piezo actuator after 2 ;

6 as an exploded view of a second embodiment of a piezoelectric actuator;

7 a manufacturing step in the manufacture of the piezo actuator according to 6 ;

8th a plan view of an effective surface of the finished piezoelectric actuator according to 6 ; and

9 the trained as a standardized module piezo actuator after 6 ,

An in 1 shown section of a helicopter rotor blade 10 indicates at its trailing edge area 11 a rotor blade flap 12 on, which consists of a plurality of piezo elements 14 supporting autonomous piezo actuator modules 15 ₁ to 15 _{n is} formed. The single juxtaposed modules 15 ₁ to 15 _n are with their mating surfaces 16 in a slot provided for this purpose 18 inserted at the front of the trailing edge area and by means of screws 19 with the rotor blade 10 firmly but detachably connected. A flexible cover 16 connects the individual modules 15 ₁ to 15 _n to an integral controllable flap on the trailing edge of the rotor blade 10 ,

The structure of a piezo actuator module is in the 2 to 5 shown. These modules each comprise a plurality of mutually identical sheet-like piezo elements 14 , the chequerboard next to and behind each other and arranged by means of an electrically conductive adhesive along its narrow sides 17 are glued together firmly. For this purpose, an existing fiber composite frame 20 provided by means of a recess 21 all piezo elements 14 includes and is also adhesively bonded at its end faces with the facing end faces of the piezoelectric elements, as is apparent from 4 , Reference numeral 13 , can be seen. Further, contact bands 23 of electrically conductive metal - such as copper / copper beryllium - provided on the in 2 remote side of the piezo-elements are placed and with its free end of the module outstanding connection contacts 24 form.

With the interposition of an electrically insulating, an elastic core forming flexurally elastic film 26 same configuration as the frame 20 , is a second with piezo elements 14 equipped and with contact bands 27 covered frame 28 with the first frame to said module also connected by gluing. The free end of the contact band 27 also forms a connection contact 29 ,

After curing at about + 115 ° C of the entire adhesive bonds under vacuum and grinding to the desired module thickness of the outwardly facing surfaces of the module manufactured in this way are still the opposite side edges 31 and 32 - see. 2 - by a sawing process - cf. 5 - Disconnect so that each finished piezo actuator module 15 in the 1 having shown configuration. For the grinding process, the module on the opposite side must be fixed flat by means of an aluminum block.

In order to be better protected against environmental influences (in particular the penetration of moisture), the module is still coated with a suitable coating in the form of a film or a copper-beryllium skin.

In the in the 6 to 9 shown second embodiment of a piezo-actuator module - with the reference numeral 30 denotes - includes this - how 6 shows -, also a number of rectangular parallelepiped piezo elements 31 that from a a recess 32 having frames 33 are comprised of a fiber composite material. On the long sides of the side by side and behind each other arranged piezo elements 31 are each in slots 34 of the frame 33 guided contact bands 35 arranged, whose free ends 37 also form terminal contacts for the control, not shown, consisting of individual piezo actuator modules rotor flap.

The frame 33 is a carrier plate 39 assigned to the piezo elements 31 fed up. The corresponding components are glued together here by means of an electrically conductive suitable adhesive. After curing these adhesive joints, the module is to the desired strength, such as 7 half sawed to thickness, so that the resulting halves each in the 8th have shown configuration. For the sawing operations, a plane fixation of the module is also necessary. Again, there is a protective coating surrounding the module 40 - see. 6 - intended. The module 30 can also - if necessary, as in 5 shown - are divided by perpendicular to its surface Sägeschritte flat in the desired configuration.

As a fiber composite material used in both Ausführungsbespielen glass fiber reinforced plastic.

Between the piezos and these associated cover layers (eg foil copper beryllium CuBe, thickness about 5 microns or more or aluminum) to protect against environmental influences (especially moisture) is not shown here another layer of electrical insulation material, eg. As fiberglass (fiberglass composite), the advantageous manner with an electrical insulation thickness of z. B. 0.05 mm or more is formed in order to avoid electrical problems with the electrodes of the piezos. However, the cover layers (CuBe / Al + insulation / GFRP) should be as thin as possible in order to minimize detrimental rigidity for active deformation of the module.

LIST OF REFERENCE NUMBERS

10

Helicopter rotor blade

11

Trailing edge region

12

Rotor blade flap

14

Piezo elements

15 ₁ to 15 _n

Piezo-actuator modules

16

Mating surfaces, cover

17

narrow sides

18

slot

19

screw

20

frame

23

contact strips

24

Statements contacts

26

foil

27

contact strips

29

connection contact

30

Piezo-actuator module

31

Piezo elements

32

recess

33

frame

34

slots

35

contact strips

37

free ends of the contact bands 35

39

support plate

40

protective coating

Claims (6)

Method for producing a piezo actuator module ( 15 ) with outwardly facing non-contact actuator surfaces for actuating at the trailing edge ( 11 ) of a helicopter rotor blade ( 10 ) arranged rotor blade flaps ( 12 ), comprising a plurality of regularly distributed, in a composite assembled and flush abutting arranged planar, held by an existing fiber composite substrate piezo elements ( 14 ), wherein a surface of the piezo-element composite of electrically conductive metal existing contact strips are assigned, whose unilaterally projecting beyond the carrier ends as electrical connection contacts ( 24 . 29 ), the carrier being a recess ( 21 ), the piezo elements ( 14 ) comprehensive framework ( 20 ) is formed and the piezo elements ( 14 ) over their faces ( 17 ) by electrically conductive adhesive bonds ( 13 ) with each other and with the frame ( 20 ) and with the interposition of an electrically insulating, congruent to the frame ( 20 ) formed, an elastic core forming film ( 26 ) of fiber composite material is congruent with the first frame ( 20 ) trained, also with piezo elements ( 14 ) equipped and contact bands ( 27 ), the second framework ( 28 ), the frames ( 20 . 28 ) and the interposed foil ( 26 ) to the single-stage piezo actuator module ( 15 ) are connected to outwardly facing non-contact actuator surfaces, characterized by the following method steps: a) in the recess ( 21 ) of a rectangular frame ( 20 . 28 ) are made of a fiber composite material planar planar piezoelectric elements ( 14 ) inserted flush against each other, b) between the mutually facing end faces ( 17 ) of piezo elements ( 14 ) and the recess ( 21 ) of the frame ( 20 . 28 ) electrically conductive adhesive is inserted, c) on the one free side of the piezo elements ( 14 ) ( 20 ) conductive metal bands are placed on one side of the frame ( 20 . 28 ) as electrical connection contacts ( 24 . 29 ), d) two congruently formed and with piezo elements ( 14 ) equipped with electrically conductive adhesive ( 20 . 28 ) with the interposition of an insulating flexurally elastic film ( 26 ) to a module ( 15 ), whose bonds are cured under vacuum, e) the cured module ( 15 ) is abraded until reaching the desired module thickness and along the opposite sides, which without outstanding electrical connection contacts ( 24 . 29 ) are sawed to such a degree that the running in the flow direction, opposite side edges ( 31 . 32 ) the frame ( 20 . 28 ) are separated. Method according to claim 1, characterized in that the cured module ( 15 ) is fixed flat for grinding and sawing. A method according to claim 1 or 2, characterized in that the curing takes place at about + 115 ° C. Method according to one of claims 1 to 3, characterized in that is used as the electrically conductive material copper / copper beryllium bands. Method according to one of claims 1 to 4, characterized in that the actuator module ( 15 ) with mounting connections ( 16 ) for attachment or installation in a rotor blade flap ( 12 ) is formed. Method according to one of claims 1 to 5, characterized in that the fiber composite material is formed as a glass fiber reinforced plastic.

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