DE102009059023A1 - Generator for converting mechanical energy into electrical energy - Google Patents

Abstract

The invention relates to a generator for generating electrical energy. This generator has a first interdigital electrode arrangement (10) with two interlaced electrode combs (11, 12). A second interdigital electrode arrangement (20) likewise has two interlaced electrode combs (11, 12). An electroactive polymer (1) is provided between the electrode combs of the first interdigital electrode arrangement (10) and between the electrode combs (11, 12) of the second interdigital electrode arrangement (20) and between the first interdigital electrode arrangement (10) and the second interdigital electrode arrangement (20). A first control circuit is provided for the selective switching of the electrode combs (11, 12) of the first interdigital electrode arrangement (10) to different potentials or to the same potential.

Description

The invention relates to a generator for converting mechanical energy into electrical energy with an electroactive polymer. Such are used for example in wave energy generators. A wave energy generator, for example, comprises a multilayer electroactive polymer film having an electrode and a counter electrode of a mechanically flexible capacitor.

From the publication DE 60 2004 008 639 T2 Such a wave energy generator is known, wherein a floating body carries a connecting element which slides up and down with the swell and correspondingly generates electrical energy in a coil surrounding the connecting element.

From the publication US 2007/0257490 A1 For example, a system and method for utilizing an electroactive polymer to convert mechanical energy originally contained in one or more waves into electrical energy is known. For this purpose, the generator has a marine device, which converts the mechanical energy of a wave into mechanical energy, which is suitable as input for the electroactive polymer transformer. The electroactive polymer accommodates capacitors whose capacitances change as the polymer expands and compresses. The generator cycle is as follows: At the beginning, the polymer is relaxed and there is no charge in the capacitors. Subsequently, the polymer is stretched so that the capacitor has a high capacity. Subsequently, charges are applied to the capacitor and the polymer is relaxed again. This reduces the capacitance, which leads to higher voltages while the charge remains constant. The charges are dissipated, and from the voltage difference of the charges between the charging operation and the discharging operation, electrical energy is gained, which can be consumed in a load. A disadvantage of such an arrangement is that mechanical energy is not converted into electrical energy during the total shaft movement, whereby the efficiency is relatively low.

The object of the invention is thus to provide a generator which provides a higher efficiency. It is also an object of the invention to provide a method for operating such a generator.

This object is solved by the subject matter of the independent claims. Advantageous embodiments emerge from the respective subclaims.

The invention relates to a generator for generating electrical energy. This generator has a first interdigital electrode arrangement with two intermeshed electrode combs and a second interdigital electrode arrangement with two intermeshed electrode combs. One of the electrode combs of the first interdigital electrode assembly is referred to as a first electrode comb, and another of the electrode combs of the first interdigital electrode assembly is referred to as a second electrode comb. Electroactive polymer is provided between the electrode combs of the first interdigital electrode assembly, between the electrode combs of the second interdigital electrode assembly and between the first interdigital electrode assembly and the second interdigital electrode assembly. A first control circuit is provided for selectively switching the electrode combs of the first interdigital electrode arrangement to different potentials or to the same potential. Thus, the first control circuit is provided for selectively switching the first electrode comb and the second electrode comb to different potentials or to the same potential.

With the presented generator energy can be converted during movements in different directions. Because the electrode combs can be charged to different or equal potentials, different capacitors can be realized by selecting the potentials. As a result, it is not only possible to gain energy while being pulled apart in one direction, but also during the separation in the second direction. This increases the efficiency of the generator.

Preferably, a second control circuit is provided for selectively switching the electrode combs of the second interdigital electrode arrangement to different potentials or to the same potential. The second control circuit thus selectively switches a first electrode comb of the second interdigital electrode arrangement and a second electrode comb of the second interdigital electrode arrangement to different potentials or to the same potential. This results in an increased flexibility with regard to the arrangement of the capacitors, which can be arranged in both the first direction and in the second direction.

The single electroactive polymer generator preferably comprises a dielectric elastomer and electrodes of a flexible electrically conductive material which follows the strains and compressions of the elastomer. The discharge of generated charges from the elastomer over Correspondingly flexible electrodes, which can follow the deformations, strains and compressions of the electroactive polymer generator, are reliably ensured.

In one embodiment, each of the electrode combs of an interdigital electrode arrangement has respective longitudinal extensions, wherein each of the longitudinal extensions in each case lies opposite a longitudinal extension of the respective other electrode comb of the same interdigital electrode arrangement. Each of the electrode combs additionally has a collecting electrode which connects the longitudinal extensions of this electrode comb. At least one of the control circuits is set up to apply a potential to the collecting electrode. With this arrangement, it is possible that the control circuit is connected at a single point to the electrode comb and can be charged via this the entire electrode comb.

Preferably, the longitudinal extents of the electrode combs are completely surrounded by the polymer. This ensures that the electrode combs can form capacitors in all spatial directions.

Preferably, the first interdigital electrode arrangement and the second interdigital electrode arrangement are identically shaped such that a symmetrical capacitance distribution results in the generator.

The generator is particularly suitable as a wave energy generator. A shaft provides mechanical energy not only in one spatial direction but also in all spatial directions of a plane. The fluid below the fluid surface moves in a circular path. Thus, mechanical work is done not only in one direction, but in all directions. By converting mechanical work that is done in different spatial directions, the efficiency increases.

In a further embodiment, the generator has a plurality of interdigital electrode arrangements, which are arranged side by side in the form of a cuboid. Such allows a very compact arrangement of electrode arrangements, so that the space in the polymer is well utilized.

The invention also relates to a method for operating a generator according to the invention. In this case, electrode combs, which are adjacent with respect to a first spatial direction, are charged to different potentials. Subsequently, the polymer is pulled apart in the first spatial direction such that the distance between the adjacent electrode combs increases. Subsequently, the electrode combs are discharged and subsequently charged such that those electrode combs which are adjacent in a second spatial direction are charged to different potentials.

Subsequently, the polymer is pulled apart in the second spatial direction such that the distance between the adjacent electrode combs increases. Thus, in each case energy is converted when pulling in the two spatial directions in an advantageous manner.

Preferably, the first spatial direction and the second spatial direction are perpendicular to each other. This allows a vertical structure of the electrode comb structure, which simplifies the production of such a generator.

In one embodiment, the potential differences in the steps differ: charging of electrode combs that are adjacent in a first spatial direction and charging of electrode combs that are adjacent in a second spatial direction. Thus, consideration can be given to different distances of the electrode combs within interelectrode arrangements and between interelectrode arrangements. In addition, it is possible to compensate if the polymer has a different elasticity in one spatial direction than in the other spatial direction.

In one embodiment, only in a first spatial direction is actively pulled by a mechanical force added externally. During springback, due to its elasticity, the generator also expands due to the incompressibility of the polymer in the second spatial direction. As a result, electrical energy can be obtained solely by spring-back without additional externally supplied work.

The invention is illustrated in more detail in the drawings with reference to an embodiment. It shows

1 a first interdigital electrode arrangement with interdigitated electrode combs in a plan view;

2 a plurality of juxtaposed interdigital electrode assemblies;

3 the shading of a plurality of interdigital electrode arrangements in a first operating mode;

4 the wiring of in 3 shown plurality of interdigital electrode assemblies in a second mode of operation;

5 two interdigital electrode arrangements with switches for charging the electrode combs of the interdigital electrodes.

6 a further embodiment of a plurality of juxtaposed interdigital electrode arrangements;

1 shows a first interdigital electrode arrangement 10 , The first interdigital electrode arrangement 10 has a first electrode comb 11 and a second electrode comb 12 on. The first electrode comb 11 consists of a collecting electrode 6 and a plurality of longitudinal extensions perpendicular to the collecting electrode 6 branch off and of which the top three by the reference numeral 2 . 4 and 8th Marked are. The second electrode comb 12 contains a collecting electrode 7 as well as a multiplicity of longitudinal extensions. The uppermost longitudinal extensions are denoted by the reference numerals 3 and 5 designated. The electrode combs 11 and 12 are interlocked, so that the longitudinal extent of the electrode comb 11 each longitudinal extent of the electrode comb 12 are opposite. The longitudinal extensions are each drawn horizontally. The longitudinal extension 3 lies at the top of the longitudinal extent 2 and down the longitudinal extent 4 across from. The longitudinal extension 4 lies at the top of the longitudinal extent 3 and down the longitudinal extent 5 across from. This arrangement of each parallel opposite longitudinal extents of the electrode combs 11 and 12 will continue downwards accordingly.

The electrode combs 11 and 12 are in an electroactive polymer 1 accommodated. This polymer 1 encloses all longitudinal extensions as well as most of the collecting electrodes 6 and 7 that are only at one end, down from the polymer 1 , protrude and can be contacted there electrically.

2 shows an exploded view of three juxtaposed interdigital electrode arrays in an oblique view. The three interdigital electrode arrangements 10 . 20 and 30 are arranged side by side, so that in each case the electrode combs of an interdigital electrode arrangement are arranged in a plane. These planes of different interdigital electrode arrangements are parallel to each other. The interdigital electrode arrangements 10 . 20 and 30 are each constructed identically. The interdigital electrode arrangements 10 . 20 and 30 wise, as well as in 1 shown the polymer on. The polymer extends in the 2 not shown, also between the interdigital electrode arrays so that the gap between these interdigital electrode arrays is completely filled by the polymer. An electrode comb 11 the interdigital electrode arrangement 10 is so surrounded by the polymer that between it and the electrode comb 12 the interdigital electrode arrangement 10 and between the electrode comb 11 the interdigital electrode arrangement 10 and the electrode combs 11 and 12 the interdigital electrode arrangement 20 each the polymer 1 is provided.

3 shows a cross section through an arrangement 500 with a plurality of stacked interdigital electrode arrays 10 . 20 . 30 . 40 and 50 , The interdigital electrode arrangements 10 . 20 . 30 . 40 and 50 are each cut through the longitudinal extensions. In the left row you can see the longitudinal extension 2 , in the right next to it row the longitudinal extent 3 On the right, the longitudinal extensions close 4 . 5 and 8th at. The longitudinal extensions are each marked with dots or with hatching. The longitudinal extensions are each charged to electrical potentials. Those longitudinal extensions which have points are charged to a high potential, while the longitudinal extensions, which are at a low potential, are hatched. The longitudinal extents of all shown interdigital electrode arrangements 2 . 4 and 8th are each on the high potential and the longitudinal extents 3 and 5 are each set to the low potential. This results in electrical voltages between the longitudinal extensions 2 and 3 , between the longitudinal stretches 3 and 4 , between the longitudinal stretches 4 and 5 , between the longitudinal stretches 5 and 8th each of the interdigital electrode assemblies. In other words, it creates a variety of capacitors whose plates are horizontal.

It should be noted that the arrangement 500 in reality, a much larger number of interdigital electrodes and elongations than in 4 so that it does not matter if the number of adjacent electrode crests is even or odd.

The direction that runs horizontally is with x and the direction that runs vertically is marked with y. To the arrangement 50 as a generator, the device is loaded as follows. In the relaxed state, charges are applied to the longitudinal extents of the interdigital electrodes. Thus, in each case stresses U1 arise between the longitudinal extensions of adjacent layers. The order 1 is stretched in the generator so that the arrangement 1 becomes larger in the y direction and smaller in the x direction. The polymer 1 is designed to be elastic. After this pulling apart of the arrangement 500 is the capacitance of the capacitors between the longitudinal extents of the interdigital electrodes 10 . 20 . 30 . 40 and 50 become smaller. Since the charge on the longitudinal extensions is the same, the voltage has become larger. Thus, the electrical energy has increased. Work on the cargoes was done by pulling them apart. In the following step, the longitudinal extensions are discharged again before the arrangement 500 moved back to their original position.

There are also alternative embodiments in which the voltage is maintained or the electric field is kept constant rather than keeping the charge constant.

4 shows in section the arrangement 500 out 3 , wherein the longitudinal extents of the interdigital electrode arrangements 10 . 20 . 30 . 40 and 50 are loaded differently. The interdigital electrode arrangements 10 . 30 and 50 are applied to the positive potential, while the electrode assemblies are connected with all the longitudinal extensions with the negative potential.

In the description of 3 was stated that after the arrangement 500 in the maximum deflection with respect to the y-direction, the longitudinal extensions are discharged After this discharge, the electrode arrangements are as in 4 again loaded to different potentials. Subsequently, the arrangement 500 stretched in the x direction, resulting in a compression in the y direction. By changing the strain state in the x-direction, the capacitance of the capacitors formed by the longitudinal extents and the polymer decreases. By reducing the capacitance of the capacitors, the electrical voltage increases. In maximum deflection with respect to the x-direction, the longitudinal extensions are discharged again. Thus, mechanical energy is converted into electrical energy, using not only the extension in one direction to convert energy, but also the extension in the other direction.

5 schematically shows a section of the control circuit for applying the electrode combs. A control circuit 600 has the switches S1, S2, S3 and S4. The switch S1 is with its first connection to the busbar 6 the interdigital electrode assembly, while the first terminal of the switch S2 to the busbar 7 of the electrode comb 12 the interdigital electrode arrangement 10 connected is. The first terminal of the switch S3 is connected to the collecting electrode 6 of the electrode comb 11 the interdigital electrode arrangement 20 connected while their electrode comb 12 through his busbar 7 is connected to the first terminal of the switch S4. The switches S1, S2, S3 and S4 each have a first, a second and a third terminal. The switches are operated so that the first terminal is connected either to the second terminal or to the third terminal of the respective switch.

In the in 5 In the configuration shown, the first terminals of the switches S1 and S3 are respectively connected to their second terminals, while in the switches S2 and S4, the first terminal is connected to the third terminals. At the second terminals of the switches S1, S2, S3 and S4, the high potential is connected in each case, while at the third terminals in each case the negative potential is connected.

Thus, the electrode combs 11 the interdigital electrode arrangements 10 and 20 each charged to the high potential while the electrode combs 12 the interdigital electrode arrangements 10 and 20 are each connected to the negative potential. This circuit corresponds to the one in 3 shown wiring. Should the longitudinal extent corresponding 4 are loaded, the switches S1 and S2 are respectively switched so that the first terminal is connected to the second terminal, while the switches S3 and S4 each connect their first terminal to their second terminal.

In addition to the circuit 600 is still one in the 5 not shown circuit for processing the converted energy and a controller for setting the charging and discharging times.

7 shows a further embodiment of the interdigital electrode arrangements. These are different from those 2 in that the collecting electrodes are arranged differently. The collecting electrodes 11 the interdigital electrodes 10 . 30 and 50 as well as the collecting electrodes 12 the interdigital electrodes 10 . 30 and 50 are led out to the bottom and electrically contacted the collecting electrodes 11 and 12 the interdigital electrodes 20 . 40 and 60 be led out to the top. Thus, it is sufficient to provide only four switches S1, S2, S3 and S4 to contact all collecting electrodes as needed.

LIST OF REFERENCE NUMBERS

1

polymer

2

longitudinal extension

3

longitudinal extension

4

longitudinal extension

5

longitudinal extension

6

collecting electrode

7

collecting electrode

8th

longitudinal extension

10

Interdigitated electrode arrangement

11

electrode comb

12

electrode comb

20

Interdigitated electrode arrangement

30

Interdigitated electrode arrangement

500

arrangement

600

control circuit

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 602004008639 T2 [0002]
• US 2007/0257490 A1 [0003]

Claims (10)

Generator for converting mechanical energy into electrical energy, comprising: - a first interdigital electrode arrangement ( 10 ) with two interlinked electrode combs ( 11 . 12 ), - a second interdigital electrode arrangement ( 20 ) with two interlinked electrode combs ( 11 . 12 ), - electroactive polymer ( 1 ) between the electrode combs ( 11 . 12 ) of the first interdigital electrode arrangement ( 10 ), between the electrode combs ( 11 . 12 ) of the second interdigital electrode arrangement ( 20 ) and between the first interdigital electrode arrangement ( 10 ) and the second interdigital electrode arrangement ( 20 ), characterized in that a first control circuit (S1, S2) is provided for selectively switching the electrode combs of the first interdigital electrode arrangement ( 10 ) to different potentials or to the same potential. Generator according to claim 1, characterized in that a second control circuit (S3, S4) is provided for switching the electrode combs ( 11 . 12 ) of the second interdigital electrode ( 20 ) to different potentials or to the same potential. Generator according to claim 1 or 2, characterized in that each of the electrode combs ( 11 . 12 ) an interdigital electrode arrangement ( 10 ) each longitudinal extent ( 2 . 3 . 4 . 5 . 8th ), each of the longitudinal extensions ( 2 . 3 . 4 . 5 . 8th ) each one longitudinal extension ( 2 . 3 . 4 . 5 . 8th ) of the respective other electrode comb ( 12 ) of the same interdigital electrode arrangement ( 10 ) and that each of the electrode combs ( 11 . 12 ) each have a collecting electrode ( 6 . 7 ) having the longitudinal extensions ( 2 . 3 . 4 . 5 . 8th ) of the electrode comb ( 11 . 12 ), wherein at least one of the control circuits (S1, S2, S3, S4) for charging the collecting electrode ( 6 . 7 ) is set up with a potential. Generator according to one of claims 1 to 3, characterized in that the longitudinal extents of the electrode combs ( 11 . 12 ) are completely surrounded by the polymer. Generator according to one of Claims 1 to 4, characterized in that the first interdigital electrode arrangement ( 10 ) and the second interdigital electrode arrangement ( 12 ) are identically shaped. Generator according to claim 1 to 5, characterized in that the generator is designed as a wave energy generator. Generator according to claim 1 to 6, characterized in that the generator comprises a plurality of interdigital electrode arrays, which are arranged side by side in a cuboid. Method for operating a generator according to one of Claims 1 to 7, - charging of electrode combs ( 11 . 12 ), which are adjacent in a first spatial direction (y), to different potentials, - pulling the polymer apart such that the capacitance between the electrode combs adjacent in the first spatial direction (y) ( 2 . 3 ), - unloading the electrode combs ( 2 . 3 ) and then loading electrode combs which are adjacent in a second spatial direction (x) to different potentials, - pulling the polymer apart ( 1 ) such that the capacitance between the electrode combs adjacent in the second spatial direction (x) ( 2 . 3 ). A method according to claim 8, characterized in that the first spatial direction (x) and the second spatial direction (y) are perpendicular to each other. Method according to claim 8 or 9, characterized in that in the steps Charging of electrode combs adjacent in the first spatial direction (y) to a first potential difference, and Loading of electrode combs which are adjacent in the second spatial direction (x) to a second potential difference, the first potential difference is different from the second potential difference.

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