WO2011047404A2

WO2011047404A2 - Thermogenerator

Info

Publication number: WO2011047404A2
Application number: PCT/AT2010/000403
Authority: WO
Inventors: Michael Waste; Raimund Ratzi; Georg Leonardelli; Katrin Barbara Tauber
Original assignee: Miba Sinter Austria Gmbh
Priority date: 2009-10-23
Filing date: 2010-10-22
Publication date: 2011-04-28
Also published as: DE112010004107A5; WO2011047404A3

Abstract

The invention relates to a thermogenerator (1, 101) comprising several thermoelectric elements (2, 102) arranged over a length (11) thereof, wherein in each case two thermoelectric elements (2, 102) are arranged at a distance (10) from each other. At least one of the distances (10) between two thermoelectric elements (2, 102), in particular in the x- and/or y-direction, differs from the other distances (10) and/or the thermoelectric elements (2, 102) are arranged in a strip-like manner as element strips (3, 123). Furthermore, two thermoelectric elements (2, 102) can be electroconductively connected to a conducting element (4, 109) respectively, wherein the conducting element (4, 109) is connected with in each case two thermoelectric elements (2, 102) to an adhesive (110) or wherein the conducting element (4, 109) is applied onto two thermoelectric elements (2, 102), respectively, which are electroconductively connected to each other by means of a, particularly thermal, spraying process or by means of low-temperature connection technology.

Description

Thermal generators

The invention relates to a thermogenerator comprising a plurality of thermoelectric elements distributed over a length, wherein each two thermoelectric elements are arranged at a distance to each other, a thermoelectric generator comprising a plurality of thermoelectric elements distributed over a length, each two thermoelectric elements arranged at a distance from each other and with a Guide element are electrically connected, and a device for generating electrical energy from heat, comprising a heat source and at least one thermal generator.

Increasing energy costs as well as increased environmental awareness have recently been forcing systems to extract electrical energy from waste heat that has been released to the environment in the past. As is known, in internal combustion engines, the efficiency is well below 100%. Exhaust gases of motor vehicles, which are discharged via the exhaust system to the environment, usually still have temperatures of several 100 ° C. On the other hand, it has long been known in the prior art to use so-called thermoelectric modules in order to generate electric current from heat sources. As is known, such thermoelectric modules deliver electrical current when there is a temperature difference due to the Seebeck effect. These modules are therefore also called Seebeck modules.

Thermoelectric modules are now manufactured in the form of arrays to almost reach the voltage required in the load circuit. These arrays are designed for use in a stationary temperature environment that is as uniform as possible over the area of the array. In addition, these arrays are usually used in combination with so-called heat spreaders in order to achieve the most uniform possible distribution of the heat emitted by the heat source to the array. Such a thermoelectric module is known for example from DE 10 2007 063 168 AI. This consists of arranged in a first position, electrical guide elements, arranged in a second, spaced apart from the first layer position, electrical guide elements, from a disposed between the first layer and the second layer plurality of thermoelectric elements, of at least one insulating layer, by means of which the arranged in the first layer, the electrical guide elements relative to a heat source or arranged in the second layer, electrical guide elements are electrically insulated relative to a heat sink. The at least one insulating layer is formed from a plurality of Isolierschichtabschnitten, which are separated from each other. As a heat source, the exhaust system is called a discontinuous combustion device, in particular an exhaust system of the internal combustion engine of a motor vehicle. It is thus achieved the task of creating a thermoelectric module, which to enable a good Wir- "degree of efficiency, a compact design and as tension-free operation of a thermoelectric generator.

Comparable thermoelectric modules are also described in DE 10 2007 063 173 AI and DE 10 2007 063 196 AI. The object of the present invention is to further develop a thermal generator or a device for generating electrical energy from heat such that this or these can be better integrated into the temperature field of an exhaust system of a motor vehicle, in order to improve their or their cost-effectiveness. This object is achieved independently by the above-mentioned thermal generator in which at least one of the distances between two thermoelectric elements, in particular in the x and / or y direction, is different from the further distances between two thermoelectric elements and / or in which these Thermoelectric elements are arranged in strips, and by the aforementioned device for generating electrical energy from heat which comprises at least one thermal generator according to the invention.

Another object of the present invention is to improve one

Thermogenerator or an improved device for generating electrical energy from heat to create such.

This object of the invention is achieved independently by a thermogenerator mentioned above, in which the guide element with two thermoelectric Elements is connected to an adhesive or that the guide element is applied to each two electrically conductively connected thermoelectric elements by a, in particular thermal, spraying or by means of low temperature connection technology, or in which the thermoelectric elements are arranged on a DCB substrate, and by the above said device for generating electrical energy from heat in which the thermal generator is designed according to the invention.

In the context of the invention, a thermoelectric generator is understood to mean a thermoelectric generator for converting thermal energy into electrical energy.

As a result of this variable arrangement of the thermoelectric elements, it becomes possible to better compensate for temperature field fluctuations, that is to say fluctuations in the temperature with which the inventive thermogenerator or the device according to the invention is applied during operation, so that one thereby causes

This has the consequence that the power output of the device according to the invention in comparison with known devices of the prior art with the same effective volume of thermoelectric elements at least substantially by this "detuning" is not adversely affected, that is, that the power output does not decrease massively by such temperature fluctuations. The reason for the decrease in the power output in known, thermoelectric generators is that the voltage-emitting, thermoelectric elements are connected in series, in order for the subsequent voltage conversion to electrical system level, that is to the level of the motor vehicle, favorable starting base for a high Have converter efficiency. However, this causes a poor voltage yield in the case of small-scale temperature changes, since thermoelectric elements of high voltage are connected in series with those of low voltage. In addition, can be achieved with the inventive arrangement of the thermoelectric elements, a longer life of the thermal generator or the device according to the invention, since said small-scale temperature differences are not or not essential leads to a tightening of the mechanical stress of the thermo generator according to the invention or the device according to the invention.

Due to the strip-shaped arrangement of the thermoelectric elements and their handling during installation easier to make and thus the number of

External connections are reduced. In particular, this makes it possible to adapt these thermoelectric elements according to their distribution in the available heat source or vice versa, the distribution of the available amount of heat from the heat source accordingly, for example, by the thermoelectric elements are arranged at a lower density than in that area when entering the hot gas, in which the hot gas has already experienced a cooling.

It should be noted that, in principle, there is the possibility that the thermoelectric elements are combined to form an element strip, but in the context of the invention the division of the thermoelectric elements onto a plurality of element strips is preferred. Furthermore, there is the possibility that an element strip consists only of a thermoelectric element.

Due to the adhesive bond or the layer produced by thermal spraying can be made relatively thin, whereby a longer life of the thermal generator or the device according to the invention can be achieved as small-scale

Temperature differences do not or not significantly lead to a tightening of the mechanical stress of the thermal generator or the device according to the invention. To further improve this effect, in particular the adhesive layer can be equipped within certain limits with a flexibility, for example by running it with a higher layer thickness, whereby the mechanical stress of the contact points during use of the thermal generator can be further reduced. In addition, thus a good bond strength of the compound can be achieved and the said connection methods in industrial manufacturing are well manageable, whereby the industrial production of thermal generators - many of which are still assembled by hand - is made possible, and as a result high-quality Thermogeneratioren are cheaper to produce , By using a DCB substrate for the arrangement of the thermoelectric elements, the advantage is achieved that, with simple means, different surface sizes and shapes can be made available for different arrangements of the thermoelectric elements. In addition, it can be a relatively even

Surface are provided, which is in the further industrial production of the thermal generator, in particular with regard to the arrangement of the thermoelectric elements, an advantage. In addition, a complete array of thermoelectric elements can be constructed inexpensively and the variability of array design is also advantageous.

According to an embodiment variant of the invention, it is provided that the distance between two thermoelectric elements changes over the length of the thermal generator with an exponential function. It can thus be further improved the efficiency of the device according to the invention.

It is also possible that a longitudinal extent of the element strip formed by the strip-shaped thermoelectric elements is aligned at least approximately perpendicular to a predeterminable flow direction of the heat flow from the heat source, so that the element strips are each preferably aligned parallel to the isotherms of the device for generating electrical energy , Essentially, therefore, the element strips are at least approximately at right angles to the flow direction of an exhaust system of a motor vehicle or generally to the flow direction of the heat flow of a heat source. It is advantageous that small temperature fluctuations in the individual zones or layers of the heat flow, that is, for example, in the exhaust gas flow, have a smaller influence on the voltage of the generated electrical energy.

At least two of the element strips can be combined to form a module, wherein the thermal generator comprises at least one such module. Preferably, several such modules are distributed over the length of the thermal generator. Due to the modular design, a faster assembly of the thermal generator is possible and beyond the adaptation to different heat sources with different temperatures is simplified by the modular design. The replacement of entire modules is thereby simplified, in particular with regard to the contacting. The module can be housed at least partially. On the one hand to facilitate the handling of the modules, on the other hand to better protect the module against the attack of corrosive constituents of an exhaust gas. In the space between two thermoelectric elements, at least one insulating element can be arranged. On the one hand, a corresponding thermal insulation or a reduction of the heat radiation can be achieved, which in turn the efficiency of the device or the thermal generator can be improved, on the other hand, the insulating element also serves the better electrical insulation of the thermoelectric elements.

The arrangement of the thermoelectric elements in strip form, it is possible that they are contacted at the opposite longitudinal extension in the distal end regions. It can thus be achieved the advantage that these contact points are also arranged outside the application of heat in a range which is less critical with respect to the corrosive attack and / or the temperature load, whereby a better protection of these contacts is possible.

Due to the modular design, it is also possible that several element strips are optionally electrically connected together in series or in parallel in the thermogenerator in order to achieve a better adaptation to the respective voltage requirements, and thus also to achieve a higher efficiency.

Preferably, the thermoelectric elements are formed from a skutterudite or powder composition of the class of skutterudites. In particular, this material, filled or unfilled, has proven to be advantageous because of its resistance in the field of high temperature applications of thermoelectric elements in automotive exhaust systems.

According to another embodiment variant, it is provided that at least two element strips are arranged one above the other in the thermogenerator, which in turn can increase the efficiency of the thermogenerator. Of course, the arrangement of several element strips in the flow direction of the heat flow, that is, for example, the exhaust gases, can be continued. A ratio of the length in millimeters to the cross-sectional area in square millimeters of the thermoelectric elements can be selected from a range with a lower limit of 1: 100 and an upper limit of 4: 1. In the course of testing the invention, with such geometrical dimensions particular effect can be observed with regard to the efficiency of the thermogenerator.

The thermoelectric elements preferably have a rectangular cross-section - viewed in the direction of the longitudinal extent. Although other cross-sectional shapes are also possible in principle, rectangular cross-sections have proven to be advantageous both in terms of the degree of efficiency and in terms of installation and handling of the thermoelectric elements in the course of testing the invention.

According to an embodiment variant of the thermogenerator, it is provided that the adhesive is an oxygen-curing adhesive. It is thus achieved that oxygen, which is optionally present on the surface of the thermoelectric elements, is consumed by the setting reaction of the adhesive, whereby the use of oxidation-sensitive materials for the thermoelectric elements can be simplified.

Between the guide element and the thermoelectric elements, a diffusion barrier layer may be arranged to prevent the diffusion of constituents of the material of the guide element, in particular when it is applied to the thermoelectric elements by a thermal spraying method. In addition, the

Diffusion barrier layer but also advantages in view of the high temperatures when using the thermal generator, especially when it is integrated into an exhaust system of a motor vehicle. It is thus possible for the guide element to use materials from which at the prevailing temperatures there is a risk that components diffuse into the thermoelectric elements. This results in the advantage that with regard to the choice of material for the guide element but also for the thermoelectric elements - the diffusion barrier layer can also be designed so that it prevents diffusion from the thermoelectric elements into the guide element - a larger bandwidth is possible, whereby special Material combinations for the guide element and the thermoelectric elements essentially does not have to be taken into account, so even materials can be used for the elements, which allow a higher energy yield. It also improves the long-term stability of the thermogenerator.

The thermoelectric elements have a top surface, a bottom surface and side surfaces lying between them, wherein at least one of the side surfaces

Oxidation barrier layer and / or a sublimation barrier layer can be arranged so that the thermoelectric element better against environmental influences, such as. the

To protect the risk of oxidation or sublimation under the prevailing high temperatures of material components, resulting in the loss of active thermoelectric Matrial and thus the reduction of the degree of rotation.

The thermoelectric elements may be arranged meandering on the DCB substrate for better handling and minimizing the number of external terminals. For a simpler production of larger modules to achieve a good thermal cycling is possible.

It is possible that the DCB substrate is arranged between the meandering

thermoelectric elements having recesses in order to better compensate for thermal stresses during use of the thermal generator, whereby the

Thermoelectric elements and the contact points can be better protected against damage due to the thermal load of the thermogenerator.

Preferably, these recesses are slit-shaped, so that therefore the DCB substrate is substantially adapted to the meandering course of the arrangement of the thermoelectric elements, whereby the above-mentioned effect of avoiding damage to the thermoelectric elements and the contact points can be improved.

To reduce the notch effect, at least one corner region of the recesses can be rounded.

The DCB substrate may additionally be metallized on the underside, whereby the flatness of the substrate and the heat dissipation is improved. With underside is that page or Surface facing the surface having the thermoelectric elements.

The thermoelectric elements can be housed at least partially, on the one hand to simplify the handling of the thermoelectric elements, on the other hand to better protect the thermoelectric elements against the attack of corrosive constituents of an exhaust gas or from the ambient air or by (spray) water or water vapor. Preferably, the heat source is an exhaust system of a motor vehicle, whereby the

Energy efficiency of a motor vehicle can be improved.

But it is also possible that the heat source is associated with a heat exchanger on which the thermoelectric elements or the thermal generator are or will be arranged. By this embodiment of the invention, a simple installation or replacement in the event of a repair of the thermal generator is possible by namely the entire heat exchanger can be exchanged. On the other hand, however, a better utilization of the energy in exhaust gas is possible by this exhaust gas is at least partially recycled in the heat exchanger, in turn, in this feedback region thermoelectric elements can be arranged. In this case, the arrangement of the thermoelectric

Elements with variable distance from each other, that is, with different occupation density over the length of the heat exchanger, proven advantageous because the hot exhaust gases gradually cool over the length of the heat exchanger. Nevertheless, higher densities with thermoelectric elements in colder zones mean that a corresponding voltage can be achieved, due to the lower occupation density at the beginning of the

Heat exchanger, that is in the inlet region of the hot exhaust gases, no voltage spikes occur. It is also possible in this case that the heat exchanger for the guidance of the hot exhaust gases is designed meandering. For a better understanding of the invention, this will be explained in more detail with reference to the following figures.

Each shows in a schematically simplified representation: 1 shows a first embodiment of a device according to the invention with strip-shaped thermoelectric elements arranged in an oblique view.

2 shows an element strip in side view;

Fig. 3 shows the arrangement of thermoelectric elements on a heat exchanger in

Side view cut;

Fig. 4 shows an embodiment of the thermoelectric elements in modular design in

Side view cut;

FIG. 5 a side view of a variant of a device according to the invention with a meandering heat exchanger tube; FIG.

6 shows a detail of a thermogenerator in an exploded view;

Fig. 7 shows the detail of FIG. 1 with an additional thermoelectric element in

Tilt;

8 is a plan view of a DCB substrate with partially arranged thermoelectric elements;

9 shows an embodiment variant of a thermogenerator according to the invention with stripe-shaped thermoelectric elements in oblique view;

10 shows an element strip in side view;

11 shows the arrangement of thermoelectric elements on a heat exchanger in FIG

Side view cut;

Fig. 12 shows an embodiment of the thermoelectric elements in modular design in

Side view cut; 13 shows a variant of a device according to the invention with a meandering heat exchanger tube cut in side view.

By way of introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component names, wherein the disclosures contained in the entire description can be mutatis mutandis to the same parts with the same reference numerals or component names. Also, the location information chosen in the description, such as top, bottom, side, etc. related to the immediately described and illustrated figure and are to be transferred to the new situation mutatis mutandis when a change in position. Furthermore, individual features or combinations of features from the different exemplary embodiments shown and described can also represent independent, inventive or inventive solutions. In Fig. 1, a thermal generator 1 according to the invention is shown in an oblique view. This comprises in the illustrated variant a plurality of thermoelectric elements 2, which are arranged in strips to form six element strips 3, wherein the thermoelectric elements 2 may be interconnected within an element strip 3, so that the element strips 3 may be integrally constructed of several parts. One of the element strips 3 is shown in Fig. 2 in side view. The thermoelectric elements 2 consist of a semiconductor material and are p-doped and n-doped, with a sequence of alternating p- and n-doped, thermoelectric elements 2 being arranged in the thermal generator 1 or in the element strips 3. However, it is also possible within the scope of the invention that the element strips 3 each consist of a thermoelectric element 2, so that therefore the element strips 3 are each only p- or n-doped. However, an element strip 3 preferably has at least one p-type and at least one n-doped thermoelectric element 2.

Furthermore, it is not absolutely necessary, although preferred, for the element strips 3 to be straight. For example, an element strip 3 may also be formed meander-shaped. Of course, the thermal generator 1 may also have less than or more than six such element strips 3, that is, for example, two, three, four, five, seven, eight, nine, ten, etc. The thermoelectric elements 2 are electrically conductively connected to one another via guide elements 4, wherein the contact is made such that the thermoelectric elements 2 are connected in series with each other. As can be seen from FIG. 1, the contacting of the thermoelectric elements 2 with the guide elements 3 preferably takes place in the distal end regions 5 of the element strips 3. The contacting can, however, also be arranged in another region of the thermoelectric elements 2.

It should be noted at this point that in Fig. 1, only the contacting of the element strips 3 is shown together. The contacting of the thermoelectric elements 2, as shown in FIG. 2, is not shown in FIG. 1 for reasons of better illustration.

It is also possible that between the thermoelectric elements 2 and the guide elements 4, one or more intermediate layers are arranged and connected thereto. It is also possible that the contacting of the element strips 3 with each other as shown in Fig. 1 alternately top and bottom or these contacts are each arranged on the same side, ie only above or only below, based on the relative position of the element strips 3 in Fig. 1. Within an element strip 3, the individual thermoelectric elements 2 are connected in series with each other in an electrically conductive manner.

For tapping the voltage generated in the thermoelectric elements 2 electrical lines 6, 7 are provided in the form of a positive pole 8 and a negative pole 9, wherein these two terminals 5, 6 are in turn arranged in the distal end portions 5 of the element strips 3 and After the thermoelectric elements 2 are contacted with each other in series, respectively, these terminals 5, 6 are formed on the first and last element strips 3, respectively, as shown in FIG. The guide elements 4 are electrically conductively connected to the thermoelectric elements 2 or element strips 3. When selecting the connection method or contacting method and the materials used for the guide elements 4, the temperature prevailing at the place of use must of course be taken into consideration, in particular if the thermal generator 1 is preferably in an exhaust system of a motor vehicle, for example before or after the catalytic converter of an exhaust system a motor vehicle, is arranged, as can prevail in these areas temperatures up to 700 ° C. In any case, an interruption of the contacts must be avoided. After such uses of thermoelectric generators for exhaust systems of motor vehicles is already known, for example, from the documents mentioned above for

State of the art, further explanations are unnecessary for this, since the skilled person will select suitable materials and connection methods on the basis of his specialist knowledge.

The thermoelectric elements 2 and, as a consequence, the element strips 3, as shown in FIG. 1, preferably have a rectangular cross section. However, it is within the scope of the invention, although this is not the preferred embodiment, to choose other cross-sectional shapes, such as square, hexagonal, octagonal, round, etc. As a base material for the production of the thermoelectric elements 2 is preferably a skutterudite or a powder composition from the class of Skutterudite or a corresponding mixture of the respective elements used. Skutterudites have the advantage, in particular with regard to the temperature resistance compared to conventional semiconductor materials, that they can be exposed to a higher temperature load and, in addition, that better efficiencies can be achieved.

Within the scope of the invention with the thermogenerator 1, it is possible to achieve efficiencies of up to almost or just over 10%, whereas to date, efficiencies of around 6% have been achieved with thermoelectric generators from the prior art.

Depending on the design of the thermoelectric elements 2 as a p or n element, this base material from the class of skutterudites is p-doped or n-doped accordingly. For the dotie For example, at least one of Ba, Ca, Ce, Eu, Fe, Ge, In, La, Nd, Ni, Os, Pd, Pr, Pt, Ru, Sm, Sn, Sr, Te, Yb can be used.

Although the use of skutterudites is the preferred embodiment of the invention, it is also possible within the scope of the invention to use other semiconductor materials, in particular for temperature applications well below 700 ° C. Examples of these are Bi ₂ Te ₃ / Sb ₂ Te ₃ , PbTe-PbSe-PbS, (SiGe), Chlatrate, such as Ba 8 Ga ₆ Ge ₃ o, Zn ₄ Sb ₃ , etc. The element strips 3 are at a distance 10 to each other arranged. According to the invention, it is now provided that this distance 10 over an entire length 11, which is indicated in Fig. 1 with an arrow and over which the individual, element strips 3 are arranged distributed, is not constant, but this distance 10 changes over this length 11. At least one of the distances 10 between two element strips 3 is different from the further distances 10 between the element strips 3, that is to say that in the simplest case, the remaining distances 10 can be constant except for one of the distances 10 and only one of the distances 10 be different. In the preferred embodiment, that is, depending on the temperature field in which the thermal generator 1 is arranged, however, these distances 10 are generally variable, so that these distances 10, ie their values, change over the entire length 11 between each of the element strips 3. In particular, the distance 10 between two elemental strips 3 in that region in which the temperature is greatest will be greatest and will already prevail in areas in which due to the cooling of the heat source, for example the exhaust gases of a motor vehicle, lower temperatures prevail the distance 10 is reduced accordingly. In other words, the density of the arrangement of the Elmentestreifen 3, and thus the thermoelectric elements 2, in the temperature field of the heat source over the length 11 of the thermal generator 1 is varied, wherein in the relatively lower temperature regions, a higher density of thermoelectric elements 2 is arranged as in areas of relatively high temperature. It is thus achieved that the efficiency of the thermal generator 1, that is, the efficiency of the thermal generator 1, can be improved by namely voltage fluctuations due to the temperature fluctuations in the thermal generator 1 can be better compensated or better taken into account. In addition to the formation of a variable distance 10 between the element strips 3 in the x direction, there is also the possibility within the scope of the invention that, alternatively or additionally, the distances in the y direction, ie the distances between the individual thermoelectric elements 2, be varied ,

It is further preferred, after the preferred use of the thermal generator 1 in an exhaust system of a motor vehicle is that the element strips 3 vertically, that is at least approximately at right angles to the flow direction of the exhaust gases or in other words perpendicular to the longitudinal extent, that is the length 11th of the thermal generator 1 are aligned, as shown in Fig. 1.

FIG. 3 shows a device 12 which, in addition to the thermogenerator 1, also comprises a heat exchanger 13 as a heat source for the thermogenerator 1. In the simplest case, this heat exchanger 13 is formed by a heat exchanger tube or a heat exchanger profile with at least approximately rectangular cross section, wherein according to arrow 14, the exhaust gases forming the primary heat source are introduced into this heat exchanger profile and flow through this. On the outer surface of the heat exchanger 13, that is, the heat exchanger profile, the thermoelectric elements 2 of the thermogenerator 1 in the form of the element strips 3 are arranged, according to the statements to the thermogenerator 1 according to FIG. 1. In particular, the element strips 3 by means of a connecting means 15th be thermally conductively connected to the surface of the heat exchanger 13 and the heat exchanger profile. Such connection means 15 are known from the prior art. Also in this embodiment of the invention, the distance 10 between two element strips 3 in the flow direction of the exhaust gases according to arrow 14 over the length 11 of the device 12 is varied according to the invention, wherein upon entry of hot exhaust gases (in the left part of Fig. 3) in the heat exchanger 13 the distance 10 is selected to be greater than when the exhaust gases exit (in the right-hand part of FIG. 3) from the heat exchanger 13.

Dashed line is indicated in Fig. 3, that the device 12 can be housed at least approximately entirely with a sheath 16, whereby the thermoelectric elements 2 can be better protected against environmental influences. In particular, this also creates a Device 12, which can be installed as an entire unit in the exhaust system of a motor vehicle, so for example in the exhaust pipes, or this device 12 can even replace a part of an exhaust pipe of a motor vehicle, similar to the installation of a catalyst.

In the lower part of FIG. 3, a possible temperature profile over the length 11 of the device 12 is shown. The temperature decreases in curves. For this embodiment, it is advantageous that when the distances 10 between the individual, element strips 3 are changed over the length 11 with an exponential function.

It should be noted, however, that other temperature profiles over the length 11 are possible. It is precisely here that the invention has the advantage that, due to the strip-shaped arrangement of the thermoelectric elements 2, a variable arrangement over the length 11 of the device 12 becomes possible, that is to say that the distances 10 correspond to the expected temperature profile of the heat source over the length 11 can be adapted to the device 12, so that a further optimization of the economy of the device 12 can be achieved.

In a modification to this, it is possible, as shown in FIG. 2, that as an alternative or in addition to the housing of the device 12, the individual element strips 3 may also be provided with a covering 17.

4, a section of a device 12 is shown in cross section. In particular, in each case two element strips 3 of the thermal generator 1 are combined to form a module, wherein in this embodiment, between the element strips 3 of a

Module, ie in the x direction, an insulating member 18 is arranged, which preferably fills the entire area between the element strips 3. The insulating element 18 consists of an electrically and thermally insulating material, for example of a ceramic. With the aid of the insulating element 18, a reduction of the heat radiation is achieved by the thermoelectric elements 2, whereby the efficiency of the thermal generator 1 can be improved. Alternatively or additionally, it is also possible, as shown in Fig. 2, that between the thermoelectric elements 2, ie in the y direction, such insulating elements 18 are arranged. The device 12 according to FIG. 4 comprises at least two of these modules, wherein optionally the area between the modules can also be filled with an insulating element 16, not shown, if required. The modules themselves may in turn be connected via a connecting means 15 to the surface of the heat exchanger 12. Likewise, an ontaktierung by means of the guide elements 4 between the modules, whereby a total structure results, which is similar to that of FIG. 1, so the thermoelectric elements 2 are connected in series in series with each other.

However, it should be noted at this point that it is possible within the scope of the invention that such modules can be electrically connected to one another not only serially but also in parallel, wherein also mixed forms of serial and parallel are possible.

According to the invention, however, a module can also have only one element strip 3, as shown in FIG. It is therefore not absolutely necessary for a module to comprise a plurality of element strips 3.

Furthermore, it should be pointed out that it is of course possible for more than two modules, for example three, four, five, six, etc., to be arranged in the device 12 or in the thermal generator 1, and on the other hand for a module to have more as two element strips 3, for example, three, four, five, six, etc., may have.

Furthermore, it is possible that the modules not only include the thermoelectric elements 2 and possibly the insulating elements 18, but a complete, modular design of the device 1 takes place, so that the modules include the heat exchanger 13 and in the subsequent application, the individual modules accordingly of the invention with non-constant distance 10 between the element strips 3 over the length 11 in or on one

Heat source, so for example, the exhaust system of a motor vehicle, are arranged. Finally, FIG. 5 shows a variant embodiment of the device 12 in which the heat exchanger 13 is meander-shaped, that is, the heat exchanger profile has at least one return, wherein the heat exchanger profile according to the embodiment of FIG. 5 in the illustrated cross-sectional variant is S-shaped.

It should be noted at this point that it is possible within the scope of the invention for the heat exchanger 13 to comprise a plurality of heat exchanger profiles and to be arranged on at least a plurality of the heat exchanger profiles, preferably on all, thermoelectric elements 2.

With the embodiment according to FIG. 5, on the one hand a more compact design of the device 12 is achieved, whereby here again a further increase in the economic efficiency of the device 12 according to the invention can be achieved, namely by lengthening the length 11 (FIG and thus more thermoelectric elements 2 can be arranged in the device 12.

It should be pointed out that the thermoelectric elements 2 in FIG. 5 are only indicated more in the modular design according to FIG. 4 and reference is made to details for this, for example, to the embodiment according to FIG. 4 or FIG.

Furthermore, there is the possibility that the thermoelectric elements 2 and the modules are arranged not only in the flow direction of the exhaust gases according to arrow 14 in succession, but that as shown in Fig. 5 is shown in broken lines, such modules or element strips 3 are also arranged one above the other , In this case, the modules can lie directly against one another or else be arranged at a distance from one another. Such a possibility of arrangement exists both in the thermal generator 1 and in the device 12.

There is also the possibility of a sheath 16 of the entire device 12, as indicated in phantom in Fig. 5.

It is also possible within the scope of the invention for the modules themselves to be at least partially enclosed, as indicated in FIG. 4 by the partial arrangement of the enclosure 16 on the modules, wherein in the specific embodiment according to FIG. ment 16 extends over at least a portion of both modules shown. However, within the scope of the invention, it is possible that each module has at least partially such a casing 16 for itself, which can have mutually corresponding recesses at the corresponding points for contacting, that is to say for the electrically conductive connection of the individual modules to arrange the electrical guide elements 4.

The sheath 16 may be made of plastic, a ceramic or preferably of metal or of combinations of these materials, for example.

The thermoelectric elements 2 preferably have a height 19 (FIG. 1) of at least 1 mm. This height 19 is oriented perpendicular to the entire length 11 of the device 12 and the thermogenerator 1, as shown in Fig. 1. A cross-sectional area of the thermoelectric elements 2, viewed in the direction of a contacted end face of the thermoelectric elements 2, is preferably at least 4 mm

According to a further preferred embodiment, a ratio of the height 19 in millimeters to the cross-sectional area in square millimeters of the thermoelectric elements 2 is selected from a range with a lower limit of 1: 100 and an upper limit of 4: 1, wherein the ratio is considered dimensionless is.

There is also the possibility that the thermoelectric elements 2 and / or the element strips 3 have a different cross-section, so for example the

Cross-section of the individual thermoelectric elements 2 or the element strips 3 in the direction of the length 11 of the device 12 and the thermogenerator 1 is greater.

In addition, it should be noted that in the context of the invention an element strip 3 is understood to be an element whose length is at least twice, preferably at least four times, in particular six times, as large as the smallest dimension defining the cross section of the element. With an edge length of 1.5 mm of a rectangular cross-section (in the sense of the definition, the shorter edge length of the two edge lengths is used here). means) so the length can be at least 3 mm. So it has the strip on a significant length.

It is further possible to increase the efficiency that another heat exchanger is arranged with at least one coolant line.

Preferably, the thermoelectric elements 2 and the thermoelectric generator 1 are operated by utilizing the Seebeck effect, which is known to generate an electrical voltage by the different temperature at the different semiconductor materials. However, there is always the possibility with such thermoelectric elements 2 that they are operated by utilizing the Peltier effect, ie that power is supplied and thus a cooling of the environment of the thermoelectric elements 2 is achieved. Although the thermoelectric elements 2 can in principle be produced by processes known from the prior art, they are preferably produced by means of a sintering process in such a way that no or only minimal reworking of the elements 2 is required. Reference is here made to the filed with the Austrian Patent Office on the same day application with the title "Method for producing a thermoelectric element", which counts in this scope of the sintering process to the disclosure of this invention, in particular the execution of 90 ⁰ to the pressing direction twisted arrangement of the elements 2 in the thermal generator 1 and the device 12. FIGS. 6 and 7 show a detail of a preferred embodiment of a

Thermogenerators 101 in exploded view or oblique view. This thermoelectric generator 101 comprises a plurality of thermoelectric elements 102. In FIGS. 6 and 7, only one or two such thermoelectric elements are shown for better illustration. Although it is possible within the scope of the invention for the thermogenerator 101 to have only two of these thermoelectric elements 102, it is preferred for reasons of achievable performance that the thermoelectric generator 101 has more than two thermoelectric elements 102, the exact number of thermoelectric elements 102 directed to the desired voltage. For example, the thermal generator 101 a Array of thermoelectric elements 102 having between 20 and 300 thermoelectric elements 102.

As base material for the production of the thermoelectric elements 102, a skutterudite or a powder composition from the class of skutterudites or a corresponding mixture of the respective elements is preferably used. Skutterudites have the advantage, in particular with regard to the temperature resistance compared to conventional semiconductor materials, that they can be exposed to a higher temperature load and, in addition, that better efficiencies can be achieved.

Within the scope of the invention with the thermogenerator 101, it is possible to achieve efficiencies of up to approximately or just over 10%, whereas to date, efficiencies of around 6% have been achieved with thermoelectric generators from the prior art. Depending on the design of the thermoelectric elements 102 as a p or n element, this base material from the class of skutterudites is p-doped or n-doped accordingly. For doping, for example, at least one of Ba, Ca, Ce, Eu, Fe, Ge, In, La, Nd, Ni, Os, Pd, Pr, Pt, Ru, Sm, Sn, Sr, Te, Yb may be used become. Although the use of skutterudites is the preferred embodiment of the invention, it is also possible within the scope of the invention to use other semiconductor materials, in particular for temperature applications well below 700 ° C. Examples include Bi2Te3 / Sb2Te3, PbTe-PbSe-PbS, (SiGe), Chlatrate, such as Ba8Gal6Ge30, Zn4Sb3, etc.

Preferably, the thermoelectric elements 102 are manufactured by a sintering process. These can be prepared as already finished elements or cut out of a larger sintered block or a sintered plate. The thermal generator further comprises a substrate 103 on which the thermoelectric elements 102 are arranged. This substrate 103 is formed in particular planar and preferably consists of a ceramic. For example, the substrate 103 may be selected from at least one ceramic selected from the group consisting of or consisting of Al 2 O 3, AlN, Si ₃ N ₄ and glass ceramics. In the preferred embodiment of the thermogenerator 1, the substrate 103 consists of A1 ₂ 0 _3rd

The substrate 103 is preferably provided on at least one surface 104 with a metallic layer 105, preferably also on the surface 104 opposite

Surface 106. The metallic layer 105 is formed by copper or a copper alloy. The metallic layer (s) 105 are in particular applied directly to the substrate 103, for example by vapor deposition of the substrate 103. The substrate 103 may have a layer thickness selected from a range with a lower limit of 0.1 mm, in particular 0 , 3 mm and an upper limit of 2 mm, in particular 1.5 mm.

The metallic layer 105 may have a layer thickness selected from a range having a lower limit of 0.1 mm and an upper limit of 0.5 mm, especially 0.3 mm.

According to a preferred embodiment of the invention, the substrate 103 is formed by a DCB substrate (DGB = direct copper bonded), as they are known from semiconductor technology.

Between the thermoelectric elements 102 and the substrate 103, a diffusion barrier layer 107 is preferably disposed on a bottom surface of the thermoelectric elements 102. The diffusion barrier layer 107 may be in direct contact with the respective thermoelectric element 103. For this purpose, the thermoelectric element 102 may be coated with the material for the diffusion barrier layer 107, for example by a PVD method, such as e.g. Magnetron sputtering, atomic layer deposition (ALD), laser ablation. As the material for the diffusion barrier layer 107, a material selected from a group consisting of Nb, Ni, W, Mo, Ru, Pd, Ti, Ta is preferably used. Preferably, the diffusion barrier layer 107 is nitrides of these elements.

The diffusion barrier layer 107 may have a layer thickness selected from a range having a lower limit of 60 nm and an upper limit of 100 μm. The thermoelectric element 102, optionally with the diffusion barrier layer 107 arranged, is connected to the substrate 103, which is the cold side of the thermal generator 101, via a connection layer 108 arranged between the thermoelectric element 102 and the substrate 103. This bonding layer 108 may be made as a soldering layer by soldering or by NVT (Low Temperature Bonding) technique. The material for the connecting layer 108 may be adapted to the respective materials of the further layers of the thermal generator, for example, be formed from a Mo-Cu, a Fe-Ni or a Ni-Ti alloy. The connection layer 108 may have a layer thickness selected from a range having a lower limit of 10 μτη and an upper limit of 300 μκα.

On the hot side opposite the substrate 103, in each case two thermoelectric elements 102 of the thermogenerator 101 arranged next to one another are electrically conductively connected to one another via a conductor element 109.

The electrically conductive connection of two juxtaposed thermoelectric elements 102 on the cold side in the region of the substrate 103 takes place in the illustrated embodiment via the metallic layer 105, in particular over a copper layer. The electrically conductive connection is made in such a way that the thermoelectric elements 102 are connected in series, ie that the two juxtaposed thermoelectric elements 102 are connected in an electrically conductive manner alternately on the cold side and the hot side. As a material for the guide member 109 is a metal or a metal alloy can be used, or the selected comprising or consisting of Mo, Cu from the group Mo ₅ OCU _50, Mo ₇₀ Cu ₃₀ Fe-Ti alloys, Fe-Ni alloys. Preferably, the guide element 109 consists of Mo ₆₅ Cu35 or of a Ni-Ti alloy or a Fe-Ni alloy, in particular with an oxidation protective coating. Preference is given here Ni-Ti alloys or an Fe-Ni alloys used which a Wäremausdehnungs- coefficient of maximum ΙΟχΙΟ ^"6 K ^{" 1} and / or an electrical conductivity of at least 4 × 10 -6 m- ¹ and / or a thermal conductivity of at least 15 W / mK For example, a FesoNiso can be used. It should be noted that the oxidation protection coating of a guide element 109 can represent an independent invention, regardless of how the thermo generator 101 is further constructed or which materials are used for the individual layers. In particular, in this case the connection of the guide element 109 via an adhesive layer or a sprayed-on layer or a layer produced according to a low-temperature connection technique is advantageous but not absolutely necessary. In other words, a guide element 109 for thermal generators 101 provided with the oxidation protection coating or at least one oxidation protection layer constitutes an independent invention.

The guide element 109 may have a layer thickness selected from a range having a lower limit of 0.1 mm and an upper limit of 1.5 mm.

The connection of the guide element 109 is carried out according to a first embodiment via an adhesive 110 which forms an adhesive layer 111. The adhesive 110 may, for example, consist of an inorganic binder composition in which silver particles are contained. In particular, a high temperature adhesive is used. 110 pyro- ^® is particularly preferred as an adhesive duct used. According to a preferred embodiment, an adhesive 110 is used, the required oxygen to setting or hardening, such as Pyroduct ^®.

In order to be able to better avoid a stress rupture of the adhesive layer 111, preference is given to using an adhesive 110 whose thermal expansion coefficient has a value of not more than ± 20%, in particular not more than ± 10%, of the thermal expansion coefficient of the material of the thermoelectric elements.

The adhesive layer 111 may have a layer thickness selected from a range with a lower limit of 10 μηι and an upper limit of 300 μπι.

According to another embodiment, the guide element 109 by means of a, in particular thermal, spraying method, such as plasma spraying, flame spraying, HVOF, plasma precision syringes, or combinations of these methods, or by means of low-temperature Connection technology, such as silver sintering, sprayed directly onto the thermoelectric elements 102 to be joined on the top surface. Since the thermal spraying processes are known in principle, reference is made to the relevant literature for further details. The guide element 109 in this case may have a layer thickness selected from a range with a lower limit of 0.2 mm and an upper limit of 2 mm.

It is further possible for a diffusion barrier layer 112, which is connected to the thermoelectric element 102 and the adhesive layer 111 or the guide element 109, to be disposed between the adhesive layer 111 and the sprayed guide element 109. This diffusion barrier layer 112 may be the same as described above diffusion barrier layer 107 between the connection layer 108 and the thermoelectric element 102 on the cold side. However, after the diffusion barrier layer 112 is disposed on the hot side of the thermal generator 101, it is preferable that it is made of a material selected from a group consisting of b, Ni, W, Mo, Ru, Pd. Ti, Ta. In particular, nitrides of these elements are used for the diffusion layer 112. The formation of the diffusion layer 112 may be accomplished by directly coating the surface facing the baffle 109, i. the top surface of the thermoelectric element 102, for example by a PVD method, sputtering, atomic layer deposition (ALD), laser ablation.

On at least one of the side surface 113 to 116 located between the bottom surface and the top surface of the thermoelectric element 102, preferably at all, an oxidation barrier layer 117 and / or sublimation barrier layer may be arranged, in particular connected to the thermoelectric element 102.

The oxidation barrier layer 117 and / or Sublimationssperrschicht may consist of a material which is selected from a group comprising or consisting of Cr, Si, A1 ₂ 0 _3, Zr0 _2, Al ₂ Ti0 _3, NbN, TaN, WN, and combinations thereof. In particular, A1 ₂ 0 _{3 is used} . It is also possible that the oxidation barrier layer 117 simultaneously forms the sublimation barrier layer, ie, not two separate layers are applied to the thermoelectric element 102. In this case, the oxidation barrier layer may consist of Al ₂ O ₃ . The oxidation barrier layer 117 and / or the sublimation barrier layer may have a layer thickness which is (in each case) selected from a region having a lower limit of 60 nm and an upper limit of 300 μm. The oxidation barrier layer 117 and / or the sublimation barrier layer can be produced, for example, by one of the methods mentioned or, for example, by electron beam vapor deposition

Although the oxidation barrier layer 117 and / or the sublimation barrier layer in the illustration in FIG. 2 extends over only a partial region of the height of the thermoelectric elements 102, it goes without saying that there is the possibility that this layer (s) extends over the entire height of the thermoelectric elements 102 or extend.

8 shows a top view of a substrate 103, preferably a DCB substrate, with thermoelectric elements 102 arranged thereon. The connection of the thermoelectric elements 102 is preferably carried out as described with reference to FIGS. 6 and 7 via the connection layer 108, not shown, if desired Intermediate arrangement of the diffusion barrier layer 107. In general, with regard to the structure and the arrangement of the individual further layers of the thermal generator 101 formed with this substrate 103 with the thermoelectric elements 102, which are likewise not shown in FIG. 8 for reasons of clarity, that is the guide element 109, the adhesive layer 111, the diffusion barrier layer 112, the oxidation barrier layer 117 and / or the sublimation layer, as well as on the cold side, if necessary, arranged metallic layer 105, referred to above, and can applanate these embodiments according to this embodiment variant dt be.

The thermoelectric elements 102 are arranged in the embodiment of FIG. 3 in the form of rows 118, wherein on the substrate 103, a plurality of rows 118 are arranged side by side. For example, 36 thermoelectric elements 102 may be arranged on the substrate 103, which are divided into 6 rows 118. These details have but in terms of the invention only exemplary character, so that a different number of thermoelectric elements 102 may be present.

The individual thermoelectric elements 102 may be connected in series entirely, so that therefore the thermoelectric elements 102 have a meandering course.

On the other hand, there is also the possibility that the thermoelectric elements 102 are connected in series within a row 118, but that the rows 118 are connected in parallel to each other.

Depending on the circuit selected-exclusively in series or in combination with parallel-a different number of external contacts in the form of a positive pole 119 and a negative pole 120 are present on the substrate 103. In the embodiment variant shown in FIG. 3, the substrate 103 has a positive pole 119 (on the right) and a negative pole 120

(left). Preferably, the two external contacts are arranged on the same side of the substrate 103, but there is also the possibility that one of the poles is arranged on another side, for example the opposite side. The two poles consist of a metal or a metallic alloy, in particular of Cu or a Cu alloy.

For completeness, it should be noted that the two poles are electrically connected to the thermoelectric elements 102.

Furthermore, it should be noted for the sake of completeness that - as is known from the prior art - alternately p- and n-doped thermoelectric elements 102 are arranged and electrically conductively connected to each other.

In the preferred embodiment of the substrate 103, this has recesses 121, in particular openings, between the rows 118 of thermoelectric elements 102 for the reasons stated above. These recesses 121 are in particular slit-shaped, as shown in Fig. 3. In principle, these Ausnelimungen 121 but also have a different shape. It is advantageous if the closed corner region 122 is rounded in the slot base or executed with a cross-sectional widening, wherein a radius of curvature may be selected from a range having a lower limit of 0.2 mm and an upper limit of 1 mm. The cross-sectional widening may, for example, be in the form of a bore having a diameter which is greater than the width of the slot. In principle, other forms of cross-sectional expansion are possible, with preferably round shapes, that is, for example, also oval, are used. In essence, therefore, the substrate also receives a meander-shaped appearance through the slot-shaped recesses 121, likewise in plan view.

This embodiment variant provides a thermogenerator 101 which, owing to the thermoelectric elements 102 arranged on the cold side on the substrate 103, has good handleability and, moreover, by the skeleton structure on the hot side - the thermoelectric elements 102 are here only via the guide elements 109 communicating with each other to form an open structure on the hot side-allowing thermal expansion of the thermal generator 101, thereby reducing the risk of damaging the thermal generator 101.

FIG. 9 shows an oblique view of a thermal generator 101 according to the invention. In the illustrated variant, this comprises a plurality of p-doped and n-doped thermoelectric elements 102, which are arranged in strips to form six element strips 123, wherein the thermoelectric elements 102 can be interconnected within an element strip 123, so that the element strips 123 are integrally formed from a plurality Parts can be constructed. One of the element strips 123 is shown in side view in FIG. But it is also possible that the element strips 123 each consist of a thermoelectric element 102, so that therefore the element strips 123 are each only p- or n-doped.

Of course, the thermal generator 101 may also have fewer or more than six such element stripes 123, e.g. also two, three, four, five, seven, eight, nine, ten, etc.

The thermoelectric elements 102 are electrically conductively connected to one another via the guide elements 109 in series. As can be seen from FIG. 9, the contacting takes place thermoelectric elements 102 with the guide elements 109 preferably in the distal end regions 124 of the element strips 123. However, the contacting can also be arranged in another region of the thermoelectric elements 102. It should be noted at this point that in Fig. 6, only the contacting of the element strips 123 is shown together. The contacting of the thermoelectric elements 102 can be carried out as described above for FIGS. 6 and 7.

It is also possible that the contacting of the element strips 123 with each other, as shown in Fig. 9, alternately up and down or these contacts are each arranged on the same side, ie only above or only below, based on the relative position of the element stripes 123th in Fig. 9.

Within an element strip 123, the individual thermoelectric elements 102 are connected in series with each other in an electrically conductive manner.

For tapping the voltage generated in the thermoelectric elements 102, the positive pole 119 and the negative pole 120 are provided. Preferably, the thermoelectric elements 102 and, in sequence, the element stripes 123, e.g. in the figure shown on a rectangular cross-section. However, it is within the scope of the invention also the possibility, although this is not the preferred embodiment, to choose other cross-sectional shapes, such as square, hexagonal, octagonal, round, etc.

It is further preferred, after the preferred use of the thermal generator 101 in an exhaust system of a motor vehicle, that the element strips 123 and / or the thermoelectric elements 102 is perpendicular, that is at least approximately at right angles to the flow direction of the exhaust gases or in other words perpendicular to the Longitudinal extension, that is, the length of the thermal generator 101, are aligned, as shown in Fig. 9. It is also possible in the above-described embodiment of the thermogenerator 101 with slotted DCB substrate between the individual rows - as viewed in the longitudinal direction of the slot-shaped recesses 121 - to use different distances from thermoelectric elements 102. For example, the slot-shaped recesses 121 may at least partially have a different slot width.

FIG. 11 shows a device 125 which, in addition to the thermogenerator 101, also comprises a heat exchanger 126 as a heat source for the thermogenerator 101. In the simplest case, this heat exchanger 126 is formed by a heat exchanger tube or a heat exchanger profile with at least approximately rectangular cross section, wherein according to arrow

127, the exhaust gases forming the primary heat source are introduced into this heat exchanger profile and flow through it. On the outer surface of the heat exchanger 126, that is to say of the heat exchanger profile, the thermoelectric elements 102 of the thermogenerator 101 are arranged in the form of the element strips 123. In particular, the elementary test strips 123 can be thermally conductively connected to the surface of the heat exchanger 126 or the heat exchanger profile by means of a connection means 128. Such connection means 128 are known from the prior art.

Dashed line is indicated in Fig. 11, that the device 125 may be housed at least approximately entirely with a sheath 129, whereby the thermoelectric elements

102 can be better protected against environmental influences. In particular, this also creates a device 125, which can be installed as an entire unit in the exhaust system of a motor vehicle, so for example in the exhaust pipes, or this device 125 even replace a part of an exhaust pipe of a motor vehicle, similar to the installation of a catalyst.

In a modification to this, it is possible, as FIG. 10 shows, that alternatively or additionally to the housing of the device 125, the individual element strips 123 may also be provided with a covering 130.

FIG. 12 shows a section of a device 125 in cross-section. In particular, in each case two element strips 123 of the thermal generator 101 are combined to form a module, wherein in this embodiment variant between the element strips 123 a module, an insulating element 131 is arranged, which preferably fills the entire area between the element strips 123. The insulating element 131 consists of an electrically and thermally insulating material, for example of a ceramic. With the aid of the insulating member 131, a reduction of the heat radiation from the thermoelectric elements 102 is achieved, whereby the efficiency of the thermal generator 101 can be improved.

Alternatively or additionally, it is also possible, as shown in FIG. 10, for such insulating elements 131 to be arranged between the thermoelectric elements 102.

The device 125 according to FIG. 12 comprises at least two of these modules, wherein optionally the area between the modules can also be filled with an insulating element 131, not shown, if required. The modules themselves may in turn be connected via a connecting means 128 to the surface of the heat exchanger 126. Likewise, contacting takes place by means of the guide elements 109 between the modules, as a result of which the thermoelectric elements 102 are connected in series with one another in their entirety.

However, a module can also have only one element strip 123, as shown in FIG. 10. It is therefore not absolutely necessary for a module to comprise a plurality of element strips 123.

Furthermore, it should be noted that it is of course possible that more than two modules, for example three, four, five, six, etc., are arranged in the device 125 or in the thermo-generator 101, and on the other hand that one module also more as two element strips 123, for example, three, four, five, six, etc., may have.

Furthermore, it is possible for the modules to comprise not only the thermoelectric elements 102 and, if appropriate, the insulating elements 131 and the above-described FIGS. 6 to 8. but a complete, modular design of the device 125 is carried out, so that the modules and the heat exchanger 126th

Finally, FIG. 13 shows a variant embodiment of the device 125 in which the heat exchanger 126 is meander-shaped, that is to say the heat exchanger profile has at least one return, wherein the heat exchanger profile according to the embodiment variant according to FIG. 13 is S-shaped in the illustrated cross-sectional variant.

It should be noted at this point that it is possible within the scope of the invention for the heat exchanger 126 to comprise a plurality of heat exchanger profiles and to be arranged on at least a plurality of the heat exchanger profiles, preferably on all the thermoelectric elements 102.

With the embodiment according to FIG. 13, on the one hand a more compact design of the device 125 is achieved, whereby here again a further increase in the economic efficiency of the device 125 according to the invention can be achieved by lengthening the length of the device 125 accordingly and thus more thermoelectric Elements 102 can be arranged in the device 125. It should be pointed out that the thermoelectric elements 102 in FIG. 13 are only indicated in the modular design and, for details, reference is made, for example, to the embodiment variant according to FIG. 12.

Furthermore, there is the possibility that the thermoelectric elements 102 and the modules are arranged not only in the flow direction of the exhaust gases according to arrow 127 in succession, but that as shown in Fig. 13 by dashed lines, such modules or element strips 123 are also arranged one above the other , In this case, the modules can lie directly against each other or even spaced from each other. Such an arrangement possibility exists both in the thermal generator 101 and in the device 125.

There is also the possibility of a sheath 129 of the entire device 125, as indicated by dash-dotted lines in Fig. 13. It is also possible within the scope of the invention that the modules themselves are at least partially enclosed, as indicated in FIG. 12 with the partial arrangement of the enclosure 129 on the modules, wherein in the special embodiment of FIG. 12 the enclosure 129 itself extends over at least a portion of both illustrated modules. Within the scope of the invention, however, there is the possibility that each module has at least partially such an enclosure 129 for itself, which can have mutually corresponding recesses at the corresponding points for contacting, that is to say for the electrically conductive connection of the individual modules to arrange the electrical guide elements 109.

The sheath 129 may be made of plastic, a ceramic or preferably of metal or of combinations of these materials, for example.

The thermoelectric elements 102 preferably have a height of at least 1 mm. This height is oriented perpendicular to the entire length of the device 125 and the thermo generator 101st

A cross-sectional area of the thermoelectric elements 102, viewed in the direction of a contacted end face of the thermoelectric elements 102, is preferably at least 4 mm ² .

According to a further preferred embodiment, a ratio of the height in millimeters to the cross-sectional area in square millimeters of the thermoelectric elements 102 is selected from a range with a lower limit of 1: 100 and an upper limit of 4: 1, wherein the ratio is to be considered dimensionless ,

There is also the possibility that the thermoelectric elements 102 and / or the element strips 123 have a different cross section, that is, for example, the cross section of the individual thermoelectric elements 102 or the element strips 123 in the direction of the length of the device 125 and the thermal generator 101 is larger.

In addition, it should be noted that for the purposes of the invention an element strip 123 is understood to mean an element whose length is at least twice, preferably at least four times, in particular six times as large as the smallest dimension defining the cross section of the element. With an edge length of 1.5 mm of a rectangular cross-section (meaning here the shorter edge length of the two edge lengths in the sense of the definition), the length can therefore be at least 3 mm. Thus, the strip has a clear longitudinal extent.

Preferably, the thermoelectric elements 102 and the thermal generator 101 are operated by utilizing the Seebeck effect, which is known to generate an electrical voltage by the different temperature at the different semiconductor materials. However, such thermoelectric elements 102 always have the possibility that they are operated by utilizing the Peltier effect, ie, that power is supplied and thus a cooling of the surroundings of the thermoelectric elements 102 is achieved. Although the thermoelectric elements 102 can in principle be produced according to methods known from the prior art, they are preferably produced by means of a sintering process in such a way that no or only minimal reworking of the elements 102 is required. It is also possible that the outer surfaces of the thermoelectric elements

102 and the element strips 123 are provided with an insulating member 131 on the above reasons.

Embodiment 1

The thermoelectric elements 102 are made by sintering as a tool from a powder having a composition corresponding to a skutterudite. On the bottom surfaces of the thermoelectric elements 102, the diffusion barrier layers 107 of NbN or WN or TaN are deposited by ALD. As a result, the thermoelectric elements 102 are connected via the diffusion barrier layers 107 with the connecting layers 108 of Pyroduct ^® or by silver sintering with the substrate 103 of A1 ₂ 0 ₃ . The substrate 103 has a double-sided Cu coating and is designed as shown in FIG. 8.

On the top surfaces of the thermoelectric elements 102, the Diffusionssperrschich- are ten 112 of NbN TaN or WN or deposited by ALD and the contacting with the guide elements 109 MoCu via the adhesive layer 111 from Pyroduct ^®.

On the side surfaces 113 to 116 of the thermoelectric elements 102, the oxidation barrier layers 117 of Al ₂ O ₃ + Zr0 ₂ are deposited by ALD prior to their arrangement on the substrate 103.

In this way, a module is produced that has a number of 36 meander-shaped thermoelectric elements 102, which are connected in series. The contacting of the module to the outside via Cu electrodes, which are prepared prior to the arrangement of the thermoelectric elements 102 on the substrate 103 by soldering.

Embodiment 2:

Essentially, the embodiment 1 is readjusted, wherein, however, not the adhesive layer III is used for contacting the thermoelectric elements 102 with the guide element 109, but the guide element 109 directly to the provided with the diffusion barrier layer 112 top surfaces of the thermoelectric elements 102 by thermal spraying of Mo and Cu is sprayed.

The exemplary embodiments show possible embodiments of the thermal generator 1, 101 wherein it should be noted at this point that the invention is not limited to the specifically illustrated embodiments of the same, but rather also various combinations of the individual embodiments are mutually possible and these variations Possibility due to the doctrine of technical action by objective invention in the skill of working in this technical field expert.

For the sake of order, it should finally be pointed out that for a better understanding of the structure, thermogenerators 1, 101 of these or their components have been shown partially unevenly and / or enlarged and / or reduced in size.

REFERENCE NUMBERS

Thermogenerator 101. Thermogenerator Element 102. Element

Element stripes 103. Substrate

Guide element 104. Surface

End area 105. shift

Line 106. Surface

Conduction 107. Diffusion barrier layer Pol 108. Connection layer Pol 109. Conductor element

Distance 110. Adhesive

Length 111. Adhesive layer

Device 112. Diffusion barrier layer heat exchanger 113. Side surface

Arrow 114. side surface

Connecting means 115. Side surface

wrapping

116. side surface

Envelope 117. Oxidation barrier insulating element

118th row

height

119. Plus pole

120th negative pole

121. recess

122. corner area

123. Element stripes

124. End area

125th device

126. Heat exchanger

127. arrow

128. Connecting means

129. Serving

130. Serving

131. Insulating element

Claims

Patent claims

1. Thermogenerator (1) comprising a plurality of thermoelectric elements (2) distributed over a length (11), wherein in each case two thermoelectric elements (2) are arranged at a distance (10) from each other, characterized in that at least one of the distances ( 10) between two thermoelectric elements (2), in particular in the x and / or y direction, to the further distances (10) is different and / or that the thermoelectric elements (2) are arranged in strips as element strips (3) ,

2. Thermogenerator (101) comprising a plurality of thermoelectric elements distributed over a length (102), wherein each two thermoelectric elements (102) arranged at a distance from each other and electrically conductively connected to a guide element (109), in particular according to claim 1, characterized in that the guide element (109) is connected to an adhesive (110) by two thermoelectric elements (102), respectively, or that the guide element (109) is connected to two thermoelectric elements (102) electrically conductively connected to each other by a, in particular thermal, spraying method or is applied by means of low temperature connection technology.

3. thermoelectric generator (101) according to 2, characterized in that the thermoelectric elements (102) are arranged in strips as element strips (123).

4. Thermogenerator (1,101) according to any one of claims 1 to 3, characterized in that the distance (10) between two thermoelectric elements (2, 102) over the length (11) of the thermal generator (1, 101) with a Exponential function changes.

5. thermoelectric generator (1, 101) according to one of claims 1 to 4, characterized in that a longitudinal extent of the element strip (3, 123) formed by the strip-shaped thermoelectric elements (2, 102) at least approximately perpendicular to a predeterminable flow direction the heat flow from the heat source is aligned.

6. thermoelectric generator (1, 101) according to one of claims 1 to 5, characterized in that at least two of the element strips (3, 123) are summarized to form a module and that the thermal generator (1, 101) comprises at least one such module ,

7. Thermogenerator (1, 101) according to claim 6, characterized in that the

Module is at least partially housed.

8. Thermogenerator (1, 101) according to one of claims 1 to 7, characterized in that at least one insulating element (18) is arranged in at least one intermediate space between two thermoelectric elements (2, 102).

9. thermoelectric generator (1, 101) according to any one of claims 1 to 8, characterized in that the element strips (3, 123) are contacted at the opposite longitudinal extension in the distal end regions (5).

10. Thermogenerator (1, 101) according to one of claims 1 to 9, characterized in that the modules of a plurality of element strips (3, 123) are connected in series or in parallel.

11. Thermogenerator (1, 101) according to any one of claims 1 to 10, characterized in that the thermoelectric elements (2, 102) are formed from a skutterudite or a powder composition of the class of Skutterudite.

12. Thermogenerator (1, 101) according to any one of claims 1 to 11, characterized in that in the thermal generator (1, 101) at least two element strips (3, 123) are arranged one above the other.

13. thermoelectric generator (1, 101) according to any one of claims 1 to 12, characterized in that a ratio of the length in mm to the cross section in mm ^{2 of} the thermoelectric see elements (2, 102) is selected from a range with a lower limit of 1: 100 and an upper limit of 4: 1.

14. Thermogenerator (1, 101) according to any one of claims 1 to 13, characterized in that the thermoelectric elements (2, 102) has a rectangular cross-section - viewed in the direction of the longitudinal extension - have.

15. Thermogenerator (1, 101) according to any one of claims 2 to 14, characterized in that the adhesive (110) is an oxygen-setting adhesive (110).

16. Thermogenerator (1, 101) according to any one of claims 2 to 15, characterized in that between the guide element (9, 109) and the thermoelectric elements (2, 102), a diffusion barrier layer (107, 112) is arranged.

17, thermoelectric generator (1, 101) according to one of claims 1 to 16, characterized in that the thermoelectric elements (2, 102) have a top surface, a bottom surface and intermediate side surfaces (113 to 116), wherein on at least one of the side surfaces (113 to 116) an oxidation barrier layer (117) and / or a sublimation barrier layer is arranged.

18. Thermogenerator (1, 101) comprising a plurality of distributed over a length of several thermoelectric elements (2, 102), wherein each two thermoelectric elements (2, 102) arranged at a distance from one another and with a guide element (9, 109) electrically conductive are connected, in particular according to one of the preceding claims, characterized in that the thermoelectric elements (2, 102) are arranged on a DCB substrate.

19. Thermogenerator (1, 101) according to claim 18, characterized in that the thermoelectric elements (2, 102) are arranged meandering on the DGB substrate.

20. Thermogenerator (1, 101) according to claim 18 or 19, characterized in that the DCB substrate between the meandering arranged thermoelectric elements (2, 102) has at least one recess (121).

21. Thermogenerator (1, 101) according to claim 20, characterized in that the

Recess (121) are slot-shaped.

22. Thermogenerator (1, 101) according to claim 20 or 21, characterized in that at least one corner region (122) of the recess (121) is rounded.

23. Thermal generator (1, 101) according to any one of claims 18 to 22, character- ized in that both opposing surfaces (104, 106) of the DCB substrate are metallized.

24. A device (12, 125) for generating electrical energy from heat, comprising a heat source and at least one thermal generator (1, 101), characterized in that the thermal generator (1, 101) is designed according to one of the preceding claims.

25. Device (12, 125) according to claim 24, characterized in that the heat source is an exhaust system of a motor vehicle.

26. Device (12, 125) according to claim 24 or 25, characterized in that the heat source is associated with a heat exchanger (13, 126).