THERMOELECTRIC MODULE

Abstract

A thermoelectric module may include a plurality of thermoelectric elements, a first side wall connected to a plurality of first conductor bridges in a thermally conductive manner, a second side all connected to a plurality of second conductor bridges in a thermally conductive manner, and at least one liquid metal layer disposed between the first conductor bridges and an outer side of the first side wall. The at least one liquid metal layer may face away from the first conductor bridges, and at least one spacer may be arranged in the at least one liquid metal layer. The thermoelectric elements may be electrically interconnected to and extend between the first and second conductor bridges.

Claims

1. A thermoelectric module, comprising: a plurality of thermoelectric elements; a first side wall connected to a plurality of first conductor bridges in a thermally conductive manner; a second side wall connected to a plurality of second conductor bridges in a thermally conductive manner; and at least one liquid metal layer disposed between the first conductor bridges and an outer side of the first side wall, the at least one liquid metal layer facing away from the first conductor bridges, and at least one spacer being arranged in the at least one liquid metal layer; wherein the thermoelectric elements are electrically interconnected to the first and second conductor bridges; and wherein the thermoelectric elements extend between the first and second conductor bridges.

2. The thermoelectric module according to claim 1, wherein the at least one spacer includes a plurality of spacer elements.

3. The thermoelectric module according to claim 1, wherein the at least one spacer element is a separate component from at least one of a respective one of the first conductor bridges and the first side wall.

4. The thermoelectric module according to claim 1, wherein the at least one spacer element is a rolling body.

5. The thermoelectric module according to claim 4, wherein the rolling body is cylindrical or spherical.

6. The thermoelectric module according to claim 1, wherein: the at least one liquid metal layer is in contact with an inner boundary wall on a side facing a respective one of the first conductor bridges; the at least one spacer element directly touches the inner boundary wall; the at least one liquid metal layer is in contact with an outer boundary wall on a side facing the first side wall; and the at least one spacer element directly touches the outer boundary wall.

7. The thermoelectric module according to claim 1, wherein one of: the first side wall is assigned to a cold side of the thermoelectric module, and the second side wall is assigned to a warm side of the thermoelectric module; or the first side wall is assigned to the warm side, and the second side wall is assigned to the cold side.

8. The thermoelectric module according to claim 1, wherein at least one of: the thermoelectric module has a first electrical insulating layer disposed between the first conductor bridges and the first side wall; the at least one liquid metal layer is disposed between the first conductor bridges and the first electrical insulating layer; and the at least one liquid metal layer is disposed between the first electrical insulating layer and the first side wall.

9. The thermoelectric module according to claim 8, wherein: the first electrical insulating layer is formed by a structured ceramic body; and on a side facing the first conductor bridges, the structured ceramic body has webs, which separate areas assigned to individual ones of the first conductor bridges from one another.

10. The thermoelectric module according to claim 9, wherein one of: the structured ceramic body has a plurality of metalized surfaces, wherein the metalized surfaces are interrupted by the webs on the side facing the first conductor bridges; or the structured ceramic body has a cohesive metalized surface on a side facing the first side wall.

11. The thermoelectric module according to claim 8, wherein: the first electrical insulating layer is formed by a plurality of ceramic elements; the first side wall has a plurality of metalized surfaces; each liquid metal layer abuts on a corresponding one of the metalized surfaces of the first side wall; the ceramic elements have metalized surfaces on a side facing away from the first conductor bridges; and each liquid metal layer abuts on a corresponding one of the metalized surfaces of the ceramic elements.

12. The thermoelectric module according to claim 1, wherein: the first side wall is double-walled; the first side wall has an inner wall, which faces the first conductor bridges, and an outer wall, which faces away from the first conductor bridges and has the outer side; and one liquid metal layer is disposed between the inner wall and the outer wall.

13. The thermoelectric module according to claim 12, wherein the first electrical insulating layer is applied to a side of the inner wall.

14. The thermoelectric module according to claim 8, wherein: the first electrical insulating layer is applied to the first conductor bridges; the first side wall has a plurality of metalized surfaces; each liquid metal layer abuts on a corresponding one of the metalized surfaces of the first side wall; the first conductor bridges each has a metalized surface on the first electrical insulating layer; and each liquid metal layer abuts on a metalized surface of the first electrical insulating layer.

15. The thermoelectric module according to claim 1, further comprising a module housing surrounding a module interior, wherein: the thermoelectric elements are disposed in the module interior; the first and second conductor bridges are disposed in the module interior; the first side wall forms a first side of the module housing, which is provided for contacting a heat source or heat sink; and the second side wall forms a second side of the module housing, which is provided for contacting a heat sink or heat source.

16. The thermoelectric module according to claim 1, wherein the at least one spacer element is a separate component from at least one of a respective one of the first conductor bridges and the first side wall.

17. The thermoelectric module according to claim 2, wherein the at least one spacer element is a rolling body.

18. The thermoelectric module according to claim 3, wherein the at least one spacer element is a rolling body.

19. The thermoelectric module according to claim 18, wherein the rolling body is cylindrical or spherical.

20. A thermoelectric module, comprising: a plurality of thermoelectric elements; a first side wall connected to a plurality of first conductor bridges in a thermally conductive manner; a second side wall connected to a plurality of second conductor bridges in a thermally conductive manner; at least one liquid metal layer disposed between the first conductor bridges and an outer side of the first side wall, the at least one liquid metal layer facing away from the first conductor bridges, and at least one spacer being arranged in the at least one liquid metal layer; and a first electrical insulating layer disposed between the first conductor bridges and the first side wall; wherein the thermoelectric elements are electrically interconnected to and extend between the first and second conductor bridges; the at least one liquid metal layer is disposed between one of: the first conductor bridges and the first electrical insulating layer; or the first electrical insulating layer and the first side wall.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In each case schematically,

[0045] FIG. 1 shows a sectional illustration through a thermoelectric module according to a first embodiment,

[0046] FIG. 2 shows a sectional illustration through a thermoelectric module according to a second embodiment,

[0047] FIG. 3 shows a sectional illustration through a thermoelectric module according to a third embodiment, and

[0048] FIG. 4 shows a sectional illustration through a thermoelectric module according to a fourth embodiment,

DETAILED DESCRIPTION

[0049] A thermoelectric module 10 illustrated in FIGS. 1 to 4 is used to create electrical energy from heat energy. For example, the thermoelectric module 10 can be used in response to the residual heat use in the exhaust tract of a motor vehicle. The thermoelectric module 10 has a module housing 12, which encloses a module interior 14. A plurality of thermoelectric elements 16, which are electrically connected by means of a plurality of conductor bridges 18, are disposed in the module interior 14. The thermoelectric elements 16 are preferably electrically connected in series by means of the conductor bridges 18. On a first side 20, the module housing 12 has a first side wall 22, which is connected to a plurality of first conductor bridges 24 so as to conduct heat. On a second side 26, the module housing 12 further has a second side wall 28, which is connected to a plurality of second conductor bridges 30 so as to conduct heat, whereby the thermoelectric elements 16 extend between the first conductor bridges 24 and the second conductor bridges 30. The conductor bridges 18 are in each case connected to the respective side walls 22, 28 via an electrical insulating layer 32 on the first side 20 as well as on the second side 26. The conductor bridges 18 are thus electrically separated from the side walls 22, 28.

[0050] The first conductor bridges 24 are connected to these thermoelectric elements 16 in an electrically conductive manner. Such an electrically conductive connection 33 can for example be established by soldering or silver sintering. In the case of a solder connection, a solder is preferably used, which has a melting point of above 120 C., for example a silver copper connection. The conductor bridges 18 preferably have copper, nickel or iron. To improve the connection, the conductor bridges 18 can have a primer, for example titanium, silver, nickel or copper. The conductor bridges 18 can furthermore have a barrier layer, for example nickel.

[0051] A first electrical insulating layer 34 is disposed between the first conductor bridges 24 and the first side wall 22. The first conductor bridges 24 are in each case in contact with the first electrical insulating layer 34 via a liquid metal layer 36.

[0052] The first conductor bridges 24 and the first electrical insulating layer 34 in each case preferably have metalized surfaces 38. The metalized surfaces 38 improved the wetting with the liquid metal of the liquid metal layer 36. The metalized surfaces 38 can for example be produced by annealing a metallization paste. Such metallization pastes can for example have copper, silver or tungsten. The thickness of the metallization layer is preferably between 20 m and 300 m. The layers formed by means of the metallization pastes are preferably additionally coated with nickel and/or silver.

[0053] The liquid metal layers 36 have a metal or a metal alloy, which is liquid at an operating temperature of the thermoelectric module 10. Due to the fact that a temperature gradient is present in the thermoelectric module 10 during the operation, the operating temperature is a function of the position of the respective element in the thermoelectric module 10. If the liquid metal layer 36 is for example located at a heated first side 20 of the thermoelectric module 10, a higher melting point can be sufficient, than if the liquid metal layer 36 were located at a cooled side of the thermoelectric module 10. Metals or metal alloys with a melting point of between 50 C. and 250 C. are preferably used. Such metal alloys are, for example, gallium, bismuth, indium, copper, silver and/or stannous alloys.

[0054] As can be gathered from the examples of FIGS. 1 to 4, the respective liquid metal layer 36 is in each case disposed between an outer side 58 of the first side wall 22, which faces away from the first conductor bridges 24. Embodiments, in the case of which exactly such a liquid metal layer 36 is provided, are shown, e.g. in FIG. 3, and embodiments, in the case of which a plurality of such liquid metal layers 36 are provided, e.g. in FIGS. 1, 2 and 4. In all embodiments, at least one spacer element 50 is disposed in at least one of these liquid metal layers 36. At least one such spacer element 50 is thereby preferably disposed in each such liquid metal layer 36. A plurality of such spacer elements 50 are advantageously disposed in the respective liquid metal layer 36. An arrangement is thereby shown, in which the individual spacer elements 50 are spaced apart from one another. It is also conceivable, however, that at least two such spacer elements 50 touch one another. The spacer elements 50 are further preferably embodied as separate components with regard to the respective first conductor bridge 24 and with regard to the first side wall 22. Provision is further made for the respective spacer element 50 to be embodied as rolling body 52. In the examples, the respective rolling body 52 is embodied cylindrically or spherically. An embodiment comprising spherical rolling bodies 52 or spacer elements 50, e.g. of metal or ceramic, in particular of glass, is preferred.

[0055] Provision is further made for the respective liquid metal layer 36 to be in contact with an inner boundary wall 54 on a side facing the respective first conductor bridge 24 and for the liquid metal layer 36 to be in contact with an outer boundary wall 56 on a side facing the first side wall 22. The respective spacer element 50 now preferably in each case touches this inner boundary wall 54 and this outer boundary wall 56 directly, so that it can roll therealong with little friction in response to relative movements between the first side wall 22 and the first conductor bridges 24.

[0056] In the embodiment shown in FIG. 1, the first electrical insulating layer 34 is formed by a ceramic body 40, which as a plurality of webs 42. The webs 42 divide the ceramic body 40 into a plurality of areas, which are in each case assigned to a first conductor bridge 24. The first conductor bridges 24 are thermally connected to the areas assigned thereto via the liquid metal layers 36.

[0057] The webs 42 separate the metalized surfaces 38 from one another on the ceramic body 40. The webs 42 furthermore separate the liquid metal layers 36 from one another, so that no electrical contact is present between the liquid metal layers 36.

[0058] On a side facing the first side wall 22, the ceramic body 40 furthermore also has a metalized surface 38, which improves the contact to a further liquid metal layer 36, which is disposed between the first electrical insulating layer 34 and the first side wall 22 and which establishes a thermal contact between these two.

[0059] To improve the wetting of the first side wall 22 with the liquid metal layer 36, the first side wall 22 can also be provided with a metalized surface 38.

[0060] By means of this arrangement, the first conductor bridges and thus the thermoelectric elements 16 to the first electrical insulating layer 34 are mechanically uncoupled, so that thermally induced mechanical stresses can be compensated. The first electrical insulating layer 34 is furthermore also mechanically uncoupled from the first side wall 22, so that the thermally induced mechanical stresses can also be reduced here. As a whole, such a setup allows for a higher operating temperature of the thermoelectric module 10, whereby a significantly improved efficiency can be attained.

[0061] On the second side 26 of the thermoelectric module 10, the second side wall 28 is provided with a second electrical insulating layer 45. This second electrical insulating layer 45 can for example be produced by annealing a dielectric or by thermally spraying a ceramic layer or by soldering a ceramic body. For example, Al.sub.2O.sub.3, AIN or Si.sub.3N.sub.4 ceramics can be used.

[0062] The second conductor bridges 30 are connected to the second electrical insulating layer 45. Such an electrically conductive connection 47 can preferably be a solder connection. For example, a soft solder comprising a melting point of above 120 C., such as tin for example, can be used. A hard solder, for example a silver copper alloy or an active solder, for example a silver copper titanium alloy, is likewise possible. In the alternative or in addition thereto, the connection 47 between the second conductor bridges 30 and the second electrical insulating layer 45 can be established by silver sintering.

[0063] To improve the wetting of the second electrical insulating layer 45, it can also be provided with a metalized surface 38.

[0064] The second conductor bridges 30 are electrically connected to the thermoelectric elements 16. Such a connection 49 could for example be a solder connection. For example a soft solder with a melting point of above 120 C., a hard solder, for example a silver copper alloy, can be used as solder. In the alternative or in addition thereto, the second conductor bridges 30 can be connected to the thermoelectric elements 16 by means of a silver sintering.

[0065] In the case of this described alternative, the first side 20 of the thermoelectric module 10 is used as hot side and the second side 26 of the thermoelectric module 10 is used as cold side. It goes without saying that a complementary use is possible a well. However, the solder connections on the second side 26, which is then the hot side, should then not be created by means of a soft solder. In return, the solder connections on the first side 20, which is then the cold side, can also be formed by means of a soft solder.

[0066] A second embodiment of the thermoelectric module 10 shown in FIG. 2 differs from the first embodiment of the thermoelectric module 10 illustrated in FIG. 1 in that the first electrical insulating layer 34 is formed by a plurality of ceramic elements 44 and in that the first conductor bridges 24 are in each case formed by a metalized surface 38 on the ceramic elements 44 of the first electrical insulating layer 34.

[0067] The ceramic elements 44 of the first electrical insulating layer 34 are thus connected to the thermoelectric elements 16 in a mechanically fixed manner via the first conductor bridges 24. The metallic surfaces 38, which form the first conductor bridges 24, preferably have a thickness of between 150 m and 300 m. A sufficient conductivity can thus be attained.

[0068] The ceramic elements 44 in each case further have a second metalized surface 38, which are disposed on the side located opposite the first conductor bridges 24, thus the side of the ceramic elements 44 facing the first side wall 22. These metalized surfaces 38 serve for the improved wetting of liquid metal layers 36, which are disposed between the first electrical insulating layer 34 and the first side wall 22. Due to the fact that the first electrical insulating layer 34 is formed by means of a plurality of ceramic elements 44, the metalized surfaces 38 are interrupted, whereby the liquid metal layer 36 is interrupted as well and thus each ceramic element 44 is thermally connected to the first side wall 22 by means of a separate liquid metal layer 36.

[0069] Apart from that, the second embodiment of the thermoelectric module 10 illustrated in FIG. 1, with regard to setup and function, corresponds to the first embodiment of the thermoelectric module 10 illustrated in FIG. 1, to the above description of which reference is made in this respect.

[0070] A third embodiment of the thermoelectric module 10 illustrated in FIG. 3 differs from the first embodiment of the thermoelectric module 10 illustrated in FIG. 1 in that the first side wall 22 is embodied in a double-walled manner and in that a liquid metal layer 36 runs between an inner wall 46 and an outer wall 48 of the first side wall 22. The inner wall 46 and the outer wall 48 can in each case be provided with a metalized surface 38, in order to improve the wetting with the liquid metal layer 36.

[0071] On a side, which faces the first conductor bridges 24, the inner wall 46 has the first electrical insulating layer 34. The first electrical insulating layer 34 can for example be formed by annealing a dielectric. In the alternative or in addition thereto, the first electrical insulating layer 34 can also be formed by thermal spraying of a ceramic onto the inner wall 46. The first electrical insulating layer 34 can further also be formed by means of a ceramic body, which is soldered to the inner wall 46.

[0072] The first conductor bridges 24 are connected to the first electrical insulating layer 34. Such a connection 51 can for example be a solder connection with hard solder or active solder. As an alternative thereto, the first conductor bridges 24 can also be connected to the first electrical insulating layer 34 by means of silver sintering.

[0073] To improve the wetting of the first electrical insulating layer 34, the latter can be provided with a metalized surface 38. Apart from that, the third embodiment of the thermoelectric module 10 illustrated in FIG. 3 corresponds, with regard to setup and function, to the first embodiment of the thermoelectric module 10 illustrated in FIG. 1, to the above description of which reference is made in this respect.

[0074] A fourth embodiment of the thermoelectric module 10 illustrated in FIG. 4 differs from the first embodiment of the thermoelectric module 10 illustrated in FIG. 1 in that the first electrical insulating layer 34 is formed by a coating of the first conductor bridges 24. The first electrical insulating layer 34 is thus divided into a plurality of layer sections, each of which coat the first conductor bridges 24. The first electrical insulating layer 34 is thereby applied to the respective first conductor bridge 24 from a plurality of sides. Only the side, to which the first conductor brides 24 are connected by means of the thermoelectric elements 16, is not covered by the first electrical insulating layer 34. The first electrical insulating layer 34 can for example be formed by a dielectric, which is applied to the conductor bridges by means of immersion, spraying or printing. The first conductor bridges 24 can thereby be embodied in a cuboidal manner or in a cuboidal manner comprising rounded corners. In the alternative or in addition thereto, the first conductor bridges 24 can also be formed as convexly formed metal sheet, wherein one side of the conductor bridges, which is connected to the thermoelectric elements 16, is flat.

[0075] A liquid metal layer 36 is disposed between the first electrical insulating layer 34 and the first side wall 22 and forms a thermal contact between the first side wall 22 and the first conductor bridges 24. For a better wetting, the first electrical insulating layer 34 as well as the first side wall 22 can be provided with a metalized surface 38.

[0076] Apart from that, the embodiment of the thermoelectric module 10 illustrated in FIG. 4 corresponds, with regard to setup and function, to the first embodiment of the thermoelectric module illustrated in FIG. 1, to the above description of which reference is made in this respect.