Thermoelectric Module

Abstract

The invention relates to a thermoelectric module with a thermoelectric element for converting a temperature gradient between the two ends of the thermoelectric element into an electric voltage, an electrically conductive heat conducting element which is arranged between the thermoelectric element and a warm medium in order to thermally couple the high-temperature side of the thermoelectric element to the warm medium, and/or an electrically conductive heating element which is arranged between the thermoelectric element and a cold medium in order to thermally couple the low-temperature side of the thermoelectric element to the cold medium. The invention is characterized in that the electrically conductive heat conducting element is designed as a spring element which is elastic parallel to the direction of progression of the temperature gradient t.

Claims

1. A thermoelectric module comprising: a thermoelectric element for converting a temperature gradient between the two ends of the thermoelectric element into an electric voltage, an electrically conductive heat conducting element which is arranged between the thermoelectric element and a warm medium order to thermally couple the high-temperature side of the thermoelectric element to the warm medium, wherein the electrically conductive heat conducting element is designed as a spring element which is elastic parallel to the direction of progression of the temperature gradient t.

2. The thermoelectric module according to claim 1, wherein the electrically conductive heat conducting element comprises a metal or a metal alloy.

3. The thermoelectric module according to claim 1, further comprising an electrically insulating, planar, fiber-ceramic support element for supporting the electrically conductive heat conducting element, wherein fiber-ceramic support element particularly extends vertically to the direction of the temperature gradient, wherein the fiber-ceramic support element comprises at least one recess having the electrically conductive heat conducting element passing through it, so that an outer portion of the electrically conductive heat conducting element is arranged outside the fiber-ceramic support element and an inner portion of the electrically conductive heat conducting element is arranged inside the fiber-ceramic support element.

4. The thermoelectric module according to claim 1, wherein the electrically conductive heat conducting element has a loop-shaped design, wherein the loop comprises a first and a second open end, said ends respectively extending parallel to the fiber-ceramic support element outside thereof and forming a contact surface to the warm and respectively cold medium, and the round central element of the loop is connected to the thermoelectric element by force locking or by material bonding.

5. The thermoelectric module according to claim 1, wherein, between the electrically conductive heat conducting element and the thermoelectric element, particularly exclusively, a heat distribution plate is arranged for homogenous heat distribution at the first and respectively second end of the thermoelectric element, said heat distribution plate comprising preferably a metal or a metal alloy.

6. The thermoelectric module according to claim 1, wherein the thermoelectric module has a planar or curved shape.

7. The thermoelectric module according to claim 1, wherein the electrically conductive heat conducting element forms a bridge between two adjacent thermoelectric elements wherein, for this purpose, the electrically conductive heat conducting element particularly comprises two loops, a first one of them serving for contacting the first thermoelectric element and the second one serving for contacting the second thermoelectric element.

8. The thermoelectric module according to claim 5, wherein the thermal expansion coefficient of the heat distribution plate is identical with the thermal expansion coefficient of the adjacent thermoelectric element.

9. The thermoelectric module according to claim 1, wherein a direct metallic connection exists between the thermoelectric element and the hot and respectively cold medium.

10. The thermoelectric module according to claim 3, wherein the size and the shape of the recess of the fiber-ceramic support element are adapted to the size and the shape of the electrically conductive heat conducting element so that the fiber-ceramic support element is in direct abutment on the outer edge of the electrically conductive heat conducting element and insulates the thermoelectric element from the hot and respectively cold medium.

11. A thermoelectric module comprising: a thermoelectric element for converting a temperature gradient between the two ends of the thermoelectric element into an electric voltage, an electrically conductive heat conducting element which is arranged between the thermoelectric element and a cold medium in order to thermally couple the low-temperature side of the thermoelectric element to the cold medium, wherein the electrically conductive heat conducting element is designed as a spring element which is elastic parallel to the direction of progression of the temperature gradient t.

Description

[0045] Hereunder, preferred embodiments of the invention will be explained with reference to the Figures.

[0046] The following is shown:

[0047] FIGS. 1 and 2 show the configuration of thermoelectric modules according to the state of the art,

[0048] FIG. 3 shows the deformation of a thermoelectric module according to the state of the art,

[0049] FIG. 4 shows the thermal resistances in a thermoelectric module according to the state of the art,

[0050] FIG. 5 shows a first embodiment of the thermoelectric module according to the invention,

[0051] FIG. 6 is an isolated view of a heat conducting element according to the invention,

[0052] FIGS. 7 and 8 show further embodiments of an thermoelectric element according to the invention,

[0053] FIG. 9 shows the thermal resistances in an embodiment of the thermoelectric element according to the invention.

[0054] FIGS. 1 and 2 have already been explained in connection with the state of the art.

[0055] FIG. 3 illustrates the manner in which a thermoelectric module 10 known from the state of the art is expanding on its hot side 18 more than on its cold side 20. This leads to deformation of the module, to a deterioration of the thermal coupling of the individual components and thus to a reduction of the achievable electric power of the thermoelectric module 10.

[0056] This effect is further intensified since, in thermoelectric modules known from the state of the art, a plurality of different materials are used, with high thermal resistances existing between them (see FIG. 4). This holds true particularly because the heat transition between different materials, e.g. between metal and ceramic, is subject to a high thermal resistance.

[0057] According to the invention, however, the fiber-ceramic support element 22, 24 is not used as a heat conductor but only for electric insulation of the heat conducting elements 14a, 14b, 16a, 16b as well as for mechanical stabilization of the thermoelectric module (see FIGS. 7 and 9, among others). Particularly from FIG. 9, it is evident that the thermoelectric module 10 of the invention makes it possible to reduce the thermal resistances between the heat source and respectively the heat sink and the thermoelectric module 10. This holds true both for the number of thermal resistances and for their type since, for instance, a heat transition between a ceramic material and metal is entirely avoided and ceramic materials with high thermal resistance do not participate in the heat conduction. Thereby, a higher heat flow and thus a more efficient use of the existing heat quantity are rendered possible.

[0058] An exemplary design of the thermoelectric module 10 of the invention is shown in FIG. 5. On the top side of each thermoelectric element 12a, 12b, there is arranged a respective heat distribution plate 30 of metal, whose thermal expansion coefficient preferably is identical with that of the thermoelectric element 12a, 12b so that non thermoelectric tension will occur at the transition between these two elements. Thermally and electrically coupled to the top side of the heat distribution plates is the electrically conductive heat conducting element 14a. The latter comprises two loops, a first one of them serving for contacting the left-hand heat distribution plate 30 and the second one serving for contacting the right-hand heat distribution plate 30. This contacting is effected respectively by the round central element of the loop, wherein, additionally, the respective first and second open end 26, 28 of each loop is thermally coupled to the heat source, not shown.

[0059] FIG. 6 illustrates in which manner the heat conducting element 14a can become elastically deformed: On the one hand, an elastic deformation is possible in a direction parallel to the module surface, i.e. vertically to the direction of the temperature gradient t. Into this direction the heat conducting element 14a can expand without subjecting the thermoelectric elements 12a, 12b or the heat distribution plates 30 to substantial mechanical stresses. This is because also the round central portion 27 of each loop is movable independently from the two open ends 26, 28 of the loop in parallel to the surface of the module so that possible movements on the open ends 26, 28 can be compensated.

[0060] Additionally, the heat conducting element that is designed as a spring element has resilient properties in the direction of the temperature gradient t so that, in this manner, e.g. height differences in the thermoelectric elements 12a, 12b can be compensated.

[0061] The loop-shaped heat conducting elements 14a, 14b, 16a, 16b of the invention can be used in different manners: According to FIG. 7a, they are used both on the top side and on the bottom side of the thermoelectric elements 12a, 12b while in each case being held by a fiber-ceramic support plate 22, 24, the latter comprising recesses having the loops of the heat conducting element passing through them. The fiber-ceramic support plate 22, 24 further provide for a thermal insulation of the space between the thermoelectric elements 12a, 12b against the heat source and the heat sink.

[0062] By way of alternative, it is possible that one side of the thermoelectric element 10 is formed e.g. as the cold side according to the state of the art by using, for the electric contacting of the thermoelectric elements 12a, 12b, metal bridges 34 that are supported by the ceramic plate 32 which itself is connected to an outer metal plate (see FIG. 7b). This design of the cold side of the thermoelectric element 10 corresponds to the design from the state of the art according to FIG. 1b.

[0063] Further, according to FIG. 7c, one side of the thermoelectric element, e.g. the cold side, can comprise, on the outer side of the ceramic plate 32, individual metal plates 38a, 38b (DBD, DCB substrates with optionally adapted metallization).

[0064] According to FIG. 8, the thermoelectric module 10 can also have a curved shape. This is rendered possible by the use of the fiber-ceramic support element.

[0065] In all embodiments of the thermoelectric module, it is possible that the thermoelectric elements 12a, 12b are connected to each other at a respective displacement via an electrically conductive heat conducting element 14a, 14b, 16a, 16b. As can be seen in FIG. 7a, the two left-hand thermoelectric elements 12a, 12b are connected to each other via the heat conducting element 14a while the second and the third thermoelectric element 12b, 12a are connected to each other via the lower heat conducting element 16a. The third and the fourth thermoelectric element 12a, 12b are again connected via the upper heat conducting element 14b, etc. Thereby, a serial connection of a plurality of thermoelectric elements can be achieved, as is known from the state of the art.