Cooling element and cooling device having a cooling element

Abstract

The invention relates to a cooling body (1) having at least one base body (6) with a plurality of projections (3). It is provided that carbon nanostructured fibers (CNB), in particular carbon nanotubes (CNT), are thermally fastened to at least some of the projections (3). The invention also relates to a cooling device having the cooling body (1).

Description

Technical Field

[0001] The invention relates to a cooling body having at least one base body, the at least one base body having a plurality of projections. In addition, the invention also relates to a cooling device having a cooling body of the type described. Background Art

[0002] A so-called pin-fin heat exchanger is known from US 2004150956. The heat exchanger, which can also be referred to as a cooling element, has a base body with a plurality of projections. These projections are designed as pins or fins and are used for heat exchange. Summary of the invention

[0003] The cooling body according to the invention has at least one base body, which has a plurality of projections. On at least some of the projections, carbon nanostructured fibers made of carbon nanotubes or graphite flakes are fixed in a particularly heat-conducting manner. The carbon nanostructured fibers very effectively enlarge the heat exchange surface of the cooling body in the following way, that is, they conduct heat from the projections. The coolant preferably flows along the cooling body, as a result of which heat is discharged from the projections and from the carbon nanostructured fibers. The carbon nanostructured fibers have very good thermal conductivity and are also soft, so that they can be fixed to the projections in a simple manner in a heat-conducting manner.

[0004] According to an embodiment of the invention, at least several of the projections are thermally connected to one another by means of fibers based on carbon nanostructures. The fibers based on carbon nanostructures not only cause an increase in the heat exchange surface, but also cause a heat distribution in such a way that the projections that heat up more strongly discharge part of their heat via the fibers based on carbon nanostructures to the projections that heat up less strongly. Such a cooling body according to the invention is preferably used in power electronics in order to discharge the corresponding heat, especially at power peaks during operation. The coolant can be a liquid, i.e. a liquid cooling, but it is also possible to use a gas, in particular air, which is subjected to normal convection or forced convection, for example, by means of a ventilator.

[0005] Preferably, it is provided that the fibers based on the carbon nanostructure extend straight between the relevant projections. In particular, the fibers based on the carbon nanostructure can extend tensioned between the projections, wherein however, a very high tension is not necessary, but is also possible.

[0006] Preferably, it is provided that the base body has a substrate from which the projections project. On the base body itself, a component is fixed, for example a power electronic component, from which heat should be dissipated if it is an application in the field of power electronics. The heat of this component is transferred to the base body, from the base body to the projections and from the projections to the fibers based on the carbon nanostructure. Alternatively, the heat source is connected to the heat sink (base body) via a cooling liquid circuit. The coolant transports the heat away, wherein the coolant also flows along the projections and preferably also at least along a part of the base.

[0007] Preferably, it can be provided that the projection is designed as a pin. The pin can preferably have a circular or oval cross section.

[0008] For simple and heat-conductive fixing, it can preferably be provided that the carbon nanostructured fibers are arranged in a manner wound around the projections. It is particularly sufficient here to wind the carbon nanostructured fibers only in a single layer around the projections. The integral length of the carbon nanostructured fibers is sufficient to connect at least two projections, and possibly also many more projections than two projections, to one another.

[0009] According to an extension of the invention, it is provided that the fibers based on the carbon nanostructure are fixed to the projections extending in multiple directions and / or in multiple planes. Therefore, different fiber extension directions may be present on different projections. Additionally or alternatively, it is also possible that fibers extending in different directions are fixed to one and the same projection. It is also possible that not only one fiber but multiple fibers are fixed to one projection, more precisely in the same plane or distributed over the length of the projection, so that different planes appear.

[0010] One embodiment of the invention provides that the fibers based on the carbon nanostructure extend along the same side or different sides of the projections. The projections of a projection row are thus connected by means of fibers that can be based on the carbon nanostructure in such a way that the fibers are respectively located on the same side of the projections. However, it is also possible, alternatively or additionally, for the fibers to abut against different sides of the projections arranged in a row along their course.

[0011] The invention also relates to a cooling device with a cooling body as explained above and with a flow path for a flowing coolant. It is provided that the fibers based on the carbon nanostructure extend in the direction of the flow path and / or transversely to, in particular perpendicularly to, the flow path. If the fibers based on the carbon nanostructure extend in the direction of the flow path, i.e. in the flow direction of the coolant, the counterpressure of the cooling device hardly changes. A positive effect is that the temperature gradient along the flow direction of the coolant is reduced. However, it is also possible, in addition or as an alternative, to provide for the fibers to extend transversely to the direction of the flow path, whereby flow vortices may be generated, which may improve the cooling efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings illustrate the invention with the aid of exemplary embodiments and more precisely in the drawings:

[0013] Figure 1 The cooling body is shown in a lateral cross-sectional view in the longitudinal direction of the flow;

[0014] Figure 2 yes Figure 1 A top view of a cooling body;

[0015] Figure 3 yes Figure 1 A side cross-sectional view of a region of a protrusion of a cooling body;

[0016] Figure 4 Another embodiment of a cooling body is shown in a top view;

[0017] Figure 5 Another embodiment of a cooling body is shown in a top view;

[0018] Figure 6 Another embodiment of a cooling body is shown in a top view;

[0019] Figure 7 Another embodiment of a cooling body is shown in a top view; and

[0020] Figure 8 A further exemplary embodiment of a cooling element is shown in a lateral section in the longitudinal direction of flow. DETAILED DESCRIPTION

[0021] Figure 1 The cooling body 1 is shown in a lateral sectional view. Figure 2 The heat sink 1 is shown in a top view. The heat sink 1 has a substrate 2 which is designed as a metal plate in the present exemplary embodiment. A projection 3 projects from the substrate 2 on one side. The substrate 2 and the projection 3 together form a base body 6 of the heat sink 1. The projection 3 can be formed as follows. Figure 2As shown, the projections are arranged in a matrix (in particular, rows, preferably longitudinal and transverse rows are formed). In this embodiment, the projections are configured as pins 4 with a circular cross section. Based on the matrix arrangement of the pins 4, according to Figure 2 The pin row 5 is obtained. In fact, the components to be heated, such as power semiconductor components (not shown) of power electronics, are fixed in a heat-conducting manner on the substrate 2. The power electronics belong to an electric vehicle, for example. The flow path is defined by the upper wall 8 and the side walls (not shown).

[0022] Carbon nanostructured fibers CNB, in particular carbon nanotubes CNT, are thermally conductively fixed to the projections 3 of the cooling body 1. The carbon nanostructured fibers CNB are designed in the form of yarns or strips. For thermally conductive fixing to the projections 3, the carbon nanostructured fibers are arranged in a manner wound around the respective projections 3. Figures 1 to 7 In the exemplary embodiment of the present invention, the process is carried out in a single layer, that is to say, only one circle of carbon nanostructure-based fibers CNB is laid around each projection 3. The arrangement is now such that the carbon nanostructure-based fibers CNB extend from projection 3 to projection 3, in particular along the corresponding pin row 5 (or projection row), thereby thermally connecting the individual projections 3 or pins 4 to one another. Figure 1 It can be seen that the carbon nanostructured fibers CNB are arranged in multiple planes on the protrusions 3, that is, multiple carbon nanostructured fibers CNB are arranged one above the other and fixed to each protrusion 3 in a heat-conducting manner. In this way, on the one hand, the heat dissipation surface of the cooling body 1 is greatly enlarged, and on the other hand, as already mentioned, the individual protrusions 3 are connected to each other in a heat-conducting manner. According to this, the component to be cooled, as already mentioned, outputs its heat to the matrix 6 and this matrix outputs it to the carbon nanostructured fibers CNB. In the cooling device, the coolant can preferably flow along the flow path 7 on the cooling body 1, wherein the direction of the flow path 7 corresponds to the longitudinal extension of the carbon nanostructured fibers CNB. In this way, the heat is effectively discharged by means of the coolant.

[0023] Figure 3 In cross section it is shown Figure 1 and 2 A section of the projection 3 configured as a pin 4. It can be seen that a plurality of carbon nanostructured fibers CNB are fixed to the projection 3 in a single layer, ie, each overlapped by only one circle, and are spaced apart from each other. Figure 2 In the exemplary embodiment of , the respective carbon nanostructure-based fibers CNB extend straight between the associated projections 3 , more precisely only on one side of the projections 3 .

[0024] Figure 4 Explains a corresponding Figure 2 , wherein the projection 3 is designed as a pin 4 with an oval cross section.

[0025] Figure 5 Another embodiment is described, which corresponds to Figure 2 In the embodiment of the present invention, however, the carbon nanostructured fibers CNB extend not only along the side of the pins 4 of each of its pin rows 5, but also along the two mutually opposite side faces of the pins 4 of the corresponding pin row 5. This further increases the surface and improves the heat distribution of the cooling body 1.

[0026] Figure 6 In the embodiment of the present invention, there is a base body 6, and also a Figure 4 It can be seen that pins 4 with an elliptical cross section are also provided. In this case, the carbon nanostructured fibers CNB are extended in a cross shape so that between two pins 4 in each pin row 5 there is a cross of carbon nanostructured fibers CNB, which are located on two mutually opposite sides in the region of the pins 4.

[0027] Figure 7 Corresponding Figure 5 An embodiment in which, however, the carbon nanostructured fibers CNB not only extend in the direction of the flow path 7, but also extend transversely thereto, in particular perpendicularly thereto, in such a way that the corresponding pins 4 are provided with carbon nanostructured fibers CNB on two mutually opposite sides and offset by 90° and then again on two mutually opposite sides.

[0028] Applies to Figures 1 to 7 In all the exemplary embodiments, the heat-conducting fixing of the respective carbon nanostructured fibers CNB is accomplished by winding in a single layer, ie, by one turn, around the respective projection 3 . Figure 8 In contrast to this, the heat-conducting fixing on the respective projection 3 is accomplished by winding the respective carbon nanostructure-based fibers CNB around the respective projection 3 in multiple layers, for example by means of two or more turns.

[0029] Therefore, it is crucial in the present invention that the carbon nanostructured fiber CNB is thermally connected to the projection 3 of the corresponding cooling body 1, in particular connected by winding. As a result, the heat flow from the corresponding projection 3 to the adjacent projection 3 is greatly improved, so that thermal balance occurs. At the same time, the carbon nanostructured fiber CNB also greatly increases the surface of the cooling body 1, thereby greatly improving the heat dissipation. The fixation of the carbon nanostructured fiber on the pin (projection) is preferably purely mechanical. Alternatively, a preferred material-locked connection is specified. This can be achieved, for example, by brazing with a suitable solder, which wets the metal and the carbon nanostructured fiber. Another possibility of a material-locked connection is to separate the metal on the pin and the carbon nanostructured fiber without current.

Claims

1. A cooling element (1) comprising at least one base body (6) having a plurality of projections (3), characterized in that: Carbon nanostructured fibers (CNB) are thermally conductively fixed on at least a few of the protrusions (3). The carbon nanostructured fibers (CNB) are arranged in a manner of being wound around the protrusions (3) for their thermally conductive fixation. The carbon nanostructured fibers extend from one protrusion (3) to another protrusion (3), thereby thermally connecting the protrusions (3) to each other.

2. The cooling body according to claim 1, characterized in that At least several of the protrusions (3) are thermally connected to each other by means of the carbon nanostructure-based fibers (CNB).

3. The cooling body according to claim 1 or 2, characterized in that The carbon nanostructure based fibers (CNB) extend straight between the associated protrusions (3).

4. The cooling body according to claim 1 or 2, characterized in that The base body (6) has a substrate (2) from which the projection (3) projects.

5. The cooling body according to claim 1 or 2, characterized in that The projection (3) is designed as a pin (4).

6. The cooling body according to claim 5, characterized in that The pin (4) has a circular or oval cross section.

7. The cooling body according to claim 1 or 2, characterized in that The carbon nanostructure based fibers (CNB) are carbon nanotubes (CNTs).

8. The cooling body according to claim 1 or 2, characterized in that The carbon nanostructure-based fibers (CNB) are wound around the protrusion (3) in a single layer.

9. The cooling body according to claim 1 or 2, characterized in that The carbon nanostructure-based fibers (CNB) are fixed to the protrusion (3) in a manner extending in multiple directions and / or in multiple planes.

10. The cooling body according to claim 1 or 2, characterized in that The carbon nanostructure-based fibers (CNB) extend along the same and / or different sides of the protrusion (3).

11. Cooling device with a cooling body according to any one of the preceding claims and with a flow path (7) for a flowing coolant, characterized in that The carbon nanostructure-based fibers (CNB) extend in the direction of the flow path (7) and / or in a direction transverse to the flow path (7).

12. The cooling device according to claim 11, characterized in that The carbon nanostructure based fibers (CNB) extend perpendicularly to the direction of the flow path (7).

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