Pulsating Heat Pipe Heatsink

Abstract

The invention relates to a heat pipe cooling element (10; 10a-10p), with at least one meandering channel (11) for guiding a cooling medium, with at least two components (16; 16a-16j; 16m; 16o, 18; 18a; 18c-18J; 18m; 18o) that define the cross-section of the at least one channel (11), wherein at least the first component (16; 16a-16j; 16m; 16o) is manufactured using a primary forming process and preferably has ribs (26; 26a; 26b; 26l; 65; 66) arranged parallel to each other for laterally defining the cross-section of the at least one channel (11).

Description

Technical field

[0001] The invention relates to a pulsating heat pipe heat sink, hereinafter referred to simply as a heat pipe heat sink, which is characterized by a particularly advantageous manufacturing process, whereby, among other things, the desired thermomechanical properties can be adapted to the respective application in a particularly simple and advantageous manner. State of the art

[0002] Heat pipe heat sinks are known in various forms from the prior art. Such a heat pipe heat sink is characterized by at least one, typically meandering, channel that serves to guide a vaporizable cooling medium, such as glycerin or similar substances. The operating principle of such a heat pipe heat sink is such that, at an evaporator section of the heat pipe heat sink arranged in at least indirect contact with a heat-generating component, the cooling medium in the at least one channel is heated to a temperature above its boiling point and evaporates. This causes it to be forced by pressure pulsation into a condenser section of the heat pipe heat sink, where the vaporized cooling medium condenses and can thus flow back into the evaporator section.

[0003] Typically, such a heat pipe heat sink consists of a central body or first component in which at least one channel is formed, terminated on its two opposite sides by end caps or similar components. The end caps or similar components serve to reverse the flow of the cooling medium between two adjacent sections of the at least one channel, which is separated by ribs in the first component. This enables the meandering flow of the cooling medium within the heat pipe heat sink. It is known, for example, to form the central body as an extruded profile or from several interconnected components. Disclosure of the invention

[0004] The (pulsating) heat pipe heat sink according to the invention, with the features of claim 1, has the advantage that it can be optimally adapted to the respective application. In particular, a wide variety of fin geometries, which laterally define the sections of the channel, can be manufactured with particular ease. Furthermore, not only flat heat sinks, i.e., heat sinks whose central or first component has a constant cross-section, can be produced, but also heat sinks that have a special geometry in the area where the heat pipe heat sink is in thermally conductive contact with the components to be cooled, for example, wider fins or similar features.

[0005] The invention is based on the idea of ​​constructing the area of ​​the heat pipe cooling element that forms the at least one channel from two components, in contrast to the prior art: a first component manufactured using a primary forming process, and a second component that covers the first component, at least in the area of ​​the fins. The primary forming process makes it particularly easy to realize a wide variety of geometries and arrangements of the fins in the first component. In contrast, the second component, acting as a lid or base, serves to limit the cross-section of the at least one channel and to make the heat pipe cooling element media-tight. For this purpose, the first and second components are typically connected by means of a material-bonded connection such that leakage of the pressurized cooling medium in the area of ​​the at least one channel is prevented.

[0006] In light of the above explanations, a heat pipe heat sink with the features of claim 1 therefore has at least one meandering channel for guiding a cooling medium. Furthermore, the heat pipe heat sink consists of at least two components that define the cross-section of the at least one channel. The first component is manufactured using a primary forming process and preferably has ribs arranged parallel to each other for laterally defining the cross-section of the at least one channel. Finally, the second component is designed to cover the first component, at least in the area of ​​the at least one channel, in the manner of a lid or bottom.

[0007] A primary forming process for the first component includes, but is not limited to, die casting, extrusion, forging, or compression molding. Materials suitable for forming the first and / or second component include, for example, copper, aluminum, iron, steel, titanium, and their alloys. As explained above, the two components are preferably joined by a metallurgical bond. This includes, but is not limited to, laser welding, adhesive bonding, friction stir welding, or similar processes.

[0008] Advantageous further developments of the heat pipe cooling element according to the invention are listed in the dependent claims.

[0009] A first preferred design provides that the ribs have different widths, at least over a portion of their longitudinal extent. The different rib widths (given the same rib height) result in differently sized sections or different cross-sections of the at least one channel, which has proven advantageous in certain applications for varying the local flow velocity of the cooling medium.

[0010] Another preferred embodiment of the heat pipe heat sink features fins with rectangular and / or trapezoidal cross-sections. Both rectangular and trapezoidal fins can be used within a single heat pipe heat sink. The cross-sections of the fins can be rounded, for example, in the area where they connect to the second component. It is also conceivable that the connections between the two components in the fin area are not completely sealed. Instead, small gaps may be permitted between the fins and the second component, which could arise, for example, due to manufacturing tolerances. The essential requirement is that both components are media-tight, meaning that no coolant escapes from the heat pipe heat sink.

[0011] Another advantage of the heat pipe heat sink is that its geometry can be easily adapted to the specific conditions and arrangement of the components to be cooled. Specifically, the first and / or second component is designed to have raised areas, at least in some sections, running in the direction of the fins. These raised areas can then be in direct thermal contact with the components to be cooled, eliminating the need for intermediate elements or similar components.

[0012] The fins can also have different heights. This means that the cross-sectional area of ​​the channel also varies locally (assuming equal spacing between the individual fins). This allows for local adjustment of the flow velocity and / or heat transfer properties.

[0013] Another preferred design feature of the heat pipe heat sink for local adaptation to components to be cooled or for influencing the effect of the cooling medium provides that the first and / or second component has at least one increase in wall thickness on the outside facing away from the at least one channel.

[0014] Particularly if the second component is not only designed as a (flat) lid or base, but also features flow elements or ribs, it may be possible to manufacture the second component using a primary forming process, with some of the ribs already formed on the second component. This allows for advantageous properties, such as the realization of particularly narrow spacing between the ribs, which would be difficult or impossible to achieve simply by forming all the ribs on the first component.

[0015] In order to enable a kind of positive fit between the two components in the area of ​​the ribs, or to make the formation of material-bonded connections particularly simple and effective, it may be provided that the ribs engage in recesses of the first and / or second component.

[0016] The heat pipe heat sink typically requires flow deflection elements in the area between two immediately adjacent fins. These elements allow the cooling medium to flow in different directions in the two adjacent channels, forming the meandering channel. For this purpose, a third component is provided between the fins to deflect the flow. However, it is also conceivable to incorporate the corresponding elements or flow deflections into the first and / or second component.

[0017] As explained above, it is essential that the heat pipe heat sink is designed to be media-tight on the outside. For this purpose, at least the first and second components are designed to be media-tightly connected to each other, at least in their edge sections, by a material-bonded connection.

[0018] Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments of the invention and from the drawings. Brief description of the drawings Fig. Figure 1 shows a longitudinal section through a first heat pipe cooling element in the area of ​​its first component manufactured using the primary forming process. Fig. 2 to Fig. Four partial cross-sections through a heat pipe heat sink to illustrate differently shaped fins on the first component and differently shaped second components. Fig. 5 a longitudinal section according to the representation of the Fig. 1 in the case of a heat pipe heat sink that has fins that are enlarged in width in certain areas, Fig. 6 and Fig. 7 partial cross-sections through modified heat pipe heat sinks that have local depressions or elevations, Fig. 8 to Fig. 11 partial cross-sections through further modified heat pipe heat sinks, which have recesses for arranging the cooling fins, Fig. 12 a partial cross-section according to the representation of the Fig. 8 to 11, where recesses for ribs are formed on both components, Fig. 13 a partial cross-section through a heat pipe heat sink, in which the second component is shaped in a wave-like form, Fig. 14 to Fig. 16 longitudinal sections through heat pipe heat sinks with specially designed deflection areas using two components, Fig. 17 a longitudinal section through a heat pipe heat sink, in which the deflection areas are realized by a third component, Fig. 18 a longitudinal section through a heat pipe heat sink, in which the second component engages in a circumferential recess of the first component, Fig. 19 a partial cross-section in the plane AA of the Fig. 18 and Fig. 20 a perspective view of a second component, in which the second component has raised areas for contacting with heat-generating components. Embodiments of the invention

[0019] Identical elements or elements with the same function are provided with the same reference numbers in the figures.

[0020] The one in the Fig. The pulsating heat pipe heat sink 10, shown in longitudinal section, serves to cool, in particular, electronic components (not shown) that generate heat during operation. For this purpose, the heat pipe heat sink 10 is thermally connected to the component(s) or assembly to be cooled on an evaporator side 13 of the heat pipe heat sink 10 in a manner known per se and therefore not shown. The thermally conductive connection can be made, for example, via a thermally conductive adhesive or by direct mechanical connection to the heat pipe heat sink 10.

[0021] Within the heat pipe heat sink 10, a cooling medium (not shown) in the form of a vaporizable liquid is arranged in at least one channel 11. The cooling medium, which is vaporized by the heat of the component or assembly to be cooled, flows within the at least one channel 11 of the heat pipe heat sink 10 from the evaporator side 13 to a condenser side 14, where the cooling medium cools down again to a temperature below the condensation temperature due to the ambient cold or by other means, whereupon it flows back towards the evaporator side. The operating principle of such a heat pipe heat sink 10 is known from the prior art and is therefore not described further.

[0022] The heat pipe heat sink 10 has a housing 12, which consists of at least two components 16, 18, with component 18 only being present in the Fig. 2 to Fig. 4 is recognizable. The two components 16, 18 are at least partially connected to each other in a media-tight manner, such that the cooling medium located in the channel 11 of the heat pipe cooling body 10 cannot escape from the housing 12 of the heat pipe cooling body 10.

[0023] While the first component 16 is manufactured by a primary forming process and is made of aluminum or an aluminum alloy, the second component 18 can be manufactured either by a primary forming process or by other means, for example, by a forming process from a (flat) sheet metal part or similar. Preferably, the second component 18 is made of the same material as the first component 16 in order to avoid thermal stresses due to different coefficients of expansion.

[0024] The first component 16 is shaped like a trough and has a side parallel to the plane of the drawing. Fig. The plane running along 1 forms a flat ground section 22. The ground section 22 is shown in the diagram. Fig. 1 is bounded by a circumferential edge section 24. Within the edge section 24, the first component 16 has several parallel ribs 26 for guiding the cooling medium within the meandering channel 11. The channel 11 also has deflection areas 28, 30 at the end faces of the ribs 26 for the cooling medium, so that the cooling medium guided between the ribs 26 can flow alternately in one direction or the other towards the channel 11, as indicated by arrows 31, 32.

[0025] The edge section 24, together with the ribs 26, forms the part in the Fig. In the embodiment shown in Figure 1, a (single) endless channel 11 for the cooling medium is provided. For this reason, the channel 11 has a connecting channel 35 on the side of the deflection areas 30 facing away from the deflection areas 28, which connects the two edge-side channel sections 37, 38 of the channel 11.

[0026] It is further mentioned that, in modification of the one in the Fig. In the embodiment shown in Figure 1, the channel 11 can also be designed as a channel 11 closed on both sides, without the connecting channel 35, as is also known from the prior art.

[0027] As shown by the Fig. As can be seen in Figure 1, the ribs 26 can have different widths b1, b2, with the width b2 being greater than the width b1. In the illustrated embodiment, the ribs 26 of different widths alternate in a direction running in the direction of arrow 33.

[0028] Furthermore, the cross-section of the ribs 26 can be configured in different ways. For this purpose, we will first refer to the Fig. 2 referred. In the Fig. 2. It can be seen that ribs 26a are provided, which have a rectangular cross-section. In light of the above explanation, the width of the ribs 26a can vary. Furthermore, in the Fig. In the embodiment shown in Figure 2, ribs 26b are also shown, which have inclined flanks. In particular, the cross-section of the ribs 26b can also be trapezoidal.

[0029] In the Fig. Figure 2 further shows that the second component 18, serving as a cover element 19, is connected to the first component 16 at least in the area of ​​the edge section 24, and additionally also in the area of ​​most of the ribs 26a, 26b. The connection between the two components 16, 18 can be formed, in particular, as a material-bonded connection 36. A material-bonded connection is understood to include, in particular, but not exclusively, brazing, soldering, welding (especially laser beam welding), or possibly bonding. Fig. Furthermore, it can be seen that small gaps 38 may be formed between the ribs 26a, 26b and the second component 18 in the areas where no material-bonded connection 36 is formed. Depending on the manufacturing process or component tolerances, as well as the material-bonded connection 36, contact may also be present between the ribs 26a, 26b and the second component 18, even if no material-bonded connection 36 is formed there.

[0030] In the Fig. Figure 3 shows the case where the ribs 26b on the side facing the second component 18 are formed with radii 40.

[0031] The heat pipe heat sink 10a according to the Fig. In contrast, component 4 has only ribs 26a having a rectangular cross-section. The second component 18a, unlike the second component 18, is designed according to the Fig. 1 to 3 are only planar within the edge section 24 of the first component 16a. Outside the edge section 24, the second component 18a has an obliquely arranged edge 46 projecting towards the first component 16a, with sections 48 running parallel to the bottom section 22 of the first component 44. In the area of ​​sections 48, the second component 18a can additionally be connected to the first component 16a, in particular by a material-bonded connection (not shown). This is especially intended if there is only a contact between the edge section 24 of the first component 16a and the second component 18a.

[0032] In the Fig. Figure 5 shows a heat pipe cooling element 10b, the first component 16b of which, in addition to ribs 26 which may have different widths b1, b2, comprises ribs 52 which, viewed in the longitudinal direction of the ribs 52, have a width b3 in certain areas that is larger than the width b1, b2, such that raised sections 53 are formed on opposite sides of the ribs 52 over a portion of their longitudinal extent. This reduces the flow cross-section of the channel 11 in the area of ​​the sections 53.

[0033] In the Fig. 6 and Fig. Figure 7 shows heat pipe heat sinks 10c and 10d, where the first component 16c, 16d has a raised area 55, 56 relative to the rest of the surface. While the second component 18c of heat pipe heat sink 10c is a flat component, the second component 18d of heat pipe heat sink 10d is adapted to the shape of the first component 16d, so that the height h of the channel 11 within heat pipe heat sink 10d is constant due to the raised area 57. In contrast, the channel 11 of heat pipe heat sink 10c has different heights h1, h2.

[0034] In the Fig. Figures 8 to 11 show further heat pipe cooling elements 10e to 10h in sections. All heat pipe cooling elements 10e to 10h are characterized by the fact that the second components 18e to 18h each have groove-shaped recesses 63, 64 into which the end faces of the fins 65, 66 of the first components 16e to 16h are inserted. While the recesses 63 each have a rectangular cross-section corresponding to the rectangular cross-section of the fins 65, the recesses 64 are each rounded, with the fins 66 being either flat or rounded on the side facing the recesses 64.

[0035] In the Fig. 12 The heat pipe cooling element 10i has a first component 16i with an edge section 24, which, viewed in the direction of the double arrow 66, alternately has recesses 67 (rounded recesses in the exemplary embodiment) and ribs 26 (rounded ribs in the exemplary embodiment). The second component 18i, like the first component 16i, is manufactured by primary forming and, in the exemplary embodiment, has rectangular recesses 68 for receiving the end faces of the ribs 26 of the first component 16i, and rectangular ribs 26 in cross-section that project into the recesses 67 of the first component 16i.

[0036] In the Fig. Figure 13 shows a heat pipe cooling element 10j, in which the second component 18j is designed as a corrugated sheet metal part. The second component 18j is connected to some of the ribs 26 of the first component 16j in the area of ​​recesses 69, in particular by laser welds 70.

[0037] In the Fig. In the heat pipe cooling element 10k shown in Figure 14, consisting of the two components 16k and 18k, the first component 16k has fins 26, while the second component 18k, which is also manufactured using the primary forming process, has fins 26k. Viewed in the direction of the double arrow 71, the fins 26 and 26k of the two components 16k and 18k alternate. On one side of the heat pipe cooling element 10k, the first component 16k also has a deflection section 72 extending in the direction of the double arrow 83, in which the end faces of the fins 26 and 26k are arranged alternately.

[0038] The one in Fig. The Heat Pipe cooling body 10l shown in section 15 differs from the Heat Pipe cooling body 10k in that the deflection section 72l is part of the fins 26l, which are formed on the second component 18l.

[0039] In the Fig. In the heat pipe cooling body 10m shown in Figure 16, its deflection section 72m is formed on the second component 18m, while on the first component 16m all ribs 26 are formed.

[0040] In the Fig. Figure 17 shows a heat pipe heat sink 10n, which, in addition to the two components 16n and 18n with fins 26, is formed from a third component 74. The third component 74 forms the deflection section 72n.

[0041] In the Fig. 18 and Fig. Figure 19 shows a heat pipe cooling element 10o, the second component 18o of which is completely inserted within a recess 76 of the first component 16o. The first component 18o also has local or linear protrusions 78 that penetrate corresponding counter-openings on the second component 18o. In the area of ​​the protrusions 78, the connection between the two components 16o and 18o is made, for example, by friction stir welding.

[0042] Most recently, in the Fig. Figure 20 shows a heat pipe heat sink 10p, which is characterized by the fact that either the first component 16p and / or the second component 18p is formed with one or more raised sections 80 on the outer surface facing away from the channel 11 (not shown) in order to reduce the distance to the heat-conducting components. In the area of ​​the raised sections 80, the heat pipe heat sink 10p has an increased wall thickness on the first and / or second component 16p, 16p, which can be achieved particularly easily in manufacturing by means of the primary forming process.

[0043] The heat pipe cooling element 10, 10a to 10p described so far can be modified or adapted in a variety of ways without deviating from the inventive concept.

Claims

[1] Heat pipe cooling element (10; 10a-10p), with at least one meandering channel (11) for guiding a cooling medium, with at least two components (16; 16a-16j; 16m; 16o, 18; 18a; 18c-18J; 18m; 18o) that define the cross-section of the at least one channel (11), wherein at least the first component (16; 16a-16j; 16m; 16o) is manufactured by a primary forming process and preferably has parallel ribs (26; 26a; 26b; 26l; 65; 66) for laterally defining the cross-section of the at least one channel (11), and wherein the second component (18; 18a; 18c-18J; 18m; 18o) defines the first component (16; 16a-16j; 16m; 16o) at least in the area of ​​the at least one channel (11) covered in the manner of a lid or bottom. [2] Heat pipe heat sink according to claim 1, characterized by , that the ribs (26; 26a; 52) have different widths (b1, b2, b3) at least over a section of their longitudinal extent. [3] Heat pipe heat sink according to claim 1 or 2, characterized by , that the ribs (26; 26a; 26b; 26l; 65; 66) are rectangular and / or trapezoidal in cross-section. [4] Heat pipe heat sink according to one of claims 1 to 3, characterized by , that the first and / or second component (16c; 16d, 18d) has at least partially raised areas (56-57) in a direction extending in the height direction of the ribs (26). [5] Heat pipe heat sink according to claim 4, characterized by , that the ribs (26) have different heights (h1, h2). [6] Heat pipe heat sink according to any one of claims 1 to 5, characterized by , that the first and / or second component (16p, 18p) has at least one increase (80) of increased wall thickness on the outer side facing away from the at least one channel (11). [7] Heat pipe heat sink according to any one of claims 1 to 6, characterized by, that the second component (18i; 18k; 18o) is manufactured using the primary forming process, and that some of the ribs (26) are formed on the second component (18i; 18k; 18o). [8] Heat pipe heat sink according to any one of claims 1 to 7, characterized by , that the ribs (26; 65; 66) engage in recesses (63; 64; 67; 68; 69) of the first and / or second component (16e-16j, 18e-18j). [9] Heat pipe heat sink according to any one of claims 1 to 8, characterized by , that a third component (74) is provided for deflecting the flow of the cooling medium between the ribs (26). [10] Heat pipe heat sink according to any one of claims 1 to 9, characterized by , that at least the first and second components (16; 16a-16j; 16m; 16o, 18; 18a; 18c-18J; 18m; 18o) are connected to each other in a media-tight manner at least in edge sections (24) by a material-bonded connection (36).

Images