Pulsating heat pipe heat sink

Abstract

The invention relates to a pulsating heat pipe heat sink (10; 10a to 10h) comprising: at least two fluidically separated channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d; 51 to 53; 61 to 64; 68, 69) which each convey an evaporable cooling medium (A, B, C); an evaporator region (16) in which at least one heat-generating component (1) can be disposed; and a condenser region (22) which is spaced from the evaporator region (16).

Description

[0001] R.411594

[0002] - 1 -

[0003] Description

[0004] title

[0005] Pulsating Heat Pipe Heatsink

[0006] Technical field

[0007] The invention relates to a pulsating heat pipe heat sink which is characterized by a particularly advantageous cooling behavior of at least one heat-generating component.

[0008] State of the art

[0009] From DE 102021 204 769 A1 of the applicant, a pulsating heat pipe heat sink with the features of the preamble of claim 1 is known. The known heat sink is characterized essentially by having two separate channels arranged side by side in one plane for guiding a cooling medium. A heat-generating component arranged in an evaporator area and thermally connected to the heat sink is thus cooled simultaneously by both channels. The use of two fluidically separated channels has the particular advantage that even if one channel fails or leaks due to the escape of cooling medium, the functionality of the heat sink is at least partially maintained.

[0010] Disclosure of the invention

[0011] The pulsating heat pipe heat sink according to the invention, with the features of claim 1, has the advantage that different operating points of the cooling media can be generated in the at least two channels. This has the advantage that, for example, the channel in which a first cooling medium is located is already at its operating point, i.e., evaporated, while the channel with R.411594

[0012] - 2 - the second cooling medium only reaches its operating point at higher temperatures. This has the advantage, for example, that the first cooling medium can exhibit very good start-up behavior, while the second cooling medium has the ability to transport very high heat values ​​to the condenser area. Because the first cooling medium evaporates early, it also improves the start-up behavior of the second cooling medium, as the latter is preheated (evenly) by the channel containing the first cooling medium. Furthermore, the advantage is that the first cooling medium, which is sensitive to temperature fluctuations, can thereby compensate for possible temperature fluctuations in the second cooling medium.

[0013] Furthermore, instabilities that may occur in the temperature profile of the two channels are compensated for by their independent operation. If one channel is unstable, the other can dissipate more heat directly, thus smoothing out temperature peaks. The aforementioned advantages are further enhanced by an optimal selection of the channels' geometric cross-sections.

[0014] In light of the above explanations, a pulsating heat pipe heat sink according to the invention, comprising the features of claim 1, therefore has at least two fluidically separated channels for guiding a vaporizable cooling medium. Furthermore, an evaporator section for accommodating at least one heat-generating component and a condenser section arranged at a distance from the evaporator section are provided. Crucially, cooling media with different operating points are arranged in the at least two channels, from which the respective cooling medium in the evaporator section can be vaporized by heat input from the at least one heat-generating component.

[0015] Advantageous further developments of the Pulsating Heat Pipe cooling body according to the invention are listed in the dependent claims.

[0016] Regarding the selection of different cooling media to achieve the different operating points, there are several possibilities: In one variant, the cooling media are intended to consist of at least two different chemical substances with different boiling points. R.411594

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[0018] Alternatively, it can also be provided that the cooling media each consist of at least two identical chemical substances with different boiling points, and that the mixing ratio of the at least two substances in the cooling media is different. In other words, this means that different boiling points can be achieved by choosing different mixing ratios of the otherwise identical substances.

[0019] In yet another alternative embodiment, the cooling media arranged in the at least two channels may have different fill levels in those channels. This applies both to the use of the same cooling medium and to the use of different cooling media. In other words, even if the substances are the same or have the same boiling points, in a channel containing less cooling medium than another channel, more cooling medium evaporates due to the larger internal surface area of ​​the bubbles in the latter channel. This results in a different pressure gradient between the evaporator and condenser sections of the latter channel, and thus different flow conditions. This is primarily caused by the larger quantity or mass of the cooling medium to be heated in the latter channel.

[0020] There are also different possibilities regarding the arrangement of the at least two channels to the evaporator area, which produce different properties depending on the operating point: In one variant, the at least two channels are arranged in a single plane, at least in the evaporator area. This allows, for example, a relatively simple design for the heat sink or a very compact design in terms of height.

[0021] Alternatively, the at least two channels can be arranged on at least two levels, at least in the evaporator area. This delays the heat input into a channel located further away from the evaporator area, or results in a faster temperature rise in the channel closer to the evaporator area. R.411594

[0022] - 4 -

[0023] Alternatively or additionally to arranging the channels on one or different levels, it can be provided that the at least two channels, at least in the evaporator section, have different cross-sectional shapes and / or different cross-sectional sizes. This means, for example, that round, triangular, or rectangular channels, possibly with different cross-sectional sizes, influence the operating point. The effect of this design, when using the same cooling media, is comparable to that of different fill levels.

[0024] Alternatively, it can also be provided that at least two channels have the same cross-sections.

[0025] Regardless of the geometry or cross-section of the individual channels, a further advantageous embodiment of the cooling sink provides that the at least two channels are designed in a meandering shape. In particular, it is provided that the at least two channels have channel sections arranged parallel to each other, at least in the evaporator area. This also includes the case where the at least two channels are intertwined, i.e., arranged alternately perpendicular to the longitudinal direction of the channel sections, at least in the evaporator area.

[0026] In an alternative design, it can also be provided that at least the two channels interlock in a comb-like manner, at least in the evaporator area.

[0027] It is also conceivable that at least two channels, at least in the evaporator area, are arranged at an oblique angle to each other.

[0028] However, it is also conceivable that at least the two channels, at least in the evaporator area, are designed in a star-shaped or cloverleaf shape without mutual or with mutual geometric overlap.

[0029] 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. R.411594

[0030] - 5 -

[0031] Brief description of the drawings

[0032] Fig. 1 shows a section through a first pulsating heat pipe heat sink according to the invention,

[0033] Fig. 2 and

[0034] Fig. 3 shows different cross-sections through the heat sink according to Fig. 1 in the plane 11-11 of Fig. 1.

[0035] Fig. 4 shows a section through a second heat sink according to the invention,

[0036] Fig. 5 and

[0037] Fig. 6 shows different cross-sections through the heat sink according to Fig. 4 in the plane VV of Fig. 4.

[0038] Fig. 7 and

[0039] Fig. 8 shows different cross-sections through the heat sink according to Fig. 4 in the plane VI I— VI I of Fig. 4.

[0040] Fig. 9 shows a section through a third heat sink designed according to the invention,

[0041] Fig. 10 to

[0042] Fig. 14 shows different cross-sections through the heat sink according to Fig. 9 in the plane XX of Fig. 9.

[0043] Fig. 15 shows a section through a fourth cooling body designed according to the invention with channels arranged at an oblique angle to each other, R.411594

[0044] - 6 -

[0045] Fig. 16 shows a section through a fifth cooling body designed according to the invention with comb-like interlocking channels,

[0046] Fig. 17 to

[0047] Fig. 19 shows different cross-sections through the heat sink according to Fig. 16 in plane XVI I— XVI I of Fig. 16.

[0048] Fig. 20 shows a section through a sixth cooling body designed according to the invention with three fluidically separated channels,

[0049] Fig. 21 and

[0050] Fig. 22 shows a section in the XXI-XXI plane of Fig. 20,

[0051] Fig. 23 shows a section through a seventh heat sink designed according to the invention and

[0052] Fig. 24 and

[0053] Fig. 25 shows sections through modified heat sinks with channels arranged in a star shape relative to each other.

[0054] Embodiments of the invention

[0055] Identical elements or elements with the same function are provided with the same reference numbers in the figures.

[0056] Figure 1 shows a section through a first pulsating heat pipe heat sink 10 designed according to the invention, hereinafter referred to simply as heat sink 10. The heat sink 10 serves to cool at least one component 1 or assembly, visible only in Figures 2 and 3, wherein the component 1 or assembly dissipates heat during operation. The component 1 or assembly can be, for example, but is not limited to, a power IC, a power transistor, or the like. The heat sink 10 is preferably used in the context of electromobility or in an R.411594

[0057] - 7 - at least partially autonomous vehicles. However, the use of the heat sink 10 should not be limited to such applications.

[0058] The heat sink 10 has a cuboid-shaped housing 12, which is made of metal and can be constructed in one or more parts. Regarding the manufacturing process of the housing 12 or the heat sink 10, it can be produced by either machining or non-machining processes. It is also conceivable to manufacture the heat sink 10 using an additive manufacturing process.

[0059] In the exemplary embodiment, the housing 12, which has a rectangular basic shape, has through-openings 14 in its corner areas, which serve to attach the heat sink 10 to a larger support assembly or similar.

[0060] The at least one heat-generating component 1 is arranged in the area of ​​an evaporator section 16, which in the illustration of Fig. 1 has a square base and is characterized by a boundary 18. In the illustrations of Figs. 2 and 3, the evaporator section 16 is shown in relief only for better visibility, but it runs along the surface of the housing 12. The evaporator section 16 is surrounded by a rectangular intermediate section 20 with a boundary 21, which in turn is surrounded by a rectangular or frame-shaped condenser section 22 with a boundary 23.

[0061] Within the cross-section of the housing 12, two fluidically separated channels 24, 26 are formed or arranged as an example. The two channels 24, 26 extend at least from the evaporator section 16 to the condenser section 22. On opposite sides of the housing 12, the two channels 24, 26 can each be filled with a cooling medium A (first channel 24) and a cooling medium B (second channel 26) via a supply channel 28, 30. The two supply channels 28, 30 can also be sealed to prevent the respective cooling medium A, B from escaping the channels 24, 26 during operation of the heat sink 10. R.411594

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[0063] It is essential that the two cooling media A and B have different boiling points or operating points. This can be achieved by using different (chemical) substances for the two cooling media A and B, or by using the same substances but in different mixing ratios. Finally, it is also possible for the two cooling media A and B to consist of the same (chemical) substances and have the same mixing ratio, but to be present in different fill levels within channels 24 and 26. This means that, for example, with the same volume in both channels 24 and 26, cooling medium A (in its liquid state) occupies only 40% of the volume of channel 24, while cooling medium B occupies a larger volume, for example, 70%, of the volume of channel 26.

[0064] The operating principle of the heat sink 10, which is known per se, is explained below as follows: when the at least one heat-generating component 1 is operated, the cooling medium A, B located in the channels 24, 26 is heated above its boiling point, whereupon it evaporates and, with the formation of vapor bubbles, flows towards the condenser section 22. There, the cooling medium A, B condenses again and can thus flow back into the evaporator section 16. Because the two cooling media A, B have different boiling points or operating points, the two cooling media A, B evaporate at different temperatures (assuming the same heat input into the respective cooling medium A, B).

[0065] In the illustrated embodiment, the two channels 24, 26 are each meandering and each has first channel sections 31 (first channel 24) and first channel sections 32 (second channel 26) arranged parallel to each other. The straight first channel sections 31, 32 are spaced ai and a2 apart from each other (Fig. 2) and, moreover, have at least substantially the same length when viewed in the longitudinal direction of the first channel sections 31, 32. Two immediately adjacent first channel sections 31, 32 of the respective channel 24, 26 are connected to each other by means of arcuate second channel sections 33, 34. Furthermore, the two outermost first channel sections 31, 32 of R.411594

[0066] - 9 - both channels 24, 26 are connected to each other via a return section 36, 38, into which the respective supply channel 28, 30 also flows.

[0067] Figures 2 and 3 show that the first channel sections 31, 32 extend in two superimposed planes 41, 42, perpendicular to the plane of the evaporator area 16. In the embodiment according to Figure 2, the cross-sections of the first channel sections 31 are square, while the cross-sections of the first channel sections 32 are rectangular. Furthermore, the first channel sections 31, 32 extend at the same distance from the underside 43 and the top side 44 of the housing 12, respectively.

[0068] In the embodiment shown in Fig. 3, the first channel sections 31 of the first channel 24 each have a circular cross-section, while the first channel sections 32 of the second channel 26 each have a triangular cross-section. The size of the cross-sections of the two channels 24, 26, or of the respective first channel sections 31, 32, can be the same or different, depending on the cooling medium A, B.

[0069] The heat sink 10a shown in Fig. 4 differs from the heat sink 10 essentially in that its two channels 24a, 26a are intertwined in the area of ​​the first channel sections 31a, 32a. This is particularly evident from Fig. 5, where two first channel sections 31a, 32a, arranged directly next to each other, are alternately positioned on different planes 41, 42.

[0070] In contrast, Fig. 6 shows an embodiment in which two first channel sections 31a, 32a of each channel 24a, 26a arranged directly next to each other have alternately different cross-sections, in the exemplary embodiment alternating a square and a rectangular cross-section.

[0071] Figures 7 and 8 illustrate the transition between the first channel sections 31a and 32a, each having a square cross-section, between the planes 41 and 42 in the area of ​​the second channel sections 33a and 34a. Figure 7 shows in particular that the two first channel sections 31a and 32a R.411594

[0072] - 10 - each are connected with a diagonally extending connecting section 45 as a second channel section 33a, 34a, while in Fig. 8 an embodiment is shown in which the two first channel sections 31a, 32a are connected to each other by means of a step-shaped connecting section 46 as a second channel section 33a, 34a.

[0073] The heat sink 10b shown in Fig. 9 is characterized by the fact that its two channels 24b, 26b are arranged laterally offset from each other in the region of the first channel sections 31b, 32b, such that in the region of the first channel sections 31a, 32a, there is no overlap between the first channel sections 31b, 32b in a direction perpendicular to the longitudinal extent of the first channel sections 31b, 32b, or rather, gaps 47 are present between the first channel sections 31b, 32b. Various arrangements of the first channel sections 31b, 32b are possible, which are described below with reference to Figs. 10 to 14:

[0074] In the embodiment according to Fig. 10, the first channel sections 31b, 32b run completely in different planes 41b, 42b. For example, the first channel sections 31b have a rectangular cross-section, while the first channel sections 32b are each square.

[0075] In Fig. 11, the two planes 41b, 42b partially overlap each other, such that in an intermediate zone 48 both first channel sections 31b and first channel sections 32b are present.

[0076] In contrast, Fig. 12 shows the case where the first channel sections 31b on the side facing the evaporator area 16 have the same distance to the evaporator area 16 as the first channel sections 32b.

[0077] Figure 13 illustrates the case where the first channel sections 31b, 32b of immediately adjacent first channel sections 31b, 32b are arranged alternately on different planes 41b, 42b. However, the first channel sections 31b, 32b each have the same cross-section when considered individually. R.411594

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[0079] In contrast, Fig. 14 shows the case in which the first channel sections 41b, 42b additionally have alternating rectangular and square cross-sections in the different planes 41b, 42b, so that in plane 41b rectangular first channel sections 31b, 32b are arranged next to each other, and in plane 42b first channel sections 31b, 32b with square cross-sections are arranged next to each other.

[0080] Figure 15 shows a heat sink 10c in which its channels 24c, 26c, arranged on different planes, have first channel sections 31c, 32c that are arranged at an oblique angle α to each other. In the illustrated embodiment, the angle α is approximately 60°, but it can typically be between approximately 20° and 90°. It is further shown, purely by way of example, that the first channel 24c, which has a smaller cross-section, runs completely above the second channel 26c, which has a larger cross-section.

[0081] The heat sink 10d according to Fig. 16 has two channels 24d, 26d which are comb-like and interlock in the region of their first channel sections 31d, 32d. By way of example, the first channel sections 31d are closer together than the first channel sections 32d. Furthermore, the first channel sections 31d have a larger cross-section than the first channel sections 32d.

[0082] Figures 17 to 19 show different arrangements of the first channel sections 31d, 32d. While in Figure 17 the first channel sections 31d, 32d are equidistant from the evaporator section 16 or run in the same plane, in Figure 18 the first channel sections 31d, 32d are arranged on different planes 41d, 42d and thus have different distances from the evaporator section 16. As shown in Figure 19, it is also conceivable that the first channel sections 31d, 32d of adjacent first channel sections 31d, 32d run on different planes 41d, 42d. R.411594

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[0084] The cooling element 10e shown in Fig. 20, unlike cooling elements 10, 10a to 10d, has three fluidically separated channels 51, 52 and 53. For example, the three channels 51, 52, 53 are each meandering and interlock like a comb. The three channels 51, 52, 53, whose cooling media A, B and C have different boiling points or operating points, can either be arranged on a common plane (Fig. 21) or on different planes as shown in Fig. 22.

[0085] The cooling element 10f shown in Fig. 23 has four fluidically separated channels 61, 62, 63, and 64 for cooling media with different operating points, wherein the individual channels 61, 62, 63, and 64 have a different number of first channel sections 65, 66, and 67. The first channel 61 has a total of ten first channel sections 65, which are arranged in a meandering pattern relative to each other. In contrast, the oval-shaped second channel 62 has only two first channel sections 66 arranged parallel to each other, which traverse the evaporator area 16 centrally. The identically designed channels 63 and 64 each have only one first channel section 67, which runs opposite each other along the edge regions of the evaporator area 16.

[0086] The cooling element 10g shown in Fig. 24 has two star- or cloverleaf-shaped channels 68, 69 for cooling media with different operating points, arranged one above the other in different planes, with the evaporator section 16 located in a centrally arranged overlapping area of ​​the channels 68, 69. In contrast, the cooling element 10h according to Fig. 25 also has two channels 68, 69, which, however, are arranged in a common plane since there is no overlapping area.

[0087] The heat sink 10, 10a to 10h described so far can be modified or adapted in a variety of ways without deviating from the inventive concept. For example, it is conceivable to assign components 1 with different heat outputs or maximum temperatures to different channels or cooling media in a locally targeted manner, or to integrate them into their R.411594

[0088] - 13 -

[0089] to arrange the area in order to enable specifically adapted cooling of different components 1.

Claims

R.411594 - 14 - Claims 1. Pulsating heat pipe heat sink (10; 10a to 10h), with at least two fluidically separated channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d; 51 to 53; 61 to 64; 68, 69) for guiding a vaporizable cooling medium (A, B, C), with an evaporator section (16) for arranging at least one heat-generating component (1), and with a condenser section (22) arranged at a distance from the evaporator section (16), characterized in that the at least two channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d; 51 to 53; 61 to 64; 68, 69) arranged cooling media (A, B, C) have different operating points from which the respective cooling medium (A, B, C) can be evaporated in the evaporator area (16) by heat input from the at least one heat-generating component (1).

2. Cooling element according to claim 1, characterized in that the cooling media (A, B, C) consist of at least two different substances with different boiling points.

3. Cooling element according to claim 1, characterized in that the cooling media (A, B, C) each consist of at least two identical substances with different boiling points, and that the mixing ratio of the at least two substances in the cooling media (A, B, C) is different.

4. Heat sink according to one of claims 1 to 3, characterized in that, R.411594 - 15 - that the cooling media (A, B, C) arranged in the at least two channels (24; 24a; 24b; 24c; 24d 26; 26a; 26b; 26c; 26d; 51 to 53; 61 to 64; 68, 69) have different fill levels in the at least two channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d; 51 to 53; 61 to 64; 68, 69).

5. Heat sink according to one of claims 1 to 4, characterized in that the at least two channels (24b; 24d, 26b; 26d; 51 to 53; 61 to 64; 68, 69) are arranged at least in the evaporator area (16) in the area of ​​a single plane.

6. Cooling sink according to one of claims 1 to 4, characterized in that the at least two channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d; 51 to 53; 68, 69) are arranged at least in the evaporator area (16) on at least two different levels (41; 41b; 41d, 42; 42b; 42d) with different distances to the evaporator area (16).

7. Heat sink according to one of claims 1 to 6, characterized in that the at least two channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d; 51 to 53; 61 to 64; 68, 69) at least in the evaporator area (16) have different cross-sectional shapes and / or different cross-sectional sizes.

8. Heat sink according to one of claims 1 to 6, characterized in that the at least two channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d; 51 to 53; 61 to 64; 68, 69) have the same cross-sections.

9. Heat sink according to one of claims 1 to 8, characterized in that the at least two channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d; 51 to 53; 61 to 64) are meander-shaped. R.411594 - 16 - 10. Heat sink according to claim 9, characterized in that the at least two channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d; 51 to 53; 61 to 64) at least in the evaporator area (16) have first channel sections (31 ; 31a to 31 d, 32; 32a to 32d; 65, 66) which are arranged parallel to each other.

11. Heat sink according to claim 10, characterized in that the at least two channels (24; 24a; 24b; 24c; 24d, 26; 26a; 26b; 26c; 26d) are intertwined at least in the evaporator area (16).

12. Cooling sink according to claim 10, characterized in that the at least two channels (24d, 26d; 51 to 53; 61 to 64) interlock in a comb-like manner at least in the evaporator area (14).

13. Cooling sink according to claim 9, characterized in that the at least two channels (24c, 26c) have at least in the evaporator area (16) first channel sections (31c, 32c) which are arranged at an oblique angle (a) to each other.

14. Cooling sink according to claim 9, characterized in that the at least two channels (68, 69) are located at least in the evaporator area (16) are star-shaped without mutual geometric overlap.

15. Cooling sink according to claim 9, characterized in that the at least two channels (68, 69) are formed in a star shape with mutual geometric overlap, at least in the evaporator area (16).

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