Pulsating heat pipe heat sink

Abstract

The invention relates to a pulsating heat pipe heat sink (10; 10a to 10e) comprising: a housing (14) in which at least one channel (20; 20a; 20b; 20c; 35, 36; 44, 46; 56, 58, 60) for an evaporable cooling medium is disposed; an evaporator region (12) which can be connected to at least one heat-generating component; and a condenser region (18) for cooling the cooling medium; wherein the at least one channel (20; 20a; 20b; 20c; 35, 36; 44, 46; 56, 58, 60) has a plurality of first channel portions (24, 24a, 24b, 24c, 52) which are arranged parallel to one another and are connected to one another by arcuate second channel portions (26, 26a, 26b), by return portions (28; 40, 42) or by meandering channel portions (54).

Description

[0001] R.411702

[0002] Description

[0003] title

[0004] Pulsating Heat Pipe Heatsink

[0005] Technical field

[0006] The invention relates to a pulsating heat pipe heat sink, which is characterized by a particularly effective cooling of at least one heat-generating component with regard to preferred flow directions of a cooling medium and a high density of the arrangement of channel sections.

[0007] State of the art

[0008] Pulsating heat pipe heat sinks, often referred to simply as heat sinks in the following, are known in various forms from the prior art. Typically, known heat sinks have at least one meandering channel characterized by parallel first channel sections connected to each other by means of arc-shaped second channel sections or return sections.

[0009] Furthermore, such channel geometries are characterized by the fact that they are arranged or formed in a mirror-symmetrical manner relative to a straight line running parallel to the first channel sections.

[0010] Furthermore, point-symmetrical channels are also known, which typically have star-shaped channel sections radiating from an evaporator area. Because the distances between the individual channel sections increase circumferentially and with increasing distance from the center of the evaporator area, the density of channel sections that can be arranged on a given area of ​​the heat sink is limited, which in turn limits the maximum possible cooling capacity. R.411702

[0011] - 2 -

[0012] Disclosure of the invention

[0013] The Pulsating Heat Pipe cooling element according to the invention with the features of claim 1 has several advantages, which are characterized in particular by a particularly good start-up behavior or the formation of a preferred flow direction of the cooling medium as well as by a particularly high cooling performance.

[0014] The invention is based on the idea of ​​designing the channel with parallel first channel sections to achieve the highest possible density or number of channel sections in the heat sink, thereby maximizing cooling performance. Furthermore, a point-symmetrical design of the geometry of at least one channel results in a preferred flow direction for the (vaporizable) cooling medium, enabling particularly good start-up behavior and rapid cooling of the component being cooled. This is due, on the one hand, to the preferred flow direction of the cooling medium, and on the other hand, to the fact that, starting from the evaporator area, cooling paths for the cooling medium are created in two different directions, allowing for the rapid removal of heat energy from the evaporator area towards the condenser area.

[0015] In light of the above explanations, a pulsating heat pipe heat sink according to the invention, having the features of claim 1, therefore comprises a housing in which at least one channel for an evaporable cooling medium is arranged. Furthermore, an evaporator section is provided which can be connected to at least one heat-generating component. Additionally, a condenser section is provided for cooling the cooling medium, wherein the at least one channel has several first channel sections arranged parallel to one another. The first channel sections are connected to one another by means of arc-shaped second channel sections or by means of return sections, wherein the at least one channel is point-symmetrical about an intersection of two straight lines that run parallel and perpendicular to the first channel sections. R.411702

[0016] - 3 -

[0017] According to the invention, point-symmetric about an intersection of two straight lines means that a supply channel typically provided for filling the channel with the cooling medium is not taken into account in the point-symmetric design of the channel.

[0018] Advantageous further developments of the Pulsating Heat Pipe cooling body according to the invention are listed in the dependent claims.

[0019] Based on the above-described basic idea of ​​a point-symmetric design or arrangement of the at least one channel, preferred geometric configurations are described below, which can be advantageously adapted to the respective application depending on the application, size of the evaporator area, the heat output to be dissipated, etc.

[0020] A first preferred embodiment provides that the intersection of the at least one channel is arranged centrally to the evaporator area. In other words, this means that equal heat transfer distances or thermal conditions are enabled in different directions radiating from the center.

[0021] There are several possibilities regarding the design of the first channel sections. In one embodiment, it is provided that the first channel sections have at least essentially the same length, extending on both sides into the capacitor area.

[0022] Further developing this proposal, it may be provided that the feedback sections extend laterally next to the first channel sections in the capacitor area, running essentially perpendicular to the first channel sections and encompassing several first channel sections laterally.

[0023] An alternative design of the first channel sections provides that they have at least two different lengths: first channel sections that extend on both sides into the capacitor area and shortened first R.411702

[0024] - 4 -

[0025] Channel sections that extend from the evaporator area only to one side of the condenser area.

[0026] In a preferred geometric development of the last proposal, it can either be provided that further shortened first channel sections are arranged in extension of the shortened first channel sections, or that meandering channel sections are arranged laterally next to the shortened first channel sections.

[0027] Furthermore, it is generally conceivable to design the cross-section of at least one channel to be variable. This allows, for example, the flow velocity or pressure of the cooling medium to be influenced or controlled as desired. Preferably, the cross-section of at least one channel has a minimum, at least in the evaporator section.

[0028] Furthermore, the cooling element according to the invention is not limited to the use of a single channel. Rather, for example, two or three fluidically separated channels can be provided. This makes it possible, for example, to provide different cooling media and / or concentrations or fill quantities of the cooling medium in the channels for different temperature ranges, etc.

[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.

[0030] It should be specifically mentioned that various deviations from pure point symmetry are also intended to fall within the scope of the invention if these deviations are characterized solely by the fact that different channel sections have a different length / geometry and / or position. This means that such deviations can be transformed into point symmetry by simple geometric operations (e.g., translation, rotation, or stretching).

[0031] Brief description of the drawings R.411702

[0032] - 5 -

[0033] Figures 1 to 6 show simplified sectional views of differently designed geometries of a heat pipe cooling body.

[0034] Embodiments of the invention

[0035] Identical elements or elements with the same function are provided with the same reference numbers in the figures.

[0036] The pulsating heat pipe heat sink 10 shown in Fig. 1, hereinafter referred to simply as heat sink 10, serves to cool at least one heat-generating component, for example, an electronic component such as a power IC or a similar component. For this purpose, the aforementioned at least one component is thermally connected to a housing 14 of the heat sink 10 within a rectangular evaporator area 12 (square in the exemplary embodiment), for example, by means of a thermally conductive adhesive or a mechanical fixing. The evaporator area 12 has a boundary 15 and is surrounded by a rectangular intermediate zone 16 with a boundary 17, which in turn is surrounded by a rectangular condenser area 18 with a boundary 19.

[0037] The housing 14 of the heat sink 10 is typically multi-part, at least two-part, and has a channel 20 that receives a cooling medium (not shown) in the form of an evaporable cooling medium. To introduce the cooling medium into the channel 20, the channel 20 is connected to a supply channel 22, which opens laterally onto the housing 14 and is designed to be closable to prevent the cooling medium from escaping the heat sink 10.

[0038] Furthermore, as can be seen from Fig. 1, the channel 20 (with the exception of the supply channel 22, which plays at least a substantially negligible role in the operation of the heat sink 10) is arranged within the evaporator section 12, the intermediate zone 16, and the condenser section 18. R.411702

[0039] - 6 -

[0040] Channel 20 has parallel first channel sections 24, with two adjacent first channel sections 24 being connected to each other by arc-shaped second channel sections 26. Furthermore, the two outermost first channel sections 24 are each connected via a return section 28 to the two centrally located first channel sections 24 that pass centrally through the evaporator section 12. The two return sections 28 are located on opposite sides of the condenser section 18 at a short distance from the second channel sections 26. On the opposite side of each return section 28, the second channel sections 26 extend to the edge of the condenser section 18.

[0041] In the evaporator area 12, a first straight line 31 and a second straight line 32 are drawn, the first straight line 31 being parallel to the first channel sections 24, and the second straight line 32 being perpendicular to the first channel sections 24. An intersection point 33 of the two lines 31, 32 coincides with the center of the area of ​​the evaporator area 12.

[0042] The arrangement and design of the channel 20 described so far is, with the exception of the supply channel 22, point-symmetrical about the intersection point 33 of the two lines 31 , 32.

[0043] The heat sink 10a shown in Fig. 2 differs from the heat sink 10 according to Fig. 1 essentially in that the channel 20a in the evaporator section 12 has a total of four first channel sections 24a, which are shorter than the first channel sections 24. Two first channel sections 24a arranged directly next to each other are connected to each other by means of an arc-shaped second channel section 26a. The first channel sections 24a extend essentially from the condenser section 18 into the evaporator section 12. The second channel section 26a adjoins the channel 20a directly on the side of the evaporator section 12 facing away from the condenser section 18. The channel 20a is also point-symmetrical about the intersection 33 of the two lines 31, 32. R.411702

[0044] - 7 -

[0045] Figure 3 shows another heat sink 10b, which differs from the heat sink 10a according to Figure 2 by additional shortened first channel sections 24b of its channel 20b. These first channel sections run parallel to and in extension of the shortened first channel sections 24a and are connected to each other by arcuate second channel sections 26b. Only relatively small gaps 34 are formed between the second channel sections 26a and 26b in the intermediate zone 16. The additional shortened first channel sections 24b of the channel 20b allow the pressure conditions in the channel 20b, which is point-symmetrical with respect to the intersection point 33, to be changed.

[0046] The heat sink 10c shown in Fig. 4 is characterized by two fluidically separated channels 35, 36. Channel 35 forms an inner heat sink structure 37, which is nested within an outer heat sink structure 38 of channel 36. Each of the two heat sink structures 36, 38 has separate return sections 40, 42. The outermost first channel sections 24c of the outer heat sink structure 38 extend outside the condenser area 18. Furthermore, it can be seen that the two channels 35, 36 of the heat sink 10c have different cross-sections. In particular, the channel 35 of the inner heat sink structure 36, in which the evaporator area 12 is also located, has a smaller cross-section than the channel 36 of the outer heat sink structure 38. This design of the two channels 35, 36 enables both redundancy and the possibility of mitigating hot spots in the inner area and / or the outer area.The components in the evaporator area 12 are cooled differently than those with lower power losses, which are located, for example, in the intermediate zone 16. While the outer channel 36 can be filled with the cooling medium via the supply channel 22, the inner channel 35 can be filled with cooling medium via a supply channel 43 arranged perpendicular to the plane of Fig. 4. The cooling media in the two channels 35 and 36 may differ or, for example, have different characteristics. Furthermore, the different geometries of the two channels 35 and 36, which are arranged point-symmetrically about the center point 33, result in differently shaped intermediate zones 16c. R.411702.

[0047] - 8 -

[0048] The cooling element 10d shown in Fig. 5 is also characterized by two fluidically separated channels 44, 46. The two channels 44, 46 are connected on opposite sides to a supply channel 48, 50, respectively. Furthermore, each of the channels 44, 46 has, in addition to first channel sections 24 in the evaporator area 12, shortened first channel sections 52. Laterally adjacent to the shortened first channel sections 52, each of the two channels 44, 46 has a meandering channel section 54. The channel sections 54 cause a pressure drop to promote a preferred flow direction of the respective cooling medium. The arrangement and design of the channels 44, 46 described so far is also (with the exception of the two supply channels 48, 50) point-symmetric about the intersection point 33 of the two lines 31, 32.

[0049] Finally, Fig. 6 shows a cooling element 10e, which has a total of three fluidically separated channels 56, 58, and 60. The two approximately oval-shaped channels 56 and 58 are arranged in the evaporator area 12 directly on both sides of the straight line 31 and can be filled with the cooling medium via a supply connection 62, 64 running perpendicular to the plane of Fig. 6. The outer channel 60 surrounding the channels 56 and 58 is similar in design to the channel 20 of the cooling element 10 and has first channel sections 24, wherein the outermost first channel sections 24 are connected by means of return sections 28 to first channel sections 24 arranged next to the channels 56, 58.

[0050] The heat sinks 10, 10a to 10e described so far are all characterized according to the invention in that they (with the exception of the supply channels 22, 48, 50, 62, 64) are arranged or designed point-symmetrically with respect to the intersection point 33 of the two lines 31, 32. Furthermore, the geometries according to the invention have only been explained by way of example and also include further embodiments that are obvious to those skilled in the art. In particular, the combination of individual geometric elements of the heat sinks 10, 10a to 10e is also possible. For example, even when using only a single channel 20, 20a, 20b, it is possible to design it with a different cross-section for pressure control (R.411702).

[0051] - 9 - to form, wherein the cross-section in the evaporator area 12 preferably has a minimum.

Claims

R.411702 - 10 - Claims 1. Pulsating heat pipe heat sink (10; 10a to 10e), comprising a housing (14) in which at least one channel (20; 20a; 20b; 20c; 35, 36; 44, 46; 56, 58, 60) for an evaporable cooling medium is arranged, comprising an evaporator section (12) which can be connected to at least one heat-generating component, and a condenser section (18) for cooling the cooling medium, wherein the at least one channel (20; 20a; 20b; 20c; 35, 36; 44, 46; 56, 58, 60) has several first channel sections (24, 24a, 24b, 24c, 52) arranged parallel to each other, which are connected by means of arc-shaped second channel sections (26, 26a, 26b), are connected to each other by means of return sections (28; 40, 42) or by means of meandering channel sections (54), and wherein the at least one channel (20; 20a; 20b; 20c; 35, 36; 44, 46; 56, 58, 60) is formed point-symmetric to an intersection point (33) of two lines (31, 32) which run parallel and perpendicular to the first canal sections (24, 24a, 24b, 24c, 52).

2. Cooling element according to claim 1, characterized in that the intersection point (33) is arranged centrally to the evaporator area (12).

3. Heat sink according to claim 1 or 2, characterized in that the first channel sections (24) have at least substantially the same length and extend on both sides into the condenser area (18).

4. Heat sink according to claim 3, characterized in that the feedback sections (28; 40, 42) extend laterally next to the first channel sections (24) in the condenser area (18), which R.411702 - 11 - run essentially perpendicular to the first channel sections (24) and encompass several first channel sections (24) laterally.

5. Cooling sink according to claim 1 or 2, characterized in that the first channel sections (24, 24a) have at least two different lengths, first channel sections (24) extending from the evaporator area (12) on both sides to the condenser area (18) and shortened first channel sections (24a) extending from the evaporator area (12) only to one side of the condenser area (18).

6. Cooling element according to claim 5, characterized in that further shortened first channel sections (24b) are arranged as an extension of the shortened first channel sections (24a).

7. Cooling element according to claim 5, characterized in that the meandering channel sections (54) are arranged laterally next to shortened first channel sections (52).

8. Heat sink according to one of claims 1 to 7, characterized in that the size of the cross-sectional area of ​​the at least one channel (20; 20a; 20b; 20c; 35, 36; 44, 46; 56, 58, 60) is not constant or that several channels (35, 36; 44, 46; 56, 58, 60) with different, each constant, cross-sectional areas are provided.

9. Cooling element according to claim 8, characterized in that the cross-section of the at least one channel (20; 20a; 20b; 20c; 35, 36; 44, 46; 56, 58, 60) has a minimum at least in the evaporator area (12).

10. Heat sink according to any one of claims 1 to 9, R.411702 - 12 - characterized in that at least two fluidically separated channels (35, 36; 44, 46; 56, 58, 60) are provided.

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