Modular heat sink with space-filling cooling channel structure

Abstract

The invention relates to a modular heat sink, in particular a liquid heat sink (1) for a power semiconductor (10), wherein the liquid heat sink (1) has at least one inlet (2) and an outlet (3) in a housing (4) which surrounds the liquid heat sink (1) and to which the power semiconductors (10) are directly thermally coupled at least on one side of the housing (4), an open channel structure (11) is provided in a heat-conducting material, said channel structure being closed by a cover of the housing (4), and the channel structure (11) of the liquid heat sink (1) is designed as a modified space-filling curved portion.

Description

[0001] Description

[0002] Modular heatsink with space-filling cooling channel structure

[0003] The invention relates to a modular liquid heat sink and a converter with such a liquid heat sink.

[0004] The heat sinks previously used in power semiconductors either have too low a pressure drop with insufficient cooling efficiency or uneven cooling on the surface to be cooled.

[0005] Thus, an unsatisfactory compromise was always made between cooling uniformity and heatsink pressure drop. The thermal performance of the overall heatsink resulted from the thermal performance of the worst-cooled component. This led to lower cooling effectiveness.

[0006] Up to now, an increase in the pressure drop has been achieved either by narrowing the cooling channel cross-section and increasing the cooling channel length or by narrowing the inlet and return lines by means of orifices.

[0007] However, more uniform cooling of multiple components, achieved by parallel branched cooling circuits and parallel cooling of the components, produces a lower pressure drop.

[0008] The way in which the pressure drop is generated varies. The known solutions generate the pressure drop through a high flow velocity of the cooling medium in the cooling channel of the heat sink, which can be achieved by narrowing the channel / extending the channel length or by narrowing the inlet and return lines of the heat sink.

[0009] Conversely, an increased pressure drop, achieved by narrowed and longer cooling channels and serial cooling of the components, leads to a more uneven cooling of the overall cooling surface.

[0010] The pressure drop primarily results from an increase in the speed of the cooling medium, which is caused by a cooling channel with a cross-section that is too narrow. The cooling channels are therefore either long or the cooling fluid is moved in a spiral pattern. Consequently, the sensitivity of the heat sink to pressure drop fluctuations and, in addition, to manufacturing variations is increased. Based on this, the invention is based on the object of providing a liquid heat sink that, among other things, avoids the aforementioned disadvantages and ensures efficient cooling, particularly of power semiconductors in an electric drive.

[0011] The solution to the problem is achieved by a combination of features of the independent claims.

[0012] Advantageous embodiments can be found in the dependent claims.

[0013] A modular heat sink, specifically a liquid heat sink, was created in which the channel shape is modular in its length. Each module was created as a modified space-filling curve, such as those found in Hilbert or Peano curves. This makes it possible to almost completely fill any surface, e.g., the heat sink surface, with an arrangement of correspondingly similar, especially identical, cooling channel modules, and thus thermally optimize it.

[0014] According to the invention, there is now a modularly constructed heat sink, in particular a liquid heat sink with a space-filling channel structure, in particular in one plane.

[0015] Gases such as air are conceivable as cooling media, but above all liquids such as water.

[0016] This heatsink features a comparatively higher or adjusted pressure drop. This results in a uniform cooling performance of the heatsink, ensuring a sufficiently uniform thermal performance of the heatsink.

[0017] This eliminates the need to oversize the heat sink, as all components thermally coupled to this heat sink are cooled comparably well and evenly.

[0018] A pressure drop in the heat sink is now generated by redirecting the flow direction of the cooling medium, which causes additional mixing of the fluid layers and leads to a turbulent boundary layer. According to the invention, this leads to a higher heat transfer coefficient between the heat sink and the component to be cooled and thus to a comparatively better thermal performance of the entire cooling system. The cooling channel can be designed so that the fluid velocities are comparatively moderate. The fluid velocity is between 1 and 3 m / s; a fluid velocity of 2.2 m / s has proven particularly advantageous.

[0019] According to the invention, the pressure drop is not generated by a cross-sectional constriction and a high channel length, but by a change in the flow direction and a highly turbulent flow with high heat transfer capacity.

[0020] If several components need to be cooled, the modules can be arranged in series so that the fluid cools the components one after the other in several alternating flows to achieve uniform cooling.

[0021] According to the invention, a small temperature gradient is established between different areas of a modular heat sink according to the invention, so that a uniform cooling effect is achieved over the entire heat sink.

[0022] The change in flow direction is achieved in the channel structure by redirecting the flow direction of the cooling medium. The channel of the channel structure undergoes several turns or changes of direction, ranging from a few degrees up to 180 degrees.

[0023] A particularly efficient, space-filling channel structure is created by diverting the channel in the same direction. These individual diverters can be arranged directly one after the other or spaced apart. The key is to create a particularly space-filling structure in each case.

[0024] The comparatively small distance between the individual windings of the cooling channels results in thermal uniformity across the entire heat sink, so that a comparatively small temperature gradient is established within the heat sink and the components to be cooled.

[0025] Ideally, in a module or the entire heat sink, the distance between two adjacent cooling channels corresponds to the channel width, at least in sections, which supports thermal homogenization within the heat sink.

[0026] According to the invention, the pressure drop in the channels of the heat sink is generated by a targeted redirection of the fluid flow direction, while the fluid velocity remains moderate. This advantageously leads to comparatively better turbulent swirling of the cooling medium in the cooling channel, thus creating a turbulent boundary layer and thus a higher heat transfer coefficient. These factors lead to improved cooling performance.

[0027] The design of the cooling channel is different. In the known solutions, the channel is not constructed modularly.

[0028] In the invention, the heat sink / cooling channel consists of several modules that can be connected to each other in different directions, for example, via sleeves. This allows a heat sink to be easily scaled with almost identical modules and thus easily expanded.

[0029] The advantage is more even cooling of the surface to be cooled and an increase in heat output.

[0030] Another advantage is that modularization allows heat sinks with different sized cooling surfaces to be designed, constructed and thermally designed simply by varying the number and connection of identical modules.

[0031] Another advantage is that different pressure drops can be generated by scaling only one module, e.g. by changing the channel depth, without changing the shape of the module.

[0032] The invention and further advantageous embodiments of the invention are explained in more detail using exemplary embodiments shown in principle, in which:

[0033] FIG 1 Cooling channel without heat sink,

[0034] FIG 2 Heat sink with channel,

[0035] FIG 3 Heat sink with cooling channel and electronic components to be cooled,

[0036] FIG 4 Section through heat sink,

[0037] FIG 5 perspective view of the heat sink.

[0038] It should be noted that terms such as "axial," "radial," "tangential," etc., refer to the axis used in the respective figure or example described. In other words, the directions axial, radial, and tangential always refer to an axis. "Axial" describes a direction parallel to the axis; "radial" describes a direction orthogonal to the axis, toward it, or away from it; and "tangential" is a direction that is directed in a circle around the axis at a constant radial distance from the axis and at a constant axial position. The term "circumferential" is synonymous with "tangential."

[0039] With reference to a surface, e.g. a cross-sectional area, the terms “axial”, “radial”, “tangential” etc. describe the orientation of the normal vector of the surface, i.e. the vector that is perpendicular to the surface in question.

[0040] The term "complementary," in the context of two components that are "complementary" to each other, means that their external shapes are designed such that one component can preferably be arranged completely within its complementary component, so that the inner surface of one component and the outer surface of the other component ideally touch each other seamlessly or over their entire surface. Consequently, in the case of two complementary objects, the external shape of one object is determined by the external shape of the other object. The term "complementary" could be replaced by the term "inverse."

[0041] For the sake of clarity, in some cases where components are present multiple times, not all of the components shown are provided with reference symbols.

[0042] The described embodiments can be combined in any way. Individual features of the respective embodiments can also be combined without departing from the essence of the invention.

[0043] FIG. 1 shows the course of a cooling channel 9 of a modular heat sink, in particular a liquid heat sink (1). The course of the cooling channel 9 forms a modified space-filling curve, such as those known as Hilbert or Peano curves.

[0044] A pressure drop is generated by redirecting the flow direction of a cooling medium, such as a liquid or gas, which causes additional mixing of the fluid layers of the cooling medium and leads to a turbulent boundary layer. According to the invention, this leads to a higher heat transfer coefficient between a heat sink 1 and a component, such as a power semiconductor 10. This results in comparatively better thermal performance of the entire cooling system. The cooling channel 9 covers almost the entire surface to be cooled, as can be seen, for example, in FIG. 3. The arrangement of the cooling channels of the modules 13, 14 and / or the heat sink 1 runs in particular in one plane.Due to the comparatively small distance between the individual turns of the channel structure 11 of the cooling channels 9, thermal homogenization is achieved across the entire heat sink 1, so that a comparatively small temperature gradient with uniform cooling performance is present within the heat sink 1 and the components to be cooled.

[0045] FIG. 2 shows a heat sink 1 with the course of the cooling channel 9 and its inlet 2 and outlet 3. The parts of a housing 4 of the heat sink 1 can preferably be secured via fastening points 8. The power semiconductor components 10 can also be secured via these fastening points 8.

[0046] FIG. 3 shows the heat sink 1 with the areas exposed to the channel structure 11, which are provided with power semiconductor components 10 to be cooled. The modules 13, 14 shown as examples are also sketched, with which almost any heat sink 1 can be designed. Module 13 shows a cooling channel that is structured similarly to a Hilbert or Peano curve and has a specific pressure drop. Module 14, for example, is a modified module 13 (e.g., rotated by 180°) that is extended / adapted for other components to be cooled. The pressure drop essentially corresponds to module 13.

[0047] The pressure drop in heat sink 1 or in modules 13, 14 is generated by the redirection of the cooling fluid in cooling channel 9 and not by a narrowing of the channel's cross-section or the channel length. The total pressure drop in heat sink 1 is thus the sum of the pressure drops across all modules 13, 14—preferably connected in series—which makes heat sink 1 modular and scalable.

[0048] The pressure drop of an individual module 13, 14 can be adjusted during production via the shape and / or cross-section of its cooling channel 9. If a heat sink 1 has several modules 13, 14, these can be fluidically coupled via sleeves (not shown in detail).

[0049] FIG. 4 particularly advantageously shows the modular channel structure 11 of the heat sink 1, which, according to the invention, is scalable and easily expandable. The modules 13, 14 are assembled as needed. The heat sink 1 is made of a highly thermally conductive material, into which the channel structure 11 is embedded. This channel structure 11 of the entire heat sink 1 or of the individual modules 13, 14 was, for example, milled into a block of material. It is also possible to 3D print the heat sink 1 with this channel structure 11.

[0050] FIG 5 shows a perspective view of a heat sink 1 with the fastening points 8 to which the power semiconductor components 10 can be attached. Advantageously, a thermally conductive paste is provided between the heat sink 1 and the power semiconductor components 10 to improve thermal coupling.

[0051] List of reference symbols

[0052] 1 heat sink

[0053] 2 Inlet 3 Outlet

[0054] 4 housings

[0055] 6 Width of the cooling channel

[0056] 7 Component to be cooled

[0057] 8 Mounting points 9 Cooling channel

[0058] 10 Power semiconductor components

[0059] 11 Channel structure

[0060] 12 lids

[0061] 13, 14 modules

Claims

Patent claims 1. A modularly constructed heat sink, in particular a liquid heat sink (1) for a power semiconductor (10), the liquid heat sink (1) having at least one inlet (2) and one outlet (3) in a housing (4) which surrounds the liquid heat sink (1) and to which the power semiconductors (10) are thermally directly coupled at least on one side of the housing (4), an open channel structure (11) being provided in a thermally conductive material which is closed by a cover of the housing (4), the channel structure (11) of the liquid heat sink (1) being designed as a modified space-filling curve, a pressure drop being generated in the heat sink by deflecting the flow direction of the cooling medium, which pressure drop brings about additional mixing of fluid layers, up to four deflections of the channel structure in one direction being provided in some sections in order to create a space-filling curve.

2. Modular heat sink, in particular liquid heat sink (1) according to claim 1, characterized in that the deflections are up to 360°.

3. Modular heat sink, in particular liquid heat sink (1) according to claim 1 or 2, characterized in that the shape of the channel structure (11) is modular in its length.

4. Modular heat sink, in particular liquid heat sink (1) according to one of the preceding claims, characterized in that the same channel width (6) is provided in the course of the cooling channel (9) of a module and / or the liquid heat sink (1).

5. Modular heat sink, in particular liquid heat sink (1) according to one of the preceding claims, characterized in that at least in sections different channel depths are provided within the heat sink, in particular liquid heat sink (1) while maintaining the channel structure (11).

6. Inverter of an electric drive, which has at least one modularly constructed heat sink, in particular a liquid heat sink (1) according to at least one of the preceding claims.

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