Cooling device for cooling electronic components and its use

Abstract

For efficient cooling of electronic components (3), in particular power electronics in an electric vehicle, the electronic components (3) are provided on an outer side of a first coolant chamber wall (2A) of a cooling device (1). The cooling device (1) has an inner coolant chamber (10) with an array of compartments (14) formed by first and second fins (13A, 13B) lateral to the flow direction (5).

Description

[0001] Cooling device for cooling electronic components and its use

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to cooling device for cooling electronic components and its use thereof, for example for an electric vehicle. It is also applicable in applications where high-power electronic components require liquid cooling, for example wind turbines or solar inverters.

[0004] BACKGROUND OF THE INVENTION

[0005] In electric vehicles, the available power for propulsion is regulated in modules that contain power converters, switches, and regulators, which are subject to heating and which must be cooled in order to avoid damage. Especially during accelerations, electric vehicles, EV, need power in excess of 100 kW, for example up to 500 kW as in popular EV models at the time of filing of this application, and although only a small percentage of this power is converted to heat in the electronic power control system, the heat created in the electronic system can be as much as several kW, and with a local power density of more than 500 W / cm2, which is substantial. To give an impression of this power, it is put forward that this power density is more than what a kitchen cooking plate produces. This heat has to be removed efficiently from the electronics in order to prevent damage by overheating. Accordingly, cooling of the electronics is a serious issue in EVs.

[0006] This issue is discussed in detail in US11644253 and corresponding US2021 / 037678A1, disclosing a cooling module for a power converter. For efficient cooling, this disclosure suggests two opposite parallel thermally conducting walls for cooling electronics on the outer side of each of the walls. A flow field for coolant is provided inside the volume between the two walls. Each of the walls has on its inner side a plurality of parallel fins extending from the respective wall for forming the flow field. The two sets of fins are combined and arranged intertwined so that one fin from one of the walls is located between two fins from the opposite wall. The fins are shorter than the distance between the walls so that the flow field causes the coolant to flow between two fins to the one of the walls, then change direction at the wall and continues its flow into a space between a neighboring pair of fins to the opposite wall, where the coolant changes direction again, so as to continue flowing in a meander-shaped flow path through the coolant volume. The cooling fins are corrugated and form flow channels for providing low pressure drop and high flow speed, which increases the throughput of coolant through the cooling module.

[0007] Although, the considerations expressed in US 11644253 appear as an improvement relatively to older prior art, it has a disadvantage of substantial high pressure drop if the number of fins is high, which is due to the fact that the coolant is changing directions into opposite flows for each further fin. Serpentine paths are disclosed in DE102017109890A1, EP1683404B1, US2012 / 0139096A1, US2021 / 0130002A1, US2022 / 0170706A1. Various alternatives are disclosed in CN105514064A, EP3772096A1, and WO2012 / 153414A1.

[0008] DE112022002737T5 discloses a cooling unit in which corrugated ribs are connecting two opposite walls, where the corrugated ribs are perforated for coolant flow through the ribs.

[0009] US11293697 discloses a cooling device with a cold plate on which there are provided semiconductor elements. A coolant flow chamber is provided between the cold plate and an opposite plate that is arranged in parallel with the cold plate. Corrugated ribs extend from the cold plate to the opposite plate, the ribs being fastened to both plates. Adjacent corrugated ribs are corrugating in opposite directions, so as to create wiggling channels for flow of the coolant, the average motion of the wiggling path of the coolant being largely in parallel with the cold plate. Although, the wiggling motion creates turbulence, which is beneficial for cooling, the mixing action is not optimum, as there is only very little force that is pressing the coolant towards the cold plate, where the semiconductors have to be cooled. Accordingly, there is still potential for improvement for more efficient cooling.

[0010] Despite the above-mentioned systems, which are disclosing various forms for advantages, there is a still an ongoing motivation to further improve cooling modules and there is still room for improvements and alternative configurations for efficient cooling of high power electronics, such as inverters and converters in vehicles.

[0011] DESCRIPTION / SUMMARY OF THE INVENTION

[0012] It is therefore an objective of the invention to provide an improvement in the art. In particular, it is an objective to provide efficient cooling systems for electronics which are suitable for low-cost mass production, in particular in connection with electric vehicles. It is a further objective to provide a cooling device for cooling of electronics on a thermally conductive support plate in which the temperature distribution in the support plate is uniform. This objective and further advantages are achieved with a cooling device for cooling electronic components, its use, and method of operation, as described below.

[0013] For clarification of the invention described herein in view of the prior art described above, especially in view of US11644253, it must be explained here as an offset that the invention described herein takes a different approach to solve the problem of efficient cooling of electronics as compared to the principle disclosed in US11644253. By studying the meander path of the coolant through the channels formed by the corrugated fins in US 11644253, it is understood that the smooth canal-forming fins involve reduced turbulence of the coolant, which bring about the low pressure drop and high flow speed that is aimed at in US11644253. However, a consequence of reduced turbulence is reduced mixing of the coolant inside the channels, which in turn implies a risk of the coolant becoming hot near the cooling fins but remaining cooler in the center of the channels, so that the capacity of the coolant is not fully exploited. In the invention presented herein, the solution follows a different approach with increased turbulence and mixing.

[0014] In short, for cooling of electronic components, for example power electronics in an electric vehicle, the electronic components are provided on an outer side of a first coolant chamber wall of a cooling device. The cooling device has an inner coolant chamber with an array of fins that form compartment walls between multiple compartments, which are lateral or approximately lateral to the flow direction. For flow through the compartment, the coolant crosses the fins, which creates turbulence in the compartments for better mixing of the coolant and increased thermal uptake.

[0015] Details are explained in the following.

[0016] The electronic components that are to be cooled are in thermal contact with an outer side of a thermally conducting first coolant chamber wall. For cooling purposes, the cooling device comprises a coolant chamber delimited by an inner side of the first coolant chamber wall and an inner side of an opposite second coolant chamber wall. The inner sides of the first and second coolant chamber walls are facing each other at an interdistance. Typically, for simplicity in production, the first and the second coolant chamber walls are planar and arranged parallel to each other with an interplanar distance. The coolant chamber is further delimited by a first and a second coolant chamber side wall.

[0017] The coolant, for example water, optionally containing glycol, flows through the coolant chamber along an average flow direction from a coolant inlet to a coolant outlet for cooling the first coolant chamber wall, and optionally also the second coolant chamber wall, in particular if the second coolant chamber wall also carries electronics on its outer side for cooling.

[0018] The coolant flow from the coolant inlet to the coolant outlet is along the inner sides of the first and second coolant chamber walls and the first and second coolant chamber side walls, which in common confine the coolant flow through the coolant chamber from one end to the opposite end.

[0019] The cooling device comprises a first array of multiple side-by-side placed, thermally conductive first fins, each of which is connected to the inner side of the first coolant chamber wall by a thermally conductive and sealing connection and has a first end that extends therefrom a first distance from the inner side of the first coolant chamber wall into the coolant chamber towards the second coolant chamber wall. The coolant chamber comprises as well a second array of multiple side-by-side placed second fins, each of which is sealingly connected to the inner side of the second coolant chamber wall and has a second end that extends a second distance from the inner side of the second coolant chamber wall into the coolant chamber towards the first coolant chamber wall. The term sealingly implies that it is liquid tight and no liquid passes through the connection at the respective coolant chamber wall.

[0020] Notice that the connection between the fins and the respective coolant chamber wall conducts heat away from the electronics through the coolant chamber wall and into the coolant. Typically, the coolant is a liquid.

[0021] Optionally, the device has only one coolant chamber wall that is provided with electronic components on its outer side, but it is also possible to provide electronic components on an outer side of the opposite second coolant chamber wall of the device. As the first coolant chamber wall carries electronics, it is made of a thermally conducting material as well as the first fins, for example metal, and the first fins are in thermally conductive connection with the first coolant chamber wall for removal of thermal energy from the electronics, through the first coolant chamber wall, and through the fins into the coolant. Similar conditions are valid for the second coolant chamber wall if it also carries electronics that have to be cooled. Otherwise, this is not necessary, and the second coolant chamber wall and the second fins are not necessarily made of a thermally conducting material.

[0022] Although, the coolant does not move linearly but with turbulence, there is average flow direction for coolant through the coolant chamber from a coolant inlet to a coolant outlet for cooling the first coolant chamber wall.

[0023] For example, the first and second arrays of fins pairwise form an array of compartment walls, each of which is separating two neighboring of multiple compartments. Optionally, the arrays of compartments are delimited by the first and second coolant chamber wall, the first and second coolant chamber side wall and the first and second fins.

[0024] The fins and compartments are oriented perpendicular or almost perpendicular to the average flow direction. In more detail, each of the first fins and the second fins, and, correspondingly, the compartments, extend from the first to the second coolant chamber side wall and are oriented within the range of 70-110 degrees, for example within the range of 80-100 degrees, or even within the range of 85 to 95 degrees, relatively to the average flow direction. The coolant has to cross all first fins, second fins, and compartments during flow of the coolant through the coolant chamber.

[0025] The first distance by which the first fins extend from the first coolant chamber wall and the second distance by which second fins extend from the second coolant chamber wall are optionally identical but need not be so. However, the first distance, when measured in a perpendicular direction from the inner side of the first coolant chamber wall, and the second distance, when measured in a perpendicular direction from the inner side of the second coolant chamber wall, is at least 20%, for example at least 30%, but less than 100%, of the coolant chamber wall interdistance.

[0026] In comparison to US 11293697 that was discussed in the introduction, where fins are extending from the cold plate to the opposite plate, it is pointed that the principle of the invention is generally different in that the corrugations are perpendicular in the invention as compared to the disclosure in US 11293697. In the invention, the corrugations wiggle along a plane parallel with the first coolant chamber wall, whereas the corrugations wiggle along a plane perpendicular to the cold plate in US 11293697. This implies differences in several points. First of all, in contrast to US 11293697, the corrugated fins are not extending from the first coolant chamber wall to the opposite, second coolant chamber wall. Thus, the first and second fins extends less than 100% of the coolant chamber interdistance into the coolant chamber.

[0027] Each of the thermally conducting first fins is connected only to the inner side of the first coolant chamber wall by a thermally conductive and sealing connection but not connected to the inner side of the second coolant chamber wall and extends towards but not to the second coolant chamber wall. Similarly, each of the second fins is sealingly connected to the inner side of the second coolant chamber wall but not connected to the inner side of the first coolant chamber wall and extends towards but not to the first coolant chamber wall.

[0028] The sum of the first and second distance is 80-100% of the coolant chamber wall interdistance. In other words, either, the ends of the fins meet, or there is a minor distance in between the first and the second fins, forming a gap, for example due to mechanical tolerance in fabrication. In no event, the distance of the gap would exceed 20%, for example be equal to or less than 10%, of the interdistance, and the gap would typically be smaller. This is useful for creation of turbulence in the compartments that are formed by the each other opposing first and second fins.

[0029] For example, the gap is in the order of 0.05-3 mm. In particular, a gap of 0.1-1 mm has been found useful.

[0030] In order to make sure that the first fins and the second fins actually meet each other on a contact area when the cooling device is assembled, while preventing overload on the contact area due to manufacturing tolerances where the sum of the length of the fins slightly exceed the wall interdistance, the second fins optionally are made of a resilient material for compression. For this purpose, in more detail, the sum of the first and second distance is more than 100% of the coolant chamber wall interdistance when in a state prior to assembly and equal to 100% in assembled state due to compression of the resilient second fins.

[0031] The first fins or the second fins or both have an undulating shape. The undulation causes turbulence in the coolant when it crosses the laterally undulating compartment walls.

[0032] The undulating shape of the first fins has a first undulation wavelength, and the undulating shape of the second fins has a second undulation wavelength. Optionally, the first undulation wavelength is different from the second undulation wavelength.

[0033] For example, when the fins do not meet but have a minor distance, as explained above, the coolant will be pressed through the narrow slit and experience influence on its further flow direction behind the slit due to the lateral undulations of the fins. The coolant will be directed upwards and downwards, respectively, by every second of the undulations. For example, first bend portions of the undulations, which are bend in an upstream direction, causes downwards bending of the coolant just behind the first bend. Second bend portions of the undulations, which are bend in a downstream direction, causes upwards bending of the coolant just in front of the second bend. The combination causes both upwards and downwards motion of the coolant when entering the compartment behind such undulating fin, which results in vigilant turbulence of the coolant, mixing warmer and colder portions of the coolant and equalizing the temperature in a compartment. This, in turn, increases the cooling efficiency.

[0034] In the embodiment, where each of the first fins extends to one of the second fins, coolant flows from one compartment to the subsequent compartment through multiple canals connecting the compartments .

[0035] In particular, as an example, each combination of one of the first fins and one of the second fins forms multiple first and second canals through the respective compartment wall. This is achieved by the combination of first and second fins, where the first fins or the second fins or both have an undulating shape. For example, both have an undulating shape and are mirrored relatively to each other, as will be exemplified in more detail below.

[0036] Optionally, as an alternative, the first fins are undulating and the second fins are straight, or vice versa.

[0037] In some specific of such embodiments, for each such combination of one of the first fins and one of the second fins, each first canals is formed by a first portion of the first fin of the combination and a first portion of the corresponding second fin of the combination, and each second canals is formed by second portions of the first fin of the combination and a second portion of the second fin of the combination, the second portions being different from the first portions. The first and second canals are arranged alter- natingly along the compartment walls with one of the first canals between two of the second canals and one of the second canals between two of the first canals. Each first canal has a first coolant flow direction and each second canal a second coolant flow direction from one compartment through the compartment wall into a subsequent compartment along the average flow direction. The first flow directions is towards the first coolant chamber wall but not towards the second coolant chamber wall and the second flow directions is towards the second coolant chamber wall but not the first coolant chamber wall.

[0038] In comparison to the aforementioned US11644253, it is emphasized that the coolant in US11644253 flows unidirectional along one side of a wall and then shift direction to flow in opposite direction on the opposite side of the wall, which is typical in meanderflow. This implies that the coolant enters a compartment in only one direction and moves in an almost laminar flow along the undulated fins inside the compartment. In the invention, the coolant flows from one compartment to the subsequent compartment across the undulated fins and is deflected by the undulated fin into two opposite directions simultaneously which creates turbulence inside the subsequent compartment.

[0039] In the cooling device described herein, the flow crosses all undulating fins largely laterally, as the average flow through the cooling chamber is largely laterally to the arrays of fins.

[0040] Each of the first fins and / or the second fins has an alternating wave-form that is undulating about a line parallel with the first coolant chamber wall so as to comprise a first set of bends on a first side of the line and a second set of bends on a second, opposite side of the line. The first set of bends are directed upstream and the second set of bends are directed downstream. For example, the line is perpendicular to the average flow direction. Alternatively, the line is inclined and deviates in the range of up to 10 degrees, or even up to 20 degrees, from the perpendicular direction, the latter being equivalent to an angle in the range of 70-110 degrees relatively to the average coolant flow direction.

[0041] For some of the embodiments, where fins meet, the first and second bends, respectively, constitute the above-mentioned canal-forming first and second portions of the first fin, which in combination with the corresponding second fin form the first and second canals.

[0042] In more general embodiments, the first end of each of the first fins meets the second end of at least one of the second fins, but not necessarily only one of the second fins. Similarly, the second end of each of the second fins meets the first end of at least one of the first fins, but not necessarily only one of the first fins.

[0043] Alternatively, the first and second fins do not meet but are provided with a space in between of no more than 10% of the coolant chamber wall interdistance. In particular, the first end of each one of the first fins face but does not contact the second end of at least one of the second fins, but not necessarily only one of the second fins. Similarly, each of the second end of each one of the second fins face the first end of at least one of the first fins, but not necessarily only one of the first fins.

[0044] In some embodiments, which eases production, the second fins are identical to the first fins but rotated 180 degrees about a line perpendicular through the first coolant chamber wall so as to provide the second fins as mirrored relatively to the first fins and relatively to a plane perpendicular to the first coolant chamber wall. In such embodiments, the first coolant chamber wall with its first fins is similar to the second coolant chamber wall with its second fins, so that both the first and the second fins are undulated.

[0045] Optionally, the compartments and the compartment walls are oriented perpendicular to the average flow direction. For undulating fins and walls and compartments, the perpendicular direction of the fin, the wall and the compartment are meant to be the average direction being perpendicular to the average flow direction. Alternatively, these directions deviate up to 10 degrees or even up to 20 degrees from the perpendicular direction.

[0046] Optionally, the first fins are perpendicular to the first coolant chamber plate.

[0047] Optionally, the second fins are perpendicular to the second coolant chamber plate.

[0048] Optionally, the first and the second coolant chamber walls are parallel.

[0049] Although, the fins can be mounted onto the inner side of the respective coolant chamber wall, it can be advantageous if the first fins are integral with the first coolant chamber wall. For example, the first fins and the first coolant chamber wall are formed out of a single piece of material. An option in this respect is a single forged metal block. Metal forging under high pressure is a fast production method, and due to the first coolant chamber wall and first fins being a single metal piece, where the metal is thermally conducting, good thermal conductivity is provided from the coolant chamber wall through the fins to the coolant. As an alternative to metal forging, molding of metals or other thermally conducting materials, such as thermally conducting polymers, is useful or sintering of thermally conductive ceramics Optionally, the cooling device comprises one or more cooling modules in a housing, typically also comprising a manifold for the distribution of coolant into and out of the modules. The cooling device has a coolant inlet and a coolant outlet and a coolant flow path in an inner volume of the device and through a coolant chamber for each of the modules, from the coolant inlet to the coolant outlet. Electronics are provided on each module wall for efficient cooling, as the electronics have thermal contact to the thermally conducting wall, for transfer of thermal energy from the electronic components through the module wall and to the circulating coolant inside the coolant chamber of the module. Each module wall is formed similar to the first coolant chamber wall described above with its fins reaching into a coolant chamber inside the housing. Optionally the housing forms the second coolant chamber wall for each of the modules.

[0050] The term undulating wave-form is used for a structure that is repetitive alternating in a straight or bent plane, for example a structure with edges, such as a zigzag-shaped structure, or a smoothly undulating structure, such as a sine-shaped structure.

[0051] Optionally, all first fins are shaped mutually identical and arranged mutually equidistant with a first fin distance when measured along the average flow paths, and all second fins are shaped mutually identical and arranged mutually equidistant with a second fin distance when measured along the average flow paths. The first fin distance and the second fin distance are optionally identical but can also be different.

[0052] The coolant chamber encloses at least three, but typically more than three first and second fins.

[0053] Typically, the compartment walls comprises at least three first canals and three second canals.

[0054] Useful dimensions have been found in the first fins extending a first distance of 2-8 mm from the first coolant chamber wall. Similarly, it has been found useful if the second fins extend a second distance of 2-8 mm from the second coolant chamber wall. Advantageously, the fins are non-perforated, in contrast to DE112022002737T5. In other words, the fins do not contain perforations through which the coolant would be able to flow, but the coolant is forced to flow around the fins in order to advance.

[0055] The cooling device is useful in particular for cooling power electronics, e.g. in an electric vehicle (EV) or a wind turbine, for example cooling power modules, converters and / or inverters.

[0056] Typical dimensions of the cooling module are 50-250mm x 50-250mm x 5-30mm for automotive applications.

[0057] For example, dimensions of a cooling device, when used for a personal electric vehicle, are approximately 200 mm x 60 mm x 15 mm.

[0058] For renewable energy applications, such as the power electronics in wind turbines where several MW are processed or off-road electric vehicles for example mining the cooling device dimension will be on the order of 200-800mm x 200-800mm x 20-80mm.

[0059] Although, the device is particularly useful for vehicles, it is of more general character and can also be advantageous for use in an industrial machine for cooling electronic components. Another advantageous use is in a wind turbine for cooling electronic components. It is also applicable in other applications where high-power electronic components require liquid cooling, for example solar inverters.

[0060] SHORT DESCRIPTION OF THE DRAWINGS

[0061] The invention will be explained in more detail with reference to the drawing, where FIG. 1 A illustrates a cooling device in perspective view;

[0062] FIG. IB is a perspective view of first fins on the first coolant chamber wall;

[0063] FIG. 2A is an overlay image of first and second fins;

[0064] FIG. 2B is a perspective cross sectional side view into the coolant chamber;

[0065] FIG. 2C is an enlarged explanatory section of FIG. 2B;

[0066] FIG. 3 A is a perspective view of an alternative embodiment

[0067] FIG. 3B is an enlarged section of FIG. 3 A; FIG. 3C is an enlarged explanatory section of FIG. 3A;

[0068] FIG. 4A illustrates flow of the coolant through the coolant chamber;

[0069] FIG. 4B is an enlarged section of FIG. 4A;

[0070] FIG. 4C is a side projection of the coolant flow through the coolant chamber;

[0071] FIG. 4B is an end projection of the coolant flow through the coolant chamber;

[0072] FIG. 5 A illustrates an embodiment with sine-shaped fins in top view;

[0073] FIG. 5B illustrates a perspective close-up view of a section of the FIG. 5 A;

[0074] FIG. 5C illustrates parameters of the fins;

[0075] FIG. 6 illustrates two set of fins that are rotated relatively to each other;

[0076] FIG. 7 illustrates two set of fins with different parameters;

[0077] FIG. 8 is a graph with different flow calculations;

[0078] FIG. 9 is an example of a fin structure;

[0079] FIG. 10A illustrates an array of coolant modules in perspective view;

[0080] FIG. 10B illustrates the array of FIG. 6 A in an exploded view.

[0081] DETAILED DESCRIPTION / PREFERRED EMBODIMENT

[0082] Figure 1 A is a perspective view of a cooling device 1 for cooling electronic components 3 on at least one of its outer surfaces, optionally both surfaces. The cooling device 1 has a sandwich structure of a first coolant chamber wall 2A and a second coolant chamber wall 2B, sandwiching a coolant chamber 10, which is further delimited by side walls 4 A, 4B.

[0083] Important is that the first coolant chamber wall 2A that is used for cooling of the electronics 3 is thermally conductive in order for the first coolant chamber wall 2A to take up thermal energy from the electronics 3 on the outer side of the first coolant chamber wall 2 A and transfer the heat to the coolant flowing in the coolant volume 10 along the inner side of the first coolant chamber wall 2A. If there are electronics 3 provided on the second coolant chamber wall 2B, this should be thermally conductive as well.

[0084] FIG. IB shows an enlarged view of the first coolant chamber wall 2A from that side that faces the coolant chamber 10, which is opposite to the side on which the electronics 3 are mounted. A first flow structure 7A is provided on the first coolant chamber wall 2A as part of a flow field that is directing the flow of coolant through the coolant chamber 10. The first flow structure 7A comprises multiple identical undulating first fins 13A with identical flow compartment 14 in between the undulating first fins 13A. The first fins 13 A are arranged parallel and equidistant with a distance D indicated by arrow 28. The undulations are periodic with a constant wavelength L, as indicated by the arrow 29. An arrow 5 indicates the average flow direction. It is observed that the undulating first fins 13A and, correspondingly, the first flow compartments 14 are arranged perpendicular to the flow directions 5. In more detail, the undulating first fins 13A and the resulting undulating compartments 14 have average longitudinal direction along a line 19 that is perpendicular to the average flow path 5 of the coolant.

[0085] FIG. 2A, FIG. 2B and FIG. 2C illustrates a first embodiment of a flow field in the coolant chamber 10. The first flow structure 7A on the inner side of the first coolant chamber wall 2 A is as illustrated in FIG. IB.

[0086] Between the second coolant chamber wall 2B and the first flow structure 7A, there is provided a second flow structure 7B, which comprises a plurality of straight, parallel second fins 13B. Similar to the equidistant undulating first fins 13A and the flow compartment 14 in between the undulating first fins 13A, also the straight, parallel second fins 13B are arranged equidistant with the same distance 28 and perpendicular to the flow direction 5, indicated by an arrow 5.

[0087] As best seen in FIG. 2A, each undulating first fin 13 A is undulating symmetrically to opposite sides of the corresponding straight, parallel second fin 13B. As best seen in FIG. 2B, each one of the second fins 13B is tightly abutting or attached to or integral with the corresponding first fin 13 A.

[0088] Accordingly, each flow compartment 14 is delimited by two neighboring undulating first fins 13 A and that portion of the first coolant chamber wall 2A that is in between these two neighboring undulating first fins 13 A. Further delimitation is provided by two neighboring straight, parallel second fins 13B and that portion of the second coolant chamber wall 2B that is in between these two neighboring straight, parallel second fins The perspective overview image in FIG. 2B illustrates the undulating fins 13 A that extend towards a middle region 6 of the coolant chamber 10.

[0089] The first fins 13 A and optionally also the second fins 13B are made of a thermally conducting material and in thermally conductive connection with the corresponding coolant chamber wall 2A, 2B that is cooling electronics.

[0090] For example, the first flow structure 7A is integral with the first coolant chamber wall 2A or attached to it, for example glued, welded or brazed to the first coolant chamber wall 2A. For example, the second flow structure 7B is integral with the first coolant chamber wall 2A or attached to it, for example glued, welded or brazed to the second coolant chamber 2B. Optionally, if the first flow structure 7A is attached to or integral with the first coolant chamber wall 2A and the second flow structure 7B is attached to or integral with the second coolant chamber wall 2B, the first flow structure 7A is tightly abutting but not necessarily fastened to the second flow structure 7B. Such embodiments are useful if both the first and the second coolant chamber wall 2A, 2B carry electronics to be cooled.

[0091] A possible alternative is in the first flow structure 7A and the second flow structure 7B being attached to each other or integral with each other and being attached to or integral with the first coolant chamber wall 2A but not necessarily the second coolant chamber wall 2B, if only the first coolant chamber wall carries electronics 3 that are to be cooled. Optionally, in the latter case, the second flow structure 7B is tightly abutting the second coolant chamber wall 2B but not necessarily attached to it.

[0092] The term “attached to” refers to the two structures being provided separately and then joined, for example by gluing, welding or brazing. The term “integral with” refers to the corresponding structures being made out of a single piece, for example by milling or casting or sintering, optionally using heat-conductive polymers or ceramics. A further possible production method that can be used for producing the flow structures 7A, 7B as integral with the corresponding coolant chamber walls 2A, 2B, is impact extrusion, also called forging, in which a stamp with a template matrix by high pressure impact deforms a metal block into the desired shape. In the illustrated embodiment in FIG. 2, the first flow structure 7A is integral with the first coolant chamber wall 2A, as the undulating first fins 13 A and the first coolant chamber wall 2A are made of a single piece of material, and the second flow structure 7B is integral with the second coolant chamber wall 2B, as the straight second fins 13B and the second coolant chamber wall 2B are made of a single piece of material.

[0093] With reference to FIG. 2A, the undulating portions of the first fins 13 A on opposite sides of the second fin 13B form first canals 15 and second canals 16 which connect neighboring compartment 14. As will become apparent from the explanation in connection with FIG. 2C, these canals 15, 16 provide flow from one compartment to its subsequent compartment 14 in opposite directions, one direction, which is shows as upwards in FIG. 2C, towards the first coolant chamber wall 2A and the opposite direction, which is shows as downwards in FIG. 2C, towards the second coolant chamber wall 2B. This change in direction of the flow is important, as it creates turbulence in the coolant so that the temperature of the coolant in a compartment 14 is largely constant throughout the compartment 14 and, thus, optimized for maximum uptake of thermal energy from the first fins 13A and second fins 13B.

[0094] The first fins 13 A have a first end 23 A remote from the inner side 25 of the first coolant chamber wall 2A and extend a distance 24A from the inner side 25 A of the first coolant chamber wall 2A into the coolant chamber 10. The second fins 13B have a second end 23B remote from the inner side of the second coolant chamber wall 2A and extend a distance 24B from the inner side of the first coolant chamber wall 2A into the coolant chamber 10. The first end 23 A and the second end 23B meet and connect to form a liquid tight connection.

[0095] For example, the distances 24A and 24B are equal. Alternatively, the distances 24A and 24B are different but, typically, do not differ by more than 20% of the width of the coolant chamber, which is identical to the interdistance 26 between the first and the second coolant chamber walls 2 A, 2B.

[0096] As illustrated in FIG. 2C, each first canals 15 is formed by first portions 27A of the corresponding first fins 13A and a first portion 27B of corresponding second fin (13B), the first portion being a portion of the edge 23B of the second fin 13B. Correspondingly, each second canals 16 is formed by a second portion of the corresponding first fins 13 A and a second portion of corresponding second fin 13B. As seen from the drawing, the second portions for the two canals 15, 16 are different from the first portions, as the canals 15, 16 are located differently. In other words, only the combination of the first fins 13 A and the second fins 13B creates the first and second canals 15, 16.

[0097] FIG. 2C, which is an enlarged section of the perspective cross sectional image of FIG. 2B, illustrates a flow pattern by arrows 15 A, 15B, 16A, 16B, 17A. In the inlet compartment 11, liquid coolant flows towards the first and second flow structures 7A, 7B. As the straight second fin 13B obstructs a straight flow of the coolant, the coolant is forced into a first canal 15, as indicated by arrow 15 A. The first canal 15 is also illustrated in FIG 2A. Each of the first canals 15 forces the coolant to change direction towards the first coolant chamber wall 2A, which is in an upwards direction in FIG. 2C, in order for the coolant to reach the subsequent compartment 14. Once, the coolant has passed the first canal 15, it continues it to flow towards the first coolant chamber wall 2A due to its speed, as indicated by arrow 15B. After impinging onto that portion 22 A of the first coolant chamber wall 2A that delimits the compartment 14, the coolant is recoiled towards the second coolant chamber wall 2B, as also indicated by arrow 15B in FIG. 2C.

[0098] On the other hand, as the undulating first fin 13B also obstructs a straight flow of the coolant, the coolant from the inlet compartment 11 is forced into the second canal 16, as indicated by arrow 16A. The second canal 16 is also illustrated in FIG 2A. Each of the second canals 16 forces the coolant to change direction towards the second coolant chamber wall 2B, which is in a downwards direction in FIG. 2C, in order for the coolant to reach the subsequent compartment 14. Once, the coolant has passed the second canal 16, it continues to flow towards the second coolant chamber wall 2B due to its speed, as indicated by arrow 16B. After impinging onto that portion 22B of the second coolant chamber wall 2B that delimits the compartment 14, the coolant is recoiled towards the first coolant chamber wall 2A, as also indicated by arrow 16B in FIG. 2C.

[0099] The coolant in the compartment 14 before and after recoil on the respective portions 22A, 22B of the coolant chamber walls 2A, 2B undergoes a heavy mixing due to the turbulence created by the coolant flowing into the compartment 14 in opposite directions through the first and second canals 15, 16. After mixing, the coolant leaves the compartment through corresponding first and second canals 15, 16 to likewise enter the subsequent compartment, as indicated by arrows 16B and 17A.

[0100] FIG. 3A, 3B, and 3C illustrate an alternative embodiment in which the straight second fins 13B of FIG. 2 have been substituted with undulating second fins 13B. The overall effect is similar as in FIG. 2. However, the first and second canals 15, 16 have a larger cross section and, accordingly, reduced flow resistance and reduced pressure drop. Also in this embodiment, the first fins 13 A have first and second canals 15, 16 on opposite sides of the second fins 13B. Due to the undulating shape of the second fins 13B, each undulating first fin 13 A is undulating symmetrically to opposite sides of the corresponding second fin 13B and vice versa.

[0101] For this structure of FIG. 3, the flow through the corresponding flow field is illustrated in the overview image of FIG. 4 A and the enlarged section of FIG. 4B. It illustrates the discussion above of the two-directional flow from one compartment 14 to the next, the arrow 5 indicating the average flow direction. FIG. 4D illustrates a side-projection, resembling an alternating motion of the coolant, the arrow 5 indicating the average flow direction. Supported by the front-projection in FIG. 4D of the flow field, it appears the flow resembles not only a forward alternating motion as per FIG. 4C but also a sideways motion approximately resembling a circle, the combination of which resembles helical flow paths.

[0102] As alternatives to the shown embodiments, the undulating fins 13 A, 13B may have different shapes for example a zigzag-shaped structure with sharp edges or a smoothly undulating structure, such as a sine-shaped structure, for example as illustrated in FIG. 5A in a top view and in FIG. 5B in a perspective view of an enlarged portion thereof. The flow speed of the coolant through the structure is dependent on various parameters, some of which are indicated in FIG. 5C, such as wavelength L of the undulating fin, amplitude A of the undulating fin, distance D from one fin to the neighboring fin in the array of fins 13 A as measured in the same direction as measuring the amplitude A, as well as the wall thickness T of the fin, as the latter determines the accessible channel width W through which the coolant can flow. As illustrated in FIG. 5B, the channel width W for the undulating fins 13 A is defined as the lateral distance between the straight portions of the walls of the fins 13 A. Notice that the amplitude A in FIG. 5C is illustrated as a peak-to-peak amplitude from the center of one first fin 13 A to the center of the neighboring first fin 13 A.

[0103] As an example, a useful wall thickness is in the range of 0.3-2 mm, rather 0.6-1.6 mm.

[0104] As shown in the above discussed drawings, the first fins 13 A and the second fins 13B meet and are in contact with each other along their ends 23 A, 23B. In order to make sure that the first fins 13 A and the second fins 13B actually meet each other on a contact area when assembled, while preventing overload on the contact area due to manufacturing tolerances where the sum of the length of the fins 13 A, 13B slightly exceed the wall interdistance 26, the second fins 13B are optionally made of a resilient material that can be compressed. For this purpose, in more detail, the sum of the first and second distance 24A, 24B is more than 100% of the coolant chamber wall interdistance 26 when in a state prior to assembly and equal to 100% in assembled state due to compression of the resilient second fins 13B.

[0105] As an alternative for preventing overload of the fins 13 A, 13B during assembly, it is also possible to let the ends 23 A, 23B of the first and second fins 13 A, 13B face each with a spacing between the ends 23 A, 23B of the first and second fins 13 A, 13B and without the first fins 13 A coming in contact with the second fins 13B. Such gap between the first and second fins 13 A, 13B is typically small, for example in the range of 0.05- 3 mm or rather 0.1-1 mm, as the gap should not allow the coolant to pass through the coolant chamber 10 without being forced against the coolant chamber walls 2A, 2B, especially the first coolant chamber wall 2A, with a turbulent flow. In particular, the gap should be no more than 15%, rather no more than 10%, of the coolant chamber wall interdistance 26.

[0106] As explained above, the first and second fins 13A, 13B and the compartments 14 have an average longitudinal fin direction 19 and corresponding compartment direction that is perpendicular to the flow path 5. However, as illustrated in FIG. 6, the average fin direction 19 for the first fins 13a or the second fins 13B or both may deviate slightly from the exact perpendicular direction relatively to the average flow direction 5, for example deviating by an angle in the range up to 10° from perpendicular. In alternative embodiments, the deviation from perpendicular is in the range of 0°- 20°, 0°- 30°, 10- 20°, 10°- 30° or 20°-30°. For example, the fins have an angle in the range of 70°-l 10°, rather in the range of 80°-100°, for example in the range of 85°-95°, to the average flow path 5. As an example, the first and second fins 13 A, 13B extends from the first to the second coolant chamber side wall 4A, 4B and are oriented within the range of 70°-l 10°, for optionally in the range of 80°-100°, such as in the range of 85°- 95°, relatively to the average flow direction 5. In all of these embodiment, the coolant crosses all first and second fins 13 A, 13B during flow of the coolant through the coolant chamber 10. In the example of FIG. 6, the geometries of the first fins 13A and the second fins 13B are similar.

[0107] However, identical geometries need not be the case, as already illustrated in FIG. 2A. Further options for geometries involve first fins 13 A and second fins 13B having different wavelength L, different amplitude A, different spacing D and / or different wall thickness T. An example is illustrated in FIG. 7.

[0108] If these parameters are varied, experimental values and / or flow model calculations, which are well known in the technical field and usually used for dimensioning heat exchangers, may reveal the usefulness for specific applications and help identify the optimum combination of dimensions.

[0109] For example, in some automobile industry, it is desired that the pressure for the cooling devices are within predetermined levels, so that a pressure drop dP through the cooling device is not higher than a predetermined value, optionally 100 mbar. On the other hand, the thermal resistance should be minimized. This is a general challenge and requires some iterations for the designer.

[0110] For example, the pressure drop should be no more than 100 mbar at a flow of 8 liter / mi- nute through the coolant chamber.

[0111] FIG. 8 illustrates some results that have been obtained by varying the various parameters of wavelength L, amplitude A, wall thickness T, distance D between fins, and canal width W. The numbering in the drawing is not of importance and serves for the present purpose only for distinguishing the points. The abscissa is pressure drop dP in mbar (1 mb = 100 Pa), and the ordinate is thermal resistance Rth in units K / W. Variations of parameters were in the ranges of 4-14 mm for the wavelength L, 1-3 mm for the amplitude A, and 1.5-3 mm for the channel widths W.

[0112] The point 1 in FIG. 8 was calculated for a pressure drop of 100 mbar, which was mentioned above as a desired feature in automobile industry. This was achieved with a design of coolant chamber 10 in which the wavelength, Ll=12 mm of the first fins 13A was identical to the wavelength L2=12 mm of the second fins 13B, the peak-to-peak amplitude Al=4.50 mm of the first fins 13A was identical to the peak-to-peak t amplitude A2=4.50 mm of the second fins 13B, and the channel width Wl=1.6 mm of the first fins 13 A was identical to the channel width W2=1.6 mm of the second fins 13B. The design was following overall dimensions desired for cooling devices for electronic components in electrical automobiles.

[0113] FIG. 9 is illustrating the fin structure that was used for the calculation of point 1 in FIG. 8.

[0114] In FIG. 8, it is further observed that many of the calculated designs have a higher thermal resistance, some of which up to 15-20% higher at the same pressure drop of 100 mbar. Although, this may not seem dramatic at first sight, it must be pointed out that a 20% higher thermal resistance implies a reduction in cooling efficacy in the same order. On the other hand, reducing the pressure drop dP may increase the flow for a certain pumping pressure, which can be beneficial, however, the lower pressure drop dP, which implies a higher flow through the cooling chamber 10 for a fixed pumping pressure, comes with a price of higher thermal resistance, see for example points 100, 90, 36 and 97. On the other hand, experiments revealed that a lower thermal resistance can be obtained, see in particular points 35, 57, 77 in FIG. 8, if a higher pressure drop can be accepted. Accordingly, as already mentioned above, the parameters have to be balanced according to the actual needs.

[0115] The points in FIG. 8 represent the results of a Design of Experiments, DoE, where the relevant geometric parameters are varied in order to achieve the best coverage of the design space. Modern simulation tools are then applied to get a “reduced order model”, which is an analytical expression, that can predict the thermal resistance and pressure drop for any combination of input parameters. This methodology can be further applied to explore the so-called Pareto Frontier that represents the optimum trade-off between the thermal resistance and pressure drop (indicated by the blue line in FIG. 8 that connects the best designs of the DoE).

[0116] FIG. 10A in perspective view and FIG. 10B in exploded view illustrate a cooling device 100 with an array of cooling modules 101 mounted inside a manifold housing 102. Each of the cooling modules 101 is to a large extent similar to the cooling device 1 of FIG. 1. It comprises a first coolant chamber wall 2A, similar to the first coolant chamber wall 2A in FIG. 1 but does not comprise a different second coolant chamber wall 2B, which in this embodiment instead is substituted part of the manifold housing 102. The first coolant chamber wall 2 A, similar to the first coolant chamber wall 2 A in FIG. 1, comprises a first flow structure 7A adjacent to the first coolant chamber wall 2A, for example attached to or integral with the first coolant chamber wall 2A. However, the second flow structure 7B, which is adjacent the opposite side of the separation wall 5, relatively to the first flow structure 7A, is not attached to any second coolant chamber wall, as this is absent in the module 101. The second flow structure 7B is provided inside the housing 102, for example integral with the housing 102. A gasket 105 seals between the first coolant chamber wall 2A and the housing 102. From the inlet 103, coolant flows into the various coolant chambers and long the flow fields defined by the flow structures 7 A, 7B and leaving the manifold 102 through coolant outlet 104.

Claims

CLAIMS1. A cooling device (1, 100) for cooling electronic components (3) that are in thermal contact with an outer side of a thermally conducting first coolant chamber wall (2A); wherein the cooling device (1, 100) comprises a coolant chamber (10) delimited by an inner side (25 A) of the first coolant chamber wall (2A) and an inner side of an opposite second coolant chamber wall (2B) and a first and second coolant chamber side wall (4A, 4B), wherein there is provided an average flow direction (5) for coolant through the coolant chamber (10) from a coolant inlet to a coolant outlet along the inner sides (25A, 25B) of the first and second coolant chamber walls (2A, 2B) and the first and second coolant chamber side walls (4A, 4B) for cooling the first coolant chamber wall (2A), wherein the inner side of the first coolant chamber walls (2A) and the inner side of the second coolant chamber wall (2B) are spaced by a coolant chamber wall interdistance (26); wherein the cooling device (1) comprises a first array (7 A) of multiple, side-by- side placed, thermally conducting first fins (13 A), each of which is connected to the inner side (25 A) of the first coolant chamber wall (2A) by a thermally conductive and sealing connection and has a first end (23 A) that extends a first distance (24A) from the inner side (25 A) of the first coolant chamber wall (2A) into the coolant chamber (10) towards the second coolant chamber wall (2B), and wherein the cooling device (1) comprises a second array (7B) of multiple side-by-side placed second fins (13B), each of which is sealingly connected to the inner side (25B) of the second coolant chamber wall (2B) and has a second end (23B) that extends a second distance (24B) from the inner side (25B) of the second coolant chamber wall (2B) into the coolant chamber (10) towards the first coolant chamber wall (2A); wherein the first distance (24A) of each the first fins (13 A), when measured in a perpendicular direction from the inner side (25 A) of the first coolant chamber wall (2A), and the second distance (24B) of each of the second fins (13B), when measured in a perpendicular direction from the inner side (25B) of the second coolant chamber wall (2B), are at least 20% of the coolant chamber wall interdistance (26); wherein the first end (23 A) of each of the first fins (13 A) meets the second end (23B) of at least one of the second fins (13B) and the second end (23B) of each of the second fins (13B) meets the first end (23A) of at least one of the first fins (13A), orwherein the first end (23A) of each of the first fins (13A) face the second end (23B) of at least one of the second fins (13B) and the second end (23 A) of each of the second fins (13A) face the first end (23B) of at least one of the first fins (13B) with a gap in between of no more than 15% of the coolant chamber wall interdistance; wherein the first fins (13 A) or the second fins (13B) or both have an undulating shape; wherein each of the first and second fins (13A, 13B) extends from the first to the second coolant chamber side wall (4A, 4B) and is oriented within the range of 70- 110 degrees relatively to the average flow direction (5) in order for the coolant to cross all first and second fins (13A, 13B) during flow of the coolant through the coolant chamber (10).

2. The cooling device according to claim 1, wherein both the first fins (13 A) and the second fins (13B) have an undulating shape3. The cooling device according to claim 2, wherein the undulating shape of the first fins (13 A) has a first undulation wavelength (L, 29), and the undulating shape of the second fins (13B) has a second undulation wavelength, and wherein the first undulation wavelength (L, 29) is different from the second undulation wavelength.

4. The cooling device according to any preceding claim, wherein the first fins (13 A) are mutually spaced equidistant (D, 28) or wherein the second fins (13B) are mutually spaced equidistant, or both.

5. The cooling device according to claim 4, wherein the first fins (13 A) are spaced equidistant with a first distance (D, 28) between neighboring first fins (13 A) and the second fins (13B) are spaced equidistant with a second distance between neighboring second fins (13B), wherein the first distance (D, 28) is different from the second distance.

6. The cooling device according to anyone of the claims 2-5, wherein the first fins (13 A) have an undulating shape with a first undulation wavelength (L, 29) and are spaced with a first distance (D, 28) between neighboring first fins (13 A), wherein the first undulation wavelength (L, 29) is larger than the first distance (D, 28); or wherein the second fins (13B) have an undulating shape with a second undulation wavelength and are spacedwith a second distance between neighboring second fins (13B), wherein the second undulation wavelength is larger than the second distance; or both.

7. The cooling device according to any preceding claim, wherein the first end (23 A) of each of the first fins (13A) meets the second end (23B) of at least one of the second fins (13B), and wherein the second end (23B) of each of the second fins (13B) meets the first end (23A) of at least one of the first fins (13A).

8. The cooling device according to claim 7, wherein the second fins (13B) are resilient for compression, and wherein the sum of the first and second distance (24A, 24B) is more than 100% of the coolant chamber wall interdistance (26) when in a state prior to assembly and equal to 100% in assembled state due to compression of the resilient second fins (13B) by assembly.

9. The cooling device according to any preceding claim, wherein the first and second coolant chamber walls (2A, 2B) are parallel, wherein the first and second fins (13 A, 13B) extend perpendicular from the coolant chamber walls (2A, 2B), and wherein the first and second ends (23 A, 23B) face each other along a plane (30) perpendicular to the first and second coolant chamber wall (2A, 2B).

10. The cooling device according to claim 9, wherein the second fins (13B) are identical to the first fins (13A) but rotated 180 degrees about a line perpendicular through the first coolant chamber wall (2A) so as to provide the second fins (13B) as mirrored relatively to the first fins (13A) and relatively to a plane perpendicular to the first coolant chamber wall (2A).

11. The cooling device according to any preceding claim, wherein the first fins (13 A) and the second fins (13B) in pairwise combinations form an array of compartment walls (20) each pairwise combination (13A, 13B) separating two adjacent of multiple compartments (14), wherein each compartment (10) is delimited by the first and second coolant chamber wall (2A, 2B), the first and second coolant chamber side wall (4A, 4B) and two pairwise combinations (13A, 13B).

12. The cooling device according to claim 11, wherein each pairwise combination (13 A, 13B) forms multiple first and second canals (15, 16) extending through the respective compartment wall (20), wherein each first canals (15) is formed by a first undulating portion (27 A) of the first fin (13) and a first portion (27B) of the second fin (13B) and each second canals (16) is formed by second undulating portions of the first fin (13A) and a second portion of the second fin (13B), the second portions being different from the first portions (27 A, 27B); wherein the first and second canals (15, 16) are arranged altematingly along the compartment wall (20) with one of the first canals (15) between two of the second canals (16) and one of the second canals (16) between two of the first canals (15), wherein each first canal (15) has a first coolant flow direction (15 A) and each second canal (16) has a second coolant flow direction (16A) from one compartment (11) through the compartment wall (20) into a subsequent compartment (14) along the average flow direction (5), wherein the first flow directions (15A) is towards the first coolant chamber wall (2A) but not towards the second coolant chamber wall (2B) and the second flow directions (16A) is towards the second coolant chamber wall (2A) but not the first coolant chamber wall (2A).

13. The cooling device according to claim 12, wherein each of the first fins (13) has an undulating shape about a line (19) parallel with the first coolant chamber wall (2 A) and each of the first fins (13) comprises a first set of bends (21A) on a first side of the line (19) and a second set of bends (2 IB) on a second, opposite side of the line (19), wherein the first and second bends (21A, 21B), respectively, are the first portions (27A) and second portions of the first fin (13 A), which in combination with the corresponding second fin (13B) form the first and second canals (15, 16), respectively; wherein the line (19) is perpendicular to the average flow direction (5) or is inclined and has an angle in the range of 70-110 degrees relatively to the average flow direction (5).

14. The cooling device according to any preceding claim, wherein each of the first fins (13A) is facing or meeting only one of the second fins (13B).

15. The cooling device according to any preceding claim, wherein the first distance (24A) is identical for all first fins (13A) and constant along the first fins (13A) and wherein the second distance (24B) is identical for all second fins (13B) and constant along the second fins (13B).

16. The cooling device according to any preceding claim, wherein first fins (13 A) and the first coolant chamber wall (2A) is a single forged metal block.

17. The cooling device according to any preceding claim, wherein first fins (13 A) and the second fins (13B) are non-perf orated.

18. Use of a cooling device according to anyone of the preceding claims in an electrical vehicle for cooling electronic components (3) used for power regulation of electrical propulsion motors.

Images