Cooling device configured to cool an electronic module

Abstract

Title: Cooling Device Configured to Cool an Electronic Module The invention relates to a cooling device (3) configured to cool an electronic module (2) comprising an electronic board (4) on which a plurality of electronic components (5) are mounted. The cooling device comprises: a housing (10) configured to receive the electronic board (4) and the electronic components (5), and to be filled with a dielectric fluid intended to immerse the electronic components. The housing (10) includes, in particular, at least one retaining element for the electronic board; a cover (14) configured to close the housing and having at least one rib to form, within the housing, a channel for the circulation of dielectric fluid (17) with at least one section (21) having a higher heat transfer than outside this section, configured to locally cool the electronic module. Figure for the abstract: Fig. 2

Description

Title of the invention: Cooling device configured to cool an electronic module

[0001] The present invention relates in particular to a cooling device configured to cool an electronic module.

[0002] It is known, in the context of cooling a power electronic board, such as that used in a DC-DC converter (this converter being designed to transform a direct current voltage from a first voltage value to a second voltage value), to employ a coolant circulating in a plate that is in contact with the electronic board. Such a system involves a significant fluid flow rate and is energy-intensive. Moreover, the architecture of the electronic board can complicate access, in terms of cooling, to the hottest components.

[0003] The present invention aims in particular to further improve the thermal regulation, in particular the cooling, of an electronic module.

[0004] The invention thus relates to a cooling device configured to cool an electronic module comprising an electronic board on which a plurality of electronic components are mounted, the cooling device comprising: - an enclosure configured to receive the electronic board and electronic components, and to be filled with a dielectric fluid intended to immerse the electronic components, the enclosure including in particular at least one device for retaining the electronic board, - a cover configured to close the enclosure and having at least one rib to form, in the enclosure, a channel for the circulation of dielectric fluid with at least one section with a higher heat transfer than outside of that section, configured to locally cool the electronic module.

[0005] In the invention, the components are completely immersed, in particular without air or gas resulting from a phase change of dielectric fluid.

[0006] Thanks to the invention, the cooling of electronic components is achieved through direct contact with the dielectric-type cooling fluid. This is advantageous compared to state-of-the-art systems that have thermal interfaces, for example formed by plates.

[0007] According to the invention, the higher heat transfer section is configured to allow a higher heat transfer coefficient between the dielectric fluid and Some of the electronic components. This heat transfer coefficient is specifically chosen to be better along this section with higher heat transfer compared to other dielectric fluid zones within the enclosure. It should be noted that this section with higher heat transfer is specially designed to improve the heat transfer coefficient in several possible ways, as will be seen below.

[0008] The invention thus allows for differentiated cooling of the various electronic components of the electronic module. The cooling capacity is greater on the components that require more cooling (even if this generates higher local pressure drops), while the cooling capacity on the other components can be lower. The invention therefore allows for a good compromise between cooling components (for example, transistors) that generate a lot of heat and maintaining pressure drops at an acceptable level by not excessively increasing the cooling capacity where it is not needed.

[0009] According to one aspect of the invention, the fluid circulation channel is configured to direct dielectric fluid towards electronic components to be cooled.

[0010] According to one aspect of the invention, the circulation channel is formed between two substantially parallel ribs of the cover.

[0011] According to one aspect of the invention, the higher heat transfer section is configured so as to locally accelerate the dielectric fluid flowing in this higher heat transfer section.

[0012] According to one aspect of the invention, the higher heat transfer section has a passage cross-section (or hydraulic cross-section) that is smaller than a passage cross-section of the channel outside of this higher heat transfer section.

[0013] In particular, the higher heat transfer section has a width between two side walls that is smaller than a width of the channel outside this higher heat transfer section.

[0014] It should be noted that the higher heat transfer section does not necessarily have the smallest passage section, or width, over the entire circulation channel.

[0015] This passage section, or the width of the section, is in any case chosen to be as small as possible taking into account the dimensions of the electronic components to be cooled in this section.

[0016] This passage section, or width, as small as possible of the channel makes it possible to guarantee that the dielectric fluid passes through this section with a flow velocity sufficient to have a satisfactory heat transfer.

[0017] According to one aspect of the invention, the higher heat transfer section extends over only a portion of the channel, between a fluid inlet of the channel and a fluid outlet of the channel.

[0018] According to one aspect of the invention, the channel has sections with higher heat transfer with means to increase the heat exchange coefficient, and sections with lower heat transfer, in particular in alternation.

[0019] Apart from the higher heat transfer section, the channel has at least one lower heat transfer section which is, for example, devoid of means to increase the heat transfer coefficient.

[0020] According to one aspect of the invention, the fluid circulation channel has at least two higher heat transfer sections, separated from each other by a lower heat transfer section.

[0021] The fluid entering the channel thus passes successively through sections with higher heat transfer and sections with lower heat transfer.

[0022] According to one aspect of the invention, the circulation channel forms a U or, alternatively, a succession of U's defining a serpentine flow. Alternatively, the circulation channel can be configured to allow a spiral flow.

[0023] According to one aspect of the invention, the rib which delimits sections of the channel is configured to be permeable to the fluid which can thus pass through this rib, for example because this rib does not extend over the entire height of the channel.

[0024] Alternatively, the rib that delimits the dielectric fluid circulation channel forms a sealed wall, preventing fluid from passing through the wall from one face to the other.

[0025] For example, the rib has an upper edge bearing on the lid and a lower edge bearing on a bottom of the enclosure, the rib having a flexible band on its upper edge and / or its lower edge configured to ensure a seal of the junction of the wall with the lid and / or the bottom with respect to the fluid.

[0026] According to one aspect of the invention, the higher heat transfer section has a lower height than the channel height in lower heat transfer sections.

[0027] Thus the section with higher heat transfer has a lower height at the electronic components which heat up the most so as to reduce the hydraulic diameter and therefore improve the heat transfer coefficient.

[0028] Apart from this section with higher heat transfer, the channel has a higher height so as to minimize pressure losses.

[0029] According to one aspect of the invention, the higher heat transfer section includes means for disturbing the fluid, in particular disruptors, also called "Dimples" in English, configured to generate turbulence in the fluid flow.

[0030] It is thus possible to increase the heat transfer coefficient.

[0031] According to one aspect of the invention, the disruptors comprise bosses formed inside the channels.

[0032] According to one aspect of the invention, the disruptors are made by stamping a plate forming the cover.

[0033] Alternatively, the disruptors can be formed by injection or by machining.

[0034] According to one aspect of the invention, the disruptors are on the lateral and / or upper walls of the section.

[0035] According to one aspect of the invention, the disruptors can have different shapes, for example a chevron shape, a circular shape, an oblong shape, a polygonal shape, for example square or rectangle.

[0036] According to one aspect of the invention, the disruptors can have a height in the channel which is between 25% and 40% of the height of the channel.

[0037] According to one aspect of the invention, the cover includes cooling fins placed in the fluid flow in the higher heat transfer section.

[0038] According to one aspect of the invention, electrical insulation is provided between the cooling fins and the rest of the cover.

[0039] According to one aspect of the invention, the fins and / or the cover are made of an electrically insulating material.

[0040] It is thus possible to avoid unwanted electrical contact between electronic components.

[0041] These unwanted electrical contacts can indeed occur when the fins and the cover are made of electrically conductive materials, for example metal.

[0042] According to one aspect of the invention, the cooling fins are configured so that, when the cover is mounted on the enclosure, the fins come into contact with the electronic components to be cooled, potentially with a compression of the fins, in particular a compression of less than 5% of the fin height.

[0043] According to one aspect of the invention, a thermal interface, for example a thermal paste, is provided between the fins and the electronic components so as to improve thermal contact between them. Alternatively, the fins may be brazed onto the electrical component to be cooled.

[0044] According to one aspect of the invention, the cooling fins are part of a component attached to the lid. The cooling fins can have different shapes. For example, these fins can be straight and parallel to each other, or they can be corrugated and parallel to each other. These fins can also form staggered crenellations from one row to the next.

[0045] According to one aspect of the invention, the cover includes at least one heat sink, for example in the form of a metal block, placed in the section with higher heat transfer.

[0046] According to one aspect of the invention, an insulator can be used between the heat sink and the cover in order to prevent any unwanted electrical contact.

[0047] According to one aspect of the invention, the heat sink is configured to be in contact with the electronic components to be cooled.

[0048] According to one aspect of the invention, the heat sink is of the rigid type while the cooling fins described above can be compressed to a certain extent.

[0049] In the case of a heat sink, a flexible thermal interface may be provided allowing thermal contact between the heat sink and the electronic components without having to subject the electronic components to a compressive force likely to damage them.

[0050] According to one aspect of the invention, the higher heat transfer section may comprise a combination of the elements described above; for example, it may comprise, on one portion, inducers and, on another portion, cooling fins or a heat sink. Various combinations are possible.

[0051] According to one aspect of the invention, the cover is electrically isolated from the electronic board and the electronic components on that board.

[0052] According to one aspect of the invention, the lid is configured to close the enclosure in a watertight manner.

[0053] According to one aspect of the invention, the lid comprises a main wall.

[0054] According to one aspect of the invention, the main wall comprises regions which are at different heights from the electronic board when the cover is placed on the enclosure.

[0055] Thus the electronic components on the electronic board which may have different heights, can be integrated as close as possible to the cover thanks to these regions of different heights of the cover, minimizing the bulk and allowing good electrical insulation between its electronic components and the cover.

[0056] According to one aspect of the invention, a space is provided between the electronic components on the electronic board and the walls of the cover.

[0057] According to one aspect of the invention, the cover comprises a plate, in particular stamped to form the rib or ribs which define the circulation channel.

[0058] Alternatively, the lid can be made by injection.

[0059] Alternatively, the cover is made by machining.

[0060] According to one aspect of the invention, the lid is made of a material plastic, specifically a polymer. The lid may also be made of a composite material with a polymer matrix and a mineral or plant-based filler.

[0061] Alternatively, the lid is made of metal such as aluminium.

[0062] According to one aspect of the invention, the lid comprises a main wall surrounded by a raised rim relative to this main wall, so that when the lid is assembled with the enclosure, the main wall is recessed further into the enclosure than the raised rim of the lid. Thus, the main wall of the lid is located as close as possible to the electronic board and electronic components.

[0063] The invention further relates to a system comprising an electronic module and a cooling device as described above, configured to cool the electronic module.

[0064] According to one aspect of the invention, the areas to be cooled in a preferential manner include in particular transistors, in particular of the MOSFET type.

[0065] According to one aspect of the invention, the electronic module is part of a DCDC converter, in particular for motor vehicles.

[0066] The invention thus makes it possible to preferentially cool the areas which tend to heat up the most, in particular areas on the electronic board which group the transistors.

[0067] Such transistors in the case of a DCDC converter can generate more than half of the total heat loss.

[0068] The invention makes it possible to concentrate the cooling power mainly on the hot areas of the electronic board by increasing the flow rate and the heat exchange coefficient of the dielectric fluid circulating in these areas.

[0069] In other areas which require less cooling capacity, it is possible to have a lower fluid flow rate.

[0070] According to one aspect of the invention, the enclosure includes a retaining element for the electronic card, this retaining element being, for example, a hollow column, for example threaded, allowing the card to be fixed to it, for example by means of a screw.

[0071] Other features, details and advantages of the invention will become clearer upon reading the following description on the one hand, and several illustrative and non-limiting examples of embodiments given with reference to the accompanying schematic drawings on the other hand, in which:

[0072] [Fig.1] Fig.1 is a schematic representation of a system according to an example of an embodiment of the invention, with an electronic module in a housing of a cooling device;

[0073] [Fig.2] The [Fig.2] is a profile view of the system of the [Fig.1];

[0074] [Fig.3] Fig.3 is a perspective view from below of the cover of the cooling device illustrated in figures 1 and 2;

[0075] [Fig.4] Fig.4 is a view, from below, of the cover of the cooling device illustrated in figures 1 and 2;

[0076] [Fig. 5] [Fig. 5] is a view, from below, of the cover of a re-device cooling according to another embodiment of the invention;

[0077] [Fig. 6] Fig. 6 is a schematic representation of cooling fins of a cooling device according to an example of an embodiment of the invention;

[0078] [Fig.7] Fig.7 is a schematic representation of cooling fins of a cooling device according to another embodiment of the invention;

[0079] [Fig.8] Fig.8 is a schematic representation of cooling fins of a cooling device according to another embodiment of the invention;

[0080] [Fig.9] Fig.9 is a schematic representation of cooling fins of a cooling device according to another embodiment of the invention.

[0081] The features, variants, and different embodiments of the invention can be combined in various ways, provided they are not incompatible or mutually exclusive. In particular, variants of the invention may be conceived comprising only a selection of features, described hereafter in isolation from the other described features, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0082] Figures 1 and 2 show a system 1 comprising an electronic module 2 and a cooling device 3 according to an example of an embodiment of the invention, configured to cool the electronic module.

[0083] The electronic module 2 is part of a DCDC converter, in particular for motor vehicles.

[0084] The electronic module 2 includes an electronic board 4 on which are mounted a plurality of electronic components 5, including MOSFET type transistors present in areas 6.

[0085] Areas 6 are to be cooled preferentially because MOSFET transistors tend to heat up more than other components. Such transistors in the case of a DCDC converter can generate more than half of the total heat loss for a fraction of the total contact area.

[0086] The cooling device 3 includes a housing 10 configured to receive the electronic board 4 and the electronic components 5, and to be filled with a dielectric fluid intended to immerse the electronic components 5.

[0087] The enclosure includes retaining elements 11 for the electronic board 4. The enclosure 10 is for example a single piece, made of plastic or metal, and is in the form of a tank.

[0088] The retaining elements 11 of the electronic card include hollow columns, for example threaded, allowing the card to be fixed to them, for example using screws.

[0089] The screws pass through holes 12 formed in the card 4.

[0090] The cooling device 3 further includes a cover 14 configured to close the enclosure 10 in a sealed manner.

[0091] The cover 14, made by injection molding of a plastic material, has a main wall 15 surrounded by a raised rim 16 relative to this main wall 15, so that when the cover 14 is assembled with the enclosure 10, the main wall 15 is pushed further into the enclosure 10 than the raised rim 16 of the cover 14. Thus the main wall 15 of the cover is located as close as possible to the electronic board 4 and the electronic components 5.

[0092] As illustrated in [Fig.3], the cover 14 has ribs 20 to form, in the enclosure 10, a circulation channel 17 of dielectric fluid with sections 21 with higher heat transfer than outside this section, configured to locally cool the electronic module 2.

[0093] The cover 14 has a stamped plate to form the ribs 20 which define the circulation channel.

[0094] The higher heat transfer sections 21 are configured so as to locally accelerate the dielectric fluid which flows in each higher heat transfer section 21.

[0095] Each higher heat transfer section 21 has a passage section (or hydraulic section) that is smaller than a passage section of the channel outside of this higher heat transfer section 21.

[0096] This smallest possible passage section of the channel ensures that the dielectric fluid passes through this section 21 with a flow velocity sufficient to have satisfactory heat transfer.

[0097] The higher heat transfer sections 21 extend over only certain portions of the channel 17, between a fluid inlet 25 of the channel and a fluid outlet 26 of the channel.

[0098] In the described example, the channel 17 has alternating sections 21 with higher heat transfer, equipped with means to increase the heat transfer coefficient, and sections 27 with lower heat transfer. These sections 21 and 27 follow one another, forming a flow in a single U or several successive U-shaped sections. Here, each section 21 and 27 extends along a straight branch of the U.

[0099] In the example described, each rib 20 which delimits sections of the channel is configured to be permeable to the fluid which can thus pass through this rib, because this rib does not extend over the entire height of the channel 17, as can be seen in [Fig.2].

[0100] Alternatively, the rib 20 which delimits the dielectric fluid circulation channel forms a sealed wall, preventing fluid from passing through the wall from one face to the other.

[0101] For example, such a rib has a lower edge resting on a bottom of the enclosure or the electronic board, the rib having a flexible band on its lower edge configured to ensure a seal of the junction of the wall with the bottom or the electronic board 4.

[0102] In the example described, each higher heat transfer section 21 has a lower height H1 than the height H2 of the channel in lower heat transfer sections 27, as can be seen in [Fig.2].

[0103] Thus the higher heat transfer section 21 has a lower height H1 at the electronic components 5 which heat up the most so as to reduce the hydraulic diameter and therefore improve the heat transfer coefficient.

[0104] Apart from this higher heat transfer section 21, the channel has a higher height H2 so as to minimize pressure losses and therefore pressure drop.

[0105] The main wall 15 thus includes regions which are at different heights from the electronic board when the cover 14 is placed on the enclosure 10.

[0106] Each higher heat transfer section 21 includes means for disturbing the fluid, including disruptors 30, also called "Dimples" in English, configured to generate turbulence in the fluid flow.

[0107] It is therefore possible to increase the heat transfer coefficient.

[0108] The disruptors 30 have bosses formed inside the channel 17, which are made by stamping a plate forming the cover 14.

[0109] The disruptors 30 can have a height in the channel which is between 25% and 40% of the height of the channel 17.

[0110] In another example of an implementation of the invention illustrated in [Fig.5], the cover 14 has cooling fins 40 placed in the fluid flow in one of the higher heat transfer sections 21.

[0111] Electrical insulation is provided for the cooling fins 40 and the rest of the cover 14. For example, the fins 40 and the cover 14 are made of an electrically insulating material. This prevents unwanted electrical contact with electronic components 4.

[0112] The cooling fins 40 are configured so that, when the cover 14 is mounted on the enclosure 10, the fins 40 come into contact with the electronic components 5 to be cooled, potentially with a small compression of the fins 40, in particular a compression of less than 5% of the fin height.

[0113] A thermal interface, for example thermal paste, is provided between the fins 40 and the electronic components 5 in order to improve contact thermal conductivity between them.

[0114] In the described example, the cooling fins 40 are part of an added component 41 fixed to one of the higher heat transfer sections 21 on the cover 14. In the described example, the higher heat transfer section 21 receives three finned components 41, arranged one after the other in the direction of flow. Each finned component 41 is in thermal contact with two electronic components 5. The finned components 41 are, for example, glued or soldered to the cover 14.

[0115] The cooling fins 40 can have different shapes. These fins can, for example, be straight and parallel to each other ([Fig. 6]), or be corrugated and parallel to each other ([Fig. 7]). These fins 40 can also form staggered slots from one row to the next ([Fig. 8]). The fins 40 can be perforated ([Fig. 9]) instead of being solid.

[0116] In another embodiment not shown, the cover 14 includes at least one heat sink, for example in the form of a metal block, placed in the higher heat transfer section 21, and the heat sink is configured to be in contact with the electronic components 5 to be cooled. This heat sink is of the rigid type, whereas the cooling fins 40 described above can be compressed to a certain extent.

[0117] In the case of a heat sink, a flexible thermal interface, for example a thermal adhesive, may be provided, allowing thermal contact between the heat sink and the electronic components without having to subject the electronic components to a compressive force likely to damage them.

[0118] Of course, the higher heat transfer section 21 may include a combination of the elements described above; for example, it may include, on one portion, disturbances and, on another portion, cooling fins or a heat sink. Various combinations are possible.

[0119] In any event, the cover 14 is electrically isolated from the electronic board 4 and the electronic components 5 on this board.

Claims

Claims

1. Cooling device (3) configured to cool an electronic module (2) comprising an electronic card (4) on which a plurality of electronic components (5) are mounted, the cooling device comprising: - an enclosure (10) configured to receive the electronic card (4) and the electronic components (5), and to be filled with a dielectric fluid intended to immerse the electronic components, the enclosure (10) comprising in particular at least one holding member (11) of the electronic card, - a cover (14) configured to close the enclosure and comprising at least one rib to form, in the enclosure, a dielectric fluid circulation channel (17) with at least one section with higher heat transfer (21) than outside this section, configured to locally cool the electronic module.

2. Cooling device (3) according to the preceding claim, wherein the fluid circulation channel (17) is configured to direct dielectric fluid towards electronic components (5) to be cooled, and this circulation channel (17) is formed between at least two substantially parallel ribs (20) of the cover.

3. Cooling device (3) according to the preceding claim, in which the rib (20) which delimits sections of the channel is configured to be permeable to the fluid which can thus pass through this rib (20), for example because this rib does not extend over the entire height of the channel (17).

4. Cooling device (3) according to one of the preceding claims, wherein the higher heat transfer section (21) has a passage section which is smaller than a passage section of the channel outside this higher heat transfer section.

5. Cooling device (3) according to one of the preceding claims, in which the circulation channel (17) forms a U or a succession of U's defining a serpentine flow.

6. Cooling device (3) according to one of the preceding claims, wherein the higher heat transfer section (21) has a lower height than the height of the channel (17) in lower heat transfer sections.

7. Cooling device (3) according to one of the preceding claims, in which the higher heat transfer section (21) comprises means for disturbing the fluid, in particular disruptors (30), the disruptors being able in particular to have a height in the channel which is between 25% and 40% of the height of the channel (17).

8. A cooling device (3) according to one of the preceding claims, wherein the cover (14) comprises cooling fins (40) placed in the fluid flow in the higher heat transfer section (21), the cooling fins (40) being configured so that, when the cover is mounted on the enclosure, the fins bear on the electronic components to be cooled, potentially with compression of the fins (40), in particular compression of less than 5% of the fin height.

9. Cooling device (3) according to one of the preceding claims, wherein the cover (14) comprises at least one heat sink, for example in the form of a metal block, placed in the section with higher heat transfer.

10. Cooling device (3) according to one of the preceding claims, in which the cover (14) comprises a main wall (15) surrounded by a raised rim (16) relative to this main wall, so that when the cover (14) is assembled with the enclosure, the main wall (15) sinks further into the enclosure than the raised rim of the cover.

11. System (1) comprising an electronic module (2) and a cooling device (3) according to one of the preceding claims, configured to cool the electronic module.

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