Cooling device configured to cool an electronic module

Abstract

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 comprising: - an enclosure (10) that is configured to receive the electronic board (4) and the electronic components (5) and is to be filled with a dielectric fluid intended to immerse the electronic components, the enclosure (10) comprising in particular at least one member for retaining the electronic board, - a cover (14) that is configured to close the enclosure and includes at least one rib for forming, in the enclosure, a channel for circulating dielectric fluid (17), the channel having at least one section (21) in which heat transfer is greater than outside said section and which is configured to locally cool the electronic module.

Description

DESCRIPTION TITLE: COOLING DEVICE CONFIGURED TO COOL AN ELECTRONIC MODULE [1] The present invention relates in particular to a cooling device configured to cool an electronic module. [2] It is known, in the context of cooling a power electronic card, such as that used in a DCDC converter (this converter being intended to transform a voltage of a direct current from a first voltage value to a second voltage value), to use a cooling liquid circulating in a plate which is in contact with the electronic card. Such a system involves a significant fluid flow rate and is energy-intensive. In addition, the architecture of the electronic card can complicate access, in terms of cooling, to the hottest components. [3] The present invention aims in particular to further improve the thermal regulation, in particular the cooling, of an electronic module. [4] The invention thus relates to a cooling device configured to cool an electronic module comprising an electronic card on which a plurality of electronic components are mounted, the cooling device comprising: - an enclosure configured to receive the electronic card and the electronic components, and to be filled with a dielectric fluid intended to immerse the electronic components, the enclosure comprising in particular at least one member for holding the electronic card, a cover configured to close the enclosure and comprising at least one rib to form, in the enclosure, a dielectric fluid circulation channel with at least one section with higher heat transfer than outside this section, configured to locally cool the electronic module. [5] In the invention, the components are completely immersed, in particular without air or gas resulting from a phase change of dielectric fluid. [6] Thanks to the invention, the cooling of the electronic components is done by direct contact with the dielectric cooling fluid. This is advantageous compared to state-of-the-art systems which have thermal interfaces, for example formed by plates. [7] According to the invention, the higher heat transfer section is configured to allow a higher heat exchange coefficient between the dielectric fluid and some of the electronic components. This heat exchange coefficient is notably chosen better along this higher heat transfer section compared to other dielectric fluid areas in the enclosure. It should be noted that this higher heat transfer section is specifically designed to improve the heat transfer coefficient in several possible ways, as will be seen below. [8] The invention thus allows differentiated cooling on the different electronic components of the electronic module. The cooling capacity is higher on the components which need more cooling (even if this means generating more local pressure losses) while the cooling capacity on the other components can be provided to be lower. The invention thus allows a good compromise between the cooling of components (for example transistors) which give off a lot of heat and the maintenance of pressure losses at an acceptable level by not excessively forcing the cooling capacity where it is not necessary. [9] 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 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 section (or hydraulic section) which is smaller than a passage section of the channel outside this higher heat transfer section.

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

[0014] It should be noted that the higher heat transfer section does not necessarily have the smallest flow area, or width, across the entire flow 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 smallest possible passage section, or width, of the channel ensures that the dielectric fluid passes through this section with a sufficient flow speed to have 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 for increasing the heat exchange coefficient, and sections with lower heat transfer, in particular alternately.

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

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

[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 II defining a serpentine flow. Alternatively, the circulation channel may 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 comprises an upper edge resting on the cover and a lower edge resting on a bottom of the enclosure, the rib comprising a flexible strip on its upper edge and / or its lower edge configured to ensure sealing of the junction of the wall with the cover 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 in line with the electronic components which heat up the most so as to reduce the hydraulic diameter and therefore improve the heat transfer coefficient.

[0028] Outside of 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 comprises means for disturbing the fluid, in particular disruptors, also called "Dimples" in English, configured to generate turbulence in the fluid flow.

[0030] This makes it possible to increase the heat transfer coefficient.

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

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

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

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

[0035] According to one aspect of the invention, the disruptors may 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 may 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 positioned 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 remainder 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] This makes it possible to avoid unwanted electrical contact between electronic components.

[0041] These unwanted electrical contacts can actually 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 bear on the electronic components to be cooled, potentially with compression of the fins, in particular compression of less than 5% of the height of the fin.

[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 the thermal contact between them. It is also possible to envisage the fins being soldered onto the electronic component to be cooled.

[0044] According to one aspect of the invention, the cooling fins are part of an insert on the cover. The cooling fins can have different shapes. These fins can be, for example, straight and parallel to each other, or they can be wavy and parallel to each other. These fins can also form slots offset from one row to another.

[0045] According to one aspect of the invention, the cover comprises 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 may be used between the heat sink and the cover to prevent 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 a 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 to allow thermal contact between the heat sink and the electronic components without having to subject the electronic components to a compressive force that could 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 may comprise, on one portion, disruptors and, on another portion, cooling fins or a heat sink. It is possible to envisage different combinations

[0051] According to one aspect of the invention, the cover is electrically insulated from the electronic card and the electronic components on this card.

[0052] According to one aspect of the invention, the cover is configured to seal the enclosure.

[0053] According to one aspect of the invention, the cover 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 size 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 walls of the cover.

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

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

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

[0060] According to one aspect of the invention, the cover is made of a plastic material, in particular a polymer. The cover may also be made of a composite material with a polymer matrix and a mineral or vegetable filler.

[0061] Alternatively, the cover is made of metal such as aluminum.

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

[0063] The invention also 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 zones to be cooled in a preferred manner comprise 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 a motor vehicle.

[0066] The invention thus makes it possible to cool in a preferential manner the areas which tend to heat up the most, in particular areas on the electronic card 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 card by increasing the flow rate and the heat exchange coefficient of the dielectric fluid circulating in these areas.

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

[0070] According to one aspect of the invention, the enclosure comprises a member for holding the electronic card, this holding member being for example a hollow column, for example threaded, allowing the card to be fixed there, for example using a screw.

[0071] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and several examples of embodiment given for informational and non-limiting purposes with reference to the appended schematic drawings on the other hand, in which:

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

[0073] [Fig. 2] Figure 2 is a side view of the system of Figure 1;

[0074] [Fig. 3] Figure 3 is a perspective representation, from below, of the cover of the cooling device illustrated in Figures 1 and 2;

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

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

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

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

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

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

[0081] The features, variants and different embodiments of the invention may be combined with each other in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be conceived comprising only a selection of features described below in isolation from the other features described, 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 exemplary embodiment of the invention, configured to cool the electronic module.

[0083] Electronic module 2 is part of a DCDC converter, particularly for motor vehicles.

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

[0085] Areas 6 should be cooled in a preferential manner 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 surface.

[0086] The cooling device 3 comprises 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 5.

[0087] The enclosure comprises members 11 for holding the electronic card 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 holding members 11 of the electronic card comprise hollow columns, for example threaded, allowing the card to be fixed there, for example using screws.

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

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

[0091] The cover 14, produced by injection molding a plastic material, comprises 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 sinks 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 card 4 and the electronic components 5.

[0092] As illustrated in Figure 3, the cover 14 comprises 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 comprises a stamped plate to form the ribs 20 which define the circulation channel.

[0094] The higher heat transfer sections 21 are configured to locally accelerate the dielectric fluid flowing through each higher heat transfer section 21.

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

[0096] This smallest possible passage section of the channel makes it possible to guarantee that the dielectric fluid passes through this section 21 with a sufficient flow speed 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 example described, the channel 17 has sections with higher heat transfer 21 with means for increasing the heat exchange coefficient, and sections with lower heat transfer 27, alternately. These sections 21 and 27 follow one another, forming a flow in one or more successive U-shapes. Here, each section 21 and 27 extends over 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, due to the fact that 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 comprises a lower edge resting on a bottom of the enclosure or the electronic card, the rib comprising a flexible strip on its lower edge configured to ensure sealing of the junction of the wall with the bottom or the electronic card 4.

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

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

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

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

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

[0107] This makes it possible to increase the heat transfer coefficient.

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

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

[0110] In another exemplary implementation of the invention illustrated in Figure 5, the cover 14 includes 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 remainder of the cover 14. For example, the fins 40 and the cover 14 are made of an electrically insulating material. It is thus possible to avoid unwanted electrical contact with electronic components 5.

[0112] The cooling fins 40 are configured so that, when the cover 14 is mounted on the enclosure 10, the fins 40 bear on 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 height of the fin.

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

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

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

[0116] In another exemplary embodiment not shown, the cover 14 comprises 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 while 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 that could damage them.

[0118] Of course, the higher heat transfer section 21 may comprise a combination of the elements described above, for example may comprise, on one portion, disruptors and, on another portion, cooling fins or a heat sink. It is possible to envisage different combinations

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

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 single 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, the section with higher heat transfer (21) having a lower height than the height of the channel (17) in sections with lower heat transfer.

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, 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).

7. 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.

8. 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.

9. 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.

10. 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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