FR3082051A1 - COMPUTER MODULE HOUSING FOR MOTOR VEHICLE - Google Patents

Abstract

A computer module housing (11) for a motor vehicle comprises an interior space (12) for housing a printed circuit (14) carrying at least one hot component (20) and a heat dissipation wall (26) having a face external (28) exchange with the ambient medium and an opposite internal face (30). The housing incorporates a steam chamber (30) between the heat dissipation wall (26) and an interior heat sink partition (32) having coupling portions (38) to the hot components of the printed circuit. The steam chamber contains a heat transfer fluid and a capillary structure for recirculating the fluid.

Description

Computer module housing for motor vehicle

Technical area

The present invention generally relates to the automotive field and in particular that of cooling the hot electronic components fitted to the computer modules.

State of the art

Motor vehicles are fitted with an increasing number of systems based on electronic components and the new use of artificial intelligence systems for driving assistance reveals a need for computers offering even greater powers.

Vehicle development now plans to integrate computer modules capable of managing category 5 (or Level 5) autonomous driving, i.e. full autonomous driving for which humans no longer need to intervene, not even to monitor traffic.

The increase in computing power implies the use of more microprocessors, generating a large amount of heat which must be evacuated.

A difficulty in this regard is that the electronic card, carrying the hot components, is housed in a closed and sealed protective box. Indeed, the engine environment is difficult: vibrations, humidity, temperatures experiencing large fluctuations (typically between -40 ° C and 100 ° C).

FR 2 958 794 describes a motor vehicle computer module comprising a box in which a printed circuit is placed on which electronic components are mounted. The computer includes a cover which has recessed areas. These recessed areas are local deformations of the cover, aimed at bringing the cover wall closer to the hot components, a thermal paste being used to thermally couple the components with the cover on the remaining gap. This solution improves heat exchange at the level of hot components, through the housing. On the other hand, the heat exchanges are carried out by passive convection, by ambient air, on the external surfaces of the housing. The thermal diffusion capacity of such a box seems insufficient for the new computer modules mentioned above.

Moving away from the automotive field, active thermal energy dissipation systems are known, by forced convection of air or liquid, supplied at the level of hot components, typically microprocessors, in conventional computer installations. These techniques seem difficult to transpose to the automotive world. In fact, the technical choices for a box to be installed in an engine compartment are limited by the additional constraints inherent in the engine environment and architecture. Solutions using water circulation cooling inside the housing seem difficult to implement, in particular because they require a water circuit separate from that of the engine cooling.

Object of the invention

The object of the present invention is to provide a computer module housing suitable for installation in a motor vehicle which allows increased dissipation of thermal energy, in particular at the level of the hot components of the electronic card.

General description of the invention

The present invention relates to a computer module housing for a motor vehicle defining an interior housing space for a printed circuit carrying at least one hot component. The housing comprises a heat dissipation wall having an external face for exchange with the ambient medium and an opposite internal face.

According to the invention, the housing comprises an interior heat sink partition having a first face, called the drain face, facing the interior housing space and a second opposite face, said inside face. This internal heat sink partition comprises at least one coupling portion intended to be thermally coupled to a hot component of the printed circuit. It will be noted that the housing includes a steam chamber integrated between the heat dissipation wall and the internal heat sink partition, the steam chamber being fluid-tight and having an internal volume delimited at least in part by the internal faces of the walls and partition, the interior volume containing a heat transfer fluid.

The present invention therefore provides a computer housing which integrates a steam chamber produced in a compartment defined by one of the walls of the housing (the heat dissipation wall) and an interior partition mounted in the housing. The steam chamber is designed to operate according to the principle of heat pipes and contains a heat transfer liquid, the phase transition of which is used, and advantageously a capillary structure configured so as to recirculate the condensed fluid towards the coupling portion or portions.

The steam chamber increases the amount of heat evacuated by the housing, allowing the use of larger computing capacities, as required for category 5 autonomous driving computers.

It will also be noted that the steam chamber is defined, for its cold interface, by the external wall known as the heat dissipation wall. So the vapor chamber is really integrated into the housing by design, and it was not added as an insert. This has the advantage that it can be designed in the usual materials of automobile electronic boxes, that is to say aluminum (or alloy). The outer wall is often the wall of the cover, and it is therefore easy to integrate the steam chamber into the cover.

Conventionally, the capillary structure comprises a main portion extending in the steam chamber along, and against, the internal face of the heat dissipation wall. A second portion is provided on the interior face of the interior partition. This capillary assembly ensures the thermal transfer of heat between the fluid and the respective walls and allows the recirculation of the condensed fluid towards the hot wall of the steam chamber, that is to say the internal partition and in particular the coupling portions. This type of capillary structure (called "wick" in English) is well known in the art and can be of any suitable shape, for example grooves in the faces or a metallic foam.

The coupling portions are advantageously pushed towards the interior space. They are therefore typically offset from the general plane of the interior partition, to approach the hot component. The area of each coupling portion is preferably adapted to the area of the corresponding hot component. The space between the hot component and the coupling portion is conventionally filled with a heat transfer material such as a paste or a thermal block, for example.

The housing may include a body closed by a cover, the body having a bottom and side walls. The body can be in one or more pieces. The heat dissipation wall is generally part of the cover, which allows the steam chamber to be integrated into the cover, but it can also be integrated into other walls of the housing.

According to one embodiment, the internal thermal drainage partition is formed in one piece with the side walls. This minimizes the number of parts and is favorable for sealing the system. The cover is then fixed on one side of this assembly, side which will form the steam chamber, while the bottom of the box will be fixed on the other side. This variant is well suited for making aluminum parts: cover, bottom side walls and interior partition.

According to another variant, the interior partition is fixed to the heat dissipation wall, which is itself included in the cover. In this variant, the housing has a conventional configuration, and the interior partition is fixed against the interior wall of the cover to form the envelope of the steam chamber. The housing can therefore be made of aluminum (or alloy) and the interior partition, which is an attached piece, can be made of aluminum or copper (or alloy).

According to the variants, whether the internal partition is integrated into the side walls or fixed to the cover, it can be dimensioned to extend over part or all of the heat dissipation wall, depending on the cooling needs.

Advantageously, the external face (ambient medium side) of the heat dissipation wall carries a heat dissipation structure, for example cooling fins or any other suitable structure. We can even consider adding a water cooling circuit with an exchanger in contact with the external face of the heat dissipation wall. Alternatively, the external face of the heat dissipation wall can be provided to receive a cooling accessory which is just fixed against it, and which then carries for example fins or a water cooling circuit.

According to another aspect, the invention relates to an automotive computer module comprising the present box inside which is placed a printed circuit on which are mounted electronic components called "hot components". The interior drain wall includes a plurality of recessed coupling portions, each being thermally coupled to a respective hot component mounted on the printed circuit, preferably via a pad or thermal paste.

Detailed description using the figures

Other features and characteristics of the invention will emerge from the detailed description of at least one advantageous embodiment presented below, by way of illustration, with reference to the accompanying drawings. These show:

Figure 1: a schematic sectional representation of the present housing according to a first embodiment of the invention; and

Figure 2: a schematic sectional representation of the present housing according to a second embodiment of the invention.

Two embodiments of the invention will be described in detail with reference to the figures, in automotive applications and in particular in computer ECU modules.

In the first embodiment shown in Figure 1, a computer module 10 comprises a housing 11, typically made of aluminum (or aluminum alloy) defining an interior space 12 for housing inside which an electronic card 13 is placed with a printed circuit 14 carrying electronic components, among which one, or more generally several components capable of heating during operation, and therefore called hot components.

The printed circuit 14 can be of any suitable type and the components which it carries depend on the desired functionalities: motherboard, regulation card, control module, etc. The printed circuit 14 is here rectangular in shape (but other shapes are possible) and has an upper face 16 and an opposite lower face 18. The printed circuit 16 can be of the single layer type, but in the case of microprocessor cards will typically be multilayer. Among these components, the hot components are those which, in use, produce a significant amount of thermal energy (heat) such as, for example, microprocessors, or power transistors, certain capacitors, etc. In Figure 1, we see three hot components 20, in particular microprocessors, mounted on the printed circuit board 14 and arranged in the section plane of the figure.

The housing 11 here has a general shape of a rectangular parallelepiped, but other shapes are possible. It breaks down for example into two parts which will be called cover 22 and body 24, so as to distinguish them.

By convention, the cover 22 designates the element of the housing 11 which is arranged on the side of the upper surface 16 of the printed circuit 14, and by body 24 the element arranged on the side of the lower surface 18. In the figure, has simply shown the printed circuit 14 in the interior space 12, but there could be other elements, for example another electronic card which does not include hot components, and the housing typically includes a cable passage and / or connectors, etc.

It will also be noted that the body 24 here has two parts: a bottom 24.1 and a block of four side walls 24.2 (peripherals) extending between the bottom

24.1 and the cover 22. The bottom 24.1 is assembled to the side walls 24.2 in a leaktight manner by all appropriate means (welding, screwing, joints, etc.).

The outer wall 26 of the housing 11 facing the hot components 20 is used for cooling purposes; it is therefore called the heat dissipation wall. The heat dissipation wall 26 thus has an external face 28 for exchange with the ambient medium and an opposite internal face 30. The wall 26 is included in the cover 22.

It will be appreciated that the cooling of the hot components 20 is achieved by means of a steam chamber 31 integrated into the housing 11, and in particular here the cover 22. More particularly, the steam chamber 31 is integrated between the heat dissipation wall 26 and an interior heat sink partition 32. The interior partition 32 has a first face, called the drain face 34, facing the interior housing space 12 and a second face 36, called the inner face. In the variant, the internal partition 32 comprises a plurality of coupling portions 38 allowing thermal coupling with the hot components 20 of the electronic card 13; three coupling portions 38 are visible in Fig.l. The coupling portions 38 are locally deformed zones, said to be depressed, of the internal partition 32 so as to come close to the surface of a hot component 20. The coupling portions project beyond the general plane P of the partition intermediate 32, to the printed circuit. Typically, the interior partition 32 includes a recessed area 38 for each of the hot components 20 of the printed circuit 14.

The invention, in principle, therefore aims to dissipate the heat produced by the hot components 20 through the housing 11, and uses a steam chamber 31 integrated into the cover 22 which improves the cooling of the hot components 20.

The steam chamber 31 is fluid tight and has an interior volume 40 which is mainly delimited by the wall 26 and the interior partition 32 (therefore by the faces 30 and 38). In practice, the interior partition 32 is spaced from the wall 26 and the interior volume 40 is therefore delimited, at the lateral periphery, by the upper part of the side walls 24.2 extending between the interior partition 32 and the wall 26. It will be noted also here that the internal heat sink partition 32 is, in the variant, manufactured in one piece with the side walls 24.2. Thus, the interior partition is linked by its peripheral edge to the side walls 24.1 of the housing and is therefore also made of aluminum.

The internal volume 40 contains a heat transfer fluid which will therefore be able to move between the internal face 36 of the internal partition 32 and the internal face 30 of the heat dissipation wall 26.

The internal heat sink partition 32 receives, in use, the thermal energy produced by the hot components 20. For this purpose, the coupling portions 38 are formed in the internal partition 32 at positions corresponding to the locations of the respective hot components. For good heat exchange, each coupling portion has a shape adapted to the component with which it is associated. For example, for microprocessors 20, the coupling portion 38 is a flat part having a surface (in the plane perpendicular to the drawing) corresponding to the surface of the microprocessors 20.

The reference sign 42 designates a thermal coupling layer applied between the coupling portion 38 and the upper face of the hot component 20. This layer 42 fills the space (assembly play) which is typically less than mm. Conventionally, one can use for the coupling layer 42 a thermal paste, a thermal block or any other suitable material.

The steam chamber 31 is designed to operate according to the general principle of heat pipes (in English "heat pipe", and more specifically here in a flat configuration also called "steam chamber"), and is therefore intended to transport heat thanks to the principle of thermal transfer by phase transition (latent heat) of the heat transfer fluid. For this purpose, the internal volume 40 is a closed hermetic enclosure and the heat transfer fluid is, in operation, in equilibrium with its gaseous phase. The steam chamber 31 therefore constitutes here a flat heat pipe, the hot face of which is the intermediate partition 32 (in particular the coupling portions) and the cold face of which is the wall 26.

Conventionally, the steam chamber 31 comprises a capillary structure 44 configured so as to recirculate the condensed heat transfer fluid towards the coupling portion (s) 38. All forms of capillary structures can be envisaged, based on grooves or metallic foams (for example . fried), or others. In the variant, the capillary structure 44 comprises a main portion 44.1 extending along, and against, the interior face 30 of the heat dissipation wall 26. A second portion of capillary structure

44.2 is arranged along the inner face 36 of the partition 32. The capillary structure 44 covers all of the internal surfaces 30 and 36. The two parts of the capillary structure 44 are advantageously metallic foams, in particular copper.

In use, when the hot components 20 generate heat, this is transmitted by conduction to the respective coupling portions 38 of the partition 32, creating a heat flux at the hot interface of the steam chamber.

31. When the heat is sufficient, the temperature of the heat transfer fluid, then liquid, reaches its boiling point and the liquid is vaporized, absorbing heat. The vapor moves in the chamber from the coupling portion 38, as symbolized in FIG. 1 by the arrows 2, and travels towards the cold interface formed by the wall 26. The vapor condenses on the cold side, in particular at the internal face 30 of the heat dissipation wall 26. The condensation of the heat transfer fluid is accompanied by a release of thermal energy (latent heat) at the level of the wall 26. The heat transfer fluid is then brought back to the liquid state, by the capillary forces inside the capillary structure 44 in the lower part of the chamber 31, towards the coupling portions 38. This results in a closed loop process for transporting and delivering thermal energy.

The thermal energy transmitted to the internal face 30 is distributed in the wall 26 of the cover and is then dissipated towards the ambient medium in contact with the air (as shown by the arrows 4). To improve the heat exchange with the ambient medium, the external surface of the wall 26 is designed as a fin radiator 46. The plurality of parallel fins 46 stand perpendicular to the rear face 28.

A certain number of practical aspects of production still deserve to be noted. The housing 11 with the interior partition is preferably made of aluminum or aluminum alloy. This material is common in the automotive industry and is easily implemented, in particular by extrusion or metal molding. As we have seen in the variant, the internal partition 32 is advantageously made in one piece with the side walls, which reduces the diversity of the pieces, simplifies assembly, and allows the use of the same materials, and guarantees the sealing of the bottom of the steam chamber.

The coupling portions 38 (sunken regions) can be easily obtained by stamping or metal molding.

The cover 22 is fixed to the body 24 by any suitable means, for example screwing or welding, if necessary with a seal at the interface of the two parts. It is the same for the bottom 24.2 fixed on the side walls 24.2. The assembly of the cover 22 to the body 24 is made to be liquid and gas tight.

The printed circuit is fixed in the housing to a shoulder 24.3 inside the side walls 24, for example by means of screws 25 or the like.

The heat transfer fluid is chosen to have a balance between liquid and vapor phases at operating temperatures, and also for its compatibility with the material of the envelope of the chamber formed by the wall 26 and the partition 32. For aluminum walls, may use a heat transfer fluid comprising ammonia. Alternatively, it is possible to use a heat-transfer fluid, if necessary with an adjuvant (s), for example propylene glycol.

Another alternative construction of the housing 111 is illustrated in FIG. 2. With reference to FIG. 1, identical or similar elements are designated by the same reference signs, increased by 100.

The variant of FIG. 2 differs mainly from that of FIG. 1 by the fact that the drainage partition 132 is an attached part which is fixed to the cover 122, in particular to the external wall 126. The steam chamber 131 therefore remains here integrated into the cover 122.

We recognize in Figure 2 the cover 122 and the body of the housing 124 which define an interior space 140 for the electronic card 113, which comprises in the plane of the figure two hot components 120. The cover 122 comprises side walls 122.1 recessed which form a peripheral rim

122.2 on which the printed circuit 114. The body 124 comprises a base 124.1 made in one piece with the side walls 124.2. The cover 122 penetrates slightly, with its side walls 122.1, inside the body 124 and is securely fixed by any appropriate means, and closed in a leaktight manner by seals or the like.

As can be seen, the partition 132 extends in a main plane P at a distance from the surface 130 to define the interior volume 140. The coupling portions 138 are so-called depressed areas (here downwards) to approach the surface of the hot components 120. The partition 132 comprises a peripheral edge 132.1 projecting from the plane P on the side opposite to the coupling portions 138. The partition 132 is fixed to the face 130 of the wall 126 by this peripheral edge 132.1 by any appropriate means: screwing, welding, etc., and if necessary supplemented by a gasket 132.2. The assembly of the intermediate partition 132 is made to be liquid and gas tight.

It will be noted that in the figure the partition 132 extends over the entire inner face 130 of the wall 126. However, it will be understood that in certain variants, for example where the hot components are placed on only one section of the printed circuit. , the internal heat dissipation partition may extend over only part of the internal face 130 of the wall 126.

Claims (12)

claims 1. Housing (11) of a computer module for a motor vehicle, said housing defining an interior space (12) for housing a printed circuit (14) carrying at least one hot component (20); said housing comprising a heat dissipation wall (26) having an external face (28) for exchange with the ambient medium and an opposite internal face (30); characterized in that the housing (11) comprises an interior heat drain partition (32) having a first face (34), said drain face, facing towards said interior housing space and a second opposite face (36), said face interior, the interior heat sink partition (32) comprising at least one coupling portion (38) intended to be thermally coupled to a hot component (20) of the printed circuit; and in that said housing comprises a steam chamber (30) integrated between the heat dissipation wall (26) and the internal heat sink partition (32), the steam chamber being fluid-tight and having an interior volume (40 ) delimited at least in part by the internal faces (30, 36) of said heat dissipation wall (26) and internal partition (32), the internal volume (40) containing a heat transfer fluid. 2. Housing according to claim 1 comprising a capillary structure (44) configured so as to recirculate the condensed fluid towards the coupling portion (s). 3. Housing according to claim 2, wherein the capillary structure (44) comprises a main portion (44.1) extending in the steam chamber (30) along the internal face (30) of the heat dissipation wall ( 26). 4. Housing according to claim 1, 2 or 3, wherein the one or more coupling portions (38) are pressed towards the interior space (12). 5. Housing according to one of the preceding claims, in which the housing comprises a body (24) closed by a cover (22), the body comprising a bottom (24.2) and side walls (24.1). 6. Housing according to claim 5, wherein the inner partition (32) is formed in one piece with the side walls (24.1) and, preferably, the cover (22) comprises the heat dissipation wall (26). 7. Housing according to claim 5 or 6, wherein the cover, the body and the interior partition are made of aluminum or aluminum alloy. 8. Housing according to any one of claims 1 to 5, wherein the cover (122) comprises the heat dissipation wall (126) and the interior partition (132) is fixed to said cover. 9. Housing according to claim 8, wherein the cover (122) and the body (124) are made of aluminum or aluminum alloy; and the interior partition (132) is made of aluminum or copper, or an alloy of aluminum or copper. 10. Housing according to any one of the preceding claims, in which the internal partition extends over part or all of the heat dissipation wall. 11. Housing according to any one of the preceding claims, in which the external face (28) of the heat dissipation wall (26) carries a heat dissipation structure, for example cooling fins (46). 12. automotive computer module comprising a housing according to any preceding claim inside which is placed a printed circuit (14) on which are mounted electronic components called "hot components" (20); wherein the interior heat sink partition (32) comprises a plurality of recessed coupling portions (38), each being thermally coupled to a respective hot component (20) mounted on the printed circuit (14), preferably via a pad ( 42) or a thermal paste.