FR3035200A1 - BI-MATERIAL HEAT DISSIPER MODULE - Google Patents

Abstract

The invention relates to a heat sink module (2) comprising a core (6) with an outer surface and a sleeve (8) in contact with the outer surface of the core (6). The core (6) is a first material and the sleeve (8) a second material, the first material having a thermal conductivity which is at least five times, preferably ten times, greater than the thermal conductivity of the second material.

Description

The invention relates to the field of heat dissipation for electronic component (s) for cooling said component (s). More particularly, the invention relates to the field of heat dissipation for light source (s) of light device, such as a lighting device for a motor vehicle. EP 2 133 914 A2 discloses a heat sink module for microprocessors or electroluminescent diodes. However, it has a certain massiveness as well as some constraints with regard to the location of the light sources. The object of the invention is to propose a heat sink module that is thermally efficient, compact, lightweight and / or simple to produce. The subject of the invention is a heat sink, comprising: a core with an outer surface; and a sleeve, in contact with at least a portion of the outer surface of the core; remarkable in that the core is of a first material and the sleeve is a second material, the first material having a thermal conductivity which is at least five times greater than the thermal conductivity of the second material.According to an advantageous embodiment of the invention, the first material having a thermal conductivity which is at least ten times greater than the thermal conductivity of the second material. According to an advantageous embodiment of the invention, the core is adapted to conduct heat along said core from one end of said core to a portion of the outer surface in contact with the sleeve, and the sleeve is adapted to conduct heat at least a portion of said sleeve in contact with the outer surface of the core to an outer end of said sleeve. For example, the core conducts the heat substantially longitudinally and the sleeve conducts the heat substantially radially. According to an advantageous embodiment of the invention, the sleeve is in contact with at least a portion of the outer surface of the core so as to surround it at least partially. Advantageously, the contact surface between the core and the sleeve is at least 50% of the core area.

According to an advantageous embodiment of the invention, the sleeve comprises an annular or cylindrical portion. According to an advantageous embodiment of the invention, the annular portion is in contact with the core.

According to an advantageous embodiment of the invention, in which the sleeve comprises fins. According to an advantageous embodiment of the invention, the fins extend essentially radially from the annular portion towards the outside of the sleeve. According to an advantageous embodiment of the invention, the core comprises a mounting surface intended to receive at least one light source. According to an advantageous embodiment of the invention, the mounting surface is at one end of the core. According to an advantageous embodiment of the invention, the core comprises a hollow cylindrical portion.

According to an advantageous embodiment of the invention, the hollow cylindrical portion is formed by a circular wall, the mounting surface extending radially from said wall inwards, said surface comprising a central orifice. According to an advantageous embodiment of the invention, the first material comprises at least one metal.

According to an advantageous embodiment of the invention, the metal comprises aluminum and / or copper and / or an alloy of these metals. According to an advantageous embodiment of the invention, the first material has a thermal conductivity greater than or equal to 50 W / (m K). According to an advantageous embodiment of the invention, the second material is a plastic material that conducts heat with a thermal conductivity greater than or equal to 0.5 W / (m K), preferably greater than or equal to 1 W / (m K).

According to an advantageous embodiment of the invention, the heat conductive plastic material comprises a base material and a heat conductive filler material. According to an advantageous embodiment of the invention, the base material of the heat conductive plastic material comprises a polymer. According to an advantageous embodiment of the invention, the heat-conducting filler material comprises graphite carbon fibers and / or at least one ceramic. According to an advantageous embodiment of the invention, the ceramic comprises aluminum nitride and / or or boron nitride.

According to an advantageous embodiment of the invention, the density of the second material is at least 25%, preferably 40%, less than the density of the first material. According to an advantageous embodiment of the invention, the sleeve is overmolded on the core. According to an advantageous embodiment of the invention, the core is inserted in force in the sleeve. The invention also relates to a heat sink module, characterized in that it comprises a heat sink according to the invention and a fan disposed opposite the core of the heat sink so as to generate a stream of air along of the sleeve.

According to an advantageous embodiment of the invention, the fan comprises an electric drive motor housed in a hub of said fan. According to an advantageous embodiment of the invention, the fan comprises at least one housing arranged so as to protect the radial end of the fan. According to an advantageous embodiment of the invention, the module further comprises at least one tubular casing receiving the core and the sleeve, the fan being disposed at one end of said casing. According to an advantageous embodiment of the invention, the case and the envelope are made of material.

According to an advantageous embodiment of the invention, the case and the envelope have different shapes. According to an advantageous embodiment of the invention, the case and the envelope are complementary forms, for example identical.

According to an advantageous embodiment of the invention, the case is of circular, triangular, square or hexagonal shape. According to an advantageous embodiment of the invention, the shape of the housing is preferably square with rounded corners. The invention also relates to a light source support for a light device, in particular for a motor vehicle, comprising: a heat sink; at least one light source; remarkable in that the dissipator is in accordance with the invention, the light source being mounted on the mounting surface. According to an advantageous embodiment of the invention, the light source support comprises a heat sink module according to the invention and in which the heat sink is part of said heat sink module. According to an advantageous embodiment of the invention, the source light source comprises at least one semiconductor transmitter element. According to an advantageous embodiment of the invention, the light source is an electroluminescent diode. According to an advantageous embodiment of the invention, the light-emitting diode is a laser diode. According to an advantageous embodiment of the invention, the light source is in contact with the heat sink. This contact may be direct or indirect, for example via an integrated circuit card, with the sink. According to an advantageous embodiment of the invention, the core comprises a hollow cylindrical portion and, at one end of said portion, a mounting surface of one or more light sources; and preferably, the hollow cylindrical portion being formed by a circular wall, the mounting surface extending radially from said wall inward, said surface comprising a central orifice; the or at least one of the light sources is disposed on the mounting surface. According to an advantageous embodiment of the invention, the module further comprises electrical supply wires for the light source or sources, said wires extending in the hollow of the core from said light source (s) to the light source. end of the core opposite to the mounting surface. According to an advantageous embodiment of the invention, the module comprises electrical wires for supplying the light source or sources, said wires extending from an outer surface of the sleeve between two fins of said sleeve. According to an advantageous embodiment of the invention, the electrical supply son of the light source or sources are housed in a groove formed on the outer surface of the sleeve between the two fins. Luminous device, in particular lighting and / or signaling for an automobile vehicle, remarkable in that it comprises a light source support according to the invention. The measurements of the invention are interesting in that they provide a thermal diffuser or heat diffuser module that is compact, lightweight, efficient and simple in construction. Indeed, the fact of using two different materials for the core and the finned sleeve not only optimizes the weight of the module but also its construction. The sleeve having a larger exchange surface than the core, it can be made of a less good conductor material without penalizing the performance of the module. In addition, the fact of using a conductive plastic material and providing an overmolding is interesting from a point of view of weight and cost of manufacture. The diffuser of the invention is particularly well suited to a single light source, such as a laser diode. The light source may be centrally disposed on the end of the core and have power leads extending along the core within the core. Other features and advantages of the present invention will be better understood from the description and the drawings, of which: FIG. 1 is a perspective view of a light source support, including a dissipator module heat according to the invention; FIG. 2 is a front perspective view of the dissipator module of FIG. 1, provided with the light source; Figure 3 is a side view of the finned heat sink of the module of Figures 1 and 2; FIG. 4 is a rear perspective view of the dissipator module of FIGS. 1 and 2, the module being provided with the fan; FIG. 5 comprises two rear and front perspective views of the core of the dissipator module of FIGS. 1 and 2, also illustrating the position of the fins. Figure 1 illustrates in perspective a heat sink module according to the invention. The heat sink module 2 essentially comprises a core 6 and a fin cooler in the form of a sleeve 8 surrounding the core 6. This latter supports a light source 10. It may be of the electroluminescence diode type. In this case it is of the laser diode type arranged in the center of the core 6. The module 2 may comprise an envelope 4 surrounding the core 6 and the finned dissipator 8. This envelope 4 is preferably of the tubular type, more preferably of square section . It can be closed at its rear end by a fan 12, the fan being able to generate a cooling air current along the fins between the dissipator 8 and the envelope. Figure 2 illustrates the heat sink module of Figure 1 where the casing 4 is absent. It can be seen that the fan 12 comprises a fan wheel 14 disposed opposite the fins of the dissipator 8 and a housing 16 around the fins. The core 6 is made of a first material, preferably metal such as aluminum, with a high coefficient of thermal conductivity, for example greater than or equal to 50 W / (m K). The finned heat sink 8 is made of a second, less dense material than the first and potentially less good conductor. It may be a plastic material that conducts heat with a thermal conductivity greater than or equal to 0.5 W / (m K), preferably 1 W / (m K). The thermal conductivity of this type of material can be essentially between 1 and 20 W / (m · K), while that of aluminum is of the order of 200 W / (m · K). This type of plastic material is available in particular under the trade names CoolPoly® and Therma-Tech® (from PolyOne). In order to obtain a heat conductive plastic material, it is known to provide a base plastic material, such as a polymer, in which a thermally conductive filler material has been incorporated. It may especially be graphite carbon fibers, especially in the form of nanotubes, and ceramic such as aluminum nitride or boron nitride. This makes it possible to change the thermal conductivity of a conventional plastic material of the order of 0.1 W / (mK) to a value between 1 and W / (mK), ie a multiplication of the coefficient by a factor of from 10 to 200. Recent studies also show that it is possible to control and thereby increase the thermal conductivity of a polymer by working on its atomic structure by nanotechnologies.

A thermoplastic material comprising a thermoplastic resin and fillers whose nature, shape and size are chosen to increase the thermal conductivity of the resin alone can be used. It is possible to use a thermoplastic resin chosen from the group comprising: polyamide, polyethylene.

Fillers selected from the group consisting of: nano particles, zinc sulfide, boron nitride, carbon-based particles. For example, the following thermally conductive thermoplastic materials may be used: a composition comprising a polyamide matrix and zinc sulfide dispersed in the matrix; a composition comprising a matrix containing particles whose shape and size are chosen to obtain a low-fill thermal conductivity; a composition comprising a thermoplastic polymer, at least 60% by weight of a mixture of boron nitride powders having an average size of at least 50 microns; and a coupling agent. Such a composition has a thermal conductivity greater than 15 VV / (m.K); a composition comprising a resin matrix and a charge with a high thermal conductivity. The high thermal conductivity charge forms an organic-inorganic composite in continuity with the matrix, and the charges have an aspect ratio of between 3 and 100. The charges are substantially evenly distributed in the matrix, and are substantially aligned in the matrix. the same direction; a composition comprising a highly structured resin matrix, and charges of high thermal conductivity. The charges with high thermal conductivity have a length of 1 to 1000 nm, and have an aspect ratio of between 3 and 100; a composition comprising 30 to 80% by weight of thermoplastic resin; 10 to 60% by weight of a mixture containing insulating charges of spherical and plate form; and 10 to 50% by weight of inorganic fibers.

The thermally conductive plastic materials have a density of the order of 1.5 to 2, while aluminum, one of the less thermally conductive good metals, is 2.7. The use of a thermally conductive plastic material thus makes it possible to reduce the mass of the thermal diffuser by about 26% to 44%.

The thermal diffuser 8 is preferably overmoulded on the core 6, it being understood that other bonding processes between the two are possible. FIG. 3 is a view of the section of the thermal diffuser 8. The latter comprises a cylindrical portion 81 and fins 82 which extend radially outwardly from the cylindrical portion 81. The latter makes it possible to ensure intimate contact and optimal with the outer surface of the core. It also makes it possible to ensure mechanical retention of the fins 82. The fins may have a thickness that decreases progressively as one moves away from the cylindrical portion 81. The fins 82 are preferentially distributed homogeneously around of the cylindrical portion 81.

FIG. 4 is a rear view of the heat diffuser module of FIGS. 1 and 2. There can be seen the fan wheel 14 which comprises vanes 141 fixed to a hub 142. The latter has an outside diameter close to that of the core. . It may contain an electric motor (not visible) for driving in rotation of the wheel 14.

Fig. 5 comprises two views: the top view is a rear perspective view of the kernel and the bottom view is a front perspective view of the kernel. The heat diffuser is not really represented, only the fins are represented. It can be observed that the core 6 comprises a cylindrical portion 61 and an annular portion 62 extending radially at the front end of said core 6. This annular portion 62 forms an orifice 63 able to pass wires. or power cables of the light source (s). The outer face of the annular portion 62 also forms a mounting surface 64 of the light source (s) 10. This construction of the core 6 is particularly advantageous for mounting a single light source, such as a laser diode. The heat sink module that has just been described can thus serve as a source of light source (s) and be integrated into a lighting device such as a motor vehicle headlamp.

Claims (15)

REVENDICATIONS1. Heat sink (2), comprising: a core (6) with an outer surface; and a sleeve (8) in contact with at least a portion of the outer surface of the core (6); characterized in that the core (6) is of a first material and the sleeve (8) of a second material, the first material having a thermal conductivity which is at least five times greater than the thermal conductivity of the second material. 2. heat sink (2) according to the preceding claim, wherein the core (6) is adapted to conduct heat along said core from an end of said core to a portion of the outer surface in contact with the sleeve (8). and the sleeve (8) is adapted to conduct heat from at least a portion of said sleeve in contact with the outer surface of the core (6) to an outer end of said sleeve (8). Heat sink (2) according to any one of claims 1 to 2, wherein the sleeve (8) is in contact with at least a portion of the outer surface of the core (6) so as to surround it at least partially. The heat sink (2) according to any one of the preceding claims, wherein the sleeve (8) comprises fins (82). 5. Heat sink (2) according to claim 4, wherein the fins (82) extend substantially radially from the annular portion (81) outwardly of the sleeve (8). The heat sink (2) according to any one of the preceding claims, wherein the core (6) comprises a mounting surface (64) for receiving at least one light source (10). 7. Heat sink (2) according to the preceding claim, wherein the core (6) comprises a hollow cylindrical portion (61). 3 0 3 5 2 00 11 8. Heat sink (2) according to the preceding claim, wherein the hollow cylindrical portion (61) is formed by a circular wall, the mounting surface (64) extending radially from said wall (61) inwardly, said surface (64) including a central orifice (63). 5 9. Heat sink (2) according to any one of the preceding claims, wherein the second material is a plastic material which conducts heat with a thermal conductivity greater than or equal to 0.5 W / (mK), preferably greater than or equal to 1 W / (mK). The heat sink (2) of claim 9, wherein the heat conductive plastic material comprises a base material and a heat conductive filler material. 11. Heat sink (2) according to claim 10, wherein the heat conductive filler material comprises graphite carbon fibers and / or at least one ceramic. 15 12. Heat sink module (2), characterized in that it comprises, a heat sink, according to one of claims 1 to 11, and a fan (12, 14), said fan being arranged in front of the core (6) the heat sink so as to generate a stream of air along the sleeve (8). 20 13.Support of light source for light device, especially for a motor vehicle, comprising: a heat sink; at least one light source; characterized in that the dissipator (2) is according to one of claims 6 to 11, the light source being mounted on the mounting surface. 14. Light source support according to the preceding claim characterized in that the light source support comprises a heat sink module according to claim 12 and wherein the heat sink is part of said heat sink module. 3035200 12 15. Illuminating device, including lighting and / or signaling for a motor vehicle, characterized in that it comprises a light source support according to one of claims 13 to 14.