HEAT SINK DEVICE FOR A MOTOR VEHICLE LIGHTING MODULE

Abstract

A heat sink device for a motor vehicle lighting module made of stamped aluminum and ensures good thermal conductivity. The arrangement of the cooling fins of the device is such that the device is able to be installed in various orientations, while at the same time ensuring good dissipation of the heat produced by a printed circuit board attached to the device.

Claims

1. A heat sink device for a motor vehicle lighting module, comprising a base intended to receive, on a first face, a printed circuit board and comprising heat dissipation means on an opposite second face, wherein the heat dissipation means comprise cooling fins that are formed by folds of at least one metal sheet, the heat dissipation fins being joined to the base by way of an attachment between at least one of the folds and the base.

2. The device as claimed in claim 1, wherein the base is made of stamped aluminum.

3. The device as claimed in claim 1, wherein the cooling fins are made of aluminum.

4. The device as claimed in claims 1, wherein the metal sheet has a thickness of less than 1 mm.

5. The device as claimed in claim 1, wherein the base and/or the cooling fins have a thermal conductivity of between 180 and 230 W/(m.Math.K).

6. The device as claimed in claim 1, wherein the heat dissipation fins extend in at least two different directions that are parallel to the base.

7. The device as claimed in claim 6, wherein the device comprises a plurality of cooling fins, wherein at least two groups of fins extend in two directions that are perpendicular to one another.

8. The device as claimed in claim 6, wherein the device comprises a plurality of cooling fins that extend radially in a plurality of directions starting from a central portion of the base.

9. The device as claimed in claim 1, wherein the device includes a thermal interface positioned between the cooling fins and the base.

10. The device as claimed in claim 1, wherein the base comprises, on its first face, crimping studs that are intended for attaching a printed circuit board to this face.

11. The device as claimed in claim 1, wherein the device comprises a cover made of stamped aluminum and intended to be attached in a sealtight manner to the first face of the base.

12. A lighting module for a motor vehicle, comprising at least one semiconductor element-based light source and a printed circuit board comprising a circuit for controlling the supply of power to the light source(s), wherein the printed circuit board is attached to a heat sink device of the module, the device being as claimed in claim 1.

13. The lighting module as claimed in claim 12, wherein the printed circuit board is covered in a sealtight manner by a cover of the heat sink device.

14. The device as claimed in claim 2, wherein the cooling fins are made of aluminum.

15. The device as claimed in claim 2 wherein the metal sheet has a thickness of less than 1 mm.

16. The device as claimed in claim 2 wherein the base and/or the cooling fins have a thermal conductivity of between 180 and 230 W/(m.Math.K).

17. The device as claimed in claim 2, wherein the heat dissipation fins extend in at least two different directions that are parallel to the base.

18. The device as claimed in claim 7, wherein the device comprises a plurality of cooling fins that extend radially in a plurality of directions starting from a central portion of the base.

19. The device as claimed in claim 2, wherein the device includes a thermal interface positioned between the cooling fins and the base.

20. The device as claimed in claim 2, wherein the base comprises, on its first face, crimping studs that are intended for attaching a printed circuit board to this face.

Description

[0029] Other features and advantages of the present invention will be better understood with the aid of the description and the drawings, in which:

[0030] FIG. 1 is a perspective depiction from below of a device according to one preferred embodiment of the present invention;

[0031] FIG. 2 is a perspective depiction from above of a device according to one preferred embodiment of the present invention;

[0032] FIG. 3 is a perspective depiction from above of a device according to one preferred embodiment of the present invention, including a printed circuit board;

[0033] FIG. 4 is a perspective depiction from above of a device according to one preferred embodiment of the present invention, including a cover;

[0034] FIG. 5 is a perspective depiction from above of a device according to one preferred embodiment of the present invention;

[0035] FIG. 6 is a schematic depiction of a view from below of a device according to one preferred embodiment of the present invention.

[0036] In the following description, similar reference numerals will be used to describe similar concepts across the various embodiments of the invention. Thus, the numerals 100, 200, 300 describe a heat sink device in three different embodiments according to the invention.

[0037] Unless specified otherwise, technical features that are described in detail for one given embodiment may be combined with the technical features that are described in the context of other embodiments described by way of non-limiting example.

[0038] FIG. 1 shows a heat sink device 100 for a motor vehicle lighting module according to a first exemplary embodiment of the invention. The device comprises a base 110 with a generally flat geometry, which base is preferably made of substantially pure aluminum and has a thermal conductivity of between 180 and 230 W/(m.Math.K). In the example illustrated, the base has a contour of generally rectangular shape. The base forms a main heat sink element of the device. A first face 112, shown directed downward, is intended to receive a printed circuit board, not illustrated. The printed circuit board may for example comprise light sources of the lighting module. This may involve light sources based on semiconductor components, for example light-emitting diodes, LEDs. As an alternative, the printed circuit board may comprise a circuit for controlling the supply of electric power to such light sources. The converters of such a circuit, such as the light sources, generally generate significant heat when they operate, which heat the device 100 has to be able to dissipate.

[0039] A second face 114, opposite the first face 112 and illustrated directed upward, comprises cooling fins 120 that are joined to the base by way of an attachment between at least one of the folds and the base. In the example shown and according to one preferred embodiment, the fins extend in at least two directions that are different but parallel to the plane of the base 110, so as to create air flow channels or grooves. In the example shown, these are two directions A, B that are generally perpendicular to one another. The cooling fins 140 are formed by folds of a metal plate. The plate preferably has a thin thickness of less than one millimeter, for example of 0.6 mm. Advantageously, it is also made of aluminum and has a high thermal conductivity of between 180 and 230 W/(m.Math.K). The dissipation fins may be formed by one or more clad and knurled aluminum sheets. The height of the folds is chosen depending on the intended application. A greater height of the folds implies a larger heat exchange area of the fins with respect to the ambient air, and therefore a better heat dissipation capability of the device. The height of the folds may by way of example be between 15 and 25 mm. The cooling fins are attached to the face 114 of the base 110 in such a way as to ensure good mechanical strength and a good thermal link between the two elements. The link is preferably produced by bonding using a polymerization adhesive that is cured when the device is put into a polymerization oven. As an alternative, other attachments between the fins 120 and the base 110 may be contemplated without otherwise departing from the scope of the present invention, in particular an attachment by brazing the two components in question. As shown in FIG. 1, a plurality of groups of fins, two in each of the directions A and B, may be folded from one and the same aluminum sheet. As an alternative, each of the groups, or each of the fins, may be folded from a dedicated aluminum sheet. A protective grating, not illustrated, preferably made of plastic, may be provided so as to cover the cooling fins, in order to protect them upon the occurrence of any mechanical shocks.

[0040] FIG. 2 shows the first face 112, which is opposite the face 114 of the base 110 of the device 100. This face is intended to receive a printed circuit board that comprises heat-producing active electronic elements. In the example shown, the face 112 comprises crimping studs 113 that are intended to interact with holes that are provided in the substrate of a printed circuit board for this purpose. The crimping studs 113 are preferably formed by stamping of the plate made of aluminum that forms the base 110. To guarantee this effect, it is necessary to provide a thickness of at least 3 to 4 mm for the base. FIG. 3 shows by way of example a printed circuit board 10, without illustrating the electronic components thereof, held by the studs 113. The crimping makes it possible to ensure good mechanical strength and good thermal contact between the substrate of the printed circuit board and the base 110, in order to guarantee the exchange of heat between the two elements. As an alternative or in addition to the crimping, the printed circuit board may be bonded using a thermally conductive adhesive, for example a polymerization adhesive, on the face 112 of the base 110.

[0041] Heat is first of all exchanged between the printed circuit board, on which the heat is produced, and the base 110 of the device 100. Next, through the thermal link between the base 110 and the cooling fins 120, the heat travels to said cooling fins. The cooling fins have a large heat exchange area with the ambient air, which makes it possible to dissipate the heat.

[0042] The illustration of FIG. 4 once again takes up the device 100 comprising the base 110, on one face 114 of which base the cooling fins 120 are attached. The opposite face 112 of the base 110 is covered by a cover 130. The cover protects the printed circuit board that it covers on the face 112 from mechanical shocks and from possible electromagnetic interference. It may also contribute to the overall heat dissipation capability of the device. To this end, it is advantageous for the cover 130 to be formed by a plate made of lightweight metal, such as aluminum. The shape of the plate is obtained by stamping using a suitable tool. The variant of aluminum used preferably has a thermal conductivity of between 180 and 230 W/(m.Math.K). The lower edge of the cover may, in a known manner, interact with the edge of the base 110 in order to link the two elements. Other mechanical linking means, such as crimping, and preferably also thermal linking means, are known per se in the art, and implementing them is within the scope of those skilled in the art. In order to guarantee the sealtightness of the link between the base 120 and the cover 130, a gasket 134, as illustrated in FIG. 4, manufactured for example from rubber, may be installed at the joint. In the example shown, the cover comprises an aperture 132 allowing access to the inside of the device, that is to say to the printed circuit board received on the face 112 of the device. The aperture 132 makes it possible for example to produce an electrical connection from the outside of the device to the printed circuit board.

[0043] FIG. 5 shows another embodiment of the heat sink device 200 according to the invention. The device comprises a base 210 with a generally flat geometry, which base is preferably made of aluminum and has a thermal conductivity of between 180 and 230 W/(m.Math.K). A first face 212, shown directed upward, is intended to receive a printed circuit board, not illustrated. A second face 214, opposite the first face 212 and illustrated directed downward, comprises cooling fins 220 that extend in at least two directions that are different but parallel to the plane of the base 210. The face 212 has the particular feature that a recessed portion 216 has been produced by stamping of the base 210. Such a configuration is beneficial when the heat sink device 200 is intended to house therein a printed circuit board that comprises electronic components that are mounted on these two flat surfaces. When the printed circuit board is received on the face 212, the electronic components that are mounted on that face of the printed circuit board facing the face 212 are then housed in the recessed portion 216. Alternative geometries may obviously be provided according to the same principle and produced by suitable stamping, without otherwise departing from the scope of the present invention.

[0044] FIG. 6 shows a schematic view from above of an additional embodiment of the heat sink device 300 according to the invention. The face 314 of the base 310 is shown. This is the face to which the cooling fins 320 are attached. In comparison with the previous examples, an alternative arrangement of the cooling fins is illustrated by way of example. The fins 320 extend radially from a central portion of the base 310, so as to form a star-shaped or circular structure. Each pair whose cooling fins are radially opposite about the center is oriented in one direction. Other geometries for arranging the cooling fins are able to be contemplated. A larger number of directions in which the cooling fins extend generally implies increased flexibility in terms of the possibilities for positioning and orienting the device 300 within a lighting module. With a larger number of ambient air flow directions, the probability of a heat exchange between the cooling fins and the ambient air is generally higher.