ON-BOARD TELEMATIC DEVICE WITH INTEGRATED COOLING FOR A MOTOR VEHICLE

Abstract

An on-board telematic device intended to be attached to a metal part (3) of a body of a motor vehicle comprises, according to the invention, a housing (1) integrating a printed circuit board (5), a face of which supports at least one electronic power component (6), a radiofrequency antenna (7), intended to extend through an opening of the metal part (3), and a metal screen (9) interposed between a lower part of the antenna (7), on the one hand, and the printed circuit board (5) and said at least one component, on the other hand, in order to isolate the antenna from parasitic emissions. The component (6) is placed in line with the metal screen (9) and in thermal contact with a portion of said screen, and said screen (9) is made of a thermally conductive material so as to form a thermal transfer means between the electronic power component (6) and the metal part (3).

Claims

1. An onboard telematic device that is intended to be attached to a metal part (3) of a body of a motor vehicle, including a housing (1) incorporating a printed circuit board (5), one face of which bears at least one power electronic component (6), a radiofrequency transceiving antenna (7), which is intended to extend through an opening in the metal part (3), and a metal screen (9) that is interposed between a lower part of the antenna (7) on one side and the printed circuit board (5) and said at least one component in order to insulate the antenna from parasitic emissions, said screen being intended to be attached between said metal part (3) and the housing (1) so as to provide electrical continuity, in which device said at least one component (6) is placed in line with the metal screen (9) and in thermal contact with a portion of said screen, and said screen (9) is made of thermally conductive material so as to form a means for heat transfer between the power electronic component (6) and the metal part (3).

2. The device as claimed in claim 1, characterized in that the metal screen (9) includes a rim that bears against an outer face of the housing and is peripheral to the opening, and in that the device is capable of being attached to the metal part by means of fastening bolts (4) passing through said rim and the outer face of the housing (1) together.

3. The device as claimed in either of the preceding claims, characterized in that the thermal conductivity of the conductive material is higher than or equal to 50 W.Math.m.sup.−1.Math.K.sup.−1.

4. The device as claimed in claim 3, characterized in that the conductive material is steel.

5. The device as claimed in claim 3, characterized in that the conductive material is aluminum.

6. The device as claimed in claim 3, characterized in that the conductive material is zamak.

7. The device as claimed in any one of the preceding claims, characterized in that said at least one power electronic component (6) is borne by a face of the printed circuit board (5) that is directly facing the portion of said screen (9), and in that a thermal interface-forming layer (11) is interposed between a lower part of the portion of said screen (9) and the upper part of said component.

8. The device as claimed in any one of claims 1 to 7, characterized in that said at least one power electronic component (6) is borne by a first face of the printed circuit board (5) opposite a second face of the board (5) that is directly facing the portion of said screen (9), and in that a thermal interface-forming layer (11) is interposed between a lower part of the portion of said screen (9) and the first face of the printed circuit board (5).

9. The device as claimed in any one of claims 2 to 8, characterized in that the rim of the metal screen (9) runs parallel to the printed circuit board (5) so as to form one face of said housing (1).

10. The device as claimed in claim 9, characterized in that said rim includes a projection extending into the interior of the housing (1), with a lower portion of said projection placed in line with and in thermal contact with another power electronic component (6′) borne by said printed circuit board (5).

Description

[0019] The invention will be better understood upon reading the following description, given with reference to the appended figures, in which:

[0020] FIG. 1, which has already been described above, schematically illustrates two onboard telematic devices with integrated cooling for a power electronic component in position attached to the roof of a motor vehicle;

[0021] FIG. 2 schematically illustrates a first embodiment of a telematic device according to the invention, in position attached to the roof of a motor vehicle, and according to two variant embodiments;

[0022] FIG. 3 schematically illustrates a second embodiment of a telematic device according to the invention, in position attached to the roof of a motor vehicle.

[0023] In all of the figures, the various common elements bear the same reference symbols.

[0024] The principle of the invention is based on the presence, in an onboard telematic device 2 such as described above with reference to FIG. 1, of the metal screen 9, the primary function of which is to protect the radiofrequency communication antenna 7 from interference generated by the electronic components of the device. According to the invention, what is proposed is to assign a second function to this screen by also using it as a vector for thermal energy between the power electronic component and the metal portion of the vehicle body, for example the vehicle roof, to which the device is to be attached.

[0025] In doing so, the metal screen 9 becomes a thermal conductor and draws the heat to be dissipated to the metal body portion which then acts as a heatsink.

[0026] A first embodiment will now be described with reference to FIG. 2, which shows an onboard telematic device 2 already attached to the metal portion of the vehicle body, here the roof 3. This device includes all of the elements already described with reference to FIG. 1. However, unlike in FIG. 1, the power electronic component 6 that is to be cooled is placed in line with the metal screen 9 and in thermal contact with a portion of said screen. Additionally, the screen 9 is made of thermally conductive material so as to form a means for heat transfer between the power electronic component 6 and the metal part 3.

[0027] The conductive material is preferably chosen from metallic materials exhibiting a thermal conductivity that is higher than or equal to 50 W.Math.m.sup.−1.Math.K.sup.−1. For example, it is possible to use steel, aluminium or zamak, which is an alloy of zinc, aluminum and of magnesium and copper.

[0028] In the case of FIG. 2(a), the power electronic component 6 is borne by the top face of the board 5, more generally by the face of the printed circuit board 5 that is directly facing the portion of the screen 9. In this case, a thermal interface-forming layer 11 is preferably interposed between a lower part of the portion of the screen 9 and the upper component part.

[0029] In the variant of FIG. 2(b), the power electronic component 6 is borne by the other face of the printed circuit board, i.e. the face of the printed circuit board 5 opposite that which is directly facing the portion of the screen 9. Here again, a thermal interface-forming layer 11 is preferably interposed, this time between the lower part of the portion of said screen 9 and the face of the printed circuit board 5 that is directly facing the portion of the screen 9.

[0030] In both variants, the layer 11 is formed of a thermal grease, of a thermal adhesive, of a thermal paste or of any other material allowing the space between the elements to be filled and good thermal conduction to be provided.

[0031] In any case, it is the metal body portion, here the roof, which acts as a heatsink for the thermal energy passing therethrough, as indicated by the dashed arrows, between the component 6 and the body via the metal screen 9.

[0032] In a second embodiment illustrated schematically in FIG. 3, the rim of the metal screen 9 is further sized such that it runs parallel to the printed circuit board 5 so as to form one face (in this example the upper face) of the housing 1.

[0033] One advantage of this second embodiment is that the screen 9 may also be used as a thermal energy vector for other components of the device 2 that are to be cooled, such as a second power electronic component 6′. This second component 6′ is here placed in line with and in thermal contact with a lower portion of a projection 12 of the rim that extends into the interior of the housing 1.