Lighting module comprising a cooling device producing an air flow by ionization of air

Abstract

One aspect of the invention relates to a lighting module M1 for a motor vehicle comprising a light source (2) mounted on a substrate (1), and a cooling device (3) producing an air flow by ionization of air. The cooling device (3) comprises an electrically conductive heat sink (30) forming a first electrode in thermal contact with the substrate (1), and a plurality of fins (300) facing the substrate (1). The cooling device (3) also comprises an electrode unit (31) mounted facing the heat sink (30) to form, with the fins, at least one channel (33), comprising a dielectric electrode support (310) and at least one second electrode (311) supported by the electrode support (310). Connecting the heat sink (30) or the second electrode (311) to a positive polarity produces a flow movement from an inlet opening (312) towards the outlet opening in the channel (33), ionizing the fluid.

Description

DESCRIPTION TITLE: Lighting module comprising a cooling device producing an air flow by ionization of the air TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a lighting module for a motor vehicle and in particular to the cooling of the lighting module. More particularly, the invention relates to a heat sink for the heat generated by at least one component integrated into a lighting module (headlight and / or signaling device) and in particular the front headlights of motor vehicles. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] The light sources present in the lighting module (which may be a projector and / or a signaling device) are subject to overheating and often need to be cooled. This is particularly the case for semiconductor light sources, such as light-emitting diodes, or mini light-emitting diodes or micro-light-emitting diodes or active matrix organic light-emitting diodes or laser diodes. These light sources are in fact very small in size while offering significant lighting power. They are generally arranged on a printed circuit board and are often thermally coupled to one or more heat sinks, also called radiators.

[0003] Published patent document FR3042259 discloses a projector comprising lighting modules and an air cooling duct for said plurality of lighting modules, with at least one inlet for airflow from one or more mechanical fans, several air outlets to said plurality of lighting modules, and a passage connecting said at least one inlet to said air outlets. The mechanical fan(s) and the duct are bulky and complex.

[0004] Furthermore, in these lighting modules, the airflow produced by the mechanical fan in the ducts or along the fins is affected by boundary layer effects. The presence of a boundary layer results in the presence of a thin layer of stagnant air, acting as a thermal insulator between the airflow and the heat sink. In addition, the thickness of the boundary layer increases along the duct, which reduces the operational section of the duct or between two fins, thus reducing the airflow. This phenomenon significantly increases the thermal resistance of the heatsink, which requires larger heatsinks with powerful ventilation.

[0005] There is therefore a need to provide a cooled device having a better efficiency / size ratio than the prior art. SUMMARY OF THE INVENTION

[0006] The applicant considered, without disclosing, an unsuccessful solution consisting of having a cooling device that uses an electro-fluid-dynamic fan operating without mechanical part movement instead of the mechanical fan to produce an airflow towards a heat sink. The electro-fluid-dynamic fan ionizes the air surrounding a charged conductor, producing an airflow by corona effect. The electro-fluid-dynamic fan takes advantage of the corona effect to direct an airflow towards a heat dissipation element equipped with fins arranged downstream of the electro-fluid-dynamic fan, in order to cool the fins of the heat sink which are responsible for receiving the heat from a component intended to be cooled and dissipating it.Adapting these devices to automotive lighting modules results in bulky devices including large heat sinks and electro-fluidic fan arrangements whose cooling performance and power consumption remain conventional.

[0007] The object of the present invention is therefore to provide a cooled device having a better ratio between efficiency and size than the prior art, and than the cooling device envisaged by the applicant in the preceding paragraph.

[0008] To this end, a first object of the present invention consists of a lighting module for a motor vehicle comprising: a substrate comprising an electronic circuit, a light source mounted on the substrate, connected to the electronic circuit in order to power the light source, a cooling device producing an air flow by ionization of the air comprising:an electrically conductive heat sink forming a first electrode, comprising: a first face in thermal contact with the substrate and a second face opposite the first face, an electrode unit facing the second face of the electrically conductive heat sink, the electrode unit comprising: a dielectric electrode support, at least one second electrode supported by the electrode support, the second electrode extending along the second face, said second electrode being spaced from the heat sink, wherein the heat sink forming the first electrode or the second electrode is connected to a terminal of positive polarity forms a positive electrode and respectively the second electrode or the heat sink forming the first electrode is connected to ground to form a negative electrode, so as to produce an air flow movement directed against the heat sink by ionizing the air.

[0009] This means that: ■ either the heat sink (30, 30') forming the first electrode is connected to a terminal of positive polarity to form a positive electrode, and the second electrode (311, 311', 311'") is connected to ground to form a negative electrode, ■ either the second electrode (311, 311', 311'") is connected to a positive polarity terminal to form a positive electrode, and the heat sink (30, 30') forming the first electrode is connected to ground to form a negative electrode;

[0010] By "directing against" is meant the act of producing an ionic wind, by ionization of the air by one electrode, by producing and moving ions directed towards the other electrode until contact with this other electrode, said displacements of the ions causing displacement of surrounding air particles, thus causing air flow from one electrode to the other electrode.

[0011] By an element "facing" another element, we mean that the elements are spaced only by an air gap.

[0012] The cooling device of the invention uses the heat sink of the lighting module as part of the electro-fluidic fan, which reduces the size of the cooling device. The fact of not using a mechanical fan, i.e. a mobile one (motor and blade), nor tubes also reduces the weight of the cooling device.

[0013] Furthermore, using the heat sink as a radiator as well as an electrode of an electro-fluidic fan directly improves the cooling efficiency. First, since the surface of the heat sink forms the other electrode of the electro-fluidic fan, the movement of air takes place between the surfaces of the electrodes, thus reducing the thickness of the boundary layer considerably, and, at the same time, reducing or avoiding the thermal insulation effect of a layer of stagnant air in contact with the heat sink. The fact that the heat sink itself is an electrode therefore solves the boundary layer problem of the unsuccessful solution envisaged by the applicant. Preferably, the heat sink may include fins to promote heat exchange with the air moved by the fan. The reduction of the boundary layer promotes the circulation of air between the fins.Alternatively, the heat sink has pins, studs, or other types of protrusions to increase the heat exchange surface of the heat sink.

[0014] Additionally, cooling is efficient enough to use an FR4 PCB as a substrate, even though FR4 PCBs have poorer heat transfer characteristics than more expensive IMS PCBs. Typically, cheaper components can be used because the steady-state temperature is lower due to better heat dissipation.

[0015] By an IMS PCB type substrate is meant a substrate comprising an electrically insulating layer, for example of the CML6 type (polymer containing ceramic reinforced by a fiberglass mesh), plated on a sole metallic, for example aluminum, and covered with a conductive layer of copper.

[0016] An FR4 PCB substrate is a substrate made of epoxy and glass fabrics; such substrates form the majority of double-sided and multi-layer printed circuits.

[0017] The lighting module according to the invention may also have the optional characteristics listed below, considered individually or in combination:

[0018] According to one embodiment, the second face of the electrically conductive heat sink comprises fins, said fins forming between them at least one channel along which at least the second electrode extends.

[0019] The fins, which form a channel with the electrode unit, allow the air displaced by the cooling device to be channeled. This allows for more air / dissipator exchange and the fins also allow for better cooling of the dissipator.

[0020] Secondly, as the heat sink forms with the dielectric electrode the air flow channel without adding tubes, plenums or guide walls (which are added between the fan and the heat sink in the prior art), the invention also solves the space requirement problem encountered on the heat sinks of the prior art.

[0021] According to an example of this embodiment, the dielectric electrode support is in contact with a longitudinal edge of the fins. This allows the channel to be closed longitudinally and thus forms a closed channel between the inlet(s) and the outlet(s).

[0022] According to an example of this embodiment: the channel is formed between the electrode unit, the fins facing the electrode unit and a portion of the surface of the heat sink located between the fins, the channel forming a flow path for the cooling air circulating between an inlet opening and an outlet opening formed between the unit electrode unit and the heat sink or in the electrode unit and / or the heat sink, and the second electrode comprises an electrical surface facing the first and / or second fin. It is understood that the second electrode runs along the fins of the heat sink so that an ionic wind is established between these electrodes.

[0023] According to an example of this embodiment: the electrical surface of the second longitudinal electrode faces a second fin, the first and second fins form longitudinal edge walls of the channel, the dielectric electrode support forms a cover of the channel, a surface of the heat sink between the first and second fins forms a bottom of the channel, and the electrical surface of the second electrode is oriented along the fins.

[0024] This allows the second face to be used to form the channel and fins as the main part of the electrode formed by the heat sink.

[0025] According to another embodiment which is a variation of this embodiment, the electrode unit comprises a plurality of fins extending from the dielectric electrode support, forming between them with the electrically conductive heat sink a plurality of channels parallel to each other, forming different fresh air flow circuits, and wherein the lighting module comprises a second electrode per fresh air flow circuit along at least one channel forming the fresh air flow circuits. This allows the cooling device to have a plurality of circuits to be more efficient in the same surface area of ​​the heat sink.

[0026] According to an example of this embodiment, the fins of the electrode unit are in physical contact or at least in thermal contact (by an electrically insulating thermal paste or layer for example) with the electrically conductive heat sink.

[0027] According to an example of this embodiment, the fins of the electrode unit are metallic.

[0028] According to an example of one of these two embodiments, the first and second fins each form a longitudinal edge wall of the channel and the electrode support with a surface of the heat sink between the first and second fins, each respectively form a cover and a bottom of the channel, the electrical surface of the second electrode runs along the fins. According to one example, the second electrode is located closer to the bottom than to the cover. According to a variant, the second electrode is located closer to the cover than to the bottom, for example closer to the ends of the fins.

[0029] According to an example of one of these two embodiments, the electrode unit and / or the heat sink forms an inlet opening and / or an outlet opening for respectively bringing fresh air into the at least one channel and expelling hot air from the at least one channel, the air flow movement being produced from said inlet opening towards the outlet opening.

[0030] Fresh air means air intended to cool the heat sink. Hot air means air that has been heated because it was used to cool the heat sink.

[0031] According to an example of one of these two embodiments, each first fin and second fin also contribute to forming another channel, respectively second and third channel, and the electrode unit comprises two other second electrodes, each supported by the dielectric support in respectively the second and third channel. This allows the first and second fins to be used in two channels, which reduces the volume and weight of the cooling device.

[0032] According to an example of one of these two embodiments, the second electrode and the heat sink forming the first electrode are at a minimum distance of 1 to 5 mm.

[0033] According to an implementation of this example, the second electrode and the first fin are at a minimum distance of 1 to 5 mm and the second electrode and the second fins are at a minimum distance of 1 to 5 mm. This allows the air flows to be efficiently moved in the channel.

[0034] According to an example of one of these two embodiments, the second electrode is at the same minimum distance from the two fins. This arrangement makes it possible to balance the movement of the ions in order to reduce, or even avoid, disturbances of the air flow in the channel.

[0035] According to an example of one of these two embodiments, the channel comprises a second outlet opening located at a second longitudinal end of the channel. This makes it possible to divide the (or each) channel into two cooling circuits each having opposite airflow flow directions. Thus, the air circulates in two opposite directions, which makes it possible to reduce the air temperature at each of the outlets, for a given length of the channel. Such a reduction in the temperature at the channel outlet allows for better heat transfer throughout the channel, and thus, more efficient cooling.

[0036] According to an example of one of these two embodiments, the inlet opening is located in the middle between the first and second outlet openings. This allows the channel to have the same length of channels between the inlet and the outlets.

[0037] According to an example of one of these two embodiments, the inlet opening of the channel faces an area of ​​the heat sink corresponding to an area of ​​the substrate connected to the light source(s). This allows the hottest part of the heat sink to be in contact with the air entering the channel to decrease the areas of the heat sink with the highest temperatures; in effect, the air entering the channel is cooler because it has not yet been heated and therefore allows for more efficient cooling. In particular, the inlet opening may face the area of ​​the substrate immediately to the rear of the light source.

[0038] Preferably, the light sources are mounted on an area of ​​the substrate extending in a main direction in the plane of the second face of the substrate, the channels extend in a direction perpendicular to + / -20 0to the main direction. This allows the air arriving from the opening to start heating by exchange with the substrate area and to exit the channel away from one of the light sources closest to an edge of the substrate. This prevents the heated air leaving the channel from coming into contact with hot areas opposite light sources. The light sources can be mounted on the substrate by being aligned on a light source arrangement axis; the area of the substrate then extends along the main direction formed by the axis of arrangement of the light sources.

[0039] According to one example, the light sources are not all aligned, and the main direction in which the area of ​​the substrate on which they are arranged extends is an axis of the plane of the second face of the substrate making it possible to minimize a sum of the distances, preferably a sum of the squares of the distances, of each of the light sources to said axis.

[0040] The electrode holder may include the inlet opening, which is perpendicular to a longitudinal axis of the channel. This allows the inlet opening to be located as close as possible to the hottest point to be cooled in the heat sink.

[0041] According to an example of one of these two embodiments, the outlet opening is located in a longitudinal end of the channel. Rotation or deflection of the airflow at the outlet is thus avoided, which contributes to an optimal airflow in the heat sink, thereby increasing the performance of the device.

[0042] According to an example of one of these two embodiments, said second electrode is parallel to a first fin of the plurality of fins.

[0043] According to an example of one of these two embodiments, the electrode unit comprises one electrode per channel extending in this channel.

[0044] According to an example of one of these two embodiments, the cooling device comprises an inlet opening for all of the channels.

[0045] According to an example of one of these two embodiments, all of the channels open onto at least one outlet opening, in particular two outlet openings.

[0046] According to an example of one of these two embodiments, the second electrode is longitudinal, running along the fins which are longitudinal.

[0047] According to an example of one of these two embodiments, the fins are rectilinear and the second electrode is rectilinear and runs along the fins.

[0048] According to a variant of this example of one of these two embodiments, the fins are curved and the second electrode is curved and runs along the fins.

[0049] According to another variant of these examples, the second electrode is spiral-shaped running along the fins which are spiral-shaped, the inlet opening being in the center of the spiral and the outlet opening at the outer periphery of the cooling device.

[0050] According to one embodiment, the second electrode of the support and the first electrode are at a constant minimum distance from each other. This has the effect of preventing the minimum arc voltage between the electrodes from encountering excessively large differences depending on the position along the electrode. Thus, a higher voltage between the two electrodes can be achieved without generating electric arcs, which damage the electrodes and prevent the establishment of a stable ionic wind.

[0051] According to one embodiment, the electrode unit is mounted on the heat sink. This makes it possible to control a non-variable (fixed) distance between the electrode unit and the heat sink, i.e. to avoid having a variable distance between these two elements when mounting the module. Furthermore, this makes it possible to have a lighting module that can be articulated.

[0052] According to one embodiment, the substrate is an FR4 PCB. This substrate is less expensive than the IMS PCB and the cooling device makes it possible to efficiently cool this type of substrate.

[0053] In another embodiment, the substrate is an IMS PCB. Such a substrate allows for more efficient cooling of light sources with high heat dissipation. In particular, the cooling device is well suited for light sources such as pixelated LEDs, such as monolithic pixelated LEDs, in which the LED comprises an array of light emitting elements grown from the same substrate.

[0054] For example, the electronic circuit of FR4 PCBs can have more than 2 layers, for example 4 layers.

[0055] According to one embodiment, the electrode formed by the electrically conductive heat sink is a negative electrode and the second electrode is a positive electrode. This allows the electronic circuit to be connected to the heat sink because the negative electrode can be used as a ground terminal of the electronic circuit. In addition, this helps prevent arcing. between the heat sink and other components of the lighting module or its environment, or towards a tool or part of a person's body, in particular a tool or part of a user's body introduced into the vehicle enclosure in which the lighting module is mounted. A less advantageous alternative would be to electrically isolate the heat sink, but this generates additional costs and complexity in terms of material, manufacturing process, design and validation, while the effectiveness of such insulation could restrict the air flow and thus harm the heat dissipation efficiency of the assembly. Indeed, it is simpler to electrically isolate the electrode from ground than the heat sink.Thus, the fresh air entrained by the ions moves to the heat sink, where the fresh air is heated by heat transfer with the heat sink, said transfer being favored by the reduction of the boundary layer, and is evacuated through the outlet. Finally, this allows the heat sink to be used as a ground connector to the substrate. This also allows the heat sink and possibly the substrate to be connected and grounded for protection against electrostatic discharge.

[0056] According to an example of this embodiment, the heat sink is connected to a ground terminal of the substrate and the electrode to a positive terminal.

[0057] According to a variant of the previous embodiment, the electrode formed by the electrically conductive heat sink is a positive electrode and the second electrode is a negative electrode.

[0058] According to one embodiment, the air is at atmospheric pressure and either the first or second electrode, called the positive electrode, is electrically powered by a direct voltage with a value between 500 volts and 7000 volts. This provides sufficient power to ensure ionization and prevent the generation of electric arcs.

[0059] According to an example of this embodiment, the value of the voltage at the positive electrode is between 500 volts and 2000 volts. This variation range is simpler to design in the automotive field than a voltage of up to 7000 volts.

[0060] According to one embodiment, the electrode support is made of plastic, such as polycarbonate or thermoplastic.

[0061] According to one embodiment, the lighting module comprises a high voltage control device comprising a positive terminal connected to the second electrode to electrically power it and in which the heat sink forming the negative electrode is connected to a ground terminal of the vehicle.

[0062] According to one example, the high voltage control device comprises an information input of a temperature of an electronic component, the high voltage control device raising or lowering the high supply voltage of the electrode as a function of the value received at the information input of a temperature. Thus a temperature sensor or a temperature estimator, connected to the high voltage control device makes it possible to influence the flow rate of cooling air. For example, the module comprises a temperature sensor on the substrate measuring the temperature of the light source. Preferably, the temperature sensor is mounted on the same face of the substrate as the light source (in the lighting chamber).

[0063] According to an example of this embodiment, the lighting module comprises a lighting control device secured in the housing in the rear chamber, the lighting control device comprising an input connector for electrically connecting to a power supply and an output connector electrically connected to the substrate, for example by a wire harness.

[0064] In the case of the latter two examples above, the lighting control device comprises a second output connector connected to the second substrate to power the high voltage control device.

[0065] According to one embodiment, the first face of the electrically conductive heat sink comprises a planar surface and the substrate is a printed electronic circuit board on which electronic components are mounted, having a face in contact with the planar surface by thermal paste. This allows the heat sink to absorb the thermal energy of the electronic components mounted on the substrate.

[0066] According to a variant of this embodiment, the first face of the electrically conductive heat sink comprises a planar surface and the substrate is a printed circuit board having a surface in physical contact with the planar surface.

[0067] A second aspect of the invention relates to a lighting device comprising: a lighting module according to the first aspect of the invention, which may also have one or more of the preceding characteristics, considered individually, or in all technically possible combinations, a housing defining an interior space and an exterior space, comprising a transparent wall adapted to transmit the light rays emitted by the light sources to the exterior of the housing, the housing supporting the lighting module in the interior space, wherein the cooling device comprises a high voltage control device for powering the positive electrode, the high voltage control device is mounted in the housing.

[0068] By mounting the high-voltage control device of the cooling device in the housing, the installation of the lighting module in the motor vehicle is simplified. The control device therefore delivers a high voltage to the cooling device which it supplies, for example by means of a cable harness, which usually involves unacceptable electromagnetic interference for the components of the headlight and the rest of a motor vehicle in which the headlight is assembled. To avoid such interference, electromagnetic protections are known, for example cable shielding, resulting in additional costs and excess material consumption.However, in the case of a high-voltage control device adapted to power the ionic wind cooling device, the delivered voltage is sufficiently stable so that electromagnetic disturbances are negligible; thus, the control device can be integrated into the housing without additional costs.

[0069] According to one embodiment, the lighting device comprises an articulation device, which may be mechanical or electromechanical, for moving the at least one lighting module which is of high power to perform frontal lighting functions such as a low beam (a lighting beam with a horizontal cut-off) or a high beam (a wide beam), or a pixelated beam with vertical and possibly horizontal lines. The wind cooling device ionic is particularly suitable for such a high-power lighting module dissipating a lot of heat.

[0070] According to one embodiment, the lighting device comprises: several light modules including several lighting modules according to the first aspect of the invention, the high voltage control device being electrically connected to at least one positive electrode of each cooling device of each lighting module to power them.

[0071] Using a single high voltage control device for different cooling devices reduces cost and space requirements.

[0072] According to one embodiment, the lighting device comprises a housing surrounding each of the lighting modules, a transparent wall attached to the housing, and a wall oriented such that air exiting through the outlet of each channel is diverted towards the transparent wall.

[0073] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0074] The figures are presented for information purposes only and in no way limit the invention.

[0075] [Fig. 1] is a schematic diagram of a section of a lighting module according to a first example of a first embodiment of the invention.

[0076] [Fig. 2a] is a side view of a lighting module according to a second embodiment of the invention /

[0077] [Fig. 2b] is a section AA of Figure 2a.

[0078] [Fig. 2c] is a section BB of Figure 2b.

[0079] [Fig. 3] is a side view of a lighting module according to a third embodiment of the invention.

[0080] [Fig. 4] is a side view of a lighting module according to a fourth embodiment of the invention. DETAILED DESCRIPTION

[0081] The figures are presented for information purposes only and in no way limit the invention.

[0082] For clarity, identical or similar elements are indicated by identical reference signs throughout the figures.

[0083] Figure 1 shows a schematic diagram of a section of a lighting module M1 for a motor vehicle according to an example of a first embodiment of the invention.

[0084] In this first embodiment (both examples), the lighting module M1 comprises a substrate 1 comprising an electronic circuit (not shown) and electronic components including at least one light source 2 (here three LEDs) mounted on the electronic substrate 1, connected to the electronic circuit in order to power the light source.

[0085] The electronic components may belong to a source control device I. For example, the light source control device comprises electronic switches or switches of the power circuit of the light sources electrically supplying them. The light source control device may comprise other electronic components outside the lighting module. In other words, the lighting module M1 may comprise all or some of the electronic components electrically mounted on the substrate forming an electronic card. According to an example, the lighting module M1 comprises at least one temperature sensor of the light source 2 belonging to the control device for monitoring and controlling a cooling device 3 explained below.

[0086] In all embodiments of the invention, the light source 2 may participate in the generation, in other examples, of a low beam (a lighting beam with a horizontal cutoff) or a high beam (a wide beam), or a pixelated beam with vertical and possibly horizontal cutoffs. In all embodiments of the invention, the lighting module may be located at the front of the vehicle (mounted in a front light or projector and / or device signaling) or at the rear of the vehicle (mounted in a tail light) or even on the side of the vehicle (for example under the rear-view mirrors).

[0087] In this first embodiment (both examples), the lighting module M1 also comprises the cooling device 3 producing an air flow by ionization of the air. The cooling device 3 uses electro-fluidodynamic fan technology.

[0088] The cooling device 3 comprises an electrically conductive heat sink 30 forming a first electrode of the electro-fluidodynamic fan.

[0089] The electrically conductive heat sink 30, referred to after "heat sink 30", comprises a first face in thermal contact with the substrate 1, in this example by a thermal paste 13, but could be in physical contact directly, i.e., the first face in physical contact with a surface of the substrate 1.

[0090] The heat sink 30 comprises a plurality of fins 300 on a second face opposite the first face. The fins 300 are parallel in this example but may be oriented differently. In this example, each fin 300 is straight and extends longitudinally between a first and a second end, each forming a transverse edge of the fin 300. In this example, there are three fins 300 (two lateral fins and one central fin) and two channels 33 each formed between two fins 300. Each channel 33 comprises a longitudinal axis extending along and between the two fins 300. In the other exemplary embodiments described below, the fins 300 are more numerous. In these examples, there are a number of N-1 channels 33 for a number N of fins. The heat sink 30 may have a number of fins independent of the number of channels. In another example not shown, there are only two fins and one channel 33.

[0091] The heat sink 30 is for example made of aluminum to dissipate heat through the fins. The heat sink 30 comprises a wall comprising the first face and opposite, on the second face, a plurality of channel bottoms 33. Each fin extends transversely between the wall and a longitudinal edge, and longitudinally along the wall, in a first direction.

[0092] The cooling device 3 comprises an electrode unit 31 mounted on the heat sink 30 facing the second face of the heat sink 30 to form with the fins 300 and the lower surface of the wall, each channel 33. In other words, the electrode unit 31 forms a cover of the channels 33.

[0093] Each channel 33 comprises an inlet opening 312 and an outlet opening. Figure 1 schematically represents a section of the lighting module M1 at the inlet opening 312.

[0094] In this embodiment, the inlet opening 312 opens laterally onto the channel 33 (represented by two arrows in FIG. 1 ). In this example, the inlet opening is located between the side fins and the electrode unit 31. The side inlet opening is located longitudinally at one end of the side fin 300 opposite the outlet opening.

[0095] According to another example not shown, each lateral fin comprises a lateral opening (between a transverse edge of a lateral fin and a transverse edge of the central fin) forming an inlet opening or an outlet opening. Of course, each lateral fin may comprise at each end a lateral opening forming an inlet opening and / or an outlet opening.

[0096] According to another example not shown, the inlet opening is a longitudinal opening along the channel 33 (between a longitudinal edge of the corresponding side fin and the electrode unit) and each outlet opening is a side opening which passes through a side fin close to the wall of the heat sink.

[0097] In this embodiment, the outlet opening is a longitudinal opening in the channel at a longitudinal end of the heat sink 30, i.e. between the longitudinal end of the corresponding side fin 300 and the longitudinal end of the central fin. By longitudinal end of a fin is meant the end of the edge of the fin extending in the first direction.

[0098] According to another example, there are two outlet openings opening the channel 33 at two opposite ends (at each longitudinal end of the side fin and the central fin). According to this example, the side inlet opening is located longitudinally between the two ends of the heat sink 30, for example in the middle.

[0099] According to another example not shown, the location of the inlet and outlet opening is reversed (outlet opening between the longitudinal edge and the electrode unit 31 and inlet opening between the longitudinal ends of the central fin and the corresponding lateral fin or according to the previous example, close to the wall of the dissipator 30).

[0100] The electrode unit 31 comprises a dielectric electrode support 310 and at least one electrode 311 supported by the dielectric electrode support 310, hereinafter referred to as "second electrode 311" or "support electrode". In this embodiment, there is only one second electrode 311 supported by the electrode support 310, but the electrode unit 31 may comprise several second longitudinal electrodes 311, for example one second electrode 311 per channel 33 (as in the other embodiments explained hereinafter). The dielectric electrode support 310, hereinafter referred to as "electrode support 310", may be made of plastic such as polycarbonate or thermoplastic.

[0101] The second electrode 311 extends longitudinally along the two channels 33 between the two longitudinal edges of two fins 300. In this embodiment, the second electrode 311 extends laterally between the two lateral fins. The second electrode 311 is spaced from the heat sink 30 and comprises an electrical surface facing each fin 300, forming a space between each fin and the second electrode 311.

[0102] The cooling device 3 comprises a high voltage control device 4 for supplying high voltage to the second electrode 311 or the heat sink 30. In this embodiment, the second electrode 311 is connected to the high voltage output of the high voltage control device 4 and the heat sink 30 forms another electrode connected to ground. The lighting module M1 comprises a lighting control circuit 6 connected to the high voltage control circuit 4 and to the light source 2 for supplying electrical energy from a battery of the vehicle.

[0103] In the example of Figure 1, the high voltage control device 4 is mounted on a support separate from the substrate 1. In Figure 1, there are three connectors, a first connector between the lighting control device 6 and the substrate 1, a second connector between the high voltage control device 4 and the second electrode 311, and a third connector between the high voltage control device 4 and the lighting control device 6.

[0104] When the high voltage is transmitted to the second electrode by the high voltage control device 4, an electroaerodynamic phenomenon of ionic wind occurs. The air between the electrodes, i.e. between the heat sink 30 (fins and wall) and the second electrode 311, is at least partially ionized and the ionized air components move towards the opposite polarized electrode. As shown by the circles in the channel 33 in FIG. 1, ionic particles I move towards the heat sink 30 and thus generate an air flow by displacing the surrounding air components A represented by the other circles. Thus, the cooling device moves the air flow from the inlet opening to the outlet openings by licking the fins 300 and the bottom of the wall.The airflow licking the fins absorbs heat and the hot air exits the cooling device 3 through the outlet opening and dissipates out of the cooling device 3.

[0105] Figure 1 also shows a lighting device comprising a housing 5, for defining an interior space of the device, said space comprising the module M1, and a space external to the device. The housing 5 is fixed, preferably by means of a hinge, to the substrate 1 or to the heat sink 30.

[0106] The housing 5 comprises a transparent wall which is in this case a transparent wall 51 adapted to transmit the light rays emitted by the light sources 2 towards the external space of the housing 5. The transparent wall 51 is located in this case opposite the substrate 1 forming a light chamber between the transparent wall 51 and the first face of the heat sink 1. Of course, the transparent wall 51 can be located in another direction, for example at 90° to the substrate 1, and the housing 5 can comprise reflectors delimiting the light chamber, in a known manner, to reflect the light from the light sources towards the transparent wall 51.

[0107] A lighting module M' of a second embodiment, shown in Figures 2a, 2b, 2c, is described below.

[0108] Figure 2b is a section AA of Figure 2a and Figure 2c is a section BB of Figure 2a. These figures represent an example of a diagram of the principle of the second embodiment.

[0109] The lighting module M' of the second embodiment is identical to the lighting module M1 of the first embodiment, except for the cooling device 3'.

[0110] Each reference including a in these figures corresponds to a different characteristic of the lighting module M1 of the first embodiment.

[0111] The cooling device 3' is different from the cooling device 3, in that the heat sink 30' comprises more than three fins 300, in this example six fins 300 and the electrode support 310' comprises several second longitudinal electrodes 311' and at least one inlet opening 312'. The inlet opening 312' passes through the electrode support 300' in the first direction, i.e. perpendicular to the longitudinal axis of the channel 33.

[0112] In this example, there are four inlet openings 312' for five channels 33, but the cooling device 3' may include fewer or more inlet openings at different locations (e.g., adding the two side inlet openings as in the first embodiment). Each inlet opening 312' includes an open portion in the two neighboring channels 33, i.e., each inlet opening 312' faces the longitudinal edge of the fin 300 corresponding to FIG. 2c. In FIG. 2c, the portions of the longitudinal edge of each fin 300 that do not face an inlet opening 312' are shown by dotted lines to simplify understanding. In particular, each inlet opening 312' is opposite an area of ​​the heat sink 30' corresponding to an area of ​​the substrate 1 connected to the light source 2 (represented by three dotted rectangles in FIG. 2c).

[0113] In another embodiment not shown, there is an inlet opening 312' for a channel 33 and the opening is open only in the corresponding channel 33, for example facing the second electrode 311'.

[0114] In particular, in this example, each inlet opening 312' is located in the longitudinal middle of the channel 33 as visible in Figures 2b and 2c (between the two longitudinal ends of the channel 33). In this example, each inlet opening 312' is more open longitudinally along the longitudinal edge than laterally as shown in Figures 2c.

[0115] The cooling device may comprise a second electrode 311' supported by the support 310, for each channel 33. In other words, the device comprises N second electrodes 31T, in this example five second electrodes 311', which are longitudinal.

[0116] Each second longitudinal electrode 311' extends in the middle of a periphery formed between the two longitudinal edges of the two fins 300. For each second electrode 311', this electrode may be included in the electrode support 310' as long as a portion of this electrode is left exposed. This is for example advantageous when the electrode support is overmolded onto the electrodes.

[0117] Further, in this example, the electrode holder 310' includes a wall surrounding a portion of each side fin 300. Thus, in this example, the electrode holder 310' is mounted on the side fins 300.

[0118] In this example, there are two outlet openings for each channel 33 at the longitudinal end of channel 33, as indicated in Figure 2b by the arrows.

[0119] A lighting module M'" of a fourth embodiment is described in the following. Figure 4 shows an example diagram of the general principle of the fourth embodiment.

[0120] The lighting module M'" of the fourth embodiment is identical to the lighting module M' of the second embodiment, except for the electrode unit 31'".

[0121] The electrode unit 3T" includes a single inlet opening 312'" passing through the electrode holder 310'". The inlet opening 312'" may extend into the longitudinal middle of the cooling device as in the second embodiment.

[0122] In particular, the electrode support 310'" is in contact against the longitudinal edge of the fins 300 making each channel 33 sealed relative to each other.

[0123] The electrode holder 310"' also includes a support wall 3101 '" per second electrode 311. Each support wall 3101 '" extends into the corresponding channel 33 and supports the second electrode 311 '".

[0124] The electrode support 310'" is in contact with each longitudinal edge of the fins 300 (as in the third embodiment).

[0125] Furthermore, in this example of this fourth embodiment, the inlet opening 312'" passes through the electrode support 310'" to be open on each channel 33 and is therefore open opposite also the non-lateral fins 300, that is to say fins delimiting at least two channels. The support wall 3101'" also comprises a portion opposite the inlet opening 312" (of course it extends from the wall of the electrode support 310" to the longitudinal ends to be supported).

[0126] Of course, the housing 5, the high voltage control 4, the light control 6 in the second, third and fourth embodiments can be identical to the examples of the first embodiment and / or be used as a lighting device.

[0127] Unless otherwise specified, the same element appearing in different figures has a single reference.

Claims

CLAIMS

1. Lighting module (M1, M', M", M'") for a motor vehicle comprising: - a substrate (1, 1") comprising an electronic circuit, - a light source (2) mounted on the substrate (1), connected to the electronic circuit in order to power the light source (2), - a cooling device (3, 3', 3", 3'") producing an air flow by ionization of the air comprising: o an electrically conductive heat sink (30, 30') forming a first electrode, comprising: ■ a first face in thermal contact with the substrate (1, 1") and ■ a second face opposite the first face; o an electrode unit (31, 31', 31'") facing the second face of the electrically conductive heat sink (30)), the electrode unit (31) comprising: ■ a dielectric electrode support (310, 310', 310", 310'") ■ at least one second electrode (311, 311', 311'"), supported by the electrode support (310, 310', 310", 310'"), the second electrode (311, 311', 311'") extending along the second face, said second electrode (311, 311', 311'") being spaced from the heat sink (30); - in which: o either the heat sink (30, 30') forming the first electrode is connected to a terminal of positive polarity to form a positive electrode, and the second electrode (311, 311', 311'") is connected to ground to form a negative electrode, o either the second electrode (311, 311', 311'") is connected to a terminal of positive polarity to form a positive electrode, and the heat sink (30, 30') forming the first electrode is connected to ground to form a negative electrode; - so as to produce an air flow movement directed against the dissipator by ionizing the air.

2. Lighting module according to the preceding claim, characterized in that the second face of the electrically conductive heat sink (30, 30') comprises fins (300), said fins (300) forming between them at least one channel (33) along which at least the second electrode (311, 311', 311'") extends.

3. Lighting module (M'") according to the preceding claim, wherein the electrode support (310'") is in contact with a longitudinal edge of the fins (300), wherein the first and second fins each form a longitudinal edge wall of the channel (33) and the electrode support (310') between the first and second fins (300) forms with a surface of the heat sink (30', 30") respectively a cover and a bottom of the channel, wherein the electrical surface of the second electrode (311') runs along the fins (300).

4. Lighting module according to claim 2 or 3, characterized in that the electrode unit (31, 31', 31'") and / or the heat sink (30, 30') forms an inlet opening (312, 312', 312") and / or an outlet opening for respectively supplying fresh air into the at least one channel (33) and expelling hot air from the at least one channel (33), the air flow movement being produced from said inlet opening (312, 312', 312") towards the outlet opening.

5. Lighting module (M 1 , M", M'") according to the preceding claim, wherein the inlet opening of the channel is oriented to face an area of ​​the heat sink (30', 30") corresponding to an area of ​​the substrate connected to the light source so that the flow of fresh air is directed against said area of ​​the substrate.

6. Lighting module (M 1, M", M'") according to claim 4 or 5, wherein the outlet opening is lateral and located in a longitudinal end of the channel (33) and in particular the channel (33) comprises a second outlet opening located at a second longitudinal end of the channel.

7. Lighting module (M1, M', M", M'") according to one of claims 2 to 6, wherein the light sources are mounted on an area of the substrate extending in a main direction in the plane of the second face of the substrate, the channels extend in a direction perpendicular to + / -20 0 to the main management.

8. A lighting module (M1, M', M", M'") according to any preceding claim, wherein the electrode formed by the heat sink (30, 30') is a negative electrode and the second electrode is a positive electrode, and wherein the heat sink (30, 30') is connected to a ground terminal of the substrate (1) and the second electrode to the positive terminal.

9. Lighting module (M1, M', M", M'") according to one of the preceding claims, in which the air is at atmospheric pressure and either the first or the second electrode, called the positive electrode, is electrically powered by a direct voltage of between a value of 500 volts and 7000 volts, in particular between a value of 500 volts and 2000 volts.

10. Lighting module (M 1, M") according to the preceding claim, in which the second electrode (311 ') and the heat sink forming the first electrode are at a minimum distance (G) of 1 to 5 mm.

11. Lighting device comprising: - a lighting module (M1, M', M", M'") according to one of claims 1 to 10, - a housing (5) defining an interior space and an exterior space, comprising a transparent wall (51) adapted to transmit the light rays emitted by the light sources (2) towards the exterior of the housing, the housing supporting the lighting module (M1, M', M", M'") in the interior space, - wherein the cooling device (3) comprises a high voltage control device (4, 4') for supplying the positive electrode, the high voltage control device (4, 4') is mounted in the housing (5).

12. Lighting device according to the preceding claim comprising: - several other lighting modules (M1, M', M", M'") according to one of claims 1 to 10, - the high voltage control device (4, 4') being electrically connected to each positive electrode of each cooling device (3) of each lighting module (M1, M', M", M'") to power them.

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