WO2020174140A1

WO2020174140A1 - Luminous lighting device for motor vehicle equipped with a reflector provided with cooling fins

Info

Publication number: WO2020174140A1
Application number: PCT/FR2020/050188
Authority: WO
Inventors: Rodolphe Peron
Original assignee: Psa Automobiles Sa
Priority date: 2019-02-26
Filing date: 2020-02-05
Publication date: 2020-09-03
Also published as: FR3093161A1; FR3093161B1

Abstract

The invention relates to a luminous lighting device for motor vehicle including a high-power light-emitting diode (323) installed on a printed circuit board (324) mounted on a support (322), and a reflector (321) including a wall (321A), one of the faces of which is covered with a reflective coating capable of redirecting the light rays emitted by said diode (323) in the direction of a space to be illuminated; characterized in that said wall (321A) comprises a series of cooling fins (321C) extending from its face opposite said cooling face.

Description

DESCRIPTION

Title of the invention: Luminous lighting device for a motor vehicle fitted with a reflector fitted with cooling fins

Technical area

The present invention relates generally to the field of optical lighting and signaling units for motor vehicles. It relates in particular to a luminous lighting device housed in such an optical unit.

Prior art

International regulations require motor vehicles to be fitted at the front and rear with optical lighting and signaling units in order, on the one hand, to illuminate the road to improve the visibility of the driver of the vehicle, especially at night, and, on the other hand, to signal the position of the vehicle to other road users.

Such an optical unit conventionally comprises at least one housing intended to be fixed to the structure of the vehicle and on which is mounted, directly or by means of a dedicated support, at least one light device capable of performing a photometric function of lighting such as for example a high beam, a low beam (also referred to as a code), or a position light (also known as a night light or a lantern), or a photometric signaling function such as for example a reversing light, a STOP light , a direction change indicator light or even a daytime running light commonly referred to by the English acronym DRL (Daytime Running Light) and which comes on automatically when the vehicle is moving forward in order to increase its visibility in daylight conditions.

Each light device conventionally comprises at least one light source conventionally constituted by a halogen incandescent bulb, and being generally associated with a reflector capable of reflect the light rays reaching it in the direction of a space to be illuminated.

For questions of lower electrical energy consumption, increased lifespan and freedom of style, it is now common to use LEDs (for "Light Emitting Diodes" in English translating into French by diodes. electroluminescent) as an alternative to conventional incandescent bulbs, in particular to perform the low beam and high beam functions.

Installed on printed circuit boards commonly known by the English acronym PCB (for “Printed Circuit Board”), such light-emitting diodes have the advantage of consuming relatively little and being able to emit a very white light, the color temperature of which is close to that of daylight.

However, LEDs have the drawback of generating a large amount of heat in their area of implantation on the PCB, which leads to a significant degradation of their light output (their brightness decreasing for example by about 30% when the temperature prevails. around them goes from 25 ° C to 120 ° C).

In order to remove the heat generated by these diodes, it is known in particular from patent application FR 3 056 483 to provide, on the supports carrying the PCBs on which the latter are located, heat sinks comprising a plurality of fins. through which the heat emitted by the LEDs is propagated by conduction and which thus make it possible to optimize the heat exchange surface with the ambient air which heats up.

Moreover, when the high beam function is provided by a single power LED, the light intensity of the rays emitted by this diode and reflected by the reflector being associated with it causes localized heating of certain areas of this reflector, this heating being able to cause slight degradation and / or deformation of the surface of this reflector altering the resulting output beam.

Disclosure of the invention The present invention therefore aims to limit the heating of the reflector associated with such a power light-emitting diode.

For this purpose, it proposes a luminous lighting device for a motor vehicle comprising a power light-emitting diode implanted on a printed circuit board mounted on a support, as well as a reflector comprising a wall, one of the faces of which is covered with a reflective coating capable of reflecting the light rays emitted by said diode towards a space to be illuminated; characterized in that said wall comprises a series of cooling fins extending from its face opposite to said reflecting face.

The presence of these fins limits the heating of the reflecting wall of the reflector by improving the dissipation of the heat absorbed thanks to the increase in the heat exchange surface with the ambient air. The invention thus makes it possible to avoid the appearance of localized deformations at the level of this reflecting wall so as to preserve its initial geometry.

According to preferred characteristics of said luminous lighting device according to the invention:

the longitudinal depth of said fins varies as a function of their implantation zones on said wall;

said fins have a two by two spacing varying according to their zones of implantation on said wall;

said fins extend substantially horizontally, transversely encircling said wall over the whole of its width; said fins have a thickness of between 1.5 and 2.5 mm;

said fins have a depth of between 5 and 25 mm;

said fins have a spacing two by two of between 8 and 25 mm;

said reflector is molded from a thermosetting polymer resin reinforced with natural and / or synthetic fibers; and or

said polymer resin is an unsaturated polyester. The invention also relates in a second aspect to an optical lighting and signaling unit for a motor vehicle comprising a housing, an optical module comprising at least one such lighting device, and an external transparent cover glass mounted on the periphery. of said housing.

Brief description of the drawings

The description of the invention will now be continued with the detailed description of an exemplary embodiment, given below by way of illustration but not limitation, with reference to the appended drawings, in which:

[Fig 1] is a perspective view of an optical lighting and signaling unit according to the invention;

[Fig 2] shows a sectional view along a vertical longitudinal plane of the optical unit of Figure 1;

[Fig 3] is a three quarter front perspective view of the optical module that comprises the optical unit of Figure 1;

[Fig 4] is a three quarter rear perspective view of the optical module of Figure 3; and

[Fig 5] is an enlargement of the rear part of the reflector of the central lighting device of the optical unit of Fig. 3.

detailed description

One defines in Figures 1 and 2 an orthogonal reference XYZ comprising three perpendicular axes two by two, namely:

an axis X, defining a longitudinal direction, parallel to the longitudinal axis of the vehicle,

a Y axis, defining a transverse, horizontal direction, which together with the X axis defines a horizontal XY plane, and

a Z axis, defining a vertical direction, perpendicular to the horizontal XY plane.

In the following description and by convention, the terms “front”, “rear”, “lower” and “upper” will be defined with respect to the mounting position of this optical signal unit 1 on such a motor vehicle.

Furthermore, the use of the term “substantially” will indicate that a slight deviation is allowed from a predetermined nominal position or arrangement, while remaining included within the scope of the invention. For example, “substantially vertical” indicates that a deviation of the order of 10 ° from a strictly vertical orientation is allowed within the framework of the invention.

Figures 1 and 2 show two views respectively in perspective and in section along a longitudinal vertical plane of a front optical unit for lighting and signaling 1 intended to be mounted on the body structure of a motor vehicle.

As illustrated in these figures, the optical unit 1 comprises a housing 10 having a front opening covered by a transparent cover glass 20, mounted in a sealed manner on the periphery of this housing 10.

The optical unit 1 also comprises two optical lighting 30 and signaling modules 40 housed one above the other in the cavity defined by the housing 10 and the cover glass 20, as well as a mask 50 also housed in this cavity and making it possible to conceal certain portions of the housing 10 and of the optical modules 30, 40 from the sight of an observer looking inside this unit through this glass 20. Intended to be fixed to the body structure of the vehicle, the housing 10 is preferably made in one piece from a thermoplastic polymer such as, for example, an acrylonitrile butadiene styrene (ABS).

The cover glass 20 is preferably produced as a one-piece molding from a transparent thermoplastic polymer such as polycarbonate or poly-methyl methacrylate (PMMA). It is attached to the housing 10 by means of a peripheral ice foot 21 inserted into a corresponding peripheral gluing groove 11 provided on the housing 10. A bonding and sealing gasket, not shown, is interposed and compressed between the peripheral ice foot 21 and the bottom of the peripheral gluing groove 11 on the whole of its perimeter. This seal makes it possible both to effectively secure the lens 20 to the housing 10, and to ensure excellent sealing over the entire periphery of the optical unit 1.

The optical signaling module 40, the design of which is illustrated here only by way of non-limiting example, consists of a single luminous device providing the direction change indicator light function.

The light device 40 comprises a reflector 42 fixed to the housing 10 as well as a light source consisting of an incandescent halogen bulb 43 of the P21W type, mounted at the rear of the housing 10 via a mounting socket 44 inserted. through an opening made at the rear of this reflector 42.

Coming advantageously from molding from a thermoplastic material such as polymethyl methacrylate (PMMA) or polycarbonate (PC), the reflector 42 comprises a parabolic or elliptical wall, the front outer face of which is oriented in the direction of the cover glass 20. is covered with a reflective metallic coating. Shown alone in FIGS. 3 and 4, the optical lighting module 30 comprises three adjacent lighting devices 31, 32 and 33 substantially aligned transversely.

Of identical general design, the two side lighting devices 31 and 33 are designed to perform the low beam function, while the central lighting device 32 provides the high beam function.

Each of the side lighting devices 31, 33 comprises a plastic reflector 311, 331 rigidly linked to the housing 10, a metal support 312, 332 fixed to the upper part of this reflector 311, 331, a light-emitting diode (not visible in the figures and constituted for example by a white multi-chip LED emitting a luminous flux of approximately 600 Im) installed on a printed circuit board of the PCB (for “Printed Circuit Board” in English language) mounted on the support 312, 332 and not visible in the figures.

Each reflector 311, 331 comprises a parabolic main wall 311A, 331A, the front outer face of which is oriented towards the mirror. cover 20 is covered with a reflective metallized coating capable of reflecting the light rays emitted by the diode towards a space to be illuminated, as well as a skirt 311 B, 331B extending longitudinally forward from the edges side and bottom of the parabolic main wall 311A, 331A and the outer faces of which are striated or grained in order to burst the light rays reaching them so as to avoid the generation of parasitic reflected rays in undesired and potentially annoying directions.

Each of the supports 312, 332 is in the form of a square composed of a first horizontal wall 312A, 332A overhanging the reflector 311, 331 and carrying the PCB, as well as a rear wall 312B, 332B connected to the rear edge of this horizontal wall and extending behind the reflector in a vertical transverse plane.

As illustrated in FIG. 4, this rear wall 312B, 332B has two lateral flanges 312C, 332C folded back towards the rear and forming fins increasing the exchange surface with the air contained in the rear part of the cavity of the optical unit. 1.

Similar in design to the two lateral lighting devices 31, 33, the central lighting device 32 comprises a plastic reflector 321 rigidly linked to the housing 10, a metal support 322 fixed to the upper part of this reflector 321, a light-emitting diode 323 (visible in FIG. 2 and constituted for example by a white multi-chip power LED emitting a luminous flux of about 1000 Im) implanted on a printed circuit board 324 of the PCB type mounted on the support 322.

The reflector 321 comprises a parabolic main wall 321A, the front outer face of which oriented in the direction of the cover glass 20 is covered with a reflective metallized coating capable of reflecting the light rays emitted by the diode 323 in the direction of a space to illuminate, as well as two side walls 321B (only one of them being visible in FIG. 3) extending in parallel vertical longitudinal planes from the two side edges of the main wall 321A and whose outer faces are facing one of the other are striated or grained in order to burst the light rays reaching them so as to avoid the generation of parasitic reflected rays.

Structurally similar to supports 312 and 332 but larger in size, support 322 is also in the form of a bracket composed of a first horizontal wall 322A overhanging reflector 321 and carrying PCB 324, as well as a wall rear 322B connected to the rear edge of this horizontal wall and extending behind the reflector 321 in a vertical transverse plane. This rear wall 322B has two side edges 322C folded backwards and forming fins increasing the exchange surface with the air contained in the rear part of the cavity of the optical unit 1.

Each support 312, 322, 332 is advantageously obtained by cutting and folding from a sheet of metal made of a metal having high thermal conductivity (typically aluminum or an aluminum alloy, or even copper or a copper alloy), so as to ensure rapid and efficient evacuation of the heat emitted by the corresponding light-emitting diode towards the rear part of the cavity of the optical unit 1.

In order to better dissipate the heat generated by the higher power light-emitting diode 323 and maintain the latter at a relatively low operating temperature (around 25 ° C to 30 ° C) where it has good energy efficiency, the light device central 32 also comprises a heat sink 325 fitted against the rear face of the rear wall 322B of the support 322 and comprising a plurality of fins extending substantially parallel to each other in vertical longitudinal planes.

This dissipator is advantageously obtained from a sheet of sheet metal folded into an accordion and also made of a metal having high thermal conductivity (typically aluminum or an aluminum alloy, or even copper or a copper alloy) . As illustrated in Figures 3 to 5, the three reflectors 311, 321 and 331 are molded in one piece, from a thermosetting polymer resin reinforced with natural and / or synthetic fibers (such as in particular the BMC acronym of the English expression "Bulk Molding Compound ”and consisting of an unsaturated polyester resin filled with glass fibers), so as to have good mechanical resistance to heating caused by the absorption of these reflectors of part of the energy of the light rays hitting them. .

In order to limit the rise in temperature of the central reflector 321, its reflective main wall 321A further comprises a series of cooling fins 321C extending, substantially horizontally and parallel to the longitudinal main axis of the outgoing reflected light flux, from its rear inner face opposite the reflective front outer face, so as to increase the heat exchange surface with the ambient air.

Also participating in the reinforcement of the mechanical strength of the reflector 321, these fins 321C, the thickness of which is advantageously between 1.5 and 2.5 mm, transversely surround the reflecting wall 321A over its entire width.

As is clearly visible in Figure 2, the longitudinal depth (preferably between 5 and 25 mm) of these fins 321A and their spacing two by two (preferably between 8 and 25 mm) vary depending on their areas of 'implantation on the reflective wall 321A of the reflector 321.

Thus, the fins 321C located in the lower part of this reflector 321 struck by the majority of the light rays emitted by the diode (and therefore absorbing the most heat) are clearly deeper and have a smaller spacing than those located in the upper part of the diode. this same reflector, so as to obtain a significantly greater heat exchange surface and therefore greater heat dissipation in this lower part.

According to variant embodiments not shown, the fins 321C of the reflector 321 are oriented differently, the latter being able for example to extend along vertical longitudinal planes (such an arrangement having, however, the drawback of complicating the demolding operations).

According to other variant embodiments not shown, all the reflectors are provided with cooling fins such as 321C. In general, it is recalled that the present invention is not limited to the embodiments described and shown, but encompasses any variant execution within the reach of a person skilled in the art.

Claims

1. Luminous lighting device for a motor vehicle comprising a power light-emitting diode (323) implanted on a printed circuit board (324) mounted on a support (322), as well as a reflector (321) comprising a wall (321A) ) one of the faces of which is covered with a reflective coating suitable for reflecting the light rays emitted by said diode (323) towards a space to be illuminated; characterized in that said wall (321A) comprises a series of cooling fins (321C) extending from its face opposite to said reflecting face.

2. A luminous lighting device according to claim 1, characterized in that the longitudinal depth of said fins (321C) varies as a function of their implantation zones on said wall.

3. A luminous lighting device according to one of claims 1 or

2, characterized in that said fins (321C) have a two by two spacing varying according to their zones of implantation on said wall.

4. Illuminated lighting device according to one of claims 1 to

3, characterized in that said fins (321C) extend substantially horizontally, transversely surrounding said wall (321A) over the whole of its width.

5. Illuminated lighting device according to one of claims 1 to

4, characterized in that said fins (321C) have a thickness of between 1.5 and 2.5 mm.

6. A luminous lighting device according to one of claims 1 to

5, characterized in that said fins (321C) have a depth of between 5 and 25 mm.

7. Illuminated lighting device according to one of claims 1 to

6, characterized in that said fins (321C) have a two-by-two spacing of between 8 and 25 mm.

8. A luminous lighting device according to one of claims 1 to 7, characterized in that said reflector (321) is molded from a thermosetting polymer resin reinforced with natural and / or synthetic fibers.

9. A lighting device according to claim 8, characterized in that said polymer resin is an unsaturated polyester.

10. Optical lighting and signaling unit for a motor vehicle comprising a housing (10), an optical module (30) comprising at least one luminous lighting device (32), and an external transparent cover glass (20) mounted. on the periphery of said housing (10); characterized in that the at least said luminous lighting device (32) conforms to one of claims 1 to 9.