EP1898144A2 - Lighting device with several LED components and method for its manufacture - Google Patents

Abstract

The motor vehicle lamp, for internal and external illumination, has a number of LEDs (6) directly bonded to a cooling body (2) to take off the heat loss from them. A housing (4) is of a heat-conductive material for at least one LED, held in an opening or recess (3) in the cooling body in a force fit. Each LED is within its own cooling element (7), in contact with the housing.

Description

State of the art

The present invention relates to a lighting unit with a plurality of LED components which are indirectly connected by means of a heat-transmitting intermediate element with a heat sink, via which the heat loss of the LED components can be dissipated. Such lighting units can be used both for purposes of interior lighting and outdoor lighting. In particular, use of these lighting units is also possible in or on motor vehicles. As light-emitting LED components (LED = light emitting diode), optical semiconductor components in the form of light-emitting diodes, in particular light-emitting diode chips (LED chips) can be used. Usually, a plurality of LED components (also referred to below as LEDs) are arranged in an array, the LEDs preferably being surface-mounted SMD (SMD = surface mounted device) by soldering or gluing on a printed circuit board, which is also structured as a circuit carrier can be configured to be mounted.

Not only in motor vehicles, LEDs are increasingly being used because they have some significant advantages over conventional light bulbs. LEDs have a longer life, a smaller size and a better efficiency in the conversion of electrical energy into light. Furthermore, LEDs are characterized by insensitivity to shocks and vibrations, which represents a considerable advantage, especially in motor vehicles.

Despite the lower heat dissipation compared to incandescent lamps, the LEDs must also be used against the backdrop of constantly increasing performance Loss occurring waste heat to be dissipated to prevent overheating and thus functional impairment or even destruction of the LEDs. Usually, the waste heat is dissipated from the underside of the LED components via their electrical connections. In addition to the two electrical connection contacts, the high-brightness LEDs used for a particularly high light output have a third contact, via which the heat loss of the LED is dissipated. This heat connection, which is generally not floating, is soldered to a surface area of the circuit carrier which is configured over the layout of the circuit carrier so that it is not in electrical contact with the rest of the circuit. The waste heat is then removed via an electrical insulating layer in the circuit carrier to a metallic heat sink.

For example, to arrange a plurality of LEDs or a plurality of LED groups in a headlight of a motor vehicle, flexible printed circuit boards are usually equipped with LEDs in a two-dimensional plane, and then the flexible structure thus obtained is glued to a heat sink. The heat sink can, as it is from the DE 199 22 176 A1 is known, for example, made of copper or aluminum, which have the desired application for the desired three-dimensional shape and be provided on the side facing away from the circuit board surfaces with cooling fins. The printed circuit board is preferably attached to the heat sink with a thermal paste, a thermal adhesive, a heat-conducting foil or the like, with an exact alignment of the LED components is difficult and just like the sticking of the circuit board to the heatsink means a considerable assembly effort.

From the DE 10 2004 001 124 B3 is a lamp for a vehicle is known in which a plurality of light-emitting diodes are pressed by means of resilient pressure elements to a heat sink and thus held in place by means of additional components frictionally.

Regardless of optical applications and lighting units are out of the DE 197 57 513 A1 Also Einpressdioden known in cooling plate design, which are received positively in a recess or depression of a cooling plate. such Insertion diodes are used, for example, in welding equipment as a rectifier, where it does not depend on an exact alignment during assembly.

A lighting unit of the type mentioned above is from the DE 195 28 459 C2 known. In this case, a printed circuit board is equipped with a plurality of encapsulated LEDs in a wired version, wherein on the equipped with the LEDs side of the circuit board a bored cooling plate is arranged such that the heads of the LEDs protrude into the holes and the cooling plate and are aligned therein.

Disclosure of the invention

Object of the present invention is to provide an improved lighting unit of the type mentioned above, which is constructed in a particularly effective modular construction method and allows installation of the LED modules, which makes their adjustment as possible no more adjustment required.

This object is achieved by a lighting unit according to claim 1.

The idea underlying the present invention is that at least one housing is provided, which consists of a thermally conductive material and in which at least one LED component is arranged, wherein the housing is positively received in the heat sink.

In this way, a pre-assembled LED module is created, which consists of a separate housing with one or more LED components arranged therein, which are preferably designed as LED chips. The inventive lighting unit according to claim 1 has the advantage over the prior art embodiments that in a relatively simple and robust construction due to the frictional recording of the module housing in the heat sink, a very quick and easy installation is possible, the one to the desired orientation of the LED components necessary adjustment to a minimum or even completely dispensable. Advantageously, the housing of the LED modules are taken directly in the frictional insertion into the heat sink so that the desired focus of the LEDs is virtually automatically obtained in a particularly quick and easy way. At the same time, a fast and particularly effective heat distribution (heat spreader function) is made possible in this way.

Advantageous developments and improvements of the lighting unit according to the invention will become apparent from the dependent claims.

So it is particularly advantageous if the housing is inserted into an opening or a recess of the heat sink, preferably pressed. As a result, a high-precision alignment of the LED module can be achieved. The pressing of the module housing in a complementary recording of the heat sink allows a particularly fast, positive and positive recording and alignment of the LED module.

According to a particularly preferred embodiment of the invention it is provided that the housing includes an LED module which comprises a plurality of LED components, in particular a plurality of light-emitting diode chips. The LED module can be preassembled with any number of LEDs before it is pressed in the manner described above in the heat sink of the lighting unit according to the invention. In this case, arbitrarily shaped outer contours are possible both for the heat sink and for the housing, which can be adapted to the respective requirements of the lighting unit. Advantageously, a plurality of housings of a plurality of LED modules can be pressed into a common overall heat sink, whereby particularly close tolerances of the individual LED modules can be maintained and a complex optical alignment of the LED modules to each other during assembly is no longer required.

It is particularly advantageous if the individual LED components are each arranged in a separate cooling element, wherein the individual cooling elements are each accommodated in the housing in such a way that they are in heat-conducting contact with the housing. The waste heat of the individual LEDs is thereby passed via the individual cooling elements first to the housing of the LED module and from there to the heat sink housing the housing. Preferably, the individual cooling elements can also be positively received in the housing of the LED module be here to also allow a quick and highly effective heat transfer here.

It is also favorable if at least individual cooling elements contain or form optical means, in particular reflectors and / or optical conversion means, for example an optical filling medium for color conversion of the light emitted by the LED.

It is likewise advantageous if optical means are received or fitted in the housing of the LED module. In particular, a plastic optic can be inserted into the housing by means of clip mounting.

In order to achieve a permanently secure interference fit between the housing and the heat sink, it is further proposed that the housing is made of a material which has the same coefficient of thermal expansion as the material of which the heat sink is made. Preferably, the housing can be made of the same material as the heat sink, which can be used for cost reasons, in particular aluminum.

A permanently effective heat transfer can be further ensured by the fact that the outer sides of the housing at least partially have a toothing or knurling, which is pressed into the heat sink.

The subject matter of the present invention is furthermore a headlamp, in particular a motor vehicle headlamp, which comprises a headlamp heat sink in which at least one housing of the type described above is received in a force-fitting manner, preferably pressed in.

The present invention further relates to a method for producing and assembling a lighting unit comprising a plurality of LEDs and a heat sink. Preferably, a headlight for motor vehicles can then be manufactured or mounted. For this purpose, at least one LED component is arranged in a housing made of a thermally conductive material, which is non-positively inserted into the heat sink. In this way, the production can be particularly fast and easy simultaneously high-precision optical alignment of the housing containing the LEDs are performed in the heat sink.

It is particularly advantageous for achieving a highly accurate optical alignment in this method, when the housing is pressed into an opening or in a recess of the heat sink.

According to a particularly preferred embodiment of the manufacturing method according to the invention, it is proposed that a plurality of openings and / or depressions be introduced simultaneously and / or in a single clamping of the heat sink in the heat sink for receiving a plurality of LED modules, which can be advantageously carried out with appropriate machining centers.

Brief description of the drawings

In the drawings, embodiments of the invention are shown, which are explained in more detail in the following description.

Figur 1:

dreidimensionale Darstellung eines Teils einer ersten Ausführungsform eines erfindungsgemäßen Leuchtaggregats;

Figur 2:

Ansicht eines einzelnen, noch nicht eingesetzten LED-Moduls für die Ausführungsform aus Figur 1;

Figur 3:

Schnittdarstellung eines eingesetzten LED-Moduls;

Figur 4:

Ansicht des LED-Moduls aus Figur 2 mit abgenommener Optik;

Figur 5:

dreidimensionale Explosions-Darstellung eines LED-Moduls für eine zweite Ausführungsform eines erfindungsgemäßen Leuchtaggregats;

Figur 6:

Ansicht eines einzelnen LED-Bauelements für das LED-Modul aus Figur 5 in einem eigenen Kühlelement;

Figur 7:

Ansicht des teilmontierten LED-Moduls aus Figur 5;

Figur 8:

Darstellung der Montage von drei LED-Modulen aus Figur 5 in eine zweite Ausführungsform eines erfindungsgemäßen Leuchtaggregats; und

Figur 9:

fertigmontiertes Leuchtaggregat aus Figur 8.

Show it:

FIG. 1:

three-dimensional representation of a part of a first embodiment of a lighting unit according to the invention;

FIG. 2:

View of a single, not yet inserted LED module for the embodiment of Figure 1;

FIG. 3:

Sectional view of an inserted LED module;

FIG. 4:

View of the LED module of Figure 2 with removed optics;

FIG. 5:

three-dimensional exploded view of an LED module for a second embodiment of a lighting unit according to the invention;

FIG. 6:

View of a single LED component for the LED module of Figure 5 in a separate cooling element;

FIG. 7:

View of the partially mounted LED module of Figure 5;

FIG. 8:

Representation of the assembly of three LED modules of Figure 5 in a second embodiment of a lighting unit according to the invention; and

FIG. 9:

Fully assembled lighting unit from FIG. 8.

Embodiments of the invention

In the embodiment of a lighting unit illustrated in FIGS. 1 to 4, five LED modules 1 are pressed into a heat sink 2. For this purpose, the heat sink 2, which simultaneously forms the rear wall of a headlight for a motor vehicle, five recesses 3, in each of which the housing 4 of an LED module 1 is received and held positively and non-positively. The heat sink 2 consists of a substantially flat plate on which are formed to improve the heat dissipation on both sides perpendicularly projecting cooling fins 5. Here, the heat sink 2 as well as the housing 4 of the LED modules 1 is made of aluminum, so that not only a particularly good heat transfer, but also a permanently secure interference fit between the module housings 4 and the overall heat sink 2 is ensured due to the identical thermal expansion coefficient.

In the exemplary embodiment illustrated in FIG. 4, the individual LED modules 1 comprise seven LED components 6, which are each designed here as surface-mounted LED chips. The individual LED chips 6 are each connected via a separate cooling element 7 thermally conductive to the bottom 8 of the module housing 4. On the front side, the LED modules 1 are each terminated by a plastic optics 9 clipped into the housing 4. The thus obtained and shown in Figure 2, preassembled LED modules are then pressed into the recesses 3 of the overall heat sink 2, that on the trough-shaped Metal housing 4 a particularly fast and effective distribution of heat loss to the heat sink 2 is ensured. At the same time an optical alignment of the individual LED modules 1 to each other during assembly is no longer required in the inventive arrangement, since the LED modules 1 are pressed directly into their predetermined position by the recesses 3 positionally accurate alignment in the overall heat sink 2.

In the embodiment variant shown in FIGS. 5 to 9, three LED modules 1 are frictionally received in a total heat sink 2, which also serves to cool a motor vehicle headlight. In this case, the LED modules 1 in three different levels 10 of the heat sink 2 are aligned parallel to each other (Figure 9). The case 4 of the LED modules 1 which is circular in cross-section here, like the heat sink 2, is made of aluminum.

Each LED module 1 comprises in the embodiment shown nine LED chips 6, which are each arranged in a separate cone-shaped cooling element 7. These cooling elements 7 are formed as a frusto-conical cooling base, wherein in the front side base of the truncated cone a likewise frusto-conical recess 11 is introduced, on the bottom 12 of the LED chip 6 is soldered. The inner side region of the cooling base 7 surrounding the LED chip 6 forms a reflector 13, which is preferably mirrored (FIG. 6).
The individual cooling base 7 are then introduced with the soldered LED chips 6 in accordance with conically executed holes 14 in the bottom 8 of the module housing 4, wherein either the cooling base 7 wetted with a thermally conductive adhesive layer 15 or a thermally conductive adhesive before the onset of the cooling base 7 by dispensing is placed in the holes 14.

While the cooling base 7 is made as a cooling element of a single LED chip 6 from a copper blank produced in particular by extrusion, the housing 4 of an LED module 1 is made of aluminum. For this purpose, in this embodiment, first of all a geometrical requirements of the headlight corresponding three-dimensional housing base body is formed by die casting or machining. Subsequently, nine conical holes 14 are machined into the bottom 8 of the module housing 4, wherein the number and arrangement The holes 14 may vary depending on the requirements placed on the headlight. In particular, any orientation of the bores 14 in three-dimensional space are possible with a three-dimensional basic body.

Thereafter, a plug-shaped plastic frame 16 is inserted with injected contacts 17 and exposed bonding surfaces 18 in the module housing 4 and preferably secured by gluing therein. Subsequently, the individual LED components 6 are connected by bonding wires 19 in series with each other and with the two bonding surfaces 18 of the plastic frame 16. After making this electrical connection to the contact pins 17, an optical converting means 20 for converting the blue light emitted from the LED chip 6 into white light is applied to the recesses 11 of the cooling pedestals 7 on the bonded LED chips 6 (FIG. 7). In order to complete the individual LED modules 1, a plastic primary optics 9 is glued to the aluminum housing 4, which has an opening for the passage of the contact pins 17 of the plastic frame 16 in its lower region.

The three LED modules 1 thus produced are then pressed positively and non-positively into the recesses 3 provided in the overall heat sink 2, so that they are located directly in the desired optical alignment and subsequent adjustments are not required. In order to achieve this high-precision alignment of the three LED modules 1 in the heat sink 2, the three recesses 3 have been introduced in a corresponding processing center in only a single clamping. Also, for this purpose, special processing machines with a number of cutting tools corresponding to the desired number of LED modules 1 can be introduced into the heat sink 2 at the same time and thus in a high-precision positional tolerance.

After pressing the LED modules 1 into the heat sink 2, a flexible circuit carrier 21 is applied to the heat sink 2 in a final assembly step and selectively soldered to the contacts 17 of the three LED modules 1 (FIG. 9).

Claims (12)

Illuminating unit with a plurality of LED components (6), which are indirectly connected to a heat sink (2), via which the heat loss of the LED components (6) can be dissipated,
characterized,
in that at least one housing (4) is provided, which consists of a thermally conductive material and in which at least one LED component (6) is arranged, wherein the housing (4) is frictionally received in the heat sink (2). Illuminating unit according to claim 1, characterized in that the housing (4) in an opening or in a recess (3) of the heat sink (2) is inserted, preferably pressed. Illuminating unit according to claim 1 or 2, characterized in that the housing (4) includes an LED module (1) which comprises a plurality of LED components (6), in particular a plurality of light-emitting diode chips. Illuminating unit according to claim 3, characterized in that the individual LED components (6) are each arranged in a separate cooling element (7), wherein the individual cooling elements (7) each with to the housing (4) thermally conductive contact in the housing (4 ) are included. Illuminating unit according to Claim 4, characterized in that at least individual cooling elements (7) contain or form optical means, in particular reflectors (13) and / or optical conversion means (20). Illuminating unit according to one of the preceding claims, characterized in that in the housing (4) optical means, in particular a plastic optics (9), are received or fitted. Illuminating unit according to one of the preceding claims, characterized in that the housing (4) consists of a material which has the same coefficient of thermal expansion as the material of which the heat sink (2) consists. Illuminating unit according to one of the preceding claims, characterized in that the outer sides of the housing (4) at least partially have a toothing or knurling. Illuminating unit according to one of the preceding claims, characterized in that it is designed as a headlight, in particular as a motor vehicle headlamp, which has a headlamp heat sink (2), in which at least one housing (4) positively received, preferably pressed. Method for producing a multi-LED components (6) and a heat sink (2) comprising lighting unit, preferably a headlight for motor vehicles, characterized in that arranged at least one LED component (6) in a housing consisting of a thermally conductive material (4) is, and that the housing (4) non-positively in the heat sink (2) is used. A method according to claim 10, characterized in that the housing (4) in an opening or in a recess (3) of the heat sink (2) is pressed. A method according to claim 11, characterized in that a plurality of openings and / or recesses (3) are introduced simultaneously and / or in a clamping of the heat sink (2) in the heat sink (2).

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