DE102009033909A1 - Headlamp with a cooling device - Google Patents

Abstract

Front headlight (10) for a motor vehicle, with at least one heat source (20) to be cooled and a cooling device (50) which has a heat sink thermally coupled to the heat source (20) and a blower with a blower housing which has an air flow cooling the heat sink ( 40) generated. The front headlight (10) is distinguished by the fact that the heat sink and the blower housing form an integral structural heat sink / blower housing unit (52; 53).

Description

The The present invention relates to a headlamp for a motor vehicle according to the preamble of claim 1. Such a headlight has a to be cooled Heat source and a cooling device on, which has a thermally coupled to the heat source heat sink and a fan having a fan housing, the one cooling the heat sink Airflow generated.

One Such headlamps are used by the applicant as LED headlights (LED = Light Emitting Diode) for delivered the Audi R8 and is therefore known in the market. In this Front headlight represents the LED array is the heat source.

Semiconductor light sources are currently being used increasingly in lighting fixtures Used motor vehicles. After the use first on Had limited signal lights such as brake and direction indicators, is currently being started, semiconductor light sources also for headlight functions, So for to use a lighting of the vehicle environment.

in the Unlike halogen lamps or gas discharge lamps, LEDs give cold Light off. The radiation itself therefore contains no heat radiation components, with the appropriate proportions of a halogen lamp or gas discharge lamp comparable. Nevertheless, even when operating LED losses of about 80% occur. This means, that 80% of the electrical energy used for operation as heat loss free and heat up the LED. This is problematic because important Properties of LED such as their luminous flux, color, forward voltage and lifetime are highly temperature dependent. The temperature of the Semiconductor light sources must therefore be within narrow, fixed Limits are around a predetermined thermal operating point. It must the LED in particular against overheating protected become.

The maximum permissible Chip temperature is between 125 ° C and 185 ° C depending on the manufacturer. An overrun the respective maximum temperature has a destruction of the LED result. There only about 20% of the electrical energy used is converted into light In headlights, losses in heat output, the values, occur between 20 watts and 40 watts.

Around this occurring in the LED chip loss heat outputs without unduly high LED temperatures reliable lead away to be able to become cooling concepts used, in particular large-area aluminum or copper heatsink the Provide the aforementioned type to absorb the heat loss and cooling fins and / or other surface-enlarging structures to give to the environment.

often are the requirements for cooling so high that the normal convective cooling is no longer sufficient and with a fan a forced cooling through a cooling air flow must be done. The heat sink is in usually arranged in the outlet air flow of the fan wherein the outlet air flow cross section through one between the blower and arranged the heat sink Diffuser from the comparatively small fan outlet cross section to a comparatively large Kühlkörperanströmquerschnitt is enlarged.

at this series connection of blower and heat sink and possibly still interposed diffuser results in a large length. This is disadvantageous because a large overall length For cornering light modules, there is plenty of room for swiveling the light module needed. This place is usually scarce. In addition, the space requirement limits the constructive and creative freedom in headlight development one, which is undesirable is.

Furthermore results from the great length undesirable great relationship inner surfaces the cooling air leading Parts of the volume of these parts, which caused by wall friction flow resistance elevated and thus larger and heavier cooling equipment to achieve a predetermined cooling effect requires.

In front In this background, the object of the invention in the specification a headlight of the type mentioned, in which these disadvantages at least reduced.

These The object is achieved with the features of claim 1.

Of the inventive headlight draws characterized by the fact that the heat sink with the Blower housing one one-piece Structural heat sink-blower housing unit forms.

By these features will be a headlamp with a particularly compact, comparatively light and efficient through reduced flow resistance and powerful cooler provided.

In In a preferred embodiment, the fan is a radial fan or a diagonal fan with one in the fan housing as Rotor rotatable impeller.

Such blowers offer especially for heat sinks with small cross-sections and high Luftwider There are advantages over axial fans, which require flow-optimized heat sinks with large cross-sections because of their low working pressure. In addition, radial fans can be built mechanically more robust compared to axial fans, since the motor and impeller can be mounted on a closed side wall of the fan housing.

In A preferred embodiment is the heat sink-blower housing unit to set up the heat source on a parallel to the axis of rotation of the rotor wall of the heat sink stator housing unit take.

There this housing wall deflects the airflow, it acts like a stator blade. Such as for stator blades applies to this wall, that this deflection effect the thickness of the still and thus reducing insulating boundary layer in the air flow. This will be achieves particularly small thermal contact resistances, what the desired cooling effect favored.

It is therefore independent from the arrangement of the heat source preferred that the heat sink-blower housing unit as a stator is trained. By training as a stator, the housing directs the from the impeller outflowing Air through the housing wall and optionally further stator blades in a preferred direction and creates a static pressure. Again, that applies to the Deflecting the air flow on the stator blades the unmoved, d. H. insulating boundary layer in the air flow, is very thin, so that achieves particularly small thermal contact resistance become. Because stator and heat sink in a component are executed, Only comparatively low wall friction losses occur.

One Another advantage of the heat sink housing unit is that they have the opportunity offers to divide the outlet airflow. In a preferred embodiment is the heat sink-blower housing unit adapted to divide the outlet air flow to a plurality of outlet air substreams. Thereby can several light modules or heat sources largely independent be cooled from each other.

Prefers is also that the heat sink-blower housing unit at least comprising a surface-enlarging structure disposed in an outlet airflow of the heat sink-blower housing unit.

Thereby will the for the transition the heat from the heat sink fan housing unit on the cooling air flow to disposal standing surface enlarged, what the cooling effect improved.

By at least one cooling fin arranged in the outlet airflow, in the cooling air flow stands, becomes the laminarity and vortex freedom of the cooling air flow improved. Preferably, the ribs in the flow direction and thus along the Outlet air flow arranged and tapered to one or both End up. Ideally, the ribs are rounded at one or both ends. In both cases the streamed Edge of the ribs the greater attention in terms of rejuvenation and to dedicate rounding. This allows high volume flows, respectively high static pressures and thus a good heat dissipation be achieved.

there can the streamed End of the rib across a circumference of the rotor or in a plane be arranged with a circumference of the rotor.

The Invention is generally suitable for cooling heat sources in headlamps. In addition to semiconductor light sources can Depending on the design and lighting functions controlling controllers and / or Power stage assemblies of the headlamp are cooled, with which, for example Adjustment drives of a cornering light module, a headlight range adjustment or a variable aperture arrangement.

there is in each case preferred that the heat source on an outer wall the heat sink housing unit Therefore, you can heat their dissipated by direct thermal Contact in as a heat sink serving heatsink fan housing unit Feeding yourself through at their possibly smooth Interior wall without big flow resistance along stroking air chilled becomes.

Further Advantages result from the dependent claims, the Description and attached Characters.

It it is understood that the above and the following yet to be explained features not only in the specified combination, but also in other combinations or alone, without to leave the scope of the present invention.

drawings

embodiments The invention are illustrated in the drawings and in the following description explained. In each case, in schematic form:

1 a highly schematic representation of a known headlamp;

2 a cross section through a Lichtmo dul of an embodiment of a headlight according to the invention;

3 a volute casing having a first configuration of an arrangement of cooling fins;

4 a volute casing having a second configuration of an arrangement of cooling fins; and

5 a cross section through a light module of another embodiment of a headlight according to the invention.

In detail, the shows 1 a headlight 10 with a spotlight housing 12 , one in the headlight housing 12 arranged light module fourteen and one for light 16 permeable cover 18 , The light 16 is generated by a semiconductor light source, which is an example of a heat source to be cooled 20 represents.

By optical elements 22 becomes that of the semiconductor light source 20 generated light 16 bundled and possibly additionally influenced to a desired light distribution in front of the headlight 10 to achieve. In the illustrated embodiment, the optical element 22 a reflector. Alternatively or additionally, aperture arrangements and / or lenses can be used as optical elements to realize reflection systems or projection systems and / or to produce different light distributions. The different light distributions differ, for example, as to whether or not they have a defined light-dark boundary and, if appropriate, how such a light-dark boundary is configured.

In the illustrated embodiment, the light module fourteen Cardan in the housing 12 suspended. For headlamp leveling it can be about the horizontal axis 24 be panned. A tilt about a vertical axis 26 takes place to realize a cornering light function. These lighting functions and the configurations of optical elements, part-turn actuators and control elements required for their achievement are familiar to the person skilled in the art and therefore do not require further explanation at this point.

The invention does not concern these lighting functions but rather the cooling of the heat source 20 of the headlight 10 , in particular the cooling of a semiconductor light source. It is therefore to be understood that the invention is not limited to headlamps in the 1 is shown limited type. The 1 insofar serves merely to explain an example of a technical environment of the invention.

For the purpose of cooling the heat source 20 has the headlight 10 a cooling device 30 on, the one with the heat source 20 thermally coupled heat sink 32 as well as a blower 34 with a blower housing 36 that has the heat sink 32 cooling airflow 38 . 40 generated.

At the heat sink 32 it is usually one with ribs 42 provided flow cast or continuous casting heat sink of a material having a good thermal conductivity. Typical representatives of such materials are aluminum, magnesium and copper as well as alloys based on these metals.

Around the heat source to be cooled by the semiconductor light source 20 generated heat at a given cooling air flow 40 and dissipate given geometry, the heat sink must 32 have a certain heat capacity and surface. This contributes to the undesirably large space requirement. For cross-section adaptation between the comparatively small air outlet cross section of the blower 34 and the relatively large incoming cross-section of the heat sink 32 has the cooling device 30 a diffuser 44 on.

This conventional sequential arrangement of blowers 34 , Diffuser 44 and heat sink 32 results in an undesirably large length, which is disadvantageous for the realization of Kurvenlichtfunktionen. In addition, the series arrangement leads to losses of flow energy due to air friction and turbulence in the fan 34 , the diffuser 44 and the heat sink 32 ,

The following is with reference to the 2 an embodiment of the invention explained. It shows the 2 a light module 46 that is the subject of the 1 the light module fourteen replaced. In conjunction with the other features of the subject - matter 1 gives the light module 46 An embodiment of a headlight according to the invention.

In detail, the light module points 46 a semiconductor light source 48 as a heat source to be cooled 20 and a cooling device 50 put on a thermally with the heat source 20 coupled cooling body and a fan having a fan housing having a cooling body cooling the air flow 40 generated.

In contrast to the subject of 1 , at the heat sink 32 and blower housing 36 are different components, is characterized the cooling device 50 of the 2 characterized in that the heat sink with the fan housing a one-piece structural heat sink fan housing unit 52 forms. Accordingly, in the invention, multiple use of the same structure takes place 52 as fan housing and as a heat sink instead.

In a preferred embodiment, in addition to the heat source 20 other components of the light module 46 on the compact and stable structure of the heat sink-blower housing unit 52 attached. At the subject of 2 These are an optical element 22 in the form of a reflector, a screen 54 and a lens wearer 56 , which is a projection lens 58 wearing. Other mounting, storage or centering elements may be used in the manufacture of the heat sink-blower housing unit 52 be integrated into this.

The heat sink fan housing unit 52 is preferably made of the same material as the heat sink 32 from the 1 made of aluminum, magnesium, copper or an alloy containing at least one of these materials. In particular, injection molding methods are considered as suitable production methods.

Compared to the blower housing 36 from the 1 , which only serves the air guide and therefore can be made of lightweight plastic, has the heat sink-blower housing unit preferably made of metal injection molding 52 Weight disadvantages on. However, these weight penalties are overcompensated by the weight advantage resulting from the elimination of the separate heat sink 32 from the 1 results. In sum, one can save about one third of the weight of the heatsink 32 expected.

The present invention is not limited to a particular type of blower and, in principle, can be operated with any device that converts mechanical energy into moving air flow energy. In a preferred embodiment, however, a radial blower or a diagonal blower with a in the heatsink fan blower unit 52 as a rotor or impeller rotatable impeller 60 used.

In the in the 2 Fan shown is such a radial fan in which the cooling air is sucked perpendicular to the drawing plane from the environment. The air is initially in a central region of the rotatable as a rotor and acting as an impeller impeller 60 sucked and by blades of the impeller 60 radially accelerated. The inner surface 62 the designed here as a spiral housing heat sink-blower housing unit 52 acts under these circumstances as a stator blade, which the radially accelerated air in the circumferential direction and thus in the drawn direction of the cooling air 40 deflects. The 2 shows thus in particular a heat sink-blower housing unit 52 , which is designed as a stator. It is understood that more stator blades between the impeller 60 and the inner surface 62 can be arranged.

The described deflection of the air results in a high tangential air velocity and a very low density of the air boundary layer on the inner surface 62 what a small thermal resistance for the transfer of heat from the heat sink-blower housing unit 52 on the cooling air 40 provides. This results in a very intense cooling effect, which ensures that a cooling air flow 40 at the subject of 2 absorbs heat better than an equal cooling air flow 40 at the subject of 1 , This allows the same amount of heat in the subject of 2 be discharged over a smaller area than the subject of the 1 ,

This applies in particular to the surfaces of the heat sink-blower housing unit 52 at which inside of the heat sink fan housing unit 52 high air velocities prevail, which, for example, to the axis of rotation of the impeller 60 parallel walls of the heat sink-blower housing unit 52 So on the inside surface 62 the case is. A preferred embodiment is therefore characterized in that the heat sink-blower housing unit 52 to set up the heat source 20 on an outer wall, parallel to the axis of rotation, of the heat sink / blower housing unit 52 take.

A execution of the stator housing as a spiral housing allows a use of a radial fan or a diagonal blower. volute As a rule, they have a comparatively large area, which is complementary Use as a heat sink Advantage of a high heat capacity and a low thermal contact resistance in terms of heat transfer on the cooling air flow Has.

The cooling air sucked in from the direction of the impeller axis is in the illustrated embodiment in the direction of the projection lens 58 from the heat sink fan housing unit 52 blown out. This provides the additional advantage that the heated cooling air moisture, which can condense with changing temperatures and / or humidities in the headlight, absorbs and carries out with the air flow from the headlight.

In one embodiment, the heat sink-blower housing unit 52 at least one in an outlet airflow 64 the heat sink-blower housing unit 52 arranged surface-enlarging structure. Due to the enlarged surface, the over the heat sink-blower housing unit 52 Successful heat dissipation source 20 strengthened.

At the subject of 2 set in the outlet airflow 40 arranged cooling fins 66 . 68 . 70 Embodiments of such a surface-enlarging structure, wherein instead of three cooling fins 66 . 68 . 70 also more or less ribs can be provided.

The cooling fins 66 . 68 . 70 are preferred along the outlet flow 64 arranged and tapered towards at least one of its two longitudinal ends. When pictured, they rejuvenate towards both ends. In addition, they should have at least at their end streamlined a rounded rib edge.

The 3 shows an embodiment of a heat sink-blower housing unit 52 , for a radial fan, at which the end of the cooling fin 66 . 68 . 70 each transverse to a circumference of the sake of clarity there not shown impeller 60 is arranged.

The 4 shows an alternative embodiment, in which the flowed end of the rib 66 . 68 . 70 each in a plane with a perimeter of the impeller 60 is arranged.

The 3 and 4 also illustrate the integration of fasteners such as screw-on domes 72 , Drilling 74 and protrusions 76 for drilling as well as centering elements such as bars 78 , which serve for example for the correct orientation of a reflector.

The objects of 2 to 4 show each heat sink fan housing units 52 with a single discharge nozzle as outlet and thus only a single, possibly by cooling fins 66 . 68 . 70 divided outlet airflow 64 ,

In contrast, the 5 an alternative embodiment, wherein a heat sink-blower housing unit 53 is adapted to the outlet air flow to a plurality outlet air partial streams 80 . 82 divide.

This possibility of dividing the outlet air flow to several outlet air partial flows 80 . 82 represents another advantage of the heat sink-blower housing unit 53 As a result, a plurality of light modules or heat sources can be cooled largely independently of each other. To realize owns the heat sink housing unit 53 two or more tangential discharge ports 84 . 86 , via which the cooling air flow can be divided and fed to several different heat sources. In contrast to a distribution of the volumetric flow downstream of the discharge port / outlet area (Y-manifolds), this division offers the most compact design option.

In addition, the two or more outlet air substreams influence each other 80 . 82 less than would be the case using a manifold branching behind a single blower outlet. By dividing the air flows in the heat sink-blower housing unit 53 minimum sizes for the cooling system can be achieved.

The 5 shows a division into two discharge nozzles 84 . 86 and thus on two outlet air streams 80 . 82 , This embodiment allows with the through the second discharge port 86 discharged cooling air 82 a cooling of another light module or a cooling of another heat source in the headlight. The further heat source is, for example, a further semiconductor light source and / or a control device controlling the light functions of the pig projector and / or an associated output stage arrangement, this list not being intended to be exhaustive.

About the dimensioning of the outlet cross sections of the discharge nozzles 84 . 86 and the each discharge nozzle 84 . 86 operatively associated length of the spiral sections, the distribution of air quantities is structurally influenced.

An arrangement of adjustable aperture in the form of a diaphragm roller is in the 5 with the numeral 88 designated. The iris roller 88 replaces the fixed bezel 54 from the 2 and illustrates that the invention is not limited to use in a particular headlamp but is applicable to a variety of different headlamps having one or more heat sources to be cooled, such as semiconductor light sources and / or controllers and / or power stage assemblies.

Claims (12)

Headlight ( 10 ) for a motor vehicle, with at least one heat source to be cooled ( 20 ) and a cooling device ( 50 ), which thermally with the heat source ( 20 ) coupled to a cooling fan and a blower with a fan housing, which has a heat sink cooling the air stream ( 40 ), characterized in that the heat sink with the fan housing a one-piece structural heat sink fan housing unit ( 52 ; 53 ). Headlight ( 10 ) according to claim 1, characterized in that the fan is a radial fan or a diagonal fan with a in the Blower housing as rotor rotatable impeller ( 60 ). Headlight ( 10 ) according to claim 2, characterized in that the heat sink-blower housing unit ( 52 ; 53 ) is adapted to the heat source ( 20 ) on a wall parallel to the axis of rotation of the heat sink-blower housing unit ( 52 ; 53 ). Headlight ( 10 ) according to claim 2 or 3, characterized in that the heat sink-blower housing unit ( 52 ; 53 ) is designed as a stator. Headlight ( 10 ) according to one of the preceding claims, characterized in that it is adapted to the outlet air flow ( 40 ) to a plurality of outlet air substreams ( 80 . 82 ). Headlight ( 10 ) according to one of the preceding claims, characterized in that the heat sink and blower housing unit ( 52 ) at least one in an outlet air stream ( 40 ) of the heat sink-blower housing unit ( 52 ) has arranged surface-enlarging structure. Headlight ( 10 ) according to claim 6, characterized by at least one in the outlet air flow ( 40 ) arranged cooling rib ( 66 . 68 . 70 ), Headlight ( 10 ) according to claim 7, characterized in that the cooling rib ( 66 . 68 . 70 ) along the outlet stream ( 40 ) is arranged, at least one of its two longitudinally tapered ends tapers and at least at its upstream end has a rounded rib edge. Headlight ( 10 ) according to claim 6 or 7, characterized in that the flowed end of the rib is arranged transversely to a circumference of the rotor. Front headlamp according to claim 6 or 7, characterized in that the flowed end of the rib ( 66 . 68 . 70 ) in a plane with a circumference of the rotor ( 60 ) is arranged. Headlight ( 10 ) according to one of the preceding claims, characterized in that the heat source ( 20 ) a semiconductor light source ( 48 ). Headlight ( 10 ) according to one of the preceding claims, characterized in that the heat source ( 20 ) on an outer wall of the heat sink housing unit ( 52 ; 53 ) is arranged.

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