EP2278218B1 - Front headlamp with a cooler device - Google Patents

Description

The present invention relates to a headlamp for a motor vehicle according to the preamble of claim 1, as from the generic document DE 10 2006 037 481 A known.

Such a headlight has a heat source to be cooled and a cooling device, which has a heat sink coupled to the heat source and a fan with a blower housing, which generates an airflow cooling the heat sink.

Such a headlight is supplied by the Applicant as LED (Light Emitting Diode) headlight for the Audi R8 and is therefore known in the market. In this headlight, the LED array represents the heat source.

Semiconductor light sources are currently increasing used in lighting devices of motor vehicles. After the use was initially limited to signal lights such as brake and turn signals, it is currently being begun to use semiconductor light sources for headlight functions, so for lighting the vehicle environment.

Unlike halogen or gas discharge lamps, LEDs emit cold light. The radiation itself thus contains no heat radiation components which would be comparable to the corresponding proportions of a halogen lamp or gas discharge lamp. Nevertheless, even when operating LED losses of about 80% occur. This means that 80% of the electrical energy used for operation is released as heat loss and the LED heat up. This is problematic because important features of LEDs 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 by a predetermined thermal operating point. In particular, the LEDs must be protected against overheating.

Depending on the manufacturer, the maximum permissible chip temperature is between 125 ° C and 185 ° C. Exceeding the respective maximum temperature results in destruction of the LED. Since only about 20% of the electrical energy used is converted into light, headlamp heat losses occur, which can reach values between 20 watts and 40 watts.

In order to reliably dissipate these occurring in the LED chip loss heat outputs without inadmissibly high LED temperatures, cooling concepts are used, in particular the large-area aluminum or copper heat sink of the above provide said type to absorb the heat loss and emit via cooling fins and / or other surface-enlarging structures to the environment.

Often, the cooling requirements are so high that the normal convective cooling is no longer sufficient and with a fan forced cooling must be done by a cooling air flow. In this case, the heat sink is usually arranged in the outlet air flow of the blower wherein the Auslassluftstromquerschnitt is increased by a arranged between the fan and the heat sink diffuser from relatively small Geblääseauslassquerschnitt on a comparatively large Kühlkörperanströmquerschnitt.

In this series connection of blower and heat sink and the optionally still interposed diffuser results in a large length. This is disadvantageous because a large length of curve lighting modules requires a lot of space to pivot the light module. This place is usually scarce. In addition, the space requirement limits the constructive and creative latitude in the headlamp development, which is undesirable.

In addition, results from the great length an undesirably large ratio of internal surfaces of the cooling air leading parts to the volume of these parts, which increases the wall friction caused by flow resistance and thus requires larger and heavier cooling devices to achieve a predetermined cooling effect.

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

This object is achieved with the features of claim 1.

The headlamp according to the invention is characterized in that the heat sink forms a one-piece structural heat sink-blower housing unit with the blower housing.

These features provide a headlamp with a particularly compact, comparatively lightweight and efficient and efficient cooling device through reduced flow resistances.

In a preferred embodiment, the blower is a radial blower or a diagonal blower with an impeller rotatable in the blower housing as a rotor.

Such blowers offer advantages over axial fans, especially for heat sinks with small cross-sections and high air resistance, 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, the heat sink-blower housing unit is adapted to receive the heat source on a parallel to the axis of rotation of the rotor wall of the heat sink stator housing unit.

Since this housing wall deflects the air flow, it acts like a stator blade. The same applies to stator blades for this wall, this deflection effect reduces the thickness of the stationary and therefore insulating boundary layer in the air flow. As a result, particularly small thermal contact resistances are achieved here, which favors the desired cooling effect.

It is therefore also preferred regardless of the arrangement of the heat source, that the heat sink-blower housing unit is designed as a stator. Due to the design as a stator, the housing deflects the air flowing out of the blower wheel through the housing wall and possibly further stator blades in a preferred direction and generates a static pressure. Again, when deflecting the airflow on the stator blades, the stationary, i. insulating boundary layer in the air flow, is very thin, so that particularly small thermal contact resistance can be achieved. Since the stator and heat sink are designed in one component, only comparatively low wall friction losses occur.

Another advantage of the heat sink housing unit is that it offers the opportunity to divide the outlet air flow. In a preferred embodiment, the heat sink-blower housing unit is configured to divide the outlet air flow to a plurality outlet air partial streams. As a result, a plurality of light modules or heat sources can be cooled largely independently of each other.

It is also preferable that the heat sink-blower housing unit has at least one surface-enlarging structure arranged in an outlet airflow of the heat sink-blower housing unit.

This will change the heat transfer from the Heatsink fan housing unit increases on the cooling air flow available surface, which improves the cooling effect.

By at least one arranged in the outlet air flow cooling fin, which is in the cooling air flow, the laminarity and vortex freedom of the cooling air flow is improved. Preferably, the ribs are arranged in the flow direction and thus along the outlet air flow and taper to one or both ends. Ideally, the ribs are rounded at one or both ends. In both cases, the streamlined edge of the ribs should be given greater attention to rejuvenation and rounding. As a result, high volume flows, or high static pressures and thus good heat dissipation can be achieved.

In this case, the inflowed end of the rib can be arranged transversely to a circumference of the rotor or in a plane with a circumference of the rotor.

The invention is generally suitable for cooling heat sources in headlamps. In addition to semiconductor light sources, it is also possible to cool control units and / or output stage arrangements of the headlight which control lighting functions, for example adjusting drives of a cornering light module, a headlight range control or a variable diaphragm arrangement.

It is preferred in each case that the heat source is arranged on an outer wall of the heat sink housing unit, you can therefore feed their dissipated heat by direct thermal contact in serving as a heat sink heat sink fan housing unit, the self is cooled by sweeping on their possibly smooth inner wall without great flow resistance along stroking air.

Further advantages will be apparent from the dependent claims, the description and the attached figures.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

drawings

Fig. 1

eine stark schematisierte Darstellung eines bekannten Frontscheinwerfers;

Fig. 2

einen Querschnitt durch ein Lichtmodul eines Ausführungsbeispiels eines erfindungsgemäßen Frontscheinwerfers;

Fig. 3

ein Spiralgehäuse mit einer ersten Ausgestaltung einer Anordnung von Kühlrippen;

Fig. 4

ein Spiralgehäuse mit einer zweiten Ausgestaltung einer Anordnung von Kühlrippen; und

Fig. 5

einen Querschnitt durch ein Lichtmodul eines weiteren Ausführungsbeispiels eines erfindungsgemäßen Frontscheinwerfers.

Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. In each case, in schematic form:

Fig. 1

a highly schematic representation of a known headlamp;

Fig. 2

a cross section through a light module of an embodiment of a headlight according to the invention;

Fig. 3

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

Fig. 4

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

Fig. 5

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

In detail, the shows FIG. 1 a headlight 10 having a headlight housing 12, a light module 14 arranged in the headlight housing 12 and a cover plate 18 permeable to light 16. The light 16 is generated by a semiconductor light source, which represents an example of a heat source 20 to be cooled.

By means of optical elements 22, the light 16 generated by the semiconductor light source 20 is bundled and optionally additionally influenced in order to achieve a desired light distribution in front of the headlight 10. In the illustrated embodiment, the optical element 22 is 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, in terms of 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 14 is gimballed in the housing 12. For headlamp leveling it can be pivoted about the horizontal axis 24. A pivoting about a vertical axis 26 takes place for the realization of 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 relate to 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 Fig. 1 is shown limited type. The Fig. 1 insofar serves merely to explain an example of a technical environment of the invention.

For the purpose of cooling the heat source 20, the front headlight 10 has a cooling device 30, which has a cooling body 32 thermally coupled to the heat source 20 and a fan 34 with a fan housing 36, which generates a heat sink 32 cooling air flow 38, 40.

The heat sink 32 is usually a finned 42 flow cast or continuous casting heat sink made 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.

In order to dissipate the heat generated by the semiconductor light source as to be cooled heat source 20 at a given cooling air flow 40 and given geometry, the heat sink 32 must have a certain heat capacity and surface. This contributes to the undesirably large space requirement. For cross-sectional adaptation between the comparatively small air outlet cross section of the blower 34 and the relatively large inflowing cross section of the cooling body 32, the cooling device 30 has a diffuser 44. This conventional series arrangement of blower 34, diffuser 44 and heat sink 32 results in an undesirably large length, which is disadvantageous for the realization of Kurvenlichtfunktionen. In addition, the leads Sequential arrangement to losses of flow energy by air friction and turbulence in the fan 34, the diffuser 44 and the heat sink 32nd

The following is with reference to the FIG. 2 an embodiment of the invention explained. It shows the FIG. 2 a light module 46, the object of the FIG. 1 the light module 14 is replaced. In conjunction with the other features of the subject - matter FIG. 1 the light module 46 results in an embodiment of a headlight according to the invention.

In detail, the light module 46 has a semiconductor light source 48 as a heat source 20 to be cooled and a cooling device 50, which has a heat sink coupled to the heat source 20 and a fan with a blower housing, which generates an air flow 40 cooling the heat sink.

In contrast to the subject of FIG. 1 in which heat sink 32 and blower housing 36 are different components, the cooling device 50 of the FIG. 2 characterized in that the heat sink with the fan housing forms an integral structural heat sink fan housing unit 52. In the invention, therefore, a multiple use of the same structure 52 takes place as a fan housing and as a heat sink.

In a preferred embodiment, 20 other components of the light module 46 are attached to the compact and stable structure of the heat sink-blower housing unit 52 in addition to the heat source. At the subject of Fig. 2 These are an optical element 22 in the form of a reflector, a diaphragm 54 and a lens carrier 56, which carries a projection lens 58. Other attachment, Storage or centering can be integrated in the manufacture of the heat sink-blower housing unit 52 in this.

The heat sink-blower housing unit 52 is preferably made of the same material as the heat sink 32 of the FIG. 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 Fig. 1 , which only serves to guide the air and therefore can be made of lightweight plastic, has the heat sink-blower housing unit preferably produced by injection molding 52 weight disadvantages. However, these weight penalties are overcompensated by the weight advantage resulting from the elimination of the separate heat sink 32 from the Fig. 1 results. In sum, one can count on the savings of about one third of the weight of the heat sink 32.

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 fan or a diagonal fan is used with an impeller 60 rotatable in the heat sink fan unit 52 as a rotor or impeller.

In the in the Fig. 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 radially accelerated by blades of the impeller 60. The inner surface 62 of the here designed as a spiral housing heat sink-blower housing unit 52 acts under these circumstances as a stator blade, which deflects the radially accelerated air in the circumferential direction and thus in the drawn direction of the cooling air 40. The Fig. 2 shows in particular a heat sink and blower housing unit 52, which is designed as a stator. It is understood that further stator blades may be disposed between the impeller 60 and the inner surface 62.

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, which provides a small thermal resistance for the transfer of heat from the heat sink-blower housing unit 52 to the cooling air 40. This results in a very intense cooling effect, which ensures that a cooling air flow 40 at the subject of the FIG. 2 absorbs heat better than an equal cooling air flow 40 at the subject of FIG. 1 , This allows the same amount of heat in the subject of FIG. 2 be discharged over a smaller area than the subject of the FIG. 1 ,

This is especially true for the surfaces of the heat sink-blower housing unit 52, in which high air velocities prevail within the heat sink-blower housing unit 52, which, for example, to the parallel to the axis of rotation of the impeller 60 walls of the heat sink-blower housing unit 52, so on the inner surface 62 is the case. A preferred embodiment is therefore characterized in that the heat sink-blower housing unit 52 is adapted to receive the heat source 20 on an outer wall of the heat sink-blower housing unit 52 which is parallel to the axis of rotation.

An embodiment of the stator housing as a spiral housing allows use of a radial fan or a diagonal fan. Spiral housings usually have a relatively large area, which has the advantage of a high heat capacity and a low thermal contact resistance with respect to the heat transfer to the cooling air flow in the complementary use as a heat sink.

In the illustrated embodiment, the cooling air sucked in from the direction of the impeller axis is blown out of the heat sink / blower housing unit 52 in the direction of the projection lens 58. 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 has at least one surface-enlarging structure arranged in an outlet airflow 64 of the heat-sink blower housing unit 52. The increased surface area enhances the cooling of the heat source 20 via the heat sink-blower housing unit 52.

At the subject of Fig. 2 represent in the outlet air flow 40 arranged cooling fins 66, 68, 70 embodiments of such a surface-enlarging structure, wherein in place of three cooling fins 66, 68, 70 also more or fewer fins can be provided.

The cooling fins 66, 68, 70 are preferably arranged along the outlet stream 64 and taper towards at least one of their 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 Fig. 3 shows an embodiment of a heat sink-blower housing unit 52, for a radial fan, in which the inflowed end of the cooling fin 66, 68, 70 is arranged transversely to a circumference of the sake of clarity, there not shown impeller 60.

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

The Figures 3 and 4 clarify beyond the integration of fasteners such as Anschraubdomen 72, holes 74 and projections 76 for holes and centering elements such as webs 78, which serve for example for the correct alignment of a reflector.

The objects of FIGS. 2 to 4 each show heat sink-blower housing units 52 with a single discharge nozzle as the outlet region and thus only a single, possibly by cooling fins 66, 68, 70 divided exhaust air flow 64th

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

This possibility of dividing the outlet air flow into a plurality of outlet air partial flows 80, 82 represents a further advantage of the heat sink fan housing unit 53. As a result, a plurality of light modules or heat sources can be cooled substantially independently of one another. For implementation, the heat sink housing unit 53 has two or more tangential discharge ports 84, 86, via which the cooling air flow can be divided and fed to a plurality of 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.

Additionally, the two or more outlet air substreams 80, 82 are less affected than would be the case using a manifold after a single blower outlet. By dividing the air streams in the heat sink-blower housing unit 53 minimum sizes for the cooling system can be achieved.

The Fig. 5 shows a division of two discharge ports 84, 86 and thus two Auslassluftteilströme 80, 82. This configuration allows the discharged through the second discharge port 86 cooling air 82 cooling a further light module or cooling 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-thrower and / or one associated power amplifier arrangement, this list should not be exhaustive.

About the dimensioning of the outlet cross-sections of the discharge ports 84, 86 and the each pressure port 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 Fig. 5 designated by the numeral 88. The shutter roller 88 replaces the fixed shutter 54 from the Fig. 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)

1. A headlight (10) for a motor vehicle, having at least one heat source (20) to be cooled and one cooling device (50), which cooling device has a heat sink, coupled thermally to the heat source (20), and a fan with a fan housing which generates an air stream (40) that cools the heat sink, characterized in that the heat sink with the fan housing forms a one-piece structural heat sink/fan housing unit (52; 53).
2. The headlight (10) of claim 1, characterized in that the fan is a radial fan or a diagonal fan, with a rotatable fan wheel (60) as a rotor in the fan housing.
3. The headlight (10) of claim 2, characterized in that the heat sink/fan housing unit (52; 53) is arranged so as to receive the heat source (20) on a wall, parallel to the axis of rotation, of the heat sink/fan housing unit (52; 53).
4. The headlight (10) of claim 2 or 3, characterized in that the heat sink/fan housing unit (52; 53) is embodied as a stator.
5. The headlight (10) of one of the foregoing claims, characterized in that the heat sink/fan housing unit is arranged for splitting the outlet air stream (40) into a plurality of partial outlet streams (80, 82).
6. The headlight (10) of one of the foregoing claims, characterized in that the heat sink/fan housing unit (52) has at least one surface-area-increasing structure located in an outlet air stream (40) of the heat sink/fan housing unit (52).
7. The headlight (10) of claim 6, characterized by at least one cooling fin (66, 68, 70) located in the outlet air stream (40).
8. The headlight (10) of claim 7, characterized in that the cooling fin (66, 68, 70) is located along the outlet stream (40), tapers toward at least one of its two ends that are located in the longitudinal direction, and has a rounded fin edge at least on its end facing the oncoming flow.
9. The headlight (10) of claim 6 or 7, characterized in that the end of the fin facing the oncoming flow is located transversely to a circumference of the rotor.
10. The headlight of claim 6 or 7, characterized in that the end, facing the oncoming flow, of the fin (66, 68, 70) is located in the same plane as a circumference of the rotor (60).
11. The headlight (10) of one of the foregoing claims, characterized in that the heat source (20) is a semiconductor light source (48).
12. The headlight (10) of one of the foregoing claims, characterized in that the heat source (20) is located on an outer wall of the heat sink housing unit (52; 53).

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