DE102011120123A1 - LED-headlight i.e. front headlight, for use in motor car, has light source arranged on printed circuit board that is arranged in housing, where areas of cooling body stay in contact with liquid cooling medium provided in container - Google Patents

Abstract

The headlight i.e. front headlight, has a light source designed as a LED (10), and a cooling body (9) connected with the source in a heat-conducting manner. The source is arranged on a printed circuit board (8) that is arranged in a housing. Areas of the cooling body stay in contact with liquid cooling medium provided in a cooling medium container. The areas of the cooling body form a wall of the container. The cooling body is designed as a massive metallic body, metallic hollow body or heat pipe. The cooling body is guided into a washing water container (3) through an opening (12). Independent claims are also included for the following: (1) a motor car (2) a method for cooling a LED-headlight.

Description

The application relates to an LED (Light Emitting Diode) headlamp assembly having at least one LED configured as a light source. It further relates to a motor vehicle with such an LED headlamp assembly and a method for cooling an LED headlamp.

Such LED headlights are increasingly being used in motor vehicles for the main light functions low beam and / or high beam. They require a special cooling concept because of their strong heat dissipation. For this purpose, typically an electrically operated fan is placed in the headlight housings. The resulting air flow cools down on the cover of the headlamp and thus cools the LED.

However, such electrically powered fans require considerable space and also consume power. Partly it has been proposed to use body components as heat sinks. However, as these increasingly consist of non-metallic, poorly heat-conductive materials, this is not always efficient.

It is from the DE 10 2007 055 165 A1 known to divert coolant from the cooling circuit of an air conditioner and to use for cooling the LED. However, this solution requires specially laid for this purpose coolant lines.

It is an object of one aspect of the invention to provide an LED headlamp assembly that is optimized for low power consumption, long life and low cost both during assembly and during operation. Furthermore, the LED headlight system should be flexible in their arrangement and take up a small space.

The object of a further aspect of the invention is to provide a most efficient method for cooling LED headlamps.

This object is achieved with the subject matter of the independent claims. Advantageous developments of the solution will become apparent from the dependent claims.

According to one aspect of the application, an LED headlamp arrangement is specified which comprises at least one light source designed as an LED and at least one heat sink to which the light source is connected in a heat-conducting manner. Regions of the heat sink are in contact with a liquid coolant held in a coolant tank.

A coolant container is understood here and below as meaning a container in which a coolant supply is kept in reserve and which has a large volume in relation to corresponding coolant lines.

Accordingly, in the case of such a headlight arrangement, at least one region of the heat sink is located within a coolant tank.

Such LED headlight assembly uses the good heat exchange with a liquid coolant to dissipate the heat generated. The heat can thus be dissipated particularly effectively, so that particularly powerful LEDs can be used. At the same time can be dispensed with a lot of space-consuming elements such as fans.

This has the advantage that the shape and position of the headlights on the motor vehicle can be largely chosen freely from the technical constraint of heat dissipation. It is thus possible to provide very long, thin or specially, in particular laterally positioned headlights. This is desirable for reasons of insurance classification and pedestrian protection.

It is not necessary to provide a separate coolant tank for cooling the LED headlight assembly. Rather, already existing in the vehicle coolant can be used, in particular washing water tank a windscreen washer system, wash water tank headlight cleaning system and / or cooling water tank of an engine cooling system.

According to one embodiment, at least portions of the heat sink form a wall of the coolant tank. In this embodiment, the heat sink for discharging the heat on a large area, which forms a wall of the coolant tank and thus is in contact with the coolant.

The heat sink may be formed as a solid metallic body and consist for example of copper or other good heat conducting metal.

Alternatively, the heat sink may also be formed as a metallic hollow body and, for example at least partially comprise a tube which dips into the liquid coolant.

The heat sink can also be designed as a heat pipe. Heat pipes are heat exchangers that allow the transfer of heat with a high heat flux density using the heat of vaporization of a substance. They are therefore to accommodate relatively space-saving even with high transmission power.

In a heat pipe, a transport medium is typically enclosed, which evaporates at one end of the heat pipe in the boiling zone while absorbing heat. The vapor passes through a barrier, which is formed for example of a porous, non-wettable material from the condensate channel in the steam channel and flows in the steam channel to the other end of the heat pipe in the condensation region. In the condensation region, the transport medium condenses again with the release of heat and is returned to the boiling zone using the capillary action in the condensate channel.

Such a heat pipe could dive into the liquid coolant with its end forming the condensation region.

According to one embodiment, the heat sink is designed to be flexible at least in regions. Such a heat sink makes it possible to compensate for tolerances in its mounting on or in the coolant tank.

According to one embodiment, the coolant reservoir has at least one opening for the passage of the heat sink. In this embodiment, where the heat sink passes through a wall of the coolant tank to immerse in the liquid coolant, a seal is provided in the corresponding opening in the wall to prevent the escape of coolant. In addition, seals can also be provided where the heat sink is connected to the LED or to a board carrying the LED.

According to one aspect of the application, the LED headlight assembly is used in a motor vehicle, in particular as a headlight.

Headlamps often feature AFL (Adaptive Frontlight) functionality today. They are therefore optimized on the one hand so that they can produce a high brightness, on the other hand, it is also desirable to adapt the geometry of the headlights as flexible as possible to the shape of the motor vehicle and to be able to freely design otherwise. This not only has visual reasons, but is also important, for example, when the function of a direction indicator is to be integrated into the headlamp assembly.

In the design of such a headlamp, the problem may arise that resulting from some areas heat can not be sufficiently dissipated. This can lead to the destruction of the LEDs. However, the connection of the heat sink to a liquid coolant held in a coolant container makes it possible to dissipate the heat particularly effectively in such a vehicle.

According to one embodiment, the coolant reservoir is designed as a coolant reservoir of an engine cooling system. Alternatively or additionally, the coolant container may also be designed as a wash water tank of a windscreen washer system and / or as a wash water tank of a headlight cleaning system.

If a wash water tank is used as a coolant tank, it can be placed in the immediate vicinity of the headlights. For example, it is also conceivable to use the washer fluid tank of a windscreen washer system for a headlight of the motor vehicle and the washer fluid tank of a headlight washer system for another headlight. It would also be conceivable, for example, to split the washing water container of a windshield washer and to place one of the two containers in the immediate vicinity of the headlamps.

Such a headlight assembly uses already existing coolant reservoirs, which are flexible in their placement and therefore can be mounted in close proximity to the headlights. There are no major modifications to the coolant tanks necessary. Depending on the embodiment, it may be sufficient to provide only an opening for the passage of the heat sink and a corresponding seal in the wall of the coolant tank.

According to one aspect of the application, a method for cooling an LED headlight is specified, wherein heat generated by at least one LED light source is dissipated by means of a heat sink and delivered to a liquid coolant held in a coolant container. In such a method, additional lines are not required. Since the heat sink is in contact with the coolant held in the coolant tank, the dissipation of heat can be particularly effective.

Embodiments will now be described in more detail with reference to the accompanying drawings.

1 schematically shows a motor vehicle with LED headlights according to an embodiment of the invention;

2 shows schematically a perspective view of an LED headlamp assembly according to a first embodiment of the invention;

3 shows a section through the LED headlamp assembly according to 2 ;

4 shows steps in assembling the LED headlamp assembly according to 2 ;

5 schematically shows a perspective view of the LED headlamp assembly according to a second embodiment and

6 schematically shows a section through the LED headlamp assembly according to 5 ,

Identical parts are provided with the same reference numerals in all figures.

The car 1 according to 1 has two headlights 2 on, which are designed as LED headlights. The LED headlights can be designed in particular as LED matrix headlights or as LED full headlights and fulfill both a low beam function and additional functions such as daytime running lights, turn signals, brake lights and license plate lights.

The headlights 2 have at least one designed as an LED light source whose emission direction is typically optimized by means of a reflector. The LED is arranged on a circuit board, whereby also a number of LEDs can be mounted on the same board. The board is arranged in a housing, not shown, which is sealed to the outside.

In operation, the LED generates heat by means of an in 1 dissipated heat sink not shown and discharged to a coolant. In 1 are as a coolant tank of wash water tank 3 a windscreen washer and the coolant tank 4 an engine cooling system 5 shown.

2 shows a first embodiment of the headlamp assembly, in which the washing water tank 3 the windscreen washer system is used as a coolant tank. The washing water tank 3 has a container housing 6 and at its upper end a closure 7 on. The LEDs of the headlamp assembly are on a circuit board 8th mounted with a heat sink 9 is thermally conductively connected. Areas of the heat sink 9 protrude into the wash water tank 3 into it.

This is in 3 shown in cross section. The washing water tank 3 , inside which a water pump 11 is arranged, has in its container housing 6 an opening 12 on, through which the heat sink 9 into the interior of the wash water tank 3 protrudes. He is there from the in 3 not shown washing water flows around, so that a particularly effective heat dissipation and thus a good cooling of the LED 10 is possible.

In the wash water tank 3 a device, not shown, is provided which monitors the water level. If this is too low, a warning signal is issued.

4 shows in its upper and its lower part the assembly of the headlamp assembly according to the 2 and 3 , The washing water tank 3 points to its container housing 6 a recess 13 on, in which after mounting areas of the LED board 8th nestle.

When mounting the LED board 8th with the heat sink 9 as in the lower part of the 4 shown, in the direction of the arrow 16 on the wash water tank 3 be moved, the heat sink 9 through the opening 12 into the interior of the wash water tank 3 occurs and the first end 14 the board 8th in the recess 13 to come to rest.

In this embodiment, a particularly space-saving arrangement of the components to each other is achieved. The result is a summary of the LED board 8th with the wash water tank 3 to a module in which the shapes of the parts are coordinated.

In this embodiment, it may be advantageous not to assemble the headlamp assembly from the outside, as has hitherto been customary, but rather the LED board 8th before installation with the wash water tank 3 to connect and install with this from the inside.

5 shows a second embodiment of the headlamp assembly in which areas of the heat sink are flexible.

This is especially in 6 recognizable. The heat sink 9 that in turn through an opening 12 into the interior of the wash water tank 3 sticks out, points near the LED board 8th a flexible area 15 on. In this embodiment, the heat sink is 9 designed as a metallic hollow body and is in its flexible range 15 guided or "twisted" that he can be compressed or stretched in this area. This allows for tolerances in the location of the LED board 8th and the wash water tank 3 be balanced with each other.

The embodiment of the headlamp assembly with a designed as a metallic rod heat sink 9 passing through an opening 12 in the container housing 6 a washing water tank 3 is guided, represents a particularly simple structure of the LED headlamp assembly, which is thus very robust. In such an embodiment let the opening 12 and optionally the board 8th seal very well, allowing the leakage of water from the wash water tank 3 and in particular the contact of water with the board 8th can be safely avoided.

In this embodiment, wash water tanks 3 and LED board 8th also be well separated from each other, since due to the flexible connection of the two together through the flexible heat sink 9 Tolerances can be compensated.

Although at least one exemplary embodiment has been shown in the foregoing description, various changes and modifications may be made. The above embodiments are merely examples and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing description provides those skilled in the art with a scheme for practicing at least one example embodiment, which may make numerous changes in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the appended claims and their legal equivalents ,

LIST OF REFERENCE NUMBERS

1

motor vehicle

2

headlights

3

Washer fluid reservoir

4

Coolant tank

5

Engine cooling system

6

container housing

7

shutter

8th

LED board

9

heatsink

10

LED

11

water pump

12

opening

13

recess

14

first end

15

flexible area

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007055165 A1 [0004]

Claims (12)

LED headlight assembly comprising - at least one LED ( 10 ) formed light source, - at least one heat sink ( 9 ), with which the light source is thermally conductively connected, wherein areas of the heat sink ( 9 ) in contact with a in a coolant container ( 3 . 4 ) held liquid coolant. LED headlight assembly according to claim 1, wherein at least portions of the heat sink ( 9 ) a wall of the coolant tank ( 3 . 4 ) form. LED headlight assembly according to claim 1 or 2, wherein the heat sink ( 9 ) is formed as a solid metallic body. LED headlight assembly according to claim 1 or 2, wherein the heat sink ( 9 ) is designed as a metallic hollow body. LED headlight assembly according to claim 1 or 2, wherein the heat sink ( 9 ) is designed as a heat pipe. LED headlamp assembly according to one of claims 1 to 5, wherein the heat sink ( 9 ) is flexible at least in areas. LED headlamp assembly according to one of claims 3 to 6, wherein the coolant container ( 3 . 4 ) at least one opening ( 12 ) for passing the heat sink ( 9 ) having. Motor vehicle ( 1 ) with at least one LED headlight assembly according to one of claims 1 to 7. Motor vehicle ( 1 ) according to claim 8, wherein the coolant container ( 3 . 4 ) as a coolant reservoir ( 4 ) of an engine cooling system ( 5 ) is trained. Motor vehicle ( 1 ) according to claim 8 or 9, wherein the coolant container ( 3 . 4 ) as a washing water tank ( 3 ) is designed a windscreen washer. Motor vehicle ( 1 ) according to one of claims 8 to 10, wherein the coolant container ( 3 . 4 ) is designed as a washing water tank a headlight cleaning system. Method for cooling an LED headlamp, wherein at least one LED ( 1 ) generated by means of a heat sink ( 9 ) and to a in a coolant container ( 3 . 4 ) reserved liquid coolant is discharged.

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