The invention relates to a motor vehicle headlight, comprising a headlight housing and a cover plate including at least one light source arranged in this motor vehicle headlight, wherein the light of the at least one light source can be imaged ahead of the motor vehicle headlight in the form of a defined light distribution, and wherein a heat sink device is provided for cooling the at least one light source.
On a motor vehicle headlight, light sources are generally arranged inside the headlight housing, such as filament lamps, high-intensity discharge lamps or light-emitting diodes. During operation of the motor vehicle headlight, these customary light sources and the components thereof generate heat, which must be dissipated. Light-emitting diodes in particular should be kept below the maximum operating temperature thereof to ensure optimal output and a long service life.
In general, the ambient temperature of the vehicle headlight being operated is lower than inside the motor vehicle headlight itself, and the most practical approach thus is to give off the generated heat inside the motor vehicle headlight to the ambient temperature.
However, since the headlight housing of a motor vehicle headlight and a cover plate covering the front region of the housing usually fluidically separate the inside of the motor vehicle headlight from the surrounding area so as to prevent impurities, such as dust or other dirt particles, from penetrating into the interior of the motor vehicle headlight, a dedicated cooling device is provided, which is mounted so as to cool the inside of the motor vehicle headlight and the light sources arranged therein by giving off heat to the outside surrounding area.
Motor vehicle headlights are normally attached to a section of the vehicle frame abutting the engine compartment, which often has considerably higher temperatures than the outside ambient temperature. During operation of the vehicle, for example, heat is given off in the engine compartment by the internal combustion engine and a wide variety of components.
Likewise, the air in the engine compartment is heated by the sun's energy during use as well as non-use of the vehicle. It would therefore be an obvious choice to dissipate the temperature inside the motor vehicle headlight via the cover plate of an installed motor vehicle headlight, as is described in the patent application DE 10 2006 057 569 B4. However, this is refrained from for appearance reasons and so as not to limit the functionality of the cover plate, which can have a partially transparent design in the light-emitting direction of the motor vehicle headlight.
So as not intervene into the outer appearance of the vehicle with further structural measures, heat sink devices are mounted on the vehicle headlights in such a way that these are arranged in the direction of the engine compartment when installed. As was already mentioned, the temperature in the engine compartment can possibly be as high as, or higher than, the temperature inside the motor vehicle headlight. In this case, it is not possible for the heat sink device arranged in the direction of the engine compartment to cool the inside of the motor vehicle headlight, but the device would even heat it further.
It is therefore advantageous to configure the motor vehicle headlight with a cooling device that shields the inside of the motor vehicle headlight and the light sources arranged therein against the relatively high temperatures in the engine compartment.
It is the object of the invention, with respect to the aforementioned restrictions and other shortcomings of the prior art, to provide a motor vehicle headlight comprising a heat sink device, which cools the inside of the motor vehicle headlight and shields the light sources arranged therein against the relatively high temperatures in the engine compartment.
This object is achieved in that the heat sink device comprises two heat sink elements that are separated from one another by an air gap and that are arranged in such a way that a first heat sink element is mounted inside the motor vehicle headlight and a second heat sink element is mounted outside the motor vehicle headlight, wherein the heat sink device is provided with a contacting device, which is designed in such a way that heat exchange takes place between the heat sink elements via this contacting device when the temperature inside the motor vehicle headlight is higher than the temperature in the area outside the motor vehicle headlight on which the second heat sink element is mounted, and that no heat exchange between the heat sink elements is possible when the temperature inside the motor vehicle headlight is lower than the temperature in the area outside the motor vehicle headlight on which the second heat sink element is mounted.
An advantageous refinement of the device according to the invention provides that the heat sink elements are arranged in such a way that the first heat sink element is positioned in heat transfer contact with the at least one light source arranged in the headlight housing.
Furthermore, it may be expedient when the second heat sink element is oriented in the direction of the engine compartment, and preferably is positioned in an engine compartment, when the motor vehicle headlight is installed.
It may be advantageous when the heat sink elements are arranged in a stationary manner with respect to one another.
Advantageously, the contacting device can comprise at least one heat-conducting contact element, which is movable with respect to the heat sink elements.
In an advantageous embodiment, it can further be provided that the contacting device comprises one contact element or multiple contact elements, allowing heat exchange between the heat sink elements when the temperature inside the motor vehicle headlight is higher than the temperature in the area outside the motor vehicle headlight on which the second heat sink element is mounted, wherein the contact element or the contact elements of the contacting device is or are in simultaneous heat-conducting contact with the first heat sink element and the second heat sink element, and that no heat exchange between the heat sink elements is possible when the temperature inside the motor vehicle headlight is lower than the temperature in the area outside the motor vehicle headlight on which the second heat sink element is mounted, in that the included contact elements of the contacting device are only in contact with one heat sink element in each case or no heat sink element.
Since the contact surfaces of the contact elements, which make contact with one another under the above-described temperature condition to transfer heat, can have a flat or planar design, for example, wear or other reasons can cause the contact surfaces of the contact elements to no longer make contact across the full surface area. This is not conducive to optimal heat transfer, and for this reason a heat conductive paste or other means suitable for improving the heat transfer between two objects may be used.
Furthermore, it may be advantageous when the contacting device comprises a first contact element and a second contact element which enable heat exchange between the heat sink elements when the temperature inside the motor vehicle headlight is higher than the temperature in the area outside the motor vehicle headlight on which the second heat sink element is mounted, wherein the first contact element is in simultaneous heat-conducting contact with the first heat sink element and, via the second contact element, also with the second heat sink element, and that no heat exchange between the heat sink elements is possible when the temperature inside the motor vehicle headlight is lower than the temperature in the area outside the motor vehicle headlight on which the second heat sink element is mounted, in that the contact elements of the contacting device are only in contact with one heat sink element in each case, but not with one another.
It may be provided that at least one contact element of the contacting device is displaceably mounted in at least one recess in a heat sink element.
It is expedient when exactly two contact elements of the contacting device are displaceably mounted in a respective recess in the heat sink elements.
Advantageously, it is provided that the contact elements of the contacting device can be moved by at least one control element assigned to the respective contact element.
Furthermore, it is advantageously provided that a first control element is assigned to the first contact element and a second control element is assigned to the second contact element.
For example, the first control element can be designed in such a way that the first contact element is extended by the first control element when the temperature inside the motor vehicle headlight rises, so that a heat-conducting contact can be established with the second contact element.
Furthermore, it is favorable when the second control element is designed in such a way that the second contact element is retracted by the second control element when the temperature in the area outside the motor vehicle headlight on which the second heat sink element is mounted rises, so that a heat-conducting contact with the first contact element can be suppressed.
It is expedient when the control elements are made of a material that expands and contracts as a function of the temperature.
In one embodiment, it is provided that the control elements are made of bimetal.
When bimetals are used as control elements, for example, the same bimetal could be used for all control elements. It must be noted in this regard that the contact elements travel the same distance, in absolute terms, when heated or cooled by a certain ΔT, with a mirror-inverted positioning of the control elements—that is, the bimetals. For a general function of the invention, it is advisable to establish a “calibration position” at a certain temperature at which the contact surfaces of the contact elements make contact at the same temperature.
For this purpose, the position of the contact elements could be set so that these, for example at 70° C. inside the headlight housing and at 70° C. in the area outside the motor vehicle headlight on which the second heat sink element is mounted, just barely make contact with one another and establish a heat-conducting contact. Likewise, it would be conceivable for the contact elements to be positioned or calibrated so that these, for example at 71° C. inside the headlight housing and at 70° C. in the area outside the motor vehicle headlight on which the second heat sink element is mounted, just barely make contact with one another and establish a heat-conducting contact. The first calibration or positioning would thus be a heat-conducting contact between the contact elements at the same temperature, wherein the second possible calibration position, in which a heat-conducting contact is just barely present between the contact elements, is for a temperature difference at which the temperature inside the headlight housing is just barely higher than the temperature in the area outside the motor headlight.
The invention will be described in more detail hereafter based on the drawings. In the drawings:
As is apparent from
As is apparent from
A first contact element 203 is displaceably mounted in a recess 205 present in the first heat sink element 201, and a second contact element 204 is displaceably mounted in a recess 206 present in the second heat sink element 202. A first control element 207 is assigned to the first contact element 203, and a second control element 208 is assigned to the second contact element 204.
The contact elements 203, 204 can be moved by the respective control elements 207, 208, which in the shown example are made of bimetal, at least partially into or out of the recesses 205, 206.
Further possible embodiments of the present invention are shown in the further figures; for example, it is possible for multiple recesses 505, 506, 511, 512, 606, 612, 705, 706, 712 to be provided for the respective heat sink elements 501, 502, 601, 602, 701, 702, as is shown in
In
In contrast to the embodiment shown in
In
It shall also be noted that it has been dispensed with in
Moreover, temperature sensors can be provided in the embodiments shown in
Number | Date | Country | Kind |
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A 51043/2016 | Nov 2016 | AT | national |
Filing Document | Filing Date | Country | Kind |
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PCT/AT2017/060287 | 10/25/2017 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2018/090067 | 5/24/2018 | WO | A |
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102006001711 | Jul 2007 | DE |
102007057056 | May 2009 | DE |
2602538 | Jun 2013 | EP |
2009021135 | Jan 2009 | JP |
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Number | Date | Country | |
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20200072435 A1 | Mar 2020 | US |