Motor vehicle with at least one lighting device for the exterior lighting of the motor vehicle

Abstract

Motor vehicle (K,K'), with at least one lighting device (1,1'') for the exterior lighting of the motor vehicle (K, K'), wherein the respective lighting device (1,1'') has at least one heat dissipation device (15,25') for cooling at least one light source (14) of the respective lighting device (1,1''), and is equipped with both at least one transport or guiding means (18a) for guiding air (L) to the respective heat dissipation device (15,25') and with at least one transport or guiding means (18b, 18b') for guiding the air (L) to a condensation-critical point of the respective lighting device (1,1''), characterized in that the transport or guiding means (18;18a, 18b, 18b') are connected to the respective heat dissipation device (15, 25') for guiding the air (L) in such a way that at least one inlet opening (180a) for incoming air (L) and at least one outlet opening (180b, 180b') for outgoing air (L) is provided, wherein the at least one inlet opening (180a) is positioned such that it (180a) is exposed to the airflow (W) occurring during travel and the at least one outlet opening (180b, 180b') is arranged in the area of ​​a light lens (11) of the respective lighting device (1, 1'').

Description

[0001] The invention relates to a motor vehicle with at least one lighting device for the exterior lighting of the motor vehicle with the features of the preamble of claim 1.

[0002] Exterior lighting devices for a motor vehicle can be designed, for example, as headlights and / or taillights. Designation as separate fog lights, rear fog lights, or turn signals is also quite conceivable.

[0003] A common problem with lighting fixtures arises when the air temperature drops below the dew point. This can lead to the formation of condensation or dew on a cold surface, i.e., at a condensation-prone area. Such dew formation is undesirable because it impairs the proper functioning of the lighting fixture. A condensation-prone area is particularly likely to form on the lens of a lighting fixture.

[0004] In order to prevent condensation on lighting equipment or to accelerate defrosting, a variety of methods for ventilating a lighting equipment have become known in the prior art.

[0005] A common practice is the additional use of a suitable desiccant, which is stored in a container. The container can be located inside or attached to the lighting fixture. Under certain operating conditions, air used to ventilate the lighting fixture comes into contact with the desiccant and is thus dried. This allows for efficient dehumidification of the air and therefore improved defrosting of the lighting fixture.

[0006] The use of a desiccant is known, for example, from DE 43 04 789 A1. This document also proposes integrating a heating element into the desiccant to make it regenerable.

[0007] German patent application DE 10 2005 022 938 A1 proposes a ventilation device for a vehicle lighting system, in which the housing of the lighting system encloses an interior housing chamber to which a ventilation duct leads. The ventilation duct connects the interior housing chamber of the lighting system to a dry area of ​​the vehicle, for example, a trunk or vehicle interior.

[0008] German patent application DE 10 2005 043 499 A1, which has the features of the preamble of claim 1, describes a headlight for vehicles with a cover plate facing away from a lens. The cover plate holds a lighting module that projects into a cavity of the headlight. The headlight incorporates a forced air system for heat dissipation from the LEDs. Specifically, air is directed past cooling fins of a mounting plate for the LEDs by a fan. The air is then guided through a channel formed by an annular aperture and directed to the lens through a slot-like outlet.

[0009] From DE 103 40 073 A1, a headlight is known comprising a housing and a cover plate that closes a light-emitting opening. The housing contains a reflector with a projection lens arranged at a distance in front of the reflector, as well as an incandescent lamp. To reduce condensation of humidity inside the housing, a space between the reflector and the projection lens is enclosed by a metal casing. This casing has an air inlet and an air outlet for an airflow generated by the heated incandescent lamp when the headlight is in operation, thus creating air circulation within the housing. The housing also has air inlet and outlet openings.

[0010] German patent application DE 10 2011 089 945 A1 describes a motor vehicle headlight comprising a housing and a light outlet opening closed by a cover lens. A light module for generating a predetermined light distribution is arranged within the housing, the light module comprising at least one light source. The light source is connected to an electrothermal transducer designed as a Peltier element. Furthermore, means for controlling the electrothermal transducer are provided, causing the electrothermal transducer to dissipate heat towards the light source, thus increasing the temperature inside the headlight housing. Additionally, a fan is arranged within the housing, which creates a warm airflow along the inner surface of the cover lens.

[0011] Finally, DE 10 2014 106 793 A1 discloses a motor vehicle headlight comprising a headlight housing, a lens, and an air inlet and outlet. Furthermore, an air-permeable membrane is provided, by means of which the air inlet is closed. A ventilation device located within the headlight housing draws in air through the air inlet, whereby at least some of the drawn-in air can act on the inner surface of the lens.

[0012] Based on this state of the art, the object of the present invention is to provide a motor vehicle with which efficient defrosting or prevention of dew formation of at least one lighting device of its exterior lighting can be carried out.

[0013] The present problem is solved using the features of claim 1.

[0014] Advantageous further developments or adaptations of the invention can be found in the dependent claims.

[0015] First, a method for ventilating a lighting device for the exterior lighting of a motor vehicle is described, in which air from outside the lighting device is directed into it.

[0016] It is proposed that the air be brought into contact with at least one waste heat dissipation device, which serves to cool at least one light source of the lighting device, and then directed to a condensation-critical point of the lighting device.

[0017] This allows for very effective ventilation of the lighting system and lays the foundation for rapid defrosting or the prevention of condensation. This can also be achieved without the use of a costly desiccant. However, the invention does not necessarily preclude the use of a desiccant. The waste heat from at least one light source can thus be elegantly used for targeted defrosting of a condensation-prone area.

[0018] Both bringing the air into contact with the waste heat removal device and subsequently guiding the air to a condensation-critical point are preferably carried out in a targeted manner with the support of a suitable transport or guiding medium for the air.

[0019] As already mentioned, the invention relates to a motor vehicle for carrying out the method. As a starting point for the invention, such a motor vehicle has at least one lighting device for the exterior lighting of the motor vehicle, wherein the at least one lighting device has at least one heat dissipation device for cooling at least one light source of the lighting device. The lighting device is equipped with both at least one transport or guiding means for preferably directing air towards the heat dissipation device and with at least one transport or guiding means for preferably directing the air towards a condensation-critical point of the lighting device.

[0020] According to a further development, the waste heat dissipation device is designed as a substantially closed heat exchanger. In this case, the waste heat dissipation device has a cavity through which air can flow from at least one inlet opening of the heat exchanger to at least one outlet opening of the waste heat dissipation device. Furthermore, the waste heat dissipation device has fastening aids for attaching the at least one transport or guiding medium for air.

[0021] The essentially closed heat exchanger allows for particularly effective heating of the air, which is then used to defrost or prevent condensation.

[0022] The mounting points on the heat exchanger allow for easy attachment of an air transport or conveying device. This enables the controlled and leak-free flow of air used for ventilation through the heat exchanger.

[0023] As already mentioned, the heat dissipation device is arranged and designed in such a way that it can serve to dissipate the heat from at least one light source of the lighting device. Thus, the heat dissipation device can perform a space-saving dual function: Firstly, cooling of the light sources, and secondly, heating of the air used to ventilate the lighting system.

[0024] The heat dissipation device can, for example, be directly connected via a thermal conductor to a holder on which one or more light sources are mounted. When using LEDs (light-emitting diodes) as light sources, it is advantageous to thermally attach the heat dissipation device to a circuit board that carries one or more LEDs.

[0025] The invention proposes that the at least one air transport or guiding means be connected to the waste heat dissipation device such that at least one inlet opening for incoming air and at least one outlet opening for outgoing air are provided. The at least one inlet opening is positioned such that it is exposed to the airflow generated when the motor vehicle is in motion. The at least one outlet opening is located in the area of ​​a lens of the lighting device.

[0026] By using a transport or guiding medium, a very effective and targeted transport of air from the outside to the heat dissipation unit and from there to the particularly critical areas inside the lighting unit, especially the lens, is enabled. Positioning the inlet opening in a location exposed to the airflow and with existing positive air pressure leads to a significant increase in the airflow rate inside the lighting unit and thus to very effective ventilation / defrosting. Due to the increased airflow rate and the higher temperature, condensation is hindered and faster defrosting is facilitated.

[0027] According to a further embodiment of the motor vehicle according to the invention, the transport or guiding element is designed in the form of a hose and / or tube. At least over a large part of a first section, extending from the inlet opening to the heat dissipation device, the transport or guiding element is thermally conductive. At least over a large part of a second section, extending from the heat dissipation device to the at least one outlet opening, the transport or guiding element is, conversely, thermally insulating.

[0028] This design allows for the optimization of the thermal efficiency of the ventilation system, which consists of the waste heat removal system and the transport or guiding medium for air.

[0029] The inner diameter of the hose- and / or tube-shaped transport or conveying means is preferably in a range of about 8 to about 15 millimeters, particularly preferably about 10 millimeters.

[0030] To further increase the air volume flow, another embodiment of the invention provides at least one additional transport or guiding means for air, which runs from the lighting device to a wheel arch. In this way, the pressure difference contributing to the air volume flow can be maximized, since a slight negative pressure is created in the wheel arch when the vehicle is in motion, at least at typical speeds.

[0031] As mentioned previously, the inlet opening of the transport or guide element is located in an area of ​​positive air pressure. It may therefore be positioned, for example, behind a radiator grille. To prevent contamination of the air entering the interior of the lighting device, it is therefore highly advisable to equip the inlet opening with an air filter.

[0032] Another improved design proposes that two outlet openings for the transport or guiding medium be provided, each located in a lower, lateral area of ​​the lens. This promotes an airflow that contributes to the rapid defrosting of the lens.

[0033] Furthermore, it can contribute to an increase in thermal efficiency if the transport or conducting medium, from its inlet opening to the lighting device, is routed at least predominantly through an engine compartment. With sufficient engine heat, this allows the transport or conducting medium, and thus the air it contains, to be preheated.

[0034] In addition, according to another embodiment of the invention, the transport or guiding means, starting from its inlet opening to the lighting device, can be guided past an oil or water cooler in such a way that air transported in the transport or guiding means can be heated by waste heat from the oil or water cooler.

[0035] This measure can also contribute to increasing the thermal efficiency of the ventilation system. One possibility here is to use a separate component, such as a closed heat exchanger. Alternatively, the transport or conveying medium could be designed as a thermally conductive pipe and connected to the oil or water cooler via a thermally conductive connection.

[0036] Finally, according to a preferred embodiment of the motor vehicle according to the invention, it is also proposed that the at least one lighting device has at least one transport or guiding means for air, designed as a fan, through which air can be drawn in and brought into operative contact with the at least one heat dissipation device. Furthermore, at least one guiding means is provided through which air flowing from the heat dissipation device can be directed towards a light lens.

[0037] This makes it possible to implement the inventive method in a particularly cost-effective manner, since the waste heat dissipation device can remain a conventional cooling body with cooling fins.

[0038] Preferred embodiments of the invention are illustrated in the figures and are explained in more detail in the following description with reference to the figures, where further advantages of the invention also become apparent. In this context, identical reference numerals refer to identical, comparable, or functionally equivalent components, whereby corresponding or comparable properties and advantages are achieved, even if a repeated description is omitted.

[0039] They show, schematically, each one Fig. 1 a lighting device of a motor vehicle according to the invention, in a side view, Fig. 2 the lighting device from above in a view II according to Fig. 1, Fig. 3 a representation of a waste heat dissipation device in the lighting device according to view II from Fig. 1, but in isolation, Fig. 4 a motor vehicle according to the invention in a side view, Fig. 5 a motor vehicle according to the invention in a side view, in a further embodiment, Fig. 6 a lighting device of a motor vehicle not encompassed by the invention, in a side view, Fig. 7 a motor vehicle not encompassed by the invention in a side view, with a lighting device according to Fig. 6 and Fig. 8 a lighting device of a motor vehicle according to the invention in a further embodiment, in a side view,

[0040] First, attention will be drawn to the Fig. 1 and Fig. 2. Referenced.

[0041] The figures show a lighting device 1 according to the invention, which in the exemplary embodiment is designed as a headlight.

[0042] The lighting device 1 has a housing 10, which is closed off to the outside by a light lens 11.

[0043] The housing 10 contains a circuit board 13 which carries several light sources 14 designed as LEDs (light-emitting diodes).

[0044] Light rays LS can be emitted by the light source 14 towards a reflector 12, which are reflected by the reflector 12 towards the light disk 11. Only one light ray LS is shown as an example.

[0045] The figures also show that a heat dissipation device 15 in the form of a heat exchanger is connected to the circuit board 13 below it. The connection is thermally conductive, such that the heat dissipation device 15 can absorb and dissipate the heat generated by the operation of the light sources 14.

[0046] Furthermore, fastening aids 153 are indicated, which enable the fastening of a transport or guiding means 18 for air L.

[0047] The air L is intended to serve for the ventilation of the interior of the lighting device 1, in particular for the ventilation of the lens 11. In the Fig. 1 and Fig. 2 already indicates the transport or guide means 18, which can be attached to the waste heat dissipation device 15.

[0048] In the exemplary embodiment, the transport or guiding means 18 is designed in a hose- and / or tube-like form. The transport or guiding means 18 has a first section 18a, which leads towards the waste heat dissipation device 15, and a second section 18b, which leads away from the waste heat dissipation device 15.

[0049] On the rear wall of the housing 10 there are two openings 16, through which, on the one hand, the first section 18a of the transport or guiding means 18 passes and, on the other hand, another, hose-like transport or guiding means 19 (also for air) is passed through.

[0050] Both openings 16 are sealed by sealing grommets 17. As can be seen in particular from the Fig. As can be seen in Figure 2, the second section 18b of the transport or guiding means 18 branches off and is brought towards a lower area of ​​the light disk 11. This creates two outlet openings 180b in the lower area of ​​the light disk 11. Heated air can exit from these outlet openings 180b towards the light disk 11 and flow past it from bottom to top. The outlet openings 180b are preferably oriented frontally towards the light disk 11 at a distance of a few millimeters.

[0051] Based on Fig. Section 3 now describes the waste heat extraction device 15 in more detail on its own.

[0052] The waste heat dissipation device 15 is made of a highly thermally conductive material, such as aluminum, and can be designed as a single or multiple component. It is essentially closed and has a cavity 150 into which the air L to be heated can enter via an inlet opening 151 and exit again via an outlet opening 152.

[0053] Air guide vanes 154, which are arranged offset from one another, result in a meandering airflow L through the waste heat extraction device 15. The inlet and outlet openings 151, 152 are also arranged diagonally offset from one another in the selected view.

[0054] The ends of sections 18a and 18b of the transport or guiding means 18 are indicated by dashed lines. These sections can be attached to the heat exchanger 15 by means of the fastening aids 153. The fastening aids 153 are preferably designed as tube-like projections onto which sections 18a and 18b of the transport or guiding means 18 can be clamped.

[0055] The Fig. Figure 4 shows a motor vehicle K with a lighting device 1 designed as a headlight. The lighting device 1 is equipped with a heat dissipation device 15. It can be seen that a first section 18a and a second section 18b of the transport or guide means 18 are connected to the heat dissipation device 15. The first section 18a has an inlet opening 180a for incoming air, which is located in the area of ​​a ventilation grille 23, preferably behind it. In this way, the inlet opening 180a is exposed to the airflow W that occurs when the motor vehicle K is in motion and is thus located in an area of ​​positive air pressure.

[0056] In order to keep the air L entering the transport or conveying medium 18 clean, the inlet opening 180a is equipped with an air filter 20.

[0057] Furthermore, it is evident that at least a large part of the first section 18a is routed from the transport or guide means 18 through an engine compartment M of the motor vehicle K. Additionally, the first section 18a, which runs from the inlet opening 180a to the heat dissipation device 15, is thermally conductive, at least for a large part. For this purpose, the first section 18a can, for example, be designed as a hose with metal inserts or metal sections. However, it is also conceivable to design a large part of the first section 18a as a metal tube.

[0058] In this way it is possible for the air L guided in the transport or guide medium 18 to be heated, even without the lighting device 1 having to be put into operation and the light sources 14 being able to release the generated heat to the waste heat dissipation device 15.

[0059] The second section 18b of the transport or conveying medium 18, which leads away from the waste heat dissipation device 15, is largely designed to be thermally insulating. This ensures that the heated air L is kept as warm as possible until it exits the outlet openings 180b.

[0060] To maximize the air volume flow in the transport or guiding medium 18, the housing 10 of the lighting device 1 is pneumatically connected to a wheel arch R of the motor vehicle K via the further transport or guiding medium 19. When the motor vehicle K is in motion, a negative pressure is created in the wheel arch R. The transport or guiding medium 19 can also be hose- or tube-like. A maximum pressure differential can thus be generated between the inlet opening 180a and the outlet openings 180b.

[0061] In Fig. Figure 5 shows a motor vehicle K' in which, unlike motor vehicle K, an additional heat exchanger 21 is interposed between the inlet opening 180a and the waste heat dissipation device 15. The heat exchanger 21 is thermally connected to an oil or water cooler 22, which can thus transfer its heat to the heat exchanger 21.

[0062] The heat exchanger 21 is preferably constructed similarly to the waste heat removal device 15 and can serve to further improve the “preheating” of the air L flowing through the first section 18a of the transport or conveying medium 18.

[0063] From the Fig. A lighting device 1' is visible in Figure 6. Unlike lighting device 1, lighting device 1' has a heat dissipation device 25 designed as a heat sink. This heat sink is made of a highly thermally conductive material, such as aluminum, and has several cooling fins (not specified). The heat dissipation device 25 is connected via a thermally conductive coupling device 26 to a circuit board 13, which carries light sources 14 in the form of LEDs. Air L is drawn inwards to the heat dissipation device 25 by a transport or guide element 24 in the form of a fan and passed through it. The air L flowing out of the heat dissipation device 25 is directed towards the light lens 11 by means of a scoop-like guide element 27. At the end of the guide element 27 adjacent to the light lens 11, it has an upward bend 28.This allows the airflow to be optimally directed upwards along the light disc 11.

[0064] The Fig. Figure 7 shows a motor vehicle K'' not encompassed by the present invention, in which the lighting device 1' is installed in the form of a headlight.

[0065] The Fig. Section 8 describes yet another embodiment of a lighting device 1''. In contrast to the variant according to the Fig. 6. In this case, there is no actively supported transport of air L by means of a fan. Rather, a "passive system" is implemented here as well, similar to the Fig. 4 and Fig. 5, whereby the lighting device 1 of the Fig. 4 and Fig. 5 can be replaced by the lighting device 1'' if required.

[0066] The only difference is that, unlike the closed heat exchanger 15, an open heat dissipation device 25' in the form of a heat sink with cooling fins is used. As can be seen, air L to be heated or preheated is guided from an overpressure area in a first section 18a of an air transport or guiding medium to the heat dissipation device 25'. The air L is then forced approximately horizontally through the heat dissipation device 25', heated (further) there, and subsequently guided to the light lens 11 by means of a second section 18b' of a transport or guiding medium, which may be channel-like. Due to the transport and guiding medium 19 being connected to an underpressure area, a maximum pressure difference and thus good air circulation within the lighting device 1'' can be achieved.

[0067] In all embodiments, lighting devices are shown that operate according to the reflection principle. Of course, within the scope of the invention, the use of lighting devices operating according to the projection principle or according to both principles is also conceivable. Reference symbol list 1,1',1'' Lighting device 10 cases 11 Light lens 12 Reflector 13 circuit boards 14 light sources; LEDs (light-emitting diodes) 15 Waste heat dissipation device; heat exchanger 16 openings 17 sealing grommets 18 Transport or guiding means for air 18a first section of the means of transport or guidance 18b,18b' second section of the means of transport or guidance 19 other means of transport or guidance for air 20 air filters 21 additional heat exchangers 22 Oil or water coolers 23 ventilation grilles 24. Air transport or conveyance devices; fans 25.25' Waste heat dissipation device; heat sink 26 thermally conductive coupling device 27 Air Conductive Devices 28 Upward turn 130 openings 150 Cavity of the heat exchanger 151 Inlet opening of the heat exchanger 152 Outlet opening of the heat exchanger 153 Mounting aids for the heat exchanger for the transport or conveying medium 154 air baffles 180a Entrance opening 180b,180b' Exit openings K, K', K'' motor vehicle L air LS light rays M Engine compartment R wheel arch W Wind

Claims

[1] Motor vehicle (K,K'), with at least one lighting device (1,1'') for the external lighting of the motor vehicle (K, K'), wherein the respective lighting device (1,1'') has at least one heat dissipation device (15,25') for cooling at least one light source (14) of the respective lighting device (1,1''), and is equipped with both at least one transport or guiding means (18a) for guiding air (L) to the respective heat dissipation device (15,25') and with at least one transport or guiding means (18b, 18b') for guiding the air (L) to a condensation-critical point of the respective lighting device (1,1''), characterized by, that the transport or guiding means (18; 18a, 18b, 18b') for guiding the air (L) are connected to the respective waste heat dissipation device (15, 25') in such a way that at least one inlet opening (180a) for incoming air (L) and at least one outlet opening (180b, 180b') for outgoing air (L) is provided, wherein the at least one inlet opening (180a) is positioned such that it (180a) is exposed to the wind (W) occurring during travel and the at least one outlet opening (180b, 180b') is arranged in the area of ​​a light disc (11) of the respective lighting device (1, 1''). [2] Motor vehicle (K, K') according to claim 1, characterized by, that the respective waste heat dissipation device (15) is designed as a substantially closed heat exchanger, wherein the respective waste heat dissipation device (15) has a cavity (150) through which the air (L) can flow from at least a second inlet opening (151) to at least a second outlet opening (152) and wherein fastening aids (153) for fastening the transport or guiding means (18; 18a, 18b) for guiding the air (L) are provided on the respective waste heat dissipation device (15). [3] Motor vehicle (K) according to claim 1 or 2, characterized by, that the transport or guiding means (18; 18a, 18b) for guiding the air (L) are designed in a hose-like and / or tube-like form and are thermally conductive at least over a large part of a first section (18a), starting from the at least one inlet opening (180a) up to the respective waste heat dissipation device (15), and are thermally insulating at least over a large part of a second section (18b), starting from the respective waste heat dissipation device (15) up to the at least one outlet opening (180b). [4] Motor vehicle (K) according to any one of the preceding claims, characterized by , that at least one further means of transport or guidance (19) for air (L) is provided, which is guided from the respective lighting device (1,1'') to a wheel arch (R). [5] Motor vehicle (K) according to any one of the preceding claims, characterized by , that at least one inlet opening (180a) is equipped with an air filter (20). [6] Motor vehicle (K) according to any one of the preceding claims, characterized by , that two outlet openings (180b) of the transport or guiding means (18, 18b) are provided for guiding the air (L), each of which is arranged in a lower, lateral area of ​​the light disk (11). [7] Motor vehicle (K) according to any one of the preceding claims, characterized by , that the transport or guiding means (18; 18a), for guiding the air (L) from the at least one inlet opening (180a) to the respective lighting device (1), is guided at least to a predominant extent through an engine compartment (M). [8] Motor vehicle (K') according to any one of the preceding claims, characterized by, that the transport or guiding means (18; 18a) for guiding the air (L), starting from the at least one inlet opening (180a) to the respective lighting device (1), are additionally guided past an oil or water cooler (22) in such a way that the air (L) transported in the transport or guiding means (18; 18a) for guiding the air (L) can be heated by waste heat from the oil or water cooler (22).

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