Lighting unit with Anti-fog system

Abstract

The invention relates to a lighting unit (10), in particular an elongated lighting unit (10), outside a motor vehicle, comprising a housing (30) having at least one lighting opening closed by a light-permeable cover (31), the housing (30) having two end regions, a lighting assembly (20; 21) having at least one light source designed to emit light through the cover plate is arranged on each end region. At least one air inlet (40) and at least one air outlet (41) separate from the at least one air inlet (40) are provided on the rear housing wall (32), i.e. On the rear wall of the housing (30), between the two end lighting assemblies (20, 21), the air inlet (40) being connected to a vehicle interior (60) of the motor vehicle, whereas the air outlet (41) being connected to an outer region (70) of the motor vehicle. During operation of the motor vehicle, an automatic air circulation is established inside the housing (30) from the air inlet (40) to the air outlet (41), the automatic air circulation being caused by a pressure difference between the vehicle interior (60) and an outer region (70) of the motor vehicle.

Description

Technical Field

[0001] The invention relates to a lighting unit in the form of an elongated lighting unit for the outside of a motor vehicle according to the preamble of claim 1, comprising a housing having at least one light-emitting opening closed by a light-transmitting cover, wherein the housing has two end regions, on each of which a lighting component having at least one light source designed to emit light through the cover is arranged. Background Art

[0002] In newer motor vehicle models, LED lamps are increasingly being used as light sources for exterior lighting units. They can be used for taillights and brake lights, but also for high beam, low beam, turn signals or daytime running lights. For example, LED lamps are often brighter, more energy-efficient and more durable than halogen lamps.

[0003] LED technology also allows greater freedom when designing individual lighting components and their interconnection. For example, it is possible to provide functional lighting that interconnects the lighting components of a motor vehicle across the entire width or height of the rear of the motor vehicle or the tailgate, often referred to as a "cross-body" light strip or center light strip.

[0004] For example, such a transverse lighting unit optically connects the taillights of the rear of the motor vehicle to each other, so that the corresponding lighting unit has an elongated hollow lighting housing or lighting body, and the respective lighting components are accommodated in the end area of ​​the lighting housing or lighting body. For example, the elongated lighting housing extends over the entire width of the tailgate and its end area is in particular adjacent to a further lighting unit on the vehicle body (i.e., for example, the fender) and therefore usually forms a unit optically with this lighting unit. In other embodiments, the lighting is completely on the tailgate. In addition, further lighting devices, such as dynamic LED light strips and / or illuminated lettering, can be provided in the central area of ​​the lighting unit. However, the area between the ends can also be non-luminous.

[0005] However, this also applies to other lighting housings with light sources on the outside of the motor vehicle, where a problem that may arise with such cross-body lighting units is fogging of the hollow lighting housing from the inside, including fogging in the outer transparent area. Although the outer lighting bodies can be sealed to prevent unwanted water ingress, they cannot be completely isolated from the outside environment, since the expansion of the air due to the heat generated during operation must be ensured. Usually, the ambient air contains gaseous water, and therefore also the interior of the lamp. At lower temperatures, the gaseous water in the at least partially transparent lighting body becomes liquid and forms a visible film with the fogging of the lighting unit, which is often perceived as a quality problem by motor vehicle users. In the case of lamps that appear black and have a transparent outer lens, the liquid water film is even more visible. Furthermore, lighting units across the full width of the motor vehicle (cross-body coast-to-coast) result in greater susceptibility to the above-mentioned types of failure.

[0006] Therefore, various solutions for preventing the transparent outer surface from fogging are known for individual lighting units. For example, JP 2007-335 292 A discloses a system for a lamp of a motor vehicle intended to prevent the lamp from fogging, including the tail lamp. For this purpose, a wiring opening in the tail lamp leads from the vehicle interior to the tail lamp. The air flow passes through the bulb and the reflector to the exhaust duct.

[0007] In contrast, US 10 576 935 B2 discloses a motor vehicle with headlamps which are fluidically connected to an air conditioning system which supplies an air flow to the headlamps. The entire system comprises an electric fan for generating the air flow, an electric heater for heating the air flow generated by the electric fan, a sensory system for measuring the air temperature and humidity inside the headlamps, an electric heater and an electric fan arranged inside each headlamp, and an electronic control unit connected to the sensory system for receiving the measured quantities. The system is controlled by the measured quantities, which means a highly complex process with a number of additional components.

[0008] DE 10 2015 002 246 B4 likewise discloses a lighting device for a motor vehicle which is connected to an air conditioning system for preventing fogging.

[0009] CN 211 526 340 U also discloses an anti-fog system for a motor vehicle headlamp. The motor vehicle headlamp is composed of a lamp housing, a lampshade and a light-emitting unit. In addition, a light-emitting unit (LED lamp) includes an air intake pipe, an air guide pipe and a vent cap, wherein the air intake pipe is installed outside the lamp housing, the air intake pipe is connected to one end of the air guide pipe, the air guide pipe is arranged in the lamp housing, the other end of the air guide pipe leads to the inner surface of the lampshade, and the vent cap is arranged on the lamp housing. The air flow is introduced from the outside to the inner surface of the lampshade through the air intake pipe and the air guide pipe, and then flows out from the vent cap to form a continuously flowing air flow, and the inner surface of the lampshade is dehumidified and fog-free.

[0010] However, there is still no known suitable solution for the above-mentioned cross-body lighting unit and in view of the prior art shown, there is still room for improvement in this field. Summary of the invention

[0011] Therefore, the object of the present invention is to provide an improved cross-body lighting unit, in which externally visible fogging can be prevented or reduced and which can be dispelled in a simple manner without great effort.

[0012] According to the invention, this object is achieved by a lighting unit in the form of an elongated lighting unit having the features of claim 1. Further particularly advantageous developments of the invention are disclosed in the dependent claims.

[0013] It should be noted that the features and measures described in detail individually in the following description can be combined with one another in any desired technically meaningful manner and disclose further developments of the invention. The description, in particular together with the drawings, additionally characterizes and explains the invention in detail.

[0014] The lighting unit according to the invention is a longitudinal lighting unit outside the motor vehicle. "Long" in the context of the invention means that in the vehicle coordinate system the lighting unit is many times longer in one extension direction (y direction) than in the other two extension directions (x / z directions). Here, the y direction in the vehicle coordinate system extends along the vehicle transverse axis, the x direction extends along the driving direction and the z direction extends along the vehicle vertical axis. The lighting unit comprises a housing with at least one light-emitting opening closed by a light-transmitting cover. The housing is therefore also longitudinal and has two end regions, at each of which a lighting assembly with at least one light source designed to emit light through the cover is arranged.

[0015] For example, the lighting unit is mounted in the rear region of a motor vehicle and the light of the at least one light source is emitted from the housing backwards through the light-emitting opening. Preferably, therefore, the lighting unit is a tailgate lighting unit on a motor vehicle, which extends in the y-direction over the entire width of the tailgate and forms a so-called cross-body lighting unit together with the lighting unit on the vehicle body. In the context of the present invention, a "tailgate" also includes a trunk lid or a door which opens or closes about a vertical rotation axis.

[0016] For example, the lighting assembly of such a lighting unit may include a tail light, a rear fog light and a reversing light and may be adapted to form a side marker light or a side rear light. For example, at least one light source of the lighting assembly operates according to the reflection principle and comprises a light source and a reflector. In contrast, if the light source operates according to the projection principle, a projection lens and an aperture arrangement are additionally provided. In theory, a conventional incandescent lamp or a gas discharge lamp may be used as a light source, but preferably one or more light emitting diodes (LEDs) are used.

[0017] According to the invention, at least one air inlet and at least one air outlet separated from the air inlet are provided on the rear housing wall between the two end lighting assemblies, wherein the air inlet is connected to the vehicle interior of the motor vehicle, whereas the air outlet is connected to the exterior area of ​​the motor vehicle. During operation of the motor vehicle, this creates an automatic air circulation from the air inlet to the air outlet in the housing interior, which is characterized in that the automatic air circulation is caused by a pressure difference between the vehicle interior and the exterior area of ​​the motor vehicle.

[0018] According to the invention, it is therefore proposed that air flows from the vehicle interior of the motor vehicle through the housing of the lighting unit so that dehumidification and defogging of the light-transmitting cover plate is achieved in a determined and reliable manner. Preferably, for this purpose, the air from the interior is heated. However, the pressure difference required for the air flow is not generated by an additional device such as a fan; on the contrary, during the operation of the motor vehicle, with the doors and windows closed, a positive pressure relative to the environment is usually formed and the positive pressure causes a sufficiently large air flow. For example, the pressure difference between the vehicle interior and the outer area of ​​the motor vehicle is caused by the operation of the air conditioning system in the vehicle interior. This means that humidity is additionally removed from the air entering the housing of the lighting unit. Therefore, the air can be used particularly advantageously for the dehumidification of the lighting unit. Alternatively or in addition, the pressure difference can also be caused by the forward movement of the motor vehicle. Therefore, "operation of the motor vehicle" can cover different states in which different functional components of the motor vehicle are in operation and can generate a positive pressure in the vehicle interior. For example, the air conditioning system of the motor vehicle can also be operated when the motor vehicle is not moving forward.

[0019] It is thus possible to dispense with expensive devices for generating an air flow, ie no additional fans, blowers, heaters etc. are required, and instead the required air circulation is generated solely by the positive pressure which prevails in the vehicle interior and results in the required pressure difference.

[0020] For example, in one exemplary embodiment, the pressure difference is about 20 Pa. In practical tests, such a pressure difference results in an air flow of about 4.5 l / min, which is sufficient to achieve satisfactory dehumidification. For example, dehumidification is thus achieved in about 15 minutes in practical tests. The dimensions of the air inlet and outlet are appropriately chosen, but in particular in the case where the outlet connected to the external area is not so large as to allow excessive and undesirable moisture to enter, so that the incoming air flow is sufficiently large.

[0021] About 2-20mm 2 (Preferably about 3-10mm 3 ) level opening size was found to be advantageous.

[0022] The air inlet may be connected to the vehicle interior via ducts and / or hoses, whereas the air outlet is connected to the outside area via ducts and / or hoses. However, in the present invention, a direct air interface is established between the housing (i.e. preferably the rear housing wall of the lighting unit) and the vehicle interior. For example, the inner surface of the tailgate is directly adjacent to the vehicle interior and the air interface can be achieved with little assistance.

[0023] Furthermore, according to an exemplary embodiment of the invention, the air at the air inlet and / or the air outlet flows through a ventilation element having a membrane. Such ventilation elements are provided in particular for allowing pressure equalization in two directions through their membranes, protecting the interior of the lighting unit from contamination (e.g. dust, insects, etc.) and preventing the ingress of moisture. For example, it has been found that ventilation elements having membranes made of ePTFE (polytetrafluoroethylene) or PET (polyethylene terephthalate) can be used for this purpose. It has been found that membranes made of the material PET are particularly advantageous because they allow high air flow rates. Thus, in an ideal improvement, the connection between the lighting unit and the interior / exterior area of ​​the vehicle can be advantageously used without this leading to soiling inside the lighting unit.

[0024] If more than one air inlet and / or more than one air outlet are provided, they can be arranged appropriately so that the air flow is still automatically established. It is within the scope of the invention if the air inlet is not arranged directly next to the air outlet. In an ideal refinement, they have the greatest possible spacing in the lateral direction.

[0025] In one embodiment of the present invention, at least one additional central lighting assembly is provided in the housing of the longitudinal lighting unit between at least one air inlet and at least one air outlet, and the automatic air circulation flows through the additional central lighting assembly along the inner surface of the light-transmitting cover plate. For example, the central lighting assembly forms an LED light strip or a light-emitting font.

[0026] Preferably, an air circulation is formed inside the housing of the lighting unit so that the air circulation flows along the inner surface of the light-transmitting cover plate. For this purpose, a guide structure for the air flow of the air circulation can be provided inside the housing for specifically guiding the air circulation. Alternatively or in addition, the air flow enters the housing of the lighting unit in a favorable direction. Preferably, the direction of the air flow is preferably not perpendicular to the inner surface of the cover plate, but diagonally to the inner surface of the cover plate. At least one air inlet can be appropriately designed to guide the air flow back in the desired direction.

[0027] Both the air inlet and the air outlet are located on the rear housing wall, i.e. preferably on the back side of the lighting unit opposite the light-emitting opening, i.e. on the rear wall. The lighting unit is mounted on the vehicle via this back wall / rear wall and the air also enters and exits from this side. The arrangement of the at least one air inlet and the air outlet is selected so that the air circulates through the maximum number of critical areas in the housing. However, other components such as lighting components, connections, brackets, etc. in the housing must be taken into special consideration and taken into account when arranging the openings. It is advantageous within the scope of the invention if the openings are arranged between the two end lighting components, but at the widest possible distance from each other in order to achieve the greatest possible air circulation.

[0028] Thus, for example, according to one embodiment of the invention, the at least one air inlet and the at least one air outlet are arranged at a maximum distance Δy from each other in the y direction of the motor vehicle, taking into account the other components in the housing. Thus, the air flow covers as far as possible in the housing, which in turn leads to the maximum possible air circulation. Furthermore, the air flow can absorb as much moisture as possible and, if applicable, release heat, which accelerates the removal of condensed liquid from the cover plate.

[0029] According to another embodiment of the invention, at least one air inlet and at least one air outlet are arranged at different heights in the z-direction of the motor vehicle. Preferably, at least one air inlet is arranged above, i.e. higher, than at least one air outlet. The inventors have found that the weight of air increases due to absorption of moisture and then it flows out more easily from the lower air outlet.

[0030] Preferably, the at least one air inlet opening and the at least one air outlet opening are arranged at a maximum height difference Δz relative to each other, taking into account other components in the housing, so that the maximum possible height difference is conveniently achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Further advantageous developments of the invention are disclosed in the dependent claims and in the following description of the figures. In the figures: Figure 1 shows a three-dimensional view of an embodiment of a lighting unit according to the invention, seen from the back; Figure 2 Display according to Figure 1 A front view of the lighting unit, and Figure 3 Display according to Figure 1 Rear view of the lighting unit. DETAILED DESCRIPTION In the various figures, identical parts are always provided with the same reference symbols, for which reason these parts are usually also described only once.

[0032] Figure 1 A possible embodiment of an elongated lighting unit 10 according to the invention is shown in a three-dimensional view. Here, the lighting unit 10 is shown from the back and is mounted on a motor vehicle via the back. For example, the lighting unit 10 is a tailgate lighting unit which preferably extends over the entire tailgate of the motor vehicle, i.e. a so-called cross-body lighting unit is shown here. The motor vehicle and further lighting components mounted on the motor vehicle are not shown; however, for example, the two ends of the lighting unit 10 in the mounted state are adjacent to further lighting components of the motor vehicle, which further lighting components may in particular be rear lighting, such as tail lights, reversing lights and / or turn signals. This is shown in FIG. Figure 2 Schematically shown in .

[0033] The lighting unit 10 has an elongated housing 30 which in particular forms the outer contour of the lighting unit 10. The housing 30 has a rear housing wall 32 which serves as a rear wall of the rear side. On this rear wall, the housing 30 in particular has means for the electrical connection of the lighting unit 10 to the electrical system of the motor vehicle; however, in Figure 1 In the exemplary embodiment of the embodiment of the rear panel 10, they are shown only by way of example. In addition, exemplary means for fastening the lighting unit 10 are shown. An elongated light-emitting opening closed by a light-transmitting cover plate 31 is formed on the side opposite to the rear wall, i.e., on the front of the lighting unit 10. This light-emitting opening can extend in the y-direction over the entire housing 30 and can be closed by the light-transmitting cover plate 31. The tailgate lighting unit 10 is then transparent over its entire width and can contain different light sources.

[0034] For example, at least two lighting assemblies 20 and 21 are arranged inside the housing 30, and at least two lighting assemblies 20 and 21 are respectively arranged on the end areas of the housing 30. Light emitted by the lighting assemblies radiates backward and passes through the cover plate 31 and is emitted from the housing 30. Each lighting assembly 20, 21 forms, for example, a taillight, a rear fog lamp and / or a reversing lamp. These are only Figure 2 Shown schematically.

[0035] The two end lighting assemblies 20, 21 are formed in a known manner and include, for example, one or more light-emitting diodes and reflectors as light sources. Furthermore, an aperture and / or a lens can be provided in this region. At least one air inlet 40 is provided between the lighting assemblies 20, 21 on the rear wall of the housing 30. Furthermore, an air outlet 41 is also provided between the two lighting assemblies 20, 21, which is separate from the at least one air inlet 40. The air inlet 40 is connected to the vehicle interior of the motor vehicle, which is connected to the vehicle interior by Figure 1 In contrast, the exhaust port 41 is connected to an external area of ​​the lighting unit 10 , and the external area is identified by reference numeral 70 .

[0036] Due to the positive pressure in the vehicle interior 60, air (also referred to as inlet air flow 51) flows through the air inlet 40 into the interior of the housing 30. Here, an air flow 50 or air circulation is formed, which flows in particular through the central area of ​​the housing 30 and leaves the housing again through the outlet 41 and flows into the outer area 70. This air flow into the outer area 70 is also referred to as exhaust air flow 52. The course of the air flow 50 is only shown in an essentially idealized form without any turbulence. For example, suitable guide structures not shown in the drawings enable the realization of the following. Figure 1 and 2 The shown routing of air flow 50 is made possible.

[0037] Air intake 40 may be connected to vehicle interior 60 via various ducts and / or hoses to induce intake air flow 51 due to the positive pressure in vehicle interior 60. The same applies to exhaust 41, which may be connected, for example, to hoses to direct exhaust air flow 52 to exterior area 70 at appropriate points.

[0038] Positive pressure in the vehicle interior 60 can be achieved in various ways and, according to the invention, is generated by the operation of the motor vehicle. For this purpose, the windows and doors of the motor vehicle are ideally closed. For example, the operation of the air conditioning system in the vehicle interior 60 then generates positive pressure in the vehicle interior. This has the following advantages: the supplied air is also dry and heated. Alternatively or in addition, the forward movement of the motor vehicle also generates positive pressure. The positive pressure causes a pressure difference between the vehicle interior 60 and the external area 70, which causes the above-mentioned air flow. For this purpose, it is not necessary to provide additional components such as fans, blowers, heaters, etc. in order to transport air into the housing 30; instead, air circulation occurs automatically.

[0039] In one embodiment of the invention, at least one further lighting assembly 22 is provided in the central region of the lighting unit 10. For example, the further lighting assembly 22 is an LED light strip, a light letter or some other light-emitting element provided in the lighting unit 10 for lighting reasons. This lighting assembly 22 is located between the two openings 40 and 41, and the air supplied in the event of fogging of the cover plate 31 is also particularly effective in this region to defog the cover plate 31. Moreover, possible fogging in the region of the end lighting assemblies 20 and 21 is effectively prevented or dissipated by the air circulation generated, because the supplied air flow circulates the air right into this region, although this is not shown in the drawings.

[0040] In order to prevent or dissipate fogging as effectively as possible, the widest possible air circulation is thus achieved. For this purpose, the openings 40 and 41 are appropriately designed and arranged.

[0041] For example, Figure 2 The front of a lighting unit 10 is schematically shown with two lighting assemblies 20 and 21 on the left and right of the drawing plane. In the installed state, the lighting assemblies 20, 21 are adjacent to further lighting assemblies of the motor vehicle, which however are located at Figure 2 They are shown only in dotted form to illustrate their location. Figure 2 Schematic diagram of the rear wall of the housing 30 through the cover plate 31, on which the air inlet 40 is formed and the air outlet 41 is separated from the air inlet 40. The air inlet 40 and the air outlet 41 are located between the two lighting assemblies 20 and 21, and the distance Δy between them in the y direction of the motor vehicle is selected to be as large as possible, but taking into account other accessories in the housing 30. The distance is therefore maximum when taking into account these other components, i.e. if further components are required between the two lighting assemblies 20, 21, the former are appropriately positioned and the remaining space is used to set the openings 40 and 41 at the largest possible distance Δy from each other. The same applies to the height difference Δz between the two openings 40 and 41 in the z direction. The indicated directions correspond to the common vehicle coordinate system x, y, z.

[0042] Figure 2 Also shown is the basic path of the resultant air flow 50 within the housing 30. Although the resultant air flow 50 does not flow directly along the lighting assemblies 20 and 21, it creates an air circulation within the entire housing 30 that can also remove fogging from or prevent fogging of the two lighting assemblies 20, 21. Furthermore, a possible central lighting assembly 22 is indicated, and fogging in the area of ​​the possible central lighting assembly 22 can also be prevented or dissipated.

[0043] Figure 3 The lighting unit 10 is shown again from the back, mounted on a motor vehicle. The rear housing wall 32 can be seen again, i.e. the rear wall with the air inlet 40 and the low-level exhaust outlet 41, the air inlet 40 being at a higher level than the exhaust outlet 41. Here too, the air inlet airflow 51 and the exhaust airflow 52 enter and exit through the openings in the rear wall of the housing 30, the flow of the air flow 50 inside the housing 30 being shown in dashed lines. As can be seen, Figure 3 The route of the air flow 50 shown by the dashed line is Figure 1 and 2 The course of the airflow 50 in the center is different and this can be achieved by corresponding guide structures.

[0044] Ventilation elements with membranes, not shown, can be provided on the air inlet 40 and on the air outlet 41 and they allow a continuous air flow but prevent or reduce the ingress of moisture and dust. The ventilation elements with membranes are ideally permeable enough so that the pressure difference is sufficient to achieve automatic air circulation.

[0045] Reference numerals list 10 lighting units 20,21 Lighting assembly, end 22 Lighting assembly, central 30 Shell 31 Cover 32 Shell wall, rear wall 40 Air Inlet 41 Exhaust port 50 air circulation, air flow 51 Intake air flow 52 Exhaust flow 60 Vehicle Interior 70 External Area x,y,z vehicle coordinate system Δz height difference Δy distance

Claims

1. A lighting unit (10), the lighting unit (10) being a longitudinal lighting unit on the outside of a motor vehicle, the lighting unit (10) comprising a housing (30), the housing (30) having at least one light-emitting opening, the at least one light-emitting opening being closed by a light-transmitting cover plate (31), wherein the housing (30) has two end regions, a lighting assembly (20; 21) being arranged on each of the end regions, the lighting assembly (20; 21) having at least one light source, the at least one light source being designed to emit light through the cover plate, It is characterized in that At least one air inlet (40) and at least one air outlet (41) separated from the at least one air inlet (40) are arranged on the rear housing wall (32) between the two end lighting assemblies (20; 21), wherein the air inlet (40) is connected to the vehicle interior (60) of the motor vehicle, whereas the air outlet (41) is connected to the exterior area (70) of the motor vehicle, whereby during operation of the motor vehicle, an automatic air circulation from the air inlet (40) to the air outlet (41) is established inside the housing (30), the automatic air circulation being caused by a pressure difference between the vehicle interior (60) and the exterior area (70) of the motor vehicle.

2. The lighting unit according to claim 1, It is characterized in that The pressure difference between the vehicle interior (60) and the exterior area (70) of the motor vehicle is caused by operation of an air conditioning system in the vehicle interior (60) and / or by forward movement of the motor vehicle.

3. The lighting unit according to claim 1 or 2, It is characterized in that The pressure difference is at least 20Pa.

4. A lighting unit according to any one of the preceding claims, It is characterized in that In the housing (30), at least one further central lighting assembly (22) is provided between the at least one air inlet (40) and the at least one air outlet (41), and the automatic air circulation flows through the at least one further central lighting assembly (22).

5. A lighting unit according to any one of the preceding claims, It is characterized in that Taking into account other components within the housing (30), the at least one air inlet (40) and the at least one air outlet (41) are arranged at a maximum distance Δy from each other in the y direction of the motor vehicle.

6. A lighting unit according to any one of the preceding claims, It is characterized in that The at least one air inlet (40) and the at least one air outlet (41) are arranged at different heights in the z-direction of the motor vehicle.

7. The lighting unit according to claim 6, It is characterized in that Taking into account other components within the housing (30), the at least one air inlet (40) and the at least one air outlet (41) are arranged with a maximum height difference Δz relative to each other.

8. The lighting unit according to any one of claims 6 and 7, It is characterized in that The at least one air inlet (40) is arranged above the at least one air outlet (41).

9. A lighting unit according to any one of the preceding claims, It is characterized in that The lighting unit is a tailgate lighting unit on the motor vehicle which extends in the y-direction over the entire width of the tailgate.

10. The lighting unit according to any one of the preceding claims, It is characterized in that The air inlet (40) and / or the air outlet (41) has a ventilation element which has a membrane.

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