Lighting equipment

Abstract

Lighting device (10, 60) for a motor vehicle (motor vehicle) with a housing (12) for delimiting a housing interior (14), wherein the housing (12) has an air inlet opening (34) and an exhaust air outlet opening (36) for the housing interior (14), with an air guide (38) for guiding incoming air through the air inlet opening (34), wherein a filter element (48) is provided such that air flowing in through the air guide (38) can first pass through the filter element (48) and only then into the housing interior (14), wherein the filter element (48) is arranged on the air guide (38) and within the housing interior (14), wherein the filter element (48) is completely enclosed in the housing interior (14), characterized in that the air guide (38) is designed as a hollow tube (39) penetrating the housing wall (42), wherein the hollow tube (39) has a free end (40) exhibits which protrudes into the interior of the housing (14),wherein the filter element (48) is arranged at the free end (40), wherein the filter element (48) is designed and arranged on the air guide (38) such that it completely covers the free end (40) of the hollow tube (39).

Description

The invention relates to a lighting device for a motor vehicle (motor vehicle), in particular a motor vehicle headlight. A car headlight typically has a housing that encloses an interior space. This interior space contains, for example, light sources for the lighting system and / or optical components such as reflectors or lenses. The interior of the housing is usually largely sealed off from the outside to prevent the ingress of dirt. This can lead to the problem that the humidity present inside the housing condenses on those parts of the lighting device that are adjacent to or enclosed within the housing. Condensation occurs when the dew point is reached, especially when the surface temperature of a component is lower than the temperature of the humid air in the adjacent housing interior. Condensation on parts of the lighting system is generally undesirable. This is especially true for parts visible from the outside, such as lenses, reflectors, or the lens itself. The cloudiness caused by condensation is often perceived as a defect. Condensation can also impair the functionality of electrical components and, for example, lead to short circuits. The moisture that leads to condensation can be trapped within the lighting device itself, for example, on the surface of components adjacent to the housing interior. This effect can occur particularly with plastic components. During operation, the waste heat from the light sources warms the lighting device and the housing. This can release the trapped moisture, humidifying the air inside the housing. This moisture can then condense on those components of the lighting device that heat up more slowly from the light sources and therefore have a lower temperature. Various measures are known to reduce or prevent dew formation. WO 2004 / 058381 A1 describes a lighting device in which the housing containing the light source is connected to a ventilation chamber open to the environment via a single pressure relief opening. Ventilation occurs when, as the housing interior heats up, air is expelled through the pressure relief opening into the ventilation chamber and thus into the environment. During cooling, fresh air is supplied to the housing interior through the same pressure relief opening. A multi-stage filter is associated with the pressure relief opening to reduce the ingress of moisture, dampness, and dirt into the housing interior. Moisture is removed by a cyclical inflow and outflow through the single pressure relief opening. Alternatively, ventilation systems for automotive lighting devices are known in which an airflow through the interior of the housing is provided via at least one intake air opening and one exhaust air opening (e.g., in DE 198 41 727 A1). The intake air opening can be open to the vehicle's surroundings or, for example, connected to the vehicle's ventilation system. To prevent dirt from entering the interior of the housing, filters can be arranged in front of the intake air opening. When the lighting device is used in the vehicle, these filters are then exposed to the vehicle's surroundings or the engine compartment. This places a heavy burden on the filters from splashing water and dirt. This can lead to a reduction in service life, premature clogging, and ventilation failure, or necessitate frequent filter changes. The use of correspondingly resistant filters also results in high manufacturing costs. US 6 224 247 B1 discloses a vehicle light, DE 102 21 405 A1 discloses a discharge lamp for vehicle headlights and US 6 071 000 A discloses a vehicle light with a ventilation opening. DE 10 2009 017 728 A1 discloses a lighting device with the features of the preamble of claim 1. The present invention is based on the objective of increasing the reliability of the ventilation, in particular improving the service life of the filter element. This problem is solved by a lighting device according to claim 1, which can be used in particular as a headlight in a motor vehicle. The lighting device comprises a housing to enclose an interior space and a ventilation system for ventilating the interior space. The ventilation system includes at least one air inlet for drawing ambient air into the housing and at least one exhaust opening for expelling air from the housing. An airflow through the housing interior can be provided for ventilation via the air inlet and exhaust openings. An air duct is provided to guide the incoming air through the air inlet, and this duct is equipped with a filter element such that the air flowing through the duct first passes through the filter element and only then enters the housing interior. According to the invention, the filter element is arranged on the air duct and within the housing interior. The air duct protects the filter element. Since the filter element is located inside the housing interior, it is also largely shielded by the housing from splashing water, spray, and contamination from the outside or from the engine compartment. This significantly reduces the stress on the filter element. The filter element can reliably perform its intended function of filtering the air directed through the housing interior for ventilation. In principle, the housing can have several ventilation openings, at least one of which serves as an air intake opening and at least one as an exhaust opening. The air inlet and / or exhaust opening preferably borders directly on the interior of the housing. In particular, the air inlet and / or exhaust opening is designed as an opening or recess in the housing wall that defines the interior of the housing. The air duct exits through the housing wall and the air inlet opening into the housing interior. The air duct is designed to direct ambient air or ventilation air through the air inlet opening into the housing interior. The air duct features, in particular, an air passage defined by guide walls. These guide walls may extend into the housing wall at the air inlet opening. Alternatively, the air duct may penetrate the housing through the air inlet opening into the housing interior. In any case, the air passage opens into the housing interior and is also connected to the surrounding environment or a ventilation source. The interior of the housing is primarily designed to accommodate functional components of the lighting system, such as at least one light source or optical devices, such as reflectors and / or lenses. Such devices may also be arranged in sections around or within the interior of the housing. The housing of the lighting device extends, for example, along a longitudinal axis between a base section and a light-emitting section through which light can be emitted during operation of the lighting device. The light-emitting section can, for example, be designed as a transparent section of the housing, such as a light-emitting aperture covered by a translucent lens. According to the invention, the filter element is completely enclosed within the housing interior. It can, for example, cover the air intake opening inside the housing interior. In particular, the filter element is arranged at a distance from an inner wall of the housing in which the air intake opening is provided. The air duct is thus also designed to support the filter element within the housing interior. The air duct is preferably designed as a channel opening into the interior of the housing. According to the invention, the air duct is a hollow pipe penetrating the housing wall through the air inlet opening. In principle, the air duct and the housing, or a housing section containing the air intake opening, can be formed as a single piece, e.g., as a continuous injection-molded part. However, it is also conceivable that the air duct is designed as a separate component that is positioned and attached within the air intake opening. The section of the hollow pipe that penetrates the inner wall of the housing through the air intake opening is primarily tubular in design. The cross-section of the hollow pipe can, in principle, have any shape. For example, a circular, oval, polygonal, or square cross-section is conceivable. According to the invention, the hollow tube has a free end at which the hollow tube is open, with this free end projecting beyond the inner wall of the housing into the interior of the housing. This ensures that the free end is spaced away from the inner wall of the housing. According to the invention, the filter element is then arranged at the free end and thus spaced away from the inner wall of the housing and arranged inside the housing interior. According to the invention, the filter element is designed and arranged on the air duct in such a way that it completely covers the free end of the hollow tube. In a preferred embodiment, the airflow continues outside the housing, forming an air duct with at least one bend. The air duct can also have multiple bends. Therefore, the air duct changes direction at least once along its path, starting from the air intake opening outside the housing, preferably by an angle of change between 45° and 120°, particularly 90°. Due to this angled path, air can only reach the filter element via a correspondingly angled flow path. This prevents the filter element from being contaminated by direct splashing water, spray, or dust. Particularly when driving through rain or dusty environments, this can significantly extend the service life of the filter element. The angled or kinked air duct can be designed in such a way that at least a portion of the dirt or moisture carried along with the air passed through the air duct for ventilation is already deposited on the inner walls of the air duct, thus reducing the load on the filter element. The housing and / or air duct is preferably designed as a single component manufactured using injection molding. The filter element can be injected into the air duct or housing during the manufacturing process. Alternatively, the filter element can be welded into the air duct, for example, using ultrasonic welding for plastics. This allows for simple and cost-effective production of the ventilation system with filter. Another option is to design the filter element as an insert for the air duct and weld it in place during assembly of the lighting unit. For further development, an additional air guide is also provided for the exhaust opening, which is designed to direct air flowing from the interior of the housing through the exhaust opening. This additional airflow can also be designed with the features described above for the first airflow. In particular, the additional airflow can continue outside the housing and form an angled air duct there. This prevents direct entry of droplets or contaminants into the housing interior through the exhaust opening. The filter element is designed, for example, to filter out dirt, dust, and / or moisture droplets. The filter element can be designed as a membrane. Such a membrane can, for example, be stretched over or embedded in the opening of the air intake leading into the interior of the housing. Preferably, the membrane completely covers the opening. The filter element can also be designed as a compact filter cartridge or as a filter extending elongated in the direction of flow. Paper filters or sintered filters can be used. Because the filter element is protected inside the housing, a long service life can be achieved even with cost-effective filter elements. Further details and advantageous embodiments of the invention are explained in more detail below with reference to the figures. The figures show: Fig. 1 a sketched representation of a lighting device according to the invention; Fig. 2 a detailed view of Fig. 1; Fig. 3 another lighting device according to the invention. In the following description and in the figures, the same reference symbols are used for identical or corresponding features. Figure 1 schematically shows a longitudinal section of a vehicle lighting device 10. An example of a lighting device designed as a vehicle headlight is shown. The headlight 10 has a housing 12, which defines an interior housing space 14. The housing 12 is shaped such that the interior housing space 14 extends along a longitudinal axis 16. With respect to this longitudinal axis 16, a rear section 18 and a front section 20 of the housing 12 are defined. The front section 20 comprises a light emission section 21 through which light can be emitted during operation of the lighting device 10. As shown in the example, a transparent light lens 22 can be provided on the light emission section 21, which allows light to be emitted from the interior of the housing 14 into the surrounding area 24 of the lighting device 10. The rear section 18 can, for example, serve to anchor the lighting device in a motor vehicle. When the lighting device 10 is used as intended with a motor vehicle (MV), for example as a headlight, the housing 12 is arranged in such a way that the light emission section 21 and / or the lens 22 together with other body components 26 forms an outer skin of the MV. The interior of the housing 14 contains optical devices of the lighting device 10, e.g. a schematically represented light source 28 and an associated optical device 30 (e.g. reflector, lens). In principle, the housing 12 can be constructed of multiple parts. In the example shown, the rear section forms one housing part, and the front section 20 another housing part. The housing parts 18 and 20 are connected to each other, for example, by a snap-fit ​​connection 32. The snap-fit ​​connection 32 is preferably designed to be media-tight, for example, by means of sealing elements not shown in detail. For ventilation of the housing interior 14, the housing 12 in the illustrated example has an air inlet 34 and an exhaust air outlet 36. However, several ventilation openings can also be provided. Ventilation of the housing interior 14 can be achieved by air flowing into the housing interior through the air inlet 34 and flowing out of it through the exhaust air outlet 36. In the example shown in Fig. 1, the air inlet 34 is located in a region of the rear section 18 facing the front section 20. The exhaust air inlet 36 is located in the opposite region of the rear section 18. However, this configuration is not mandatory (see Fig. 3). To introduce air into the housing interior 14, an air guide 38 is provided, which penetrates the housing 12 through the air inlet opening 34 and opens into the housing interior 14. The air duct 38 is preferably designed as a hollow tube 39, which penetrates the housing 12 through the air inlet opening 34. Preferably, the hollow tube 39 projects with an open, free end 40 through the housing wall 42 into the housing interior 14 (see Fig. 2). As can be seen in Fig. 2, the hollow tube 39 has a guide wall 44, which surrounds an air duct chamber 46 of the air duct 38 in a tube-like manner. The air duct chamber 46 is connected to the housing interior 14 at the free end 40 (through the filter element, as described below). The guide wall 44 can, for example, penetrate the housing 12 through the air inlet opening 34. Preferably, the guide wall 44 projects slightly beyond the housing interior wall 42 and forms the free end 40. To prevent dirt particles or moisture droplets from contaminating the interior of the housing 14, a filter element 48 is arranged on the air duct 38. The filter element 48 is attached to the air duct 38 in such a way that it is positioned inside the interior of the housing 14. In the illustrated example, the filter element 48 is attached to the free end 40 of the air duct 38. As indicated in Figures 1 and 2, the filter element 48 can be designed as a membrane that completely covers the opening of the air duct space 46 of the air duct 38. The filter element 48's placement inside the housing 12 protects it from contamination. However, the filter element 48 is not limited to membrane-like designs. For example, capsule-like filter elements can also be provided, which are inserted into the air duct 38, for example into the air duct chamber 46. The manufacture of the ventilated lighting device 10 can be considerably simplified by injecting the filter element 48 into the air duct 38 during its production using an injection molding process. It is also conceivable that the filter element 48 is welded to the air duct 38, e.g., by ultrasonic welding. The protection of the filter element 48 can be further improved by extending the air guide 38 outside the housing 12 into an air guide duct 50, which is preferably also designed as a hollow tube. Starting from the air inlet opening 34, the air guide duct 50 preferably has an angled path (see Fig. 1). This reduces the direct ingress of splash water or dust onto the filter element 48. It can be advantageous if the air guide duct has multiple angles along its path, for example, several bends 52 (see Fig. 1). An air guide 54 can also be provided for the exhaust opening 36, which serves to guide the air flowing from the housing interior 14 through the exhaust opening 36. The further air guide 54 preferably continues outside the housing 12 in a further air guide duct 56. The air guide duct 56 can also have an angled course (see Fig. 1). The airflow used to ventilate the interior of the housing 14 can be achieved, for example, by providing increased air pressure in the air duct 38. For this purpose, the air duct 50 can, for instance, open into a forward-facing, forward-facing stagnation section, so that increased stagnation pressure is achieved in the air duct 38 due to the movement of the vehicle in the direction of travel. It is advantageous for this to be arranged in a section of the housing 12 located at the front of the vehicle in the direction of travel, as shown, for example, in Fig. 1. However, it is also conceivable that the air duct 38 is connected to a blower system of the vehicle, which provides increased air pressure. The airflow for ventilating the interior of the housing can, however, also have a different path. Accordingly, the lighting device can be designed differently, as is the case, for example, with the lighting device 60 sketched in Fig. 3. This differs from the lighting device according to Fig. 1 in that the air intake opening 34 is provided in the rear section 18 of the housing 12, which is located, for example, at the rear with respect to the direction of travel of the vehicle. The exhaust opening 36 of the lighting device 60 is located in a region of the housing 12 facing the light output section 22. To generate the airflow, the air duct 56, which opens into the exhaust opening 36, can, for example, be connected to a flow device of the vehicle, which creates a negative pressure for ventilation. This draws air into the interior of the housing 14 through the air duct 38. In this case as well, the filter element 48 is arranged within the housing interior 14 on the air duct 38, which is associated with the supply air opening 34. The air duct 38 preferably continues beyond the housing 12 in an angled air duct 50. Through this duct, ventilation air is drawn in through the air duct 38, through the filter element 48, and into the housing interior 14.

Claims

Lighting device (10, 60) for a motor vehicle (motor vehicle) with a housing (12) for delimiting a housing interior (14), wherein the housing (12) has an air inlet opening (34) and an exhaust air outlet opening (36) for the housing interior (14), with an air guide (38) for guiding incoming air through the air inlet opening (34), wherein a filter element (48) is provided such that air flowing in through the air guide (38) can first pass through the filter element (48) and only then into the housing interior (14), wherein the filter element (48) is arranged on the air guide (38) and within the housing interior (14), wherein the filter element (48) is completely enclosed in the housing interior (14), characterized in that the air guide (38) is designed as a hollow tube (39) penetrating the housing wall (42), wherein the hollow tube (39) has a free end (40) exhibits which protrudes into the interior of the housing (14),wherein the filter element (48) is arranged at the free end (40), wherein the filter element (48) is designed and arranged on the air guide (38) such that it completely covers the free end (40) of the hollow tube (39). Lighting device (10, 60) according to claim 1, characterized in that the air guide (38) continues outside the housing (12) and forms an air guide channel (50) that is angled at least once. Lighting device (10, 60) according to one of the preceding claims, characterized in that the filter element (48) is injected or welded into the air duct (38). Lighting device (10, 60) according to one of the preceding claims, characterized in that a further air guide (54) is provided for the exhaust opening (36) for guiding air flowing out of the housing interior (14) through the exhaust opening (36). Lighting device (10, 60) according to the previous claim, characterized in that the further air guide (54) continues outside the housing (12) and forms an air guide channel (56) that is angled at least once. Lighting device (10, 60) according to one of the preceding claims, characterized in that the filter element (48) is designed to filter out dirt, dust and / or moisture droplets.

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