GB2482910A - Vehicle lamp - Google Patents

Abstract

A vehicle lamp 2 comprising a housing 4 with at least one first, at least partially transparent or translucent, housing piece 6 and at least one second housing piece 8, wherein first housing piece 6 and second housing piece 8 are mounted to each other, and at least one light source mount (10, figure 2), wherein a venting gap (12, figure 2) is formed between first housing piece 6 and second housing piece 8.

Description

Vehicle lamp The invention relates to a vehicle lamp, particularly a lamp for a car. The vehicle lamp comprises at least two housing parts and condensation reduction means.

Condensation is a common problem in vehicle lamps.

One prerequisite of condensation is the existance of humidity in the inner volume of the lamp. Condensation will occur at the coldest surfaces of the lamp. In mounted condition, these are usually the outwardly oriented surfaces. Condensation is therefore most likely to be strongest at surfaces oriented to the exterior of the vehicle. Those areas are necessarily at least partly transparent or translucent.

Condensation on transparent or translucent surfaces of the vehicle lamp has an impact on the brightness of the lamp due to light reflection and light scattering.

Different condensation reduction measures and means are known in the art. One known way is to use anti-condensation coatings at sensitive areas. Those coatings require additional manufacturing steps and materials and increase the costs of goods. Further, the coatings lose effectiveness with the time and their overall efficiency is limited.

Further, the use of closed systems is known. Those closed systems need sealed surfaces that may lose tightness in worn state. The sealings and materials have to work in a wide temperature range. Exchange of light bulbs may also be difficult in those systems.

Another technology known in the art is the use of ventilation holes in the surfaces. Those ventilation holes may have a negative optical impression and may have drawbacks in, e.g., heavy rain where they may be an entry for water into the interior of the housing.

EP 0 587 502 Bi discloses a motor vehicle headlamp, the components of which together define an essentially closed internal space, which headlamp comprises at least two passages for ventilating the said internal space, connecting this space with the outside. At least one of the two passages is provided with a mobile wind-sensitive element, capable of at least reducing the cross-section of the said passage in the presence of a relative wind created by the movement of the vehicle. This should allow to produce ventilation through two passages when at rest and ventilation through a single passage during driving.

It is therefore an object of the invention to improve on the lamps known in the art such that the drawbacks are at least partially eliminated or mitigated. It is particularly an object of the invention to provide a vehicle lamp that has effective anti-condensation measures that are easy to facilitate and that do not have a negative impact on the appearance of the lamp.

The object of the invention is solved by a vehicle lamp as described in claim 1. Further embodiments of the invention are described in dependend claims.

A vehicle lamp according to the invention comprises a housing with at least one first at least partially transparent or translucent housing piece and at least one second housing piece. ,,At least partially" according to the sentence before can relate to the degree of transparency or translucency on the one hand and to the area that is transparent or translucent.

The first housing piece and the second housing piece define an inner volume of the vehicle lamp. The first, at least partially transparent or translucent housing piece and the second housing are mounted to each other. The vehicle lamp comprises at least one light source mount.

According to the invention, a venting gap is formed between first housing piece and the second housing piece.

The vehicle lamp is therefore basically an open system.

The design of the vehicle lamp allows for easy construction and manufacturing. A coating as often used

in the prior art is not necessary. Further, the

transparent or translucent surfaces can be designed free of ventilation holes.

In a vehicle lamp according to the invention, condensation is removed using a stream of air. The air stream may be generated by air heated and accelerated at the light source that is guided along the inner surface of the at least partially transparent or translucent housing part to the gap.

The warm air will have at least two effects. First, it will heat the at least transparent or translucent surfaces so that humidity won't condensate there. Second, the air stream will take away already existing condensated water by exerting force and by evaporating the humidity. The humidity will be carried away through the gap.

In a first further embodiment, the venting gap has a length of 2 to 20 cm, preferably 3 to 15 cm. This will allow for laminar flow of air along the inner surface of the first housing part.

In a further embodiment, the venting gap may have a width of 2 mm to 6 mm, preferably 3 mm to 6 mm, preferably 5 mm. This will, on the one hand, reduce the potential entry of water and dirt from outside of the lamp and, on the other hand, allow a smooth design.

In a further embodiment, the second housing piece may be designed as an inner lens or as an inner reflector.

The inner lens or reflector can be used to guide and shape the light as desired. No separate inner lens or reflector will be needed to assemble the vehicle lamp.

In a further embodiment, an inner surface of the first housing piece may comprise a continuous surface towards the gap forming end of the housing. Therefore, this embodiment will allow a free flow of the air stream along the inner surface of the housing piece and will therefore improve the ability to remove condensation on the respective surface and the efficiency of the design.

In a further embodiment, the inner surface of the housing piece may comprise air guiding means. These air guiding means may be arranged such that the air stream created inside the housing is present in areas where condensation occurs. The guiding means may be designed as cavities or protrusions, as ribs or as neps.

In a further embodiment, the light source mount may be arranged at the second housing piece. This will reduce the necessary part count for the vehicle lamp and save costs. If the second housing piece is further designed as a lens or reflector, proper arrangement of the light source relative to the lens or reflector can be ensured.

In a further embodiment, the first housing piece may be free of open through holes in mounted condition. This will reduce penetration of water in the inner volume of the vehicle lamp.

In a further embodiment, the vehicle lamp may be a rear lamp. The vehicle lamp may also be a headlight.

In a further embodiment, the gap may be oriented in driving direction. This improves air flow within the inner volume.

The invention will be explained in greater detail with reference to the figures, whereby: Fig. 1 shows a vehicle lamp according to the present invention shown in an three dimensional angular view partly in driving direction; Fig. 2 shows the vehicle lamp of Fig. 1 in a three dimensional angular view partly against driving direction, and Fig. 3 shows the vehicle lamp of Fig. 1 in a three dimensional view partly against driving direction in another viewing angle than Fig. 2 indicating air flow.

Figure 1 shows a vehicle lamp 2 according to the invention shown in an three dimensional angular view partly in driving direction. The shown vehicle lamp 2 is a rear lamp of a car.

The vehicle lamp 2 comprises a housing 4 that is built of two housing pieces, a transparent first housing piece 6 and a second housing piece 8. First and second housing pieces 6, 8 are mounted to each other by known mounting means, e.g., screws or snap-fit.

The second housing piece 8 is designed as a lens that shapes light exerted by a light source, e.g. a light bulb. The light source is not shown in Figure 1.

Figure 2 shows the vehicle lamp 2 in a three dimensional angular view partly against driving direction.

The second housing piece 8 comprises light source mounts 10 where light sources can be mounted in a defined position and/or orientation relative to the second housing piece 8. The light exerted from the light sources is shaped by the second housing piece 8 in a predefined manner.

A gap 12 is formed between first housing piece 6 and second housing piece 8. The gap 12 has a width w of approx. 5 mm and a length 1 of approx. 20 cm. It is therefore narrow and nearly invisible.

Since the first housing piece 6 is positioned outwardly with respect to the car, humidity inside the vehicle lamp 2 will condensate on an inner surface 14 of the first housing piece 6. This will lead to partially blinding of the first housing piece 6 because of light scattering, light reflexion and absorption.

The light sources will start to produce heat as soon as they are switched on. The heat produced leads to an initial stream of air that is directed away from the light sources and to the inner surface 14 of the first housing piece 6. The stream of warm air will remove condensed fluid by evaporation and by displacement. The first housing part will keep it's original and intended optical properties.

As shown in Figure 3, said stream of air, indicated with arrows 16, will flow through the gap 12. Gap 12 further allows intake of fresh air so that the stream of air will continue to flow to provide a clean inner surface 14 of the first housing piece 6.

Depending on shape and design of the respective embodiment, air guiding means positioned in the inner volume of the housing 4 may be useful to increase efficiency of the present invention. The air guiding means may be arranged on the first housing piece and/or the second housing piece. Such air guiding means may be designed as ribs, walls, grooves, neps, detents or other

suitable geometries.

LIST OF REFERENCE NUMERALS

2 Vehicle lamp 4 Housing 6 First housing piece 8 Second housing piece Light source mount 12 Venting gap 14 Inner surface of the first housing piece 16 Air stream