A DEVICE ARRANGED TO BE PROVIDED IN FRONT OF A HEADLAMP OF A VEHICLE

Abstract: The present invention relates to a device arranged to be provided in front of a headlamp lens (4) of the vehicle, wherein the device comprises a film (6) of a transparent material. The film (6) is arranged to form a heat-insulating layer in front of the lens (4) to protect it against rapid temperature variations, which otherwise may lead to cracking of the lens. The film (6) may comprise a thermoplastic polyurethane elastomer, which has such properties that it also protects the lens (4) against external mechanical wear. The device also comprises markings (7, 8) which are arranged to facilitate the positioning of the film (6) on the lens (4).

Description: A device arranged to be provided in front of a headlamp of a vehicle TECHNICAL FIELD OF THE INVENTION AND PRIOR ART. The present invention relates to a device arranged to be provided in front of a headlamp lens of a vehicle, wherein the device comprises a film of a transparent material. A problem with headlamp lenses of vehicles is that the lens is exposed for rapid temperature variations, wherein the lens in unfavourable cases may crack. These rapid temperature variations arise in the lens, for example when the headlamp lens is heated to a high temperature by the lightening unit and a cold liquid in form of a windscreen washer fluid or the water in a washing equipment chills the lens rapidly. This is a great problem in connection with commercial traffic with, for example, busses, which leads to heavy expenses for the bus companies. Stones throwing up from the road and other mechanical wear on the headlamp lenses are other problems, which lead to damages and accompanying repairs. FR 2 663 568 A shows the possibility of attaching a film of an anti- adhesive material, as for example polytetrafluoroethylene to the windscreen, windows and headlamps of a vehicle in order to reduce the adherence of raindrops, insects etc to these lens surfaces. Furthermore, in the document is specified that an additional effect, which is obtained by such a film is that it protects the windscreen by soften impacts, which arise due to, for example, stones throwing up from the road, and in that it prevents the windscreen from be splintered by heavy impacts. In this document the above mentioned problem is not mentioned, which arises during rapid temperature variations in the lens. Furthermore, polytetrafluoroethylene is an expensive sort of plastic and it will probably not have such heat insulating properties that it solve the above mentioned problem. GB 2 192 450 A shows a shield for a headlamp lens, which is designed of a transparent plastic material. The shield is provided in front of the headlamp lens by distance elements and arranged to protect the headlamp lens from damages, which may arise from stones and other hard objects throwing up from the road. This shield is not arranged to and has no such properties protecting the headlamp lens against rapid temperature variation. SUMMARY OF THE INVENTION The object of the present invention is to provide a device defined initially, which protects the headlamp lens of a vehicle against rapid temperature variations so that the lens does not crack. This object is obtained according to the invention by the device defined initially, which is characterised in that the film is arranged to form an heat insulating layer in front of the lens to protect it against rapid temperature variations. By such a heat-insulating layer in front of the lens, cold liquids like windscreen washer fluid and water in a washing equipment do not immediately hit the surface of the lens. Consequently, the lens is more slowly chilled by the very favourable heat insulating properties of the film. Advantageously, such a film also has such properties that it is able to protect the lens against external mechanical wear. Thereby, the film is an effective protection against, for example, stones throwing up from the road. When the lens is crashed by greater external mechanical wear, the film keeps the broken lenspieces together so that they not are spread out on the ground. According to a preferred embodiment of the invention, the film is arranged to be attached to a surface of the lens. This may be performed by attaching the film to the lens surface by means of a transparent attachment means. Such an attachment means may be a glue or an adhesive of a suitable kind. In order to facilitate the mounting of the film onto the surface of the lens, the film may be self-adhering. Thereby, the film may comprise an already pasted surface, which is provided with a protective film arranged to be withdrawable before the attachment of the film to the lens surface. Other possibilities may be the attachment of the film immediately to an already pasted lens surface by being pressed against it or being attached electrostatically against it. According to a preferred embodiment of the invention, said films are manufactured to suit different types of headlamp lenses. Thereby, the outer dimension of the film may be adapted to the outer dimension of the lens. In order to facilitate the mounting of the film on the lens, the film may comprise at least one marking for the positioning of the film. Such a marking may comprise a line extending inside of the outer edge of the film and which is arranged to be provided inside the outer periphery of the headlamp lens during the attachment of the film. Such another marking may comprise an essentially dotted marking, which is arranged to be positioned centrally on the headlamp lens during the attachment of the film. Such markings make a quick and effective positioning of the film on the headlamp lens possible. Thereby, following adjustments, with deteriorate adhesive capacity of the adhesive means, are avoided possibly. In order to make it possible to mount the film on non-planar lens surfaces, the film may comprise at least one of a cut through the material and a breakable material weakening, which is arranged to enable the adjustment of the film to a non-planar surface of the lens. Said material weakening may be provided by a line or an area of the film in order to enable said adjustment. In the case that said material weakening is a line the remaining film may overlap the film lying adjacent to this broken line. Thereby, in case that said material weakening comprises an area, which consequently is removable from the film, the film may form a shape, which is arranged to be adaptable to a certain type of headlamp lenses. A film may also be provided with a plurality of such a removable areas in order to be adaptable to several types of headlamp lenses. According to another embodiment, the film may have a curved shape, preferably dome-shaped. Such a shape may be provided, e. g. by vacuum suction in a mould. According to a preferred embodiment of the invention, the film comprises a plastic material. The film may comprise an elastomer, as it is preferable, that the film has elastic properties during its mounting and for protecting the lens against external mechanical wear. Suitably, the film may comprise a thermoplastic elastomer and especially a thermoplastic polyurethane elastomer. Such a plastic film has excellent heat-insulating properties and forms a good protection against external mechanical wear. Furthermore, such a plastic material is relative cheap to manufacture. The thickness of the film may be varied from 0, 1 mm to 1 ,0 mm. Thereby, the thickness may be dimensioned to obtain sufficient heat insulating properties and a sufficient protection against external mechanical wear. In order to form the film relative thin, the film material may have a coefficient of thermal conductivity, which is less than 0,25 W/m°C. BRIEF DESCRIPTION OF THE DRAWINGS In the following, preferred embodiments of the invention are described by way of example with reference to the attached drawings, in which: Fig 1 shows a side-view of a headlamp and a film according to a first embodiment of the invention. Fig 2A shows a front-view of a film according to a second of the embodiment of the invention. Fig 2B shows the film in Fig 2A seen from the side. Fig 3A shows a film according to a third embodiment of the invention. Fig 3B shows the film in Fig 3A seen from the side. F Fiigg 44AA shows a side-view of a film according to a fourth embodiment of the invention. ig 4B shows a partly sectional view of a mould for the manufacturing of the film in Fig 3. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Fig 1 shows a headlamp 1 of a vehicle. The headlamp 1 comprises a light-generating member 2, which may be a conventional headlamp mounted in a reflector 3, which leads the light from the member 2 through a headlamp lens 4. In order to enable exchange of a defect light-generating member 2, the reflector 3 comprises an opening with a mounting device 5 for the light-generating member 2. During a longer use of the vehicle, the lens 4 is heated by the light-generating member 2 and may obtain a relative high temperature. By supplying a windscreen washer fluid or cold water in, e. g. a washing equipment, to the surface of the lens 4, the lens 4 is rapidly chilled, whereby the risk arises that the lens will crack. Furthermore, according to the invention Fig 1 shows a film 6, which is arranged to be attached on the outer surface of the lens 4. In this case, the film 6 comprises a thermoplastic polyurethane elastomer, which comprises good heat insulating properties. Thereby, a relative thin film of this material forms a heat-insulating layer in front of the lens, which protects it against rapid temperature variations. Since said material has elastic properties, it also forms a protection for the lens against external mechanical wear, such as e. g. stones throwing up from the road. The film 6 is attached to the surface of the lens 4 by means of a transparent attachment means, which may be a suitable glue or an adhesive. In Fig 2A a second embodiment of such a film is shown. In this case the film 6 has a circular outer dimension, which is adapted to a headlamp lens having a corresponding outer dimension. In order to facilitate the mounting of the film 6 on the headlamp lens 4, the film comprises partly a first marking 7, which comprises a line extending inside the outer edge of the film and being arranged during the arrangement of the film on the lens, to be provided inside the outer periphery of the headlamp lens 4. Thereby, an uncomplicated mounting of the film 6 on the headlamp lens 4 is obtained in a simple way. Furthermore, the film 6 comprises a second marking 8, which comprises a dashed cross centrally positioned on the film 6. In connection with an alternative mounting method, this second marking 8 is arranged to be positioned centrally on the headlamp lens, whereupon the remaining portions of the film 6 are attached to the headlamp lens 4. The film 6 is already pasted by a transparent attachment means 10 and comprises a protective film 9, as shown in Fig 2B. The protective film is arranged to be withdrawable before the attachment of the film to the surface of the lens. Because the headlamp lens 4 of a vehicle mostly comprises an outer non-planar surface, the film in Fig 2A is provided with a material weakening 1 1 arranged to be broken or a cut 1 1 through the material. Thereby, the material weakening 1 1 comprises a part 12, which may be removed, wherein the film is adaptable to a non- planar surface of a headlamp lens 4. The material weakening may also comprise a line, wherein the remaining film material, at a broken line, overlaps the adjacent film material along this line. By usual headlamp lenses, the shape of the films may be prepunched with a removed "piece of cake" so that no material weakenings need to be provided. Furthermore, the adaptation of the film 6 is facilitated by its elastic properties, so that the film 6 may be attached to the surface of the lens 4 without unnecessary foldings. In Fig 3A an embodiment of a film 6 is shown, which is arranged to form a heat insulating layer in front of a headlamp lens 4. This film 6 is adapted to a headlamp having an elongated headlamp lens 4. Also in this case, the film 6 comprises a marking 7 for the positioning of the film 6 on the lens 4. In this case, the marking 7 comprises a dashed line extending inside the outer edge of the film 6 and being arranged, during the attachment of the film 6 on the lens 4, to be provided inside the outer periphery of the headlamp lens 4. In Fig 3B the film 6 in Fig 3A is shown, seen from the side. This film 6 also comprises a transparent attachment means 10 and a protective film 9, which is arranged to be withdrawable for the attachment of the film to the surface of the lens 4. In Fig 4A another embodiment of the film 6 is shown, wherein the film 6 has a curved -or a dome-like shape. Preferably, the domelike shape is adapted to the shape of the specific headlamp to which the film 6 is intended to be attached. Fig 4B shows a mould 13 for providing the showed dome-shape of the film 6. The mould 13 has a concave surface 14 over which an essentially plane film of a flexible material is placed. A suction pipe 15 has an opening in the concave surface 14 and is connected to a vacuum pump 16. When the vacuum pump 16 is started, the space between the film 6 and the concave surface 14 may be vacuum sucked and the film will be pressed against the concave surface 14 and obtain the dome-shape shown. The mould 13 may be provided with a heating member 17, which gives the film 6 an elevated temperature during the vacuum suction in order to facilitate the deformation. Also the protective film 9 may get the showed dome-shape during the vacuum suction process. The invention is not in any way restricted to the preferred embodiments showed in the drawings but may be varied within the scope of the claims.

Claims: 8 Claims 1 . A device arranged to be provided in front of a headlamp lens (4) of a vehicle, wherein the device comprises a film (6) of a transparent material, characterised in that the film (6) is arranged to form a heat insulating layer in front of the lens (4) to protect it against rapid temperature variations. 2. A device according to claim 1 , characterised in that the film (6) also is arranged to protect the lens (4) against an external mechanical wear. 3. A device according to any one of claims 1 or 2, characterised in that the film (6) is arranged to be attached to a surface of the lens (4). 4. A device according to claim 3, characterised in that the film (6) is arranged to be attached to the surface of the lens (4) by a transparent attachment means. 5. A device according to any one of the claims 3 or 4, characterised [n that the film (6) is self-adhering. 6. A device according to claim 5, characterised in that the film (6) is provided with a protective film (9), which is arranged to be withdrawable before the attachment of the film (6) to the surface of the lens (4). 7. A device according to any one of the preceding claims, characterised in that the outer dimension of the film (6) is adapted to the outer dimension of the lens (4). 8. A device according to any one of the preceding claims, characterised in that the film (6) comprises at least one marking for the positioning of the film (6) on the lens (4). 9. A device according to claim 8, characterised in that said marking comprises a line (7), which extends inside of the outer edge of the film (6) and which is arranged to be provided inside the outer periphery of the headlamp lens (4) during the attachment of the film (6) to the lens (4). 10. A device according to the claim 8 or 9, characterised in that said marking comprises an essentially dotted marking (8), which is arranged to be centrally positioned on the headlamp lens (4) during the attachment of the film (6). 1 1 . A device according to any one of the preceding claims, characterised in that the film (6) comprises at least one of a cut through the material and a breakable material weakening (1 1 ), which is arranged to enable the adaptation of the film (6) to a non- planar surface of the lens (4). 12. A device according to any one of the preceding claims, characterised in that the film (6) has a curved shape. 13. A device according to any one of the preceding claims, characterised in that the film (6) comprises a plastic material. 14. A device according to claim 13, characterised in that the film (6) comprises an elastomer. 15. A device according to claim 14, characterised in that the film (6) comprises a thermoplastic elastomer. 16. A device according to claim 17, characterised in that the film (6) comprises a thermoplastic polyurethane elastomer. 17. A device according to any one of the preceding claims, characterised in that the thickness of the film (6) is from 0, 1 mm to 1 ,0 mm. 10 18. A device according to any one of the preceding claims, characterised in that the film (6) has a coefficient of thermal conductivity, which is less than 0,25 W/m°C.

Inventors: JONSSON TORD, JONSSON, TORD
Applicants: ABENUM AB, JONSSON TORD, JONSSON, TORD
Application year: 1999
Main classification: B60Q1
IPC codes: B60Q1, F21V15, F21V17