EP0071585A1

EP0071585A1 - Headlight including a device for the dissipation of the heat of the source of light

Info

Publication number: EP0071585A1
Application number: EP82830212A
Authority: EP
Inventors: Mario Bellu
Original assignee: SACEX SpA
Current assignee: SACEX SpA
Priority date: 1981-07-29
Filing date: 1982-07-23
Publication date: 1983-02-09
Also published as: IT1171424B; IT8149009A0

Abstract

A headlight comprising a hollow body (1 or 1a) frontally dosed by a transparent cover (2 or 2a) both made of plastic msterial. The body (1 or 1 a) has an inner parabolic surface (7) adapted to produce a light beam. The body (1 or 1a) is provided with a large central opening (14) through which passes a sleeve (11) for recelving and supporting the screw cap (6) of a lamp (3), said sleeve (111 being a part of a metallic device (8 or 8a) provided with rear fins (10 or 10a) for the dissipation of the heat produced by the lamp (3). The sleeve (11) does not contact the edge of the orifice (14) and is supported by means of arms by an outer annular portion (9 or 9a) of the device (8 or 8a), where means (15) are provided for fixing said annular portion (9 or 9a) to the rear wall of the body (1 or 1a).

Description

The present invention relates to a headlight which may be mounted on any suitable supporting member so as to act as a swinging lighting means for work spots or which could be also mounted on a motor vehicle so as to act as lighting lamp in order to light up the vehicle travel, i.e. it can be used as a lamp of common type or also as a fog light. Said headlight is of a type in which the source of light has a considerable power: in particular, it could be a halogen lamp, in which the emitted heat is very ligh.
Up to date the headlights of this kind have been entirely constructed in metal, owing to the very high heat which such a source of light produces. In fact if syntetic materials would be used, the walls of the lamp could be easily and rapidly damaged and deformed. But the construction of a headlight made of metal is very expensive, owing to the material cost as well as to the high working cost for the construction and application of the fastening means and the like thereto.
In contrast the present invention provides to construct the headlight body as well as the fastening means for the connection of the headlight to a support device, made wholly of a plastic material; as a result thereof by a simple moulding process the headlight casing can be shaped as a single body together with its fastening means as well as its reflecting surface, which can be made then reflecting by an application of a suitable paint or a metallized layer.
Plastics have been really already utilized for headlight construction, but only for lamps of low power, as the small lamps for bycicles and the like, wherein the source of light has always a very modest power, so that said lamps produce a very reduced heat emission. On the contrary, this known solution could not be applied to the construction of powerful headlights as those of the motor vehicles or those used as work headlights, since in these conditions the plastics material could not be able to windstand. On the contrary, the present invention permits to realize headlights of high light power, made of plastics by mounting the electric lamp up on a metal device, placed substantially behind the back of the headlight and which is designed to support the lamp in such a manner that the heat produced by said lamp can be substantially wholly absorbed by its metal body and diffused in the atmosphere by means of fin system, while the headlight body is connected only by screws to the said device for the heat absorption and diffusion and never in any point directly to the lamp body.
As a result thereof the headlight body and the respective cover element can be constructed in plastics, since they are no more subjected to any heating effect so that they have a long life, are easy constructed, do not require any outer paint or plating, since they are not subjected to any oxidation, as on the contrary takes place with the use of metal headlights; in addition they have also a reduced cost. These and other characteristics and advantages of the present invention will be better understood from the following description of two embodiments of the headlight, in particular, of the type designed to be mounted on motor vehicles. In the drawings:

Figure 1 shows a front view of a headlight for motor vehicles, in which the reflecting surface is shaped as a rotation parabolid;
Figure 2 is a side exploded view of the components of the headlight, with a partial section of the rear portion of the headlight body as well as with an axial section of the device for the dissipation of the heat according to this invention; the source of light or lamp has not been shown, since this latter is conventional;
Figure 3 is the back view, in enlarged scale, of the device for the heat absorption and dissipation, aloof from the other components;
Figure 4 shows the rear view of a second embodiment, in which the inner reflecting surface is shaped as a parabolic cylinder; and
Figure 5 is an explosion side view of the components of the headlight with partial section of the headlight body and with an axial section of the device for the absorpion and dissipation of the heat.

Now referring to the Figures 1 to 3, the headlight is constituted of a hollow body 1 having the shape of a paraboloid of rotation about the axis X-X; said body 1 is provided with a cover member 2 made of trasparent material of a type adapted for a light diffusion and having "per se" well known characteristics. The body 1 and the cover 2 are of conventional configuration, but at least the body 1 is constructed by a moulding process in plastics so that it can be obtained in its final shape and does not require any outer application of paints or other protection coverings. In addition, the body 1 can be made integral with one of the hinge elements, i.e. the element 12a of an articulation hinge designed to allow to adjust the orientation of the light beam, while the other hinge element 12b will be made integral with at least one support means 5. The inner parabolic surface 9 of the body 1 will be covered by a reflecting paint 7 or a bright metallized coating will be applied thereon, so as to make this surface reflecting. The cover member 2 will be fastened to the body 1 by an adhesive medium of such a type that it can ae easily removed, or by means of connection means which will be elastically force inserted owing to the Light elastic deformability of the used material thereof, thus eliminating the use of the conventional netal spring clips which easily rust and become quickly inefficient. At the central part of the body 1 a circular opening 14 is arranged coaxial to the axis X-X and larger than those holed which are provided in the conventional headlight, since according to this convention, the lamp, not shown in the first embodiment, is not directly supported by the body 1, but it is inserted in and carried by the device 8 fastened to the body 1. For such a purpose the device 8 is made of a thermally conductive metal; this device 8 comprises a peripheral annular portion 9 having a system of parallel fins 10 designed to promote the dissipation of the heat into the atmosphere, said fins 10 being provided on the rear surface of the device 8, but the front part of this latter is shaped so as to be able to made the back surface of the body 1, to which the device 8 is fixed by means of screws inserted in pairs of coaxial holes 16a, 16b arranged in the body 1 and in the portion 9 of the device 8 respectively. This device 8 further comprises an axial tubular sleeve 11 supported by radial arms 13 by the annular portion 9 of lhe device 8 and which has an outer maximum diameter slightly shorter than that of the central opening 14, so as to be able to enter passing through said orifice 14, without any direct contact with the edge of this latter. The sleeve 11 has an inner conduit so shaped as to be able to receive and house the screw cap 6 of the bulb of the lamp 3 which is of a known type.
Thus according to this invention the lamp is supported only by the metallic device 8 by means of the sleeve 11 thereof so that the heat produced by this lamp 3 is transmitted to the body 11, 9 only and will be substantially nearly wholly dissipated through the fin system 10, while the headlight body 1 remains substantially free from any thermal effect. The embodiment of Figures 4 and 5 is subtantially equivalent to the first one. It concerns only an application of the invention to a headlight, in which the inner surface 4a is provided with a reflecting coating 7 and has the shape of a parabolic cylinder. Thus the equivalent parts are indicated with the same references, while the similars parts are differentiated by a letter. In this case the body la, when seen form the front, has a rectangular outline so that the transparent cover 2a will be of a rectangular shape. The device 8a thus comprises a peripheral portion 9a provided with a large central orifice through which extends forwards a sleeve 11 identical to the preceding one, said sleeve 11 being carried by arms 9a and being designed to house the screw cap 6 of the lamp 3. The body la is constructed in a single piece together with the hinge element 12a, while the hinge element 12b (not shown) which is designed to cooperate with the preceding one is made integral with a connection means (not shown in Figures 4 and 5), provided for the fixing of the headlight la to a headlight support (not shown). From the rear surface of the device 8a extend outwardly a plurality of radial fins 10a operatively equivalent to the fins 10. The operation of the headlight la according to this second embodiment is identical to that which has been shown and described in detail, with reference to the first embodiment.

Claims

1- A headlight including a device for the dissipation of the heat emitted from a source of light, in particular a lamp, and consisting of a hollow body which internally defines a parabolic reflecting surface (4), said body having a central orifice through which passes the screw cap of the lamp and further having connections means (5) for connecting the headlight to a support (5) therefore, said headlight being provided with a front cover member made of transparent material and so shaped as to be able to produce a light diffusion of the beam of the light rays, characterized by the fact that the hollow body (1 or la) and optionally also the cover member (2 or 2a) are made of plastics by a moulding process, while the parabolic surface (4 or 4a) is made reflecting by means of a paint or a metalized layer (7) applied thereon, said lamp (3, 6) being carried by a coaxial device (8 or 8a) which is so shaped as to receive and house the screw cap (6) thereof, the device (8 or 8a) being made of metal of a thermally conductive type and comprises a peripheral portion (9 or 9a), the front surface of which is so shaped as to mate the rear surface of the body (1 or la), while on the back part of said device (8 or 8a) a plurality of fins (10 or lOa) is provided, said peripheral part (9 or 9a) being made integral with a central sleeve (11), which projects through the central orifice (14) of the body (1 or la) and is designed to support the lamp (3) and to receive the screw cap (6) thereof.

2- A headlight according to claim 1, wherein said headlight (1 or la) is connected to the support (5) by means of an articulation hinge (12a, 12b) provided to permit to adjust the position and orientation of the headlight (1 or la), the hinge element (12a) being made . integral with the body (1 or la) and the other hinge elment (12b) are made integral with the support (5).

3- A headlight according to claim 1, wherein the body (1) has at least its inner surface shaped as a paraboloid of rotation having the axis X-X, while the peripheral portion (9) of the device (8) has its front surface shaped as a substantially spherical cap, while from the rear surface of said device (8) a plurality of parallel fins (10) extends outwardly, said peripheral portion (9) being connected to the central sleeve (11) by means of radial arms (18), while in the facing surfaces of the bodies (1 and 8) holes (16a and 16b) are respectively arranged to receive locking screws (15) in order to connected the portion (9) of the device (8) to the rear part of the body (1).

4- A headlight according to claim 1, wherein at least the inner surface (4a) of the hollow body (la) is shaped as parabolic cylinder coating with a reflecting layer (7), while the device (8a) includes a peripheral annular portion (9a), the front surface of which is so shaped as to mate the rear surface of the body (la), while the rear portion of the device (8a) is provided with a crown of radial fins (10a).