Patent Publication Number: US-9899207-B2

Title: Vibration resistant automotive front lighting lamp

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a § 371 application of International Application No. PCT/EP2014/070741 filed on Sep. 29, 2014 and entitled “Vibration Resistant Automotive Front Lighting Lamp,” which claims priority to European Patent Application No. 13187951.2, filed Oct. 9, 2013. Both PCT/EP2014/070741 and 13187951.2 are incorporated herein. 
     FIELD OF THE INVENTION 
     The invention relates to an electrical lamp, and in particular to a lamp for use in automotive vehicle front lighting. The invention further relates to a vehicle headlight. 
     BACKGROUND OF THE INVENTION 
     Automotive headlights, i.e. headlights for use on board of a vehicle, such as e.g. a car, motorcycle, truck or other type of vehicle generally comprise a reflector and, mounted therein, a lamp. Known incandescent lamps, in particular halogen lamps, generally comprise a base and a burner. The base provides mechanical and electrical connection to the automotive headlight, whereas the burner comprises the actual light-emitting element, in particular filament. Light emitted from the filament is reflected by the reflector to form a beam for illumination in front of the vehicle. 
     Different types of incandescent lamps are known, which comprise one or more filaments arranged within a vessel. 
     SU431581A1 describes a lamp with a tubular bulb and a part which serves for securing the filament including a shield. To improve the dynamic stability of the lamp and reduce the amount of dazzle, the shield includes a flat member shown to be arranged perpendicular to the axis of the filament which engages the inner side surface of the bulb at several positions. The size of the member corresponds to the inner diameter of the bulb and acts as a guide when being inserted in the lamp. The member automatically centers the lamp stem along the axis of the bulb and restricts vibration of the shield inside the bulb when subjected to dynamic loads. The shape of the member is chosen such that it does not prevent the halogen cycle. 
     SUMMARY OF THE INVENTION 
     According to an aspect of the invention, a lamp according to claim  1  and a vehicle headlight according to claim  11  are proposed. 
     A lamp according to an aspect of the invention comprises a base for mechanical and electrical connection to an automotive headlight. Electrical contacts may protrude out of the base, in particular from the rear thereof. The base further preferably comprises a positioning ring which serves for mounting the lamp in a reflector of a vehicle headlight in a defined position and orientation. The positioning ring may comprise radial protrusions, which may serve for mechanical fixing, and for exact positioning. It is in particular preferred to provide one reference protrusion to define a radial reference direction R. 
     The lamp further comprises a burner with a sealed vessel, at least partially transparent, preferably of quartz glass. According to the invention, at least a first filament is arranged within the vessel. In preferred embodiments, a second filament may be arranged within the vessel, provided at a distance from the first filament. Preferably, the filaments are spaced along the longitudinal axis X of the lamp, i.e. the axis extending centrally through the positioning ring. 
     According to one aspect, a baffle is arranged proximate to a first filament. As will become apparent in connection with preferred embodiments, the baffle may in particular be arranged to cover the axial range of the first filament, i.e. be arranged in radial directions of the first filament along the whole axial length thereof. Thus, a portion of the light emitted from the first filament, emitted into spatial directions of the proximate baffle, will be shaded by the baffle. 
     At least one holding wire is arranged within the vessel. In preferred embodiments, two or three holding wires are provided. The holding wires may be fixed in a pinch seal of the vessel, and may project into its interior. At least one of the holding wires may serve to hold the baffle in its position proximate to the first filament. The baffle may be fixed to the holding wire, preferably welded thereto. Further, the first and second filaments may be fixed to the holding wires. 
     According to an aspect of the invention, the transparent vessel comprises a vessel wall which includes a cylindrical portion surrounding at least the first filament. According to an aspect of the invention, a support member is provided which is fixed to the baffle or to the holding wire. The support member includes at least a first part that is fixed to the baffle or holding wire, and a second part that is in contact with the cylindrical portion of the vessel. The support member further comprises at least one flexible intermediate part connecting the first and second parts, so that the baffle or the holding wire are resiliently supported against the vessel. 
     The thus formed resilient support does not completely immobilize the baffle within the vessel, but retains a certain movement, while at the same time resiliently restricting the movement. Under the influence of forces of inertia caused e.g. by vibration, the baffle and the holding wire may still move within and relative to the vessel, but the movement will be significantly less than without the support member. Thus, the lamp will be more resistant to vibration. 
     According to preferred embodiments, the support member may include a first and a second flexible intermediate part or leg, and each of the legs will comprise a second part in contact with the cylindrical portion. The second part of the first and second flexible legs may be arranged on the inside of the vessel at different positions distant from each other. 
     In a preferred embodiment, the second part is in one-sided contact with the interior of the vessel. Thus, preferably, the support member is not fixedly attached to the interior of the vessel. This facilitates manufacture of the lamp and allows a substantial degree of remaining flexibility. 
     According to a different embodiment, the flexible support member may be made out of a wire material, or out of a flat metal material. The material of the flexible support member may preferably be molybdenum. The metal material may be stamped and bent. In one embodiment, the flexible support member may even be formed in one piece with the baffle. 
     In a preferred embodiment, the flexible support member is positioned to be shaded from the first filament by the baffle. Thus, the support member, located behind the baffle as viewed from the first filament, will not lead to significant optical distortion. 
     According to a preferred embodiment of the invention, at least three holding wires are arranged to project into the interior of the vessel. The first filament, preferably also a second filament and the baffle are fixed to the holding wires. A pinch seal is formed at a portion of the vessel, sealing the vessel and embedding the holding wires. Thus, the holding wires extend from the pinch seal into the interior of the vessel. Further, a holding bar is arranged within the interior of the vessel, distant from the pinch seal. The holding bar serves to hold the holding wires, preferably by at least partially enclosing the wires within the material of the holding bar. The holding bar is preferably made out of glass. 
     According to one embodiment, the base comprises three electrical contacts, and three holding wires are arranged extending from a pinch seal into the interior of the vessel. Each of the holding wires is electrically connected to one of the electrical contacts. The first filament is electrically connected between a first and a third holding wire, and the second filament is electrically connected between a second and the third holding wire. Thus, the filaments share a common electrical connection. Preferably, the first filament is not connected directly to the third holding wire, but electrical contact is established via the baffle fixed to the third holding wire. 
     In preferred embodiments, the baffle may be of concave shape, e.g. provided in one piece and made out of correspondingly shaped sheet metal, in particular molybdenum. A front surface of the baffle may be arranged at a front axial end of the baffle, preferably the end facing towards the base, arranged at least partially in between the filaments. Thus, the baffle may be effective to shield the second filament from light emitted from the first filament. The baffle then serves to separate angular ranges illuminated by both filaments from angular ranges illuminated only by the second filament, where light emitted from the first filament is shaded at the baffle. Corresponding portions of the reflector may be shaped to reflect light emitted from the first filament which may be denoted a low beam filament into a first beam (low beam, comprising a bright/dark cutoff) and correspondingly reflect light emitted from the second filament (e. g. high-beam filament) into a reflected beam (high beam) without a bright/dark cutoff. 
     According to a further aspect, a vehicle headlight with a reflector may be equipped with a lamp according to one of the above aspects. In particular, the vehicle headlamp may be a motorcycle headlamp. 
     These and other aspects of the invention will become apparent from and elucidated with reference to the embodiment described hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings 
         FIG. 1  shows a perspective view of a lamp according to a first embodiment of the invention. 
         FIG. 2  shows a side view of the lamp of  FIG. 1  in the horizontal operating position. 
         FIG. 3  shows an enlarged perspective view of a portion of a lamp according to a second embodiment. 
         FIG. 4  shows an enlarged perspective view of a portion of a lamp according to a third embodiment. 
         FIG. 5  shows in a schematic representation a vehicle headlight with a lamp according to  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       FIGS. 1, 2  show a first embodiment of an automotive halogen lamp  10 . 
     The lamp  10  comprises a base  12  and a burner  14  fixed to the base  12 . 
     The base  12  comprises a positioning ring  16  which includes three positioning protrusions  18   a ,  18   b ,  18   c  radially protruding from the base  12  (of which only two are shown in  FIG. 1 ). 
     The lamp  10  may be fixed to a vehicle headlight  50  as symbolically shown in  FIG. 4 . A protrusion  18   c  (shown in  FIG. 2 ) serves as a reference protrusion defining a radial reference direction R. A reference plane is defined by the upper portions of the positioning protrusions  18   a ,  18   b ,  18   c  of the positioning ring  16 . A longitudinal axis X of the lamp  10  is defined to run through the center of the positioning ring perpendicular to the reference plane. A symmetry plane may be defined by the radial reference direction R and the longitudinal axis X. 
     The burner  14  comprises a glass vessel  22  of quartz glass material with a central portion  24  of generally circular cylindrical shape. At the top, the otherwise transparent vessel  22  comprises a coated portion  26  which is opaque. At the bottom, the vessel  22  is sealed in a pinch seal  28 , which is fixed to the base  12 . 
     Projecting from the pinch seal  28  into the interior of the vessel  22  are three holding wires  30   a ,  30   b ,  30   c . The holding wires  30   a ,  30   b ,  30   c  are further fixed by a holding bar  32  made out quartz glass material and arranged distant from the pinch seal  28 . The holding wires  30   a - 30   c  are embedded within the material of the holding bar  32 . Further, fixed to the holding wires  30   a ,  30   b ,  30   c  are arranged a first filament  34  (low-beam filament, not shown in  FIG. 1 ) and a second filament  36  (high-beam filament). 
     Proximate to the first filament  34 , a baffle  40  is arranged, welded to one of the holding wires  30   c . As shown, the baffle  40  is provided to cover the axial extent of the first filament  34  and thus partially shield light emitted from the filament  34  into radial directions. Further, a front portion  42  of the baffle  40 , shown in  FIG. 2 , is arranged in between the first and second filaments  34 ,  36  and therefore serves to shield the filaments  34 ,  36  from one another. 
     As also shown in  FIG. 2 , the first, low beam filament  34  is connected at one end to a first holding wire  30   a  and at the other end to the baffle  40 , which is welded to the third holding wire  30   c . The second, high-beam filament  36  is fixed to a second holding wire  30   b  and to the third holding wire  30   c . By these connections, the filaments  34 ,  36  are both mechanically held at defined positions within the vessel  22  and are electrically connected between the holding wires  30   a ,  30   b ,  30   c . The holding wires, in turn, are connected internally within the base  12  to electrical contacts  20  protruding from the lower portion of the base  12 . Thus, the filaments  34 ,  36  may be operated by supplying electrical power at the electrical contacts  20 . 
     The filaments  34 ,  36  are each provided as a single winding structure of filament wire wound around a straight filament axis. An axis of the first filament  34  and an axis of the second filament  36  are arranged in parallel to the longitudinal axis X of the lamp  10 . 
     The baffle  40  comprises a bottom surface  41  from which a front surface, a back surface, and side surfaces extend, which terminate in side edges  48 . At the back surface, an attachment tab  52  is integrally formed. The attachment tab  52  serves to connect the filament wire of the first filament  34  to the baffle  40 . As shown, the filament wire of the first filament  34  is welded to the attachment tab  52 . 
     As shown in  FIG. 1 ,  FIG. 2 , a support member  38  is attached to the lower surface  41  of the baffle  40 . The support member  38  is made out of a stamped and bent piece of sheet metal material. It comprises a central bar  39  connected to outer bars  43  by legs  37 . 
     As shown in  FIG. 1 ,  FIG. 2 , the outer bars  43  lie flat against the inner surface of the wall of the vessel  22  within the cylindrical portion  24 . 
     The legs  37  are flexible, so that the baffle  40 , attached to the central bar  39  is resiliently supported on the interior surface of the vessel  22 . Thus, external forces acting on the baffle  40  due to vibration will still lead to movement of the baffle  40  relative to the vessel  22 , however, the movement of the baffle  40  will be limited by the resilient support  38  which rests on the inside of the vessel  22 . 
     As shown, the support member  38  is provided at the back side  41  of the baffle  40 , and is thus shaded from the first filament  34  by the baffle  40 . Consequently, no optical distortion is caused by the support member  38 . 
       FIG. 3  shows a part of a lamp according to a second embodiment. The lamp according to the second embodiment differs from the lamp  10  described above only with regard to a different support member. Thus, in the following description only the different support member will be explained in detail for the second embodiment, and like parts of the lamp according to the second embodiment will be designated by like reference numerals. 
     In the second embodiment as shown in  FIG. 3 , a support member  138  is formed as a tab integral with the baffle  40 . In the example shown, the tab  138  is formed at one side of the attachment tab  52 . The tab  138  serving as support member has a flexible leg  137  extending up to the interior of the vessel  22 , of which an end  143  rests resiliently against the interior surface thereof. 
     A further embodiment of a lamp is shown in  FIG. 4 , which differs from the previous embodiments by a still different support member. In the following description only the different support member will be explained in detail for the third embodiment, and like parts of the lamp according to the third embodiment will be designated by like reference numerals. 
     In the embodiment according to  FIG. 4 , a support member  238  is provided as a wire clamped to the attachment tab  52  of the baffle  40 . The wire may be made out of tungsten, or preferably molybdenum. The end of the attachment tab  52  is bent to hold the wire  238  which projects to both sides as flexible portions  238   a ,  238   b , the ends of which are resiliently pressed to the interior of the glass vessel  22 . 
     The lamp with a support member  238  may be manufactured especially easily, because the wire  238  may be provided with a length slightly longer than the diameter of the vessel  22 . As the holding wires  30   a ,  30   b ,  30   c , the baffle  40  and the filaments  34 ,  46  are inserted into the glass sleeve  22 , the wire  238  resiliently bends and the ends abut against the interior of the vessel. The wire  238  may be provided initially straight, such that the bend at the ends  238   a ,  238   b  is formed by insertion. This initial straight form may in particular be used for a wire of lower diameter and resulting lower resilient forces acting on the interior of the vessel wall. Alternatively, in particular for a wire of larger diameter, the wire may be pre-bent at the ends to facilitate insertion into the vessel  22 . 
     The lamp according to the third embodiment also shows good vibration resistance. The resilient contact of the ends of the wire  238  on both sides against the vessel  22  stabilizes the baffle  40 , while the flexible nature of the bent ends  238   a ,  238   b  still allows flexibility. 
       FIG. 5  shows schematically a headlight  50  where the lamp  10  as described above is schematically shown arranged within a reflector  46 . Light emitted from the filaments  34 ,  36  (not shown in  FIG. 3 ) is reflected by the reflector  46  to form different illumination beams. Light from the second (high-beam) filament  36  is shown as a dotted line to be reflected by both the upper and lower part of the reflector  46  to form a high-beam without a bright/dark cutoff. 
     Light emitted from the first low-beam filament  34  is shown as a dashed line to be partially shielded by the baffle  40  such that only an upper portion of the reflector  46  is illuminated. The upper portion of reflector  46  is shaped to reflect the light from the first filament  34  to form an illumination beam with a horizontal bright/dark cutoff. In the resulting low beam, there is no distortion from the support member  38 , because of the position thereof behind the baffle  40 . 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiment. 
     Variations from the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims the word “comprising” does not exclude other elements, and the indefinite articles “a” or “an” do not exclude a plurality. 
     The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.