Patent Publication Number: US-6210024-B1

Title: Vehicle lamp

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a vehicle lamp wherein a light source is fitted into a light-source fitting hole formed in a metal reflector disposed within a lamp chamber. More particularly, the invention relates to a vehicle lamp wherein a light source is fixed, by a plastic fixedly holding means, in the light-source fitting hole formed in a metal reflector. 
     2. Related Art 
     As shown in FIG. 7, a projection-type automobile headlamp as an example of the conventional lighting fixture of this type is provided with a light source unit integrating a substantially elliptic reflector  3  fitted with a bulb  4  as a light source, a cylindrical lens holder  5  and a projection convex lens  6  together within a lamp chamber defined by a lamp body  1  and a front cover  2 . Reference numeral Sa denotes a shade for forming a clear cut line of a low-beam. 
     The bulb  4  is structurally formed by integrating a bulb body  4   a  as a light source with a plastic bulb socket  4   b , and a focusing ring  4   c  formed with mating pawls  4   c     1   in its peripheral edge portion is integrated with the outer periphery of the bulb socket  4   b . On the other hand, a ring-like socket fixture  7  formed of synthetic resin is fixed with screws to the edge face of a cylindrical portion  3   b  forming a bulb fitting hole  3   a  in the reflector  3  and a mating groove  8  is formed so that the mating pawls  4   c     1   on the side of the bulb socket  4   b  can be brought into engagement with the mating groove by bayonet coupling between the bulb fitting hole  3   a  and the socket fixture  7 . The bulb  4  is made detachable from the bulb fitting hole  3   a  by turning the bulb  4  (the bulb socket  4   b ). 
     As the conventional projection-type headlamp of this type can be made compact to the extent that a smaller reflector is usable though a large quantity of light is available in comparison with a reflection-type headlamp using a parabolic reflector, the former is increasingly spotlighted and positively utilized for automobile headlamps. 
     However, because the reflector  3  in the aforesaid projection-type lamp is made of metal having high thermal conductivity (generally aluminum die-cast), it suffers from a problem that high temperature resulting from the generation of heat when the bulb  4  is lighted may subject to heat deformation any part of the plastic bulb socket  4   b  or plastic socket fixture  7  which is brought into contact with the reflector  3 . 
     SUMMARY OF THE INVENTION 
     In view of the foregoing problems accompanying the conventional vehicle lamp, it is an object of the present invention to provide a vehicle lamp eliminating the possibility of subjecting to thermal deformation a plastic means for fixedly holding a light source, such as a plastic bulb socket and a plastic socket fixture, in the light source fitting hole of a metal reflector. 
     In order to accomplish the object above, a vehicle lamp according to the present invention includes a cap-like metal reflector opening toward the front end of a lamp chamber, a light source body fixedly held in a light source fitting hole formed in the rear top portion of the reflector by plastic fixing-holding means and disposed in a predetermined position ahead of the reflector, and convection-current forming holes for restraining the reflector from being heated to high temperatures. 
     An air convection current is generated between the inside and outside of the reflector via the convection-current forming holes and this air convection current promotes the heat radiating action of the reflector causing warmed air inside the reflector to flow out through the convection-current forming holes and further preventing heat from accumulating inside the reflector thereby restraining the reflector from heating to high temperatures. 
     Furthermore, as the light receiving area of the reflector is reduced by what corresponds to the convection-current forming holes, the heat transmitted to the reflector due to the direct rays of light and the radiant heat are also reduced and the reflector is restrained from being heated up to high temperatures. 
     Further, according to the present invention, the vehicle lamp that are provided with the convection-current forming holes is formed on the non-effective reflective surface of the reflector. 
     The light distribution of the vehicle lamp is obtained from the light reflected from the effective reflective surface of the reflector, and as the light reflected from the non-effective reflective surface of the reflector hardly contributes to the light distribution of the vehicle lamp, the light distribution of the vehicle lamp remains unaffected even though the convection-current forming holes are provided in the non-effective reflective surface. 
     Furthermore, according to the present invention, the vehicle lamp is such that the convection-current forming holes respectively include a plurality of laterally-long slits formed at predetermined intervals in the direction of an optical axis extending in a direction substantially perpendicular to the optical axis of the reflector; and vertical wall-like heat-radiating fins extending along the respective slits are provided between the adjoining slits. 
     The whole open area of the convection-current forming holes is increased by forming the convection-current forming holes with a plurality of rectangular slits. The heat radiating action of the reflector is promoted by making the convection current active and besides the vertical wall-like heat-radiating fins extending along the respective slits. 
     According to the present invention, the vehicle lamp is such that each of the heat-radiating fins is tilted in a direction substantially perpendicular to the direction of direct rays of light from the light source body in order to have the light reflected backward. 
     Since the direct rays of light emitting from the light source body and passed through the convection-current forming holes are shaded by the heat-radiating fins, a wall forming the plastic lamp chamber is never irradiated with the direct rays of light. Since the direct rays of light from the light source body are reflected backward by the heat-radiating fins, moreover, the intensity of light leaking from the vehicle lamp forward is extremely low and the light distribution of the vehicle lamp remains substantially unaffected. 
     According to the present invention, the vehicle lamp is such that the convection-current forming holes are provided in the upper and lower portions of the reflector opposite to each other. 
     The air warmed in the lamp chamber is made to flow out of the reflector smoothly through the upper convection-current forming holes, whereas the air outside the reflector is made to flow into the reflector smoothly through the lower convection-current forming holes. 
     According to the present invention, the vehicle lamp is such that the reflector is integrated with a projection lens via a cylindrical lens holder, so that region ranging from the inside of the lens holder up to the front of the reflector is substantially closed. 
     The air convection current generated between the inside and outside of the reflector via the convection-current forming holes prevents heat from being accumulated inside the reflector kept substantially closed. 
     A vehicle lamp according to the present invention includes a cup-like metal reflector opening toward the front end of a lamp chamber and a light source body fixedly held in a light source fitting hole provided in the rear top portion of the reflector by plastic fixing-holding means and disposed in a predetermined position ahead of the reflector. Additionally, heat-radiating fins for restraining the reflector from being heated to high temperatures are provided on the outside of the reflector. 
     Since the outer surface area of the reflector is increased to an extent equivalent to the area of the heat-radiating fins, the heat radiating effect is improved. In other words, the heat radiating action of the reflector is promoted and the reflector is restrained from being heated to high temperatures. 
     According to the present invention, the vehicle lamp is such that the fixing-holding means of the light source body is a socket fixture for integrally fixing a bulb socket in the light source fitting hole, the bulb socket being a plastic bulb socket integrated with the light source body as a light emission source and/or a bulb socket integrated with the light source body as a light emission source. 
     As described above, the thermal deformation of the plastic bulb socket and/or the plastic socket fixture can be avoided, and the heat radiating action of the reflector is promoted by the air flow generated inside and outside of the reflector via the convection-current forming holes and direct heat and radiant heat accompanied with a reduction in the light receiving area equivalent to the area of convection-current forming holes is reduced. Moreover, according to the present invention, the heat radiating action of the reflector is promoted by the heat-radiating fins with the effect of restraining the reflector from being heated to high temperatures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view of an automobile headlamp embodying the present invention; 
     FIG. 2 is a vertical sectional view of the headlamp taken along a line II—II of FIG. 1; 
     FIG. 3 is a vertical sectional view of the headlamp taken along a line III—III of FIG. 1; 
     FIG. 4 is a horizontal sectional view of the headlamp taken along a line IV—IV of FIG. 1; 
     FIG. 5 is an exploded perspective view of a fog lamp unit; 
     FIG. 6 is an enlarged sectional view illustrating the shading action of heat-radiating fins provided in the convection-current forming holes of a reflector in the fog lamp unit; and 
     FIG. 7 is a vertical sectional view a conventional automobile headlamp. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A description of the preferred embodiment will now be made with reference to accompanying drawings. 
     FIGS. 1 to  6  show an embodiment of the present invention. FIG. 1 is a front view of a headlamp embodying the present invention; FIG. 2 is a vertical sectional view of the headlamp (taken along a line II—II of FIG.  1 ); FIG. 3 is a vertical sectional view of the headlamp (taken along a line III—III of FIG.  1 ); FIG. 4 is a horizontal sectional view of the headlamp (taken along a line IV—IV of FIG.  1 ); FIG. 5 is an exploded perspective view of a fog lamp unit; and FIG. 6 is an enlarged sectional view illustrating the shading action of heat-radiating fins provided in the convection-current forming holes of a reflector in the fog lamp unit. 
     In these drawings, reference character  10  denotes a longitudinally-long container-like lamp body which opens from the front side toward the diagonal side and a transparent front cover  11  with its side curving backward is incorporated with the front opening of the lamp body  10 , so that a lamp chamber curving from the front side toward the side. A reflection-type lamp unit  20  for forming a driving and a meeting beam and a projection-type fog lamp unit  40  are vertically provided in parallel in the lamp chamber. 
     Reference symbols H   1   , H   2   represent air holes provided in the lamp body  10  and used for performing a breathing action by which the air warmed in the lamp chamber is made to flow out of the lamp chamber through the upper air hole H   2   , whereas the air outside the lamp chamber is made to flow into the lamp chamber through the lower air hole H   1   lest condensation is produced on the front cover  11 . 
     The lamp unit  20  includes a plastic parabolic reflector  22  subjected to an aluminum deposition process (mirror polishing) and a bulb  30  as a light source fitted and fixed in a bulb fitting hole  23  formed in the rear top portion of the reflector  22 . 
     The bulb  30  is integral in structure with a bulb body  36  integrally containing a filament  36   a  for forming a main (high) beam and a filament  36   b  for forming a sub (low) beam, and a focussing ring  33  having three mating pawls  33   a  projecting from its peripheral edge portion is formed on the outer periphery of the bulb socket  32 . 
     On the other hand, a ring-like socket fixture  37  formed of synthetic resin is fixed with three screws (not shown) to the edge face of a cylindrical portion  24  forming a bulb fitting hole  23  in the reflector  22  and a mating groove  38  is formed so that the mating pawls  33   a  can be brought into engagement with the mating groove by bayonet coupling between the bulb fitting hole  23  and the socket fixture  37 . The bulb  30  is made detachable from the bulb fitting hole  23  by turning the bulb  30  (bulb socket  32 ). In this case, a flexible rubber hood F   1   is mounted between a bulb replacing opening  10   b  formed in the lamp body  10  and the cylindrical portion  24  of the reflector  22  in order that the rear opening  10   b  of the lamp body  10  is closed. 
     Then the focal point of the reflector  22  positions substantially in between filaments  36   a ,  36   b  in the bulb body  36  in such a state that the bulb  30  is fixed in the bulb fitting hole  23  (that the mating pawls  33   a  are brought into engagement with the mating groove  38  by bayonet coupling). The main beam is formed by the emission of light from the filament  36   a  for forming the main beams, whereas the sub-beam is formed by the emission of light from the filament  36   b  for forming the sub-beam. 
     Furthermore, the lamp unit  20  is tiltably supported with respect to the lamp body  10  by two aiming screws  12 ,  13  rotatably and removably supported with the rear wall of the lamp body  10  and extend; forward and one ball joint  14 . More specifically, nuts  12   a ,  13   a  screwed to the respective aiming screws  12 ,  13  are fitted to brackets  22   a ,  22   a  projected from the rear of the reflector  22  and by making the aiming screws  12 ,  13  pivot, the nuts  12   a ,  13   a  move back and forth along the respective aiming screws  12 ,  13 , whereby the lamp unit  20  is tilted around a vertical and a horizontal axis Ly   2   , Lx   2   (see FIG.  1 ). Thereby tilting of the optical axis L   2   of the lamp unit  20  can be made adjustable vertically and horizontally. 
     Reference symbol D in FIG. 3 represents a driver for controlling the pivoting of the aiming screws, the driver being capable of controlling the pivoting of a coronary gear  13   b  installed in the read end portion of the aiming screw  13 . A coronary gear (not shown) similar to the coronary gear  13   b  on the aiming screw side  13  is also installed in the rear end portion of the aiming screw  12 . 
     A lamp unit  40  includes a substantially elliptic reflector  42  formed by aluminum die-cast and subjected to an aluminum deposition process (mirror polishing), the reflector  42  being smaller in caliber than the reflector  22  of the lamp unit  20 , a bulb  50  as a light source fitted into the bulb fitting hole  43  of the reflector  42  and a projection convex lens  48  which is circular in a front view and integrated with the front opening of the reflector  42  via a cylindrical lens holder  46  die-cast in aluminum. 
     The bulb  50  is structurally formed by integrating a bulb body  56  containing a filament  56   a  with a plastic bulb socket  52 , and a focussing ring  53  having three mating pawls  53   a  projecting from its peripheral edge portion is formed on the outer periphery of the bulb socket  52 . 
     On the other hand, as shown in FIG. 4, a resin-made ring-like socket fixture  57  is fixed with three screws  59  to the edge face of a cylindrical portion  44  forming a bulb fitting hole  43  in the reflector  42  and a mating groove  58  is formed so that the mating pawls  53   a  can be brought into engagement with the mating groove by bayonet coupling between the bulb fitting hole  43  and the socket fixture  57 . The bulb  50  is made detachable from the bulb fitting hole  43  by turning the bulb  50  (the bulb socket  52 ). In this case, a flexible rubber hood F   2   is mounted between a bulb replacing opening  10   c  formed in the lamp body  10  and the cylindrical portion  44  of the reflector  42  in order that the rear opening  10   c  of the lamp body  10  is closed. 
     The filament  56   a  in the bulb body  56  positions on the first focal point of the rotary elliptic effective reflective surface of the reflector  42  and a fog lamp beams is formed by the emission of light from the filament  56   a  in such a state that the bulb  50  is fixed in the bulb fitting hole  43  (that the mating pawls  53   a  are brought into engagement with the mating groove  58  by bayonet coupling). In other words, reference numeral  46   a  denotes a shade for forming a cut off line, which is uprightly provided in the focal position of the projection convex lens  48  in a position near the second focal point of the rotary elliptic effective reflective surface of the reflector  42 . Part of the light reflected from the reflector  42  and directed to the projection convex lens  48  is blocked off by the shade  46   a , so that a predetermined light distribution pattern having a clear cut off line following the upper edge configuration of the shade  46   a  is formed. 
     Furthermore, the lamp unit  40  is tiltably supported in only the vertical direction with respect to the lamp body  10  by one aiming screw  15  rotatably and removably supported with the rear wall of the lamp body  10  and extending forward. More specifically, lateral upper side edge corner portions of an outwardly-directed flange  47  (see FIGS. 3 and 5) provided to the lens holder  46  are fixed with screws  47   a  to the respective bosses  10   a  (see FIG. 3) projecting from the lamp body  10  and a nut  15   a  screwed into the aiming screw  15  is fitted to the right lower edge corner portion of the outwardly-directed flange  47 . Consequently, the nut  15   a  moves back and forth along the aiming screw  15  by making the aiming screw  15  pivot, whereby the lamp unit  40  is tilted around the horizontal axis Lx   4   (see FIG.  1 ). Thereby tilting the optical axis L   4   of the lamp unit  40  which is adjustable only vertically. Incidentally, a mating portion  15   b  with which a driver D can be brought into engagement is provided in the rear end portion of the aiming screw  15  and the mating portion  15   b  is caused to pivot by the use of the driver D. 
     Reference numeral  18  denotes an extension reflector in which circular openings  18   a ,  18   b  are formed each corresponding to the reflector  22  of the lamp unit  20  and the projection convex lens  48  of the lamp unit  40 , and which is provided from the front opening of the lamp body  10  along the inner part of the front cover  11 . The surface of the extension reflector  18  is subjected to an aluminum deposition process (mirror polishing) like the reflectors  22 ,  42  and acts not only conceals the peripheral regions of the reflectors  22 ,  42  but also makes the whole inner part of the lamp chamber look like a single specular color, with the effect of giving the headlamp an excellent appearance. 
     Reference numeral  60  ( 60 A,  60 B) denotes convection-current forming holes formed in the upper and lower side walls of the reflector  42  and a convection current is generated between the inside and outside of the reflector  42  via the convection-current forming holes  60  ( 60 A,  60 B) as shown by arrows of FIG.  2 . 
     More specifically, the bulb  50  itself is caused to be heated to high temperatures when lighted and thermal energy originating from the heat radiated from the bulb  50  or the direct rays of light is transmitted to the plastic bulb socket  52  and the plastic socket fixture  57  via the reflector  42  die-cast in aluminum having high thermal conductivity. As the reflector  42  is kept in a substantially airtight condition by the cylindrical lens holder  46  and the projection convex lens  48 , the inside thereof in particular is filled with heated air and intense heat is transmitted to the bulb socket  42  and the socket fixture  57 , which may subject the bulb socket  52  and the socket fixture  52  to thermal deformation. 
     Therefore, the convection-current forming holes  60  ( 60 A,  60 B) are formed in the upper and lower side walls holding the bulb body  56  of the reflector  42  therebetween according to the present embodiment of the invention. Accordingly, there develops an air convection current in which the warmed air inside the reflector  42  flows out of the reflector  42  through the upper convention-current forming holes  60 A, whereas the air outside the reflector  42  flows into the reflector  42  through the lower convection-current forming holes  60 B. Due to the air convection current thus formed between the inside and outside of the reflector  42  via the convection-current forming holes  60  ( 60 A,  60 B), the heat radiating action of the reflector  42  is promoted and the air between the inside and outside of the reflector  42  is stirred, whereby the reflector  42  is restrained from being heated up because the airtight space inside the reflector  42  is set free from heat accumulation. 
     As the light receiving area of the reflector  42  is reduced by what corresponds to the convection-current forming holes  60  ( 60 A,  60 B), the thermal energy transmitted to the reflector  42  due to the direct rays of light and the radiated heat energy of the bulb  50  are also reduced and the reflector  42  is restrained from being heated up to that extent. 
     The reflective surface  41  subjected to the aluminum deposition treatment on the inside of the reflector  42  includes a substantially elliptic effective reflective surface  41   a  which is formed in a region ranging from the periphery of the bulb fitting hole  43  to the inner lateral sides and contributes to the light distribution of the lamp, and a non-effective reflective surface  41   b  which is formed in a region up to an inner vertical side close to the opening of the reflector  42  and which hardly contributes to the light distribution of the lamp (see FIG.  5 ). Since the convection-current forming holes  60  ( 60 A,  60 B) are formed in the non-effective reflective surface  41   b , substantially the same quantity of light as that of the fog lamp unit using the reflector without having the convection-current forming holes  60  ( 60 A,  60 B) is secured. 
     Furthermore, the convection-current forming holes  60  ( 60 A,  60 B) are formed with a number of rectangular slits  62  formed longitudinally at predetermined intervals and the whole open area is large enough to make greater the flow rate of an air convection current formed between the inside and outside of the reflector  42  and also make greater the quantity of heat radiating from the reflector  42  as well as the quantity of stirred air, so that the reflector  42  hardly becomes heated to high temperatures. 
     Moreover, vertical wall-like heat-radiating fins  63  are longitudinally provided in between the slits  62  and air flow from the slits  62  takes off heat on the surface and undersurface of each heat-radiating fin  63  when the air flows along the heat-radiating fins  63 . Thus, the heat-radiating action of the reflector  42  is increased. 
     Heat-radiating fins  64  are also provided on the outer peripheral face of the cylindrical portion  44  where the bulb fitting holes  43  are formed and consequently the heat-radiating action of the reflector  42  is increased likewise. 
     As the heat-radiating fins  63  are tilted from the filament  56   a  in a direction substantially perpendicular to the direct rays of light to ensure that the direct rays of light are shaded by the heat-radiating fins, the direct rays of light are never allowed to directly pass through the slits. Therefore, it is possible to obviate nonconformity arising from bringing the extension reflector  18 , the reflector  22  of the lamp unit  20  and the lamp body  10  into direct contact with the direct rays of light. 
     Although the light reflected from the heat-radiating fins  63  is, as shown in FIG. 6, directed to the rear and front of the reflector  42 , the intensity of light reflected from the heat-radiating fins  63  is low because the outer surface of the reflector  42  including the heat-radiating fins  63  are subjected to oxidation and turned black. Since the intensity of light reflected from the lamp body  10 , the extension reflector  18  and the reflector  22  is weakened further, the light is extremely weak in intensity even though there exists the light passed through the front cover  11  and directed forward and the light distribution of the lamp entirely remains unaffected. 
     Although the metal reflector  42  is provided with the convection-current forming holes  60  ( 60 A,  60 B) and the heat-radiating fins  63 ,  64  according to the aforesaid embodiment of the invention, the metal reflector  42  may be arranged so that it is provided with only heat-radiating fins without forming convection-current forming holes in order to restrain such a reflector from being heated to high temperatures. 
     A description has been given of a structure wherein the substantially elliptic reflector  42  of the projection-type lamp unit  40  kept substantially airtight inside is provided with the convection-current forming holes  60  ( 60 A,  60 B) according to the aforesaid embodiment of the invention. In a case where the reflector  22  in the reflection-type lamp unit  20  is made of metal, however, the provision of convection-current forming holes for the metal reflector (i.e., its non-effective reflective surface) makes the present invention also applicable to any lamp of the reflection-type. 
     A description has been given of an automobile fog lamp according to the aforesaid embodiment of the invention. However, the present invention is not limited to the fog lamp but may be widely applicable to headlamps and other vehicle lamps as long as the lamp is equipped with a metal reflector. 
     Although the bulb socket  52  as a means for fixedly holding a light source body and the socket fixture  56  are made of synthetic resin according to the aforesaid embodiment of the invention, the present invention is needless to say applicable to the case of a plastic bulb socket with a metal socket fixture or of a plastic socket fixture with a metal bulb socket whereby to avoid the thermal deformation of the plastic bulb socket or the plastic socket fixture. 
     As is obvious from the description given above, according to the present invention, the reflector, though extremely simple in structure, is restrained from being heated to high temperatures when the vehicle lamp is lighted by providing the reflector with the convection-current forming holes. There is no possibility that the plastic light-source fixing-holding means is subjected to thermal deformation to ensure that the durability of the plastic light-source fixing-holding means is extended over a long period of time. 
     Further, the provision of the convection-current forming holes in the non-effective reflective surface hardly contributing to the light distribution of the vehicle lamp makes available substantially the same light distribution as the light distribution of the vehicle lamp without having the convection-current forming holes. 
     Furthermore, as the whole open area of the convection-current forming holes is large, the active convection current together with the heat radiating action of the vertical wall-like heat-radiating fins ensures that the reflector is restrained from being heated to high temperatures when the vehicle lamp is lighted. 
     According to the present invention, moreover, as the direct rays of light are not emitted from the convection-current forming holes, there is no possibility that the vertical wall-like heat-radiating fins are subjected to thermal deformation and that the disturbance of the light distribution of the vehicle lamp as well as the generation of glare light occur. 
     According to the present invention, the air convection current is directed from the upper side to lower side around the light source body of the reflector via the convection-current forming holes, which results in stirring the air inside and outside of the reflector efficiently, thus restraining the reflector from being heated to high temperatures. 
     According to the present invention, the inside of the substantially airtightly closed reflector in the projection type lamp unit is stirred by the air convention current produced between the inside and outside of the reflector via the convection-current forming holes with the effect of restraining the reflector from being heated to high temperatures. 
     According to the present invention, the reflector though extremely simple in structure is restrained from being heated to high temperatures when the vehicle lamp is lighted by providing the heat-radiating fins on the outside of the reflector and as there is no possibility that the plastic light-source fixing-holding means is subjected to thermal deformation to ensure that the durability of the plastic light-source fixing-holding means is extended over a long period of time. 
     According to the present invention, the reflector is restrained from being heated to high temperatures and besides the plastic socket fixture for fixing the plastic bulb socket and/or the bulb socket as the light-source fixing-holding means is never subjected to thermal deformation.