Abstract:
A vehicular lamp which employs one or more projector lamp units and which is capable of preventing a reflector from being deformed by weight-induced strain while achieving and maintaining required light distribution characteristics. In one embodiment, the vehicular lamp includes first and second lamp units provided with respective reflectors, light sources, and projection lenses, with each lamp unit being tiltably supported on a lamp body via brackets formed separately at least from the reflectors. The brackets are tiltably supported at fulcrums the lamp body. Even in a case where stresses resulting from the weights of the lamp units are applied to bearings to the fulcrums, the stresses can be attenuated or absorbed by the brackets and the reflectors of the lamp units are not strained. Thus, the reflectors are prevented from being deformed, and the lamp units can achieve desired light distribution characteristics.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    Not applicable  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not applicable  
         REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX  
         [0003]    Not applicable  
         BACKGROUND OF THE INVENTION  
         [0004]    The present invention relates to a vehicular lamp. More specifically, the present invention relates to a vehicular lamp wherein a lamp unit provided with a light source, a reflector, and a condenser lens is fitted in a lamp body and the lamp unit is tiltably supported in the lamp body so as to permit aiming adjustment of the lamp.  
           [0005]    A projector lamp unit has been employed in a vehicular lamp for automobiles and the like. In a projector lamp unit (hereinafter referred to simply as a lamp unit), a bulb forming a light source is supported on a reflector, and a lens is attached to a front opening portion of the reflector by means of a holder or the like so as to realize a functional unit. In a case where a headlamp for a vehicle is constructed using such a lamp unit, the lamp unit is mounted in the lamp body in such a manner as to be tiltably supported on a fulcrum within the lamp body. Further, the lamp unit is coupled to and supported by the lamp body at positions vertically separated from the fulcrum by aiming screws. The aiming screws are rotated to effect aiming adjustment. That is, the lamp unit is vertically tilted around the fulcrum upon rotation of the aiming screws, whereby the direction of the optical axis of the lamp unit can be adjusted.  
           [0006]    In the vehicular lamp described above, a supporting piece is formed integrally with part of the reflector, and the fulcrum for tiltably supporting the lamp unit is located on the supporting piece. With this construction, the weight of the lamp unit acts on the supporting piece in a concentrated manner, and stress resulting from the weight of the lamp is applied to the supporting piece. Thus, the reflector integrated with the supporting piece is strained, which can result in deformation of the reflective surface of the reflector to such an extent that the lamp can no longer provide the desired light distribution characteristics. Especially because a lamp unit of this type has a thick lens so as to achieve the desired light distribution characteristics, the center of gravity of the lamp unit is offset toward the front lens, resulting in a weight moment being constantly applied to the supporting piece since the latter is located behind the lens. Hence, the reflector tends to be severely strained. Furthermore, in a case where a four-lamp type automotive headlamp is constructed using lamp units of such a type, it is required that two lamp units be tiltably supported on the lamp body on each of left and right sides. In this case, the total weight of the lamp units is almost doubled, and the stress applied to the supporting piece is increased as well. As a result, the reflector may be severely strained.  
         BRIEF SUMMARY OF THE INVENTION  
         [0007]    It is an object of the present invention to provide a vehicular lamp which employs a projector lamp unit whose reflector is not strained and which can maintain required light distribution characteristics.  
           [0008]    The present invention provides a vehicular lamp wherein a lamp unit is tiltably supported in a lamp body, wherein a bracket formed separately at least from the reflector is formed integrally with the lamp unit, and the bracket is tiltably supported at a fulcrum on the lamp body. It is preferable that the fulcrum be disposed on a vertical line including the center of gravity of the lamp unit or a nearby position. It is also possible to provide at least one additional lamp unit supported by the bracket, in which case a plurality of fulcrums are formed on the lamp body on an axis around which the bracket tilts, the bracket is supported at one of the fulcrums, and part of each additional lamp unit is supported at another of the other fulcrums  
           [0009]    According to the present invention, even in a case where stress resulting from the weight of the lamp unit is applied to the fulcrum, the stress can be attenuated or absorbed by the bracket, and hence the reflector of the lamp unit is not strained. In particular, if the fulcrum is disposed at a position immediately below or close to the center of gravity of the lamp unit, no rotational moment or the like resulting from the weight of the lamp unit is applied to the fulcrum, and the reflector can be prevented from being strained. Furthermore, in a case where a plurality of lamp units are integrally supported, the weights of the lamp units are supported in a dispersed manner by a plurality of fulcrums. Hence, the stress applied to each of the fulcrums is reduced, and the reflector prevented from being strained.  
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a partially cut-away front view of an embodiment in which the present invention is applied to a headlamp of a vehicle.  
         [0011]    [0011]FIG. 2 is a cross-sectional view taken along a line AA shown in FIG. 1.  
         [0012]    [0012]FIG. 3 is a cross-sectional view taken along a line BB shown in FIG. 1.  
         [0013]    [0013]FIG. 4 is a perspective view of an essential part of the lamp shown in FIG. 1.  
         [0014]    [0014]FIG. 5 is an exploded perspective view of FIG. 2.  
         [0015]    [0015]FIG. 6 is a perspective view of an essential part of another embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    Preferred embodiments of the present invention will be described with reference to the drawings.  
         [0017]    [0017]FIG. 1 is a partially cut-away front view of a right-side headlamp constructed in accordance with a preferred embodiment in which the invention is applied to a four-lamp type headlamp for automobiles. FIG. 2 and FIG. 3 are cross-sectional views taken along lines AA and BB, respectively, shown in FIG. 1. FIG. 4 is a perspective view of an essential part of the headlamp. FIG. 5 is a partially exploded view of an essential part of the headlamp.  
         [0018]    In FIG. 1, a lamp chamber  3  is defined by a lamp body  1  securely fixed to a vehicle body and a translucent cover  2  attached to a front opening of the lamp body  1 . Two lamp units  4 ,  5  are mounted within the lamp chamber  3 . A seal leg portion  21  formed on a peripheral portion of the translucent cover  2  is inserted into a seal groove  11  formed along the front opening of the lamp body  1  and attached by means of a sealing agent  22 . The two lamp units  4 ,  5  are laterally disposed within the lamp chamber  3 . The lamp unit  4  on the external side of the vehicle (i.e., the side of the vehicle toward the side of the road) is constructed as a low-beam lamp, while the lamp unit  5  on the central side of the vehicle (i.e., the side of the vehicle toward the center of the road) is constructed as a high-beam lamp. An extension  6 , whose surface is plated with a metal such as aluminum, is disposed in the lamp chamber  3  and positioned such that the inner surface of the lamp body  1  is not visible from outside the two lamp units  4 ,  5 . The extension  6  is supported by the lamp body  1 . Furthermore, a socket insertion hole  12  is formed in the lamp body  1  at rearward positions of each of the lamp units  4 ,  5 . Bulb sockets  42 , which will be described in more detail later, are provided in the lamp units  4 ,  5 . The bulb socket  42  of the lamp unit  4  is shown in FIG. 2. A rear end portion of this bulb socket  42  is inserted through and positioned in the socket insertion hole  12 . A rubber cap  13  is fitted between the opening  12  and the bulb socket  42 , whereby a waterproof structure is realized.  
         [0019]    As shown in FIG. 2, the lamp unit  4  is provided with a reflector  41 , a bulb  43 , and a lens structure body  44 . The reflector  41 , which is formed generally in the shape of an ellipse of revolution, has a reflective inner surface. The bulb  43 , which functions as a light source, is supported by the bulb socket  42 , which attached to a socket attachment hole formed in the rear surface of the reflector  41 . The lens structure body  44  is attached to the front opening of the reflector  41 . As shown in FIG. 5, the lens structure body  44  is provided with a lens holder  46 , a condenser lens  47 , and a lens fixture  48 . The lens holder  46  is formed in generally a cylindrical shape and is attached to a front end portion of the reflector  41  by means of screws  45 . The condenser lens  47  is disposed on a front end surface of the lens holder  46 . The lens fixture  48  is fitted to a front end portion of the lens holder  46  from a position in front of the condenser lens  47 , whereby the condenser lens  47  is sandwiched between the lens holder  46  and the lens fixture  48 . The lens holder  46  is provided with a shade  49  for blocking some of the light emitted by the light source  43 . The same is also the case for the lamp unit  5 . A lens structure body  54  provided with a reflector  51 , a bulb socket  52 , a lens holder  56 , a condenser lens  57 , and a lens fixture  58  is shown in FIGS. 4 and 5.  
         [0020]    In the low-beam lamp unit  4 , the reflector  41  and the lens holder  46  are attached to each other by means of the screws  45 , as described above, with a bracket  7  sandwiched between the reflector  41  and the lens holder  46 . The bracket  7  is provided with a vertical piece  71 , a horizontal piece  72 , and a supporting piece portion  73 . The vertical piece  71  is formed in the shape of a circular frame corresponding to the cylindrical structures of the reflector  41  and the lens holder  46 . The horizontal piece  72  curves forwards from a lower end edge of the vertical piece  71  substantially in the horizontal direction. The supporting piece portion  73  extends vertically downward from the front end edge of the horizontal piece  72 . It is to be noted that the longitudinal length of the horizontal piece  72  is determined such that the supporting piece portion  73  is located immediately below or close to the center of gravity of the lamp unit  4 . A concave fitting hole  73   a  is formed in the supporting piece portion  73  at a position slightly offset toward the high-beam lamp unit  5  from a position immediately below the center of gravity. A ball receiver  74  is fitted into the fitting hole  73   a  and fixed by means of a screw  75 . The ball receiver  74  is formed by plastic molding. A spherical ball-receiving surface  74   a  is formed inside the ball receiver  74 . A rectangular hole  76  is formed in the vertical piece  71  at a position located along the upper end edge thereof. An aiming nut  77  is fitted into and supported by the rectangular hole  76 . An insertion hole  77   a  of a female threaded structure is formed in the aiming nut  77 . A lance (not shown) is formed on the outer surface of the aiming nut  77 , whereby the aiming nut  77  is retained within the rectangular hole  76 .  
         [0021]    In the high-beam lamp unit  5  as well, a bracket  8  is sandwiched between the reflector  51  and the lens holder  56 . Protruding pieces  81 ,  82  are integrally formed on both sides of the bracket  8  extending horizontally outwards. The outer protruding piece  81 , that is, the protruding piece  81  on the side of the low-beam lamp unit  4 , forms a coupling piece, and is fixed to part of the supporting piece portion  73  of the bracket  7  by means of a screw  83 . The inner protruding piece  82  on the other side forms a supporting piece. A ball receiver  84 , which is identical to the ball receiver  74  on the side of the lamp unit  4 , is fitted into a fitting hole  82   a  formed in a tip end portion of the protruding piece  82  and is fixed by means of a screw  85 . It is to be noted that the coupling piece  81  and the supporting piece  82  are disposed in such a manner as to be aligned with the ball receiver  74  that is fitted to and supported by the bracket  7  on the side of the lamp unit  4 . For convenience of explanation, the former ball receiver  74  formed in the supporting piece portion  73  of the bracket  7  will be referred to as a main ball receiver, and the latter ball receiver  84  formed in the supporting piece  82  will be referred to as a sub ball receiver.  
         [0022]    The lamp units  4 ,  5 , integrally connected by the brackets  7 ,  8 , are mounted within the lamp chamber  3 . The main ball receiver  74  and the sub ball receiver  84  vertically tiltably support the lamp units  4 ,  5  with respect to the lamp body  1 . That is, rod-like ball screws  14 ,  15 , whose tip ends are formed into ball portions  14   a ,  15   a , respectively, are screwed into and thus fix the lamp body  1  at positions corresponding to the main ball receiver  84  and the sub ball receiver  84 , respectively. The ball portions  14   a ,  15   a  of the ball screws  14 ,  15  are fitted into the main ball receiver  84  and the sub ball receiver  84 , respectively, whereby a main ball bearing  74 A and a sub ball bearing  84 A are constituted. Because the main ball receiver  74  and the sub ball receiver  84  are aligned with each other, the main ball bearing  74 A and the sub ball bearing  84 A are also aligned with each other. Thus, the two lamp units  4 ,  5 , which are integrated via the brackets  7 ,  8 , are made vertically tiltable around a line connecting the two ball bearings  74 A,  84 A.  
         [0023]    An aiming screw  16  is provided which is rotatably mounted on the rear surface wall of the lamp body  1  at a position opposed to the aiming nut  77  that is fitted into and supported by the rectangular hole  76  of the bracket  7 . A threaded portion  16   a  of the aiming screw  16  is screwed into the aiming nut  77 . Hence, by rotating the aiming screw  16  from a position outside the lamp body  1 , the aiming nut  77  is moved in the axial direction of the aiming screw  16 . The brackets  7 ,  8 , and hence the lamp units  4 ,  5 , are thereby vertically tiltably moved around the line connecting the two ball bearings  74 A,  75 A. As a result, the tilt angles of the two lamp units  4 ,  5 , that is, the directions of the radiation optical axes of the two lamp units  4 ,  5 , can be adjusted.  
         [0024]    With the construction described above, the low-beam lamp unit  4  is tiltably supported by the lamp body  1  via the main ball bearing  74 A formed in the bracket  7 . Moreover, the main ball bearing  74 A is disposed close to a position immediately below the center of gravity in the longitudinal direction of the low-beam lamp unit  4 . Hence, the weight of the low-beam lamp unit  4  acts primarily in the vertical direction on the main ball bearing  74 A. Therefore, even if the condenser lens  47  of the low-beam lamp unit  74 A is heavy, almost no rotational moment acts on the main ball bearing  74 A. Thus, both in the static case and the case where the tilt angle of the low-beam lamp unit  4  is adjusted by operating the aiming screw  16 , very little stress is applied to the main ball bearing  74 A. Even in a case where a small amount of stress is generated, since the bracket  7  is formed separately from the reflector  41  of the low-beam lamp unit  4 , the stress is absorbed by strain on the bracket  7 . Thus, strain-induced deformation of the reflector  41  is prevented. In this embodiment, the high-beam lamp unit  5  is coupled to the bracket  7  via the bracket  8 , and is supported by the sub ball bearing  84 A at the supporting piece  82  formed in the bracket  8 . The sub ball bearing  84 A is aligned with the main ball bearing  74 A. Hence, the sum of the weights of the two lamp units  4 ,  5  acts on the main ball bearing  74 A and the sub ball bearing  84 A. However, since these weights are applied in a dispersed manner by the main ball bearing  74 A and the sub ball bearing  84 A, the stresses applied to the ball bearings  74 A,  84 A are reduced. Moreover, in the high-beam lamp unit  5 , the stress applied to the supporting piece  82  is absorbed by the bracket  8 , whereby the reflector  51  is prevented from being strained. Furthermore, since the main ball bearing  74 A is disposed at a position offset toward the high-beam lamp unit  5  on the line connecting the main ball bearing  74 A and the sub ball bearing  84 A, the stress applied to the main ball bearing  74 A is larger than the stress applied to the sub ball bearing  84 A. However, the stress is absorbed by strain on the bracket  7  as described above. On the other hand, since the stress applied to the sub ball bearing  84 A is small, there is very little likelihood that the reflectors  41 ,  51  would be subjected to damaging strain, as described above. That is, the reflectors are prevented from being subjected to significant amounts of strain in both the low-beam lamp unit  4  and the high-beam lamp unit  5 . Therefore, the reflective surfaces of the reflectors are not deformed and the light distribution characteristics can be achieved and maintained.  
         [0025]    Because, as described above, the weight acting on the main ball bearing  74 A is larger than the weight acting on the sub ball bearing  84 A, it is preferable that the main ball bearing  74 A have higher mechanical strength. FIG. 6 shows an example of such a bearing  9 . A pair of tongue pieces  73   b  that are spaced apart from each other on a line serving as a fulcrum are cut from and extend downwards from the supporting piece portion  73  of the bracket  7 , and a through-hole is formed in each of the tongue pieces. A shaft  91  is inserted in such a manner as to extend along the space between these openings, supported at both ends thereof by the tongue pieces  73   b . A lock washer  92  is fitted onto the inserted tip end portion of the shaft  91 , whereby the shaft  91  is retained between the tongue pieces  73   b . A grommet  93  is fixed to the lamp body  1  at a position corresponding to the shaft  91  by means of a screw  94 . The grommet  93  has a semicircular cross-section corresponding to the radial dimension of the shaft  91  and has a concave groove  93   a  that is substantially equal in length to the shaft  91 . When the lamp unit  4  is supported by the lamp body  1 , the shaft  91  is fitted into the concave groove  93   a  of the grommet  93  and thereby supported while being fitted into the concave groove  93   a . In this bearing  9 , the area of contact between the shaft  91  and the concave groove  93   a  is larger in comparison with the case of a ball bearing. Thus, the bearing  9  can more stably receive the weight of the lamp unit, and as a result makes it possible to more effectively prevent the lamp unit from being strained.  
         [0026]    In the above-described embodiment, a headlamp in which the two lamp units  4 ,  5  are integrally tiltably supported is shown as an example. However, the present invention can be practiced as well in a case where a single lamp unit is tiltably supported in the same manner. In such a case, although not shown, it is appropriate that a bracket be formed in the same manner as in the case of the low-beam lamp unit of the aforementioned embodiment, and that the lamp unit be supported by the lamp body at the bracket by means of a shaft bearing or a ball bearing, also as mentioned above. In such a case, however, on the basic premise that the bearing is disposed immediately below or close to the center of gravity of the lamp unit in the longitudinal direction thereof, it is preferable that the bearing be disposed immediately below or close to the center of gravity of the lamp unit in the lateral direction thereof as well. Thus, the weight of the lamp unit vertically acts on the shaft bearing, whereby it becomes possible to effectively prevent the lamp unit from being strained.  
         [0027]    Alternatively, it is also appropriate that two or more lamp units are coupled to a bracket of a single lamp unit, with these lamp units being integrally tiltably supported.  
         [0028]    In the above-described embodiment, the bracket is formed separately from the lamp unit. However, the bracket may be formed integrally with a part other than the reflector, for example, the lens holder. Such construction is preferable from the standpoint of reducing the number of parts. Further, the bearing employed in the practice of the invention is not limited to a ball bearing or shaft bearing as described above, and it is possible to adopt another bearing structure.  
         [0029]    As has been described above, the vehicular lamp of the present invention is designed that a bracket formed separately from the reflector is formed integrally with the lamp unit and the bracket is tiltably supported at a fulcrum on the lamp body. Therefore, even if stress resulting from the weight of the lamp unit is applied to the fulcrum, the stress can be attenuated or absorbed by the bracket, and the reflector of the lamp unit is not strained or deformed. In particular, by disposing the fulcrum at a position immediately below or close to the center of gravity of the lamp unit, no rotational moment or the like resulting from the weight of the lamp unit is applied to the fulcrum, thus protecting the reflector from being strained. In addition, in a case where a plurality of lamp units are integrally supported, the weights of the lamp units can be received in a dispersed manner by a plurality of fulcrums. In such a case, the stress applied to each of the fulcrums can be attenuated, and the reflector protected from strain and deformation.  
         [0030]    It should further be apparent to those skilled in the art that various changes in form and detail of the invention as shown and described above may be made. It is intended that such changes be included within the spirit and scope of the claims appended hereto.