Abstract:
A device capable of tilting a reflector installed in a lamp body for adjusting the body&#39;s optical axis is provided. Workability of the process for securing the ball bearing to the reflector can be simplified and dislocation of the ball bearing can be prevented.

Description:
FIELD OF THE INVENTION 
     The invention relates to a vehicle lamp provided with a built-in reflector holding a light source in its lamp body and a device for tilting the reflector so as to allow adjustment of the optical axis angle of the lamp. 
     BACKGROUND OF THE INVENTION 
     A known headlamp for a vehicle such as an automobile is provided with a so-called aiming adjusting mechanism in which a reflector installed in the lamp body is tilted in vertical and lateral directions to adjust the optical axis of the reflector. Also, there is a known headlamp provided with an automatic optical axis leveling mechanism that maintains the optical axis of the headlamp at a certain angle in response to the tilting movement of the vehicle body. In either case, the headlamp is required to have a device for tilting the reflector provided overall or inside the lamp so as to adjust the optical axis angle. For this purpose, the latter case, for example, the reflector installed in the lamp body is supported on one or more pivots so as to move tiltably along the direction required to perform optical axis adjustment in vertical and lateral directions relative to the lamp body. An actuator for tilting movement is provided at a position different from the aforementioned pivot so as to move a part of the reflector towards the tiltable direction. As a result, the reflector can be tilted along the required direction to adjust the optical axis angle. 
     To realize the aforementioned structure in which the part of the reflector is moved by the actuator for tilting movement, the position where the actuator and the reflector are joined is required to combine the linear movement generated by the actuator and the revolution movement about the pivots generated by the reflector. Both movements do not conflict with each other. For this purpose, there has been proposed a joint structure including a ball bearing of groove type (this structure is referred to as a grooved ball bearing hereinafter). FIG. 8 is a schematic view showing the structure of the conventional art. Specifically, the reflector  3  installed in the lamp body  1  is in the tiltable state in the vertical direction at the pivot (not shown). An actuator  31  for tilting movement is fixed to the lamp body  1  at the position opposite to the rear surface of the reflector  3 . The actuator  31  for tilting movement has an actuator rod  32  provided with a spherical end  33  having a spherical end portion, which extends toward the optical axis of the lamp. As a result, the actuator rod  32  is structured to perform reciprocating movement along the extending direction upon driving. A stem  3   c  is integrally formed on the rear surface of the reflector  3  to extend from the position opposite to the actuator rod  32 . The grooved ball bearing  21 A is fixed to the tip end of the stem  3   c  using a screw  7 . 
     The grooved ball bearing  21 A is formed by resin molding and includes a groove  22  of a semi-tubular shape, a pair of engagement pieces  23  disposed along and at both sides of the groove  22  to protrude therefrom, each end piece  24  of which is bent at an acute angle to face the groove  22 , and an anchor part  25  extending outward from the base of the engagement piece  23 . The grooved ball bearing is fixed at its anchor part  25  to the stem  3   c  of the reflector  3  by the screws  7  so that an opening of the groove  22  faces the actuator  31  for tilting movement. The spherical end  33  of the actuator rod  32  is fitted in the gap defined by the groove  22  and the end piece  24  of the pair of engagement pieces  23 . The spherical surface of the spherical end  33  abuts against the inner bottom surface of the groove  22  and the pair of end pieces  24 . As a result, the spherical end  33  is pivotally supported to allow spherical movement at abutment points. In the above structure, the groove  22  and the engagement piece  23  keep their respective cross sections constant at any point along the axis of the groove, thus allowing a free movement of the spherical end  33  in the direction of the groove axis. When the actuator  31  moves the actuator rod  32  reciprocally in the optical axis direction, the grooved ball bearing  21 A secured on the reflector  3  moves as the spherical end  33  moves in the optical axis direction. During this operation, the spherical end  33  is allowed to move along the groove  22  of the ball bearing  21 A in its axial direction such that the reflector  3  is allowed to be relatively tilted in a predetermined direction to the actuator rod  32 , that is, in the vertical direction in the present case. 
     SUMMARY OF THE INVENTION 
     The grooved ball bearing  21 A is secured at both side anchor parts  25  on the stem  3   c  of the reflector  3  with screws  7  as described above. Such arrangement, therefore, requires the process of securing two screws  7  to mount the grooved ball bearing  21 A onto the reflector, thus increasing man-hours for the assembly process and complicating the assembly work. Furthermore, if the screw  7  is threaded into a hole in an anchor part  25  having a diameter larger than that of the screw with much allowance, the grooved ball bearing  21  is likely to be out of the desired mounting position with respect to the stem  3   c . Such dislocation may interfere with alignment between the axis of the actuator rod  32  and the center line of the groove  22  of the ball bearing. This prevents the groove  22  from admitting proper insertion of the spherical end  33  of the actuator rod  32 . Even if the insertion is performed, a smooth movement of the actuator rod  32  and the grooved ball bearing  21  may be prevented. In addition, over the extended period of use, the screw  7  may be loosened, which would cause dislocation of the grooved ball bearing  21  relative to the reflector  3 . Dislocation of the relative position between the grooved ball bearing  21  and the actuator rod  32  deteriorates the precise tilting of the reflector  3 . 
     An object of the present invention is to provide a vehicle lamp having a device for tilting a reflector, which simplifies the work for assembling the grooved ball bearing and prevents deterioration of tilting movement of the reflector and assures smooth movement by preventing dislocation of the grooved ball bearing. 
     A vehicle lamp of the present invention is provided with a device for tilting a reflector installed in the lamp body for adjusting the optical axis of the reflector. The device comprises an actuator, for tilting movement disposed on the lamp body, having an actuator rod which is actuated to move linearly along the optical axis of the reflector and a ball bearing secured to the reflector to support pivotally the distal spherical end of the actuator rod so as to convert the linear movement into the tilting movement of the reflector. The ball bearing has first and second anchor parts to be secured to the reflector. The first anchor part is constructed to be secured to the reflector by a fastener means, and the second anchor part is constructed to be fitted with the reflector. The second anchor part has a plurality of fitting walls disposed to define a cross-shaped gap between the fitting walls. The reflector is integrally provided with a cross-shaped boss having a cross-shaped cross section, which can be fitted into the cross-shaped gap. Preferably, the second anchor part has a pin hole at the crossing center of the cross-shaped gap, and the reflector is provided with a pin projecting from the top end of the cross-shaped boss so as to be fitted into the pin hole. 
     In the present invention, the ball bearing is secured to the reflector by inserting the top end of the cross-shaped boss on the reflector into the cross-shaped gap defined by the walls at the second anchor part, while inserting the pin of the cross-shaped boss into the pin hole in the ball bearing. Then at the first anchor part, the ball bearing is secured to the reflector by the screws. In the process for securing the ball bearing to the reflector, the insertion process is only required at the second anchor part, and fastening the fastening means such as the screw is only required at the first anchor part. This makes it possible to improve assembly workability as a whole. Furthermore the joint system of the cross-shaped gap and boss at the second anchor part prohibits the relative dislocation of the ball bearing with respect to the reflector, thereby ensuring the smooth tilt movement realized by the device for tilting the reflector as well as improving precision in its tilt movement. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front elevational view of a vehicle headlamp according to an embodiment of the present invention. 
     FIG. 2 is a cross-sectional view taken along line A—A in FIG.  1 . 
     FIG. 3 is an enlarged plan view seen from line B—B in FIG.  2 . 
     FIG. 4 is an exploded perspective view of the grooved ball bearing and the lower stem. 
     FIG. 5 is a frontal perspective view of the grooved ball bearing. 
     FIG. 6 shows a rear side view (rear elevational view) and a plan view of the grooved ball bearing, respectively. 
     FIG. 7 is a cross sectional view taken along line C—C in FIG.  3 . 
     FIG. 8 is a perspective explanatory view showing a concept of a device for a tilting reflector; and 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the present invention will be described referring to the attached drawings. FIG. 1 is a front elevational view of a headlamp for a vehicle incorporating the device for tilting reflector according to the first embodiment of the invention. FIG. 2 is a cross-sectional view taken along line A—A in FIG.  1 . FIG. 3 is an enlarged plan view seen from line B—B in FIG.  2 . The headlamp HL includes a lamp body  1 , and a lens  2  is secured and sealed along the circumference edge of an front opening thereof. A lamp chamber is defined by the lamp body  1  and the lens  2 . A reflector  3  molded of resin is disposed in the lamp chamber. The reflector  3  has a paraboloidal inner face for reflection, and a bulb-mounting bore at its center, in which a bulb socket  6  supporting a bulb  5  as a light source is detachably mounted. In addition, a device  8  for tilting the reflector in a vertical direction is provided so as to adjust the optical axis. 
     Now the device  8  for tilting reflector will be hereinafter described. The reflector  3  is supported to the lamp body  1  by means of pivot units  11  at its right and left points at the upper portion of its rear. The pivot unit  11  is composed of a ball shaft  12  press fitted to the top portion of the upper stem  3   a  disposed at two right and left points on the rear surface of the reflector  3  and protruding rearward therefrom, and a ball bearing  13  disposed on a part of the inner surface of the lamp body  1  having a spherical recess portion. Thus the end  12   a  of the ball shaft  12  is fitted in the ball bearing  13  so that the reflector  3  is tiltably moveable about the joint of the ball shaft  12  and the bearing  13 . 
     The reflector  3  is provided with a lower stem  3   b  at a lower part on its back, which protrudes rearward therefrom. A grooved ball bearing  21  is secured to the end of the lower stem  3   b . An actuator  31  for tilting movement is mounted on the back of the lamp body  1  via an opening  1   a  confronting the grooved ball bearing  21 . The spherical end  33  having a substantially spherical shape of an actuator rod  32  extends from the actuator  31  to the lamp body  1  so as to be fitted into the grooved ball bearing. Although detailed description and drawings are omitted, the actuator  31  houses a motor and a worm wheel mechanism to be driven thereby such that the revolution drive from the motor extends and contracts (reciprocate) the actuator rod along its length. The actuator  31  is controlled by a control circuit which is not shown. In this embodiment, it is constructed to function such that the optical axis is maintained at a predetermined angle based on an output signal from a level sensor for detecting the horizontal position of the vehicle body. 
     FIG. 4 is an exploded perspective view of the lower stem  3   b  and the grooved ball bearing  21 . The lower stem  3   b  includes a cylindrical boss  41  having a circular cross section, and a cross-shaped boss  42  having a cross-shaped cross section both extending horizontally toward the back of the reflector  3 . These two bosses are connected to each other via connector plates  43 ,  44  extending between those bosses and between the cylindrical boss  41  and the reflector  3 , respectively, for the purpose of improving mechanical strength of the bosses  41  and  42 . The cylindrical boss  41  has a threaded hole  45  at the distal end, into which a screw  7  is threaded to secure the grooved ball bearing  21 . Further the cross-shaped boss  42  has a cylindrical fitting pin  46  protruding rearward from the crossing center of the cross section of the cross-shaped boss  42 . 
     FIG. 5 is a frontal perspective view of the grooved ball bearing  21 , and FIGS. 6A,  6 B are rear and plan views, respectively. The grooved ball bearing  21  has basically the same structure as that of the prior art shown in FIG.  8 . More specifically, it is provided with a groove  22  of a semi-tubular shape having the inner diameter approximately the same as that of the spherical end  33  of the actuator rod  32 , a pair of engagement pieces  23  disposed along and at both sides of the groove  22  to protrude therefrom toward the aperture, each end piece  24  of which is bent toward the groove  22  at an acute angle constituting a wedge shape, and anchor parts  25   a ,  25   b  each protruding outward from the base of the engagement piece  23  at both sides of the groove  22 , and is formed by the resin molding. Both ends of the groove  22  in its axial direction are integrally provided with arch shaped end stoppers  26  that extend inwards from opposed sides. The draft direction of the molding die for the grooved ball bearing  21  is set along the direction of the groove  22 . Accordingly each cross section of the groove  22 , engagement piece  23  and anchor part  25   a ,  25   b  has the identical shape along the axial direction of the groove  22 . In order to allow drafting during release of the molding die, the end stoppers  26  are disposed in a mutually offsetting manner with respect to the groove  22  for enabling the molding die to be released off from the molded product. 
     A first anchor part  25   a  of the anchor parts  25   a ,  25   b  provided at both sides of the grooved ball bearing  21  has a through hole  27   a  through which the screw is threaded into the threaded hole  45  formed in the cylindrical boss  41  of the lower stem  3   b . An arched guide wall  27   b  is provided to project backward from the back of the first anchor part  25   a . It can abut against the outer peripheral surface of the cylindrical boss  41 . According to this embodiment, a plurality of ribs  23   a  constituting parallel raised rows of ridges are formed on the exterior face of the engagement piece  23  facing the first anchor part  25   a , thereby improving the strength thereof. Meanwhile, the second anchor part  25   b  has reinforcing flanges  23   b  of a triangular wing shape formed integrally therewith at opposite ends in the direction of the groove  22 , thereby improving the strength of the groove  22  and the second anchor part  25   b . At the back of the second anchor part  25   b , four L-shaped fitting walls  28  are erected to form jointly a cross-shaped gap  28   a , into which the distal end of the cross-shaped boss  42  of the lower stem  3   b  can be fitted. Also a pin hole  28   b  is formed at the crossing center of the cross-shaped gap  28   a , into which the fitting pin  46  of the cross-shaped boss  42  is fitted. 
     With such arrangement described above, the grooved ball bearing  21  is secured to the distal end of the lower stem  3   b  such that the open side of the groove  22  is confronted by the actuator  31  for tilting movement. More particularly, at the second anchor part  25   b , the distal end of the cross-shaped boss  42  of the lower stem  3   b  is fitted into the cross-shaped gap  28   a  defined by the four fitting walls  28 . At the same time, the fitting pin  46  of the cross-shaped boss  42  is inserted into the pin hole  28   b  of the grooved ball bearing  21 . In addition, at the first anchor part  25   a  of the grooved ball bearing  21 , the screw  7  is threaded from the back side through the hole  27   a  into the threaded hole  45  of the cross-shaped boss  41  for securing the grooved bearing to the lower stem  3   b  while the arched guide wall  27   b  abuts against a portion of the circumferential surface of the cylindrical boss  41 . This means that the process of securing the grooved ball bearing  21  to the lower stem  3   b  can be achieved in a simple manner by only inserting the fitting pin  46  into the pin hole  28   b  and fitting the tip of the distal end of the cross-shaped boss  42  into the cross-shaped gap  28   a  of the fitting walls  28  at the second anchor part  25   b  of the grooved ball bearing  21 . Then at the first anchor part  25   a , the screw  7  is threaded into the threaded hole  45  via the through hole  27   a . Therefore according to such arrangement, the process. of securing the grooved ball bearing  21  does not require any troublesome work other than fastening one screw  7 , thus improving the efficiency of assembling process for a lamp. 
     As shown in FIG. 7 representing a vertical cross section taken along line C—C in FIG. 3, in the state where the grooved ball bearing  21  is secured to the lower stem  3   b , the cross-shaped boss  42  is fitted into the cross-shaped gap  28   a  defined by the fitting walls  28 . Therefore, dislocation of the relative position between the cross-shaped boss  42  and the grooved ball bearing  21  is restrained by the structure where the cross-shaped boss  42  abuts against the cross-shaped gap  28   a  in the vertical and lateral directions. Even when the grooved ball bearing  21  is deformed backward relative to the cross-shaped boss  42 , the fitting state of the cross-shaped boss  42  is not brought to be out of the cross-shaped boss  28   a  by fitting the fitting pin  46  into the pin hole  28   b . The grooved ball bearing  21  is secured to the cylindrical boss  41  at the first anchor part  25   a  with the screw  7 . The grooved ball bearing  21  is positioned with respect to the cylindrical boss  41  by bringing the guide wall  27   b  into abutment against the outer peripheral surface of the cylindrical boss  41 . At the first anchor part  25   a , an obstacle such as a triangular wing-like reinforcing flange provided at the second anchor part  25   b  does not interfere with the fastening operation of the screw  7 . 
     In the grooved ball bearing  21  secured to the low stem  3   b , the spherical end  33  of the actuator rod  32  is fitted into the gap defined by the groove  22  and the end piece  24  of the pair of engagement pieces  23  as shown in FIG.  3 . During such fitting process, the spherical end  33  moves vertically from the front opening of the groove  22 . Then it is brought into abutment against the respective exterior face of the pair of end pieces  24 . It further enters while deforming the end piece  24  resiliently inward, and moves past the end piece  24  to be finally received and fitted in the gap. The fitted spherical end  33  is brought into abutment against the inner bottom surface of the groove  22  and the edges of the end piece  24  at a plurality of points on its spherical surface. Accordingly the spherical end  33  is pivotally and moveably supported at the abutted points. The groove  22  and the engagement piece  23  have uniform cross sections at any point along the groove axis, which allows the spherical end  33  to move freely along the groove axis. Meanwhile the spherical end  33  is prohibited to move out of the groove forward by the end piece  24 . As the end stoppers  26  extend inward of the groove  22 , the spherical end  33  is kept from slipping out of the groove  22  from both ends in the direction of the groove axis. 
     The constructed device  8  for tilting a reflector operates in the following manner. The actuator  31  for tilting movement is driven upon the receipt of the control signal sent from the control circuit, not illustrated, to move the actuator rod  32  in a direction of the optical axis of the lamp, i.e. in the direction X shown in FIGS. 2 and 3. The grooved ball bearing  21  secured to the reflector  3  is moved in the optical axis direction together with the spherical end  33  of the actuator rod  32 . Accompanied with this, the reflector  3  is tilted vertically about the pivot unit  11 . During this operation, the spherical end  33  allows relative vertical movements between the reflector  3  and the actuator rod  32  owing to tolerance generated in the axial direction of the groove in the grooved ball bearing  21 . As a result, the reflector  3  is tiltably moved in the vertical direction by the reciprocating linear movement of the actuator rod  32 . This makes it possible to maintain the angle of the optical axis of the headlamp HL constant following up the leveling fluctuation of the vehicle body. 
     Alternatively, the guide wall of the first anchor part for the grooved ball bearing may be a cylindrical guide wall to surround the entire circumference of the cylindrical boss. This arrangement makes the securing system more reliable because the grooved ball bearing is fitted into the lower stem at both the first and second anchor parts. It is also possible to employ the securing system as fastener means like a caulking instead of the screw for securing the first anchor part. Also the cross-shaped gap defined by the fitting walls of the grooved ball bearing may be designed into an arbitrary shape such as an X-shape or parallel-cross, so long as the thus jointed members will not be dislocated neither in the vertical nor lateral directions. The foregoing embodiments are described for the headlamp using an automatic leveling unit for optical axis adjustment. However, the present invention may also be applied to vehicle lamps so long as it includes a headlamp provided with a device for tilting the reflector in the lamp body to adjust the optical axis, and also provided with an automatic or manually operating the actuator for tilting movement having a spherical end as described in the foregoing embodiment and a grooved.ball bearing mounted to the reflector. 
     As described above, the present invention provides a structure of the ball bearing constituting the device for tilting the reflector, which includes first and second anchor parts. The first anchor part is secured to the reflector using the fastening means, and the second anchor part is fitted to the reflector. As the first anchor part is required to be secured to the reflector using the fastening means, and the second anchor part is required only to be fitted therewith, the process for securing the ball bearing can be simplified. Furthermore, at the second anchor part, the top end of the cross-shaped boss at the reflector side is fitted into the cross-shaped gap defined by the fitting walls. Also the fitting pin is fitted into the pin hole formed in the ball bearing, thus preventing the relative dislocation between the ball bearing and the reflector. Even when the pin is loosened over an extended period of use, the structure of the second anchor part prevents the positional dislocation of the ball bearing. Hence the present invention ensures a smooth movement of the device for tilting a reflector, thus improving the precision in the reflector movement. 
     Several embodiments of the invention have been described herein, but it should be understood that various additions and modifications could be made which fall within the scope of the following claims.