Abstract:
A bracket coupling a headlamp module to a fixed structure is sandwiched between two ribs that constrain the bracket in only the cross-car direction. Internal clearances in the bracket or rib features for accepting attachment bolts are designed to provide fore/aft and up/down position adjustments. The sandwich structure can be locked in (i.e., compressed) for a rigid, final attachment to the vehicle which will nevertheless allow sliding of the bracket within the ribs when subjected to the forces corresponding to an impact.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not Applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
       [0002]    Not Applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention relates in general to a system for mounting a headlamp module to an automotive vehicle, and, more specifically, to a support structure with an adjustable mounting position for a headlamp module while managing reaction forces when the hood is impacted during a collision (e.g., with a pedestrian). 
         [0004]    A typical headlamp module is connected to surrounding support structures in a grille opening beneath a forward end of a vehicle hood, usually with three or more connection points. To reduce potential injuries to a pedestrian in a collision with the vehicle, it is desirable for the vehicle hood to crumple or collapse in order to lessen the acceleration imparted to an impactor. However, a crumple zone beneath a hood may have a limited size as a result of a rigid headlamp module and mounting structures beneath the hood. Consequently, breakaway features have been used for headlamp mountings so that a greater range of deformation of the hood is achieved. However, breakaway components may have disadvantages such as poor control over the force at which breaking occurs and the added repair costs for the broken components. 
         [0005]    A further problem of the prior art for mounting headlamp modules to a vehicle support structure relates to assembly tolerances in which structures being interconnected may not line up properly. A typical headlamp module may have three or more distinct interconnection points around its perimeter. Each connection point may be mounted to different vehicle components such as a grille opening reinforcement or a vehicle frame rail, for example. Variability in the dimensions and spatial relationships on individual vehicles may result in difficulties in the final assembly connections. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention employs a bracket for coupling a headlamp module to a fixed structure, wherein the bracket is sandwiched between two ribs that constrain the bracket in only the cross-car direction. Internal clearances in the bracket or rib features for accepting attachment bolts are designed to provide fore/aft and up/down position adjustments. The sandwich structure can be locked in (i.e., compressed) for a rigid, final attachment to the vehicle which will nevertheless allow sliding of the bracket within the ribs when subjected to the forces corresponding to an impact. The sliding movement gives the same increased hood movement as a breakaway component would while potentially avoiding destruction of the bracket. Furthermore, the variability of the locking position provides adjustability to compensate for the assembly tolerances. 
         [0007]    In one aspect of the invention, apparatus for a transportation vehicle comprises a headlamp module housing having first and second parallel, upstanding ribs defining a channel therebetween. The channel extends along an axis adapted to be aligned with a front-to-rear direction of the vehicle. The first rib has a first opening disposed within a first substantially planar contact surface and the second rib has a second opening, wherein the first and second openings are coaxial. A first U-nut is slidably clipped onto the second rib having a first receptacle disposed coaxially with the first and second openings. At least one of the first U-nut or second rib provides a second substantially planar contact surface, wherein the first and second contact surfaces define opposite sides of the channel. A compensation bracket has a first end coupled to the headlamp module housing and a second end adapted to be coupled to a rigid support structure of the vehicle, wherein the first end has a first bore disposed coaxially with the first and second openings and the receptacle. A first fastener has first and second ends and a first shaft with a first diameter passing through the first opening, the first bore, the receptacle, and the second opening. The first fastener has a head at the first end with a first bearing surface disposed against the first rib. The second end of the first fastener is gripped by the first receptacle to provide a predetermined compression of the first and second contact surfaces against the first end of the compensation bracket configured to fixedly retain the headlamp module at a desired position with respect to the rigid support structure. At least one of the first bore or the first and second openings receiving the first shaft has an open diameter greater than the first diameter so that the desired position is adjustable. The predetermined compression is adapted to allow sliding between the first end of the compensation bracket and the first and second contact surfaces in response to an external force greater than a predetermined force acting in a plane parallel to the first and second contact surfaces. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a perspective view of a headlamp module and compensation bracket of the present invention. 
           [0009]      FIG. 2  is a partially exploded view of the headlamp module and bracket of  FIG. 1 . 
           [0010]      FIG. 3  is a partially exploded, perspective view of mounting features on the headlamp module with U-nuts. 
           [0011]      FIGS. 4 ,  5 , and  6  are top, side, and isometric views of the compensation bracket of  FIG. 1 , respectively. 
           [0012]      FIG. 7  is a perspective view of the compensation bracket between the headlamp module ribs with the fastening bolts removed. 
           [0013]      FIGS. 8 and 9  are vertical and horizontal cross sections, respectively, of the mounting features showing the internal clearances around the fastening bolt. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0014]    Referring to  FIGS. 1-3 , a headlamp module  10  includes a housing component  11  with a mounting section  12  that connects with a compensation bracket  13 . Bracket  13  has a first end  16  for joining with mounting section  12  and a second end  17  that connects to a rigid support structure of the vehicle such as a grille opening reinforcement (GoR)  14  or another cross car frame member. The vehicle has a front-to-rear direction  15  coinciding with the vehicle&#39;s direction of travel. This is also the main direction in which collision with an impactor would occur. 
         [0015]    As shown in  FIG. 2 , first end  16  of bracket  13  has first and second bores  18  and  19  which extend perpendicularly to vehicle direction  15 . Mounting section  12  on headlamp housing  11  includes first and second parallel, upstanding ribs  20  and  21  to define a channel  28  with an axis aligned substantially parallel with vehicle direction  15 . Channel  28  has first and second contact surfaces  30  and  31  which slidably receive first end  16  of bracket  13 . Ribs  20  and  21  prevent bracket  13  from moving in the cross-car direction. 
         [0016]    First rib  20  has a first opening  22  which may be formed as a U-shaped slot opened at the top to provide a height adjustment of the mounting position. Second rib  21  has a second opening  23  disposed coaxially with first opening  22 , which may also be formed as a U-shaped slot. First rib  20  has a third opening  24  coaxially disposed with a fourth opening  25  on second rib  21 , both of which may also be U-shaped slots. A first U-nut  26  is slidably clipped onto second rib  21  and has a first receptacle  32  disposed coaxially with openings  22  and  23 . U-nut  26  may provide a portion of second contact surface  31 . Similarly, a U-nut  27  is slidably clipped onto second rib  21  over fourth opening  25  to place its second receptacle  33  coaxially with openings  24  and  25 . Preferably, receptacles  32  and  33  may be threaded in order to secure first and second fastening bolts  34  and  35 . More specifically, a shaft  36  of first fastening bolt  34  passes through first opening  22 , bore  18 , opening  23 , and receptacle  32  so that a bolt head  37  bears against first rib  20  and a threaded end  38  is gripped by receptacle  32 . Shaft  36  of fastening bolt  34  has a first diameter in the regions passing through openings  22  and  23  and bore  18 . Likewise, fastening bolt  35  has a shaft  40  having a second diameter (which may be equal to the first diameter) passing through openings  24  and  25  with a threaded end  42  received by receptacle  33  and a head  41  bearing against first rib  20 . 
         [0017]    Fastening bolts  34  and  35  may be tightened to provide a predetermined compression of contact surfaces  30  and  31  against first end  16  of bracket  13 , wherein the compression is configured to fixedly retain the headlamp module at a desired position with respect to the rigid support structure. At least either 1) the open diameters of openings  22  and  23  or 2) the open diameter of bore  18  is greater than the first diameter of shaft  36  so that the relative position between bracket  13  and mounting section  12  is adjustable. During assembly, first end  16  and bores  18  and  19  are more easily aligned with bolts  34  and  35  extending through the rib openings and into U-nuts  26  and  27 . The open diameters of openings  24  and  25  and/or bore  19  are likewise greater than the diameter of shaft  40 . Although bores  18  and  19  are shown with circular cross-sections, other shapes are possible. Moreover, clearances for movement in different directions can be accommodated by providing different directions for any non-circular diameter increases of either the rib openings or the bracket bores. 
         [0018]      FIGS. 4-6  show compensation bracket  13  in greater detail. In the side view of  FIG. 5 , dashed lines inside bore  18  illustrate an alternative cross-sectional shape (e.g., oval) in which the direction of the increased diameter of bore  18  would provide a front-to-back position adjustment. Bore  19  has a circular cross-section with a diameter D 1  in which bracket  13  provides both front-to-back and up-and-down adjustment. As shown in  FIG. 6 , second end  17  includes a mechanical connector  45  of any suitable type for joining bracket  13  to the rigid structure. 
         [0019]      FIG. 7  shows the initial installation of bracket  13  into channel  28  so that bores  18  and  19  are aligned within openings  24  and  25 . U-nuts  26  and  27  may be moveable on rib  21  in order to align the receptacles with bores  18  and  19 . Alternatively, rib  21  may include respective recesses for receiving U-nuts  26  and  27  at a fixed position, or U-nuts  26  and  27  may otherwise be made non-slidable on rib  21 . Nevertheless, the larger diameter of bores  18  and  19  ensure that the receptacles are accessible to the fasteners. Even if U-nuts  26  and  27  are not slidable on rib  21 , bracket  13  is slidable over the U-nuts whether it contacts them or not. 
         [0020]      FIG. 8  is a cross section showing the vertical clearance between shaft  36  and bore  18 . Prior to tightening of fastener  34 , up and down movement is allowed both by the clearance within bore  18  and the upward openings of U-shaped slots  22  and  23 . 
         [0021]      FIG. 9  is a horizontal cross-section showing the horizontal clearance between shaft  34  and bore  18 . Thus, movement in the front-two-back direction is permitted by the horizontal clearance of bore  18 . 
         [0022]    During assembly, the fastening bolts are tightened according a torque that results in a fixed retention and support of the headlamp module. Due to the planar nature of the contact surfaces, sliding is prevented only by the compression force. According to the present invention, the predetermined compression is adapted to allow sliding between the compensation bracket and the sliding contact surfaces of channel  28  in response to an external force greater than a predetermined force acting in a plane parallel to the contact surfaces. In other words, a collision force which is acting downward and/or rearward of the vehicle causes a relative movement between the headlamp housing and the fixed vehicle structure. A portion of the energy of impact is absorbed by the sliding response, thereby lowering the acceleration to the impacting body. Moreover, the likelihood of damage to the headlamp module is reduced.