Abstract:
A motor vehicle front unit assembly ( 1 ) comprising a rigid front surface ( 10 ), a bumper skin ( 15 ), two flexible beams ( 30 ) extending laterally, whereof one first end is connected to the front surface ( 10 ) and a second end is connected to a front part ( 2   a ) of a body fender ( 2 ), and two optical units ( 20 ). The bumper skin ( 15 ) is fixed on the first end of each flexible beam ( 30 ) and each end is adjustable along a first axis X and a second axis Y on the front face ( 10 ) to adjust each optical unit ( 20 ) relative to the bumper skin ( 15 ), the third axis Z being nonadjustable.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a motor vehicle front unit assembly. 
     DESCRIPTION OF THE RELATED ART 
     The front units of motor vehicles generally comprise a front face which has a central portion and two lateral portions, a bumper and a bumper skin which forms a fairing for this bumper, two beams each extending from the central portion, to which it is fixed, to a respective lateral portion and forming support members for the bumper skin, and two optical units (i.e., headlight or headlamp). Each optical unit is supported by a respective lateral portion and has a peripheral lateral portion which is suitable for co-operating with a complementary recess of a respective front wing portion. 
     A major problem encountered by automotive manufacturers involves positioning the optical units precisely relative to the outer elements constituted by the wings and the bumper skin. This adjustment is significant owing to the fact that a defect in terms of surface continuity of the visible portion of the optical unit, that is to say, of the light, of the corresponding wing and the bumper skin significantly impairs the aesthetic quality of the vehicle. Furthermore, a precise adjustment of the position of the optical unit relative to the wing and the bumper skin is difficult to maintain between the operation for mounting the optical units on the front face and the operation for assembly of the equipped front unit on the body of the motor vehicle. 
     These difficulties have been exacerbated by the standardisation of unitary optical units which integrate the indicating function (i.e., turn signal function), whilst the portion which forms the indicator was previously adjustable relative to the main portion of the optical unit so that it was relatively straightforward to compensate for positioning tolerances. 
     In the case of unitary optical units which integrate the indicator function, each optical unit is generally fixed at four points to the front face which constitutes a rigid component. 
     After assembling each optical unit, they are mounted on the body of the vehicle and the front end of the corresponding body wing is fixed to each of these optical units. 
     In a subsequent operation, the automotive manufacturer carries out the adjustment of the position of the optical unit relative to the wing by acting on two points for fixing the optical unit to the front face. 
     The major disadvantage of this operating method is in particular this reworking operation at the end of assembly, which involves adjusting the position of the optical unit. Furthermore, this fine adjustment must be carried out for all vehicles taking into account the production and assembly tolerances of the various elements involved. Since these elements are also susceptible to deformations to a greater or lesser extent, the aligned surface states obtained with these adjustments are not stable in the long term and may require additional adjustments. 
     To this end, document EP-A-1 232 932 discloses a motor vehicle front unit assembly which comprises a front face, which has a central portion and two lateral portions, a bumper skin, two flexible beams which extend laterally and which form supports for the bumper skin, each of which has a first end which is connected to the central portion and a second end which is intended to be connected to a front wing portion of the body of the vehicle, and two optical units, each of which is rigidly fixed to a respective beam. 
     The structure described in this document allows automatic and permanent positioning of the visible contours of the optical units relative to the corresponding wing ends and the bumper skin. 
     At the same time, this structure provides precise relative positioning of the wing ends and the bumper skin. However, it may also be desirable, in order to improve the aesthetic qualities of the vehicle, to provide a continuity in terms of appearance of the optical units and the bumper skin with other body elements, such as, for instance, the bonnet of the motor vehicle. 
     Furthermore, some bumper skins have shapes which surround each optical unit over a portion of the inner perimeter thereof so that it is necessary to be able to take up the clearance between the bumper skin and the optical units in this inner portion. 
     SUMMARY OF THE INVENTION 
     The object of the invention is therefore to provide a motor vehicle front unit assembly in the form of a pre-assembled module whose various elements formed by the optical units and the bumper skin can be automatically adjusted and locked in position in order to provide a mutual continuity in terms of appearance. 
     The invention therefore relates to a motor vehicle front unit assembly, comprising:
         a rigid front face which has a central portion and two lateral portions,   a bumper skin,   two flexible beams which extend laterally, a first end of which is connected to the central portion of the front face and a second end of which is connected to a front portion of a body wing, and   two optical units, each of which is rigidly fixed to a respective flexible beam,
 
characterised in that the bumper skin is fixed to the first end of each flexible beam and each first end can be adjusted along a first axis Z and along a second axis Y on the central portion of the front face for an adjustment of each optical unit relative to the bumper skin.
       

     According to other features of the invention:
         the adjustment along the first axis Z of the first end of each beam is obtained using indexing means which comprise a sleeve which is fixedly joined to the front face and which extends perpendicularly relative to this front face and a member which is provided on the beam and which extends perpendicularly relative to this beam, and which is capable of sliding axially in the sleeve, the member being locked by the sleeve along the first axis Z,   the sleeve comprises means for locking the member along a third axis X,   each beam comprises means for indexing the bumper skin along the first axis Z and along the third axis X,   the means for indexing the bumper skin are formed by at least one hollow portion which is provided on the upper portion of the beam and which extends transversely in the general direction of this beam and by at least one complementary protruding portion which is provided on the upper portion of the bumper skin,   each beam comprises a flexion zone which is arranged between the first end and the fixing of the corresponding optical unit, and   the flexion zone is formed by a substantially vertical recess which is provided on the beam.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood from a reading of the following description, given by way of example and with reference to the appended drawings, in which: 
         FIG. 1  is a perspective schematic view of a front unit assembly in accordance with the invention, 
         FIG. 2  is an exploded, schematic perspective view of the various elements which form the front unit assembly in accordance with the invention, 
         FIG. 3  is a schematic perspective view of the front face of the front unit assembly in accordance with the invention, 
         FIG. 4  is a perspective schematic view of a flexible beam of the front unit assembly in accordance with the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIGS. 1 and 2  schematically illustrate a front portion of a motor vehicle comprising a front unit assembly  1  which is partially illustrated, a front end  2   a  of a body wing  2  and a front end  3  of a bonnet. 
       FIGS. 1 and 2 , and  FIGS. 3 and 4 , have been orientated along three axes X, Y and Z which correspond to the normal orientation of a motor vehicle, that is to say, the longitudinal axis X which is orientated in the direction of forward travel, the transverse axis Y which is orientated from right to left, from the viewpoint of the driver, and the vertical axis Z which is orientated from bottom to top, respectively. All the terms used in the remainder of the description, which may indicate a direction or a position, must be understood with reference to this system of axes. 
     The front portion of the vehicle illustrated in  FIGS. 1 and 2  is symmetrical or almost symmetrical relative to a vertical centre plane of the vehicle so that, for reasons of simplification, the following description will be given for one side of this front portion, the other side being identical. 
     The front unit assembly  1  of the vehicle comprises a substantially rigid structure which is constituted by a front face which is generally designated  10  and which has a central portion  11  which is generally in the form of a frame and, at each side, a lateral portion  12 , as illustrated in  FIG. 3 . 
     The front unit assembly  1  also comprises a bumper skin  15  which is produced, for example, from a component of plastics material and which is arranged over the entire width of the front face  10 , as illustrated in  FIG. 1 , laterally extending beyond the lateral portions  12  of the front face  10  and pressing on an edge of the front end  2   a  of the wing  2  so as to be aligned therewith. 
     The front unit assembly  1  further comprises, at each lateral side, an optical unit  20  which is mounted on the front face  10  in complementary shapes which are provided in the wing  2 , the bonnet  3  and the bumper skin  15 , below an upper extension  13  of the front face  10  and above an upper edge  16  of the bumper skin  15 , as illustrated in  FIGS. 1 and 2 . 
     The optical unit  20  is fixed to the lateral extension  13 , for example, by means of two lugs  21 . 
     The front unit assembly  1  also comprises, at each lateral side, a flexible and curved beam which is generally designated  30  and which is illustrated on a larger scale in  FIG. 4 . Each flexible beam  30  extends substantially laterally in the direction of the bumper skin  15  and comprises a central portion  31  whose front face is provided with a first pin  32  which is intended to co-operate with a first lower lug  22  of the optical unit  20  for indexing this optical unit  20  along the axes X and Z and a second pin  33  which is intended to co-operate with a second lower lug  23  of the optical unit  20  for indexing this optical unit  20  along the axes XYZ. 
     The flexible beam  30  comprises a first end  34  which is connected to the central portion  11  of the front face  10  and to which the upper edge  16  of the bumper skin  15  is also fixed in order to obtain a positioning of this bumper skin  15  along axis Z. The flexible beam  30  comprises a second end  35  which is connected to the front portion  2   a  of the body wing  2 , as illustrated in  FIG. 1 . The central portion  31  of the flexible beam  30  comprises, on the lower edge thereof, a lug  36  for fixing to the central portion  11  of the front face  10 . 
     Generally, the first end  34  of each flexible beam  30  can be adjusted along a first axis Z and along a second axis Y on the central portion  11  of the front face  10  for an adjustment of each optical unit  20  relative to the bumper skin  15 . 
     To this end, the adjustment along these two axes is obtained using indexing means which comprise a hollow sleeve  14  which, in the embodiment illustrated in  FIG. 3 , is fixedly joined to the central portion  11  of the front face  10  and extends perpendicularly relative to this front face  10 , protruding from the front face towards the rear along the longitudinal axis thereof which is directed substantially along the longitudinal axis X of the vehicle. This sleeve  14  comprises an elongate hole  14   a  in the direction X of the axis of the sleeve  14 . 
     For example, the hole  14   a  has a rectangular cross-section, the largest sides of which are horizontal. The hole  14   a  may have other shapes, such as, for example, an oblong shape. 
     Furthermore, the indexing means comprise a member  37  which is provided on the beam  30  and which extends perpendicularly relative to this beam, towards the rear of the motor vehicle, along the longitudinal axis thereof which is orientated substantially along the longitudinal axis X of this vehicle. The member  37  is capable of sliding axially in the hole  14   a  of the hollow sleeve  14 . 
     In the embodiment illustrated in  FIG. 4 , the member  37  has a rectangular cross-section whose height h 1  is substantially equal to the height h 2  of the hole  14   a  of the sleeve  14  and whose width l 1  is less than the width l 2  of this hole  14   a  in order to allow the member  37  and consequently the corresponding flexible beam  31  to be able to be displaced along the transverse axis Y, all being locked along the axis Z. 
     Each sleeve  14  also comprises means (not illustrated) for locking the corresponding member  37  along the axis X, which allows the member  37  and the sleeve  14  to be fixedly joined in a definitive manner with a possibility of disassembly. These locking means are constituted by any appropriate device of the conventional type, such as, for example, a screw/nut pair or a pin. 
     Furthermore, each flexible beam  30  comprises means for indexing the bumper skin  15  along the axes X and Z. These indexing means which are illustrated in particular in  FIG. 4  comprise at least one hollow portion  38  which is provided on the upper portion of the central portion  31  of the beam  30 . In the embodiment illustrated in this Figure, the hollow portion is formed by at least one channel  38  and, for example, by two channels  38  which extend transversely in the general direction of the beam  30 . 
     These indexing means comprise at least one complementary protruding portion which is provided at the upper portion of the bumper skin and which, in the embodiment illustrated in  FIGS. 1 and 2 , is constituted by the upper edge  16  of the bumper skin  15 , in order to fasten this bumper skin  15  to each beam  30 , with a possibility of relative adjustment movement in the general direction of this beam  30 , that is to say, along the axis Y. 
     Each flexible beam  30  optionally comprises a flexion zone  40  which is arranged between the first end  34  and the central portion  31  and, more particularly, between the first end  34  for fixing the bumper skin  15  and the central portion  31  on which the corresponding optical unit  20  is mounted. This flexion zone is formed, for example, by a substantially vertical recess  40 . This recess  40  is advantageous in particular when the end portion  2   a  of the wing  2  fixed to the second end  35  of the corresponding beam  30  is rigid.