Abstract:
A lower crossbeam for a window opening, the lower crossbeam to be installed between an edge of a windshield and a firewall. The lower crossbeam includes: a first portion having an attachment edge connected to a firewall and a receiving edge for receiving the windshield edge; and a second portion having a bearing edge and a connecting edge connected to the first portion while dividing the first portion into a receiving portion and an attachment portion. The bearing edge is connectable to the firewall so as to form a transverse hollow shell between the second portion and the attachment portion.

Description:
TITLE 
     The present invention relates to a window opening lower crossbeam intended to be installed at the front of a motor vehicle. 
     BACKGROUND 
     The front of motor vehicles has a structure in which the windshield, the hood and the bulkhead separating the engine compartment from the passenger compartment meet. The window opening lower crossbeam is secured to the bulkhead in such a way as to be able to support the windshield on which the latter rests. Hence, the lower crossbeam is installed transversely and, according to the vertical and longitudinal components of the vehicle, extends between a lower edge of the windshield and the bulkhead which itself extends substantially plumb with said windshield. In order to perform its role of supporting the windshield, the window opening lower crossbeam has to be sufficiently strong. Hence it usually comprises two transverse parts combined with one another, an upper window opening lower crossbeam and a lower window opening lower crossbeam, so as to form a transverse box structure, or hollow body, on which the lower edge of the windshield rests directly. To do this, of the two transverse parts, a first part having a fixing transverse edge and, opposite, a receiving transverse edge, is fitted between the bulkhead and the windshield. The first part constitutes the upper window opening lower crossbeam. The fixing edge is therefore engaged on the bulkhead, while the lower edge of the windshield rests in the receiving transverse edge. The second transverse part of the crossbeam, which has a transverse connecting edge and an opposite transverse resting edge, is fitted against the first part in such a way that the connecting edge is connected to the first part between the first fixing edge and the first receiving edge of the first part and that the resting edge is connected to the receiving transverse edge of the first part, thereby forming a tubular element therewith, which tubular element constitutes the transverse box structure. The second part constitutes the lower window opening lower crossbeam. As a result, the lower edge of the windshield is held directly by the transverse box structure which itself rests laterally in the structure of the motor vehicle, and notably on the shock-absorber cups. 
     Moreover, the connecting edge of the second transverse part divides the first part into a receiving portion which extends toward the receiving edge thereby forming one wall of the transverse box structure and an opposite fixing portion which extends toward the fixing edge of the first part and which meets the bulkhead. This fixing portion is, by nature, deformable and in the event of a pedestrian impact, i.e. in the event of the relative movement of an individual toward the windshield of the vehicle, allows the windshield precisely to be able to push in in order to dissipate some of the mechanical energy generated by the impact and thus as far as possible safeguard the vital parts of said pedestrian, notably the pedestrian&#39;s head. 
     Reference may be made to document U.S. Pat. No. 6,193,304 which describes such a shock-absorbing lower crossbeam. 
     However, the transverse box structure which is required for supporting the windshield limits the ability of the aforementioned fixing portion to deform and, at the same time, limits the possibilities for dissipating the energy generated by the impact. 
     So, one problem which arises and which the present invention seeks to overcome is that of supplying a window opening lower crossbeam which, while supporting the windshield of the motor vehicle, has a better ability to deform in order to safeguard individuals in the event of an impact. 
     BRIEF SUMMARY 
     To this end, the present invention proposes a lower crossbeam for a motor vehicle front window opening and intended to be installed transversely in a motor vehicle between a lower edge of a windshield and a bulkhead situated plumb with the windshield, said crossbeam comprising a first and a second transverse part which are substantially parallel to one another, said first part having a fixing edge that can be connected to said bulkhead and a receiving edge opposite said fixing edge to accept said windshield lower edge, while said second part has, firstly, a connecting edge connected to said first part between said first fixing edge and said first receiving edge, thereby dividing said first part into a receiving portion extending toward said receiving edge and an opposite fixing portion extending toward said fixing edge and, secondly, a resting edge opposite said connecting edge, said second and first transverse parts being intended to form a transverse box structure to increase the rigidity of said crossbeam, whereas said first part is able to bend along said connecting edge when said windshield is pushed in under the effect of an impact. According to the invention, said resting edge of said second part can be connected to said bulkhead in such a way as to form said transverse box structure between said second part and said fixing portion of said first part in a position distant from said windshield lower edge, whereas said receiving portion extends between said transverse box structure and said windshield lower edge. 
     Thus, one feature of the invention lies in the use of the transverse box structure, or hollow body, which is no longer directly in contact with the lower edge of the windshield but lies in a position distant from this lower edge, toward the bulkhead, whereas the receiving portion of the first crossbeam part itself does precisely extend between the transverse box structure and the lower edge of the windshield. In that way, it is no longer the transverse box structure directly which absorbs the load in the event of a pedestrian impact and the pushing-in of the windshield, but the receiving portion of the first transverse part which then has a tendency to bend toward the box structure along the connecting edge of the second part connected to the first part of the crossbeam. The transverse box structure effectively forms a beam which has a far lower ability to bend under load than does a simple wall such as the receiving portion of the first transverse part. Hence, thanks to the abilities of this receiving portion to deform, in the event of a pedestrian impact with the windshield, this windshield will be pushed in as the receiving portion supporting it gradually undergoes plastic deformation and bends. 
     According to one particularly advantageous feature of the invention, said fixing portion of said first part has a transverse zone running alongside said receiving portion substantially perpendicular to said second part. Thus, the transverse zone forms, with the second part, two transverse box structure walls which are adjacent at right angles, thus improving the rigidity thereof. For preference, said second part has a recess forming an inlet opening providing access to the inside of the transverse box structure. This inlet opening notably allows air to be admitted to the ventilation circuit, as will be explained in greater detail hereinafter. 
     Furthermore, and according to one particularly advantageous embodiment of the invention, said vehicle comprises a heating duct transverse lower wall able to be connected to said bulkhead, and said fixing edge of said first part is connected to said bulkhead via said transverse lower wall. This heating duct transverse lower wall extends in a longitudinal direction of the vehicle, from the bulkhead against which it rests, toward the front of the vehicle plumb with the lower edge of the windshield and with an edge of the hood of the vehicle adjacent to said windshield lower edge. Thus, the fixing edge of the first crossbeam part is secured to the bulkhead via the heating duct transverse lower wall. 
     In addition, said resting edge of said second part is preferably likewise connected to said bulkhead via said heating duct transverse lower wall. In that way, the portion of transverse lower wall comprised between the fixing edge of the first part of crossbeam and the resting edge of the second part, the second part itself and the fixing portion of the first part, then form a tubular structure that constitutes the transverse box structure. The latter is then directly connected to the bulkhead. 
     Moreover, said heating duct transverse lower wall has a first wall transverse edge, able to receive said fixing edge of said first part, and an opposite second wall transverse edge, able to extend plumb with said receiving edge of said first part. These two opposite wall transverse edges are bent toward one another to form a receptacle. In addition to guiding air toward the ventilation circuit, this receptacle is also intended to receive the water which runs off between the edge of the hood and the lower edge of the windshield so that this water can then be discharged. 
     Also, said heating duct transverse lower wall has a transverse portion which is sunken along said first wall transverse edge in an opposite direction to said fixing portion of said first part. In that way, water running off specifically between the edge of the hood and the lower edge of the windshield is conveyed under gravity into the sunken transverse portion. Advantageously, said sunken transverse portion has an orifice to form a discharge opening, along the bulkhead. Such an orifice is made in a lateral portion of the transverse lower wall. 
     According to one particularly advantageous embodiment of the invention, said vehicle further comprises two lateral shock-absorber cups situated substantially plumb with said receiving edge of said first part, and said heating duct transverse lower wall rests on said lateral shock-absorber cups. In that way, the lower crossbeam also rests laterally, via the heating duct transverse lower wall, on the lateral shock-absorber cups. 
     Advantageously, said first and second transverse parts of said crossbeam are made of a deformable metallic material, so as to be able to deform plastically in the event of an impact, the mechanical energy absorbed then being dissipated in the form of heat. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other specifics and advantages of the invention will become apparent from a reading of the description given hereinbelow of one particular embodiment of the invention, given by way of nonlimiting indication with reference to the attached drawings in which: 
         FIG. 1  is a schematic three-quarters front perspective view of a structural element of a motor vehicle including a window opening lower crossbeam according to the invention; 
         FIG. 2  is a schematic three-quarters rear perspective view of part of the structural element depicted in  FIG. 1 ; 
         FIG. 3  is a schematic view in axial section on the plane III-III of the part depicted in  FIG. 2 , supplemented by other components; 
         FIG. 4  is a schematic view in axial section on the plane IV-IV of the structural element depicted in  FIG. 1 , supplemented with other components; and 
         FIG. 5  is a schematic three-quarters front perspective view of another part of the structural element depicted in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a structural element  10  of a motor vehicle which extends transversely between an engine compartment  12  situated toward the front of the motor vehicle and a passenger compartment  14  situated toward the rear. The structural element  10  has a window opening lower crossbeam  16  which extends transversely under the window opening  18  of the motor vehicle. The structural element  10  also has two shock-absorber cup raisers  20 ,  22  opposite one another and on which a heating duct transverse lower wall  24  described in greater detail hereinafter rests laterally. The window opening lower crossbeam  16  comprises a first part  26 , or upper window opening lower crossbeam, and a second part  28 , or lower window opening lower crossbeam. The latter has a central recess  30  forming a first inlet opening through which the continuation of the first part  26  can be glimpsed. According to one particularly advantageous embodiment of the invention, the first and second parts  26 ,  28  are respectively each made from a single sheet metal component of a thickness of between 1 mm and 0.5 mm, for example 0.65 mm so as to be able to undergo plastic deformation if need be, as will be explained hereinafter. 
     The structural element  10  has two opposite legs  32 ,  34  between which, plumb with the window opening lower crossbeam  16 , there extends a bulkhead which has not been depicted in this  FIG. 1 . Furthermore, vertically, on the opposite side to the legs  32 ,  34 , there extend two lateral uprights  33 ,  35 , depicted here in part, and against which the respective lateral edges of a windshield not depicted in this  FIG. 1  rest. 
     Reference will be made to  FIG. 2  which shows again, but from a different angle, one,  32 , of the two opposite legs, one,  20 , of the two shock-absorber cup raisers and the first part  26  of the window opening lower crossbeam showing two perpendicular walls that will be described hereinafter and which is secured to a first curved edge  36  of the heating duct transverse lower wall  24  against which it rests. 
     Thus,  FIG. 3  again schematically shows the window opening lower crossbeam first part  26  and the second part  28  which was visible in  FIG. 1 . It also again shows said one shock-absorber cup raiser  20  and the curved first edge  36  of a heating duct transverse lower wall  38  which presses against an upper part  40  of the shock-absorber cup raiser  20 . 
     In addition, this  FIG. 3  illustrates additional components to the structural element  10 . Thus, a bulkhead  42  which extends substantially vertically between the passenger compartment  14  and the engine compartment  12 , has resting against it the heating duct transverse lower wall  38  in the region of the curved edge  36 . Also, a windshield  44  having a windshield lower edge  45  is partially depicted and extends in line with the window opening lower crossbeam  16 , the windshield lower edge  45  running alongside the edge of a hood  43 . Before this lower edge is described in detail, a more specific description will first be given of the heating duct transverse lower wall  38  on which the window opening lower crossbeam  16  specifically rests and which itself rests on the bulkhead  42 . 
     Thus the heating duct transverse lower wall  38  extends not only laterally but also longitudinally between its first curved edge  36  situated toward the passenger compartment  14  and an opposite second curved edge  46  situated toward the engine compartment  12 . In addition, it is inclined from the second curved edge  46  toward the first curved edge  36  and has, firstly, a first part  48  resting against the upper part  40  of the shock-absorber cup raiser  20  and, secondly, a second part  50  which is sunken along the first curved edge  36 . In that way, the first part  48  of the heating duct transverse lower wall  38  extends plumb with a slot  52  which extends transversely between the edge of the hood  43  and the lower edge of the windshield  45  so as to be able to collect water running through this slot  52 . Hence, under the effect of gravity, the water will flow toward the sunken second part  50  in order then to be discharged through an orifice  54  formed in the bottom of this sunken second part  50 . As will be explained in the remainder of the description, the heating duct transverse lower wall  38  is also able to guide air entering through the slot  52  toward the ventilation installation. 
     The window opening lower crossbeam  16 , considered in line with the shock-absorber cup raiser  20 , will now be described in greater detail, still with reference to  FIG. 3 . 
     Thus, the window opening lower crossbeam  16 , comprising the upper window opening lower crossbeam, or first part  26 , and the lower window opening lower crossbeam, or second part  28 , extends transversely from one upright  33  to the other  35 . The first part  26  has a fixing edge  56  extended by a return  58  which itself comes to rest against a rim  60  of the sunken part  50  turned back in the continuation of the first curved edge  36 . Opposite the fixing edge  56 , the first part  26  has an opposite receiving edge  62  able to receive the lower edge of the windshield  45 . This lower edge is secured thereto using a bead of mastic  64 . 
     As for the second part  28 , it has a connecting edge  66  bent back and in the opposite direction a bearing edge  68  which is likewise bent back. The bent-back connecting edge  66  is connected to the first part  26  for example by spot welds, whereas the resting edge  68  is connected to the first part of the heating duct transverse lower wall  38  at the edge of the sunken second part  50 . It may also be connected thereto by spot welds. Thus, the connected connecting edge  66  divides the first part  26  into two portions, a receiving portion  70  which extends like a bracket from the connecting edge  66  as far as the receiving edge  62 , and an opposite fixing portion  72  which extends from the connecting edge  66  to the fixing edge  56 . The receiving portion  70  has a first ledge-like part  74  extending substantially horizontally between the connecting edge  66  and the windshield  44 , and a first inclined part  76  extending facing the windshield  44 , while the opposite fixing portion  72  has a second ledge-like part  78 , or transverse zone, in the continuation of the first ledge-like part  74 , and a second part  80  bent back, extending as far as the fixing edge  56 . The first ledge-like part  74  extends, in the longitudinal direction of the vehicle, over a width of between 80 mm and 150 mm, whereas the second ledge-like part  78  extends over a width of between 100 mm and 200 mm. It may be noted that this width varies transversely and, particularly in the case of the latter ledge-like part, between the middle of the window opening lower crossbeam  16  and the ends thereof. 
     Furthermore, the second part  28  extends substantially perpendicular to the two ledge-like parts  74 ,  78 , resting against the heating duct transverse lower wall  38 , while the second bent-back part  80  of the fixing portion  72  extends substantially parallel to the second part  28  to rest against the first curved edge  36  of the heating duct transverse lower wall  24 . In that way, the second part  28  of the window opening lower crossbeam  16 , the second ledge-like part  78 , the second bent-back part  80  on the one hand, and the sunken second part  50  of the heating duct transverse lower wall  38  on the other hand, constitute a tubular element here referred to as a transverse box structure  82  or hollow body. This transverse box structure  82  rests on the bulkhead  42  and also in part at its opposite ends on the upper part  40  of the shock-absorber cup raisers  20 ,  22 . By contrast, it extends some distance away from the windshield  44  and, more specifically, from the lower edge  45 , whereas the receiving portion  70  itself, by acting like a bracket out from the transverse box structure  82 , extends as far as the connecting edge  66  of the second part  28  to meet the windshield lower edge  45  and receive it in its opposite receiving edge  62 . 
     Before setting out the advantages of the structure described hereinabove, the same window opening lower crossbeam  16 , considered not now in line with the shock-absorber cup raiser  20  but in the median plane of the motor vehicle or, more specifically, between the shock-absorber cup raisers  20 , will first of all be described with reference to  FIG. 4 . That figure shows the same components again, but some with a different shape because the window opening lower crossbeam  16  has curved parts. Hence, the parts which differ in shape will bear the same references followed by a “′” symbol. 
     Thus, in the same way, the figure shows the lower edge  45  of the windshield  44  which is kept bonded against the receiving edge  62  of the first part  26  by means of the bead of mastic  64 . It also again shows the bulkhead  42  supporting the sunken second part  50  of the heating duct transverse lower wall  38 , which has a restricted first part  48 ′ extended by the curved edge  46 ′. The second part  28  has kept the same shape and the figure again shows the central recess  30  that forms the first air inlet opening admitting air to the transverse box structure  82 ′. This air comes in from the slot  52 . Moreover, the second ledge-like part  78 ′ is not as wide whereas the second bent-back part  80 ′ is in the form of an inclined plane leading as far as the fixing edge  56 ′ thereof. The second bent part  80 ′ has another recess  86  forming an air outlet leading to the vehicle ventilation system. 
     Moreover, and according to one particularly advantageous embodiment of the invention, a Z section  88  is fitted along the sunken second part  50  to form another tubular element  90  forming a second hollow body. One of the flanges  92  of the Z section is connected to the restricted first part  48 ′ of the heating duct transverse lower wall  38 , from underneath, while the other flange  94  is secured to the bottom of the sunken second part  50 . Thus, the Z section  88  forms a transverse and additional central reinforcement attached to the heating duct transverse lower wall  38 . That notably makes it possible to stiffen the zone extending transversely under the window opening and therefore stiffen the acoustics within the motor vehicle. 
     Finally, reference will be made to  FIG. 5  to complete the structural description of the window opening lower crossbeam  16 , before returning to  FIGS. 3 and 4  for a description of the functionalities thereof. This  FIG. 5  illustrates the other end of the window opening lower crossbeam  16  in a three-quarters front view from the engine compartment. It again shows the shock-absorber cup  22 , the leg  34  and the opposite upright  35  together with the first  26  and second  28  parts of the window opening lower crossbeam  16 . Moreover, it also again shows the first part  48  of the heating duct transverse lower wall  38  and the curved second edge  46  thereof. In addition, it may be seen that the second part  28  of the window opening lower crossbeam  16  has, in the region of the shock-absorber cup raiser  22 , a second recess  96  allowing the discharge of water but also allowing air into the transverse box structure  82 . 
     With reference to  FIGS. 3 and 4  it can be clearly seen that the transverse box structure  82 ,  82 ′, made as a single piece, lies some distance from the zone of connection between the lower edge  45  of the windshield  44  and the receiving edge  62  of the upper window opening lower crossbeam, or first part,  26 . 
     Thus, thanks to this arrangement, in the event of a pedestrian impact in which the lower edge  45  of the windshield  44  is pushed in toward the bulkhead  42  in the direction of the arrow F, the receiving portion  70  of the first part  26  will then deform, pivoting in a counterclockwise direction about the zone of connection between the connecting edge  66  of the second part  28  and the first part  26 . In that way, by deforming and bending, the receiving portion  70  absorbs the mechanical energy generated by the pedestrian impact and dissipates it partially in the form of heat. In addition, because the windshield  44  and the transverse box structure  82 ,  82 ′ are distant from one another, when the windshield  44  is pushed in, the extent of its movement corresponding to the deformation of the receiving portion  70  alone is greater than it would have been had the lower edge  45  been resting directly against the transverse box structure  82 ,  82 ′. As a result, a greater amount of mechanical energy can be absorbed, thereby safeguarding the pedestrian in the impact. 
     What is more, such an arrangement not only allows air to flow from outside to the ventilation system through the transverse box structure  82 ,  82 ′ but also allows the water collected in the heating duct transverse lower wall  38  to be discharged.