Abstract:
A motor vehicle having a windshield, A-pillars laterally enclosing the windshield and a window cross member connected to the A-pillars is provided. The window cross member supports a lower edge of the windshield in that it comprises a support section touching the windshield. The window cross member includes a point of action fastened to the A-pillar, which is offset in the direction of a surface normal of the windshield against the support section. The window cross member also includes a compressible section that connects the point of action with the support section.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to German Patent Application No. 10 2011 115 588.4, filed Oct. 11, 2011, which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     This application pertains to a motor vehicle body with a front hood, and a window cross member supporting a front lower edge of the windshield. 
     BACKGROUND 
     Such a motor vehicle is known from DE 10 2009 029 921 A1. With this conventional motor vehicle, the window cross member comprises a support leg whose front edge is formed by a support section touching the windshield and which, during an accident, for example, the head of a pedestrian striking the lower edge of the windshield can yield in order to reduce the risk of serious head injuries. 
     When the head strikes a middle region of the support section, the support section can yield approximately uniformly on both sides of the head and the stiffness of the window cross member can be set so that the legal requirements regarding the HIC (Head Injury Criterion) are adhered to. 
     However, it is being shown in practice that during a head impact in the vicinity of the A-pillars laterally enclosing the windshield deviating HIC-values are obtained. The reason for this is the connection of the window cross member to the A-pillars, which renders a yielding of the support section in the vicinity of the A-pillars difficult. 
     Thus, it may be desirable to create a motor vehicle wherein the fluctuation of the HIC-values along the window cross member is reduced. In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background. 
     SUMMARY 
     According to various exemplary embodiments, provided is a motor vehicle having a windshield, the A-pillars laterally enclosing the windshield and a window cross member supporting a lower edge of the windshield, connected to the A-pillars and touching the windshield having a support section, in which an engagement point of the window cross member fastened to the A-pillar is offset in the direction of a surface normal of the windshield against the support section and the window cross member comprises a compressible section which connects the support section to the point of action. By way of shaping and material thickness of the compressible section, the resilience of the support section can be adjusted also in the immediate vicinity of the A-pillar substantially uninfluenced by the latter. 
     In one exemplary embodiment, the window cross member is unitarily formed from a flat material, for example, a sheet metal. 
     In one example, according to various exemplary embodiments, the compressible section can comprise a strip of flat material, which is angled off at an end of the window cross member facing one of the A-pillars. Generally, the strip is angled off immediately from the support section of the window cross member. 
     In order to be effectively compressed during an impact, the strip is generally oriented substantially in the direction of the surface normal of the windshield. 
     In order to be able to reproducibly adjust the force at which the strip would yield, it is practical if the strip is not exactly oriented in the direction of the surface normal, but at least comprises a section that is near the window and near the engagement point, which are separated from each other through a buckling section or bending section. 
     A person skilled in the art can gather other characteristics and advantages of the disclosure from the following description of exemplary embodiments that refers to the attached drawings, wherein the described exemplary embodiments should not be interpreted in a restrictive sense. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein: 
         FIG. 1  is a perspective view of a part of a motor vehicle body according to various teachings of the present disclosure and of an exemplary impactor simulating the impact of the head of a pedestrian; 
         FIG. 2  is a schematic cross section through the window cross member and its surroundings immediately before an impact; 
         FIG. 3  is a schematic cross section through a part of an A-pillar and the windshield adjoining thereto according to one exemplary embodiment of the present disclosure; 
         FIG. 4  is a cross section analogous to  FIG. 3  according to another exemplary embodiment; and 
         FIG. 5  is a cross section analogous to  FIG. 3  according to another exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or the application and uses of the present disclosure. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. 
       FIG. 1  shows a perspective view of a part of a motor vehicle body, to which the various teachings of the present disclosure can be applied. Visible is the rear region of a front hood  1  and a window opening following said region which with the finish-assembled vehicle receives a windshield, flanked by A-pillars  2 . An instrument panel covering is omitted in  FIG. 1  in order to be able to show installations  3  of the instrument panel located below and a window cross member  4  formed from a single-layer sheet metal cutting, which in the finished vehicle are concealed under the instrument panel covering. A rear edge  5  of the cross member supports itself on the upper edge of a separating wall, which, not visible in  FIG. 1 , extends between passenger cell and engine compartment. A front edge of the window cross member  4  forms a support section  6 , which supports a front lower edge of the windshield in direct contact. 
     An impactor  7  shown above the window cross member  4  shows the position in which, when the vehicle collides with an adult pedestrian of normal size and said pedestrian strikes the front hood  1 , the head of said pedestrian strikes the bodywork. The impact point is located in a lower region of the windshield above the window cross member  4  and the impact direction approximately corresponds to the surface normal of the windshield at this point. 
       FIG. 2  shows the impact situation by means of a schematic cross section of the window cross member  4  and its surroundings in the finish-assembled vehicle. In this cross section, the windshield  8  is also shown whose lower edge is fastened to the support section  6  of the window cross member  4  via an adhesive layer  9 . The support section  6  extends almost over the entire width of the windshield  8  in close contact with the latter; it merely ends shortly before reaching the A-pillars  2  and merges into compressible sections  10  angled off into the vehicle interior at its ends facing the A-pillars  2 . Distal ends  11  of the compressible sections  10  are anchored to the A-pillars  2  spaced from the windshield  8 . 
     The support section  6  forms a front edge of the window cross member  4  unitarily cut to size and formed from sheet metal; the rear edge  5  is located at a lower level than the support section  6  and is fastened to the upper edge of an intermediate wall  12 , which separates engine compartment and passenger cell. A central region  13  of the window cross member  4 , which connects the support section  6  and the rear edge  5  comprises a zig-zag or wavy cross section, which can yield in the case of a head impact, in that it is compressed and the support section  6  moves towards the upper edge of the intermediate wall  12 . When such an impact occurs in a region of the windshield  8  that is far distant from both A-pillars  2 , the deflection of the support section  6  immediately at the impact point of the head or impactor  7  is greatest and from there gradually decreases towards both sides. The kinetic energy of the impactor  7  is therefore consumed by the central region  13  through deformation directly at the impact point and on both sides of said region. 
     If the window cross member  4  were only supported on the intermediate wall  12  and not connected to the A-pillars, only a central region  13  deformable on one side of the impact point would be available in the case of an impact on the windshield  8  in the vicinity of one of the A-pillars  2 . As a consequence, the resilience of the window  8  near the A-pillars  2  would be substantially higher than in a central region of the windshield  8  between the A-pillars  2 , and there would be the risk of a striking-through of the impactor  7  as far as into regions of the body that can be deformed only to a minor degree, such as for example the intermediate wall  12 . Sliding-off of the impactor  7  in lateral direction and striking against the A-pillar  2  would also be possible. In both cases, no satisfactory pedestrian protection is possible. However, if the ends of the support section  10  were directly fastened to the A-pillars  2 , these ends could yield only together with the A-pillars  2  in the event of an impact in their vicinity. However, these must not yield too easily so that they can firmly support the roof of the vehicle so that the vehicle occupants are effectively protected also during a roll-over. In this case, the resilience of the window  8  in the vicinity of the A-pillars  2  is less than between them. The compressible section  10  by contrast allows substantially determining arbitrarily the resilience of the support section  6  even in the immediate vicinity of the A-pillars  2 . For this reason it is possible through a suitable choice of parameters such as wall thickness, length and cross section of the compressible section  10  to adjust a resilience of the window  8  that substantially stays the same over the entire width of the windshield  8 . 
       FIG. 3  shows a first exemplary embodiment of the compressible section  10  in a schematic cross section in a plane that is perpendicular to the longitudinal direction of the A-pillar  2  (shown only partially). The A-pillar  2  is a hollow profile joined together from a plurality of panels, in this case an outer panel  14  and an inner panel  15 . Edges of the panels  14 , welded together form a web  16 , which stands away from a flank of the A-pillar  2  facing the edge  17  of the windshield  8 . The edge  17  extends parallel to the web  16  spaced from the latter. The spacing is bridged by the compressible section  10  substantially extending in the direction of the surface normal of the windshield  8 . On the distal end of the compressible section  10  facing away from the support section  6  a tongue  18  is angled off in an orientation that is substantially parallel to the support section  6  in order to act on the web  16 . The tongue  18  can be fastened to the web  16  for example through spot welding, but a simple positive connection of the window cross member  4  between the windshield  8  and the A-pillars  2  can also suffice in order to retain the tongues  18  on the webs  16  on both ends of the window cross member  4 . In the exemplary embodiments, the tongues  18  serves as engagement points (not separately numbered) of the window cross member  4  to engage the A-pillars  2 . 
       FIG. 4  shows a section that is analogous to  FIG. 3  according to a second configuration. The orientation of the compressible section  10  substantially in the direction of the surface normal of the windshield  8  designated  23  here is the same as in the case of  FIG. 3 , however the compressible section  10  in this case is divided through a buckling zone  20  into a section  21  adjacent to the windshield  8  and a section  22  adjacent to the web  16 , the orientation of which individually deviates from the surface normal  23  in each case. In the case considered here, the deviation is such that the buckling zone  20  is offset towards the vehicle center against the surface normal  23  running through proximal and distal end  19  and  11  respectively of the compressible section  10 . The presence of the buckling zone  20  ensures that the compressible section  10  starts to yield with an accurately and reproducibly adjusted load. Through the offset of the buckling zone  20  towards the vehicle center it is ensured that the compressible section  10 , when it is compressed under the load of an impact, yields towards the vehicle center and the compression of the section  10  can thus not be obstructed through a striking against the A-pillars  2 . In that the section  21  close to the window is made slightly narrower than the section  22  close to the web it can be ensured that forces parallel to the surface of the web  16 , which during a compression act on the tongue  18 , are directed away from the vehicle center. Thus, sliding-away of the tongue  18  from the web  16  is securely avoided even when both are not immovable fastened to each other. 
     With the exemplary configuration of  FIG. 5 , the orientation of the compressible section  10  significantly deviates from the surface normal. The proximal end  19  is clearly offset towards the vehicle center relative to the distal end  11 . This compressible section  10  is initially subjected to thrust in the event of an impact. It exerts a strong supporting force at the latest when the tip of the tongue  18  at the foot of the web  18  strikes against the outer panel  14 . At the same time, bending moments in opposite direction occur at the proximal end  19  and in a middle region of the support section  10 , which after overcoming an initial resistance result in that the support section  10  buckles towards the vehicle center in a similar manner as the one shown in  FIG. 4 . 
     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the present disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the present disclosure as set forth in the appended claims and their legal equivalents.