Abstract:
A front structure for a motor vehicle has a stiffening element situated in a crossbeam. The stiffening element is enclosed by a bulkhead plate and a front wall and ensures a high level of rigidity of the crossbeam. The front structure additionally has a low weight in this case.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to German Patent Application No. 102008049762.2, filed Sep. 30, 2008, which is incorporated herein by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    The invention relates to a front structure for a motor vehicle having a front wall which delimits a passenger compartment in the travel direction, having a front frame situated in front of the front wall, and having a crossbeam. 
       BACKGROUND 
       [0003]    A crossbeam for such a front structure is known, for example, from DE 20 2004 011 120 U1. The crossbeam has two half shells, between which an insert part is fastened and situated between two A columns of the motor vehicle. The half shells and the insert part are manufactured from sheet metal and generate a provided stability of the crossbeam. A high stability of the area of the crossbeam is necessary in order to protect the occupants of the motor vehicle in the event of a crash. A front structure equipped with the known crossbeam has the disadvantage that it has a very high weight. In addition, the crossbeam is composed of a plurality of sheet-metal plates, which are complex to install. 
         [0004]    The invention is based on the problem of designing a front structure of the type cited at the beginning so that it has a particularly low weight and ensures a high rigidity of the motor vehicle in the area of the front wall. 
       SUMMARY 
       [0005]    This problem is solved according to the invention in that the crossbeam has a stiffening element made of plastic. 
         [0006]    Through this design, the crossbeam which is provided in any case is stiffened by the stiffening element. This stiffening ensures a high rigidity of the motor vehicle in the area of the front wall and thus allows a high level of crash safety of the motor vehicle equipped with the front structure according to the invention. Because the stiffening element is manufactured from plastic, the front structure thus has a particularly low weight. The stiffening element can be manufactured from plastic in the injection-molding method or from a fiber-reinforced resin. 
         [0007]    The crossbeam which stiffens the front wall typically has a bulkhead plate fastened to the front wall. According to another advantageous embodiment of the invention, the stiffening element is capable of stiffening such a crossbeam easily if the stiffening element is situated between a bulkhead plate fastened to the front wall and the front wall and if the front wall and the bulkhead plate enclose the stiffening element. The stiffening element is mounted positively between the front wall and the bulkhead plate by the positive enclosure. A screw connection of the stiffening element to adjoining components is not necessary thanks to the invention. 
         [0008]    According to another advantageous embodiment of the invention, the crossbeam having the stiffening element has a high stability if the stiffening element is situated below a reinforcement plate which connects the bulkhead plate to the front wall. 
         [0009]    It contributes to further increasing the stability of the crossbeam having the stiffening element, according to another advantageous embodiment of the invention, if the stiffening element is designed as linear between two longitudinal girders of the front frame. 
         [0010]    It contributes to further increasing the stability of the front structure according to an embodiment of the invention if the stiffening element connects two plates of wheel wells which are fastened to the front wall. 
         [0011]    Twisting of the wheel wells in the event of a crash of the motor vehicle may be avoided easily according to another advantageous embodiment of the invention if the stiffening element is guided from the lower half of the front wall up to above the wheel wells in the upper half of the front wall. 
         [0012]    The crossbeam having the stiffening element is designed particularly compactly and has a low weight according to another advantageous embodiment of the invention if the stiffening element is designed as tapering in cross-section toward its lower end. Through this design, the stiffening element has a higher material strength in an area distant from a floor plate of the motor vehicle than close to the floor plate, which is typically very stiff in any case. The front wall is thus deliberately stiffened at the point at which particularly high forces act in the event of a crash. 
         [0013]    The crossbeam having the stiffening element is particularly rigid according to another advantageous embodiment of the invention if the stiffening element has reinforcement ribs pointing in the intended travel direction of the motor vehicle. The reinforcement ribs are preferably situated in a lattice or honeycomb. 
         [0014]    The manufacturing of different stiffening elements for left-hand and right-hand drive vehicles may be avoided easily according to another advantageous embodiment of the invention if the stiffening element has two steering passages. 
         [0015]    The crossbeam having the stiffening element is prepared for assuming manifold functions if the stiffening element has a channel for a water drain and/or an opening for a wiring passage. The integration of the channel for the water drain in the stiffening element manufactured from plastic also has the advantage that the function of a water chamber can also be integrated easily in the crossbeam having the stiffening element. Penetrating water is thus kept away from components made of sheet metal by the plastic of the stiffening element. The stiffening element thus contributes to protecting the crossbeam from corrosion. 
         [0016]    Annoying rattling noises from the stiffening element may be avoided easily according to another advantageous embodiment of the invention if the stiffening element has at least one trough open toward an adjoining component and a seal is situated in the trough. The seal prevents or damps relative movements of the stiffening element relative to the front wall and the bulkhead wall. Furthermore, in this way the steering passages, the wiring passage, and/or the water drain may be sealed easily. The seal preferably comprises a foaming material which cures in a drying furnace of a painting shop. 
         [0017]    The installation and orientation of the stiffening element to adjoining components is particularly simple according to another advantageous embodiment of the invention if the stiffening element is manufactured integrally with a centering element which penetrates into the front wall or the bulkhead plate. 
         [0018]    It contributes to further simplifying the mounting of the stiffening element if the centering element has a detent hook which engages in the front wall or the bulkhead plate. 
         [0019]    According to another advantageous embodiment of the invention, the stiffening element contributes to simplifying the installation of components to be situated in the motor vehicle if the centering element mounts insulation or further components to be situated in a motor vehicle using an end part which penetrates the front wall. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and: 
           [0021]      FIG. 1  shows a front structure according to the invention before installation; 
           [0022]      FIG. 2  shows an enlarged sectional illustration through the front structure from  FIG. 1  along line II-II after installation; 
           [0023]      FIG. 3  shows a further embodiment of the front structure according to the invention; 
           [0024]      FIG. 4  shows an enlarged sectional illustration through the front structure from  FIG. 3  along line IV-IV after installation; 
           [0025]      FIG. 5  shows an enlarged sectional illustration through the front structure from  FIG. 3  along line V-V after installation; 
           [0026]      FIG. 6  shows an enlarged sectional illustration through a subarea of a front wall; and 
           [0027]      FIG. 7  shows an enlarged subarea of a stiffening element of the front structure according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]      FIG. 1  shows a front structure for a motor vehicle having a front wall  1 , which delimits a passenger compartment in the travel direction, before the connection to a front frame  2 . The front wall  1  is connected to plates  3  of two wheel wells, between which a stiffening element  4  made of plastic is situated. The front frame  2  has two laterally situated longitudinal girders  5 , which point in the travel direction, and a bulkhead plate  6 , which connects the longitudinal girders  5  to one another. The bulkhead plate  6 , the front wall  1 , and the stiffening element  4  form a crossbeam  7 , which is shown in cross-section in  FIG. 2 , after installation. The stiffening element  4  has a plurality of stiffening ribs  8  situated in rhomboids and lattices in the travel direction. The stiffening element  4  is situated on the lower half of the front wall  1 . 
         [0029]      FIG. 2  shows the crossbeam  7  in a sectional illustration along line II-II after the connection of the bulkhead plate  6  to the front wall  1 . The connection of the bulkhead plate  6  to the front wall  1  can be performed in the welding method. It can be seen in  FIG. 2  that the stiffening element  4  made of plastic is situated completely inside the crossbeam  7  and is enclosed by the bulkhead plate  6  and the front wall  1 . The crossbeam  7  is designed as tapering toward a floor  9  of the motor vehicle. Furthermore, the reinforcement ribs  8  are recognizable in  FIG. 2 . 
         [0030]      FIG. 3  shows a further embodiment of the front structure, which differs from that from  FIG. 1  only in that a stiffening element  10  is led up to above the plates  3  of the wheel wells. The stiffening element  10  is thus situated between the longitudinal girders  5  on the lower half of the front wall  1  and its end is lead into the upper half of the front wall  1 . A bulkhead plate  11  of a front frame  12  is led upward like the stiffening element  10 . The stiffening element  10  is covered on top by a reinforcement plate  13  fastened to the front wall  1 . The bulkhead plate  11  and the stiffening element  10  have two steering passages  14  for right-hand and left-hand drive vehicles, a wiring passage  15 , and a water drain  16 . 
         [0031]      FIG. 4  shows a crossbeam  17  generated after the connection of the front frame  12  to the front wall  1  in a sectional illustration along line IV-IV from  FIG. 3 . It can be recognized that the reinforcement plate  13  is also fastened to the bulkhead plate  11 . The stiffening element  10  has reinforcement ribs  18  and is enclosed by the front wall  1 , the bulkhead plate  11 , and the reinforcement plate  13 . 
         [0032]      FIG. 5  shows, in a sectional illustration along line V-V from  FIG. 3  in the area of the water drain  16 , that the stiffening element  10  has a channel  19 , using which water is guided inside the crossbeam  17 . The channel  19  is sealed via a seal  21  situated in a trough  20 . 
         [0033]      FIG. 6  shows a sectional illustration through a subarea of the stiffening element  10  fastened on the front wall  1 . The stiffening element  10  has a centering element  23 , which penetrates a hole  22  in the front wall  1 , having a detent hook  24 . The detent hook  24  allows fixing of the stiffening element  10  on the front wall  1 . Furthermore, a free end part  25  of the centering element  23  protrudes beyond the front wall  1 . For example, insulation  26  is fastened using a retaining clip  27  on the end part of the centering element  23  penetrating the front wall  1 . 
         [0034]      FIG. 7  shows a perspective view of a subarea of the stiffening element  10 . It can be seen that the wiring passage  15 , the steering passage  14 , and the channel  19  of the water drain  16  each have an open peripheral trough  20  for receiving the seal  21 . 
         [0035]    While at least one exemplary embodiment has been presented in the foregoing summary and 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 in any way. Rather, the foregoing summary and 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 as set forth in the appended claims and their legal equivalents.