Abstract:
Three structural components meet at a structural node for a motor vehicle bodywork. The structural components are fitted together from at least one outer part and one an inner part in each case. A reinforcement part is arranged in a hollow space formed in one of the structural components and is fixed to the inner part of at least a first structural part and the outer part of at least a second structural part.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to German Patent Application No. DE102016001241.2, filed Feb. 4, 2016, which is incorporated herein by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    The present disclosure pertains to the structure of a structural node, at which a plurality of supporting structural components meet in a motor vehicle bodywork. 
       BACKGROUND 
       [0003]    The structure of a node is of great importance for the stability, in particular the torsional rigidity, of the bodywork as a whole. The more stable the structural nodes themselves, the lighter are the structural components that can be used to achieve a required stability, and weight savings thus achieved contribute towards a reduction in fuel consumption. 
         [0004]    A structural node for a motor vehicle bodywork is known from DE 10 2009 051 036, in which a reinforcement part cast from light metal includes three grooves, each of which accommodates one of three structural components. The structural components are fixed to the reinforcement part by rivets distributed at the bottom and side walls of the grooves. In order to increase the buckling strength of the reinforcement part, ribs extending transversely through the grooves can be provided. The latter occupy space which, if not present, could be occupied by the structural components themselves. As a consequence, the structural components have to be fixed to the reinforcement part with a long lever arm, which promotes a deformation of the reinforcement part. 
       SUMMARY 
       [0005]    According to the present disclosure, a structural node is provided with a high loading capacity along with low weight. In an embodiment of the present disclosure, a structural node is formed for a motor vehicle bodywork at which three structural components meet. The structural components are fitted together from an outer part and an inner part in each case. A reinforcement part is arranged in a hollow space formed by the structural components and is fixed to the inner part of at least a first structural part and the outer part of at least a second structural part. 
         [0006]    Such a reinforcement part can, as a result of torque acting on the structural components, be subjected not only to bending stress, but also to axial and in particular tensile stress. Even with a thinner wall thickness of the reinforcement part, much more effective stiffening can be achieved than with a reinforcement part essentially subjected to bending stress. 
         [0007]    The reinforcement part can be fixed by welding to the inner part of the first structural part. A connection with high loading capacity can thus be created even with a small wall thickness, since welding, in contrast with a riveted joint, is not necessarily accompanied by a structural weakening of the parts fixed to one another. 
         [0008]    The reinforcement part can be fixed by adhesion to the outer part of the second structural part. Weld traces on the outer part can thus be avoided, which is particularly attractive when the outer part remains visible on the finished vehicle. Selecting an adhesive joint can however also be expedient if the connection region between the reinforcement part and the outer part is difficult to reach for welding after the fitting-together of the parts. 
         [0009]    A decisive contribution can also be made to the strength of the structural node by the fact that the structural parts are fixed to one another not only via the reinforcement part, but also directly. For this purpose, the outer part of one of the structural parts can include an edge which is fixed to the outer part of at least another one of the structural parts, or the inner part of one of the structural parts can include an edge which is fixed to the inner part of at least another one of the structural parts. 
         [0010]    In order to optimize the tensile loading capacity of the reinforcement part, the reinforcement element can include, between a first flange fixed to the first structural part and a second flange fixed to the second structural part, a central portion extending rectilinearly between the flanges. 
         [0011]    A projection of the central portion lying adjacent to the inner part is useful for unequivocally establishing the installation position of the reinforcement part in the structural node even when the inner and outer parts of the structural components are not yet all connected to one another, so that after the fitting-together of all the parts the second flange lies against the outer part of the second structural component in such a way that both can be fixed securely to one another. 
         [0012]    For the further stiffening of the structure, the projection can for its part be fixed to the inner part. The projection can be formed on the reinforcement part by an embossing or deep-drawing operation. The entire reinforcement part is preferably formed from one piece of flat material, in particular a steel plate. 
         [0013]    For the sake of easier production, the reinforcement part can be fixed in the case of each structural part either to its outer part or its inner part. The reinforcement part can also be fixed to the outer part of the third structural part. 
         [0014]    At least one roof frame and a pillar supporting the roof frame are preferably located beneath the structural components. The reinforcement element is particularly effective if it is positioned at the corners, in particular the rear corners, of a vehicle roof, i.e. if a longitudinally running roof frame and a transversely running, in particular rear roof frame are beneath the structural components. With such a vehicle roof, the transversely running roof frame is preferably the first structural part. The connection portions of reinforcement parts can thus be arranged at both ends of the transversely running roof frame essentially along one and the same line, so that the roof frame virtually cannot be deformed by tensile loading in the vehicle transverse direction. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The present embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements. 
           [0016]      FIG. 1  shows a diagram of the passenger compartment of a motor vehicle 
           [0017]      FIG. 2  shows a motor vehicle bodywork in an early construction stage; 
           [0018]      FIG. 3  shows a perspective view of a reinforcement part; 
           [0019]      FIG. 4  shows the reinforcement part, fitted to the side wall on the inside of the motor vehicle bodywork from  FIG. 2 ; 
           [0020]      FIG. 5  shows an enlarged detail from  FIG. 4 ; 
           [0021]      FIG. 6  shows the motor vehicle bodywork in a mid-point construction stage; 
           [0022]      FIG. 7  shows an enlarged detail from  FIG. 6 ; 
           [0023]      FIG. 8  shows the motor vehicle bodywork in a late construction stage, with a closed roof; 
           [0024]      FIG. 9  shows a detail from  FIG. 8  in cross-section; 
           [0025]      FIG. 10  shows a cross-section along the plane X-X of  FIG. 8 ; and 
           [0026]      FIG. 11  shows a representation, analogous to  FIG. 8 , of a motor vehicle bodywork with an open roof. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description. 
         [0028]      FIG. 1  shows in very diagrammatic form a passenger compartment of a motor vehicle. Elongated structural components, here A-, B- and C-pillars  1 ,  2 ,  3  as well as a front, a rear and side roof frames  4 ,  5 ,  6  are connected to one another rigidly at structural nodes  7  and border areas which are filled by window panes, doors, a boot lid or suchlike and the contribution whereof to the torsional rigidity of the passenger compartment is rather small compared to structural components  1 - 6 . The present disclosure is explained in the following on the basis of rear structural nodes  7 , at which C-pillars  3  meet side roof frames  6  and rear roof frame  5 ; it can also be applied to other structural nodes  7 . 
         [0029]      FIG. 2  shows an unfinished motor vehicle bodywork in an early construction stage. The side walls on the inside  10  can be seen, which each form inner parts  11 ,  12 ,  13  of still incomplete A, B and C-pillars  1 ,  2 ,  3 , as well as inner parts  14 ,  15  and  16  of front, rear and side roof frames  4 ,  5 ,  6 . The bodywork is in the fastback or estate car design; the rear roof-frame inner part  15  and inner parts  13  of the C-pillars border a boot opening  17  at a steeply sloping vehicle rear. C-pillar inner part  13 , side roof-frame inner part  16  and rear roof-frame inner part  15  each border a channel open towards the bodywork exterior. The channels meet at upper rear corners  18  of the bodywork, and mutually overlapping flanges  19 ,  20  at the ends of inner parts  13 ,  15 ,  16  are welded together. Flanges  21 ,  22 ,  23  running along the longitudinal edges of inner parts  13 ,  15 ,  16  are provided in order to be welded at a subsequent assembly stage with outer parts of the C-pillar, of the rear roof frame and of the side roof frame. 
         [0030]      FIG. 3  shows in a perspective view a left-hand reinforcement part  24 , which is provided to be assembled approximately in the orientation in which it is shown in  FIG. 3 , at left-hand corner  18 . A reinforcement part shown as a mirror-image to the latter is provided for right-hand corner  18 . Reinforcement part  24  is formed in one piece from a sheet metal blank like inner parts  4 ,  5 ,  7  and using the same techniques. The cross-section of reinforcement part  24  for the most part follows that of rear roof-frame inner part  15 . An essentially flat central portion  25  and flanks  26 ,  27  adjacent thereto above and below replicate the cross-section of inner part  15  and form at their right-hand edges a flange  28  bounded in the figure by a broken line, the flange being provided to be inserted into the channel of inner part  15  and welded therein. 
         [0031]    A wedge-shaped projection  29  projecting towards the side facing away from the observer is embossed in central portion  25 . Projection  29  splays reinforcement part  24  and inner part  15  apart from one another, so that central portion  25  at its left-hand edge becomes increasingly distant from inner part  15 . 
         [0032]    A flange  30  is bent off at an angle at the left-hand edge of central portion  25 . Further bent-off flanges  31 ,  32  extend along the edges of flanks  26 ,  27 . 
         [0033]      FIG. 4  shows an assembly  33 , which is provided for mounting on the left-hand side wall on the inside  10  of the unfinished bodywork shown in  FIG. 1 . Assembly  33  includes wall elements  34 ,  35 ,  36 , which are positioned for the completion of A-, B- and C-pillar  1 ,  2 ,  3  on inner parts  11 ,  12  and  13 , a wall element  37  for supplementing side roof frame  6 , a sill strip  38  and, at a rear upper corner of the assembly at which wall elements  36  and  37  meet, reinforcement  24 . 
         [0034]      FIG. 5  shows an enlarged view of the rear upper corner of assembly  33 . A left-hand edge region  39  of central portion  25  and flank  36  project laterally beyond wall element  37 , flank  27  forming in a similar manner a bulkhead  40  projecting backwards beyond wall element  36 . 
         [0035]    In the view of  FIG. 6 , assembly  33  is mounted on the bodywork, so that A-, B- and C-pillar  1 ,  2 ,  3 , are complete; moreover, a cover  41  is fitted over wall element  37 , which cover, together with wall element  37  covered by it and inner part  16  lying behind, forms side roof frame  6 . Cover  41  extends at its rear end down to flange  32  on lower flank  27  of reinforcement part  24  and is fixed to the latter by spot welds  43 , the locations whereof are denoted in  FIG. 5  by circles distributed along flange  32 . Flange  30  is inaccessible after the positioning of cover  41 , cover  41  being fixed to it by an adhesive bead  44  (see  FIG. 5 ). 
         [0036]    A portion of reinforcement part  24  with flange  28  projects beneath cover  41 . As can be seen in the enlarged detail view of  FIG. 7 , central portion  25  essentially extends along inner part  15  of the rear roof frame and is fixed to the latter by spot welds  43 , which are distributed along flange  28  and on projection  29 . 
         [0037]    In the next construction stage shown in  FIG. 8 , a roof panel  45  is inserted between the two side roof frames  6 , the roof panel covering flanges  28  of reinforcement parts  24 .  FIG. 9  shows a cross-section through the rear edge of roof panel  45  and rear roof-frame inner part  15  along the cross-sectional plane depicted in  FIG. 6  with IX-IX. The cross-sectional plane runs through flange  28  of one of reinforcement parts  24  and shows a plurality of spot welds  43 , by which the reinforcement part and inner part  15  are fixed to one another. The rear edge of roof panel  45  forms here an outer part  46  of rear roof frame  5 , which is welded along one of its two flanges  22  to a hollow profile. An edge of outer part  46  projecting backwards beyond flange  22  is bent up in order to form a drainage channel  47  for rainwater above the boot opening. 
         [0038]      FIG. 10  shows a cross-section in a vehicle transverse direction through left-hand reinforcement part  24  and its surroundings along the plane denoted in  FIG. 9  with X-X. Main part  25  and flange  28  of the two reinforcement parts  24  and the portion of rear roof-frame inner part  15  extending between reinforcement parts  24  lie on one and the same line. The lateral end of rear roof-frame inner part  15 , on the left of flange  28  in  FIG. 10 , is bent down and welded to flange  19  of C-pillar inner part  13 . Projection  29  is supported on this end. At the end of reinforcement part  24  lying opposite flange  28 , flange  30  is bent down at an angle and glued to cover  41  of side roof frame  7 . Reinforcement part  24  thus forms on the one hand a cross-bracing between inner parts  15 ,  13  and an outer part  41  of respective different structural components  3 ,  5 ,  6  meeting at corner  18 , by which corner  18  is stiffened, whilst on the other hand a transverse connection between the two side walls  10  of the bodywork that is virtually non-deformable by tensile loading is created as a result of the connection of reinforcement parts  24  on both sides of the bodywork via rear inner part  15 . 
         [0039]      FIG. 11  shows an alternative embodiment of the vehicle bodywork in a representation similar to  FIG. 8 . Instead of a roof panel extending over the entire length of the roof, an outer part  46  is affixed here to inner part  7 , the dimensions of which outer part are roughly the same as those of inner part  15  in the vehicle longitudinal direction. A roof module can be inserted into opening  48  of the roof remaining open, the roof module being able to be constituted differently according to the customer&#39;s wishes, e.g. with a glazing, a sliding roof or suchlike. Since the roof module here, in contrast with the closed roof of  FIG. 8 , can make only a relatively small contribution to the torsional rigidity of the passenger compartment, the contribution of reinforcement part  24  is particularly important here. 
         [0040]    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 invention 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 invention as set forth in the appended claims and their legal equivalents.