Abstract:
In a motor vehicle includes, but is not limited to a chassis module, a front module, and a body, front module, body, and chassis module, At least one first and one second set of cooperating fastenings are provided for fastening the front module on the chassis module and/or the body. The cooperating fastenings of the first set define an axis about which the front module can be pivoted relative to the chassis module into a stop position in which it is held by the fastening means of the second set.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to German Patent Application No. 102010018482.9, filed Apr. 28, 2010, which is incorporated herein by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    The technical field relates to a motor vehicle composed of a plurality of modules, including at least one chassis module, a front module, and a body, and a method for the manufacture thereof. 
       BACKGROUND 
       [0003]    An assembly station for carrying out the assembly method is known from DE 10 2007 017 167 A1. This prior-published application comprises an assembly plate on which the front module and the chassis module are placed as well as transporting tools for transporting toward and exact placement of the components to be assembled. After lowering the body onto the chassis module, the front module is pivoted toward the chassis module and the body about an axis defined by a supporting column of the assembly plate and is fastened. This method certainly enables a rapid and simple assembly of the motor vehicle but is to some extent complex in practical implementation since assembly plates adapted in each case to a type of vehicle to be assembled are required in order to place front and chassis module with respect to one another so that through pivoting, the front module enters precisely into the position in which it can be fastened on the body and/or chassis module. In addition, the large number of working steps which need to be executed while the vehicle is located on the assembly plate (lowering the body and connecting to the chassis module, pivoting the front module and fastening the front module), necessitates a long dwell time of the vehicle on the assembly plate. In order to prevent this phase from forming a bottleneck during series production, a large number of assembly stations need to be provided which again increases the costs. 
         [0004]    Therefore, it is at least one object to provide a motor vehicle, which can be mounted in the manner known from DE 10 2007 017 167 A1 by pivoting a front module toward chassis module and body, but for the mounting whereof a simplified assembly plate is sufficient and in which the dwell time on the assembly plate can be shortened, or to further develop the assembly method known from DE 10 2007 017 167 A1 such that the implementation costs are reduced. 
       SUMMARY 
       [0005]    The at least one object is achieved on the one hand by a method for assembling a motor vehicle comprising the steps fitting into one another first fastening means of a chassis module and a front module of the motor vehicle in a preliminary position, bringing together the modules with a body as far as a stop position of the chassis module on the body, then pivoting the front module about an axis defined by the first fastening means, which have been fitted into one another, into a final position, and fastening the front module on the chassis module or the body by means of second fastening means. 
         [0006]    The object is achieved on the other hand whereby in a motor vehicle comprising a chassis module, a front module, and a body wherein front module, body, and chassis module comprise at least one first and one second set of cooperating fastening means for fastening the front module on the chassis module and/or the body, the cooperating fastening means of the first set define an axis about which the front module can be pivoted relative to the chassis module into a stop position in which it is held by the fastening means of the second set. 
         [0007]    Since the first set of fastening means defines the pivot axis of the front module, the supporting column of the assembly plate conventionally provided for this purpose is superfluous. The assembly plate is therefore on the one hand simpler and cheaper and on the other hand, it is also less specific to vehicle type so that the same assembly station can be used for fabricating different types of vehicle without retrofitting or with relatively little retrofitting effort. The fastening means of the first set can expediently comprise at least one fork and a hinge bolt embraced by the fork. The fork can be part of the front module; then the hinge bolt is part of the body or, preferably, of the chassis module. Conversely, however, the hinge bolt can be part of the front module; then the fork pertains to the body or to the chassis module. 
         [0008]    A lead-in chamfer formed on the fork facilitates the placement of the hinge bolt in the fork. The fork is expediently oriented so that it and the hinge bolt can be fitted into one another by a lowering movement of the front module. That is, if the fork is part of the front module, its opening points downward whereas in the case of a fork pertaining to the chassis module or to the body, the opening is directed upward. 
         [0009]    The chassis module can comprise a supporting structure such as an engine frame, to which a fastening means of the first set, that is in particular the form or the hinge bolt, is firmly connected. If at least one part of the supporting structure is fabricated by a molding method such as die casting, the fastening means of the first set is expediently molded in one part with this part. 
         [0010]    A highly stiff piece of the supporting structure which can be implemented using simple molding tools can comprise a base plate and reinforcing ribs projecting from the base plate in a demolding direction. In such a case, the fastening means of the first set is preferably a hinge bolt which is held by walls aligned in the demolding direction. To save weight, the supporting structure can be composed of extruded supports and at least one connecting piece that connect at least two of the supports. This connecting piece can expediently be the aforementioned part fabricated by a molding method. 
         [0011]    The second set of cooperating fastening means preferably comprises an elastically deflectable locking hook and an edge on which the locking hook acts in the stop position. Thus, after fitting the fastening means of the first set into one another, a simple pivoting of the front module into the stop position is sufficient to at least temporarily fasten the front module. An assembly station at which this fabrication step has taken place can now be made free in order to assemble front module, chassis module, and body of the next vehicle there, while further assembly steps such as a definitive fastening of the front module of the vehicle just assembled can be carried out at another location. If the dwell time of the individual vehicle at the assembly station is shortened in this way, the number of assembly stations required for a given production speed is reduced, which allows significant cost savings during manufacture. 
         [0012]    A fastening means of the second set is preferably disposed on the body, vertically spaced apart from the first set of fastening means connecting the front module, preferably to the chassis module. If a longitudinal member of the body is terminated at its front end by a flange in a manner known per se, a fastening means of the second set can expediently be disposed on the flange. 
         [0013]    The front module preferably comprises at least one radiator assembly and a radiator frame extending around the radiator assembly. To save weight, the radiator frame can expediently be formed at least in part, in hybrid technology, by a plastic-sheathed sheet. Furthermore, a bumper cross member can be part of the front module. 
         [0014]    In order to make the assembly of body and front module, in particular a vertical movement of body and front module toward one another, simple and reliable, the radiator frame can have a width which decreases from bottom to top in order to facilitate the insertion thereof into the body, in particular between the longitudinal members thereof. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and: 
           [0016]      FIG. 1  shows a first stage of the assembly of a vehicle according to an embodiment; 
           [0017]      FIG. 2  shows a second assembly stage; 
           [0018]      FIG. 3  shows a third assembly stage; 
           [0019]      FIG. 4  shows a perspective view of an engine frame forming a part of the front module of the vehicle; 
           [0020]      FIG. 5  shows an enlarged detail of the engine frame from  FIG. 4 ; 
           [0021]      FIG. 6  shows a perspective view of the front module of the vehicle; 
           [0022]      FIG. 7  shows an enlarged detail of the front module from  FIG. 6 ; 
           [0023]      FIG. 8  shows the engine frame as well as parts of the front module in the assembled state; 
           [0024]      FIG. 9  shows an enlarged detail of the front module from  FIG. 8 ; 
           [0025]      FIG. 10  shows the vehicle components shown in  FIG. 8 , joined to longitudinal members of the body; 
           [0026]      FIG. 11  shows an enlarged detail from  FIG. 10 ; 
           [0027]      FIG. 12  shows a schematic section in the vehicle longitudinal direction through the structure of  FIG. 10 ; 
           [0028]      FIG. 13  shows an enlarged detail from  FIG. 12 ; 
           [0029]      FIG. 14  shows a perspective view of a front end structure forming a part of the body according to a second embodiment of the invention; 
           [0030]      FIG. 15  shows an enlarged detail of the front end structure from  FIG. 14 ; 
           [0031]      FIG. 16  shows a radiator frame according to the second embodiment; and 
           [0032]      FIG. 17  shows a front module, an engine frame as well as parts of the front end structure in the assembly step of  FIG. 2  according to the second embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    The following detailed description is merely exemplary in nature and is not intended to limit application and uses. Furthermore, there is no intention to be bound by any theory presented in the preceding background or summary or the following detailed description. 
         [0034]      FIG. 1  shows in a side view a chassis module  2  of a motor vehicle placed on a liftable assembly plate  1 . The chassis module  2  comprises a chassis comprising front and rear axle  4 ,  5  each having two suspension struts  6 , an engine frame  14 , an engine  7  anchored in the engine frame  14 , a tank  8 , as well as other components omitted in the schematic diagram. At two front corners of the engine frame  14 , pairs of supports project in each case, said supports holding between them respectively one horizontal hinge bolt  13 . 
         [0035]    A front module  3  to be mounted on the chassis module  2  is shown in  FIG. 1  above the hinge bolt  13 . A bumper support  9 , a radiator assembly  10 , and a radiator frame  11  are connected in the front module  3 . Holders  12  for headlamps can be integrated in the radiator frame  11 . An upper strut of the radiator frame  11  can additionally serve as a holder of a hood lock for a hood (not yet mounted and therefore not shown in the figure) of the vehicle. Two downwardly open forks  15  project from the radiator frame  11  on opposite sides. In order to facilitate a snapping of the forks  15  onto the hinge bolts  13 , when the front module  3  is lowered from the position shown in  FIG. 1 , the forks  15  are each provided with lead-in chamfers  16  at the free ends of their tines. 
         [0036]      FIG. 2  shows a later stage of the assembly in which the front module  3  is lowered onto the chassis module  2  and the forks  15  are locked embracingly onto the hinge bolts  13 . In this stage, the front module  3  can be pivoted relative to the chassis module  2  about a horizontal axis which runs perpendicular to the plane of the drawing through the two hinge bolts  13 . In the orientation shown in  FIG. 2  the front module  3  can be held with the aid of a supporting column  17  emanating from the assembly plate  1 , against which the front side of the bumper support  9  or another suitable loadable surface of the front module  3  abuts. Alternatively it would be feasible to temporarily hold the front module  3  in the orientation shown with the aid of the same transport apparatus that has been used to convey the front module  3  toward the assembly plate  1  and for lowering onto the chassis module  2 . 
         [0037]    In the next step, a vehicle body  18 , as indicated by an arrow, is brought into the position shown in  FIG. 2  above the assembly plate  1 . The body  18  has a rigid frame with two longitudinal members  19 , whose front ends projects into an engine compartment  20  on the front side of the body  18 . The body  18  is placed above the assembly plate  1  so that by raising the assembly plate  1 , the engine  7  moves between the two longitudinal members  19  and the suspension struts  6  dip into corresponding receptacles of the body  18 , which are not shown. This stage is shown in  FIG. 3 . 
         [0038]    In the next assembly step the front module  3  is pivoted about the axis defined by the hinge bolts  13  in the clockwise direction onto the body  18  until two flanges  21  on the rear side of the front module  3  abut against flanges  22  which terminate the longitudinal members  19  toward the front. In this position, parts of the radiator frame  11 , in particular the headlamp holders  12 , are located vertically above the longitudinal members  19 , which is the reason why the body  18  must be placed on the chassis module  2  before pivoting the front module  3 . 
         [0039]    Since the freedom of movement of the front module  3  in relation to the chassis module  2  is already restricted to a single degree of rotational freedom due to the engagement of the forks  15  and hinge bolts  13 , a few fastening means attached expediently to the two flanges  21 ,  22  are sufficient to fasten the modules  2 ,  3  permanently onto one another. 
         [0040]      FIG. 4  shows in a perspective view the engine frame  14  obliquely from the front and from above. The engine frame (assembly plate  1 ) could be a one-piece casting, for example, die-cast aluminum.  FIG. 4  shows a preferred further development, as a result of which the engine frame  14  is composed of a plurality of components, i.e., two front corner pieces  23  made of die-cast aluminum, a rear frame part  24  also made of die-cast aluminum, as well as a front cross strut  25  and two longitudinal struts  26 , which are fabricated as extruded profiles, preferably also made of aluminum. The rear frame part  24  has two frontwardly projecting hollow arms  27 , into which the longitudinal struts  26  are inserted positively. The corner pieces  23  have pins, not visible in the figure, which are inserted into cavities of the struts  25  or  26 . Horns  28  projecting obliquely to the side and upward from the corner pieces  23  as well as projections  29  of the rear frame part  24  are used for fastening the engine frame  14  on the longitudinal members  19  of the body  18 . 
         [0041]    As is particularly clear from the enlarged view of a corner piece  23  in  FIG. 5 , the corner pieces  23  have a chassis-like structure comprising a base plate and intersecting reinforcing ribs  30  which protrude vertically upward and downward from this base plate. Since the base plate in the view in  FIG. 5  is completely concealed behind one of the frontmost of the reinforcing ribs  30 , its profile in  FIG. 5  is indicated by a dashed line  31 . Two triangular supporting plates  32  project from the frontmost reinforcing rib  30 , holding one of the hinge bolts  13  between them. Since the supporting plates  32  like the reinforcing ribs  30  are vertically oriented, the base plate  31 , the reinforcing ribs  30 , the supporting plates  32 , and the hinge bolt  13  can be fabricated in one piece using a simple forming tool, of which the two mold halves can be moved away from one another vertically, parallel to the reinforcing ribs  30  and supporting plates  32  during demolding of the finished corner piece. 
         [0042]      FIG. 6  shows a perspective view of the front module  3 . The radiator frame  11  is fabricated in one piece in hybrid technology by overmolding with plastic a thin-walled sheet deep-drawn substantially in the form of the finished radiator frame, for reinforcement. The radiator assembly  10  received in a central opening of the radiator frame  11  here comprises an engine cooler  33  and an air-conditioning or compressor cooler  34 . The bumper support  9  is connected to lateral struts of the radiator frame  11  via deformation elements  35 , also designated as crashboxes. A bumper reinforcing bracket  36  extends horizontally below the bumper support  9  and is fastened to the radiator frame  11  by means of two large-area flanges  37 . 
         [0043]      FIG. 7  shows the right lower corner of the front module  3  in an enlarged view. The downwardly open fork  15  can be fastened directly on the radiator frame  11 , on the reinforcing bracket  36 , or on the flange  37 . 
         [0044]      FIG. 8  shows the engine frame  14  of the chassis module  2  and the front module  3  in the assembled state. Due to the deep drawing, the inner sheet of the radiator frame has a curved cross-section in large parts, and the resulting hollow rear side of the radiator frame  11  is reinforced by a network of ribs  38 , which form a frame extending around the central opening of the radiator frame  11 . The flanges  21  supporting the bumper support  9  and the reinforcing bracket  36  project from these rib-reinforced regions of the radiator frame  11  in the lateral direction. 
         [0045]      FIG. 9  shows the rear side of one of the flanges  21  at the height of the bumper support  9 . A centering element  39  made of elastic plastic comprises a base plate, which is fastened on the front side of the flange  21  between this and the deformation element  35  as well as a pointed guide pin  40  and a locking hook  41 , which project backward through an opening  42  formed in the flange  21 . 
         [0046]      FIG. 10  shows the engine frame  14 , part of the longitudinal member  19 , and the front module  3  after pivoting the front module  3  into its final position. The flanges  21  of the radiator frame  11  abut against the flanges  22  which terminate the longitudinal members  19  toward the front. As can be seen in the enlarged view in  FIG. 11 , the guide pin  40  and the locking hook  41  of the centering element  39  have passed through an opening  43  of the flange  22 . The locking hook  41  acts on the rear side of the flange  22  and thus secures the front module  3  in the position shown. In this position holes  44  of the flange  22  are aligned with holes  45  (see, for example,  FIG. 6 ,  9 ) in the flange  21  of the radiator frame  11  so that the front module  3  can be permanently fastened to the longitudinal members  19  with the aid of screws inserted in the holes  44 ,  45 . These screws can be inserted after the vehicle has already left the assembly station so that this is already available again after a short time for assembly of the next vehicle. 
         [0047]      FIG. 12  shows a schematic vertical section through the front module  3 , one of the corner pieces  23  of the engine frame  14  as well as the flanges  21 ,  22  locked onto one another. The structure of the corner piece  23  with the substantially horizontal base plate  31  and a plurality of vertical reinforcing ribs  30  intersecting the base plate  31  can be clearly identified in  FIG. 12  just the same as the curved cross-section of the horizontal struts of the radiator frame  11 , which is open at the back and reinforced by the ribs  38 . The contacting flanges  21 ,  22  are shown enlarged in  FIG. 13 . The centering element  39  is locked vertically in an opening  45  of the flange  21  while maintaining clearance in the vehicle transverse direction, and aligns automatically when, upon pivoting of the front module  3 , oblique surfaces  46 ,  47  of the guide pin  40  and the locking hook  41  impinge upon the edges of the opening  43 . Despite possible dimensional tolerances, a rapid and secure locking of the locking hook  41  at the edge of the opening  43  is thus ensured. 
         [0048]      FIG. 14  shows a perspective view of the front region of a body  18  according to a second embodiment of the invention. As a result of this embodiment, a bumper support  9  is mounted by means of deformation elements  35  at the front ends of longitudinal members  19  before the body  18  is joined to front and chassis modules  3 ,  2 .  FIG. 15  shows an enlarged view of the connection between one of the longitudinal members  19  and one of the deformation elements  35 . An opening  43  for receiving a locking hook of the front module  03  (not shown in  FIGS. 14 ,  15 ) can be seen in an edge zone of a flange  22  disposed between longitudinal members  19  and deformation element  35 , which zone projects toward the interior of the body. A support  48  extending downward from the end of the longitudinal member  19  forms a stop for the placement of the body on the chassis module. 
         [0049]      FIG. 17  shows the engine frame  14  of the chassis module  2  of the second embodiment together with a front module  3  placed thereon. On the underside of its radiator frame  11 , the front module  3  has forks, not visible in  FIG. 17 , which, as described with reference to  FIG. 4  to  FIG. 7 , embrace hinge bolts projecting over a front transverse strut  49  of the engine frame. In this embodiment, a bumper reinforcing bracket  36  is mounted on the transverse strut  49  of the engine frame  14  and supports an air baffle  50  projecting from the radiator assembly  10  held in the radiator frame  11 . The front module  3  is thereby held stably in the position shown in  FIG. 17  without requiring the supporting column  17  on the assembly plate  1  for this. The vehicle type specificity of the assembly station can thus be further reduced. Two cutouts  51  open toward the top are formed on lateral flanks of the air baffle  50 . These are provided to receive the bumper support  9  when the body  18  is lowered onto the chassis module  2 . 
         [0050]    The radiator frame  11  shown in  FIG. 16  in a front view approximately has the shape of a trapezium which tapers upward. This shape facilitates the joining of chassis and front module  2  or  3  to the body  18 . 
         [0051]    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.