Abstract:
A support structure for a motor vehicle body includes, but is not limited to a side member extending between an engine compartment and a wheel installation space, a wheel installation brace running above the wheel installation space and a unitary stiffening element extending above the wheel installation space and connecting the wheel installation brace with the side member, on which one or a plurality of fastening points for the attachment of an engine and/or transmission mounting are formed.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to German Patent Application No. 10 2011 111 236.0, filed Aug. 20, 2011, which is incorporated herein by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    The technical field relates to the bodywork of a motor vehicle body, in particular the front region of such a body. 
       BACKGROUND 
       [0003]    The supporting parts of a motor vehicle body are connected in a fixed manner both to engine and transmission as well as to a passenger cell of the vehicle and are well suited for transmitting vibrations of the engine and of the transmission to the passenger cell. In order to avoid this leading to extreme noise pollution in the passenger cell it is known to provide vibration dampers between engine and transmission on the one hand and passenger cell on the other hand, and to arrange fastening points via which the engine and transmission are connected to the supporting bodywork parts so that they can preferably conduct away only a preferably minor part of the vibration. Examples for such engine mountings are found, for example, in US 2003/0136601 A1 or U.S. Pat. No. 5,466,033. 
         [0004]    On the one hand, the supporting parts of a motor vehicle body are to be as light as possible in weight in order to make possible a fuel-saving operation of the vehicle, while on the other hand they must have a high stiffness in order to impart to the body the torsional rigidity for normal driving operation and ensure an effective occupant protection in the event of accidents. In addition, those parts of the body outer skin, which could be struck by a passenger during an accident, should be yielding and spaced away from vehicle parts which are not deformable in the event of an accident involving a pedestrian such as for example supporting structures of the body or an engine block so far that they can continuously decelerate the impact of the pedestrian and prevent his/her striking through onto the non-deformable parts. However, the more distant the supporting bodywork parts have to be from the vehicle outer skin in order to satisfy the requirements of the pedestrian protection, the more rigid and heavier must these be in order to be able to guarantee a required torsional rigidity of the body. 
         [0005]    Since any weight increase, on the one hand because of material costs, on the other hand because of an increased fuel requirement due to weight, brings with it costs for a user of the motor vehicle, there is a need for proposals as to how the weight of a motor vehicle body can be reduced while maintaining or even improving stiffness while adhering to the need for pedestrian protection at the same time. 
         [0006]    In view of the foregoing, at least one object is to supply such a proposal. 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 
       [0007]    A support structure is provided for a motor vehicle body having a side member extending between an engine compartment and a wheel installation space, a wheel installation brace running above the wheel installation space and a one-piece stiffening element extending over the wheel installation space and connecting the wheel installation brace with the side member, one or a plurality of fastening points for the fastening of an engine or transmission mounting are formed on the stiffening element. 
         [0008]    The stiffening element can practically comprise an L-like or T-like shape with a longitudinal section extending over the side member and fastened to the side member distributed in longitudinal direction and a cross section having a distal end running from the longitudinal section in transverse direction and fastened to the wheel installation brace. Preferentially, at least one of the fastening points is provided on the transverse section. In particular, when the latter rises towards the wheel installation brace, a statically favorable connecting point for the engine mounting located high up can be created in this manner. In order to optimize the bending stiffness of the stiffening element, at least one bead continuously extends preferentially between the longitudinal section and the transverse section. 
         [0009]    The longitudinal section can comprise flanges angled off in opposite directions fastened to the side member on both sides of a center piece. Such a structure is particularly suited for fastening to a side member, which in turn is assembled from an inner panel bent hat-like located towards the engine compartment and a closing plate facing the wheel installation space and welded to the rims of the hat-shaped inner panel, for one of the flanges can be welded to one of the upper rims and the other to a center piece of the inner panel. 
         [0010]    The longitudinal section of the stiffening element can be corrugated in longitudinal section; between two peaks of the longitudinal section each comprising the fastening points a trough touching the side member and supporting itself on the latter can be formed. In order to stabilize the transverse section between side member and wheel installation brace, said transverse section can practically comprise a flange on a side facing the passenger cell, which is fastened to a spring strut mounting. Preferentially, the transverse section and a reinforcing part extending between the wheel installation brace and the side member complement each other into a hollow profile. 
         [0011]    The flange of the transverse section can be fastened to the spring strut mounting in particular via a flange of the reinforcing part. The reinforcing part can be extended as far as to below the side member in order to form a support that acts on an engine frame or auxiliary frame. In order to securely fix the engine carrier with little use of material, the fastening points are to be practically located not on a line but define the corners of a triangle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and: 
           [0013]      FIG. 1  is a perspective view of parts of a motor vehicle body according to an embodiment; 
           [0014]      FIG. 2  is an enlarged detail from  FIG. 1 ; 
           [0015]      FIG. 3  is a stiffening element of the motor vehicle body; 
           [0016]      FIG. 4  is the stiffening element together with an inner plate of a side member; 
           [0017]      FIG. 5  is a closing plate of the side member with a spring strut mounting and a complementary reinforcing part following said closing plate; 
           [0018]      FIG. 6  is a cross section through the structure shown in  FIG. 2 ; and 
           [0019]      FIG. 7  is a second cross section along a sectional plane displaced in parallel to the plane of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    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. 
         [0021]    With the motor vehicle body partially shown in  FIG. 1 , two side members  3  and two wheel installation braces  4  extend forward from a front wall  1 , which separates the engine compartment  2 , shown empty here without engine and transmission therein, from a passenger cell located behind it. At their front ends, the side members  3  are connected by a bumper  5 . Supports  6 ,  7  extending downwards from the side members  3  act via vibration-damping rubber buffers which are not shown on an auxiliary frame, also called engine frame, which is likewise not shown, which closes off the engine compartment to the bottom and carries engine, transmission and front axle of the vehicle. Arms  8 , obliquely raising upwards to the outside in extension of the front supports  7  hold the peaks of the wheel installation braces  4 . 
         [0022]    In a middle region, the wheel installation braces  4  are each supported by a stiffening element  9 . The stiffening element  9  is approximately T-shaped in top view, with a longitudinal section  10  extending on the side member  3  and a transverse section  11  extending in an arc from the side member  3  to the wheel installation brace  4 . The stiffening element  9  is unitarily deep-drawn from a sheet metal blank. Two fastening points  13  for attaching a bearing pedestal  12  shown in  FIG. 2  and supporting engine and transmission in lateral direction are formed on the longitudinal section  10 ; a third fastening point  14  is located on the transverse section  11  opposite the previously mentioned ones, offset vertically and in vehicle transverse direction. 
         [0023]    As is evident in particular by the enlarged representation of the stiffening element  9  in  FIG. 3 , the longitudinal section  10  comprises two flanges  15  and  16  which are substantially oriented vertically and, between the flanges  15 ,  16 , a middle region running wave-shaped in vehicle longitudinal direction, which is divided into horizontal sections  17 ,  18 ,  19 , which in the assembled state rest on the side member  3 , horizontal sections  20 ,  21  spaced from the side member  3 , in which the fastening points  13  are formed, as well as inclines continuously connecting these sections. Two beads  22  extend across the flange  16  as far as into the transverse section  11  following thereon. At its outer end, the transverse section  11  carries an angled-off flange  23  for welding to the wheel installation brace  4 . The transverse section  11  is divided in cross section into four sections similar to a W, a substantially vertical flange  24  on its side facing the front wall  1 , a substantially horizontal wall  25  in cross section, a vertical wall  26  and a second approximately horizontal flange  27 . 
         [0024]      FIG. 4  and  FIG. 5  illustrate the attachment of the stiffening element  9  in the body. For the sake of clearer representation, an inner profile  28  of the side member  3  that is hat-shaped in cross section and a closing plate  29  of the latter are shown separately from each other although at the time of the installation of the stiffening element  9 , these are already connected in a fixed manner to each other into side member  3  and to a wheel installation housing  30 . As is evident in  FIG. 4 , the flanges  15 ,  16  of the stiffening element  9  hug an upper welding flange  31  of the inner profile  28  as well as a middle vertical wall section  32  of the latter facing the engine compartment  2  where they are welded together. 
         [0025]    The wheel installation housing  30  fills out an intermediate space, which towards the engine compartment  2  is limited by the closing plate  29  of the side member  3 , in vehicle transverse direction towards the outside by the wheel installation brace  4 , towards the back by the front wall  1  and towards the front by a reinforcing part  33 , which extends in an arc from the outside of the support  6  as far as to the wheel installation brace  4 . By welding the flanges  24 ,  27  of the stiffening element  9  to corresponding flanges  34 ,  35  of the reinforcing part  33 , a hollow member that can be subjected to a high load with low weight is created between the side member  3  and the wheel installation brace  4 . 
         [0026]      FIG. 6  shows a section in vehicle transverse direction through the side member  3 , the stiffening element  9 , the reinforcing part  33  and a part of the wheel installation brace  4 . In the reinforcing part  33 , a protrusion  36  is tightened opposite the fastening point  14 , on the inside of which a welding nut  37  is attached. A screw  38  fixing the bearing pedestal  12  is held in the welding nut  37 ; a sleeve  39  surrounding the screw  38  stabilizes the distance between the stiffening element  9  and the reinforcing part  33  and prevents a deformation during the tightening of the screw  38 . In a corresponding manner, a welding nut  37  is attached in the interior of the side member  3  in  FIG. 7 , which shows a cross section at the height of one of the fastening points  13  of the longitudinal section  10 , and the distance between the top of the side member  3  and the longitudinal section  10  is stabilized through a sleeve  39  surrounding the screw  38 . 
         [0027]    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.