Abstract:
A front end assembly for a vehicle includes a U-shaped tubular structure, a body portion having a pair of laterally-spaced, longitudinally extending cowl sides, and, a pair of laterally-spaced A-pillar structures. The U-shaped tubular structure is secured to each A-pillar and each cowl side at longitudinally-spaced apart locations. The laterally-spaced connection points provide improved rigidity and reduce distortion.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a front end assembly for an automobile vehicle. 
     2. Background Art 
     Conventional front end assemblies are often made by stamping and welding together several individual frame components. One of the major challenges for manufacturing is to maintain rigidity because these assemblies are often a combination of a number of various frame parts. As each of the frame parts are attached to form subassemblies and then are attached to the body portion of the vehicle, it becomes more difficult to achieve the necessary or desired stiffness in the front end. This problem is sometimes referred to as “matchboxing.” Matchboxing is a phenomenon that occurs when the sheet metal portion of the vehicle is attached to the frame and tends to sway on a hinge point and move from a desired perfect square orientation to a parallelogram orientation. Distorting the sheet metal in this manner may result in poor natural frequency characteristics of the front end structure. 
     Hydro-formed tubular elements are increasingly being used in the construction of vehicle body structures. Hydro-forming is a metal forming process that uses high-pressure fluids to outwardly expand tubular blanks to conform with the surfaces of a die cavity of a die assembly to form a contoured hydro-formed part. 
     Vehicle front end assembly processes have yet to take full advantage of the capabilities of tubular hydro-formed parts. A number of prior patents have described the use of tubular members in hybrid front end assemblies, but fail to address the matchboxing issue. For example, Gerricke et al., U.S. Pat. No. 6,416,119 B1, describes a vehicle front end constructed through the use of hydro-formed tubes. In Gerricke, a first body structure formed from a plurality of tube members and a second body structure formed from sheet metal are welded to each other in a sandwiching relationship. However, this method is still subject to matchboxing because the sheet metal structure can be distorted as it is secured to the tube members. 
     There is a need for a front end construction that may incorporate the use of hydro-formed tubes that provides superior stiffness and rigidity when compared to conventional vehicle front end assembly designs. There is a further need for a front end assembly process that minimizes any tendency of the assembly to distort or matchbox. There is also a need to eliminate structural reinforcements, reduce part counts, and improve the durability of the vehicle body. 
     The above problems and needs are addressed by Applicants&#39; invention as summarized below. 
     SUMMARY OF THE INVENTION 
     The present invention provides A front end assembly for a vehicle, comprising a U-shaped tubular structure, a body portion having a pair of laterally-spaced, longitudinally extending cowl sides, and a pair of laterally-spaced A-pillar structures. The U-shaped tubular structure is secured to each A-pillar and each cowl side at longitudinally-spaced apart locations. The longitudinally-spaced connection of the U-shaped tubular structure provides improved rigidity and reduces distortion. 
     A second aspect of the present invention is to provide a method for assembling a vehicle front end having a pair of side tubes each having a front end portion, a body end portion, a first connecting point, and a second connecting point, a radiator support tube having a left end and a right end, a pair of A-pillars each having a securing portion, a body structure having a pair of cowl sides each containing a pair of first and second cowl side securing points, the tubular side structures being secured to each A-pillar and each cowl side at longitudinally-spaced apart locations. The method includes connecting the radiator support tube extending in a transverse direction to the front ends of the pair of side tubes extending in a longitudinal direction with the left end and the right end to form a generally U-shaped tubular structure. The body structure extending in a transverse direction is aligned with the U-shaped tubular structure such that the pair of first connecting points are disposed adjacent to the pair of first cowl side securing points. The pair of A-pillar structures are aligned with the U-shaped tubular structure such that the body end portion of each side tube contacts one of the securing portions of the A-pillar. The U-shaped tubular structure is joined to the A-Pillar, the body structure, and the cowl top at longitudinally-spaced connection points such that a body end portion is secured to each of the pair of A-pillar securing portions, and each of the second connecting points are secured to one of second securing points of the cowl side. 
     A third aspect of the present invention is to provide a front end assembly for a vehicle comprising a U-shaped tubular structure comprising an inboard surface and an outboard surface, the outboard surface having a pair of laterally-spaced end connections, the inboard surface having at least one pair of laterally-spaced connecting points, a body portion having a pair of laterally-spaced, longitudinally extending cowl sides, and a pair of laterally-spaced A-pillar structures, each A-pillar having a sidewall and a transverse wall. The U-shaped tubular structure is secured between each A-pillar and each cowl side at longitudinally-spaced apart locations such that each end connection is secured to one of the sidewall walls such that the U-shaped tubular structure passes through each transverse wall and each of the side tube structure connecting points is secured to one of the cowl sides. 
     A fourth aspect of the present invention is to A front end assembly for a vehicle comprising a pair of laterally spaced side tube structures having an upper tube and a lower tube, each side tube structure having a front end, a body end, a first connecting point, and a second connecting point, a radiator support tube structure, a body portion having a pair of first and second securing points laterally spaced apart, and a pair of A-pillar structures laterally spaced apart having a sidewall and a transverse wall, each sidewall having a first securing point and a second securing point. The side tube structures are secured between each A-pillar and each cowl side at longitudinally-spaced apart locations such that each side tube structure passes through one A-pillar transverse wall such that the body end is secured to one A-pillar first securing point and to one A-pillar second securing point, each side tube structure front end is secured to the radiator support tube structure, and each side tube structure first connecting point and second connecting point are secured to one body portion first securing point and one body portion second securing point. 
     These and other features and advantages of the invention will be more fully understood from the following detailed description of the invention in view of the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an improved front end assembly made according to one embodiment of the present invention; 
         FIG. 2  is an exploded perspective view of an improved front end assembly according to one embodiment of the present invention; 
         FIG. 3  is a fragmentary interior side elevation view of an A-pillar made according to one embodiment of the present invention; 
         FIG. 4  is a fragmentary perspective view of a portion of a front end assembly made according to one embodiment of the present invention; 
         FIG. 5  is a fragmentary interior side elevation view of an A-pillar attached to two tubular frame members according to one embodiment of the present invention; 
         FIG. 6  is a cross-sectional view taken along the line  6 — 6  in  FIG. 5 ; 
         FIG. 7  is a fragmentary interior side elevation view of a cowl panel attached to two tubular frame members according to one embodiment of the present invention; 
         FIG. 8  is a fragmentary perspective view of an improved front end assembly made according to one embodiment of the present invention; 
         FIG. 9  is a cross-sectional view taken along the line  9 — 9  in  FIG. 8 ; and 
         FIG. 10  is a cross-sectional view taken along the line  10 — 10  in  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , an improved front end assembly for a vehicle is generally identified by reference numeral  10 . The front end assembly  10  comprises a body portion  12  and a U-shaped tubular structure  14 . The U-shaped tubular structure  14  comprises a left side tube structure  16 , a right side tube structure  18  and a radiator support tube structure  20 . Right and left side designations as used herein refer to the sides of the vehicle relative to the driver of the vehicle. The side tube structures  16 , 18  are mirror images of each other. Each side tube structure  16 , 18  extends in a longitudinal direction generally further forward of the body portion  12  to a radiator support structure  20 . The radiator support structure  20  generally extends transversely across the front of the vehicle and perpendicular to the longitudinal direction of the side tube structures  16  and  18 . Each side tube structure is independently connected to the radiator support structure  20  by a U-shaped bracket  22  or similar connector. The tubes are hydroformed. They can also be formed from extrusions, seamless tubes or seamed tubes. The tubes may be formed with varying thicknesses throughout their length to save weight. 
     Referring to  FIGS. 1 and 2 , the left and right side tube structures each comprise an upper tube  24  and a lower tube  26 . Each upper tube  24  comprises a body end  28 , a first connecting point  30 , a second connecting point  32 , a support portion  34 , an upper cooling portion  36 , and a front end  38 . The upper tube  24  has an inboard surface  40  and an outboard surface  42 . The outboard surface  42  has a plurality of access holes  44  that provide clearance for installation as well as performing securing operations. The upper tube  24  extends from a higher relative vertical position to a lower vertical position between the upper cooling portion  36  and the front end  38 . The front end  38  is attached to the radiator support tube  20 . 
     Each lower tube  26  of the left and right side tube structures  16 , 18  comprises a body end  46 , a first connecting point  48 , a second connecting point  50 , a support portion  52 , and a front end  54 . Each lower tube  26  has an inboard surface  56  and an outboard surface  58 . The lower tube has a plurality of access holes  60  that provide access for installation and for performing welding or other assembly operations associated with the assembly of the front end. 
     The lower tube  26  and the upper tube  24  are secured together in order to form each of the side tube structures  16 , 18 . In the preferred embodiment of  FIG. 1 , a bottom surface  62  of the upper tube  24  and a top surface  64  of the lower tube  26  are secured to each other along the respective surfaces to allow the upper tube second connecting point  32  and the lower tube second connecting point  50  to be disposed in close proximity to each other. Furthermore, an inboard surface  66  of the lower tube  26  and an outboard surface  42  of the upper tube  24  are secured together in close proximity to the upper tube front end  38  and the lower tube front end  54  respectively. The upper tubes  24  and the lower tubes  26  extend longitudinally toward the front of the vehicle and joined together prior to connecting to the radiator support tube  20 . The upper tube  24  is formed to be inboard of the lower tube  26  such that the upper tube front end  38  is disposed in a vertical plane inboard of the upper body end  28 . Similarly, the lower tube front end  54  is located in a vertical plane more inboard than the lower tube body end  46 . 
     The body portion  12  will now be further described. A dash structure  70  and an underbody structure  72  are joined together. A cowl inner structure  74  is attached along the forward portion of the dash  70 . A pair of cowl sides  78 ,  80  are each attached longitudinally to the dash  70  and cowl inner  74 . 
     A pair of laterally-spaced A-pillars  82 , 84  are positioned such that each is outboard of the respective cowl side. The left and right cowl sides  80 ,  78  and the left and right A-pillars  84 , 82  are mirror images of each other. The right A-pillar  82  is shown attached to the right cowl side  78 , the dash structure  70 , and the underbody structure  72 . Body portion  12  may be formed from sheet metal or structural plastic components that are combined to form an assembly. 
       FIG. 2  is an exploded view of a partial side perspective of one embodiment of the invention. The right cowl side  78  includes a cowl side flange  86  that extends in an outboard direction and forms essentially a 90 degree angle with the cowl side  78 . A portion of the right cowl side  78  extends forward longitudinally and contains a second securing point  88 . A plurality of vertical clearance holes  89  are formed in each cowl side to allow for thru access to the A-pillar  84  (described below). 
     Referring to  FIGS. 1 and 2 , the cowl inner  74  is the part of the body portion  12  extending laterally in a horizontal plane between the pair of cowl sides  78 , 80 . Referring to  FIG. 2 , a portion of the cowl inner  74  shows a peripheral flange  92  extends in an outboard direction from an end portion  90  of the cowl inner  74 . 
     Each A-pillar  82 , 84  comprises a sidewall  94  that extends generally in a vertical and longitudinal plane. A transverse wall  96  extends inwardly from a forward edge  98  of the A-pillar towards the cowl side inner  78 . The transverse wall  96  has a lower clearance opening  100  and an upper clearance opening  102  separated by a portion of the transverse wall  96 . 
     A cowl top  104  is shown extending across the top of the cowl inner  74 . The cowl top  104  is attached to the cowl inner  74  and the cowl side  78 . A formed flange  106  is provided on each end of the cowl top  104 . 
     Referring to  FIG. 3 , an interior surface  108  of the sidewall  94  of the right A-pillar  82  is shown supporting a hinge reinforcement bracket  110 . Bracket  110  is attached to the interior surface  108  of each A-pillar. The bracket  110  is attached to the A-pillar  82  by either fasteners or a welding process. A perpendicular flange  111  of the upper hinge reinforcement bracket  110  extends inwardly from the interior surface  108 . The flange is located to be level with the lower edge of the clearance opening  102 . 
     The body portion  12  and the U-shaped tubular structure  14  connections shall be described in detail with specific reference to  FIGS. 1 ,  2 , and  4 . The body portion comprises the underbody structure  72 , the dash structure  70 , the cowl inner  74 , and the left and right cowl sides  80 , 78  that are assembled together.  FIG. 1  shows the cowl inner  74  attached to the left cowl side  80  and the right cowl side  78 . A right cowl end portion  90  contains a peripheral flange  92  which is fabricated to mate with the corresponding cowl side flange  86  located on each cowl side  78 , 80 . 
       FIG. 4  is a fragmentary view of a portion of the front end assembly in its final position. The cowl side flange  86  and the peripheral flange  92  are secured together. The upper tube  24  rests on top of the peripheral flange  92 . The first connecting point  30  is disposed on the peripheral flange  92 . Each upper tube can be secured to each peripheral flange  92  by conventional means through the access hole  44 . The second securing point  88  located on each cowl side is disposed adjacent to the upper tube second connecting portion  32  and the lower tube second connecting point  50 . Access holes  44  in the upper and lower tubes provide for the use of conventional securing methods such as spot welding to be used. 
     Referring to  FIG. 5 , the right A-pillar  82  is assembled to the body end portion  46  and body end portion  28  of the U-shaped tubular structure  14 . The upper tube  24  passes through the forward clearance opening  102  of the A-pillar and rests on the flange surface  111  of the upper hinge reinforcement bracket  110 . The lower tube  26  extends through the lower clearance opening  100  of the A-pillar  82  and contacts the A-pillar sidewall  94  to which it is secured. 
     Referring to  FIG. 6 , the upper tube  24  is shown resting on the flange  111  of the hinge reinforcement bracket. The upper tube may be secured to both the sidewall  92  and the flange  111  by spot welding or another conventional securing method. 
     Referring to  FIG. 7 , an interior side view of the cowl side  78  attached to the upper and lower tubes  24 , 26  will be described. The upper and lower tubes  24 , 26  are secured at the second securing point  88 . The upper tube  24  is supported by the cowl side flange  86 . An upper access hole  113  and a lower access hole  114  are provided in the cowl side  78 . Access holes  113  and  114  are aligned with the upper and lower tubes  24  and  26 , respectively, to provide access for assembly operations. 
     Referring to  FIGS. 8 and 9 , the cowl top  110  is disposed over the top of the cowl inner  74 . The cowl top flange  106  located on each end of the cowl top  110  is aligned with a top surface of the upper tube  118  adjacent to the first connecting point  30 . Upper tube  26  has an access or clearance hole  119  in its outboard surface for securing the cowl top flange  106  to the upper tube top surface  118 . The access hole  119  also provides for securing the upper tube bottom surface  62  to both the cowl inner peripheral flange  92  and the cowl side flange  86 . 
     Referring to  FIG. 10 , a cross-sectional view taken along the line of  10 — 10  in  FIG. 8  will now be described. The upper tube  24  and the lower tube  26  have clearance holes  44 , 50 , respectively in their outboard surfaces to provide access for conventional securing tools to attach the tubes to the cowl side  78 . 
     In an alternative embodiment of a front end assembly, the lower tube  26  and the upper tube  24  may be secured together in order to form each side tube structures similar to  FIGS. 1 and 2  with each lower tube  26  of the left and right side tube structures  16 , 18  comprising a body end  46  moved further outboard than the upper tube body end  28 . The vertical offset of the upper and lower tubes would provide further rigidity. Correspondingly, each of the A-pillar sidewalls and transverse walls would be mirror the offset to accommodate the upper and lower tubes. 
     While the best mode for carrying out the invention has been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.