Abstract:
A running board assembly is provided that has structural tubing mounted to one of the spaced, longitudinally-extending frame rails. The structural tubing is configured to bear side impact loads in part by providing a continuous load-bearing path to direct the load to the frame rail. Additionally, because the structural tubing is of a higher strength than materials typically used for running boards, the structural tubing itself absorbs some of the side impact load.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to a vehicle running board assembly mounted to a vehicle frame rail. 
       BACKGROUND OF THE INVENTION 
       [0002]    To assist in entering and exiting the passenger compartment, pickup trucks and SUVs may be outfitted with side platforms or “running boards” that extend lengthwise beneath and alongside the passenger compartment of the vehicle at a position adjacent to the passenger doors in order to provide a convenient step surface. Running boards may be relatively flat, board-like surfaces, or may be tubular, serving the same function, but offering a different aesthetic look and appeal. Running boards are typically secured to sheet metal rocker panel assemblies that run longitudinally under the passenger doors. Running boards are generally constructed from various materials, such as stainless steel, chrome, brushed metal, and/or injection-molded plastics and are designed to be sturdy enough to support the weight of a vehicle user standing on the running board while not unnecessarily adding additional weight to the vehicle. Thus, in a side impact situation, energy absorption by the running board is limited, as neither the running board nor the rocker assemblies are typically designed to perform the side impact energy absorption functions performed by structural members such as the frame. 
       SUMMARY OF THE INVENTION 
       [0003]    A running board assembly is provided that has structural tubing mounted to a longitudinally-extending frame rail. The structural tubing is configured to bear side impact loads in part by providing a continuous load-bearing path to direct the load to the frame rail. Additionally, because the structural tubing is of a higher strength than materials typically used for running boards, the structural tubing itself absorbs some of the side impact load. As used herein, “structural tubing” is tubing having adequate wall thickness, material properties, and section geometry to enable the transmission of loads similar in magnitude to those capable of being borne by frame members in an impact event, as opposed to non-structural elements, which are not designed to withstand such loading and will fail at loads significantly below those capable of being borne by the frame. For example, structural tubing with a 2.5 inch diameter and 0.125 inch wall thickness would be of adequate load-bearing ability. As used herein “running board” and “running board assembly” is not limited to embodiments with a flat, board-like stepping member, but instead includes those with structural tubing, and may alternately be referred to as a stepping member and a stepping member assembly. 
         [0004]    More specifically, the structural tubing may include a first structural tubing portion that is generally perpendicular to the frame rail. This first structural tubing portion may be laterally-aligned with a cross member, such as a transmission support, that spans the space between the frame rail and another longitudinally-extending frame rail, and is rigidly attached to both frame rails. Thus, the first structural tubing portion, the frame rail and the cross member at least partially define a load-bearing path for side impact loads. 
         [0005]    In some embodiments, the first structural tubing portion is mounted to the frame rail via a closed-section mounting member, which also forms part of the continuous load-bearing path. The first structural tubing portion is welded or otherwise rigidly secured (e.g., by bolts) to the mounting member. The closed-section mounting member is welded or otherwise rigidly secured (e.g., by bolts) to the frame rail. As used herein, “closed-section” means that the mounting member is substantially continuous in a cross-section taken laterally therethrough where the first structural tubing portion mounts to the mounting member. 
         [0006]    The structural tubing may also have a second structural tubing portion extending longitudinally and secured to a laterally outward end of the first structural tubing portion so that it is spaced from one of the frame rails by the first structural tubing portion. If a like running board assembly is secured to the other frame rail via a like mounting member, the running board assemblies, mounting members, frame rails and cross-member form a side impact assembly with a continuous load-bearing path formed from an outer extremity (i.e., a laterally outboard extremity) of the second structural tubing portion of one of the running board assemblies to an outer extremity of the second structural tubing portion of the other running board assembly. 
         [0007]    The second structural tubing portion may have inwardly-extending end portions spaced forward and rearward of the first structural tubing portion and also rigidly connected to the same frame rail that the first structural tubing portion is connected to, preferably by like, closed-section mounting members. A trim member may be secured to an upward-facing surface (i.e., a stepping surface) of the second structural tubing portion. Additionally, the second structural tubing portion may be cylindrical or non-cylindrical in a lateral cross-section. A non-cylindrical second structural tubing portion may be configured to provide a generally flat stepping surface. 
         [0008]    The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a schematic plan view illustration of a vehicle with a first embodiment of running board assemblies mounted to two longitudinal frame rails; 
           [0010]      FIG. 2  is a schematic cross-sectional fragmentary view of the vehicle of  FIG. 1  taken at the lines  2 - 2  in  FIG. 1 ; 
           [0011]      FIG. 3  is a schematic perspective illustration of one of the running board assemblies of  FIG. 1  having cylindrical structural tubing; 
           [0012]      FIG. 4  is a side cross-sectional view of a first alternative embodiment of a running board assembly with non-cylindrical structural tubing; 
           [0013]      FIG. 5  is a side cross-sectional view of a second alternative embodiment of a running board assembly with non-cylindrical structural tubing; and 
           [0014]      FIG. 6  is a side cross-sectional view of a third alternative embodiment of a running board assembly with non-cylindrical structural tubing. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]    Referring to the drawings, wherein like reference numbers refer to like components,  FIG. 1  shows a vehicle  10 . In this embodiment, the vehicle  10  is represented generally by a vehicle body  11  that is of a pickup-type. The body  11  defines an engine compartment  12 , a passenger compartment or cab portion  14 , and a bed  16 . However, a variety of other types of vehicles may be used within the scope of the invention, including sport utility vehicles and trucks. 
         [0016]    The vehicle  10  has longitudinally-extending (i.e., running fore and aft) frame rails  18 ,  20 . The frame rails  18 ,  20  are of a structural, load-bearing material, such as structural steel, and are connected to other frame components (not shown) to add structural integrity to the vehicle. The frame rails  18 ,  20  may each be a unitary component, formed by hydro-forming or another method, or may have separate inner and outer members welded or otherwise secured to one another. 
         [0017]    A transmission cross-member  22  spans the lateral space between the frame rails  18 ,  20  (i.e., inboard of the frame rails  18 ,  20 ), and is rigidly connected to and supported by the frame rails  18 ,  20 . As shown in  FIG. 2 , the cross member  22  is bolted to each of the frame rails  18 ,  20  with bolts  24  and forms a cradle to support a transmission (not shown) in the space  26  between the cross member  22  and a floor assembly  28 . Sheet metal rocker assemblies  27 A,  27 B are secured to the floor assembly  28  and run generally fore and aft. Door assemblies  29 A,  29 B, also formed of sheet metal, fiberglass or the like, interfit with the rocker assemblies  27 A,  27 B and other frame pillars, such as A-pillars and B-pillars (not shown), as is readily understood by those skilled in the art. The vehicle body  11  is connected to the vehicle frame rails  18 ,  20  via tabs welded to the frame rails. A threaded fastener passes through each tab to connect the frame rails  18 ,  20  to the body  11 . Elastomeric bushings are positioned between the tabs and the body  11  to isolate the body  11  from the tabs. The tabs, bushings and fasteners are not shown in the cross-section of  FIG. 2 , but are known and will be understood by those skilled in the art, and are most likely located forward or rearward of the mounting members  42 A,  42 B, shown and discussed below with respect to  FIG. 2 .  FIG. 2  is a schematic partial cross-sectional view, showing only a portion of the vehicle  10  from a lower portion of the door assemblies  29 A,  29 B and below. 
         [0018]    Running board assemblies  30 A,  30 B are rigidly connected to the respective frame rails  18 ,  20 . As best viewed in  FIGS. 1 and 3 , running board assembly  30 A is structural tubing including a first tubing portion  32 A that is generally perpendicular to the frame rail  18 . Likewise, running board assembly  30 B is structural tubing including first tubing portion  32 B that is generally perpendicular to frame rail  20 . A respective second tubing portion  34 A,  34 B extends longitudinally and is secured to the first tubing portions  32 A,  32 B outboard thereof by welding or other means. The second tubing portions  34 A,  34 B are each formed with inwardly curved end portions  36 A forward of the first tubing portions  32 A and inwardly curved end portions  38 A rearward of the first tubing portions  32 A,  32 B. End portions  36 A and  38 A are shown only with respect to second tubing portion  34 A in  FIG. 3 ; second tubing portion  34 B has substantially identical end portions  36 B,  38 B, as illustrated in  FIG. 1 . 
         [0019]    An inboard end  40 A,  40 B (see  FIG. 2 ) of the first tubing portions  32 A,  32 B, and inboard ends of the end portions  36 A,  36 B,  38 A,  38 B (see  FIG. 1 ) are welded or otherwise secured to respective rigid closed-section mounting members  42 A,  42 B, also referred to as stanchions. As used herein, “closed-section” means that the mounting members  42 A,  42 B are solid structural steel in cross-sectional view. In this embodiment, the mounting members  42 A,  42 B are steel plates bolted to the respective frame rails  18 ,  20  laterally outboard thereof with bolts  43  (shown in  FIG. 1 ) extending through bolt openings  44  (shown in  FIG. 2 ) aligned with corresponding openings in the frame rails  18 ,  20 . A trim member  46  is secured to an upward-facing surface  48  (i.e., a stepping surface) of the second structural tubing portion  34 A (and a like trim member  46  is secured to second structural tubing portion  34 B as shown in  FIG. 2 ). The trim members  46  may be plastic or of any other material suitable for enhancing traction at the surface  48  and/or to meet desired styling. For example, the trim members may be more extensive, and may extend inward toward the mounting member  42 A to provide a larger stepping area, similar to typically, flat running boards. The respective first and second tubular portions  32 A,  34 A and  32 B,  34 B may be referred to as running boards. The running board assemblies  30 A,  30 B include the first and second tubular portions  32 A,  34 A and  32 B,  34 B (i.e., the running boards), the trim members  46  (if provided), and the mounting members  42 A,  42 B, respectively. 
         [0020]    Referring again to  FIGS. 1 and 2 , the cross member  22  is longitudinally (fore and aft; see  FIG. 1 ) and laterally (sideways, at overlapping elevations; see  FIG. 2 ) aligned with the running board assemblies  30 A,  30 B. Thus, from an outer extremity  52 A of running board assembly  30 A to an outer extremity  52 B of running board assembly  30 B, a side impact assembly  50  is formed by the assembled running board assemblies  30 A,  30 B (including the first and second tubular portions  32 A,  34 A and  32 B,  34 B, the trim members  46  (if provided), the mounting members  42 A,  42 B, frame rails  18 , and cross member  22 ) that forms a continuous load-bearing path when subjected to a side impact force F. Accordingly, the impacting force F will be transferred to the frame rails  18 ,  20  and the cross member  22  to begin energy dissipation as soon as the force F contacts the outer extremity  52 A. Laterally inward deformation of either of the door assemblies  29 A,  29 B and/or rocker assemblies  27 A,  27 B due to the side impact force F should be mitigated by the energy absorption of the more rigid side impact assembly  50  with its greater energy absorbing capability. 
         [0021]      FIGS. 4-6  illustrate alternative embodiments of running board assemblies, and particularly the running board structural tubing portions thereof any of which may be used on vehicle  10  of  FIGS. 1 and 2  in lieu of running board assembly  130 A with a like, symmetrical running board assembly also used in lieu of running board assembly  130 B. Referring to  FIG. 4 , a running board assembly  130  is illustrated. Running board assembly  130  includes a first structural tubing portion  132  secured at one end to a mounting member  42 A (such as by bolts or welding) and secured at an opposing end to a second structural tubing portion  134 . (Note that second structural tubing portion  134  has inwardly curved end portions (not shown) that would be secured at additional mounting members  42 A to the frame rail  18 .) At least a portion of the second structural tubing portion  134  is non-cylindrical and elongated in cross-section and provides a generally flat stepping surface  148  on which trim member  146  is secured. 
         [0022]    Referring to  FIG. 5 , running board assembly  230  includes a first structural tubing portion  232  secured at one end to a mounting member  42 A (such as by bolts or welding) and secured at an opposing end to a second structural tubing portion  234 . (Note that second structural tubing portion  234  has inwardly curved end portions (not shown) that would be secured at additional mounting members  42 A to the frame rail  18 .) The second structural tubing portion  234  is non-cylindrical in cross-section and provides a generally flat stepping surface  248  on which trim member  246  is secured. 
         [0023]    Referring to  FIG. 6 , running board assembly  330  includes a first structural tubing portion  332  secured at one end to a mounting member  42 A (such as by bolts or welding) and secured at an opposing end to a second structural tubing portion  334 . (Note that second structural tubing portion  334  has inwardly curved end portions (not shown) that would be secured at additional mounting members  42 A to the frame rail  18 .) The second structural tubing portion  334  is non-cylindrical and elongated in cross-section and provides a generally flat stepping surface  348  on which trim member  346  is secured. 
         [0024]    While the best modes for carrying out the invention have 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 within the scope of the appended claims.