Abstract:
An integrated door substrate and pelvic bolster is provided for use in a vehicle. The integrated component is formed from a polymerizable material by injection molding. The pelvic bolster is formed from thin lateral walls that buckle and tear under compressive loading. The pelvic bolster is designed to bend but not fracture under load, thus maintaining a continuous loading curve.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates generally to collapsible door structures for use with vehicle doors. More particularly, the present invention relates to a collapsible pelvic bolster that is integral with the vehicle door substrate and is produced therewith. 
       BACKGROUND OF THE INVENTION 
       [0002]    Side impact events in vehicles have been identified as one of the top priorities for both research and regulation with government requirements continuing to become more stringent. These additional requirements make designs for door trim systems more challenging because they may impact the door trim at the pelvic bolster. It is known in vehicles to provide a pelvic bolster composed of polymerized foam, such as polyurethane (PU) and expanded polypropylene (EPP). While providing certain attractive features, both materials have limitations. Specifically, in the case of polyurethane, the material cost is relatively high. This becomes of increasing concern particularly as pelvic safety zones are increased in size. In the case of expanded polypropylene, while the cost of this foam tends to be cheaper than the cost of polyurethane, this material has other limitations. First, expanded polypropylene tends not to use modifiers, so there may be some temperature dependence. Second, expanded polypropylene tends to be heat staked, thus reducing the volume available for energy absorption. 
         [0003]    In addition, both polyurethane and expanded polypropylene are inherently separate from the door trim substrate, which adds to manufacturing operations, costs and complexity. Some efforts are being made to provide pelvic bolsters, separate from the door trim substrate, formed from a material other than foam, such as injection molding, but these efforts are also unsatisfactory because of manufacturing and assembly costs. 
         [0004]    Accordingly, as in so many areas of vehicle technology, there is room in the art of vehicle door design for an alternative configuration to known pelvic bolster structures which provides effective protection that can be adapted to a variety of shapes while maintaining relatively low manufacturing and assembly costs. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention generally provides a door assembly in which the energy absorption characteristics are integrated in the door trim substrate by providing a door substrate having a pelvic bolster formed thereon as opposed to the use of a separate foam or plastic piece. The pelvic bolster absorbs energy by placing the door trim substrate and related stiffening features in a complex loading condition, which may include tension, compression, and shear loading. As the occupant intrudes into the door trim, the pelvic bolster absorbs energy by placing the door trim substrate in bending and tension, in a manner similar to a trampoline. The pelvic bolster is designed to bend but not fracture under load, thus maintaining a continuous loading curve. 
         [0006]    The molded substrate having the pelvic bolster formed thereon of the disclosed invention is preferably composed of molded polypropylene (PP), but other polymerizable materials may be used. An integrally-molded pelvic bolster is able to generate load more quickly than foam. Accordingly, higher forces earlier in the event allow for a reduction in peak loads later. In addition, the lateral stiffness of the pelvic bolster may be designed to vary significantly over the surface of the bolster so that occupants of different sizes, who would sit in different locations in the vehicle, would see different loads. Simulations have shown that the component design of the disclosed invention meets the requisite loading curves. 
         [0007]    Other advantages and features of the invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    For a more complete understanding of this invention, reference should now be made to the embodiments illustrated in greater detail in the accompanying drawings and described below by way of examples of the invention wherein: 
           [0009]      FIG. 1  illustrates a portion of a stiffened panel according to the disclosed invention positioned at a first location of an interior door panel; 
           [0010]      FIG. 2  is a sectional view of a door trim assembly shown prior to the impact of an occupant; 
           [0011]      FIG. 3  is the same view of the door trim assembly of  FIG. 2  but showing the assembly after impact of an occupant; 
           [0012]      FIG. 4  illustrates a view of a door assembly viewed from the inside of the vehicle having the substrate integrated pelvic bolster of the present invention; 
           [0013]      FIG. 5  is a sectional view of the door without the interior door panel of  FIG. 4  taken along lines  5 - 5 ; 
           [0014]      FIG. 6  illustrates a view of the door of  FIG. 4  but shown without the interior door panel to reveal the door substrate and support structures formed thereon and illustrating an alternative location from that shown in  FIG. 1 ; 
           [0015]      FIG. 7  is a view of the substrate integrated pelvic bolster of the present invention is illustrated prior to an impact event; 
           [0016]      FIG. 8  is a view similar to that of  FIG. 7  but showing the pelvic bolster early into an impact event; 
           [0017]      FIG. 9  is a view similar to that of  FIG. 8  but showing the pelvic bolster mid-way through the impact event; 
           [0018]      FIG. 10  is a view similar to that of  FIG. 9  but showing the pelvic bolster late in the impact event; 
           [0019]      FIG. 11  is a perspective view of an alternate construction of the pelvic bolster of the disclosed invention; and 
           [0020]      FIG. 12  is a perspective view of an additional construction of the pelvic bolster of the disclosed invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]    In the following Figures, the same reference numerals will be used to refer to the same components. In the following description, various operating parameters and components are described for different constructed embodiments. These specific parameters and components are included as examples and are not meant to be limiting. 
         [0022]    With reference to  FIG. 1 , a view of a door trim substrate  10  is shown from the outboard side of the vehicle, looking inboard. Integral to the door trim substrate  10  is a set of energy absorbing features  12 , a storage pocket  14 , a storage pocket wall  16 , and a storage pocket extension  18 . In the preferred embodiment the energy absorbing features include various rib elements, generally illustrated as a first generally vertical rib  20 , a second generally vertical rib  22 , a third generally vertical rib  24 , a first generally horizontal rib  26 , and a second generally horizontal rib  28 . The rib  24  and the rib  28  are shown having shapes as compared to the other rib elements in order to increase the lateral stiffness of the door trim system at those locations. An occupant&#39;s seating position is generally predictive of that occupant&#39;s size, which is generally predictive of the occupant&#39;s resistance to lateral injuries. The rib structure is shown for illustrative purposes only and is not intended as being limiting. 
         [0023]    With reference to  FIG. 2 , a sectional view of the door trim system, generally illustrated as  30 , is shown prior to occupant contact. The door trim system  30  includes a door inner sheetmetal  32 , a door trim substrate  34 , and a door trim finish panel  36 . Integrally molded into the door trim substrate  34  is a storage pocket extension  38  and an energy absorbing rib  40 . In this illustration, any potential appearance concerns are masked by the additional door trim finish panel. Other embodiments may remove the finish panel and cover the door trim substrate with a vinyl or other material. The occupant&#39;s pelvis  42  is shown prior to contact with the door trim system. 
         [0024]    With reference to  FIG. 3 , the door trim system  30  is shown following occupant contact. The door trim system  30  is composed of several parts, including the door inner sheetmetal  32 , the door trim substrate  34 , and the door trim finish panel  36 . Integrally-molded into the door trim substrate are two additional features, including the storage pocket extension  38  and the energy absorbing ribs  40 . As shown, the occupant&#39;s pelvis  42  is interacting with the door trim system  30 . As the occupant&#39;s pelvis  42  continues to move relative to the door trim system  30 , the energy absorbing rib  40  deforms. It is this deformation along with the deformation of the surrounding door trim substrate  34  and the door trim finish panel  36  that absorb substantial levels of crash energy. 
         [0025]    With reference to  FIG. 4 , a view of a door assembly, generally illustrated as  50 , is shown from the inside of the vehicle. The door assembly  50  is of the standard type and it is to be understood that different configurations of the door are envisioned within the scope of the present invention. The door assembly  50  includes an outer panel (or skin)  52 , an interior panel  54 , an armrest and grab handle assembly  56 , a map pocket  58 , and a pelvic bolster  60 . It is also to be understood that the general configuration of the interior panel  54  and the particular configurations of the armrest and grab handle assembly  56 , the map pocket  58 , and the pelvic bolster  60  are shown for illustrative purposes only and are not intended as being limiting. Particularly, the armrest and grab handle assembly  56 , the map pocket  58 , and the pelvic bolster  60  could be configured differently in terms of shape, size and overall configuration. 
         [0026]    In  FIG. 5  and  FIG. 6  the interior panel  54  of the door assembly  50  has been removed, revealing a door substrate  70 . As is known in the art, the door substrate  70  includes a variety of supporting structures, including, for example, a first armrest support structure  72  and a second armrest support structure  74 . It is to be understood that any of a great variety of support structures may be provided in a variety of different configurations. 
         [0027]    A door pocket closeout  76  is formed on the door substrate  70  as is known in the art. Adjacent the door pocket closeout  76  is a pelvic bolster support structure  80 . The pelvic bolster support structure  80  may also be of a variety of shapes and sizes and it is to be understood that the placement, size and shape of the pelvic bolster support structure  80  illustrated in  FIG. 5  and  FIG. 6  is for demonstrative purposes only. 
         [0028]    According to one of the objectives of the disclosed invention, the pelvic bolster support structure  80  is formed integrally with the door substrate  70  such that, collectively, the pelvic bolster support structure and the door substrate are one and the same piece. This simplifies manufacturing and assembly. 
         [0029]    To provide the pelvic bolster support structure  80  with the requisite impact-responsive characteristics the pelvic bolster support structure  80  is formed from a series of relatively thin walls that collapse, fold and in some instances tear in a relatively controlled, non-random way. A better understanding of this arrangement may be established by reference to  FIG. 7  through  FIG. 12  in which the pelvic bolster support structure  80  is first illustrated, in  FIG. 7 , in its pre-impact state. In  FIG. 8  through  FIG. 12  the pelvic bolster support structure  80  is illustrated in different stages of an impact event, with  FIG. 8  illustrating the pelvic bolster support structure  80  early in an impact event,  FIG. 9  illustrating the pelvic bolster support structure  80  mid-way through an impact event, and  FIG. 12  illustrating the pelvic bolster support structure  80  at the last stage of the impact. 
         [0030]    With reference to  FIG. 7 , the pelvic bolster support structure  80  is shown in detail. It is to be understood that the pelvic bolster support structure  80  is an integral part of the door substrate  70  in all of these views. It is also to be understood that the illustrated pelvic bolster support structure is shown in one of many possible arrangements, and thus the illustrated configuration and its related description are provided for non-limiting illustrative and explanatory purposes. 
         [0031]    The pelvic bolster support structure  80  includes an upper wall  82 , a lower wall  84 , a first side wall  86 , and a second side wall  88 . The walls  82 ,  84 ,  86 , and  88  may be modified and adapted as needed to fit within a prescribed area. Within the outer structure defined by the walls  82 ,  84 ,  86 , and  88  are a pair of substantially vertical walls  100  and  100 ′ and a pair of substantially horizontal walls  102  and  102 ′. A greater or lesser number of vertical and horizontal walls may be provided. The vertical walls  100  and  100 ′ and the horizontal walls  102  and  102 ′ may be formed in a variety of ways. As illustrated, each of these walls is formed to define a recessed area. 
         [0032]    Along the upper wall  82  is preferably provided a plurality of flanges  90 ,  90 ′,  90 ″ and  90 ′″. Along the lower wall  84  is also preferably provided a plurality of flanges  94 ,  94 ′, and  94 ″. Similarly, along the first side wall  86  is preferably provided a plurality of flanges  96 ,  96 ′,  96 ″, and  96 ′″ and along the second side wall  88  is preferably provided a plurality of flanges  98 ,  98 ′,  98 ″, and  98 ′″. All of the flanges are angled away from the pelvic bolster support structure  80 . A greater or lesser number of flanges may be provided and the flanges may be of a shape, configuration, and placement other than that as shown. Of course, the flanges themselves may not be provided. 
         [0033]    With reference to  FIG. 8 , the pelvic bolster support structure  80  is shown in the earliest stage of an impact event. The flanges  90 ,  90 ′,  90 ″ and  90 ′″ on the upper wall  82 , the flanges  94 ,  94 ′, and  94 ″ on the lower wall  84 , the flanges  96 ,  96 ′,  96 ″, and  96 ′″ on the first side wall  86  and the flanges  98 ,  98 ′,  98 ″, and  98 ′″ on the second side wall  88  have all begun to be pressed downward and outward, as have the walls  82 ,  84 ,  86  and  88 . This outward motion causes a tearing condition at the seams between the walls  82 ,  84 ,  86  and  88 , for example, at seams  104 ,  106  and  108 . In addition, the vertical walls  100  and  100 ′ and the horizontal walls  102  and  102 ′ are also beginning to bend. 
         [0034]    As the deflection increases, as illustrated in  FIGS. 9 and 12 , the vehicle occupant (not shown) would contact more and more material to insure that the load increases. As the impact event proceeds as illustrated in  FIG. 9 , which is about half way through the event, and  FIG. 12 , which is at the end of the event, the walls  82 ,  84 ,  86 , and  88  continue to bend outwardly, substantially like a rose petal. The tearing of the seams, such as the seams  104 ,  106 , and  108 , also continues. 
         [0035]    The walls of the pelvic bolster support structure  80  are preferably formed from a thin polymerized material which substantially enables energy absorption. (If the walls were thick then the pelvic bolster support structure  80  would tend to fracture. Conversely, thin walls bend and provide a more continuous loading curve.) The pelvic bolster support structure  80  works in an impact event because it relies upon relatively thin load-bearing walls in combination with the designed-in outward bending of the walls as guided by the flanges. This arrangement creates a loading curve which is more continuous than those known. The thickness, placement, and arrangement of all of the walls  82 ,  84 ,  86 ,  88 ,  100 ,  100 ′,  102  and  102 ′ can be modified or tuned as needed to provide maximum results. 
         [0036]    While the pelvic bolster support structure of  FIGS. 5 through 12  provide an approach to providing the desired integrated pelvic bolster and door substrate, other arrangements are possible and are provided in  FIGS. 11 and 12 . 
         [0037]    With reference first to  FIG. 11 , a pelvic bolster support structure  110  is illustrated and is formed integral with a door substrate  70 ′. The pelvic bolster support structure  150  is composed of a plurality of pyramid-like structures having a base  112  that is integrally formed with the door substrate  70 ′ and a top  114 . As illustrated, the base  112  is wider than the top  114 . The thickness, size, shape, arrangement, and number of the pyramid-like structures may be modified as required to achieve the desired results. 
         [0038]    With reference next to  FIG. 12 , a pelvic bolster support structure  120  is illustrated and is formed integral with a door substrate  70 ″. The pelvic bolster support structure  120  is composed of a plurality of pyramid-like structures having a base section  122  that is integrally formed with the door substrate  70 ″ and a top section  124 . As illustrated, the base section  122  is wider at its lower end than at its top end. Similarly, the top section  124  is wider at its lower end than at its top end. As with the pelvic bolster support structure  110  of  FIG. 11 , the thickness, size, shape, arrangement, and number of the pyramid-like structures may be modified as required to achieve the desired results. In addition, a greater number of sections may be added. Furthermore, some structures may have a greater or lesser number of sections than adjacent or other structures. 
         [0039]    The foregoing discussion discloses and describes exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the true spirit and fair scope of the invention as defined by the following claims.