Abstract:
An expansible enclosure adapted for storage across the flooring surface of a transportation vehicle beneath the foot of an occupant. The enclosure is expansible away from the underlying flooring surface and generally towards the foot of the occupant so as to engage the foot during a deceleration event thereby providing prolonged supporting contact to the foot during the deceleration event.

Description:
TECHNICAL FIELD 
     This invention is related generally to inflatable vehicle protective devices and, more particularly, to an expansible bolster element disposed along the flooring surface of a vehicle and deployable upwardly towards the feet of the vehicle occupant upon the occurrence of an activating collision event. 
     BACKGROUND OF THE INVENTION 
     Inflatable bolsters have been developed to enhance vehicle occupant protection in the event of sudden vehicle deceleration. In particular, such devices have been developed in the form of knee bolsters to increase the duration of deceleration of occupants&#39; femurs and to control upper torso kinematics during a frontal impact event. Representative knee bolster systems are illustrated and described in U.S. Pat. Nos. 6,213,497 and 6,203,057 to Spencer et al. the teachings of which are each incorporated by reference as is fully set forth herein. In such systems, the bolster impact surface is moved from a stored position to an extended position to intercept occupants&#39; knees early in the impact event. This allows the knees more time to decelerate to the final velocity of the vehicle. The initial positioning of the bolster impact surface in a retracted stored position allows styling flexibility and enhances leg room prior to deployment. 
     While deployable knee bolsters are believed to provide substantial protection to the knees and femur of a vehicle occupant, such systems do not substantially address energy transfer between the occupants&#39; feet and the underlying vehicle flooring. Impact studies have recently shown that during a sudden deceleration interaction between an occupant&#39;s feet and the flooring surface of the vehicle may lead to injury. Such injury may be particularly likely to occur during the act of braking as the operator of the vehicle attempts to respond in a rapid manner to a perceived impending collision event. The possibility of injury may be enhanced as the foot pivots during interaction with the braking pedal. Furthermore, if the foot is not centered in the middle of the brake pedal, the possibility exists that the foot may turn to one side thereby further promoting the potential for injury. Of course, in the case of a vehicle incorporating a manual transmission, such issues are also encountered with respect to operation of the clutch pedal. Moreover, non-operating vehicle passengers may be subjected to similar types of energy transfer which may lead to injury during a deceleration event such as when the foot is not positioned squarely on the flooring surface. 
     Common injuries seen in the lower extremities of occupants following collision events include heel injuries, ankle injuries, and injuries to the lower tibia. Such injuries are generally the result of contact between the heel and the toe pan region of the flooring surface. The use of static padding elements to support the foot under the heel area has been contemplated. However, due to the limited space availability below the operating pedals, padding of sufficient thickness to provide substantial benefit may be difficult to incorporate. Moreover, if padding of excessive thickness is used, the feet may be forced into localized compressed pockets surrounded by a raised surface of uncompressed padding. Such localized indentation may be undesirable in the event of a secondary impact such as a side collision due to the fact that the feet are unduly constrained. 
     SUMMARY OF THE INVENTION 
     This invention provides advantages and alternatives over the prior art by providing a highly efficient energy absorption device to support the foot and heel during a rapid deceleration event. The device also aids in preventing an operator&#39;s foot from slipping off the brake and/or clutch pedals if contact between the foot and the pedal is off center when in the braking mode. In addition, the device incorporates a shallow profile configuration which occupies only a minor degree of space beneath the feet of the occupant and which may be hidden in a substantially undetectable manner beneath the carpeting on the vehicle floor. 
     These advantages are accomplished in a potentially preferred form of the invention by providing a hollow expansible enclosure adapted for storage at the intersection of the toepan and floorpan regions of the vehicle floor. The hollow enclosure is expansible away from the underlying flooring support surface and generally towards the foot of the occupant to be protected so as to engage the foot at an early stage of the deceleration event and to thereafter provide prolonged supporting contact between the hollow enclosure and the foot. The hollow enclosure is preferably formed of a substantially rigid material such as plastic, polycarbonate, or the like so as to provide a substantially non-cavity forming expanded surface for interaction with the foot of the occupant to be protected. 
     Preferably, the hollow enclosure is of a generally profiled geometry so as to mate with the contour of the interface between the toepan and the floorpan regions of the underlying flooring support surface. The expanded depth dimension of the hollow enclosure may be either uniform throughout the structure or may be enhanced in a region substantially in opposing relation to the heel of the occupant to be protected so as to provide added energy absorption at that location. The hollow enclosure may also have an enhanced expanded profile extending in a direction laterally of the foot of the occupant to be protected so as to offset the effects of lateral flexion in the event that the foot is misplaced or slips off of the pedal during the deceleration event. 
     Preferably, expansion of the hollow enclosure is carried out by the collapsible deformation of accordion style rib elements normally extending in raised and lowered relief away from the underside of the enclosure and towards the face portion thereby causing the face to be projected towards the foot of the occupant to be protected. The materials forming the underside and the face portion may be either similar or dissimilar in character. If desired, the hollow enclosure may be formed as a single piece construction by means of highly efficient injection or blow molding techniques. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A full enabling disclosure of the present invention is set forth more particularly in the remainder of the specification, including reference to the accompanying figures in which: 
     FIG. 1 is a cut-away side view of a vehicle interior illustrating a lower extremity energy absorption device in a stored position prior to activation; 
     FIG. 2 is a view similar to FIG. 1 following expansion of the energy absorption device; 
     FIG. 3 is a plan view of one embodiment of the energy absorption device as shown in FIGS. 1 and 2; 
     FIG. 4 is a view taken generally along line  4 — 4  in FIG. 3; 
     FIG. 5 is a view taken generally along line  5 — 5  in FIG. 3; 
     FIG. 5A is a view similar to FIG. 5 illustrating an expansible element of multi-piece construction with the face separated from the underside. 
     FIG. 6 is a plan view of an alternative embodiment of the energy absorption device according to the present invention incorporating a substantially non-profiled configuration; 
     FIG. 7 is a view taken generally along line  7 — 7  in FIG. 6 illustrating the substantially flat profile configuration. 
    
    
     While the invention has been illustrated and generally described above and will hereinafter be described in connection with certain potentially preferred embodiments, constructions and practices, it is to be understood that in no event is the invention to be limited to such illustrated and described embodiments, constructions or practices. On the contrary, it is intended that the present invention shall extend to all alternatives and modifications as may embrace the broad principles of this invention within the true spirit and scope thereof. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now to the drawings, wherein like reference numerals have been utilized to designate like components throughout the various view, in FIG. 1 there is illustrated the interior of a vehicle  10  such as a automobile as will be well known to those of skill in the art. As illustrated, the vehicle  10  includes a front seat  12  which may be used to support a front seated vehicle occupant  14 . The vehicle  10  may further include one or more rear seats which may be used to support additional occupants (not shown). While the front seat  12  is illustrated as being located on the driver&#39;s side of the vehicle  10 , it is to be appreciated that the present invention is also useful in the protection of an occupant (not shown) seated on the passenger side of the vehicle  10 . 
     As shown, the vehicle  10  includes an instrument panel  16  disposed in substantially opposing relation to the occupant  14 . A steering wheel  18  extends generally away from the instrument panel  16  for manipulation by the occupant  14 . The vehicle  10  includes a flooring support surface  20 . As will be appreciated by those of skill in the art, the flooring support surface  20  typically includes a floorpan portion  22  extending to a position in front of the front seat  12  to an angled transition zone. The flooring support surface  20  typically further includes a toepan portion  24  angled upwardly away from the floorpan portion  22  towards the underside of the instrument panel  16 . On the driver&#39;s side of the vehicle  10 , the toepan portion  24  is disposed generally behind a plurality of operating pedals  26  for manipulation by the occupant  14  using his or her feet  30 . As will be appreciated, in the event that the vehicle  10  incorporates an automatic transmission, the operating pedals  26  typically include an accelerator pedal and a brake pedal while in a manual transmission vehicle  10 , a clutch pedal will also be present. As will be further appreciated, the configuration of the flooring support surface  20  is typically substantially duplicated on the passenger side of the vehicle but with the omission of the operating pedals  26 . 
     According to the embodiment of the present invention as illustrated in FIGS. 1-3, an expansible element  40  of relatively thin profile is disposed across a portion of the flooring support surface  20  generally at the intersection between the floorpan portion  22  and the toepan portion  24  beneath the operating pedals  26 . The expansible element  40  preferably occupies a similar position on the passenger side of the vehicle  10 . 
     As best illustrated in FIG. 3, the expansible element  40  is preferably of a generally shallow panel-like configuration including a gas inlet opening  42  for introduction of an inflating medium into the expansible element  40 . The expansible element  40  may be secured in place to the flooring support surface  20  by an arrangement of attachment tabs  44  as shown. As illustrated in FIG. 4, the expansible element  40  preferably includes a face portion  46  arranged facing generally towards the feet  30  of the occupant  14  and an underside  48  generally opposing the flooring support surface  20 . The face portion  46  and the underside  48  define the upper and lower boundary surfaces of an expansible chamber  49 . 
     According to the potentially preferred practice, the underside  48  is molded to incorporate a plurality of deformable profile elements  50  in the form of collapsible pleats projecting from the underside  48  towards the face  46  across the expansible chamber  49  between the face portion  46  and the underside  48 . The profile elements  50  are preferable arranged in a concentrated pattern at locations where expansion of the expansible element  40  is to be promoted. In particular, it is contemplated that the expansible element  40  preferably includes a plurality of profile elements  50  in the region adjacent the lower edge of the expansible element  40  in opposing relation to the heel of the occupant  14 . As best illustrated in FIG. 2, this configuration gives rise to enhanced expansion of the expansible element  40  towards the heel upon introduction of inflation gas through the gas inlet opening  42 . 
     As illustrated in FIG. 5, one or more profile elements  50  may also be arranged in a pattern so as to extend in a generally lateral direction (i.e. substantially parallel) to the normal position of the feet  30  of the occupant  14 . Such an arrangement of profile elements  50  in a generally lateral direction is believed to provide a stabilizing surface peripheral to the pedals  26  thereby aiding in the prevention of lateral flexure of the feet  30  in the event that the feet  30  are out of position or slip off of the pedals  26 . According to the illustrated embodiment, the profile elements arranged laterally of the pedals  26  are disposed generally outboard of the normal position of the feet  30 . However, it is likewise contemplated that such profile elements may also be disposed at positions generally inboard of the normal position of the feet  30  if desired. 
     In operation, upon the occurrence of an initiating event such as deceleration exceeding a certain level, an inflating gas is released from an inflator (not shown) for introduction into the expansible chamber  49  between the face portion  46  and the underside  48 . As inflation gas enters the expansible chamber  49 , an enhanced internal pressure is established. This pressure buildup causes the profile elements  50  to undergo at least a partial collapse towards the flooring support surface  20 . This collapse in turn causes the face portion  46  to be thrust upwardly away from the flooring support surface  20  and towards the opposing feet  30  of the occupant  14  so as to result in the desired interaction. The expansible element  40  may thereafter undergo a force dissipating collapse as the deceleration event proceeds to conclusion. As will be appreciated, by controlled patterning of the profile elements  50  at predetermined locations across the expansible element  40 , substantial inflation may be achieved at desired locations without interfering with the ability to fully depress the pedals  26  needed for operation. Accordingly, in the zone directly beneath the pedals  26 , little if any expansion may take place while substantial inflation may take place in the regions below and to the side of the pedals  26  as may be desired. 
     It is contemplated that the expansible element  40  may be formed from a single material as a unitary structure using injection-molding or blow molding practices. It is also contemplated that the face  46  and underside may be formed of separate materials and thereafter jointed together by means such as welding, mechanical clamping or the like. In such a configuration, it is contemplated that the face portion  46  may be of a more rigid material than the material forming the underside  48  thereby promoting preferential deformation of profile elements  50 . Such differential rigidity may be achieved by adjusting the thickness of the face portion  46  relative to the underside  48  or by using polymers of different durometer for the face portion  46  and the underside  48 . Potentially preferred materials for forming the face portion  46  and the underside  48  are thermoplastic moldable polymers including by way of example only, polypropylene, polycarbonates, polyurethanes, and combinations thereof. 
     It is believed that injection molding of expansible element  40  may permit the achievement of extremely close tolerances which may be desirable in some applications. However, other molding techniques as may be known to those of skill in the art including by way of example only, compression molding, extrusion, blow molding, and the like may also be utilized if desired. 
     As previously indicated, the expansible element may be formed as separate components which are thereafter joined together in a desired configuration. By way of example, it is contemplated that the face may be formed separately from the underside and thereafter joined to the underside. The separate components of such a multi-piece construction are illustrated in spaced apart aligned relation in FIG. 5A in which the expansible element  40 ′ is formed from a face portion  46 ′ which may be welded or otherwise secured in place over a separately formed underside portion  48 ′. 
     As indicated, it is contemplated that the materials forming the face portion  46  and the underside  48  may be either of similar or dissimilar chemical composition. According to one embodiment, the face portion  46  is formed from an injection molded polycarbonate thermoplast of high rigidity and impact strength while the underside  48  is formed from a flexible injection molded polyurethane rubber. The use of materials of such different rigidity tends to facilitate the preferential deformation of the profile elements  50  across the underside  48  while simultaneously permitting the face portion  46  to resist substantial surface deformation and thereby provide a substantially uniform contact surface for the feet  30  of the occupant  14 . 
     According to the embodiment illustrated in FIGS. 1-5, the expansible element  40  is of a profiled cross-sectional geometry so as to conform to the contour of the flooring support surface  20 . As illustrated in FIG. 1, this configuration gives rise to a toe impact portion  52  and to a heel impact portion  54  in raised relation to the toe impact portion  52  immediately opposing the heel of the occupant  14 . As best illustrated in FIG. 4, this profile orientation may be enhanced by the configuration of the attachment tabs  44  which may be used to maintain the lower portion of the expansible element  40  in a slightly raised condition relative to the heel prior to expansion so as to provide early interaction with the heel of the occupant  14  upon activation. Moreover, such attachment tabs  44  may be of a deformable character such that upon engagement between the expansible element  40  and the feet of the occupant  14 , the tabs  44  may themselves undergo either elastic or plastic deformation so as to provide further energy dissipation. 
     While the expansible element  40  is illustrated as having fluid communication throughout its interior, it is likewise contemplated that the expansible element  40  may be subdivided into two or more substantially discrete chambers each of which are independently inflatable if desired. Such independent expansion may provide further control over the final expanded profile if desired. 
     As indicated, it is contemplated that the final expanded profile of the expansible element  40  may be controlled to a substantial degree by the location and number of profile elements  50  extending towards the face portion  46 . In general, it is believed that the larger the surface area of the profile elements in a given region, the greater the outer projection will be for the face portion  46  opposing those profile elements  50 . It is contemplated that further control over the expansible characteristics may be achieved by limiting the degree of separation between the face portion  46  and the underside  48  in locations where inflation is not desired. By way of example only, and not limitation, it is contemplated expansion may be limited in predefined locations by the establishment of fixed connections between the interior surfaces of the face portion  46  and underside  48 . Such fixed connections may be established by an arrangement of weld points  56  arranged in a predefined desired pattern across the expansible element  40  thereby establishing substantially zero length tethers between the face portion  46  and the underside  48 . By way of example only, it is contemplated that such limitation on expansion may be introduced in regions of the expansible element  40  immediately below the pedals  26 . 
     While the present invention may incorporate a generally profiled configuration promoting enhanced expansion beneath the heel of the occupant  14  in a manner as previously illustrated and described, it is likewise contemplated that a substantially flat panel configuration may also be utilized to provide a number of benefits. Such a configuration is illustrated in FIG. 6 wherein elements previously described are denoted by like reference numerals increased by 100. As illustrated, in this embodiment, the expansible element  140  is substantially planar in configuration thereby establishing a substantially flat panel bounded by a face portion  146  and underside  148  (FIG.  7 ). In such a configuration, expansion takes place by simple outward expansion between the face  146  and the underside  148 . Such a configuration may be particularly suitable for use in opposing relation to a front or rear seated non-operating passenger whose feet are typically not in well defined positions. As with previously described embodiments, energy may be further dissipated by deformation of the attachment tabs  144  if desired. 
     Regardless of the embodiment utilized, it is believed that the present invention provides a useful energy dissipation device which may be stored prior to activation along the flooring support surface  20  of a vehicle  10  in an unobtrusive manner below the carpeting or other material overlying the flooring support surface  20 . The present invention is thus believed to provide a useful advancement over the state of the art. It is to be understood that while the present invention has been illustrated and described in relation to certain potentially preferred embodiments, constructions and procedures, that such embodiments, constructions and procedures are intended to be illustrative only and that the present invention is in no event to be limited thereto. Rather it is contemplated that modifications and variations embodying the principles of this invention will no doubt occur to those of skill in the art. It is thus contemplated and intended that the present invention shall extend to all such modifications and variations as may incorporate the broad aspects of the invention within the full spirit and scope of the appended claims and all equivalents thereto.