Abstract:
An armrest which is sufficiently sturdy to support vertical loads but is deformable when a side impact collision occurs so as to avoid injury to an occupant. In one embodiment, a top platform pivots up when a supporting trim panel section is collapsed and a crush cell structure is collapsed under a side impact condition. In another embodiment, a cover molding encloses the crush cell structure is crushable with the structure in a side impact collision.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. provisional application No. 60/793,840 filed on Apr. 20, 2006. This application is a continuation in part of U.S. application Ser. No. 11/190,693 filed on Jul. 26, 2005. 

   BACKGROUND OF THE INVENTION 
   In a side impact collision, where a vehicle is hit from the side by another vehicle, the impact is typically taken by the front and rear doors and the body structure surrounding the doors. An arm rest structure on the inside of the vehicle doors is primarily provided as a convenience feature to support one arm of each of the occupants. Typically, the armrest structure is padded on the outside with foam for comfort and has interior structure such as one or more brackets to provide substantial vertical stiffness to support service and abuse loads (such as in the extreme case of someone standing on the armrest to access the roof). The arm rest must also have enough lateral stiffness to enable opening and closing of the door using a door handle incorporated in the arm rest. The armrest should also have sufficient fatigue strength to withstand the repeated door openings and closings over the life of the vehicle. To satisfy these requirements, the armrest ends up being a very stiff structure that does not crush easily so that forcible contact with an occupant&#39;s abdomen will result in internal injuries to the occupant in the event of a side impact crash. 
   Such deformable armrests have heretofore been proposed, as for example in U.S. Pat. Nos. 6,893,077 and 5,951,094. 
   To cushion the pelvis during such a side impact crash, a foam block is typically placed between the door trim panel and the door inner panel. However, foam suffers from several disadvantages such as a “stack-up” load increase after about 50% to 60% of foam compression due to foam cell wall flattening. Typically there also is degradation of foam material properties over time and at high temperature (e.g., foam can become quite soft in compression at high temperatures). 
   It is an object of the present invention to provide a vehicle armrest which is capable of supporting substantial vertical loads while being crushable on side impact to effectively protect an occupant from injury by contact with the armrest. 
   It is a further object of the present invention to provide a side impact pelvic cushion which is not subject to age or temperature degradation and is effective through widely varying range of loadings. 
   SUMMARY OF INVENTION 
   The above recited objects as well as other objects which will become apparent upon a reading of the following specification and claims are achieved by an armrest assembly including a trim panel segment sloping upwardly and inwardly from the inside of the door panel forming a ledge feature which presents only moderate lateral crushing resistance combined with a crush cell structure which is crushed upon collapse of the trim panel segment towards the door inner panel. The trim panel is preweakened as with a groove pattern to as to be readily collapsed in a side impact collision. In a first embodiment of the invention, the armrest is underlain by foam on a platform slotted to be crushable in a sideways direction. 
   Beneath the platform disposed between the outer sloping trim panel segment and door inner panel is the crush cell structure comprised of one or more crush cells defined by thin sheet metal formed into closed figures configured to be flattened by a side impact, which structure is attached to the door inner panel and trim panel segment such as to be rigid to vertically applied loads but readily crushable by side impact loads. 
   The foam and foam platform compress as the crush structure is collapsed. 
   In a second embodiment, the support platform is overlain with a soft pad. The crush cell structure lies immediately beneath the platform which is secured in a horizontal orientation by snap fit pins which allows one side of the platform to be released from the trim panel and flipped up to a substantially vertical orientation upon outward deflection of the outer sloping panel. The crush cell structure which has its thin sheet material walls in a vertical orientation, is collapsed as the sloping outer panel is moved against the crush cell structure by contact with the occupant&#39;s body. 
   The crush cell structure is preferably comprised of a thin sheet material such as steel or aluminum formed into an opened ended closed shape, and with internal cells formed by webs or convolutions of the sheet material. Holes may be formed in the sheet material to more precisely achieve a desired crushing strength to absorb the impact energy while reducing the peak pressure forces imposed on the occupant&#39;s body to minimize injuries. 
   In another version of the crushable armrest, a thin-wall armrest cover molding is used instead of a flat armrest pad fastened to the trim panel. This molding, by being made of thin-walled material, is made to be easily crushable at low side impact loads. 
   The design of the crush cell structure allows for increasing stiffness at increasing distances to the rear so that crush loads going from the  5   th  percentile female occupant to 95 th  percentile male occupant are matched to the crush strength of the crush cell, thereby accommodating differing levels of abdominal injury thresholds. Openings in the crush cell walls can be formed at various locations to further help achieve the desired crush loads. 
   The cover molding is positioned close to the crush cell so that vertical loads applied on the armrest are transmitted to the crush cell which is very stiff in the vertical direction because of the vertical orientation of its walls construction. In a side impact, the impacting vehicle crushes the door outer panel and the armrest assembly easily crushes the lower torso region of the occupant makes contact with it. 
   In a modification of the armrest assembly, another version incorporates a “pull-cup” in the armrest cover molding. A separate door handle would not be necessary in this case. the pull cup is aligned with one of the cell openings in the crush cell. the armrest cover molding is still crushable; the “pull-cup” is crushed easily by the in-board and out-board walls surrounding it. 
   A pelvic crush cell structure may also be provided also comprised of a closed shaped formed of sheet material located behind the door panel located below the level at which the arm rest is disposed. 

   
     DESCRIPTION OF DRAWINGS 
       FIG. 1  is a transverse fragmentary sectional view taken through a motor vehicle door and an arm rest according to the present invention. 
       FIG. 2  is an enlarged sectional view of the arm rest shown in  FIG. 1 . 
       FIG. 3  is a pictorial view of a foam support bracket included in the arm rest shown in  FIGS. 1 and 2 . 
       FIG. 4  is a transverse sectional view through a second embodiment of an arm rest according to the invention with adjacent door structure and a partial outline in phantom lines of an occupant&#39;s body. 
       FIG. 5A  is a view of the arm rest shown in  FIG. 4  with the door to which it is attached in contact with a side impacting vehicle indicated diagrammatically. 
       FIG. 5B  is a transverse sectional view of the arm rest shown in  FIG. 5A  and adjacent door structure collapsed by a side impact. 
       FIG. 6  is a pictorial view of a vehicle door depicted in outline in phantom lanes and showing an armrest according to the invention with a door handle attached. 
       FIG. 7A  is a pictorial view of a vehicle door shown in outline in phantom lines with the crush cell included in the armrest shown in isolation. 
       FIG. 7B  is an enlarged pictorial view of a crush cell which may be incorporated in an armrest according to the invention. 
       FIG. 8A  is a diagrammatic view of the armrest shown in  FIG. 4  with the direction of the forces which may be applied to the arm rest assembly indicated with arrows. 
       FIG. 8B  is a pictorial view of another embodiment of an armrest assembly according to the present invention with adjacent door structure shown in phantom lines. 
       FIG. 8C  is a pictorial view of the armrest assembly shown in  FIG. 8B  with a cover molding removed to reveal the crush cell assemblage mounted therewithin. 
       FIG. 8D  is an endwise sectional view taken through the armrest assembly shown in  FIGS. 8B and 8C  with adjacent structure. 
       FIG. 8E  is a horizontal sectional view of the armrest assembly shown in  FIGS. 8B-8D . 
       FIG. 8F  is a pictorial view of a thin wall cover molding included in the armrest assembly showing  FIGS. 8B-8E . 
       FIG. 8G  is a side sectional view of the armrest assembly after side impact by a vehicle shown diagrammatically. 
       FIG. 8H  is a pictorial view of another version of the armrest assembly shown in  FIGS. 8B-8E  installed on a vehicle door. 
       FIG. 8I  is a side sectional view of the armrest assembly shown in  FIG. 8H  with adjacent door structure. 
       FIG. 8J  is a horizontal sectional top view of the armrest assembly shown in  FIGS. 8H and 8I . 
       FIG. 8K  is a pictorial view from the outside of a cover molding included in the armrest assembly shown in  FIGS. 8H-8J . 
       FIG. 8L  is a pictorial view from the inside of the cover molding shown in  FIG. 8K . 
       FIGS. 9A-9E  are top views of various configurations of the crush cells which may be incorporated in the arm rest according to the invention. 
       FIG. 10  is a pictorial view of the inside of a motor vehicle with a pelvic crush cell installed therein located below the level of an arm rest according to the invention. 
       FIGS. 11A and 11B  are pictorial views of two differing pelvic crush cells which may be provided in a motor vehicle door in combination with an arm rest assembly according to the invention. 
   

   DETAILED DESCRIPTION 
   In the following detailed description, certain specific terminology will be employed for the sake of clarity and a particular embodiment described in accordance with the requirements of 35 USC 112, but it is to be understood that the same is not intended to be limiting and should not be so construed inasmuch as the invention is capable of taking many forms and variations within the scope of the appended claims. 
   Referring to the drawings and particularly  FIG. 1  a fragmentary motor vehicle door  10  is depicted in simplified form with an exterior panel  12  and an interior panel  14 . 
   An arm rest assembly  16  according to the invention includes an upwardly and outwardly curving molded plastic trim panel  18  forming a ledge or step at a level convenient for resting the forearm of the vehicle occupant. Mounted atop that ledge is a support platform  20  having snap fit pins  22  inserted in an inwardly turned lip  24  on the trim panel  18 . 
   A second set of pins  26  are inserted in a trim strip  28  extending into the door inner panel  14 . 
   An L-shaped foam retention bracket  30  is disposed spaced below the platform  20 , with the intervening space filled with cushioning foam material  32 . 
   Disposed below the bracket  30  is a crush cell structure  34  attached along one side to the outside of the door inner panel  14  and the other side to the inside of the bracket  30 . 
   The bracket  30  has slots  36  extending along its length to allow lateral crushing at moderate loads. 
   The trim panel segment  18  may have a U-shaped preweakening notch pattern  19  to make lateral movement, as will be described, easier in a crash. The crush cell structure  34  is an open ended closed figure formed from sheet material into shapes such as seen in  FIGS. 7A ,  7 B, and  9 A- 9 E. 
     FIG. 4  depicts a preferred form of an arm rest assembly  38  in which an upwardly and inwardly extending trim panel section  40  forms a ledge an the inside of a vehicle door  42  at a level convenient for resting thereon of the elbow and forearm  44  of an occupant. 
   The ledge is covered with a cushioned pad  46  supported on a rigid platform  48  attached above one side with pins  50  which are snap fit into holes in an inturned lip  52  at the top edge of the trim panel  40 . The other side is attached with snap fit pins  54  inserted in a turned out edge of a trim strip  56  secured to the inner panel  58  of the door  42 . 
   The trim panel  40  may have a preweakening notch pattern  41  formed therein at a location intermediate its height to aid in bending thereof in a side impact event described below. 
   Mounted just below the platform  48  and in the space  60  formed between the door inner panel  58  and the inside of the trim panel  40  is a crush cell structure  62 , attached to door inner panel  58  with suitable fasteners  59 . 
   The crush cell  62  is preferably of a configuration shown in  FIGS. 7A and 7B  in which a thin sheet material (such as steel) is formed into a closed shape. A plurality of inner cells  64 ,  66  may be included as well as openings  60  to produce a desired crushing strength of the crush cell  62 . This configuration provides a predictable substantially uniform crushing resistance a substantial range of crushing collapse motion to be an effective energy absorber as described in the parent U.S. patent application as well as U.S. Pat. No. 7,128,339, incorporated by reference herein. 
     FIG. 5A  shows a side impacting vehicle diagrammatically  70 , in contact with an outer door panel  72 . An occupant torso is represented in outline at  45  and his or her forearm at  44 . 
   As the outer panel collapses, the trim panel  40  moves towards the inner door panel under pressure exerted by the occupant&#39;s torso. The platform  48  is tipping up to not present any resistance to collateral collapse of the remaining structure. The outward movement of the trim panel section  40  causes crushing of the crush cell structure  62  as shown, effectively absorbing energy without exerting injurious levels of pressure on the occupant&#39;s body. 
     FIG. 6  shows that the trim panel section  40  may be a sculpted section of the door inner panel, with a door handle  78  attached to the arm rest  38 . 
     FIG. 8A  shows that the arm rest assembly presents a stiffness in a vertical direction capable of supporting heavy loads, with the walls of the crushable cell structure  62  oriented for maximum stiffness to down loadings by being vertically oriented. 
   In the horizontal direction, the flip up action of the rigid platform  48 , the hinging action of the trim panel section  40 , and the predictable, substantially uniform crushability of the crush cell structure  62  provide energy absorption in the horizontal direction reducing peak pressure on the occupant&#39;s lower torso. 
     FIGS. 9A-9E  show various forms of the crush cell structure  62 A- 62 E. Crush cell structure  62 A (also shown in  FIG. 11A ) is formed from a single strip of sheet material (preferably steel) looped into a pair of inner cells  80  having parallel sides and with the parallel sides rounded at each end, with a larger cell  82  founded at one end formed when the inner cells  74  are abutted together to present a stiffer structure at one end. 
     FIG. 9B  shows a single cell crush cell structure  62 B formed of a strip of sheet material into parallel sides and rounded ends. 
     FIG. 9C  shows a crush cell structure  62 C with one large cell  84  and a larger inner cell  86 . 
     FIG. 9D  shows a crush cell structure  62 D with a pair of side by side cells  88  joined together. 
     FIG. 9E  shows a crush cell structure  62 E in which angled corners  90  of three cells create an accordion like individual cells for reduced crush resistance. 
   It should be understood that the crush resistance is a function of the material, the sheet thickness as well as the overall shape of the crush cell structures, and these may be adjusted to obtain a desired stiffness and crushability. 
     FIG. 10  shows a motor vehicle door  92  in which a pelvic crush cell structure  94  is installed against the outer door panel at a lower level than the armrest. The crush cell structure  94  may also be made of sheet metal formed into cells such as the channel shapes shown. The crush cell structure  62 D or other similar configurations may also be employed. 
     FIGS. 8B-8B  shows another variation of an armrest assembly according to the invention. This armrest assembly  100  includes a trim panel  102  shaped to produce a horizontal ledge  104 , with an upturned upper end  106  affixed to a door inner panel  108 . A cover molding  110  enclose a region above the ledge  104 , having a peripheral flange  112  abutting a flange  114  on the trim panel  102  extending around the ledge  104 . A hole can be cut into the ledge wall  118  allowing a crush cell structure  120  to be fixedly mounted in the space enclosed by the cover molding  110 . A cushioned pad  122  is mounted to the top of the cover molding  110 . 
   The cover molding  110  is designated to be crushable by horizontally applied forces by having thin walls (2 or 3 mm thick) of a suitable plastic such as vinyl. 
   The stiffness of the crush cell structure  120  in vertical directions reinforces the cover molding in that direction. 
   A handle  122  can be included attached to the armrest assembly  100  at an end and to the trim panel wall  106  at the other end. 
     FIG. 8E  shows that the crush cell structure  120  can be made stiffer at its rear end by including more interval cells at the rear end. This creates better matching to the 5 th  percentile female A, the 50 th  percentile male B and the 95 th  percentile male C. 
     FIG. 8G  shows a impact induced collapse of the armrest assembly  100  with the cover molding  110 , crush cell structure  124  and trim panel  102  all flattened towards the door inner panel  108 . 
     FIGS. 8I-8L  show a variation in which a pull cup  126  is formed into the cover molding  110 A which is attached to the trim panel  102 . The pull cup  126  is formed integrally with the molding cover  110 A and projects downwardly where it is aligned with one of the inner cells  126  to be received therein. This eliminates the need for a separate handle  122 .