Abstract:
An armrest is provided including a flexible skin overlying at least a portion of a substrate member, the skin coupled to substrate member, the flexible skin and the substrate member defining a cavity there between and an opening along one edge, and a foam bun insertable in the cavity to form the armrest, wherein the foam bun comprises a first foam portion which the flexible skin overlies and a second foam carrier portion which closes off the opening. The first foam portion has a hardness that is less than the hardness of said second foam carrier portion, the foam bun further including an integrally formed locking flange to engage with an edge of the substrate and an integrally formed skin lock to engage with an edge of the skin.

Description:
FIELD 
     The present disclosure relates to armrests of the type that have a foam bun inserted therein for cushioning an arm-supporting surface, and more specifically, an insertable armrest bun comprising one or more foam portions of different hardness. 
     BACKGROUND 
     U.S. Pat. No. 6,213,538 relates to an armrest and method for manufacturing the same. The &#39;538 patent discloses an armrest bun comprising a die-cut foam pad adhered to a plastic substrate. The substrate and foam are inserted within the armrest skin to provide cushioning for the occupants of a vehicle. 
     Armrests are manufactured in many and various sizes and shapes for all sorts of transportation vehicles as well as for furniture. In the past, armrests were generally rectangular in shape to simplify manufacturing. The trend in newer vehicles now includes complex curvatures and tapered surfaces. This new more curved shaping may be more aesthetically appealing and may provide better comfort by conforming more closely to the shape of the portion of the arm that may be cushioned. 
     The foam comprising the armrest bun may closely match the outer shape of the armrest and fully support the outer skin so that wrinkles and depressions are not seen. 
     A problem relates to the shaping of the die-cut foam, such as disclosed by the &#39;538 patent, to properly fit the more curved armrests of today. Providing a die-cut foam bun having the desired shaping, which may include complex curvatures and tapered surfaces, may require a number of cutting operations. Multiple workstations may be required to focus on the cutting of the different and varied surfaces. For instance, one station may be needed to cut a blank, another station may be needed to cut a curve on the blank, and yet another station may be needed to cut a taper on the blank, all in a less than desirable cost effective manner. 
     Armrests were manufactured as a separate component for many years, and comprised a formed metal or plastic substrate, a separately molded outer skin and urethane foam precursors poured between the skin and substrate which expanded and cured to form a semi-rigid cushioning foam. This component was then mechanically attached to, for instance, the inner door panel of a vehicle. 
     More recently, a more efficient manufacturing process has been developed wherein the outer skin and substrate may both be injection molded by “insert-molding” or “over-molding” such that a pocket or cavity is created, into which a foam bun may be inserted to form the armrest. 
     U.S. Pat. No. 7,055,888, commonly owned by the assignee of the present disclosure is directed at a skin coupled to a first substrate that forms a cavity for inserting a foam bun into, the bun comprising a second substrate and a foam layer bonded to the second substrate. The first and second substrates are connectable to position the armrest on a door panel. 
     The present disclosure provides a less complex, more cost effective assembly by eliminating the second substrate or replacing the second substrate with a second relatively harder foam that may be formed coincident with the relatively softer foam bun. Accordingly, a more cost-effective method for manufacturing insertable armrest buns is provided. 
     SUMMARY 
     An armrest comprising a flexible skin having a plurality of edges and overlying at least a portion of a substrate member having a plurality of edges, the skin coupled to the substrate member along at least one common edge, the flexible skin and the substrate member defining a cavity there between having an opening along an edge. A foam bun is contained within the cavity, the foam bun insertable in the cavity to form the armrest and close said opening wherein the foam bun comprises a first cushioning foam portion which the flexible skin overlies and a second carrier foam portion which closes off the opening. The first cushioning foam portion has a hardness that is less than the hardness of the second carrier foam portion and the foam bun further including an integrally formed locking flange to engage with an edge of the substrate and an integrally formed skin lock to engage with an edge of the skin. 
     An armrest comprising a flexible skin having a plurality of edges and overlying at least a portion of a substrate member having a plurality of edges, the skin coupled to said substrate member along at least one common edge, the flexible skin and the substrate member defining a cavity there between having an opening along an edge and a foam bun contained within the cavity, the foam bun insertable in the cavity to form the armrest and close said opening. The foam bun comprises a cushioning foam portion which the flexible skin overlies and which closes off the opening, the foam bun further including an integrally formed locking flange to engage with an edge of said substrate and an integrally formed skin lock to engage with an edge of the skin. 
     An automotive door trim assembly comprising an interior trim door panel and an armrest attached to the door panel, the armrest comprising a flexible skin having a plurality of edges and overlying at least a portion of a substrate member having a plurality of edges, the skin coupled to the substrate member along at least one common edge, the flexible skin and the substrate member defining a cavity there between having an opening along an edge. A foam bun is contained within the cavity, the foam bun insertable in the cavity to form the armrest and close the opening; the foam bun formed by over-molding wherein the foam bun comprises a first cushioning foam portion which said flexible skin overlies and a second carrier foam portion which closes off the opening. 
     The first cushioning foam portion has a hardness that is less than the hardness of the second carrier foam portion and the foam bun further includes an integrally formed locking flange to engage with an edge of the substrate and an integrally formed skin lock to engage with an edge of the skin. 
     A method for forming an armrest, comprising providing a flexible skin having a plurality of edges, providing a substrate member having a plurality of edges, coupling the skin to the substrate along at least one common edge, such that the skin overlies at least a portion of the substrate member, the flexible skin and the substrate member defining a cavity there between having an opening along an edge. This is followed by providing a foam bun to be contained within the cavity, the foam bun insertable in the cavity to form the armrest and close the opening; wherein the foam bun is formed by over-molding a second carrier foam portion over a first cushioning foam portion and inserting the foam bun into the cavity. The flexible skin overlies the first cushioning foam portion and the second carrier foam portion closes off the opening. This is followed by engaging an integrally formed locking flange on the bun to an edge of the substrate and engaging an integrally formed skin lock on the bun with an edge of the skin wherein the first foam portion has a hardness that is less than the hardness of the second foam carrier portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features, operation and advantages of the invention may be better understood from the following detailed description of the preferred embodiments taken in conjunction with the attached drawings, in which 
         FIG. 1  illustrates a door assembly in accordance with the present disclosure; 
         FIG. 2  illustrates a cross-sectional view of an armrest shown in  FIG. 1  along the line  2 - 2 ; 
         FIG. 3  illustrates a cross-sectional view of the armrest bun of  FIG. 1  in accordance with a first embodiment the present disclosure; 
         FIG. 4  illustrates a cross-sectional view of the armrest bun of  FIG. 1  in accordance with a second embodiment of the present invention; 
         FIG. 5  illustrates a cross-sectional view of the armrest bun of  FIG. 1  in accordance with a third embodiment of the present invention; and 
         FIG. 6  is a process diagram for the molding of one embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Various features of the present invention will now become readily apparent to those skilled in the art from the following detailed description, wherein the invention is shown along with certain preferred embodiments. As will be realized the invention is capable of other and different embodiments, and its several details are capable of modification in various respects. Accordingly, the description is to be regarded as illustrative in nature and not as restrictive. 
       FIG. 1  illustrates a vehicle door assembly  10  in accordance with the present disclosure. The door assembly  10  includes an armrest  14  such as commonly used in automotive vehicles. The present invention is not limited to the embodiment shown in  FIG. 1 . The present invention contemplates a number of embodiments, including non-automotive applications, such as boats, trains, planes, furniture and the like. 
     The armrest  14  attaches to a door panel  18  of the vehicle by a fastener or other means to provide a resting location for the arm of an occupant in such vehicle. The armrest  14  may include an arcuate or curved upper surface and a tapered shape to provide an aesthetically appealing, comfortable and safe armrest. The curvature and taper define an outward appearance shape for the armrest  14 . Other shapes and configurations may also be used without deviating from the scope and contemplation of the present invention. 
     The armrest  14  may include an armrest bun  22  which may be inserted within a cavity  24  of the armrest  14  formed by the coupling of a skin layer  26  and a substrate  30  to provide cushioning thereto, as shown in  FIG. 2 . The armrest bun  22  may be inserted at a rearward end  28  of the cavity  24  which ultimately lies adjacent the door panel  18 . The present disclosure contemplates alternative designs that may include one or more buns that may be inserted at different areas on the armrest  14 . 
       FIG. 2  illustrates a cross-sectional view of the armrest  14  shown in  FIG. 1  taken along line  2 - 2 . The armrest  14  includes an outer skin  26  that covers the top surface of the inserted bun and is attached to a substrate  30 . The outer skin  26  may be molded to or separately attached to the substrate  30 . The substrate  30  and skin  26  may both be injection molded by “insert-molding” or “over-molding” such that one or more of the common edges (for instance  32  in  FIG. 2 ) of the skin and substrate are joined together during the melt processing of one of the materials forming the skin or substrate. In this manner, a pocket or cavity  24  is created, into which a foam bun  22  may be inserted. 
     The outer skin  26  may comprise a flexible material to facilitate its comfort and appearance, including, but not limited to, polyvinyl chloride (PVC), PVC/ABS (acrylonitrile-butadiene-styrene) blends, PVC/cross-linked olefin-based thermoplastic elastomer alloys, thermoplastic urethane (TPU), thermoset urethane, themoplastic polyolefin (TPO), thermoplastic elastomer (TPE), styrene block copolymers, and combinations there of. 
     The substrate  30  may comprise a plastic, as such ABS, PC (polycarbonate)/ABS, polypropylene (PP), wood fiber composites, such as woodstock or lignatock, metal, or other similar relatively rigid materials. 
     The outer skin  26  may also be mechanically or adhesively joined to the substrate  30  along one or more common edges. The substrate  30  may include an angled flange  42  to secure the armrest  14  to the door panel  18 , generally in a shelf area of the door panel. The angled flange  42  may be inserted through an opening  44  in the door panel during assembly. The angled flange  42  may be pulled by a fastener  48  to connect the substrate  30  during installation of the armrest  14  to force the armrest  14  against the door panel  18 , thereby minimizing gap formation between the outer skin  26  and the door panel  18 . 
     The armrest bun  22  in a first exemplary embodiment may include a carrier portion  50  and a cushioning portion  56  as shown in  FIG. 3 . The carrier portion  50  may be integrally molded to the cushioning portion  56  during the molding process and then inserted within the armrest cavity  24  defined by the substrate  30  and the outer skin  26 . The cushioning portion  56  may be shaped to match the desired outer contour of the armrest  14  so that it snugly fits within the armrest cavity and against the skin  26  and provides relatively even support throughout so that most, if not all, of the skin  26  is supported by the foam bun  22 . 
       FIG. 3  illustrates a cross-sectional view of the armrest bun of  FIG. 1  in accordance with a first embodiment of the present disclosure. The bun  22  comprises two portions, a carrier portion  50  for handling and positioning and a relatively softer cushioning portion  56  for supporting the skin  26  and for cushioning the arm of an occupant of the vehicle. The carrier portion  50  further includes a locking flange  60  which may engage with an end of the substrate  30  as shown in  FIG. 2  to lock the bun  22  into position on the door panel  18 . The carrier portion  50  also includes a skin lock  80  for locking the skin edge  20  of the cavity  24  to close out the armrest and secure the skin edge  20  in a substantially net condition against the surface of the door panel  18 . 
     In this embodiment, the armrest bun  22  may comprise a molded foam having portions of two different hardnesses and may be formed of any foamable polymer, for instance polyurethane, polyolefin, silicone, etc. 
       FIG. 6  provides a sequence of process steps. Preferably, the bun is formed by pouring or injecting liquid urethane precursors for a relatively softer cushioning foam into a closed mold cavity, allowing the precursors to expand and cure to form a first molded cushioning portion  56  (BLOCK  100 ), and then replacing the mold cover with a second cover having a second cavity therein that is placed adjacent the first molded cushioning portion  56  (BLOCK  200 ). A second set of liquid urethane precursors for a second relatively harder foam are then poured or injected into the second cavity (BLOCK  300 ) and against the first molded cushioning portion  56  and allowed to expand and cure to form the carrier portion  50 , adhered to the cushioning portion  56  (BLOCK  400 ). In this embodiment, the skin lock  80  and locking flange  60  are formed of the second, relatively harder foam  50 . 
     The first molded cushioning foam portion  56  may specifically have a hardness of 8.5+/−3 lbs. as an Indentation Load Deflection value measured according to General Motors Test Procedure 6084M, using a 38 mm diameter hemisphere indenter pressed into the bun at 38.1 mm/minute to a depth of two-thirds of the bun thickness with a 5 second dwell. The carrier portion  56  may have a hardness of 20+/−3 lbs. as an Indentation Load Deflection value measured according to General Motors Test Procedure 6084M, using a 38 mm diameter hemisphere indenter pressed into the bun at 38.1 mm/minute to a depth of two-thirds of the bun thickness with a 5 second dwell. In this embodiment, the carrier foam portion  50  is over-molded against the cushioning portion  50  and forms the end of the foam bun  22  that closes out the opening  28  in the cavity  24  formed by the skin and substrate. 
     In a second exemplary embodiment, as shown in  FIG. 4 , the relatively harder carrier foam portion  50  may be molded to extend under the relatively softer cushioning foam portion  56  for some or all of its length and width, that is, along two or more of the sides or ends of the softer foam portion  56 . The configuration shown in  FIG. 4  may ease the difficulty in inserting the foam bun  22  into the cavity  24  formed by the skin  26  and substrate  30 , as the harder carrier foam  50  that extends along the bottom of the bun  22  may provide a somewhat stiffer bun that may not be as prone to wrinkling of the cushioning foam  56  during insertion. 
     In a third exemplary embodiment, as shown in  FIG. 5 , the relatively harder carrier foam portion  50  may be eliminated and the entire foam bun  22  molded of the relatively softer cushioning foam  56  (BLOCK  100  in  FIG. 6 ). 
     It is contemplated that for any of the three embodiments that a relatively porous reinforcing material  70 , as shown in  FIG. 2 , such as cloth, webbing, shelf liner, etc. may be molded in place, that is integrally formed, in the area of the skin lock and locking flange to provide additional strength. 
     The integrally formed locking flange  60  may include a groove into which the substrate  30  may fit proximate the opening  28  of the armrest cavity  24  to position the bun  22  thereto. The flange may further include detents or other features to provide a friction fit. The substrate may include an aperture to receive such detent and secure the bun  22  to the substrate  30 . 
     The carrier portion  50 , or  56  in the case of the third embodiment, may include an integrally formed skin lock  80  in the form of an undercut for receiving a lip or edge  20  of the outer skin  26 . The skin lock  80  may position the outer skin  26  adjacent the door panel  18 . The skin lock  80  may also limit the edge of the outer skin  26  from flexing away from door panel  18 . Preferably, the outer skin  26  is stretched slightly to fit over the skin lock  80  and pull the skin  26  into a relatively taut condition. 
     “Integrally formed” as used herein refers to the formation of a feature (e.g. groove, reinforcement, etc.) in a molded part that is formed coincident with the formation of the molded part and not added subsequent to the forming of the molded part. 
     While particular embodiments of the present disclosure have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the disclosure. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this disclosure.