Abstract:
An armrest adapted to be mounted to a vehicle door comprises a primary substrate adapted to be mounted to a vehicle door panel with a secondary substrate mounted to the primary substrate and defining a recess. A foam layer is mounted to the secondary substrate within the recess, and a flexible outer casing intergrally molded to the primary substrate forming a recess with the primary substrate which receives the secondary substrate and the foam layer. A method of fabricating the armrest for the vehicle door is also provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. patent application Ser. No. 60/099,649, filed on Sep. 9, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a vehicular armrest, and more particularly, to an armrest having a structural substrate, a vinyl or flexible polyolefin covering and a foam filling between the substrate, secondary substrate  14  and cover and the vinyl covering. The invention also relates to a process for fabricating the vehicular armrest. 
     2. Related Art 
     Armrests filled with polyurethane foam resins have been mounted on vehicle doors for many years. An example of a prior art armrest  110  is shown in FIG. 1 comprising a structural plastic or metal internal support  112  having a substrate surface  120 , a vinyl or flexible polyolefin outer cover  118  and a polyurethane or similar foam filling  146  enclosed within the internal support  112  and cover  118  by a panel  114 . 
     While such conventional foam materials have been readily utilized in the industry, problems have been identified with respect to, among other things, the consistency of their reaction profiles. For example, armrests  110  are conventionally filled with a two-part polyurethane foam. Polyurethanes are generically prepared by nucleophilic addition of alcohols to isocyanates. Foaming occurs when a small amount of water is added to the two chemical reagents during polymerization. Specifically, water adds to the isocyanate groups providing carbamic acids, which spontaneously lose carbon dioxide, thus generating bubbles and, in turn, foam within the curing polymer. 
     When the polyurethane foam  146  is poured into the armrest  110  during the initial stages of polymerization the reagents are still susceptible to parameter changes such as atmospheric moisture (humidity), temperature, and pressure changes. These parameter changes can have a substantially adverse impact upon the consistency of the resulting foam  146  from day to day or even batch to batch. Furthermore, according to conventional methods, after the two-part polyurethane foam  146  has been poured and cured, copious quantities of scrap remain, which requires additional time and labor to clean up and, in turn, adds to the cost of production. Moreover, the disposal of the scraps and byproducts from synthesizing polyurethanes can be costly. 
     In addition, due to the complexity, smell, and messiness of preparing polyurethane foams, it is typically not practical for the armrest  110  to be assembled in one location as the preparation of the foam  146  requires and additional, separate work station which further adds to the cost of manufacturing. Further, the polyurethane foams  146  are not recyclable and thus the armrests  110  are not recyclable when the automobile is eventually scrapped. 
     SUMMARY OF THE INVENTION 
     In one aspect, the invention relates to an armrest adapted to be mounted to a vehicle door comprising a primary substrate adapted to be mounted to a vehicle door panel and a secondary substrate mounted to the primary substrate and defining a recess. A foam layer is mounted to the secondary substrate within the recess, and a flexible outer casing is integrally molded to the primary substrate forming a recess with the primary substrate which receives the secondary substrate and the foam layer. 
     The primary substrate and the secondary substrate can be formed of a thermoplastic material and the secondary substrate is heat fuised to the primary substrate. The heat fusing can comprise heat staking. The foam layer can be adhesively secured to the secondary substrate. The foam layer can be unsecured to the flexible outer casing. The flexible outer casing can be a molded thermoplastic material. The molded thermoplastic material can comprise a vinyl resin. The secondary substrate can have a depending flange with an opening and the primary substrate can have an alignment tab positioned in the opening. The secondary substrate can have a second opening and the primary substrate can be heat staked to the secondary substrate through the second opening. The secondary substrate can have at least one depending locator pin and the primary substrate can have at least one opening which receives the at least one depending locator pin. The secondary substrate can have a wedge-shaped platform which has an upper surface which receives the foam layer. The foam layer can have a substantially uniform thickness. The foam layer can be formed of a vinyl resin which is die cut. The secondary substrate can have a generally vertical wall with at least one flange extending rearwardly therefrom, wherein the at least one flange is adapted to locate the armrest in an opening on a vehicle door. The components of the armrest can be formed from recyclable materials. The primary substrate can have a flexible depending detent arm adapted to locate the armrest within an opening on a vehicle door. The outer casing can have a tab on an interior surface thereof which extends between a portion of the primary substrate and the secondary substrate whereby the tab wedges between the substrates and reduces vibratory noise therebetween. 
     In another aspect, the invention relates to a method of fabricating an armrest for a vehicle door comprising the steps of forming a primary substrate adapted to be mounted to a vehicle door panel; intergrally molding a flexible outer casing to the primary substrate and forming a recess therewith; forming a secondary substrate having a mounting platform with a shape adapted to occupy a lower portion of the recess; forming a foam layer having a shape adapted to occupy the remainder of the recess between the mounting platform and the outer casing; mounting the foam layer to the mounting platform of the secondary substrate; and inserting the assembly of the foam layer and the secondary substrate into the recess defined by the primary substrate and the outer casing. 
     The elements produced by the above method can have the features described above with respect to the armrest. Further, the method can include the steps of heat fusing and/or heat staking the secondary substrate to the primary substrate; mounting the foam layer to the secondary substrate and adhesively securing the foam layer to the secondary substrate; inserting a portion of the primary substrate into a portion of the secondary substrate to align the primary and secondary substrates with respect to one another; heat fusing the primary substrate to the secondary substrate; heat staking the primary substrate to the secondary substrate through an opening in the secondary substrate; inserting at least one depending locator pin on the secondary substrate into at least one opening in the primary substrate; and die cutting the foam layer. 
     The mounting platform can have a wedge shape from a rear portion to a front portion thereof for facilitating the step of inserting the assembly of the foam layer and the secondary substrate into the recess defined by the primary substrate and the outer casing. The foam layer can have a substantially uniform thickness. 
     Other objects, features, and advantages of the invention will be apparent from the ensuing description in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     The invention will now be described with reference to the drawings wherein: 
     FIG. 1 is a cross-sectional view of a prior art armrest filled with a two-part polyurethane foam; 
     FIG. 2 is an exploded perspective view of a first embodiment of an armrest in accordance with the present invention utilizing a die-cut vinyl nitrile or polyolefin-based foam; 
     FIG. 3 is a cross-sectional view of the armrest of FIG. 2 taken along lines  3 — 3 ; 
     FIG. 3A is a cross-sectional view of a first embodiment of a mounting post employed with the armrest of FIG. 1 taken along lines  3 A— 3 A of FIG. 3; 
     FIG. 3B is a cross-sectional view of a second embodiment of the mounting post employed with the armrest of FIGS. 2-3; 
     FIG. 3C is a cross-sectional view like FIG. 3A taken along lines  3 C— 3 C of FIG. 3B; 
     FIG. 4 is an exploded perspective view of a vehicle door being assembled with an armrest in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings and to FIG. 2 in particular, a first embodiment of an armrest  10  is shown which generally comprises a primary substrate  12 , a secondary substrate  14 , a die-cut foam filler  16 , and an outer casing  18 . 
     As best shown in FIGS. 2-3, the primary substrate  12  provides for the general structure and contour of the armrest  10 , and can be configured in any one of a number of shapes. The primary substrate  12  includes a substantially planar ridge  20  for receiving the secondary substrate  14 . The primary substrate  12  further includes an alignment tab  22  which emanates outwardly from the planar ridge  20  and which is received, upon assembly, by a slot  24  of the secondary substrate  14  to facilitate proper transverse alignment between the primary and secondary substrates  12  and  14 . 
     The primary substrate  12  further includes an L-shaped member  26  emanating substantially outwardly and downwardly proximate the lower surface of the planar ridge  20 . The L-shaped member  26  is used in two capacities. First, the L-shaped member  26  is used to align the armrest  10  with an aperture of a vehicle door  44  (shown in FIG.  4 ). Second, the L-shaped member  26  adds stability to the armrest  10 , once the armrest  10  is secured to the door  44 . 
     Moreover, the primary substrate  12  includes a plurality of fastener receivers  28  for receiving fasteners, such as, but by no means limited to, threaded screws to, in turn, secure the armrest  10  to the door of a vehicle. The fastener receivers  28  are shown by example in FIG. 2 as comprising a molded cylindrical boss having a longitudinal threaded bore therein. 
     The primary substrate  12  is preferably fabricated from glass filled polypropylene. However, any one of a number of materials can be used to fabricate the primary substrate  12  including, but by no means limited to wood, steel and various metallic alloys, and numerous other synthetic resin compounds. Of course, the precise fabrication materials used will depend upon the particular qualities desired such as price, weight, strength, durability, or any combination thereof. 
     The secondary substrate  14 , as shown in FIGS. 2-3, comprises a generally vertical cover  30  having a slot  24  adapted to receive the tab  22  of the primary substrate  12  upon assembly. In addition, the vertical cover  30  has a second slot  34  adapted to receive a heat-staking tool upon final assembly of the armrest  10  to mount the secondary substrate  14  to the primary substrate  12 . As best shown in FIG. 3, the vertical cover  30  preferably has a locking groove  50  adjacent an upper edge thereof which creates a channel to secure outer casing  18  thereto—which has a casing bead  52  adapted to snap-fit within the locking groove  50 . This locking feature prevents the outer casing  18  from distorting when mounted in abutment to the door panel  44 . 
     A mounting platform  32  emanates substantially perpendicular from the generally vertical cover  30 . The mounting platform  32  is generally planar and geometrically conforms to the planar ridge  20  of the primary substrate  12 . As shown in FIG. 3, the mounting platform  32  preferably has a tapering wedge-shaped cross-section. 
     The mounting panel  32  of the vertical cover  30  also preferably includes a number of locators  48  which facilitate proper alignment between the primary substrate  12  and the secondary substrate  14 . The locators  48  accurately position the secondary substrate  14  with respect to the primary substrate  12  for different vehicles and to lock the secondary substrate thereto after assembly. The locators  48  can be integrally molded with the L-shaped member  26  as desired when design constraints permit. 
     FIGS. 3-3A show a first embodiment of the locator  48  in detail comprising a cylindrical member  48   a  having a ramped distal surface  48   b  thereon. FIGS. 3B-3C show a second embodiment of a locator  48 ′ in detail comprising an elongated member  48   c  having an elliptical or rounded rectangular cross section and also having a ramped surface  48   d  thereon. 
     The secondary substrate  14  is preferably fabricated from acrylonitrile butadiene styrene (ABS) polymers or a polyolefin-based resin. However, any one of a number of materials can be used to fabricate the secondary substrate  14  including, but by no means limited to wood, steel and various metal alloys, and numerous other synthetic resin compounds. 
     The foam filler  16  provides a “spongy” feel to an occupant who places his/her arm upon the armrest  10 . The foam filler  16  includes an upper surface  36  and a lower surface  38 . Applied to the lower surface  38  of the foam filler  16  is a conventional pressure sensitive adhesive. Prior to final assembly, the adhesive is protected with a paperboard covering  40 . The surface of the paperboard covering  40  that contacts the pressure sensitive adhesive is coated with a conventional material to preclude adhesion between the foam filler  16  and the paperboard covering  40 . While the pressure sensitive adhesive has been disclosed as applied to the foam filler  16 , for illustrative purposes only, it is likewise contemplated that the adhesive can be applied to the mounting platform  32  of the secondary substrate  14 . 
     The foam filler  16  is preferably die-cut to conform to the geometric configuration of both the mounting platform  32  of the secondary substrate  14  as well as the planar ridge  20  of the primary substrate  12 . The foam filler  16  is preferably fabricated from vinyl nitrile resins. However, any one of a number of polymeric resins, such as EPDM, polypropylene, polyethylene, etc., are likewise suitable for use. The vinyl nitrile resins are preferred for at least two reasons. First, the vinyl nitrile cured resins are ideal for conventional die-cutting. As such, all components of the armrest can be collected and assembled in one final assembly location which, in turn, reduces the cost of production. Second, the vinyl nitrile cured resins result in a foam that is especially spongy which gives the armrest a softer feel when a occupant rests his/her arm upon the region having such a foam filler. 
     The outer casing  18  is molded to generally conform the geometric configuration of the primary and secondary substrates  12  and  14  collectively—when assembled. The outer casing  18  is preferably fabricated from polyvinyl chloride (PVC). However, any one of a number of conventional casing materials are likewise contemplated for use including known thermoplastic polyolefin-based elastomers, for example. 
     As best shown in FIG. 3, the outer casing  18  is also provided with an outer tab  54  which extends inwardly therefrom to nest between the primary substrate  12  and an outer edge of the secondary substrate  14 . The outer tab  52  effectively functions as a wedge between the primary and secondary substrates  12  and  14  and the outer casing  18  to prevent noise from being generated within the armrest  10  during use as a result of vibration of the vehicle. 
     As will be readily apparent from the description below, the armrest  10  in accordance to the present invention is suitable for final assembly in one location using only a limited number of nominal manual steps. 
     To initiate assembly of the armrest  10 , the primary substrate  12  is placed in a mold conforming to the geometric configuration of the outer casing  18 . The outer casing  18  is then applied over the primary substrate  12  by injecting outer cover material into the mold. Such a process is conventionally known as “insert molding” or “over molding.” As best shown in FIG. 2, once the outer cover material is cured, the partially fabricated armrest includes a channel  42  for receiving both the secondary substrate  14  and the foam filler  16 . 
     Upon further assembly, the paperboard covering  40  of the foam filler  16  is removed thus exposing the pressure sensitive adhesive which is applied to the lower surface  38  of the foam filler  16 . Once the paperboard material  40  is removed, the lower surface  38  having the pressure sensitive adhesive, is fixedly applied to the upper surface of the platform  32  of the secondary substrate  14 . Next the secondary substrate  14 , with the applied foam filler  16 , is inserted into the channel  42 . To assure proper alignment, the slot  24  of the secondary substrate  14  receives the tab  22  of the primary substrate  12  upon such an insertion. 
     In addition, the locators  48  on the secondary substrate  14  can be positioned within corresponding apertures or openings in the primary substrate for further location assistance between the two substrates  12  and  14 . The ramped surface  48   b  on the locators assist insertion of the locators  48  within the openings in the primary substrate  12  by allowing the secondary substrate  14  to slide relative to the primary substrate  12  in an angular fashion and then allowing pivoting to an abutted relationship when the proper alignment is obtained. 
     After the secondary substrate  14  is fully inserted into the channel  42 , assembly of the armrest  10  is completed by fusing together the primary and secondary substrates  12  and  14 , respectively. Fusion of the two substrates is preferably accomplished by inserting a conventional heat staking tool into and through the slot  34  of the secondary substrate  14  thereby contacting a portion of both the primary and secondary substrates  12  and  14 , respectively, and, in turn, fusing the two substrates  12  and  14  together. While conventional heat staking has been described herein, for illustrative purposes only, any one of a number of “fusing” and/or “sealing” procedures known to those having ordinary skill in the art are likewise contemplated for use. Attachment could also be accomplished via screws, rivets, adhesives etc. 
     As shown in FIG. 3, upon complete assembly of the armrest  10 , the die-cut foam filler  16  is wedged between the secondary substrate  14  and the outer casing  18 . The die-cut foam filler  16  does not contact the planar ridge  20  of the primary substrate  12 . In comparison with the prior art armrest assembly shown in FIG. 1, [a] the fully assembled prior art armrest thereof (utilizing a poured polyurethane filler  146 ) does, indeed, contact the planar ridge  120  of the primary substrate  112 . 
     As shown in FIGS. 3-4, after the armrest  10  of the present invention is fully assembled, it is then ready for attachment to a door  44  of a conventional vehicle. To attach the armrest  10  to the vehicle door  44 , a plurality of fasteners are fixedly received into the fastener receivers  28  of the primary substrate  12 . Further, to increase the location and appearance of the armrest  10  when it is mounted to the vehicle door  44 , the primary substrate  12  can be provided with a reversely-extending blade  56  which has a depending detent arm  58  thereon. The detent arm  58  is adapted to engage within an opening on the vehicle door  44  and is preferably biased to draw the armrest  10  and vehicle door  44  together. In this manner, the detent arm  58  on the blade  56  is used to control the appearance gap of the armrest  10  relative to an exterior panel of the vehicle door  44  by acting as vertical locator of the armrest  10  to the door  44 . The detent arm  58  also assists the assembly of the armrest  10 —for example, the detent arms  58  on the blade  56  can be temporarily mounted to an arm on a manufacturing assembly to allow the armrest  10  to be easily handled prior to fusing the substrates  12  and  14  together at the assembly plant. 
     It should also be noted that where a flexible polyolefin-based outer cover is used in conjunction with a polyolefin-based foam  16  and primary and secondary substrates  12  and  14 , the resultant armrest  10  assembly is completely recyclable. This is due to the compatibility of the components making up the armrest  10 . Thus, even if the armrest  10  is scrapped after its useful lifetime, the components  12 - 16  of the armrest  10  can be recycled. 
     While particular embodiments of the invention have been shown, it will be understood, of course, that the invention is not limited thereto since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. Reasonable variation and modifications are possible within the scope of the foregoing disclosure of the invention without departing from the spirit of the invention.