Abstract:
An armrest for a captain&#39;s chair of a vehicle includes an outer layer and an inner layer including a foaming agent and defining a hollow core. At least one of the inner layer and the outer layer may include a reinforcing material and/or may be varied in thickness along its length. The armrest may include a third layer defining the hollow core. A related method includes heating a parison having a first and second layers, mixing a foaming agent into the second layer prior to heating, feeding the heated parison between mold halves, clamping the heated parison by moving the mold halves together, and pushing the layers of the heated parison outward, using blown air, such that the first layer is adjacent the mold and the second layer forms a hollow core of the armrest, the hollow core being partially filled by expansion of the second layer during cooling.

Description:
TECHNICAL FIELD 
       [0001]    This document relates generally to parts used in a vehicle, and more specifically to a multilayered armrest, used with a captain&#39;s seat, and a bumper of a vehicle. 
       BACKGROUND 
       [0002]    Armrests, for example, are a common component of captain&#39;s chairs in vehicles. Current captain&#39;s chair armrests are produced by many methods. One piece injection molded armrests generally have an open lower surface that includes a plurality of sharp edges which could cause harm during an impact event. Two piece injection molded armrests may alleviate the issue of sharp edges, but require the pieces to be positioned together (snapped or otherwise) and secured with fasteners such as screws. For this and other reasons, two piece injection molded armrests are also relatively expensive to manufacture. A steel stamped armrest molded in foam is yet another means of manufacturing an armrest. Steel stamped armrests, however, are generally heavy and are therefore less desirable. Accordingly, a need exists for an armrest for a captain&#39;s chair that is lightweight, formed as a unitary piece, and minimizes, if not eliminates, any sharp edges. 
         [0003]    This document relates to parts used in a vehicle including an armrest for a captain&#39;s chair and a bumper that are extruded from a multi-layer parison to form a lightweight, unitary, and structurally significant piece that minimizes, if not eliminates, any sharp edges. 
       SUMMARY 
       [0004]    In accordance with the purposes and benefits described herein, an armrest for a captain&#39;s chair of a vehicle is provided. The armrest may be broadly described as comprising an outer layer and an inner layer defining a hollow core. 
         [0005]    In one possible embodiment, at least one of the inner layer and the outer layer includes a reinforcing material. In another, at least one of the inner layer and the outer layer is varied in thickness along its length. In still another possible embodiment, the hollow core is partitioned. 
         [0006]    In yet another possible embodiment, the inner layer includes a plastic and a foaming agent. 
         [0007]    In another possible embodiment, an armrest for a captain&#39;s seat for a vehicle includes an outer layer, an intermediate foam layer, and an inner layer defining a hollow core. 
         [0008]    In still another possible embodiment, at least one of the inner layer, the intermediate foam layer, and the outer layer includes a reinforcing material. In another, at least one of the inner layer, the intermediate layer, and the outer layer is varied in thickness along its length. In yet another, the hollow core is partitioned. 
         [0009]    In still another possible embodiment, the inner layer includes a plastic and a foaming agent. 
         [0010]    In other possible embodiments, the armrests described above are incorporated into a vehicle. 
         [0011]    In accordance with still another possible embodiment, a bumper for a vehicle is provided. The bumper may be broadly described as comprising an outer layer and an inner layer defining a hollow core. At least one of the inner layer and the outer layer may include a reinforcing material. In another possible embodiment, at least one of the inner layer and the outer layer is varied in thickness along its length. In still another possible embodiment, the hollow core is partitioned and the inside layers may be fused together for stiffness. In yet another possible embodiment, the inner layer may include a plastic and a foaming agent. 
         [0012]    In another, a bumper may include an outer layer, an intermediate foam layer, and an inner layer defining a hollow core. At least one of the inner layer, the intermediate foam layer, and the outer layer may include a reinforcing material. In another, at least one of the inner layer, the intermediate layer, and the outer layer may be varied in thickness along its length. In yet another, the hollow core is partitioned and the inside layers may be fused together for stiffness. 
         [0013]    In accordance with another aspect, a method of forming an armrest for a captain&#39;s seat of a vehicle is provided. The method may be broadly described as comprising the steps of: (a) forming a parison having a first layer and a second layer; (b) mixing a foaming agent into the second layer prior to forming the parison; (c) feeding the parison between first and second mold halves shaped like the armrest; (d) clamping the parison by moving the first and second mold halves together to form a mold; and (e) pushing the first and second layers of the parison outward, using blown air, such that the first layer is adjacent the mold and the second layer forms a hollow core of the armrest, the hollow core being partially filled by expansion of the second layer during cooling. 
         [0014]    In another possible embodiment, the method may further include the step of reinforcing at least one of the first layer and the second layer prior to forming the parison. The reinforcing step may further include mixing reinforcement fibers into the at least one of the first layer and the second layer of the parison. 
         [0015]    In another possible embodiment, the method may further include the step of varying a thickness of at least one of the first layer and the second layer. In still another, the method may further include the step of partitioning the hollow core of the armrest. 
         [0016]    In accordance with still another aspect, a method of forming an armrest for a captain&#39;s seat of a vehicle is provided. The method may be broadly described as comprising the steps of: (a) forming a parison having a first layer, a second layer, and a third layer; (b) mixing a foaming agent into the second layer prior to forming the parison; (c) feeding the parison between first and second mold halves shaped like the armrest; (d) clamping the parison by moving the first and second mold halves together to form a mold; and (e) pushing the first, second, and third layers of the parison outward, using blown air, such that the first layer is adjacent the mold, the second layer expands between the first layer and the third layer, and the third layer forms a hollow core of the armrest, the hollow core being partially filled by expansion of the second layer during cooling. 
         [0017]    In another possible embodiment, the method may further include the step of reinforcing at least one of the first layer, the second layer, and the third layer of the parison. The reinforcing step may further include mixing reinforcement fibers into the at least one of the first layer, the second layer, and the third layer prior to forming the parison. 
         [0018]    In another possible embodiment, the method may further include the step of varying a thickness of at least one of the first layer, the second layer, and the third layer. In still another, the method may further include the step of partitioning the hollow core of the armrest. 
         [0019]    In accordance with another aspect, a method of forming a bumper for a vehicle is provided. The method may be broadly described as comprising the steps of: (a) forming a parison having a first layer and a second layer; (b) mixing a foaming agent into the second layer prior to forming the parison; (c) feeding the parison between first and second mold halves shaped like the bumper; (d) clamping the parison by moving the first and second mold halves together to form a mold; and (e) pushing the first and second layers of the parison outward, using blown air, such that the first layer is adjacent the mold and the second layer forms a hollow core of the bumper, the hollow core being partially filled by expansion of the second layer during cooling. 
         [0020]    In another possible embodiment, the method may further include the step of reinforcing at least one of the first layer and the second layer prior to forming the parison. The reinforcing step may further include mixing reinforcement fibers into the at least one of the first layer and the second layer of the parison. In another possible embodiment, the method may further include the step of varying a thickness of at least one of the first layer and the second layer. In still another, the method may further include the steps of partitioning the hollow core of the armrest and/or fusing the inner layers together to provide additional stiffness or rigidity. 
         [0021]    In the following description, there are shown and described several preferred embodiments of the armrest and bumper and the related methods. As it should be realized, the armrest and bumper and methods are capable of other, different embodiments and their several details are capable of modification in various, obvious aspects all without departing from the assemblies and method as set forth and described in the following claims. Accordingly, the drawings and descriptions should be regarded as illustrative in nature and not as restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         [0022]    The accompanying drawing figures incorporated herein and forming a part of the specification, illustrate several aspects of the armrest and bumper and together with the description serve to explain certain principles thereof. In the drawing figures: 
           [0023]      FIG. 1  is a plan side view of an armrest; 
           [0024]      FIG. 2  is a plan bottom view of an armrest; 
           [0025]      FIG. 3  is a cross-sectional view showing the armrest and, in particular, a hollow core defined by an inner foam layer of the armrest; 
           [0026]      FIG. 4  is a cross-sectional view showing the armrest and, in particular, a hollow core defined by an inner layer of the armrest; 
           [0027]      FIG. 5  is a cross-sectional view of an armrest showing partitions in the hollow core formed by pressing the inner foam layer closer along a length of the armrest; 
           [0028]      FIG. 6  is a cross-sectional view of an armrest showing partitions in the hollow core formed by pressing the inner layer together along a length of the armrest; 
           [0029]      FIG. 7A  is a cross-sectional view of a two-layer parison extruded from an extrusion head and extending between mold halves; 
           [0030]      FIG. 7B  is a cross-sectional view of a two-layer parison pushed out against a mold by blown fluid in order to form the armrest; 
           [0031]      FIG. 8A  is a cross-sectional view of a three-layer parison extruded from an extrusion head and extending between mold halves; and 
           [0032]      FIG. 8B  is a cross-sectional view of a three-layer parison pushed out against a mold by blown fluid in order to form the armrest; 
           [0033]      FIG. 9  is a plan top view of a bumper; 
           [0034]      FIG. 10  is a cross-sectional view showing the bumper and, in particular, a hollow core defined by an inner layer of the bumper; 
           [0035]      FIG. 11  is a cross-section view of an alternate bumper designed to maximize energy absorption in the event of a collision; 
           [0036]      FIG. 12A  is a cross-sectional view of a three-layer parison extruded from an extrusion head and extending between mold halves; and 
           [0037]      FIG. 12B  is a cross-sectional view of a three-layer parison pushed out against a mold by blown fluid in order to form the bumper. 
       
    
    
       [0038]    Reference will now be made in detail to the present embodiments of the armrest, bumper, and the related methods, examples of which are illustrated in the accompanying drawing figures, wherein like numerals are used to represent like elements. 
       DETAILED DESCRIPTION 
       [0039]    Reference is now made to  FIGS. 1 and 2  which illustrate an embodiment of an armrest  10  for a captain&#39;s chair of a vehicle. The armrest  10  is elongated for comfortably supporting the arm of a passenger and includes an outer layer  12  and an inner foam layer  14 . The outer layer  12  in the described embodiment is a plastic (e.g., polypropylene). The inner foam layer  14  in the described embodiment is a mixture of plastic (e.g., polypropylene) and a foaming agent. As will be described in more detail below, the foaming agent allows for the inner foam layer to expand after extrusion and during cooling. 
         [0040]    A mounting hole  16  for mounting the armrest  10  to a back of a captain&#39;s chair extends through the armrest. The armrest  10  is attached to the back of the captain&#39;s chair using a suitable fastener (e.g., a bolt or screw). The armrest  10  may be covered by a foam backed fabric or leather  18  as is known in the art. The fabric or leather  18  and foam  20  are partially shown in the figure. As shown in  FIG. 2 , the bottom of the armrest  10  is a closed, smooth surface  22 . 
         [0041]    As shown in  FIG. 3 , the inner foam layer  14  of the armrest  10  defines a hollow core  24 . Limiting the material within the armrest in this manner lowers the overall weight while providing a suitable rigidity for the armrest. The extent of foaming, i.e., expansion of the inner layer  14 , depends on the ratio of plastic to foaming agent utilized and/or the thickness of the extruded inner foam layer. In the described embodiment, the plastic and foaming agent are in pellet form. The two are mixed together at a desired ratio to control the thickness of the inner layer prior to heating and extrusion of the parison in a blow molding machine. Alternatively, the foaming agent could be an inert gas (e.g., nitrogen or carbon dioxide) injected into melted plastic prior to extrusion. One such method of injecting an inert gas is Trexel, Inc.&#39;s Mucell® foaming process. As the parison is extruded, the pressure on the plastic is released and foaming occurs. 
         [0042]    In an alternate embodiment shown in  FIG. 4 , an armrest  26  includes the outer layer  12  and the inner foam layer  14  and further includes a third, inner, layer  28 . The inner layer  28  in the described embodiment is a plastic (e.g., polypropylene) and defines the hollow core  24 . 
         [0043]    In either of the described embodiments, at least one of the outer layer  12 , the inner foam layer  14 , and/or the inner layer  28  may include a reinforcing material. The reinforcing material may be fibers, fiberglass, talc, wood, and/or carbon among other fibrous materials known in the art. As will be discussed in more detail below, the reinforcing material in the described embodiments is mixed with the plastic (or plastic and foaming agent in the case of the inner foam layer) prior to heating the plastic for extrusion. 
         [0044]    Similarly, in either of the described embodiments, at least one of the outer layer  12 , the inner foam layer  14 , and/or the inner layer  28  may be varied in thickness across its length. As will be discussed in more detail below, varying the thickness of a layer is accomplished by adjusting the spacing of the extrusion heads during manufacturing. 
         [0045]    Even more, the hollow core  24  of the armrest  10  may include at least one partition  30  as shown in  FIG. 5 . In the embodiment described in  FIG. 5 , the partition  30  is formed by varying the thickness of the inner foam layer  14  at varying locations along the length of the armrest  10  during manufacturing. In this manner, the inner foam layer  14  is thicker such that expansion of the foaming agent, during cooling, bridges the hollow core  24  forming partition  30 . Alternately, the ratio of layer thickness between the outer layer and inner foam layer can be adjusted to accomplish the same result, i.e., creation of a partition. 
         [0046]    The hollow core  24  of the armrest  26  may likewise include at least one partition  32  as shown in  FIG. 6 . In this described embodiment, the partition  32  is formed by varying the thickness of the inner foam layer  14  at varying locations along the length of the armrest  10  during manufacturing. In this manner, the inner foam layer  14  is thicker such that expansion of the foaming agent, during cooling, causes the inner layer  28  to bridge the hollow core  24  forming partition  32 . Alternately, the ratio of layer thickness between the outer layer, inner foam layer, and inner layer can be adjusted to accomplish the same result, i.e., creation of a partition. 
         [0047]    As indicated above, the armrest  10  in the described embodiment is made utilizing a blow molding process. The outer layer  12  which includes plastic pellets is melted in a melting chamber of an extruder (not shown) prior to being fed as a melted plastic  32  to an extrusion head  34 . The inner foam layer  14  similarly includes plastic pellets and foaming agent pellets which are mixed together and melted in a separate melting chamber (not shown) prior to being fed as a melted combination  36  of plastic and foaming agent to the extrusion head. The extrusion head  34 , in the described embodiment, is a dual extrusion head allowing the outer layer  12  and inner foam layer  14  to be extruded at the same time. 
         [0048]    As shown in  FIG. 7A , a parison  38  which is generally described as a tubular shape of hot plastic is formed by the extrusion head  34  and extends between mold halves  40 ,  42 . The parison  38  includes the outer layer  12  and inner foam layer  14 . As shown, the inner foam layer  14  begins expanding (as shown by numeral  44 ) due to a decrease in pressure as the inner foam layer  14  exits the extrusion head. A cooling of the parison  38  further contributes to the expansion of the inner foam layer  14 . As the parison  38  extends from the extruding head  34  the length of the mold, the mold halves  40 ,  42  come together, as shown by action arrows A, to form the armrest mold and clamp the parison  38  in position. 
         [0049]    As shown in  FIG. 7B , fluid is introduced through tube  46  as shown by action arrows B. In the described embodiment, the fluid is ambient air which pushes the parison  38 , including the outer layer  12  and inner foam layer  14 , out to match the shape of the mold. The tube  46  may be retractable and insertion though the mold may result in fluid being blown into the open cavity  24  or into the inner foam layer  14 . Since the inner foam layer  14  is an open cell foam, the fluid can travel throughout the inner foam layer  14  having the same effect on the outer layer  12  and the inner foam layer. Once the outer layer  12  and inner foam layer  14  have cooled and hardened, the mold halves  40 ,  42  are opened as shown by action arrows C and the armrest  10  is ejected. Flashing on the ejected armrest  10  may require removal. 
         [0050]    In an alternate embodiment described above, a third or inner layer  28  is included in the armrest  26 . In this instance, the inner layer  28  is a plastic which is formed by melting plastic pellets in a melting chamber as described above with regard to the outer layer  12 . The melted plastic  48  is fed to the extruding head  50  which in the described embodiment is a tri-extrusion head. 
         [0051]    As shown in  FIG. 8A , a parison  52  which is generally described as a tubular shape of hot plastic is formed by the extrusion head  50  and extends between mold halves  40 ,  42 . The parison  52  includes the outer layer  12 , the inner foam layer  14 , and inner layer  28 . As shown, the inner foam layer  14  begins expanding (as shown by numeral  44 ) due to a decrease in pressure as the inner foam layer  14  exits the extrusion head  50 . A cooling of the parison  52  further contributes to the expansion of the inner foam layer  14 . As the parison  52  extends from the extruding head  50  the length of the mold, the mold halves  40 ,  42  come together, as shown by action arrows A, to form the armrest mold and clamp the parison  52  in position. 
         [0052]    As shown in  FIG. 8B , fluid is introduced through tube  46  as shown by action arrows B. In the described embodiment, the fluid is ambient air which pushes the parison  52 , including the outer layer  12 , the inner foam layer  14 , and the inner layer  28  out to match the shape of the mold. Again, the tube  46  may be retractable and insertion though the mold may result in fluid being blown into the open cavity  24  or into the inner foam layer  14 . Since the inner foam layer  14  is an open cell foam, the fluid can travel throughout the inner foam layer  14  having the same effect on the outer layer  12  and the inner foam layer. Once the outer layer  12 , the inner foam layer  14 , and the inner layer  28  have cooled and hardened, the mold halves  40 ,  42  are opened as shown by action arrows C and the armrest  26  is ejected. Flashing on the ejected armrest  26  may require removal. 
         [0053]    As noted above, at least one of the outer layer  12 , the inner foam layer  14 , and/or the inner layer  28 , in the described embodiments, may include a reinforcing material. In accordance with the method, reinforcement fibers (not shown) are mixed into at least one of the outer layer  12 , the inner foaming layer  14 , and/or the inner layer  28  prior to forming the parison. The reinforcing material may be fibers, fiberglass, talc, wood, and/or carbon among other fibrous materials known in the art. 
         [0054]    Similarly, in either of the described embodiments, at least one of the outer layer  12 , the inner foam layer  14 , and/or the inner layer  28  may be varied in thickness across its length. As will be discussed in more detail below, varying the thickness of a layer is accomplished by adjusting the spacing of one or more of the extrusion heads during manufacturing. Alternatively, varying the composition of the inner foam layer  14  to include a higher percentage of foaming agent may also be utilized to vary the thickness of the layer. 
         [0055]    Last, alternate embodiments may also include the step of partitioning the hollow core  24  of the armrest  10 ,  26 . In the two layer embodiment of the armrest  10  shown in  FIG. 5 , the partitions  30 ,  32  are formed by varying the thickness of the inner foam layer  14  at varying locations along the length of the armrest  10  during manufacturing. In this manner, the inner foam layer  14  is thicker such that expansion of the foaming agent, during cooling, bridges the hollow core  24  forming partition  30 . Alternately, the ratio of layer thickness between the outer layer and inner foam layer can be adjusted to accomplish the same result, i.e., creation of a partition. 
         [0056]    With reference to  FIGS. 9 and 10  which illustrate an embodiment of a bumper  110  for a vehicle, the bumper  110  includes an outer layer  112 , an inner foam layer  114 , and a third, inner, layer  128 . The outer layer  112  in the described embodiment is a plastic (e.g., polypropylene). The inner foam layer  114  in the described embodiment is a mixture of plastic (e.g., polypropylene) and a foaming agent. The inner layer  128  in the described embodiment is a plastic (e.g., polypropylene) and defines the hollow core  124 . As will be described in more detail below, the foaming agent allows for the inner foam layer to expand after extrusion and during cooling. 
         [0057]    As shown in  FIG. 10 , the inner foam layer  114  of the bumper  110  defines a hollow core  124 . Limiting the material within the bumper in this manner lowers the overall weight while providing a suitable rigidity for the bumper. The extent of foaming, i.e., expansion of the inner foam layer  114 , depends on the ratio of plastic to foaming agent utilized and/or the thickness of the extruded inner foam layer. In the described embodiment, the plastic and foaming agent are in pellet form. The two are mixed together at a desired ratio to control the thickness of the inner foam layer prior to heating and extrusion of the parison in a blow molding machine. Alternatively, the foaming agent could be an inert gas (e.g., nitrogen or carbon dioxide) injected into melted plastic prior to extrusion. One such method of injecting an inert gas is Trexel, Inc.&#39;s Mucell® foaming process. As the parison is extruded, the pressure on the plastic is released and foaming occurs. 
         [0058]    As further shown by reference numeral  129 , the inner layers  128  may be fused together during formation of one or more compartments  126  in the hollow core  124 . Fusing the inner layers  128  provides additional stiffness. In an alternate embodiment shown in  FIG. 11 , a bumper  130  is formed in a collapsible shape for energy absorption in the event of an accident. Of course, the bumper  130  of the present invention may be molded into any number of collapsible shapes which provide for energy absorption. 
         [0059]    In either of the described bumper embodiments, at least one of the outer layer  112 , the inner foam layer  114 , and/or the inner layer  128  may include a reinforcing material. The reinforcing material may be fibers, fiberglass, talc, wood, and/or carbon among other fibrous materials known in the art. As will be discussed in more detail below, the reinforcing material in the described embodiments is mixed with the plastic (or plastic and foaming agent in the case of the inner foam layer) prior to heating the plastic for extrusion. 
         [0060]    Similarly, in either of the described bumper embodiments, at least one of the outer layer  112 , the inner foam layer  114 , and/or the inner layer  128  may be varied in thickness across its length. As will be discussed in more detail below, varying the thickness of a layer is accomplished by adjusting the spacing of the extrusion heads during manufacturing. 
         [0061]    In alternate embodiments, a bumper may include only the outer layer and the inner foam layer forming a hollow core. The outer layer would be a plastic (e.g., polypropylene) and the inner foam layer would be a mixture of plastic and a foaming agent as in the described embodiment of a bumper. The inner foam layer may be fused together forming compartments within the hollow core as described above for the three layer embodiment. 
         [0062]    In the same manner described above with regard to the armrest  10 , the bumper  110  in the described embodiment is made utilizing a blow molding process as shown in  FIG. 12A . The outer layer  112  which includes plastic pellets is melted in a melting chamber of an extruder (not shown) prior to being fed as a melted plastic  132  to an extrusion head  134 . The inner foam layer  114  similarly includes plastic pellets and foaming agent pellets which are mixed together and melted in a separate melting chamber (not shown) prior to being fed as a melted combination  136  of plastic and foaming agent to the extrusion head. The inner layer  128  is also plastic which is formed by melting plastic pellets in the melting chamber as described above with regard to the outer layer  112 . The melted plastic  148  is fed to the extruding head  150  which in the described embodiment is a tri-extrusion head. 
         [0063]    The parison  152  which is generally described as a tubular shape of hot plastic is formed by the extrusion head  150  and extends between mold halves  140 ,  142 . The parison  152  includes the outer layer  112 , inner foam layer  114 , and inner layer  128 . As shown, the inner foam layer  114  begins expanding (as shown by numeral  144 ) due to a decrease in pressure as the inner foam layer  114  exits the extrusion head. A cooling of the parison  152  further contributes to the expansion of the inner foam layer  114 . As the parison  152  extends from the extruding head  150  the length of the mold, the mold halves  140 ,  142  come together, as shown by action arrows D, to form the bumper mold and clamp the parison  152  in position. 
         [0064]    As shown in  FIG. 12B , fluid is introduced through tube  146  as shown by action arrow E. In the described embodiment, the fluid is ambient air which pushes the parison  138 , including the outer layer  112 , the inner foam layer  114 , and the inner layer  128  out to match the shape of the mold. The tube  146  may be retractable and insertion though the mold may result in fluid being blown into the open cavity  124  or into the inner foam layer  114 . Since the inner foam layer  114  is an open cell foam, the fluid can travel throughout the inner foam layer having the same effect on the outer layer  112  and the inner foam layer. Once the outer layer  112 , the inner foam layer  114 , and the inner layer  128  have cooled and hardened, the mold halves  140 ,  142  are opened as shown by action arrows F and the armrest  10  is ejected. Flashing on the ejected bumper may require removal. 
         [0065]    In summary, numerous benefits result from providing an armrest and bumper including an outer layer and an inner layer defining a hollow core, and alternate embodiments include a third, or inner, layer which defines the hollow core. Forming the armrest in accordance with the described method provides for an armrest for a captain&#39;s chair that is lightweight, formed as a unitary piece, and minimizes, if not eliminates, any sharp edges. Forming the bumper in accordance with the described method similarly provides for a bumper that is lightweight, formed as a unitary piece, and minimizes, if not eliminates, any sharp edges. The bumper may also be formed with higher local stiffness, higher energy absorption, shorter tack-off distances, no tack-off witness marks, and in energy absorbing configurations. 
         [0066]    The foregoing has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. Obvious modifications and variations are possible in light of the above teachings. All such modifications and variations are within the scope of the appended claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled.