Abstract:
There is disclosed an improved seat element having a seating surface element that incorporates a plurality of peak portions and a plurality of valley portions. Preferably, the plurality of peak portions and the plurality of valley portions is incorporated in an outermost surface of the seating surface element. The term “outermost surface” is intended to include an area of the seating surface element for contact by and/or support of an occupant of the seat element and does not include, for example, grooves or trenches in which there is disposed a component for attachment of a trim cover. A process and a mold for production of such a seat element are also described.

Description:
This application is a continuation of U.S. patent application Ser. No. 11/910,423, filed Oct. 1, 2007, which is a 371 of International Patent Appln. No. PCT/CA2006/000471, filed Mar. 30, 2006, which is a non-provisional of U.S. Patent Appln. No. 60/666,195, filed Mar. 30, 2005, the contents of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     In one of its aspects, the present invention relates to a foam seat element, preferably a foam vehicular seat element. In another of its aspects, the present invention relates to a process for producing a foam seat element, preferably a vehicular seat element. In yet another of its aspects, the present invention relates to a mold for producing a molded element, preferably a molded foam seat element, more preferably a molded foam vehicular seat element. In yet another of its aspects, the present invention relates to a method for producing a mold. 
     DESCRIPTION OF THE PRIOR ART 
     Passenger seats in vehicles, such as automobiles, are typically fabricated from a foam (usually a polyurethane foam) material which is molded into the desired shape and covered with an appropriate trim cover. The foamed material is selected to provide passenger comfort by providing a resilient seat and the trim cover is selected to provide the desired aesthetic properties. 
     In recent years, seats such as vehicular seats have been developed to confer one or more of the following to the seat: comfort, climate control, occupant detection and the like. 
     One area that has received particular attention is the provision of dual density or dual firmness seat components that are more dense or firmer in the peripheral portions of the seat thereby conferring to the occupant a snug or “wrapped-in” feel. This is especially important in performance vehicles which are designed such that turning at relatively high speed may be accomplished. However, there is an ongoing challenge to balance support provided by the seat with comfort of the occupant. 
     Dual density or dual firmness seat elements are expensive to produce and, in many cases, alter the feel of the supporting surface of the seat only in areas where it is perceived to be important to have different firmness properties. In other words, the conventional dual density or dual firmness seat elements use a generally coarse approach to provision of variable density or firmness. 
     Further, dual (or multi) density or dual (or multi) firmness seats typically require the use of two or more types of foam (e.g., molded, free rise, bead and the like) which are typically produced separately and secured together increasing the production time and costs of the final seat product. Alternatively, certain dual (or multi) firmness seats are made by molding or otherwise securing an insert (e.g., wire components, flexolators and the like) to a foam substrate. 
     Accordingly, it would be highly desirable to have the seat element that could be produced from a unitary foam element yet confer the benefits of dual density or dual firmness seats. 
     It would be further advantageous if such an approach were capable of being carried out using a much more finally tuned approach resulting in a seat element having a support surface that is designed for optimum comfort regardless of the size of a particular occupant. 
     It would be particularly advantageous if such an improvement could be implemented without the requirement for large capital expenditure. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to obviate or mitigate at least one of the above-mentioned disadvantages of the prior art. 
     Accordingly, in one of its aspects, the present invention provides a seat element comprising a foam substrate and a seating surface element, at least a portion of the seating surface element comprising a plurality of peak portions and a plurality of valley portions. 
     In another of its aspects, the present invention provides mold for production of a seat element, the mold comprising a first mold portion and a second mold portion engageable to define a mold cavity, the first mold portion having a seating surface molding element comprising a plurality of peak portions and a plurality of valley portions. 
     In yet another its aspects, the present invention provides a method for manufacturing a mold for production of a seat element, the mold comprising a first mold portion and a second mold portion engageable to define a mold cavity, the first mold portion having a first molding surface comprising a seating surface molding element, the seat surface molding element comprising a plurality of peak portions and a plurality of valley portions, the method comprising the steps of: 
     forming an insert having a negative of the seating surface molding element; 
     placing the insert in a first temporary mold portion such that the combination of the insert and the first temporary mold portion corresponds substantially to the first molding surface of the first mold portion; 
     forming a second temporary mold portion having a negative of the first temporary mold portion; 
     disposing a casting composition on the second temporary mold portion; 
     forming a third temporary mold portion on an exposed portion of the casting composition, the second temporary mold portion and the third temporary mold portion combining to define a temporary mold having a mold cavity occupied by the casting composition; 
     removing the casting composition from the temporary mold; 
     dispensing a mold material in the mold cavity; and 
     removing the second temporary mold portion and the third temporary mold portion to produce the first mold portion. 
     Thus, the present inventors have discovered an improved seat element having a seating surface element that incorporates a plurality of peak portions and a plurality of valley portions. Preferably, the plurality of peak portions and the plurality of valley portions is incorporated in an outermost surface of the seating surface element. The term “outermost surface” is intended to include an area of the seating surface element for contact by and/or support of an occupant of the seat element and does not include, for example, grooves or trenches in which there is disposed a component for attachment of a trim cover. 
     In a more preferred embodiment, in a resting (i.e., unoccupied) state of the seat element, the ratio of the contact surface area (peaks only) of the seating surface element to the surface area of the seating surface element is less than 1. 
     In a further preferred embodiment, the present seat element comprises a molded foam seat element, more preferably a molded foam element comprising a unitary foam portion. An advantage of using such a molded foam element in the present seat element is the presence of a skin on the surface of the seating surface element. The presence of the skin is characterized by the foam having a greater density at the surface (e.g., 1 mm depth) as compared to the central or core region. Density can be determined using ASTM D-3574. While not wishing to be bound by any particular theory or mode of action, it is believed that the presence of such a skin (e.g., as distinct from the case where the peaks are simply glued to and/or the valleys are simply cut out of the seating surface element) confers a desirable combination of support and comfort to an occupant of the seat element. 
     The present seat element has a number of advantages, including one or more of the following:
         it is possible to achieve in a single density foam part the “dual firmness” (or multi-firmness) that is conventionally achieved using multiple density foam pieces in a seat element—the terms “dual firmness” and “multi-firmness”are used interchangeably through this specification as are the terms “dual density” and “multi-density”;   it is possible to convert conventional dual firmness split bolsters (blades and bolsters) to a dual firmness full bolster by applying a soft touch to the inboard bolster area;   it is possible to use the present seat element to confer the soft touch feel as an alternative to conventional so-called plus padding;   the present seat element has improved ventilation, optionally in combination with climate control seat technology;   the present seat element is expected to have improved acoustical features;   the present seat element has improved comfort both in fixed and adjustable lumbar areas;   the present seat element has improved comfort in thigh support areas;   the present seat element can be used to improve trim cover effects leading to improved craftsmanship;   the present seat element can be used to obviate or mitigate the use of foam inserts (e.g., border wire foam inserts, felt material and the like) conventionally used for bolster reinforcement;   the present seat element can be used in so-called thin seating applications;   the present seat element provides improved comfort for non-vehicular seating applications such as marine, motorcycle and office furniture applications;   biological effects such as improved blood flow, reduced muscle fatigue, reduced shear stress and the like can accrue from use of the present seat element; and/or   the present seat element can be used in energy management foam applications by providing two distinct layers of crush/impact zones rather than a single layer.       

     Of course, those of skill in the art will recognize other advantages accruing from the present seat element based on the present specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention will be described with reference to the accompanying drawings, wherein like reference numerals denote like parts, and in which: 
         FIG. 1  illustrates a schematic top view of a vehicular seat bottom in which a portion of the seating surface has been pressure mapped to denote relative pressure points created by an occupant seated on the vehicular seat bottom; 
         FIG. 2  illustrates a schematic view of an embodiment of pressure mapping a vehicular seat unit; 
         FIG. 3  illustrates a first preferred embodiment of a seat element in accordance with the present invention; 
         FIG. 4  illustrates a second preferred embodiment of a seat element in accordance with the present invention; 
         FIGS. 5   a ,  5   b  and  5   c  each illustrate an enlarged portion of seat element in accordance with the present invention; 
         FIGS. 6   a ,  6   b ,  6   c  and  6   d  each illustrate various arrangements of the patterns illustrated in  FIGS. 5   a ,  5   b  and  5   c;    
         FIG. 7  illustrates a perspective view of a third preferred embodiment of a seat element in accordance with the present invention; 
         FIG. 8  illustrates a sectional view through line A-A in  FIG. 7 ; 
         FIG. 9  illustrates a sectional view through line B-B in  FIG. 7 ; 
         FIG. 10  illustrates a sectional view through line C-C in  FIG. 7 ; 
         FIGS. 11   a ,  11   b  and  11   c  each illustrate a further embodiment of a textured surface repeating pattern that can be used in the present seat element; 
         FIGS. 12-32  illustrate, in a step-wise manner, production of a first mold section to be used in the present mold; and 
         FIG. 33  illustrates a perspective view of an embodiment of the present mold. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Accordingly, an aspect of the present invention relates to a seat element. Preferably, a seat element is comprised in a vehicular or passenger seat. As used throughout this specification, the term “seat” is intended to have its conventional meaning and includes one or both of a bottom or cushion (i.e., the portion of the seat on which the occupant sits) and a back or backrest (i.e., the portion of the seat which supports the back of the occupant). As is known in the automotive, airline and related industries, a “seat” includes both a cushion (or bottom) and a back (or backrest). Thus, the term “seat” includes a seat element such as a cushion (or bottom), a back (or backrest) or a unit construction comprising a cushion (or bottom) and a back (or backrest). It should also be mentioned that a seat element may be considered to be a cushion (or bottom), a back (or backrest), a headrest and/or an armrest. 
     While highly preferred embodiments of the present invention will be illustrated with reference to a vehicular seat element, in particular a seat cushion (or bottom), it will be appreciated that the present seat element can be used in non-vehicular applications such as domestic and office furniture, stadium seating, theatre seating and the like. 
     With reference to  FIG. 1 , there is illustrated a schematic top view of a vehicular seat bottom in which a portion of the seating surface has been pressure mapped to denote relative pressure of an occupant seated on the vehicular seat bottom. 
     The pressure seat map illustrated in  FIG. 1  can be generated in a conventional manner within the purview of a person of ordinary skill in the art. Once generated, the pressure map is useful insofar as it illustrates areas of relative pressure on the seating surface that are generated when occupant sits on that surface. 
     Thus, in  FIG. 1 , there is illustrated a seat bottom  10  having a pair of winged portions  12  and  14 , and a seating surface  16 . In the example shown in  FIG. 1 , the pressure map comprises three distinct pressure zones: a low pressure zone  17 , a pair of intermediate pressure zones  18  and a pair of high pressure zones  19 . It is to be understood that the terms “low pressure”, “intermediate pressure” and “high pressure” are used in a relative sense and that within each zone there can be some variation in pressure. In a typical pressure map, such variation may be colour coded. 
     By assessing areas of pressure generated by a typical occupant in such a manner, it is possible to identify the locations on seating surface  16  (and possibly on winged portions  12 , 14 ) in which it is desirable to manage surface response to the forces generated by a seated occupant. 
     With reference to  FIG. 2 , there is illustrated a perspective view of a vehicular seat  20  comprising seat bottom  10  described with reference to  FIG. 1  and a seat back  11  connected thereto. 
     The following portions in vehicular seat  20  contain support surfaces in which it may be desirable to manage the response of the surface to pressure from a typical occupant seated in vehicular seat  20 : A, B, C, D and E. The precise location and dimension of these portions of the surface can be determined using pressure mapping technique described above with reference to  FIG. 1 . As stated with reference to  FIG. 1 , in certain cases, it may be desirable to design a managed surface response in one or both winged portions  12  and  14  in seat bottom  10 . Further, it may be desirable to design a managed surface response in shoulder support portions  13  and  15  in seat back  11 . 
     With reference to  FIGS. 3 and 4 , there are illustrated specific embodiments of a seat bottom. In  FIGS. 3 and 4 , similar reference numerals are used as in  FIG. 1 . In  FIG. 3 , the suffix “a” has been used to denote like elements with respective  FIG. 1 . In  FIG. 4 , the suffix “b” has been used to denote like elements with respective  FIG. 1 . 
     In  FIG. 3 , a series of grooves  19   a  is molded into seating surface  16   a  to provide a managed surface response to relatively high pressure imposed on that portion of seating surface  16   a  in response to an occupant seating on seat bottom  10   a . As will be seen, this managed surface response corresponds generally to the location of intermediate pressure zones  18  and high pressure zones  19  generated from the pressure map shown in  FIG. 1 . 
     With reference to  FIG. 4 , it will be seen that seating surface  16   b  includes a plurality of recesses  19   b  which are arranged to provide a managed surface response to the portion of seating surface  16   b  that is expected to experience a relatively high force in response to an occupant sitting on seating surface  16   b.    
     With reference to  FIGS. 5   a ,  5   b  and  5   c , there are illustrated cross-sectional views of various preferred embodiments of the portion of the seat element surface on which it is desired to implement a managed surface response. In other words, the remaining portion of the seat element has not been shown for clarity. 
     In  FIG. 5   a , there is illustrated a surface  100   a  comprising a series of peaks  105   a  and valleys  110   a . As show, each peak  105   a  comprises a flat apex and each valley  110   a  comprises a flat floor (or nadir portion). Peaks  105   a  and valleys  110   a  combine to define a series of projections  115   a  that are generally in the shape of a trapezoid, more particularly, a bi-laterally symmetrical trapezoid. 
     In  FIG. 5   b , a suffix “b” has been added after each reference numeral to denote similar elements with respect to  FIG. 5   a . Thus, in  FIG. 5   b , it will be seen that peaks  105   b  have a round a pecks whereas valleys  110   b  have a rounded floor (or nadir portion). Further, peaks  105   b  and valleys  110   b  combine to define a series of projections  115  which, in cross-section, are generally bell-shaped. 
     In  FIG. 5   c , a suffix “c” has been added after each reference numeral to denote similar elements with respect to  FIG. 5   a . Thus, in  FIG. 5   c , it will be seen that peaks  105   c  have a rounded apex whereas valley  110   c  have a flat floor (or nadir portion). Further, it will be seen that peaks  105   c  and valleys  110   c  combine to form a series of projections  115   c  that, in cross-section, have a substantially parabolic shape. Thus,  FIGS. 5   a , 5 b , and  5   c  show a crenellated pattern. 
     As will be appreciated by those of skill in the art, the specific embodiments illustrated in  FIGS. 5   a ,  5   b  and  5   c  are exemplary in nature. Those of skill in the art having in hand the present specification will be able to modify the specifically illustrated embodiments or design other embodiments that have peaks and valleys, and are otherwise useful in the present seat element. 
     With reference to  FIGS. 6   a ,  6   b ,  6   c  and  6   d , there is illustrated, in schematic form, a top view of a seat element in accordance with the present invention. In  FIGS. 6   a ,  6   b ,  6   c  and  6   d , a series of projections is shown as  115  (no suffix). Projections  115  can be of the form illustrated in  FIGS. 5   a ,  5   b  and  5   c  or in any other shape projection that provides a desirable managed surface response. 
       FIG. 6   a  illustrates projections  115  in a parallel row or radiator-type arrangement.  FIG. 6   b  illustrates projections  115  in a diagonal arrangement.  FIG. 6   c  illustrates projections  115  in a checkerboard-type arrangement and  FIG. 6   d  illustrates projections  115  in a diamond-type pattern. Of course, those with skill in the art, having the present specification in hand, will be able to immediately reduce to practice many other arrangements of projections  115  using the cross-sections shown in  FIGS. 5   a ,  5   b  and/or  5   c , or other cross-sectional shapes. 
     With reference to  FIGS. 7-10 , there is illustrated a preferred seat bottom  150  having multiple sections that provide a managed surface response. 
     Generally, seat bottom  150  comprises a unitary foam element  152  that can be made from polyurethane foam, polypropylene foam, polyethylene foam and the like (polyurethane foam is the most preferred foam). 
     Seat bottom  150  comprises a primary seating surface  154 . Primary seating surface  154  comprises a first textured surface  160 , a second textured surface  170  and third textured surface  180 . 
     Seat bottom  150  further comprises a pair of winged portions  156 , 158 . Each winged portion  156 , 158  comprises a fourth textured surface  190 . 
     First textured surface  160  comprises projections similar to projections  115   a  in  FIG. 5   a  arranged in a pattern similar to the one illustrated in  FIG. 6   a.    
     Second textured surface  170  comprises a series of projections that have a substantial rectangular shape in a pattern such as the one illustrated in  FIG. 6   c.    
     Third textured surface  180  comprises a series of projections made up of peaks having a generally flat apex  181  and a series of valleys having a rounded floor  182  (or nadir portion) arranged in a pattern similar to that shown in  FIG. 6   b . It will be noted that the depth of valleys  182  increases from the middle of seating surface  154  to the periphery thereof. 
     Fourth textured surface  190  is disposed on each of winged portions  156 , 158  and runs along the length of first textured surface  160  and second textured surface  170 . Forth textured surface  190  comprises two rows of cup-shaped portions having a rounded valley  191  (or nadir portion). Seat bottom  150  further comprises a series of grooves  159  which serves to isolate first textured surface  160 , second textured surface  170 , third textured surface  180  and fourth textured surface  190 . In a preferred embodiment series of grooves  159  also serves to have disposed therein a suitable trim cover attachment system (e.g., hog-ring wires, touch fasteners such as Velcro™-type fasteners, mechanical clips and the like). 
       FIG. 11   a  illustrates an enlarged perspective view of a textured surface  100   d  comprising a series of semi-spheroid shaped projections  115   d . Projections  115   d  comprise rounded peaks  105   d  and a substantially continuous floor  110   d  which act as a “valley”. 
       FIG. 11   b  illustrates an enlarged perspective view of a textured surface  100   e  comprising a series of elongate projections  115   e . Projections  115   d  comprise elongate flat peaks  105   e  and a substantially elongate round floor  110   e.    
       FIG. 11   c  illustrates an enlarged perspective view of a textured surface  100   f  comprising a series of projections  115   f . Projections  115   f  comprise flat peaks  105   e  and a substantially ogival or rounded valley (or nadir portion)  110   e.    
     With reference to  FIGS. 12-32 , there is illustrated a stepwise process to producing mold capable of forming a seat element having a textures surface such as shown in  FIG. 3  described above. 
     With reference to  FIG. 12 , a machined master form  200  is produced in a conventional manner (typically from aluminum, wood or any other sufficiently durable material). Machined master form  200  has a negative of the desired texture surface to be conveyed to the seat element. 
     With reference to  FIG. 13 , machined master form  200  is disposed in a container  205  comprising a base  210  and a pair of side walls  215 . A resin (e.g., urethane, silicone and the like) composition  220  is dispensed atop machined master form  200  in a conventional manner. 
     After epoxy resin  220  has cured, it is removed from machined master form  200  to yield a cast resin form  225  having the textured surface to be conveyed to the product eventually to be molded—see  FIG. 14 . 
     Cast resin form  225  is placed in container  225  (or another container). A urethane-forming mixture  230  is dispensed atop as resin form  225  in a conventional manner. Urethane forming mixture  230  is allowed to cure and is thereafter removed from container  200  to yield urethane mat  235  which has the same textured surface as machined master form  200 —see  FIG. 16 . 
     With reference to  FIG. 17 , a model  240  of the finished seat element is constructed without the textured surface. Model  240  may be constructed from wood or any other material that is sufficiently durable to withstand the mold manufacturing process. 
     With reference to  FIG. 18 , model  240  is mounted on a follow board  245  having a seal block area  250 . 
     With reference to  FIG. 19 , model  240  mounted on follow board  245  is than placed in a containment box  255 . 
     Next, with reference to  FIG. 20 , the exposed surfaces of model  240 , follow board  245 , seal block  250  and a portion of containment box  255  are covered with a layer of plaster (or other curable) material  260 . Once plaster material  260  has cured (or otherwise requires sufficient integrity to be handled), follow board  245 , seal block  250  and containment box  255  are removed while leaving model  240  with plaster composition  260 —see  FIG. 21 . 
     With reference to  FIG. 22 , a lid containment box  265  is placed around the marginal edges of plaster composition  260 . 
     Next, plaster (or other curable) composition  270  is dispensed on exposed portions of model  240 , plaster composition  260  and a portion of lid containment box  265 —see  FIG. 23 . Once plaster composition  270  has been cured (or otherwise acquires sufficient integrity), the bowl pattern formed by plaster composition  260  is separated from the lid pattern form by plaster composition  270  and model  240  is removed. 
     With reference to  FIG. 24 , mat  235  ( FIG. 16 ) is disposed as illustrated in the bowl pattern formed by plaster composition  260 . 
     Thereafter, a foundry containment box  275  is disposed around the marginal edges of the bowl formed by plaster composition  260 —see  FIG. 25 . 
     Next, a sand-based (or plaster-based) foundry composition  280  is dispensed in the bowl formed by plaster composition  260  and is contained within foundry containment box  275 . 
     With reference to  FIG. 26 , once the sand-based foundry composition has cured, it is separated from the bowl formed by plaster composition  260  and foundry containment box  275 , and mat  235  is removed therefrom. 
     With reference to  FIG. 27 , a clay (or other malleable) composition  285  is applied over the surface of sand-based foundry composition  280  at a thickness equivalent to the desired thickness of the mold to be manufactured. 
     Next, a foundry containment box  290  is placed around sand-based foundry composition  280  and further sand-based foundry composition  295  is placed atop the exposed portions of clay composition  285 , sand-based foundry composition  280  and exposed portions of foundry composition  290 —see  FIG. 28 . With reference to  FIG. 29 , once sand-based foundry composition  295  has cured, it is separated from foundry containment box  290 , clay composition  285  and sand-based foundry composition  280 . 
     Next, the forms defined by sand-based foundry compositions  280  and  295  are recombined to define a mold cavity  297 —see  FIG. 30 . 
     An aperture  293  or other port is drilled or otherwise created in the form produced by sand-based foundry composition  295  and molten aluminum  299  is dispensed therethrough using a conventional gating system to fill mold cavity  297 . Molten aluminum  299  is allowed to cool after which sand-based foundry compositions  280  and  295  are broken away thereby yielding lower mold section  300 —see  FIGS. 31 and 32 . 
     Various of the steps shown above with reference to  FIGS. 17-30  may be repeated to produce a lid portion  305  of the mold shown in  FIG. 33 . For example, with reference to  FIG. 23 , the form produced by plaster composition  270  may be used in steps such as those appearing in  FIGS. 25  (excluding insert  235 ) and  27 - 30 . If it is not desired to have a textured surface produced by lid portion  305  of the mold shown in  FIG. 33 , the use of mat  235  is not necessary in the production of lid portion  305 . 
     While this invention has been described with reference to illustrative embodiments and examples, the description is not intended to be construed in a limiting sense. Thus, various modifications of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to this description. For example, in the process to produce the present mold, if the design of the seating surface element incorporating the plurality of peaks and the plurality of valleys is not highly contoured, it is possible produce a machined master form as shown in  FIG. 14  without the need to carry out the steps shown in  FIGS. 12 and 13 . Further, its possible to use materials other than the plaster compositions and sand-based foundry composition specifically referred to with reference to  FIGS. 17-30 . Still further, it is possible to adopt patterns other than those shown in  FIGS. 6   a ,  6   b ,  6   c  and  6   d —e.g., a herringbone pattern, a triangular pattern, a polygonal pattern containing more than four sides and the like. 
     It is therefore contemplated that the appended claims will cover any such modifications or embodiments. Further, all of the claims are hereby incorporated by reference into the description of the preferred embodiments. 
     All publications, patents and patent applications referred to herein are incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety.