Abstract:
An air permeable envelope has a gripper for securing the envelope to a seat. A mixture contained in the air permeable envelope can react exothermically upon exposure to air. A sealed bag that is relatively air impermeable, initially holds the air permeable envelope and mixture together with the gripper. Upon opening and unsealing the bag, the mixture is exposed to air in order to start an exothermic reaction. The envelope and the gripper are removed from the bag and the gripper is used to attach the envelope upon the seat to warm it.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to warming devices and methods, and in particular, to warming a seat using an air-activated, exothermic reaction. 
     2. Description of Related Art 
     Many athletic events are performed at relatively cold temperatures, either outdoors or in an open-air stadium. The spectators will be relatively sedentary and can easily become chilled when sitting on stadium seats or simple bench-style bleachers. Often these seating arrangements will have a hard plastic or metal seat that tends to remain cold or even draw away body heat. To combat this problem, spectators will dress warmly and use blankets and the like, in order to try and retain their body heat. 
     Portable cushions have been placed on stadium seats for comfort and for insulation from the cold. However, cushions tend to be bulky, are easily misplaced or lost, and are inconvenient to carry back and forth. Also, vendors cannot easily travel through a stadium carrying stacks of cushions for immediate sale to spectators. Moreover, once purchased, portable cushions must be periodically cleaned and handled with care if one wishes to use the cushion repeatedly. 
     In addition, some stadium chairs have seats that swing up when the seated person rises. A cushion can prevent the seat from fully swinging and therefore impede movement in the vicinity of the chair. This problem can be exacerbated if the cushion is secured to the seat by straps or other mechanisms that interfere with the swinging motion of the seat. On the other hand, if unsecured, the cushion can slip and fall behind the chair, becoming difficult to retrieve. 
     A known heat pack uses a mixture of iron powder, water, activated charcoal, vermiculite, and salt. The iron powder is oxidized (rusts) in an exothermic reaction. Air and water are necessary for the reaction to proceed, but only the water is provided in the mixture. For this reason, the mixture is stored in an air permeable envelope that is then, in turn, sealed in a relatively air impermeable bag. When the envelope containing the mixture is removed from the bag, air can reach the mixture and start the exothermic reaction. The vermiculite and activated carbon are useful for storing and releasing water to accommodate the reaction. The activated carbon is also useful in storing and releasing the salt catalyst, as well as conducting and dispersing the heat generated by the exothermic reaction. 
     See also U.S. Pat. Nos. 1,613,120; 1,953,513; 3,301,250; 3,976,049; 3,980,070; 4,106,478; 4,604,987; 5,398,667; 5,545,198; 5,833,309; 7,438,356; and D329,957. 
     SUMMARY OF THE INVENTION 
     In accordance with the illustrative embodiments demonstrating features and advantages of the present invention, there is provided a device for warming a seat. The device includes an air permeable envelope having a gripper for securing the envelope to the seat. The device also includes a mixture contained in the air permeable envelope that exothermically reacts upon exposure to air. Also included is a sealed bag holding the air permeable envelope together with the gripper and the mixture. In comparison to the air permeable envelope, the bag is relatively air impermeable in order to restrict exothermic reaction with air of the mixture in the envelope. 
     In accordance with another aspect of the invention, there is provided a method for warming a seat by employing an exothermically reactive mixture inside an air permeable envelope that is initially sealed inside a relatively air impermeable bag together with a gripper. The method includes the step of opening and unsealing the bag to expose the mixture to air in order to start an exothermic reaction. The method also includes the step of removing the envelope and the gripper from the bag. Also included are the steps of using the gripper to attach the envelope upon the seat and sitting on the envelope. 
     By employing devices and methods of the foregoing type, one is able to provide warmth to a person using a seat. In a disclosed embodiment an air permeable envelope contains a mixture of iron, water and other useful ingredients such as activated carbon and salt. This envelope is stored in a sealed, relatively air impermeable bag. After removal from the bag, air can penetrate the air permeable envelope to begin an exothermic reaction. 
     The air permeable envelope containing this mixture will have a gripper adapted to secure the envelope to a seat. In one disclosed embodiment, the air permeable envelope will be encircled by an apron devoid of any mixture. The edge of the apron will be a hemmed to enclose an elastic member. This arrangement is relatively compact and therefore the air permeable envelope containing the exothermically reactive mixture can be easily stored in the air impermeable bag. Consequently, this envelope can be deployed with the elastic member stretched over a seat to hold the envelope in place. 
     In another embodiment, the gripper is an adhesive layer disposed on the air permeable envelope in two parallel strips. Release sheets placed over the adhesive layer can be removed just prior to installation of the envelope onto the seat. The adhesive layer is also relatively compact and therefore easily stored in the air impermeable bag as a part of the air permeable envelope containing the exothermically reactive mixture. 
     To make the device very compact, the envelope containing the mixture can be folded before being sealed into the air impermeable bag. In a disclosed embodiment the air permeable envelope can be made from two opposing sheets containing four discrete portions of the mixture. In this embodiment, the sheets are heat sealed together along the periphery and along two intersecting fold lines to form four discrete compartments containing four portions of the mixture. Accordingly, the envelope can be folded twice along the fold lines without disturbing the mixture contained in the four compartments. When folded in this manner, the device can be fairly compact and readily carried in a purse, pocket, or the like. 
     Once in place on the seat, the mixture will continue to exothermically react over, for example, several hours. Thus, a person seated on the seat will be warmed by the foregoing device and will be able to tolerate relatively cold temperatures for an extended period of time. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above brief description as well as other objects, features and advantages of the present invention will be more fully appreciated by reference to the following detailed description of illustrative embodiments in accordance with the present invention when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is an edge view of an envelope containing an exothermically reactive mixture that is part of a device and method in accordance with principles of the present invention; 
         FIG. 2  is a plan view of the underside of the envelope of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of a portion of the envelope of  FIG. 1 , taken along line  3 - 3  of  FIG. 2 ; 
         FIG. 4  is a perspective view of the envelope of  FIG. 1  folded in order to fit inside the illustrated bag to form said device; 
         FIG. 5  is a perspective view of a seat fitted with the envelope of  FIG. 1  in accordance with the method of the present invention; 
         FIG. 6  is a perspective view of an envelope that is an alternate to that of  FIG. 1 ; and 
         FIG. 7  is a cross-sectional view of a fragment of the envelope of  FIG. 6 , taken at the periphery of the envelope. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1-3 , an air permeable envelope  10  is shown as a pair of opposing sheets  12  and  14 , which have a generally rectangular outline with rounded corners. The edges of this rectangular pair are heat sealed to form a closed peripheral boundary  16 . 
     Envelope  10  is bisected twice by a transverse pair of fold lines L 1  and L 2 , each reaching across to opposite edges of envelope  10 . Sheets  12  and  14  are also heat sealed along fold line L 1  in regions  18 A and  18 B. Similarly, sheets  12  and  14  are also heat sealed along fold line L 2  in regions  20 A and  20 B. In some embodiments heat sealing may be eliminated in favor of other sealing techniques such as gluing. 
     The space between sheets  12  and  14  is thus divided into four discrete compartments  22 A,  22 B,  22 C and  22 D. Compartments  22 A,  22 B,  22 C and  22 D are each filled with a separate portion of mixture  24 . While four compartments are illustrated, in other embodiments a different number of compartments may be provided (including the case where only one compartment is provided). One advantage of using separate compartments is that mixture  24  will be unable to shift across the full width of envelope  10  and will therefore tend to remain more evenly distributed. Since envelope  10  is segregated into compartments, the envelope may be considered a quilted envelope. 
     In this embodiment the ingredients of mixture  24  include powdered iron, water, salt (in this case, sodium chloride), and activated carbon. The water and salt may be deposited in the activated carbon as a salt solution. The activated carbon can then act as a supply source of water and salt as well as a medium for distributing heat generated by the mixture. In some embodiments the function of the activated carbon may be supplemented with vermiculite. 
     The iron in this mixture will readily oxidize when exposed to air to produce heat (exothermic reaction). Water supports the reaction and the salt acts as a catalyst. Exothermic chemical reactions of this type are disclosed in U.S. Pat. Nos. 3,301,250; 3,976,049; 3,980,070; and 4,106,478. While the foregoing mixture will operate satisfactorily, the present invention can be practiced using other mixtures, employing different constituents or different concentrations, in order to produce an exothermic reaction upon exposure to air. 
     The rate and duration of heat produced by mixture  24  can be adjusted by adjusting the constituents of the mixture and the permeability of sheets  12  and  14 . The amount of iron in the mixture  24  will primarily determine the total number of calories that can be produced. The reaction rate of mixture  24  will determine the temperature and duration of the reaction. A higher reaction rate will produce a higher temperature of a shorter duration (a lower rate producing a lower temperature and longer duration). The concentration of water and salt in the activated carbon (and vermiculite if present) will affect the feed rate of water and salt and thus the reaction rate. The permeability of sheets  12  and  14  will also affect the reaction rate, with a higher (lower) permeability leading to a higher (lower) reaction rate. 
     The permeability of sheets  12  and  14  will be determined by the sheets&#39; physical characteristics. Sheets  12  and  14  may be a fabric formed of natural or synthetic fibers. In other cases sheets  12  and  14  may be a plastic made with micropores. In some cases sheets  12  and  14  may be air permeable sheets of polyethylene, polypropylene, nylon, polyester, polyvinyl chloride, polyvinylidene chloride, polystyrene, natural rubber, synthetic rubbers, reclaimed rubbers, etc. In this embodiment, sheets  12  and  14  are essentially squares with sides that are 10 to 12 inches (25 cm to 30 cm) long, although other dimensions may be desired depending upon the intended use. 
     External adhesive layers  26 A and  26 B are laid down in two strips: one spanning compartments  22 A and  22 B, and the other spanning compartments  22 C and  22 D. While two disjoint segments are shown, other embodiments may employ a different number of segments (including a single segment) having different shapes. Release sheets  28 A and  28 B initially cover adhesive layers  26 A and  26 B, respectively, but will be removed when these layers are needed to act as grippers, in a manner to be described presently. 
     Referring to  FIG. 4 , previously mentioned envelope  10  is shown folded once along fold line L 1  (regions  18 A and  18 B) and a second time along fold line L 2  (regions  20 A and  20 B). Having been folded twice, envelope  10  can readily fit into bag  30 . Bag  30  is formed from an opposing pair of sheets  32  and  34  that are shown heat sealed along border  36 . Sheets  32  and  34  are essentially air impermeable so that when sealed, bag  30  will be air impermeable. 
     In  FIG. 4  bag  30  is shown open on top so that folded envelope  10  can be inserted in (removed from) the opening. The opening can be heat sealed or glued along margin  38 . In some embodiments, a side of the sealed bag  30  may be arranged to be torn open in order to access folded envelope  10 . It will be understood that in some cases, folded envelope  10  will be placed between unattached sheets  32  and  34  before all edges of the bag are heat sealed or glued in a single pass. When envelope  10  is sealed in bag  30 , the combination is herein referred to as device  10 / 30 . 
     Because mixture  24  ( FIG. 3 ) in envelope  10  will react to air, the mixture may be prepared in an inert atmosphere or vacuum. Likewise, the insertion of folded envelope  10  into bag  30  ( FIG. 4 ) will be performed either in an inert atmosphere or vacuum. When finally sealed, bag  30  will be evacuated or will hold an inert gas so that mixture  24  in folded envelope  10  will not begin to exothermically react. 
     To facilitate an understanding of the principles associated with the foregoing device  10 / 30 , its operation will be briefly described. With folded envelope  10  sealed in bag  30 , mixture  24  will not react since the bag is substantially air impermeable and does not otherwise contain any appreciable amount of air. Being relatively compact, a person can readily carry bag  30  with envelope  10  in a pocket, purse, or other carrier. 
     In some cases, a person will carry device  10 / 30  to a sporting event; for example, an event in an open air stadium. The stadium will typically have many rows of chairs such as chair  32  of  FIG. 5 . Chair  32  has a back  34  mounted between a pair of side frames  36  (the upper portion of the right frame being broken away for illustrative purposes). Hinged on frames  36  are a pair of arms  38  (only one visible in this view) for supporting seat  40 . In a well known manner, seat  40  and arms  38  can be swung up against back  34  to ease traveling past chair  32 . 
     If the day is cold, a person may wish to use device  10 / 30 . Therefore, bag  30  will be opened by tearing one of its edges, pulling apart one of its seams, or the like. Envelope  10  can then be removed in the folded condition shown in  FIG. 4 . Thereafter, envelope  10  will be unfolded as shown in  FIG. 2 . Specifically, envelope  10  will be unfolded twice, once along fold line L 2  and then along fold line L 1 . 
     Next, the user will remove release sheets  28 A and  28 B to expose adhesive layers  26 A and  26 B, respectively. Then, with the adhesive layers  26 A and  26 B facing down, envelope  10  will be placed atop seat  40  as shown in  FIG. 5  so that the envelope will then adhere to seat  40 . This adhesive feature will prevent dislodging of envelope  10  in the event of wind gusts or in the event that seat  40  should swing up against back  34 . At this time a user will sit upon envelope  10 . 
     Since sheets  12  and  14  are air permeable, air will reach mixture  24  to sustain an exothermic reaction that will generate heat. In this embodiment, with a given quantity of active ingredients in mixture  24 , the reaction rate will be tailored to produce over a three to five hour time interval an average temperature of 100° F. (37.8° C.) with a maximum temperature of 107° F. (41.7° C.). It will be understood that depending upon the anticipated circumstances, device  10 / 30  can be designed to produce a different temperature over a different time interval. In some cases, the user may replace an expended envelope  10  with a fresh one. 
     When a user is ready to leave (or the exothermic reaction of mixture  24  has ended) envelope  10  with its mixture  24  will be lifted from seat  40  and discarded. Since the mixture  24  is environmentally safe, it can be discarded in any convenient refuse receptacle. Furthermore, the user need not worry about returning home with any heating equipment that needs to be cleaned or maintained. 
     Referring to  FIGS. 6 and 7 , components corresponding to that previously illustrated in  FIGS. 1-5  will bear the same reference numeral but increased by 100. As before, mixture  124  will be sealed between sheets  112  and  114  by heat sealing (or gluing) along border  116  as well as along regions  118 A,  118 B,  120 A, and  120 B to form four discrete compartments  122 A,  122 B,  122 C and  122 D. Fold line L 3  runs along regions  118 A and  118 B, while fold line L 4  runs along regions  120 A and  120 B. 
     Sheet  114  extends beyond sheet  112  to form an annular apron  142 . Apron  142  is folded back around elastic member  144  and sealed at seam  144 . Thus elastic member  144  is hemmed in place to form an elastic belt  148 . 
     The foregoing envelope  110  can be folded twice in the manner previously described along fold lines L 3  and L 4  before being sealed inside an air impermeable bag similar to bag  30  of  FIG. 4 . Elastic belt  148  consumes little space and is therefore easily contained within a sealed bag. 
     When needed, envelope  110  will be removed from its sealed bag (e.g. bag  30  of  FIG. 4 ) and will be unfolded in the manner previously described. A user may now stretch elastic belt  148  over the edges of previously mentioned seat  40  as illustrated in  FIG. 6 . Once under seat  40 , elastic belt  148  can be released to contract so that apron  142  of envelope  110  will fit snugly over the edge of seat  40 . Thus, belt  148  will act as a gripper to hold envelope  110  in place. As before, when expended or no longer needed, envelope  110  can be pulled off seat  40  and simply discarded. 
     It will be appreciated that various modifications may be implemented with respect to the above described embodiments. While the opposing sheets that form an envelope for holding the exothermically reactive mixture may be identical, in some embodiments the sheet intended to rest upon a seat may be thicker to provide insulation that prevents excessive heat loss to the environment. While the envelope is shown in  FIG. 5  installed on a stadium seat, the envelope can also be installed on a bleacher bench, on a separate chair (e.g. a folding chair carried by a user), or any other seating surface that may be available. In some embodiments the elastic member at the edge of the apron will be eliminated in favor of an adhesive layer disposed on one side of the apron, in which case the apron may optionally be segmented into a number of discrete wings. In other embodiments the elastic member may be replaced with a drawstring. Some embodiments may have belts girdling the seat to act as grippers. While the foregoing envelope is shown with a generally rectangular outline, in some embodiments the envelope&#39;s outline may be circular, oval, polygonal, etc. Instead of a single envelope contained in a bag, some embodiments may have multiple envelopes in a single bag, and each envelope may have appropriate means for gripping a seat. For embodiments using multiple envelopes, the envelopes, after removal from a bag, may optionally be interconnected into a single structure by adhesives, snaps, zippers, etc. Instead of folding, some envelopes may be rolled into a cylindrical package before storage in an air impermeable bag. 
     Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.