Abstract:
A heater device for heating objects, including a compartment having a heat generating material and a second compartment having an activation material to generate heat upon mutual contact. The compartments are adapted to present a heating surface to the object to be heated. A divider is positioned in the compartments forming a barrier to maintain separation between reaction components until opened by an opening member positioned in alignment with the divider. An access element is movable into contact with the barrier to permit a heat generating reaction there between.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application is a continuation-in-part of Heater Device application filed Dec. 7, 2009, having Ser. No. 12/632,308, which is a continuation-in-part of Heater Device application filed Jul. 22, 2008, having Ser. No. 12/220,146, which is a continuation-in-part of Pan In Pan Heater application filed Oct. 4, 2007, having Ser. No. 11/973,178. 
     
    
     BACKGROUND 
       [0002]    This invention relates to a device for heating the contents of a container and for keeping it warm. More particularly, the invention relates to a self-contained heater device that allows the contents such as food in a container to be heated. 
         [0003]    Often times, it is desirable to heat food and other items at a location remote from a source of heat such as a stove or oven. Other times it is desirable to take warmed or hot food and other items from the place of heating to another location, such as a picnic, school or church basement, scout meeting and any of the myriad of events that do not meet or gather where heat is available. Sometimes the location is in a location where fire is not permitted, such as a classroom or outdoors during the dry season. It is also important for military personnel to have access to warm food, particularly when deployed in locations remote from their base or station. 
         [0004]    One such self-contained warmer is disclosed in U.S. Patent Application Publication No. US 2007/0034202, to Punphrey et al. in which a container with an exothermic composition is used to heat a vessel. A membrane is used to cover the exothermic composition, which is then activated by removal of the membrane. Various compositions are disclosed that are based on iron oxidation chemistry. The heater is in direct contact with the container and must be put on a heat-resistant surface to be used without damage. 
         [0005]    U.S. Pat. No. 6,705,309 discloses a self-heating or self-cooling container in which tubular walls defining an internal cavity into which steam or hot air is placed as a source of heat. This, of course, requires a source of that heated material. 
         [0006]    It would be a great advantage if a way of heating containers could be developed that has a controlled release of heat that is within acceptable safety limits. 
         [0007]    Another advantage would be to provide a way of heating containers that produces heat over an extended period of time, rather than simply having an exothermic reaction that lasts a few minutes or less. 
         [0008]    Yet another advantage would be to provide a way to activate heaters for containers that is simple and effective and that does not have the potential for pre-activation. 
         [0009]    Other advantages will appear hereinafter. 
       SUMMARY 
       [0010]    The unique aspect of this invention is that a controlled, dispersed exothermic reaction can be used to heat the contents of a container quickly and effectively while maintaining the heat for an extended period of time. The heat generating reaction is activated by an access element that is not in position to cause the activation material to contact the heat generating material until that is desired by the user. 
         [0011]    In its simplest form, the present invention is a two component heater that has a surface on which objects can be heated upon activation of the two components to cause a heat generating reaction. Examples of objects, by way of example and not by way of limitation, that can be heated are towels, wipes, cushions, hats, gloves and other apparel, food packages and the like. The food package may be any package containing comestibles or other material that is to be heated. Typical food boxes are what are known in the military as MRE, which is an acronym for “meals ready to eat.” 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a front elevation view of one component of the preferred embodiment of this invention. 
           [0013]      FIG. 2  is a back elevational view of the embodiment of  FIG. 1 . 
           [0014]      FIG. 3  is a sectional, side elevation view of the embodiment of  FIG. 1  taken along line  33 . 
           [0015]      FIG. 4  is a sectional view of a second component of the preferred embodiment of this invention. 
           [0016]      FIG. 5  is a section view of the preferred embodiment of this invention in  FIG. 3 , with the second component of  FIG. 4 , showing the device prior to activation. 
           [0017]      FIG. 6  is a sectional view of the device of  FIG. 5  after activation of the device. 
           [0018]      FIG. 7  is a view of an object to be heated by the device of this invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    The device,  10  generally in  FIG. 1 , includes a first compartment  11  and a second compartment  13 , separated in this embodiment by a penetrable divider  15  that keeps the contents of the compartments separated from each other. It is preferred that divider  15  have some thickness separating the walls of the compartments, to provide a larger area that will be penetrated as described below. In an alternative, equally effective embodiment, second compartment  13  can be a separate container inside first compartment  11 . 
         [0020]    Also provided is an opening member  17 , shown mounted on the second compartment  13 , on the end  19  of compartment  13  away from divider  15 . Opening member has threads  17   a  that will hold an optional cap, not shown. End  19  is not in communication with the inside of compartment  13 . Compartment  13  also has an end  21  remote from divider  15 . In a preferred embodiment, the junction  23  of the side of compartment  13  and its bottom,  21 , are curved as shown in  FIG. 1 . This prevents accumulation of components in compartment  13  from collecting in the corners where access to them is limited by their being accumulated in the square corners. 
         [0021]    Inside compartment  13  is a quantity of heat generating material  25  that will undergo a chemical reaction and generate heat when contacted by an activation material, such as material  27  inside compartment  13 . An access element  29 , shown in  FIG. 4 , is designed to fit into opening member  17  and penetrate divider  15 . Penetration of divider  15  will cause the activation material  27  to admix with the heat generating material  25  to generate heat. In the following figures, reference is made to heat generating material  25  and activation material  27 , which are shown here in  FIG. 1  and not shown in the remaining figures for purposes of simplicity. These two reaction agents are present in the chambers as described below. 
         [0022]      FIG. 2  shows the back of device  10 , which, in a preferred embodiment, includes a nonwoven material back  31  with a tab  33  that can be used to fasten device  10  to an object to be heated. One side  35  of device  10  is open after initial manufacture and is sealed after the heat generating material  25  and activation material  27  in chambers  13  and  11  respectively. 
         [0023]      FIG. 3  illustrates device  10  in section with upper chamber  11  and lower chamber  13  in position to hold the activation material  27  and heat generating material  25  as described above. Divider  15  is shown as being attached to the side walls of chamber  11  at  15   a  and  15   b , and extending down to its lowest point  15   c . Low point  15   c  is in the middle of the width of chambers  11  and  13 , so that the activation material  27  in chamber  11  is near low point  15   c  when the device  10  is upright as shown in the figures. To activate device  10 , divider  15  is opened to permit the activation material  27  flow into chamber  13  and react with heat generating material  25 . 
         [0024]      FIG. 4  illustrates preferred access element  29  that has a circular cross section over it&#39;s entire length. Access element  29  also includes a central bore  41  that extends nearly the full length thereof. Access element  29  includes a conically tapered tip  43  that is capable of penetrating divider  15  when pressed against it, such as lowest point  15   c . At the other end of access element  29  is a head portion  45  of a first diameter d 1  that tapers at chamfer  47  to the diameter of the body  49  of access element  29  with a diameter d 2  at taper  43  and along the entire length of body  49  up to chamfer  47 . Central bore  41  thus extends from solid tip  43  to head portion  45 . 
         [0025]    Body  49  has a first slot  51  that functions to transfer activation material  27  through it to enter compartment  13  and react with heat generating material  25 , as described below. 
         [0026]    Body  49  has a second slot  53  that functions to allow steam or other gasses generated in compartment  13  during the reaction of heat generating material  25  with activation material  27  to travel up body  49  and into upper chamber  11  to exit through opening member  17  through exhaust hole  55 . 
         [0027]      FIGS. 5 and 6  illustrate the use of access element  29  in device  10 .  FIG. 5  illustrates device  10  before activation and  FIG. 6  illustrates device  10  after activation. 
         [0028]    In  FIG. 5 , access element  29  is inserted into opening member  17  and positioned above hole  55  that is sealed by membrane  57 . At this point, heat generating material  25  is isolated from activation material  37 . An insulating layer  31  is located on the back side of device  10  and the other side is not insulated, so the heat generated will go through the front or not insulated side of  FIG. 1 . 
         [0029]    In  FIG. 6 , access element  29  has been fully inserted into device  10 , rupturing or penetrating membrane  57  and further extending down to puncture the lower end  15   c  of divider  15 . At this point, the activation agent  27 , not shown for simplicity but shown in  FIG. 1 , passes through first slot  51  from chamber  11  into chamber  13 , and begins to react with heat generating material  25 , again shown in  FIG. 1 . Heat generating reactions such as those describe below and contemplated for device  10  will generate steam or other gaseous byproducts. The reaction, at point  61  in chamber  13 , generates gas or steam that flows from the reaction point  61  into first slot  51 , up central bore  41 , through second slot  53  and into chamber  11 . If the pressure in chamber  11  increases, the steam or gas may also flow up central bore  41  and out hole  55 . Because the end  45  of access element  29  is recessed in opening member  17 , the steam does not directly heat anything that might adversely affect someone using device  10 . Arrow  63  describes generally the path of the steam. 
         [0030]    In operation, referring again to  FIGS. 1 and 2 , an object to be heated,  71  in  FIG. 7 , is placed on the front face of device  10  shown in  FIG. 1 . In a preferred embodiment, object  71  is about ½ the size of device  10 , so that device  10  can be folded to put object  71  in contact with both halves of the front of device  10 . The folded device  10  is then secured by placing tab  33  in attaching contact with back  31 . In a preferred embodiment, tab  33  has a look and latch element that engages nonwoven back  31  to thus hold object  71  in contact with device  10 . When it is desired to heat object  71 , access element  29  is inserted into device  10  to function as described above and generate sufficient heat to achieve the desired temperature. 
         [0031]    The preferred activating material of this invention is water. This is plentiful and safe, and reacts with a number of materials to produce an exothermic reaction. The activating material may include a small amount of an added liquid chemical that extends the time that water can hold the heat once it is generated. Ethylene glycol is a preferred liquid chemical heat holding agent. The amount of ethylene glycol may range from about 0.2% by weight to about 2.0% by weight, the percentages being based upon the weight of the water. 
         [0032]    The preferred heat generating material is a solid formed from several components that, when free from moisture, are stable for up to three to five years or more, and which react when moisture is present to generate heat. The preferred solid is made from crystalline calcium oxide, a zeolite powder, and a polyalkyl glycol such as polyethylene glycol. The amount of activation material, such as water, is preferably from about 75 to 125 weight percent, based upon the total weight of heat generating material. Approximately equal amounts by weight of water and heat generating material is the preferred ratio of these reaction components. 
         [0033]    The amount of calcium oxide ranges from about 30 to 70 weight percent, the amount of polyethylene glycol ranges from about 15 to about 35 weight percent, and the amount of zeolite ranges from about 15 to about 35 weight percent, based on the total weight of heat generating material. Preferred is about 25 weight percent each of the polyethylene glycol and zeolite and about 50 weight percent calcium oxide. 
         [0034]    The heat generation material most preferred, using the above components includes a calcined calcium oxide. This material is available as a small particle size, with a diameter less than about 0.2 mm, and as a particle of somewhere between 0.2 and 0.8 mm. Larger particles are ground and smaller ones sieved, and the calcium oxide is then calcined. It has been found to be effective to calcine for at least 60 to 120 minutes, and preferably about 90 minutes, at temperatures above 500° C., and most preferably at about 550° C. for that period of time. The calcined calcium oxide is, of course, desiccated to prevent any contamination by moisture. 
         [0035]    More than 150 zeolite types have been synthesized and 48 naturally occurring zeolites are known. They are basically hydrated alumino-silicate minerals with an “open” structure that can accommodate a wide variety of positive ions, such as Na+, K+, Ca 2 +, Mg 2 + and others. These positive ions are rather loosely held and can readily be exchanged for others in a contact solution. Some of the more common mineral zeolites are: analcime, chabazite, heulandite, natrolite, phillipsite, and stilbite. An example mineral formula is: Na 2 Al 2 Si 3 O 10 -16H 2 O. Zeolites, by their nature, are finely porous structures that are “hungry” for water and that have the ability to hold heat. In the present invention, the activation agent, water in the preferred embodiment, enters into the zeolite pores, trapping the water as it is heated by reacting with the calcium oxide, thus storing heat, providing a longer, more evenly distributed supply of useable heat. 
         [0036]    The polyethylene glycol component of the heat generating material is admixed with the calcium oxide and zeolite and placed in the outer container as described above. When the activation agent, water, is introduced into the heat generating material, the polyethylene glycol coats the calcium oxide and zeolite, further delaying the exothermic reaction between calcium oxide and water, and adding to the utility of this invention. 
         [0037]    The heater of this invention has been used to heat products such as MRE packages to 150° F. within 5 minutes and maintained the heat at or above 140° F. for 50 minutes. Prior art devices take 12 minutes to reach only 140° F. and only hold that temperature for 20 minutes. Thus the food can be cooked and kept warm for more than enough time to consume it. 
         [0038]    Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.