Patent Document

BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to a free standing fireplace hearth and a fuel composition for use therein.  
           [0002]    In many patio, deck, back yard or other similar outside settings, an actively burning fire is often used to add significant ambiance to the setting. In addition to the visual appearance of the fire, the setting is enhanced by the soothing and pleasing crackling and popping sound of a wood burning fire. However, wood burning fires of this type often require significant attention to periodically add logs to maintain the fire. Wood burning fires generate a significant amount of ash, soot and the like thereby requiring clean up. Further, open kettles or the like which are commonly used to house the burning logs present a significant hazard and often do not adequately contain the fire during use thereby leading to the potential and dangerous spread of the fire through falling and burning logs, cinders or the like. Constant attention to the fire is thereby prudently required.  
           [0003]    Therefore, there is a need for an improved outdoor fireplace or hearth which avoids these above-described drawbacks while still offering the visual and audible ambiance of a burning wood fire.  
           [0004]    In a further aspect of the invention, it is highly desirable to provide a self-containing fire hearth which provides the ambience of a wood burning fire, that is a flame which has the appearance and sound of a wood burning flame, but without the necessity of wood fuel or cleanup of waste combustion products usually attendant a wood-fueled fire. Moreover and in this regard, it will be appreciated that an “ambience” fire or flame need not be measured by the typical parameters applied to a fire. For example, heat output, or BTUs, is a typical fire or heat performance criteria as is the heat producing efficiency from the fuel used. In a free-standing fire or hearth for ambience purposes, these parameters and efficiencies are relatively unimportant. In the case of heat production, the less heat produced, the better.  
           [0005]    What is important are entirely different characteristics, namely burn time, fuel volume and burn characteristics. Thus, the efficiency of a decorative or ambient fire, for example, is measured in consideration of these parameters and their coalescence to provide the most desirable aesthetic result, with an acceptable burn time, at the least operational cost.  
           [0006]    For example, acceptable burn characteristics require a fire with golden colored flame having random dancing patterns. A desirable burn time per fuel load is in the two to four hour range and the fuel cost per unit used should be low, compared to other systems within the above parameters.  
           [0007]    Accordingly, it is a further objective of the invention to provide a freestanding fireplace hearth with an improved efficiency taking into account burn characteristics, volume of fuel used and burn time or duration per fuel unit consumed.  
           [0008]    A further objective of the invention has thus been to provide a freestanding fireplace hearth with improved flame color and burning sound like a wood burning fire, at acceptable burn time and fuel volume used.  
         SUMMARY OF THE INVENTION  
         [0009]    This invention overcomes the above-described and other drawbacks of known fireplace or hearth systems while still offering a visually and audibly pleasing safe live fire and associated ambiance in an outdoor setting.  
           [0010]    In a presently preferred embodiment, the invention includes a free standing fireplace hearth for burning a fuel to provide an attractive ambiance fire in an outdoor setting. The fireplace hearth includes a base having a fuel tray defining a chamber slidably mounted therein on a drawer-like structure for movement between open and closed configurations and a spring biased latch to releasably secure the tray in the closed configuration. The tray is configured with a throat as an integral part of the overall combustion system as will be described. A snuffer or burner is disposed in the hearth over the tray and provides flaps or dampers for controlling the flame height and for snuffing out the flame as desired. The tray is mounted for movement on the drawer structure between a lowered and a raised position. A plurality of cams are pivotally oriented with respect to the tray. A stop is mounted on the base relative to the tray so that as the tray approaches the closed configuration, the tray abuts against the stop. Continued movement of drawer rails on which the tray is mounted toward the closed configuration activates the cams and thereby elevates the tray relative to the snuffer into the raised position and in operative contact with the snuffer.  
           [0011]    A log set of fiber/ceramic or other wood simulation material is operably disposed over the snuffer. Flame from the snuffer dances up through passages in the log set which has features which glow. Air moving up the passages produces lift to enhance the burn characteristics of the flames.  
           [0012]    A pair of spaced dampers or shutters are mounted for movement to and between a closed snuffing configuration and a fully open burn configuration. Each of the damper shutters are coupled via a linkage to a rotational control knob such that rotation of the control knob in a first direction pivots the damper shutters toward the closed snuffing configuration to extinguish the burning fuel. Rotation of the control knob in a second opposite direction pivots the damper shutters toward the fully open configuration to increase the flame height through the log set.  
           [0013]    A plurality of posts extend upwardly from the base to support a roof. The roof includes a heat shield mounted on the interior thereof to deflect hot air generated by the burning fuel from impinging upon the roof and thereby maintains the roof at a lower temperature than the heat shield during fuel burning. At least a portion of the heat shield is spaced from the roof to define space for an insulation layer of air between the heat shield and the cover. A plurality of baffles are included on the heat shield to direct the heat out from under the roof, off of the heat shield and cooler air into the insulation layer of air between the roof and the heat shield.  
           [0014]    The present invention in another aspect includes a specific composition of fuel which is suitable for use in the free standing fireplace hearth. The fuel in a presently preferred embodiment is a gel composition which satisfies the characteristics of fireplace fuel with respect to aesthetic features such as producing golden high luminous flame without producing an offensive odor or smoke while still generating a crackle and pop sound. Further, the fuel is safe for handling and storage purposes and the formulation is of generally non-toxic components as well as being self-contained if spilled, environmentally safe in burning, producing minimal pollutants and being readily extinguishable without any smoke buildup. Further, the burnt fuel does not produce any significant amount of residue or the like.  
           [0015]    Accordingly, it will be appreciated that the fuel tray, the fuel chamber throat in the tray, the snuffer with its dampers and the log set combine to define a combustion system producing a flame having the random pattern appearance of a wood flame with desirable burn time and low fuel volume requirements.  
           [0016]    In brief, the combustion system performs or acts something like a carbueration system.  
           [0017]    When the drawer is shut the fuel chamber mates or couples with the snuffer assembly to complete the combustion system and also acts as a way to extinguish the flame. Air is mixed with the fuel. The fuel vaporizes in the fuel chamber and the air-alcohol gas mixture rises or moves through the throat out of the chamber via a plurality of flame paths created by a wedge-shaped, diverter of the snuffer and the openings on top of the snuffer assembly. The damper or doors control the height of the flames and also act when closed to snuff out the flame. The log set is decorative. As the flames move through the log set, they actually warm the log set material causing it to glow when touched by flame. The flames move through the log set with as little impingement as possible so that sooting is kept to a minimum. The passages in the log set warm up and cause convection of additional ambient air up through the passages so the fire or flame is decoupled and is lifted up therethrough. The system is self-regulating, so as the user adjusts the dampers, increasing or decreasing the size of the flame, the combustion system continues to work the same way.  
           [0018]    A preferred fuel according to the invention is a gel composition, or mix of a lower alkyl alcohol, water, flammable organic tertiary butyl alcohol and double or single walled microencapsulated solvents, gelling agent, polyacrylic acid, cross linking agent and surfactant. Such a fuel as described herein, when used in the hearth described herein, produces desirable burn characteristics over an acceptable burn time and with an acceptable fuel volume required. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    The objectives and features of the invention will become more readily apparent from the following detailed description taken in conjunction with the accompanying drawings in which:  
         [0020]    [0020]FIG. 1 is a perspective view of the invention showing in phantom a withdrawn fuel tray for fueling;  
         [0021]    [0021]FIG. 2 is a front elevational view of the invention of FIG. 1;  
         [0022]    [0022]FIG. 3 is a side elevational view of the invention of FIG. 1;  
         [0023]    [0023]FIG. 4 is a rear elevational view of the invention of FIG. 1;  
         [0024]    [0024]FIG. 5 is a plan view of the invention of FIG. 1;  
         [0025]    [0025]FIG. 6 is a bottom view of the invention of FIG. 1;  
         [0026]    [0026]FIG. 7 is a cross-sectional view taken along lines  7 - 7  of FIG. 1 showing the fuel tray in closed, operational position;  
         [0027]    [0027]FIG. 7A is a view of the fuel tray and its drawer mount similar to FIG. 7, but showing only the tray, drawer components and snuffer in lowered partially opened position;  
         [0028]    [0028]FIG. 8 is a cross sectional view taken along lines  8 - 8  of FIG. 7 with certain components removed for clarity;  
         [0029]    [0029]FIG. 9 is a cross sectional view taken along lines  9 - 9  of FIG. 7A with certain components removed for clarity;  
         [0030]    [0030]FIG. 10 is a perspective view showing the tray, drawer components and snuffer of FIGS. 1, 7A and  9 ;  
         [0031]    [0031]FIG. 10A is a perspective view of the upperside of the fuel tray and drawer of the invention,  
         [0032]    [0032]FIG. 10B is a perspective view of the underside of the hearth showing fuel tray and drawer components of the invention;  
         [0033]    [0033]FIG. 10C is a perspective view of the forward end of the fuel tray and drawer of the invention viewed from a rear perspective;  
         [0034]    [0034]FIG. 11 is a perspective view of the roof and heat shield of FIGS.  1 - 7 ;  
         [0035]    [0035]FIG. 12 is a perspective view of a corner structure of the invention as shown in FIG. 1;  
         [0036]    [0036]FIG. 13 is a diagrammatic elevational illustration of the combustion systems of the invention of FIG. 1; and  
         [0037]    [0037]FIG. 14 is a diagrammatic perspective illustrative of a log set used in the hearth of FIG. 1. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0038]    Referring to the figures, presently preferred embodiments of a free standing fireplace hearth  10  according to this invention are shown. The hearth  10  is intended for outdoor use and is free standing and portable as needed.  
         [0039]    The hearth  10  includes a base  12  with four downwardly projecting legs  14 , each of which include a rotationally adjustable foot  16 , all of which in combination could be used to level the base  12  and the hearth  10  as appropriate. An upwardly extending post or column  18  is mounted proximate each corner of the base  12  and the posts  18  in combination support a roof  20 . The roof  20  includes a centrally located vent cap  22  secured to and spaced from the roof  20  to provide for the free flow of air therebetween. A support arch  24  is mounted between each pair of adjacent posts  18 . A plurality of preferably artificial, although realistic appearing, logs making up log set  26  (FIGS. 13, 14) are positioned atop the base  12  within the hearth  10 . Log set  26  includes side logs  27 ,  29  and a center log  31 , for example.  
         [0040]    It will be appreciated that posts  18  are preferably formed, hollow columns having in two adjacent sides slots  19  and  21  (FIG. 12). Also, each slot is provided with a groove  23  in a bottom of the slot and extending a short distance downwardly.  
         [0041]    On assembly, the corner posts  18  are secured in appropriate recesses in base  12 . A resilient tube, gasket or bumper is inserted into a lower end of slot  19 ,  21  to resiliently support a preferably transparent panel  17 , such as glass or plastic slid downwardly to the bumper in the slots so the bottom edge of panels  17  are spaced from base  12 . Thereafter, a tenon end  25  of a support arch  24  is slid into grooves  23  to lock the arches  24  in place and columns  18  together, the bottom of grooves  23  supporting the arches  24  above the glass panels  17  in slots  18 ,  21 .  
         [0042]    The roof  20  is provided with corner projections  15  (FIGS. 11, 12) which then fit into the top ends of corner columns  18  for securing the roof  20  and heat shield  68  thereon.  
         [0043]    It will be appreciated that hearth  10  includes a floor  13  extending across the base  12  and alongside snuffer  42 . Floor  13  may comprise two formed components of aluminum, metal, ceramic or other suitable material on each side of snuffer  42 . One suitable, but not necessary material for the floor is a material manufactured by The Foundry in Toronto, Canada, under the name “Cool Crete”.  
         [0044]    A drawer structure  28  is slidably mounted in the base  12  for movement to and between a closed configuration (FIG. 9) and toward an open configuration (FIG. 8). The drawer structure  28  is slidably mounted on rollers  38 . Rear rollers  38  are mounted on drawer rails  44 ,  45  and forward rollers  38  (FIG. 10B) on stationary slide rails  55   a  and  55   b.    
         [0045]    A control knob  30  projects from the base  12  for adjusting dampers  32 ,  33  to control flames resulting from burning fuel  34 . Mounted within the drawer  28  is a fuel tray  36  defining a fuel chamber  37  for holding the vaporizing fuel  34 . Tray  36  also defines a constricted throat  39  tapering inwardly over chamber  37 .  
         [0046]    The tray  36  is movably mounted on the drawer structure  28  for movement to and between a lowered position (FIG. 7A) when the drawer is moved toward an open configuration (FIGS. 7A and 8) and a raised or closed position (FIGS. 7 and 9). In the raised position, spaced uppermost flanges or lips  40  of the tray  36  are placed into operative sealing engagement with lower flanges or lips  48  (FIG. 7) of a snuffer  42  mounted within the base  12 . The tray  36  in the raised sealing configuration inhibits air from entering between the lips  40  and flanges  48  during operation of the hearth  10  and allows extinguishment of the fire when desired by operation of the snuffer dampers  32 ,  33 .  
         [0047]    The tray  36  is operatively coupled to the slidable drawer  28  by way of a cam mechanism comprising, for example, cam followers  49  mounted on tray  36  and cam slots S 1  (FIGS. 8, 9) disposed in slidable drawer rails  44 ,  45  (FIG. 7A). As shown, cam followers  49  comprise a cam follower portion  49   a  and an enlarged flange  49   b  outwardly thereof (with respect to tray  36 ) to maintain the cam followers in the slots  51  in the rails  44 ,  45 .  
         [0048]    When the drawer  28  is pushed inwardly or rearwardly, the back end of the tray  36  engages a stop  46 . Continued rearward movement, however, of rails  44 ,  45  pushes the cam slots  51  under or across the followers  49 , raising them, and thus tray  36 , upwardly toward snuffer  42 , where lips  40 ,  48  engage effectively to cut off air passages therebetween.  
         [0049]    In an alternative embodiment (not shown) the tray  36  is coupled to the drawer  28  by a plurality of links which are pivotally coupled at a first lower end to the tray and at a second upper end to the drawer  28 . As the drawer slides or rolls from the open configuration toward the closed configuration, a back end of the tray  36  approaches a stop  46  (see FIG. 9) mounted on the base  12  so that as the drawer approaches the closed configuration, the tray abuts against the stop. Continued movement of the drawer  28  toward the closed configuration thereby pivots the links  44  toward a more vertical orientation. Since the tray is prevented from translating in a generally horizontal direction, it rises vertically on the links into sealing engagement with the snuffer through the continued lateral movement of the drawer inwardly or rearwardly towards the closed configuration.  
         [0050]    Once the drawer  28  is in the closed configuration and the tray  36  is in the raised position, the drawer  28  is maintained in the closed configuration by a spring biased latch  50  which engages holes  52  in a keeper plate  54  of the stationary slide rails  55   a ,  55   b . To open the drawer, a user grasps a catch or arm  56  on the latch  50  to thereby pivot the latch out of engagement with the keeper plate  54  and permit the drawer  28  to be pulled open and the tray  36  lowered as the cam followers  49  descend in slots  51  when drawer  28  is pulled out so the tray is at least partially exposed for filling.  
         [0051]    As shown in the figures and particularly FIGS. 8 and 9, the control knob  30  is mounted on a shaft  58  for pivotal movement to adjust the position of spaced dampers  32 ,  33  of the snuffer  42 . These are mounted for movement to and between a closed snuffing configuration and a fully open configuration (dotted line in FIG. 13), with intermediate burning positions adjusting the size of the respective openings in the snuffer  42  and thus any flame height. Such control movement of dampers  32 ,  33  is illustrated by arrows A, B in FIG. 7. The dampers  32 ,  33  are coupled via a pivotable linkage  62  to the shaft  58  so that upon rotation of the shaft  58  by the control knob  30 , an upper edge of the damper shutters moves into or out of engagement with an upper edge  65   a ,  65   b  of a V-shaped diverter  64  of snuffer  42  extending generally parallel to the shaft. Similarly, rotation of the control knob and shaft moves a lower edge  32   a ,  33   a  of each damper  32 ,  33  toward or away from a flange  66   a ,  66   b . In this regard, the damper could be pivoted. Preferably they are slotted to receive pins  67  for motion as described. When the dampers  32 ,  33  are engaged with the adjacent structure as described, in closed configuration, and fuel burning is thereby extinguished. Alternatively, adjustment of the position of the dampers  32 ,  33  controls the air flow to the flame for regulating the intensity and height thereof. The dampers  32 ,  33 , diverter  64 , flanges  66   a ,  66   b  and related structure combine to form a flue or controller for the burning fuel.  
         [0052]    Of course, while specific drawer and motion compartments have been described, and other suitable components could be used, it will be readily appreciated that a preferred embodiment of the invention comprises a fuel tray  36  which can easily be unlatched and drawn forwardly or outwardly of hearth  10  for loading of a gel fuel  34  (to be described) or other suitable fuel.  
         [0053]    Thereafter, the drawer  28  and tray  36  are pushed rearwardly into hearth  10  and the tray is lifted by the ending motion of the return to operative engagement with a snuffer  42 .  
         [0054]    It will be appreciated that the lower flanges  48  of the snuffer are engaged with upper flanges or lips  40  of the tray  36  to effectively seal the chamber  37  so the snuffer  42  is operable to extinguish flame therefrom when dampers  32 ,  33  are closed.  
         [0055]    A projection  35  of knob  30  extends downwardly and blocks outward motion of drawer  28  and tray  36  unless the knob  30  is positioned to close openings  60 ,  61  in a snuffer  42  with dampers  32 ,  33  (FIG. 8). Thus, for all operable open or “burn” positions of dampers  32 ,  33 , knob  30  and projection  35  block outward movement of drawer  28 . This prevents the opening or withdrawal of fuel tray  36  when any flame is burning.  
         [0056]    Shaft  58  is engaged by a double spring clip  59  which frictionally maintains the rotary position of shaft  58  and thus that of linkage  62  and the damper position, once set.  
         [0057]    It will be also be appreciated that stationary rails  55   a  and  55   b  are secured to base  12 . Rollers  38  are oriented on the rear ends of drawer rails  44 ,  45  and ride in the stationary rails  55   a  and  55   b , respectively. Forward rollers are mounted on the stationary rails  55   a  and  55   b  and support the drawer rails  44 ,  45  so those rails are easily pulled and pushed outwardly and inwardly as described, carrying tray  36 . Also, it will be appreciated that tray  36  moves with respect to drawer rails  44 ,  45  after the tray is stopped by stop  46 , in order that it is raised toward snuffer  42 .  
         [0058]    A strap  53  (FIG. 10B) is disposed to secure stationary rails  55   a ,  55   b  from separating apart.  
         [0059]    The roof  20  of the fireplace hearth  10  includes a single piece heat shield  68  (FIGS. 7 and 11) mounted interiorly thereof to deflect hot air generated by the burning fuel from impinging upon the roof  20 . This maintains the roof at a lower temperature to avoid someone being burned by touching the roof  20  during operation of the fireplace hearth  10 . The heat shield  68  is spaced from the roof  20  to thereby provide an insulation layer of air  70  between the heat shield and the roof  20  and further minimize the transfer of heat to the roof  20 . Additionally, around the perimeter of the heat shield  68 , a raised baffle  72  is provided which terminates at the corners of the heat shield at slits  74  defined by the space between edges  75  of roof  20  and  76  of heat shield  68  (FIG. 7). A tongue  77  connects the heat shield  68  to the roof  20  at each of the four corners. This structure allows for the hot air from the fire which impinges upon the heat shield to be directed outwardly and downwardly away from the roof  20 . Furthermore, the baffles  72  and slits  74  between the roof  20  and the heat shield  68  allow for cooler air to be drawn into and circulate around the roof  20 , entering the space between the heat shield and the roof  20  to provide the insulation of air  70  therebetween. Furthermore, air which is warmed in the insulation layer  70  rises and escapes between the cap  22  and the roof  20  and is replaced by cooler air drawn in by slits  74 . It will be appreciated that the passage from slits  74  to caps  22  are unobstructed, allowing a free flow of air between roof  20  and shield  68  with the only contact between them at the corners. This helps keep roof  20  from becoming too hot.  
         [0060]    Log set  26  is diagrammatically illustrated in FIGS. 1, 13 and  14 . It may be made of a fiber and ceramic material or any other suitable material for this use. The log set  26  may be formed in one piece or in a plurality of separate pieces, fitted or joined together to provide the appearance of authentic logs. FIGS. 13 and 14 illustrate side logs  27 ,  29  and a center log  31 , for example, for illustrative purposes only.  
         [0061]    However formed, the log set has a plurality of passages. Two of these are illustrated at  79 ,  80  (FIG. 13). These passages have respective entry ends  81 ,  82  and outlet ends  83 ,  84 . Entry ends  81 ,  82  are disposed proximate the openings  60 ,  61  in snuffer  42  for receiving flames therefrom, the flames extending upwardly through passages  79 ,  80  to and through outlets  83 ,  84 .  
         [0062]    It will also be appreciated that inlets  81 ,  82  are disposed or oriented such that ambient air can be drawn into the inlets, mixing with the flames, decoupling the flame, and lifting the flame up through the log set  26 . Further, it will be appreciated that the outer logs  27 ,  29  could be lower than the center log  31 . In any event, the top edges of dampers  32 ,  33  form a gap (changing when the dampers are moved) between the dampers and the logs  27 ,  29  respectively. This gap allows air into inlets  81 ,  82  to decouple and lift the flames through passages  79 ,  80 .  
         [0063]    As the flame moves up passages  79 ,  80  they heat the surrounding log set material and this heating produces a convection effect, drawing outside air  85 ,  86  into the passages  79 ,  80  and into the flames. The amount of heat so generated and the resulting convection effect produced is controlled by the flames which are in turn controlled by the position of dampers  32 ,  33 . The drawing in of decoupling air is thus self-regulating as a function of flame control by the dampers  32 ,  33 , and as a function of the gap between top edges of the dampers and either the logs or any adjacent floor structure.  
         [0064]    While only two passages  79 ,  80  are shown in FIG. 13, there may be numerous passages through the log set  26 , such as the passages  1 - 5  in FIG. 14. As shown, it is desirable that the passages are generally oriented to reduce actual flame contact on the log set material and thereby reduce sooting of the surfaces. The manner of the formation of the log set  26  or of its individual components at this interconnection is not a part of this invention. The passages such as  79 ,  80  can be formed through the log components or therebetween as desired. Preferably, there is an elongated space between the respective outer or side logs  27 ,  29  and center log  31 . This space (passages  79 ,  80  for example) are open at the bottom near snuffer  42 , but may be bridged at the top by contact of the side logs  27 ,  29  with the center log.  
         [0065]    Having explained and described the structural features and operation of the fireplace hearth according to presently preferred embodiments of this invention, the fuel  34  which is particularly adapted for use in the fireplace hearth comprises an additional aspect of the present invention. Specifically, the fuel for use in the present invention is a gel composition which satisfies the characteristics of fireplace fuel with respect to aesthetic features such as producing a golden high luminous flame without producing an offensive odor or smoke and generating a crackle and pop sound. The fuel is safe for handling and storage purposes and is formulated from generally non-toxic components. The fuel is self-contained if spilled, environmentally safe in burning, producing minimal pollutants and readily extinguishable without any smoke build-up. Further the product does not produce any significant amount of residue.  
         [0066]    The gel composition for use in the present invention is a mixture of a lower alkyl alcohol preferably ethanol, water, a flammable organic composition which produces a golden flame, such as an aliphatic hydrocarbon preferably with an aniline point above 180° F. (such as odorless mineral spirits). Tertiary butyl alcohol also produces a yellow flame and stabilizes the gel. The gel composition also includes cross-linked and double-walled microencapsulated solvents such as toluene, xylene, etc. and a gelling agent such as water and a minor amount of polyacrylic acid or polyacrylate, along with a cross-linking agent and a surfactant. This is neutralized to a pH of 6-10 with a basic amine such as triethanolamine, diethanolamine, Ethomine (manufactured by Sonobel) and other organic bases.  
         [0067]    The gel formulation has a viscosity of 500,000 cps or higher in a high yield value fuel with excellent suspending properties. The aliphatic hydrocarbons produce the golden yellow flame without producing smoke or soot when burned unlike normal characteristics of aromatic compounds.  
         [0068]    A preferred formulation includes:  
                                                                                                                 Preferred               Ingredients   % by Weight   % Range                                        Ethanol anhydrous   58.5   50 to 65           proprietary Polyacrylic acid   0.5   0.2-1.2           (Carbopol E21 from           BF Goodrich)           Water   28.5   25-38           Aliphatic hydrocarbons   6.84   2-15           (odorless mineral spirits)           Tertiary Butyl Alcohol   5.16   0-12                Denatonium Benzoate   40 ppm   40 ppm           (bittering agent, for safety)           Triethanolamine   0.4   0.3-1.0           dye   5 ppm   2-30 ppm                Toluene/Xylene   0.1   0.1-1.0           capsules   100                      
 
         [0069]    The product is formulated by combining the polyacrylic acid with water to wet the polyacrylic acid. The remaining components are added into the mix under agitation. The process is completed by neutralizing the excess acid and further mixing for uniformity of the product by pumping (recirculation) of product through an in-line static mixer.  
         [0070]    Preferably the solvent microcapsules are cross-linked and double-walled complexes formed by coacervation. Single walled complexes could be used. The cross linked gelatin double wall forms about 30% of the capsule weight. This prevents permeation of the solvents to provide a long shelf life. Further, the capsules should have a size greater than 500 microns, preferably 600 to 1500 microns with 50% or more of the capsules being 900-1200 microns.  
         [0071]    Further the solvent in the microcapsule is an aromatic solvent preferably a lower alkyl aromatic solvent such as toluene or xylene having a vapor pressure of 5 to 15 millimeters mercury at 68° F. and a boiling range of 300-325° F. This produces the best crackling sound during burning.  
         [0072]    This formulation is readily soluble in water making it easy to clean without leaving any stain on the carpet or flooring materials. Further the product is made safe to handle.  
         [0073]    In an alternative embodiment of the fuel, the tertiary butyl alcohol (TBA) is omitted and the aliphatic hydrocarbon (odorless mineral spirits) is increased to about 12% by weight. This aids in reduction of the flame point temperature of the fuel when that might be desired, but may exhibit a small problem of separation of some of the components.  
         [0074]    Turning now to FIGS. 13 and 14, the preferred combustion process provided by the invention produces a flame with a random dancing pattern, of golden color as if burning from wood fuel, a crackling authentic wood burning sound, with minimal use of fuel and over a burn time of about 2-4 hours, depending on the position of dampers  32 ,  33 .  
         [0075]    Initially, a load or unit of fuel  34  is introduced to tray  36 . An amount of about  64  ounces of fuel  34  is appropriate to fill tray  36 , pulled out from base  12 , to a level as illustrated in FIG. 13. Thereafter, the drawer  28  and tray  36  are pushed into the hearth  10 . The lateral motion of tray  36  is stopped while slides or rails  44 ,  45  continue rearwardly, as previously described. This cams the tray  6  up into operative engagement with the snuffer  42  and the drawer  28   10  and tray  36  are latched in this position.  
         [0076]    Knob  30  can now be turned to open dampers  32 ,  33 . Vaporization of fuel  34  occurs and the fuel vapor rises from tray  36  up through its throat  39  where it is constricted toward snuffer  42 . The vapors are diverted by diverter  64  through openings  60 ,  61  between the diverter  64  and dampers  32 ,  33 .  
         [0077]    When the vapors are lit by a suitable ignitor, flame is produced. This flame appears at the snuffer and rises upwardly toward passages  79 ,  80 . As the log set  26  heats, the heat draws air ( 85 ,  86 ) into the entry ends of the passages  81 ,  82  between the dampers  32 ,  33  and the logs or any adjacent floor  13  (not shown) which may be situated just to the side and beneath the logs. This convection air decouples the flame from the snuffer  42  and tray  36  and helps lift the flame upwardly through and above log set  26 .  
         [0078]    At the same time, air  87 ,  88  is drawn or convected upwardly around tray  36 , cooling the tray and keeping fuel from becoming too hot and thus regulating its vaporization.  
         [0079]    Dampers  32 ,  33  can be moved through manipulation of knob  30 , turning shaft  58  and moving linkage  62  through various burn positions regulating the flame produced. Movement of dampers  32 ,  33  to restrict openings  60 ,  61  reduces the flame height and movement of dampers  32 ,  33  to enlarge openings  60 ,  61 , permitting passage of more fuel vapor, enlarging the flames and opening the side passages between dampers and logs on floors for more decoupling air.  
         [0080]    For all positions of knob  30  wherein dampers  32 ,  33  are open, knob projection  35  restricts outward lateral motion of tray  36  and drawer  28  so that it cannot be extended out of hearth  10  while fuel is burning. When knob  30  is turned to move dampers  32 ,  33  to close off openings  60 ,  61  and snuff out any flame, projection  35  is moved away from its tray and drawer blocking position. This allows refueling.  
         [0081]    When the dampers  32 ,  33  are moved to fully open openings  60 ,  61 , maximum flame height and a shorter burn time of about two hours results. When dampers  32 ,  33  are moved to restrict openings  60 ,  61  to the lowest suitable flame, an extended burn time of about four hours is provided by the  64  ounce fuel unit.  
         [0082]    This combustion system thus operates like a carbureation system, wherein the fuel vapors are concentrated by throat  39 , throttled at dampers  32 ,  33  and then boosted, in flame, by the decoupling air.  
         [0083]    While not restricted to any particular sizes, one combination of sizes of various components found suitable is as follows. Of course, these dimensions are approximations for purposes of clarity of description and may be varied in production.  
         [0084]    Fuel tray  36  is about 12 inches long measured between two  10  tray end panels about 4⅝ inches wide at its bottom. Sides  89 ,  90  of tray  36  extend up from bottom  91  and outwardly at an angle from the horizontal of about 100 degrees, for about 1½ inch. Throat panels  92 ,  93  then taper inwardly from upper edges of side  89 ,  90  for about 1 inch at an angle of about 35 degrees from the horizontal. From the inner edges of throat panels  92 ,  93 , the throat panels  94 ,  95  extend upwardly and outwardly for about 1½ inches at an angle of about 5 degrees from the vertical to the tray lip or flange  40 . Overall vertical height of the tray  36  from bottom  91  to flanges  40  is about 3½ inches. The throat  39  at the top of the panels  92 ,  93  is a little over 3 inches wide. When filled with a preferred unit of fuel  34 , the filled fuel level is just below the junction of panels  89 ,  90  with throat panels  92 ,  93  respectively.  
         [0085]    The snuffer  42 , at its opening to tray  36  through throat  39  is about 12 inches long and that snuffer opening is preferably slightly larger than the upper opening of the throat  39  between the upper edges of panels  94 ,  95 . The openings  60 ,  61  in snuffer  42  are about 12 inches long and a little over one inch wide, resulting in a cross-sectional area of about 13 square inches for each opening  60 ,  61 .  
         [0086]    As noted, there are preferably numerous passages, such as passages  79 ,  80  up through log set  26 . Fire passages  1 - 5  are shown in FIG. 14. These passages are positioned in the log set to give the aesthetic appearance of an authentic wood fire by means of bridges over the logs. At the bottom of the passages  1 - 5  (i.e. such as  78 ,  80 ) the entry openings  81 ,  82  defining a restrictive log out-take ( 81 ,  82 ) are about 12 inches long and about ½ inches wide. The logs themselves are about 16 inches long. Thus, the restrictive log take out flow area is about 6 square inches on each side (FIG. 13). The air gap associated with these openings  81 ,  82  is formed by the dampers  32 ,  33  at their top edges and the logs or adjacent floor panels  13 . This gap is between about ¼ inches and ⅝ inches so that the effective decoupling air openings are about 12 inches long and vary from ¼ to ⅝ inches wide.  
         [0087]    These dimensions result in a combustion system which is self-regulating when the dampers are moved for the best efficiency for all burn positions. Of course, other dimensions, shapes and sizes of all components will be appreciated. Variations in the parameters of one combustion system component will or may vary the parameter of another component.  
         [0088]    From the above disclosure of the general principles of the present invention and the preceding detailed description of at least one preferred embodiment, those skilled in the art will readily comprehend the various modifications to which this invention is susceptible. Therefore, we desire to be limited only by the scope of the following claims and equivalents thereof.

Technology Category: 8