Abstract:
A solid fuel cooking device incorporates a combustion chamber bound by an open upper side and an open lower side and is substantially closed on four sides by a retaining wall. The combustion chamber is covered from above by a cooking surface grate and below by a solid fuel support grate where the fuel support is disposed within the retaining wall below and parallel to the cooking surface grate. A housing is attached to the exterior of the retaining wall creating an air space between the housing and retaining wall. The cooking device uses a unique arrangement of gas jets to ignite the solid fuel where the gas jets are mounted horizontally within the retaining wall below the fuel support platform, injecting the lit gas beneath the solid fuel positioned upon the fuel support.

Description:
FIELD OF THE INVENTION 
     This invention relates to a solid fuel cooking device, and more particularly to a hollow-walled solid-fuel-burning grill having improved means for starting, stopping, and maintaining the combustion of solid fuel within the combustion chamber, while keeping the exterior of the grill relatively cool. 
     BACKGROUND OF THE INVENTION 
     Prior solid-fuel-burning grills have utilized gas burner tubes as starters for logs with little success. The problems stem from the positioning of the burner tubes. Typically, these tubes have been placed centrally below the combustion chamber of the grill. Consequently, the openings in the tubes quickly become clogged with ash and drippings from the chamber and are thereafter abandoned as a method of igniting solid fuel. Without effective gas burner tubes it is common in the industry for cooks to ignite fuel either by a slower method such as the use of paper and kindling wood or by the use of various accelerants such as lighter fluid. The use of accelerants requires the cook to store the flammable material in the kitchen area where storage conditions are not ideal, and lead to various liability and insurance issues. Furthermore, cooks that rely on methods other than gas burner tubes for igniting the fuel are tempted to overbuild their fire so that they will not risk repeating the ignition process. Overbuilding leads to fuel waste and often requires the cook to douse the fuel with water to regulate the temperature of the overbuilt fire. 
     From a practical standpoint, previous solid-fuel-burning grill designs have suffered from the dual problem of inefficient fuel consumption and unwanted heat retention. Many current solid-fuel-burning grill designs have fire brick interiors where it is necessary to warm up the grill for approximately two hours before the grill heats evenly. Likewise, when the grill is no longer needed for cooking, a lengthy wait is necessary to cool the grill to a safe temperature to be left unattended. An additional drawback to these solid wall designs is that heat is conducted through the walls of the burning chamber and the exposed exterior of the grill is heated to unsafe temperatures during the course of the cooking period. Because the grill is imperceptibly hot cooks may be burned by touching the exterior of the grill, and the grill may not be placed adjacent to walls due to the potential fire hazard. 
     Finally, in commercial solid-fuel-burning stoves it is necessary to let the fire burn out at the end of the night and to leave a vented hood operating to blow the smoke from the restaurant. The fire brick interior walls of the stoves preclude completely dousing the fire with water. Burning out the fire requires someone to either remain at the restaurant to tend the fire or to leave the fire unattended overnight. Neither option is ideal, and again, places the owner/manager of the restaurant in the difficult situation of weighing convenience versus liability. In addition fuel is wasted in the burn-out process. 
     As such, a need exists for a solid-fuel-burning grill capable of being easily started by igniting gas jets, while also providing an efficient manner in which to terminate the cooking session. The present invention provides an efficient solid-fuel-burning grill, and keeps the exterior of the grill at a safe temperature. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide a solid-fuel cooking device including a combustion chamber bounded by an open upper side and being substantially closed on four lateral sides, the lateral combustion chamber sides being double walled. These double walled sides are constructed with open bottoms and air space that permits air to enter from the bottom and then as the air warms, to vent into the upper portions of the burning chamber. This continual flow of air within the double wall prevents the outer walls from overheating. In addition, in the lateral sides of the stove, not bearing a door, a third wall may be added in between the inner and outer walls to provide an even greater cooling/insulation effect. 
     It is also an object of the present invention to provide a solid-fuel cooking device having shielded natural-gas jets mounted horizontally on the interior of the combustion chamber for quick, safe, and efficient ignition of the solid-fuel. 
     It is a further object of the present invention to provide a solid-fuel cooking device having a timer connected to a solenoid to control the burn time of the natural-gas jets. 
     It is yet another object of the present invention to provide a solid-fuel cooking device with rotatable and removable combustion chamber doors to provide access to the combustion chamber and to permit easy cleaning. 
     It is still another object of the present invention to provide a solid-fuel cooking device that quickly reaches suitable cooking temperatures while using a minimum amount of fuel, and can be quickly extinguished to prevent the waste of fuel. 
    
    
     Other objects and advantages of the present invention will become apparent from the following detailed description when viewed in conjunction with the accompanying drawings, which set forth certain embodiments of the invention. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front plan view of a grill according to the present invention showing some interior features in phantom. 
     FIG. 2 is a top plan view of the grill of FIG.  1 . 
     FIG. 3 is a side plan sectional view of the lower portion of the grill illustrating the location of the solenoid and gas cock. 
     FIG. 4 is a side plan sectional view of the grill illustrating placement of an angle stiffener. 
     FIG. 5A is an isolated front view of a grill door and its associated hinge and hook apparatus. 
     FIG. 5B is a side view of the grill door and apparatus. 
     FIG. 6 is a view of the gas supply manifold in isolation. 
     FIG. 7 is a sectional view of the grill illustrating the air inlets and the direction of air flow through the grill. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning now to the drawings, and initially to FIG. 1 a solid fuel cooking device of the present invention is depicted in the form of grill  10 . The grill  10  comprises a housing  12 , which may be further subdivided into combustion chamber  19  and debris chamber  23 . The housing  12  includes front doors  16  which provide access to a fuel support platform  18  (shown in FIG. 2) by pulling on handle  80 . The front door  16  is best seen in FIG. 5 a . The door  16  is removable and is attached to the housing  12  by a hook-hinge  30   a  and hanger  31 . The hook-hinge  30   a  is attached to the exterior of the housing  12  slightly above the door opening  15  as shown in FIG. 5 b . The hook-hinge  30   a  angles upward and allows the hanger  31 , attached to one side of the front door  16 , to rest on the hook-hinge  30   a . A second hook hinge  30   b  holds latch  7 . The latch  7  may be pulled up and off the hook-hinge  30   b  to pivot the door on hook-hinge  30   a . The door may be completely removed from the housing  12  by pulling the latch  7  and the hanger  31  off the hook-hinges  30   a  and  30   b . Once the door is removed the combustion chamber  19  may be accessed with ease. 
     Referring to FIG. 2, the combustion chamber  19  is further defined by the fuel support platform  18  near the bottom of the grill  10 , and parallel to the cooking surface  14  near the top, and from side walls  33  and  35  extending upward from the perimeter of the fuel support platform  18  to the cooking surface  14 . Both fuel support platform  18  and cooking surface  14  are typically comprised of heavy metal grates. 
     Referring back to FIG. 1, the debris chamber  23  of grill  10  includes three collection trays  28  disposed immediately below the fuel support platform  18 ; however, any number of trays may be employed. The collection trays  28  function to collect both drippings from food placed upon the food cooking surface  14 , and spent fuel, ash and cinders from the fuel support platform  18 . A left gable  61  and right gable  62  are positioned above the adjacent sides of the three collection trays  28 . As best seen in FIG. 2 the gables  61  and  62  are attached to the interior of the front wall  11  and back wall  50 , below the fuel support platform  18 . The gables  61  and  62  serve to direct the ash and drippings away from the space between the sides of the collection trays  28  so that the waste is captured in the easily removable trays  28 . This design allows the grill  10  to have an open bottom allowing air to freely enter the combustion chamber  19  around the sides of the trays  28 . 
     As shown in the drawings, the housing  12  is supported by four legs  32  having casters  34 , which permits the grill  10  to be moved about as necessary. Additionally, the legs  32  may be adjustable to insure a horizontal elevation of the cooking surface  14 , and to permit the height of the cooking surface  14  to be altered according to preference. 
     As best shown in FIG. 2 the grill  10  is conveniently built in a rectangular configuration with an upper cooking surface  14 , on the top side of the cooking device. The cooking surface  14  comprises rectangular grate  13  adapted to support food to be cooked (meat, fish, fowl, vegetables, etc.) in the usual manner. 
     As with the cooking surface  14 , the fuel support platform  18 , at the bottom of combustion chamber  19  comprises grates  17  capable of supporting individual pieces of solid fuel, most typically hard wood logs. Grates  17  permit the flow of outside air from below the fuel support platform  18  up into the combustion chamber  19 , and thence to the cooking surface  14 . Both fuel support grates  17  and food cooking grates  13  are removably positioned relative to the housing  12  so that they may be easily removed for cleaning purposes, when desired. 
     Also illustrated in FIG. 2, are a plurality of gas jet housings  26 . The gas jet housings  26  are disposed below the fuel support platform  18 . These gas jet housings  26  may take the form of hollow pipes or tubes. The gas jet housings  26  are in communication with the burner manifold  65  and although six (6) gas jet housings  26  are shown, varying numbers of housings  26  may be used to good advantage in accordance with the size of the grill  10 . 
     As disclosed in the isolation view of burner manifold  65  in FIG. 6, the burner manifold  65  has a body  66  with a plurality of gas jets  67 . Each of the gas jets  67  rests inside a gas jet housing  26 . As shown in FIG. 7 the body  66  is mounted near the back  50  of the grill  10  below the fuel support platform  18  with the gas jets  67  facing the front interior wall of the grill  11 . The body  66  of the manifold  65  is welded to the support leg  32  using plug ends  68   a  and  68   b  to mount the weld  69  which consists of nut  70  and washer  72 . The gas supply inlet  73 , which supplies the entire manifold  65  with gas from gas source  60  shown in FIG. 3, is located at one end of the manifold  65 . The placement of the manifold  65  allows the gas jets  67  to be positioned below the fuel support  18 , clear of the retaining wall  22  such that flames from the jets  67  will enter the combustion chamber  19  and contact the fuel to be ignited. 
     Referring again to FIG. 2, the grill  10  includes outer housing  12  that substantially closes the grill  10  to form combustion chamber  19 . Generally defining the combustion chamber  19  are the left side wall  33  and right side wall  35  and back wall  50  and inner retaining wall  22  which is encompassed by the outer housing  12 . The inner retaining wall  22  and outer housing  12  form a double wall around the combustion chamber  19  creating an air space  21  where outside air may be drawn by convection action from openings located near the bottom of the grill  10 . This prevents the outer housing  12  from overheating. In a preferred embodiment, a third wall  39 , shown in FIG. 7 is located in the sides  33 ,  35  and back  50  of the grill  10 , between the retaining wall  22  and the housing  12  providing additional insulation effect to the exterior of the housing  12 . 
     The interior of the grill  10  is best seen in FIG. 7 illustrating the unique hollow-walled structure which allows the oven to heat and cool rapidly. The outer housing  12  and the third wall  39  are spaced by several “Z” plates  74 . The “Z” plates  74  are used to connect the third wall  39  to the side walls  33  and  35  and the back wall  50 . The front wall  11  does not contain “Z” plates  74  due to the presence of the front doors  16 . Grill railing  75  extends from side  33 ,  35 , back  50  and front walls  11 , and is not attached to the inner retaining wall  22 . This prevents the high temperatures reached in the combustion chamber  19  from transferring heat to the railing  75 . Because cooks may accidentally touch the railing  75 , minimizing the conductivity of heat from the combustion chamber  19  to the railing  75  improves the safety of the grill  10 . 
     FIG. 7 illustrates the various air spacing and air conduits that allow outside air to enter the interior of the grill  10  to either fuel the fire or cool the exterior of the grill  10 . Arrow  90  illustrates the primary air intake to feed air to the combustion chamber  19 . The air enters between gaps in the collection trays  28  and moves around the gable  61  to the combustion chamber  19 . Arrow  95  shows air entering from the open bottom of the grill  10 . Air is directed around the manifold  65  and branches into arrows  95   a  and  95   b . Arrow  95   a  shows air rising in between the retaining wall  22  and the third wall  39 . Arrow  95   b  shows air entering the air space between the back wall  50  and the third wall  39 . The cool air that runs on either side of the third wall serves as a buffer to prevent the exterior of the grill from becoming dangerously hot. Eventually arrows  95   a  and  95   b  merge and exit the grill  10  through the cooking surface  14  without ever entering the combustion chamber  19 . A third air entry point is shown by arrow  100 . Arrow  100  enters the grill  10  above the handle  80  of the collection tray  28 . The arrow  100  eventually mixes with arrow  90  and enters the combustion chamber  19  to feed the fire. A fourth entry is represented by arrow  105  where air enters the open bottom of door  16 . Arrow  105  eventually enters the combustion chamber  19 . The air that enters the door  16  helps to keep the door  16  cool to the touch allowing the cook to open the door  16  to add fuel without fear of burning her hand on the door  16 . 
     FIG. 7 also discloses angle stiffeners  71  which add stability to the retaining wall  22  of the grill  10 . A typical grill  10  contains two stiffeners  71  placed adjacent and parallel to rear wall  50  and welded in place connecting the two side walls of the grill  10 . The angle stiffeners  71  are necessary to add stability to the retaining wall  22  to prevent fuel that is cast into the combustion chamber  19  from pushing the retaining wall  22  back and potentially separating the retaining wall  22  from the spacers  93   a  and  93   b . The welds of spacers  93   a  and  93   b  are responsible for holding the retaining wall  22  in position to define the combustion chamber  19 . The welds at each end and spacers  93   a  and  93   b  connect the retaining wall  22  with the cooking surface  13 . If the retaining wall  22  has force applied in a lateral direction, the spacers  93   a  and  93   b  are stressed and tend to break. The stiffeners  71  are in position to prevent the retaining wall  22  from moving laterally and also provide additional support to the wall to prevent fuel thrown into the combustion chamber  19  from piercing the retaining wall  22 . 
     FIG. 4 illustrates an optional second position for the stiffener  71 . The stiffener  71  is attached to the front wall  11  and the back wall  50  and supports the retaining wall  22 . The rear portion of the stiffener  78  attaches above the burner manifold  65  to aid in supporting the additional weight of the manifold  65 . 
     FIG. 7 also illustrates the relationship between the cooking surface  14 , the fuel support platform  18 , and the collection trays  28 . Drippings from food placed on the cooking surface  14  pass the fuel support platform  18  and either deposit within the collection trays  28  or first hit a gable  61  before being deposited in the collection tray  28 . Likewise, ash and debris, generated by the burning of the solid fuel, fall through the fuel support grate  17  and are deposited in the collection tray  28 . After a cooking session, the fire may be extinguished, and the collection tray  28  removed by pulling upon handle  80 . The contents of the collection tray  28  may be deposited in a waste receptacle and the collection tray  28  returned to its position. FIG. 7 also illustrates the position of the burner manifold  65  and jet housing  26  relative to the gable  61  and the fuel support platform  18 . The jet housing  26  is located below the fuel support platform  18  in such a position that flames emanating from the jet housing  26  will come into contact with fuel placed on the support  18 . 
     FIG. 7 also illustrates a deflecting plate  88  that hangs over the retaining wall  22 . Typically, more than one deflecting plate  88  is used to cover the length of the retaining wall  22 . Spaced about one-half inch apart, each Deflecting plate  88  should cover a hole  89  in the retaining wall  22  allowing air from arrow  95   a  to cool the interior of the retaining wall  22 . The additional air flow contributes to the overall cooling effect that prevents the exterior of the grill  10  from reaching unsafe temperatures. In addition the air flow generated by the deflecting plate  88  shields the retaining wall  22  from extreme temperatures which result in repeated expansion and contraction of the retaining wall  22 . Over time, if the retaining wall is not shielded properly the wall tends to buckle placing stress on the joints of the housing, which in turn compromises the structural integrity of the combustion chamber. 
     Referring now to FIG. 3, a gas cock  36  is disposed within or adjacent to the housing  12 . The gas is supplied from gas source  60  and flows to gas cock  36 . The gas cock  36  will be closed when the grill  10  is out of use, but will be open when the grill  10  is operational. The solenoid valve  38  is activated by a timer  42 . The timer  42  may be set to keep the solenoid valve  38  open for a desired time. Opening the solenoid valve  38  and the gas cock  36  permits gas to flow through flex pipe  40  into the burner manifold  65  where flame is released from the gas jets. After the timer  42  expires and the solenoid valve  38  closes, the solid fuel should be well ignited. If the fuel is not ignited the timer  42  may be reset. An alternative embodiment of the invention may use a thermostat to detect when the combustion chamber  19  has achieved a sufficient temperature to sustain the burning of the fuel. 
     OPERATION 
     At the start of the cooking shift, solid fuel pieces such as hickory or mesquite logs are placed upon the fuel support surface  18 . The logs are ignited by setting the ignition timer  42 , the timer  42  may be set to varying lengths of time, depending on the type, condition, and quantity of fuel. The timer  42  once set opens the solenoid valve  38  which provides gas, from a gas source  60 , through flex pipe  40  through the open gas cock  36  through more flex pipe  40 , to burner manifold  65 , to the plurality of gas jets  67  within gas jet housings  26 . Gas may be manually or automatically ignited, and gas pressure and burner adjustments should be sufficient to throw flames beneath the fuel placed on the above fuel support platform  18 . Gas flames will preferably extend at least about to the mid-point of the fuel support platform  18 . After the timer  42  time has expired the solenoid valve  38  is closed automatically shutting off the gas source  60 . Once the solid fuel pieces are ignited, air flow through the grill  10  is primarily upward from spaces between the collection trays  28 . Because only the grates  13 ,  17  and retaining wall  22  must be heated, rather than a larger mass of fire bricks the present invention is able to achieve a stable cooking temperature in about twenty (20) minutes time. This is due to the unique double walled design of the grill, where the sides  33  and  35  and doors  16  are constructed with open bottoms and air spaces that permit the air to enter from the bottom and be vented into the upper portions of the combustion chamber  19 . This forms a dynamic air barrier between the retaining wall  22  and the housing wall  8  and prevents the exterior of the housing  12  from overheating, without a sizable mass of fire brick. 
     At the end of a cooking shift the fire inside the combustion chamber  19  of grill  10  may be extinguished. Typically the cook will water down the fire. Unlike fire brick which may shatter if quenched with water the fire within steel retaining wall  22  may be quickly extinguished without consuming partially spent fuel. Once the fire is out, partially spent solid fuel may be removed to dry or left inside the combustion chamber for burning at the next cooking session. The gas jets  26  can provide sufficient heat to dry damp fuel at the beginning of a cooking session. 
     Although a preferred embodiment of the present invention has been disclosed in detail herein, it will be understood that various substitutions and modifications may be made to the disclosed embodiment described herein without departing from the scope and spirit of the present invention as recited in the appended claims.