Patent Abstract:
An oven for cooking foods includes a housing having a fire chamber and a cooking chamber disposed generally above the fire chamber. A vessel is receivable in the fire chamber and is adapted to hold combustible material therein to generate heat and smoke for cooking food in the cooking chamber. A blower is mounted on the housing. The blower is selectively operable to move air. A tube is attached to an outlet of the blower and extends into the fire chamber such that when the vessel is received in the fire chamber the tube extends to a position adjacent the vessel so that air from the blower is blown directly into the vessel without first passing a heating element. The oven does not require supplemental heat from a burner or similar heating element.

Full Description:
FIELD OF THE INVENTION 
     The present invention generally relates to barbecue ovens, and in particular to a barbecue oven having controlled heat and smoke flow. 
     BACKGROUND OF THE INVENTION 
     Barbecuing is a traditional cooking process that typically involves the cooking of foods by exposing them to relatively low temperature smoke for a number of hours. The structure used for barbecuing typically includes a heating or fire chamber, a cooking chamber and a conduit or flue through which smoke and heated combustion gases are transported from the fire chamber to the cooking chamber. Smoke and heat is produced by burning a smoke producing substance in the fire chamber such as wood. The wood is burned using a heating element such as a gas or electric burner. These burners are costly and it may be difficult to control the heat generated with the burners without additional devices such as sophisticated logic thermometers, dampers, vents and/or baffles. Accordingly, there exists a need for a barbecue oven that adequately controls the heat generated in the oven without using a burner and without the need for complex controllers or mechanical devices like dampers, vents or baffles. 
     SUMMARY OF THE INVENTION 
     In one aspect, an oven for cooking foods generally comprises a housing including a fire chamber and a cooking chamber disposed generally above the fire chamber. A vessel is receivable in the fire chamber and is adapted to hold combustible material therein to generate heat and smoke for cooking food in the cooking chamber. A blower is mounted on the housing. The blower is selectively operable to move air. A tube is attached to an outlet of the blower and extends into the fire chamber such that when the vessel is received in the fire chamber the tube extends to a position adjacent the vessel so that air from the blower is blown directly into the vessel without first passing a heating element. 
     In another aspect, an oven for cooking foods generally comprises a housing including a fire chamber and a cooking chamber disposed generally above the fire chamber. A vessel is receivable in the fire chamber and is adapted to hold combustible material therein to generate heat and smoke for cooking food in the cooking chamber. A blower is mounted on the housing. The blower is selectively operable to move air. A tube is attached to an outlet of the blower and extends into the fire chamber through an opening in the housing. The tube has an interior surface area and a generally square shaped cross section having an area. The ratio of the interior surface area to cross sectional area is at least about 20 to 1. 
     In yet another aspect, an oven for cooking food generally comprises a housing including a fire chamber having a volume and a cooking chamber disposed generally above the fire chamber. A vessel is receivable in the fire chamber and is adapted to hold combustible material therein to generate heat and smoke for cooking food in the cooking chamber. A blower is mounted on the housing. A tube is attached to an outlet of the blower and extends into the fire chamber through an opening in the housing. The blower is configured to blow air through the tube to produce a volumetric flow rate generally at an end of the tube in the fire chamber. The ratio of the volume of the fire chamber to the volumetric flow rate generally at the end of the tube is between about 1 to 1 and about 1 to 1.5. 
     In still another aspect, an oven for cooking food generally comprises a housing having a fire chamber and a cooking chamber disposed generally above the fire chamber. The fire chamber is configured to receive a vessel for holding combustible material therein to generate heat and smoke for cooking food in the cooking chamber. The oven further comprises a blower for blowing air into the fire chamber. The fire chamber is adapted to be substantially sealed from inflow of air surrounding the oven except from the blower. 
     In another aspect, a method of supplying heat to an oven in a controlled temperature range without the use of gas or electric burners generally comprises the steps of filling a vessel adapted for receipt in a fire chamber of the oven with charcoal. The vessel is placed in the fire chamber. Selectively blowing air into the filled vessel with a blower attached to the oven, the blower blowing air through a tube attached to an outlet of the blower and extending into the fire chamber to a position adjacent the vessel such that the air from the blower is blown directly into the vessel without first passing a heating element. 
     Other objects and features will be in part apparent and in part pointed out hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a left side perspective of a barbecue oven of the present invention with a door open to show internal construction; 
         FIG. 2  is a right side perspective of the barbecue oven with doors open to show internal construction; 
         FIG. 3  is a front elevation of the barbecue oven shown in  FIG. 2 ; 
         FIG. 4  is a vertical section of the barbecue oven; 
         FIG. 5  is a perspective of a blower and tube of the barbecue oven; 
         FIG. 6  is a perspective of the barbecue oven as shown in  FIG. 2  with a charcoal basket partially removed and supported by an ash tray; 
         FIG. 7  is an enlarged fragmentary perspective showing the charcoal basket and ash tray; and 
         FIG. 8  is a perspective of the charcoal basket filled with ignited and unignited charcoal. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the drawings. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings and in particular to  FIGS. 1-5 , a barbecue oven that efficiently circulates heat and smoke around food in the oven is designated generally by reference numeral  10 . For the purpose of illustration, the invention will be described in conjunction with a barbecue oven. The invention, however, should not be limited to this specific use, as it is instead intended that the invention be used in any application in which circulation of heated air around food is to be employed. The oven  10  includes a housing, indicated generally at  11  which comprises a front wall  12 , back wall  14 , side walls  16 ,  18 , a top  20  and a bottom  22 . The front, back and side walls  12 ,  14 ,  16 ,  18  define wall members which together form vertical walls of the housing  11 . The walls  12 ,  14 ,  16 ,  18 , top  20  and bottom  22  are preferably seam welded together to form the housing  11 . The number of wall members forming the vertical wall may be other than described without departing from the scope of the present invention. The housing  11  is supported by legs  24  extending from the bottom  22  to position the oven  10  above an underlying floor F. Wheels  25  may be used to facilitate transport of the oven  10 . For the purposes of this description, the legs  24 , wheels  25  and any other supporting structure are considered part of the housing  11 . The housing is suitably constructed of heat resistant materials such as stainless steel. Other metals or porcelain coated materials suitable for use in cooking ovens can also be utilized. The oven  10  may include insulation material (not shown) in various parts of the oven to help maintain temperatures in the oven and to protect users from heat generated by burning fuel in the oven. Insulation may comprise a double-wall construction of the walls  12 ,  14 ,  16 ,  18 ,  20 ,  22  of the housing  11 . The double-wall structure may also include insulating material between the walls such as high-temperature mineral wool or other non-combustible materials. 
     A heat flow regulating fire wall  26  divides the interior of the oven  10  into a fire chamber  28  and a cooking chamber  30 . In one embodiment, the firewall  26  extends between the opposite side walls  16 ,  18  along a width W of the oven  10  ( FIG. 3 ) and extends from the front wall  12  to near the back wall  14  along a depth D of the oven ( FIG. 4 ). The fire chamber  28  has an approximate length L fc  of about 2 ft., an approximate height H fc  of about 1.08 ft., and an approximate width W fc  of about 1.58 ft. Therefore, the fire chamber  28  has an approximate volume of about 3.4 cubic feet. An angled plate  29  is welded to the bottom  22  and back wall  14 . The fire chamber  28  is in the lower part of the oven beneath the firewall  26 , and the cooking chamber  30  is above the firewall. Thus, the oven  10  has a generally vertical orientation, with the cooking chamber  30  located above the fire chamber  28 . The firewall  26  has a generally arcuate shape with a back portion  33  that extends upward to form a tapered duct  32  having a throat, or outlet  34  between the firewall and the back wall  14 . The duct  32  is defined by the back portion  33  of the firewall  26 , a portion of the back wall  14  generally opposing the back portion and sections of the side walls  16 ,  18  extending between the back portion and opposing portions of the back wall. It is believed that heated air and smoke from the fire chamber  28  is provided with an upward thrust by the angled plate  29  and passes through the throat  34  to the cooking chamber  30 , as will be more fully explained below. The shape of the firewall  26  may be described as a segment of an ellipse ( FIG. 4 ). One or more flanges (not shown) extending from the firewall  26  to the back wall  14  may be used to secure the firewall to the back wall without substantially blocking the throat  34 . The firewall  26  is fixed to the front wall  12  and the side walls  16 ,  18  of the housing  11  by welding. However, the firewall  26  can be fixed to the housing  11  using suitable brackets and fasteners (not shown) without departing from the scope of the invention. Continuous seam welds are preferred, at least in the region of the fire chamber  28 . For ovens such as the oven  10  described in the present invention, a firewall like firewall  26  is preferred for controlling heat flow in the oven. 
     A food rack, indicated generally at  40 , is located within the cooking chamber  30 . As shown, the food rack  40  includes a series of slidable horizontal shelves  42  supported on brackets  44  that are secured to the side walls  16 ,  18  of the housing  11 . Each bracket  44  includes vertically spaced rails  46 , each aligned with a corresponding one of the rails  46  on the bracket  44  on the opposite side wall  16  or  18 . The rails  46  of each pair of aligned rails receive opposite edge margins of one of the racks  42  to support the rack in the cooking chamber  30 . Generally speaking, the food rack  40  may have various configurations including rotating slits, rotisserie wheels, baskets or even stationary shelves without departing from the scope of the invention. 
     A lid or door  50 A makes up a portion of the front wall  12  and the top  20  of the housing  11  and provides access to the cooking chamber  30 . The door  50 A may have a heat resistant glass window (not shown) located therein to allow the user to monitor the food product being cooked without having to open the door. A thermometer  52  may be mounted on side wall  18  adjacent the door  50 A to indicate the temperature inside the cooking chamber  30  of oven  10  to monitor the heat produced in the fire chamber  28  as will be explained in greater detail below. It will be understood that the thermometer  52  may have other locations on the oven  10  without departing from the scope of the present invention. During operation of the oven  10 , the door  50 A is typically closed except when inserting food or retrieving food from the oven. 
     In one embodiment, the firewall  26  is shaped with a front edge  54 , back edge  56  and middle portion  58  ( FIG. 4 ). The back edge  56  is located vertically higher in the oven  10  than the middle portion  58  such that the firewall  26  has a concave shape opening upward toward the cooking chamber  30 . The position of the firewall  26  below the food rack  40  permits the firewall to act as a drip pan for catching grease and other meat drippings produced by food while it is cooking on the racks  40 . It will be understood that the firewall may have other configurations within the scope of the present invention. 
     The heated air and smoke in the cooking chamber  30  circulate in a generally circular or elliptical path around the food products on the food rack  40 , flowing up the rear wall  14 , across the top  20  of the cooking chamber, down the front wall  12 , and over the fire wall  26 . The accelerated current of heated air and smoke passing through the throat  34  of the tapered duct  32  entrains the air in the cooking chamber  30  to provide momentum and to keep the air circulating in this circular pattern. The accelerated heated air stream flowing through the tapered duct  32  reduces heat stratification in the cooking chamber  30 , even when there is no artificial means to circulate the air within the cooking chamber. Thus, this circulation path within the oven  10  is configured to eliminate the need for baffles, flues or convection fan blades (not shown) located in the cooking chamber  30  for distributing the heated air around the food products being cooked. The shape of the duct  32  and cooking chamber  30  may have other configurations without departing from the scope of the present invention. Moreover, baffles, flues and or convection fan blades may be used with the present invention although less desirable. 
     In one embodiment, smoke exits the cooking chamber  30  through one or more portals  64  located in the sidewalls  16 ,  18  of the housing. The portals  64  (only one illustrated in  FIG. 4 ) serve as openings into exhaust ducts  66  contained within the sidewalls  16 ,  18 . Desirably, the portals  64  are located in the sidewalls  16 ,  18  so that the portals are below the bottom-most portion of the food rack  40 . This location of the portals  64  facilitates removal of smoke in an amount and rate which promotes circulation of smoke and maintenance of smoldering solid fuel in the fire chamber  28 . Thus, food in the oven is properly flavored by the smoke without being over-exposed to the smoke. The exhaust ducts  66  desirably have a bottom surface that slopes upward from the interior surface of the sidewall to the outward surface of the exhaust duct so that any grease splattering into the portals  64  is discouraged from accumulating in the ducts. The exhaust ducts  66  are suitably about 4 inches wide and about ¾ of an inch deep and form a conduit leading to exhaust stacks  68  near the top  20  of the oven  10  which can be open to the atmosphere or connected to a suitable chimney. The exhaust stacks  68  extend from the housing  11  above the sidewalls  16 ,  18  so as to not interfere with the door  50 A. Ambient heat in the cooking chamber  30  is transferred through the side wall  16 ,  18  to the confined space in the exhaust duct  66  to aid in transporting the smoke. When heated, the exhaust ducts  66  transport heat and smoke through the exhaust stacks  68  to the atmosphere, promoting the circulation of the smoke and heat within the cooking chamber  30 . Other means for venting smoke from the cooking chamber  30  are contemplated without departing from the scope of the invention. 
     The fire chamber  28  contains a charcoal basket (broadly, “a solid fuel vessel”) generally indicated at  70 . The charcoal basket  70  holds combustible material such as charcoal or charcoal bricks and other fuels besides charcoal. The charcoal basket  70  may also contain a relatively small quantity of smoke producing material such as wood chips, wood chucks or pellets (not shown). Referring to  FIGS. 6 and 7 , the charcoal basket  70  includes downwardly extending end walls  72  and downwardly extending mesh side walls  74  that lead to a substantially planar bottom wall  75  ( FIG. 4 ). As best seen in  FIG. 8 , the charcoal basket  70  is suitably elongated in shape and spans nearly the entire width W of the oven  10 . As illustrated, the charcoal basket has a length L b  of about 19 in., a height H b  of about 7 in. and a width W b  of about 6 in. Thus, the illustrated charcoal basket  70  has a height to width ratio of about 1.2. In one embodiment, the charcoal basket  70  has a ratio of height H b  to width W b  of at least about 1. An upper flange  79  extends outwardly around the top of the charcoal basket  70 . The charcoal basket  70  is accessible and removable through a side door  77 . The door  77  is provided with a gasket  80  to seal the fire chamber  28  when the door is closed. In the illustrated embodiment, the charcoal basket  70  is partially formed from expanded metal. However, other suitable configurations of the charcoal basket  70  are within the scope of the invention. 
     Beneath the bottom  22  of the oven  10 , below the charcoal basket  70 , is a removable ash tray  76  for collecting expended ash material. The ash tray  76  includes a substantially horizontal planar member  78 . The ash tray  76  is mounted below side wall  16  and suitably removable from below the oven  10  for convenient emptying of the ash. The ash tray  76  can also be partially removed ( FIG. 6 ) to serve as a support for the charcoal basket  70  when loading the charcoal into the charcoal basket as will be explained in greater detail below. In another embodiment (not shown), an ash tray could be formed integral with the bottom of an oven and slidable out from a fire chamber conjointly with a charcoal basket carried by the ash tray. 
     A blower  84  is located in a forward compartment  86  behind the front wall  12  of the housing  11  adjacent the fire chamber  28 . The compartment  86  comprises a top wall  88  and side wall  89 . A door  50 B closes off the compartment  86  to the surrounding environment. However, vents  85  allow the blower  84  to draw in air from the surrounding environment for operation. The blower  84  is mounted in the compartment  86  in a suitable manner such as by a bracket  96 . A square tube  94  is attached to an outlet of the blower  84  by a flange  98  and extends through an opening in side wall  89  and into the fire chamber  28 . The tube  94  has a length L t  of about 16 in., an inside perimeter P t  of about 3 in., and a uniform cross-sectional area CA of about 0.56 in 2  ( FIG. 5 ). Thus, the tube  94  has an internal surface area of about 48 in 2 . Therefore, the ratio of the internal surface area to the cross-sectional area of the tube  94  is about 85 to 1. In one embodiment, the ratio is at least about 20 to 1. In another embodiment, the ratio is at least about 50 to 1. The tube  94  extends about 7½ in. into the fire chamber  28  to a position about 1 to about 5 in. (2.5 to 12.7 cm.) from the charcoal basket  70 . Therefore, the tube  94  extends into the fire chamber  28  a distance greater than a greatest cross sectional dimension of the tube. In the illustrated embodiment, the charcoal basket is not located in the fire chamber  28  by any specific structure. However, it is envisioned that a locating element (not shown) could be use to precisely position the charcoal basket  70  in the fire chamber  28  with respect to the end of the tube  94 . Also, multiple tubes and/or multiple blowers (not shown) can be used to accommodate larger ovens requiring larger charcoal baskets. For example, a single blower could exhaust into a manifold from which several tubes extend into the fire chamber. 
     The blower  84  has a motor  90  which directs air though the tube  94  directly into the charcoal basket  70 . The tube  94  directs the air from the blower  84  to a position about mid-height and mid-length of the charcoal basket  70  and generally perpendicular to the side walls  72  of the charcoal basket. The tube  94  is free of any dampers, vents, baffles or any other devices for regulating air flow. Also, there are no heating elements disposed between the end of the tube  94  and the charcoal basket  70 . In fact, there are no heating elements within the fire chamber  28 . The blower motor  90  can be an electric motor capable of operating at various speeds. However, in the illustrated embodiment, the blower motor  90  operates at a single speed generating an air flow rate of about 1600 FPM. The length L t  and cross-sectional area of the tube  94  produce an air flow rate generally at the end of the tube between about 820 to about 850 FPM (about 3.2 to about 3.3 cubic feet/min). Thus, the ratio of the approximate volume of the fire chamber  28  and the volumetric flow rate generally at the end of the tube  94  is between about 1 to 1 and about 1 to 1.5. 
     In the illustrated embodiment, a thermostat  100 , broadly a controller, is mounted on the housing  11  and is connected to the blower motor  90  by electrical wiring and controls in a conventional manner. The thermostat  100  is adjusted to maintain a desired temperature within the cooking chamber  30  by switching the blower  84  on and off. As shown in  FIG. 1 , thermocouples  102 , broadly temperature sensors, are mounted in the cooking chamber  30  of the housing  11  and provide temperature input to the thermostat  100 . The thermocouples are secured to a mount  144 . The thermocouples  102  may be secured within the cooking chamber  30  at other locations within the scope of the present invention. Further, a protective screen  146  covers and protects thermocouple tubes and connectors (not shown) while also allowing the ambient air of the cooking chamber  30  to flow around the tubes and connectors for more accurate measurements. 
     The thermostat  100  may be a conventional thermostat such as a Robertshaw 5300-17E and may use simple logic or may receive input from additional thermocouples (not shown) and use staged or sequenced logic. However, in one embodiment only simple logic is used. When the desired temperature is achieved, (suitably between about 150 degrees F. and about 250 degrees F., the thermostat  100  automatically turns off the blower  84 . When the temperature in the cooking chamber  30  falls sufficiently below the desired temperature, such as to a range between about 5 degrees F. and about 10 degrees F., the thermostat  100  turns the blower  84  on, thus reestablishing combustion in the solid fuel and restoring the cooking chamber  30  to the desired temperature. In this manner, the thermostat  100  controls the blower  84  to restore combustion of the fuel and maintain the air temperature within the oven  10  within a predetermined range. One of the reasons a simple logic thermostat is used is because it is easy calibrate. More complex thermostats may require a trained professional to perform the calibration. Also, the electronics associated with complex thermostats are susceptible to damage when they experience elevated temperatures such as those required for cooking food in an oven. The thermostat  100  of the present invention needs only a small set screw (not shown) for calibration. However, it is understood that a thermostat having complex functions could be used in the present invention. The complex functions, however, are not necessary to maintain temperature control. One example of a feature that could be present in both a simple or complex logic thermostat is a cook and hold feature where the thermostat is programmed to drop the temperature in the cooking chamber  30  after a certain period of time (e.g., at end of cooking cycle). This feature keeps the cooked food warm without further cooking (e.g., 225 F to 150 F). 
     In use, the charcoal basket  70  can be partially removed from the fire chamber  28  and supported on the ash tray  76  to provide access to the charcoal basket ( FIG. 6 ). The charcoal basket  70  can also be completely removed from the fire chamber  28  and supported by the floor F. The charcoal basket  70  is then filled half way with ignited charcoal. The remaining portion of the charcoal basket  70  is filled with unignited charcoal such that the top half of the charcoal basket is occupied by the unignited charcoal. The charcoal basket  70  is then placed in the fire chamber  28  and the door  77  is closed to seal off the fire chamber. It is understood that the charcoal could also be loaded into the charcoal basket  70  while the charcoal basket is completely housed in the fire chamber  28 . Other proportions of ignited and unignited charcoal could be used, including using all ignited charcoal. 
     The thermostat  100  can then be set to a desired temperature for cooking food in the cooking chamber  30 . In a preferred embodiment, the thermostat  100  is set to a temperature between about 150 and about 250 degrees F. The sensor  102  in the cooking chamber  30  then senses the temperature in the cooking chamber. If the temperature is below the desired temperature, the thermostat  100  will turn on the blower  84  so that the blower blows air through the tube  94  and onto the charcoal in the charcoal basket  70 . A combustion reaction is produced when the oxygen in the air energizes the ignited charcoal releasing smoke and heat which cause the temperature in the fire chamber  28  to rise, thus causing the temperature in the cooking chamber  30  to rise. The blower  84  will remain on, producing a sufficient air flow to energize the ignited charcoal and increase the temperature in the cooking chamber  30  until the desired temperature is reached. When the desired temperature is reached the thermostat  100  automatically turns the blower  84  off. For purposes of this description, this type of thermostat is considered to be an “on/off control.” Once the desired temperature in the cooking chamber  30  is reached, the oven  10  is configured to maintain this temperature for an extended period of time. In addition to the configuration of the tube  94  and blower  84  which will be explained below, the housing  11  and firewall  26  of the oven  10  are sized and shaped to help maintain the cooking chamber  30  at the desired cooking temperature. The tapered duct  32  formed by the fire wall  26  and the rear wall  14  of the housing create a choke that prevents a large influx of air and heat leaving the fire chamber  28 , limiting the draw into the fire chamber through back pressure. Inhibiting the charcoal in the fire chamber  28  from overfiring allows the heat in the cooking chamber to be maintained at a steady temperature for extended periods of time. Also, the size and location of the portals  64  leading to exhaust ducts at the bottom of the cooking chamber  30  help to control the flow of air in the cooking chamber. Smoke is exhausted in an amount and at a rate which promotes circulation of the smoke in the cooking chamber and maintenance of the fuel in the fire chamber  28 . This provides additional control over the temperature in the cooking chamber  30 . 
     However, with the blower  84  off, the source of oxygen to the fuel (charcoal) is substantially removed; therefore the temperature in the fire chamber  28  will eventually begin to gradually decrease causing the temperature in the cooking chamber  30  to decrease. Once the temperature in the cooking chamber  30  decreases by an amount of about 5 to about 10 degrees F., the thermostat  100  will automatically turn the blower  84  back on, blowing air into the charcoal basket  70  to reenergize the ignited charcoal to again raise the temperature in the fire chamber  28  so that the temperature in the cooking chamber also raises, back to the desired cooking temperature. Once the desired cooking temperature is reached again, the thermostat  100  automatically turns the blower  84  back off. It will be understood that over time the energized ignited charcoal will burn such that it will light the unignited charcoal above the ignited charcoal, replenishing the fuel source to maintain the cooking chamber  30  at the desired temperature for cooking the food. Moreover, adding additional unlit charcoal to the basket  70  facilitates the continued combustion reaction aiding in the maintenance of the desired cooking temperature in the cooking chamber  30 . 
     The size and length of the tube  94 , and the range of about 820 to about 850 FPM for the flow rate of the air at the end of the tube are selected because they provide a rapid elevation of the temperature in the oven  10  without “over firing” the charcoal. Over firing is a condition that occurs when too much oxygen is supplied to the charcoal to the point where the combustion reaction continues of its own accord, creating its own draw to supply additional oxygen. The charcoal will continue to ignite even after the blower has been tuned off. This will result in a spike in the temperature above the desired cooking temperature. This is not ideal when cooking foods at low and slow temperatures, such as when smoking foods. Further, the oven  10  is configured such that the reintroduction of charcoal to the fire chamber  28  can be performed while the oven is in operation without running the risk of over firing the charcoal and spiking the temperature in the cooking chamber  30 . Even with the fire chamber door  77  open, the tapered duct  32  and the location of the portals  64  help control the temperature in the cooking chamber  30 . 
     In addition to the size and length of the tube  94 , and the flow rate generated in the tube, the tube directs air to a location that is about mid-height and mid-length of the charcoal basket  70  so that the charcoal in the charcoal basket is evenly energized and ignited. Also, the square shape of the tube  94  is believed to produce a turbulent flow of air causing the air to disperse or spread along the charcoal basket  70 . This dispersion of air is not as easily produced with a round tube which generates substantially laminar flow. Thus, the location to which the tube  94  directs air into the charcoal basket  70  along with the shape of the tube further reduce the chance of over firing the charcoal. 
     Generally speaking, the use of the ignited charcoal to begin the process eliminates the need for any heating elements such as gas or electric burners to provide the heat source necessary to create the combustion cycle described above. The pre-ignited charcoal also reduces the initial heating time needed to reach the desired cooking temperature. The charcoal itself is preferred because the uniform pieces provide a stable and predictable temperature change within the fire chamber  28 . Additional solid fuel sources such as woodchips, wood chucks or pellets may be used to produce added smoke and to flavor the food being cooked. 
     Having described the invention in detail, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims. 
     When introducing elements of the present invention or the preferred embodiments(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. 
     In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained. 
     As various changes could be made in the above constructions and methods without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Technology Classification (CPC): 8