Abstract:
A cooking apparatus has a food support with food engaging structure, such as a rotisserie spit. A firebed is mounted under the food support to heat food at the food support. A heat reflective vault is mounted over the food support for reflecting radiant heat back down toward the food support. The vault extends over the food support while still providing access from the side. A drive mechanism can vertically adjust the firebed to adjust heat flowing toward the food support. An elevator motor may be coupled to the drive mechanism for vertically positioning the firebed. A thermostat responsive to heat from the firebed and coupled to the elevator motor can control elevation of the firebed.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to cooking apparatus and methods, and in particular, to cooking techniques that make the cooking temperature adjustable and leave the cooking food easily accessible. 
     2. Description of Related Art 
     Home barbecues and other types of home cooking grills and rotisseries are adequate for cooking simple, small batches of food, but are inadequate for more demanding cooking. For example, cooking a whole pig is impossible with traditional home cooking devices. For this reason, consumers are left to their own devices, such as excavating a fire pit and building a fireproof structure to support a heavy-duty roasting spit. Such cooking arrangements are not only difficult to build, but difficult to operate. Maintaining a proper fire for delivering the correct amount of even heat is also difficult. Moreover, an open fire is relatively inefficient and most heat is dissipated into the environment. 
     Even when the food being cooked is a simple batch of hamburgers and hot dogs, conventional barbecues are lacking. The heat produced by a conventional charcoal barbecue varies dramatically over time. When the charcoal is first ignited little heat is delivered, but then the heat gradually rises to a peak before gradually declining as the charcoal is consumed. Therefore, the cook must avoid overcooking during the peak interval or undercooking cooking outside this peak interval. 
     In U.S. Pat. No. 5,996,572 charcoal tray 32 can be vertically adjusted by threaded crankshaft 56, relative to grill 30 or to motor-powered rotisserie shaft 96 mounted in cover 38. See also, U.S. Pat. Nos. 5,154,159, and 2,968,301 
     In U.S. Pat. No. 5,660,101 a food basket 25 can be turned by hand crank 26. The same hand crank circulates endless chain 31A to rotate camshaft 58. Thus as the food basket 25 is turned on edge, charcoal grill 33 is retracted by cam crank 53 to avoid a collision with food basket 25. 
     In U.S. Pat. No. 4,462,306 a support frame 90/92 for supporting a grill or rotisserie rod can be hoisted or lowered by cables 106, which are wound on shaft 140 of adjustment wheel 141. 
     The firebox 50 of U.S. Pat. No. 4,572,062 can be raised and lowered by placing the ends of handlebars 40 in different notches 32 of the rotisserie grill. A small pig or other food can be mounted on the spit 70 and rotated by motor 130. The roasting food can be covered by a cover 160 to provide a drum-shaped enclosure. 
     In U.S. Pat. No. 2,943,557 vertically adjustable firebox 30 protrudes through bottom opening 27 of conical reflector 20, and may be adjusted up and down using handle 55. Notches 56 engage bar 14, which is connected to arm 50 using pin 57. 
     In U.S. Pat. No. 3,379,190 fireboxes 23, 25 are supported by cantilever arms 27, which are vertically moveable in the grill housing. Using handles 51 to swing cranks 45 out of notches 49, fireboxes 23, 25 may be moved along slot 29 in post 15 to their desired vertical position. 
     In U.S. Pat. No. 6,809,297 temperature switch 38 regulates the temperature in cooking chamber 12. Motor 56 rotates spit 58. Motor 71 rotates heating element 44, and drive gear 74 is adapted and configured to engage “D” shaped wheel 76 for positioning hearing element 44 at various locations within cooking chamber 12. 
     In U.S. Pat. No. 5,000,083 heating unit 30 can be vertically displaced by motor 32. Motor 13 can operate turntable 11 and a separate motor 43 vertically displaces light curtain 40 relative to heating unit 30. Controller 50 automatically adjusts the position of heating unit 30 and serves as a timer. 
     In U.S. Pat. No. 5,928,544 the vertical position of heating elements 10 and 20 may be controlled by a motor 34. 
     In U.S. Pat. No. 3,757,675 firebox 15 is supported on cross members 13, which comprise a firebox track 16. Latches 21 and studs 20 allow the firebox to be horizontally adjusted along track 16 when the user grasps handle 23. 
     In U.S. Pat. No. 5,676,045 vertically-oriented second firebox 38 is positioned in housing 12 opposite first firebox 22. Handle 42 protrudes through an opening in the grill housing 12 and allows horizontal movement of firebox 38 using a roller on the grill&#39;s bottom 16. 
     In U.S. Pat. No. 4,418,615 firebox thermostat 44 controls the temperature within cooking chamber 15 by regulating the passage of air through firebox inlet port 17 and the corresponding combustion rate within firebox 12. 
     In U.S. Pat. No. 3,589,269 prod 36 of thermostat 35 projects into barbecuing oven 8 to determine the temperature of the oven. Current to heating element 39 is cut off when the predetermined temperature is reached, and switched back on when the temperature drops below a specified level. 
     In U.S. Pat. No. 4,663,517 as control housing 24 is rotated, heating element 28 and reflector 30 are also rotated within the grill bowl. Rotisserie rod 38 is operated by drive unit 42. Thermostat 194 is controlled by rotating knob 182 to switch the power to heating element 28 on and off. Thermostat 194 also detects ambient heat within housing 24 and adjusts the current to heating element 28 according to the position on control knob 182. 
     In U.S. Pat. No. 3,800,691 panel 4 includes oven thermostat 5 and panel 3 includes toast thermostat control and oven on-off switch 6. These switches control temperature inside the toaster oven. 
     In U.S. Pat. No. 5,667,714 drive means 7 rotates turntable 5 within cooking chamber 2. Turntable 5 is also vertically moveable, to allow even cooking of food. 
     In U.S. Pat. No. 6,564,793 firebox 21 is rotated by motor 17 in order to promote radiant and convective heating. 
     In U.S. Patent Application 2003/0015188 cooling fans 32 and 34, designed to regulate the temperature in region 30, are controlled by a processor module 36 in accordance with an output signal from temperature detector 42. 
     See also, U.S. Pat. Nos. 3,359,887; 3,490,357; 3,943,837; 4,089,258; 4,334,516; 4,462,306; 4,924,766; 5,140,896; 5,224,676; 5,410,950; 5,536,518; 5,649,475; 5,720,217; 6,131,505; 6,131,560; 6,138,553; 6,189,528; 6,314,955; D336,593; and D403,919. 
     SUMMARY OF THE INVENTION 
     In accordance with the illustrative embodiments demonstrating features and advantages of the present invention, there is provided a cooking apparatus having a food support with food engaging structure. The cooking apparatus also has a firebed mounted under the food support to heat food at the food support. Also included is a heat reflective vault mounted over the food support for reflecting radiant heat back down toward the food support. The vault extends over the food support while leaving the food support laterally accessible. The cooking apparatus also has a drive mechanism for vertically adjusting the firebed to adjust heat flowing toward the food support. 
     In accordance with another aspect of the present invention, a cooking apparatus is provided with a food support having food engaging structure. The cooking apparatus also has a firebed mounted under the food support to heat food at the food support. Also included is a drive mechanism for vertically adjusting the firebed to adjust heat flowing toward the food support. The cooking apparatus also includes an elevator motor and a thermostat. The elevator motor is coupled to the drive mechanism for vertically positioning the firebed. The thermostat is responsive to heat from the firebed and is coupled to the elevator motor for controlling elevation of the firebed. 
     In accordance with yet another aspect of the present invention, a cooking method is provided employing a firebed, a reflector, and a rotisserie spit with food engaging structure. The method includes the step of vertically adjusting the firebed to adjust heat flowing toward the rotisserie spit. The method also includes the step of reflecting radiant heat over the rotisserie spit back down toward the rotisserie spit without laterally enclosing the rotisserie spit. 
     By employing the apparatus and methods of the foregoing type an improved cooking technique is achieved. The presently disclosed cooking apparatus is able to cook a whole meat (pig. lamb, goat, turkey, gyros etc) evenly and thoroughly, and still be portable, user-friendly, safe, efficient, durable, compact and reliable; and last but not the least important: enjoyable to operate and fun to watch it. 
     In this disclosed embodiment, a firebed is mounted on a movable upper frame that can be lifted and lowered by a drive mechanism. Moreover, a rotisserie spit (or an ordinary grill) can be mounted over the firebed. A heat reflecting vault can be mounted over the rotisserie spit to reflect radiant heat back to the food on the spit, thereby increasing the cooking efficiency. In one constructed embodiment the vault was a cylindrical metal reflector mounted over the rotisserie spit, but with the sides of the rotisserie spit left accessible. 
     In the disclosed embodiment the drive mechanism for vertically adjusting the firebed is driven by a thermostatically controlled motor. Accordingly, the firebed can be moved vertically to regulate the amount of heat delivered to the food on the rotisserie spit. 
     The drive mechanism can be a scissor lift in the form of a pair of crossed members that are supported on a lower frame. As an example, the nut on a motor driven lead screw can operate the scissor lift to adjust the height of the firebed. The scissor lift allows the firebed to move within a wide vertical range, adjusting the amount of heat delivered to cook the food properly. The movement may be assisted by a temperature control system, backed-up by a manual control. In this way the temperature is maintained automatically at a desired value to facilitate even and thorough cooking. 
     The scissor lift also gives the apparatus a very low profile when collapsed. The overall collapsed height of the device may be kept very small by placing the charcoal tray of the firebed under the frame, in between the casters, when the apparatus is idle or stored. This design makes the apparatus portable and in one embodiment easily carried in a car trunk. The presently disclosed embodiment achieves portability by employing casters, lightweight materials, and by having a collapsible frame that can fit in a car trunk. Adaptability to a variety of power sources also enhances portability. 
     In this embodiment, user-friendliness and safety is achieved by avoiding a complicated set up, and by employing an automated temperature control that is easy and safe to use and is backed up by manual controls. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above brief description as well as other objects, features and advantages of the present invention will be more fully appreciated by reference to the following detailed description of presently preferred but nonetheless illustrative embodiments in accordance with the present invention when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a cooking apparatus according to principles of the present invention; 
         FIG. 2  is a different perspective view of the cooking apparatus of  FIG. 1  with a heat reflecting vault installed; 
         FIG. 3  is a perspective view of the cooking apparatus of  FIG. 1  partially disassembled, collapsed, and packed for storage; and 
         FIG. 4  is a perspective view of the cooking apparatus of  FIG. 3  covered with the heat reflecting vault in place. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1 and 2 , the illustrated cooking apparatus has a four sided open lower frame  10  with wheels  12  and upwardly directed bumpers  10 A at each corner. The lower ends of a parallel pair of scissors arms  14  are pivotally attached to shaft  15  journaled in bosses  43 C, which are mounted in two adjacent corners of frame  10 . A crossing pair of scissor arms  16  is pivotally attached to shaft  18 , which is journaled at either end in a pair of sliding blocks  20 . Arms  14  and  16  are attached together at pivot  22 . The pair of blocks  20  slide on respective shafts  24 , which are supported in bosses  26  and  28  mounted in the inside of frame  10  (bosses  28  are located in two adjacent corners of frame  10 ). 
     The center of shaft  18  is journaled in nut  30 , which is threaded on lead screw  32 , which is rotatably mounted on the underside of bracket  34 . The outside end of shaft  32  is attached to crank wheel  36 , which has a handle  37 . The inside end of lead screw  32  is attached through splined connector  38  to elevator motor  40 , which is supported on platform  41  of frame  10 . 
     A firebed  48  in the form of a metal pan designed to hold a charcoal fire, rests inside stops  41 A and  41 B on upper frame  42 . In one embodiment pan  48  was 48 inches (122 cm) long and 24 inches (61 cm) wide, although these dimensions may be different in other embodiments. Upper frame  42 , constructed in a manner similar to lower frame  10 , has downwardly directed bumpers  42 A, and a shaft  44  supported on sliding blocks  120  (shown in  FIG. 3  together with one of the supporting blocks  126 ). Shaft  44  and sliding blocks  120  are constructed and mounted in a fashion similar to blocks  20  and shaft  18  on frame  10 . 
     The upper ends of scissor arms  14  are pivotally attached to shaft  44 . The upper ends of scissor arms  16  are pivotally attached to shaft  46  (shown in phantom in  FIG. 1 ) which is mounted in a manner similar to previously mentioned shaft  15 . 
     Accordingly, scissor arms  14  and  16  act as a scissor lift or drive mechanism for vertically adjusting the height of upper frame  42 . Specifically, elevator motor  40  can turn lead screw  32  to move nut  30  and shaft  18  longitudinally. Consequently, the spacing between the lower ends of arms  14  and  16  changes to change the angle between arms  14  and  16 . In response, the height of frame  42  changes as shaft  44  moves in the same direction as shaft  18  to accommodate the motion of arms  14 / 16 . 
     Limits switches  43 A and  43 B mounted in frame  10  can shut off motor  40  when sliding block  20  reaches one of the ends of shaft  24 . In one embodiment upper frame  42  had a height that was adjustable from 10 inches (25 cm) to 42 inches (106 cm), although this range may be different in other embodiments. 
     Frames  50  and  52  have an inverted U shape and are attached to frame  10  by thumb screws  54 . The frames  50  and  52  are made of square aluminum tubes to lower the overall weight. Bearing blocks  56  and  58  are self-lubricated bearings made of graphite bronze and are mounted atop frames  50  and  52 , respectively. Bearings  56  and  58  have a hinged, clamshell construction allowing the bearings to hold or quickly release rotisserie spit  60 . Spit  60  has a number of conventional skewers  62 ,  64 ,  66  and  68  designed to hold food such as a whole adult pig, weighing perhaps 70 pounds (32 kilograms) or more. While a rotisserie spit is illustrated herein, in other embodiments the spit may be replaced with another food support such as a grill having a number of parallel, spaced metal bars. 
     A crank wheel  70  having a handle  72  is attached to one end of spit  60 , the other end being attached through the splined connector  74  to spit motor  76 , which is supported by box  78 , which is in turn supported by frame  50 . Box  78  contains a motor control, such as a commercially available motor speed controller designed to adjust the speed of motor  76 . The motor control has manual controls such as knobs and switch handles for adjusting the speed and direction of motor  76  (and as will be described presently, the direction of motor  40 ). Specifically, there are four controls: two for the scissor lift  14 / 16  and two for the spit  60 . In particular the angular speed of the spit  60  may be regulated to a constant speed somewhere between 6 to 20 rpm, although other speed ranges are contemplated (e.g., between 10 to 12 rpm). The two controls for the scissor lift  14 / 16  command raising and lowering of firebed  48  and also control the speed of movement. The lift controllers operate in automatic and/or manual modes. 
     Power is brought to box  78  from junction box  82  which has a socket  84  for receiving a power supplying line (not shown). A power cord  86  plugged into junction box  82  is routed through the inside of frame  50  into the interior of box  78 . As described further hereinafter, signal lines (not shown) embedded in column  88  terminate in contacts  90 , for purposes to be described presently. Column  88  and column  89  are attached atop frame  50  and are spanned by a bridge  92 . Likewise, columns  94 ,  96  are mounted atop frame  52  and spanned by bridge  98 . Elements  88 - 98  support a heat reflective vault  100 , for example, a cylindrical metal reflector that may be made of sheet aluminum or stainless-steel. The reflector  100  has a concave underside. 
     A combined temperature gauge and thermostat  102  centrally mounted along one edge of reflector  100  can display temperature and send a temperature signal along line  104 , which runs along the underside of reflector  100  to connect to the contacts  90  of column  88 . In this embodiment the case of thermostat  102  can be rotated to adjust the temperature setpoint. If the temperature sensed by thermostat  102  is close to the temperature setpoint no signal is sent along line  104 . If the sensed temperature is sufficiently greater or less than the temperature setpoint a high or low signal, respectively, will be sent along line  104 . 
     The frame  10 / 42  is made of aluminum angles in one embodiment to provide strength and lightness. Also it is easy to machine or weld it. The scissor lift  14 / 16  uses aluminum channels that are more substantial to sustain the forces created when in operation. 
     To facilitate an understanding of the principles associated with the foregoing apparatus, its operation will be briefly described. The cooking apparatus can be set up as shown in  FIG. 1  and the wheels  12  (with brakes) ensure excellent maneuverability. To begin, a user can fill firebed  48  with charcoal or other combustible fuel and ignite it. The user can also release clamshell bearings  56  and  58  and then pull spit  60  out axially, disconnecting it from splined connector  74 . 
     In the usual fashion, spit  60  can be inserted through a piece of meat such as a whole adult pig. The skewers  64  and  66  can be inserted radially through the pig carcass (and locked with the crosspieces  64 A and  66 A) while skewers  62  and  68  can be inserted into either end of the pig. Thereafter the spit  60  can be reconnected to spline connector  74  and placed in bearings  56  and  58 , which are then closed. Next, the user can fasten reflector  100  atop posts  88 ,  89 ,  94 , and  96 , being careful to establish an electrical connection between contacts  90  and thermostat lead  104 . 
     The user can check the cooking temperature by observing the reading on thermostat  102 . If the temperature is inappropriate, the height of firebed  48  can be adjusted by turning crank wheel  36  to rotate lead screw  32  and move nut  30  axially. As previously mentioned, shaft  18  and sliding blocks  20  move with nut  30  to change the separation between the lower ends of scissor arms  14  and  16 , thereby changing the elevation of frame  42  and firebed  48 . 
     The user can continually turn crank wheel  70  to rotate spit  60  and the meat supported thereon. In some cases crank wheel  70  may be turned in angular increments every five minutes or so. In most cases, however, the user will operate controls  80  on control box  78  to start motor  76  and rotate spit  60 . These controls can be used to set the direction of rotation as well as setting the speed, somewhere in the range of perhaps 6-20 RPM. 
     The power for this process will be supplied by a power cord plugged into junction box  82 , which will in turn transmit power through cable  86  to control box  78 . This power can be supplied by a public utility or, for embodiments having appropriate power converters, from a storage battery, such as an automobile battery. 
     As the cooking proceeds the heat from firebed  48  can change. The user may operate controls  80  to begin automatically adjusting the height of firebox  48 . The target temperature is set by turning the thermostat body  102  to set the desired temperature. If the temperature measured by thermostat  102  is within 5 degrees Fahrenheit of the target temperature, no signal is sent through line  104 . If the measured temperature differs from the target temperature by more than 5 degrees Fahrenheit a high or low signal, as appropriate, is issued along line  104  and through the wires (not shown) in column  88 , finally providing a signal inside control box  78 . Alternatively, an analog temperature signal can be transmitted from thermostat  102  and sensed inside control box  78  by a comparator (not shown), which produces an up or down signal, as appropriate. 
     In any event, the up or down signal is converted in control box  78  into a motor control signal that is routed through wires (not shown) inside frame  50  and along the inside of frame  10  to motor  40 . This motor control signal causes motor  40  to spin in the appropriate direction, turning lead screw  32  in order to drive nut  30  in the requisite direction. For example, if the temperature measured by thermostat  102  was too far above the target temperature, a down signal sent to control box  78  to produce a motor control signal ultimately causing nut  30  to move outwardly to separate the lower ends of scissor arms  14  and  16 , thereby lowering frame  42  and firebed  48 . 
     Using any one of various well-known control techniques, firebed  48  can either be lowered by some fixed increment or lowered by an amount calculated to be appropriate to eventually reduce the measured temperature to the target temperature. Alternatively, motor  40  can turn lead screw  32  very slowly to avoid overshooting the position needed to achieve the target temperature. 
     In some cases the user will simply observe that the temperature reading from thermostat  102  is out of the desired range and use controls  80  to steer motor  40  to bring firebox  48  to an elevation deemed appropriate by the user. 
     As the meat on spit  60  cooks, heat from firebed  48  or from the meat itself can radiate upwardly, but will be reflected back toward the cooking meat by reflector  100 . This greatly increases the efficiency of the cooking. Also, reflector  100  does not fully enclose the meat on spit  60 . Therefore, the user can watch the cooking process to judge its progress or simply for the pleasure of watching. Moreover, since the cooking meat is accessible from the side, the user is able to baste the meat or make sample cuts to judge how well the meat is cooking. 
     Eventually, the meat on spit  60  will be done and the roasted meat can be served directly from spit  60 . In that case, the user will want to lower firebed  48  to the lowest position and perhaps extinguish the fire therein. The user will then stop motors  76  and  40 . The reflector  100  can now be removed. In some cases spit  60  will be released from bearings  56  and  58  and spline connector  74  so the roasted pig can be carried to a carving or serving table. The meat on spit  60  can be removed by releasing skewers  62 - 68  and removing crank wheel  70 . 
     When the foregoing cooking apparatus is no longer needed the ashes in firebed  48  can be discarded and firebed  48  and spit  60  with its skewers  62 - 68  can be cleaned. If convenient, the cooking apparatus can be moved to or near a storage or transport location where the breakdown and storage can be completed. 
     Using either crank wheel  36  or motor  40 , frame  42  will now be fully lowered to rest against frame  10 . Frames  50  and  52  can be disconnected from frame  10  by unscrewing thumbscrews  54 , which can later be rethreaded into frame  10 . If desired, columns  88 ,  89 ,  94 , and  96  can be detached from frames  50  and  52 . 
     Referring to  FIG. 3 , the various disassembled components can be packed as shown. This packing can be done after the frames  10  and  42  are wheeled to a storage location or hoisted onto a transport (e.g., the trunk of an automobile). The firebed  48  can first be filled with various components such as skewers  62 - 68 , wheel  70 , frame  52 , etc. The loaded firebed  48  can then be slid under frame  10  between the wheels  12 . Certain bulky items may be placed inside firebed  48  after sliding it under frame  10 . For example, one may wish to so delay packing the frame  50 , which remains attached to the relatively bulky control box and motor  76 . 
     Once all the components are packed inside firebox  48  and frames  10 / 42 , reflector  100  can be placed over everything. Latches  127 A on frame  10  can then connect with four mating catches on frame  42  (elements  127 A and  127 B, being referred to as latches  127 ) to hold all items together. See  FIG. 4 . Alternatively, the assembly can be held together with straps, bungee cords, or the like. When fully closed, the scissor lift  14 / 16  and the motors (electrical or hydraulic) are hidden and protected inside the frame  10 / 42 . They do not contribute to the overall height of the apparatus. The overall height is primarily determined by the thickness of the aluminum frames  10 / 42  and the wheels  12 . The resulting package may be about 12 inches tall and can easily be stored in a garage or various other storage locations. 
     This sturdy design and the use of non-corrosive materials, and self-lubricating bearings provides reliability, durability and low maintenance. 
     It is appreciated that various modifications may be implemented with respect to the above described, preferred embodiment. For example, the temperature may be measured by a wireless thermometer inserted into the roasting meat. In some embodiments the rotisserie spit may be replaced with a conventional grill. The drive mechanism for adjusting the height of the firebox may employ hoisting cables or chains, hydraulic pistons, vertical lead screws, rack and pinions, etc. The size; shape, and thickness of the various components, as well as the materials used to build the components, can be selected to produce the desired strength, durability, temperature stability, styling, etc. 
     Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.