Abstract:
A rotisserie grill includes a control device that alternates heat generation by a plurality of heating elements disposed at the periphery of a cooking chamber. The alternating heat evenly cooks food in a manner similar to a traditional rotisserie, while eliminating the need for food-rotating apparatus. The control device is a timer, which rotates a cam having a profile that actuates a switch. Heating elements are connected to the switch such that when one is energized, the other is not energized. The on/off cycle produced by the rotating cam repeats every 1 to 2 minutes. The rotisserie grill may be provided with multiple heating elements controlled by multiple switches. More than one cam may be employed to actuate the multiple switches in a complex pattern to simulate relative movement between the heating elements and the food.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the field of rotisseries for roasting food. More particularly, the present invention relates to a simplified electric rotisserie for roasting food. 
     2. Description of the Related Art 
     Electric rotisseries for roasting food are well known in the art. Rotisseries constructed for use in the food service industries typically rotate the cooking food adjacent heat sources which can be electric heating elements, burning wood or charcoal or gas flame. Food service rotisseries are characterized by large size, high cost and mechanical complexity. The apparatus for rotating the meat typically involves an electric motor and some form of mechanical transmission. Rotating the food is considered the key to uniform cooking. 
     Rotisseries for use in the home are also available. Home rotisseries are characterized by reduced size and lower cost. However, the home rotisserie typically retains mechanical apparatus for rotating the roasting food. Some home rotisseries rotate on a vertical axis while others rotate on a horizontal axis. Inclusion of mechanical rotating apparatus in the rotisserie increases the cost and complexity of the home rotisserie. In the harsh environment of a rotisserie oven, the mechanical rotating apparatus wears quickly, resulting in failure of the appliance or necessitating costly maintenance of the rotating apparatus. 
     There is a need in the art for a compact, inexpensive and uncomplicated appliance for the homeowner which produces evenly roasted food. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a new and improved rotisserie grill of simplified and efficient construction. 
     Another object of the present invention is to provide a new and improved rotisserie grill with a minimum number of moving parts. 
     A further object of the present invention is to provide a new and improved rotisserie grill that quickly and evenly roasts food placed therein. 
     These and other objects of the present invention are achieved in a rotisserie grill where the food remains stationary relative to the heating elements while an electromechanical control device switches electric power alternately among several heating elements surrounding the food. Alternating delivery of electric power to heating elements surrounding the food provides even cooking of the food while eliminating the requirement for relative movement between the food and the heating elements. 
     In one embodiment of the rotisserie grill the food is secured to an upright rack which is disposed in the middle of a vertical-cooking chamber. The rack surrounds a central heating element while at least two side heating elements are arranged to substantially surround the centrally located food/rack. A control timer permits the user to select an overall cooking duration. During the cooking time selected, power is continuously applied to the central heating element while the control timer alternately delivers power to the side elements. Alternate application of power to the side heating elements simulates relative movement between the food and the heaters and produces an evenly cooked, rotisserie-like result. An alternative embodiment includes four side heaters. 
     An alternative configuration of the rotisserie grill utilizes a horizontal food rack for supporting food between at least two upper and two lower heating elements. In this embodiment, the control timer alternately applies electric power to each of the upper and lower heating elements, again simulating relative movement between the food on the rack and the heating elements to produce a rotisserie-like result. 
     Either embodiment of the rotisserie grill eliminates the need for bulky, expensive and maintenance intensive mechanisms for rotating the food relative to the heat sources. Instead, a compact control timer utilizes a spring-driven rotating cam and switch arrangement to apply electric power to selected heating elements disposed adjacent to the food. The resulting rotisserie grill is of simplified construction, compact size and increased reliability. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects, features, and advantages of the invention will become readily apparent to those skilled in the art upon reading the description of the preferred embodiments, in conjunction with the accompanying drawings in which: 
     FIG. 1 is a front exterior view of a preferred embodiment of a rotisserie grill in accordance with the present invention; 
     FIG. 2 is a side exterior view of the rotisserie grill shown in FIG. 1; 
     FIG. 3 is a side sectional view through the rotisserie grill shown in FIG. 1 taken along line  3 — 3  of FIG. 4; 
     FIG. 4 is a top view of the rotisserie grill shown in FIG. 1 (lid removed for clarity); 
     FIG. 5 is a side sectional view through the rotisserie grill shown in FIG. 1 taken along line  5 — 5  of FIG. 4; 
     FIG. 6 is a front exterior view of an alternative embodiment of a rotisserie grill in accordance with the present invention; 
     FIG. 7 is a side sectional view through the rotisserie grill shown in FIG. 6 taken along line  7 — 7  thereof; 
     FIG. 8 is a side sectional view through the rotisserie grill shown in FIG. 6 taken along line  8 — 8  thereof; 
     FIG. 9 is a side exterior view of a control timer suitable for use in conjunction with a rotisserie grill in accordance with the present invention; 
     FIG. 10 is a right end view of the control timer shown in FIG. 9; 
     FIG. 11 is a bottom side view, partly cut away and partly in section, of the control timer shown in FIG. 9; 
     FIG. 12 is the side view of FIG. 9 partly in section; 
     FIG. 13 is a left end exterior view of the control timer shown in FIG. 9; 
     FIG. 14 is a bottom view of a timer body suitable for use in the control timer shown in FIG. 9; 
     FIG. 15 is an exterior side view of the timer body shown in FIG. 14 rotated  90  to the left; 
     FIG. 16 is a top view of an alternative embodiment of the rotisserie grill of FIG. 1 (lid removed for clarity); 
     FIG. 17 is an electrical schematic diagram of power delivery to the heaters of the rotisserie grill shown in FIG. 16; 
     FIG. 18 is a table illustrating a representative pattern of “on” and “off” cycles for the heaters of the rotisserie grill illustrated in FIGS. 6-8; 
     FIG. 19 is a bottom view of a control timer with four micro switches attached thereto; and 
     FIG. 20 is an electrical schematic diagram of power delivery to the heaters of the rotisserie grill shown in FIGS.  1 - 5 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1-5 illustrate the overall configuration of a first preferred embodiment of a rotisserie grill  10  in accordance with the present invention. The rotisserie grill  10  defines a vertical cooking chamber  9  having a greater width (measured left to right of FIGS. 1,  4  and  5 ) than depth (measured left to right in FIGS.  2  and  3 ). 
     The front of the rotisserie grill (best seen in FIG. 1) includes a window  16  through which the food in the cooking chamber may be observed. A knob  25  for a control timer  20  is also arranged on the front of the rotisserie grill  10 . The cooking chamber  9  is defined by a double wall  14  mounted to a base  12 . The upper portion of the double wall includes slit vents  17 . A baffle  15  is arranged within the double wall  14  so that the vents  17  do not open directly into the cooking chamber  9 . 
     The oval shape of the cooking chamber  9  is clearly illustrated in FIG. 4. A rack  5  is arranged in the center of the cooking chamber  9 . The rack comprises a tubular centerpiece  8 , around which are secured an arrangement of metal bars for supporting food (not illustrated). The hollow centerpiece  8  of the rack  5  surrounds and substantially encloses the center-heating element  6 . The illustrated preferred embodiment  10  includes two side heating elements  2 ,  4  arranged adjacent the front and rear walls of the cooking chamber  9 . The side heating elements  2 ,  4  are curved to the shape of the wall  14  of the cooking chamber  9  as best seen in FIG.  4 . 
     FIG. 5 illustrates the rear side heating element  4  and center element  6  relative to the other components of the rotisserie grill  10 . Each side heating element  2 ,  4  has an arcuate serpentine configuration best seen in FIGS. 3 and 5. This arcuate serpentine configuration provides an extended heat radiating surface for each side heater element  2 ,  4 . The serpentine configuration of the side heater elements  2 ,  4  also aids in evenly distributing heat generated thereby over the surface of the food fixed to the rack  5 . FIG. 16 illustrates an alternative side heater arrangement in which four side heaters  2   a ,  2   b ,  4   a  and  4   b  are arranged around the periphery of the cooking chamber  9 . 
     FIG. 5 also illustrates a drip pan  7  arranged beneath the centrally located rack  5  to catch juices and/or fat from the cooking food. A close-fitting lid  18  to retain heat and moisture during cooking closes off the cooking chamber  9  from above. The side sectional view of FIG. 3 shows that the side heating elements  2 ,  4  do not completely surround the cooking chamber  9 . However, the oval configuration of the cooking chamber  9  makes this unnecessary by permitting the laterally extended side-heating elements  2 ,  4  to effectively surround food secured to the centrally located rack  5 . The four side heaters  2   a ,  2   b ,  4   a ,  4   b  of FIG. 16 more evenly surround the food. 
     The heaters used in accordance with the present invention are of the tubular type, having a metallic outer tube that surrounds a resistive heating element encased in heat resistant insulation. The power requirements of such heating elements vary with the gage of the resistive heating element as well as the overall length of the heater. In the illustrated preferred embodiment of FIGS. 1-5, the center heater  6  consumes in the range of 160-200 watts of electrical power. Each side heater  2 ,  4  consumes in the range of 800-1000 watts of electrical power. The maximum temperature at the outer tube of this type of heater is approximately 760° C. The four side heaters  2   a ,  2   b ,  4   a ,  4   b  of FIG. 16 consume between 300 and 500 watts each. 
     A control timer  20  permits the user to select the duration of cooking. For the duration of cooking selected by the user, the control timer  20  alternately applies electrical current to the side heaters  2 ,  4 . Thus, the side heaters  2 ,  4  alternately apply cooking heat to food arranged on the rack  5 . This intermittent application of heat simulates relative movement between the food and the heat sources produced in the typical rotating rotisserie. In accordance with a significant aspect of the present invention, the control timer  20  applies electrical power to the central heater for the selected duration of cooking. Heat generated by the center heater  6  is taken up by the metallic rack  5  and transmitted to the food. Heat generated by the side heaters  2 ,  4  is radiated directly onto the food and also reflected onto the food by the adjacent wall  14  surrounding the cooking chamber  9 . Heat generated by the various heaters is trapped within the cooking chamber by the lid  18 . 
     In accordance with a particular aspect of the invention, a control timer  20  such as that illustrated in FIGS. 9-15 controls the flow of electric current to the center and side heaters. A control timer body  22  includes an electric timer responsive to the position of a control knob  25 . Rotation of the control knob  25  approximately 270° sets the maximum cooking duration of 60 minutes. Of course, the user may select any cooking duration up to the maximum by rotation of the control knob  25  some smaller amount. 
     A control shaft  26  projects from the control timer body  22  opposite the control knob  25 . The shaft  26  is rotated by the control timer for the duration of a timed event, e.g. the selected duration of cooking. The shaft  26  includes two sets of projections  27 , one of which, in the disclosed embodiment, engage a cam wheel  28  for rotation with the shaft  26 . The cam wheel  28  illustrated in FIG. 10 comprises a series of peaks  50  separated by concave arcs defining troughs  51 . A micro switch  24  is arranged adjacent the cam wheel  28  for actuation by the peaks  50  of the cam wheel. The micro switch  24  is provided with normally open and normally closed contacts connected to terminals  23 . In accordance with the present invention, one side heater is connected to the normally open contacts of the micro switch  24  while the other side heater is connected to the normally closed contacts. In this manner, the side heaters  2 ,  4  are alternatively provided with power as the control timer shaft  26  rotates. In accordance with the present invention, this on-off sequence repeats every one to two minutes. The center heater  6  is connected directly to the control timer  20  such that the center heater  6  is provided with electrical power for the duration of the cooking cycle. When the selected cooking duration has elapsed, the control timer  20  removes electrical power from all the heating elements  2 ,  4 ,  6 . 
     FIG. 20 illustrates an alternative electrical schematic for the rotisserie grill embodiment of FIGS. 1-5. Instead of routing power to both side heaters through one micro switch, power is delivered to the side heaters  2 ,  4  through micro switches  24  actuated by the control timer  20 . It should be noted that power is delivered to center heater  6  continuously, while side heaters  2 ,  4  receive power intermittently through switches  24  actuated by a cam wheel driven by the control timer as will be explained below. 
     FIG. 17 illustrates one possible electrical schematic for the rotisserie grill of FIG.  16 . Power to each of the four side heaters  2   a ,  2   b ,  4   a ,  4   b  is delivered through a micro switch actuated by a cam wheel driven by the control timer  20 . Power is delivered to the side heaters in an alternating pattern to simulate relative movement between the heat source and the food on the stationary rack  5 . 
     The only moving parts in the inventive rotisserie grill are those of the control timer  20 . The control timer  20  is of the type driven by a coiled spring (not illustrated). Turning the control knob  25  in a clockwise direction tensions the spring, which unwinds in a controlled manner to turn the control timer shaft  26  at a substantially constant speed. The control timer body  22  contains the tension and controlled release mechanisms as well as a first set of electrical contacts  22   a  responsive to the timer. Connectors  21  are electrically connected to the internal contacts  22   a  of the control timer  20 . In the embodiments of FIGS. 1-5 and  16 , power is provided to the center heater  6  by these internal electrical contacts  22   a  and are electrically connected for the duration of a selected cooking cycle. FIGS. 17 and 20 illustrate how power to all the heating elements is controlled by internal electrical contacts  22   a . FIGS. 17 and 20 also illustrate that each side heating element may be provided with its own micro switch  24  for control of electrical energy delivered thereto. 
     It can be seen from FIGS. 12 and 15 that the control timer shaft  26  includes two pairs of projections  27 . One pair of projections  27  is used to rotate the cam wheel  28 . The second set of projections may be fitted with a similar cam/micro switch arrangement for control of further heating elements. In addition, alternative cam profiles and switch arrangements are possible. Each micro switch  24  is a single pole, single throw switch capable of transmitting the high current required by the side heaters,  2 ,  4  without resort to a relay circuit. FIG. 19 illustrates how four micro switches can be arranged around the base  22  of a control timer  20  for actuation by a single cam wheel. 
     FIGS. 6-8 illustrate an alternative embodiment of rotisserie grill  40  in accordance with the present invention. The alternative rotisserie grill  40  defines a horizontal-cooking chamber  41  in which straight heating elements  43   a ,  43   b ,  45   a ,  45   b  are arranged across the top and bottom of the cooking chamber  41 . A door  42  closes off the front of the cooking chamber  41 . In the illustrated embodiment  40 , two heating elements  43   a ,  43   b  are arranged above and two heating elements  45   a ,  45   b  are arranged below a horizontal cooking rack  48 . A tray  47  is disposed below the cooking rack  48  to catch drippings. A control timer  20  alternately applies power to the heating elements  43   a ,  43   b ,  45   a ,  45   b . The heating elements are alternately provided with electrical power to simulate relative movement between the food and the heat sources. FIG. 18 illustrates one possible pattern of energy delivery to the four heaters  43   a ,  43   b ,  45   a ,  45   b . A second control knob  30  is provided on the face of the rotisserie grill for the purpose of overall temperature control as is known in the art. 
     While preferred embodiments of the foregoing invention have been set forth for purposes of illustration, the foregoing description should not be deemed a limitation of the invention herein. Accordingly, various modifications, adaptations, and alternatives may occur to one skilled in the art without departing from the spirit and the scope of the present invention.