Patent Publication Number: US-10307016-B2

Title: System and method for operating rotisserie oven

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application represents a divisional application of U.S. application Ser. No. 12/638,448, filed Dec. 15, 2009. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention pertains to the art of cooking and, more particularly, a system and method of operating a rotisserie oven. 
     Description of the Related Art 
     In general, placing a rotisserie assembly in a domestic oven is known in the art of cooking appliances. In typical arrangements, a rotisserie arm is positioned in an oven cavity for supporting food to be cooked. The rotisserie arm is typically driven by a motor which causes the rotisserie arm and food to rotate at a constant speed. In this known arrangement, the motor is switched off when the oven door is opened to stop the rotation of the rotisserie arm in order to baste or brown the food supported on the rotisserie arm. For example, U.S. Pat. No. 5,639,497, which discloses a cooking control system for rotisserie ovens, includes an assembly for driving a food supporting spit. When the oven door is opened, the rotisserie driving assembly is disabled. Similarly, each of U.S. Pat. Nos. 5,361,686 and 5,451,744 discloses a rotisserie oven wherein, when the oven door is opened, the motor is disabled. Conversely, when the door is again closed in each of these ovens, power is restored to the motor and the motor resumes operation. 
     When performing a rotisserie cooking operation, periodic basting of the food product being rotated may be desirable. Using these known constructions, only a single side of the food product would be exposed upon opening of the door such that, if a user wanted to baste all sides of the food product, the oven door would need to be repeatedly opened and closed in order to rotate the food for basting. Obviously, this is burdensome to the user and would require accuracy to open the door at precisely the correct time when the desired part of the food product to be basted is exposed. Based on the above, there exists a need in the art for a cooking appliance having a rotisserie motor which can be operated even when the oven door is open. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an oven for performing a rotisserie cooking operation and a method of performing a rotisserie operation. In accordance with a preferred embodiment of the invention, the oven includes an oven cavity having a door movable between open and closed positions in order to selectively provide access to the oven cavity, at least one heating element exposed to heat the oven cavity and a rotisserie arm adapted to support a food product positioned within the oven cavity. A motor is operatively coupled to the rotisserie arm for driving the rotisserie arm and rotating the food product on the arm. The oven also includes a control interface having a rotisserie cooking mode input and a control system for controlling the rotisserie motor and the heating element. Most importantly, the control system enables the motor to further rotate the rotisserie arm even when the door is in the open position. In the most preferred form of the invention, the control system causes the rotisserie motor to cycle on and off to allow for an intermittent 360 degree rotation of the food product supported on the rotisserie arm while the oven door is in the open position. 
     Additional objects, features and advantages of the present invention will become more readily apparent from the following detailed description of preferred embodiments when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a double wall oven incorporating a rotisserie arrangement in accordance with the present invention; and 
         FIG. 2  is a block diagram illustrating a control system for the rotisserie arrangement of the invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     With initial reference to  FIG. 1 , a cooking appliance constructed in accordance with the present invention is generally indicated at  2 . Cooking appliance  2 , as depicted, constitutes a double wall oven. However, it should be understood that the present invention not limited to this model type and can be incorporated into various types of oven configurations, e.g., cabinet mounted ovens, as well as both slide-in and free standing ranges. In any event, in the embodiment shown, cooking appliance  2  constitutes a dual oven wall unit including an upper oven  4  having upper oven cavity  6  and a lower oven  8  having a lower oven cavity  10 . Cooking appliance  2  includes an outer frame  12  for supporting both upper and lower oven cavities  6  and  10 . 
     In a manner known in the art, a door assembly  14  is provided to selectively provide access to upper oven cavity  6 . As shown, door assembly  14  includes a handle  15  at an upper portion  16  thereof. Door assembly  14  is adapted to pivot at a lower portion  18  to enable selective access to within oven cavity  6 . In a manner also known in the art, door  14  is provided with a transparent zone or window  22  for viewing the contents of oven cavity  6  while door  14  is closed. A corresponding door assembly  24  including a handle  25  and a transparent zone or window  26  is provided to selectively access lower oven cavity  10 . 
     As best seen in  FIG. 1 , oven cavity  6  is defined by a bottom wall  27 , an upper wall  28 , opposing side walls  30  and  31  provided with a plurality of vertically spaced side rails  32 , and a rear wall  33 . In the preferred embodiment shown, bottom wall  27  is constituted by a flat, smooth surface designed to improve the cleanability of oven cavity  6 . Arranged about bottom wall  27  of oven cavity  6  is a bake element  40 . Also, a top broiler element  42  is arranged along upper wall  28  of oven cavity  6 . Top broiler element  42  is provided to enable a consumer to perform a grilling process in upper oven  4  and to aid in pyrolytic heating during a self-clean operation. As shown, both bake element  40  and top broiler element  42  are constituted by sheathed electric resistive heating elements. 
     Based on the above, cooking appliance  2  actually constitutes an electric, dual wall oven. However, it is to be understood that cooking appliance  2  could equally operate on gas, either natural or propane. In addition, cooking appliance  2  may be a single wall oven or a combination of a wall oven and a microwave oven. In the preferred embodiment shown in  FIG. 1 , oven cavity  6  employs both radiant and convection heating techniques for cooking food items therein. To this end, rear wall  33  is shown to include a convection fan or blower  44 . Although the exact position and construction of fan  44  can readily vary, as shown, fan  44  draws in air at a central intake zone (not separately labeled) and directs the air into oven cavity  6  in a radial outward direction. Although not depicted in this figure, another sheathed electric heating element is provided behind cover  46 , which preferably takes the general form of a ring, with this heating element extending circumferentially about fan  44  in order to heat the radially expelled air flow. 
     In addition to the heating elements described above, the oven  10  also includes a steam system (identified below) exposed to oven  4  in order to introduce steam into the cavity  6 . The steam system may include a boiler that heats water stored in the steam system. However, the steam system can be any suitable system that is capable of introducing steam directly into cavity  6  or introducing water that is turned into steam in the cavity  6  and is not limited to any particular steam system. 
     As further shown in  FIG. 1 , cooking appliance  2  includes an upper control panel  50  having a plurality of control elements. In accordance with one embodiment, the control elements are constituted by first and second sets of oven control buttons  52  and  53 , as well as a numeric pad  54 . Control panel  50  is adapted to be used to input desired cooking parameters and input initial operating conditions for cooking appliance  2 . More specifically, the first and second sets of control buttons  52  and  53 , in combination with numeric pad  54  and a display  62 , enable a user to establish particular cooking operations for upper and lower ovens  4  and  8  respectively. 
     Although a wide range of control configurations could be employed, in the embodiment shown in  FIG. 1 , first set of control buttons  52  includes a cancel button, a convection button, a bake button, a steam button, broil button, and a clean button. In addition, an oven light button  88  and a button  109  used to access more cooking options may also be provided. In a corresponding manner, second set of control buttons  53  may include a light button, a cancel button, a convection button, a bake button, a broil button, steam button and a clean button. 
     Since the general operational characteristics of cooking appliance  2  do not form part of the present invention, these features will not be discussed further here. Instead, the present invention is particularly directed to the operation of a rotisserie cooking mode to perform a desired cooking operation in cooking appliance  2 . To this end, control panel  50  is also provided with a rotisserie cooking mode input, such as in the form of a button  180 , used to control the operation of the rotisserie system of the invention as will now be described in detail. 
     A rotisserie arm  150 , or spit, is provided within cooking appliance  2  and is operatively coupled to a rotisserie motor  160  for rotating rotisserie arm  150 . Rotisserie arm  150  may be a removable attachment that fits within oven cavity  6  and coupled directly to oven walls  30  and  31 . However, in the embodiment shown in  FIG. 1 , rotisserie arm  150  is supported by a support frame  162  and is coupled to rotisserie motor  160  at a first end  165 . One end  167  of rotisserie arm  150  is provided with a sharp piercing point (not shown) for passing through food products. That is, a food product, such as a chicken, turkey or other food item to be cooked in the rotisserie cooking mode, is supported on support frame  162  through rotisserie arm  150 , such as outside of oven cavity  6 , and then first end  165  is drivingly engaged with an output shaft (not shown) of motor  160 . In this manner, rotisserie arm  150  supports food products for rotational movement within oven cavity  6 . 
     After a user mounts a food product on rotisserie arm  150  and selects a rotisserie cooking mode by depressing the rotisserie cooking mode input button  180  from control panel  50 , a control system  175  causes a rotisserie motor relay to close, thereby activating rotisserie motor  160 . Upon the selection of the rotisserie cooking mode, control system  175  also causes a heating element relay switch to close, thereby activating heating elements  40  and  42 . More specifically, as illustrated in  FIG. 2 , control system  175  controls the operation of rotisserie motor  160 , heating elements  40  and  42 , a steam system  185  and the convection system including fan  44 . Basically, control system  175  receives signals from control panel  50 , a temperature sensor  190  used to sense an operating temperature within oven cavity  6 , and a switch coupled to door  14  in order to regulate the operation of cooking appliance  2 . In connection with the invention, during a rotisserie cooking operation, control system  175  is able to cause rotisserie motor  160  to continuously operate, pulse or cycle, or stop as detailed below. 
     When door  14  is closed during the rotisserie cooking operation, rotisserie motor  160  is designed to normally rotate at a pre-established rotational speed. However, the speed of rotisserie motor  160  may also be controlled based on user inputs, timing sequences or sensed temperature values in order to maximize the cooking performance. More specifically, control system  175  can function to control rotisserie motor  160  to continuously rotate at a fixed speed, while cycling heating elements  40  and  42 , with or without fan  44  of the convection system, at present intervals, for the duration of the cooking operation. That is, so long as door  14  is closed. Alternatively, control system  175  can be configured to cycle both rotisserie motor  160  and heating elements  40  and  42  at preset intervals while door  14  is closed. In another variation, timing circuits within control system  175  can be user programmable through a plurality of methods, including switch settings and keypad entry on control panel  50 . For instance, it may be desired to perform a browning stage at a terminal phase of the overall cooking operation such that heating elements  40  and/or  42  are activated while rotisserie motor  160  is stopped to allow food product to be browned or seared. Therefore, it should be readily recognized that various interrelated control configurations are available for the cooking mode while door  14  is closed, including continuously activating rotisserie motor  160  while cycling heating elements  40  and  42 , simultaneously cycling both rotisserie motor  160  and the various heating sources, and activating heating element(s)  40  and/or  42  while rotisserie motor  160  is stopped for browning purposes. 
     In addition to the above control variations, cooking appliance  2  preferably includes temperature sensor  190  for detecting the air temperature within oven cavity  6 . Temperature sensor  190 , which may be a resistance temperature detector (RTD), signals the temperature in oven cavity  6  to control system  175 . As with the operation of a conventional oven, control system  175  uses the temperature signals to regulate the activation status of the various heating sources, with this regulation being used to solely control the activation state of the various heating sources as in a conventional oven or to also control the activation state of rotisserie motor  160  based on the particular control sequence employed as discussed above. 
     As indicated above, the invention contemplates a specified control for at least rotisserie motor  160  when door  14  is opened. More particularly, in accordance with the present invention, if a user opens door  14 , control system  175  will automatically cause rotisserie motor to cycle on and off, while also preferably disabling heating elements  40  and  42 . In a preferred form of the invention, rotisserie arm  150  is automatically pulsed to rotate 360 degrees whenever door  14  assumes an open position. In this manner, portions of the food product on rotisserie arm  150  will be successively exposed to the user such that the user can easily baste the entire food product. For example, rotisserie arm  150  and food product may rotate 90 degrees with each pulse or cycle of rotisserie motor  160  so that the user may baste quarter portions of the food product. In one advantageous embodiment, rotisserie motor  160  is slowly cycled on and off to allow for an intermittent 360 degree food product rotation in 20 to 30 seconds. 
     Although described with reference to preferred embodiments of the invention, it should be readily understood that various changes and/or modifications can be made to the invention without departing from the spirit thereof. For instance, the method of operating a rotisserie oven may be used in a single cavity oven. Further, the overall rotisserie operational cycle may automatically incorporate a steam heat function that may be activated during a portion of an overall rotisserie cooking operation. In general, the invention is only intended to be limited by the scope of the following claims.