Abstract:
A high temperature convection fan device that improves the operation of an oven is provided. Each oven convection fan device component is designed to withstand the harsh environment and elevated temperatures common to an oven. Sources of energy include but are not limited to wind-up springs and/or drawing electric power from the oven lamp socket. Other solutions provide additional features including but not limited to lighting, sensors, control systems and/or displays.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    Embodiments of the present invention generally relate to a convection fan for ovens. More specifically, embodiments of the present invention relate to an after market device that can be incorporated in an ordinary oven to improve performance. 
         [0003]    2. Description of the Related Art 
         [0004]    As people become more aware of rising energy costs and environmental concerns, there is an opportunity to improve the efficiency of appliances and in particular household kitchen ovens. For new construction, renovations and replacements, consumers have the choice to upgrade the oven to a convection oven with a built-in convection fan. Consider that repairing an oven is common since replacement oven parts are widely available, inexpensive and easy to replace. Built-in ovens are often hard to match in size, color, style and require a licensed contractor to handle the electrical power connections. Thus, ovens last a long time. 
         [0005]    This invention allows one to enhance an existing oven without the waste, cost, inconvenience, construction, time or hassle of matching appliances required when replacing an otherwise perfectly good oven. 
         [0006]    It is well understood in thermodynamics that heat can be transferred using convection, conduction and/or radiation. 
         [0007]    It is well understood that closed loop control systems and feedback control systems can be used to improve the individual characteristics of ovens, heaters, motors or fans. Previous to this invention, such closed loop control systems were restricted to include the oven device such as an integrated convection oven. Previous to this invention, the closed loop control system components necessary to operate in the harsh high temperature environment of an oven were expensive relative to the cost of a consumer oven or consumer oven accessory item. 
         [0008]    It is well understood in cooking to display food temperature. It is well understood that temperature probes are used to monitor food temperature and signal an alarm or make a sound when a desired temperature is achieved. These devices are limited in ability and do not offer an air moving device and the related benefits. 
         [0009]    Previous to this invention, one could purchase table top convention ovens and convection toaster ovens. These devices occupy additional counter space and lack the performance of a full size oven. The exteriors are generally hotter, the insulation is poorer and the efficiency is low when compared to a conventional oven. These devices include one or more heating elements that are more for reheating a small or single serving. 
         [0010]    Previous to this invention, a variety of electric fans are available that operate at common room temperatures. These room temperature devices are unable to operate in the sustained high temperature environment found in or around a hot oven. Common fan parts made from plastic and rubber would melt. Paper parts would burn. Electrical insulation on wires and particularly motor windings would fail. Materials would expand and change shape causing moving parts to stick. Energy source devices such as batteries might even explode. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention describes a system for an oven convection fan. This fan allows a user to upgrade the performance of their existing oven. The user obtains a simple and easy way to reduce power consumption, shorten cooking time, lower room temperature on a hot summer day, bake more uniformly, roast more consistently, and/or save money. 
         [0012]    Variation of power source solutions, energy conversion solutions, transmissions solutions, air movement solutions, and/or control systems are combined to create similar yet different fans for use in ovens. Other solutions incorporate sensors to detect temperatures, count time, measure air flow rates, and/or measure power consumption to better control the system and/or report information to the user. 
         [0013]    In some variations, the system is partitioned with some parts located outside of the oven while other parts are located within the oven. In this way, there is more flexibility in the ease of use and/or the high temperature design requirements for the system. 
         [0014]    Power is equal to temperature multiplied by flux (heat flow rate). By raising the amount of air circulation, the oven can produce the same amount of power using a lower temperature at the heating element. Stated another way, given the same temperature at the heating element, the oven produces more power due to the higher flux. The ability to make adjustments in both temperature and flux increases the ability to properly control the cooking process. 
         [0015]    Similarly the food (such as a turkey) within the oven cooks more evenly and quickly. Better circulation results in more consistent crusts when baking and crisp exteriors when roasting. Baking or roasting times can be shortened. Total power consumption can be reduced. 
         [0016]    Many of the advantages of an integrated convection oven are obtained at a fraction of the cost. A separate convection fan device is also easily replaced and machine washable. Multiple fans can be used together. 
         [0017]    A number of novel methods of locating the convection fan within the oven help to maximize useful space. The design of the fan is improved to produce more efficient air flow in low cost production methods. Some designs of the fan incorporate novel sources of power such as using the pre-existing oven light bulb socket and the pre-existing oven light switch. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    Advantage of one or more disclosed embodiments may become apparent upon reading the following detailed description and upon reference to the drawings in which: 
           [0019]      FIG. 1  is a sketch depicting an illustrative system dynamics in and around an oven with a convection fan device, according to one or more embodiments described herein; 
           [0020]      FIG. 2  is a block diagram depicting an illustrative oven convection fan device, according to one or more embodiments described herein; 
           [0021]      FIG. 3  is a block diagram depicting an illustrative oven light and convection fan device, according to one or more embodiments described herein; 
           [0022]      FIG. 4  is a block diagram depicting an illustrative oven sensor(s) and convection fan device, according to one or more embodiments described herein; 
           [0023]      FIG. 5  is a sketch depicting an illustrative wind-up propeller fan device, according to one or more embodiments described herein; 
           [0024]      FIG. 6  is a sketch depicting an illustrative wind-up impeller fan device, according to one or more embodiments described herein; 
           [0025]      FIG. 7  is a sketch depicting an illustrative impeller device, according to one or more embodiments described herein; 
           [0026]      FIG. 8  is a sketch depicting an illustrative tray style oven fan device, according to one or more embodiments described herein; 
           [0027]      FIG. 9  is a sketch depicting an illustrative oven light and convection fan device, according to one or more embodiments described herein; 
           [0028]      FIG. 10  is a sketch depicting an illustrative magnetic oven convection fan device, according to one or more embodiments described herein; 
           [0029]      FIG. 11  is a sketch depicting an illustrative inductive oven convection fan device, according to one or more embodiments described herein; 
           [0030]      FIG. 12  is a sketch depicting an illustrative cable driven oven convection fan device, according to one or more embodiments described herein; 
           [0031]      FIG. 13  is a sketch depicting an illustrative belt driven oven convection fan device, according to one or more embodiments described herein. 
           [0032]      FIG. 14  is a logic flow diagram depicting an illustrative closed loop control system, according to one or more embodiments described herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    Described herein are exemplary systems and methods for an oven convection fan device. In the following description, numerous specific details are set forth to provide a thorough understanding of various embodiments. However, it will be understood by those skilled in the art that the various embodiments may be practiced without the specific details. In other instances, well known methods, procedures, components, and circuits have not been illustrated or described in detail so as not to obscure the particular embodiments. 
         [0034]    The term “air moving device” includes but is not limited to turbines, propellers, impellers, blades, wings, blowers, pumps, compressors, rotating or non-rotational air moving devices, piezo electric vibrating devices, MEMS (Micro Electro Mechanical System), explosive devices, pressure difference generating devices, temperature difference generating devices, velocity difference generating devices, mass difference generating devices, arrays of air moving devices, and combinations of air moving devices. 
         [0035]    The term “energy source device” includes but is not limited to electric, mechanical, human, fluidic, chemical, rotational, biological, nuclear, atomic, regenerative types of power, connectors to energy, energy plugs, energy sockets, and combinations of energy source devices. Electric power includes but is not limited to AC (alternating current), DC (direct current), switching, inductive, magnetic, hybrid, battery, thermal electric, and combinations of electric power types. Mechanical power includes but is not limited to spring, linear spring, weight, mass, and combinations of mechanical power types. Some sources of energy are stored locally such as from within a battery or spring while others are introduced externally such as from an electrical outlet, bulb socket or hand wound spring. 
         [0036]    The term “power conversion device” includes but is not limited to motors, transformers, springs, linear springs, levers, pumps, gears, magnets, coils, wires, electronics, mechanisms, and combinations of power conversion devices. 
         [0037]    The term “transmission device” includes but is not limited to shafts, gears, magnetic coupling, rods, arms, clutches, belts, cables, pulleys, bearings, rotational devices, linear motion devices, non-linear motion devices, and combinations of transmission devices. 
         [0038]    The term “control device” includes but is not limited to on/off switches, variable switches, limit switches, electronic switches, mechanical switches, chemical switches, fluidic switches, micro switches, control systems, feedback control systems, closed loop control systems, open loop control systems, external switches, oven light bulb switches, touch sensors, smart grid controllers, power management controllers, safety switches, fuses, temperature controlled switches, thermostats, bi-metal materials, wireless control systems, wired control systems, remote control systems, motion sensing control systems, proximity control systems, software, computers, and combinations of control devices. 
         [0039]    The term “mechanical device” includes but is not limited to hangers, stands, clips, trays, bars, screws, wires, silicon parts, metal parts, ceramic parts, stone parts, synthetic parts, high temperature parts and combinations of mechanical devices. 
         [0040]    The term “lighting device” includes but is not limited to light bulbs, LED lights, chemical lights, gas fire, fire, light reflectors, lens, focusing systems, optical films, wave guides, fiber optics, photon emitting solutions and combinations of lighting devices. 
         [0041]    The term “sensor” includes but is not limited to thermometers, thermistors, thermostats, thermocouples, bi-metal materials, timers, clocks, temperature measuring devices, flow measuring devices, pressure measuring devices, voltage meters, current meters, power measuring devices, ohm meters, capacitive sensors, resistive sensors, impedance sensors, electronic instruments, mechanical instruments, size measuring devices, scales, weight measuring instruments, moisture measuring instruments, odor detectors, flavor detectors, chemical measuring instruments, fire detectors, smoke detectors, carbon monoxide detectors, radiation detectors, infrared detectors, and combinations of sensors. 
         [0042]    High temperature materials include but are not limited to metal, plastic, glass, ceramic, stone, silicone, silicon, plastics, fluorinated ethylene propylene (FEP), polychloro triflouroethylene (PCTFE), perflouroalkoxy (PFA), vespel polyiminde, polyetherether-ketone (PEEK), Meldin 7001, Torlon 4203, Rulon, polybenzimidazole (PBI), polyimides (PI), polyvinylidene fluoride (PVDF), polycarbonate, and combinations of high temperature materials. Electrical conductive high temperature materials are useful for but not limited to circuits, motors, switches, power supplies, batteries, wires, sockets, plugs, electromagnets, inductors, sensors, semiconductors, processors, and logic. 
         [0043]      FIG. 1  is a sketch depicting an illustrative system dynamics in and around an oven  200  with an oven convection fan device  100 , according to one or more embodiments. In one or more embodiments, an oven convection fan device  100  is used to circulate air  201  within the oven  200 . The food  204  is commonly placed within a tray  202  on an oven shelf  206  or rack  206  within the oven  200 . The circulating air  201  transfers energy from the heating elements  208  to the food  204 . Within some ovens is an oven light bulb  210  that is inserted into a light socket  212  which is controlled from one or more oven light switches  214 . 
         [0044]    As cooking involves time  230 , various temperatures, thermal flux rates and/or air flow rates  228 , it is useful to know the measure of these values as they change. In control systems, these values are commonly called state variables. The temperature of various locations and elements are useful and include ambient temperature  220  of the room, oven temperature  222 , heating element temperature(s)  224 , and food temperature(s)  226 . 
         [0045]      FIG. 2  is a block diagram depicting an illustrative oven convection fan device  100 , according to one or more embodiments. In one or more embodiments, an energy source device  110  is attached to an air moving device  140  using a power conversion device  120  and a transmission device  130 . The rate of air movement is varied using a control device  170 . An example of a basic control device  170  is a switch that turns the oven convection fan device  100  on and off. The oven convection fan device  100  is located within an oven using a mechanical device  180 . An embodiment of the mechanical device  180  is to locate the oven convection fan device  100  in a convenient position within the oven that occupies less useful space and/or improves air circulation. 
         [0046]    The energy source device  110  is capable of withstanding the high temperatures found in or around an oven. A preferred embodiment of a high temperature energy source device  110  is a metal wind-up knob attached to a linear force spring. Another example of a high temperature energy source device  110  is to draw power from the oven light bulb socket. 
         [0047]    The air moving device  140  is capable of withstanding the high temperatures found in or around an oven. A preferred embodiment of a high temperature air moving  140  device is a metal impeller or propeller. Another embodiment of a high temperature air moving device  140  is a silicone impeller or propeller. 
         [0048]    The power conversion device  120  is capable of withstanding the high temperatures found in or around an oven. A preferred embodiment of a high temperature power conversion device  120  is a linear spring constructed from spring steel and related moving parts of metal. Another embodiment of a high temperature power conversion device  120  is an electric motor with high temperature insulation on the motor windings. 
         [0049]    The transmission device  130  is capable of withstanding the high temperatures found in or around an oven. An embodiment of a high temperature transmission device  130  is a set of gears or shafts manufactured from metal. 
         [0050]    The control device  170  is capable of withstanding the high temperatures found in or around an oven. An embodiment of a high temperature control device  170  is an on/off switch manufactured from metal. 
         [0051]    The mechanical device  180  is capable of withstanding the high temperatures found in or around an oven. A preferred embodiment of a high temperature mechanical device  180  is a hanger made from metal. Another embodiment of a high temperature mechanical device  180  is a mating electrical connector that fits an existing oven light bulb socket. 
         [0052]      FIG. 3  is a block diagram depicting an illustrative oven light and convection fan device  200 , according to one or more embodiments. In one or more embodiments, a lighting device  150  draws power from the energy source device  110  to illuminate the oven and items within the oven. 
         [0053]    An energy source device  110  is attached to an air moving device  140  using a power conversion device  120  and a transmission device  130 . The rate of air movement is varied using a control device  170 . An example of a basic control device  170  is a switch that turns the oven light and convection fan device  200  on and off. The oven light and convection fan device  200  is located within an oven using a mechanical device  180 . An embodiment of the mechanical device  180  is to locate the oven convection fan and lights system  200  in a convenient position within the oven that occupies less space and/or improves air circulation. 
         [0054]    The energy source device  110  is capable of withstanding the high temperatures found in or around an oven. An embodiment of a high temperature energy source device  110  is to draw power from the oven light bulb socket. 
         [0055]    The air moving device  140  is capable of withstanding the high temperatures found in or around an oven. An embodiment of a high temperature air moving  140  device is a metal impeller or propeller. Another embodiment of a high temperature air moving device  140  is a silicone impeller or propeller. 
         [0056]    The power conversion device  120  is capable of withstanding the high temperatures found in or around an oven. An embodiment of a high temperature power conversion device  120  is an electric motor with high temperature insulation on the motor windings. 
         [0057]    The transmission device  130  is capable of withstanding the high temperatures found in or around an oven. An embodiment of a high temperature transmission device  130  is a set of gears or shafts manufactured from metal. 
         [0058]    The control device  170  is capable of withstanding the high temperatures found in or around an oven. An embodiment of the control device  170  is to use the oven light on/off switch typically located outside of the oven chamber. 
         [0059]    The mechanical device  180  is capable of withstanding the high temperatures found in or around an oven. An embodiment of a high temperature mechanical device  180  is a mating electrical connector that fits an existing oven light bulb socket 
         [0060]    The lighting device  150  is capable of withstanding the high temperatures found in or around an oven. An embodiment of a high temperature light device  150  is an incandescent light bulb made mainly of glass and metal. 
         [0061]      FIG. 4  is a block diagram depicting an illustrative oven sensor(s) and convection fan device  300 , according to one or more embodiments. In one or more embodiments, one or more sensors  160  provide information to the control device  170 . The sensor or sensors  160  measure temperature(s), time, flow rate, power and other state variables. One use for the information from one or more sensors  160  is to improve the control of the air moving device  140 . 
         [0062]    One embodiment of a control system is to use a bi-metal material (as commonly found in a thermostat) to automatically turn on the air moving device  140  above a given temperature and/or automatically turn off the air moving device  140  below the same or different temperature. In this way, the fan would automatically turn on and off. 
         [0063]    Another use for the sensor information from one or more sensors  160  is to display status information to the user such as food temperature or cooking time remaining. 
         [0064]    An energy source device  110  is attached to an air moving device  140  using a power conversion device  120  and a transmission device  130 . The rate of air movement is varied using a control device  170 . An example of a basic control device  170  is a switch that turns the oven convection fan and sensor(s) system  300  on and off. The oven convection fan and sensor(s) system  300  is located within an oven using a mechanical device  180 . An embodiment of the mechanical device  180  is to locate the oven convection fan and sensor(s) system  300  in a convenient position within the oven that occupies less space and/or improves air circulation. 
         [0065]    The energy source device  110  is capable of withstanding the high temperatures found in or around an oven. An embodiment of a high temperature energy source device  110  is a metal wind-up knob attached to a linear force spring. Another example of a high temperature energy source device  110  is to draw power from the oven light bulb socket. 
         [0066]    The air moving device  140  is capable of withstanding the high temperatures found in or around an oven. An embodiment of a high temperature air moving  140  device is a metal impeller or propeller. Another embodiment of a high temperature air moving device  140  is a silicone impeller or propeller. 
         [0067]    The power conversion device  120  is capable of withstanding the high temperatures found in or around an oven. An embodiment of a high temperature power conversion device  120  is a linear spring constructed from spring steel and related moving parts of metal. Another embodiment of a high temperature power conversion device  120  is an electric motor with high temperature insulation on the motor windings. 
         [0068]    The transmission device  130  is capable of withstanding the high temperatures found in or around an oven. An embodiment of a high temperature transmission device  130  is a set of gears or shafts manufactured from metal. 
         [0069]    The control device  170  is capable of withstanding the high temperatures found in or around an oven. An embodiment of a high temperature control device  170  is and on/off switch manufactured from metal. 
         [0070]    The mechanical device  180  is capable of withstanding the high temperatures found in or around an oven. An embodiment of a high temperature mechanical device  180  is a hanger made from metal. Another embodiment of a high temperature mechanical device  180  is a mating electrical connector that fits an existing oven light bulb socket. 
         [0071]    The sensor device(s)  160  is(are) capable of withstanding the high temperatures found in or around an oven. An embodiment of a high temperature resistant sensor device is a bi-metal strip that senses oven temperature. Another embodiment of a high temperature resistant sensor device that measures food temperature is a thermocouple. 
         [0072]      FIG. 5  is a sketch depicting an illustrative wind-up propeller fan device  300 , according to one or more embodiments. In one or more embodiments, the energy source device  110  is a hand wound spring attached to an air moving propeller device  142  through a power conversion device  120  and a transmission device  130 . An embodiment of the spring is a linear force spring. The energy stored in the spring is released through a time release mechanism and converted to rotational force which is transmitted to the air moving device  142  through shafts and/or gears. 
         [0073]    The air moving propeller device  142  is turned on and off using a control device  170 . An embodiment of the mechanical device  180  is a mechanical hanging device that suspends the wind-up propeller fan device  300  from an oven rack or shelf. 
         [0074]    Air intake moves generally co-axially towards the propeller device  142 . The air exhaust moves generally co-axially away from the propeller device  142 . 
         [0075]      FIG. 6  is a sketch depicting an illustrative wind-up impeller fan device  310 , according to one or more embodiments. In one or more embodiments, the energy source device  110  is embodied by a hand wound spring attached to an air moving impeller device  144  through a power conversion device  120  and a transmission device  130 . A preferred embodiment of the spring is a linear force spring. The energy stored in the spring is released through a time release mechanism and converted to rotational force which is transmitted to the air moving device  144  through shafts and/or gears. 
         [0076]    The air moving impeller device  144  is turned on and off using a control device  170 . A preferred embodiment of the mechanical device  180  is a mechanical hanging device that suspends the wind-up propeller fan device  300  from an oven rack or shelf. 
         [0077]    Air intake moves generally co-axially towards the impeller device  144 . The air exhaust moves generally radially away from the impeller device  144 . 
         [0078]      FIG. 7  is a sketch depicting an illustrative impeller device  148 , according to one or more embodiments. In one or more embodiments, impeller device  148  uses one or more conic section to approximate the complex high order surface of an efficient impeller. In an embodiment, each impeller blade is approximated with two linear sections that may be bent from a flat or nearly flat piece of material  146 . Another embodiment is a combination of propeller and impeller geometries to improve air draw towards the central portion of the impeller and then accelerate the air radially away from the impeller. 
         [0079]      FIG. 8  is a sketch depicting an illustrative tray style oven fan device  320 , according to one or more embodiments. In one or more embodiments, the mechanical tray device  180  allows the tray style oven fan device  320  to be placed in a horizontal position such as placed on an oven rack or shelf. In an embodiment, this tray style oven fan device  320  may be incorporated into a food tray or used in conjunction with a standalone food tray. 
         [0080]    An embodiment of the air moving device is an impeller device  144  with air intake generally co-axial and air exhaust generally radial to the impeller device  144 . 
         [0081]    The energy source device is attached to the impeller device  144  through a power conversion device  120  and transmission device  130 . An embodiment is to use a hand wound linear force spring. Another embodiment is to use a machine such as a power drill to assist in winding the linear force spring. 
         [0082]      FIG. 9  is a sketch depicting an illustrative oven light and convection fan device  400 , according to one or more embodiments. In one or more embodiments, the energy source device  110  provides electricity to the lighting device  150  and the power conversion device  120 . 
         [0083]    The power conversion device  120  converts the electrical energy to rotational energy which is transmitted to the air moving device  140  using a transmission device  130 . An embodiment of the power conversion device  120  is an electric motor with high temperature windings  420 , high temperature rotor  432 , and high temperature motor bearing  422  able to operate at the temperatures commonly found within an oven. 
         [0084]    The transmission device  130  connects the motor rotor  432  to the air moving device  140 . The air moving device  140  draws air into the air intake  436  and pushes air out the exhaust  434 . 
         [0085]    We teach that the control device is provided by the oven light bulb switch located externally to the oven chamber. 
         [0086]    The mechanical device  180  is fitted to the oven light bulb socket. An embodiment is to use a screw thread  430  that mates with the existing oven light bulb socket. The shape of the oven light and convection fan device  400  is designed to mate the existing oven light bulb opening allowing the lighting device  150  to perform in a similar manner as the original oven light bulb. 
         [0087]      FIG. 10  is a sketch depicting an illustrative magnetic oven convection fan device  500 , according to one or more embodiments. In one or more embodiments, the energy source device  110  and power conversion device  120  are located outside of the oven  502 . An embodiment of the energy source device  110  is one or more electric batteries. An embodiment of the power conversion device  120  is an electric motor. 
         [0088]    The transmission device is partitioned such that the outside magnets  530  of the transmission device are located outside of the oven  502  and the inside magnets  532  of the transmission device are located inside of the oven  504 . The outside magnets  530  of the transmission device creates a magnetic force which is transmitted through the oven door glass  506  driving the inside magnets  532 . 
         [0089]    The air moving device  140  is located inside the oven  504 . The air moving device  140  is propelled by the energy source device  110  through the power conversion device  120  and transmission devices outside magnets  530  and inside magnets  532 . 
         [0090]    The mechanical device  180  is located on both the inside  502  and outside  504  of the oven door glass  506 . An embodiment of the mechanical device  180  is to use magnets. 
         [0091]      FIG. 11  is a sketch depicting an illustrative inductive oven convection fan device  550 , according to one or more embodiments. In one or more embodiments, the inductive energy source device  560  is located outside of the oven  502 . The inductive energy receiver device  562  is located inside of the oven  504 . The outside inductive energy source device  560  creates an inductive field which is transmitted through the oven door glass  506  and received by the inductive energy receiver device  562 . 
         [0092]    The air moving device  140  is located inside the oven  504 . The air moving device  140  is propelled by the inductive energy source device  560  through the inductive energy receiver  562 , and power conversion device  120 . 
         [0093]    The mechanical device  180  is located on both the inside  502  and outside  504  of the oven door glass  506 . An embodiment of the mechanical device  180  is to use magnets. 
         [0094]      FIG. 12  is a sketch depicting an illustrative cable driven oven convection fan device  600 , according to one or more embodiments. In one or more embodiments, the energy source device  110  and power conversion device  120  are located outside of the oven  502 . An embodiment of the energy source device  110  is one or more electric batteries. An embodiment of the power conversion device  120  is an electric motor. 
         [0095]    A flexible cable  630  is routed around the oven door  508  and used as a transmission device to attach the power conversion device  120  to the air moving device  140 . An embodiment of the flexible cable  630  is a spiral metal drive shaft with a metal sleeve that is thin enough to fit around the oven door  508  insulation or gaps in the insulation. 
         [0096]    The air moving device  140  is located inside the oven  504 . The mechanical device  180  is located on both the inside and outside of the oven door  508 . An embodiment of the mechanical device  180  is to use magnets. 
         [0097]      FIG. 13  is a sketch depicting an illustrative belt driven oven convection fan device  650 , according to one or more embodiments. In one or more embodiments, the energy source device  110  and power conversion device  120  are located outside of the oven  502 . An embodiment of the energy source device  110  is one or more electric batteries. An embodiment of the power conversion device  120  is an electric motor. 
         [0098]    A flexible belt device  660  is routed around the oven door  508  and used as a transmission device to attach the power conversion device  120  to the air moving device  140 . An embodiment of the flexible belt  660  is a thin metal strap within a metal sleeve that is thin enough to fit around the oven door  508  insulation or gaps in the insulation. 
         [0099]    The air moving device  140  is located inside the oven  504 . The mechanical device  180  is located on both the inside  502  and outside  504  of the oven door  508 . An embodiment of the mechanical device  180  is to use magnets. 
         [0100]      FIG. 14  is a logic flow diagram depicting an illustrative closed loop control system  700 , according to one or more embodiments. The transfer function  740  characterizes the behavior of the oven convection fan device using mathematical formulae or computational programs. The input vector  710  consists of one or more set point values. One embodiment of the input vector  710  is a set of values that includes cooking time, fan speed and desired food temperature. The state variables  750  is a vector array of data collected from sensor devices. One embodiment of the state variable  750  is a set of data that includes time, oven temperature, food temperature, heating element temperature, ambient temperature, fan speed, thermal flux rate, air flow rate, and power. 
         [0101]    The control function  760  accepts the state variables  750  to produce a control vector  730 . The control vector  730  is combined with the input vector  710  using a sum device  720 . In this way, the input control vector  730  values are modified before being used by the oven control device to more precisely achieve the desired cooking result. 
         [0102]    The display  780  allows the user to observe the values for one or more state variables  750 . One embodiment is to show an indication of the food temperature. Another embodiment is to show an indication of the amount of time remaining before the desired cooking is completed.