Patent Publication Number: US-9418528-B2

Title: Oven appliance with cavity fire detection

Description:
FIELD OF THE INVENTION 
     The subject matter of the present disclosure relates generally to an oven appliance with features for detecting and containing a fire and/or smoke within the oven cavity. 
     BACKGROUND OF THE INVENTION 
     Oven appliances generally include a cabinet that defines a cooking chamber for baking or broiling food items therein. Oven appliances also generally include a self-cleaning feature for cleaning the cooking chamber. To heat the cooking chamber for baking, broiling, or self-cleaning, oven appliances include one or more heating elements, such as gas burners or electric resistance elements, which may be positioned at a top and/or bottom portion of the cooking chamber. During self-cleaning, particularly high temperatures are generated in the cooking chamber. Additionally, during baking and broiling operations, food items may be overcooked or may char or burn if a user is inattentive. Under certain conditions, smoke and/or a fire may even occur within the cooking chamber. However, the user may be unaware that such conditions have developed, and the user could be exposed to dangers posed by smoke and/or fire if the user is unaware that such conditions exist in the cooking chamber of the oven appliance. For example, the user could open the door of the oven appliance and thereby allow smoke to escape or provide fresh air that could fuel a fire. 
     Accordingly, an oven appliance with features for detecting a fire and/or smoke within the cooking chamber would be useful. Further, an oven appliance having features for containing a fire and/or smoke within the cooking chamber would be beneficial. Moreover, a method for using the features of an oven appliance to detect and contain a fire and/or smoke within the cooking chamber of the oven appliance also would be useful. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present invention provides an oven appliance with features for detecting and containing a fire and/or smoke within the cooking chamber of the oven appliance. A method for operating an oven appliance to detect and contain a fire and/or smoke within the cooking chamber of the oven appliance is also provided. Additional aspects and advantages of the invention will be set forth in part in the following description, may be apparent from the description, or may be learned through practice of the invention. 
     In a first exemplary embodiment, an oven appliance includes a cabinet defining an opening at a front portion of the cabinet. The cabinet also defines a cooking chamber configured for receipt of food items for cooking. The cooking chamber comprises a top wall, a bottom wall, a back wall, and opposing side walls. The oven appliance also includes a door mounted to the cabinet at the opening of the cabinet; the door is selectively adjustable between an open position and a closed position to permit selective access to the cooking chamber through the opening of the cabinet. Further, the oven appliance includes a heating element configured to heat the cooking chamber, and the heating element has an energy source. The oven appliance also includes a vent for exhausting fumes and gases generated during cooking from the cooking chamber; a temperature sensor; and a controller. The controller is configured for monitoring a rate of temperature change ΔT within the cooking chamber; comparing the rate of temperature change ΔT within the cooking chamber to a reference rate of temperature change ΔT ref  to determine if there is a fire in the cooking chamber and, if so, then providing a warning to a user of the oven appliance and containing the fire within the cooking chamber. 
     In a second exemplary embodiment, an oven appliance includes a cabinet defining an opening at a front portion of the cabinet. The cabinet also defines a cooking chamber configured for receipt of food items for cooking. The cooking chamber comprises a top wall, a bottom wall, a back wall, and opposing side walls. The oven appliance also includes a door mounted to the cabinet at the opening of the cabinet; the door is selectively adjustable between an open position and a closed position to permit selective access to the cooking chamber through the opening of the cabinet. Further, the oven appliance includes a heating element configured to heat the cooking chamber, and the heating element has an energy source. The oven appliance also includes a vent for exhausting fumes and gases generated during cooking from the cooking chamber; a temperature sensor; and a controller. The controller is configured for monitoring a current gas level; comparing the current gas level to a reference gas level to determine if there is a fire in the cooking chamber and, if so, then providing a warning to a user of the oven appliance and containing the fire within the cooking chamber. 
     In a third exemplary embodiment, a method is provided. The method includes the steps of monitoring a rate of temperature change ΔT within a cooking chamber of the oven appliance; comparing the rate of temperature change ΔT within the cooking chamber to a reference rate of temperature change ΔT ref  to determine if there is a fire in the cooking chamber and, if so, then providing a warning to a user of the oven appliance and containing the fire within the cooking chamber. 
     These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
         FIG. 1  provides a front view of an exemplary embodiment of an oven appliance of the present subject matter. 
         FIG. 2  is a perspective view of a cooking chamber of an exemplary embodiment of an oven appliance of the present subject matter. 
         FIG. 3  is a perspective view of a top portion of a cooking chamber of an exemplary embodiment of an oven appliance of the present subject matter, with a damper shown in the open position. 
         FIG. 4  is the perspective view of the top portion of a cooking chamber of the exemplary embodiment shown in  FIG. 3 , except with the damper shown in the closed position. 
         FIG. 5  illustrates a method of operating an oven appliance in accordance with one exemplary embodiment of the present subject matter. 
         FIG. 6  illustrates a method of operating an oven appliance in accordance with another exemplary embodiment of the present subject matter. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
     Referring to  FIGS. 1 and 2 , for this exemplary embodiment, oven appliance  100  includes an insulated cabinet  102  with an interior cooking chamber  104  defined by a top wall  112 , a bottom wall  114 , a back wall  116 , and opposing side walls  118 ,  120 . Cooking chamber  104  is configured for the receipt of one or more food items to be cooked. Oven appliance  100  includes a door  108  pivotally mounted, e.g., with one or more hinges (not shown), to cabinet  102  to permit selective access to cooking chamber  104 . A handle  110  is mounted to door  108  and assists a user with opening and closing door  108 . For example, a user can pull on handle  110  to open or close door  108  and access cooking chamber  104 . Further, door  108  includes a door lock  160 , which may be engaged to prevent access to cooking chamber  104  through door  108 , e.g., during a self-cleaning operation of oven appliance  100 . 
     Oven appliance  100  can include a seal (not shown) between door  108  and cabinet  102  that assists with maintaining heat and cooking fumes within cooking chamber  104  when door  108  is closed as shown in  FIG. 1 . Multiple parallel glass panes  122  provide for viewing the contents of cooking chamber  104  when door  108  is closed and assist with insulating cooking chamber  104 . A baking rack (not shown) for the receipt of food items or utensils containing food items may be slidably received onto embossed ribs or sliding rails  136 ,  138  such that the rack may be conveniently moved into and out of cooking chamber  104  when door  108  is open. 
     A heating element at the top, bottom, or both of cooking chamber  104  provides heat from an energy source to cooking chamber  104  for cooking. Such heating element(s) can be gas, electric, microwave, or a combination thereof. For example, in the embodiment shown in  FIG. 2 , oven appliance  100  includes a top heating element  124  and a bottom heating element  126 , which are connected to an energy source  162 . 
     Oven appliance  100  also may include a convection fan  142  positioned adjacent back wall  116  to provide air movement in cooking chamber  104  during, e.g., convection modes of oven appliance  100 . As shown in  FIG. 2 , a panel  140  protects fan  142 . Other configurations of convection fan  142  may be used as well. 
     Referring now to  FIG. 1 , oven appliance  100  includes a user interface  128  having a display  130  positioned on an interface panel  132  and having a variety of controls  134 . Interface  128  allows the user to select various options for the operation of oven  100  including, e.g., temperature, time, and/or various cooking and cleaning cycles. Operation of oven appliance  100  can be regulated by a controller  154  that is operatively coupled, i.e., in communication with, user interface  128 , heating elements  124 ,  126 , door lock  160 , and/or other components of oven  100 . For example, in response to user manipulation of the user interface  128 , controller  154  can operate the heating element(s). The controller can receive measurements from a temperature sensor  150  placed in cooking chamber  104  and, e.g., provide a temperature indication to the user with display  130 . Alternatively, controller  154  can be enabled with wireless communication components (e.g., “Wi-Fi”) to provide such temperature indication to the user through another wireless communication enabled device such as, e.g., a cellular phone, tablet computer, or the like. Other forms of communication may be included as well including e.g., a wired connection. Controller  154  can also be provided with other features as will be further described herein. 
     Controller  154  may include a memory and one or more processing devices such as microprocessors, CPUs, or the like, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with operation of oven appliance  100 . The memory may represent random access memory such as DRAM or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor. 
     Controller  154  may be positioned in a variety of locations throughout oven appliance  100 . In the illustrated embodiment, controller  154  is located next to user interface  128  within interface panel  132 . In other embodiments, controller  154  may be located under or over user interface  128  or otherwise within interface panel  132 , or controller  154  may be located at any other appropriate location with respect to oven appliance  100 . In the embodiment shown in  FIG. 1 , input/output (“I/O”) signals are routed between controller  154  and various operational components of oven appliance  100  such as heating elements  124 ,  126 , controls  134 , display  130 , door lock  160 , temperature sensor  150 , alarms, and/or other components as may be provided. In one embodiment, the user interface  128  may represent a general purpose I/O (“GPIO”) device or functional block. 
     Although shown with touch type controls  134 , it should be understood that controls  134  and the configuration of oven appliance  100  shown in  FIG. 1  is provided by way of example only. More specifically, user interface  128  may include various input components, such as one or more of a variety of electrical, mechanical, or electro-mechanical input devices including rotary dials, push buttons, and touch pads. The user interface  128  may include other display components, such as a digital or analog display device designed to provide operational feedback to a user. User interface  128  may be in communication with controller  154  via one or more signal lines or shared communication busses. 
     While oven  100  is shown as a wall oven, the present invention could also be used with other cooking appliances such as, e.g., a stand-alone oven, an oven with a stove-top, or other configurations of such ovens. 
     Referring now to  FIGS. 3 and 4 , an exemplary embodiment of oven appliance  100  is shown with a vent  156  in top wall  112 . Vent  156  allows fumes and gases generated during cooking to exhaust from cooking chamber  104 . Oven appliance  100  also includes a damper  158  in operative communication with controller  154 . Damper  158  is positioned such that, when controller  154  selectively operates damper  158 , damper  158  opens vent  156  as shown in  FIG. 3  or closes vent  156  as shown in  FIG. 4 . As illustrated in  FIGS. 3 and 4 , vent  156  may be configured as an opening in top wall  112 ; in alternative embodiments, more than one vent may be used and each vent may have an associated damper. Alternatively, one damper may be configured to close more than one vent. In still other embodiments, the one or more vents may be positioned at other locations in cooking chamber  104 . 
     As illustrated, temperature sensor  150  may be located adjacent top wall  112 . In alternative embodiments, temperature sensor  150  may be positioned in another location within cooking chamber  104 . In still other embodiments, oven appliance  100  may include more than one temperature sensor. Temperature sensor  150  may be a resistive temperature device (RTD) or any other suitable sensor. 
     In addition to temperature sensor  150 , oven appliance  100  may include a gas sensor  152 . Gas sensor  152  measures the level of a gas or several gases, such as CO, CO 2 , or the like, in cooking chamber  104 . In certain embodiments, gas sensor  152  is positioned in cooking chamber  104 , as shown in  FIGS. 3 and 4 . In other embodiments, gas sensor  152  may be positioned outside cooking chamber  104 , as shown in  FIG. 1 . Gas sensor  152  may be positioned in other locations as well, and certain embodiments may utilize more than one gas sensor positioned at various locations of oven appliance  100 . Gas sensor  152  may be a metal oxide semiconductor (MOS) sensor array or any other suitable sensor. 
     During the operation of oven appliance  100 , food items placed in cooking chamber  104  for cooking or food items that have fallen onto bottom wall  114  of cooking chamber  104  may burn or overcook, or cooking chamber  104  may become overheated, which could lead to a fire and/or smoke in cooking chamber  104 . Thus, oven appliance  100  may include features for detecting and containing and/or extinguishing fire and smoke within cooking chamber  104 . 
     For example, temperature sensor  150  may be in communication with controller  154 , and temperature values detected by temperature sensor  150  may be used by controller  154  to determine the rate of temperature change ΔT in cooking chamber  104 . If the rate of temperature change ΔT reaches at least a reference rate of temperature change ΔT ref , controller  154  may thereby detect a fire or other potentially harmful thermal event in cooking chamber  104  and implement measures to contain and/or extinguish the fire and protect a user of the oven appliance from the thermal event, as further described below. In other embodiments, controller  154  may compare a current temperature T measured by temperature sensor  150  to a threshold temperature T thr  to determine if there is a fire or other potentially harmful thermal event within cooking chamber  104 . That is, if the current temperature T reaches at least the threshold temperature T thr , controller  154  may thereby detect a fire or other thermal event in cooking chamber  104  and implement measures to contain and/or extinguish the fire and protect a user of the oven appliance from the thermal event. The reference rate of temperature change ΔT ref  and the threshold temperature T thr  may be stored in controller  154  or any other suitable device. 
     As a further example, gas sensor  152  may be in communication with controller  154 , and gas levels detected by gas sensor  152  may be used by controller  154  to monitor cooking chamber  104 . If the current gas level reaches at least a baseline gas level, controller  154  may thereby determine that a fire or other potentially harmful event within cooking chamber  104 . Controller  154  may then implement measures to contain and/or extinguish the fire and protect a user of the oven appliance from the event, as further described below. The baseline gas level may be the gas level determined when oven appliance  100  is first assembled or installed, and in certain embodiments, the baseline gas level may be determined after, e.g., each self-cleaning operation of oven appliance  100 . The baseline gas level may be stored in controller  154  or any other suitable device. 
       FIG. 5  illustrates one exemplary method  200  for operating oven appliance  100 . The exemplary method includes step  202  of monitoring the rate of temperature change ΔT in cooking chamber  104  and measuring the current gas level. At step  204 , the rate of temperature change ΔT is compared to the reference rate of temperature change ΔT ref . If the rate of temperature change ΔT has not reached at least the reference rate of temperature change ΔT ref , the method proceeds to step  206 , where the current gas level is compared to the baseline gas level. If the current gas level has not reached at least the baseline gas level, the method returns to step  202 . However, if at step  204  the rate of temperature change ΔT has reached at least the reference rate of temperature change ΔT ref , or if at step  206  the current gas level has reached at least the baseline gas level, the method proceeds to step  208 , implementing measures to contain and/or extinguish the fire and protect the user of the oven appliance. The order of steps  204  and  206  can be changed or even operated simultaneously. 
     At step  208 , a warning is provided to a user of oven appliance  100  that there is a fire or other potentially harmful event, such as, e.g., very high temperatures or smoke, in cooking chamber  104 . The warning may be any audible and/or visual signal that indicates to the user that a fire or other potentially harmful event has been detected in cooking chamber  104 . By way of example, the warning may be a notification displayed on user interface  128 , an LED light, a buzzer, and/or any other appropriate visual and/or audible signal. 
     At step  210 , door lock  160  of oven door  108  is engaged to lock the oven door. Locking door  108  prevents the user from accessing cooking chamber  104  and being injured by, e.g., flames or smoke. At step  212 , damper  158  is operated to close vent  156 . Closing vent  156  reduces the oxygen available to fuel a fire within cooking chamber  104 , which could help extinguish a fire within cooking chamber  104 . Closing vent  156  may also help contain any smoke within cooking chamber  104 . Similarly, convection fan  142  could be deactivated to diminish air movement within cooking chamber  104 . Further, at step  214  of method  200 , heating elements  124 ,  126  are disconnected from energy source  162  to prevent the addition of heat to cooking chamber  104  through heating elements  124 ,  126 . 
     Method  200  also includes step  216  of alerting emergency services to a possible fire. In certain embodiments, controller  154  may alert emergency services to a possible fire in oven appliance  100  through the wireless or wired communication connection described above. In alternative embodiments, step  216  may include providing an audible and/or visible instruction to a user, e.g., through user interface  128 , to alert emergency services. 
     As described above, in alternative embodiments, oven appliance  100  may include more than one vent and damper, and each vent may be closed by a damper at step  212 . Additionally, oven appliance  100  may include a convection heating element that also is disconnected from its energy source at step  214 . Other configurations of oven appliance  100  may also be used, and method  200  may include steps to contain a fire and/or smoke within oven appliance  100 , or to protect a user of the oven appliance, based on other configurations of oven appliance  100 . 
       FIG. 6  illustrates another exemplary method  300  for operating oven appliance  100 . The exemplary method includes step  302  of monitoring the temperature T in cooking chamber  104  and measuring the current gas level. At step  304 , the temperature T is compared to a threshold temperature T thr . If the temperature T has not reached at least the threshold temperature T thr , the method proceeds to step  306 , where the current gas level is compared to the baseline gas level. If the current gas level has not reached at least the baseline gas level, the method returns to step  302 . However, if at step  304  the temperature T within cooking chamber  104  has reached at least the threshold temperature T thr , or if at step  306  the current gas level has reached at least the baseline gas level, the method proceeds to step  308 , implementing measures to contain and/or extinguish the fire and protect the user of the oven appliance. Also, it is noted the order of steps  304  and  306  can be changed or even operated simultaneously. 
     At step  308 , a warning is provided to a user of oven appliance  100  that there is a fire or other potentially harmful event, such as, e.g., very high temperatures or smoke, in cooking chamber  104 . As described, the warning may be any audible and/or visual signal, such as a notification displayed on user interface  128 , an LED light, and/or a buzzer, that indicates to the user that a fire or other potentially harmful event has been detected in cooking chamber  104 . At step  310 , door lock  160  of oven door  108  is engaged to lock the oven door and prevent the user from accessing cooking chamber  104 . At step  312 , damper  158  is operated to close vent  156 . As described, convection fan  142  also could be deactivated to diminish air movement within cooking chamber  104 . Further, at step  314 , heating elements  124 ,  126  are disconnected from energy source  162  to prevent the addition of heat to cooking chamber  104  through heating elements  124 ,  126 . At step  316 , emergency services are alerted to a possible fire through, e.g., the wireless or wired communication connection of oven appliance  100 , or an audible and/or visible instruction is provided to a user, e.g., through user interface  128 , to alert emergency services. 
     As described above, in alternative embodiments, oven appliance  100  may include more than one vent and damper, and each vent may be closed by a damper at step  312 . Additionally, oven appliance  100  may include a convection heating element that also is disconnected from its energy source at step  314 . Other configurations of oven appliance  100  may also be used, and method  300  may include steps to contain a fire and/or smoke within oven appliance  100 , or to protect a user of the oven appliance, based on other configurations of oven appliance  100 . For example, a combination of the embodiments of  FIGS. 5 and 6  may be used that includes both T thr  and ΔT ref . 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.