Patent Publication Number: US-2006016445-A1

Title: Methods and apparatus for a gas range

Description:
BACKGROUND OF THE INVENTION  
      This invention relates generally to gas cooking appliances, and, more particularly, to a gas shutoff valve assembly for a cooking appliance.  
      Gas fired stoves, ovens, and ranges typically include one or more gas heating elements coupled to a main gas line to the appliance and providing fuel to the heating elements, sometimes referred to as burners. In a domestic range, a gas line is connected to a distribution manifold within the appliance to direct gas to a plurality of surface burner elements on a cooktop or to oven elements within an oven cavity. Operation of the burners and cooking elements is usually accomplished with burner control knobs mounted on either a front or back wall of the appliance. When a control knob is actuated, fuel is supplied to associated heating elements and an ignition module creates a spark to ignite the gas and produce a flame.  
      Some gas cooking appliances include a valve to prevent gas flow to the burners when actuated (sometimes referred to as a lockout condition), and thus the appliance can be rendered inoperable as desired. In some known gas cooking appliances, a self-clean feature is necessary to clean the gas cooking appliances without manual labor, which is apparently convenient for a user.  
      However, when a gas cooking appliance is operated in a self-clean mode, some international standards require a gas range to meet predetermined temperature limits. Specifically, because of the relatively large amount of heat that is generated during the self-clean mode, relatively large quantities of insulation are installed to insulate the oven cavity. Moreover, if the cooking appliance burners are operated during the self-clean mode, additional quantities of insulation are installed to meet the international standards.  
     BRIEF DESCRIPTION OF THE INVENTION  
      In one aspect, a gas cooking appliance is provided. The gas cooking appliance includes at least one gas surface burner element, a controller configured to receive a signal indicative of a self-clean mode, and a gas lockout valve assembly coupled in line with the surface burner element, wherein the gas lockout valve assembly is configured to close in response to receiving the self-clean signal such that gas flow to the surface burner element is stopped during the self-clean mode.  
      In another aspect, a gas range is provided. The gas range includes a cabinet, a plurality of gas surface burners coupled to the cabinet, a controller configured to receive a signal indicative of a self-clean mode, and a gas lockout valve assembly coupled between the plurality of gas surface burner elements and a gas line, the gas lockout valve assembly is configured to close in response to receiving the self-clean signal such that gas flow to the surface burner elements is stopped during the self-clean mode.  
      In a further aspect, a method for automatically shutting off a gas supply during a self-clean process of a gas cooking appliance is provided. The appliance includes a plurality of surface burner elements, a gas lockout valve assembly having a solenoid coupled to the surface burner elements, and a controller operatively coupled to the gas lockout valve assembly. The method includes inputting an instruction of a self-clean mode to the controller, transferring a signal of a self-clean mode from the controller to the gas lockout valve assembly, and shutting off the gas supply via the gas lockout valve assembly in response to receiving the self-clean signal from the controller. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  illustrates an exemplary free standing gas range.  
       FIG. 2  is a side elevational view of the range shown in  FIG. 1  partly broken away.  
       FIG. 3  is a cross sectional schematic view of an exemplary gas lockout valve assembly for the range shown in  FIGS. 1 and 2 .  
       FIG. 4  is a plan view of a control panel interface for the range shown in  FIGS. 1 and 2 .  
       FIG. 5  is a schematic block diagram of a control system for the range shown in  FIGS. 1 and 2 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       FIG. 1  illustrates a gas cooking appliance in the form of a free standing gas range  10  including an outer body or cabinet  12  that incorporates a generally rectangular cooktop  14 . An oven, not shown, is positioned below cooktop  14  and has a front-opening access door  16 . A range backsplash  18  extends upward of a rear edge  20  of cooktop  14  and contains various control selectors (not shown) for selecting operative features of heating elements for cooktop  14  and the oven. It is contemplated that the present invention is applicable, not only to cooktops which form the upper portion of a range, such as range  10 , but to other forms of cooktops as well, such as, but not limited to, free standing cooktops that are mounted to kitchen counters. Therefore, gas range  10  is provided by way of illustration rather than limitation, and accordingly there is no intention to limit application of the present invention to any particular appliance or cooktop, such as range  10  or cooktop  14 . In addition, it is contemplated that the present invention is applicable to duel fuel cooking appliances, e.g., a gas cooktop with an electric oven.  
      Cooktop  14  includes four gas fueled surface burners  22 ,  24 ,  26 ,  28  which are positioned in spaced apart pairs  22 ,  24  and  26 ,  28  positioned adjacent each side of cooktop  14 . Each pair of burners  22 ,  24  and  26 ,  28  is surrounded by a recessed area (not shown in  FIG. 1 ) respectively, of cooktop  14 . The recessed areas are positioned below an upper surface  29  of cooktop  14  and serve to catch any spills from cooking utensils being used with cooktop  14 . Each burner  22 ,  24 ,  26 ,  28  extends upwardly through an opening in cooktop  14 , and a grate assembly  30 ,  32  is positioned over each respective pair of burners,  22 ,  24  and  26 ,  28 . Each grate assembly  30 ,  32  includes a respective frame  34 ,  36 , and separate utensil supporting grates  38 ,  40 ,  42 ,  44  are positioned above the cooktop recessed areas and overlie respective burners  22 ,  24 ,  26 ,  28  respectively.  
      The construction and operation of the range heating elements, including cooktop gas burners  22 ,  24 ,  26 ,  28  are believed to be within the purview of those in the art without further discussion.  
       FIG. 2  illustrates range  10  mounted adjacent a kitchen wall  50 . Range  10  includes a front panel  52 , a rear wall  54 , laterally spaced side walls  56  and  58 , and backsplash  18 . Gas burners  22 ,  24 ,  26 , and  28  of cooktop  14  are connected by a gas line  62  to a manifold  64 . A plurality of burner knobs  65  are mounted on front panel  52  of range  10  in front of cooktop  14 . A gas appliance connector hose  70  is connected between a main gas line  68  and gas line manifold  64 , and a gas lockout valve assembly  66  is connected to or in line with gas line manifold  64  along appliance connector hose  70 . Gas lockout valve assembly  66  therefore regulates gas flow between main gas line  68  and gas manifold  64 . While lockout valve assembly  66  is illustrated coupled to appliance connector hose  70  between backsplash  18  and manifold  64 , it is contemplated that gas lockout assembly  66  may be located elsewhere in appliance  10 , including but not limited to, a location in the immediate vicinity of the main gas line connection to appliance  10 .  
      When lockout valve assembly  66  is in an open position, gas flow is channeled through appliance connector hose  70  to manifold  64  and to surface burners  22 ,  24 ,  26 , and  28  when the applicable control knob  65  is actuated. When lockout valve assembly  66  is in a closed position, gas flow is prevented from entering into gas manifold  64  from appliance connector hose  70 , thereby blocking gas flow to surface burners  22 ,  24 ,  26 , and  28  even though the applicable control knob  65  may be opened. Surface burners  22 ,  24 ,  26 , and  28  (as well as other heating elements connected to manifold  64 ) are thereby inoperative and gas flow is avoided.  
       FIG. 3  is a cross sectional schematic view of an exemplary embodiment of a gas lockout valve assembly  66  including a valve  80  adapted for connection to a gas line such as gas line  70  (shown in  FIG. 2 ). In one embodiment, gas lockout valve assembly  66  includes an electric motor  82  for actuating valve  80  to open or close a fluid path or passage  81  through valve  80  to supply or not supply gas to appliance gas manifold  64  (shown in  FIG. 2 ) and therefore to associated surface burner elements. In another embodiment, gas lockout valve assembly  66  includes a solenoid (not shown) for actuating valve  80  to open or close a fluid path or passage  81  through valve  80  to supply or not supply gas to appliance gas manifold  64  (shown in  FIG. 2 ) and therefore to associated surface burner elements  22 ,  24 ,  26 , and  28 . In the exemplary embodiment, valve  80  is a ½ inch NPT (Normal Pipe Thread) panel mount ball valve including an actuation shaft  84  rotatable about an axis  88  through the valve. In one embodiment, valve shaft  84  is operatively coupled to motor  82 , and more specifically to a motor output shaft  85  extending from a motor output gear  86  through a cam  90  that receives motor shaft  85  and valve shaft  84 . As motor  82  is energized, motor shaft  85  is rotated and causes valve shaft  84  to be rotated. As valve shaft  84  is rotated, a spherical valve element mechanism is displaced from or seated to valve seats within a flow path to control the flow of gas through valve  80 .  
      In another embodiment, valve shaft  84  is operatively coupled to a solenoid  83  such that energizing solenoid  83  causes valve  80  to open or close a fluid path or passage  81  through valve  80  to supply or not supply gas to appliance gas manifold  64  (shown in  FIG. 2 ) and therefore to associated surface burner elements. It is believed that such valve mechanisms are readily appreciated by those in the art without further explanation, and it is contemplated that other types of valves familiar to those in the art could likewise be employed without departing from the scope of the present invention.  
       FIG. 4  illustrates an exemplary input interface panel  130  that may be used with range  10  (shown in  FIGS. 1 and 2 ). Interface panel  130  includes a display  132  and a plurality of input selectors  134  in the form of touch sensitive buttons or keypads for accessing and selecting oven features. In alternative embodiments, other known input selectors are used in lieu of touch sensitive switches.  
      More specifically, input selectors  134  are divided into two groups  136 ,  138 . Group  136  includes a SURFACE LIGHT keypad  139 , a BAKE keypad  140 , a BROIL keypad  142 , an OVEN LIGHT keypad  144 , a CONVECTION BAKE keypad  146 , a CONVECTION ROAST keypad  148 , a CLEAN keypad  150 , a FAVORITE RECIPE keypad  152 , a MULTI-STAGE keypad  154 , a temperature up ( ) slew keypad  156  and a temperature down ( ) slew keypad  158 . Group  138  includes an hour up ( ) slew keypad  160  and an hour down ( ) slew keypad  162 , a minute up ( ) slew keypad  164  and a minute down ( ) slew keypad  166 , a START keypad  168 , a CLEAR/OFF keypad  170 , a LOCK keypad  172 , a COOK TIME keypad  174 , a DELAY START keypad  176 , a POWER LEVEL keypad  178 , a CLOCK keypad  180 , a KITCHEN TIMER keypad  182 , and a SURFACE WARMER keypad  184 .  
      By manipulating the appropriate input selector  134  in one of the control selector groups  136 ,  138 , the appropriate feature or function is activated by an appliance controller (not shown in  FIG. 4 ) and, for most of the features, an icon or indicator is displayed on display  132  to visually indicate selected appliance features and operating parameters, such as cooking time, and cooking temperature.  
       FIG. 5  is a block diagram of a control system  200  that may be used with range  10  (shown in  FIGS. 1 and 2 ). Control system  200  includes a controller  201  that includes a microprocessor  202  that is coupled to input interface  130  and to display  132 , and including a RAM memory  204  and a permanent memory  206 , such as a flash memory (FLASH), a programmable read only memory (PROM), or an erasable programmable read only memory (EPROM) as known in the art. The controller memory is used to store calibration constants, oven operating parameters, cooking routine, and recipe information that may be used to control the oven heating elements and execute user instructions.  
      Microprocessor  202  is operatively coupled to a plurality of electrical heating elements  208  (i.e., oven bake element, broil element, convection element, and cooktop surface heating units) for energization thereof through relays, triacs,  209  or other known mechanisms (not shown) for cycling electrical power to oven heating elements  208 . One or more temperature sensors  210  sense operating conditions of oven heating elements  208  and are coupled to an analog to digital converter (A/D converter)  212  to provide a feedback control signal to microprocessor  202 . It is contemplated also that gas heating elements may be employed for oven operation in alternative embodiments of the invention.  
      In the exemplary embodiment, gas lockout valve assembly  66  is coupled to gas heating elements such as burners  22 ,  24 ,  26 ,  28  (shown in  FIG. 1 ) for regulating a gas supply thereto as described above. Valve assembly  66  is operatively coupled to microprocessor  202  and is responsive thereto. When the gas lockout feature is selected through user manipulation of I/O interface  130 , microprocessor  202  transmits a signal to valve assembly  66  to either open or close valve assembly  66 . In one embodiment, when an operator depresses CLEAN keypad  150  to initiate the self-clean mode, microprocessor  202  energizes at least one of motor  82  or solenoid  83  to reposition valve  80  such that valve assembly  66  is repositioned to a closed position. When the gas lockout feature is deselected through user manipulation of I/O interface  130 , microprocessor  202  transmits a signal to valve assembly  66 . More specifically, microprocessor  202  energizes at least one of motor  82  and solenoid  83  to open valve  80  such that valve assembly  66  is repositioned to an open position.  
      In the exemplary embodiment, range  10  includes a plurality of switches  102 ,  104  that transmit a signal indicative of the operational position of gas lockout valve assembly  66 . More specifically, gas lockout valve assembly  66  is activated, a portion of valve  80 , such as for example cam  90  repositions at least one of switches  102 ,  104  from an open state to a close state such that an electrical signal is transmitted to microprocessor  202  indicative of an opened or closed state of valve  80 , and microprocessor  202  causes appropriate visual indicia via interface  130  and/or audible signals to alert a user of the gas lockout condition when the gas lockout feature is activated. By monitoring a state of switches  102 ,  104  fault conditions, such as motor failure or switch failure, can be detected and indicated to a user.  
      In operation, when there is a need for a self-clean of the gas range  10 , the operator initiates the self-clean mode by depressing an icon on visual indicia via interface  130 , and gas lockout valve assembly  66  will automatically shut off gas supply before the self-clean is initiated. More specifically, when an operator depresses CLEAN keypad  150  of input selectors  134 , an instruction of a self-clean mode is input to control system  200 , in an exemplary embodiment, to microprocessor  202 . After receiving the instruction of the self-clean mode, microprocessor  202  transmits a signal of a self-clean mode to gas lockout valve assembly  66 . Gas lockout valve assembly  66 , more specifically, valve  80  shuts off the gas supply in response to receiving the self-clean signal from microprocessor  202 . When valve  80  is completely closed, switch  102  will be actuated, and provide a feedback of the self-clean signal to microprocessor  202 . After receiving the feedback from switch  102  indicating the gas is in fact off, microprocessor  202  will provide instructions to initiate the self-clean mode. Thus surface burners  22 ,  24 ,  26 , and  28  cannot be used during the self-clean process. After the self-clean process is completed, microprocessor  202  will prompt a user via display  132  to unlock the gas range  10  such that valve assembly  66  can be opened and allow the gas supply again.  
      The methods and apparatus described herein facilitate reducing a quantity of heat that is generated from an oven cavity during a self-clean mode of operation. More specifically, when the oven described herein is operated in a self-clean mode, the gas valve is closed such that the gas surface burners are not operable in the self-clean mode. Accordingly, the methods and apparatus described herein facilitate reducing a heat output of the oven such that during the self-clean mode, additional insulation is not used to insulate the oven cavity, thus lowering construction costs.  
      While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.