Abstract:
A gas burner assembly for a cooking appliance that includes a cooktop surface includes a gas burner assembly having a first gas burner including a first burner body. The first burner configured to be mounted on, and contact, the cooktop surface, and provide a cooking flame. The gas burner assembly also includes a second gas burner including a second burner body. The second burner configured to be mounted on, and contact, the cooktop surface. The second burner also configured to be concentric with the first burner and separated from the first burner by a distance at all points along the burners. The second burner body including at least one air passage defined therethrough that is configured to allow air to flow through the second burner and to the cooking flame.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to gas burners, and, more particularly, to methods and apparatus for gas burner assemblies including inner and outer burners. 
     For gas burners that are used as surface heating units in cooking appliances such as ranges and cooktops, having a high turndown ratio, which is a ratio of maximum output to minimum output, is desirable. For a given burner, the maximum output typically signifies the “power” or “speed” of the burner and the minimum output is related to the simmer capability of a burner. The maximum output is limited by system gas flow handling capabilities and safety considerations. The minimum output is limited by the ability of the burner to maintain a stable flame under transient pressure fluctuation conditions caused, for example, by air currents in the room, or sudden opening or closing of nearby cabinet doors or the oven door. 
     A vast majority of gas burners used in cooking applications are partially pre-mixed burners using both primary-air and secondary-air. Based on whether the primary-air is drawn from above the cooktop or below the cooktop, these burners are termed either top-breathers or bottom-breathers respectively. In bottom-breather burners, also referred to as sealed burners, there are no gaps around the burner to allow spills or air to get inside the cooktop. However, the sealed burners are sensitive to pressure fluctuations under the cooktop. 
     At least some known gas burner assemblies include an inner gas burner and an outer gas burner for collectively producing a plurality of rings of flame to heat a utensil supported thereon. Such gas burners are generally secured on a cooktop surface by screws, and it is difficult to clean the cooktop surface around and between the burners. The inner burner is surrounded by the outer burner, and secondary-air cannot flow through the outer flame ring to enter the inner flame ring, such that the maximum energy output of the inner burner is undesirably limited unless a gap is provided either through or under the other burner. This further increases the difficulty of cleaning the cooktop. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one aspect, a gas burner assembly is provided for a cooking appliance that includes a cooktop surface. The gas burner assembly includes a first gas burner including a first burner body. The first burner configured to be mounted on, and contact, the cooktop surface, and provide a cooking flame. The gas burner assembly also includes a second gas burner including a second burner body. The second burner configured to be mounted on, and contact, the cooktop surface and to be concentric with the first burner and separated from the first burner by a distance at all points along the burners. The second burner body including at least one air passage defined therethrough that is configured to allow air to flow through the second burner and to the cooking flame. 
     In another aspect, a cooking appliance is provided that includes a cooking panel having a cooktop surface and at least one gas burner assembly mounted on the cooking panel. The gas burner assembly including a first gas burner mounted on the cooktop surface and including a first burner body. The first gas burner configured to provide a cooking flame. The gas burner assembly also includes a second gas burner contacting the cooktop surface and surrounding the first burner. The second burner including a second burner body having at least one passage defined therethrough. The passage configured to allow air to flow through the second burner and to the cooking flame. At least one of the first burner and the second burner configured to be removed from the cooktop without removal of the other of the first burner and the second burner. 
     In another aspect, a method is provided for assembling a cooking appliance. The method includes providing a cooking panel having a cooktop surface and mounting a first gas burner on, and in contact with, the cooktop surface. The first burner including a first burner body and configured to provide a cooking flame. The method further including mounting a second gas burner on, and in contact with, the cooktop surface such that the second gas burner surrounds the first burner and is separated from the first burner by a distance at all points along the burners. The second burner including a second burner body. The method further including defining at least one passage through the second burner body. The passage configured to allow air to flow through the second burner and to the cooking flame. 
     In another aspect, a cooking apparatus is provide that includes a cooktop surface and at least one gas burner assembly mounted on the cooktop surface. The gas burner assembly further including a gas simmer burner mounted on, and in contact with, the cooktop surface. The simmer burner includes a simmer burner body and it is configured to provide a cooking flame. The gas burner assembly further includes a second gas burner mounted on, and in contact with, the cooktop surface and concentric with the simmer burner. The second burner comprising a second burner body having at least one passage defined therethrough. The passage configured to allow air to flow through the second burner and to the cooking flame. Wherein the second burner configured to be removed from the cooktop surface without removal of the first burner. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an embodiment of an exemplary free-standing gas range; 
         FIG. 2  is an exemplary burner assembly applicable to the gas range shown in  FIG. 1 ; 
         FIG. 3  is an exploded view of the burner assembly shown in  FIG. 2 ; and 
         FIG. 4  is a cross sectional view of the burner assembly shown in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates an exemplary free-standing gas range  10  in which the herein described apparatus and methods may be practiced. Range  10  includes 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 from 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. 
     Cooktop  14  includes four gas fueled burner assemblies  22  which are positioned in spaced apart pairs positioned adjacent each side of cooktop  14 . Each burner assembly  22  extends upward through an opening in cooktop  14 , and a grate  28  is positioned over each burner assembly  22 . Each grate  28  includes a horizontally extending support structure thereon for supporting cooking vessels. 
     Cooktop  14  also includes control devices, such as, knobs  32 ,  34 ,  36 , and  38  that are manipulated by a user to adjust the setting of a corresponding gas valve (not shown) to control the amount of heat output from the corresponding one of burner assemblies  22 . For example, rotating knob  32  in one direction switches the valve from off to the full on position. Continued rotation gradually moves the valve from the full open position to the minimum setting position. Accordingly, the user may adjust the heat output of the corresponding burner to the desired level. 
     It is contemplated that the herein described apparatus and methods are 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, cooktops that are mounted to a kitchen counter. Therefore, range  10  is provided by way of illustration rather than limitation, and accordingly there is no intention to limit application of the herein described apparatus and methods to any particular appliance or cooktop, such as range  10  or cooktop  14 . It is also to be understood that there can be any other number of burner assemblies or any combination of burner assemblies and other type of cooking surfaces, such as, grills and hot plates, included in cooktop  14 . 
       FIG. 2  is an exemplary burner assembly  50  applicable to gas range  10  shown in  FIG. 1 , and  FIG. 3  is an exploded view of burner assembly  50  shown in  FIG. 2 . Burner assembly  50  is mounted on a cooktop surface  52  of a cooktop  54 , and includes a central simmer burner  60 , and an outer gas burner  62  concentric with simmer burner  60 . In the exemplary embodiment, cooktop  54  is fabricated from one of steel and glass, and cooktop surface  52  includes a first and a second mounting opening  64 ,  66  for mounting simmer burner  60  and outer burner  62  thereon, respectively. Alternatively, cooktop  54  is made of other suitable materials. 
     Simmer burner  60  includes a simmer burner body  68  having a simmer burner chamber  70  defined therein, a central cap  72  for covering simmer burner body  68 , a plurality of ports  74  defined on an outer circumferential surface  76  of simmer burner body  68 , and a venturi  78  extending downward from simmer burner body  68 . Central cap  72  is substantially circular in shape, and is removably mounted on simmer burner body  68  for enclosing simmer burner chamber  70  therein. Removal of cap  72  also enables an operator to clean simmer burner chamber  70 . Ports  74  are in flow communication with simmer burner chamber  70 , and are shown in the form of slots in  FIG. 3 . In alternative embodiments, ports  74  have shapes other than slots. Venturi  78  is in flow communication with simmer burner chamber  70 , and is inserted into mounting opening  64 . Venturi  78  includes a gas inlet  80  positioned beneath cooktop  54  for receiving gas from a gas supply (not shown) and channeling the gas into chamber  70 . 
     Outer gas burner  62  is separate from simmer burner  60  and surrounds simmer burner  60  therein. Outer burner  62  includes an outer burner body  82  having a ring-shaped outer burner chamber  84  defined therein, an outer cap  86  for covering outer burner body  82 , a first group of ports  88  and a second group of ports  90  defined thereon. A venturi  92  extends downward from outer burner body  82 . In alternative embodiments, at least one of burner bodies  82 ,  84  have a shape other than ring-shaped. 
     Outer cap  86  is substantially ring-shaped, and is removably mounted on outer burner body  82  for enclosing outer burner chamber  84  therein. In alternative embodiments, outer cap  86  is other than ring shaped. First group of ports  88  are located on an inner circumferential surface  94  of outer burner body  82 , and second group of ports  90  are located on an outer circumferential surface  96  of outer burner body  82 . Both first group of ports  88  and second group of ports  90  are in flow communication with outer burner chamber  84 , and are illustrated as slots in  FIG. 3 . However, in alternative embodiments, ports  88 ,  90  have other shapes. Venturi  92  is also in flow communication with outer burner chamber  84 , and is inserted into mounting opening  66 . Venturi  92  includes a gas inlet  98  positioned beneath cooktop  54  for receiving the gas from the gas supply and channeling the gas into chamber  84 . 
       FIG. 4  is a cross sectional view of burner assembly  50  shown in  FIG. 2 . In the exemplary embodiment, both simmer burner  60  and outer burner  62  are mounted on cooktop  54  without using screws. As such, simmer burner  60  and outer burner  62  are easily removed from cooktop by an operator&#39;s hands without using additional tools. This easy removal facilitates conveniently cleaning cooktop surface  52  beneath and around burners  60 ,  62 . In a further exemplary embodiment, simmer burner  60  and outer burner  62  are not fastened onto cooktop  54  to facilitate even easier removal of burners  60 ,  62  from cooktop  54 . In another embodiment, simmer burner  60  is fastened, or sealed, to cooktop  54  and outer burner  62  is not mounted to cooktop  54  with fasteners. 
     In the exemplary embodiment, simmer burner  60  is a sealed burner, and simmer burner body  68  includes a continuous and flat bottom surface  100  that contacts cooktop surface  52 . Surface  100  thus forms a substantially annulus seal surrounding mounting hole  64 . This seal restricts liquid and/or spillage collected on cooktop surface  52  from flowing therethrough and into an interior of cooktop  54  through mounting hole  64 . In alternative embodiments, simmer burner body  68  has other shapes and includes other structures known in the art to form a seal between the simmer burner  60  and cooktop surface  52 . 
     Outer burner  62  includes a bottom surface  102  and a plurality of passages  104  circumferentially defined on bottom surface  102 . Passages  104  are illustrated as slots in  FIG. 4 , and are positioned above cooktop surface  52 . In alternative embodiments, the number of passages  104  is varied, and passage  104  has other shapes and is defined through outer burner body  82  at other positions for allowing air flow therethrough. 
     The gas supply (not shown) includes a plurality of gas conduits (not shown), a first orifice  106  and a second orifice  108  coupled in flow communication with the gas conduits and positioned beneath cooktop surface  52 . Orifices  106 ,  108  face gas inlets  80 ,  98  of venturis  78 ,  92  and supply gas into burner chambers  70 ,  84 , respectively. In alternative embodiments, gas is fed to each burner chamber  70 ,  84  via multiple orifices. 
     In operation, simmer burner chamber  70  receives the primary-air from an underside of cooktop surface  52 . The primary-air beneath cooktop surface  52  mixes with the gas supplied via orifice  106  to form an air-gas mixture. The air-gas mixture flows through venturi  78  to simmer burner chamber  70 , and flows out from ports  74  defined on outer circumferential surface  76  of simmer burner body  68 . The air-gas mixture is ignited by an ignition source (not shown), such as a spark ignition electrode or a hot surface igniter, to generate an inner ring of flame  110 . 
     The primary-air beneath cooktop surface  52  also mixes with the gas supplied via orifice  106  to form an air-gas mixture. The air-gas mixture flows through venturi  92  to outer burner chamber  84 . The air-gas mixture also flows out from first and second group of ports  88 ,  90  defined on inner and outer circumferential surfaces  94 ,  96  of outer burner body  82 . The air-gas mixture exiting ports  88  is ignited to generate a middle ring of flame  112 , and the air-gas mixture exiting ports  90  is ignited to generate an outer ring of flame  114 . 
     Secondary-air above cooktop  54  flows towards outer flame ring  114  to complete combustion. The secondary-air above cooktop  54  also flows through passages  104  along direction A shown in  FIG. 4 , and then to inner and middle flame rings  110 ,  112 . The secondary-air flows below outer flame ring  114 , and into the interior of outer burner  62  to complete combustion of inner and middle flame rings  110 ,  112 . 
     In the exemplary embodiment, outer burner  62  has a maximum energy output larger than a maximum energy output of simmer burner  60 . In addition, both simmer burner  60  and outer burner  62  are operable simultaneously when burner assembly  50  is operated at levels above a simmer range. Alternatively, only one of simmer burner  60  and outer burner  62  is operated during a particular cooking event such as, for example, when burner assembly  50  is operated within the simmer range. Specifically, when knob  32  (shown in  FIG. 1 ) is moved to a position within the simmer range, outer burner  62  is de-energized, and simmer burner  60  is energized to a level indicated by a position of knob  32 . When knob  32  is turned from a low level to a high level, the energy output of simmer burner  60  increases to a higher rate, and outer burner  62  is ignited when knob  32  is turned to a level above the simmer range. When knob  32  is turned to an “off” position, both burners  60 ,  62  are de-energized. 
     By allowing the secondary-air to flow through the underside of the outer burner and to the central burner, the central burner is able to reach a much higher energy output. In addition, the central and outer burners are removably mounted on the cooktop surface, which facilitates cleaning the cooktop surface beneath and around the burners. 
     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.