Abstract:
A gas range has a cook top and a gas burner assembly. The gas burner assembly includes a burner body positioned in the cook top and connected to a source of gas. The burner body has at least one substantially enclosed chamber. The chamber has an inner wall with at least one port, and an outer wall with at least one port. At least one gas conduit with a substantially round entry for receiving a gas flow, a throated region, and a non-round exit in flow communication with the at least one chamber.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates generally to an apparatus for gas burners, and, more particularly, an apparatus for improved flow characteristics for gas surface burners used in a gas-cooking product. 
         [0002]    Atmospheric gas burners are commonly used as surface units in household gas cooking appliances. A significant factor in the performance of gas burners is their ability to withstand airflow disturbances from the surroundings, such as room drafts, rapid movement of cabinet doors, and oven door manipulation. Manipulation of the oven door is particularly troublesome because rapid openings and closings of the oven door often produce respective under-pressure and over-pressure conditions under the cook top. 
         [0003]    These under-pressure and over-pressure conditions cause related pressure variations in the gas entering the burner chamber. Gas refers to any gas or fuel air mixture. The pressure variations can translate into flow disturbances at the burner ports causing flame extinction. 
         [0004]    Gas surface burners used in cooking products typically include a burner body including a plurality of burner ports through which a gas is distributed, and a burner cap positioned over the burner body. Almost all designs include an internal chamber of increased gas volume near the burner ports. This is important where gas flow may change over time. Providing equal flame characteristics from one port to the next is critical to prevent hot spots or uneven heating of the cooking vessels. Variations in the size of the burner port and the distance of the burner port from the venturi can also affect the flame characteristics. Adverse changes in the flame characteristics are detrimental to various performance characteristics such as the inability to support flames at certain ports particularly at very low input rates. 
         [0005]    In these burners there are a number of port rings for the combustion of the gas. A typical multi-ring burner would include a doughnut shaped outer burner and a single inner burner. The outer burner would have a ring of ports on the outside and inside of the burner. This would create a triple ring burner. However, these burners, while uniform in applying heat the cooking vessel, are only efficient for large cooking vessels where the diameter of the vessel is larger than the burner. This is because there are several main factors influencing the minimum size of a triple ring burner. First, the inner burner must be sized to accommodate a stability chamber as discussed above. Second, the outer burner must be offset from the inner burner, further, the width of the outer ring is determined by the size of the venturi supplying gas to the chambers of the outer burner. Thus the minimum diameter of the outer ring=diameter of the inner burner+2×offset from inner burner to outer burner+2×width of the outer burner. Thus, as there is a finite distance to be maintained between the inner and outer burners and a finite size is required for the inner burner, there is a need to reduce the width of the outer burner to decrease the size of the burner assembly. 
       SUMMARY OF THE INVENTION 
       [0006]    As described herein, embodiments of the invention overcome one or more of the above or other disadvantages known in the art. 
         [0007]    In one aspect, a gas range has a cook top and a gas burner assembly. The gas burner assembly includes a burner body positioned in the cook top and connected to a source of gas. The burner body has at least one substantially enclosed chamber. The chamber has an inner wall with at least one port, and an outer wall with at least one port. At least one gas conduit with a substantially round entry for receiving a gas flow, a throated region, and a non-round exit in flow communication with the at least one chamber. 
         [0008]    In another aspect, a gas burner assembly is connected to a source of gas. The gas burner assembly has a burner body. The burner body comprises at least one substantially enclosed chamber. The chamber has an inner wall with at least one port, and an outer wall with at least one port. At least one venturi has an input for receiving a gas flow, a throated region, and a non-round exit in flow communication with the at least one chamber. 
         [0009]    In yet another aspect, a gas range has a cook top; and a gas burner assembly. The gas burner assembly includes a burner body positioned in the cook top and connected to a source of gas. The burner body comprises at least one chamber and at least one venturi. The chamber has an inner wall with at least one port, and an outer wall with at least one port. The at least one venturi has an input for receiving a variable gas flow, a throated region and an elliptical exit in flow communication with the at least one chamber. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The following figures illustrate examples of embodiments of the invention. The figures are described in detail below. 
           [0011]      FIG. 1  is a perspective view of a gas range according to an embodiment of the invention. 
           [0012]      FIG. 2  is a perspective view of a burner assembly of the range of  FIG. 1  according to an embodiment of the invention. 
           [0013]      FIG. 3  is a perspective view of a burner body of the burner assembly of  FIG. 2  according to an embodiment of the invention. 
           [0014]      FIG. 4  is a top view of a burner body of the burner assembly of  FIG. 2  according to an embodiment of the invention. 
           [0015]      FIG. 5  is a cutaway view of the burner body of  FIG. 3  along centerline  5 - 5 . 
           [0016]      FIG. 6  is a perspective view of multi-ring burner assembly incorporating a burner assembly of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    While the methods and apparatus are herein described in the context of a gas-fired cook top, as set forth more fully below, it is contemplated that the herein described method and apparatus may find utility in other applications, including, but not limited to, gas heater devices, gas ovens, gas kilns, gas-fired meat smoker devices, and gas barbecues. In addition, the principles and teachings set forth herein may find equal applicability to combustion burners for a variety of combustible fuels. The description herein below is therefore set forth only by way of illustration rather than limitation, and is not intended to limit the practice of the herein described methods and apparatus. 
         [0018]    Typically, for a burner chamber, flow distribution is governed by individual port areas. The larger ports exhibit higher flow rates than smaller ports. Thus, port sizing, a static attribute of a burner, primarily determines this flow characteristic. This defines the distribution of flow rates across the burner ports. In some cases, it is desired that the flow characteristics be “dynamic” or variable. One such instance would be in a burner where an interior region of ports are altered during high flow and unaltered during low flow conditions. For example, the inside ports are optimized for a particular flow and therefore produce poor and undesirable operational conditions when a flow other than the optimized flow conditions are experienced. Particularly, the ports require a minimum flow rate to prevent premature extinguishing of the cooking flame, however, due to oxygen requirements for proper burning, also exhibit poor performance during high flow conditions. 
         [0019]      FIG. 1  illustrates an exemplary freestanding gas range  100  in which the herein described methods and apparatus may be practiced. Range  100  includes an outer body or cabinet  112  that incorporates a generally rectangular cook top  114 . An oven, not shown in detail, is positioned below cook top  114  and has a front-opening access door  116 . A range backsplash  118  extends upward of a rear edge  120  of cook top  114  and contains various control selectors (not shown) for selecting operative features of heating elements for cook top  114  and the oven. It is contemplated that the herein described apparatus is applicable, not only to cook tops which form the upper portion of a range, such as range  100 , but to other forms of cook tops as well, such as, but not limited to, built in cook tops that are mounted to a kitchen counter. Therefore, gas range  100  is provided by way of illustration rather than limitation, and accordingly there is no intention to limit application of the herein described methods and apparatus to any particular appliance or cook top, such as range  100  or cook top  114 . 
         [0020]    Cook top  114  includes four gas fueled burner assemblies  200  which are positioned in spaced apart pairs positioned adjacent each side of cook top  114 . Each pair of burner assemblies  200  is surrounded by a recessed area  124  of cook top  114 . Recessed areas  124  are positioned below an upper surface  126  of cook top  114  and serve to catch any spills from cooking utensils (not shown in  FIG. 1 ) being used with cook top  114 . Each burner assembly  200  extends upwardly through an opening in recessed areas  124 , and a grate  128  is positioned over each burner  200 . Each grate  128  is adapted to provide the desired support of cooking vessels and utensils over burner assemblies  200  for cooking of meal preparations placed therein. 
         [0021]      FIG. 2  is a perspective view of an exemplary burner assembly  200  that can be used with gas range  100  (shown in  FIG. 1 ). Burner assembly  200  includes a burner cap  202  and a burner body  206 . A main gas conduit  208  has an orifice  212  and is open to an interior chamber or chambers of burner body  206  and defines a passage which extends axially through the base of burner body  206  to provide a gas or a fuel/air mixture to flow into burner assembly  200 . As used herein, the term “gas” refers to a combustible gas or gaseous fuel-air mixture. 
         [0022]    Burner assembly  200  is mounted on a support surface, such as cook top  114 , of a gas-cooking appliance such as a range or a cook top  100  (see  FIG. 1 ). A cap  202  is disposed over the top of burner body  206 . Gas enters burner body  206  at orifice  212  and traverses gas conduit  208  before entering the chambers of burner body  206 . Burner assembly  200  also includes at least one igniter (not shown) extending through an opening in burner body  206 . While one type of burner is described and illustrated, the herein described methods and apparatus are applicable to other types of burners, such as stamped aluminum burners and separately mounted orifice burners. 
         [0023]    Referring to  FIG. 6  a multi-ring burner assembly is shown. The multi-ring burner assembly has an inner burner assembly  300  and an outer burner assembly  200 . Inner burner assembly has a single ring of ports and burner cap  302 . Outer burner assembly  200  has two rings of ports. One ring of ports faces to the outside, the second ring of ports (hidden by cap  202 ) faces to the inside, or toward the inner burner assembly  300 . Gas conduit  208  provide a supply of gas to the outer burner body  206 . 
         [0024]    Now referring to  FIGS. 3 and 4 ,  FIG. 3  is a perspective view of a burner body  206 .  FIG. 4  is a top view of burner body  206  that can be used with gas range  100  (shown in  FIG. 1 ). Burner body  206  includes at least one conduit orifice  212  where a gas is introduced. For each orifice  212  the gas travels up gas conduit  208  to an opening  210 . Each opening  210  is in flow communication with at least one chamber or set of chambers  220 ,  240  and  260 . Chambers  240  and  260  are on opposite sides of opening  210  and will be described as separate chambers even though the chambers are not separated by a physical obstruction and each chamber experiences similar pressure and flow of gas from opening  210 . 
         [0025]    Gas is supplied to ports  222  via chamber  220 . Gas is supplied to ports  262  and  264  via chamber  260 . Gas is supplied to ports  242  via chamber  240 . Annular chamber  220  is defined by an outer wall  221 , an inner wall  223 , a lower surface of the burner body  206 , and cap  202 . A plurality of primary burner ports  222  are disposed in outer wall  221 . Primary burner ports  222  are typically, although not necessarily, evenly spaced about outer wall  221 . Inner wall  223  forms an isolation wall between chamber  220  and chamber  240 . Chamber  240  is further defined by a wall  241 . A plurality of burner ports  242  are disposed in wall  241 . As used herein, the term “port” refers to an aperture of any shape from which a flame may be supported. 
         [0026]      FIG. 5  is a cutaway view of  FIG. 3 . A gas conduit  208  typically has a round orifice  212  where gas enters. A single jet  290  is used for directing a fuel into orifice  212 . The jet  290  is configured smaller then orifice  212  so atmospheric may enter between the jet  290  and the wall  213  around orifice  212 . The velocity of the fuel exiting the jet  290  at orifice  302  draws atmospheric air into gas conduit  208 . The fuel and atmospheric air compress and mix while traveling through a necked region  211  of the gas conduit  208 . The necked region has a maximum cross section at the orifice  212  and a minimum cross-section where transition region  209  begins. For optimum performance a round cross-sectional orifice  212  is used. However, under some circumstances, a uniformly round opening  210  is not desirable. 
         [0027]    A uniformly round opening is not desirable where the distance between the inner ring of ports  242 ,  262  and outer ring of ports  222  and  264  is less than the necessary diameter of the opening  210 . The size of opening  210  is determined by the flow rate of gas during maximum output of the burner. In these conditions it may be necessary for opening  210  to have a diameter greater then the distance between the inner and outer wall. 
         [0028]    For example, there are situations where inadequate space is available for an opening  210  to have a symmetrically round cross section. Particularly, a finite distance is needed between the venturi opening  210  and the ports  265  immediately radially adjacent to the opening  210 . If ports  265  are too close to opening  210  much higher pressures will be experienced at the ports. The higher pressure reduces flame stability and would create a hot spot under the cooking vessel. The individual size of each of the ports  256 , relative to ports further from the opening, may not be reduced either, because the reduced size ports would then not support flames at anything other than maximum gas input rates. 
         [0029]    Making the opening  210  non-round allows more space to put a baffle  270  (or wall) between the opening and the ports  265  without increasing the diameter of the burner. As shown in  FIGS. 3 and 4  the opening  210  is non-round and has an elliptical shape. However, any non-round shape may be used that is capable of supplying gas at the maximum flow rate. The baffle  270  redirects the flow along the baffle  270 , parallel with the ports  265 , rather than normally into it. This way, more uniform port loading is achieved without varying the relative size of each of the ports. Further, the elliptical shape of opening  210  reinforces the action of the baffle  270 , directing flow in a manner that reduces the need to vary ports sizes to gain uniform flame lengths between individual ports. 
         [0030]    The methods and apparatus described herein facilitate providing substantially uniform heat distribution at relatively low input rates in a smaller diameter burner assembly. 
         [0031]    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.