Abstract:
The present inventions provide, among other things, tapered burner tubes having raised gas ports and a smooth interior surface free from obstructions. Venturi members and air shutters may also be included.

Description:
FIELD OF THE INVENTION 
       [0001]    The present inventions relate to burners for use in gas appliances such as gas grills. More particularly, the present inventions relate to tapered burner tubes having raised gas ports and a smooth interior surface. 
       BACKGROUND OF THE INVENTION 
       [0002]    Burners and burner tube assemblies, including those used in gas grills, are well known. Most conventional gas grills include burner tube assemblies that provide a plurality of burner tubes, gas valves and a gas distribution manifold. Each burner tube has a length defined by an open end and a closed end and a plurality of outlet ports along the length of the burner tube between the open and closed ends. The open end of the burner tube typically includes an air shutter that it used to adjust the gas and combustion air mixture, as well as a venturi region to increase the velocity of the gas/air mixture in the tube. The open end is connected to the neck of a gas control valve, which is in fluid communication with a gas distribution manifold, which is in fluid communication with a gas source such as a tank. 
         [0003]    For cost, manufacturing and other reasons, many conventional burner tubes are constructed from hollow welded circular tubing, often made from stainless steel. A venturi region is typically formed by pinching the tube near the open end of the burner tube. The venturi increases the velocity of the fuel/air mixture from the gas nozzle into the burner tube. An air shutter is also typically provided on the open end of the burner tube to adjust the fuel to air mixture. 
         [0004]    Also for cost and other manufacturing reasons, the gas ports of typical burner tubes are punched into the tube from the outside of the tube to the inside, either on the top or sides of the tube. This results in burrs or other obstructions on the inside of the burner tube that can disrupt the flow of the fuel/air mixture and provide poor flame quality. Moreover, the flames produced by those burner tubes typically sit directly on the surface of the burner tube itself. This increases the temperature of the burner tube and can result in increased corrosion and clogging of the ports as well as a shorter life of the burner tube. In addition, many known burner tubes have a substantially uniform cross-section along their length that can result in uneven or inconsistent fuel pressure along the length of the tube. This can also negatively affect flame quality. 
         [0005]    Thus, there is a need for improved burner tubes that provide improved flame characteristics and quality and which increase the life of the burner tube. There is also a need for burner tubes that enable smooth fuel/air flow throughout their length, as well as consistent pressure throughout the length of the burner tube. The present inventions solve the above described and other deficiencies and provide new features and advantages over known burner tubes. 
       SUMMARY OF THE INVENTION 
       [0006]    In general, the burner tubes of the present inventions are part of burner assemblies used with gas grills. The present inventions preserve the advantages of known burner tubes and provide new features and advantages, some of which are described below and others which will be apparent to those of ordinary skill in the art. 
         [0007]    In accordance with the present inventions, a burner for use in a gas grill is provided. It includes a tapered burner tube having an open end, a closed end and a substantially hollow and smooth interior which is free of burrs or other obstructions. The burner tube includes an upper surface, the upper surface including a plurality of gas ports having a height projecting above the upper surface of the tube and an opening at the top of the height, the opening having a diameter. A venturi member at the open end of the burner tube is also provided, the venturi member including two opposing, generally v-shaped flanges to restrict the interior of the open end of the burner tube. 
         [0008]    In a preferred embodiment, the gas port height is between approximately 0.020 and 0.62 inches and the opening diameter is between approximately 0.075 and 0.110 inches. More specifically and preferred, the gas port height is approximately 0.060 inches and the port diameter is approximately 0.093 inches. In addition and as preferred, the ratio of gas port height to opening diameter is between approximately 0.640 and 0.650, and preferably greater than 0.5. 
         [0009]    The present inventions also provide a burner assembly for a gas grill, the assembly having a burner tube, the burner tube including an open end and a closed end and a length between the open end and the closed end and an upper surface. The burner tube further includes a cross-sectional shape defining a hollow interior, wherein the cross-sectional shape is tapered and defines an area that decreases from the open end to the closed end. Also included is a plurality of raised gas ports along the length of the upper surface of the burner tube, the gas ports having a height projecting above the upper surface of the burner tube and an opening at the top of the height of the gas port, the opening having a diameter. In addition, the hollow interior of the burner tube is free from burrs or other obstructions. 
         [0010]    In a preferred embodiment the ratio of the height of the gas port in inches to the diameter of the gas port opening in inches is between approximately 0.625 and 0.670. It is also preferred that the height of the port is between 0.020 inches and 0.062 inches and the opening diameter is between 0.075 inches and 0.110 inches. More specifically and preferred, the height of the port is approximately 0.060 inches and the opening diameter is approximately 0.093 inches. 
         [0011]    Also provided by the present inventions is a burner assembly for a gas grill, the grill having a fuel source, a gas distribution manifold in fluid communication with the fuel source and control valves in fluid communication with the gas distribution manifold. A burner tube having an open end, a closed end and a substantially hollow interior, the burner tube gradually tapering from the open end to the closed end, is also provided. A plurality of raised gas ports Is included on an upper surface of the burner tube, the gas ports projecting above the upper surface of the burner tube having a height front the upper surface and an opening at the top of the height, the opening having an area. The interior of the burner tube is free from burrs or obstructions to permit the smooth flow of fluid along the length of the interior of the burner tube and wherein a flame sits on top of the openings of the gas ports and above the upper surface of the burner tube. 
         [0012]    In a preferred embodiment, the height of the gas ports is between 0.020 and 0.062 inches and the area of the port opening is between 0.006 and 0.008 square inches. In the particular preferred embodiment, the height of the gas port is approximately 0.060 inches and the area of the opening is approximately 0.007 square inches. A venturi member and an air shutter may also be provided. 
         [0013]    Alternatively, the port opening may be generally circular and have a diameter. In a preferred embodiment, the height of the gas port is between 0.020 and 0.062 inches and the diameter of the opening is between 0.075 and 0.110 inches. In the preferred embodiment, the height of the gas port is approximately 0.060 inches and the diameter of the opening is approximately 0.093 inches. 
         [0014]    Accordingly, it is an object of the present inventions to provide a safe, reliable burner tube that efficiently operates over a wide range of gases and mixtures and a wide range of input pressures. 
         [0015]    It is another object of the present inventions to provide a tapered burner tube that enables consistent pressure along the length of the tube. 
         [0016]    Still another object of the present inventions is to provide a burner tube having a smooth interior surface that enables laminar fluid flow along the length of the interior of the tube. 
         [0017]    Yet another object of the present inventions is to provide raised gas ports that enable better flame characteristics and help maintain a cooler burner tube temperature. 
         [0018]    Still yet another object of the present inventions is to manufacture the burner tube by forming the raised gas ports from what will be the inside of the burner tube to what will be the outside of the burner tube so that the interior of the burner tube is smooth and tree from burrs of other obstructions. 
         [0019]    An additional object of the present inventions is to reduce corrosion and gas port clogging of the burner tube. 
         [0020]    Still an additional object of the present inventions is to provide larger gas port openings that provide improved flame characteristics and are less susceptible to corrosion, yet are not prone to backflash or flame pull back into the burner tube when in use. 
         [0021]    Yet an additional objection of the present inventions is to enable greater material selection as well as manufacturing and cost advantages. 
         [0022]    A further object of the present inventions is to provide a burner tube having improved flame characteristics and less material degradation. 
         [0023]    Still a further object of the present inventions is to provide an improved venturi member and including one that functions with a burner tube having a non-circular cross-section. 
         [0024]    Still yet another object of the present inventions is to provide an improved burner tube having a tapered cross-section, a venturi member and an air shutter that cooperates with the open end of the burner tube to adjust the fuel/air mixture. 
       Inventor&#39;S Definition of the Terms 
       [0025]    The following terms which may be used in the various claims and/or specification of this patent are intended to have their broadest meaning consistent with the requirements of law: 
         [0026]    As used herein, “front” or “forward” is used by reference to the front or toward the front of a gas grill which typically includes the control panel, gas control knobs and the like. 
         [0027]    As used herein, “rear” or “rearward” is used by reference to the back or toward the back of a typical gas grill. 
         [0028]    As used herein, “air shutter” shall mean the device, typically found at the open end of the burner tube, that cooperates with the open end of the burner tube to permit the adjustment of an opening of the burner tube to control the fuel to combustion air mixture. 
         [0029]    As used herein, “ignition system” shall mean devices that are capable of generating sparks to ignite the fuel/air mixture emitted from the outlet ports of a burner tube. 
         [0030]    Where alternative meanings are possible, in either Ute specification or claims, the broadest meaning is intended consistent with the understanding of those of ordinary skill in the art. All words used in the claims are intended to be used in the normal, customary usage of grammar, the trade and the English language. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]    The stated and unstated objects, features and advantages of the present inventions (sometimes used in the singular, but not excluding the plural) will become apparent from the following descriptions and drawings, wherein like reference numerals represent like elements in the various views, and in which: 
           [0032]      FIG. 1  is a side plan view of a preferred embodiment of a burner tube of the present invention, shown with a preferred air shutter and preferred venturi member installed and shown with the closed end prior to closure; 
           [0033]      FIG. 2  is an exploded perspective view of the components of the embodiment of  FIG. 1  and showing the closed end, closed; 
           [0034]      FIG. 3  is a side plan view of a preferred embodiment of the burner tube of the present invention of  FIG. 1 ; 
           [0035]      FIG. 4  is atop plan view of the preferred burner tube of  FIG. 3 ; 
           [0036]      FIG. 5  is a perspective view of the preferred burner tube of  FIG. 3 ; 
           [0037]      FIG. 6  is a cross-sectional detail view of the preferred raised gas ports of the present invention; 
           [0038]      FIG. 7  is a top detail plan view of the preferred raised gas ports of the present invention; 
           [0039]      FIG. 8  is a perspective view of a preferred venturi member of the present invention; and, 
           [0040]      FIG. 9  is a perspective view of a preferred air shutter of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0041]    Set forth below is a description of what is currently believed to be the preferred embodiments or best representative examples of the inventions claimed. Future and present alternatives and modifications to the embodiments and preferred embodiments are contemplated. Any alternatives or modifications which make insubstantial changes in function, purpose, structure or result are intended to be covered by the claims of this patent. 
         [0042]    The overall aspects of a burner assembly  10  of the present inventions may be seen by reference to  FIGS. 1 and 2 . Burner assembly  10  includes a preferred burner tube  20 , an air shutter  50  and a venturi member  60 . Burner tube  20  has a length between an open end  21  and a closed end  22 . Open end  21  is typically toward the front of the grill adjacent to a gas valve and gas distribution manifold (not shown) and the closed end  22  is typically secured to the rear of a grill. In most situations, a grill will include a plurality of burner tubes  20  spaced parallel to each other. 
         [0043]    In a preferred embodiment, burner tube  20  has a rectangular cross-sectional shape, with an upper surface  23 , two side surfaces  24 ,  25  and a bottom surface  26  forming a substantially hollow interior. It will be understood by those of skill in the art that the cross-sectional shape of hunter tube  20  does not have to be rectangular, as in the preferred embodiment. For example, the cross-sectional shape may be square, circular or oval. In the preferred embodiment, the burner tube  20  is tapered, i.e., there is a gradual decrease in cross-sectional area along the length from the open end  21  to the closed end  22 . This permits a constant pressure of the fuel/air mixture throughout the length of the burner tube  20 . A window  28  is provided on each side  24 ,  25  near the open end  21  of burner tube  20 . The window  28 , in conjunction with air shutter  50  ( FIG. 9 ), is used to adjust the air/fuel mixture as will be understood by those of skill in the art. 
         [0044]    A plurality of gas ports  30  are also provided. In a preferred embodiment, gas ports  30  are equally spread along the top surface  23  of the burner tube  20 . It will be understood by those of skill in the art that the number and spacing of ports, as well as the size of the cross-sectional shape of burner tube  20 , is calculated or determined based upon the BTU&#39;s desired from each burner tube  20 . Importantly, the gas ports  30  are formed or extruded from the inside of tube  20  to the outside of tube  20 . In this manner, unlike conventional burner tubes which are punched from the outside to the inside of the tube, there are no burrs or obstructions on the inside of the burner tube  20  to obstruct the fuel/air flow or to make that flow turbulent. As a result, desirable blue flame characteristics, among other advantages, are achieved. 
         [0045]    In the preferred embodiment and preferred method of its manufacture, burner tube  20  is constructed from a single sheet of appropriately sized and shaped material, typically stainless steel. On what will become the inside of burner tube  20 , gas ports  30  are formed or extruded on what will be the top surface  23 . Once the ports  30  are formed from the inside to the outside, the sheet of material is then folded to form the upper  23  and side surfaces  24 ,  25 , as well as bottom surface  26 . A tab  27  is provided and welded together so that a substantially hollow, tapered and burr-free burner tube  20  is formed. See  FIGS. 1, 2, 3 and 5 . It will be understood by those of skill in the art that there are methods, other than the preferred method, of manufacturing tapered burner tube  20  and ports  30  consistent with the goals and objects of the present inventions. 
         [0046]    The preferred raised gas ports  30  of the present inventions may better be seen by reference to  FIGS. 6 and 7 . Each port  30  has a height  32  measured from the upper surface  23  with an opening  33  at the top of the height  32 . Each opening  33  has a diameter  34 . In the preferred embodiment, the openings  33  are circular. It will be understood by those of skill in the art that openings  33  may be another shape and that the dimensions discussed herein for diameter may be readily converted to area if, for example, square or rectangular openings are used. Because the opening  33  of port  30  is raised above upper surface  23  of burner tube  20 , the flame is also lifted above upper surface  23  of burner tube  20 . This improves flame quality and reduces the temperature of tube  20  during grilling, which increases the life of the tube  20  and prevents corrosion and clogging of the port openings  33 . It will be understood by those of skill in the art that ports  30  may alternatively be located on one or both side surfaces  24 ,  25 . It will also be understood that non-rectangular shapes of burner tube  20  may also be used consistent with the present inventions. 
         [0047]    Tests have shown that the ratio of port height  32  to port opening  33  diameter  34  is important to proper and efficient flame quality and burner tube  20  longevity. The ideal theoretical port height  32  to port opening  33  diameter  34  is 1:1. However, in practice, that ratio is unobtainable when cost effectively manufacturing a burner tube  20  of the present inventions. Since the ports  30  are formed from the material of upper surface  23 , there is only so much material available to form the ports  30 , as will be understood by those of skill in the art. In addition, tests have also shown that in burner tubes  20  sized for use in typical gas grills, the port opening  33  diameter  34  should not exceed 0.110″ to avoid flame pullback into burner tube  20 . Thus, it has been determined that the maximum, reasonably feasible port height  32  is approximately 0.020″ to 0.062″. And, the preferred port opening  33  diameter  34  is between approximately 0.075″ and 0.110″. In the preferred embodiment, the port height  32  to opening diameter  34  ratio is approximately 0.645. This preferred ratio is achieved using a preferred port height  32  of 0.060″ and a preferred port opening diameter  34  of 0.093″. This preferred configuration, along with the taper of burner tube  20 , provides the best flame quality, reduces clogging and extends the life of the burner tube  20 . 
         [0048]    A preferred venturi member  60  may be seen by reference to  FIG. 8 . Venturi member  60  includes a front face  61  having an opening  62  to accommodate the neck of a typical gas valve (not shown). A rearwardly projecting side tab  63  having a hole  64  is also provided on each side of front face  61 . A top flange  65  and a bottom flange  66  project rearward of face  61 . Top flange  65  includes a v-shaped portion having an apex  67 . Similarly, bottom flange  66  includes an inverted v-shaped portion having an apex  68 . As can be seen in  FIG. 8 , the space between the top and bottom flanges  65  and  66  becomes constricted where the two opposing apexes  67  and  68  meet. A stabilizer brace  69  is provided at the rear of the member to support the upper and lower flanges  65  and  66 . A hole  70  may be provided on upper flange  65  near the front in order lo accommodate a screw used to secure air shutter  50  to the hunter tube  20  (see  FIGS. 2 and 9 ), as hereinafter described. 
         [0049]    As shown in  FIGS. 1 and 2 , venturi member  60  is inserted into the open end  21  of burner tube  20 . It may be affixed to the burner tube  20  using a screw (not shown) through hole  64  of tab  63  into holes  71  in the sides  24 ,  25  of burner tube  20 . ft will be understood that other means may be used to attach venturi member  60  to burner tube  20 . 
         [0050]    When inserted into burner tube  20 , the neck of a typical gas valve (not shown) is inserted into opening  62 . As the fuel/air mixture passes between the space between upper apex  67  and lower apex  68 , it velocity is increased. It will be understood by those of skill in the art that venturi member  60  is shaped and sized to fit within the open end  21  and coincides with the cross-sectional shape of burner tube  20 . 
         [0051]    A preferred air shutter  50  of the present inventions may be seen by reference to  FIG. 9 . As will be understood by those of skill in the art, air shutter  50  cooperates with the window  28  at the open end  21  of burner tube  20  to permit adjustment of the combustion air to fuel mixture. Preferred shutter  50  includes a top  51  having a slot  52  which is used to secure shutter  50  through hole  72  to burner tube  20  once in the proper position for the desired mixture. Shutter  50  includes two sides  53 , each having a recess  54  and two bottom sections  55 . It will be understood by those of skill in the art that a space between bottom members  55  is provided to accommodate tab  27  on the bottom of burner tube  20  that is part of a preferred manufacturing process. The recesses  54  of sides  53  accommodate the attachment flanges  63  of venturi member  60  when it is attached to burner tube  20 . 
         [0052]    When in use, the neck of a gas valve is inserted into opening  62  of venturi member  60  with the open end of burner tube  20  typically at the front of the grill. The closed end  22  of burner tube  20  is movably secured to a rear of the grill and the open end slidingly connected to the valve neck by the air shutter  50 . In this manner, tube  20  may expand and contract as necessary during use. The gas is injected into venturi member  60  and mixed with the desired amount of combustion air using air shutter  50 . The velocity of the fuel/air mixture is accelerated by die venturi member  60  and flows down the length of burner tube  20 . Because of the taper of burner tube  20 , the pressure throughout the length of the tube  20  is relatively constant. 
         [0053]    When lit, the flame sits on top of the raised gas ports  30  at the opening  33 . Since the flame is lifted off of the upper surface  23  of burner tube  20 , the burner tube  20  remains cooler. This results in less port  30  clogging and less corrosion of the burner tube  20 . In this manner, a longer life of burner tube  20  and high flame quality may be achieved. In addition, when the preferred port height  32  to port opening  33  diameter  34  is used, flame quality is further increased. 
         [0054]    The above description is not intended to limit the meaning of the words used in or the scope of the following claims that define the invention. Rather, it is contemplated that future modifications in structure, function or result will exist that are not substantial changes and that all such insubstantial changes in what is claimed are intended to be covered by the claims. Thus, while preferred embodiments of the present inventions have been illustrated and described, it will be understood that changes and modifications can be made without departing from the claimed invention. In addition, although the term “claimed invention” or “present invention” is sometimes used herein in the singular, it will be understood that there are a plurality of inventions as described and claimed. 
         [0055]    Various features of the present inventions are set forth in the following claims.