Patent Publication Number: US-6699036-B2

Title: Curvilinear burner tube

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     TECHNICAL FIELD 
     The present invention relates to a burner tube for use with a cooking chamber. More specifically, the present invention relates to an elongated curvilinear burner tube having a union region that forms a continuous, multi-directional passageway for the flow of fuel. 
     BACKGROUND OF THE INVENTION 
     The popularity of gas barbecue grills and gas outdoor cooking devices has increased tremendously over the last twenty-five years. In contrast to charcoal barbecue grills, gas barbecue grills employ a burner assembly that requires a combustible fluid, for example, propane or natural gas, as a fuel source. Barbecue grills with gas burner elements have proven extremely popular with consumers because they provide controlled, uniform heat distribution. In addition, gas burner assemblies are relatively simple to operate and generally require less maintenance and clean-up time. 
     Conventional gas burner assemblies typically include a plurality of linear burner tubes, control valves, and a manifold. Each burner tube has a first end and a second end, and a plurality of fuel outlet ports spaced between the first and second ends. The first end of the burner tube is connected to a control valve which meters the flow of fuel. The first end and the control valve are connected to the manifold which is linked to a fuel source, for example, a propane tank. Therefore, multiple burner tubes extend from the manifold. The second end of the burner tube is closed or crimped such that fuel cannot flow past the second end. Accordingly, fuel from the fuel source flows in only one linear path, from the first end to the second end of the burner tube. 
     Conventional burner assemblies require specific construction and assembly that are susceptible to higher cost and related limitations. First, due to the fact multiple burner tubes are required to form a burner assembly, the material, labor, and assembly costs are significant. These costs are compounded by the fact that each burner tube may require a separate inlet assembly, including a venturi element and a control valve. Further, because the second end of burner tubes are closed or crimped, the first end of each burner tube must be connected to a manifold, thereby limiting the configuration of the burner assembly. Consequently, the versatility of conventional burner assemblies is reduced because such assemblies cannot be uniquely configured or utilized in a wide variety of cooking chambers. 
     An example of a burner assembly susceptible to the limitations identified above is U.S. Pat. No. 5,676,048 to Schroeter et al. As shown in FIGS. 2 and 11 therein, a burner assembly  17  is formed from the combination of a linear burner tube  18  and two “L-shaped” burner tubes  24 . The linear burner tube  18  has a first end  19  and a closed or crimped second end  20 . Referring to FIG. 12, the L-shaped burner tube  24  has a primary member  25 , a secondary member  28 , and a curved elbow segment  31 . The first end  26  of the L-shaped burner tube  24  is open, while the second end  30  is closed. Consequently, in either burner tube  18 ,  24 , fuel is constrained to flow in a single path—from the first end to the closed second end. 
     Another example of a burner assembly with the concerns identified above is U.S. Pat. No. 5,890,482 to Farnsworth et al. As shown in FIG. 2, the burner assembly is formed from the combination of six (6) burner tubes  14 . Each burner tube has a venturi element, an inlet valve assembly, a first series of outlet ports, and a second series of outlet ports. Referring to FIG. 3, the burner tube  14  has a first segment  44 , a second segment  42 , and a curved elbow segment  46 . The first segment  44  is open while the second segment  42  has a closed end. Accordingly, in the burner tubes  14 , fuel flows from the first end to the closed second end. 
     Yet another example of a burner assembly of the prior art construction is U.S. Pat. No. 6,102,029 to Schlosser et al., which is assigned to the Assignee of the present invention. As shown in FIGS. 3-5, the burner assembly  10  generally comprises a first burner tube  21 , a second burner tube  22 , a third burner  23 , and a crossover tube  24 . The second burner tube  22  is positioned between the first and second burner tubes  21 ,  23  to form a burner grid  20 . Each burner tube  21 ,  22 ,  23  has a first end with a venturi assembly  32  connected to a control valve  30  of the manifold  16 . The second end  25  of the first, second, and third burner tubes  21 ,  22 ,  23  is closed. A crossover tube  24  ports with an orifice  28  located upstream of the second end  25  in the first and second burner tubes  21 ,  22 . The crossover tube  24  is in fluid communication with only the first burner tube  21  and the third burner tube  23 . Accordingly, the crossover tube  24  serves as a pilot tube for either the first or third burner tube  21 ,  23 . The closed, second end  25  of the second burner tube  22  has a flange  40  that is adapted to be received by a stock connection  42  attached to the crossover tube  24 . Since the second burner tube  22  is not in fluid communication with the crossover tube  24 , the second burner tube  22  only receives fuel from the manifold  16 . Therefore, in the second burner tube  22 , fuel can only flow from the first end to the second end. 
     Therefore, there is a need for a continuous burner assembly formed from a burner tube wherein fuel can flow in multiple paths or directions throughout the burner tube. Also, there is a definite need for a continuous burner assembly which is compact and capable of being employed in a wide variety of cooking chambers. In addition, there is considerable need for a continuous burner assembly with a single inlet valve assembly to minimize the overall size of the burner assembly while providing an enlarged burner flame area. 
     The present invention is provided to solve these and other deficiencies. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a burner for use with a cooking chamber. More specifically, the present invention relates to a continuous burner constructed from an elongated burner tube having a proximal segment, a distal segment, and a terminal end in fluid connection with a union region of the proximal segment. Due to the fluid connection between the terminal end and the union region, the burner has a curvilinear configuration and defines a multi-directional passageway for the flow of fuel throughout the burner. 
     The proximal segment is adapted to be connected to a fuel source, i.e., a fuel tank. The distal segment is downstream of the proximal segment. The terminal end is connected to the burner tube at a union or interference region of the proximal segment. The connection between the terminal end and the union region forms a continuous burner tube with a multi-directional passageway. This means that fuel from the fuel source can flow throughout the burner tube, including the proximal segment, the distal segment, the union region, and the terminal end. Specifically, fuel can flow from the proximal segment through the union region and into and through the terminal end. The burner tube has a plurality of fuel outlet ports or apertures from which flames extend. An ignitor is used to ignite fuel that has exited the outlet ports along the burner tube to form a burner flame area. 
     The burner tube can have a variety of configurations, including a generally obround or rectangular configuration. Preferably, the distal segment has at least one curvilinear portion, which facilitates the connection of the terminal end with the union region. Due to the mating of the terminal end with the proximal segment, the burner tube defines an enclosed central region. The terminal end is connected to the union region whereby the continuous, integral burner tube is formed. The connection between the terminal end and the union region is facilitated by the curvilinear portion. The terminal end can have a necked portion with a tapered diameter, and a mating portion. The mating portion is either partially or entirely received by an aperture in the union region. Once received by the aperture, the terminal end is in fluid communication with the union region of the proximal segment. The fluid communication between the union region and the mating portion defines a passageway or control volume for fuel to flow throughout the burner tube. 
     In accord with the invention, the burner tube is in a first position P 1  wherein the terminal end is connected to the union region. Due to the curvilinear configuration of the distal segment, the terminal end is biased towards the union region. This biasing causes the terminal end to be lockingly engaged to, or secured with the union region in the first position P 1 . In a second position P 2 , the terminal end is unconnected or disengaged from the union region and due to the biasing described above, a portion of the terminal end extends past the union region. Also, in the second position P 2 , the terminal end is vertically misaligned with a plane defined by the burner tube. The second position P 2  generally represents an unassembled status of the burner tube. Once aligned with the aperture, the biasing of the burner tube will cause the terminal end to lockingly engage the union region. 
     In the first position P 1 , fuel flows from the fuel source in an initial flow path through the proximal segment and into the union region. Flow separation occurs generally within the union region. A first flow path F 1  flows past the union region and downstream to the distal region. Because the terminal end is in fluid communication with the union region, a second flow path F 2  flows past the union region and downstream into the terminal end. Therefore, fuel from the fuel source can flow in one of two distinct paths, downstream into the distal region or downstream into the terminal end. 
     In further accord with the invention, the terminal end has a mating portion that is in fluid communication with the aperture of the union region. The mating portion can be received by the aperture. Structure of the mating portion can extend past the aperture such that an edge or wall of the mating portion extends into the union region. This results in alteration of the fuel flow in the union region. As a result, a first portion of fuel flows through the union region and downstream into the distal region and a second portion of fuel flows through the union region and downstream into the terminal end. The geometry of the mating portion and the degree or amount that the mating portion extends past the aperture affects the flow of the fuel in the burner tube. 
     Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a barbecue grill assembly showing a first burner tube of the invention; 
     FIG. 2 is a top plan view of the first burner tube of FIG. 1; 
     FIG. 3 is a partial cross-section of the first burner tube taken along line  3 — 3  of FIG. 2, showing a first connection between a terminal end and a union region; 
     FIG. 4 is a partial cross-section of the first burner tube taken along line  4 — 4  of FIG. 3; 
     FIG. 5 is a partial cross-section of the first burner tube taken along line  3 — 3  of FIG. 2, showing a second connection between the terminal end and the union region; 
     FIG. 6 is a partial cross-section of the first burner tube taken along line  3 — 3  of FIG. 2, showing a third connection between the terminal end and the union region; 
     FIG. 7 is a partial cross-section of the first burner tube taken along line  7 — 7  of FIG. 6; 
     FIG. 8 is a partial cross-section of the first burner tube taken along line  3 — 3  of FIG. 2, showing a fourth connection between the terminal end and the union region; 
     FIG. 9 is a partial cross-section of the first burner tube taken along line  9 — 9  of FIG. 8; 
     FIG. 10 is a partial cross-section of the first burner tube taken along line  3 — 3  of FIG. 2, showing a fifth connection between the terminal end and the union region; 
     FIG. 11 is a partial cross-section of the first burner tube taken along line  11 — 11  of FIG. 10; 
     FIG. 12 is a partial cross-section of the first burner tube taken along line  3 — 3  of FIG. 2, showing a sixth connection between the terminal end and the union region; 
     FIG. 13 is a partial cross-section of the first burner tube taken along line  13 — 13  of FIG. 12; 
     FIG. 14 is a partial cross-section of the first burner tube taken along line  3 — 3  of FIG. 2, showing a seventh connection between the terminal end and the union region; 
     FIG. 15 is a partial cross-section of the first burner tube taken along line  15 — 15  of FIG. 14; and, 
     FIG. 16 is a top plan view of a second burner tube of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated. 
     A barbecue grill assembly  10  is shown in FIG.  1 . The barbecue grill assembly  10  generally includes a cooking chamber  12  and a support frame assembly  14 . The frame assembly  14  is adapted to provide support to the cooking chamber  12 . The cooking chamber  12  includes a cover  16  hingeably connected to a firebox  18 . The barbecue grill assembly  10  further includes a first work surface  20  and a second work surface  22 , each operably connected to a transverse member  24  of the support frame assembly  14 . The firebox  18  has an interior geometry or configuration defined by a first wall  126 , a second wall  27 , a front wall  28 , and a rear wall  29 . As shown in FIG. 1, the first and second walls  26 ,  27  are sloped or curved. 
     An elongated burner tube  30  is positioned generally within the firebox  18  of the cooking chamber  12 . The burner tube  30  has a multi-directional configuration which results in passageways for the flow of fuel throughout the burner tube  30 . The burner tube  30  has a geometry similar to the interior geometry of the firebox  18  whereby the burner tube  30  is received by the firebox  18 . Because the burner tube  30  can be configured to match the configuration of the firebox  18 , the utility and versatility of the burner tube  30  is increased. Preferably, the burner tube  30  is a cylindrical element with a circular cross-section with an inner wall diameter and an outer wall diameter. The burner tube  30  is connected to a fuel source (not shown) to define a pathway for flow of the fuel. The burner tube  30  is positioned generally between a grid or grate  32  and a bottom wall (not shown) of the firebox  18 . A portion of the burner tube  30  extends through a port or opening  34  in the proximal sidewall  26  of the firebox  18 . An ignitor  38  is used to ignite fuel as it flows through the burner tube  30 . 
     Referring to FIG. 2, the burner tube  30  has a curvilinear configuration with proximal segment  42 , a curvilinear distal segment  44 , and a terminal end  46 . The proximal segment  42  is adapted to be connected to a fuel source, i.e., a fuel tank. The distal segment  44  is downstream of the proximal segment  42 , meaning that fuel flows from the proximal segment  42  to the distal segment  44 . Unlike conventional burner tubes, the terminal end  46  connects to, or mates with the burner tube  30  at a union or interface region  48  of the proximal segment  42 . Thus, the union region  48  is a junction zone between the terminal end  46  and the proximal segment  42 . The connection between the terminal end  46  and the union region  48  forms a continuous burner tube or burner loop  30  wherein fuel flows in two distinct paths—through the distal segment  44  and through the terminal end  46 . Described in a different manner, the terminal end  46  is in fluid communication with the proximal segment  42  at the union region  48  forming a multi-directional passageway that permits the flow of fuel between the proximal segment  42  and the terminal end  46 . Described in yet another manner, the connection between the terminal end  46  and the union region  48  forms a control volume with multi-directional paths for the flow of fuel. Although shown as having a “P-shaped” or “D-shaped” configuration, the configuration and dimensions of the burner tube  30  can vary. For example, the burner tube  30  can have a round, square, or elliptical configuration. 
     As shown in FIG. 1, the burner tube  30  is positioned within the firebox  18  such that a portion of the proximal segment  42  extends through an aperture  34  in the second wall  27  of the firebox  18 . Consequently, the distal segment  44  of the burner tube  30  is cooperatively positioned with the first wall  26  of the firebox  18 . An inlet port  52  and a venturi element  54  of the proximal segment  42  are positioned beyond the firebox  18 , and the inlet port  52  is connected to the fuel source. A control valve can be employed to regulate the supply of fuel from the fuel source. Accordingly, fuel from the fuel source passes through the proximal segment  42  and downstream to the distal segment  44  and the terminal end  46 . Since the inlet port  52  is connected to the fuel source, no manifold is required for operation of the burner tube  30 . 
     The distal segment  44  has at least one curvilinear portion  56 , which contributes to the generally obround or rectangular configuration of the burner tube  30 . As shown in FIG. 2, the distal segment  44  has three curvilinear portions  56 , however, the precise number of such portions varies with the overall configuration of the burner tube  30 . For example, the burner tube  30  can have an oval or elliptical configuration in which there would be a single, generally continuous curvilinear portion  56 . In addition, the degree or amount of curvature varies with the overall configuration of the burner tube  30 . The curvilinear portion  56  facilitates the connection of the terminal end  46  with the union region  48 . Due to the mating of the terminal end  46  with the proximal segment  42 , the burner tube  30  defines an enclosed central region  58 . Although shown as having a generally obround or rectangular configuration, the central region  58  can have a round, square, or elliptical configuration. 
     The burner tube  30  has a plurality of outlet ports or apertures  60  from which a flame extends. Due to its multi-directional configuration, the continuous burner tube  30  forms an enlarged burner flame area compared to a conventional linear burner. The ignitor  38  (see FIG. 1) is used to ignite the fuel that has flowed through the through the burner tube  30  and exited the ports  60 . As shown in FIG. 2, the outlet ports  60  are linearly aligned along the burner tube  30  to discharge fuel in a substantially vertical direction, meaning perpendicular to the plane of the burner tube  30 . As a result, the outlet ports  60  are positioned in an upper portion of the burner tube  30  such that the resulting flame is directed towards the grate  32 . Preferably, the outlet ports  60  are positioned at an upper portion of the burner tube  30  when viewed in cross section. Alternatively, the ports  60  are positioned in a side portion of the burner tube  30 . Preferably, the outlet ports  60  are positioned throughout the burner tube  30 , including the union region  48 . The first or initial outlet port  60   a  is spaced a distance from the venturi element  54 . Due to its multi-directional configuration, the continuous burner tube  30  forms an enlarged flame area, which is the sum of flames extending the outlet ports  60 , that is consistent with the interior geometry of the firebox  18 . 
     The distal segment  44  includes a bracket  61 , that in combination with the aperture  50  in the proximal wall  26  of the firebox  18 , supports the burner tube  30  within the firebox  18 . A ramp or ledge (not shown) of the first wall  26  includes a fastener (not shown) that is cooperatively positioned for engagement with the bracket  61 . The bracket  61  and the aperture  50  combine to support the burner tube  30  in an elevated position with respect to the bottom wall of the firebox  18 . Preferably, the bracket  61  is welded to the burner tube  30 . 
     Referring to FIGS. 3 and 4, the terminal end  46  is in fluid connection with the union region  48  thereby forming the continuous burner tube  30 . Due to the fluid connection, the burner tube  30  has a multi-directional passageway for the continuous flow of fuel. This structural aspect of the burner tube  30  provides multi-directional fuel flow through the tube  30 . The connection between the terminal end  46  and the union region  48  is facilitated by the curvilinear portion  56 . The terminal end  46  has a necked portion  62  with a tapered diameter that ceases at a mating portion  64 . Accordingly, the diameter of the mating portion is less than the diameter of the necked portion  62 . The mating portion  64  is either partially or entirely received by an aperture  66  in the union region  48 . Once received by the aperture  66 , the terminal end  46  is in fluid communication with the union region  48  of the proximal segment  42 . The fluid communication between the union region  48  and the mating portion  64  defines a loop or passageway for fuel to flow throughout the burner tube  30 . 
     To ensure the fluid communication, the diameter of the aperture  66  is equivalent to the diameter of the mating portion  64 . Preferably, the diameter of the aperture  66  and the mating portion  64  is less than the diameter of the burner tube  30  at the union region  48 . As shown in FIGS. 3 and 4, the aperture  66  and the mating portion  64  have a circular configuration when viewed in cross-section. Alternatively, the aperture  66  and the mating portion  64  can have an oval or elliptical configuration. A force can be applied to the terminal end  46  to deform it radially inward such that the mating portion  64  has an oval or elliptical configuration. 
     As shown in FIG. 2, the terminal end  46  is connected to the union region  48  at a connection angle θ, defined as the angle between the union region  48  and the terminal end  46 . Although shown as approximately 90 degrees, the connection angle θ varies between 10 to 90 degrees along with the design parameters of the burner tube  30 . The configuration of the burner tube  30  will be altered as the connection angle θ is varied. For example, when the connection angle θ is between 30-60 degrees the burner tube  30  has a “V-shaped” junction between the union region  48  and the terminal end  46 . In addition, the geometry of the aperture  66  will vary with the connection angle θ. Where the connection angle θ is approximately 90 degrees, the aperture  66  will have a circular configuration. Where the connection angle θ is less than 90 degrees, the aperture  66  will have an elliptical configuration. 
     As shown in FIG. 4, the burner tube  30  has a first wall  68  and a second wall  70 . Preferably, the aperture  66  is formed in the first wall  68  and has an leading edge  66   a  and a trailing edge  66   b . The mating portion  64  has a leading edge wall  64   a  and a trailing edge wall  64   b . The leading edge wall  64   a  extends past the leading edge  66   a  of the aperture  66  and into the union region  48 , and the trailing edge wall  64   b  extends past the trailing edge  66   b  of the aperture  66  and into the union region  48 . Preferably, the trailing edge wall  64   b  extends further into the internal area of the union region  48  than the leading edge wall  64   a . As a result, the mating portion  64  has an angled or flared tip  76 . The degree or amount that the trailing edge wall  64   b  extends past the trailing edge  66   b  of the aperture  66  varies with the design parameters of the burner tube  30 . As discussed below, the geometry of the mating portion  64  and/or tip  76  can affect the flow of the fuel through the burner tube  30 . 
     Referring to FIGS. 2-4, the burner tube  30  is in a first position P 1  wherein the terminal end  46  is connected to the union region  48 . Due to the curvilinear configuration of the distal segment  44 , the terminal end  46  is biased towards the union region  48 . This biasing causes the terminal end  46  to be lockingly engaged to, or secured with the union region  48  in the first position P 1 . Consequently, a fastening member or weldment is not required to maintain the connection between the terminal end  46  and the union region  48 . In a second position P 2 , the terminal end  46  is unconnected or disengaged from the union region  48  and due to the biasing described above, a portion of the terminal end  46  extends past the union region  48 . Described in a different manner, a portion of the terminal end  46  extends past the first wall  68  and/or the second wall  70  of the burner tube  30 . Described in yet another manner, a portion of the terminal end  46  extends past a longitudinal axis of the union region  48 . Also, in the second position P 2 , the terminal end  46  is vertically misaligned with a plane defined by the burner tube  30 . Described in a different manner, the terminal end  46  passes either above or below the plane defined by the burner tube  30 . The second position P 2  generally represents an unassembled status of the burner tube  30 . To move the burner tube  30  from the second position P 2  to the first position P 1 , the biasing resulting from the curvilinear configuration must be overcome. First, a sufficient amount of force must be applied to the terminal end  46  such that it retracts and clears the first wall  68 . Once this force is applied, a second force must be applied to the terminal end  46  to align it with the aperture  66 . Once aligned with the aperture  66 , the biasing of the burner tube  30  will cause the terminal end  46  to lockingly engage the union region  48 . 
     In the first position P 1 , fuel flows from the fuel source in an initial flow path F through the proximal segment  42  and into the union region  48 . Flow separation occurs generally within the union region  48 . As indicated by the streamlines in FIG. 4, a first fuel portion, as indicated by second flow path F 2 , flows past the union region  48  and downstream to the distal region  44 . Because the terminal end  46  is in fluid communication with the union region  48 , a second fuel portion, as indicated by first flow path F 1 , flows past the union region  48  and downstream into the terminal end  46 . Described in different terms, the flow path F of the fuel begins to diverge at the union region  48 , with the second flow path F 2  flowing through the distal region  44  and the first flow path F 1  flowing through the terminal end  46 . Since the terminal end  46  is in fluid communication with the proximal segment  42  in the first position P 1 , the fuel can flow in one of two distinct paths—downstream into the distal region  44  or downstream into the terminal end  46 . In the second position P 2 , there is no connection between the terminal end  46  and the union region  48  and as a result, the first flow path F 1  will not flow into the terminal end  46  from the union region  48 . 
     In another preferred embodiment shown in FIG. 5, the terminal end  146  has a mating portion  164  with at least one opening  180 . The opening  180  is adapted to permit an amount of the second flow path F 2  to flow past the union region  48  and downstream to the proximal segment  42 . Preferably, the opening  180  is positioned in a trailing wall  164   b  of the mating portion  164 . The precise amount of the second flow path F 2  that passes through the opening  180  depends upon a number of factors, including but not limited to the degree of insertion of the mating portion  164  in the union region  148 , the configuration of the opening  180 , and the flow rate of the fuel from the fuel source. 
     In another preferred embodiment shown in FIGS. 6 and 7, the terminal end  246  has a necked portion  262  with a tapered diameter that terminates in a mating portion  264 . The terminal end  246  is connected to the aperture  266  of the union region  248 . Referring to FIG. 7, a leading edge wall  264   a  of the mating portion  264  is positioned coincident with a leading edge  266   a  of the aperture  266 . A trailing edge wall  264   b  of the mating portion  264  is positioned coincident with a trailing edge  266   b  of the aperture  266 . Accordingly, the mating portion  264  does not extend past the aperture or into the union region  248 . Preferably, the mating portion  264  is coped to fit against the first wall  268  of the burner tube  230 . 
     In the first position P 1 , the terminal end  246  is in fluid communication with the union region  248 . Due to the curvilinear configuration of the burner tube  230 , the terminal end  230  is biased towards the union region  248 . Accordingly, the mating portion  264  is lockingly engaged or secured to the union region  248  without the use of a fastener or weldment. In the first position P 1 , as indicated by the streamline F, fuel flows from the fuel source through the proximal segment  242  of the burner tube  230  and into the union region  248 . As explained above, a second flow path F 2  flows past the union region  248  and downstream to the distal region (not shown) of the burner tube  230 . Because the terminal end  246  is in fluid communication with the union region  248 , a first flow path F 1  flows past the union region  248  and downstream into the terminal end  246 . Described in different terms, the flow of fuel F begins to diverge at the union region  248 , with the second flow path F 2  flowing to the distal region and the first flow path F 1  flowing through the terminal end  246 . 
     In another preferred embodiment shown in FIGS. 8 and 9, the terminal end  346  has a necked portion  362  with a tapered diameter that terminates in a mating portion  364 . The terminal end  346  is connected to the aperture  366  of the union region  348 . Referring to FIG. 9, a leading edge wall  364   a  of the mating portion  364  is positioned coincident with a leading edge  366   a  of the aperture  366 . A trailing edge wall  364   b  of the mating portion  364  extends past a trailing edge  366   b  of the aperture  366  and into the union region  348 . An insertion element  380  is positioned between the trailing edge  366   b  of the aperture  366  and the trailing edge  364   b  of the mating portion  364 . The insertion element  380  is an “L-shaped” structure that is adapted to alter the fluid flow in the union region  348 . The insertion element  380  is affixed to a first wall  368  of the burner tube  330  such that a portion of the insertion element  380  extends into the aperture  366 . The degree or amount that the insertion element  380  extends into the aperture  366  varies with the design parameters of the element  380  and the burner tube  330 . 
     In the first position PI, the terminal end  346  is in fluid communication with the union region  348 . Due to the curvilinear configuration of the burner tube  330 , the terminal end  330  is biased towards the union region  348 . Accordingly, the mating portion  364  is lockingly engaged or secured to the union region  348  without the use of a fastener or weldment. In the first position P 1 , as indicated by the streamline F, fuel flows from the fuel source through the proximal segment  342  of the burner tube  330  and into the union region  348 . As explained above, a second flow path F 2  flows past the union region  348  and downstream to the distal region (not shown) of the burner tube  330 . Because the terminal end  346  is in fluid communication with the union region  348 , a first flow path F 1  flows past the union region  348  and downstream into the terminal end  346 . Described in different terms, the flow of fuel begins to diverge at the union region  348 , with the second flow path F 2  flowing to the distal region and the first flow path F 1  flowing through the terminal end  346 . The geometry of the insertion element  380  causes a flow disturbance in the union region  348  which alters the flow of the first and second flow paths F 1 , F 2 . Compared to the embodiment shown in FIGS. 7 and 8, the insertion element  380  increases the quantity of fuel flowing through the terminal end  346 . 
     In another preferred embodiment shown in FIGS. 10 and 11, the terminal end  446  has a necked portion  462  with a tapered diameter that terminates in a mating portion  464 . The terminal end  446  is connected to the aperture  466  of the union region  448 . Referring to FIG. 11, a leading edge wall  464   a  of the mating portion  464  is positioned coincident with a leading edge  466   a  of the aperture  466 . A trailing edge wall  464   b  of the mating portion  464  is positioned coincident with a trailing edge  466   b  of the aperture  466 . Accordingly, the mating portion  464  does not extend past the aperture or into the union region  548 . Preferably, the mating portion  564  is coped to fit against the first wall  568  of the burner tube  530 . A vane  580  is positioned within the burner tube  530 , preferably in the union region  548 . The vane  580  is a curvilinear structure adapted to alter the fuel flow in the union region  548 . The vane  580  is affixed to a lower portion  582  of the burner tube  530  and extends upward from the lower portion  582 . The vane  580  has a leading edge  580   a  and a trailing edge  580   b . As shown in FIG. 11, the leading edge  580   a  is positioned in the union region  548  upstream of the aperture  566  and the trailing edge  580   b  is positioned at a midpoint of the aperture  566 . However, the precise location of the vane  580  within the union region  548  can vary. Referring to FIG. 10, the height of the vane  580  is approximately one-half of the diameter of the burner tube  530 . However, the height of the vane  480  can vary such that the vane  480  occupies a greater or lesser amount of the union region  448 . 
     In the first position P 1 , fuel F flows from the fuel source through the proximal segment  442  of the burner tube  430  and into the union region  448 . Flow separation occurs at the leading edge  480   a  of the vane  480 , where the leading edge  480   a  is the separation point. As indicated by the streamlines of FIG. 11, the initial flow path F is separated into two distinct flow paths F 1 , F 2 . The second flow path F 2  flows along and past an outer surface  480   c  of the vane  480  and downstream to the distal region (not shown) of the burner tube  430 . Because the terminal end  446  is in fluid communication with the union region  448 , the first flow path F 1  flows along and past an inner surface of the vane  480  and downstream into the terminal end  446 . Described in different terms, the vane  480  causes a flow disturbance in the union region  448  which alters the initial flow path F into the first and second flow paths F 1 , F 2 , with the second flow path F 2  flowing to the distal region and the first flow path F 1  flowing through the terminal end  446 . 
     In another preferred embodiment shown in FIGS. 12 and 13, a curvilinear vane  580  is positioned within the burner tube  530 , preferably in the union region  548 . The vane  580  is a curvilinear structure adapted to alter the fuel flow in the union region  548 . The vane  580  has a leading edge  580   a  and a trailing edge  580   b . As shown in FIG. 13, the leading edge  580   a  is positioned in the union region  548  downstream of the leading edge  566   a  of the aperture  566 . The trailing edge  580   b  is positioned adjacent the trailing edge  566   b  of the aperture  566 . Referring to FIG. 12, the height of the vane  580  is approximately one-half of the diameter of the burner tube  530 . However, the height of the vane  580  can vary such that the vane  580  occupies a greater or lesser amount of the union region  548 . 
     In the first position P 1 , fuel F flows from the fuel source through the proximal segment  542  of the burner tube  530  and into the union region  548 . Flow separation occurs at the leading edge  580   a  of the vane  580 , where the leading edge  580   a  is the separation point. As indicated by the streamlines of FIG. 13, the initial flow path F is separated into two distinct flow paths F 1 , F 2 . The second flow path F 2  flows along and past an outer surface  580   c  of the vane  580  and downstream to the distal region (not shown) of the burner tube  530 . Because the terminal end  546  is in fluid communication with the union region  548 , the first path F 1  flows along and past an inner surface of the vane  580  and downstream into the terminal end  546 . Described in different terms, the vane  580  causes a flow disturbance in the union region  548  which alters the initial flow path F into the first and second flow paths F 1 , F 2 , with the second flow path F 2  flowing to the distal region and the first flow path F 1  flowing through the terminal end  546 . 
     In another preferred embodiment shown in FIGS. 14 and 15, a valve  680  is positioned within the burner tube  630 , preferably in the union region  648 . The valve  680  is moveable between a closed position wherein fuel F is prevented from flowing past the union region  648 , and an open position wherein fuel F is able to flow past the union region  648 . Preferably, the valve  680  is spring-loaded such that the valve  680  is in the closed position when fuel F is not flowing to the burner tube  630 . Once fuel F is supplied to the burner tube  630 , the valve  680  moves to the open position, thereby allowing fuel F to flow past the union region  748  and downstream to the distal region and the terminal end  646 . The precise position of the valve  680 , meaning degree of opening, can vary with the spring constant used in the valve  680 . 
     In the first position P 1  and when the valve  680  is in the open position, fuel F flows from the fuel source through the proximal segment  642  of the burner tube  630  and into the union region  648 . As indicated by the streamlines of FIG. 15, the initial flow path F is separated into two distinct flow paths F 1 , F 2 . The second flow path F 2  flows around the valve  680 , including the leading and trailing edges  680   a,b  of the valve  680 , and downstream to the distal region (not shown) of the burner tube  630 . Because the terminal end  646  is in fluid communication with the union region  648 , the first flow path F 1  flows downstream into the terminal end  646 . Described in different terms, the valve  680  causes a flow disturbance in the union region  648  which alters the initial flow path F into the first and second flow paths F 1 , F 2 , with the second flow path F 2  flowing to the distal region and the first flow path F 1  flowing through the terminal end  646 . 
     In another preferred embodiment shown in FIG. 16, the burner tube  730  generally comprises a first end  742  and a second end  746  in fluid connection to a union region  748 . The fluid connection between the second end  746  and the union region  748  forms the continuous burner tube or burner loop  730 . Thus, the union region  748  defines an interface zone between the second end  746  and the burner tube  730 . Described in a different manner, the union region  748  is a junction zone between the second end  746  and the burner tube  730 . Due to the connection between the second end  746  and the union region  748 , the burner tube  730  defines an enclosed central region  749 . The first end  742  has an inlet port  750  that is adapted to be connected to a control valve of a fuel source, i.e., a fuel tank. In this manner, the first end  742  is adapted to facilitate the transfer of fuel from the fuel source to the burner tube  730 . A venturi element  752  is positioned adjacent the inlet port  750 . 
     The union region  748  is a generally linear segment that is downstream from the first end  742 . The union region  748  is bounded by the first burner position BP 1  and the second burner position BP 2 . Adjacent to the union region  748  is the first linear segment  754 , which is bounded by the second burner position BP 2  and the third burner position BP 3 . A first curvilinear segment or elbow  756  is adjacent to the first linear segment  754 . The first curvilinear segment  756  is bounded by the third burner position BP 3  and the fourth burner position BP 4 . Adjacent to the first curvilinear segment  756  is a first transition segment  758 , which is bounded by the fourth burner position BP 4  and the fifth burner position BP 5 . The first transition segment  758  includes a bracket  760  adapted to support the burner tube  730  within the firebox  18 . Preferably, the bracket  760  is welded to the burner tube  730 . 
     A second curvilinear segment  762  is adjacent to the first transition segment  758 . The second curvilinear segment  762  is bounded by the fifth burner position BP 5  and the sixth burner position BP 6 . Adjacent to the second curvilinear segment  762  is a second linear segment  764 , which is bounded by the sixth burner position BP 6  and the seventh burner position BP 7 . A third curvilinear segment  766  is adjacent to the second linear segment  764 . The third curvilinear segment  766  is bounded by the seventh burner position BP 7  and the eighth burner position BP 8 . Adjacent to the third curvilinear segment  766  is a second transition segment  768 , which is bounded by the eighth burner position BP 8  and the ninth burner position BP 9 . The second end  746  is adjacent to the second transition segment  768  and is bounded by the ninth burner position BP 9  and the union region  748 . A plurality of outlet ports  770  are spaced along the burner tube  730 . As shown in FIG. 6, the outlet ports  770  begin in the union region  748  and continue downstream throughout the burner tube  730 . The radius of curvature of the curvilinear segments  756 ,  762 ,  766  can vary with the design parameters of the burner tube  730 ; however, the curvilinear segments  756 ,  762 ,  766  must be configured to permit the second end  746  to be in fluid communication with the union region  748 . 
     Because the second end  746  is connected to the union region  748  to form a continuous burner tube  730 , fuel from the fuel source can flow in two distinct paths. These flow paths result from the second end  746  being in fluid communication with the union region  748 . In contrast, conventional burners have a single flow path which begins at the inlet and continues through the burner to the terminal end, which is closed or crimped. As shown in FIG. 16, a first fuel portion, as indicated by flow path F 1 , flows past the union region  748  and downstream to the first linear segment  754 . An amount of this first flow path F 1  exits the ports  770  in the first linear segment  754 , while a remaining quantity flows downstream to the first curvilinear segment  756 . An amount of this remaining first flow path F 1  exits the ports  770  in the first curvilinear segment  756  and a remaining quantity flows downstream to the first transition segment  758 . An amount of this remaining first flow path F 1  exits the ports  770  in the first transition segment  758  and a remaining quantity flows downstream to the second curvilinear segment  762 . An amount of this remaining first flow path F 1  exits the ports  770  in the second curvilinear segment  762  and a remaining quantity flows downstream to the second linear segment  764 . This flow path continues until all of the first flow path F 1  exits the ports  266 . 
     The second fuel portion, as indicated by flow path F 2 , flows past the union region  748  and downstream into the second end  746 . An amount of the second flow path F 2  exits the ports  770  in the second end  746  and a remaining quantity flows downstream to the second transition segment  768 . An amount of this remaining second flow path F 2  exits the ports  770  in the second transition segment  768  and a remaining quantity flows downstream to the third curvilinear segment  766 . An amount of this remaining second flow path F 2  exits the ports  770  in the third curvilinear segment  766  and a remaining quantity flows downstream to the second linear segment  764 . This flow path continues until a portion of the first flow path F 1  converges and/or mixes with a portion of the second flow path F 2 . For example, the remnants of the first flow path F 1  can combine with the remnants of the second flow path F 2  within the third curvilinear segment  766 . The point at which the first and second flow paths F 1 , F 2  converge depends upon a number of factors, including but not limited to the flow rate of the fuel and the configuration and dimensions of the burner tube  730 . 
     In another preferred embodiment (not shown), the continuous burner tube has a generally “B-shaped” configuration. The burner tube has a lengthened proximal segment which accommodates the connection of a primary burner tube and a secondary burner tube. Consistent with the above disclosure, the distal end of the primary burner tube is in fluid communication with a first union region of the proximal segment. The secondary tube is generally “C-shaped” with a first and a second end. The first end of the secondary tube is in fluid communication with a second union region, and the second end of the secondary tube is in fluid communication with a third union region. 
     Due to the three junctions at the union regions, the B-shaped burner tube has multi-directional passageways. Accordingly, fuel from the fuel source can flow in multiple directions throughout the continuous burner tube and as a result, the flame area emanating from the burner tube is increased. 
     The present invention provides a novel method for distributing fuel through a continuous burner tube. Referring to FIG. 2, the proximal segment  42  is connected to a fuel source. Fuel enters the burner tube  30  at the inlet port  52 . A regulator (not shown) is utilized between the fuel source and the proximal segment  42  to regulate and/or modulate the flow of fuel. Preferably, a manifold is not required. The fuel forms an initial flow path F and flows downstream through the venturi element  54  and into the union region  48  of the proximal segment. As shown in FIGS. 4,  8 , and  10  and due to the fluid connection between the union region  48  and the terminal end  46 , separation of the initial flow path F occurs in the union region  48  with the formation of a first flow path F 1  and a second flow path F 2 . The first flow path F 1  flows past the union region  48  and downstream to the distal region  44 . The second flow path F 2  flows past the union region  48  and downstream to the terminal end  46 . As a result, two distinct flow paths F 1 , F 2  are formed to distribute fuel throughout the burner tube  30 . Fuel from each flow path F 1 , F 2  is combusted upon exiting the outlet ports  60 . The burner tube  30  has a burner flame area, which is the collective measure of the flames exiting the plurality of outlet ports  60 . Due to the multi-directional configuration of the continuous burner tube  30 , the flame area is enlarged to match the geometry of the firebox  18 , thereby increasing the efficiency and effectiveness of the burner tube  30 . 
     Preferably, at some point downstream of the union region  48 , the first and second flow paths F 1 , F 2  converge. The precise location of the convergence depends upon a number of factors, including but not limited to the flow rate of the fuel and the configuration of the burner tube  30 . 
     The burner tube of the present invention provides a number of significant advantages over conventional burners. First, the connection between the terminal end and the union region forms a continuous burner tube having a multi-directional passageway for the flow of fuel. This allows for multiple flow paths of fuel throughout the burner tube, which in turn increases fuel distribution throughout the burner tube. Also, the burner tube has only one inlet valve, which permits a direct connection to the fuel source without the need of a manifold. This reduces the material costs and eases the assembly of the grill assembly having the burner tube. In addition, the continuous burner tube forms an enlarged flame area with a geometry that is similar to the interior geometry of the firebox resulting in uniform heat distribution to the grate positioned in the firebox. This reduces the need for multiple burner tubes in the firebox. Third, due to the curvilinear segments and the resulting biasing, the terminal end is connected to the union region without the use of a fastener. This reduces the assembly process and as a result, the material and labor costs are reduced. 
     Another benefit of the present invention relates to shipping and packaging concerns of the burner tube and the barbecue grill assembly. Unlike conventional burners, the burner tube of the present invention is easily and fully assembled by connecting the terminal end to the union region. Consequently, the burner tube can be packaged and shipped fully assembled generally eliminating further assembly by the end user or the retailer. 
     While the specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention and the scope of protection is only limited by the scope of the accompanying claims.