Patent Publication Number: US-2011053103-A1

Title: Torch

Description:
This application claims benefit of priority under 35 U.S.C. §119(e) to the filing date of to U.S. Provisional Application No. 61/236,720, as filed on Aug. 28, 2009, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     The invention relates to torches and lighters such as propane, butane, mixed gas or MAPP fueled torches and butane lighters that use a source of fuel that may be ignited by a spark (collectively a “torch”). Self-igniting torches generate the spark using, for example, a piezoelectric igniter. Self-igniting torches and lighters typically include a trigger or push button ignition that when depressed activates the igniter to create a spark that ignites the fuel in the burn tube. Activation of the trigger may also release a flow of fuel under pressure into a burn tube or the release of fuel may be controlled by a separate control. The ignited fuel creates a flame at the end of the burn tube that can be used in a variety of heating/lighting applications. Such torches may be used for heating, brazing, welding and the like and for lighting a fire. 
     SUMMARY OF THE INVENTION 
     A torch and a burn tube for a torch are provided. The torch comprises a burn tube having a first end having an orifice through which a flame is discharged and a second end remote from the first end and secured to a torch body for receiving a supply of fuel. The burn tube is one-piece from the first end to the second end. The burn tube has an enlarged or expanded portion located adjacent to the first end and a flame guide located entirely inside of the burn tube in or adjacent to the expanded portion. 
     The torch may include a valve for controlling the flow of fuel to the burn tube and a control for controlling the valve. The torch may also include an igniter for igniting the fuel in the burn tube such as a piezoelectric igniter. A trigger may be movably supported by the torch body to actuate the igniter. Conductors are provided for generating a spark in the burn tube adjacent the flame guide. 
     The burn tube may be stainless steel and the flame guide may be brass. The flame guide may be point staked to the burn tube. The flame guide may be positioned either in the non-expanded portion of the burn tube adjacent the expanded end or in the expanded end located adjacent the non-expanded portion of the burn tube. 
     A method of making a torch is also provided comprising forming a one-piece burn tube having a first diameter, a first end and a second end. A burn tip is formed in the burn tube by expanding the first end of the burn tube. A flame guide is located entirely within the burn tube adjacent the first end. The flame guide is secured to the burn tube such as by point staking. The first end of the burn tube may be crimped. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of one embodiment of a torch. 
         FIG. 2  is a side view of the torch of  FIG. 1  with a portion of the torch body removed to show the internal components of the torch. 
         FIG. 3  is an exploded view of the internal structure of one embodiment of a torch of the invention. 
         FIG. 4  is a perspective section view of an embodiment of the burn tube. 
         FIG. 5  is a perspective section view of another embodiment of the burn tube. 
         FIG. 6   a  through  6   e  illustrates the process of forming the burn tube. 
         FIG. 7  is a block diagram illustrating an embodiment of a method of making the burn tube and torch. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     A typical torch consists of a fuel source such as butane, propane, mixed gas, MAPP gas or other fuel held under pressure in a fuel container. The fuel container may be a tank or canister releasably connected to the torch body such that the fuel supply can be removed when empty and replaced. The fuel supply is connected to a fuel supply system that transports the fuel to a burn tube where it is ignited. In simpler and less expensive devices the fuel container, burn tube and fuel supply system may form part of an integrated device that may be disposed of after the fuel is depleted or the fuel container may be refilled. 
     An example embodiment of a torch is shown in the  FIGS. 1 ,  2  and  3  and comprises a torch body  1  made of plastic or other similar material. The torch body  1  may be made of two portions  1   a  and  1   b  joined together to create the finished body with the burn tube  6  trapped between the body portions and secured to the body  1 . Gas such as propane or propylene (other fuels such as mixed gas, MAPP fuel, butane or the like may also be used) is delivered from a canister (not shown) that is secured to the body in open area  2 . The fuel canister is connected to a coupler  4  such that an empty canister can be removed and replaced with a full canister. The fuel canister may be formed with screw threads or other releasable connector to connect the canister&#39;s inlet/outlet port to a mating connector on the coupler  4 . 
     A typical fuel supply system for a torch may include a regulator for regulating the pressure of the fuel entering the fuel supply system; however, a regulator may not be required. In the illustrated embodiment the regulator is built into the gas valve assembly  14 . The regulator may include a spring loaded diaphragm or piston, or other device that provides a flow of fuel under a constant pressure to avoid pressure variations that may occur due to variations in temperature, elevation or the like. 
     A fuel supply line  12  connects the coupler  4  to a gas valve assembly  14  such that the fuel is delivered via line  12  to the input port of the gas valve  14 . The output port of the gas valve  14  is connected to an orifice  17  that delivers the fuel under pressure to one end of the burn tube  6 . Apertures  18  are formed in the burn tube  6  adjacent orifice  17  such that air can be drawn into the burn tube and mixed with the fuel. A Venturi  20  may be provided in the burn tube to effectuate the mixing of the fuel and air. A manually actuated trigger  16  is used to open or close the gas valve  14  and control the flow of fuel to the burn tube  6 . When trigger  26  is depressed, trigger  26  opens valve  14  to allow the fuel to flow into burn tube  6 . A control knob  15  can be manipulated to control the size/heat of the flame generated by the torch. 
     To ignite the fuel and create a flame, trigger  16  actuates piezoelectric igniter  28  when the trigger is depressed such that a spark is created in the burn tube  6  to ignite the gas flowing through the burn tube. In the illustrated embodiment the igniter  28  is held in a chamber  16   a  formed in the trigger  16  such that the igniter  28  moves when the trigger is depressed. When the trigger  16  is depressed the igniter  28  is compressed between the end of chamber  16   a  and the valve stem  21  on the valve assembly  14  to depress the plunger  28   a  and actuate the igniter. The igniter  28  is actuated simultaneously or nearly simultaneously with the release of the fuel such that the flowing fuel is immediately ignited. A spring  27  returns the trigger  16  and igniter  28  to the extended position when the trigger is released. Other arrangements for actuating the igniter are also possible. A run-lock  29  that allows the torch to stay on even if the trigger is released may be provided to allow for hands-free operation of the torch. 
     To create the spark, igniter  28  has a first lead  28   b  that is connected to an electrical conductor  30 . The electrical conductor  30  may include any electrically conductive element such as an insulated wire. Conductor  30  extends through one of apertures  18  and into the burn tube  6 . The other lead of piezoelectric igniter  28  is connected to a second electrical conductor. The ends of the electrical conductors are spaced from one another such that when the igniter  28  is actuated a spark is generated between the conductors. In the present embodiment the burn tube  6  may be made of electrically conductive material and used as the second electrical conductor such that the spark is created between the end  30   a  of wire  30  and the interior surface of burn tube  6 . 
     Referring to  FIGS. 4 and 5 , to create the spark in the burn tube  6 , piezoelectric igniter  28  is actuated by depressing trigger  16 . The end  30   a  of electrical conductor  30  is positioned in burn tube  6  such that it is spaced from the burn tube a distance such that arcing occurs between the end of the conductor  30   a  and the interior surface of burn tube  6  to create a spark that ignites the fuel/air mixture flowing through the burn tube. The conductor  32  may be supported in the burn tube  6  by a support  7 . The end  30   a  of conductor  30  is located in the burn tube  6  toward the first end  6   a  of burn tube  6  such that the flame is generated near the opening  9  formed in the first end  6   a  of burn tube  6  and extends out of opening  9  a distance where it can be used for heating and lighting operations. The performance of a torch is based on the size and quality of the generated flame. Typically, a larger burn tube creates a larger flame with greater heat impact. 
     Burn tube  6  may be formed as a stainless steel tube that has an enlarged portion extending from opening  9  that forms burn tip  11 . A separate component is positioned inside the tube as the flame guide. This structure duplicates the performance of more expensive torches without adding the cost of a large brass tip connected to the end of the tube. The same performance is achieved with fewer machining operations and less expensive materials because the stainless burn tube constructed as shown and described is less expensive than a burn tube having a brass tip connected to the end of a burn tube. 
     The burn tube  6  has a one-piece construction between the first end  6   a  and the second end  6   b.  The first end  6   a  includes opening  9  through which a flame is discharged. The second end  6   b  of burn tube  6  is supported in the body  1  and receives fuel flowing from orifice  17 . In one embodiment the second end  6   b  fits over and closely engages orifice  17  such that fuel flows from orifice  17  into the second end  6   b  of burn tube  6 . The first end  6   a  of the burn tube  6  is enlarged to create burn tip  11  that extends from the opening  9  for a portion of the total length of burn tube  6 . Thus, the burn tip  11  is formed as an integral portion of the one-piece burn tube  6  having a larger diameter D than the diameter d of the remainder  13  of the burn tube  6 . The enlarged burn tip  11  may be expanded from a smaller diameter tube. The enlarged burn tip  11  may be approximately one-third of the length of the burn tube  6 . Further, the diameter D of the burn tip  11  may be expanded to be approximately 20 percent larger than the diameter d of the remainder of the burn tube. For example, a ½″ diameter (d) stainless steel burn tube  6  is expanded to have an enlarged burn tip  11  having a diameter (D) of approximately 0.600 inches where the expanded end extends for one-third of the total length of the tube  6 . 
     A flame guide/holder  32  is inserted into the burn tube  6  and is fixed into place inside of burn tube  6 . The flame guide  32  may be formed of a different material than the burn tube  6 . In one embodiment the flame guide  32  is made of brass. The flame guide  32  may be positioned either in the enlarged diameter burn tip  11  located adjacent the smaller diameter portion of the burn tube  6  as shown in  FIG. 4  or it may be positioned in the smaller diameter portion of the burn tube  6  just adjacent the enlarged diameter burn tip  11  as shown in  FIG. 5 . In either position some or all of the enlarged burn tip  11  extends beyond the flame guide/holder  32  and the flame guide/holder  32  is located downstream of the point where the spark is generated. 
     The flame guide/holder  32  is used to create a smaller, tighter flame that is more stable. The flame guide/holder  32  has a cylindrical portion  32   a  that is dimensioned to be closely received inside of burn tube  6 . The flame guide/holder is fixed within burn tube  6  in the desired position. In one embodiment the cylindrical portion  32   a  is point staked to the interior wall of the burn tube  6 . A plurality of vanes  32   b  are located in the flame guide/holder to create passages through which the flame passes. The vanes  32   b  create a vortex as the flame moves through the flame guide/holder  32  to mix the primary and secondary flames together. This mixing creates a smaller and tighter flame producing a higher heat concentration on the work piece. The mixing of the primary and secondary flames also burns the fuel more efficiently by mixing the secondary flame into the primary flame such that the secondary flame is not wasted. 
     Referring to  FIGS. 6 and 7 , to manufacture the burn tube  6 , a one-piece tube  106  is formed having a first diameter d,  FIG. 6   a  (block  601 ). In one embodiment the burn tube is formed of stainless steel. The enlarged burn tip  11  is formed by expanding the first end of the burn tube (block  602 ) using an expanding collet or tapered mandrel  107 ,  FIG. 6   b . The expanded burn tip  11  having a second larger diameter D and the remainder  13  of the burn tube are formed as an integral, one-piece element,  FIG. 6   c . The flame guide/holder  32  is inserted into the enlarged burn tip  7  (block  603 ) and fixed to the burn tube such as by point staking the flame guide to the burn tube (block  604 ),  FIG. 6   d . The end  106   a  of the burn tip may be crimped around opening  9 ,  FIG. 6   e  (block  605 ). 
     To manufacture a torch, collar  38  is fit over the second end  6   b  of the completed burn tube  6  and the second end is fit over and connected to the orifice  16  of valve assembly  14  such as by point staking (block  606 ). The coupler  4  is connected to the valve assembly  14  by fuel line  12  (block  607 ). 
     The body portions  1   a  and  1   b  are molded of plastic or formed of another rigid material (block  608 ). The valve assembly  14 , fuel line  12 , coupler  4  and burn tube  6  are mounted in one of the body portions  1   a ,  1   b  (block  609 ). The igniter is mounted in the trigger  16  and the trigger is mounted in one of the body portion  1   a ,  1   b  (block  610 ). The igniter conductor  30  is routed from igniter  28  through the burn tube with the end  30   a  of the conductor wire located adjacent the flame guide  32  (block  611 ). The body portions  1   a  and  1   b  are secured together such as by fasteners  50  trapping the components in the body  1  (block  612 ). 
     The construction of the burn tube  6  provides enhanced performance with fewer components, less expensive materials and fewer machining operations than existing torches. One measure of performance is the time it takes to solder a copper joint. A torch as described herein using a ½″ burn tube was tested and its performance was comparable to or better than torches with more expensive burn tubes of the same size made of brass and stainless steel. 
     While embodiments of the invention are disclosed herein, various changes and modifications can be made without departing from the spirit and scope of the invention as set forth in the claims. One of ordinary skill in the art will recognize that the invention has other applications in other environments. Many embodiments are possible. The following claims are in no way intended to limit the scope of the invention to the specific embodiments described above.