Portable gas torch

Abstract

A portable gas torch has a metal burner tube defining a gas flow passage through which gas is adapted to flow. An igniter wire in the gas flow passage generates a spark to ignite gas flowing through the passage. The torch has a wire holder for positioning the igniter wire in the gas flow passage and a flame holder downstream from the wire holder. The wire holder comprises a central hub having an axial bore and at least one spacer on the hub for contacting an inside wall of the burner tube to position the hub at a predetermined radial location in the gas flow passage. The axial bore is sized to enable the wire to be held at a selected location downstream from the hub. The wire holder comprises a dielectric material to allow a spark to jump to the inside wall of the burner tube.

What is claimed is:  
     
         1 . A portable gas torch comprising 
 a metal burner tube defining a gas flow passage through which gas is adapted to flow along a longitudinal axis of the tube to an outlet,    an igniter wire in the gas flow passage having a spark end for generating a spark to ignite gas flowing through the passage,    a wire holder for positioning the igniter wire in the gas flow passage, and    a flame holder in the gas flow passage downstream from the wire holder,    said wire holder comprising a central hub having an axial bore generally parallel to the longitudinal axis of the burner tube and at least one spacer on the hub for contacting an inside wall of the burner tube to position the hub at a predetermined radial location in the gas flow passage,    said axial bore being sized to enable the spark end of the wire to be inserted through the bore and then held at a selected location downstream from the hub,    said wire holder comprising a dielectric material whereby a spark from the spark end of the igniter wire will jump to the inside wall of the burner tube even if the spark end is positioned closer to wire holder than to the inside wall of the tube.    
     
     
         2 . A portable gas torch as set forth in  claim 1  wherein said burner tube is formed from a single piece of metal tubing from a position corresponding to the wire holder to the outlet of the tube.  
     
     
         3 . A portable gas torch as set forth in  claim 2  wherein said burner tube has substantially uniform flow area for the flow of gas from the torch.  
     
     
         4 . A portable gas torch as set forth in  claim 3  wherein said burner tube is made from stainless steel.  
     
     
         5 . A portable gas torch as set forth in  claim 1  wherein said axial bore of the hub is generally coincident with the longitudinal axis of the burner tube.  
     
     
         6 . A portable gas torch as set forth in  claim 1  wherein said axial bore of the hub is sized for gripping the wire and holding it in said selected position.  
     
     
         7 . A portable gas torch as set forth in  claim 6  wherein said axial bore of the hub has an inlet section having a first diameter and a downstream section having a second diameter.  
     
     
         8 . A portable gas torch as set forth in  claim 7  wherein said first diameter ranges from approximately 0.04 to 0.08 inches and said second diameter ranges from approximately 0.02 to 0.07 inches.  
     
     
         9 . A portable gas torch as set forth in  claim 1  wherein said at least one spacer has a rounded upstream end surface, a generally planar downstream end surface, and generally parallel side faces extending axially between the upstream and downstream end surfaces.  
     
     
         10 . A portable gas torch as set forth in  claim 1  wherein said wire holder comprises a plurality of spacers extending radially from the hub.  
     
     
         11 . A portable gas torch as set forth in  claim 10  wherein said plurality of spacers comprises a first spacer and a second spacer located approximately 180 degrees from the first spacer.  
     
     
         12 . A portable gas torch as set forth in  claim 10  wherein said plurality of spacers comprises a first spacer, a second spacer located approximately 120 degrees from the first spacer, and a third spacer located approximately 120 degrees from the second spacer.  
     
     
         13 . A portable gas torch as set forth in  claim 1  wherein said wire holder dielectric material comprises ceramic.  
     
     
         14 . A portable gas torch as set forth in  claim 1  wherein said hub and said at least one spacer are formed as a single molded part.  
     
     
         15 . A portable gas torch as set forth in  claim 14  wherein said wire holder dielectric material comprises a thermoplastic material.  
     
     
         16 . A portable gas torch as set forth in  claim 1  wherein said igniter wire extends beyond the wire holder a distance ranging from approximately 0.01 to approximately 0.08 inches.  
     
     
         17 . A portable gas torch as set forth in  claim 16  wherein the spark end of the igniter wire is spaced in from the inside wall of the burner tube approximately 1 to 6 mm.  
     
     
         18 . A portable gas torch as set forth in  claim 1  wherein said flame holder is spaced approximately {fraction (1/4)} inch downstream from the spark end of the igniter wire.  
     
     
         19 . A portable gas torch comprising 
 a burner tube defining a gas flow passage through which gas is adapted to flow along a longitudinal axis of the tube, said tube having an open end defining an outlet of the torch,    an igniter wire in the gas flow passage having a spark end for generating a spark to ignite gas flowing through the passage,    a dielectric wire holder in the burner tube for receiving the igniter wire and positioning the spark end in the gas flow passage, and    a flame holder in the gas flow passage downstream from the wire holder,    said wire holder comprising a central hub having an axial bore generally parallel to the longitudinal axis of the burner tube and a plurality of spacers extending from the hub for contacting an inside wall of the burner tube to position the hub at a predetermined radial location in the gas flow passage.    said axial bore being sized to hold said igniter wire in place by an interference fit such that the spark end of the igniter wire is held a substantially fixed distance downstream from the hub whereby a spark from the spark end of the igniter wire will jump to the inside wall of the burner tube even if the spark end is positioned closer to wire holder than to the inside wall of the tube.    
     
     
         20 . A portable gas torch as set forth in  claim 19  wherein said plurality of spacers comprises a first spacer and a second spacer located approximately 180 degrees from the first spacer.  
     
     
         21 . A portable gas torch as set forth in  claim 19  wherein said plurality of spacers comprises a first spacer, a second spacer located approximately 120 degrees from the first spacer, and a third spacer located approximately 120 degrees from the second spacer.  
     
     
         22 . A portable gas torch as set forth in  claim 19  wherein said substantially fixed distance is between approximately 0.01 and approximately 0.08 inches.  
     
     
         23 . A portable gas torch as set forth in  claim 19  wherein the spark end of the igniter wire is spaced in from the inside wall of the burner tube by approximately 1 to 6 mm.  
     
     
         24 . A portable gas torch as set forth in  claim 19  wherein said wire holder dielectric material comprises ceramic.  
     
     
         25 . A portable gas torch as set forth in  claim 19  wherein said hub and said at least one spacer are formed as a single molded part.  
     
     
         26 . A portable gas torch as set forth in  claim 25  wherein said wire holder dielectric material comprises a thermoplastic material.