US2270826A - Blowtorch - Google Patents

Description

Jan. 20, 1942. S. E. PETERS 2,270,826

BLOWTORCH Filed Sept. 22, 1939 Patented Jan. 20, 1942 UNITED STATESMPATENT OFFICE BLOWTORCH Stanley Earle Peters, Chicago, 111., assignor to Henry Baumgarth Application September 22, 1939, Serial No. 296,035

3 Claims. 158-33) This invention relates to improvements in blow torches.

In blow torches using gasoline or similar liquid fuel, pumps generally are used to provide air pressure in the tanks by means of which atomized fuel is delivered to the burner head. Excessive air pressure bursts the tanks and since the air forced into the tanks mixes with fuel and makes an explosive mixture within the tanks, serious explosions with torches of that type are relatively common.

In my Patent No. 2,155,238 granted April 18, 1939. a torch structure is disclosed which, in lieu of a conventional air 'pump for supplying air pressure to the tank for fuel feeding purposes, is capable of generating the required pressure by vaporization of the fuel in the tank whereby the danger accompanying the presence of an explosive mixture under pressure in the tank has been avoided. The present invention relates to improvements in torches of the type disclosed in said patent.

One object of the invention is to provide a tank structure which is reinforced to withstand the internal pressures to which it may be subjected in use, which reinforcement functions in facilitating the conduction of heat to the fuel in the tank for vaporization of the latter to build up an adequate working pressure.

Another object of the invention is to provide an improved burner head and valve structure which insures the maintenance of a flame within the flame tube of the head and thereby provides adequate heat for conduction to the tank for the generation of a proper quantity of gaseous fuel and working pressure within the tank, but a head which prevents the dangerous rearward projection of flame or gaseous fuel through the valve structure in the event the valve stem is inadvertently unscrewed too far during use of the torch. For the purpose of preventing a valve stem being retracted until the external threads of the stem and the internal threads of the valve chamber are disengaged, thereby releasing the valve stem and enabling the gaseous fuel to be projected rearwardly toward the operator, some blow torches have been provided with stops or lugs which are intended to limit the rearward threaded movement of the valve stem beyond the point where the valve is in maximum open position. Since such limiting means become effective while the threads of the stem are in engagement with the threads of the valve chamber of the head, operators, possibly believing that the threads merely were tight or sticking, not infrequently have turned the stem with sufficient force to damage the threads or to shear ofithe stops or lugs and thus release the valve stem with resultant injury to themselves in addition to creating a fire hazard. In the present invention means are provided which effectively prevent such occurrences since the structure is such that the valve stem may be turned rearwardly until the threads are disengaged, and

the stem is freely rotatable but is not removable from a position wherein it prevents back firing without first removing a surrounding gland nut.

Other objects relate to various features of construction and arrangement of parts such as :the provision of means which prevents the satistaken axially through the torch head and valve assembly;

Fig. 3 is an enlarged sectional view taken on line 3-3 of Fig. 2;

Fig. 4 is a broken top plan view of a forward 0.5 end of the flame tube or head with a flame spreader in position thereon; and

Fig. 5 is a sectional view taken on line 5-5 of Fig. 4.

As shown in Fig. 1, the blow torch comprises 5 a tank indicated generally by the numeral H! having upper and lower walls II and I2, respectively, connected by a reinforcing or strengthening member l3; preferably of tubular form. The

member I3 is shown as extending downwardly through the top wall H to the bottom wall [2 and is welded to each of the walls, whereby it resists outward deflection of said walls from pressure within the tank. The member I3 is provided with upper openings l3a and lower openings 132) which provide communication between the interior of the tank and the interior of the member l3. The upper end of the tube I3 is threaded internally for threadedly 0 receiving the nipple Ma of the torch head, which is indicated generally by the numeral M. The head I4, as shown in Fig. 2, is provided with a combustion and mixing chamber l5 and a shank IS with which the threaded nipple Ma. is integral. The head I4 is provided with a fuel passage by means of which fuel in gaseous form is conveyed from the tank to the flame tube, such passage comprising a bore H in the member |6, a horizontal bore 18, and a vertical bore l9. Communicating with the bore I9 is a valve chamber 2|! provided with a valve seat 2| and a valve assembly indicated generally by the numeral 22, by means of which the flow of fuel from the fuel passage to the flame tube can be controlled. The assembly 22 comprises a valve stem 23, which at its forward end carries a needle closure member 24. The valve stem has a threaded section 25 adapted to cooperate with a threaded section 26 of the valve chamber whereby turning the valve stem by means of the handle 21 in one direction or the other will cause the needle to move toward or away from the seat 2|. The valve seat and the needle preferably are of the type shown and described in my patent above referred to.

Projecting rearwardly from the head I4 is an externally threaded nipple 28 through which the valve stem extends, as shown in Fig. 2. A gland nut 29 engages the nipple 28, as shown in said figure, and clamp between the rear or right hand end of the nut as viewed in Fig. 2 and the end of the nipple, a sleeve 3|), through which the stem 23 passes. The stem is movable within, the sleeve 35, although it is desirable that the internal diameter of the sleeve be such as to rather closely fit the stem. Extending as a chord across the sleeve 30, as shown in Figs. 2 and 3, is a stop member 3|, which may be in the form of a pin of strong material, such as piano wire, for example. As shown in Fig. 2, the member 3| is located Within a circumferential slot 32 formed in the stem 23. The slot 32 and the pin 3| are so located in the assembly as to enable the valve stem to be retracted by turning the same in the proper direction until the threaded portion 25 thereof is disengaged from the internal threads 25 of the valve chamber. When the valve stem has been so retracted, the left hand wall 321]. of the groove 32 will be in abutting relation with the stop member 3| as indicated by the dotted line in Fig. 2.

It will be seen, therefore, that the valve stem, when in this position, may be freely rotated since the threads 25 and 26 are disengaged, but that the valve stem may not be slid to the right as viewed in Fig. 2 from the assembly. The relation of the member 3| to the slot 32 is such that the stern may be rotated in the usual manner for effecting the proper opening and closing of the valve for regulating the supply of fuel to the flame tube. However, should an operator of the improved torch inadvertently turn the valve stem rearwardly sufficiently to effect disengagement of the threads 25 and 26, the stem is still held in position by the co-action of the member 3| with the wall 32a of the slot to prevent withdrawal of the stem and thus providing a passage through which fuel may be projected toward him. Since the stem 23 preferably fits closely the bore of the sleeve 30, no appreciable amount of fuel, if

any at all, can escape rearwardly along the stem when the latter has been retracted to the position where the threads 25 and 26 are disengaged. In

this position, further rotation of the stem in a direction to retract the same is ineffectual and such movement does not damage the threads.

Located in the chamber I is a fuel dispersing member 33, preferably provided with annular fins 33a. This member 33 may be formed integral with the head, or, if desired, it may be in the form of a suitable screw inserted in the flame tube in the position shown in Fig. 2. When the valve has been opened to admit fuel into the chamber |5, a fine stream of vaporized fuel issues through the relatively small passage of the valve seat 2| and strikes the dispersing member 33 and causes it to mix with air in the chamber l5 which is admitted through suitable openings 34. Combustion takes place at a point forwardly of the member 33, that is, within the chamber I5, and thus heats the head, whereby conduction of heat from the latter through the shank IE to the top wall II and member |3 will cause vaporization of the fuel within the tank and build up suitable working pressure therein.

example, which will prevent passage of foreign matter from the tank into the valve passage, and to the valve to impair the operation of the torch. The fuel in passing from the tank to the head must first pass into the tube 35 either through the port 35a or the lower open end of the tube.

In operating the torch, the head is turned in a direction to unscrew the nipple I ia from the threads of the upper end of the tube I3, and fuel, such as gasoline, is poured into the tank to fill the same as much as possible to expel air therefrom. The head is then returned to proper position on the tank and additional fuel such as gasoline is poured into the priming cup 31 which is formed by welding a ring to the upper end ll of the tank. The fuel in the priming cup 31 is ignited, which heats not only the head M, including the shank IE, but also the tank itself, including the tube l3. The fuel in the tank is vaporized and passes into the tube 35 as through ports 35a, through the fuel passages and the valve when open, and into the mixing and com bustion chamber |5, where it is ignited by a match, for example. Since a portion of the flame is maintained within the chamber |5, sufficient heat is conducted to the tank to effect continued vaporization of the fuel and maintenance of a suitable working pressure after the priming fuel in the cup 3'| has been exhausted. If the torch should be inverted in use, vaporized fuel can pass into the tube 35 from the lower open end thereof due to the fact that in such position such lower end will be uncovered by the liquid fuel.

It will be seen that due to the practical exclusion of the air from the tank, the vapor which issues from the valve contains insufiicient oxygen to support combustion and hence the tank at no time contains an explosive mixture during normal operation. The air ports 33, however, admit sufiicient air into the head for admixture with the fuel issuing from the valve to provide a combustible mixture at or adjacent the member 33. Should the head M be removed from a partially filled tank by a workman for the purpose of determining the amount of liquid fuel in the latter and thereafter the head be returned to proper position without adding fuel, air will be present inthe tank. As a safety measure any substantial quantity of air should not be present in the tank during use of the torch since an explosive mixture will be formed therein by the admixture of the air with the fuel vapor. Hence the air ports 34 in the head are calculated to admit sufficient air to the vaporized fuel as it passes along the combustion chamber l so as to maintain a flame in the forward portion of the chamber. However, if in starting the torch, there is a substantial quantity of air in the tank, it will mix with the initially generated vapor and this mixture will mix with additional air in the chamber IS with the result that when a match is applied to the lean gas issuing from the head, the flame will not be sustained until the air in the tank has been exhausted. Hence until the dangerous condition created by the presence of excess air in the tank has been corrected, the torch operates either not at all or the flame may flutter for a few seconds and then be extinguished. However, upon the exhaustion of the air from the tank and the proper generation of vapor by the heat conducted thereto, the flame will be steady, ignition taking place adjacent the member 33 as above stated.

As mentioned above the member 23 establishes a definite ignition point or region within the chamber I5 which is important in that the maintenance of a flame within the head is necessary in establishing a proper correlation between the working pressure within the tank and size of the flame or the rate of fuel consumption. If the member 33 or some equivalent vapor dispersing or mixing member for the air and vapor were not employed in the head and the valve were widely opened and the pressure of the vapor in the tank were high, the velocity of the fuel through the chamber l5 might be sufficient to prevent adequate mixture of air and vapor within the chamber so that combustion, instead of occurring within the head, would take place at a point beyond the end of the nozzle, as frequently occurs in torches of the air pump type. Under such circumstances the head would lose its heat and generation of vapor within the tank would be reduced and the torch prevented from operating at its maximum capacity. By utilizing the air dispersing or mixing member 33 to establish a zone (immediately to the left of said member as viewed in Fig. 2) wherein sufilcient mixture of the vapor fuel with air occurs to support combustion within the head, the torch operates satisfactorily at maximum or reduced capacity since the quantity of heat absorbed by the head from the flame therein (and consequently'the quantity of heat conducted to the tank for generating vapor) increases or decreases with increase or decrease respectively in the rate of fuel consumption. The member 33 thus is effective in establishing a suitable balance between the rate of fuel generation and the rate of fuel consumption, that is, in maintaining adequate but not excessive pressures within the tank.

As is known, commercial gasoline is formed of various fractions which vaporize or distil off at different temperatures. For the purpose of reducing undesirable fluctuations in the operation of the torch that would occur should the more volatile portions of the gasoline in the tank be first consumed, leaving the remaining less volatile fuel in the cooler bottom portion of the tank, means are provided for causing some of the latter portions of the fuel in liquid form to be carried through the tube 35 and to be atomized and mixed with lighter volatilized portions which have passed into the tube through the port 35a. For accomplishing this result, the tube 35 is closed at its upper end except for the provision of a small port 352), as shown in Fig. 1. Volatilized fuel which is generated by the conduction of heat from the head to the tank passes through port 35a into tube 35 and thence through the port 35b into the fuel passage section IT. The flow of vapor through port 35a has an aspirating or entraining effect upon the liquid fuel in the tubeand carries the aspirated fuel upwardly and through the port 35?), thus atomizing it as it is discharged into the hot interior passage of the shank l6 where it is volatilized by the heat and mixed with the lighter gases. Since the lower end of the tube 35 is open, liquid fuel flows readily from the lower portion of the tank into the tube to replace the fuel that is removed. The mixture thus formed is delivered to the combustion chamber for admixture with air as above described. By this arrangement there is provided a gaseous fuel of relatively uniform combustion characteristics, the components of which are the lighter readily volatilized fractions of the gasoline and the heavier or less readily volatilized portions thereof, which results in less spluttering and a more uniform flame than would be the case were the various fractions of fuel consumed in the order of their volatility.

It will be noted that the tank is provided with a handle 38 secured to a compressible split ring 39 which is adapted to be clamped as by means of a screw 4|] around the priming cup 31. By loosening the screw 40, the handle can be adjusted to different angular positions with reference to the axis of the head and valve stem, whereby the torch is self-supporting in angular position, that is, it may rest upon the handle 21, the end of the handle 38, and a portion of the base of the tank in a manner similar to that shown in the above mentioned patent.

Figs. 4 and 5 illustrate a flame spreader which may be used with the improved torch, comprising a casting 4| having a relatively wide nozzle 42 through which flame from the forward end of the flame tube may be projected. Such a flame spreader is useful for example in removing paint from old Woodwork. The member 4| is provided with a bayonet slot 43 in a cylindrical shank portion 44 whereby the member 4| can be readily assembled on the forward end of the flame tube, the bayonet slot accommodating a lug 45 cast integral with the head.

While I have shown and described a certain embodiment of my improvement for the purpose of illustration, it is apparent that various changes may be made therein without departing from the spirit of the invention.

I claim:

1. A blow torch comprising a tank for liquid fuel, a head provided with a combustion chamber and being heat conductively connected with said tank whereby heat from the head is conducted to said tank for vaporizing fuel therein, said head having a fuel passage for conducting vaporized fuel from the tank to the head, and aspirating means for elevating liquid fuel from the tank and effecting the atomization thereof and the admixture of the atomized fuel with vaporized fuel in said passage, said means comprising a ported tube extending from said passage into said tank to a point below the normal level of liquid fuel therein and provided with a constricted port at the upper end and a vapor port located above the normal level of the fuel therein.

2. A blow torch adapted for burning liquid fuel having fractions which distil off at different temperatures, comprising a tank for such liquid fuel, a burner head heat conductively associated with a tank for effecting the vaporizationof fuel in the tank, and provided with a fuel passage for conducting vaporized fuel to the head, and means comprising a tube extending from said passage into the liquid in the tank and provided with a liquid intake below the normal level of liquid in the tank and provided also with a vapor port above the level of liquid in the tank for effecting the elevation of liquid fuel through said tube, and a constricted port at the upper end through which the vapor and entrained liquid fuel flow for effecting atomization of the latter and admixture therewith of the vaporized fuel in said passage.

3. A blow torch comprising a fuel tank for vaporizable fuel, a head on the tank heat conductively connected therewith and provided with a flame chamber therein, said chamber being open at one end and being provided with a fuel admission port at the other end, a passage in the head for conducting vaporized fuel from the tank to said port, air apertures in said head for admitting air into said chamber, and a member in said chamber located intermediate the ends thereof and in the path of vapor entering the same through said port for dispersing the vapor stream and effecting a mixing of air and vapor to provide a combustible mixture and thereby establishing an ignition zone in the portion of the chamber at the side of said member remote from the fuel port.

STANLEY EARLE PETERS.

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