US3829278A

US3829278A - Gasoline stove

Info

Publication number: US3829278A
Application number: US00352948A
Authority: US
Inventors: H Penberthy
Original assignee: Individual
Current assignee: MSR ACQUISITION Co Inc A CORP OF WASH
Priority date: 1973-04-20
Filing date: 1973-04-20
Publication date: 1974-08-13
Anticipated expiration: 1991-08-13

Abstract

This invention relates to a stove for burning various hydrocarbon fuels such as gasoline, naphtha, kerosene and the like and more particularly is directed to an improved burner construction for portable stoves of this type which may be used by campers, back-packers, mountain climbers and others interested in the outdoors.

Description

United States Patent [191 Penber thy Aug. 13, 1974 GASOLINE STOVE [76] Inventor: Harvey Larry Penberthy, 5624 SW. Admiral Way, Seattle, Wash. 98116 [22] Filed: Apr. 20, 1973 [21] Appl. No.: 352,948

52 U.S. Cl. 431/2 27 [51] Int. Cl. F23d' 11/44 [58] Field of Search 431/218, 227, 344; 126/43, 126/44; 239/5903 [56] References Cited UNITED STATES PATENTS 2,363,098 11/1944 ,Tullis ..l26/44X 2,465,572 3/ 1949 Bramming 126/44 X Primary Examiner-Edward G. Favors Attorney, Agent, or Firm-Le Blane & Shur [5 7] ABSTRACT This invention relates to a stove for burning various hydrocarbon fuels such as gasoline, naphtha, kerosene and the like and more particularly is directed to an improved bumer construction for portable stoves of this 7 type which may beused by campers, back-packers, mountain climbers and others interested in the outdoors. I

13'Claims, 6 Drawing Figures PAIENIH! nus! 31914 amena- SHEET 2 u! 2 FIG. 3

GASOLINE STOVE cooking utensil may be supported directly above the burner to receive heat from it.

One of the difficulties associated with the use of liquid fuels in small portable stoves is the problem of insuring complete vaporization of the liquid fuel prior to combustion. Attempts to overcome this problem have resulted in a variety of proposed devices for incorporation in the stove burner adjacent the burner orifice to enhance vaporization and improve fuel combustion. Incomplete vaporization in addition to reducing the efficiency of fuel consumption tends to produce deposits of less volatile hydrocarbon products in the burner and these deposits have a tendency to clog the burner orifice after the stove has been used for only a relatively short period of time. However, insofar as applicant is aware, none of these attempts have been completely successful and it is conventional in portable cooking stoves to incorporate a cleaning rod having a needlelike point or tip which may be inserted into the burner orifice to unclog the orifice and remove hydrocarbon materials that have been deposited in it. In addition to increasing the cost of the stove the use of cleaning rods is at the very least an annoyance to the camper since they do not prevent clogging and only serve to remove deposits after the burner has become partially or wholly ineffective. Further, deposits dislodge by the cleaning rod may come to rest in the fuel line only to be carried by gasoline and/or vapor back to the orifice where they again clog the orifice and have to be removed.

For example, in one known type of stove construction the stoves are provided by the manufacturer with a jet (sometimes called tip) cleaning tool. This tool consists of a very fine wire, commonly.0.0l inch in diameter, mounted on a small handle. The user isinstructed to clean the opening in the jet by inserting the fine wire of the tool several times while the stove is operating. In some stoves, this tip-cleaning wire or needle is built into the vaporizer section and is caused to enter the orifice in the jet by working a small rotating handle.

The present invention relates to an improved construction for burning liquid fuel in portable stoves of the type used by hunters, campers, back-packers and the like. In particular, the invention is concerned with improving the reliability of the stove burner with the avoidance of malfunction due to clogging of the fuel jet of the burner.

The novel construction of the stove burner jet of the present invention eliminates the clogging described above and, therefore, eliminates the need for any orifice cleaning needle.

In the present invention, substantially complete vaporization of the fuel is achieved by requiring the fuel to travel a long helical path where the fuel is subjected to the heating action of a substantial mass of metal. In addition, the present invention provides a pre-cracking device in the form of a metal screen within the jet itself.

This screen is press-fit into the jet and is substantially at the same temperature as the jet. The holes in the screen are smaller than the diameter of the jet orifices so that any particles which can pass through the screen also pass through the orifice. More importantly, the fact that the screen is at the same temperature as the jet means that there is no further cracking of the longer-chain hydrocarbons in the space between the screen and orifice and thus there is no deposition of carbon in the orifice. The screen traps any particles which may 7 come through from dirty fuel and these particles are such that they do not clog the screen. The ends of the wires comprising the screen are substantially all in pressed contact with the jet and are at substantially the same temperature as the jet. Due to the good heat conductivity of the metal screen, the heat from the jet is transported through and about the screen wires so that substantially the same temperature exists across the entire screen.

It is therefore one object of the present invention to provide an improved stove for burning liquid fuels.

Another object of the present invention is to provide an improved liquid fuel burning stove of the small portable type particularly adapted for use by campers, hikers and the like.

Another object of the present invention is to provide an improved burner construction for portable liquid fuel burning stoves.

Another object of the present invention is to provide a stove burner having improved fuel vaporization characteristics suitable for burning a variety of hydrocarbon fuels such as gasoline, naphtha, kerosene and the like.

Another object of the present invention is to provide an improved stove burner in which a transversely extending hydrocarbon pre-cracking screen is provided directly in the burner jet adjacent the jet orifice.

Another object of the present invention is to provide an improved stove burner construction in which a liquid fuel is first substantially vaporized by passing it through a helical path adjacent a relatively large mass of hot metal and then passed through a pre-cracking screen at substantially the temperature of the burner jet orifice.

Another object of the present invention is to provide an improved burner construction for liquid fuel stoves which eliminates the deposition of uncracked and partially cracked material in the burner jet orifice and therefore eliminates the need for frequent cleaning of the jet orifice by a cleaning rod or cleaning needle as in previous constructions.

Another object of the present invention is to provide a portable camp stove with an improved burner construction which is less susceptible to orifice clogging.

These and further objects and advantages of the invention will be more apparent upon reference to the following specification, claims and appended drawings wherein:

FIG. 1 is a top plan view of a portion of a portable cooking stove constructed in accordance with the present invention;

FIG. 2 is an elevational view with parts in section of the stove illustrated in FIG. 1;

FIG. 3 is an enlarged vertical cross section through the burner portion of the stove illustrated in FIG. 2;.

FIG. 6 is a plan view of the burner jet filter screen prior to insertion into the burner jet.

Referring to the drawing, and particularly to FIGS. 1 and 2, the novel stove of the present invention is generally indicated at 10 and is of the portable type generally used by back-packers. Liquid fuel such as gasoline is contained in a fuel tank 12 and is pressurized by an air pump or the like so that when valve 14 is open the liquid fuel passes under pressure into a fuel tube 16. The fuel tube passes through the vertical wall 18 of a metal cup 20. Enclosed within tube 16 is a wicking 22 preferably made of fine wires or fiberglass. From fuel tube 16 the fuel passes into a burner assembly generally indicated at 24.

Burner assemly 24 includes a burner cup 26 of generally outwardly and upwardly flaring conical configuration provided with suitable apertures such as the aperture 28 illustrated in FIG. 2 permitting entry of air into the interior of the burner cup. The apertures 28 by way of example only may be four or six in number to permit the entry of combustion air. Overlying the upper end of burner cup 26 is a flame spreader 30 including a central solid circular disc 32 with four integral and outwardly extending arms 34. These arms are each crimped over at their ends as indicated at36 to overlie and tightly engage the upper annular edge of burner cup 26 so as to support the flame spreader at the upper end of the cup.

The metal cup or body 18 is provided at its upper end with an outwardly extending annular flange 38 and attached to this flange or rim are the opposite ends of a pair of

support wires

40 and 42 which run parallel across the stove body to provide a support for a cooking pan or other cooking utensil which may be placed on the

support wires

40 and 42. The burner assembly 24 is supported within the cup or body 18 by means of a screw 44 passing through a suitable aperture in the center of the bottom wall 46 of the cup and threaded into a primer cup 48 forming a part of the burner assembly.

FIG. 3 shows the burner assembly 24 to an enlarged scale and like parts bear like reference numerals in that figure. Primer cup 48 is provided with internal threads 50 adapted to engage the threads on the screw 44 of FIG. 2 and an annular well 52 formed by the body of the primer cup and the outer annular flange 54. Primer cup 48 is in turn secured to a vaporizer in the form of an elbow 56 having a central passageway 58 receiving one end 60 of the fuel tube 16. The end 60 of the fuel tube is preferably secured to the elbow 56 as indicated at 62. Received within the passageway 58 is a solid metal plug 64 having helical threads defining grooves 66 which form with the adjacent vertical wall 68 of the elbow an annular helical passageway for the fuel.

The upper end 70 of elbow 56 is externally threaded to receive the internally threaded collar 72 of the burner cup 26. Upper end 70 of the elbow 56 is also internally threaded to receive a burner jet 74 provided with a burner orifice 76. Positioned within jet 74 closely adjacent to the orifice 76 is a fine wire mesh 78 having a plurality of openings through which the fuel may pass substantially smaller than the diameter of the jet orifice 76.

FIGS. 4 and 5 show the details of the burner jet 74 and FIG. 6 is a plan view of the wire screen 78 prior to its insertion into the jet. As previously described, jet 74 is externally threaded as at 80 for insertion into the upper end of elbow 56 of FIG. 3 and one end of the jet 78 is provided with a groove or notch 82 adapted to receive the end of a screwdriver for inserting and rotating the jet 74 into the upper end of the elbow. This notch 82 communicates with the orifice 76 formed in a central wall 84 of the jet. The other end of the jet is provided with a chamber 86 in fluid communication with the other end of jet orifice 76 and which chamber receives the wire screen 78. Wire screen 78 is originally preferably of flat circular shape as illustrated in FIG. 6 and is inserted into the chamber 86 with its outer edges in tight heat contacting engagement with the annular wall of chamber 86 so that the wire mesh assumes the generally bowed configuration illustrated. Wire mesh 78 is inserted into the chamber 86 a substantial distance so that the central bowed portion of the mesh is close to the orifice 76.

In operation, gasoline is admitted into the fuel tube 16 through the valve 14 from pressurized tank 12. Liquid gasoline enters elbow 56 and is vaporized. To insure that little or no liquid gasoline passes through the elbow to the jet, the fuel is made to flow through the helical passageway formed by metal plug 64 and the adjacent vertical walls of the elbow. Plug 64 may comprise a screwthreaded metal rod with a light press-fit in the passageway of the elbow. The vapor then passes through the wire mesh 78 and through orifice 76. The vapor exits from orifice 76 with sufficient energy to inspirate air through the slots 28. The combined fuel vapor and air strike spreader 30 which deflects the gases outwardly in all directions toward burner cup 26 where active combustion takes place. The flame is deflected upwardly from the burner cup 26 toward the bottom of the cooking utensil resting on the

support wires

40 and 42. In starting the stove the elbow 56 is customarily preheated to above the boiling point of gasoline. This is done by adding liquid gasoline or alcohol to the reservoir 52 of the priming cup 48 and setting it afire.

Liquid fuel such as gasoline, naphtha and kerosene, are commonly mixtures of various low boiling point fractions of petroleum. When stored for an extended period of time such as a few months to a few years, some of these hydrocarbon fractions recombine to form varnishes and gum. These degradation products of the original liquid do not vaporize uniformly and instead tend to crack or decompose when heated with the formation of free carbon which deposits on the hot metal surfaces. The accumulation is not stable, however, and comes loose occasionally in small chunks which are large enough to clog a fuel orifice.

Further, there is some possibility at higher burning rates that droplets of fuel can go through a conventional vaporizer carried along by the portion of the fuel which has vaporized so that droplets of liquid fuel can get to the orifice itself. There vaporization takes place with the deposition of these higher molecular weight hydrocarbons such as varnishes. A coating then builds up on the jet which must be removed from time to time.

' For this reason, previous portable stoves have usually metal of elbow 56 and the other side by the metal of plug 64. The metal and plug are heated by the conduction of heat from the burner cup 26. I have not found it necessary to have the vaporizing helix plug 64 in leak-tight relationship at the peak of its threads with elbow 56. It is sufficient that the clearance between the peak of the threads and the bore in the elbow is small enough to prevent significant droplets of gasoline from going through without being vaporized.

A more important aspect of the present invention which avoids the clogging of prior art stoves is the provision of the metal screen or mesh 78 within the jet orifice itself. This screen is press-fit into the chamber 86 in the jet itself and hence is substantially at the same temperature as the jet. The holes in the screen by way of example only may be 0.005 inches in diameter as compared with the diameter of the orifice 76 which in this example may be from 0.010 to 0.030 inch. Thus, any particles which can pass through the screen also can pass through the orifice. The screen being of good heat conducting metal itself, being located closely adjacent the jet orifice and in good heat conducting contact with the metal of the jet 74, insures that the wire mesh 78 will be over its entire area at effectively the same temperature as the jet 74, i.e., between about from 400 to 500 P, so that there is no substantial further cracking of the longer chainhydrocarbons in the space between the screen 78 and the orifice 76. Thus, there is little or no deposition of carbon in the orifice 76. A further benefit of the screen 78 is that it traps any foreign particles which have come through from dirty fuel.

These particles are deposited on the screen which screen is of sufficiently large size that they do not serve to clog the screen. Should the screen become clogged after long periods of usage, it is a simple matter to disassemble the unit, remove it from the jet and replace it with a new wire mesh screen 78.

In the preferred embodiment the metal elbow, burner cup, flame spreader and jet are all made of brass for good thermal conductivity. Plug 66 is made of steel or brass and screen 78 is made of stainless steel or brass. While a metal screen whose outer peripheral edge is in tight heat conductive contact with the jet is preferred, in some instances screen 78 can be replaced with a circular plug of porous heat conducting metal made by sintering partially-compacted metal powder. The primer cup, if desired, can be replaced by a primer pad or primer wick.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States letters Patent is:

l. A burner assembly for liquid fuel stoves comprising a fuel vaporizer, a fuel jet having a jet orifice with one end of said orifice in fluid communication with said vaporizer, a burner cup in fluid communication with the other end of said jet orifice, and a pre-cracking heat conductive member adjacent said orifice with openings smaller than the diameter of said orifice, said member extending laterally between said vaporizer and said orifice whereby all the fuel passing from said vaporizer to said orifice must pass through said openings, said heat conductive member having an annular portion in tight heat conductive contact with said jet whereby substantially the entirety of said member is at effectively the same temperature as said orifice due to proximity to said orifice and heat conduction from said jet.

2. A burner assembly according to claim 1 wherein said pre-cracking member comprises a resilient wire mesh having its outer edges resiliently urged in press fit engagement with said jet.

3. A burner assembly according to claim 2 wherein said wire mesh comprises a plurality of criss-crossing wires, said wires each having its ends contacting said jet whereby heat from said jet is conducted through each of said wires from each of its ends.

4. A burner assembly according to claim 1 wherein the openings in said pre-cracking member are approximately 0.005 inch wide.

5. A burner assembly according to claim 4 wherein the diameter of said orifice is from 0.010 to 0.030 inch.

6. A burner assembly according to claim 1 wherein said vaporizer comprises a tubular metallic elbow, and a primer cup adjacent said elbow for applying primer heat to said vaporizer.

7. A portable liquid fuel stove comprising, a fuel tube for receiving liquid fuel under pressure, a vaporizer coupled to said liquid fuel tube, a fuel jet having a jet orifice coupled to said vaporizer, a burner cup having apertures for inspirating air into said cup, the interior of said burner cup being in fluid communication with the outlet end of said jet orifice, a flame spreader mounted over the upper end of said burner cup, and a pre-cracking heat conductive member between said vaporizer and said orifice, said heat conductive member having openings smaller than the diameter of said orifice and extending laterally of the fuel flow path between said vaporizer and said orifice whereby all of the fuel passing from said vaporizer to said orifice must pass through said openings, said heat conductive member being located adjacent said orifice with at least its outer periphery in tight heat conductive contact with said jet whereby substantially all of said pre-cracking member is at the temperature of said orifice due to proximity to the orifice and heat conduction from said jet.

8. A stove according to claim 7 wherein said fuel jet comprises an elongated tubular member including a transverse wall containing said jet orifice and a chamber adjacent said orifice, said heat conductive member extending laterally across said chamber with its peripheral edge press fit against the interior wall of said chamber.

9. A stove according to claim 8 wherein said vaporizer comprises an elbow, primer means attached to one arm of said elbow, and said fuel jet being removably joined to the other arm of said elbow.

10. A stove according to claim 9 wherein said heat conductive member is at a temperature of from about 400 to 500 F during operation of said stove.

11. A burner assembly for liquid fuel stoves comprising a fuel vaporizer, a fuel jet having a jet orifice with one end of said orifice in fluid communicationwith said vaporizer a burner cup in fluid communication with the other end of said jet orifice, and a pre-cracking heat conductive member adjacent said orifice with openings smaller than the diameter of said orifice, said member extending laterally between said vaporizer and said orifice whereby all the fuel passing from said vaporizer to said orifice must pass through said opening, said heat conductive member having an annular portion in tight heat conductive contact with said jet whereby substantially the entirety of said member is at effectively the same temperature as said orifice due to proximity to said orifice and heat conduction from said jet, said precracking member comprising a resilient wire mesh having its outer edges resiliently urged in press fit engagement with said jet, said wire mesh comprising a plurality of criss-crossing wires, said wires each having its ends contacting said jet whereby heat from said jet is conducted through each of said wires from each of its ends, the resiliency of said mesh causing it to bow inwardly at its center into close proximity with said jet orifice.

12. A burner assembly for liquid fuel stoves comprising a fuel vaporizer, a fuel jet having a jet orifice with one end of said orifice in fluid communication with said vaporizer, a burner cup in fluid communication with the other end of said jet orifice, and a pre-cracking heat conductive member adjacent said orifice with openings smaller than the diameter of said orifice, said member extending laterally between said vaporizer and said orifice whereby all the fuel passing from said vaporizer to said orifice must pass through said openings, said heat conductive member having an annular portion in tight heat conductive contact with said jet whereby substantially the entirety of said member is at effectively the same temperature as said orifice due to proximity to said orifice and heat conduction from said jet, said vaporizer comprising a tubular metallic elbow, a primer cup adjacent said elbow for applying primer heat to said vaporizer, and a solid metal plug with helical threads in one end of said elbow defining with said elbow a helical passageway for the fuel flowing through said vaporizer.

13. A portable liquid fuel stove comprising, a fuel tube for receiving liquid fuel under pressure, a vaporizer coupled to said liquid fuel tube, a fuel jet having a jet orifice coupled to said vaporizer, a burner cup having apertures for inspirating air to said cup, the interior of said burner cup being in fluid communication with the outlet end of said jet orifice, a flame spreader mounted over the upper end of said burner cup, and a pre-cracking heat conductive member between said vaporizer and said orifice, said heat conductive member having openings smaller than the diameter of said orifice and extending laterally of the fuel flow path between said vaporizer and said orifice whereby all the fuel passing from said vaporizer to said orifice must pass through said openings, said heat conductive member being located adjacent said orifice with at least its outer periphery in tight heat conductive contact with said jet whereby substantially all of said pre-cracking member is at the temperature of said orifice due to proximity to the orifice and heat conduction from said jet, said fuel jet comprising an elongated tubular member including a transverse wall containing said jet orifice and a chamber adjacent said orifice, said heat conductive member extending laterally across said chamber with its peripheral edge press fit against the interior wall of said chamber, said vaporizer comprising an elbow, primer means attached to one arm of said elbow, said fuel jet being removably joined to the other arm of said elbow, said heat conductive member being at a temperature of from 400 to 500 F. during operation of said stove, and an externally threaded solid metal plug received in said other arm of said elbow, said plug forming with said other arm a helical passageway for fuel flowing to said orifice.

Claims

1. A burner assembly for liquid fuel stoves comprising a fuel vaporizer, a fuel jet having a jet orifice with one end of said orifice in fluid communication with said vaporizer, a burner cup in fluid communication with the other end of said jet orifice, and a pre-cracking heat conductive member adjacent said orifice with openings smaller than the diameter of said orifice, said member extending laterally between said vaporizer and said orifice whereby all the fuel passing from said vaporizer to said orifice must pass through said openings, said heat conductive member having an annular portion in tight heat conductive contact with said jet whereby substantially the entirety of said member is at effectively the same temperature as said orifice due to proximity to said orifice and heat conduction from said jet.

10. A stove according to claim 9 wherein said heat conductive member is at a temperature of from about 400* to 500* F during operation of said stove.

11. A burner assembly for liquid fuel stoves comprising a fuel vaporizer, a fuel jet having a jet orifice with one end of said orifice in fluid communication with said vaporizer a burner cup in fluid communication with the other end of said jet orifice, and a pre-cracking heat conductive member adjacent said orifice with openings smaller than the diameter of said orifice, said member extending laterally between said vaporizer and said orifice whereby all the fuel passing from said vaporizer to said orifice must pass through said opening, said heat conductive member having an annular portion in tight heat conductive contact with said jet whereby substantially the entirety of said member is at effectively the same temperature as said orifice due to proximity to said orifice and heat conduction from said jet, said pre-cracking member comprising a resilient wire mesh having its outer edges resiliently urged in press fit engagement with said jet, said wire mesh comprising a plurality of criss-crossing wires, said wires each having its ends contacting said jet whereby heat from said jet is conducted through each of said wires from each of its ends, the resiliency of said mesh causing it to bow inwardly at its center into close proximity with said jet orifice.

13. A portable liquid fuel stove comprising, a fuel tube for receiving liquid fuel under pressure, a vaporizer coupled to said liquid fuel tube, a fuel jet having a jet orifice coupled to said vaporizer, a burner cup having apertures for inspirating air to said cup, the interior of said burner cup beiNg in fluid communication with the outlet end of said jet orifice, a flame spreader mounted over the upper end of said burner cup, and a pre-cracking heat conductive member between said vaporizer and said orifice, said heat conductive member having openings smaller than the diameter of said orifice and extending laterally of the fuel flow path between said vaporizer and said orifice whereby all the fuel passing from said vaporizer to said orifice must pass through said openings, said heat conductive member being located adjacent said orifice with at least its outer periphery in tight heat conductive contact with said jet whereby substantially all of said pre-cracking member is at the temperature of said orifice due to proximity to the orifice and heat conduction from said jet, said fuel jet comprising an elongated tubular member including a transverse wall containing said jet orifice and a chamber adjacent said orifice, said heat conductive member extending laterally across said chamber with its peripheral edge press fit against the interior wall of said chamber, said vaporizer comprising an elbow, primer means attached to one arm of said elbow, said fuel jet being removably joined to the other arm of said elbow, said heat conductive member being at a temperature of from 400* to 500* F. during operation of said stove, and an externally threaded solid metal plug received in said other arm of said elbow, said plug forming with said other arm a helical passageway for fuel flowing to said orifice.