US2822037A - Pulsating combustion burner appliance - Google Patents

Description

Feb. 4, 1958 J. E. M CUTCHEN 2,822,037

PULSATING COMBUSTION BURNER APPLIANCE Filed Sept. 1, 1955 Ji J I N V EN TOR.

A77 ORN E X51 United States Patent 2,822,037 PULSATING COMBUSTION BURNER APPLIANCE John E. McCntchen, Wichita, Kans., assignor to 'I he Coleman Company, Inc., Wichita, Kans, a corporation of Kansas Application September 1, 1955, Serial No. 531,872

9 Claims. (Cl. 158--94) This invention relates to a heating device, and more especially to a burner appliance adapted for use in heating and cooking, and to a burner appliance adapted to burn liquid fuels of various types.

This application is a continuation-in-part of my copending patent application, Serial No. 194,085 filed November 4, 1950 now abandoned.

An object of this invention is to provide a light-weight heating device capable of producing exceptionally high heat outputs under extremely varied atmospheric conditions; such as, for example, those encountered in the Arctic regions. Another object is to provide a liquid fuel burning, combustion heating appliance which may be operated on gravity or capillary feed and which burns steadily with a minimum amount of smoking on a wide variety of liquid fuels ranging from alcohols, fuel oil and kerosene, to high octane gasolines such as are produced by cracking processes or by the addition of antiknock compounds, such as tetraethyl lead.

Still another object of the invention is in providing a combustion heating appliance adapted to burn liquid fuel with explosions which occur in a pulsating regular manner and which create rapid vaporization of the fuel and apparently serve to pump it across a .capillary Wick structure from a reservoir to a point of burning. Yet another object of the invention is in the provision of a combustion heating device of the character described which may be easily and quickly ignited in the face of high winds and which may be operated under temperature conditions ranging from about minus 65 F. to about 125 F.

A further object of the invention is in'theprovision of a combustion heating device adapted for usein acooking and heating stove, and which is constructed of relatively few, low cost parts. Additional objects andadvantages will become apparent as the specification develops.

Embodiments of the invention are illustrated in the accompanying drawings, in which- Figure 1 is a front view in elevation of a combustion heating appliance embodying the invention; and Figure 2 is a longitudinal sectional view, the section being taken as indicated by the line 2-2 of Figure 1.

In Figures 1 and 2, 50 designates a=housing having a rear end closure plate 51and an open front end. An oil intake nozzle 52 communicates with the housing through anopening in the top thereof .and is provided .with. a passage 53 for the feeding of liquid fuel into the housing. In the particular structure shown, the housing 50is's'hown positioned in a horizontalplane, but it will bennderstood that the housing may bemounted inany desired position. Further, the closure .plate 51 at the rear of the housing may be omitted, and the wicksemployed may be extended into a container for the liquid fuel, as will be the case when the burner is incorporated into :a stoveassembly.

Within thehousing 50 are wicks 54 'havingtheir .forward end portions extending throughthe front. open end of the housing. Enclosing thehousing 50 and the ,forward end of the bundle of wicks is an air'baflleplate'SS having a central circular opening v56. 'The'housingfj50 is supported so as'tooccupy a central position'within the ice aperture 56 of plate 55, and thus provides an annular pas= sage 57 about the housing 50 and the wicks 54 through which air may pass. A metal strap 58, or a plurality of such straps, serves to support the housing 50 centrally within the aperture 56 of the battle 55.

Iprefer to employ a tubular shell 59 which may be circular or rectangular in cross section, or of any other desired shape, and providing an enclosure about the wicks 54. It will be understood, however, that when the baffle and housing 50 are placed within a burner box or casing, it may often be possible to omit the shell 59.

In the illustration given, the bundle of wicks 54 extends forwardly from the housing 50 with a portion thereof in a generally straight line, while another portion is turned laterally and across the annular air passage 57. As will be observed more clearly from the showing in Figure 1, the laterally or radially turned wick portions 54a provide between them substantially V-shaped openings 60 through which the air may pass. Thus, there is a central wick bundle portion which is substantially solid and which virtually excludes air circulation, and lateral V- shaped areas where air may circulate more freely as it approaches the outer edge of the bafiie opening 56.

Any suitable heat-resisting material may be employed for forming the wicks. I have found that glass fibers form an excellent wick structure, and that the glass can be coated effectively with a refractory material which greatly increases its ability to withstand high temperatures. For example, I find that I can apply a coating of refractory oxide to each individual fiber of the wick ,by wetting the wick with a solution of a soluble salt which will upon decomposition deposit a refractory oxide .on the fiber. For example, a solution of thorium nitrate may be applied to the capillary material by simply immersing one end of the capillary material in the solution, and thereby the solution is drawn up about the individual fibers to coat them. After drying, the .wick structure may be heated to cause decomposition of the nitrate, depositing a coating of oxide on the glass fibers. I have found thatthis process is also very useful in shaping ithe wicks so as to produce the outwardly or radially extending portions 54a. By heating the wick after it has been impregnated with the solution, and after the wick has been turned to the desired angular position, it is foundithat the heatingof the wick to the point that'the salt decomposes and the oxide or other refractory material coats the glass, sets the wick in :the desired shape.

In the burner structure described, the housing and {the bundle of wicks, together with thethousing, form a barrier to the flow of air into the central portion of the burner chamber or area withinthe tubularshell 59. As a result, the central portion of the chamber in front'of the wicks 54 tends to become filled with a coreof riohvapors. l he air is supplied-only in an annular stream about thevapors. With this structure, it isfound that there isa rich inner core of vapors and an outer, less -rich,.mixture of air and I vapors. The ignition ofthe vapors and air is found to form an explosion which squeezes the inner rich core backwardly toward the wicks, and theheat fromthe retreating flame bears intenselyupon the wick end portions to vaporizea large amount of fuel. Simultaneously'with' the explosion, itisfound that .a backward movement of the :gases toward the annular air inlet seals otf-theinlet for an instant against the inflow of air, and thereafter air flows quickly through the'an-nular opening and again encloses the rich core of vapors, and the flame causes a second explosion.

fuel, while at the same time the pulsating pressure changes seem to have a pumping action upon the flow of fuel vapors from the wicks. As a result, it is found that with a relatively small burner, a tremendous output of B. t. u.s per hour can be obtained, up to and above 1,000,000 B. t. u.s per hour.

The operation of the burner is very similar to that of a gun-type burner where a blower forces air and fuel into a combustion chamber. However, with this structure applicant is able to dispense with a blower and, instead, the pulsating action described seems to supply a rich vapor and air mixture while producing extreme turbulence, resulting in the burning of the fuel within a very small area about the outlet end of the wicks.

By turning a portion of the wicks outwardly in a radial direction, it is found that a more etfective pulsating action of the character described above is obtained, while producing a greater heat output and, at the same time, the structure makes it unnecessary for one to employ a retarder within the tubular shell 59. In the structure shown, it will be noted that the radially extending wicks 54a extend outwardly in spaced relation across the annular air passage 57, but provide between them V-shaped passages which enlarge as they extend outwardly for the passage of the sheath of air forwardly to enclose the rich core of vapors.

It has further been found that where the wicks are turned outwardly, the burner will function properly at lower fuel rates while providing an effective heat production without a smoking condition being present. Where the wicks are not turned laterally, as shown in Figures 1. and 2, and when the burner is operating at low fuel rates, a smoke condition is frequently present at the burner.

As has been brought out, stove assemblies provided in accordance with this invention have been found to deliver a tremendous heat output that may approach a million B. t. u.s per hour even with very small, light-weight burners. It appears that these phenomenal results are achieved through the unusual ignition described, in which the flame is free to advance and retreat from the bundle of wicks; and in so doing, the advance of the flame toward the wicks momentarily interrupts the emanation of fuel vapors therefrom, and at the same time heats the wicks to a very high temperature and thereby brings about a rapid vaporization of the fuel. When the flame advances toward the wicks, it is also operative to seal off momentarily the flow of air into the combustion chamber; and after the flame moves away or retreats from the wicks and the central air opening, air again rushes very rapidly through the opening and mixes with the large amount of fuel vapors provided by the intense heat of the flame hearing against the wicks to provide the combustible mixture.

The rapid pulsations or explosions seem to have a pumping action upon the flow of fuel vapors from the wicks that further facilitates the desirability of this type of ignition. The pumping action, it seems, provides a greater fuel flow through the wicks and contributes to the high B. t. u. output attained by the stove assembly. It is noted that the flame is not confined within a small area surrounding the wicks, but is free to dance or move, and to advance toward and retreat from the wicks and also from the air opening. The flame advances toward and retreats from the wicks; and while it seals the air opening or air passage momentarily, when the flame moves away, the air rushes through the inlet very rapidly and mixes with the high concentration of fuel vapors.

While in the foregoing specification an embodiment of the invention has been set forth in considerable detail for purposes of making a complete disclosure, it will be apparent to those skilled in the art that numerous changes may be made in those details without departing from the spirit and principles of the invention.

I claim:

1. A combustion heating device for bu ni g liquid fuels, comprising a hollow wick housing, a bundle of elongated wicks in said housing and projecting freely forwardly of the forward end thereof, means for supplying liquid fuel to the rear end of said wicks, and an air baffle about said wick bundle and having an opening therein receiving said wick bundle and providing between the baflle and said bundle of wicks a perimetric air-intake port, at least some of said wicks being turned laterally and extending outwardly across said air-intake port in spaced apart relation.

2. A combustion heating appliance for burning liquid fuels, comprising a hollow wick housing, a bundle of elongated wicks in said housing and projecting from the forward open end thereof, means for supplying liquid fuel to the other'ends of said wicks, and an air baffle about said housing and providing an opening receiving said wick bundle and providing between the baffle and said wicks a perimetric air-intake port, some of said wicks extending forwardly in line with said housing and other of said wicks extending freely laterally in radial directions across said air-intake port and at a substantial angle with respect to the forwardly extending wicks.

3. A combustion heating appliance for burning liquid fuels, comprising a tubular shell, an air bafile within said shell and extending thereacross, said baflle having a central aperture, a housing extending through said aperture in spaced relation to said baffle and providing therebetween an annular air-intake passage, a bundle of wicks in said housing and having free end portions extending forwardly a substantial distance of said housing into the space within said shell, and means for supplying liquid fuel to the opposite ends of said wicks, certain of said 1 wicks extending radially across said air-intake passage and generally adjacent said air baflle.

4. A liquid fuel burning heating appliance, comprising a hollow housing having at one end an inlet and at the other end an outlet, a bundle of wicks extending longitudinally of said housing, said housing and wicks forming a closed central area serving as a barrier to the inflow of air through said central area, an air bafile extending about the housing and having an annular opening adjacent said housing through which air may pass in a substantially annular stream to meet vapors from the wicks at the outlet end of said housing, and means for supplying liquid fuel to said wicks at the inlet end of said housing, at least a portion of said wicks freely extending laterallyand radially across said annular opening and in spaced apart relation relative to each other.

5. A liquid fuel burning heating appliance, comprising a tubular shell, an air baflle extending across said shell and provided with a central aperture, a housing supported within said aperture in spaced relation to the edge of the battle to provide a generally annular intake air passage and providing an open forward end adjacent thereto, a bundle of wicks within said housing and extending freely forwardly of the forward end of said housing, and means for supplying liquid fuel to the wicks at the rear end of said housing, a portion of said wicks extending forwardly of said housing in longitudinal alignment therewith and other of said wicks freely extending laterally across said air-intake passage.

6. In a liquid fuel burner, a shell, an air baflle extending across said shell and being provided centrally with an enlarged opening therethrough, a wick housing Within said opening and being spaced from the edges of said baffle defining said opening to provide a perimetric air passage between those edges and the wick housing, said wick housing having an open forward end adjacent said air baflle and being adapted adjacent its other end to receive liquid fuel, and a bundle of wicks within said wick housing, some of the wicks extending forwardly beyond said air baffle and longitudinal of said wick housing, and other of the wicks extending laterally across said passage and forwardly of said air baffle.

7. Thestructure of claim 6 in which the laterally extending wicks project radially across said passage and at least some thereof are in spaced apart relation relative to each other.

8. The structure of claim 6 in which the laterally extending wicks are generally normal to the longitudinal axis of said wick housing.

9. The structure of claim 6 in which the laterally turned wicks extend radially across said passage with some thereof being in spaced apart relation relative to each other and being generally normal to the longitudinal axis of said wick housing, and in which said shell and said air baflie, except for the central opening therethrough, are substantially imperforate.

References Cited in the file of this patent UNITED STATES PATENTS Barnes et al. Apr. 25, 1876 Williams Nov. 4, 1913 Blackford Jan. 17, 1922 McKesson Feb. 11, 1941 Hess Oct. 9, 1945 Morse Sept. 5, 1950 McCutchen Aug. 3, 1954 Stelle et a1. Sept. 13, 1955

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