US2181407A - Combustion apparatus - Google Patents

Description

Nov. 28, 1939. J. w. MILLER I COMBUSTION APPARATUS Filed April 16, 1938 l\ U JOHN W M/LLE'E.

INVENTOR.

' 'ATTORNEY.

Patented Nov. 28, 1939 PATENT OFFICE COMBUSTION APPARATUS John W. Miller, Lansing, Mich., assignor to Motor Wheel Corporation, Lansing, Mich., a corporation of Michigan Application April 16, 1938, Serial No. 202,397

7 Claims.

This invention relates to oil burners of the vaporizing pot type, and more particularly to means for' controlling the secondary air in such burners.

One of the problems encountered in the de-- sign of oil burners of the vaporizing pot type is the proper control of the flame so that it will not become extinguishedas long as fuel vapors in appreciable quantities are present in the burner. In ordinary oil burners that are not equipped with means for constantly maintaining a flame in the combustion chamber when the burner is operating at its highest stages, the flame may become extinguished while there are still appreciable quantities of fuel vapors present in the combustion chamber. This undesirable condition is ordinarily caused by a sharp decrease in the amount of air admitted to the burner, which in turn is usually due to a sudden decrease in draft. If the burner has been operating at its highest stage and the draft decreases sharply, the burner will still be relatively hot, and will continue to generate fuel vapors at a rapid rate. As a result, the mixture of air and 25 fuel vapors will become so rich that combustion cannot be supported. The flame will then go out, and the stage is set for an explosion when the mixture becomes combustible. The mixture may ignite spontaneously due to the heat stored in the walls of the burner, and an explosion will almost inevitably result.

Heretofore', various methods of overcoming this tendency to explode have been utilized. One way of overcoming this effect is to introduce an excess of air into the combustion chamber so that the mixture will never become too rich to burn. Such a procedure has the disadvantage of decreasing the eiiiciency of the burner because of the undesirable presence of this excess of air, which has no effect other than to absorb heat and carry it up the chimney.

Another method of obviating this difliculty is to provide a baffle ring above the top wall of the 45 burner which deflects the secondary air toward the opening in the top of the burner. This does away with the necessity of providing an excess of air in the combustion chamber, but it tends to localize the flame in the center of the com- 50 bustion space, and consequently impairs the efliciency of the burner. In order to operate at maximum efficiency, the flame must be distributed throughout the combustion chamber, and preferably a portion of the flame should strike 55 the wall of the combustion chamber in order to heat it to a higher temperature than would otherwise be the case.

This invention does away with the tendency toward explosions, and yet at the same time it does not in any way reduce the efllciency of the 6 burner. These desirable results are obtained by providing a novel baflle for controlling the secondary air admitted to the combustion chamber. The bafile consists of an annular ring provided with angularly spaced, downwardly opening 10 channels extending inwardly therefrom. The baflle surrounds the opening in the top wall and is located above the secondary air inlet openings. Thus a portion of the secondary air is led through the channels toward the center of the burner to mingle with the vapors arising directly therefrom, while the remaining air may rise between the channels and between the batlie and the wall of the combustion chamber, to properly distribute the flame in the combustion chamber.

Accordingly, it is an object of this invention to provide an anti-explosion baflle which will distribute the flame uniformly throughout the combustion space, and at the same time prevent explosions in the burner. A further object of 5 the invention is to provide a baflle in the form of an annular ring with angularly spaced channels extending radially inwardly therefrom which direct a portion of the air toward the center of I the burner, but allow the remainder of the incoming air to rise directly into the combustion chamber. Still another object is to construct a battle which has means for supporting the baflie on the top wall of the burner, the supports being in the form of channels. Another object is to provide a battle which canbe readily and economically fabricated from sheet ,metal, and which is so shaped as to render it still and rugged.

Other objects will become apparent in the following specification when read in connection with the accompanying drawing-wherein like reference numerals designate corresponding parts in the several views. In the drawing:

1 Figure 1 is a cross-sectional view of a space heater embodying my invention;

Figure 2 is an isometric View of the bafile itself;

Figure 3 is a fragmentary edge view taken on substantially the line 3- -3 of Figure 5;

Figure 4 is an enlarged cross-sectional view taken on-substantially the line 4-,4 of Figure 5; and I Figure 5 is a cross-sectional view taken on substantially the line 5-5 of Figure 1.

All of these views being taken in the direction of the arrows.

Referring now more particularly to the drawing, the invention is shown as embodied in a space heater comprising a casing Ill and a burner containedtherein.

The casing I0 is preferably cylindrical, but obviously it may be of any other suitable shape. The casing comprises an upper combustion chamber l2 and a lower air jacket |3. The air jacket I3 is preferably slightly greater in diameter than the combustion chamber l2, and the two parts are connected by an annular indented portion forming a shoulder Hi. The combustion chamber l2 has a top wall |5 permanently connected thereto. In the front of the combustion chamber is a door It which allows access to the interior thereof for inserting a lighted taper or the like for igniting the fuel in the burner. Adjacent the upper end of the combustion chamber is a flue outlet H which connects to a chimney l8 in a conventional manner. Mounted in the flue outlet I1 is an automatic draft regulator I9.

The jacket |3 and combustion chamber |2 are supported by legs which are preferably bolted to an inturned flange 'at the lower end of the jacket 3 by means of bolts 20a. The legs are preferably four in number, and each pair of opposite legs are formed from a single metal strip.

The strips intersect at their centers, and are secured together by means of a screw 2|. This screw 2| forms a'support for the burner II and holds the burner tightly against the shoulder M.

The burner I I is preferably made up of a sheet metal side wall 23, a cast metal bottom wall 22, and a cast metal top wall 25. The side wall 23 is preferably of frusto-conical form as shown, and secured to the bottom wall 22 in a manner to provide an air-tight joint between the parts. The side wall is provided with an annular inwardly extending bead 24 on which the top wall 25 rests. The side wall is also provided with an annular outwardly extending bead 21 which abuts the shoulder H in the casing Ill. The burner H is in open communication with the combustion chamber l2 through a large central opening 26 in the top wall 25.

Separating the lower and upper portions of the burner into two compartments is an inclined partition 29. The partition 29 is provided with a large central opening 30 which is preferably located directly below the opening 26 in the top wall of the burner. The partition 29 may be fixed in place or may be removable, as desired.

Air is supplied to the apparatus through two groups of air inlet openings. The sheet metal side wall 23 of the burner is provided with six vertically spaced rows of primary air inlet openings 28. These openings are preferably of substantially uniform size and spacing, and as shown, extend over substantially the entire area of the side wall 23. In the lower wall of the head 21 are a plurality of uniformly spaced apart secondary air inlet openings 3|. The air admitted through these openings is directed into the combustion chamber I2.

The draft communicated to the apparatus from the chimney l8 causes primary air to be admitted to the burner H in a generally horizontal direction through the openings 28, and causes secondary air to be admitted to the combustion chamber in a generally vertical direction through the openings 3!. It will be noted that the cross strips forming the legs 20 do not completely close the bottom of the air jacket l3 so that air has access to the openings 28 and 3|.

Liquid fuel is supplied to the bottom 22 of the burner chamber from a source of supply not shown, through a supply pipe 31. A conventional constant level or metering device 38 is associated with the supply pipe 31 whereby the quantity of fuel delivered to the apparatus may be conveniently regulated.

Located above the top wall 25 and also'above the openings 3| is the anti-explosion bafiie 32, probably best shown in Figure 2. This baffle is preferably formed from a sheet metal stamping, although it will be obvious that it may be cast or formed in any other suitable manner. The baflle consists of an annular ring 33 which has a downwardly extending peripheral flange 34. This flange 34 stiffens the baiiie. Extending inwardly from the annular ring 33 are a plurality of angularly spaced projections 35. The lateral edges of the projections 35 have downwardly extending legs 36 which are as wide in a radial direction as the projections 35. These legs 36 are preferably integral with projections 35, and may be formed by slitting the metal of the ring and pressing them downwardly at right angles to the projections. In this manner, the projections 35 and legs 36 constitute a plurality of angularly spaced radially inwardly extending channels. The channels open downwardly. The legs 36 rest on the top wall 25 of the burner, thus providing a means for supporting the baflie ring 33 and spacing it from said top wall.

The diameter of the ring 33 is slightly less than the inner diameter of the burner side wall 23, so i that the flange 34 is spaced slightly from the wall of the burner, as best shown in Figure 4.

The combustion apparatus illustrated in the accompanying drawing is, as previously mentioned, of the vaporizing pot type. In burners of this type the vertical location of the zone of combustion of the apparatus may be varied by regulating the quantity of liquid fuel supplied to the burner.

The supply of liquid fuel to the burner can be controlled by suitable adjustment of the metering device 38. When the fuel is first ignited, combustion initially occurs in the lower portion of the chamber ||,'or in other words, below the partition 29. The flame will remain in that portion of the chamber so long as but a limited supply of fuel is admitted thereto. As the supply of fuel is .increased the visible combustion rises in the chamber, until finally at the maximum fuel feed it is localized wholly within the combustion chamber |2. By suitable adjustment of the metering device 38 the lower limit of the zone of combustion may be localized in any desirable position between the bottom of the burner I and the secondary air inlet openings 3| in the combustion chamber l2.

If the burner has been operating at its highest stage in which the flame is localized within the combustion chamber l2, and the draft in the apparatus suddenly decreases, the mixture of fuel vapors and air will become too rich to burn. In order that an explosion will not result when the mixture again becomes combustible, it is necessary to maintain active combustion somewhere Within the combustion chamber. The baflle 32 provides such a means for always maintaining a flame in the combustion chamber under such conditions. A portion of the air admitted through the secondary air inlet openings is led through the channels on the baffle to points adjacent the opening 26 in the top wall of the burner. This air mixes with the fuel vapors arising from the burner, so that no matter how concentrated the fuel vapors become elsewhere in the combusondaryopenings 3| will rise through the spaces between the projections 35 directly into the combustion chamber, so that whenever the burner is operating at its highest stage combustion will ensue in the space directly above the baflle ring 33 and adjacent the side walls of the combustion chamber l2. Still another portion of the 'secondary air may enter between the flange 34 and the side wall 23 of the burner.

It will thus beseen that this invention provides a means for preventing explosions in the apparatus, and at the same time distributing the air substantially uniformly throughout the interior of the combustion chamber.

' It will, of course, be apparent that the invention herein disclosed is capable of considerable variation, and consequently the invention is to be limited only by the scope of the appended claims.

I claim: v

l. Combustion apparatus comprising, in combination, a burner of the vaporizing pot type and a combustion chamber in open communication therewith, a top wall for the burner having a large central opening therein, said combustion apparatus having a plurality of air inlet openings above said top wall communicating with the combustion chamber, and a baflie located in spaced relation above said top wall and above said air inlet openings, said baflle being in the form of an annular ring having a plurality of angularly spaced projections extending radially inwardly therefrom whereby a portion of the air admitted through said air inlet openings is directed toward the opening in the top wall oi the burner and another portion of said air may rise between said projections directly into the combustion chamber.

2. Combustion apparatus of the vaporizing pot type comprising, in combination, a burner having a tubular side wall provided with a horizontal row of spaced apart air inlet openings, and battle means located within the tubular side wall in proximity to said side wall, said baille means including angularly spaced apart portions ar-- ranged in a zone above certain of said air inlet openings and extending radially inwardly therefrom whereby to direct at least the major portion of the air admitted through said certain air inlet openings toward the center of the apparatus and whereby to permit the air admitted through the remainder of said air inlet openings to rise vertically between said portions.

3. Combustion apparatus as defined in claim 2, wherein the angularly spaced apart portions of the baiile means are of inverted U-shape in cross section.

4. Combustion apparatus as defined in claim 2, wherein the baiile means comprises an annular ring and the spaced apart portions thereof comprise projections extending radially inwardly from the outer periphery of the ring.

5. Combustion apparatus of the vaporizing pot type comprising, in combination, a burner having a top wall provided with a central opening therein, a plurality of horizontally spaced air inlet openings formed in a wall of said apparatus for admitting air to the apparatus above said top wall, and baille means located within said apparatus above said top wall, said baflie means including a plurality of angularly spaced apart radially extending portions located above certain of said air inlet openings whereby at least the major portion of the air admitted through said certain air inlet openings is directed-toward the opening in the top wall of the burner and whereby the air admitted through the remainder of said air inlet openings is permitted to rise vertically between said portions.

6. Combustion apparatus as defined in claim 5, wherein the angularly spaced radially extending portions of the baille means are of inverted U- shape in cross section.

7. Combustion apparatus of the vaporizing pot type comprising, in combination, a'burner having a tubular side wall provided with a horizontal row of spaced apart air inlet openings, a centrally ,apertured horizontal wall positioned within the burner below and in close proximity to said row of air inlet openings, andbaflle means associated with said horizontal wall to form therewith a plurality of angularly spaced apart channels arranged with respect to certain of said air inlet openings whereby at least the major portion of the air admitted therethrough is directed toward the central opening in said horizontal wall and whereby the air admitted through the remainder of said air inlet openings is permitted to rise vertically between said =angularly spaced apart channels.-

JOHN W. MILLER.

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