US2360891A - Liquid fuel burning apparatus - Google Patents

Description

1944- M. A. POWERS ET AL LIQUID FUEL BURNING APPARATUS 3 Sheets-Sheet 1 Filed May 27, 1,941

Milton A. Powers Y Noel H. Suiterjzid f W 4 Oct. 24, 1944. POWERS ETAL- 2,360,891

LIQUID FUEL BURNING APPARATUS Filed May 27, 1941 :5 Sheet-Sheet 2 I i l 96 77 74 E? 73 69' i v I 1 I W E5 W E a Milfon A. Pawem Noe] h. SutZeIjz'eZd Jame/whom, v

1944- M. A. POWERS ET AL 2,360,891

LIQUID FUEL BURNING APPARATUS Filed May 27, 1941 3 Sheets-Sheet 5 Patented Oct. 24, 1944 LIQUID FUEL BURNING APPARATUS Milton A. Powers and Noel H. Sutterfield, De-

troit, Mich., assignors to The Timken-Detroit Axle Company, Detroit, Mich, a corporation of Ohio Application May 27, 1941, Serial No. 395,464

11 Claims.

This invention relates to oil burning apparatus of the rotary wall flame type, and more particularly to water heaters of small capacity for smaller homes embodying oil burners of the general type shown in Sutterfield Patent No. 2,102,763 and in Wilson et a1. Patent No. 2,310,333, issued February 9, 1943.

We have discovered that by employing a fan having adequate volumetric capacity to support combustion but delivering air at sufflciently restricted velocity to insure efficient ignition, and at the same time avoiding excessive recirculation, in combination with a grill assembly designed to deflect the flame behind the flame rim, and a flame shield to prevent the combustion gases from making direct contact with the cold portion of the water backed surfaces, it is possible to successfully use smaller diametered hearths and to efiiciently burn fuel at lower rates than have heretofore been considered feasible with a rotary wall flame type burner.

It is accordingly the primary object of our invention to provide a small novel oil burnnig water heating apparatus capable of eiflciently burning extremely small quantities of oil, thereby to make it practical for medium sized and small homes having limited space and money for such facilities.

A further object of our invention is to provide a heating unit embodying an oil burner of the rotary wall flame type in which the hearth and combustion chamber are completely suspended in the cabinet member and efliciently insulated against heat loss.

A further object of our invention is to provide a fan or air distributing device having sufiicient capacity to efiiciently pump the required amount of air for combustion and which is so designed as to avoid imparting sufficient velocity to the air to interfere with ignition, even when an extremely small hearth is used, and at the same time is also designed to avoid excessively recirculating hot gases of combustion.

A further object is to provide a small rotary wall flame type water heating oil burner with a novel hearth flame rim, grille and shield assembly which makes it possible to efficiently utilize smaller diameter and/or capacity combustion chambers than have been heretofore regarded as practicable.

A still further object is to provide improvements in oil burner controls of the trip-bucket type, which eliminate the inconvenience of unnecessary trippings, and 'still insure safety of control, and to also provide improved means for tilting the hearth surface toward the overflow port.

a novel cabinet assembly for a rotary wall flame oil burning water heater so designed as to make inspection, cleaning and servicing of the burner a very direct and simple matter, and also having a novel top construction embodying novel flame baffling and burner operation inspecting features.

A further object is to provide a novel grill assembly for oil burning apparatus of the wall flame type, which is of extremely simple onepiece construction and yet is elflcient and durable.

Another object is to providea novel igniter means for burners of the wall flame type embodying means for adjusting the electrode toward and away from the flame rim without changing the angle of the electrode with respect to the fan.

The invention also aims to provide a novel combustion chamber and heating coil combination, the coil of which may be readily disassembled for servicing or replacement.

Further objects are to generally improve and refine certain subordinate features of heating apparatus, which will become apparent as the specification proceeds in conjunction with the annexed drawings, and from the appended claims.

In the drawings: 1

Figure 1 is a vertical sectional view of a heating apparatus embodying the invention.

Figure 2 is a vertical sectional View on an enlarged scale of the lower part of the apparatus shown in Figure 1, and illustrates the hearth and distributor assembly.

Figure 2a is a fragmental elevational viewof the igniter shown in Figure 1, as it appears when viewed from the right-hand side of that figure.

Figure 3 is a'fragmental top plan view of the hearth and distributor assembly shown in Figure 2. Y

Figure 4 is a bottom plan view of the fan shown in Figures 2 and 3, and illustrates the relationshipassumed by the oil finger tubes with respect to the fan blades.

Figure 5 is a sectional view of the lower part of the casing shown in Figure 1, taken substantially along the line 5-5 of that figure.

Figure 6 is a view similar to Figure 2, but illustrates a modifiedform of hearth assembly, also forming part of the invention.

Figure 7 is a fragmental sectional view on a greatly enlarged scale, of the edge of the overflow port shown in Figure 6.

A further object of the invention is to provide With continued reference to the drawings, wherein like reference characters have been employed to designate like parts throughout the several views thereof, the heating apparatus of the invention comprises a cabinet member A, in which is suspended a shell-like combustion chamber B and also a hearth assembly C, which in turn supports a liquid fuel burning apparatus designated generallly as D.

Cabinet structure The cabinet structure is made up of a base member Ill having a flanged lower edge II, and adjacent its upper edge are provided a plurality of circumferentially spaced brackets l2. The cabinet structure proper, designated as I3, is telescoped within base member ID at its lower edge and rests upon brackets 1'2. The parts may be secured in overlapped assembled relationship by nut bolt assemblies l4.

The lower front portion of the cabinet is provided with a service opening l5, which is closed by a door 16 having a handle: I! in the form of a knurled headed bolt threaded into a nut welded to the inner face of the casing. Each side of the door, at its lower edge, is provided with a clip member l8, which fits: inside base member H1; and the latter is provided: with a single upstanding retaining member I9, located adjacent the middle of the door, which prevents the midportion of the door from. bowing inwardly, when itis disposed in the abutting relationship to the upper edge of member In shown in Figure 1.

The base is also preferably provided with a plurality of levelling screws 20 threaded into brackets 2i secured to the inner wall of the base and; locked in place by lock nuts 2-2.

Cabinet l3 has a plurality of'brackets for supporting the base plate and the combustion chamher, as hereinafter set forth in detail, which are,

secured atcircumferentially spaced points around the interior of the cabinet structure, and a bracket 23 for supporting a transformer T, all of which are attached as by spot welding. A plate 2.4 is secured to the transformer and is hooked under a lip provided on bracket 23. The plate and bracket are secured together at their lower edges by bolts 25. Although'the cabinet has been illustrated as a circular section, it is to be understood that it may be of rectangular shape in section without departing from the spirit of the invention- The top of the cabinet is. closed by means. of a member 26 having a flange 27 fitting tightly over the upper edge of the cabinet. A plate 28, terminating inwardly of flange 21, is secured in spaced relationship to the under side of closure 2t by means of a plurality of brackets 29, and the space between the two members is filled with a blanket of insulating material 31 of any suitable character. 1

The cabinet top also embodies a combined baffle and inspection assembly of novel. form. Supported in spaced relationship below the top, by means of a plurality of brackets 30, is abaflie 30a, which is operable to divert the hot products of combustion around the upper convolutions of the coil, and prevent escape to the flue until they have transmitted substantially all of the available heat to the coil, as will hereinafter appear.

The bafile is provided with a preferably eccentrically located inspection opening 30b of restricted size, while cover 26 is provided with a concentrically located inspection opening 32, closed by a hinged cover 33 or the like. By opening cover 33 the operation of the burner may be observed through openings 30b and 32, and because of the location of opening 32 this may be done without permitting excess air to enter near the base of the flame and interfere with combustion. Also, because of the eccentricity of opening 3%, the cover may be rotated so as to progressively bring the entire hearth into View, the field of vision for one position of the cover being indicated by dotted lines in Figure 1.

Accordingly, by securing the baffle to a rotatable cover, and ofisetting the openings in the baflie and cover, a comparatively small opening in the baffle affords adequate inspection of the burner without appreciably affecting the efiiciency of the baflle. It is to be understood that although we have disclosed opening 30b as eccentrically located, the advantages of the invention may also be achieved by eccentrically locating opening 32 or both of the openings so long as they are so placed as to afford progressive inspection of the entire hearth assembly when the cover is rotated.

The rear wall of the cabinet adjacent the top, is provided with a flue pipe opening 34, which extends completely to the upper edge of the cabinet, so that when the top is removed it presents an open-sided recess. The back of the cabinet is also provided with a pair of openings 35 and 36, through which the outlet and inlet connections respectively of the coil project, as will here inafter appear.

It is accordingly apparent that the simple cy lindrical metal cabinet of the invention is inherently strong, is efiiciently supported upon base member ID in novel manner, is provided with an adequate service opening i5, is eiiectively reinforced at the top by a closure structure which may be removed to completely expose the interior and provides novel battle and inspection means.

Combustion chamber assembly An important feature of the invention is the novel combustion chamber and the manner in which it is supported in the cabinet, which will the like, are a plurality of bracket members 45 which are preferably so spaced as to seat upon every other bracket 24, although it is to be understood that if desired they may be made equal in number to, and seat upon, all of brackets 24. Brackets 45 are secured in place on brackets 24 by a plurality of screws 46 and nuts 47. A hearth assembly is also supported upon screws 46 as in a manner to be hereinafter described.

As seen in Figure 1, plate 28 overlaps the upper edge of combustion chamber 4|, but terminates short of the walls of cabinet l3, so that the insulation in the top of closure member 26 may contact directly with the insulation 44 between the cabinet and the combustion chamber walls. To insure proper spacing of the combustion chamber from the walls of the cabinet a plurality of spacer members 49 are preferably secured to the combustion chamber and fit closely against the cabinet walls to maintain the parts in properly spaced relationship.

Disposed within combustion chamber 4|, in proximity to the internal wall thereof, is a cylindrical helioally wound water heating coil 50, preferably of copper, and is supported in fixed relation thereto by means of an inlet fitting 5| and an outlet fitting 52, both of which are secured to the combustion chamber as by cap screws 53. As seen in Figure 1, each fitting is provided with a short neck 54 which projects through an opening in the combustion chamber and to which is threadedly secured a pipe nipple 55. The latter are connected to the domestic hot water or heating radiator lines in well known manner.

The tubing of coil 50 is preferably of sufficient diameter to permit rapid circulation of water therethrough by thermosyphon action, and of sufficient strength to be self-supporting from its two points of suspension. The diameter of the coil is suiiiciently great so that the outer periphcry of the convolutions Will be disposed in close roximity to the combustion chamber wall and the outer periphery of the lower convolution will be approximately equally spaced from the chamber walls and a combustion shield, to be hereinafter described. As seen in Figure 1, baifle30a fits rather closely into the top convolution of the coil. By giving the upper end of the chamber an opening as great as the cross-sectional area of the chamber, and mounting the baffle on the top, the chamber interior is completely accessible for cleaning or servicing the burner or coil when the top is removed.

The chamber provides sufficient clearance so that in the case of coil failure screws 53 may be removed, nipples 55 unscrewed, and the coil shifted laterally sufficiently to withdraw necks 54 from the openings in the combustion chamber and the coil unit readily lifted out of the combustion chamber.

An opening 56 is provided adjacent the top of the combustion chamber and secured in alignment therewith, is a flanged flue connecting member 51, by a pair of nut and bolt assemblies 58. Flue connection 51 extends through the insulation and opening 34 out of the cabinet to a usual'flue pipe (not shown) in well known manner. In assembling, the chamber may be lowered as a unit into the cabinet with member 51 in place, by reason of the shape of opening 34, after which the connections which maintain the combustion chamber in place are connected.

From the foregoing it is apparent that the combustion chamber and associated coil are of efficient yet simple and rugged design, and that they are totally suspended within the cabinet and blanketed by a layer of insulating material, the baffle is 50 located as to cause the combustion gas to go around the upper part of the coil before entering the flue, and that the parts are so designed that they may be readily removed for service or inspection if desired.

Hearth structure The entire hearth assembly is carried in novel manner by a foundation or base plate 6!, which has a diameter slightly greater than the combustion chamber, and is also preferably supported by brackets 45. Although, if desired,' only a few brackets 24 may be utilized for supporting the combustion chamber and hearth assembly, preferably all of the bolts 46 extend through openings in the base plate BI, and nuts are threaded thereon to hold the base plate in place. A layer of insulating material 64 is mounted on the base plate, and when nuts 62 are turned home the peripheral edge of the insulation 64 is clamped in air-tight engagement with the lower edge of the combustion chamber. Base plate 6| may be either embossed so that the hearth, supported thereby by supports 'H of equal length, will incline from the horizontal, or the lower edge of the combustion chamber and may be so shaped as to lie in a plane inclined to the horizontal, so that when the base plate is pulled into assembled relationship it will assume a similar inclination. Either alternative eliminates the necessity for specially designing the hearth 'to drain any overflow oil' to one side. In the construction shown in Figure 1 the entire base plate is inclined by reason of an inclined edge provided on chamber 4|.

As seen in Figure 2 the base plate is approximately centrally apertured. Disposed in alignment therewith is a spacer collar 53 which supports the central portion of an apertured metal hearth 6'! in spaced relation to the base plate. The hearth and collar are secured to the base plate by a sleeve 68 which is flanged over the hearth and base plate at its upper and lower ends respectively. The outer edge of the hearth is provided with an upstanding flange 69, to which is secured a plurality of supporting legs 75, which extend through openings 12 in the insulation and rest upon the upper surface of the base plate, to which they are attached as by welding.

Mounted in spaced relation to each other on the hearth is an oil atomizing and vaporizing rim l3 and an air deflecting wall 14, which are welded to a plurality of U-shaped brackets 15, and the latter are welded to the hearth, so as to form a rigid unitary assembly. Also rigidly secured to the hearth is a shield ring 16, which snugly fits inside flange G9 and may be welded thereto if desired.

At one side of the hearth is provided an igniter of novel construction, comprising an electi ode 'il, having an outwardly projecting portion 'E'Ea, which is disposed in sparking relationship to the inner face of flame rim 73, and is disposed at a predetermined angle with respect to a radius drawn through the center of the hearth, preferably 25 degrees, as indicated in Figure 3. The electrode is eocentrically mounted in an insulator E8 of generally cylindrical form. The latter is frictionally gripped in a bracket 18a carried by the base plate. The hearth adjacent the insulator i8 is flanged up as at 19 to prevent any excess oil from leaking down between the insulator and hearth.

By mounting the electrode in an igniter insulator having an eccentric aperture, and mounting the insulator for rotative adjustment, a fixed angle of incidence and a predetermined gap may be maintained despite manufacturing tolerances and burning or wear. For instance, if the gap becomes too large, insulator l8 may be rotated slightly in its bracket, to move the electrode closer toward the flame rim. If this results in swinging portion Tia materially away from the desired angle, proper relationship of the parts may be restored by loosening a pair of nuts 19a and rotating the electrode within a clip i929, which engages fiat portions provided on opposite sides of the insulator. When the adjustment is completed, nuts 19a are then tightened,

which pulls the clip into tight engagement with a shoulder 190 provided on the electrode.

The igniter is connected to the high tension circuit of the transformer in any well known manner. Located at the low side of the hearth, preferably opposite the igniter, is a pair of recesses or circular channels 80 and 8| which surround an outlet port 82. Outlet port 82 communicates with a pipe 83 supported by a bracket 84 below the hearth, which leads to a trip bucket type of automatic shut-01f mechanism S, so that after a predetermined quantity of oil passes through pipe 83 the bucket will be tripped and the burner automatically shut off. Mechanism S projects through an opening in the casing and is preferably supported on a bracket assembly 840. carried by plate 6|.

Channels 80 and 81 perform the highly important function of trapping any oil discharge which is not immediately ignited at the time the burner starts. This prevents a flow of oil through pipe 83 into the trip bucket on cold start. As previously pointed out, the foundation plate is inclined, which produces a corresponding slope of the hearth toward. outlet 82, so that in the event of failure of the ignition, the overflowing oil will pass through the discharge port into pipe 83, and cause the shut-off mechanism to stop the burner motor. In the past some difficulty has been experienced in having small driblets of oil on cold or slow starts dripping into the drip bucket and eventually tripping the bucket, despite the fact that no more than normally cold starts have occurred, and no occasion has arisen for the shut off of this character.

With the novel constructions herein disclosed, any oil accumulating in channels 8!! and 8| during cold starts, and which is not immediately ignited, is ,under normal conditions burned oif during the ensuing normal operating cycle of the burner, with the result that when the burner is stopped at the end of the cycle the hearth is dry.

Grille structure A further important feature of the invention resides in an improved grille structure, which, particularly when employed in combination with the novel distributor of the invention and shield 16, greatly assists in enabling the burner to opcrate at extremely small rates of oil consumption, and in combustion chambers of smaller size than heretofore regarded practical.

The grille ring shown in Figures 2 and 3 comprises a simple cylindrical band of heat resistant sheet metal 85 having its ends overlapped and secured together, and a plurality of similarly shaped channel members 86. Each of the channel members is secured to or integral with the outer face of ring 85, preferably with the open sides of the channels facing downwardly. As seen in Figure 3, the channels are disposed in symmetrical, radiating relationship to ring 85 and are supported approximately at their midportion by flame rim 13. Although the channels may be secured to the flame rim, the grille assembly preferably merely freely rests upon the flame rim, so that any thermally induced expansion or contraction of the parts may take place freely. Also, it enables the grille ring to be inverted, so as to face the channels upwardly, depending upon the arrangement which is found to work best under the particular condition at hand. The channels preferably open downwardly inthe particular small capacity unit illustrated, so as to cause the flame to pass outwardly along the channels and then behind flame rim I3, and to maintain a zone of rapid and eflicient combus-.

tion between band 13 and shield 16, and to also maintain the flame rim at an eflicient fuel vaporizing temperature. Reversibility of the grille is particularly desirable when the lower grades of fuel oil are burned.

The function of any grille is to assist mixing of the air and oil projected from the distributor head and to prevent the flame from lifting above the flame rim to a height that it will not heat the flame rim sufficiently to vaporize the oil projected against it. In the small heating unit illustrated, the distance between the ends of the distributor tubes, to be hereinafter described, and the flame rim is comparatively short, approximately 2 inches. With the rim in such close proximity to the flinger tubes it was found impossible for the older type of grilles to properly mix the air and oil for complete and clean combustion without circulating a large amount of the hot gasses of the combustion. Hence excessive recirculation is undesirable, especially in the small hot water heater because there may be many numerous cold starts, particularly during the summer season, and on a cold start the efiect of excessive recirculation is to cause an excessive flow of cold, fresh air, which at high velocity may retard rather than assist ignition of the fuel. We have found that by so designing the fan as to produce a limited degree of recirculation, with suihcient volume to combust the fuel and at sufficiently low velocity to avoid delaying ignition, as will be described hereinafter, and providing the grille assembly constructed as just described, which deflects the gases of the combustion flame behind the flame rim under all normal conditions, and using a shield 16 to prevent contact of the flame with the lower portion of the coil, the apparatus performs with complete satisfaction.

Distributor The distributor comprises a motor and pump unit 88, which is preferably constructed substantially as disclosed in Wilson et al. Patent No. 2,310,333, issued February 9, 1943. The unit as illustrated, however, is supported by two studs which pass through brackets 90 secured to the bottom of the motor housing and have wing nuts 90 threaded thereon. The motor is provided with a shaft 89 upon which is supported an oil distributing head 9|. A pair of upwardly and outwardly extending oil tubes 92, carried by head 9| are designed to propel the oil in the form of unatomized droplets in a trajectory located above the blast from the fan, against the inner face of flame rim (3, with suflicient velocity to shatter or atomize them.

Secured to the upper end of shaft 89, by means of a set screw 93, is a hub member 94, to which is welded a fan head or disc 95.

Secured to the underside of head are a plurality of flanged blades 96 and 91, which are preferably equally spaced. Blades 96 are preferably six in number and will be termed the pumping blades since they are comparatively short and function primarily as pumping blades. Blades 9! are two in number and extend beyond the periphery of the head and will be hereinafter termed velocity blades.

It was found that the earlier designs of fans, having many long velocity blades, imparted too great velocity to the air, which rendered ignition, particularly on a cold start, extremely difficult. Further, in a small. combustion chamber and hearth assembly as employed in the present con-- stnuction, a high air velocity tends to induce excessive recirculation. The novel fan assembly just described overcomes this difficulty because the greatest number of short pumping blades assures suflicient air for combustion without excess velocity, and by locating the distributor tubes leeward of the velocity blades the tubes are maintained out of contact with the heated recirculated gases that are inevitably drawn into the fan and are discharged along the leading faces of the blades with the fresh air supply.

To further insure against excessive recirculation by the tips of the oil tubes 92, and to also protect the tubes against excessive heating, cover 95 is provided with a short lip or skirt 9B, and the ends of the fiinger tubes are located closely adjacent the fan cover. Both of these features cooperate to prevent the recirculated gases from heating and carbonizing the oil in the ends of the distributor tubes.

Shield 16 is important in the small sized unit illustrated, because in such unit a number of critical factors are present. Although shields of various types have been before disclosed in the art, the only functions were to prevent the shielded parts from being subjected directly to the flame, and to prevent the cold water coils from chilling the flame and precipitating soot. It has been found that by making the shield 16 of the correct height it will deflect the hot gases of recirculation and combustion upwardly and away from the lower convolutions of the coil 50 and very good control over the hearth temperature can be maintained, in addition to realizing the decided advantage of preventing direct contact of the flame with the lower convo-lutions of the coil.

The illustrated construction is a commercial unit marketed by the assignee of this application and which has given complete satisfaction in all respects. The important dimensions of this unit are as follows, which are given by way of illustration and not limitation,.it being understood that some latitude is permissible, depending upon the size of the hearth, the speed of the fan and other factors of the particular unit under consideration.

The hearth is approximately inches in diameter and shield 16 is spaced approximately 2 inches from wall 4|. Flame rim 13 is approximately 8 inches in diameter and one and onehalf inches high, while shield 16 is three inches high. Grilles 86 are approximately one and onehalf inches wide and one-fourth of an inch deep.

The fan is rotated at approximately 1600 R. P. M. The two sets of blades are of the same width and their inner ends all terminate approximately five-eights of an inch from the axis of rotation. Blades 91 are approximately one and seven-eighths inches long, while blades 96 are three-fourths of an inch in length.

In Figures 6 and 7 we have illustrated a modified form of heating apparatus also forming part of the invention. The major differences reside in the use of an embossed base, which automatically disposes the hearth at the proper inclination to effect drainage of oil, and a different form of overflow port, which is particularly useful where space does not permit use of the double groove construction shown in Figure 2.

A base plate 6 I a is secured in tight engagement with the lower edge of the combustion chamber as before. However, in this instance the lower edge lies substantially in a horizontal plane, and

the plate, inwardly of its clamping edges, is embossed or formed so as to present an inclined portion l0l to which hearth supports H are secured. This construction accordingly makes it possible to utilize a combustion chamber having a square lower edge and hearth supporting legs of equal length, and yet supports the hearth at the necessary inclination to effect proper drainage of overflow oil. Also, if desired, insulation retaining members 102 may be secured to legs H.

In this form of the invention a single oil drainage groove l03 is provided adjacent outlet 82a, and, as seen in Figure '7, the outlet is machined out at I04 to provide a sharp edge I05 over which the oil must discharge. We havefound that, when using commercial grades of number 2 or number 3 fuel oil, the oil overflowing over the hearth will build up in groove I03 and form a meniscus I06, as shown in Figure '7, to a depth of approximately one-sixteenth of an inch above edge I05 before overflowing into opening 8211.. As previously explained any oil remaining in groove I03 after the burner is started will be consumed during the normal burning cycle, and the hearth will be dry when the burner is shut off.

Accordingly, by using a sharp edge adjacent the outlet port the oil will build up to a depth suffioiently great to take care of all normal conditions, and yet it is unnecessary to employ a high wall to impound the oil.

From the foregoing it is apparent that the invention provides water heating apparatus of emcient and extremely simple and durable construction; and which, by reason of the novel assembly, when top 26 is removed, the interior of the cabinet and the combustion chamber are completely exposed, so that they may be inspected or serviced, and in the case of Fig. 1, the entire coil may be thoroughly cleaned.

Also, by reason of the novel oil and air distributor, which supplies adequate air for combusti on and yet is so designed to effect a minimum recirculation of the combustion gases, in combination with novel grille assembly which insures adequate combustion behind the flame rim 13, it is possible to use a hearth and combustion chamber assembly of much smaller diam eter than has heretofore been regarded as practicable in a wall flame burner.

The invention may be embodied, in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are 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:

1. In a liquid fuel burning apparatus, an outer chamber having a generally upstanding wall; a plurality of brackets secured to the interior of said wall at a level materially above the bottom edge thereof and presenting upwardly facing abutment surfaces; a shell-like combustion chamber disposed in said housing in substantially uniformly spaced relationship to the wall thereof and having a plurality of downwardly directed faces resting upon the abutment surfaces of at least a part of said brackets, means for detachably securing said downwardly directed faces in clamping engagement with the abutment surfaces of said brackets; .a plurality of spacer members located adjacent the upper end of one of said chambers and projecting toward and co operating in abutting relationship with the other chamber fo maintaining the walls of said chambers in properly spaced relationship; a heating device in the lower portion of said combustion chamber; and a heat exchange apparatus disposed in cooperative relationship with said heating device 2. In a liquid fuel burning apparatus, a housing having a generally upstanding wall; a plurality of brackets secured to the interior of said wall at a level above the bottom thereof; a shelllike combustion chamber disposed in said housing in substantially uniformly spaced relationship to the wall thereof, and having an open bottom spaced above the lower edge of the wall of said housing, said combustion chamber also having a plurality of downwardly directed faces resting upon atzleast part of said brackets, a hearth structure; a support closing the bottom of said combustion chamber and supporting said hearth structure, means carried by said brackets for maintaining said support in closing relationbustion chamber mounted in spaced relationship to the internal wall of :said cabinet and having a plurality of downwardly facing abutments resting upon said first-named abutments, so as to support the lower end of said combustion chamber above the bottom of said cabinet; a hearth foundation plate disposed in said cabinet and fitting against the lower end of said combustion chamber so as to close the lower end thereof; means for releasably supporting said plate upon said abutments; and means fo releasably securing the abutmen-ts of said combustion chamber to the abutments of said cabinet.

' '4. In a liquid fuel burning apparatus, an upright, hollow' cabinet of substantialy uniform transverse cross-section; a plurality of upwardly facing abutments mounted on the internal wall of said cabinet above the bottom thereof; a combustion chamber mounted in spaced relationship to the internal wall of said cabinet and having a plurality of downwardly facing abutments resting upon said first-named 'abutments, so as to support the lower end of said combustion chamber above the bottom of said cabinet; means for detachably securing the abutments of said combustion chamber to the abutments of said cabinet; a hearth foundation plate disposed in said cabinet and fitting against the lower end of said combustion chamber so as to close the lower end thereof; means for releasably supporting said plate upon said first-named abutments independently of said combustion chamher; a plurality of outwardly directed elements transverse cross-section; a plurality of upwardly facing abutments mounted on the internal wall of said cabinet above the bottom thereof; a combustion chamber mounted in spaced relationship to the internal wall of said cabinet and having a plurality of downwardly facin abutments resting upon said first-named abutments, so as to support the lower end of said combustion chamber above the bottom of said cabinet; a hearth foundation plate disposed in said cabinet and fitting against the lower end of said combustion chamber so as to close the lower, end thereof; and means for releasably supporting said plate upon said first-named abutments, the lower end of said combustion chamber lying'in a plane inclined to the horizontal, whereby when said hearth plate i pulled into place by said means said plate will assume a similar inclination.

6. In 'a heating apparatus, a combustion chamber having a liquid fuel burning apparatus in the lower portion thereof and a flue opening in the side wall thereof adjacent the top; heat absorbing means located adjacent the side walls of said combustion chamber; and a removable closure for the top of said combustion chamber carrying bafllc means projecting into said chamber and operable to cause the combustion gases to contact the upper part of said heat absorbing means before passing to said flue, said closure and said baffle means each being provided with an inspection opening for viewing the operation of said fuel burning apparatus, one of said openings being offset from the axis of said combustion chamber, whereby said closure may be rotated to afford progressive inspection of the entire periphery of the lower portion of said combustion chamber.

7. In a liquid fuel burning apparatus, a comparatively thin-walled upright housing having an open top, the lower end of said housing having a base portion adapted to rest on a supporting surface; a closure removably supported on the upper end of said housing; a hollow structure disposed in said housing and forming a combustion chamber of smaller cross section than said housing and spaced inwardly from the walls of the latter, said hollow structure extending upwardly substantially to the top of said housing, and extending downwardly to a level spaced above the lower end of said housing; a hearth plate assembly cooperating in direct engagement with the lower edge of said combustion chamber and closing the lower end of said hollow structure; and common means for supporting said hollow structure and said hearth plate assembly in said housing, comprising a plurality of circumferentially spaced, upwardly facing abutments provided on the inner wall of said housing abovethe level of the bottom thereof, and fastening means passing through aligned openings in said abutments and the periphery-of said hearth plate and operable to pull the latter into gas-tight engagement with said hollow structure, said fastening means and said aligned openings being located outwardly of the lower end of said combustion chamber.

8. In a liquid fuel burning apparatus, a comparatively thin-walled upright housin having an open top, the lower end of said housing having a base portion adapted to rest on :a'supporting surface; a closure removably supported-on the upper end of said housing; a hollowshell-like structure disposed in said housing and forming a combustion chamber of smaller cross section than said housing and having an-open top and an open bottom, with its side walls spaced .-inwardly from the walls of said housing, said hollow structure extending upwardly substantially to the top of said housing and closed by said closure, and extending downwardly to a level spaced above the lower end of said housing; a hearth plate assembly closing the lower end of said hollow structure; and common means for supporting said hollow structure and said hearth plate assembly in said housing, comprising a plurality of upwardly facing abutments provided on the inner wall of said housing coacting with downwardly facing abutments on said structure and a plurality of fastening elements associated with said abutments and holding said hearth plate assembly in engagement with the lower end of said hollow structure.

9. In a liquid fuel burning apparatus, a comparatively thin-walled upright housing having an open top, the lower end of said housing havin a base portion adapted to rest upon a supporting surface; a closure removably supported on the upper end of said housing; a hollow, shell-like structure disposed in said housing and forming a combustion chamber of smaller cross-section than said housing and having an open top and an open bottom, with its outside walls spaced inwardly from the walls of said housing, said hollow structure extending upwardly substantially to the top of said housing and being closed by said closure, and extending downwardly to a level spaced above the lower end of said housi g; a hearth plate assembly engagin the lower edge of said hollow structure and closing the lower end thereof; and

common means for supporting said hollow structure and said hearth plate assembly in said housing, comprising a plurality of upwardly facing abutments provided on the inner wall of said housing above the level of the bottom thereof coacting with downwardly facing abutments on said structure; and a plurality of fastening elements associated with said abutments and holding said hearth plate assembly in engagement with the lower end of said hollow structure, the portion of the hearth plate registerin with the interior of said hollow structure being inclined with respect to the horizontal.

10. The liquid fuel burning apparatus defined in claim 9, wherein the lower edge of said hollow structure is disposed in a plane inclined to the horizontal and said hearth plate assembly comprises a fiat, plate secured in a plane parallel to the plane of the lower edge of said hollow structure.

11.The liquid fuel burning apparatus defined in claim 9, wherein the lower edge of said hollow, shell-like structure is disposed in a substantially horizonta1 plane, and said hearth plate assembly includes a plate which is oifset in an annular area adjacent the bottom of said hollow structure to provide a central fiat base plate portion substantially aligned with the interior of said hollow structure.

MILTON A. POWERS. NOEL H. SUTIERFIELD.

CERTIFICATE OF CORREC TION Patent No. 2,560,891. October 2;, 19m,

MILTON A. POWERS, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: e 1, second column, lineh5, for the word "finger" read -flinger-, page 5, first co1umn, line5, for "greatest" read greater-; line 59, for "five-eights" read --five-eighths; line l, after "are" insert -approximately--; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 50th day of January, A. D. 19%.

Leslie Frazer,

(Seal) Acting Commissioner of Patents.

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