US2491517A - Liquid fuel burning apparatus - Google Patents

Description

v20, 1949' M. A. PowERs ETAL LIQUID FUEL BURNING APPARATUS 1 Filed May 27, 1941 3 Shets-Sheet 1 Orig' Milton Power.: /Ycl Jutteield' Original -Fled I ay 27, 1941 DGZ-O, 1.949 M. A. POWERS HAL 2,491Q517 LIQUID FUEL BURNING APPARATUS 's sheets-sheet 2 l|| gnam )filtern A. Riu/ers Mez /flqrfefffezd De 20, 1949 M. A. PowERs ETAL LIQUID FUEL BURNING APPARATUS s sheets-'sheep s Original Filed May 27, 1941 lll- .Wwfm/ 7. P@ A AH. 4

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Patented Dec. 20, 1949 LIQUID FUEL'BURNING APPARATUS Milton A. Powers and Noel H. Sutterfield, Detroit, Mich., assgnors to The Timken-Detroit Axle Company, Detroit, Mich., a corporation of Ohio Qrginal application May 27, 1941, Serial No. 395,464. Divided and this application July 17, 1944, Serial No. 545,234

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 United States Letters Patent to Sutteriield No. 2,102,763 and to Wilson and Sutterfield No. 2,310,333, and is a. division of our application Serial No. 395,464 led May 27, 1941, which issued October 24, 1944, as United States Letters Patent No. 2,360,891.

We have discovered that by employing a fan having adequate volumetric capacity to support combustionbut delivering air at sufliciently restricted velocity to insure emcient ingition, and at the same time avoiding excessivel recirculation, in combination with a grill assembly designed to deflect the name 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 eiliciently 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 burning water heating apparatus capable of eiiiciently 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 aheating unit embodying an oil burner of the rotary wall name type in which the hearth and combustion chamber are completely suspended in the cabinet member and eiciently insulated against heat loss.

A further object of our invention is to provide a fan or air distributing device having sufficient capacity to eiliciently pump the required amount of air for combustion and which is so designed as to avoid imparting suflicient 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 recir-v culating hot gases of combustion.' j

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

A still further object is to provide improve-` ments in oil burner controls of the trip-bucket type, which eliminate the inconvenience of un. necessary trippings, and still insure safety of control, and to also provide improved means for. tiltitng the hearth surface toward the overflow; por y,

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:

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

Figure 2 is a vertical sectional 4view on an enlarged scale of the lower part of theapparatus shown in Figure 1, and illustrates the hearth and distributor assembly.

Figure 2a is a fragmental elevational view of the ignitor shown in Figure 2, 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 Fig-- ure 2.

Figure 4 is a bottom plan view of the fan shown in Figures 2 and 3, and illustrates the relationship assumed by the oil flinger tubes with re. spect to the fan blades.

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

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

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

With continued reference to the drawings, wherein like reference characters have been em ployed 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 generally as D.

Cabinet structure The cabinet structure is made up of a base member I0 having a bottom rim I I, and adjacent its upper edge are provided a. plurality of circumferentially spaced brackets I2. The cabinet structure proper, designated as I3, is telescoped within base member I 0 at itsl lower edge and rests upon brackets I2. The partsl may be secured ln 3 overlapped assembled relationship by nut bolt assemblies I4.

The lower front portion of the cabinet is provided with a service opening I5, which is closed by a door I6 having a handle Il 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 I8, which ts inside base member I0, and the latter is provided with a single upstanding re.- taining member I9, located adjacent the middle of the door, which prevents the mid-portion of the door from bowing inwardly, when it is disposed in the abutting relationship to the upper edge of member I shown in Figure l.

The base is also preferably provided with a plu: rality of levelling screws threaded into brackets 2| secured to the inner wall of the base and locked in place by lock nuts 22.

Cabinetl I3 has a plurality of brackets 24 for supporting the base plate and the combustion chamber, as hereinafter set forth in detail, which are secured at circumferentially spaced points around the interior of the cabinet structure, and

a bracket 23 for supporting a transformer T, all

fwhich are attached as by spot welding. A plate 24 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 or other 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 ange 2 tting tightly over the upper edge of the cabinet. A plate 28, terminating inwardly of ange 2l, is secured in spaced relationship to the under side of closure 26 by means of a plurality of brackets 29, and the space between the two members is filled with a blanket of insulating material 3I of any suitable character.

The cabinet top also embodies a combined baille and inspection assembly of novel form. -Supported in spaced relationship below the top, by means of a plurality of brackets 3B, is a baffle 30a, which is operable to divert the hot products 0f 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 baille is provided with a preferably eccentrically located inspection opening 30h of restricted size, while cover 2Q 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 33h and 32, and beeause of the location of opening 32 this may be tiene without permitting excess air to enter near therese ei the flegie end interfere with eeeieee'- iiel.- Alea be. eee ef the eeeeilirieiiy ef epeelag Sie., the eier he retenes eeee'tefefegrss'vely bring the entire hearth view, the eld of vision for one position cftle cover being indicated by dotted lines' in Figure l.

The reer- Well, 9- tlie eebinet edieeegt. the iep' is provided with a ilueA pipe opening 34, which extends completely to the upper edge oi the cabinet, sq that when the top is removed it presents an openfsided recess.v The back of the cabinet is also provided. with e Deir ef Openings en d 35., through whieetre outlet end inlet eegeeeiieae flue pipe (not shown) in well knpwn manner.

respectively of the coil project, as will hereinafter appear.

Combustion chamber assembly The combustion chamber proper comprises a cylindrical shell 4I of sheet metal having its endsbutted at 42 and secured together in any suitable manner such as by welding. The combustion chamber fits within the'cabinet and is so diametered as to provide a space 43 between the walls thereof, and which is preferably completely filled with a blanket of insulating material 44.

Secured to the outs-ide of the combustion chamber adjacent its lower end, as by welding or 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 t'o, and seat upon, all of brackets 24'. Brackets 45 are secured in place on brackets 24 by a plurality of screws 46 and nuts 4l. A hearth assembly is also supported upon screws gli as in a marmer eo be hereinafter deserted.

Ae eeen in .Finire lfplete 'everless the weer edge ef eembueiien 'ehember .4!! bei termizites short of the walls of cabinet I3, so that the insulation the top o f olpsureV 'member 25 may contact directly with the insulation 4,4 between the cabinet and the combustion chamber walls. To insure proper spacing of 'the combustign chamber from the walls of the cabinet a plurality of spacer members 491' are preierably secured to the. eembueen ehember and t eleeely es eiget the cabinet Walls to maintain the partsv in proper:

L ly spaced relationship.

Disposed. "Wthir'i' 1combusti@ .chamber 4!! in. proximity to the internal wall thereof, is a cylin: drical helically wound water heating goil 5 0, pref,- erably of copper,'and is supported in fixed rela:v tion thereto by means of an inlet fitting 5I and an utlet fitting 52, both of which are secured to the combustion 'chamber as by cap screws 5,5. As seen in Figure 1, each tting is proyided with 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.

An opening 56 is provided adjacent the` top of the combustion chamber and secured in alignment therewith, is a flanged nue connecting member 5T, 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 In assembling, the chamber may be lowered as a unit into the cabinet with member 5,1 in place, by reason of the shape of opening 34, after which the connections which maintain the combustion chamber in place are connected.

Hearth structure The entire hearth assembly is carried ln novel mannerV by a feundation er base plate 6l, which hee e demeter slightly greater than, the eembe.- tien ehember, eed ie eleerreferebly eiiiieer'eed er breekeie 45. Altrieueh if'fde eef @my e ev'v brackets 2 4" maybe utilized for lsupporting the combustion chamber and hearth assembly, pref-- erably all of the boltsl 46 extend through open-f ings in the base plate 6I, and nuts' S2 are threaded thereon to hold the base plate in place.

A layer of insulating material B4 is mounted on the baseplate, end when nuts $2, are turned tiene the reeherel esse' ef' tae'leeuletien @l 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 1| of equal length, will incline from the horizontal, or the lower edge of the combustion chamber 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 B6 which supports the central portion of an apertured metal hearth 61 in spaced relation to the base plate. The hearth and collar are secured to the base plate by a sleeve 68 which is iiangedover the hearth and base plate at its upper and lower ends respectively. The outer edge of the hearth is provided with an upstanding iiange 69, to which is secured a plurality of supporting legs 1|, which extend through openings |2 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 annular flame rim having an oil atomizing and vaporizing wall 13 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 |59 and may be welded thereto if desired.

At one side of the hearth is provided an igniter of novel construction, comprising an electrode 11, having an outwardly projecting portion 11a, which is disposed in sparking relationship to the inner face of wall 13, and is disposed at a predetermined angle with respect to a radius drawn through the center of the hearth, preferably degrees, as indicated in Figure 3. The electrode is eccentrically mounted in an insulator 18 of generally cylindrical form. The latter is frictionally gripped in a bracket 18a carried by the base plate. The hearth adjacent the insulator 18 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 18 may be rotated slightly in its bracket, to move the electrode closer toward wall 13. If this results in swinging portion 11a 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 191:, which engages flat 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 19e provided on the electrode.

The igniter is connected to the high tensioncircuit of the transformer in any well known manner. Located at the low side of the hearth, prefeably opposite the ignite?, is a.v pair of recesses.

or circular channels 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-off 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 84a carried by plate 6| Channels 80 and 8| perform the highly important function of trapping any oil discharge which is not immediately ignited at the time the burner starts. This prevents a ilow 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-ofi mechanism to stop the burner motor. In the past some diiiiculty 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 on of this character.

With the novelconstructions herein disclosed, any oil accumulating in channels 80 and 8| during cold starts, and which is not immediately ignited, is under normal conditions burned oi during the ensuing normal operating cycle of the i burner, with the result that no oil whatever enters the trip bucket.

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 operate at extremely low 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

r seen in Figure 3, the channels are disposed in symmetrical, radiating relationship to ring 85 and are supported approximately at their midportions by wall 13. Although the channels may be secured to the flame rim, the grille assembly preferably merely freely rests upon the ame 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 in the particular small capacity unit illustrated, so as to cause the flame to pass outwardly along thechannels and then behind wall 13, and to maintain azone of rapid and eicient combustion between band 13 and shield 1S, and to also maintain the ilame rim at an eilicient fuel vaporizing temperature. Reversibility of the grille is particularly desirable 75 when the 'lower grades of fueloil are burned.

The .function of any grille is to assist mixing ofthe -r and oil proccted from the distributor head and to prevent the haine from lifting above the flame rim to a height where it will not heat the flame rim suiicie'ntly 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 21A; inches. With the rim in Asuch close proximity to the flinger tubes it was found liinpossible for the older type of grilles to properly mix lthe air and oil for complete and clean combustion without circulatinga large amount of the hot gases of the combustion. Excessive recircul- .lation is undesirable, especially in the small hot water heater because there may be many numerfA -ous cold starts, particularly during the summer season, and on a cold start'the'eifect of excessive recirculation is to cause an excessive ilow of cold,

fresh air, which at high velocity may retardl 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 suliicient volume to combust the fuel and at suiiiciently low velocity to avoid delaying ignition, as will be described hereinafter, and providing the grille assembly constructed as just described, which d e fleets the gases ofthe combustion ame behind the flame rim under al1 normal conditions, and using a shield 1 to prevent contact of the llame with the lower portionv of the coil, the apparatus performs with complete satisfaction.

Distributor The distributor comprises a motor and plumpv uting head 9 l. A pair of upwardly and outward? ly 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 wall T3, with sufficient 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 S, to which is welded a fan head or disc 9'5.

Secured to the underside of head 95 are a plurality of flanged blades 96 and Sl, 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 91 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 lthe air, which rendered ignif, t'io'n, particularly on acold start, extremely :dif-1 ficult. Further, in a small combustion chamber and hearth assembly as employed in the present construction, a high air velocity tends Yto induce excessive recirculation. The novel fan assembly just described overcomes this difficulty because the greater number of short pumping blades assures sufficient air for combustion v'vithout'r excess velocity, and by locating the distributor tubes leeward of- 'the velocity-blades-'thub's are maintains@ .out gf with the ,braise recirculated gases that are drawn the fan and are discharged along the leading faces of the blades Awith 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 is provided with a short lip or skirt 38, and the ends of the flinger tubes are located closely ad.- jacent the fau'couer, Both of these features cooperate to prevent the recirculated gases from heating and carbonizipg the oil ln the ends .of .the distributor tubes.

Shield 16 is important in the small sized illustrated, because in such unit a number` o'kf critical factors are presen-t. .although shields `of various types have -been before disclosed in the art the only functions were to ,Prever-it 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 L5 of the correct height it will deflect the hot gases- Oi recrulatien and amenities uvwardlr'emi away from the lower convclutipns of the coil 53 and very good control over the hearth terllpslaeA ture can be maintained, addition to realizingthe decided advantage of preventing direct con?. tact 0f the name W-itih the. 19H95 CQVQlilOQ 9? the coil.

The illustrated construction is e commercie! unit marketed by the assignee of this application and which has given complete satisfatiea in all fepecs.' The PPQr-*'ellt @.mligl .0i .th init are .as follows., whli are. Slifer; by War 0f ililutmw tion and not limitation. it heilig understood that some latitude is permissible, depending upon the size of the hearth, the speed of the fan and gther factors of the particular unit under consideration.

The hearth is approximately l0 inches in di ameter and shield 15 is spaced approximately 2 inches from wall 4I. Flame rim 'I3V is approxi-f mately 8 inches in diameter and one and one,- half inches high. while shield 'I6 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-eighths of an inch from the axis of rotation. Blades 91 are approximately one and seven?- eighths inches long, while blades 96 are approxif mately three-fourths of an inch in length.

In Figures 6 and 7 we have. illustrated a mod-i ied form of heating apparatus also formingpart of the invention. The major differences reside in the use of an embossed base, which automatically disposes the hearth at the proper inclination to elect drainage of oil, and a different form of overliow port, which is particularly useful where space does not permit use of the double groove constructionshown in Figure 2.

A base plate Blais secured in tight engagement with the`lower edge of the combustion chamber as before.` Hwever, in this' Yinstance the lower edge lies substantially in a horizontal plane. and the plate,l inwardly o f its clamping edges', is embossed or formed so as to present an inclined portion I0! to' which hearth supports 'Il are secured. This construction accordingly makes it possible to utilize a combustion chamber having a square lower edge and hearth suppgrtng legs of equal length, and yet supports th 'hearthA at the 'necessary inclination 't6 eiect proper drainage of overflow oil. Also, if desired, insulation retaining members |02 may be secured to legs 1|.

In this form of the invention a single oil drainage groove |03 is provided adjacent outlet 82a, and, as seen in Figure 7, the outlet is machined out at |04 to provide a sharp edge |05 over which the oil must discharge. We have found that, when using commercial grades of number 2 or number 3 fuel oil, the oil overiiowing over the hearth will build up in groove |03 and form a meniscus |05, as shown in Figure 7, to a depth of approximately one-sixteenth of an inch above edge |05 before overiiowing into opening 82a. As previously explained, any oil remaining in groove |03 after the burner is started will be consumed during the normal burning cycle, and the hearth will be dry when the burner is shut oif.

Accordingly, by using a sharp edge adjacent the outlet port, the oil will build up to a depth suiiiciently 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 eilicient 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 Figure l, the entire coil may be thoroughly cleaned.

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

The invention may be embodied in other speciiic 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:

l. In a liquid fuel burning apparatus having means defining a combustion chamber; a centrally apertured refractory hearth in said combustion chamber and having a fuel atomizing and vaporizing wall located adjacent its periphery against which oil and air are adapted to be projected by a distributing device located in the aperture in said hearth; means providing an outlet in said hearth adapted to be coupled to a burner shut-off mechanism; the upper surface of said hearth being so sloped as to cause liquid oil to drain along said hearth toward said outlet; and recess means in said hearth surface adjacent said outlet for accumulating a predetermined quantity of oil before flow to said shutoff mechanism occurs.

2. In a liquid fuel burning apparatus having means defining a combustion chamber; a centraily'apertured refractory hearth in said combustion chamber and having a fuel atomizing and vaporizing wall located adjacent its periphery against which oil and air are adapted to be projected by a distributing device located in the aperture in said hearth; means defining an outlet port opening upwardly into the oor of said hearth and adapted to be coupled to a burner shut-off mechanism, the upper surface of said hearth being so sloped as to cause any overflow oil to drain along said hearth toward said outlet port; and means defining a recess in said hearth in surrounding relationship to said outlet port for accumulating a predetermined quantity of oil on said hearth before flow to said shut-off mechanism occurs.

3. The liquid fuel burning apparatus defined in claim 2, wherein said hearth, between said recess and said outlet port, is provided with a substantially continuous sharp edge so located as to cause the accumulating liquid fuel to build up to a predetermined depth above the level of said outlet port before discharging from said recess into said outlet port.

4. In a liquid fuel burning apparatus having means defining a combustion chamber; a centrally apertured refractory hearth in said combustion chamber and having a fuel atomizing and vaporizlng wall located adjacent its periphery against which oil and air are adapted to be projected by a distributing device located in the aperture in said hearth; said-hearth having a plurality of substantially continuous upper surface recesses therein located one inside the other; and means dening a discharge port opening into the upper surface of the hearth inside the innermost of said recesses, and said port having its upper edge at a higher level than the bottoms of said recesses.

5. In a liquid fuel burning apparatus having walls defining a combustion chamber, a hearth supported in said combustion chamber; a fuel atomizing and vaporizing wall extending around the periphery of said hearth and spaced from the interior of said combustion chamber and adapted to have liquid fuel and air projected toward it for combustion adjacent the upper edge thereof; an annular shield ring supported on said hearth in outwardly spaced and surrounding relation to said wall and extending a substantial distance above the top of said wall; and a at narrow grill structure disposed within the confines of said shield ring comprising an annular member having a plurality of trough elements radiating outwardly therefrom, said trough elements resting on said wall to support said grill structure in the apparatus.

6. In a liquid fuel burner assembly adapted to be installed in a combustion chamber, a closure for the lower end of said chamber substantially centrally apertured to accommodate a rotatable fuel distribution head, a hearth mounted on said closure in surrounding relation to said head and having an annular upper surface sloping radially in opposite directions from its inner and outer peripheries, means defining a drain outlet port in said hearth at the lowermost region of said surface so that unburned liquid fuel deposited on said surface will drain toward said port, an annular ame rim surrounding said head mounted on said hearth in spaced relation to said head, an outer peripheral ange on said hearth spaced from said flame rim but within the connes of said combustion chamber, and an'annular shield ring secured t0 Said flange and upwardly into the combustion chamber. v,

mounted `on said hearth surrounding the aperture in said hearth and adapted to be impacted -b'y liquid fuel projected outwardly by a rotating fuel distributing head extending upwardly throughthe aperturein said hearth, means proi viding a d rai'nport on, one side of said hearth,

,means mounting said hearth in said chamber in suchinclined. relation tothe horizontal that liquid. fueldepozsited onA thehupper surface of said hearth will drain .therealong toward said port, and areces'sed hearth region about said drain port in the path' of liquid fuel. tending to drain into said port for accumulating .a predetermined sinall amount of it on the hearth surface before allowing .any ofhit to, enter said port, but overowing: into'saidpot when an excess ofvfluid felfainshsrsintoff 9.- Inthe liquid f uel burning apparatus dened clainifus'aid discharge V port being located tolviladthe.outer pai-tof said hearth, and means saidglhearth'linsuch inclined relation as to', cause ,liquidfuel to drain along said hearth 10a ,1n a burningapparatus, a, hearth apeitured .toaccommodatea Afuel projecting head 'and having a' low levl region toward which the upper surfac'- f said h" h1, slopes', said .low level region being formed vfllth a drain outlet port adapted to .be.' .coupled to V1a. burner -shut-ofi? vde- Vice, and a recessed hearth' region, about said drain outlet port ifi' the path f liquid fuel' tending to drainalong said. surface into said port for accumulating'r ,a predetrmined`-small amount of said liquid fueIHbefore' allowing any of itto enter4 said port, butoyerowin'g into Savidport when an excess of.,liduid fuel drains thereinto, said accumulatedl'iqiiid f uel in, A'Said means being exposed to .vaporizing heat and tending to burn off during normal operation of ,said apparatus.

MiLfroN A,A POWERS.. NOEL` HQ SUTTERFIELD.

REFERENCES CITED The following references are of record in the le of this patenti' UNITED STATS PATENTS Number ,Nfaie Date 1,886,675 Heathf..z Nov. 8, 1932 2,013,642 Binkly sept. 1o, 1935 2,029,859 o0zz1 Een .4, 1936 2,034,737 Appel' Mr. 24, 193,6 2,051,130 Cole Aug. 18, 193.6 2,064,080 Powers Dec. 15, 1936 2,094,764 Wi1SQn.'. f Q` L Oct. 5, 193.7 2,102,763 Suttereld Dec. 21, 193.7 2,104,691 Q01e,; ,qan. 4., 1938 2,117,781 Wilson Q May 17, 1938 2,130,471 Powersfn-.. Sept. 20, 1938 2,161,220 BeckettA June s, 1939 2,207,002 D 'L ".Q July 9, 1940

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