US2385782A - Automatic stoker - Google Patents

Description

Oct. 2,1945." M, T N 2,385,7821

' AUTOMATIC STOKER 7 Original Filed on. 9, 1939 8 s-heets sheet 1 Oct. 2, 1945.

w. M. FULTON AUTOMATIC STOKER Original Filed 001:. 9, 1959 8 Sheets-Shet 2 Oct 1945 w. M. FULTON 8 ,782 7 AUTOMATIC STOKER Original Filed Oct. 9, 1939 a Sheets-Sheet 5 Oct. 2, 1945. w. M. FULTON AUTOMATIC STOKER 8 Sheets-Sheet 4 igina ,1 Filed Oct. 9, 1939 v Oct. 2, 1945. w. M. I 'ULTON AUTOMATIC STOKER 8 Sheets-Sheet 5 Original Filed 001;. 9,v 1939 Och 2,1945; w, M Fug- N 2,385,782

AUTOMATIC STOKER Original Filed Oct. 9, 1939 8 Sheets-Sheet 6 Oct. 2, 1945. w FULTON AUTOMATIC STOKER Original Filed Oct. .9, 1939 8 Sheets-Sheet 8 Patented Oct. 2, 1945 AUTOMATIC STOKER Weston M. Fulton, Knoxville, Tenn., assignor to W.'J. Savage Company, Inc., Knoxville, Tenn.,

, a corporation of Tennessee -Original application October 9, 1939, Serial No. 298,651, now Patent No. 2,269,812, dated January 13 1942.

Divided and 24, 1941, Serial No. 403,929

this application July 17 Claims. ((31. 110-32) This invention relates to automatic stokers for burning solid fuel, and more particularly to the cross draft type of stoker such as that generally described and shown in my U. S. Patent No. 2,126,104, granted August 9, 193

Cross draft stokers of the types now known and used possess a number of objectionable features. These defects and shortcomings are due in part to the stringent requirements of the domestic field in which these stokers are widely used. Domestic stokers are required to meet conditions quite different frompower plant stokers. For example, domestic stokers are used principally in the heating of residences, small apartment houses, etc., where the heating load'varies with the weather and consequently is subject to very wide extremes. Noise and dust must be avoided. Further, domestic stokers are cared for either by the house owner or by a domestic servant, the vast majority of whomare not familiar with mechanical devices and consequently neglect the mechanical upkeep of the stoker. Powerplant stokers, on the other hand, operate under more uniform load conditions; are installed in,indus,- trial plants with other noisy machinery, need not be silent and are under the constant care of a skilled power plant engineer. Power plant stokers are usually installed at the time the power plant itself is installed, whereas the vast majority of domestic stokers are installed on heating plants of varying design that have been in service for a greater or less length of time with resulting installation difficulties not found in the power plant stoker.

Another objection to known stokers of the cross draft type is their inability to remain idle for protracted periods of time when the load demand drops to, ornearfzero, and then promptly resume normal functioning when the demand abruptly and drastically increases. When these stokers are standing idle it is necessary to admit an appreciable amount of air to the combustion zone to create a natural draft through the chimney, or smoke pipe to which the stoker is connected. Otherwise smoke and fumes arising from the incandescent fuel in the burner would escape around the access doors of the stoker and fill the furnace room and work their way up into the living quarters of the house'being heated. This natural draft produces slow combustion of the fuel in the stoker, and, if greatly prolonged, will consume all available fuel and the fire becomes very low. When demand is resumed and fresh fuel is fed into the stoker this fuel is consumed as fa'st as it is-fed to the stoker and the fire has great difiiculty in building up again to normal proportions. This objection'may be illustrated by reference to the shaker gratetype of stoker in wide use in which fuel is discharged by gravity from the feed hopper to'the shaker grate and moves slowly over the grate while being consumed. The rate of feed and rate of combustion are so timed that combustion will be completed as the moving fuel reaches the'discharge end of the shaker grate. If the load demand drops and the stoker remains idle for a protracted period of time, the natural draft required to carry fumes away will consume all the fuel at the lower end,

. of the shaker gratefthis fuel having already been partially consumed), and consequently this portion of the grate Willbe covered with dead ash.

When demand is resumed, all the cold air from the blast fan which passes through the'lower portion of the grate will find no fuel with which it may combine and will mingle with the hot gases rising from the burning fuel at the upper end of the grate, cooling these gases and reducing their heating effect. Furthermore, since the rate. of feed and rate of combustion are timed for normal working conditions under a fairly constant load; the feeding. device is now lacking in capacity to supply sufficient fuel for actual combustion plus a surplusv sufficient to again cover the lower portion of the shaker grate. Various devices such as, the so-called automatic air controls for adjuste ing the air supply to correspond with the thickness of the fuel bed have been producedrin an effort to cure this defect inthese stokers, but these devices have met with little more than indifferent success.

Another objection to known stokers of the cross draft type, to which the present invention pertains, is that they have hitherto failed to pro} vide ready access of air to that portion of the fuel lying against the opposing wall sectionsjof the combustion chambers. In stokers utilizing the cross draft principle the distance between the front and rear sections of the combustion chambers must be relatively small to maintain a relatively thin fire-bed, since in a thick fire-bed the temperature of combustion reaches such a high point that large, unweildy clinkers are formed in the combustion chambers, clogging the latter. and making ash disposal difficult. Hollow, water-cooled members in close proximitytoaeach other and in physical contact with the burning fuel have been used to rapidly conduct heat. away from the fuel and prevent the temperature. of the fire-bed is very thick since a region will still exist midway between the front and rear sections where high temperatures will prevail and objectionable clinkers will form. When a thin firebed is used the width of the front and rear sections of the combustion zone has been relatively large. Hence there are zones, or: pockets in the.

since the tendency of the air is to pursue a '1 straight-line course through .the fuel and the slight resistance to the progress ofv the air offered by the fuel in a relatively thin fire-bedis not sufficient to cause the air to diffuse in the burning zone. This results in unevenburning of the fuel bed where the latter lies against these front and rear sections which the air cannot reach invention is to provide a novel cross draft type of stoker in which more fuel is supplied to the burning zones than is required for the normal I operation of the stoker.

fuel, fusion and consequent sticking of the fuel in y the pockets referred to and arching of. the entire fuel bed in the combustion chambers.

Still another defect in known stokers of the cross draft type is that hitherto only gravity discharge of the ash has been possible. The presence of foreign matter in.the fuel has resulted in cloggingthe.ashdischarge intheabsence of positive mechanical means. for. forcing obstructions out of. the path of. ash flow.

.Another defect in known cross draft stokers is the .tendency of radiant heat to escape from the incandescent fuel through the openings of the inlet tuyeres causing -a substantialwa-ste of heat. Some smoke and. fumes: occasionally escape through the inlet'tuyeres as well.

Another defect in known cross draft-stokers is that fine particles of incombustible matter given off from the burning fuel .lodge in the passageways of the heater. .This. incombustible matter,

known'as fly-ash, isgreatly increased in quantity by theforced draft usually, provided .with these .stokers, No, satisfactory method has hitherto'beenl'devised forautomatically disposing of this fly-ash.

A. stillfurther defect oftheknown cross draft types, of, stokers is that a suitable amount offire travel between the burning fuel and the heating surface of the boiler. cannot .be .provided. To those skilled in the art it is well known that the flame. generated by burning fuel is composed of a mixture of hot gases which. are .rapidly undergoing chemical changes andthese changes proceed to completion only afterthe flame has travelled' a considerable distance away from the.

burning fuel. If these hot gases come .intofcontact with any relatively. cool .s'urface,-such...as the. crownsheet ofv alboiler, and.. are .thereby cooled below the temperature of ignition-of the Wasting fuel.

jurisdiction have a specified minimum distance between the stoker or burner and the heating surface of the boiler.

It is accordingly anobject of the present-in vention to; provide a novel cross draft. type of stoker which is uitable for general requirements,

particularly domestic, and which is wreadilvl adaptable for use with existing heating plants.

Another object of the present invention is to provide a novel. cross draft type of stoker which canafter longperiodsof idleness promptly resume normal operation when the heat demand is increased.

Another object of the present invention is to I for clarity;

Anotherand still further object of the present invention is to provide a novel cross draft type .of stoker in whichnovel means are provided for distributing the fuel to the burning zones and returning surplus fuel to the source of fuel supply.

Another and still further object of the present invention is to provide a novel cross draft of stoker which is silentin-operation, eflicient,*compact, relatively inexpensive to manufacture and install. and which may be operated without prior knowledge or training.

Other and further objects of the present invention will appear as the description thereof proceeds.

With these objects in view, an illustrative embodiment of thecross draft stoker of the present invention is shown in the accompanying drawings but it is to be expressly understood that :this embodiment of the present invention is shown in the. accompanying drawings and hereafter described for the purposes of illustration only and isnot to be construed as a limitation on the presentinvention. Reference should be had to the appended claims to determine the scope of the present invention.

In the accompanying drawings,

stokerjacket. broken away toshow the, front of the. stoker r .Fig..2 is aside elevation as seen from the left of the embodiment of the present invention shown in Fig. 1;

Fig. 3 is a view of the embodiment of the present invention shown in Fig. 1 asseen from above with the top of the jacket and the-top of -the'fuel scraper cut away;

1Fig..4 is a cross-sectional elevation on the line 4-4 of the embodiment of the present invention shown in Fig. 1;

. Fig-5 is a cross-sectional elevation of the embodiment of -the=present inventionshown in- Fig. 1 taken at right angles to the section ofFig. 4;

. Fig. Sis a sectional View on "theline' 6+6 of the embodiment of the present invention shown in Fig. 1-, the electric motor and fan being omitted Fig.-7-.is a sectional elevation of a novel fuel conveying mechanism suitable for use in conjunction with the embodiment of the present invention shown in Fig. 1; and I e Fig. 8 is an enlarged view of the clutch mechanismshown in Fig. 7.

. Referring now to the accompanying drawings for t k IS Of this. type to permit free exchange.

of water and steam between the boiler and stoker. Combustion of fuel takes place in the stoker 25 and the hot products of combustion pass through the stoker outlet 26 into the ash pit 36 of boiler 26 thence upward through the heating passageways of boiler 26 and out through the smokehood to the smoke-pipe. It has hitherto been the practice to apply forced draft to stokers of this type. In the present invention, aninduced draft is used. To create the desired induced draft an electric motor 33, supported on bracket 34 attached to stoker 25, carries the rotor of'a blower 36 (Fig. 3) on the end of the motor shaft. Said blower discharges air through pipe 36 into the air intake 39 of ejector 40 which is in communication through chamber with suction chamber 42. Pipe 4I extends from smoke-hood 3I to said suction chamber 42 of ejector 40 and the gases are delivered through pipe 32 to any suitable chimney or stack (not shown). Motor shaft 31 has pulley 43 keyed thereon and belt 44 transmits power from pulley -43 to pulley 45 which is keyed to shaft 46 of speed reducer 41 of any standard construction.

Referring more particularly now to Figs. 1 and 2, fuel hopper 60 is provided with lid 6| hinged at 62 and provided with a handle 63. A metal jacket, or covering, 64 surrounds stoker 25 and extends to the bottom 65 thereof to form a substantially air-tight closure around stoker 25. At the top of jacket 64, and in communication with the interior thereof, is vent pipe 66. Pipe 66 leads to any suitable outlet such as the chimney used with boiler 26; it may connect to ash pit 33 of boiler 26; or, as here shown, it may connect at 61 to smoke pipe 32. Jacket 64 has adjacent its top, and immediately above combustion chambers 68 (Fig. 4), two openings 69, which are provided with lids hinged at 1| and provided with handles 12. Each handle 12 has a round extension 13 journalled in lug 14 integral with lid 16. Extension 13 carries latch 15, which, when lid 10 is closed, can be rotated to engage reinforcing member 86. Each lid 10 is opened by rotating handle 12 to disengage latch and lid 18 can then be raised to the open position shown in dotted outline at the left in Fig. 4. This arrangement permits access to combustion chambers 68 for starting the fire in the stoker and gives access to the working'parts.

Referring now to Figs. 1 to 6, inclusive, it will be seen that the combustion chambers 68 of my improved stoker are built up of a plurality of hollow sections spaced from each other and secured together by a plurality of hollow nipples which are screwed into suitable threaded bosses or openings in each section. As shown in Fig. 67 hollow side sections III and H2 have mounted therebetween one or more hollow outside sections I I3 and an equal number of inside hollow sections I I4. Combustion takes place in the combustion chambers 68, inclosed by side sections 1 I I and H2, outside sections H3 and inside sections I I4, and the hot gases from the burning fuel pass out through the central chamber H6 formed by inside sections II 4. Outside sections H3 are identical in construction, being hollow to provide passages through which water may freely ciroulate and having their lower portions downwardly and inwardly inclined towards the middle of the burner so that said lower portions are closer at their lower extremities, as is apparent from Fig. 4, than at their upper extremities. The inside sections H4 are also hollow to provide passages through which water can freely circulate, and

is fitted a cylindrical member I29 suitably sehave ribs H9 formed integrallytherewith, the spaces I20 between ribs H9 constitutin tuyeres through which the hot gases of combustion enter said sections form companion tuyres with those formed by the inside sections H4.

Side section I I I has therein a cylindrical opening I21 surrounded by extension I28 into which cured thereto, by any convenient means here shown as by screws I30, and extending into chamber H6. Member I29 forms an outlet through which the gaseous products of combustion pass in their travel to boiler 26. Member I29-may be made of any suitable heat-resisting material such as fire-clay or any of the heatresisting alloys. Member I29 is so designed that the hot gases of combustion emerging from tuyeres I26 nearest opening I21 must travel to the opposite side of stoker 25 before escaping through open end I3I of member I29 to give the gaseous products of combustion a long path of travel and ample time in which the chemical reactions of combustion may be completed before the gaseous products of combustion come into contact with the relatively cool interior passageways of boiler 26. As member I29 is exposed to the hot gases of combustion emerging from tuyres I26 its outer and inner surfaces are maintained at high temperatures. The gases in contact with and surrounded by these surfaces will therefore be held at a temperature above the tem- 1 perature of ignition of the component elements of the gases untilthey emerge from opening I21. Adequate fire travel to insure complete combustion is thus provided by the present invention.

Inside sections H4 are V-shaped in cross section (Fig. 6) with the apex of the V pointing towards combustion chambers 68. Outside sections I I3 are also V-shaped with the apex of the V pointed towards combustion chambers 68. Sections H3 have no tuyre forming ribs. Hollow hubs 132 (Fig. 3 formed on sections H3 project a sufficient distance beyond the sides of sections'l I3 to form suitable spaces therebetween in which oscillating tuyre members I33 having upwardly and then downwardly inclined air pas.- sages I48, I41 (see Figs. 4 and 6) are mounted for reciprocation. As said oscillating tuyre members I33 and the means for operating the same have been fully disclosed in my application Serial No. 298,661 filed October 9, 1939, issued as Patent No. 2,269,812, January 13, 1942 to which cross reference is made, a detailed explanation herein is unnecessary.

Referring more particularly to Fig. 4, formed adjacent the lower ends of side sections III and H2 are plates I1I. Plates I1I are provided with offsets I12 having extensions I13. Also formed on sections III and H2 are lugs I14 designed to receive plates I15 positioned between sections I I I and H2, plates I15 having their upper ends supported by lugs I14 and their lower ends supported in offsets I12. Plates I15 catch any dust or ash which may sift through tuyeres I33 and direct this waste matter downward into the ash discharge. Suitably secured to plates HI are curved plates I16 which close the space between sections III and H2 and extend forwardly to a point adjacent the front of the stoker. Plates I16 deflectthe ash traveling downward from combustion chambers 68 into opening I 11 of a suitable ashpit I18. Plates I 16 are here shown gears 246 and 241.

secured to the .left sides: .(Fig. 4) of sections .II I

and H 2 but it isto be understood that plates I16 can be connected atthe right if desired. .Ashpit I18 would then be located near the left sideof Fig. 4, this feature rendering installation of the stoker more flexible.

As is best seen in Figs. 4 and 5, a suitable member I19 is spaced from.and covers the top of stoker sections II4 providing a suitable space I89 around it in which scrapers I8I may move with ample clearance. Member "I19 prevents fuel from accumulating in the space on top'of stoker sections II4.

1 Stokerside section III is provided with a hollow, water-cooled outlet 29 (Figs. 5 and 6) .for conducting the hot gaseous productsof combustion from outlet I21 and member I29 into boiler 26. Outlet 29 is'of suitable cross section here shown as rectangular and is downwardly directed to deliverthe hot gases of combustion at, or near,; the bottom of boiler 26, asmay be seen in Fig. 1.. Outlet 29 has vertically disposed ribs I64 and I85 suitably secured to opposite walls I92 and I83. to

which are attachedcross members I86 and I81 forming dust-collecting passages I88 and I89 'therebetween. Cross members 186 and I81 have their upper edges turned outwardly towards the center of outlet 29 and are suitably separated from each other to. form traps by which fly-ash and dust particles may'enter passages I88 and I89. Passages I88 empty into a suitable passage I96 which in turn empties into dust-collecting chamber I9I. Passages I69 are divided into two branches I93 (Fig, 5) which straddle outlet 29 and dischargeinto dust chamber -I 9I. A suitable passage I94 connects dust chamber I9I and outlet 29 The area of passage I94 is greater than the area of passage I96. 'When-induced-suction or draft is applied to outlet 29 through boiler 26 towhich it is connected, gases can escape from dust chamber I9 I through passage I94 faster thanzthey can enter through passage I96 producing a reduced pressure inside chamber I9I. Mounted in chamber I9l is conveyor screw I95 journalled. at I96 in wall I91 of chamber I9l and .havingits discharge end I98 loosely mounted ma suitable cylindrical hub I99 opening into ash discharge passage 266. End I98 of screw I95 terminates short of the entrance of hub I99 into ash discharge passage 266 to permit a suitable quantity ofdust or fly-ash to accumulate in hub I99 to form a. seal or plug to prevent air from being drawn into chamber I9I through. ash discharge Referring to Figs. 3, 4 and 5, a second reduced speed. shaft 2I3. of speed reducer 41 passes through jacket 64 and is journalled in bracket F31,fixed to top member 238 of fuel hopper 66. Suitable packing means may be used to insure a gastight .joint where shaft 2I3 passes through jacket64. Secured to shaft 2I3 is bevel pinion 246 Whichmeshes with pinion 2 fixed to drive shaft 242 of conveyor screw 243. Spur gear 244 likewise fixed to conveyor shaft 242 meshes with idler gear 245- which in turn meshes with spur Gear 246 :is fixed to drive shaft248 of secondary conveyor screw 249. The general construction and operation of conveyor screws 243 and 249 here shown and generally described is the same as that shown and describedin detail in my copending application SerialNo. 253,930, filed January 31, 1939, for Improvementsin feeders. A spider frame 266 has four arms 26 I secured to the lugs 262 formed on side sections III and H2. 'Fixed to spider frame 266 are studs 263 to which.arejournalle'd sprockets 264 and 265. Spur gear 241 is fixed to shaft 266 which rotates in its stud 263 and carries sprocket 264 fixed thereto. The other sprockets 265 turn idly on their studs 263. Sprocket 264 drives sprocket chain 261 and sprockets 265 support and stretch chain 261. Chain 261 carries a plurality of scrapers I8I pendant therefrom. 1

As is well known to those skilled in the art to which this invention pertains, stokers of this type are controlled by an. electric switch in turn controlled by any convenient means suchas a thermostat located in the building being heated.

Assuming that the above described embodiment of the present invention is set up as above described, to place it in. operation 1ids'16 of jacket 64 (Fig.5) are opened andpieces ofignited ma terial (paper, excelsior, Wood'shavings, etc.) are dropped into combustion chambers 68 followedby wood kindling, after which coal (or other solid fuel) is supplied with a shovel until chambers 68 have been filled up to the level of the lower edges of scrapers I8l. Lids 19 are then closedand secured by turning handles 12 to rotate latches 15 into engagement with members 86. Electric motor 33 is then started putting blower 36 intooperation and closing damper 92 in vent pipe 66 and openings dampers I66 in the lower sides of jacket 64. The air suppliedthrough air duct 36 from blower 36 to ejector 46 produces an induced draft or suction'in smoke-hood 3 I, in boiler 26 and in stoker 25 causing air to be'drawn in through damper openings I66, through tuyeres I33 through the burning 'fuel in chambers 66, and causing the hot gasesof combustion to be drawn through tuyeres I26, 26, through cylindrical member I29 and through outlet member 29 into boiler 26 as indicated-by arrows-in Figs. 4, 5 and 6. This vigorous indraft of air through the stoker causes the fuel in combustion chambers 68 to ignite rapidly until combustion is tak ing place throughout combustion chambers 6S up to the zones indicated by dotted lines 216 (Fig. 4). As there are no inlet and outlet tuyeres above the zones indicated by lines 219 the fuel in this space receives insufficient air to support combustion. Particles of dust, or fiy-ash,

that may be held in suspension in the hot gaseous products of combustion are thrown out of the gaseous stream in turning the reverse curve in outlet member 29 at high velocity by the action of centrifugal force and are caught by the outwardly protruding edges of cross members I86 and I81 and deflected through the passages between these cross members into the passages I86 and I69. The reduced pressure in dust chamber I9I causes the particles thus trapped to'b'e drawn or sucked through passages I99 and I93 into dust chamber I9i. At the same time that electric motor'33 starts blower 36 it drives pulley'45 of 7 speed reducer 41 through belt 44 driven by pulley 43 secured to motor shaft 31.

Thereby the tuyeres I33 are oscillated from cranks 232 and 233 as more particularly explained in my application Serial No. 298,661.

positions relative to the fuel. As the fuel is worked downward in chambers 68 and combustion proceeds the fuel is reduced to ashes and its volume is reduced.

Because stoker sections 113 are V-shaped in cross section the incoming air in passing through tuyeres 133 which are likewise V-shaped in cross section is allowed to spread laterally before it reaches the fuel in combustion chambers 68. The V-shaped cross section of center stoker sections 114 allows the gaseous products of combustion to converge after passing through the fuel in combustion chambers 88 before entering chamber 116. Air is therefore conducted to every portion of the burning fuel in chambers 68 preventing the formation of pockets of unburnt fuel and increasing the efficiency of the stoker.

Simultaneously with the operations just described, reduced speed shaft 213 (Fig. rotates bevel pinions 240 and 241 and rotates conveyor screws 243 and 249 which in turn elevate fuel from'hopper 60 and discharge it into the space 180 at the top of the stoker. This fuel is then picked up by scrapers 181 and distributed uniformly around the space 180, scrapers 181 being driven by sprocket chain 261, sprocket wheel 264, and gear wheels 244, 245 and 241. The speed of shaft 213 is so adjusted with respect to the gear ratios that conveyor screws 243 and 249 will supply fuel to stoker 25 faster than stoker 25 can consume it. The surplus fuel not consumed is carried around space 180 by scrapers 181 and discharged over wall 336 (Fig. 3) back into the hopper 60. When the stoker of the present invention remains idle for prolonged periods of time the fuel in space 180,; above the dotted lines 210, serves as a reserve to replenish the fuel consumed by the slow combustion in combustion chamber 68 resulting from natural draft, and as this reserve is slowly consumed the fuel level in space 180 drops down towards dotted lines 210 When demand for heat is resumed and-the stoker is again put into operation conveyor screws 243 and 249 supply fuel faster than it can be consumed and space 180 is quickly re- .8

filled and the fuel level'is brought back up to the bottom edges of scrapers I 81, after which the surplus fuel is again discharged back into hopper 60, as described. It is to be understood that while in the preferred embodiment of the present invention the surplus fuel is returned to the hopper it may be disposed of in any other way desired as for example by discharging it into a sep arate bin, or hopper, provided for that purpose.

In some installations and particularly for domestic uses it may be desirable to equip stokers of the present invention with a bin feed rather than providing a fuel hopper 60. In such an installation fuel is fedto the stoker directly from any suitable bin which may contain the full seasons supply of fuel and which isusually constructed as an integral part of the structure of modern homes. While any suitable type of binfeed may be used in conjunction with the stoker of the present invention a' preferred bin feed is shown and illustrated in Figs. 7 and 8. As-is there shown, stoker 25 is suitably mounted on the floor 211 of the conventional boiler room having a well 212 of relatively small capacity sunk below fioor 211 and lined with any suitable material such as concrete, sheet iron or the like.

-Fuel is fed into well 212 from a suitable large capacity bin 214 by any suitable means here shown as conveyor screw 215 installed in a suitable trough-216 located beneath fioor 211. Bin- '303 of spring 302 214 may be of suitable design here shown as 'having a vertical wall- 211, an inclined wall 218 and provided with a suitable opening 219 through which fuel flows by gravity to the intake end of screw 215. Trough 216 is closed at the intakeend by member 289 having a hub 285 in which conveyor screw 215 is journalled. Well 212 is provided at its lowest point with a recess 286 carryingjtherein a bearing plate 281 in which conveyor screws 243 and 249 are journalled. Conveyor screws 243 and 249 are enclosed within a sheet metal casing 288 reinforced at its base i by angle iron 289 suitably secured thereto as by rivets 290 which likewise secure bracket 291 to casing 288. Bracket 291 extends outwardly and downwardly and terminates in a suitable hub 292which provides a bearing for screw 215. A sprocket 293 is secured to screw 215 and is driven by sprocket chain 294. Shaft 213 is extended beyond bracket 231 and has mounted thereon the cone section 295 of a suitable cone clutch. A key fixed to shaft 213 fits loosely in a suitable 'keyway in cone section 295 to rotate cone sec- .tion 295 with shaft 213 but permits free lengthwise travel of cone section .295 on shaft 213. Shaft213 is of reduced diameter at, 291. Mounted loosely on section 291 is sprocket 298. Secured to sprocket 298 is the concave section 299 of thecone clutch, and secured to the opposite side of sprocket wheel 298 is hub 300. Secured to hub 300 is end 391 of coil spring 392. End engages pin 394 projecting from grooved pulley 395. Hub 300 is of reduced diameter at 306 and is threaded at 301 to carry pulley 305 which is threaded loosely thereon. Bracket 231 is provided with a suitable hollow cylindrical hub 308 to slidably receive hollow hub 309 of transverse member 310. Hub 309 slidably supports rod 311 to which is secured segment 312. Segment 312 engages the groove of grooved pulley 305. Secured to the upper portion of segment 312 is U-shaped member 313 made of tempered spring steel or other suitable resilient material and having arms 314. Arms 314 of member 313 are bifurcated to receive pins 315 on which are pivotally mounted toggles 316. Toggles 316 are pivoted together on pin 311. Link 318 is likewise pivoted on pin 311 and its opposite end is pivoted at 319 to member 319.. Arms 314 of member 313 exert a strong pressure against toggles 316 tending to press toggles 316 inward towards pin 311. Transverse member 310 engages a suitable groove 320 formed in the cone section 295. Rod 321 pivotally engages a stud 322 projecting from pulley 305 and extends downwardly inside casing 288 and passes through and is guided by a bracket 323 suitably secured to casing 288. Below bracket 323 rod 321 divides into two branches 324 which straddle bracket291 and carry a shoe 325. A suitable opening 326 is provided in top member 238 to permit rod 321 free movement in all directions. sprocket chain 294 passes through opening 321 in member 238 and engages sprocket wheel 298.

When clutch member 295 is in engagement with companion clutch member 299, the latter, together with sprocket 298, hub 300 and pulley 305 will be rotated by'shaft 213, pulley 305 being driven by the engagement of spring 302 and pin 304. Rotation of sprocket; 298 drives sprocket chain 294 and rotates sprocket 293 rotating conveyor screw 215 and feeding fuel from fuel bin 214xinto well "212.- At the same time rod 321 is being reciprocated by the rotation of pulley 305. The speed of conveyor screw 215 is adjusted to left (as seen in Fig. '7). Mov eiri'ritof pulley 395 to the left will-carr segme t m to the left and draw spring member 313 to the left-link 318 meanwhile holding pin 3|! stationary until pins 3 l 5 pass slightly to thelft of pin 311 whereupon the end thrust exerted by spring 3l3 against toggles3l6 will snap piii 3l'l to the right forcing member 350 and cone section 295 to' the right disengaging the clutch. Pulley 305, hub 3UP), sprocket 298 and clutch member 295 are new stationary while shaft 253 continues to rotate and .drive conveyor-243; The resilience of snring' 302 and the load on sprocket 298 are so nroi'i'ortiond thatthereacti'on of string 302 against bin 304 of pulley 3a5'wi11 not be sufficient to drive sprocket 298 in the reverse "direction when cone section 235 is disengaged. .A's conveyor 243 gradual-l5" exhausts the supply of fuel in well 212, the't'op of the fuel pile willi'drop from beneath sl'i'oe325 until rod 32| is free to reciprocate. Spring 302 will now,rotate 'pulley 395 in a counterclockwise direction as'seen' in Fig. 8 and screw threads 30'! will carry pulley 305 tothe right to reverse the cycle of operations above'd'escribeil; engage the clutch elements 295 and 299 and drive conveyor 215 a i It will now be apparent that the" bre'sent i'n vention prov-ides a'nbv'el cross'draft type of stoker which is particularly suited for domestic installation; which is silent, efficient, compact; relatively inexpensive andiflexibie in installation; which can, after periods of idleness, prompuy resume normal operation; in vs'rhich combustion supporting gases reach every portion of the burning zon'e to reduce the formation of ashes and clinkerin-g in which positive means are provided to assist the gravity discharge 'of ash; and in whichautomatic means are'prcvided for r'e'm'ovi ng entrained rgart-icles in the gases of eo'rneusueh. The present invention further provides a novel pross draft typeof ,stoker' in which a suitable vamount of fire travelis providd'to insure 'comp1 combustion of the gases of combustion; in wh ch-more fuel is fed to the burning zones than is required for the normal operation of the Stoker" and in which novel means are provided in distriputin the fuel to the burning Zones.

application is a division of my application :Serial No. 2 95,6 6l ijled OctoberQ, 1939, issued as get enem 2,2695812, January 1-3, 1942, for Automatic stokers q Brovisions, herein idisclos'ed con-i lcernle'clwith theflow of fumes and 'air from and thr oug h the stokler, both when the Stoker is idle fah'cl "when it is operation, are claimed in a sep ate divisijqn of my aforesaid anp-lication.

vWhat s q aimedisa T1 in a'cros draft stoker, in combination with 7 a combustion chamber, means for r aintairiing -g body of 'fuel in said fchamber durbu stionlalnd a source of solid fuel, fuel charn her said fuel feedi-ng means being ted -tq supgly fuel to said chamber at a F5 n exceiss o i the rate atwhich the fuel is normally consumed in saidfchamber, said comlou'stion chamber having a fuelrdischarge opening 3 'fi eans fcr feeding, said ,fuel to the top hosed above meme in eam fueI i'Tec'iVin' a the normal level of n ielin saia chamber; fuel distributing me ns for smearing-brie fuel del vered'to said cha'rirb'i eri weer he bod'y offful in said chamber, said distribiit means emg lioii'zemany aligned with said ripeningaha movable into adjacency thereto to'iemeve surpms fiiel frofn the top of said member when said chamber is full; and motive means for drivingf said fuel feeding and said fuel distributing eans; M In a cross draft Stoker, in combination with walls iiidvidiilg'a con'iloii sti'on cl'iai'r iber'; meafi for maintaihing'a body or fuel insaid' member urin'g combustion and. a source of solid fuel disposed be ow the top of Said diameter; liiflfedi hg' means for elevating-said fuel to the top of said chainber, said fuel feeding means being'constructed to elevate fuel to said chamber at a rate 'ke'ssof the rate at which the fuel is nbrmanyeensumed at said chamber through said openin when said chaii'lber' is run; and inijtive Inails or driving said fuel feedi'ng and sa-id'- fue1 di's'tr-iloutiiig means. 7

3-. In a cross draft Stoker, in en lbihatio n with inner and outer waiisproviaea with tu yi'es t0 form 'a combustion chamber; said wens extending 'upwardiy ebeve said. uteres to provide a feel receiving chamber above the zone of burning ffiljel for dame-rin fuel to the top bf the fuel in said receiving chamber, means in Said fuel receiving chamber for spreading the fuel delivered by said fuel feeding with'bubstei'itial unifo if rrfit y Over the top or the-fuel in said-receiving chamber; and motive means for ol-rii'ring both of said fu'el f'ed in-g metres and Said fuel spreading 4. In a cross draft striker, in eombinetienwith a source of f ueL ib'aded exterior and interiorwalls defihihg abombustioh chamber, 'sai'd'ekt'e'iiol and 'interior'walls having openings for the ingress of combustion air and egressbr productser combustioii, said ingress and egress openin s defining "a fuel bur'nihjg' zone 'said combustion chamber and said and outer wens extending above said openings to' define a fuel receiving zone above said fuel burning "zone, fuelleediilg means for elevating fuel to the-12015 of the 'ful said fuel receiving/tone; fuel 'sbibadih'g means d'iS- n'e and movable over the fuel se u i wing zb'ne ior 'evenry' distributingt e dliifefe'd rueljeh the top 'Of the fuel in sai'dici'i ifl g zone; motive means-m uni: g both-saw fuel feeding means and said fuel siireiding means; l 5. In a cross draft stbker, in combination 1th spaced exterior and interior walls definin a combustion chamber; "said 'eitei'idi and interior walls having openings for the aggressor co'nib'u'stion air and egress 'or roducts of'combus'tion,

Said ingress and egressbbenings defining drum burnin zone in said combustion member and said inner and outer walls -e'X'te'ridii r-i-g above s d openings to 'defin'e aful receiving zone above-said fuel buming- Zone, fuel feeding 'file'al'l for' delive'ring fuel to the 1151) Of the fue1 1h aid fii1 reeeixiiiig zorfe, fuel 'snrea'ding ine'ansiactingon in said combustion ch'ai'nbehiuel feeding ineans the fuel delivered to the top of the'fuel in said fuel receiving zone for evenly distributing the delivered fuel on the top of the fuel in said receiving zone, said fuel spreading means including scraping means and driving means for said scraping means for moving said scraping means said ingress and egress openings defining a fuel 1 burning zone in said combustion chamber and said inner and outer walls extending above said openings to define a fuel receiving'zone above said fuel burning zone, fuel feeding means for delivering fuel to the top of the fuel in said fuel receiving zone, fuel spreading means acting on the fuel delivered to the top of the fuel in said fuel receiving zone for evenly distributing the delivered fuel on the top of the fuel in said receiving zone, said fuel distributing means including a plurality of scrapers, an endless flexible drive element carrying said scrapers and disposed horizontally, means for driving said drive element through a closed path whereby said scrapers are circulated to level the top of the fuel in said fuel receiving zone, and motive means for driving both said fuel feeding means and said fuel spreading means.

7. In a cross draft stoker, in combination with exterior and interior walls provided with ingress openings for combustion supporting air and egress openings for products of combustion, said openings defining a combustion supporting zone and said Walls extending above said combustion supporting zone to define a fuel receiving zone from which fuel descends by gravity to replenish the fuel in said combustion supporting zone, means for feeding fuel to the top of said fuel receiving zone, said fuel feeding means being constructed to supply fuel to said fuel receiving zone at a rate in excess of the rate at which the fuel is normally consumed in the combustion supporting zone, means movable substantially horizontally through a closed path and acting on the fuel delivered by said fuel feeding means for distributing the received fuel evenly on top of the fuel in said fuel receiving zone, a fuel discharge opening communicating with said fuel receiving zone at the normal fuel level therein, said fuel distributing means moving into adjacency to said opening to displace therethrough the excess fuel when said fuel receiving zone is full, and common motive means for driving said fuel feeding means and said fuel distributing means.

8. In a cross draft stoker, in combination with a source of fuel, exterior and interior walls provided with ingress openings for combustion supporting air and egress openings for products of combustion, said openings defining a combustion supporting zone and said walls extending above said combustion supporting zone to define a fuel receiving zone from which fuel descends by gravity to replenish the fuel in said combustion supporting zone, means for elevating fuel from said source to the top' of said fuel receiving zone, means movable horizontally through a closed path for distributing evenly the fuel delivered to said fuel receiving zone by said elevating means, said elevating means being constructed to deliver fuel to said fuel receiving zone at a rate in excess .oflthat at which the fuel is normally consumed :in the combustion supporting zone, means communicating with said fuel receiving zoneadjacent the path of said fuel distributing means and extending downwardly to said source of fuel for returning excess fuel to said source by gravity, said fuel distributing means operating when said fuel receivin zone is full to. moveexcess ,fuelin said zone to said fuel returning means,; and a common motivemeans. for, driving both of'said fuel elevating means and said fuel distributing means. .7 I r J 9. ,In a cross draft stoker, in combination with fuel, supply means, exterior and interior-walls provided with ingress openings. for combustion supporting air and egress openings for products of combustion, said openings defining a combustion supporting zone and, said walls extending above said combustion supporting zone to define a fuel receiving zone from which fueldescends by gravity to replenish the fuel in said combustion supporting zone, means for feeding fuel to the top of said fuel receiving zone, said fuel feeding means being constructed to supply fuel to said fuelreceiving zone at a rate in excess ofv the rate at which the fuel is normally consumed in the combustion supporting zone, means movable substantially horizontally through a closedpath and acting on they fuel delivered by said fuel feeding means for distributing the received fuel evenly on top of the fuel in said fuel receiving zone, a fuel discharge opening communicating with said fuel receiving zone at the normal fuel level therein, said fuel distributing means moving into adjacency to said opening to displace therethrough the excess fuel when said fuel receiving zone is .full, common motive means for driving said fuel feeding means and said fuel distributing means, and means for discontinuing the operationpf said fuel supply means whena predetermined Y excess of fuel has, been supplied thereby.

10. In a cross, draft stoker, in combination with ,fuel supply means, exterior and interior walls provided with ingress openings for combustion supporting air and egress openings for products of combustion, said openings defining a combustion supporting zone andsaid walls extending above said combustion supporting zone to define a fuel receiving zone from which fuel descends by gravity to replenish the fuel in said combustion supporting zone, means for elevating fuel from said supply means to the top of said fuel receiving zone, means movable horizontally through a closed path for distributing evenly the fuel-delivered to said fuel receiving zone by said elevating means, said elevatingmeans being constructed to deliver fuel to said fuel receiving zone at a rate in excess of that at which the fuel is normally consumed in the combustion supporting zone, means communicating with said fuel receiving zone adjacent-the path of said fuel distributing means and extending downwardly to said supply means for returning excess fuel to said supply means by gravity, saidfuel distributing means operating when said fuel receiving zone is full to move excess fuel in said zone-to said fuel returning means, a common motive means for driving both I of said fuel elevating means and said fuel distributing means, and means for discontinuing the operation of said fuel supply means when arpredetermined excess of fuel has beensupplied thereby.

11. In a cross draft stoker, in combination with inner and outer walls provided with tuyeres to form a combustion chamber, said walls extending upwardly abovesaid tuyeres to provide a fuel receiving chamber above the zone of burning fuel in said' combustion chamber, fuel feeding means for delivering fuel to the top of'the fuel in said receivingchamber, 'means for spreading the :fuel deliveredwby said fuel feeding means with. substantial uniformity over the-top. of. the fuel in said receiving chamber, said fuel feeding means being constructed tofeed fuel to the top of said receivingoha'mber ata rategreater than that at which the fuel is normally consumed in said combustion zone, said receiving chamber having a fuel dlscharge'opening at the normal level-of the fuel therein and said fuel spreading means moving-into adjacencyto said opening to displace therethrough' excess fuel from the top of said chamber when the same is full, and motive means 'for'driving both of said fuel feeding means and said-fuel spreading means.

' 12.- In: a cross draft stoker, in combination with a source of fuel; spaced exterior and interior walls defining a-combustion chamber, saidexterior-and interior walls having openings for the ingress of combustion air and egress of products of combustion; said ingress and egress openings defining a fuel burning zone in said combustion chamberand said inner and outer walls extending above said openings to define a fuel receiving zone above said fuel burning zone, fuel feeding -means for elevating fuel to the top of the fueljin said fuel receiving zone, fuel spreading means acting on the fuel delivered to the top of the fuel in said fuel receiving zone for evenly distributing the delivered fuel on the top of the fuel in said receiving zon'e, said'fuel feeding means beingconstructed to elevate fuel to the top of said receiving zoneat a rate in excess of that at which the fuel is normally consumed in said combustion supporting zone, means communieating with said receiving zone and extending downwardly to said .source'for returning fuel to said source by" gravity, said fuel distributing means moving into adjacency to the inlet to said fuelreturning means and operating when said receiving zone is full to remove excess fuel from the top of said zone to said fuel returning means, and motive means for driving both said fuel feedin'g'means and said fuel spreading means.

7 1 3. In a cross draft stoker, in combination with interior walls defining a central chamber, means for-"conducting products of combustion from said exterior walls spaced from said central chamber, interior walls, said'exterlor and interior walls being-respectively provided with ingress openfor combustion supporting air andiegress openings for products of combustion, said walls defining a combustion chamber with said openings defining a combustion supporting zone therein and said walls extending above said combustion supporting zone to define a fuel receiving chamber from which fuel descends by gravity to replenish the consume'd fuel in said-combustion supporting zone, fuel feeding means for supplying fuel to the'top of said fuel receiving zone, :fuel spreading meansmova-ble horizontaflly through a closed path for leveling the fuel" in sai'd' fuel receiving chamber, and means for driving said fuel spreading means from said fuel feeding means. I

14. In a cross draft stolr'er, in Golf-1 61 with-a source o'ffucl, interior walls-den I central chamber, means for conducting products *of combustion from cen tral chambenexterio'r' walls spaced fron lsaid interior vavails, said exterior and interior walls being respectively provided with ingress openings for combustion supporting'air and egress openings for products of combustion, said walls defining a combustion in said fuel receiving chamber'the fuel delivered bysaid fuel elevating means, means communi cating with said receiving zone adjacent the path of said fuel distributing means and extending to said source for returning fuel to-said source, said fuel distributing means operating to remove excess fuel from the top of said-fuel-receiving chamber to said fuel returning means, and means for driving said fuel distributing means from said fuel feeding means.

15. In a-cross'draft stoker, in combination with interior walls defininga central member,

means for conducting products of combustion from said central chamber, exterior walls spaced from-said interior walls, said exterior andinterior walls being respectively provided with in- -gress-openings for combustion supporting air and egress openings for products of combustion, said walls defining a combustion chamberwith said openings defining a combustion supporting zone therein and said walls extending above said combustion supporting zone to define a fuel receiving chamber from which fuel descends by gravity to replenish the consumed fuel in said combustion supportlngzone, means for feeding fuel from said source to the top of said fuel receiving zone, fuel distributing means movable horizontally through a closed path for spreading at the top of the fuel in said fuel receiving chamber the fuel delivered by sa-idfuel feeding means, said 'fuel feeding means being constructed to feed fuel at a rate in excess of that at which fuel is normally consumed in said combustion supporting zone, means communicating with said receiving zone adjacent the path of said fuel-distributing means and extending to said source for returning fuel to said source, said fuel distributing means-operating to move excess fuel from the top of said fuel receiving chamber to said fuel returning means, and means for driving said fuel distributing means fromsaid f-uel feeding means.

16. In a cross draft stolzer, in combination with a source of fuel,- interior walls defining a central chamber, means for conducting products of combustion from said central chamber, exterior walls spaced from said interionwa'lls, saidexterior and interior walls being respectively provided with ingress openings for combustion-supporting air and egress openings for products of combustion, said walls defining a combustion chamber withsaid openings defining a combustion supporting "zone therein and "said walls extending above said combustion'supporting zone to define a fuel'receiving chamber from which fuel descends by gravity to replenish *theconsumed fuel in said combustion support- -ing zone, means for elevating fuel from said source to the top of said fuel receiving chamber, S37E61 elevating means being constructed to del iver fuel to said fuel receiving chamber at "a rate excess of that at which said fuel-is norexcess fuel is removed from said chamber by said distributing means, and means for driving said distributing means from said fuel elevating means.

1'7.'In a cross draft stoker, in combination with a source of fuel, interior walls defining a central chamber, means for conducting products of combustion from said central chamber, exterior walls spaced from said interior walls, said exterior and interior walls being respectively provided with ingress openings for combustion go supporting air and egress openings for products of combustion, said walls defining a combustion chamber with said openings defining a combustion supporting zone therein and said walls extending above said combustion supporting zone to define a fuel receiving chamber from which fuel descends by gravity to replenish the consumed fuel in said combustion supporting zone, means for elevating fuel from said source to the top of said fuel receiving zone, said elevating means being constructed to deliver fuel to said fuel receiving chamber at a rate in excess of that at which said fuel is normally consumed in said combustion supporting zone, means movable horizontally through a closed path and disposed at the topof said fuel receiving ,zone for acting on the fuel delivered by said fuel elevating means and distributing the same evenly over the top of the fuel in said fuel receiving zone, means communicating with said receiving zone adjacent the path of said fuel distributing means and extending to said source for returning fuel to said source by gravity, said fuel distributing means operating to move excess fuel from said receiving chamber to said fuel returning means, and means for driving said distributing means from said fuel elevating means.

WESTON M. FULTON.

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