US2393710A - Automatically fed furnace - Google Patents

Description

vJan. 29, 1946; H. w. SANFORD ET A-L 4 2,393,710

' AUTOMATICALLY-FED FURNACE Filed Dec. 8, 1941 8 Sheets-Sheet l I 77 ,l A f/ BB f 2;.

R I v My Jan. 29, 1946. H W. SANFORD Em; 3,7

AUTOMATICALLY FED FURNACE 'Filed Dec. 8, 1941 8 Sheets-Shet 2 Jan.- 29, 1946. 'H. w. SANFORD ET AL 2,393,710

' AUTOMATICALLY FED FURNACE I Filed Dec. 8, i941 8 Sheets-Sheet 5 A Erica/vans Jan. 29, 1946.

H. w. SANFORD ET AL AUTOMAT I CALLY FED FURNACE Filed Dec. 8, 1941 8 Sheetsl-Sheet 4 Jan. 29, 1946. H. w. SANFORD ET AL ,3

7 AUTOMATQECALLY FED FURNACE Filed Dec. 8, 1941 s She ets-Sheet '5 [W F g By Q/ H. W. SANFORD ET AL AUTOMATICALLY FED FURNACE Jan. 29, 1946.

Filed Dec. 8, 1941 v 8 Sheets-Sheet 6 Patented Jan. 29, 1946 UNITED STATES PATENT OFFICE:

.2,39s,71o. AUTOMATICALLY FED FURNACE Hugh WQSanford and Alfred FfSanford, II, Knox'v'ille, Tenniys'aid Alfred F. Sanford, II, asslgnor to said liu'gh W. Sanford h i Application. December 8, 1941, Serial No. 422,188 V 33 Claims; (cl. 110-32) The invention relates generally to furnace structures adapted for the burning of solid fuel and primarily seeks'to provide a novel furnace structure embodying a longitudinal fire pot open or openable at one end for ash and clinker discharge, reciprocable'means for positively forcing fuel and ash along the fire pot toward said discharge end, means for feeding charges of fresh fuel so that a column of fresh fuel will reach approximately to the bottom or grate of the combustion chamber, and in front of and adjacent to the forcing means, power means for operating the fuel feeding means and-theforcing means, and means for so timing andcontrolling the operation of the fuel feeding means and the forcing means as to meet all heat demands and yet assure against burning out of the fire, the discharging of any substantial quantity of unburned fuel with the ashes, and to prevent the heat waste that occurs when ashes are burned into clinkers.

An object of the invention is to provide in a furnace of the character stated a dual timing control effective to automaticallyprovide a predetermined definite number of fuel charge feedings in a given interval of time for maximum combustion operation of the furnace, and toprovide a variable predetermined lesser definite number of fuel charge feedings in a like interval of time for idling operation of the furnace.

Another object of the invention is to pr-ovide a furnace embodying a dual timing-control of the nature stated including two fuel-charge feed timing devices and thermostatic or pressure control means for rendering said devices selectively effective according to heat: demand.

Another object'of the invention is to provide a furnace of the character stated in which the dual timing controls and additional control meansare so cooperatively arranged that the latter will dominate control when a fresh fire is being started and will cause continuous fuel chargefeeding until a predetermined congestion of fuel mass is established in the fire pot, after which normal control will be taken over by said dual timing controls and maintained thereby until such time as rapid fuel combustion may have reduced fuel mass congestion to a predetermined minimum at which time continuous fuel charge feeding will again be temporarily occasioned.

Another object of the invention is to provide a furnace of the character stated in which said additional control means includes a novel door structure yieldably obstructing discharge of ash and clinkers, and control switch means actuated by movement of thedoorr g Another object oflthe invention is to provide a furnace of the character stated in which is embodied a fire pot flared at its side walls and offset at its bottom so as to reduce friction resulting fromfuel mass contact and also eliminatedanger of clogging the fuel mass forcing means.

Another object of the invention is to provide novel means for directing primary air into the combustion chamber within the fire pot through novel non-clogging openings in the bottom and side walls of said fire pot.

Another object of the invention is to provide novel means for providing secondary air above the fuel combustion zone in the fire pot.

Another object of the invention is to provide novel means for causing smoke and gases passing off above freshly fed green fuel located exclusively in the receiving end of the fire .pot to be directed toward the opposite end 'of the fire pot and over incandescent fuel in the combustion zone, thereb to be consumed over said combustion zone. Another object of the invention is to provid novel means for causing the primary and secondary air to be preheated before effective delivery thereof.

Another object of the invention is to provide a furnace of the character stated in which the fuel feeding means and the fuelmass forcing means comprise a common prime mover, a reciprocable pusher, a reciprocable feeder slide, a crank shaft driven by the prime mover, and connections between said pusher and slideand said crank shaft for reversely and positively reciprocating the pusher and slide.

Another object of the invention is to provide means of the nature statedlfor positively reciprocating the pusher andthe slide in which the driving'connections canbereadily adjuste'd'to vary the effective stroke movements of the slide.

Another object of theinvention is to provide means of the character stated for adjusting the effective stroke movements of the fuel feedingslide including devices for causing all variations in the'stroke of the slide to b'eieifected at the retraction end of the slide stroke, thereby to cause the slide always to be advanced .Tto a predetermined position regardless of stroke adjust; inent. r -31:

Another objectxof the invention is to provide a fire pot of the character stated including. an ash discharge door for yieldablyresisting discharge of ashes therethrough as a result of pressure. exerted onthe fuel mass by thefuel.

mass pusher, and means for varying the amount away andinsectionr 1 closely spaced yieldable fingers which will permit lump passage without free outpouring of finer fuelparticles.

Another object of the invention is to p ovide a devices for use in a furnace adapted for the burn-' in a fuel feeding means of the character stated a novel swingable fiap displaceable during each fuel charge feeding but which normally serves to protectfuel in the hopper from radiantheat' from the combustion chamber;

Another object of the invention is to't'itvie in a furnace of the characteristated a novel fuel mass pusher structure, novel means for preventing clogging of the pusher, and novel means for ing slide and the fuel mass advancing pusher in V predetermined positions, preferably but not necessarily with the slide retracted and the pusher in its advanced position. v v Another object of the invention is to provide in a furnace of the character stated a fanfor supplying air for the combustion of the fuel, and controlmeansfor causing the fan to oper-. ate continuously ,while the furnace operation is under the control of the fast timer equipment, and intermittently when the furnace operation is under control of the slow timer, that is to say when idling.

With the above and other objects in view which will more fully appear the nature of the invention will be more clearly understood by following the description, the appended claims, and the several views illustrated in the accompanying drawings.

In the drawings:

Figure 1 .is a central vertical longitudinal sec tional view of afurnace embodying the invention.

Figure 2 is a vertical cross section'ta-ken on the line 2-2 on Figural. r

Figure 3 is a vertical crosssection takenon the line 3--3 on Figure 1.

Figure 4 is a horizontal section taken on the line 4-4. on Figure 1.

Figure 5 is a right side elevationof the furnace.

Figure 6 is. .a fragmentary end elevation of the fire pot showing the mounting of the ash door actuated switches.

Figure :7 is a fragmentary. right side elevation of the parts shown in Figure 6.

Figure 8 is a fragmentary vertical crosssection showing a modified form of the arch providing a restricted passage for smoke andgases over the incandescent fire bed.

Figure 9 is a vertical cross section taken on the line 9-4 on Figure 8.

Figure 10 isa fragmentary enlarged detail horizontal section taken on the line] 11-10 on Figure 1 through the lower pivot mounting of the fuel feeding slide reciprocating lever.

Figure 11 is an enlarged front face view of one of the limit switches. v 1

Figure 12 is a right :end elevation of the limit switch shown in Figure 1l,J-parts being. broken Figure 13 is a rear elevation of the limit switch shown in Figure 11, an adjustment of the switch position being indicated in dotted lines.

Figure 14 is an enlarged side elevation showing the position switch mounting.

Figure 15 is a vertical cross section taken through the axis of the position switch actuatf a i Figure .16 is a diagrammatic view illustrating the electrical connections of the'var'ious control ing of other than anthracite coal, the ash discharge gate operated switches being omitted.

Figure 17 is a view similar to Figure 16 and illustrates the connection of the control devices in a furnace adapted for the burning of anthracite.

Figure '18 is a view similar to Figure 16 and ill'ustrates the electrical connections of the various control devices for use in a furnace in which th'e'as'h discharge gate operated switches are included. V

In the, example of embodiment of the invention herein disclosed, 5' designates the floor or bottom upon which rests an open base .framet. The framev is-closed at-the sides and rear :by a sheet met-alcasing structure 1, and its open front is closed by an ashremoval door "8. The casing 1 is, provided with a removable side panel 9 through which access ,may be had to the interior of the basestructure, and the mechanism therein.

A fire pot generally designated I0 is mounted inzspaced relationwithin the-base frame, said fire pot including, side walls H which are flared,

slightly in the forward direction and which depend from supporting flanges l2 resting upon the base frame 6. Thefire pot also includes a. fire bed supporting bottom generally designated I3 and e the staggered relation best illustrated in Figure 4,

and these cross .bars or .sections are formed. to provide an overhanging roof or hoodstructure I6 overlying each of the ports. It will be observed that the roofor hood structures are projected forwardly thereby to cause the ports to open upwardly and forwardly into the fire bed, or, in other words, in the direction in which the fuel mass is advanced over the supporting bottom IS in a manner later to be described. The particular construction and arrangement of the fire potcbottom cross bars provide other advantages. By proper regulation of. the size and locations of the openings or air ports IS in the bottom, it is possible to introduce the relative amount of air desired in each different part of the fire pot. Thus it is possible to either intensify or retard the combustion rate at will and in any certain part of the fire pot relative to someother part. This feature will be found very advantageous. The-hood structures It also tend to break up the fuelmass which passes over the fire pot bottom from the receiving end thereof to the ash discharging end thereof and to permit the easier passage of the air through the fuel mass.

It is also preferred that the fire pot bottom be inclined downwardly toward the ash discharging end thereof inthe manner illustrated in Fi ures l and 8 of the-drawings. Bythus inclining in the manner hereinbeforewstated, less resistance to movement of the fuel mass within the fire pot is offered and the effort necessary to be expen'dedby the motor which drives the pusher 24 is materially reduced. It is to be understood that the amount of thefiare of the side walls and the amount of the forward and downward inclination of the fire pot bottom may be varied according to-the nature of the particular installation and the type of fuel to be used. The use of an inclined bottom in the fire pot will be found very advantageous in installations where it is desirable at times to maintain a long but thin fuel bed. 1 a

It will be observed that the fire pot is longitudinally directed and preferably substantially u-shaped with the front end thereof through which ashes and clinkers are'adapted to be discharged sloped as at IT. The sloped, ash and clinker discharging end of the fire pot is equipped with a gravity closed ash discharging door I 8 which is hingedly supported at its upper end as at I-9. An adjustably mounted weight 2!] is carriedby the door l8 at its lower end, and by adjustment of this weight the resistance to opening of said door can be varied to suit the variations in operating conditions occasioned by the use of different forms of fuel, and different lengths of fire pot. It is also possible to vary the depth of the fire bed in the fire pot for a certain length by increasing or diminishing the resistance to opening of the ash discharging door, and by varying the downward slope of the bottom of the fire pot. It should be understood that for a certain downward slope the greater the resistance to opening of saiddoor, the greater will be the depth of the fire bed being advanced over the fire bed supporting bottom to be ultimately discharged in the form of ash and clinkers through the discharge door l8. However, the height of the fuel bed is never permitted to be greater than the height of the pusher plate 24.

Primary air for the combustion "of the fuel is delivered through the bottom ports l and it will also be observed by reference to Figures 1 and 2 of the drawings that the side walls ll of the fire pot also are provided with longitudinal, primary air admitting ports 2| which aredisposed just above the bottom l3. The side ports 2| are outwardly and upwardly inclined and have air scoop ledges 22 bordering their exteriors in position for guiding primary air thereinto. The

ledges 22 also are effective to prevent falling of bottom and sides to provide a tunnel 23, and in order to provide for the advancement of the fuel mass through the fire pot and the advancement of suitably timed fresh charges of fuel according to the present invention, a fuel mass pusher 24 is reciprocably mounted in this tunnel. See Figures 1 and 4. The pusher 25 comprises an upwardly and forwardly inclined pusher plate which terminates at its lower edge in a downwardly and forwardly inclined and sharpened step portion 25. The sharpened step preferably drags over the floor of the tunnel 23 during reciprocation of the pusher and is effectiv to dislodge any fuel tending to adhere to the tunnel fioor. At its upper extremity the pusher plate merges into a horizontally and rearwardly extended shelf portion 25 which effectively serves to support any fuel falling thereon during advancement of the-pusher plate and to prevent falling of fuelsbehind said plate. Being upwardlyand forwardly in clined, the pusherplate 24 serves to shape the fuel mass engaged thereby in the fire pot and tends also to keep the fire bed at a low level. Thus there is small possibility that the fire bed'will build up and tend to flow over onto the top 26 of the pusher plate during its forward movement.

It will be observed by reference to Figure lof the drawings that the floor 21 of the tunnel 23 which is engaged by ,the lower, step portion of thepusher plate, is disposed at a slightly higher level than the main fire bed supporting surface of the fire pot bottom I3. By thus offsetting the fire pot bottom it is more difficult to cause a' jamming-of the pusher 24 by the adherence of fuel to the fire bottom or by reason of the pres-,- ence of jammed clinkers in the bottom of the fire pot.

It will also be observed that the tunnel floor 21 is provided with a discharge opening 23 disposed just behind the limit of retraction of the cpusher plate 24, and this opening will serve to discharge any bits of fuel which might find their way past the pusher plate. It should also be observed that the rearmost primary air intake ports P5 are disposed well ahead of the most advanced position of the pusher plate 24 as illustrated in Figure 1, By reason of this arrangement of the parts the danger of sticking of fuel to the fire pot bottom just in advance of the pusher plate is reduced to a minimum and leakage of primary air and smoke rearwardly past the .pusher plate is effectively guarded against.

An upper cross wall 29 is provided at the rear of the fire pot and this cross wall preferably but not necessarily is disposed on an upward and forward inclination as indicated in Figure 1 and in position for lining up with the'pusher plate 24 when that plate is in its most advanced position as illustrated in said Figure l. The upper cross wall 29 serves to prevent coal from falling over the front face of the pusher plate 24 when it'is in its most advanced position, and this plate also serves to protect the fuel in the hopper from radiant heat from the fire bed. While it is preferred that the wall 29 be inclined in the manner stated, it is not necessary that this wall be so inclined.

The pusher is equipped with a plunger 30 which extends rearwardly from the center thereof and is slidable in a bearing 3| provided therefor and guiding same, and preferably supported'upon the tunnel floor 21. 3

The fire pot generally designated ll! opens upwardly'into a generally square body 32 which in this particular illustration is surrounded by a sheet metal casing 33 forming an air space 34 in which air is heated by contact with the heated walls of said head. Air thus heated in the space 3415 directed to rooms or other spaces tobe heated through a' duct or ducts 35 and may be returned through a duct or ducts 36 for reheating. It is to be understood that a separate circulating fan may be employed for forcing circulation of this air, but since the provision of these ducts and circulating fans of this nature are well known in the art, it is thought to be unnecessary to illustrate the fan in detail herein.

A flue 31 leads upwardly from the rear por-.

tion of the body 32, and a fire brick dome 38 is disposed across the rear portion of the head 32 between the fire pot and the flue in the manner best illustrated in Figure 1. The dome 38 extends "over slightly m'ore than the rear. half por l tionof the fire pot, and a transverse .flre brick wall or arch '39 depends from the-foremost edge of this dome and terminates just a few inches above thelfire pot so :as to provide a restricted passage or space 40 between the lower extremity of said arch and the fire bed. By reason of the. provision of the dome 38 and the arch 39 smoke :and

gases arising fromthose fresh fuel charges which are of'a volatile nature and deposited at the rear end :of the fire pot in-a manner later to be described curl upwardly and forwardly under the j dome .38 and are then forced downwardly into contact with the incandescent fuel bed while passing through the restricted passage 40 toward the flue 31. .SeeFigure 1. .In this manner the [gases and smoke are effectively heated so that the introduction of fresh oxygen in the form :of

secondary air willcomplete their combustion, and the improved furnace operates substantially in smokeless fashion.

An ash collecting pan 41 is supported on the fioor beneath the advance or discharge end of the firepot Ill and ashes, and perhaps some The pusher tunnel '23 is'in part defined by .a

7 top wall 42 which forms a slide support for a fuel c'linkers, accumulating in this pan can be convenien-tly'removed through the ash door 8.

feeder slide 43 which is horizontally reciprocable in-a feedway-44 provided in the manner best illustrated in Figures 1 and 3 of the drawings.

The feedway 44 is disposed beneath the delivery opening of a fuel hopper or magazine 45 having a downwardly and forwardly sloping rear bottom wall 46, downwardly and inwardlyslop'ing 1 side bottom walls 41., and a vertical front wall 48.

It will be obvious that so long as a supply of fuel remains in the hopper or magazine 45 the lower extremity of the hopper and the feedw ay in advance of the slide 43 will be filled with fuel, and a charge of this fuel will be delivered from the hopper at each forward movement of the slide 43.

Fuel is yieldably retained in the lower portion of nature of a transverse supporting bar 49 and preferably depending, closely spaced and fairly flexible spring steel fingers '51! which extend down into close proximity with the slideway bottom 42.

largest dimension of the largest lump of fuel 3 the hopper by a yieldable gate structure in the a 4 These fingers are considerably longer than the v likely to be fed into the fire pot so that the fingers will not be bent out abruptly and get per-'- manently set out of shape when the top of the supporting bar 49 is securely fastened to the main structure. Each time the fuel feeding slide 43 1 is advanced the fingers 50 yield to permit passage of a charge of fuel therethrough, and when the slide is retracted these fingers return to, or sub- Figure 1. By reason of the provision-of-this novel stantially to the vertical position illustratedln form of yieldable gate, coal .lumps can be forced through the gate and the individual fingers will large piece and at the same time to prevent outpouring of fine fuel particles'at each side ofrthe discharging lump. The yieldable gate 50 permits thexintended feeding of solid fuel charges without forcing the slide 43 to break up any lumps which might be present in the coal. In other words, the

1 closely spaced yieldable fingers 5.!) permit the pasmotorlcapable of crushing lumps, and italso yield in conformity with the shape of the extra assume makes it possible for foreign matter such as railroad spikes orrocks to be passeduthrough the furnace and discharged therefrom without trouble or damage. v

Just in front of the yieldable gate structure 49, 50 :there is provided-a solid flap 5] which is hingedly supported at its upper edge across the f-eedway. This flap also yields at advancement of the feed slide, 43 to permit passagethereu-nder of each charge of fuel, and uponretraction of the slide this flap returns to its normal position illustrated inFigure .1. Positioned in the manner illustrated, the flap 5| effectively serves to protect the gate 56 and the fuel inthe feedway 44 and "the hopper against direct contact of heat from the combustion chamber in the fire pot Ill. The fuel charges delivered by the intermittent advancement of the feed slide 43 always .are less in volume than the volume of the receiving space provided therefor by retraction of the pusher plate 24,. Each such charge is deposited by the forward movement :of the slide 43 and deposited generally speaking either in front of the retracted pusher face 24 or on top of the shelf portion .26 and in front of the downwardly inclined wall portion :52 and in such fashion that when the pusher 24 is completely retracted into the advance portion of the tunnel space 23, all of the fresh fuel charge will .be located in front of the pusher 24. Then as the pusher 24 advances this fresh fuel charge is forced forwardly by said pusher into the rear end of the fire pot and against the fuel mass therein in the manner illustrated in Figure 8 of the drawings. It will be noted that each fuel charge thus forced into the fire pot occupies a substantially verticallayer reaching down to the supporting surface of the The fuel feeding slide 43 includes a rearwardly and horizontally extended top wall 53, and the bottom edge thereof is equipped with a forwardly and downwardly sharpened step 54 similar in formation function with the step portion 25 of the pusher plate v24. The top wall :53 of the feeder slide 43 serves to support fuel in the hopper bottom during each forward projection of the slide 43 and by this means effectively prevents discharge of fuel behind the slide proper 43.

The fuel feeding slide 43 is equipped with a plunger 55 which extends rearwardly from the center thereof and is slidable in a bearing 56 provided therefor and is preferably supported upon the top wall 42 of the pusher tunnel.

Access to the fuel feedway 44 may be had through a suitable door 5'! in the casing structure and best illustrated in Figure 5 of the drawings.

It will be observed by reference to Figures .1 and 2 of the drawings that a primary air casing 58 is suspended beneath the fire pot I 8. This casing is formed to provide a horizontal duct 59 extending in spaced relation to the fire pot bottom 13 and beneath all of the air ports l5 therein, but it will be noted that this duct is closed across :itstop portion and does not deliver air directly into said P H BSL A fan 60 delivers air into the rear end portion of the duct 59, and this fan is driven by a separate motor Bl.

Side plates 62 extend upwardly from the lateral extremities of the duct 59 and in laterally spaced relation to the side Walls ll of the fire pot. Intermediate side plates 63 are disposed in spaced relation between the vside plates '62 and the adjacent fire pot'side walls II, and the duct 59 communicates upwardly into the space pro-v vided between the adjacent side'plates 62 and 63. It will be'observed by reference to Figure 2 of thedrawin'gs that the intermediateplates terminate at 64 well below thehorizontal support ing flanges l2 of the fire pot, and by reason of the particular relation of these side plates, .9, tor tuous passage 65 is provided through whichpri-i mary air, for introduction'into the bottom of the fire pot through the side ports 2| and the bottom portsl5 first passes upwardly "at each side from the bottom duct 59 between the spaced plates 62 and '63 at the-respective sides,*,and thence downwardly between the plates 63*and the respective side walls H of the fire pot." In passing downwardly the air is scoopedjinto' the side openings 2| by the deflectors 22, and the. air which passes these deflectors passes into the space 66 directly beneath the fire pot bottom l3 and thence upwardly'and forwardly through the ports l5. By directing the primary air in the particular manner stated, this air is preheated while passing in contact with the fire pot side walls I l, and this contactserves the double purpose of tending to cool said side walls;

A secondary air duct 61 leads from the main bottom duct 59 into the fire brick wall or arch 39 where it delivers into a manifold-68 provided in said arch; From the manifold,- the secondary air is delivered through a multipleiof individual ducts 69 through the bottom edge of the Wall or arch 39 and intothe'restricted s'pace'immediately beneath said arch. See Figures 1 and 2. It should perhaps be noted here 'that for anthracite firing,'no secondary air -is needed; This means of providing secondary air is' designed primarily for furnaces in which the burning of volatile bituminous coal is intended. The casing 33 is also provided with a side door "Ill through which access may be had into the interior of the dome structure above'the 'fire pot for fire inspection purposes, for the laying'of'a new fire, or for the replacing of the fire arch or cross wall 39. l

As an example of means for suitably reciprocating the pusher and the feed slide, there is illustrated a crank shaft H which is rotatable in bearings 12 provided therefor and supported on the floor 5. Rotation may be imparted to'the crank shaft H by a motor 13 and the speed of the motor is reducedthrough suitable reduction gearing generally designated "so that the crank shaft is rotated preferably at approximately one revolution every two minutes. It is found by' experience that'the slow rotation of the crank shaft with the consequent slow movement of the pusher 24 and the feed slide 43 provides bettenc'ombustion conditions invthe fire box. The crankshaft is provided with a relatively short crank 15 which 'is effective for driving the pusher 24, and with a longer crank l6 which is effective for driving the fuel feed'slide 43. The particular crank shaft speed referred to is'but an illustrative example effective to impart reciprocation to the pus'h'er and-the feedslide at'a maximum rate of thirty reciprocations perh'our, and is not to becons'true'd as a limitation upon the nature or scope of the invention.

,While crank shaft, lever and link connections are herein shown and described as the means for imparting positive reciprocation to the pusher 24 and the slide 43, it is to be understood that any other acceptable means can be employed for im-' parting the desired fuel feeding movements to these parts.

" The'pusher plunger 30 is slot and .pin connected, as at 11, with the upper end of a lever 18 which is fixedly pivoted at its lower end, as at 19, and is pivoted intermediate its ends, as at 80, with a thrust link 8! connected with the crank 15.

The feed slide plunger is slot and pin connected; as at 82, with the upper end of a lever 83 which hasa lost motion pivot connection at its lower end in a variable length slot 84 and is pivotally connected intermediate its ends, as at 85, with a thrust link 86 which is connected at its forward end with'the crank 16. The slot 84 is formed in a fixed support 84a and the length of the slot can be varied by adjustment of a screw 8412. It will be obvious that as the crank shaft H is rotatedthe pusher 24 and the fuel feeding slide 43 will be reversely reciprocated. In other words, each time the pusher plate 24 is advanced to its foremost position illustrated in Figure 1, the fuel feeding slide 43 will be retracted to its rearmost position illustrated in Figure 1, and vice versa. By reason of the provision of the pivotal connection at the lower end of the lever 83 in the lost motion slot 84, the forward stroke limit of the slide 43 will remain constant at the juncture of the horizontal wall portion 42 and the forwardly and downwardly inclined wall portion 52, while the retraction stroke limit of this slide may be varied by adjustment of the screw 84b, or; in other words, vby adjustment of the length of the slot. It will be understood that each time the link 86 is thrust rearwardly it will move the lower] endof the lever 83 along the slot 84 without imparting movement of retraction to the slide'43 until the pivot pin at the bottom of the lever 83 engages the variable end of the slot, namely, the screw 842), at which time the lost motion movement of'the lower end of the lever will be stopped and movement of the lever 83 will become efiective. to impart movement of retraction to the slide 43. It will be obvious that the shorter the length of the slot 84, the longer will be the length of the effective stroke imparted to the slide 43, and the longer the slot the greater will be the lost motion movement of the lower end of the lever 83 and the shorter the effective or fuel feeding stroke imparted to the slide 43.

By definitely fixing the forward limit of the slot '84, the forward stroke limit of the slide movement is fixed at thepoint hereinbefore described, and thus, regardless of the length of feed strokebeing impartedto the slide 43, the forward liimt ofthe slide movement is fixed at a point where it will surely remove all coal from the advanceportion of, the wall 42 and thereby overcome any tendency of coal lumps to hold the flap 5! open so that'such coal might become ignited by radiant heat from the fire pot and burn up into the hopper.

A timing switch'setting collar 81 is adjustably secured to the pusher plunger 30 in the manner best illustrated in Figuresll and 13 of the drawings. This collar has two actuator fingers 88 projecting in opposite directions laterally therefrom in position for actuating or settingthe two timing switches which form a part of the means 1 recesses 88 formed in the front Wall 92...

6 asses-1c for automatically controlling the furnace, it being understood that one of these switches 'servesto I provide for a predetermined definite number of fuel charge feedings and advancements in a given interval of time for maximum combustion operati'on of the furnace, and the'other-th'ereof serves toprovidefor a predetermined lesser definitenumber of fuel charge. feedings: and advanceswitchportion thereof, a detailed description of one of the units: will. suffice for bothv of them;

Each timer unit; comprises a bracket having a Base 9!, an upstanding front wall 92, and a parallel rear 'wall'93, andz is rigidly supported above the floor as at; 94. A cross shaft; 95 is rotatably mounted in; the bracket and is extended through the front. wall 921* and: provided. with a position adjusting" handle 86. The handle: car'- ries a spring pin 91 which may be engaged in one of a pluralityof selective position retaining Acasing 99 is secured upon.- andmovable with the shaft 95, and an'independent rotor we is rotatably mounted in and projects: rearwardly from the casing; ,The rotor I200 has; a crank arm 1M attached thereto, and this arm depends in position ,for being engaged and moved rearwardly by the respective one of'the actuator fingers 88 each time the pusher plunger 38 moved. rearwardly during a retraction of the pusher.

Each rearward movement of the arm it; serves to store energy in a spring, in which is mounted within the casing lie-and return move ment. of: the arm HM urged by the spring I02 controlled by an escapement mechanism H13 mounted within the casing. Thus; each rearward movement of. the arm WE occasioned by retraction of. the pusher plunger 3! is rapid, but return i or forward movemnt of the arm is very slow un- 55 and this; switch is: of the well known type in which the circuit controlling contacts are normally spaced apart or open. The switch con- 1 taots are caused to! engage: to completea circuit throughthe switch. only when'the switch plunger Hi5 is pushed inwardly. In order to accomplish this a disk Hi6 is secured torotate with the rotor 1 lot! and is provided atone point on its periphery with an. actuator hump or'cam portion Hil which is engageable with a roller H38 carried at. the

free end of a. y-ieldalaile. arm- Hlfl which overlies the plunger l5 and is secured to the.- switch as at lto.

After each crank arm Hit is moved rearward-1y His. After it. has returned a predetermined distance, determined by placement of. the shaft 95 and the switch Hi4 movable therewith, the hump 1 Ill: on. the disk. lfifi will engage the roller "18 and cause the armt09' to; forcethe plunger inwardly and close the control circuit through the switch m4. It'i's to be: understood, however. that the circuit closed throughthe-respectiue switch. [04

be. efieetive to initiate another cycle of move;- Lment of the crank shait It and thereby effect a designated EH dominate'the control of the furretraction and an advancement of the pusher 24 and an attendant advancement and retraction of the fuel feeding slide43 only when the positioning: switches are closed. These positioning switches will be described hereinafter and it is to be understood that they are: closed only when the: pusher isin its most'advanced position and the fuel feeding slide: in its fully retracted position.

While it is preferred that the pusher plate 2! always be stopped in its most advanced position, and the 'fuel feeding slide in its fully retracted positiomit is to be understood that the parts can be sotimed as to stop the pusher plate and the slide in any predetermined relati'om Should the parts be timed so that: the pusher plate 2 can: come to rest in a. retracted or' partially re traeted position, the feature of providing primary air intake ports F5 in the bottom of the fire pot and pusher tunnel only in advance of or forwardly' of the most.- advanced position of the pusher plate 2* effectively overcomes the possibility of any fresh coal which might. be disposed in front oi the retracted p'usher plate receiving enough oxygen to burn and fuse or stick to the tunnel floor and by this means jam or tend to jam the: next: forward movement of the pusher 7 plate Two additional or auxiliary control switches generally designated lfl are provided and each mounted for being automatically actuated by movement of the ash discharging door. One such switch; is mounted at each side of the ash discharging door as shown in Figures- 6' and'l.

These switches are so formed and connected in ciprocations of the pusher M and the fuel feeding slide 43: when a fresh fire is being built and before a fuel mass. has: been advanced over the fire pol; bottom and into contact'with the ash euscharglng' door, and also at times when; very rapid combustion provides an excess; of ash. and clinker formation which when discharged through the ash door provides a temporary void or a 'minimum'of. fuel mass congestion. resulting ill; a complete closure of the ash discharge door 1 The" particular switch structure illustrated hereim particularly in Figures '6 and 7' ofthe drawings, are of the same. type illustrated at HM in Figure 13 and includes a-casingl I 2 which attached, as at 3, to one of the side plates 62 and a contact making and breaking plunger m reciprocable. in and extended from: the casing." Each plunger is engageable by an actuator H5 fixed to the: ash door at the respective side so as; to be moved to its: circuit completing position each time the door moves about its pivotal mounting [9 to its: fully closed'position. It is to be understood that; whenever the ash discharge *door is in. the closed position ilhlstrated in. Fig?- 7 of the drawings, the. switches generally mace and cause the crank shait llto rotate: con- :tinuousim It will: be obvious that if rotation is imparted to this. crank shaft at the; rate of one revolution every two minutes, reciprocations will; be imparted; during an hour to the pusher 24 and the fuel feeding slide 4-3: under control domination oi the switch H11. Whenever the feeding, and advancement of iuel brings about a sumo-lent fuel mass congestion in the not [0,. the ash; discharge door |8 will be forced open an amount sufficient to cause the swit h Plungers H4; tobreak the dominant. control circuits through the switches III and re?- store the fast and'slow timer units to normal control of the furnace operation.

The position switch equipments will now be described. An actuator cam H6 is mounted upon the'crank shaft II, and this cam is provided with two diametrically oppositely disposed peripheral recesse ,III, each said recess being positioned in a distinctvertical plane traversing the axis of the crank shaft. The cam is adjustably secured upon the crank shaft by a set screw II 8. It is preferred that therecesses II I be so disposed as to assure stoppage of the pusher 24 and the fuel feeding slide 43 respectively in the fully advanced and fully retracted positions, but it is to be understood that by reasonpf the adjustable mounting of the cam, stoppage of the parts can be effected with the elements 24 and 43 in any predetermined positions.

A position switch II 9 is associated with the fast timer, and a position switch I is associated with the slow timer. Each of these switches is of the Well known, normally open or contact spaced type, the contacts being caused to engage only when the switch plunger I2I is forced inwardly. Each switch is equipped with an actuator roller I22 supported at the free end of a yieldable arm I23 overlying the respective plunger I2I and secured, as at I24, to the switch body. The rollers ride upon the peripheral surface of the cam H6 and are receivable in th recesses I I! previously referred to.

Circuits through the switches H9 and I20 are completed at all times except when the rollers drop into the recesses II! and thereby permit slide 43 is initiated it will be continued .by operation of the respective position switch until these elements have moved through a complete cycle and have been returned to the starting position, at which time the rollers I22 will drop into the recesses III and effect a breaking of the motor circuit;

In Figures 8 and 9 of the drawings, there is illustrated a modified form of the invention in which the dome I25 and thearch I26 are formed of metal. In this modified arrangement the arch I26 is equipped with a seat I2'I at its lower edge for removably receiving a fire brick arch I28. Like .the arch previously described, this arch I28 is closely spaced above the fire pot so as to provide a restricted space I29 for passage of gases and smoke close to the underlying incandescent fire bed. The arch I28 is provided with a transverse secondary air groove or channel I30 which is supplied with secondary air at one or both ends through an end duct or ducts I3I preferably provided with adjustable plate valve equipment I32.

In Figure 16 of the drawings the electrical control connections of the various control devices for use in a furnace adapted for the burning of solid fuel other than anthracite are shown. In this illustration the positive power line is indicated at I33and the negative line at..I34. The positive line is connected at I35 with the pusher and slide actuating motor I3, through the fast timer unit 89, and this line is connected, as at 7 I36, with saidmotor through the position switch I I9; 9 The negative line I34 is connected with the motor I3, as at I31, through the slowtimer unit 90, and this negative lin is likewise connected, as at I38, with said motor through the position switch I-20. The fan diagrammatically illustrated at 606I and which serves to supply the primary and secondary air is connected, as at I39, with the connections I31 and I38 leading to the motor", and this fan is also connected, as at I40, with the positive power line I33. A thermostat T is shown as connected as at I4I as a bypass around the slow timer 90.

Figure 1'7 is a view similar to Figure 16 but diagrammatically illustrates the control parts as connected for use in a furnace adapted for the burning of anthracite coal. In this illustration the thermostat may be of the form well known and including two simultaneously operable mercury switches diagrammatically illustrated at T and T This thermostat is connected, as at I42, as a by-pass around the slow timer 90, and an additional fan control timer I43 is connected as at I44, directly between the motor and fan assembly Ell -6| and the negative power line I34. In all other respects this control circuit is identical with the illustration in Figure 16 and is so designated. When anthracite coal is being burned in the furnace, it is desirable that the additional I fan control timer I43 be included so as to enable the motor and fan assembly 60-6I to operate for short periods while the furnace is idling and independently of the operation of the stoker motor I3.

If desired, the ash discharge gate operated switches generally designated I II may be omitted, and in such cases the electrical connections with the various control devices can be made as illustrated in Figures. 16 and 17. When the ash discharge door operated switches III are ineluded, they may be electrically connected in the control circuits in themanner illustrated in Figure 18. Figure 18 is a view similar to Figure 16 and like electrical connections therein are designated in like manner as indicated. In this figure, one of the ash discharge door operated switches I I I is shown as connected at I45 between the positive power line I33 and the stoker motor I3 so as'to dominate the position switch H9 and the fast timer unit 89, and the other of these switches III is similarly connected, as at I46, between the negative power line I34 and the stoker motor I3 so as to dominate the position switch I20 and the slow timer unit 90. With the switches III thus connected in the control circuit, it will be obvious that whenever the ash discharge door I8 is'closed the stoker motor I3, and also the fan and fan motor 60-6 I, will be caused to operate continuously independently of the timer units 89-90, the position switches II9I20, and also the thermostat T. In order to avoid operation of the stoker motor and the fan motor when the ash discharge door 'is closed andit is desired that the furnace should remain out of operation, ,a manually operable circuit breaking switch I4'I may be employed.

It will be apparent that th thermostat serves to effect a selection between the fast and slow fuel feed timing controls. When the thermostat is closed by a heat demand, the current reaches the stoker motor through the fast timing control equipment. The, slow timing. control equipment is notintended. to function .when the fast timing equipment isin control of the stoker motor operation. Therefore; as long'as the thermostat bypasses the current about the slowtiming control equipment fast timing control. equipment will remain complete control, assuming, of course, the. circuit through theash discharge door operated switches ill is broken. when such switches are inv use in the system, these switches being in dominant controlwhenever said door is closed. as hereinbef-ore: described The position. of thecontrolling thermostat is determined by the purpose for which the heating. unit is being used; If the unit: is being used for hot water heating, the thermostat will be locatedso as to cut in whenever the temperature in the hot water tank has fallen; below a predetermined point, and. to cut ofi when said temperature has risen above. a predetermined point Whenthe heating unit is beingemployed as a part of a hot water heating system a house or apartment, the thermostat would. be located centrallyin the house or apartment and would. function. in the same manner just above. described with the exception that the medium. controlling the function ofthethermostat would in this case be air instead of water as in the previously mentioned case, In other words, whenever the temperature in the house or apartment rose above the predetermined. point it would cutthefurnace off, and when itr fell below the predeterminedpointi-twould serve to out the furnace on. However, in. the hot air installation, the thermostat would indirectly control the furnace operation and would be supplemented by a thermostat installation. known as a bonnet control. The main thermostat. in the house or apartment would control the air circulating fan herei-nbefore referred to, which would act to raise or lower the bonnet temperaturein the furnace, and as the tion with a steam or hotv water system, the thermostatwould again operate directly on the stoker to keep the steamor hot water within the predeterminedtemperature limit. It will be apparent also thatwhen a steam system is employed, it may be found. desirable. to control it with pressure as the factor instead of temperature, in which case the system. would include a pressurestatinstead of a thermostat.

Inthe practical operation of the furnace, access may be had to the fire pot through the side door 10 and a fire may be laid thereinin the normal way by the common: expedient of laying paper and kindling upon the supporting bottom I3 and igniting the same, and thereafter supplying solid fuel so as to obtain asubstantial fire. After a substantial fire has been obtained, the mechanical control can be resorted to. By closing the manual switch I41, the ashv discharge door operated switches III will be. placed in control and will cause. the stoker motor 73 and the. fan-motor combination 60-6| to operate continuously until a sufficient amount of fuel has been fed into the fire pot, in successive stages, to engage. and force open the ash discharge. door [8,. at which time the circuit through the switche [ll will be broken and the normal timing controls will takeover the controlling function. Obviously, if there is no heat demand uponthe. thermostat. T at this time, the idling. or slow feed control equipments. will become. effective. Should the thermostat T be closed however, indicatinga demand for heat, the

fast timing equipment beselected to control the operation of the furnace and the fuelv feeding slide 43 and the. fuel bed advancingpusher-ZA' will be reciprocated the. predetermined number of times per hour controlled by this timing equipment until. th heat. demand is: satisfied, at. which time the thermostat. T will/open. and the slow timing equipment will be placed in control and it will function to supply just enough fuel to maintain the fire in an idling. condition. regardless ofthe length: of the period preceding the next heat-demand. r 7

Once. normal operation of the fire has been achieved, the fast and. slow timing. equipments alone normally function to control operation of the furnace, and it. has been found that approximately one-tenth of the. volume of the fuel fed is expelled from the ash discharge door when the fuel being used is. ordinary bitumious coal; This expelled volume is. pure ashes. Should a period of very'rapid combustion result inan abnormal burning of fuel and the formation of a clinker of considerable size, then, and then only, will the ash discharge door operated switches lll' function. As a. clinker thus,v formed falls from the ash discharge door, it creates a considerable void in the fire; pot and permits. the ash discharge door to close- The closing of this door closes the control circuits through the switches. I l I and causes them. to dominate the furnace control as in the continuously until the void is filled and a fuel bed congestion established sufiicient to force open the ash discharge door 13 and. break the circuit through the switches Ill, thereby to return the control of the furnace operation to thenormal'ly functioning fast and slow timer equipments;

Assuming that the thermostat T is closed, indicating a demand for heat, and thus selecting the fast timing equipment as the furnace stoking control, current will pass from the positive line I33 through the fast'timer unit 89 (when closed) to the motor 13 and. backthrough the thermostat T to the negative line I34, thus initiating an operation of the motor to brin about one complete cycle of operation or the fuel feeding slide 43 and the pusher 24", namely, a retraction. of the pusher accompanied by a fuel feeding advancement of the slide, and a retraction of the slide accompanied by an advancement of the pusher to its initial position. As the pusher plunger 30, moves rearwardly, the fingers 88 projecting laterally therefrom. will reset the. two timing switches, breaking the circuits therethrough and restoring energy in the springs I02 as hereinbefore described. Before the circuit, is thus broken through the timing switch 89., initiation of movement. of the crank shaft H will effect a. completion of the circuit through the position switch I19 so that the. circuit once completed will be maintained in the completed. state by the position switch until. the complete. reciprocation cycle is effected and the slide and pusher are returned. to their initial positions i1lustrated,inFigure I. It will be. noted that during the fast timer controlled operation of the furnace the circuit. through the motor and fan assembly 606[ is maintained. through the thermostat T so that the fan operates continuously so long as there is a heat demand.-

When the heat demand is satisfied, the circuit through the thermostat T is broken and the slow timing equipment is rendered eflective to control the operation of.the-furnace.- Aspreviously stated, this slow timing equipment func-,

stat T, and therefore the fan-will operate-imtermittently only, or, in other words, only when the stoker motor 13 is operating. In Figure-l? of the drawings; however; there is illustrated, a. modified control circuitin which isincluded an additional timer I43 which. may be employed" when anthracite coal is being burned. to cause the fan to operate at intervals during the idling operation of the furnace so that air will .be, supplied tothe combustion chamber at intervals independently of the motor.

By reason of the provision of the two fuel-feed rates anrd the twoair supply rates o ne for, maximum combustionand one for idling, it is possible to properly adjust the combustion rate for these two conditions and keep the fire pot in practically uniform condition with only fine ash beingdischarged through the ash discharge door It." With the equipment herein illustrated-arid described, it has been found possible to hold the fire indefinitely while idling ,andat the same time have the fire bed ready to gofull tilt ina few moments after the full air-supply and fast timing rates go into effect. I The improved furnace structure herein dis,- closed can be readily conditioned forthe use'of any of various types of fuel. This may be done by merely adjusting the ash discharge door weight 29 and/or by adjusting the feed rate'per hour of the new fuel'charges and/or by adjusting the air supply. The feed rate per hour is adjustable either by adjusting the stroke of the feed slide 43 in the manner hereinbefore described, or by the readily accessible and simple adjustment of the timing devices illustrated in; Figures 11 to 13 of the drawings whereby-the number of fuel feed strokes per hour is controlled. The same furnace can be usedforany size of bituminous or anthracite coal within its range, and can be adjusted quicklyfor low fusing point coal ash as well as high. 7 In the operation of the furnace, the rate of feed at high capacity, for mosteconomical operation, should never exceed the combustion capacity of the fire pot for the type of. fuel being.

used and for the depth of the fuel bed that is provided. Otherwise, there will be a discharge of unburned fuel into the ash pit. Furthermore, the conditions in the combustionchamber should remain pratically uniform so that.

the air supply can be scientifically adjusted to avoid loss of heating unused oxygen. Thirdly,

the intensity of the, air blast should not be such.

as to convert the ashes into clinkers. Fourthly.

to prevent all clinker formation'the fuel should not be converted into ash until.just before it is discharged from the combustion chamber. Inthe use of the improved stoking equipment here in disclosed, it is possible to obtain these advantages in the operation'of the furnace. There.

operation of the stoker can be obtained a condition of economical equilibrium between fuel supply and combustion rate, which is automatically maintained and which will provide a fire pot for a burning fuel that becomes ashes only when it has come close to the point of discharge at the end of theme pot. The simple adjustmentsand automatic operations already referred to accomplish these ends. j For any rate of feed which is less than the combustion capacity of the furnace, the fire pot will automatically condition itself to certain accumulation of ashes at the discharge end of the fire pot. To the extent that these ashes thus collect, there is a reduction in the combustion area on the fire pot bottom, and this reduction in the effective fire pot bottom or grate area causes automatically a similar reduction in the combustion. capacity of the fire pot which automatically equalizes the combustion rate with the rate of feed of fuel. An equilibrium will thus be attained regardless of the adjustment of the feed therein. Due to the attainment of this equilibrium, if the stoker is adjusted so that it is underfed or over-aired, the fire will not go out. There will always be a portion of the fire pot which is burning effectively. The only effect of'underfeeding will be that of cutting down the heat justment which gives the minimum amount of smokeless fashion.

undischarged ash at the end of the fire pot where the least amount of air is passing through the ashes and not doing its bit in consuming unburned fuel. the combustion chamber represents waste to the extent that it is not used in completing combustion of gases reachingi-this end of the com bustion chamber.

The particular arrangement of the dome '38 and: the arch 39, and the provision of therestricted passage 40' directly over the incandescent portion of the fire bed makes it possible to oper atethe herein disclosed furnace in approximately The successively supplied fresh charges of fuel fallinto the space provided by retraction of the pusher 24 at the rear end of the fire pot. These charges are relatively small and the volatiles and smoke which pass off therefrom move forwardly in their course toward the flue 31 and are caused to intimately contact with the incandescent fuel bed portion beneath the restricted outlet 40 so as to be consumed. The

incandescent portion of the fuel bed supplies the necessary heat, and the arch ports 69 the necessary oxygen to provide for the desired combustion of thesegases. v

It has been discovered that even without the use of the baffle wall 39 and without the use of a secondary air supply, bituminous high volatile coal burns with extremel little smoke due to the fact that the small quantity of volatile matter discharged from each of. the small supplies fed at a time will be consumed in the general combustion of the large combustion chamber before the next following fresh-fuel supply is fed. Surplus oxygen passing through the fuel bed, or ashes in the fire pot, aids in accomplishing this purpose.

I It will be apparent that the primary air introduced into the fire pot is preheated by. drawing the heat away from the side walls of the fire pot.-

Air passing through ashes into eluded, other than theelectric motors and motor gear r'eductions,"on account of the slowness of their movements, will operate in a substantially noiseless manner and present no lubrication prob- 1 lems. Very little power consumption is necessary, and the furnace can operate at a materially 1 reduced repair and power cost for a given output of heat.' A' motor of 1 of a horse-power will satisfactorily handle all operations except that of the fan for a furnace having a consumption capacity of 25 pounds of bituminous coal per hour. A positive feed cycle is provided. Set timings operate this feed cycle for both high capacity and for idling at an invariable rate for an approximately invariable amount of feed per hour. Therear'e, however, combined with the preliminary setting of the feed rates for high capacity and idling, the automatic features referred to which provide uniform conditions in the fire not at both extremes of the combustion rate. The con'diticnsinside the fire not will comets an equilibrium according to'the way the controls areset, and the setting of these controls thereafter automatically regulates the available amount of combustion in the fire pot and the nature of discharge from the discharge end of the fire pot according to the pleasure of the operator.

In our improvedfurnace, means is provided for effecting an automatic delivery of the ashes :through the'discharge end of the fire pot. In the operation of the furnace, there is no extensive accumulation of ashes except at the dischargeend of the'fire pot, and inthis way a practically uniform condition of the combustion zone is maintained at all times so that the air supply can be perfectly adjusted to the fuel supply and so that there will be noexcess of air provided. By checking the analysis of the stack gases it is possible to determine whether or not too large a quantity of air is being supplied for the amount of fuel being fed, et cetera. By reason of the provision of the equipment herein shown and described, a scientificadjustment can be effected which will be perfect as long as this adjustment is maintained and the same type of fuel is used, and when the type of fuel'is changed the necessary re-adjustment can be readily and easily. effected. The uniform fire pot conditions which are in equilibrium with the air supply pertain whether the stoker is running at full capacity or idling. There will. be no intermediate periods of conditions during which the high capacity of the combustion experiences any appreciable variations. t

The provision of the downwardly sloping bottom in the .fire pot renders possible the use of a relatively long fire pot and the provision of 'a large grate area fora certain width of fire pot without increasing the depth of the fire bed unduly. By controlling the downward slope of the bottom of the fire pot where the fire pot is relatively long, it is possible to yieldably close the discharge gate l8 and obtaineffective control by itsuse and atthe same time keep down the depth of'the fuel bed to a reasonable point.

It is of course to be understood thatthe details of structure and arrangement of parts may be variouslychanged and modified without departing from the spirit and scope 'of the invention as pointed out inthe appended claims. 4

We claim; y 1. In a furnace, a longitudinal fire pot having 10 a receiving end and an end portion over which ash'and clinker can be discharged and including a fuel mass supporting bottom and fuel mass retaining side walls, a pusher'reciprocably mount ed at the fresh fuel receiving end of the fire pot l5 remote from said discharge end for advancing freshfuel charges and fuel mass along the fire pot,'a fresh fuel hopper having a discharge throat disposed above and adjacent said receiving end, a fresh fuel charge pushing slide reciprocable at least part way across saidthroat for feeding successive charges of fuel into the space formed'by each retraction of the pusher, driving means for said pusher and slide, and control means for au-' tomatically controlling operation of said driving means responsive to heat demands and including devices for causing the pusher and slide always to stop in a predetermined position.

2. In a furnace, a longitudinal fire pothaving a receiving end and an end portion over which ash and clinker can bedi'scharged and including afuel mass supporting bottom and fuel mass retaining side walls, a pusherreciprocably mounted at the fresh fuel'receiving end of the fire pot remote from said discharge end foradvancing fresh fuel charges and fuel mass along the fire pot; a fresh fuel hopper having a discharge throat disposed above and adjacent said receiving end,

a fresh fuel charge pushing slide reciprocable at 7 least part way across said throat for feeding successive charges of fuel into the space formed by each retraction of the pusher, driving means for said pusher and silde. and selective control means responsive to heat demands for controlling operation of said driving means for feeding a predetermined definite number of fuel-charges into thefire pot in a given interval of time and in ad- Vance of the pusher to be pushed along the bottom thereby for maximum combustion operation of the furnace, or for similarly feeding a predetermined definite lesser number of fuel charges into the'fire pot in the same given interval of time for idling operation of the furnace.

3. In a furnace, a longitudinal fire pot having a receivin end and an end'portlon over which 55' ash and clinkercan be discharged and including a fuel mass supporting bottom and fuel mass retaining side walls, a pusher reciprocably mounted at the fresh fuel receiving end of the fire pot remote from said discharge end for advancing go fresh fuel charges and fuel mass along the fire pot, a fresh fuel hOliper having a discharge throat disposed aboveand adjacent said receiving end,

a' fresh fuel charge pushing slide reciprocable at least part way acrosssaid throat for feeding successive charges offuel into the space formed by each retraction of the pusher,'driving means for said pusher; and slide, selective control means responsive to heat demands for controlling operation of said driving means for feeding a predenjtermined definite number of fuel charges into the fire pot in a, given interval of time and in advanceof the pushe'rto be pushed along the bottom thereby for maximum combustion operation of the furnace, or for similarly feeding a predetermined definite lesser number of fuel charges into the fire pot in the same given interval of time for idling operation of the furnace, means for varying the amount of fuel comprising each fuel charge, a swingably mounted gate for yield ably resisting passage of ash and clinkers through the discharge end of the fire pot, and adjustable means for settingrup a variable resistance to opening of said gate. p

4. In a furnace, a longitudinal fire pot having a receiving end and an end portion over which ash and clinker can be discharged and including a fuel mass supporting bottom and fuel mass retaining side walls, a pusher reciprocably mounted at the fresh fuel receiving end of the fire pot remote from said discharge end for advancing fresh fuel charges and fuel mass along the fire pot, a fresh fuel hopper having a discharge throat disposed above and adjacent said receiving end, a fresh fuel charge pushing slide reciprocable at least part way across said throat for feeding successive charges of fuel into the space formed by each retraction of the pusher, driving means for said pusher and slide, selective control means responsive to heat demands for controlling operation of said driving means for feeding a predetermined definite number of fuel charges into the fire pot'in a given interval of time and in advance of the pusher to be pushed along the bottom thereby for maximum combustion operation of the furnace, or for similarly feeding a predetermined definite lesser number of fuel charges into the fire pot in the same given interval of time for idling operation of the furnace, a swingably mounted gate for yieldably resisting passage of ash and cli'nke'rs through the discharge end of the fire pot, and additional control means effectivewhenever said gate is fully closed to dominate the other controls and cause the drivin means to operate continuously to feed successive charges of fuel until the gate is opened a predetermined amount by ash or clinker accumulation discharge therethrough.

5. In a furnace, a longitudinal fire pot having a receiving end and an end portion over which ash and clinker can be discharged and including least part way across said throat for feeding successive charges of fuel into the space formed'by each retraction of the pusher, driving means for said pusher and slide, selective control means responsive to heat demands for controlling operation of said driving means for feeding a predetermined definite number of fuel charges into the firepot in a given interval of time and in advance of the pusher to be pushed along the bottom thereby for maximum combustion operation of the furnace, or for similarly feeding a predetermined definite lesser number of fuel charges into the fire pot in the same given interval of time for idling operation of the furnace, and means including a fan for supplying air for combustion to the fire pot continuously during maximum combustion operation of the furnace and intermittently during idling operation of the furnace.

7. In a furnace, the combination of a longitudinal fire pot having a receiving end and an end portion over which ash and clinker can be pushed and discharged and also having a fuel mass supporting bottom and fuel mass retaining side walls, a reservoir for solid fuel supported beyond said receiving end and having a discharge throat located higher than the normal level of burning fuel in the fire pot, a fuelmass pusher reciprocable in the direction of the length of the fire pot with its face serving at least in part as a rear closure for said pot and bearing constant upright a fuel mass supporting bottom and fuel mass re- 7 taining side walls, a pusher reciprocably mounted at the fresh fuel receiving end of the fire pot remote from said discharge end for advancin fresh fuel charges and fuel mass along the fire pot, a fresh fuel hopper having a discharge throat disposed above and adjacent said receiving end, a fresh fuel charge pushing slide reciprocable at least .part way across said throat for feeding successive charges of fuel into the space formed by each retraction of the pusher, and means for moving the pusher and slide in timed relation, said last named means including a rotary crank shaft and driving connections between the crank shaft and said pusher and slide and control devices for causing the crank shaft to turn in identical individual successive cycles thereby to always leave the pusher and slide in the same position following completion of each cycle.

6. In a furnace, a longitudinal fire pot having a receiving end and an end portion over which ash and clinker can be discharged and including a fuel mass supporting bottom and fuel mass retaining side walls, a pusher reciprocably mounted at the fresh fuel receiving end of the fire pot remote from said discharge end for advancing fresh fuel charges and fuel mass along the fire pot, a fresh fuel hopper having a discharge throat disposed above and adjacent said receiving end, a fresh fuel charge pushing slide r'eciprocable'at angular relation to said bottom and. effective when moved forwardly to push fuel mass before it over said bottom and when retracted to provide afresh fuel receiving pocket between said face and said fuel mass, a feed plunger reciprocable at least;part way across said throat in a path substantially paralleling the path of movement of the pusher and above said level of burning fuel for feeding fuel from said throat to fall, by gravity into said pocket, means operable during maximum heat demands forcontinuously reciprocating and timing said pusher and feed plunger so that the latter moves forwardly when the former is retracted, means for varying the stroke of the feed plunger to vary the amount of fuel forced to fall into said pocket on each forward movementthereof, baffie means disposed forwardly of the feed plunger and shielding fuel in the throat and reservoir from heat in'the pot,

and means for continuously and regulatably introducing air into the fire pot to support combustion therein.

8. A furnace structure as defined in claim 7 in which there is included a gate having fiexible fingers disposed across the reservoir throat to retain fuel therein when the feeder plunger is being retracted and through which fuel charges can be forced by the feed plunger to fall by gravity into the fire pot, and which can fiex to conform about fuel lumps and prevent sifting through of fine fuel from said throatat the sides of said lumps.

9. A furnace structure as defined in claim '7 in which the pusher and the feeder plunger are so constructed and cooperatively arranged that the pocket formed by retraction of said pusher always is larger than the volume of a fuel charge fed by forward movement of the feed plunger I so that successively fed charges of fresh fuel do comprises adjustable lost motion connections in the continuously Operating reciprocating and timing means. I r

11. A furnace structure as defined in claim 7 in Which'the fire pot bottom has apertures which are hooded in the direction toward the discharge end and throughwhich the combustion supporting air is directed, thereby to prevent free falling of ash through said apertures and causingsubstantially .all ashes or solid products of combusin which'the center of thefuel engaging pusher face of the pusher lies substantially in the same vertical longitudinal plane as the center of the fuel engaging face of the feed plunger. 7

A furnace structure as definedin claim 7 in'which the pusher and the feed plunger are reciprocated synchronously by a single source of mechanical power. r

16. A furnace structure as defined .in claim '7 in which there is provided a throat floor over which the feed plunger moves andin which the pusher has a generally horizontal top portion, said fioor being spaced above the pusher top portion by a member contacted by' air from outside the furnace thereby to retain a relatively cool condition of said member and insulate the fuel engaging face of the feed plunger from the heat of'the pusher.

17. A furnace structure as defined in claim '1 in which the pusher has a generally horizontal top portion, and in which the throat shielding bafile means includes an element portion reaching down approximately to the. level of said pusher top portion. 7 7 18. A furnace structure as defined in claim 7 in which there is provided a throat floor over which the feed plunger moves and in which the throat shielding baflle means includes a swingably mounted gate suspended over said floor with its lower free edge portion disposed adjacent said floor.

19. A furnace structure as defined in claim 7 in which there is included means for yieldably resisting ash discharge from the discharge end portion of the fire .pot bottom, and means for varying the amount of said resistance.

20. In a furnace, a longitudinal fire pot having a receiving end and an end portion over' which ash and clinker can be discharged and including a fuel mass supporting bottom and fuel mass retaining side walls, means for mov- 1 ing fresh fuel charges and fuel mass along said bottom toward said discharge end, said side walls having primary air openings therethrough and extending along the fire pot just above said bottom, said bottom having openings therethrough, 1 casing structure so constructed and arranged as to form a primary air delivery chamber disposed beneath the bottom for directing primary air upwardly therethrough and extending upwardly laterally of said side wall portions into position for communicating with said side wall openings to direct said air into the side wall openings.

21. In a furnace, a longitudinal fire pot having a receiving end and an end portion over which ash and clinker can be discharged andincluding a fuel mass supporting bottom and. fuel mass retaining side walls, means for moving fresh fuel charges and fuel mass along said bottom toward said discharge end, said side walls having primary air openings therethrough and extending along thefire pot just above said bottom, said bottom having openings therethrough, casing structure so constructed and arranged as to form a primary air-delivery chamber disposed beneath the bottom for directing primary air upwardly therethrough and extending upwardly laterally of said side wall portions and then downwardly parallel and against said side wall portions into position for communicating with said side wall openings to project a sheet of air in preheating contact with each said side wall portion prior to entry through the side wall openings into the fire bed on the fuel mass supporting bottom.

22. In a furnace, a longitudinal fire pot having a receiving end and an end .oVer which ash and clinker can be discharged nd including a fuel mass supporting bottom and fuel mass retaining side walls, a pusher reciprocably mounted atthe receiving end of the fire pot remote from said discharge end for feeding fuel mass along the fire pot, a fresh fuel hopper having a discharge throat, means supporting said hopper with its discharge throat disposed above and adjacent said receiving end, a fresh fuel charge pushing slide reciprocable at least partway across said throat for feeding successive charges of fuel from said throat to fall by gravity into the space formed by each retraction of the pusher, a yieldable gate, means for supporting said gate across said throat in position for being normally effective to hold fuel in the throat, said gate including a plurality'of depending closely related spring fingers yieldable to permit passage of fuel being pushed by said slide, and means for moving the pusher and the slide in timed relation.

2,3. Ina furnace, the combination defined in claim 22 in which is included a flap swingably mounted between the yieldable gate and the fire pot for shielding fuel in the hopper from radiant heat from the fire pot. I

24. .In a furnace, a longitudinal fire pot having a receiving end and an end overwhich ash and clinker can be discharged and includin a fuel mass supporting bottom and fuel mass re tainingside walls, a pusher reciprocably mounted at the receiving end of the fire pot remote from said discharge end for feeding fuel mass along the fire pot, a fresh fuel hopper having a discharge throat, means supporting said hopper with its discharge throat disposed above and adjacent said receiving end, a fresh fuel charge pushing slide reciprocable at least part way across said throat for feeding successive charges of fuel from said throat to fall by gravity into the space formed by each retraction of the pusher, a yieldable gate, means for supporting said gate across said throat in position for being normally effective to hold fuel in the throat, said gate includinga plurality of depending closely related spring fingers yieldable to permit passage of fuel being'push'ed by said slide, and means for moving the pusher and the slide in timed relation, said last namedmeans including a rotary crank shaft having two cranks thereon, a lever pivoted at one end and connected .at its other end with the slide, a lever pivoted at one end and connectedat its other end

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