US1669705A - Stoker-ram drive - Google Patents

Description

May 15, 192s.

D. F. GRAHAME 4 STOKER RAM DRIVE original Filed Jan. 28. 1922 5 sheets-sheet 1 Rw 1% ww y. i) WMWLF May 15, 192s.

l 1,669,705 D. F. GRAHAME STOKER RAM DRIVE original Filed Jan. 2s, 1922 5 Sheets-sheet 2 ,lime/dof? 1 aZZa 'raflam e,

- May I5, 1928.

D. F. c-sRAHAME sToKER RAM DRIVE Original Filed Jan. 28.. 1922 5 Sheets-Sheet 5 [Mae/@ff @callas Fratameg mwwmm MM@ May 15, 192s.

D. F. GRAHAME STOKER RAM DRIVE 5 Sheets-sheet 4 Original Filed Jan. 28, 1922 kama,

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D. F. GRAHAME sToKER RAMDRIVE original Filed Jan. 28, 1922, 5 sheets-Sheet 5 f @www ther objects will become apparent'from the Patented May 15, 1912s.

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DALLAS 11'. GRAHAME, or WE s'riiromv'ii` QUEBEC, CANADA, Assrcr`1voa4 To RILEY sroxnn CORPORATION, or WORCESTER, MASSACHUSETTS, kA CORPORATION or MASSACHU- SETTS.

s'roxan-RAM DRIVE.

originan apiiincauon mea January 2s, 1922, serial No. 532,429. ratent'no. 1,632,461', aat'e'drune 14, 19a?.

Dividedand this application filed .Tune 10, 1927. Serial No. 197,833.

In the installation of underfeed stokers in many plants, it is desirable (as pointed out in my (zo-pending` application, Serial No. 532,429, filed January 28, 1922, now

Patent 1,632,401, June 14, 1927 of which' this application is a division) ythat the ram or rams for feeding the coal shall be,l operated by vwhat is called a "mechanical drive, rather than by a steam-cylinder piston, and

the general purpose ofmy invention is to acted' on by steam generated from the ,boiler being served by the s'toker. In practically all installationsit is required that the periodicity of operationL of the ram, or of each ram individually,fbe manually settable. In either event the time taken by a cycle of operations of any ram'is variable. I regard it as very advantageous to secure rather rapid operation of the ram plunger on both its feed stroke and its return stroke, making the speed of ram travel uniform, regardless of variations in time consumed by"a 'cycle of ramoperations, and also advantageous to drive each ram individually from an electric motor that is associated with' that particular ram'by connections which ifiremechanically compact and simple and which permit overrunning of the electric motor and a substantially loadless pick up of the motor.y

Attainment of these and other desiderata by simple, rugged, eilicient structures and by advantageous correlationof the devices yemployed, are among the objects of my invention sought and attained, and other and furfollowingv description taken yin conjunction with the accompanying 'drawings and'setting forth one desirableembodiment of my invention for purposes of full disclosure although, as will become' apparent, many changes may be made in the embodiment of the invention without departure from the spirit of the inventionand within the scope of the appended claims.-`

In the drawings, Figure 1 is a schematic of Fig. 8.

elevation of van underfeed stoker drive for.

a `two-unit plant, installed in accordance "Fig 6 is an enlarged perspective viewy of one of the pawls of the nut shown in Fig. 4;' Fig. .7 1s a planl view of a-switch structure for controlling 'the operation'y of the electric.

motor, with parts ybroken away;

Fig. 8 is an end elevation thereof, with parts broken away; y

Fig. 9 ils a fragmentary detail lof parts of vsaid switch; and

. Fig.V 10 is a side elevation', with parts broken away, of the ratchet and pawl mecha-k msm of said switch, as'viewed on line 10-10 In the furnace to which fuel is supplied by an un- Vderfeed stokerinvolving one or more feedram structures having appropriate feedfhoppers. 'vTwo such Vfeed-structures are dia'-y grammatically indicated at 16..and 16', F ig.y

1, although any suitable number may be employed. As usual, the fuel yis to be burned under forced air-draft, supplied as by a fan 17, for the generation of steam in a suitable boiler, a fragment ofwhich' is indicated at 18.

In many commercial installations it is de drawings, 15 indicates generally a' sirable to make such provision that, as the steam-pressure drops, the supplies of fuel and of air to thestoker shall, automatically,

be augmented, and vice versa. The air-draft part of this regulating action may be effected in well-known fashion and I have diagrammatically illustrated well-known appliances for this purpose. Thus, in the specilic illustration. the boiler 18 has a steampipe conection 19 witha damperregulator 2O, the movable element of which has suit! able connection, typified bya cord 21, with a suitable draft-adjuster, typified by weighted damper 22 in the fan-belt. As the boiler-damper regulator l2O,as bydetachable links pressure drops the damper regulator pays out the cord 21 to permit the damper 22to movetoward open position; rise in boiler pressure resulting lin opposite operationV .of 'the damper.. Further, the fan 17 is indicated as driven from an electric fan motor 23, the speed of vwhich is variableand the fan-motorspecd controlled by a suitable rheostat 24 which, in turn, is worked in'response to steam pressure, supplied vthrough pipe 2,5 to a pressare-responsive rheostat actuator 25 of any suitable construction. Thus inV general, air supplied to the stolzer is preferably automatically variable harmoniously with steam-pressure changes.

, Each feed-ram structure, generally indicated at 16, vllfig. 2, involves a reciprocating plunger 26 working' in a hopper-equipped cylinder-structure'26a and each plunger is to bedriven byits individual electric motor 27 or 27', as diagrainmatically illustrated in Fig.` '1.f 'Each excursion of the ram-plunger, either on its feed stroke or its return stroke, involves starting and stopping 'its respective electric motor and periodicity of the motorstarting operation determines periodicity of operation of the associated ram. For controlling the periodicity of operationof each ram-actuating motor, I associate with each motor an individual timing-switch mechanism, 28 or 28jas specifically illustrated in Figs. 7 to `10, such mechanism including `an electric4 circuit-controlling switch in the power circuit of its respective motor and mey chanical switch-operatingdevices which are variably operatable to vary lthe intervals between switch-movement and thereby vary the periodicity of operation of the associated ram.

VWhere it is desired that periodicityof ram operation, and consequently the rate of fuel feeding, shall be varied in harmony with steam-pressure variation, Athis may be accomplished by connecting mechanical'parts of the timing switch structure`s28` and 28 to be variably worked from the saine pressureresponsive devices that control the `air-supply. 'As will more fully appear'from the specific description hereinafter, rate of rotation of the power-wheel v54` of each time switch mechanism partially controls the periodicity 0f ram-operation, and by driving these pulley wheels 54 by belting connections 29 from the shaft of the-stoker-fan 17, fuel feedingrate may be augmented harmonious-y ly lwith increase of air supply, and vice versa. `Likewise, (as will more fully appear) oscillation of a lever arm 30 of the time-switch mechanism 28 will vary the number yof'revolutions of the power-wheel 54 that will occur between successive operations of the motor-controlling switch, and by connecting all of these arms 30 of the respective timing-' switches 28 and 28 with 'the and .pulley power-connections 43.

`31 engaging a'pivoted lever 32 operatively attached to the cordV 21 of the damper Vregulator, fthe fuel-.feeding rate may bevaried harmoniously. with changes of pressure ,con-

ditions. s l

Referring to Figs. 2 to 6, the mechanical screw-drive of the ram-plunger 2,6,isso constructedjthat its driving.connection withits electric motor '27 l 'will be automatically broken at each end of the plunger-excursion,

leaving the electric motor free to continuein (idle rotation without injury to any of the parts. The rearend of the pluger 26 is hollow', for reception 4of the operating screw 38, and is'provided with a fixed reducing-collar 36 at its open, rear end for cooperation with the elongated traveling nut 37 which rides on and alongV the screw-shaft. The hollow plunger,'kept practically closedby I the collar and nut, may be grease-lilledand thefscrew Iis provided at it-s end with a grease-stirring plate B9 having a suitably angled end'39y. The collar`36 is loosely embraced, for some axial lost-motion, between two abutments on theelongated nut 37, these abutmentsbeing a ring 40 on the inner endV of the nut'and a head-structure tlnear theouter end of the nut. Consequently,v as the nut 37 travels` `along its screw-Shaft `88, in either direction,

it will carry with it theram-plunger 26 at first taking up the lost-motion that is inten-` tionally left "between Ythe collar 36 andthe that the screw-.shaft 38 shall be cause to rotate first in one direction and'then in the other, its driving electricmotor .27 is reversible, and such, motor may be'mounted directly on the frame workof the ram-and connected with the screw shaft by simple beltvv nut-carried, abutmentseO' and l1. In order ldlc Referring'tov Fig. 2, itV will be observed that when v the electricmotor is `energized to drive the ram plunger' on its feedl stroke, (i. e. leftwardly in the drawing), the motor will pickf up under minimum, almost-negligible load,

since the feednut will have to travel along the'feed screw`38 far enough to bring head .l1 into contact with collar 36 before'th'e motor-driven screw begins topropel the ram-plunger' 26 along thev feed-cylinder.' Such .pick upunder minimum load is very'y desirable, and'it will occur also on there-` llii are radially shiftab'le in notches or pockets formed in the head 41. Side-rings 46 fastened to the main portion of the nut head, keep the pawls laterally in position and also act as'stops for thelugs or feet 45 of the pawls to limit radially-outward displacementof the pawls. Any pawl may, when in bottom position as illustratedl in Figs. 2 and 4, engage in a slot- 48 which extends longitudinally along'the bottom of the cylinderstructure26, the side walls of the slot forming abruptl shoulders (except at the `slot ends) to prevent rotation of any pawl that engages therewith and so to hold 'thefeed nut against idle rotation. At each end of the rangelof travel of the feed nut 37, however, one wall only of the slot 48 is beveled, as respectively indicated at 49 and 49 Ato form pawl-escapeways, these two bevels being oppositely arranged as shown in Figs. 4 and 5 sothat when any active pawl 45 reaches either end of its range of excursion along the slot 48 it encounters a beveled escape surface across which the pawl may readily slip rotatively (incidentally being cammed back into its recess in the head 4l) thereby enabling the drive-'nut 37 to idle pending reversal of direction of movement of vthe screw-shaft 38. Since ther squared shoulder of the slot forms the side-wall portion opposite each such escapeway, it will be apparent that when the direction of rotation of -the screw-shaft is reversed, after f the idling operation of thev nut'above described,

I thevpawl 45 `first approaching the slot 48 will engage such squared ys'ide-wallof the slot 48 and thereuponL the nut will start on its return travel.' 1

`It will now be apparent that the screw drive construction 'above characterized is quite importantly related to the fact that the screw is driven by an electric motorand to the further fact that the periodicity of operation of said motor (and consequently of the screw 38) is adjustablyvariable. Not only does the electric motor pick up7 under minimum load, but the duration of its run in either direction-of rotation may be considerably longer than the brief time required for causing the ram-plunger to effect its powerful, quick excursion in either'direction, the excess duration of motor-operation merely resulting in the idle rotation of the nut in unison with the screw-shaft.y This characteristic is utilized inthe illustrated embodiment of my invention, where the time-switch mechanism next to be described occasionsyarying duration of motor operation, with a minimum durationl greater than the time required for the motor vto drive the nut 37 on a single or-. unf-directional excursion.

Referring toV Figs. reversing-switch arrangement for the motor 27, incorporated with the time switch mech- 7 to' 1o, uit eieetriai.

anism 28, may be of simple' construction; Two switches are provided, each having two blades connected for unison movement by a fiber block 55 surmounted by sloping wearplate 553. One pair of blades 56 and their stationary contacts 56 control one circuit for i the motor; the other contactors 57, 57 control the yreversingy circuit. Cams'5l and 52 angularly spaced upon a rotor v53 will operate the respective switches alternately and sequentially, holdingr each switch closed for a period longer than that required for driving the ram-plunger 26 on its feed stroke..

Thus, lduring each cycle or single rotation of rotor 53, motor 27-is run vin one direction, stopped, reversely run and stopped again.

The constantly driven power-wheel 54 for 'the time-switch mechanism runs looselyfupon the shaft 58 ofthe rotor 53, but to such shaft 58 a ratchet wheel l59 is securely fixed as by a key 59, and the loosely-running power-wheel 54 carries a pawl 60 which is gravity-urged towards saidfratchet wheel 59, as best shown in Fig. l0. The pawl 6() can engagethe ratchet 59 only `when the pawllifting pin 61, near the nose `of the pawl,

drops into a peripheral recess 62 of a shieldring 63 which is fastened by screws 64 to the fixed frame 65 ofthe switch mechanislm rlhe arc or circular vlength of the recessv 62 therefore determines the angular displacement that the pawl 60. canv give to the rachet-wheel 59 (and consequently the rotor 53) during a single rotation of the power- Vwheel 54", or otherwise stated, determines the ally movable through a suitable arc of vadjustment, thereby tov set the two vrecessed members 63iand '70 for a given effective length of the recess 62. The heretoforementioned lever 30, which is mounted to be rocked about the axis of the shaft 58 and is operatively `connected to the `damper regulator 20 so as to be moved in accordancewith changes in steampressure, is alsoconnectible with the adjustable shield-plate 70,' so

lou

that movement of said lever 30 may alter any .selected one of which may be engaged by a spring-latch 73 carried by the lower end yof the manual-adjustment arm 71. Therefore, with the automatically-movable lever standing in any given .position (say the -neutral position shown in Fig. 10) the manual adjusting arm 71 may be rocked with respect to it and engage with any one of the notches 72,' thereby f to` vary the e'llective length `of the shield-ring recess 62;` yet if the lever 30 be automatically moved to one side or the other oi' its stated initial position, the effective length of. such recess i cylinder 26a.

62 will be varied accordingly, since the yautomaticallybperated lever .30 willcarry the manual-adjustment lever 71 along with it. To enable this automatic adjustment to be dispensed ywith on occasion, lever-segment `3.0fis provided with a spring lock 7 4 which may be engaged in a recess of the switch raine. a y

In .brief rsume of speciiic operation, it will :be apparent (.seef Fig. 2) that when screw'38 is rotatedA in one direction by the reversible electric motor 27, the nut-struc ture 37 will `travel along the screw v'from thc' position shown in` Fig. 2 as'longas one ot the nut-carried pawls engages the squared edge .of the slot 48 in the .bottom of the rainpractically .no load, while the nut-structure 37 istaking up the lost motion to bring its l head 41 into engagement with collar 36 oi the ram-plunger. When the nut has carried the ranrplungerthrough its feeding stroke,

the f'theretoore-restained pawl 15 comes opposite Athe beveled surface 49 (Fig. 5) and the nut-structure 37 becomes free to rotate idly in unison with the screw 38, pending stoppage and 1 reversal of the motor 27. Motor stopping and starting, in alternately reversed directions, is effected -by the ree versing switch arranged in the motor circuit and forming partoi the automatic tim'- ing switch device. 28 shownin Fig. 7to 10.

.Eachfturn-over of the rotor 53 effects a. cycle ative connection between the motor and the ram-plunger 26. The periodicity of 0peration of the time switch mechanism is kvariable, being manuallysettable and also automatically .variable in accordance with variations in steam-pressure. The ratchet and pawlinechanisms 59 and 60 intervening between the power-driven pulley wheel 54 and the rotor 53 may be varied in operation by adjusting the pa,wl-controlling shield-plate 23 which drives said fan.

l clalm:

The motor will start .under f the. screw during with respect to `the relatively listed'shieldf ally made by shiftingthe hand lever 71- with respect to the notched sector E30/showin Fig. 10.A The latter sector, 30 Imay be,-

latched in fixed .position by latch 741er' it may be vconnected for automatic movement by the damper regulator 20 throughthe cord 21, the lever 32 vand .detachable link 31.- Also 'the rate of rotation of' the 4pulley Wheel 54 oi the switch mechanism may be changed in response tochanges ot stempressure condition, as by driving said wheel from the shaftoi the blast :tan 17,' the speed of operay tion whereof is in turn controlled by the pressure-responsive device 25 working the controlling rheostat 24 ofthe electric IIOr "1. In a screw-drive for an Vi171*iderllfd stolrer ram7 a plunger, a screw, means to rotate the vscrew in either direction, a nut ycoacting `with the screw and plunger .to

carry the plunger in either direction through a definite range of Vmovement'when restrained against idle rotationr y.with :the screw, and restraining meansy controlling said nut. i.' f

2.v In a screw-drive for an underfeed stoker ram, a plunger, its shell, a screw, means .to rotate y.the screw vin eitherdirection, and a nut` coacting with the screw, the shell andthe plunger to carry the plunger in either direction throughal definite range of motion and idly to turn with the screw during excessiverotation of the screw.

3. In a yscrew-drivev forv an .underfeed stokerram, the combination with a'plunger and Aa plunger-operating screw, .of aan electric motorto rotate thescrew, a nutzen the screw having lost-motion'connection with the` plunger, fand means to .cause said l nut to travel .along thescrew through a .detinite range of motion and'idly to turn with .excessive l rotation .of the. screw. i

4. In a .screw-drive for stolrerram, `the combination with a plunger and its shellv having an internal longitudinal shouldered guideway with. oppositely ex tending beveled escape-wayso'pening.to opposite ends of the guideway, fa 'feed-screw, means to rotate said screw'in either direction, and a nut upon the screw rotatable with .respect to .and .movable longitudinally with the plunger, said'nutvhaving a pawlto enf gage said guidewayand said pawl lbeing movable with respectto the nut to permit the nut to turn idly with the screw when said pawl encounters a beveled escape-way.

,5. Driving means forfan underfeedstoker y an underteecl u ram comprising, in combination, the ramplunger, a screw, a reversible electric-motor to operate the screw in either direction, automatically-operatable reversing-switch mechanism for running said motor in opposite directions, each normally for a longer period than is necessary to move thev plunger through a single excursion, and automatic means for breaking vthe driving connections between said ymotor and the ram-plunger to permit said motor to idle when said plunger reaches the end of its excursion,

6. Driving means for an underfeed stoker ram comprising, in combination, a ramplunger, -a reversibleelectric motor to operate said plunger in opposite directions, and power transmitting connections between said motor and said plunger having .automatic means for breaking said power connections and permitting said motor to run idly when said plunger reaches either ond of its reciprocation.

7. Driving means for au underfeed stoker ram comprising, in combination with a ramplunger and shell, a screw, a. reversible electric motor to operate the screw in either direction, automatically operatable reversing-switch means for running said motor in opposite directions, each normally for a greater period than is necessary to move the plunger through a full excursion, and a nut, coacting with the screw, the shell and the plunger to carry the plunger in either direction through a. definite range of motion y period than is necessary to move the plunger through a full excursion, and a nut coacting with the screw, the shell and the plun er to carry the plunger in either directlon through a deiinite range of motion and idly to turn with the screw during excessive rotation 'of said screw, said nut having lostmotion connection with the plunger to perlmit said motor to pick up before imposition of the plunger-load on the motor.

9. Driving means for an underfeed Stokerram comprising, in combination, a ramplunger, an electric motor, plunger-driving connections between said motor and said plunger', means for breaking said connections automatically when the plunger reaches either end of its stroke, a cyclically operatable switch in the motor circuit for starting and stopping said motor to control the frequency of reciprocation of'said plunger, power supply 'means for operating' said switch, and means for varying the periodicity of operation of said switch, to vary the feed-rate of the ram. v v

DALLAS F. GRAHAME.

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