US2574032A - Stoker control - Google Patents

Description

Nov. 6, 1951 W A, HARE STOKER CONTROL.

Filed April 29, 1949 @MI H@ l ATTORNEYS.

uw Y Q f@ Nwv alternating ,current,..is

rowerand ,oneliue, such ,as .tagline il l .directly to .the motora'. ,indicated s Patented Nov. 6, 195i 1 Teoma STOKER CONTROL Wilfred -uarewindsee arterie. garage nieuwe@ een, 2,9., weisen@ N0.- 20,466 main., 01- 2361451 Y a This invention has to do with a stoker control, and it is concerned particularly with the control of a stoker mechanism Yfor supplying solid fuel, such as coal, to a furnace for heating. a building such as-a residence. f y

The generalobject of the invention is .to provideva systemof control which may be placed under the combined controlling influence of .the temperatureinthe building and the temperature outside the building. The rarrangement is such that the user may, by selection, .place-.the .control-ling' factor subject-to the outside tempera-` ture into and out of'Y operation. A further .object isto -provide an'improved-arrangement for causing intermittent operation of the Stoker, inde- .1

pendently of the temperature icontrols, tothus maintain the re in the furnace. A further 0bi'ect is to provide a control system where controlling elements are .positively .driven as by means of a synchronous motor.

Fig. 1 shows a system `Withsorhe .parts diagrammatical-ly illustrated, and illustrating the .electrif cal Wiring of the system. y

Y Fig. l2 is -a detailed View .taken .substantially .on -line22 of Eig. llshowing brush and modulator structure.

`'The furnace is--generally illustrated at I .and the stoker is generallyV shown at 2, lthe .Stoker being arranged to .supply` fuel .and air .to ,the -furnace with the fuel, usually coal, ,passing through -a conduit 3. The stokerisldriven .by asuitable electric rnotor .4. Details of :the Lfurnace and the stoker need not be shownas .these-details aresub- -ject :to Wide variation. A wall of .a r.building ,s illustrated-iat Bland itwillbe understood that ,the .Stoker ,and vfurnace are .suitably ylocated inside themuilding theV wail-6 ,being an .outside Wall thereof.. v f y ,ferne main .electricpower line `for grigliate# motora, and which. ay elflmoltsof thc-...ugual ustreted fbylcondutolts l0 yand VIl .which leadirom a Sutehle,-.SQl1.r.9f may-.lead x1 ,the lice Whehthenl0, is a line switch l2 by means of .tireisystem .may befrlaefliutoand Olli -Of Qbefa- .ma Sample thermqfetar I s. Tni'sthemstats switch-may bemanpulateatemalse a-.eneegie appreciatedthat as. the Outside; tempeeilr@ .endialls that we fleidtiiljhe Pvlbiw.

with vcontact mor. contact 2li` as elected .by4 the, user andextending from' the Contact L9 is acopductor `22 which is connected to the driying niotor. 4. ,A conductor 2.3 extends fr Om .thenllat 20. to what may be termed a modulator andonductor 2.4,1whieh is connected to the. line ZZ, 21.1.5.9. extends/to .the modulator.

A line 2,5. connects Linto the` power line lUl advance of .the thermostat and it extends Yto a synchronous motor, 2l-.while another line 28;,c4on nects the synchronous motor with thepower line Il. Aline orconductorgextends ,to .a hold fire device, this une ze beingeonveniently.connected toline, in turn connected :to the pow?? line 1,9, vandla conductor 3.0 .extends ,from the hold fire dev-ice andl connects to ,the `line `22 leading tothe driving'motor.

`The synchronous motor .2? ,is aSSQciated a power transmitting .mechanism generally `illustrated at 3.3 .which is a.,rcduction gearing tor drivin-ga shait mounted in suitable bearings 35, andi the modulator and the hold fire Wdei/ice are mounted on the shaft 34. The arrangement, `preferably .andadvlantageousl Yismsuch Ythat the shaft' rotates veryslowly, .as forexampla ,two revolutionsy per hour. The, modulatoigis in .form ofa drumgenerallyjshown Vvat .4.9 andgithas thereon la yccu'i'tact or .conductor of tapered A,forni as shown at Ai, which constitutes p art Ao f the Asurface ofthe vdrurnwhile the .remainder of .the surface, as .shown at .4.2, .is of .nonconductor lrhaterial, suchas aplastic orhardrubber. [Ehe contact-! has a continuous ring like portion .4,8 at one end-.of the drum. .The modulator construction is somewhat .inthenature of a commutator.

lThe line k24 connects With vthe modulator vthrough the means of. a brush 43 which contacts .the continuous ring portion ,413, while the line /23 connects'withthe. modulator as by ,means of a brush 44. The brush 4 4 is adjustaloly.mou,lflliely for Ywhich ,purposejt may be ,sldably .mounted onza .supporting ...rod .like 3 element 135, and the .brushL'Jl is under control ofthe outside tempera- .ture As V.representativ.e ,ofY such a control, there a leveriib` .connectedto thebrush as byy .means fof Ya link.k 4 1. `,'Ihetemperature sensitive element outsidethe building is represented asintheform of afb'ulb. 591" mounted on the outside of thewall .and protected by a covering 5 I. This bulbrnaybe .of .the usualtype sealed with an expanspible fluid therein and atube 53 extends throughthe Wall ,6 andconnectstoan expandable and contractable chamber, such asa bellows 5 4. 1t will be 's lls the expandable chamber, expands and contracts thus rocking the lever 46 and shifting the brush 44 along the support 45. The bellows is connected to the lever 46 by a link or rod 55 and if desired, a spring 56 may be employed as an aid in shifting the lever 46 when the bellows con--V This selection may depend upon the type of coal used as well as other desires of the operator.

When the switch I8 is manipulated to contact at 26, then the system is under the dual control of inside temperature and outside temperature. If the thermostat switch I6 is closed thus calling for heat, the circuit extends through line 23 and to brush 44. The circuit cannot be completed, however, unless it is closed across the brushes 44 and 43. In cold weather the brush 44 may have a position well to the left of that shown and, indeed, the brush 44 may contact with the continuous ring part 48 ofV the contact member 4I.

contacts, the brush 64 being connected to the line 29. There is an adjustable brush 65 also for conpivoted at 66 and adjustable on its pivot as by means of an adjusting screw member 61 against which the brush may be held by a spring 10.

Now, it will be appreciated that vas the modulator rotates, an electrical connection is made across the brushes 43 and 44 from time to time as the brush 44 contacts the contact member 4I. The length of time that this electrical connection is established depends upon the position of the brush 44. In the drawing it is shown in a rather intermediate position. If the brush be shifted to the right, it comes into alignment with a relatively narrow part of the member 4l and, therefore, the contact is of relatively short duration. If it is shifted to the left. the contact is of relatively longer duration. Accordingly, if the outside temperature is relatively high, the iluid expands, the bellows expand and the brush 44 is shifted to the right while, if the outside temperature is relatively low, the fluid contracts and the brush 44 is shifted to the left. Thus the periodical electrical contact at the modulator is relatively short and relatively long with corresponding relatively high and relatively low outside temperatures.

The hold fire device is similar except it is manually adjustable. When the brush 65 contacts with the member 62 the electrical current is established across the brushes 64 and 65. It will be appreciated that with the hold re drum 60 rotating constantly as, kfor example, as two R. P. H. that about every half hour a contact will be made and the duration of this contact can be determined by the position of the brush 65.

The operation of the system is as `follows: When the line switch I2 is open, the entire system isinoperative. Upon the closing of the switch I2 the synchronous motor operates constantly thus rotating the modulator drum and the hold re drum. If the switch I6 be manipulated to make a contact at I9 then the sole control for the operation of the stoker, except for the hold re device is by 'the thermostat I5. When the temperature inside the building lowers and the thermostat calls for heat as by the means of closing the switch I6, the circuit is established through the thermostat through line 22 to the stoker motor 4 and back to line I I. The stoker will operate until the thermostat switch I6 is opened by the raising of the temperature inside the building. Periodically, however, the current is established through line 26, line 29, the hold re device, that is, across the brushes 64 and 65 and thence through lines 3D and 22 to the stoker motor so that the stoker is operated for the selected period of time every half hour. As explained above, this on period is selected by the adjustment of the brush 65.

Under this condition, the Stoker will operate and cease operation with the closing and opening of `the thermostat switch. If the temperature outside is not so cold, the circuit will not be completed until the contact member 4I is in position to engage the brush 44 and then the Stoker operates. However, the stoker will cease operating even though the thermostat switch I6 is closed Ywhen the contact member 4I moves out from under the brush 44. Y

Thus will be appreciated that in quite mild weather the system is not liable to overheat. For instance, in mild weather and when the thermostat switch I6 closes the stoker will not operate until the modulator closes the circuit and then it will operate for a period of time corresponding to the outside temperature. This period of operation may be very short and just enough to supply heat in the furnace to provide adequate heat within the building. However, there is usually a delay in the transmission of the heat `to the thermostat. If the stoker operated until the thermostat switch I6 opened, the residual heat in the coal fire causes an overheatingY within the building. y However, with the present invention, the furnace operates for only a short time in mild weather and then ceases operation but the rlre in the furnace continues burning and after the usual lag period or delay the heat is transmitted to the thermostat and it opens. In a similar manner overheatingV is prevented in medium weather whenv the brush 44 is in an intermediate position because the stoker can operate for only the period determined by the modulator.

While the details of the structure of the various parts may vary, it is preferred that a quick break in the electrical circuit be made at the modulator when the contacting member 4I moves out from under the brush 44. One structure for accomplishing this is illustrated in Fig. 2 where the contact member 4I has its outer surface on a greater radius than the surfaceV of the non-conductor 42. With the modulator rotating in the direction shown by the arrow, the trailing edge of the contactor 4I may be undercut as shown at 4Ia, so that when the brush 44 drops off the same, a quicknon-sparking disconfnection is made. The end of the brush may be angled or tapered also as shown at 44a. A similar arrangement may be used on the hold fire drum.

I claim:

A control system for a Stoker for supplying solid fuel Vto a furnace for heating a building wherein an electric motor drives the Stoker, comprising, conductors constituting an electrical circuit for the motor, a thermostat in the circuit adapted to be placed inside the building for closing and opening the circuit upon temperature fall andrise respectively, a drum having tapered contact members, a synchronous motor connected into the circuit for rotating the drum, a

the contact members on the drum, the element and drum being connected in the circuit in series with the thermostat, a temperature sensitive element for location outside the buiding, a closed fluid system connected to the sensitive element and including an expansible and contractable chamber inside the building, means connecting the said chamber to the shiftable element, for shifting the same in accordance with the outside temperature to thus variably control the length of the periods in which the circuit to the motor is maintained closed in accordance with the outside temperature, another drum with tapered contact members therein rotated by the synchronous motor, a shiftable contact arm for engaging the second drum, and said arm and drum being connected into the circuit in parallel with the thermostat, and manual means for adjusting th'e position of the shiftable arm to thereby vary the periodic closing of the circuit for the motor independently of the influence of the thermostat and temperature sensitive element.

WILFRED ALMON HARE.

REFERENCES CITED The following references arev of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,883,243 Bogle Oct. 18, 1932 2,055,641 Young Sept. 29, 1936 2,279,107 Cahn Apr. 7, 1942 15 2,301,708 Roessier Nov. 10, 1942 2,309,524 Miller Jan. 26, 1943 FOREIGN PATENTS Number Country Date 279,084 Germany Oct. 9, 1914 353,550 Great Britain July 30, 1931

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