USRE22898E - Stoker control - Google Patents

Description

E. K. SCOGGIN STOKER CONTROL July 15, 1947.

2 sheets-snee@ 1` Original Filed Feb. 24, 1936I Ihr/02122.07

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@WKN

July 15, 1947. E Kscogsm Re.22,s98

` STOKER CONTROL Original Filed Feb. 24, 1936 2 Sheets-Sheet 2 bmnfnseg ,in .59,72715-.z7fornyey V/fl/"Sf "l M -Reisss'ue'd July 15, 1947 STOKER CONTROL Elmer K. Scoggin, Golden Valley, Minn., assignor to Minneapolis Regulator Company, Minneapolis, Minn., a corporation of Delaware Original No. 2,234,383, dated March 11, 1941,

Serial No. 65,226, February 24, 1936. Application for reissue December 1, 1941, Serial No.

33 Claims. 1

This invention relates to controls, and more particularly to a type of control adapted to regulate feeding of fuel to a re under predetermined temperature conditions and/or at predetermined time intervals.

One object of this invention is the provision of an improved control system arranged to operate a mechanism, such as an automatic Stoker, upon a predetermined fall in temperature to control the said temperature in a space to be heated, or at predetermined time intervals in the absence of such a temperature drop, in order to maintain combustion of the fire at all times.

Another object is the provision of a system which will automatically preclude the operation of a stoker under the control of a timed mechansm during, and for an appreciable interval after, operation of the stoker by a temperature responsive mechanism, such as a conventional thermostat.

A further object is the provision of a system wherein continued operation of a stoker by temperature controlled means after energization by timed mechanism is precluded in the absence of a call for heat in the space to be heated.

Still another object is the provision of improved mechanism for controlling intermittent timed feeding of fuel to a source of combustion.

A further object is the provision of suitable mechanism to vary the duration of a period during which fuel is fed to a re under the control of timed mechanism.

A still further object is the provision of means to vary the interval between the timed operations of a timed fuel feeding controlmechanisrn.

A more specific object is the provision of improved mechanism to accomplish the above and other objects, which will be durable in construction and reliable in operation.

A further specific object is the provision in a system including a thermostat and a timer mech` anism, of an auxiliary temperature responsive circuit controlling mechanism in the thermostat circuit.

Other objects will in part be obvious and in part be pointed out hereinafter.

Accordingly, the invention consists in the arrangements of parts, combinations of elements and features of construction, as will be exemplified in the structure to be hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, wherein is shown one of the various possible embodiments of this invention:

Figure 1 is a schematic view showing certain parts of the structure of the instant invention and a diagrammatic representation of one form of control circuit;

Figure 2 is an enlarged sectional elevation taken substantially along line 2-2 of Figure 1;

Figures 3, 4 and 5 are detailed views of certain portions of the structure shown in Figure l, showing certain movable parts in dilferent positions;

Figure 6 is a detailed view showing another portion of the structure in a different position, and

Figure 'l is a sectional view taken along line 'I-T of Figure 6. y

Similar reference characters refer to similar parts throughout the several views of the drawings.

Referring now to the drawings and more particularly to Figure l: a suitable motor, generally indicated at II), which may serve to drive any suitable apparatus such, for example, as an automatic stoker (not shown), to feed fuel to a furnace, is controlled, in a manner to be hereinafter described, by the conjoint action of a suitable thermostat, schematically indicated at I I, and a timer mechanism, generally indicated at I2. Timer mechanism I2 is so constructed and arranged as to operate motor I0 for a predetermined period at suitable intervals, such as, illustratively, four minutes every half hour, such periods and intervals being subject to variation at the will of the operator. Provision is also made to render timer mechanism I2 ineffective when motor I0 is in operation under the control of thermostat Il during the normal operating period of timer mechanism I2 and for a suitable period subsequent to the cessation of such operation. One system and arrangement of parts adapted to accomplish the above and other results will now be described.

Timer mechanism I2 includes a suitable motor I3 which may be of the synchronous type, having a iield winding I4 to which current is supplied through lead wires I5 and I6 from suitable line wires Il and I8, which in turn lead to a suitable source of electrical energy (not shown). A pair of cams i9 and 20 are coaxially mounted, in a manner to be hereinafter described, on a sleeve 22 and rotated in a counter-clockwise direction as indicated by the arrow in Figure l, through suitable gearing and friction mechanism, also to be described hereinafter, by motor I3. Cam I9 is preferably constructed in such a manner as tovhave two oppositely disposed low surfaces I9a with intervening high surfaces |91). A suitable faces 25a of a peripheral extent slightly less than the peripheral extent of low surfaces I9a. Suitable indicia 2Ilb may be suitably affixed. toer imprinted on a portion of thesurface. of ,cam

29. A stud 2| having a threaded end isprovided,v

for engagement with a suitable aperture in cam 2U.

By reference to Figures l and 2 of the drawings,V it will be seen that when the parts. are irl/assembled relation stud 2| is passed through slot 19j and threadedly engaged with cam 20, and indicia 2919 is positioned below and adjacent aperture |911 in alignment with pointer |9e. By loosening stud 2| cam 2G, maybe rotated about sleeve 22 with respect tocam I9 and thecomposite high surface area of cams I9. andZIJ, which includes the total of the high surface areas |91) and 29a,1nay be varied. Indicia 29h will be correspondingly varied with respectto pointer I9e and accordingly may indifcate,.in theform of time indications, as will be explained hereinafter, thecombined low surface area of cams I9 and 2D.

Having particular reference to Figure 2, it will be seen that motor |3 has a drive shaft 23 to which is aixed a suitable pinion 24 which engages a reduction gear 25. Pinion 24 is driven through a suitable conventional reduction train (not shown). Gear 25 has an axle 26 journaled for. rotation in a sleeveZBa. secured toa mounting bracket 21. Mounting bracket 21 may be secured in any suitable manner, as by screws 28, vto an insulating panel.29 which may comprise a portion of a suitable casing (not shown).- Axle 26 carries atone end a second reduction .gear 3|) which engagesa driven gear3| which is mounted onsleeve 22. Gear. 3| may have a diameter substantially equaltothat of gear 25 in order that sleeve 22` and shaft .23`1nay be in substantial alignment. VA suitablefriction disc 32, which may be of any desired material but for which, in practice, cork has been found advantageous, is mounted onsleeve 22 adjacent gear 3l. Cams 20 and I9 vrespectively are then superimposed on disc 32. A stud vmember 33, suitably mounted in panel 29, passes through the interior of sleeve 22 and serves asV an axle for rotation .of sleeve 22 thereabout. Sleeve 22 has a flanged annulus 22a for abutment witharim 33a .of vstud 33... A housing 34 holds a spring 35; positioned about the exterior periphery offsleepve .22, in close juxtaposition with the exterior face of .cam I9. A washer 36 may be superimposed overtheyouter end of housing 34 and held in place by the coaction of a spring -collar 31 ,with a suitable groove 331) adjacent the outer end of axle 33-` It .will now beseen that rotation of shaft 23 is imparted to cams yI9 and 20 through sleeve 22. and the chain vo-f - reduction gears 24, 25, 30 and 3|.. In` practicefit has been found desirableto arrange.thegearing-ratio in such manner that cams I9 and 20 make one complete rotation every. hour.

It lwill further be seen that friction dise 32 providesr means whereby cams I9 and 20 may be rotated with respect to sleeve 22 .for any desired purposeJ vsuch as adjustment of the timer mechanism above described.

A cam` follower assembly, generally indicated aty gage a suitable threaded opening-in cam TIS to f 49, is pivotally mounted adjacent a portion of the exterior periphery of cams I9 and 20. Cam follower 49 is comprised of a block 43 of suitable insulating material on which are mounted by any suitable means,. such as screws 44,.a plurality, illustratively three, of spring contact arms 45, 46 and 41, the purpose of which will be described hereinafter.

It will now be seen that the cam assembly comprised-of cams I9 and 20 rotates adjacent cam follower. 4D and presents thereto at spaced intervals alowsurfacefla of cam I9. The area of surface |9a-is determined by the relative position of an adjacent highsurface 20a of cam 29. Variation of the l position'of high surface 20a with respect to' lowsurface I9a correspondingly varies the position of indicia 29hwith respect to pointer I9e. Since the cam assembly rotates once an hour each low surface Illa, except under circumstances to be hereinafter described, is juxtaposed to earn follower 4D fora period of minutes during each hour.` Indicia 201),v therefore, may be calibrated to designate minutes and the position of pointer I9@ with respect thereto accordingly indicates the number of minutes during each hour prise a mounting member 4|'to which block 43 may besecured by-any suitable means, such as screws 42. Mounting member 4| may be pivotally mounted on panel 29 through pivot 49y and secured, as by a spring collar 5B. A spring 5| se"- cured to an arm 4|a extending from mounting member 4|, and a nxed point on panel 29, such as screw 28, -(see-Figure-2), is so designed and positioned as normally to hold block 43 adjacent the peripheryof cams |9and 29. A downwardly depending lug48having a cam. surface 49a and a latching surface 48h, for a purpose to be hereinafter described, is also aflixed to mounting member 4I and may comprise an integral part thereof.

It will now be seen that the timed rotation of cams I9 andi!!! causescam follower 4|! to drop a distance equal to the difference between high surface |91) and-low surface I9a, due to the combined .forcev of gravity and spring 5I each time' a lowsurfacearea of the cam assembly rotates into engagement with block 43, and that cam follower 4D is held inra raised position for the period during .which the high surface `|9bof cam I9 is adjacent thereto. The fall of cam follower 49 to its low position causes the closure of -a circuit in a manner and for-a purpose tobe hereinafter described, while -a subsequent rise of cam follower 4(1.by ljuxtaposition to high surface |919 of cam I9 causes .the circuitto re-open.

While in the preceding vdiscussion cam'l9 has been pointed out as havingv a pair of oppositely .disposedlow surfaces in order to permit a drop a drop .may occur only once during every fulll rotation of cam I9. The mechanism for accomplishing.thiscomprises a segment 55, one sur# face 55a of which is comprised of an arc having a radiusof curvature-Y substantially equal to high surfaceV |913` yof caml I9,1and the'other surface 551)u of which. is comprised of an arc having a radius of curvature. equal'to-low surface ISaof cam I9. A projection 55o formed on surface 55h is substantially equal incontourand'dimensions to projection |9c on cam I9. `A securing screw 56 'passing` throughan aperturel in segment 55 may enhold segmentl 55 in related assembly with cam I9. Additional securing means t prevent rotation of segment 55 about screw 55 may be provided in the form of an aperture 55d in member 55 and a suitable projection |99 on the surface of cam I3 adapted to engage therewith (see Figure '7 From the above it will be seen that the portion of the peripheral configuration of the cam assembly adjacent segment 55 may be varied by a simple reversal of segment 55 to the position shown in Figure 6 by release of screw 56. It will also be seen that when segment 55 is in the position shown in Figures 1, 3, 4 and 5 of the drawings both low surfaces Isa of cam |3 will be juxtaposed to cam follower 40, but that when the position of segment 55 is reversed, as in Figure 6, that portion of the cam assembly adjacent segment 55 will present an unbroken high surface area. Accordingly, when segment 55 is in the position shown in Figures 1, 3, 4 and 5 of the drawings cam follower 40 will drop twice during each full, or illustratively, hourly, rotation of the cam assembly comprising cams I3 and 20 and segment 55, to close a circuit and actuate stoker motor |0, as will be hereinafter set forth. But when segment 55 is reversed in the position shown in Figure 6, such actuation will occur only once during each hour.

As shown in Figures 1, 3, 4 and 5, in dotted lines a lever 60 is pivotally mounted as by means of a pivot 6| on, and to the rear of, operating panel 23. A projection 63a extends forwardly from lever 60 through a suitable aperture 29a in panel 29 immediately adjacent lug 43, and a second projec tion 60h extends from lever 60 through an aperture 23h at a second point spaced from aperture 29a. Projections 60a and 60h are adapted to be moved in a manner and for a purpose set forth hereinafter, and apertures 23a and 29h serve not only to permit passage of projections 60a and 00h through panel 29, but also as stops to limit the movement thereof. A suitable extension, which comprises a weight 60o, extends beyond pivot point of lever 60' and serves normally to hold lever 60 at the extreme limit of pivotal rotation in a clockwise direction, such limit, as above stated, being defined by engagement of projection 29a and 23h with the right hand (as seen in the drawings) walls of their associated apertures 60a, and 6012 respectively. A pivoted spring arm 62 is mounted adjacent projection 60b and is adapted to be actuated in a manner to be hereinafter described toward and away from projection 60h.

The fall of insulating block 43 upon engagement with low surface ISa of the cam assembly, as above stated, closes a circuit in a manner hereinafter described, which serves to draw arm 62 to the left as viewed in the drawings. Likewise, the closing of a circuit by thermostat I in a manner to be described hereinafter also draws spring arm 62 to the left as shown in Figure 1.

Referring now particularly to Figure 3, insulating block 43 is shown in engagement with the low surface |0a of cam |9. The circuit is now closed by means of cam follower 40 and spring arm |52 is shown as bearing to the left against projection 60h of lever 60. The pressure of spring arm 62 overcomes the gravitational pull of weight 60o and causes projection 60a, to abut the inner surface of lug 48. Upon continued rotation of the cam assembly engagement of high surface |35 with insulating block 43 will cause cam follower 40 to rise and break the circuit, which will in turn release the pressure of arm 60 against projection 60h and permit the parts, with the exception of `a wire 99 leads to arm |03.

the continuously rotating cam assembly, to return to the position as shown in Figure 1.

Should spring arm 62, however, be actuated by thermostat while insulating block 43 is in engagemenl-l with a high surface portion |9b of cam |9, spring arm 52 will engage projection 60h and force projection 00a into engagement with cam surface 48a and therealong into engagement, with latching surface 48h. Upon release of the pressure of arm 62 the parts will remain in the position as indicated in Figure 4, with projection 60a engaging latching surface 48h even after low surface |9a has rotated to a position adjacent insulating block 43, until continued rotation brings the parts into the position shown in Figure 5, whereupon projection |30 raises insulating block 43 and hence cam follower 40 to a height sufficient to release projection 50a from engagement with latching surface 48h of lug 48. Thereupon weight 60e turns lever 60 about its pivot El until projection 60a again abuts the righthand wall of aperture 23a.

It is to be noted that projection is adjacent an end of low surface I3a in a direction counter to the direction of rotation of the cam assembly. Accordingly, it will be seen that if cam follower 43 and lug 48 are in such position as shown in Figure 4 as to necessitate release from engagement with projection 60a by action of projection |9c, it will be impossible to close the circuit associated with cam follower 40 for a definite period, subsequent to the release of projection 60a from engagement with latch member 48h, This period is of a duration sufficient to permit an entire high surface |9b to pass.,cam follower 40 before the presentation of a low surface |3a to permit cam follower 40 to drop.

It may here be pointed out that with the parts, including segment 55, in the position as shown in Figures 1, 3, 4 and 5 of the drawings, projection 55o serves the same purpose and acts in the same manner as projection |90.

Having particular reference to the wiring diagram shown in connection with Figure l, line wires I1 and I0 lead through the primary |00a of a suitable step-down transformer |00. A wire |0| leads from one side of the secondary |0017 of transformer |00 to a coil |02a of a relay, generally indicated at |02. Relay |02 includes contact arms |03, |04, |05 and is also operably associated with spring arm 62. In practical form spring arm 62 may comprise an extension of one of the arms |03, |04 or |05 of relay |02. A wire 91 leads from the side of relay coil |02a opposite wire |0| to a junction 38 from which A wire 96 leads from junction 98 to a junction |06 from which extends a wire |01 to a contact |08 which is adapted to engage opposite contact |08 carried by spring arm 41 of cam follower 40'. A second wire |09 also leads from junction |06 to a contact |I0 adapted to engage an associated contact ||0 carried by bimetallic thermostat A wire leads from terminal ||2 of thermostat to a contact ||3 which is adapted to engage an opposed contact ||3 carried by spring arm 45 of cam follower 40. The arm 46 of cam follower 40 bears a contact ||4 at an end thereof, adapted to engage a contact H4. A Wire ||5 leads from contact ||4 to a junction H6, from which a wire leads to transformer secondary |00b at the side opposite wire |0|. A second wire I8 leads from junction ||6 to a mercury switch ||3 associated with a thermostatic element |20 for a purpose to be more fully described hereinafter, and a second wire |2| leads from mercury switch IIS to a contact |22 positioned adjacent a corresponding rcontact |22' carried. vby a, VInovable arm of thermostat II.

Arm |03 of relay |02 is adapted under circumstances to be hereinafter described, to engage a contact |23. A wire'l24 leads from contact |23 to a terminal |25 carried by cam follower 40. Terminal |25 may, in practice, comprise one of holding screwsl 44, provided'electrical contact is established therethrough with arms 45, 40 and 41 and hence contacts' II3', II4 and |08. Arms |04 and I '0`5 are adapted to engage respectively contacts" |26 and |21which in turn are'connected with Wires |28 and I 29 respectively, leading from line wires I1 and I8. The opposite ends of arms |04 and |05 are connected through wires |30 and I'3l respectively to motor I0. Accordingly, it will be seen that energization of relay I 02 in a manner to `be` explained hereinafter, will cause arms I`4 and'l05 to engage contacts |26 and |21 respectivelyand operate motor I0 directly from line wires I1 and I8.

Assuming now that the parts are in the posi- ,tion shown in Figure l, it will be seen lthat no circuit Ais closed through relay coil |02a and in consequence arms |03, |04 and |05 are open andl spring arm I52 exerts no pressure on projection 50h.

Now, Yhaving particular reference to the circuit `controlled by timer mechanism I2, Vassume that the cam assembly comprised of cams I9 and 20 has rotated to the position shown in Figure 3. Insulating block 43 will drop, permitting contactsIIII and I08to engage respectivelycontacts |I4 and |00. An energizing circuit is'gnow established from transformer secondary ',I00b through `wire IDI, relay coil |02a, wire 91, junotion 98, wires 9E and |01, contacts IBB-|08', arms 41 and 45, contacts II4-II4, wire H5, junction IIB, and wire I I1 back to transformer secondary |001), which serves to energize relay |02. Arm |03 is now pulled inwardly to engage contact I 23, whereupon a holding circuit is established from transformer secondary |0012 through wire |0I, relay coil |02a, Wire,91, junction 93 as above described, and thence through wire 99, arm |03, contact |23, wire |24, terminal |25, arm 40, contact II4 to vcontact II4- II4,l wire II5, junction IIB and wire II1 to transformer secondary |001), wires 95 and |01 and contact |08, |08 being shunted out. Simultaneously, with the closing of arm |03, arms |04 andY |05 engage contacts |26 and |21 and stoker motor I0 is placed in operation. Likewise, simultaneously spring arm 6 2Ybears against projection 50h and forces projection 60a into engagement with the right-hand surface of lug 48, as shown in Figure 3. Upon `further rotation of the cam assembly a high surface I9b raises insulating block 43 and breaks, rrst, contacts |08-I08 and in a relatively short time thereafter contacts |I4-II4'. It will be'seen from the description of the ycircuit'abwe given that motor I0 continues to operate until contacts I4--||4' are broken and in the absence of any activity on the part of thermostat |I, still assuming it to be inthe open position shown in Figure l, the circuit through'relay coil I02a is broken to permit arms |03, |04 and |05 to move away from their respective contacts andjlik'ewise to permit spring arm 02 to'release Vits pressure on projection 60h. Inthe 'continued 'absence of activity o-n the part of thermostat |I 'this cycle will be continued at hourlyv orhalfhourly intervals, ,depending upon the position of segment55, and such actuation of motor I0 will be vfor a "period to be determined by the relationship of cams I9 and 20 with respect to each other.

Assume now, with reference to the circuit controlled by thermostat I I, the parts, including the timer mechanism I2, being in the position shown in Figure l, that there is a call for heat in `the space, the temperature of which is adapted to be controlled by thermostat |I. Contacts I22--I22 close and after an interval and upon a further drop in temperature contacts IIO-IIO close. The purpose of this plurality of contacts will be described hereinafter. A circuit is now established' through contact |22, wire I2I, mercury switch yI I9, assuming switch IIS is closed, which it willbe except under certain conditions to be hereinafter setforth, wire IIB, wire II1, transformer secondary |00b, wire IDI, relaycoil I02c, wires 91,796 and |09, contacts IIO-I I0', thermostat I I `and contact |22. This circuit serves also to energize relay coil I02a and close its associated contacts to establish a holding circuit from transformer v|00 through wire IDI, relay coil |02a, wire 91, junction 98, lwire S9, arm |03, contact |23, wire |24, terminal |25, arm 45, contacts ||3I I3', wire ||I, terminal IIZ, thermostat II, contacts I22-I22", wire I12I, mercury switch I I 0, wire IIS, junction II6, wire I|1 back to transformer secondary |005. Contacts I|0'-IIO and wires |09, |06 and 90 are shunted out. Spring army E2 is likewise actuated causing projection a to be pulled into latching engagement with latching surface 48h of lug 48. 'Simultaneously stoker'motor I0 is put in operation. It will now be seen that upon, continued rotation of cam I9 to the position as shown in Figure 4, wherein it presents a low surface I9a to cam follower 40, projection 60a serves to hold cam follower 40 through latching surface 48h in the same position as though it engaged a high surface, yand accordingly will not permit closing of the circuit through contacts I |4-| I4', and IUS-|09' as previously discussed.

If, however, during the time low surface area ISa is adjacent cam follower 40 and the requirement for heat in the space to be heated has been satisfied, relay |02 is deenergized andpressure on the spring arm -62 ycorrespondingly released, whereupon the engagement of projection ISC or projection 55C, as the case may be, with insulating block 43 will serve to lift lug 48 out of latching engagement with projection 60a and permit the'same to return to'the position shown in Figures'l and 5 under the impetus'of weight 00o. The system is now in condition for operation by the tmer'mechanism upon the next'presentation of a'low surface I 9a to cam 'follower 40.

If, however, during the period immediately followingrelease by one of the projections I9c or 55o, thermostat II again responds to a call for heat and closes the circuit through relay |02,

projection 60a will again engage latching member 48hy and the cycle will be repeated.

Accordingly, it will be seen that under such circumstances as abnormally cold weather when the room'thermostat makes frequent and/or prolonged calls'for heat, the'timer mechanism may rotate for an indefinite period without 'actuating the stoker, but that under other conditions, suchk as an unusually warm spell of weather, the timer mechanism will serve to maintain a fire in the' furnace even though no demand for heat whatsoever is made `bythermostat I I. It will further be seen that the timer mechanism is rendered incapable of operating the stoker during actuation by the thermostat II and for a period subsequent thereto. Such a period may vary from, at a minimum, approximately a half an hour, assuming that thermostat I| satisfies the call for heat in the space to be heated immediately prior to the passage of a projection |9c or 55e past cam follower 40, to a period of nearly two hours, assuming that cam segment 55 is in its reversed position as shown in .Figure 6 and that the thermostat satisfies the call for heat in the space to be heated immediately subsequent to the passage of projection |9c past cam follower 40.

Referring back to thermostat II, it has been found desirable to arrange the contacts IIO and |22' in such manner that they will engage their opposite contacts III) and |22 respectively at different temperatures, as for example, contact I22-I22 may make at 72 and contact IIIl-I I0' at 70. This temperature may of course be adjusted to the individual heating requirements of the space to be heated. Assume that the temperature falls below 70. Both contacts |0-I Hi and |22-I22 make to close the energizing circuit above described and energize relay |02. Upon such energization arm |03 will engage contact |23. The maintaining circuit above described is'now established and stoker motor I0 continues to operate. Now assume the temperature rises to 71. Contact II-Il is broken but stoker motor I continues to operate since relay ||i2 is closed through the maintaining circuit above described. Upon a temperature rise above 72, however, contactsv I22-I22' break, relay |02 is deenergized, and stoker motor I9 ceases to operate. Now assume that the temperature falls from 72 to 71. Contact |22-I 22 makes but stoker motor Il] is notstarted since no circuit is established. However, if the timer mechanism I2 at this point energizes relay |02 through the closing of contacts Ilfl-IIII and contacts Hi8-m8' and actuates the stoker motor ID for the predetermined period, it will be seen that contact II3|I3 is open and that at the end of the time period the circuit is broken by the opening of contacts ||4-I |4 and IOS-|98 prior to the making Contact II3-I I3.

The inclusion of contact I|3| I3 in the circuit thus serves to maintain the temperature of the space to be heated Within the normal range of thermostat |I since, in the absence of such circuit breaking means, and assuming contact |23 to be directly connected to wire III, if relay Y |02 and motor I0 wereenergized by timer mechanism I2 withthe room temperature at 71 and 'therefore with contacts IIO'-| I0 and I22I22 open and closed respectively, stoker motor I0 would continue to operate through a holding circuit comprising transformer secondary IDIIb, Wire IOI, relay coil |020., wires 91 and 99, arm ISS, Contact |23, wire II I, terminal ||2, thermo` stat II, contact I22-I22, wire |2I, switch IIS and Wires ||8 and II'I, after the termination of the timed period until the temperature reached 72 to break contact I22-I22.

The room temperature may, therefore, through the operation of contact |I3-II3 above described, be maintained constantly within the normal predetermined differential of the thermostat as, in the illustrative example above given, between 70" and 72.

It will now be seen that the provision of contact H13-H3 serves to preclude actuationv of stoker motor I0 .by thermostat II while timer mechanism I2 ris in control, and further that no circuit originally energized by timer mechanism I2 may be held through thermostat I I after the termination of a timed operating period in the absence of a call for heat serving to close both contacts IIO-IIII' and I22-|22.

In some instances, however, it may be desirable that the temperature be maintained constantly above the normal diiferential of thermostat II or above the making point of contacts lill-I I0', as in the illustration above, 72. In this case contact II3-||3 and its associated arm and Wiring may be omitted and wire III connected directly to contact |23. Then, in the event of a temperature fall to 71 and consequent making of contact I22-I22, contact II-IIIJ remaining open, if the stoker is started and relay i122 energized by the above described action of timer mechanism I2, upon the termination of the timed period of operation, stoker motor II) will continue in operation through a holding circuit comprising transformer IElIl, wire IDI, relay |62, wires 9"! and 99, arm |03, contact |23, wire III, terminal I|2, thermostat II, Wire I2I, mercury switch II9 and wires IIB and |I'I back to transformer |00, until the temperature reaches 72 and contact |22-|22 breaks. It will accordingly be seen that while contact IIS and its associated wiring forms a desirable adjunct to the system as a whole, it may be omitted if the operation above described is desired.

Referring now to thermostatic element |29 associated with mercury switch IIS, it lhas been found desirable in many instances to position a suitable high limit control adjacent, say, the water boiler of a heating system in order to preclude an unnecessary rise in the temperature of water during such a transition period as, for eX- ample, from a night temperature of approximately to a day temperature of approximately It has been found that during such transition period in the absence of such a control as indicated diagrammatically by thermo-responsive element |20 and mercury switch I|9, the temperature of the water in the boiler may rise to an unnecessarily high degree due to the prolonged action of the stoker in raising the temperature to normal day heat. Such a high limit control suitably interposed in the thermostat circuit serves to cut o the stoker for sufcient periods to permit cooling of the water to normal operating temperatures even though the position vof thermostat II still indicates a low temperature in the space to be heated. This high limit control serves, therefore, to retard continuous action of the stoker in such a manner as to prevent unnecessary overheating of the boiler.

The inclusion of the above described control is particularly advantageous in mild climates where the temperature increases veryrapidly with the y rise of vthe sun. During the night the tempera- `to furnish the requisite heat. yperature accordingly rises rapidly, whereas the ture may be relatively low and when thermostat first calls for heat in the morning a relatively long energization of the stoker motor is required The boiler temactual temperature requirement may be partially 'satisfied by the rise in outdoor temperature,

caused by the sun. In the absence of such a limit control as above described, the boiler temperature would rise due to the aforementioned demand for heat, to a point suiicient toV overheat therbuildingand, under normal circumstances, a

vconsiderable time vwould elapse before the temperature could cool to the desired level. The inclusion of the limit control therefore serves primarilyto preclude too rapid a rise in boiler temperature in order to compensate for a relatively rapid rise in outdoor temperature, and prevents overheating of the space to be heated due to the combined effects of the outdoor temperature and heating system.

A second h'igh limit control generally indicated at 132, which may comprise a suitable stack switch, diagrammaticallyindicated by mercury switch I 33l and thermos-tatie element I 34, isy interposed in the line circuit in order to provide an absolute cu-off should ther temperature in the stack of the furnace, or, in other words, the combustion temperature, reach a point of danger.

It may here be pointed out that in the preferred embodiment of the invention motor I3 is connected through wires I5 and I6 to line wires I'I and I8 between th'e high limit -control |32 and the source of power supply, in order that the timed rotation of the cam assembly may be unaffected by the opening of mercury switch |33.

From the foregoing it will be seen that there is herein provided a system and a specific structure which embody the features of this invention and achieve the objects thereof including advantages of great practical importance.

As many possible embodiments may be made of the above invention anad as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense. l

I claim as my invention:

1. In a control system,` in combination, a circuit, condition responsive means to open and close said circuit, additional means to open and close said circuit at predetermined time intervals, and a mechanical latch means movable by said condition responsive-means to latching position to maintain' saidl additional means in open position during the period when said condition responsivev means closes said circuit and for an appreciable period subsequent to the opening thereof by said condition responsive means.

2. A circuit controlling mechanism, comprising, in combination, a relay, temperature responsive` means to openand close a circuitl through said relay, time controlled means to open and close a circuit through said relay, and means to preclude closing of said time controlled circuit during the period when said circuit is closed by said temperature responsive means and immediately subsequent to reopening thereof, said last mentioned means comprising an arm associated with said relay and adapted upon closing of said relay to engage mechanically with said time controlled means. l

'3. A circuit controlling mechanism, comprising, in combination, a relay, temperature responsive means to close a circuit through said relay, time controlled means to close a circuit through said relay, aand means to preclude closing of said time controlled circuit whi-le said temperature controlled circuit is closed and for an appreciable period subsequent to opening thereof, said means comprising latch means associated with said relay and said time controlled means.

1. A lcircuit controlling mechanism, comprising, in combination, a relay,temperature responsive means to close acircuit through said relay, timecontrolled means to close a circuit through said relay, means to preclude closing of said time controlled circuit while said temperature controlled circuit is closed and-for an appreciable period subsequent to opening thereof, said means comprising, latch means associated with said relay and said time controlled means, and means on said ytime controlled means to release said latch means after the termination of said predeterminedY period.

-5. A control system for stokers, including a plurality of circuits, closure of either of said circuitsV adapted to operate'said Stoker, condition responsive means including a switch to close one of said circuits, time controlled means including a switch to close another of said circuits, means actuated by the closure of one of said switches to maintain another of said switches open during closure of and for a variable period subsequent to reopening of said one of said switches, said means comprising mechanical latch means actuated by the closure of one of said switches to engage the other of said switches to hold the same in open position, and means actuated by said time controlled means to disengage said latch means and said other switch.

6. A device of the character described, comprising, in combination, a, relay, means to energize said relay, additional means to energize said relay, said additional means including rotatable cam means having high and low surfaces and pivotally mounted cam follower means, the arrangement being such that engagement of said cam follower means with one of said surfaces upon rotation of said cam means energizes said relay, and vmeans actuated by said first mentioned means to preclude pivotal movement of said cam follower means.

7. A device of the character described, comprising, in combinatioma relay, means to energize said relay, additional means to energize said relay, said additional means including rotatable cam means having highl and low surfaces and pivotally mounted cam follower means, the arrangementl being such that engagement of said cam follower means with one of said surfaces upon rotation of said cam means energizes said relay, and means actuated -by said ilrst mentioned means to preclude pivotal movement of said-cam follower means, said means including a latch means associated with said cam follower means.

8. A device of the character described, comprising, in combination, a relay, means to energize said relay, additional means to energize said relay, said additional means including rotatable cam means having high and low surfaces and pivotally mounted rcam follower means, the arrangement being such that engagement of said cam follower means with one of said surfaces upon rotation of said cam means energizes said relay, means actuated by said first mentioned means to preclude pivotal movement of said cam follower means, said means including latch means .associated with said cam follower means and means on said cam means to release said latch means.

9.-A device of the character described, comprising, in combination, a relay, means to energize saidV relay, additional means to energize said relay, said additional means including rotatable cam means having khigh and lov.7 surfaces and pivotally mounted cam followed means, the arrangement being such that engagement of said cam follower means with one of said surfaces upon rotation of said cam means yeriergizes said relay, means actuated by said rst mentioned means to preclude pivotal movement of said cam follower means, said means including latch means associated with said cam follower means and means on said cam means to release said latch means, said last mentioned means including a projection extending a, substantial distance above said high surface.

10. A device of the character described, comprising, in combination, a relay, means to energize said relay, additional means to energize said relay, said additional means including rotatable cam means having high and low surfaces and pivotally mounted cam follower means, the arrangement being such that engagement of said cam follower means with one of said surfaces upon rotation of said cam means energizes said relay, means actuated by said first mentioned means to preclude pivotal movement of said cam follower means, said means including latch means associated with said cam follower means, means on said cam means to release said latch means and means to return said latch means to unlatching position upon release by said means on said cam means.

1l. In a control system in combination, a motor, condition responsive means to energize said motor through a circuit, time controlled means to energize said motor through anothel` circuit,

means to prevent continued energization of said motor through said rst mentioned circuit after energization by said second mentioned circuit when said first mentioned circuit is not closed through said condition responsive means, said means including a switch, and means associated with said time controlled means to open said switch prior to energization of said motor through said second mentioned circuit, and close said switch subsequent to deenergization of said motor therethrough.

12. A device of the character described, comprising in combination, motor actuating means, first means to energize said actuating means, second means to energize said actuating means, said second means including a revolvable cam having a high and e, low surface and a, pivoted cam follower adjacent thereto the arrangement being such that engagement of said cam follower with one of said surfaces energizes said actuating means, means to rotate said cam at a predetermined speed whereby said one of said surfaces engages said cam follower at predetermined intervals and means actuated by said first means to preclude energization of said actuating means by said additional means, said last mentioned means comprising a latch member movable by said first means into latching relation with said second means.

13. In la, stoker control system, in combination, condition responsive means to operate said stoker, time controlled means to operate said Stoker, said time controlled means including la rotatable cam and a, cam follower, said cam follower being movable into and out of stoker operating position according to the cam surface adjacent thereto, means to rotate continuously said cam at a, relatively constant speed whereby said cam follower operates said stoker at predetermined intervals and mechanical means controlled by said condition responsive means for affecting said cam follower to preclude operation of said stoker by said time controlled means during, and for an appreciable period subsequent to, operation of said stoker by said condition responsive means.

14. In a stoker control system, in combination,

14 condition responsive means to operate said stoker, time controlled means to operate said stoker said time controlled means including a rotatable cam and a cam follower, said cam follower being movable into and out of stoker operating position according to the cam surface adjacent thereto, means to rotate said cam at a relatively constant speed whereby said cam follower operates said stoker at predetermined intervals and mechanica1 means controlled by said condition responsive means to preclude operation of said stoker by said time controlled means during, and for an appreciable period subsequent to, operation of said stoker by said condition responsive means, said last mentioned means comprising a latch movable upon operation of said stoker by said condition responsive means to engage said time controlled means.

15. In a stoker control system, in combination, condition responsive means to operate said Stoker, time controlled means to operate said stoker, said time controlled means including a rotatable cam and a cam follower, said cam follower being movable into and out of stoker operating position according to the cam surface adjacent thereto, means to rotate said cam at a relatively constant speed whereby said cam follower operates said stoker at predetermined intervals, and mechanical means controlled by said condition responsive means to preclude operation of said stoker by said time controlled means during and for an appreciable period subsequent to operation of said stoker by said condition responsive means, said last mentioned means comprising a latch movable upon operation of said stoker by said condition responsive means to engage said time controlled means, and tripvmeans associated with said cam to release said latch means after a desired interval.

16. In a control system, a motor, a relay adapted to operate said motor, a thermostat adapted to energize said relay, time controlled mechanism also adapted to energize said relay, said mechanism comprising revolvable cam means, means to revolve said cam means at a relatively constant speed, cam follower means operated by said cam means and means operated by said cam follower means to Operate said relay upon operation of said cam follower means by said cam means, and means operated by said relay to prevent operation of said cam follower means to a relay energizing position by said cam means during energization of said relay by said thermostat.

17; In a stoker control system,'in combination, condition responsive means to operate said stoker, time controlled means to operate said stoker'said time controlled means including a rotatable cam and a cam follower, said cam follower being movable into and out of Stoker operating position according to the cam surface adjacent thereto, means to rotate said cam at a relatively constant speed whereby said cam follower operates said stoker at predetermined intervals and mechanical means controlled by said condition responsive'l means to preclude operation of saidl stoker by said time controlled means during, and for an appreciable period subsequent to, operation of said stoker by said condition responsive means, said last mentioned means comprising a latch movable upon operation of said Stoker by said condition responsive means to engage the cam follower of said time controlled means, said last mentioned means comprising an arm and a lever adjacent said cam means, the arrangement being such that `essere l15 said arm upon movement of said relay engages "`aid ylever and through said lever holdssaid cam f ollowermeans. l18A circuit controlling mechanism, comprising, in combination, a relay, a temperature re- 'sponsiv'e means to open and close a circuit through "said relay, time `controlled means to open and close a circuit through said relay, said time 'controlled'means comprising, in combination, cam means, cam follower means operated by said cam means, means to rotate continuously said "cam'means at a predetermined speed whereby 'said cam follower means'is operatedat predetermined time intervals and circuit controlling means operated by said cam follower means to close said iir'fciiity at predetermined time intervals, and means associated with said temperature responsive means to prevent operation of said cam follower means to a relay energizing position by said cam means when said circuit is closed'by said temperature responsive 'means and for an appreciable `Aperiodvafter opening of said circuit by said. tem- ''peiatu're responsive means.

19. In a control system, a motor, a relay adapted to'operate said motor, a. thermostat adapted to energize said relay, time controlled mechanism also adapted to energize said relay, said mecha- Arii'srn comprising revolvable cam means, means "to'revolve said cam`means at a relatively con- 'stant speed, cam follower means operated by said cam means and means operated by said cam follower means to operate said relay upon operation of said cam follower means by said cam means, and means operated by said relay to prevent oper- Yation to a relay energizing position of said cam follower means by said cam means during energizatio'n of saidI relay by said thermostat, and to vmaintain saidcam follower means inoperative for an appreciable period subsequent tof opening of said circuit by said temperature responsive means. 20. In a control system, the combination of, a motor,` means including a first circuit in control of said motor, control means for closing the rst circuit to cause operation o-f said motor, a second circuit in 'control of said motor, periodically operated contro-l means for periodically closing the Vsecond circuit to cause periodic operationof said motor including continuously operated cam means and means controlled'by the means including the first circuit and directly and positively operated upon every closure of the first circuit' to preclude closing of the second circuit for an'appreciable period subsequent to opening of said irst circuit.

21. In a control system, the combination of, a motor, means including a rst circuit in control of said motor, control means for closing the first circuit to cause operation of said motor, a second circuit in control of said motor, periodically operated control means for periodically closing the second circuit to cause periodic operation of said motor including continuously operated cam means, means for adjusting the cam means to v ary the duration of the period of operation of the motor, and means controlled by the means lincluding the rst circuit and positively operated upon every closure of the first circuit to preclude closing of the second circuit for an appreciable period subsequent to opening of the first circuit. 22. A stoker control system comprising, in combination, a plurality of circuits, condition `responsive means to operate said stoker through one of said circuits, time controlled means to operate said stoker through another of said circuits, and means to prevent continued operation of said stoker through said circuit of said condition responsive means after original energiza- 'tion of said stoker through said circuit of said time controlled means in the absence ofcondition change sufficient to cause energization of the stoker by said condition responsive means, s aid means including a make and break contact in the circuit controlled by said condition responsive means, the arrangement being such that said contact is opened by said time controlled means prior to closing of said time controlled circuit and reclosed by said time controlled means subsequent to reopening of said time controlled circuit.

23. In a heating system for a space having heating means for the space and a stoker for firing the heatingmeans, the combination of, a relay having a control winding, a maintaining switch and a load switch for the stoker, the maintaining switch and the load switch beingl closed when the control winding is energized, a space thermostat having a pair of switches that are sequentially closed upon a decrease in space temperature, means for completing a starting circuit through the control winding of the relay and the last to close switch ofthe thermostat to close ythe Amaintaining switch and the load switch for starting operation of the stoker, means for completing a maintaining circuit through the control winding of the relay, the rst to close switch of the thermostat and the maintaining switch to completing a circuit through the control winding of the relay and the periodically operated iirst switch to close periodically the maintaining switch and the load switch to operate vperiodically the stoker independently of the thermostat, said second timer operated switch being included in the maintaining circuit to prevent continued operation of the stoker following a timed operation when only the first to make switch of the thermostat is closed.

24. In apparatus of the character described, rin combination, switch means, timing means for normally periodically causing closing and opening operation of the switch means, additional means for causing closing and opening operation of the switch means at indeterminate times, and mechanism comprising latch means controlled by both the additional means and timing means whereby normally after a closing and opening operation of the switch means caused by the additional means the timing means is rendered temporarily ineffective to cause closing and opening operation of the switch means and is then rendered eiective again so that a longer than normal period elapses before another closing and opening operation of the switch means is caused by the timing means.

25. A device of the class described, comprising, in combination, a switch, means to open and close said switch and including cam means rotatable at a substantially constant speed and associated cam follower means to open and close said switch in accordance with a predetermined schedule, Ysaid means to open and close said switch also including an additional means for opening and closing said switch, and means associated with said cam means and said cam follower means and connected to said additional means lfor actuation 17 thereby each time said additional means actuates said switch to prevent operation of said switch by said cam means and cam follower means at one of its scheduled times upon operation of said switch by said additional means during a predetermined different portion of said schedule.

26. Ina timing mechanism of the class described, in combination, a device to be operated, timing means to move said device to a rst position and then back to its original position according to a predetermined schedule and including rotatable cam means and associated cam follower means, additional means by which said device may be moved to its first position and then back to its original position at times differing from said predetermined schedule, and means associated with said timing means and connected to said additional ymeans for direct actuation thereby by which operation of said device by said additional means during a predetermined part of said schedule when said device would not be operated by said timing means prevents operation of said device to said first position by said timing means at a different and later portion of said schedule.

27. In a timing mechanism of the class described, in combination, a device which it is desired to move from a first position to a second position and then back to its rst position, constantly rotatable cam means and associated cam follower means for moving said device to said second position, maintaining it therein for a predetermined time and then returning it to said first position upon constant rotation of said cam means, adjusting means associated with said cam means and cam follower means for varying the length of time said device will be maintained in its second position without affecting the periodicity at which said device will be moved to said second position during constant rotation of said cam means and for independently varying the number of times said device will be moved to its second position during a given period of time without aiecting the length of time said device will be maintained in said second position, additional means independent of said cam means by which said device can be moved to its second position while said cam means is being rotated, and means cooperating with said device normally to prevent its being moved to said second position by said cam means and cam follower means if said device has been moved to its second position and back to its first position at a predetermined time other than that caused by said cam means and cam follower means.

28. In a control system, the combination of, a motor, means including a first circuit in control of said motor, control means for closing the first circuit to cause operation of said motor, a second circuit in control of said motor, periodically operated control means including cam means moved at a constant speed for periodically closing the second circuit to cause a predetermined number of periodic operations of said motor upon a given movement of the cam means, means for adjusting the cam means to increase or decrease the number of periods of operation of the motor for a given movement of the cam means, a single means for adjusting the cam means to simultaneously vary the duration of all the periods of motor operation, and means controlled by the means including the first circuit and positively operated upon every closure of the iirst circuit to preclude closing of the second circuit for an appreciable period subsequent to opening of the first circuit.

29. In a control system, the combination of, a motor, means including a first circuit in control of said motor, control means for closing the lrst circuit to cause operation of said motor, a second circuit in control of said motor, periodically operated control means including cam means moved at a constant speed for periodically closing the second circuit to cause a predetermined number of periodic operations of said motor fora given movement of said cam means, means for adjusting said cam means to vary the number of periods of operation of said motor for a predetermined movement oisaid cam means while automatically maintaining the duration of all of said periods equal to each other, and means controlled by said means including the rst circuit and positively operated upon every closure of said first circuit to preclude closing of the second circuit for an appreciable period subsequent to open.. ing of said irst circuit by said rst mentioned control means.

30. A device of the character described, comprising, in combination, a circuit, means to close said circuit, additional means to close said circuit, said additional means includingrotatable cam means having active and inactive surfaces and cam follower means adjacent thereto, the arrangement being such that engagement of said cam follower with said active surfaces closes said circuit, means to rotate said cam at a predetermined speed whereby said active surfaces engage said cam follower means at predetermined intervals, and means positively and directly actuated by said iirst mentioned means upon every operation thereof normally to preclude the next subsequent closing of said circuit by said additional means.

31. In a control system in combination, a motor, condition responsive means to energize said motor through a circuit, a maintaining circuit for said motor controlled by said condition responsive means, time controlled means to energize said motor through another circuit, and means to prevent continued energization of said motor throughr said maintaining circuit after original energization through the other of said circuits in the absence of condition change sufficient to cause said condition responsive means to initially energize said motor.

32. In a control system in combination, a motor, condition responsive means to energize said motor through a circuit, a maintaining circuit for said motor controlled by said condition responsive means, time controlled means to energize said motor through another circuit and means to prevent continued energization of said motor through said maintaining circuit after original energization by said last-mentioned circuit in the absence of condition change suicient to cause said condition responsive means to assume motor energizing position.

33. A device of the character described, comprising in combination, motor actuating means, rst means to energize said actuating means, second means to energize said actuating means, said second means including a revolvable cam having a high and a low surface and a pivoted cam follower adjacent thereto the arrangement being such that engagement of said cam follower with one of said surfaces energizes said actuating means, means to rotate continuously said cam at a predetermined speed whereby said one of said surfaces engages said cam follower at predetermined intervals to energize said actuating means at predetermined intervals and means positively and directly actuated by said first; means upon Number every operation rthereof to preclude energization 2,107,472 of said actuating means by said second means 2,141,024 for an appreciable period subsequent to termi- 1,386,698

-nation of Venergization of said actuating means 5 Re. 19,164

by said first means. 2,055,641

ELMER K. SCOGGIN. Re. 21,350

REFERENCES CITED 1,960,718

The' following references are of record in the lo 111e of this at nt: 1

UNITED STATES PATENTS Re 20 240 Name Date Halvorson May 3, 1932 15 Number 20 Name Date Denison Feb. 8, 1938 Staley Dec. 20, 1938 Garrison Aug. 9, 1921 Teeple May 15, 1934 Young Sept. 29, 1936 Miller Feb. 13, 1940 Taylor Sept. 5, 1933 Standifer et a1 May 29, 1934 Bardes July 10, 1934 Teeple Sept. 11, 1934 McCabe Apr, 4, 1939 Owens Jan. 12, 1937

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