US2371020A - Burner control mechanism - Google Patents

Description

March 6,1945. Q EA 2,371,020

BURNER CONTROL MECHANI SM Filed July 1, 1942 I N V EN TOR. Vi'lsnn. O. Qamrg i Mil A.

A I former Patented Mar. 6, 1945 UNITED STATES P TENT eonnnnloonmonmonamsm Vil'ymr o. Bcam',Mi 1meapol*fs Minm, assigrroi'. a I Minnea mismone wen Regulator company,

Minneapolis; acorporaflon of llfelavcarc' Ap lication. July 1,. mat semi N 449.25 V

' 12' Claiinsa (o1.- rse-a ni-i .This invention is concerned with a burner con-- troll mechanism: and: more particularly with oneadaptedto be: employed: ina burner control. sys-- tem having provision for automatically igniting the: burner. V I

An object the present invention is to provide an improved; burner control system ot atype proe viding for a timeddelivery of fuel during. whichcombustion. must take place or the. system will-be shut down, i

An obiect of thepresent invention is to-provide' a" burner control: mechanism. employing. a device adapted to controi the operation of. a burner. with a first: motor for moving the device" to: an active position and a'second timing: motor for moving; the device away from this active: position with; meansresponsive to the establishment of. com bastion for-rendering the: second motor inoper ative in the event of the establishment of combustinn-.. l

A. further object of the inventiom is to provide a burner control mechanism such as set teethin: the preceding object in which the means for moving the burner control; device away from its active position. consists of an electrically heated thermal timer which. is dcenergicedupon the: es: tabliishment ofa burner flame. V r A still. further object of, the invention is to pro, vide an arrangementot the typemdiscussed itn the preceding objects in which the-energization ofthe second motor is initiated by movement at the first motor to a: position inawhich said con trol: device is in. its active:position A. still: fiurther' object of. the present invention! is to; provide such an: arrangement in which. the burner control deviceis a valve whose active posi tion is one in. which .fuel flow to: the burner is v permitted.

A still further object of the present inventionv is-to provide suclr an arrangement in which the valvecontrols the fiowof fuel to apilot bummer adapted to ignite a main burner. A. still further object oi the invention is to pro vid'e such a burner control device in which burner motor means is provided. for reducingthe; amount of fuel flow to an intermediate value,v this further i -motor means being placed into operation upon the first motor means moving its associated valve to-it's openposition;

" A further object of the present invention is the operation isinit'iated by a main controlling switch. 1 A still further efiiect' of the present invention is-to' provide an arrangement such 'asdiscussed in the last paragraph. in which. means responsive: tosther pressure ot the-dual being supplied to the human is ,operativelin the event of the-pressurefalling below a: predetermined value to interrupt,

5 the energicing. circuits. to l the variousv motor means}; I p Other objects oi the invention will be apparent fromka consideration of the. accompanying specification, claims! and drawing, of. which the single figure is a schematic representation. or my tin-- v proved burner mechanism embodiedin a burner cnntrol systemt r l v Referring. to the drawing, a main gas; burner isilndicated by the reterence numeral IL Ilhe burnen lfl issupplied withgas through apipe It which isconnected to vthe outlet side of a valve [12. The inlet-side of valve. I 2. is in tu-rnconnected to a pipe l3 whichis connected to a pressure responstva device M. The inlet side at the pressure responsive: device Ht is in turn connected to a u pipe t5:leadiingtoiany suitablesourceof gas (hot Disposed adiiacent thezmain burner I10 is a pilot burner Hi2. This pilo't burnenis supplied: withigas -by pipes Ill and t8, the latter oi which is con neoted. to pi-pe t3 on the inlet-side of valve IL Thus, the flow of. gas to pilot burner. I6 is ind'ependent 01% valve l 2.-'. A. valveto is: connected be tween pipes H: and |i8- to controt the now of gas tabinmer t6; Located in ignitingrelationto pilot is connected by a. pipe 23 tothe-outlet side: ot a valve 21 which in turnisconnected. through pip,-:

ing 22 to pipe H on'the outletsi'de' .of val ve 19".;

'Ilhus the flow of gas to burner 20 is controlled by; both va-Lves ia andlll. t v

The valve 1.12,, previously? referred. to, may be operated by an. electromagnetic actuator 01'; any conventional ty-pea- As shownin the drawing: the 40 actuator is a solenoid actuator. comprising a core 25 ansdaa winding 26.-. Upon. energization' of the windinglfi the oore 254s drawn upwardly to move the: valve llto open position; Associated with thevalive core. 25 is a switch blade 21. adapted tocooperate with aifixeds contact 38; When-the core 25 moves up to move the valve it to openposition, theswitch' blade. 21 is moved into engagemerit-with: contact 28L l Referring now: to valve l 9g thi's valve is adopted 5 to be: controlled by a patr ot thermali motored-l to provide such a system in which the various motorsare electrically operated motors and and 32 which together constitinrea motor-means for controllingthe: positiom 05 valve: lat motor. '31 is designed to cause op'ez'iin gr on valve 1:91 the motor 3 2 i designed to close it. motor-t l 'compn seca biiiietailichlemeflt I! which is secured flit-its left-hand endto a fixed support 34. Associated with the bimetallic element is an electrical heater 35. As indicated by the arrow disposed adjacent the right-hand end of bimetallic element 33, the element is adapted to warp upwardly upon being heated. The motor 32 comprises a bimetallic element 31 and a heater 38. The bimetallic element 31 is fixed at its left-hand end to a fixed supported 39. As indicated by the arrow adjacent the right-hand end of element 31, this element is adapted to warp;

downwardly upon being heated.

Projecting from the valve I9 is a valve stem 4| which is secured to the valve disk of thevalve.v

The valve disk of valve I9 is. biased to open position 50 that stem 4| tends to move upwardly; When in its cold condition, the bimetallic ele- Thus, when both bimetallic elements 33 and 31 are unheated, the bimetallic element 31 tends to assume an uppermost position such as to permit valve l9 to open but is prevented from 9.5- suming this position by the bimetallic element 33 acting through the spacing rod 42 between the two elements. Obviously, as soon as the heater 35 is energized, bimetallic element.33 warps upwardly so as-to permit valve l9 to move to open position. Whenever heater element 38 is energized, on the other hand, bimetallic element 31 no longer tends to assume its uppermost position but is slowly moved downwardly to the pos'ition shown in the drawing in whichposition the valve I9 is closed. Thus, the efiect of the motor 3|, upon being energized, is to cause opening of valve I9 while the effect of motor 32, upon being energized, is to cause closing of valve l9.

Bimetallic element 33 not only operates to controlthe position of valve l9 but it also operates a pair of contacts 44 and 45 adapted to engage with contacts 46 and 41', respectively. Upon heater 35 being energized to cause movement of bimetallic element 33 upwardly to cause opening of valve l9, thecontact 45 is movedinto engagement with contact 41. Upon further heating, further upward movement of bimetallic element 33 is resisted so that the element warps downwardly at its middle to move Contact out of engagement with contact 46. Thus, upon continued heating of bimetallic element 33, contact 45 is first engaged-with contact and then contact 44 is separated from contact 46.

Referring now to the valve 2|, a thermal mo tor 56 is provided for actuating this valve. This motor comprises a bimetallic element 5| secured at its left-hand end to a fixed s'upport 55 and an electrical heater 53 disposed in heating relation with the bimetallic element 5|. The bimetallic element 5| bears at its right-hand end against a valvestem 52 secured to the movable valve element of the valve 2|. The valve 2| is biased to open position and normally assumes this position when the bimetallic element 5| is unheated, this position being the one shown in the drawing. 'As indicated by the arrow adjacent the right-hand end of bimetallic element 5|, this element warps downwardly upon being heated. Thus upon heater 53 being energized so as to cause heating of bimetallic element 5|, the

right-hand end of bimetallic element 5| moves downwardly to cause closurev of valve 2|,

A hot wire igniter 54 is provided for igniting the gas-issuing from the flare burner 20., This heated to incandescence by the passage of ourrent therethrough.

A pilot burner combustion switch is generally indicated by the reference numeral 56. This switch comprises a bimetallic element 51 dis- .when the burner flame is extinguished so that the bimetallic element is unheated, switch blade 59 occupies the position shown in which it is in engagement with contact 68. When, on the other hand, the bimetallic element 51 is heated by reason of being exposed to a pilot burner flame, the switch blade 59 occupies a position'in which it is in engagement with contact 6|. Thus contact 66 may be referred toas the cold contact and contact 6| the hot contact.

A thermostat is illustratively shown as the main controlling switch. This thermostat is of conventional construction' and comprises a bimetallic element 66 to which are secured apair of contact blades 61 and 68. These contact blades are adapted to engage with fixed contacts 69 and 10, respectively. As indicated'tby the legends adjacent the thermostat, the bimetallic element-66 is so arranged that upon a temperature drop,- contact blades 61 and 68 are moved to the rightinto engagement with contacts 69-and '18. Switch blade 68 is more'widely spaced from contact 16' than is switch blade 61 from contact 69, so that upon such a temperature drop, contact blade 61 is first moved into engagement with contact 69 and thereafter upon a further dropintem perature, contact blade 68 is moved into engagement with contact 18.

The pressure responsive device l4 wasi briefly referred to before. f This comprises a housing 15 in which is located a diaphragm (not shown) exposed to the pressure within the fuel line. This diaphragm is in turn connected through a stem 16, to a switch blade 11 which, in turn, is adapted to engage a fixed contact 18. Under normal conditions, the diaphragm within housing 1.5 is con-' tinually exposed to gas pressure so that switch blade 11 is normally held in engagement with contact 18. Upon the gas pressure dropping below a predetermined value for which the regulator I4 is set, switch blade 11 is allowed to -move away from engagement with contact.18.

As will be pointed later,-the switch blade 11 and contact 18 control the energization of the entire system. V

A step-down transformer 19 is employed 'to supply power for the control system illustrated. This transformer comprises a line'voltage primary winding 30 and a low voltage secondary winding 8|. 5 The line voltage primary winding flfl'is connected to any suitable source'of power (not shown). r

, Operation- 3 I The various elements are shown in the position occupied when the temperature. to which thermostat 65 is subjected is at or abovethe desired value. Under these conditions, valves l2 and I9 are both closed and no gas is flowing to any'of the burners.

Let it now be assumed that the temperature igniter consists of a wire element adapted to be in the space in which thermostat 65 is-located i the left-hand end of secondary 8|, through con ductor 84, switch blade :11, contact 18, conduce tors 85 and 86, contact 69, contact blade 61,1.bi-

metallic element66, conductor H5, contact 28,

switch blade 21, conductor H6, winding 25, and

Iconductors H2,- Iil2, 9|, 92 and93 back to the other terminal of secondary 8i. circuit is independent of switch blade 68 and con- Since this new tactflll, momentary separation of this contact 1 blade from this contact does not cause deenergization of winding 26. In other words, as soon as winding 26 is once energized to open the valve l2;iits energization is assured until the temperacontact :blade 6'! from contact 69.

sult of a cumulative efiect and the fact that it is momentarily deenergized at any timev does not interfere with its operation. v

Under normalconditionsthe furnace will continue in operation until such time as'the temperature adjacent the thermostat has risen sufliciently to cause separation of contact blade 61 from contact 69. When this happens, the enere gizing circuit to the main valve operating winding-;26 is interrupted so as to cause closure of main valve I2. At the same time, the circuit to heating element 35 of motor M is deenergized so asv to cause valve 19 to be closedto cut ofi thej flow-of gas to the pilot burner. Theresultant extinguishment of the pilot burner causes cooling oil? of the bimetallic element so as to cause separation of switch blade 59 from;contact 6l and movement of the switch blade into engagement with contact 60.. The result of this is that it is no longer possible to energize the main valve and in order to start the system up, it isnecessary to go through the cycle traced above.

It is obvious that if at any time during the, 1 operation, the pilot burner I6 is extinguished, the

thermostatic element cools off to cause separationof. switch blade 59 from contact Bl .with

the result that the winding 26 is deene'rgized and the main burner valve [2 is closed .to interrupt operation of the main burner. This is desirable inasmuch as it is usually unsafe. to operate the main burner unless the pilot burner is also lighted. i

If at any time, there is a failure of gas pres v sure, or if the gas pressure drops below a predetermined safe value, the switch blade His sepa ous pilot valve motors are completely deenergized so that the elements assume the various positions shown in the drawing. In this Way, it is assured that the gas flow to the main burnerwillb'e in 'stantly stopped as soon as the gas pressure is inadequate to support proper combustion. Fur thermore, if the gas has not been turned on or ifgas pressure is too low, no attempt will be made to ignite the burner. r

ture has risen sufficiently to cause separation of Thus, any I tendencyof the valve to chatter due-to unstable engagement of the thermostat .contacts is entirely avoided. While such a holdingcircuit .was i 1 notestablished in connection with the various l other motors traced, these other motors were all heat motors so that a .momentary 'deenergiza- I tion thereof would not cause any harmful effects.

The-position assumed by a heat motor is the rej 7 Conclusion It will be seen that I have provided a new burner control system employing a new and novel burner control mechanism in which provision is made for providing the conditions necessary to the establishment of combustion for a timed period during which combustion must take place before the system will be placed in such condition to require manualinterve'ntion. This,v furthermore,is accomplished in an extremely simple manner with a minimum of parts.

' While'I have shown a specific embodiment of my invention, it is to be understood that this is only for purposes of illustration and that my in-' vention is to beli'mited solely by the scope of the appended claims.

I claim as my invention:

1. In combination, a device adapted to control the operation of a burner and movable toward and away from an active position permitting burner operation, a first motor associated with said device for causing movement of the same to said active position, a second timing motor for causing movement of said device away from said active position, means dependent upon the actuation' of said first motor for activating said second timing motor'toe'xert a 'forceurging said device toward inactive position, and means including a device responsive to the establishment of a burne er flame for rendering said second motor inoperativein the event of i the establishment of a burner flame.

2i Incombinatioma device adapted to control th operatio'n of a'burner and movable toward and away from ,anfactive positionpermitting burner operation, a first motor associated with said device for causing movement of thelsame to said active position, an electrically heated thermal timer for. causinglmovement of said device away from said active position, and means .includinga device responsive to the establishment of a burner flame for deenergizing said thermal timer in the event of the establishment of a burner ffiame. a

. 3. In combination, a device adapted to control the operation of a burner and movable toward and away from. an active position permitting burner operation, a first' motor, associated with said device for causing movement of the same to said active'fposition, a second timing motor for causing movement ofsaid deviceaway fromsaid active position,meansresponsive to movement of said first-motor to a position in which said device is in said active position to-initiate operationof said second motor, and means including a device responsive to the establishment ofa burner flame for rendering said second'motor inoperative in the-event of-the establishment of :a' burner flame.

4. In combination, a valve adapted to control v the flow of fluid fuelto a burner and movable toward and away from a fuel flow permitting position, a first motor associated'with said valve for causing-movement of the same towards said fuel flow permitting position, a second timing motor for causing movement of said valve away from. said. fuel :flowzpermitting position, means dependent upon the operationof said first motor for causing saidsecond motor to exert a force resisting-movement of saiddevice to flow permitting position, and means-including a device responsive to the establishment of a burner flame for rendering said second motor inoperative.

I 5. In combination; 'val've'means adapted to control the 1: flow a-of fuel-'to' burner means and movable between fiow preventing, minimum flow, intermediate flow, and full flow positions, means for moving said valve means to full flow position,

a first motor means for causing movement of said valve means to intermediate flow position, a second motor means for causing movement of said valve means to minimum fiow position, means operative upon said valve means being moved to I second motor means controlled by said first motor means and operative upon said first valve being opened to close said second valve, and means responsive to the establishment of combustion to terminate closing operation of said first motor means before said first valve is closed.

'7. In combination, a first burner, a second burner disposed in igniting relation thereto, an electrical igniter disposed in ignitin relation to said second burner but out of the path of the flame of said first burner, a first valve controlling the fiow of fuel to both of said burners, a second valve controlling the flow of fuel to said second burner, motor means for causing first opening of said first valve and then closing movement of it after a timed period, means for initiating operation of said first motor means to open said first valve, a second motor means controlled by said first motor means and operative upon said first valve being opened to close said second valve, means to cause energization of said igniter and means responsive to a combustion condition and operative in the event of the establishment of combustion to terminate closing operation of said first motor means before said first valve is closed.

8. In combination, a first burner, a second burner disposed in igniting relation thereto, an electrical igniter disposed in igniting relation to said second burner but out of the pathof the fiame of said first burner, a first valve controlling the fiow of fuel to both of said burners, a second mined position to initiate operation of said second motor means to opensaid second valve, and

means responsive to a combustion condition and operative in the event of the establishment of combustion to terminate closing operation of said second motor means and initiate operation of said first motor means to open said main valve.

10. In a fluid fuel burner control system, a main burner, a pilot burner, a main valve controlling the flow of fuel to the main burner, a second valve controlling the flow of fuel to the pilot burner, first electrically operated motor means for operating said main valve, second electrically operated motor means for operating said second valve first to cause said second valve to open and then to cause it to move toward closed position after valve controlling the flow of fuel to said second burner, motor means for causing first opening of said first valve and then closing movement of it after a timed period, means for initiating op eration of said first motor means to open said first valve, a second motor means for closing said second valve, means controlled by said first, motor means for initiating operation of said second motor means and for causing energization of said electrical igniter for a time period, and means responsive to a combustion condition and operative in the event of the establishment of combustion to terminate closing operation of said first motor means before said first valve is closed.

9. In a fluid fuel burner control system, a main burner, a pilot burner, a main valve controlling the flow of fuel to the main burner, a second valve controlling the flow of fuel to the pilot burner, first motor means for operating said main valve, second motor means for operating said second valve first to open said second valve and then moving it toward closed position after a timed period, a main controlling device, means operative upon said controlling device moving to a predetera timed period, a main controlling switch, means operative upon said switch being closed to establish an energizing circuit to said second motor means to cause said second valve to open, and switching means responsiveto a combustion condition and operative in the event of the establishment of combustion to cause energization of said first motor means and to effect the energization of said second motor means in such a manner as to cause the latter to maintain said second valve in open position instead of closing it.

11. In a fluid fuel burner control system, a main burner, a pilot burner, a main valve controlling the flow of fuel to the main burner, a second valve controlling the fiow of fuel to the pilot burner, first electrically operated motor means for operating said main valve, second electrically 0perated motor means for operating said second valve first to cause said second valve to open and then to cause it to close after a timed period means including a device responsive to a condition indicative of the need for burner operation and operative upon said'condition assuming a predetermined value to establish an energizing circuit to said second motor'means to cause said second valve to open, switching means responsive to a combustion condition and operative in the event of the establishment of combustion to cause energization of said first motor means and to effect the energization of said second motor means in such a manner as to cause the latter to'maintain said second valve in open position, and means responsive to the pressure of the fuel'beings'upplied to said burner and operative in the event of said pressure dropping below a predetermined value to cause deenergization of both said first and second motor means.

12. In a fluid fuel burner control system, amain burner, a pilot burner, a main valve controlling the flow of fuel to the main burner, a second valve controlling the flow of fuel to the pilot burner,

first electrically operated motor means for operating said main valve, second electrically operated motor means for opening said second valve,

a third electrically operated motor for closing said second valve, a main controlling'switch, means operative upon said switch being closed to establish an energizing circuit to said second motor means to open said second valve, means including a switch controlled by said second motor means for establishing an energizing circuit to said third motor, and switching means responsive to a combustion condition and operative in the event of the establishment of combustion to cause energization of said first motor means to open said main valve and to interrupt the energizing circuit to said third motor.

VILYNN O. BEAM.

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