US2372276A - Fluid fuel burner control apparatus - Google Patents

Description

Marh 27, 1945.

S. G. ISSERSTEDT FLUID FUEL BURNER CONTROL APPARATUS Filed March 26, 1945 attorney;

. timin meansioi' interposing 0mm VIII. BI. am

zsnare mum-m1. imam coN'raor. mans-ms Siegfried G. Isserstedt, Toronto, Ontario. Canada, ll lnor Gummy, Delaware tc Minneapolismoneyweil Regulator 7 Minneapolis,

Application March 26, 194:, Serb] s tsetse isolates.

The present invention is directed to automatic control apparatus for the burners of fluid fuel, and is more particularlyconoerned with apparatus for that type'of system which incorporates separate timing means for placing the system in operation, and for terminating operations! the ignition means in the case oLan intermittent 1g- 'nition system. l

where an intermittent ignition system is desired, to time the post ignition period followingthe es- 7 tablishment of combustion.

In systems where fluid rue is burned; and

' particularly where this fuel is oil, 1: is desirable to interpose a certain'predet'ermined minimum period of inaction between successive energizations or operations of the burner for the purpose of allowing the vapors of unburned fuel .to pass out of the combustion chamber and up the stack.

sponsive to the presence or the absence oi combustion within the combustion chamber. 7 Thus when operation of the burner is terminated the combustion responsive device will require a cer-' tain predetermined time to return to its cold.

position and the control system is'so arranged that the burner cannot be reenergized until such action has taken place.

tion however was designed to be used in'combination with a, combustion responsive device which is extremely sensitive and which passes from its ,hot to its cold position so rapidly that it cannot be used fortiming the del'aybetween successive burner energizations. When such a com .bustion responsive device is used it is necessary to provide some additional means for preventing the reenergization oi the burner until a certain predetermined minimum oi. time has elapsed.

In the case of intermittent ignition systems it has been the practice in many prior art control 4 systems to time the post ignition period by means of the combustion responsive device. Thus upon the establishment of combustion the combustion responsive device starts to heat and after a certain length ct time will deenergize' the ignition.

Where an extremely sensitive combustion respon- 'sive device is. used however, some] additional means-must beprovided for timing the post'ignit'on period in view of the fact-that it is not desirable: to deenerslze the ignition device im-' mediatelyupcn the establishment of combustion.

11; is therefore a prime object of the present invention to design a control apparatus fora A further object of the-invention is to design a 8 of the above type in which the timing means is energized upon a demand for burner operation for producing the proper timing functions and is deenergized during the normal operation of the burner. The above feature is parin the form oi a thermal timer in view of the is In many prior" art control systemsthis timing is obtainedqby means of a devicewhich is rea holding the safety switch in closed position, one

latches i4 and II system whichutiliaesanextremelysensitive combustion responsive device and which has thermal energizations, and

fact that-where the thermal timer is heated during the entire time that the burner is in operaing the termination of burner operation.

A further object of the invention is to provide a control system having a biased open safety switch and a pair of thermal actuators normally of saidactuators being heated upon-a call for burner operation to energize the burner and to close a heating circuit for the second actuator.

e as the arrangement being such that when both the The control apparatus of the present inventhermal actuators are hot the safety switch is tripped to open'position. A combustion responsive device is provided for the purpose of deenergizing both actuators in the event that com-- 80 bustion is established before the safety switch has been opened.

Other objects will readily become apparent to those who are skilled in the art when the following specification is read in the light of the an accompanying drawing in which:

\ Figure 1 is a more or less diagrammatic showingof a control system embodying my invention,

Figure 2 is a detail view of the safety switch and two latches taken along the line 2-2 of Figto are 1, and i ofstiflening 'ilanges l2 and I3 extending longitu'dinaliy of the member H. -A pairof latches M and II are mormted upon a rod I. carriedby v the flanges l2 and It at one end of the same member ll the arrangement being such that the are adapted to rotate about 'therod ll. Seel'lgure-ii. Abiasing spring ll onnected theirame il andattheotherendtoamember ll which is flxedto the opposite end ofthe Asecondbiaain'gspringflisconticularly important where the timing means is tion it absorbs such a large quantity of heat that 1 it is apt to require an excessive time period to dool 0E and return to its cold position followat one end to the latch it below" also to a second fixedmember 2 5 connected to frame ll directly in back of member is as seen in Figure l. A portion of spring it may be seen in the detail view shown in Figure 2. The two sprin s 88 and 26) therefore bias the latches, i l and it; for rotation in a clockwise direction as seen in Figure 1. Thelatch 85 is actually direetly be n the latch isles seen in Figure l. The latch 5 and member 26 are shown to extend slightly above latch is and member is respectively in Figure 1. They have been shown this way for the sake of. clarity only, as they are preferably of the same size.

A thermallyexpansible wire 22 is connected a one end to the latch iii just above the frame ii, and at its other end to thefixed member 6 9. Thus it can readily be seen that the biasing spring l8 maintains theexpansible wire 22 under tension and that upon expansion of thewire 22 the latch l will rotate in a clockwise direction and upon contraction of this wire the latch will be rotated in a counter-cloclswise direction. A secondexpansible wire 23 is connected at one end to the latch it just above the frame ii and at its 0D- posite end to the second fixedmember 2 5. The biasing spring. so will maintain the expansible nected to the latch it below the frame ii and border. Therefore the reference numeral ill in dicates the usual oil burner motor and the reierence humeral :32 indicates any of the usual types of-electric ignition devices for igniting the oil delivered to the burner by the motor 435.

The combustion responsive device has been indicated diagrammatically at 63 as comprising a switch arm t8 which is adapted to engage a cold contact 650: in the absence of combustion and at a hot contact iber in the presence of combustion. Although various types oi. condition re-- sponsive devices may be utilized successfully in I cember '2, L943. 7

this invention, I prefer to utilize the device which ant heat responsive device" and filed December 22, 1941, now Patent No. 2,336,399,-issued' Dclihis system may be controlled manually or may be controlled by any automatic control device which responds to a demand for burner opera tion. However for the purposes of thepresent wire 23 under tension, and as in the case of the awire 22, expansion of thewire 2%) will cause a rotation of latch is in a clockwise direction whereas a contraction of thewire 23 will cause rotation of thelatch 85 in a counter-clockwise direction. The twowires 22 and 23 preferably, al-'safety switch blade 25 will be resting upon the tip of the insulating portions 26 and 27 which are carried by the two latches it and i5 respectively. When theswitch blade 25 is in this position it will be in engagement with it stationary contact '28, or in other words the safety switch will be latched in closed position.

The latch id is provided with a portion so which extends horizontally beneath the frame H and which carries pivotally a rod 3| having two switch I actuatingportions 32 and 33. When theexpansible wire 22 is cold as shownin Figure l the-rod 3i willnbe in its lowermost position at which.

time the switch actuating member Siw'illengage the tworesilient switch blades 34 and 35 and hold them out of engagement with the switch. blades 36 and .31. When the wire 22' expands and;

permits clockwise rotation of the latch I the" disclosure I have shown the usual type of room thermostat in the form of abimetallic element 65 which is fixedat one end and which carries 7 contactld and then at a slightly lower temper-,

ature the contact blade 61? engages its stationary contact 39.

The control'system includes an electric relay which is shown as comprising a winding 50 and an armature indicated by the dotted line ti which, when the winding so is deenergized, occu= pics the position shown in Figure 1 in which the two switch arms 62 and 6d are in open circuit position and theswitch arm 83 is in engagement with its outcontact 65. Upon energization of the winding so the armature 60 will move to the left at which time the switch arms 62, 63, and

it will be in engagement with their stationary all rod 3| will be raised and will first permit thetwoswitch blades Hand 35 to move as a result oi. I

their own bias into engagement with the switch blades 38 and 3'! respectively. Further upward movement of therod.3l will cause the switch ac-,

t'uating member 32% engage the resilient-switchergized the burner motor and ignition devices will blade 38 andmove it into engagement with the switch blade 39. The function or these various:

switches will be explained in detail later inconnection with the operation of the systemes a v whole;

i The .present bontrol systemv may be adapted contacts 56, El and 5d respectively. p

The electrical power is supplied to the system from the supply lines lid and H which feed the P imary winding E2 of a step-down transformer lshgving a low voltage secondary winding l4.

' Operation maintain thesafety switch arm 25 in closed circult position and all of the switchesicontrolled by the actuating rod 3i will be in open'oircuit position. The relay winding 50 will be deenergized and'the combustion responsive switch arm will be in engagement with its cold contact a. Inasmuch as the relay winding is deenalso be deenergiz'ed.

Inasmuch as no heat is being supplied by the burner at this time, the temperature at thethermostat 45 will begin to decrease and the thermo-' Stat I! will begin to decrease and the thermostat will cause the flexible switch arm-46 to move into engagement with thestationary contact 48; No

circuit will be established at this time in'view of the fact that the relayarm is in its "out" position. The temperature at thethermostat 45 will therefore continue to decrease until the blade 41 is moved into engagement with thestationary contact 49. This will establish an energizing circuit for theexpansible wire 22 which extends from one side of the secondary winding I3 of thetransformer 13 through conductor I8,safetyswitch arm 25,contact 28, conductor TI,contact 48,switch blades 46 and 41,contact 49, conductors I8, I9. 80 and BI,contact 85, switch arm 63,conductors 82, 83 and 84, combustion responsive switch arm 44, cold contact 45a,conductor 85,expansible wire 22 andconductor 85 back to the other side of the secondary winding 14.

The establishment of the above circuit causes sufficient heating of thewire 22, due to its own resistance, to cause it to expand and permit rotation of the latch I4 in a clockwise direction as seen in Figure 1. Such rotation causes the actuating rod 3| to move upwardly and permit movement of theresilient contact blades 34 and 35 to closed circuit position. Theswitch blade 34 is in circuit with the ignition device 42 and in view of the fact that the switch arm 62 is still in open circuit position the movement of theswitch blade 34 into engagement with the switch blade 36 will not result in the establishment of a circuit .at this time. The movement of the switchblade expansible wire 23 is effectively shunted out by I means of theswitch arm 83 andcontact 85. Thus safety switch without putting undue strain upon the operating mechanism of the switch. These details have not been illustrated in this application which has been limited more or less to a diagrammatic showing.

The second result is accomplished by the move" ment of therelay switch arms 32, 63 and 3:3 into engagement with their stationary contacts 5 3, iii and 88 respectively. Movement of theswitch arm 64 into engagement withcontact 68 establishes a shunt circuit around the switch formed by the contact blade 4! andcontact 49. This circuit extends through theswitch blade 46, bimetal 45, conductor. 98,switch arm 64, contact 38 andconductors 99, 88 and I9. Thus when theswitch arm 84 has been moved to closed circuit position a holding circuit is set up to maintain operation of the system even though the temperature at the thermostat may rise sufiiciently to cause the switch blade 41 to separate fromcontact 49.

Movement of the switch arm 63 into its at tracted position first causes it to separate from thecontact 65 thereby breaking the original energizing circuit for theexpansible wire 22. This wire however remains energized at this time by a circuit which extends from one side of the secondary winding I4 throughconductor 16,safety switch arm 25,contact 28, conductor ll, contact 48,switch blade 46,bimetal thermostat 45,conductor 98,switch arm 64,contact 68,conductors 99, 88, I9 and 88,expansible wire 23, conductor no control action will take place until the actuating member 3I causes a movement of the resilient contact blade 38 into engagement with the contact blade 39. This establishes a circuit for 1 the relay winding 5|! which extends from one side of the secondary winding I4 throughconductor 15,safety switch arm 25,contact 28, conductor TI,contact 48,switch blades 46 and 41,contact 49, conductors I8 and 88,expansible wire 23,conductor 89,switch blades 31 and 35,conductors 90, 83 and 92, switch blades 38 and 39,conductors 93 and 94, relay winding 50, andconductor 35 back to the other side of the secondary winding 14.

Closure of the above circuit accomplishes two important results. In the'first place it energizes relay 58 and breaks the shunt around theexpansible wire 23 and starts this wire heating and expanding. It will be noted that theexpansible wire 22 is already in its heated state and therefore it has rotated the latch I4 from beneath thesafety switch arm 25, but this arm remains in its latched position due to the latch I5. Heating of thewire 23, however will cause the latch I5 to start to rotate in a clockwise direction and if this action is permitted to continue for a predetermined length of time, usually about 90 seconds, the latch I5 will move from beneath thesafety switch arm 25 and permit it to move to open circuit position as shown in Figure 3. At this time thearm 25 drops down out of engagement with itscontact 28 and into engagement with astop 97. The opening of the safety switch removes the power from the entire low voltage portion of the system and therefore deenergizes both of theexpansible wires 22 and 23 as well as the relay winding 58. The safety switch must be reset manually and if desired may be provided with the usual trip free reset which is now common in the art. In actual practice some strain release means would probably be provided between the latches I4 and I5 and thesafety switch arm 25 to permit theexpansible wires 22 and 23 to cool ofi and contract following the opening of the 89,switch blades 37 and 35,conductors 99, 83. 84, combustion responsive arm 44, cold contact 45a,conductor 85,expansible wire 22 andoohductor 88 back to the other side of the secondary winding 14. Therefore after the relay winding 50 has been energized theexpansible wire 22 and the relay winding 50 are connected in parallel and they are each connected in series with theexpansible wire 23. Note there is less current flowing through theexpansible wire 22 at this time, however this current is suihcient to maintain this wire in its heated condition so that the latch I4 will be rotated sufiiciently to permit thesafety switch arm 25 to drop to the position shown in Figure 3 should theexpansible wire 23 heat for a suflicient period of time to rotate the latch I5 frombeneaththe switch arm 25.

Movement of therelay switch arm 32 into engagement with contact will result in the es tablishment of a circuit for energizing both burner motor 4i and the ignition device 52. This circuit extends from the supply line 7! through conductor ICII, contact 65, switch arm con ductors I82 and I03, burner motor 4i and conductor I94 back to the other supply line l I. The ignition device 42 is energized by means or" a circuit extending from the supply line It through conductor I Hi, contact 86, switch arm 62, conductors I82 and H15,switch blades 34 and 3t, conductor I08, ignition device 42 and conductor I81 back to the other supply line ii.

If combustion is not established within a predetermined period of time theexpansible wire 23 will heat sufficiently to,release thesafety switch arm 25 as described above. This will cut off the power to the low voltage portion of the system and the safety switch will have to be manually reset in order to restart the system. Normally, however, the energization of v burner motor 4| and ignition device 42 will sult in'the establishment of combustion which will cause the combustion responsive switch arm 44 to move from engagement with its cold contact 45a into engagement with its hot contact of the secondary winding 14.

46a. This action will break the circuit through theexpansible wire 22 and will establish a holding circuit for the relay winding 59 which is independent of any of the switches operated by asraave of the combustion responsive switch arm 44 with 46,bimetallic element 45,conductor 99, switch.

arm 64,contact 68,conductors 99, 80 and I09,

hot contact 46a, combustion responsive switch arm 44,conductors 84, 83, 82, switch arm 63, contact 61, conductors H0 and" 94, relay winding 50 andconductor 95 back to the otherside Theexpansible wire 22 will now start coo and contracting in view of the fact that the circuit therethrough has been broken. This will cause the switch actuating rod 3| to move downwardly first permitting the switch blade 38 to move out of engagement with the switch blade 39. This will have no effect upon the system in view of the fact that a holding circuit for the relay winding 50 has been established independently of this switch. Further movement of the actuating rod 3| will cause theswitch blade 35 to move out of engagement with the switch blade 3?. This action will break the circuit through theexpansible wire 23. It is pointed out how ever that this wirewas effectively deenergized at the time that the combustion responsive switch arm 44 engaged the hot contact 46a 7 because the closure of this switch established a shunt around theexpansible wire 23 which extends from oneside thereofthrough conductors 88, 19, and I09, hot contact 48a, combustion responsive switch arm 44,conductors 84, 83 and 99,

switchblades 35 and 31, andconductor 89 to the other side ofhot wire 23. Thus the separation of theswitch blade 35 from theblade 31 has A no effect upon the system.

The lowering of the actuating rod 3| also causestheswitch blade 34 to separate from theswitch blade 35. It will be noted that these two blades are in the circuit to the ignition device 42 and therefore their separation will terminate operation of the ignition device. The circuit to the burner-motor 4| however is independent of.

this switch and therefore will continue in operation as long as the'relay winding 59 is energized.

The above is'the running condition of thesystem. It will be noted that as soon as combustion i established both of theexpansible wires 22 and 23 are effectively deenergized and will start contractingto prevent the opening of the safety switch. However theignition switch 34, 36 will remain closed and the ignition device energized until theexpansible wire 22 has cooled sumciently to open theswitch 34, 35. This provides for a proper post ignition period which is very desirable in the usual 'oil burner control system. It will benoted thatthe running circuit for the system passes serially through thethermostatic switch 48, 45, thecombustionresponsive switch 46, 44 and a holding switchwhich was closed by momentary power failure, a flame failure, or an increase in temperature of-theroomj thermostat 45 will cause the relay to 'be deenergized. In the event of a flame failure or a momentary power failure the original energizing circuit for theexpansible wire 22 will be substantially immediately reclosed by engagement of therelay switch arm 93 with its out contact sand engagement motor 4| and ignition device 42 until theexpansible wire 22 has heated sufliciently to cause movement of the switch blade 38 into engagement with the switch blade 39. The time required for theexpansible wire 22 to produce this action is sufficient to permit any unbiirned vapors which might cause an explosion to pass out of the combustion chamber and up the stack. In other words theexpansible wire 22 times the delay between successive burner energizations.

As many changes and modifications of this invention will undoubtedly occur to" those who are skilled in the art I wish it to be understood that I intend to be limited, not by the specific disclosure embodied herein, but only by the scope of the accompanying claims.

I claim as my invention:

1. A fluid fuel burner control system comprising in combination, fuel delivery means, means for igniting said fuel, a timer, a main switch, a safety switch in control of said fuel delivery and said igniting means, electrical timing means for opening said safety switch at the end of a timed interval, an energizing circuit for said timer controlled by said main switch, means operated by said timer when energized for rendering said fuel delivery means operative to deliverafuel and for energizing said igniting means and'electrical tim- "ing means for said safety switch, and means op- 'erating in response to combustion for deenerinterval, an energizing circuit for said timer controlled by said main switch, means operated by said timer when energized for rendering said fuel delivery means operative to deliver fuel and for energizing said igniting means and electrical timing means for said safety switch, means operating inresponse to combustion for deenergizing said timer and electrical timing means and maintaining said fuel delivery means operative independently of said timer, and means operated by said timer upon cooling for deenergizing said igniting means. I I

3. A fluid fuel burner control system comprising in combination, fuel delivery means, means for igniting said fuel, a timer, a main switch, a safetyswitch in control of said fuel delivery and said igniting means, electrical timing meansfoi opening said safety switch at the end of a timed interval, hot and cold combustion responsive switches, an energizing circuit for said timer indelivery means operative and for energizing sail i niting means, a relay switch closed by said elay when energized, said cold combustion responsiye switch opening upon the establishment o:

' switches/a relay, a first relay switch which is closed by said timer when energized, an energizing circuit for said relay including said main switch, electrical timing means, and first timer switch, means operated by said relay for rendering said fuel delivery means operative and for energizing said igniting means, means for opening prising in combination; fuel delivery means; a

heaters; means for closing said further switch said cold combustion responsive switch and closing said hot combustion responsive switch upon the establishment of combustion, a second relay switch which is closed by said relay when ener gized, a holding circuit for said relay including said main switch, hot combustion responsive switch and second relay switch, said last named holding circuit being connected in shunt with said electrical timing means for effectively deenergiz ing the same, and means operated by said timer upon deenergization thereof for deenergizing said igniting means.

10. A fluid fuel burner control system compris.. ing in combination, fuel delivery means, means for igniting said fuel, a timer, a main switch, a

safety switch in control of said fuel delivery and said igniting means, electrical timing means for opening said safety switch at the end of a timed interval, hot and cold combustion responsive switches, a relay, a first relay switch which is closed when said relay is deenergized, an energizing circuit for said timer including said main switch, first relay switch, and cold combustion responsive switch, a first timer switch which is closed by said timer when energized, an energizing circuit for said relay including said main switch, electrical timing means, and first timer switch, means operated by said relay for rendering said fuel delivery means operative and for means upon energization of said one heater;

means effective upon closure of said further switch means to establish energizing'circuits to said fuel delivery means and said other heater; and means including a combustion responsive device for deenergizing both of said heaters while establishing a running circuit to said fuel delivery means independent of said further switch means so that upon the cooling of said heaters and the resultant opening of said further switch means, said fuel delivery means remains in operation.

13. In a fluid fuel burner control system comprising in combination; fuel delivery means; means for igniting said fuel; a safety switch in control of said fuel delivery means; means including a pair of heaters efiective only when both of said heaters are energized to cause opening of said safety switch; a further switch means; means for energizing one of said heaters; means for closing said further switch means upon energization of said one heater; means efiective upon closure of said further switch means to establish energizing circuits to said fuel delivery means, said igniting means, and said other heater; and means including a combustion responsive device for deenergizing both of said heaters while establishing a running circuit to said fuel delivery means independent of said further switch means so that upon the cooling of said heaters and the resultant opening of said further switch means, only said fuel delivery means remains in energizing said igniting means, means for opening said cold combustion responsive switch and closing said hot combustion responsive switch upon the establishment of combustioma second relay switch which is closed by said relay when energized, a holding circuit for said relay includ ing said main switch, hot combustion responsive switch and second relay switch, said last named.

holding circuit being connected in shunt with saidelectrical timing means for effectivehr deenergizing the same, switch means in series with said electrical timing means opened by said timer upon deenergization thereof for breaking the circuit through said electrical timing means, and means operated by said timer upon deenergization thereof for deenergizing said igniting means.

11, A fluid burner control system comprising in combination, fuel delivery means, a biased open operation.

14. In fluid fuel burner control-apparatus for controlling a fuel delivery means; a safety switch adapted to control said fuel delivery means; means including a pair of heaters effective only when both of said heaters are energized to cause opening of said safety switcm'a further switch means; means for closing said further switch means upon energization of said one heater; circuit means including said switch means and said other heater and adapted to be associated with a fuel delivery controlling means in such a manher as to establish, upon closure of said further switch means, energizing circuits to said fuel delivery means and said other heater; and further circuit means adapted to be connected to a combustion responsive device and to said fuel de= livery controlling means for deenergizing both safety switch in control of saidfuel delivery means, first and second latches for maintaining said safety switch closed, first and second thermal actuators for said latches, said actuators, when heated, moving said latches in a directiom to release said safety switch for movement to open position, means for closing a, heating circuit for said first actuator in response to a demand for burner operation, means controlled by said first actuator and effective when said actuator is hot to render said fuel delivery means operative to deliver fuel and ti} establish a heating circuit for said second actuator, and means operating in response to the establishment of combustion for opening both of saidheating' circuits while maintaining operation of said fuel delivery means.

of said heaters upon theestablishment of combustion while establishing a running circuit to said fuel delivery means independent of said further switch means.

15.. Fluid fuel burner control apparatus for a fuel delivery means and means for igniting said fuel, a timer, means including a safety switch adaptedto be connected to said fuel delivery means and said igniting means for controlling the same, electrical timing means foropening said safety switch at the end of a timed interval, circuit means adapted to be connected to a main switch and to constitute when so connected an energizing circuit for said timer controlled by said main switch, further circuit means including said electrical timing means for said safety switch and-a switch operated by said timer, said further circuit means being adaptedto be connected to said fuel delivery means and said igniting means and effective when 50 connected to render said fuel delivery means operative to deliver fuel and to energize said ignition means and electrical timing means for said safety switch, means including said timer and electrical timing means and adapted in be -s0nnected to a device respnm we to summation and 30 said iuei dalivery means for deenergizing said timer and electrical timing G. ISSERSTEDT.

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