US1876281A - Burner control - Google Patents

Description

sept 1932 R. J. ElsEMAN 1,876,281

BURNER cou'rRoL Filed Nov. 17, .1930 2 Sheets-Sheet 1 )van fha-m. /7 l,

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4m? @ITW 'Patented Sept. 6, 19132' UNITED STATES PATENt ori-lcs ROBERT J. EISEHAN, OF WILLOUGHBY, OHIO, ABSIGNOB TO THE K-W. IGNITION COB- PORATION, OF CLEVELAND, OHIO, A. CORPORATION 0F OHIO mmm commer.

Application Med November 17, 1930. Serial No. 490,158.

This invention relates to improvements in burner controls, that is to say electric systems for automatically regulati the o eration of a burner so as to provide eat su cient to maintain the temperature of a room or series of rooms at a given point, within relatively close limits.

It is of considerable importance, particularly where certain fuels are employed, to guard against the discharge of fuel into the burner when no means for igniting the same is available, and it is also important to guard against employing too great a degree of heat in bringing the temperature u to the predetermined level after the rooms ave been cooled down considerably.

One object of the invention therefore is the provision of a safety switch for opening up the operating circuit when for any reason the furnace fails to heat up after the fuel is turned on in response to a call for heat from the room thermostat. Such a condition might arise for instance where there was a failure in the ignition of an oil burner.

Another object is the provision of means to maintain the operating circuit open or at safety until manually closed, thus insuring that the difculty will be given atten-l tion and correction.

Still another object of the invention is the provision of means for operating the safety switch electrically, and

'A further object is the provision of an additional safety circuit or line through a room thermostat and a thermostat associated with the heating unit, these latter thermostats being arranged in arallel so that if the temperature both in t e room and in the furnace should rise above predetermined points, the operating circuit wouldbe put -on safety.

Other ob'ects and features of novelty will appear as I proceed with the descriptlon of those embodiments of the invention which, for the purposes of the present application, I have illustrated in the accompanying drawings, in which igure 1 is a diagram of electrical clrcults emfpodying the invention, the burner being of Fig. 4 a further safety provision 1n accordance with which the operatin circuit goes on safety in the event that oth the room and the furnace temperatures rise above predetermined points.

In the drawings I have illustrated the invention as applied to an oil burner control system, but it should be understood that it is ually adaptable to controls for systems in w ich other fuels are employed, the necessary changes beingI readily made by one skilled in the art.

In the drawings a pair of alternating current service wires are indicatedat 10 and 11. An electric motor for feeding carbureted oil to the burner is indicated at 12, and the magnet of an electrically operated oil valve at 13. The sparking points of the ignition means are shown at 14, being in circuit with the secondary coil of a transformer 15.

Referring now particularly to Figs. 1, 2 and 3, 16 is the primary coil of a transformer employed for stepping down the voltage from the 110 volt line to 20 volts or thereabouts, as is most suitable for the control circuits. One leg of the coil 16 is connected with line wire 10 by a conductor 17. The other leg is connected through conductor 18 with the fixed end of a iexible switch arm 19 carrying a contact 20 that engages normally with the ixed contact 21 which is connected by a conductor 22 with line wire 11.

The operating circuit runs from line wire 10 through conductors 23 and 24. Motor 12 and fuel valve magnet 13 are arranged in parallel between conductor 24 and a conductor 25 which is connected to the fixed extremity of an arm 26 of thermostatic metal,

constituting one element of the operating switch. Upon this arm is mounted a contact 27 that is adapted to en age a contact 28 mounted onA another flexi le switch arm 29 that is electrically joined to the base or fixed extremity of the arm 19.- The thermostatic arm 26 also carries a projecting rod or ram 30 that is adapted to engage arm 19 and swing it so as to separate contacts 20 and 21, as indicated in Fig. 3. The conductor 24 is connected with a contact 31 against which rests normally an armature 32 that is pivotally mounted at 33 and there connected with a conductor 34 which runs to one leg of the primary coil of ignition transformer 15.

In the control circuit there are incorporated contacts 35 and 36 of a room thermostat and contacts 38 and 39 of a heat control thermostat 40, the latter thermostat being positioned in or upon the furnace and so arranged that its contacts close shortly after the burner ignites. The thermostatic switch v 37 works in the reverse manner, that is to say itscontacts 35 and 36 come together when the room temperature falls below a predetermined point, and theg open again when the temperature rises a egree or two above that point. v

The contact 36 is connected by aconductor 41 with one leg of a secondary coil 42 of the step-down transformer, the other leg being connected by a conductor 43 with contact 38. Contact 35 is connected-by va conductor 44 with a rela coil 45, and thence the circuit goes throng a conductor 46 to a second relay coil 47 and from there b way of a conductor 48 to contact point 39. Instead of relay coils and 47 I may em loy asin le coil with two armatures, and in act I pre er to do so, but for the sake of clearns and simplicit in the diagrams I have shown se arate co' The armature 32 is adap to be raised by the energization of coil 47, as indicated in Fig. 2. Coil 45 controls an armature 49 which normally rests upon a contact 50 that is connected b a conductor 51 with a heating coil 52, from t e opposite end of which a conductor 53 extends to conductor 43. From the pivot point 54 of armature 49 a short conductor 55 leads to conductor 44. The armature 49 is normally urged toward the position illustrated in Fig. 1, as by a coil spring 56. On the rear end of armature 49 ythere is a depending finger 57 which, when the coil 45 is energized, may take a position behind the flexible armv26 of the operating switchas indicated in Fig.' 2. When, as indicated in Fig. 3, the ram 30 pushes the switch arm 19 to the left to separate contacts 20 and 21 the upper end of that arm travels over a cam shaped surface on a latch 58 until it snaps into a recess in the latter. The latch therefore holds the contact 20 away from contact 21 until the latch is manually released.

Referring to the operation of the system illustrated in Figs. 1, 2 and 3, the condition of the system when the room temperature is at or above the predetermined desired point,

is shown in Fig. 1. At this time the valve 1,sve,2s1 I m et 13 is deenergized, the motor 12 is idle an there is'no current through the transformer-15. Now, when the temperature of the room falls somewhat the contact points 35 and 36 of the room thermostat 37 will come together. A circuit will thereb be set up through the transformer secon ary coil 42 and heating coil 52. This circuit may be traced from coil 42 through conductors 43 and 53 to coil 52, and thence by way of conductcr 51, contact 50, armature 49, conductors 55 'and 44 to contacts 35 and 36 of the room thermostat, and by conductor 41 back to coil 42. The coil 52 then heats up and the thermostatic arm 26 being positioned adjacent that coil, warps away from the position of Fig. 1 to that of Fig. 2, causing the contact 27 to engage the contact 28, thus closin the operating switch. 110 volt current now ows through the valve magnet 13, motor 12 and ignition coil 15. The circuit for the motor and valve may be traced from line wire 10 through conductors 23 and 24, through the motor and valve magnet in parallel, thence by way of conductor 25 to thermostatic switch arm 26, contacts 27 and 28, switch arms 29 and 19, contacts 20 and 21 and conductor 22 to line wire 11. At the same time the ignition transformer 15 is energized, the circuit including the conductors 23 and 24 leading from line wire 10 through contact 31, armature 32, pivot mary coll of e transformer 15 to conductor 25, and thence to line wire 11 through the same path as in the case of the motor and valve magnet circuit. Fuel is thereb fed to the burner and ignited by the sparks tween points 14.

The heat control thermostat 40 then begins to warm up and in a short time the contacts 38 and 39 thereof close, completing a circuit from transformer coil 42 through conductor 43, contacts 38 and 39, conductor 48, relay coil 47 conductor 46, relay coil 45, conductor 44, contacts 35 and 36 and conductor 41 back to cil 42. The armatures 32 and 49 are thereby swung upwardly on their pivots to the positionsv illustrated in Fig. 2. The circuit through the transformer 15 is therefore broken and ignition ceases. The circuit through heating coil 52 is also broken, but at the same time the linger 57 is projected downint 33 conductor 34, the priwrdly behind the thermmic switch am any time that when the room thermostat is calling for heat and the burner is in operation, the fire should go out for any reason whatever, the heat control thermostat 40 would be affected immediately, the contacts 38 and 39 would open, opening the circuit through relay coils 45 and 47 and permitting armatures 32 and 49 to fall back into the positions of Fig. 1. The system would then be reset for operation precisely as it was at the beginning of the cycle, that is to say the thermostatic switch arm 26 would be in the position of Fig. 1, having been released by the finger 57, the heating coil 52 would be energized, the ingition circuit would again funetion, and when the thermostatic arm 26 became warm enough it would warp into position to close contacts 27 and 28, whereupon the motor and fuel valve magnet would again start functioning.

If there should. be a momentary failure of current in the line wires 10 and 11 while the burner was in operation, the armatures 32 and 49 would fall and then swing up again. Thermostatic arm 26 would straighten up when the current went off and when it came ,on again finger 57 would descend in frontof arm 26 instead of behind it, thus latching that arm in the retracted position. 'The operating circuit would then be deprived of current until such time as the furnace cooled down sufficiently to open contacts 38 and 39 of thermostat 40, whereupon the armatures 32 and 49 would again fall, and all parts would be in position to begin the regular cycle of movements through which they pass to start the burner.

Fig. 3 illustrates what would occur in my system should the heat control thermostat 40 fail to function when a fire is started in the burner. Under such conditions the relay coils 45 and 47 would not be energized and the armature 49 would not rise to open the circuit through heating coil 52. The thermostatic arm 26 would then not s top warping when the contacts 27 and 28 engaged, but would continue until the ram 30 carried by the arm 26 pushed against switch arm 19, separating contacts 20 and 21 and driving the upper end of that arm past the cam surface of spring latch 58 into the notch of that latch. As the current for the motor 12, fuel valve magnet 13 and ignition coil 15 must pass through contacts 20 and 21, the burner would then cease to operate andthe switch arml19, which I have herein termed the safety switch, would be latched in open position and so held until manually released. The actuation of the safety switch is an indication that something in the system is out of order, and hence calls for a careful inspection and a correction of the difficulty.

If the contacts 38 and 39 of thermostat 40 should stick in the closed position instead of in the open position, it would result merely in a failure of the system to operate, because when the contacts `of the room thermostat would close the relay coils 45 and 47 would immediately become energized and would attract their armatures with the result that the circuit through heating coil 52 would be opened and the thermostatic operating switch 26 would not close.

Attention is called to the fact that ifthe system should function wrongly in any respect so as either not to energize coil 52 or not to terminate the energization of the coil at the proper time, no harm can result. In the first case the operating 4circuit would merely remain open. In the second case the system would go on safety, and all current through it would be interrupted, that is t0 say not only the 110 volt current through the lnotor, fuel valve magnet and ignition coil, but also the current through the primary coil 16 of the step-down transformer which furnishes low voltage current to the circuits including the heating coil 52.

In Fig. 4 I have illustrated a modification of the system embodying an electrical operation of the safety switch rather than an` operation directly by the warping of the thermostatic switch arm.` In other respects the system is the same as that previously described. In this form of the invention a conductor 60 extends from one leg of the primary coil 16 of the step-down transformer to a contact 61 which is normally engaged by an armature 62 that constitutes the movable element of the safety switch. The end of this armature `works against a cam surface on a latch 63 which corresponds in design and function with the latch 58 of the above described form of the invention. From the pivoted end of this armature a conductor 64 extendsqto line wire l1. To conductor 60 there is joined a conductor 65 which divides into two conductors 66 and 67 leading to the two coils of a balanced relay 68, one coil of which is attached through conductor 69 with contact 21, and the other coil of which is connected through conductor 70 with the fixed ends of switch arms 19 and 29.

Current for the operating circuit passes from line wire 10 through conductors 23, 24, motor 12 and fuel valve magnet 13 in parallel, conductor 25, thermostatic switch arm 26 and contacts 27, 28 (when closed by the action of the control circuit working through heating coily 52) to switch arm 29. From switch arm 29 the current passes in parallel through the two coils of relay 68, in one case through conductor 70, the lower relay coil line wire 1l. When both coils are thus ener-- gized their effect is neutralized and consequently the armature 62 is not attracted.

The operation is like that of the first described form of theinvention exce t that ifthe heat control thermostat 40 Y ails to function, resulting in the continued flow yof current through heating coil 52, ram 30 pushes against switch larm 19 to efpen contacts 20 and 21. Thereupon all o the operating current flows through the lower. coil lonly of relay 68, throwing the relay out of balance so as to attract varmature 62 and break not only the operating circuit, but also the circuit through transformer ,coil 16 which furnishes current for the control circuits. The' armature 62 is raised until its end springs into the socket of latch 63 and the system is thereby held on safety until the latch is manually released. The ordinary operation of the system is recisely the same as in the case ofl the first escribed the invention.

In the process of bringin the temperature of a room up from a low evel the furnace may get too hot. The system illustrated in Fig. 5 is designed to prevent such a condition. In this system I employ a thermostat associated with the heating unit. This thermostat may be located in the chimney or smoke stack, or it may be associated with the boiler or otherwise positioned to be affected directly by the operation of the furnace. It has two sets of contact-, s 71, 72 and 73, 74 which are normally closed, but which open when the heat that is permitted to come in contact with the thermostat exceeds a predetermined degree that is considered safe. The contacts 73 and 74' are interposed between the ends of conductor 23, which is a part of the 110 volt operating circuit. When thev temperature of the room or house has been permitted to fall far below the temperature for which the room thermostat is set, and the system is then permitted again to function normally, the furnace may become heated highly enough to open contacts 73 and 74 more than once in the process of bringing the house up to the desired temperature. Each time this occurs the operation of the burner merely ceases temporarily, owing to the fact that the system goes on safety position, and remains there until the safety latch is manually released. It occurs in this way. When the contacts 73 and 74 are disengaged, the circuit through the motor 12 and valve 13 is broken. The furnace then begins to cool, and thermostatic switch 38, 39 opens, permitting armature 49 to return to the position indicated in Fig. 5. Current form ofv In my system asshown in thisgure there is provided a further safety control the operation of which the system will go on safet should the temperature of the room ex the predetermined desired level and the temperature inthe furnace exceed the predetermined safe level both at the same time. In this way, if the contacts 71 and 72 should fail to open for any reason then, as soon as the room tem rature reached the predetermined level, t e system would go on safety and such a condition would constitute warning that something in the system was out of order and therepair of the ther-v mostat 90 would naturally follow, I will now ex lain how this condition comes about.

, n Fig. 5 the room thermostat 75 also carries two sets of contacts, the movable elements of which are to move together, an only one of which therefore need be made of thermostatic metal. These pairs of contacts are numbered 76, 77 and 78, 79 respectvel in the drawings. Contact 76 is conn to the conductor 44 of the control circuit, while'contact 77 is con-` nected through a conductor 80 with one leg of the secondary coil 42 of the step-down transformer. The other leg of that coil is connected through a conductor 81 and va. conductor 43 with lthe contact 38 of the heat control thermostat 40. One end of the heating coil 52 is connected thro h a conductor 82 and conductor 81 to the er le of coil 42. when vthe contacts 76, V77 of t e room thermostat close therefore in the ordinary functioning of thatthermostat, current may flow from the coil 42 through conductor 80, contacts 77, 76, conductors 44, 55, pivot point 54, armature 49, contact 50, conductor 51, heating coil 52, and conductors 82 and 81 back to coil 42. Coil 52 is thereby energized to warp thermostatic switch arm 26 and close the operating circuit as in the previously described forms of the. invention. Shortly thereafter the contacts 38 and 39 of thermostat 40 close also, and current flows fromV coil 42 through conductor 80, contacts 77 76, conductor 44, relay coil 45, conductor 46, relay coil 47, conductor 48, contacts 38 and 39 and conductors 43 and 81 back to the coil. The circuit through heating coil 52 is thereby opened and the finger 57 is caused to descend referably connected behind the war ed arm 26 in a manner similar to that indicated in Fig. 2.

Contacts 7 2 and 78 are joined by a conductor 83, while contacts 71 and 79 are joined by a conductor 84. Conductor y83 is connected by a conductor 85 with fixed contact 21, while conductor 84 is connected by a conductor 86 with the fixed end of switch arm 29. The latter arm is also connected, as in Fig. 4, with the lower coil of relay 68 by a conductor 70. In this form of the invention the operating circuit takes the following path: From line wire 10 through conductor 23, contacts 73, 74, conductors 23, 24, motor 12 and valve magnet 13 (also contact 31, armature 32, conductor 34, ignition coil 15) conductor 25, contacts 27, 28 (then closed) to switch arm 29. From this point the current through relay 68 divides, substantially half of it going directly through conductor 70 and the lower coil of the relay, while the balance takes the path through conductor 86, conductor 84, one or the other or both pairs of contacts 71, 72 and 78, 79, conductors 83 and 85, contacts 21, 20 and conductor 69 through the upper coil of the relay. Hence the armature 62 is not attracted. If, however, both sets of contacts 71, 72 and 78, 79 should be open at the same time, then all of the operating current would pass through the lower coil or relay 68 and the armature 62 would be' attracted and drawn into engagement with the latch 63, thus puttin the system on safety lhile in the foregoing description and in the accompanying drawings-I have disclosed certain particular embodiments of the invention more or less in detail, I desire it to be understood that such detail disclosure has been resorted to primarily for the purpose of fully illustrating the invention in accordance with the requirements of the statute, and that such disclosures are not to be considered as amounting to limitations upon the scope of the invention, except as they may be specifically defined in the appended claims.

Having thus described my invention, I claim:

1. In an electrical control system, an operating circuit comprising a thermostatic operating switch, adapted to be actuated by the application of heat, a heating coil for said switch, a first control thermostat in circuit with said coil, a second control thermostat, and electrical means controlled jointly by said first and second control thermostats for disabling said heating coil circuit and holding said switch inthe actuated position.

2.` In an electrical control system, an operating circuit, an operating switch for controlling said circuit, said switch having a thermostatic element adapted by the application of heat to move toward switch actuating position, a heating coil for said thermostatic element, a first control thermostat in circuit `with said heating coil, a second control thermostat, electrical rmeans controlled jointly by said 'first and` second control thermostats for disablin said coil circuit and holding said switch in t e actuated position, a safety switch adapted to disable said operating circuit, and means adapted to be set in motion by the continued movement of said thermostatic element for actuatingsaid safety switch in the event that said electrical means should fail to operate.

3. In an electrical control system, an operating circuit, an operating switch for controlling said circuit, said switch having a thermostatic element adapted by the application of heat to move toward switch actuating position, a heating coil for. said thermostatic element, a first control thermostat in circuit with said heating coil, a second control thermostat, electrical means controlled jointly by said first and second control thermostats for disabling Asaid coil circuit and holding said switch in the actuated position, a safety switch adapted to disable both of said circuits, and means adapted to be set in motion by the continued movement of said thermostatic, element for actuating said safety switch in the event that said electrical means should fail to operate.

4. In an electrical control system, an operating circuit, an operating switch for controlling said circuit, said switch having a thermostatic element adapted by the application of heat to move toward `switch actuating position, a heating coil for said thermostatic element, a first control thermostat in circuit with said heating coil, a second control thermostat, electrical means controlled jointly by said first and second control thermostats for disabling said coil circuit and holding said switch in the actuated position, a safety switch adapted to disable both circuits, means adapted to be set in motion by the continued movement of said thermostatic element foractuating said safety switch in the event that said electrical means should fail to operate, said safety switch being returnable manually to the actuated position.

5. In an electrical control system, an operating switch, thermostatic means for actuating said switch, an electric heating coil for actuating said thermostatic means, an electric circuit in which said coilis located, a second switch for controlling said circuit and a relay having an armature adapted when the relay is energized to actuate said second switch and hold said operating switch in actuated position.

6. In an electrical control system, an operating switch, thermostatic means for actuating said switch, an electric heating coil for actuating said thermostatic means, an electric circuit in which said coil is located, a second switch for controlling said circuit, a relay having an armature adapted when energized to actuate said second switch hold said operating switch 1n actuated position, and a safety switch folthe operating circuit, said safety switch being adaptedto 5 be actuated by the continued' movement of said thermostatic means in the event that 'said relay should fail to actuate said second switch.

7. In apparatus of the classdcribed, an 1 operating circuit, an operating switch for controlling said circuit, a thermostatic element adapted to actuate said switch, a relay having balanced coils connected in parallel lines to one side of said operating switch, said relay controlling said operating circuit, and means ada ted to be set in motion by said thermostatlc element for disabling one of said parallel lines when said thermostatic element is operated beyond normal switch 9 actuating-position.

8. In apparatus of the class described, an -operating circuit, an operating switch for .controlling said circuit, a thermostatic element adapted to actuate said switch, a relay 53 having balanced coils connected in parallel lines to one side of said operating switch, said relay controlling said operating circuit, means adapted to be set in motion by 4said thermostatic element for disabling one of said parallel lines when said thermostatic element is operated beyond normal ition, and thermostatic means also adap to disable one of said parallel lines when a given temperature is exceeded.

9. In an electrical control system, two thermostatic switches, both of said thermostatic switches having contacts adapted to open under temperatures exceeding predetermined heights, an operating circuit, arelay control- 4 ling said operating circuit and having balanced coils connected in parallel lines within said operating circuit, said two thermostatic switches being connected in multiple within one of `said parallel lines, whereby said last named parallel line is disabled whenever both of said thermostatic switches open their contacts. A

10. In an electrical control system, an operating circuit, an operating switch for said 5 circuit, a thermostatic element adapted when heated to throw said switch to actuated position, a holding means for maintaining said switch in actuated position, an electric heating coil arranged adjacent said thermostatic element, and a control circuit comprising 'a relay having an armature to which said holding means is connected.

In testimony whereof, I hereunto aix my signature.

ROBERT J. EISEMAN.

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