US2671502A

US2671502A - Fuel burner interlocking safety control

Info

Publication number: US2671502A
Application number: US130896A
Authority: US
Inventors: Ira E Mccabe
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-12-03
Filing date: 1949-12-03
Publication date: 1954-03-09
Anticipated expiration: 1971-03-09

Description

March 9, 1954 c FUEL BURNER INTERLOCKING SAFETY CONTROL 3 Sheets-Sheet 2 Filed Dec. 3, 1949 I N V EN TOR. IRA 6'. M (484'- March 9, 1954 I. E. MCCABE 2,671,502

FUEL BURNER INTERLOCKING SAFETY CONTROL Filed Dec. 5, 1949 3 Sheets-Sheet 5 INVENTOR. m4 5. m up:

Patented Mar. 9, 1954 UNITED STATES PATENT OFFICE;

FUEL BURNER INTERLOCKING SAFETY CONTR 15 Claims.

This invention relates to a new and improved electrical control apparatus and more particularly to apparatus of this character adapted to control the operation of liquid or gaseous fuel burners.

In a specific form it relates to a relay for the control of burner operating circuits, together with secondary circuits for control of the operation of said relay and mechanical interlocks, certain interlocks being electrically operated while others may require manual operation. More specifi cally, the apparatus includes a relay which is dependent upon a combustion responsive control device for maintenance of the relay in operation, other means being provided to initially bring the relay into operation and to maintain it in opera tion long enough for the combustion responsive device to be affected by combustion and to come into operation. Should combustion fail to take place within a redetermined period, the appacondition a combustion responsive element so that a burner circuit is closed to put a burner in opera.-- tion. The device then includes means to take over the conditioning of the device and make it responsive to the existence of predetermined flame or combustion conditions so that the control apparatus may continue running of the burner as long as proper conditions prevail. A suitable combustion responsive device is shown'in my co-pending application Serial No. 127,498, filed November 15, 1949-, which comprises a switch, the movable contact of which is moved in response. to the presence or absence of light emanatingfrom the burner flame.

The present invention represents an improvement over such devices disclosed in my prior Patents Numbers 2,024,697 of December 17, 1935; 2,075,951 of" A ril 6', 1937"; and 2,158,515 of May 16, 1939. In the apparatus disclosed herein, a time of operation-in responding to the-absence of flame to shut down the burner and cut-off fuel either when attempting to establish the" flame or maintain it, is so much faster that it may be advantageousl'y' used in connection with control of burners burning a high rateof fuel per hour.

It thus becomes-possible to use-with suchcapacityburners mechanical devices of the character herein disclosed which will assure positive protection against the delivery of large quantities of fuel Without means to ignite it and to terminate such delivery quickly upon flame extinguishment from causes other than a normal shut down of the burner.

It is an object of the present invention to provide relay control apparatus which, when associated with a suitable combustion responsive device, will initiate burner operation and stop said burner operation upon failure of combustion to take place within a predetermined time.

It is a further object to provide such apparatus which will stop burner operation should c0mbustion cease or be reduced below a predetermined level after it has been initiated.

It is an additional object to provide apparatus having a plurality of operating stages and means for progressively attaining said stages whereby the apparatus serves to initiate burner operation, provide a time delay to permit the operation to become effective and thereafter assume a stage of adjustment responsive to lack of illumination from flame of combustion or reduction of illumination intensity below a predetermined level.

It is a further object to provide apparatus which will return to its initial position upon cutoff of current supply and will automatically restore combustion upon resumption of current flow.

It is another object to provide apparatus of this character which will stop burner motor operation upon failure of ignition within a predetermined time and', also, upon interruption of flame propagation for a predetermined time and which requires manual reset to restore normal burner and control.

It is still another object to provide apparatus which will be dependent upon the proper functioning of a combustion responsive safety device in order to initiate and maintain operation of the burner in response to a demand for its operation with each initiation of a burner operation requiring the combustion device attaining its operative position indicative of no combustion and the maintenance of burner operation requiring the combustion device attaining its operative position indicative of the presence of combustion and, further, that no operation of the burner may occur if the circuits controlled by the combustion device are improperly made or short circuited.

Other and further objects will appear as the description proceeds.

I have shown certain preferred embodiments of 3 my invention in the accompanying drawings, in which- Figure 1 is a front elevation showing the working parts of the control apparatus;

Figure 2 is a somewhat schematic wiring diagram of the apparatus and of the device controlled thereby;

Figure 3 is a horizontal section, partly broken away, taken on line 3-3 of Figure 1;

Figure 4 is a fragmentary view, on an enlarged scale, showing the parts of the control in the idle position;

Figure 5 is a view similar to Figure 4 showing the parts under normal running conditions;

Figure -6 shows the parts in the automatic cutoff position; and

Figure 7 is a fragmentary view showing a modified form of safety lock-out construction with the parts in operating position.

In order to better explain the operation of the control apparatus, reference will be made first to the general circuit layout shown in Figure 2. Here, the control apparatus is shown as mounted on a base I I and comprising a closed transformer core I3 secured to the base and carrying the transformer primary coil I4 which is fixedly supported thereon. One side of this primary coil I4 is connected through a normally closed safety lock-out switch I30 to terminal It, whil the other side of the coil is connected to terminal I8. The terminals I6 and I8 are fed from regular power line alternating current of standard voltage, such as 115 volts, through the lines 29 and 2|. This application discloses different structures as regards the look-out safety feature of the invention. One form, strictly mechanical, is described with respect to its representation in Figure 6. In this form the safety switch I30 may be omitted and the two sides of the primary coil I4 connected directly to terminals IB and Ill. The other form including switch I30 is described in connection with a detailed showing of the switch operating structure in Figure 7.

Power line passes through a boiler limit control 23. It will be understood that this boiler limit control comprises a normally closed switch. which, however, may be opened by abnormal boiler conditions, such as excess pressure or excess temperature. Such controls are well known and its specific construction forms no part of the present invention.

- The tiltable mercury switch is carried on one end of the rockable carrier 26, the latter being pivoted at 21 on the transformer core I3. This mercury switch 25 is shown in Figure 2 in its open position, the two contact members of the switch being connected to the terminals l6 and 29 respectively. The terminal 30 is directly connected to the incoming line terminal I8.

Wires

32 and 34 lead from the

terminals

29 and 30 to the burner motor 36. The ignition transformer 38 is connected in parallel with the burner motor 36 by the wires 39 and 4B. The ignition gap is shown at 42 with the grounded electrode 43. As thus shown, ignition is constantly provided as long as the burner motor is energized. When it may be desired to cut off ignition a predetermined period after initiating burner operation, any desired form of ignition cut-off means may be interposed in the ignition circuit to accomplish this. One such form may be that disclosed in my prior Patent No. 2,287,386 of June 23, 1942.

The secondary coil 45 on the transformer core I3 is supported by the rocking carrier 26 on the opposite side of the pivot 21 from the mercury switch 25. One side of the secondary 45 is connected to terminal 41, with the other side being connected to terminal 48. The light responsive switch 52 includes a fixed contact 5| which is connected by wire 52 to terminal 58. The switch 50 includes movable switch member 56 which is externally connected to wire 51 leading to terminal 48. It will be noted that, in the specific forms of construction shown, the fixed terminal 5| terminates in contact with a globule of mercury 59, a portion of the mercury being drawn up in the capillary tube 60. The mercury in the tube Si] is exposed through an opening 6I for engagement by the movable contact 55. This movable contact is moved by expansion of the expandable member 63. This member is expandable by the application of heat, either directly or as heat derived from the concentration of light rays of the flame upon the member 63. The member 63, being dark and opaque, absorbs the light rays and the light energy is converted into a form of heat energy.

The heating coil is connected at one end to the wire 51, this being the same wire to which the moving contact 56 is connected. The other end of the heating coil 65 is connected by wire 61 to terminal 54. The room thermostat 10 is connected by wire H to terminal 68 and by wire 13 to terminal 41. The solenoid coil 16 is connected by wire 11 to terminal 54 and by wire 19 to terminal 68. This solenoid 16 is provided with a fixed iron core 80.

The particular construction of the light and heat responsive switch 50 forms no part of the present invention, this being covered by my copending application Serial No. 127,498, filed November 15, 1949. The thermostatic switch 15, also, forms no part of the present invention. This may be any standard type of heat responsive thermostat located in a room or other space being heated by the apparatus which the present device serves to control.

It will be apparent from an examination of the circuit diagram that, assuming the given boiler conditions are normal and the boiler limit control 23 is in normal position with closed contacts, then the established line voltage is continuously applied through wires 20 and 2| and terminals I5 and I8 to the primary I4 of the transformer. This transformer is of th relay type with the secondary 45 pivotally mounted on the rocking carrier 26, as has been described. When the transformer secondary 45 is included in a closed circuit of. such character that it draws a substantial amount of current, the magnetic repulsion is such that the secondary 45 is thrust away from the primary I4. This causes the car-' rier 26 to rock in the counterclockwise direction about its pivot 21 which tilts the mercury switch 25 to such a position that the mercury therein closes the circuit through the switch. It will be apparent that, when the circuit is closed through the switch 25, line current is supplied through the switch both to the burner motor 35 and the ignition coil 38.

However, this action only takes place when a closed circuit is provided including the secondary 45, the circuit drawing suificient current to cause the necessary magnetic repulsion. It will be apparent that the circuit through secondary 45 may be closed through terminal 48, wire 51, movable switch contact 56, fixed switch contact 5 I, wire 52,

terminal 68. wire 1|, thermostat 10, wire 13 and back through the terminal 41 to the other side of the secondary. It will be noted, howeventhat under-normal conditions-,gwiththe motor oitand fireout, the switch 5.6 is:open so. that thecircuit will not be closed as described;. Analternatecircult: extends from the: secondary 45 through terminal 48', line heating: resistance. 65,.linezfil, terminal: 54 ,.line; 1.1-, solenoid 1.6,. line 1.9, terminal 63,, line 1 I ,.r.oom:, thermostat l0 and: line 13 backto terminal 4]. In thiscase; both the. heating coil fii andsolenoid coil 16 are connected in series with;the= secondary 4.5: It. will be further noted, however, that.v the circuit doesxnotibe'come closed. until. the room. thermostat becomes closed under: the temperature conditions: for which that thermostat adjusted.

Whenthealternate circuit is closedby: the room. thermostat; current flows through. the transformer: secondary: circuit but, with the heating coil 65and/or-solenoid16 being included therein, sufilcient resistance is interposed inthe circuit'to reduce the current flow: so that repulsion of the secondary coil does not occur; heating: coil isenergized and it will be apparent thattheheating coil 65, being inclose proximity to the expandablemember 63, will heat that member to. such an extent as to swing'the-moving contact 56 into-engagement with the mercury at El: and" establish a circuit through the mercury pool at 59 through. fixed contact 51 and back through line 52 to'the terminal 68. Thus, as previously described, the secondary circuit across terminals 41-48, including the relay secondary 45 and thermostat I0; is completed and, as a result, the alternate circuit, including the heating coil B5 and solenoid' 16', is shunted where'- upon magnetic repulsion: of the secondary coil" occurs to close the mercury switch 25. Upon initiating burner operation, the establishment of flameprovides asource of' light from which the switch derives heat to maintain the expand able-member 63 inheated condition, which heat replaces thatcut off' when the heating coil 65 is shunted. The member 63 is adapted to'be exposed to the light radiating from the burnerflame and, being dark and opaque, light rays are absorbed and the light energy converted into heat. The expandable member 63 is heated sufficiently by the heating coil 65, when eifectinga closure of the switch contact, that opening-of the switch contact upon de-energization' of the coil will not take place before a predetermined lapse of time which is of such duration that, normally, establishment of combustion and heating of member 63 by radiant energy will occur-to maintain the contact in closed position. Therefore, with the normal establishment of combustion, the switch 50 remains closed after de-energization of the heating coil 65' and will remain closed for continued operation of the-burner as longas the demand for same is made" and the burner flame exists.

The motor circuit must, however, be opened if a flame fails to appear toactuate the switch 50' afterthe lapse of time provided for'establishment of combustion occurs. This control is adapted forusein connection withburners using subs-tam tial quantities of oil perminuteand, if the burner is operating but. the. liquid fuel is not ignited, there will be not only substantialv losses of. fuel, but fuel will flow into the combustion. chamber in quantities which can become. very dangerous.- Itis important, therefore, that the control be. so' designed that it not only terminates operation of the motor 36 and, consequently, flow of fuel when thefiame isextinguishedfor any reason but-,also, mustrtpromptly take the same action. if. the. fuel.

However, the

failsto. ignite and produce-a flameinacompara: tively. short time after the motorisput. in opera-.-

tion. 1

They apparatus is-designed to. take careof; these several contingencies and: the. various interlocks: of: themechanical means: controlling the move;- ment of therocking-carrier 26 and, consequently, the motor circuit. controlled: by the: mercury switch 25 areshown in Figure 1 innormalinactive view and are shown on. an enlarged. scale: in Fig.-: ures:3-. to. 6.. inclusive.

Referring first to Figure 4 showing the: parts in the-idle position, that: is, with the burner motor off, the relay release catch'ili ismounted to swing. freely onthe pivot 86, being held. inv position. on; the pivot by the u-ring 81. The release.v catch is' so weighted :relative to its pivot 86*that. it would. be normally positioned. by gravity in a position. swung slightly counter-clockwise from thatirr which it is shown in Figure 4 were it not. for the interposition of the. stop. arm 93'. The relay release lever is'pivoted on the fixed pin. 91, this. relay release having the transversely extending stop. arm 93, one edge of which is adapted to engage the shoulder 94 formed. onv the lower portion of the relay releasecatch '85. In other positions of. the parts, this stop arm 93 passes above. the ledge 95' which. is located immediately above: the shoulder 94.

The relay release catch 85 is provided with a contact finger 91 which, in certain positions of the parts, engages thelower-transversely"extend-- ing abutment portion. 99 of the safety latch car-- rier. Hll The relay release 90 is further provided with an. upwardly.- extending portion I03, upon the forward. face of which is secured a small iron section I05 adapted to be attracted by the core 80 of the solenoid iii-when thatsol'enoid is energized. The safety latch carrier I01 is shown as pivoted on thepivot member 21 to which is pivoted the carrier 26Jcarrying the transformer secondary 45; This'safety latch carrier HII', however, is movable on the pivot entirely independ ent ofmovement of thecarrier 26which supportsthe secondary 45', but is weighted to the right of itsfpivot so asto assume aposition by gravity normally resulting in its movement asa unit with the secondary coil 45. This safety latch carrier lill. has an inturned portion at 101 to which is connected an arm I08 extendingparallel with the main portion off'the safety latch carrier I Ill. An iron section I09 is secured to the arm I08 so that, when placed inthe proximity of core 80 of solenoid 16, it may beattractedby the core when the solenoid is energized.

The safety latch III is pivoted at Hi! upon the" safety latch carrier llll. This safety latch has: an operating arm H3 which may beengaged. manually or by any desired operatingnreans, not shown, for swinging the safety latch H1l in the: counterclockwise direction about itspivot H2. A safety catch H5 is secured tothe relay secondary construction by the screw- H6; This? catch H5; therefore, moves with the secondary' 45 and independently of" the latch IH. The safety latch HI' isprovided' with a notch 8' adapted, under certain conditions, to engage the left side of the safety catch H5, as shown, for example,. in Figure 6.

The repulsion of the secondary 45 normally causes movement of; the latch carrier I'DI, which. is moved by and. with the. secondary since the upper corner l2! of the secondary carrier assembly engagesvthe. transversely extending nortioni l'llJ- of; the safety latch carrier, which car rier is weighted to the right of the pivot 21 whereby it assumes, by gravity, its position in abutment with corner MI. The safety latch II I carried by the safety latch carrier l9l normally rests upon the safety catch I 15, as shown in Figures 1 and 4, so that this latch Ill moves with the carrier l9l as a unit with the secondary coil 45 as it swings about its pivot 21.

Theapparatus i shown in its normal or nonoperating position in Figure 4 of the drawings, in which case the secondary 45 is swung downwardly immediately adjacent the primary. The parts are also shown in this position in Figure 1; In this position, the relay release lever 99 has its stop arm 93' in abutment with portion 99 of the safety latch carrier I9l in substantially direct alignment with the relay release lever pivot 9| so that, with the parts in this position, the stop arm 93 prevents the secondary 45 from being swung upwardly and, as a consequence, prevents the mercury switch 25 from being swung to the operative or closed position.

When the initial circuit is closed by means of room thermostat I9, the electromagnet 16 is energized and attracts the magnetic section I95 carried by the relay release member 99, thus lifting the stop portion 93 of the relay release lever 99 so that it clears the shoulder 94 and also clears the abutting portion 99 of the safety latch carrier l9l.

' When the flame switch 59 becomes operative and closes to establish the running circuit, the secondary 45 is repelled and assumes the position shown in Figure 5. This flame switch 59 is initially operated by heat derived from the resistance coil 65 which, as has been previously described, is placed in the circuit at the same time as the solenoid 16 of the electromagnet. It is to be understood that the manner of operation of the flame switch 59 is such that light rays from the flame focused upon the temperature responsive element 63 will maintain the element heated and maintain the switch circuit closed after the heating coil 95 is de-energized. De-energization of the heating coil 65, as well as the solenoid 19, occurs with the closure of the switch 59, as previously described.

Relay devices of the character and for the purposes herein disclosed are intended to operate to provide a closure of the relay switch, that is,

the mercury switch 25, at a voltage not less than below the rated voltage of the relay. At the lower portion of its operating range, the repulsion of the relay secondary is not as forceful as under the higher voltage conditions prevailing at the upper portions of its operating range. Since the magnet 16 is de-energized at the time of the repulsion of the secondary 45, it would not be desirable for the relay release 99, with its stop member 93, which release is no longer held by magnet 15, to fall back to block the repulsion of the secondary 45 when the movement of this secondary is slow due to low voltage conditions. If such a low voltage condition exists, the relay release catch 85prevents the dropping of the relay release stop portion 93 to a blocking position upon de-magnetization since the portion 93 rests on the ledge 95 of the catch 85. As has been stated, the catch 95 is so balanced that gravity causes it to swing under the relay release portion 93 when that portion is lifted above the shoulder 94. This permits the secondary to continue to move to its repelled position, whereupon the relay release catch 85 is swung to the left or. in; the cl ockwise direction about its pivot 96 by contact of the lower finger 91 with the abutment portion 99 of the safety latch carrier I9l,*as shown in Figure 5. I

Figure 5 shows the position of the parts under normal running conditions. Here, the secondary coil 45, safety latch Ill and the safety latch carrier I9l have moved upward as a unit andthe burner switch 25 is closed. During this movement, the abutment 99 of the carrier I9! has engaged the lower end 91 of the relay release catch 85 to release th relay release member 99 which, being no longer held by the magnet I6, drops back to its idle position. In this position, the stop portion 93 is in a slot I22 formed in the latch carrier I9l above the abutment portion 99.

It is to be noted here that should a current interruption of a momentary nature take place in either the primary [4 or the secondary 45, resulting in the de-energization of the secondary, it will fall back to its position, as shown in Figs ures 1 and 4, and this will restore the relay re.-: lease latch 99 and its portion 93 to the, position shown in Figure '4, preventing repulsion of the secondary coil 45 even though current be restored to the primary and secondary after its interruption. What is now required to restore operation of the control apparatus is an opening of the circuit passing through the flame switch 59 which, in the form of construction disclosed, occurs in about five seconds, provided the heater therein is not contributing any heat. In case the heater 65 has been in circuit, the time may approach a maximum of fifteen seconds. With the opening of the contact 56 of the flame switch 59, the circuit, including the electromagnet I6, is restored, the relay release 93 freeing the safety latch carrier MI and permitting the device to again reach the running position of Figure 5, as has been previously described.

Figure 6 illustrates the parts in the position assumed when through failure of ignition of the burner, no flame has been established to main tain the heating of the actuator or expandable member 93 of the flame switch 59, which heating is required to maintain the contact 56 closed, after de-energization of the heating coil 65. The parts will take the same position when, after the flame has been ignited, it goes out and there is a cessation of heat emanating from the light rays of the flame. With regard to the operation upon ignition failure, attention is invited first to the parts as shown in Figures 2 and 5. It is to be noted that when the heater 65 of the flame switch causes closure of the contact 59 therein to complete the running circuit, the repulsion of the secondary 45 which takes place places the upper left extremity I99 of the safety latch carrier' MI in the magnetic field zone of the magnet. At this time, however, by virtue of the fact that the running circuit is energized, the magnet 16 is de-energized. The burner switch being closed, combustion and establishment of a flame for maintaining the flame switch 59 closed should take place. If this does not take place, flame switch 59 will open circuit, thus restoring the initial control circuit, which includes the electro-' magnet 19 and the flame switch heater 65. Two different actions now take place. First, energization of the magnet 16 causes it to attract and hold the magnetic section I99 of the safety latch carrier l9! which holds that carrier in the position it had assumed upon closing of the flame switch 59 by the heater 65 therein. Second, the establishment of the preliminary control circuit when the flame switch 59 opened restored the resistance of the magnet coil 16 and the switch heater 65 into the circuit of the secondary coil 45, which results in reducing the value of the current passing through the secondary below that required to maintain the secondary repelled from the primary and in its upper position, as shown in Figure 5. The secondary 45 thus falls and the parts assume the positioni-n which they are shown in Figure 6. Thus, in Figure 6, the magnetic portion I09 of the safety-latch carrier IOI is in contact with the core80 of the magnet Hi, holding the carrier IIII in its upper position while, on the other hand, the secondary 45 has fallen to its lowerp'osition where 'i t'rests on the primary I4.

The safety latch III carried by the carrier 'IUI, which latter is held bythe magnet 15,:also assumes a'position swung to'the left, as viewed in Figure 6,. so that the safety catch notch I I8 has passed over the safety catch -I I5. With the parts in this position, as the heater 65 in the flame switch 50 is caused to heatand to close the-switch 58, the expected repulsion of the secondary coil 05 to close the mercury switch 25 does not take place because the relay safety catch I I5 engages the-notch H8 and its upward movement is arrested. As long as the circuit of the room thermostat I remains closed, there'will occur a con-- tinuous opening and closing of the contact 55 of the flameswitch 50 by virtue of the alternate energization of the preliminary circuit and the running circuit through the heating and cooling of the :expandable'element 63 of the flame switch 50, but without resulting in the closing of the mercury switch 25.

The safety latch II I is provided, however, at its left end with the extension piece of actuating member II3 which is adapted to be engaged by any suitable means, not shown, whereby the lower portion of the extension I'I'3 may be pushed laterally to the right to swing the safety latch II I around its pivot I I2 in the counter-clockwise direction. This movement will free the notch II8 of the safety latch from the latch member H5 and permit a subsequent repulsion of the secondary coil to take place so that the parts will return to the position shown in Figure 5.

This will again close the circuit through the motor switch 25 and put the burner into operation. Should the "burner again fail to ignite, the previously described action will take place and the secondary will again drop down, the latch II 5 again engaging the notch 'I I8.

The form of construction shown "in Figure '7 is generally similar in construction to that shown in Figure 6 but is provided with a different form of latch and a normally closed mercury switch I 30 connected in the primary circuit as shown in Figure 2 or, if desired, interposed in the burner motor circuit. This switch I30 and its associated structure accomplishes the same result of shuttingdown the burner after ignition failure until corrective measures have been taken to assure ignition and the control reset as the struc ture of Figure 6. Whereas ignition failure with the structureof Figure 6 results in the mechanical lock-out of the burner switch 25, the modification shown in Figure '7 accomplishes the same result by opening the normally closed mercury switch I30. The apparatus includes the electromagnet having the solenoid coil "16 and core 80. The secondary coil 45 is supported on the carrier 26 pivoted on pin 21. A mercury switch I30 is carried by the bell crank lever I32 which is'pivoted on the pin I34. The bell crank I32 has a long arm I35 carrying a roller I31 near its upper end, the arm and roller being of such weight that with their long lever arm they tend, by gravity, to swing the bell crank lever I32 in the clockwise direction about the pivot pin I34. The lever I32 and switch I30 are shown in Fig ure '7 in the closed circuit position.

"A roller engaging member I38 is pivoted on pin 21 in the same manner as the latch carrier IOI of the other form of construction, and moves 'in'the counter-clockwise direction with repulsion of the secondary 45. The member I38 has an upwardly extending arm I40 whichha's an upper arcuate surface [+32 upon which the roller I3! may rest. The member I38 also has'a forwardly extending arm I44 carrying an iron section I45 adapted to be attracted bythe magnetized core of the electromagnet. The fixed track member I fl is carried by the secondary 45 and always moves therewith. Thismember I41 has an upper arcuate surface I48 which, as shown in Figure '7, serves as a continuation of the arcuate surface I42 of member I38.

In the operation of this form of construction, when the flame goes out or there is failure or initial ignition, and the first control circuit is again closed as described in connection with the form of construction shown in Figures 1 to 6, the solenoid l6 isenergized and core 80 attracts and holds magnetic member I45, thus holding the member I38 in the position shown in broken lines in Figure 7. At this time, the current flow through the secondary 45 is inadequate to maintain it repelled from the primary and the secondary returns to the full line position of Figure '7 carrying with it the fixed track member *IE'I, upon the upper arcuate surface of which the roller I31 has been resting. This roller then drops down between the rear of the upwardly extending arm I40 of the member I38 and the front of the member I47. This movement is caused by gravity and the switch I30 is swung upwardly and opens the circuit. The switch I30 is normally connected in the main circuit to the transformer primary and, when open, cuts off all current to the apparatus. To resume operation again, the switch is reset by manually rotating the bell crank I32, carrying theswitc'h I30, in the counter-clockwise direction to restore it to the position shown in Figure 7. When the bell crank is so rotated, the member I38 will drop back by gravity as the electromagnet is no longer energized and all parts will be restored to the full line position of Figure 7 with the pin I31 resting on the arcuate surface I42.

The repulsion relay, as shown in the drawings and described, is arranged to operate on alternating current with low voltage current'bein'g induced in the secondary when the relay is energized. It is to be understood, however, that the relay may be adapted to direct current applications by properly connecting the pair of coils together so that one is repelled from the other. when both are energized.

The invention, as disclosed herein, comprises a controlling device for liquid or gaseous fuel burners meeting the aforementioned objectives in 'a manner which renders its operation dependent upon proper functioning of a combustion device, which latter device is responsive to normal combustion conditions to permit burner operation and responsive to abnormal combustion conditions, or, failure to attain combustion, to prevent burner operation. With the combustion responsive device acting as a safeguard against burner operation under abnormal conditions, the present invention provides that com bustion be attained and continued thereafter through the process if a particular sequence of control operation and only of the combustion responsive device, upon which sequence of operation is made dependent, is operative to perform its safeguarding functions against the establishment of hazardous conditions. Each recurring operation of the burner, after a shutdown, must await the return of the combustion responsive device to its normal starting position and the operation of the burner, upon the proper functioning of the combustion responsive device upon initiating and establishing combustion.

While certain preferred embodiments of the invention have been shown, they are to be understood to be illustrative only as it is capable of further variation to meet diiiering conditions and requirements, and I contemplate such modifications as come within the spirit and scope of the appended claims. Also, the apparatus may be used with other devices than the flame switch disclosed in my co-pending application to which reference has been made. Other forms of electrothermal actuators may be used in the initiating circuit to close the switch establishing the running circuit and other forms of combustion responsive switches may be used to parallel the electrothermally actuated switch to maintain the running circuit, permitting the electrothermal actuator to cool and open its switch.

I claim:

1. Fuel burner control apparatus comprising a relay having actuating means for closing connections to a burner circuit, means for energizing said relay to operate said actuating means, an initiating circuit including said relay energizing means, resistance of such value as to prevent passage of sufficient current to operate the relay and an electromagnet; a low resistance shunt relay operating circuit, mechanical means for blocking the actuating means, said means being movable to unblocking position by attraction of said electromagnet upon energization of the initiating circuit, and means responsive to energization of the initiating circuit to elfect closure of the shunt circuit reducing the resistance and permitting operation of the unblocked relay and responsive to combustion to maintain the shunt circuit closed while combustion continues.

2. Fuel burner control apparatus comprising a relay having actuating means for closing connections to a burner circuit, means for energizing said relay to operate said actuating means, an initiating circuit including said relay energizing means, resistance of such value as to prevent passage of sufficient current to operate the relay and an electromagnet; a low resistance shunt relay operating circuit, mechanical means for blocking the actuating means, said means being movable to unblocking position by attraction of said electromagnet upon energization of the initiating circuit, means responsive to energization of the initiating circuit to effect closure of the shunt circuit reducing the resistance and permitting operation of the unblocked relay and responsive to combustion to maintain the shunt circuit closed while combustion continues, and a latch for blocking further operation of the actuating means, said latch being rendered operative by attraction of said electromagnet upon restoring the initiating circuit following combustion failure.

3. Fuel burner control apparatus comprising a relay having actuating means for closing connections to a burner circuit, means for energizing said relay to operate said actuating means, an initiating circuit including said relay energizing means, resistance of such value as to prevent passage of sufficient current to operate the relay and an electromagnet; a low resistance shunt relay operating circuit, mechanical means for blocking the actuating means, said means being movable to unblocking position by attraction of said electromagnet upon energization of the initiating circuit, means responsive to energization of the initiating circuit to effect closure of the shunt circuit reducing the resistance and permitting operation of the unblocked relay and responsive to combustion to maintain the shunt circuit closed while combustion continues and upon combustion failure to open the shunt circuit and restore the initiating circuit, a normally closed switch controlling the burner circuit, and means responsive upon restoring the initiating circuit and subsequent operation of the relay to open the burner circuit, to open the normally closed switch.

4. Fuel burner control apparatus comprising a repulsion type relay, connections for closing a burner circuit upon actuation of the relay, mechanical means normally blocking repulsion of the relay secondary, an initiating circuit including the relay secondary, resistance of such value as to prevent passage of repulsion current through the secondary and electrical means for unblocking the secondary; a low resistance shunt relay operating circuit including the relay secondary. the initiating circuit when energized operating the means for unblocking the secondary, and means responsive to energization of the initiating circuit to effect a closure of the shunt circuit reducing the resistance and permitting re pulsion of the secondary and responsive to combustion conditions to maintain the shunt circuit closed while combustion continues.

5. Fuel burner control apparatus comprising a repulsion type relay, connections for closing a burner circuit upon actuation of the relay, mechanical means normally blocking repulsion movement of the relay secondary, an initiating circuit including the relay secondary, resistances of such value as to prevent passage of repulsion current through the secondary and electrical means for unblocking the secondary; a low resistance shunt relay operating circuit including the relay secondary, said initiating circuit when energized operating the means unblocking the secondary, means for maintaining the secondary unblocked until said secondary has been moved to operating position, and means responsive to the energization of the initiating circuit to eflect closure of the shunt circuit reducing the resistance and permitting repulsion of the unblocked secondary and responsive to combustion conditions to maintain the shunt circuit closed whilecombustion continues.

6. Fuel burner control apparatus comprising a repulsion type relay, connections for closing a burner circuit upon actuation of the relay, an initiating circuit including the relay secondary, resistances of such value as to prevent passage of repulsion current through said secondary, and

' an electromagnet; a low resistance shunt relay operating circuit including the relay secondary, mechanical means for blocking repulsion of the secondary, said means being movable to unblock-.. ing position by attraction of said electromagnet :upon .energization of the initiating cir'cuit, a-nd means responsive to the venergization of the initi- .a'ting circuit to effect closure of the shunt circuit reducing :the resistance, said last named means permitting repulsionof the unblocked secondary and being responsive to combustion conditions to maintain the shunt circuit closed while combustion continues.

- '7. Fuel burner control apparatus comprising a repulsion type relay, connections for closing a burner circuit upon actuation of the'relay, an initiating "circuit including the relay secondary, resistances of such value as to prevent passage of repulsion current through said secondary and an lectro-magnet; a low resistance shunt relay operating circuit including the relay secondary, mechanical means for blocking repulsion of the secondary, said means being movable to unblocking position by attraction of said electromagnet upon energizaticn of the initiating circuitgmeans responsive to the energization of'the initiating circuit to effect closure of the shunt circuit reducing the resistance and permitting repulsion of the unblocked secondary, and responsive to combustion conditions to maintain the shunt circuit closed 'while combustion continues and upon combustion failure to open the shunt circuit and restore the initiating circuit, and a latch for blocking further repulsion of the sec- 'ondary, said latch being rendered operative by attraction of said electromagnet upon restoring the initiating circuit following combustion failure.

8. Fuel burner control apparatus comprising a repulsion type relay, connections for closing a burner circuit upon actuation-of the relay, a pivoted carrier for the relay secondary, a burner circuit switch operable by movement of the carrier, an electromagnet adjacent the secondary, a relay release lever pivoted adjacent the relay secondary, said release lever having a magnetic member in operative relationship with the elec-- tromagnet and having a portion normally blocking movement of the relay secondary, attraction by the electromagnet serving to move the block .ing portion to unblocking position to permit operation of the relay to close the burner circuit switch, and a pivoted release levericatch adapted to engage and hold the release lever when said lever is moved to unblocking position, said catch being movable to become disengaged from said release lever upon repulsion of the relay secondary.

9. Fuel burner control apparatus comprising a repulsion type relay, connections for closing a burner circuit upon actuation of the relay, a pivoted carrier for the relay secondary, a burner circuit switch operable by movement of the carrier, an electromagnet adjacent the secondary, a relay release lever pivoted adjacent the relay secondary, said release lever having a magnetic member in operative relationship with the electromagnet and having a portion normally blocking movement of the relay secondary, attraction by the electromagnet serving to move the blocking portion to unblocking position to permit operation of the relay to close the burner circuit switch, safety latch mechanism carried by the pivoted carrier, said mechanism including a magnetic member moved to operative relationship with the electromagnet upon operation of the relay to close the switch, said safety latch being put in operation by the electromagnet and the subsequent actuation of the relay to inoperative position to block therieafter :furth'er operationtot the relay to close the switch.

10. Fuel burner control apparatus comprising a repulsion type relay having a fixed *coil :and a movable coil, connections for closing a burner circuit upon repulsion of the movable coil, an initiating circuit including the movable coil, =resist'a'nces of such value as to prevent passage or the repulsion current through the movable coil "and an electromagnet; a low resistance shunt operating circuit including the movable coil, mechanical means for blocking repulsion *of the movable coil, said means being movable to =un= blocking position by attraction of said electromagnet upon energization of the initiating cir cuit, means responsive to the energization of the initiating circuit to effect closure of the shunt circuit reducing the resistance and permitting repulsion of the unblocked movable coil, and responsive to combustion conditions to maintain the shunt circuit closed while combustion continues and upon combustion failure to open the shunt circuit and restore the initiating circuit, and means responsive upon restoring the initiating circuit and subsequent movement of the movable coil to open the burner circuit to prevent further'closure of the burner circuit.

11. Fuel burner control apparatus comprising a repulsion type relay having a fixed coil anda movable coil, an initiating circuit including the movable coil, resistances of such value as to .prevent passage of repulsion current through the movable coil and an electromagnet; a low resistance shunt operating circuit including the movable coil, mechanical means for blocking repulsion of the movable coil, said means being movable to unblocking position by attraction of said electromagnet upon energization of the initiating circuit, means responsive to the energize,- tion of the initiating circuit to efiect closure of the shunt circuit reducing the resistance and permitting repulsion of the unblocked movable coil, and responsive to combustion conditions to maintain the shunt circuit closed while combustion continues and upon combustion failure to open the shunt circuit and restore the initiating circuit, connections for closing a burnercircuit upon repulsion of the movable 0011, a normally closed switch controlling the burner circuit, and means responsive upon restoring the initiating circuit and subsequent movement of the movable coil to open the burner circuit to open the nor;- mally closed switch.

12. Fuel burner control apparatus comprising a relay having actuating means for closing connections to a burner circuit, means for energizing said relay to operate said actuating means, an initiating circuit including said relay energizing means, resistance of such value as to prevent passage of sufficient current to operate the relay and an electromagnet; a low resistance shunt relay operating circuit, mechanical means for blocking the actuating means, said means being movable to unblocking position by attraction of said electromagnet upon energization of the initiating circuit, means responsive to the energization of the initiating circuit to effect closure of the shunt circuit reducing the resistance and permitting operation of the unblocked relay and responsive to combustion to maintain the shunt circuit closed while combustion continues and upon combustion failure to open the shunt circuit and restore the initiating circuit, and means responsive upon restoring the initiating circuit and subsequent operation of the relay to open the burner circuit to prevent further closure or the burner circuit.

13. Fuel burner control apparatus comprising a relay having actuating means for closing connections to a burner circuit upon actuation of the relay, mechanical means normally blocking operation of the relay actuating means to prevent closure of the burner connections, electrical means for moving the mechanical means to unblocking position, an initiating circuit including the relay actuating means, resistance of such value as to prevent passage of suflicient current to operate the relay actuating means, and the electrical means for moving the mechanical means to unblocking position, the initiating circuit when energized operating the said electrical means and moving the mechanical means to unblocking position, a low resistance shunt relay operating circuit including the relay actuating means, means responsive to energization of the initiating circuit to effect a closure of the shunt circuit and operation of the relay actuating means and responsive to combustion conditions to maintain the shunt circuit closed while combustion continues.

14. Fuel burner control apparatus comprising a relay having actuating means for closing connections to a burner circuit upon actuation of the relay, mechanical means normally blocking operation of the relay actuating means to prevent closure of th burner connections, electrical means for moving the mechanical means to unblocking position, an initiating circuit including the relay actuating means, resistance of such value as to prevent passage of sufiicient current to operate the relay actuating means, and the electrical means for moving the mechanical means to unblocking position, the initiating circuit when energized operating the said electrical means and moving the mechanical means to unblocking position, a low resistance shunt relay operating circuit including the relay actuating means, means responsive to energization of the initiating circuit to effect a closure of the shunt circuit and operation of the relay actuating means, and responsive to combustion conditions to maintain the shunt circuit closed while combustion continues, said last named means including a switch for closing the relay operating circuit, said switch being heat responsive and being in heating relationship to resistance in the initiating circuit whereby the relay operating circuit is closed a. predetermined time after the initiating circuit is closed.

15. Fuel burner control apparatus comprising a relay having actuating means for closing connections to a burner circuit upon actuation of the relay, mechanical means normally blocking operation of the relay actuating means to prevent closure of the burner connections, electrical means for moving the mechanical mean to unblocking position, an initiating circuit including the relay actuating means, resistance of such value as to prevent passage of sufllcient current to operate the relay actuating means, and the electrical means for moving the mechanical means to unblocking position, the initiating cir cuit when energized operating th said electrical means and moving the mechanical means to unblocking position, a low resistance shunt relay operating circuit including the relay actuating means, means responsiv to energization of the initiating circuit to effect a closure of the shunt circuit and operation of the relay actuating means, and responsive to combustion conditions to maintain the shunt circuit closed while combustion continues, said last named mean includ- 1 ing a switch for closing the relay operating circuit, said switch being heat responsive and being in heating relationship to resistance in the initiating circuit whereby the relay operating circuit is closed a predetermined time after the initiating circuit is closed, and a latch for blocking further operation of th relay actuating means, said latch being rendered operative by the electrical mean for moving the mechanical blocking means upon restoring the initiating circuit upon combustion failure.

IRA E. McCABE,

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,594,020 Smith July 27, 1926 1,674,051 McCabe June 19, 1928 1,881,321 McCabe Oct. 4, 1932 2,057,383 Kroger Oct. 13, 1936 2,068,425 McCabe Jan. 19, 1937 2,102,618 Francis Dec. 21, 1937 2,159,658 Hall May 23, 1939 2,171,860 McCabe Sept. 5,1939 2,550,507 Wellman Apr. 24, 1951