US2064181A - Electric control apparatus for fuel burners - Google Patents

Description

an 6K '7 'A. L. W551; 2,064,181

Kg ha/M than Dec. 15, 1936 Abraham, Lincoln Rube], Des Moines, Iowa,

signor to Penn Electric Switch 00., Des Moines, I .Iowa, a corporation of Iowa Application August 15, 1932, Serial Nmszassa An object of my invention'is "to provide control apparatus for the electric circuit of afuel burner, the apparatus'being comparatively "simple and inexpensive to manufacture.

A further object is tofprovide control apparatus including'a warp switch which is energized when combustion occurs in order to break the circuit through a'heater of a safety switch, so that upon combustion] occurring; the safety switch will not thereafter trip out.' r

' Still a further object'is to provide means whereby the safety switchcanfbe. used to tripout for the purpose of providing a lock out type control in which combustionfailure itself has the effect ofshutting down the automatic operation of the device.

Stillafurther objectis to rearrange the circuits and contacts slightly so that after combustion failure, a purging period is provided and thenthe control apparatus is re-cycled for automatic operation. r, v

Still a furtherobject is to provide control apparatus including a relay which initiates and terminates operation of a fuel burner and which initiates operation of ignition mechanism for the fuel burner, termination of the operationofthe ignition mechanismbeing effected by combustion occurring.

Still a further object is-to providea control apparatusin which a safety switchfiheater, a warp switch and a relay are all -in.circuit with each other, acombustion responsive switch being effective to'open the safety switch heater circuit and-energizev a warp switch heater which warps the switch to a position where it shunts the relay out of the'circuitso that upon combustion failure, current will ,flowthrough the safety switch heater, but not through the relay,

with the effect of quickly heating the safety switch rheaten-totrip it and thus lock the apparatusin non-operating position. .1-

- Stilla further objectis to provide another apparatus in which the relay is not shunted out,

but the warp switch, upon combustion failure. is

allowed tdreturn to initial position for recycling the apparatuasuch return being slow so as'to provide a purging period.

Boththe lock out type andthe purgingperiod type of apparatus are used on a fuel burner so that upon combustion failure occurring, such as caused by a down draft in the-furnace, a slug of-waterin the fuel oil or the like, automatic operation of the apparatus willeither' stop until the cause has been remedied and the apparatus ---indicated as I, 2,

. son-inns. (01. 158-28 & cycle after a purging period has been provided to allow the draft of the furnace to purge the combustion chamber of any explosive gas caused bythe introduction of fuel after combustion fails.

With these and other objects in view my invention consists in the construction, arrangement and'combination of the various parts a: my de vice, whereby the objects contemplated are attained, as hereinafter more fully set forth, point- '10 ed out in my claims, and illustrated in the'ac- .companyingdrawing, in'which:

Figure -1 is an electrical diagrammatic view showing mylock out type of control apparatus;

reset,;or-it will re- .ing period'type of apparatus. D

On the accompanying drawing, I have 'used the reference numeral It to indicate a' line switch. A limit switch is shown at l2 which maybe tem- 20 -perature or steam pressure operated and which is'ordinarily used in control circuits on furnaces 'an'dboilers to prevent the furnace or boiler being heated to an excessivedegree. Junction boxes 15 1 Figure 2 is a' similar figure showing the purg- -'are shown at I 4 and I6." 'I'hese'form no essential 25 part of my present invention, but are merely provided on the. actual switch for [the convenience of the electrician when installingand wiring the apparatus. The

junction box l6 v v r 3 and L I do My apparatus further includes a room thermostat l 8, aicombustionresponsive'control switch 20, n ignition switch 22 also responsive to combushas 4 terminals tion; a safety switch 24, a warp switch 26 and a relay'28. At 30 a furnaceis shown and the burnertherefor is shown more or less diagrammatic at '32. An ignition transformer is shown at 34, and a spark gap at 36. This comprises the ignition mechanism mentioned in my claims.

In Figure 1, the control switch'2ll has contacts 40 38, t0 and", The ignition switch 22 has contacts '44 and 4 6. The safety switch 2lhas contacts 48 and 50, "The-safety switch includes a heater 52 and a bimetal latch, which, when warped to the dotted line position by. heat from the heater 52, 45 Q'will permit disengagement ofthe contacts '48 and "50. The warp switch 26 includes contacts, 58 and 60. The warp switch further includes a bimetai actuator 62 for the contact 56 anda warp switchheater 64." Y a 50 In. Figure 2, the control switch 20 has contacts '38, 4| and '42. The ignition switch has contacts and l6 3 elsafety switch and the warp switch 26 are the same as in Figure lexcept there ism contact 58. P '55 -the heater II.

J2 so that itwill v Y which wouldoccurafter a period of time if com- The relay 28 has burner control contacts 06 and 68 and holding contacts 10 and. l2.

The control and ignition switches Ill and I! in both figures are normally in the solid line positions; Upon combustion occurrin8, bimetal helixes 2| cause movement of the contacts 38 and 4G to their dotted line positions. Thecombustion responsive switches 2. and 22 are of the ordinary type commonly termed a stack switch having a slip connection to cause immediate movement of the movable contacts from one position to another and thereafter permitting slippage. The warp switches 28, when heated by energization of the heater 64, warp to the dotted line positions.

In conjunction with my apparatus, I provide a transformer 14 having a -primarywinding "and a secondary low voltage winding ll, so that the relay and the mechanism for controlling it therefore need not be constructed for high voltage current.

Operation of lock out control apparatus Referring to-Figure 1, the room thermostat I! I is in open position.

, I when it calls for heat, the current may be traced from the secondary winding 18, through the room thermostat is, through the closed contacts 3! and 40, throughthe safety switch heater 5!, through the warp switch 26 and its contacts 5 and it and through part of the relay 28 and return. This energizes the relay so that its armature 280. is attractedito'the dotted line position, whereupon highvoltage current from the left side of the line switch It, through the limit switch II, the safety switch 24 and the contacts 68 and 68 flows to the burner 32 and return. Also, the high voltage current flows from the contact II, through the ignition contacts 44 and "to the ignition transformer and return. This causes'a high tension spark at the spark gap 36. Energization of the relay 28 also, closes the contacts "l0 and I! so that currentfrom the room thermostat II is supplied through the entire coil of the relay 2. and return. Thus the. relay is held in closed position after once being energized.

Upon combustion occurring, the contacts 38 and 4| of the control switch 2|! are separated for opening the circuit through the safety switch heater not open the safety switch 24,

bustion did not separate the contacts. the firstcircuit through the relay 28, but the holding contacts It and I! retain the relay in energized position. Combustion occurringalso separates the ignition contacts 44. and to terminate operation of the ignition mechanism. Combustion occurring also closes the contacts 38 and 42 of the control switch 20 which energizes the warp switch heater 64. This will cause the switch 2' to warpto the dotted line position, engaging contact 56 with contact 54.

Subsequently, upon combustion failure, the contact "will re-engage thecontact 4| for'energlzing the safetyswitch heater I2 without passing the current through the relay coil It because the contacts "-40. are closed amaterial time period before the warp element 62 has cooled suihciently to open the contacts 4 and in the circuitof This results in a much quicker heating of the heater is m immediately nlhg the safety switch 24 contacts due to the fact that there is less resistance in series with the heater. The

apparatus is now locked out inasmuch-as it cannot here-cycled except after-the safety switch 24 has beenmanually reset.

' tion establishment also .64. Thereafter the heater warp switch. 26. It will eliminated.

This opens In Figure 2, closing of'the contacts in the room thermostat II will establish a circuit through the safety switch heater 52, the warp switch It and its contacts 50 and 80, the. relay 28 and return. This initiates operation of the burner and of the ignition mechanism, termination of the ignition mechanism being tacts 44 and 48, the same as in Figure 1.

Upon combustion establishment, the contact ll engages thecontact 4| for establishing the holding circuit through the contacts 10 and 12 which have been engagedby energization of the relay 2!; but not rendered eflective becauseof the normal full line positionsof thecontacts I8 and 4 I. Combuscloses the circuit through contacts 38 and 42 for energizing the warp switch heater 64 and causing the warp switch 26, to warp to its dotted line position. This'opens the circuit through the safety switch heater 52.

Upon combustion failure, the contact 38 separates from the contacts 4| and 42, thus de-energizing the holding circuit through the contacts "and 12 for terminating operation of the bumer I: and de-energizing the warp switch heater V 64 will gradually cool down and so will the bimetal element 62 of the finally cause engageand 00 which re-estabthe upper portion of the ment of the contacts 56 lishes a circuit through relay coil tore-cycle the apparatus by re-initiating operation of the burner". The period of time during which the bimetalelement 62 moves from the dottedline to the full line position provides a period during which the furnace is purged of gases which might explode whenthe contacts 66 and 6B are re-engaged tore-establish ignition as well as re-initiate operation of the burner. g

'In either form of my apparatus, I provide a warp switch for opening the safety switch heater circuit and for controlling the circuit so that either a lock out (in Figure 1) or a purging period operation results (in Figure 2). Although I have shown the transformer 14, it will be obvious that the entire apparatus maybe operated by high voltage current Some changes may be made in. the construc-. tion and arrangementof the parts of my device without departing from the real spirit and purpose of my inventiomandit is my intention to cover by my claims, any modified forms of struc ture or use or mechanical equivalentawhich may be reasonably included. within their scope.

-I claim as 'my invention: 2. 1. In combination with an electrically operated ;fuel burner,-a control system comprising a.

' relay operable when energized to close the burner circuit to initiate operation, 'a room thermostat controlling energization of said relay, 9. thermal time limit cutout switch including a resistance heater controlling said system, a switch having a warpelement, a heater, first contacts which, are closed when .said element is cold and 'contacts'whichare closed when said element is and the transformer heated, combustion responsive switching means 1 having contacts closed in the. absence of combustion and other contacts closed inthe presence of combustion, a circuit including the room ther-,

mostat', the contacts of the combustion ,responsive switching means closed. in the absence ofcombustio ,the cutout switchheater, said first contacts and said relay, a second circuit-including the heater for said warp element and the contacts of the combustion responsive switching means closed in the presence of combustion and a third circuit including the heater of said cutout switch and said second contacts, said warp element moving slowly when cooling whereby upon combustion failure, said cutout switch is quickly actuated to shut down the system.

2. In combination with an electrically oper ated fuel burner, a control system comprising-a relay operable when energized to close the burner circuit to initiate operation, a room thermostat controlling energization of said relay, a thermal time limit cutout switch including a heater controlling said system, a switch having a warp element, a heater, first contacts which are closed when said element is cold and second contacts which are closed when said element is heated, combustion response switching means having contacts closed in the absence of combustion and other contacts closed'in the presence of combustion, a circuit inluding the room thermostat, the contacts of the combustion responsive switching means closed-in the absence of combustion, the cutout switch heater, said first contacts and said relay, said relay having holding contacts to maintain the relay energized when said contacts of the combustion responsive switching means closed in the absence of combustion areopened by'the presence of combustion, a second circuit including the heater for said warp element and the contacts of the combustion responsive switching means closed in the presence of combustion and athird circuit including the heater of said cutout switch and said second contacts, said warp element moving upon combustion failure, said cutout switch is quickly actuated to shut down the system.

3. In a system having electrically controlled fuel feeding and ignition means, a main control switch, an electrically actuated time limit cutout switch operable to open in time periods varying in accordance with its rate of energization, switching mechanism including reactances and a combustion controlled switch, and circuit connections including the foregoing elements controlling energization of the fuel feeding and ignition means and the energization of the time switch and rate thereof and operable upon a demand for heatand closure of the main switch to: (1) energize the fuel feeding and ignition means and energize the timeswitch at a predeslowly when cooling whereby terminedrate; (2) 'deenergize the ignitionmeans and time switch upon the establishment of combustion; higher the fuel feeding during normal op'eratim. 4. In combination with its fuel feeding means, a control system includand (3) reenergize the time switch at a rate while maintaining energization of means upon a failure of flame a fluid fuel burner and ing in circuit a main control member, an electril cal safety time switch whose timing interval varies with the rate at clusion of the timing interval, a combustion responsive device, and meansresponsive to the main control member for simultaneously initiating operation of said burner and energizing said time switch at a first rate, and cooperating with the combustion responsive device to deenergize said time switch upon the successful establishment of combustion, and to ree'nergize said time switch ata second rate higher than said'flrst rate upongthe occurrence ofsubsequent flame failure, whereby said time switch provides a longer, timing interval upon initiation of operation of the burner than is provided upon the occurrence of flame failure.

5. In a system having electrically controlled fuel feeding and ignition means, a main control switch, an electrically actuated time limit cutout switch operable to open in a time period varying in accordance with the rate of current flow therethrough, a plurality of switches, switching. mechanism for actuating reactances and a combustion responsive thermostat, and circuit connections including the 10 I which it is energized for 4 discontinuing fuel feed to the burner at thereonsaid switches including? foregoing elements controlling energization of and feeding and ignition,

rate; (2) de -enure duringnormal operation to re-e'nergize said, I

time'switch at a relatively high'rate while maintaining energization of the fuel feeding means whereby said time switch will quickly. open to render the system inoperative.

ABRAHAM Lmcom RUBEL. r

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