Патент USA US2403412код для вставки
July 2, 1946 c. K. sT|§oBEL EI‘AL ' ' 2,403,412‘ IGNITION AND SAFETY CONTROL SYSTEM FOR FUEL BURNERS Filed Aug. 8, 1945 . | " ' _. %7r20<18"1a 1J9” !’ -|| 15 : ‘Ln v ' ' - - I ' IN VEN TOR! > ClzaplemhiS?o?el ana'Samael 4.5412512 . _ . 7 ' Patented July 2, 1946, 2,403,412 ' ITED STATES PATENT-OFFICE 2,403,412 IGNITION AND SAFETY CONTROL SYSTEM ‘ ._ FOR FUEL BURNERS Charles K. Strobel, Pittsburgh, Pa., and Samuel G. Eskin, Los Angeles, Calif., assignors to Robertshaw Thermostat Company, Youngwood, Pa, a corporation of Pennsylvania Application August 8,- 1945, Serial No. 609,626 6 Claims. (Cl. 158-4171) . 1 i . ticularly, to; electrically therefor. ' operated ' - may form part of a. thermostatic fuel ‘control de vice of well-known form. The cock and switch- . systems ' _2 main fuel cock and switching ‘means “which This invention relates to ignition and safety control systems for fuel burners and, more'par-v _ Systems of the type indicated may be arranged so that an electromagnetic safety valve may be opened when a main switch is closed and the fuel supply. turned on. The fuel is then ignited by an electric igniter controlled by the main switch and after the expiration of a starting 10 ing means It is arranged for manual operation by a handle l5 carrying temperature indicia- It. It will be apparent that the main fuel cock and switching means it could be arranged for sepa rate operation if desired and that the thermo static device could be dispensed with. ‘ Interposed in the fuel supply pipe it between the main fuel cock l4 and the burner it is an period the .igniter is disconnected by operation electromagnetic fuel valve_l6 of any known type which may be arranged, as in this instance, to be opened when current of su?lcient energizing supply thereto according to variations in the re- . sistance of a thermal resistor exposed to the 15 value is supplied to the solenoid ill thereof and closed by gravity, spring. or other means upon a heat of the burning fuel. reduction of the current value thereto below Where an electromagnetic relay is employed holding value. A pilot burner it is provided for I in conjunction with the timing device it is ap of a timing device. The valve then either re mains open or is closed by varying the current igniting the main burner, ill and is supplied with parent that power consumption and operating noise would be'reduced if the power consuming 20 fuel from a conduit 28 connected to the main fuel pipe it between the main burner it and the element of the relay were disconnected after the electrometlc valve it. .It will be observed, starting period. It is, therefore, an object of therefore that the electromagnetic valve 86 con this invention to render the system substantially trols the flow of fuel to both the main burner til ‘ noiseless during the running period. Another object of the invention is to effect a 25. and the pilot burner 58. It will be apparent, however, that where the pilot burner it is not saving in, power consumption in the operation of desired it could be. dispensed with without a?ect safety and ignition systems. ing the operation of the system in its essential Another object of the invention is to insure ‘ reliable operation of the ‘system in performing . aspects. The fuel issuing from the pilot burner ‘it is its functions during the starting and. running adapted to he ignited by an electric resistance periods when normally operated. ignite: The heat of the ?ame of the burning Another object of the invention is to render the system suf?ciently ?exible as to length of the‘ starting period to provide a wide range of operation. " " ' Another object of the invention is to ‘place the ' .fnei 35 resistance eieinent 255 is preferably in the form of soil wire of material having normally a timing device in condition for another starting ' period immediately upon inception of the prior running period. ' ' other objects and advantages will become ap- ‘ parent from the following description taken in connection with the accompanying drawing, wherein: ~ _ ' ‘ Fig. 1 is a schematic view of part of'a safety control apparatus‘ for a gaseous fuei tanner embodying this invention; 2 is a circuit diagram showing the elec trical connections: and ' _ adapted to cause variation in resistance of a thermos resistance element 2%. The thermal W reiatively low resistance and a positive tempera ture eoefdcient of resistance and is adapted to increase appreciably in resistance when heated by the Same. While this resistance element 2!; is also heated by passage of current therethrough and other types of ballast resistors or ?ame sensi tive elements could he substituted, it wili he tin derstocd to he primarily responsive to the heat of the The igniter 22 and thermal resist ance element both located in proximity to the piiot banner where this burner is dis -e’nsed these elements wonid be positioned in proximity to the main turner id. ‘ Figs. 3 and e are detailed views of the main switching means in di?erent positions of 50 a. second thermai resistance era-sent at is m- ' cluded in the eiretnt and is also formed from a operation. . '’ coil oi‘ wire . sting normally a relatively'low Referring more particularly to the drawing, a resistance e m “emperatlire cce?cient gaseous fuel burner la is shown in Fig. l as be ing supplied with fuel by a main fuel pipe E2. The fuel supply is under control of aicombmed 55 esistance element it a the demo of any 2,403,412 4 3 burner and is adapted to vary its resistance only due to the passage of current therethrough. As will be apparent hereinafter, the thermal re sistance characteristics of the element 26 could - be dispensed with and a ?xed or constant re be traced as follows: From a source of electrical 7 energy by line wires 54, primary of transformer 56, wire 58 connected to one terminal of the sec ondary of transformer 56, movable switch arm 50, sistor employed if desired. A cut-out 28 is provided for opening the circuit of the solenoid ill in the event of an open circuit occurring in the thermal resistance element 24. The cut-out 28 is preferably of the thermal type 10 having time-lag operation. Such devices are con structed with predetermined time current char-. acterlstics and usually contain a heater element in addition to and affecting a fusible member which opens the circuit by passage of overcur 15 rent.‘ A control relay, designated generally by the reference numeral 30, is provided for establish ing desired circuit conditions during the starting and running periods of the burner. The control 20 relay 36 is preferably of the electromagnetic type having a winding 32 and a pivotally mounted armature '34 which is rendered responsive vto en ergization of the winding 32 by means of a core terminal 52, wire 60, winding 32, wire 62 and wire 64 to the other terminal of the secondary of transformer 56. The winding 32 being now energized from the source of current supply, the armature 34 will be operated to close the contact pairs 38, 40, pro vided that the contacts are not already closed, as will'be hereinafter explained. As the heater coil 55 is notenergized at this time the bimetal ele ment 45 is cold and occupies the full line posi tion shown in Fig. 2 of the drawing. In this po sition the bias of the spring 44 is overcome and the arm 42 is enabled to latch the armature in its contact, closed position. The normal rotation of the handle l5 of the main fuel cock l4 from “off” to “on” position will next cause disengagement of the switch arm 50 from the terminal 52 and positioning of the parts in full “on” position as shown in Fig. 4. It is apparent that the circuit for the winding 36 to which the armature is hinged at one end. ' 25 32 is opened but the contact pairs 38 and 40 A plurality of pairs of switch contacts, in this remain engaged due to the latching arrange ment. In this full “on” position the fuel cock I4 is fully opened and the fuel may flow in the main fuel pipe [2 at least as far as the electro the arrangement shown both contact pairs 38 and 46 are closed and opened substantially si 30 magnetic valve IB which is normally closed. The instance two, 36 and 4|], are adapted to be opened 5 and closed by operation of the armature 34. In multaneously by appropriate movements of the I arcuate switch arm 66 is now engaged with the terminal 68 of the main switching means of fuel armature, 34. ‘ cock l4 and establishes a starting circuit for the 'Means are provided for latching the armature safety control and ignition apparatus. 34 in the closed position for a predetermined This starting circuit is in the form of an elec period during which the winding 32 may be de 35 trical bridge and may be traced from the source, energized. The latching means comprises a piv line wires 54, primary and secondary of trans oted arm 42 adapted to engage and latch the former 56, wire 58, switch arm 66, terminal 68, armature 34 but being normally biased to free and wire 10 to junction 12 of the bridge. The position by a spring 44. A thermal timer of any first arm of the bridge may be traced from junc known type comprising a bimetal element 46 and heater coil 48 therefor is adapted to overcome tion 12, wire ‘I4, contact pairs 38 and 40, wire ‘I6, igniter 22 and wire 18 to junction 86 of the bridge. the bias of the spring 44 to enable the arm 42 to move into latching engagement with the arma ture 34 when the bimetal element 46 is cold as The second arm of the bridge may be traced from junction 80, wire 82, solenoid coil H and wire 84 connected to junction 86 of the bridge. The third arm of the bridge may be traced from shown in Fig. 2. The thermal timer preferably includes the so-called instantaneous reset device (not shown) generally consisting of a cold con junction 86, wire 88, thermal‘ resistance element ducting surface for the bimetal element 4-8 which 24 and wire 90 connected to junction 32 of causes return of the latter to its cold position the bridge. The fourth arm of the bridge may after warping therefrom. be traced from junction 92, wire 94, second ther The switching means of the main fuel cock l4 mal resistance element 26 and wire 96 connected includes two movable switch arms 50 and 66 and to junction 12. two spaced terminals 52 and 68. The movable The cut-out 28 is connected as the detector arm switch arm 50 is adapted for operative engage in the bridge circuit by a wire 3!! connecting one ment with terminal 52 when the handle I5 is terminal thereof to junction 92, the opposite ter rotated to an intermediate position between “off” minal of the cut-out 28 being connected directly and “on” (Fig, 3). The switch arm 66 is of to the junction 80. The circuit for the bridge arcuate form and is adapted to maintain opera is completed by a wire Hi6 connected [at one end tive engagement with terminal 58 from the “on” to the junction 86 and at the opposite end to 60 position (Fig. 4) throughout a range of move wire 64 which is connected to the secondary of ment of the handle 55 so that various tempera the transformer 56. If the cut-out 28 is consid ‘ ture settings may be selected at which the ther ered of negligible impedance it is apparent that mostat will operate. The arcuate switch arm 66 does not, however, engage the terminal 52 at any 65 the bridge circuit is, in eiiect, two parallel meshes connected in series with the secondary of the transformer 58. The impedance of this circuit is The operation of the system is as follows: The relatively low and sumcient current ?ows to the main fuel cock i4 is shown in Fig. 2 in the “off” solenoid ll of the electromagnetic valve it to position and no fuel is being supplied to the main time. . " open this valve regardless of whether or not the burner it) or the pilot burner It. When the main fuel cook it is turned toward the “on” posia 70 .thermal resistance element 24 is heated by the burning fuel. Moreover, it will be apparent that tion engagement occurs in an intermediate “on” ' the cut-out 23 which is connected in the detector position between the movable switch arm 56 and arm of the bridge circuit receives current which -‘ the terminal 52 of the switching means as shown is maintained below its steady state operating in Fig. 3. A‘ circuit is then established for the value at all times during the starting period due winding 32 of the control relay 3!! which may ~ 2,403,412 ‘ to the various arms of the bridge being in sub stantial balance. , As the foregoing described bridge circuit causes energization of the igniter 22, the fuel which is "01?’ position will cause the movable switch arm 50 to become engaged with terminal 52. The winding 32 of the control relay is thereupon energized and the contact pairs 38', 40 will be admitted to both the main burner l0 and the pilot - closed. burner is is vignited substantially simultaneously with the opening of the electromagnetic valve It. As the bimetal element 46 preferably is ar ranged to engage a cold conducting surface as The heat of the burning fuelwill cause the thermal _ described, when in the broken line position, it will return quickly to its initial position, shown resistance element 24 to become eil’ectively heated after a predetermined period which may be a few seconds. ' ‘ in full lines, causing the arm 42 to be moved tov latching position as soon as the contact pairs 28 and 40 are opened. Thus, when the “off” posi tion shown in Fig. 2 of the drawing is ?nally reached and the winding 22 is again deenergized, ' During this starting period, the heater coil 48 . 'of thethermal timer is also energized through a vcircuit which may be traced from the source, line wires l4, primary and secondary of transformer 15 the contact pairs 38 and 40 may be held in closed 56, wire 58, switch arm 88, terminal 68, wire 10, position by the latching means due to the opera wire 14. contact pair 28, wire I02, heater coil 48, tion of the thermal timer described. v wire I04, wire 82 and wire 84 to the secondary of The winding 32 forming the electromagnetic ' component of the control relay is thus energized the transformer 58. The bimetal element 46 becomes heated by the heater coil 48 ‘and warps '20 momentarily and then deenergiaed by the normal to the broken line position shown in Fig. 2 of the drawing. ‘ operation of the main fuel cock“ during the start Thus, the I‘ bimetal element 46 is ing operation. Thus, the circuit timing function rendered incapable of overcoming the. bias of- the ‘ is performed while the power consuming element spring 44 and the arm 42 istripped to cause open is disconnected. The usual source of noise is thus ing of the contact pairs 38 and 40. The thermal 25 not present during normal running of the burner timer may conveniently operate after an eighteen and the current consumption is correspondingly second starting period which is sufficient to allow the thermal resistance element 24 to become heated bythe burning fuel. This period maybe reduced. . ' " It will be understood that various changes can be made in the arrangement and combination of varied as desired by adjustment of the timer as 30 parts and in the form of the elements herein dis will be apparent. 4 closed within the scope ofv the appended claims without departing from the spirit of the inven~ ' This operation of the contact pairs Stand 40 terminates the starting period and marks the tion. inception of the normal running period of the We claim: - . ' " burner. The operation of contact pair 40 serves 35 1. An ignition and safety control system for fuel to open the ?rst [arm of the bridge circuit and . burners having a source of electrical energy, com deenergize the igniter 22. _ The bridge circuit is now converted to a circuit including the thermal resistor 24 in parallel with the solenoid i1 and cut-out 28 all in series with thermal resistor 26. The total circuit impedance'is thus increased and causes a'reduction in the value of the current through the solenoid H. The current value is not reduced below that required‘ to hold the electro magnetic valve is in open position if the thermal is El resistance-element 24 has now become 'su?lciently prising electrically operable fuel controlling means movable between fuel. flow permitting and pre venting. positions, switching means for control ling energization of said fuel controlling means from the source and operative to cause said move-V ment thereof, means responsive we condition caused by combustion of the fuel and electrically connected to said fuel controlling means for re ducing the energy value supplied thereto su?i ciently to cause movement thereof to flow pre heated by the burning fuel and has increased venting position in the absence of combustion, an in resistance.. However, if at the end of the start electric resistance igniter for the. fuel, control " ing. period or at anytime during operation of the means responsive to operation of said switching system the ?ame of the pilot burner it should 50 means for rendering said condition responsive cease. then the "resistance of the thermal re means ineifective to cause said movement for a sistance element 24 will be reduced by cooling predetermined period during which said condi thereof and the current to the coil II will be ‘ tion responsive means has time to become respon rendered insumcient to maintain the electromag-, siVe. said control means comprising a winding netic valve iBin open position. Flow of fuel to and switch contacts adapted to be closed for es 'both burners will then cease. This action is tablishing a circuit from the source including accelerated by making the resistance element 28 said fuel controlling means, said igniter and said , ‘of the thermally responsive type. ’ _ condition responsive means of su?lcient enersiz- ‘ It will be apparent that if the thermostatic con trol deyice previously mentioned is included as part/of the main fuel cock and switching means N that the fuel supply to the main burner may be 60 ing value to cause said movement to vfuel ?ow permitting position, said winding being connected ina separate circuit with the source and adapted to be deenergized by operation‘ of said switching turned off and on thereby while the arcuate switch arm 86 which is in operative'engagement means to cause opening of'said switch contacts ditions at the temperature setting inwhich the handle I! is positioned. When the operation of the main burner i0 is no longer desired. then the handle ii of the main fuel cock 64 may be rotated not exist. 2. An ignition and safety control system for fuel burners having a source of electrical energy, todisconnect said igniter and render said condi ‘with the terminal 88 maintains closed circuit con- _ 65 tion responsive means effective if combustion does ’ v in reverse direction from "on" to, "01!” position. 70 Such operation will serve to disengage the arcu ate switch arm 68 from terminal 88 and cause deenergization of the coil ll of the electromag netic valve i8 whereupon the valve willclose. Further reverse rotation- of the handle it toward I comprising‘electrically‘ operable fuel controlling means movable between fuel ?ow permitting and preventing positions, switching meansv for con trolling energization of said fuel controlling means from the source and having a plurality of oper ative positionsjmeans responsive to a conditionv 75 caused by combustion of the fuel and electrically 2,403,412 7 . connected to said fuel controlling means for re' , ment effective if‘ the pilot burner does not pro ducing the energy value supplied thereto sum ciently to cause movement thereof to flow pre venting position in the absence of combustion, an electric resistance iguiter for the fuel, control duce a flame. _fuel burners energizalole from a source oi’ current means e?ective in one said position of said switch ing means for rendering said condition respon bridge circuit, an electrically operable fuel con sive means ineffective to cause said movement trol device in a second arm of said bridge and operable to supply fuel when current of sumcient 4. An ignition, and safety control system for supply and comprising an electric igniter for the fuel connected in a ?rst arm.‘ of an electrical for a predetermined period during which said condition responsive means has time to become responsive, said control means comprising a value is supplied‘ thereto, a pair of resistors in third and fourth arms respectively of said bridge. winding and switch contacts adapted to be closed one of said resistors being exposed to the heat of the burning fuel for varying in resistance and for establishing a circuit from the source in causing variation in said current value, control cluding said fuel controlling means, said igniter and said condition responsive means or‘ su?icient 15 means for rendering said igniter inoperable and said current value ihsu?icient after a predetera energizing value to cause said movement to fuel ?ow permitting position, said winding being con ‘_ mined period unless said one resistor is heated, said, control means comprising switch contacts nected in a separate circuit with said source and operative for opening and closing said ?rst arm adapted to be deenergized in said one position of said switching means and energized in another 20 and a winding for operating said contacts, switching means for connecting the source across said position thereof, means responsive to clos opposite junctions of said bridge with said ?rst ing of said switch contacts for holding the same and second'arms and said third and fourth arm closed when said switching means is operated in series circuit resmctively and in multiple from said other position to said one positionv thereof, and means for rendering said holding 25 across said junctions, said winding being con nected in a separate circuit with the source and means inoperative upon expiration of said period adapted to be deenergized by operation of said to cause opening of said switch contacts to dis switching means to cause operation of said switch connect said lgriter and render said condition re contacts ‘for opening said iirst arm. sponsive means eilective if combustion does not exist. ' ' ~ 30 5. An, ignition and safety control system for 3.‘ An ignition and safety control system for fuel burners having main and pilot burners and a fuel burners energizalole from a source or current source of electrical energy. comprising electro fuel connected in a ?rst arm of an electrical supply and comprising an'electric igniter for the bridge circuit, an electrically operable fuel con magnetic valve meansimovable between- closed and open positions for controlling the fuel supply 35 trol device in a second arm of said bridge and operable to supply fuel when current of sumcient to the main burner, manually operable switch ing means [for controlling energization of said value is supplied thereto, a pair of resistors in the third and fourth arms respectively of said electromagnetic valve means and having a plu bridge, one of said resistors being exposed to'the rality of operative positions, a thermal resistance element having a preselected temperature co 40 heat of the burning iuel for varying in resistance and causing variation in said current value, con emcient of resistance located in proximity of, the ' pilot burner and electrically connected to said trol means for rendering said igniter inoperable and said current value insumcient after a pre electromagnetic valve means for reducing the en ergy value supplied thereto upon variations in the 45 determined period unless said one resistor is heated, said control means comprising switch resistance of ‘said element due to the absence of contacts operative for opening and closing said a ?ame at the pilot burner, an electric resistance first arm and a winding for operating said con igniter for the pilot burner; a control relay effecr tacts, switching means having a plurality of oper— tive in one position of said switching means for menderingxsaid thermal resistance element ineffective 50 ative positions in one of which the sourceis con to reduce said energy value su?iciently to cause nected across opposite Junctions of said bridge closing." of said electromagnetic valve means for with said ?rst and second arms and said third a predetermined period during which. said thermal resistance element has time to become heated, and fourth arms in series circuit respectively and in multiple across said junctions, said winding being connected in a separate circuit with the said control relay comprising a winding'and a plurality of switch contacts adapted to be closed i source in said one position of said switching source and adapted to be deenergized in said one position of said switching means and energized in another of said position thereoi’, means re means, said ?rst circuit including said electro magnetic valve means, said thermal resistance ele >ment and said i'gniter and causing ‘movement’ of when said switching means is operated from said - for establishing first and second circuits from the sponsive to operation of said switch contacts to close said ?rst arm‘for holding the same closed other position to said one position thereof, and means for. rendering-said holding means inoper 'tion, said winding being connected in a third ative upon expiration of said period to cause circuit with the source and adapted to be ener ' sized in another position of said switching means 65 operation of said switch contacts to open said and immediately deenergized upon operation 6. An‘ ignition and safety control system for thereof to said one position, means responsive fuel ‘burners energi'zable from a source of cur to closing of said switch contacts for holding the rent supply and comprising an electric igniter same closed when said switching means is- oper for thefuel connected in a ?rst arm of an elec ated to said one position thereof, and a thermal trical bridge circuit having arms arranged in ,t'imcrhavinga heater coil in saidsecond circuit 'a sequence, an electrically operable fuel control adaptedfor rendering said holding means inop erative upon expiration of- said period to cause. - _ device in a second arm of said bridge and oper able to supply fuel when current of sufficient opening of said switch contacts to disconnect said said electromagnetic valve means to open posiy ?rst isnlter and ‘ render said thermal resistance ele arm. . r - . value is supplied thereto‘: pair of resistors in 2,403,412 ' 10' position of said switching means and the third and fourth arms respectively of said bridge, one of said resistors being exposed to the heat oi the burning fuel for varying in resistance and causing variation in said current value, con energized ' I in another said position thereof, latching means tor said armature normally biased to free posi tion and adapted to hold said ?rst arm closed when said switching means is operated from said other position to said one position thereof, and I trol means for rendering said igniter inoperable , and said current value insu?icient after a prede a thermal timer adapted to overcome the bias termined period unless said one resistor is heated, of said latching means to enable the same to-hold said control means comprising a plurality 01' pairs said ?rst arm closed, said timer having a heater of switch contacts, a winding and an armature,_ one said contact pair being adapted for opening 10 coil controlled by another said contact pair and connected to the source when said switching and closing said ?rst arm, switching means hav means is in said one position for rendering said in: a plurality oi‘ operative positions in one of timer incapable of overcoming said bias upon which the source is connected to opposite junc _ tions' oi’?'said ?rst and fourth arms and said sec- - 0nd and third arms respectivel7,- said’ winding 15 being connected in a separate circuit with the source and adapted to 'be deenergized in said one expiration of said period. ; crmnms K. s'moBEL smear. a. serum.