Патент USA US2411642код для вставки
NOV. 26, c_ K_ STRQBEL ' 2,411,642 SAFETY CONTROL APPARATUS FOR FUEL BURNERS Filed March 23, 1945 £223 ‘ v /34 I > 76 , 46 52 l ‘16 ' 0 Cambizzea'i'ael " , Value a'adMaL'n Swz'e‘ob IN VENTOR. C’barlerki Szfr’abel. Elf/WM .HYS’ATTURNEK Patented Nov‘. 2c, 1946 _ I ‘ 2,411,642.” um'rso s res PATENT ’ rrlc ., ' ‘ 2,411,642 ssrs'rv’cou'mos * Business APPARATUSFOR , iL‘harles K. Stro‘bei, Pittsburgh, Pa., assignor to Robertshaw Thermostat Company, Youngwoou, Pa, a corporation of Pennsylvania ‘ Application March 23, 1945, Serial No. 584,218 5 Claims. (Cl. 158-1171) This invention relates to safety'control sys tems for fuel burners and,‘mcre particularly, to electrically operated controls'thereior. Safety control systems of the electrically oper~ Other objects and advantages will become ap parent from the following description taken in connection with the accompanying drawing, wherein is shown a. schematic view of a safety ated type may be arranged to include a starting control apparatus for a gaseous fuel burner em period during which the circuit conditions are bodying the invention. ' ‘ such that su?icieht current is supplied to the fuel Referring more particularly to'the drawing, a, controlling means to actuate it to a position in main fuel burner is is supplied with gaseous fuel which fuel is supplied to the burner. Thereafter, by a main fuel pipe The fuel supply in the the normal running period is initiated and the iii pipe ‘52 is controlled by a main valve is which, circuit conditions automatically reduce the cur in this instance, is adapted; for manual operation rent supplied to the iuel controlling means to but which may be'arrariged for thermostatic op holding value. The fuel controlling means does 'eration if desired. interposed in the fuel supply not move from the fuel supply position providing pipe ‘l 52 between the main valve ii.‘- and the burner the burner is producing a ?ame. However, sub is is an electromagnetic or solenoid gas valve ill‘ sequent extinguishiment of the burner will of any known type which may" be arranged,‘ as in result in a prompt response of the circuit elem this instance, to be opeuesi when current of sum ments to further reduce the current to cient energizing- value s cplied to the solenoid the fuel controlling means below the H and closed by gravity more. a reduction of the value. This causes the fuel contra 3' me to current value thereto below holding value. assume a position in which "' rely the A pilot burner it is provided for burner is prevented. main burner iii and is supplied wit a The means for cletei‘uii WEE t conduit under control 2s connected or the main to thevalve mai be controlling means remains i ting position may taise the‘ i“ haul-181:. re“ > understood, could be dispensed however,v/i'thatv sistance element locatecl' burner flame and arranged the essential principles of ihe eluded for the purpose of relation ‘I and at the main burner at" various elements of the system in their relative positions of 1186, Electric current for the o" controlling means is couuectec, ' presence or abse scribed and claimed my copeum ‘ Serial No, 436,032, filed February Patent protective No. device 2,379,114; is therefore granted seem to ratus the isprimary suppliedofby a trau the ' event that the thermal ‘resistance comes open-circuiteai. prior L able in such apparatus ‘ cutout was employed to internist the » current to terminate cease,the when sushi, main switch for the elect“ l 1, transformer 23 may he is merit. of, an open However, circiut this in cutout the thermal was cosh valve lil with suitable ' ‘ circuit to receive e" ' closure of the main 3 if} is actuated to open during the starting as operate. Consequently, prior disclosure to prcvi The main switch of . connected by a wire out having a combined secondary of the‘trausioE avoid undesired int‘ i minal of the main sv " ing the startihga by a Wire it to one te an object of the present iriverr ‘ to the ocerat’ e other terl theofcoil a control 32 is connectecl relay by wire s» to o -.e tion A of a parallel mesh which is connected the required protect type described without cutout. the other terminal of secondary of the trans» former 2:3 by a wire The main switch of valve the safety features of the prior invention while is and the operating coil arethus in series substituting the improved arrangement of this circuit One branch with the of secondary the narallel of transformer mesh consists of a invention 55 Another object of i " n is retain all 2,411,642 3 the ?rst resistor 48 when the timing element is thermal resistor 38 having a preselected tem perature coei?cient of resistance and located in proximity of the flame from the pilot burner I8. closed. The thermal resistor 38 is preferably in the form , of a coil of Wire of material having normally a relatively low resistance and a positive tempera ture cocflicient of resistance. While being ther mally responsive to the passage of current there through the thermal resistor 38 is primarily re sponsive to the heat of the ?ame of the pilot burner 18. It will be apparent that other types of temperature responsive, flame sensitive ele ments or so-called ballast resistors could be sub-‘ stituted for the thermally responsive resistor dis closed herein. The branch consisting of the _ parent, therefore, that in addition to opening and closing the parallel circuit for the cutout 48, the timing element 88 will simultaneously open and close the circuit of the igniter 88. Should the igniter 88 become. burnt‘out or otherwise dam 1.0 aged 50 that an open circuit occurs therein, then means provided herein may be operated man ually to complete the circuit of the igniter. This vmeans takes the form of a manually operated switch 18 which is normally held open by a spring 18 and is connected in parallel circuit with the igniter 88. The connection may be traced by way thermal resistor 38 is connected at one end by a of a Wire 88 connected at one end to the wire 12 and at the other end to one terminal of the switch wire 40 to the junction A and at the other end by a wire 42 to the opposite junction B of the parallel mesh. ' The second constant resistor serves to adjust the current value to the igniter 88. It is ap 18, and by a wire 82 extending‘from the other . terminal of the switch '_|8 to ‘the wire 10. A The other branch of the parallel mesh consists 20 suitable constant resistor 84 may be included in of an operating coil 44 for the electromagnetic the wire 88 in series with the switch 18 to com valve 16, a ?rst constant resistor 48 and a cutout pensate for the loss of the resistance value of 48. These elements are connected in series cir the igniter 88 should it become open-circuited. cuit in the other branch by a wire 50 connecting The operating coil 44 of the electromagnetic 25 one terminal of the coil 44 to wire 38 at junction valve I8 is ‘arranged to be shortécircuited for a A‘, a wire 52 connecting the opposite terminal of predetermined period of time during the initial coil 44 to one end of the resistor 48, a wire 54 or starting period in order to permit the igniter connecting the opposite end of the resistor 48 to 88 to produce a flame at the pilot burner l8 be one terminal of the cutout 48, and a wire 58 con 30 fore the main burner i8 is suppliedwith fuel. necting the opposite terminal of the cutout 48 The short-circuit for the coil 44 is established to wire 42 at junction B of the parallel mesh. by switching means in the form of a second tim As previously indicated herein, the cutout 48 is of the simple renewable type and will operate to interrupt the 'flow of current to the coil 44 ing element 88 in the control relay 30. As in the case of the timing element 88 the second tim ing element 88 may be of the mercury tube type and arranged to open from its initially closed‘ position after a predetermined time delay follow ing energization of the coil 32 but after a delay of the electromagnetic valve I8 upon the oc currence of an open circuit in'th'e thermal re sistor 38. As will appear hereinafter, no time delay or other special construction is required in connection with the cutout 48 due to the cir cuit arrangements of this invention. The ?rst constant resistor 48 serves to adjust the current value to the cutout'48 so that during the starting period of. only six seconds. ~ Preferably, both the 40 timing elements 80 and 88 close instantaneouly , period it is less than the steady operating value of the current supplied thereto and is of suitable resistance value for this purpose. It is apparent that during the starting period of the burner if current of su?icient value to actuate the electro magnetic valve l8 to open position is supplied to the coil 44 thereof, then the cutout 48 which is in series circuit with the coil 44 would also re ceive sufiiciently large current to cause it to op erate and open the circuit of the electromagnetic valve I8. Means are provided in this invention to prevent this undesired operation of the cutout ; 48 as will now be described. The control relay 38 embodies switching means upon deenergization of the coil 32, it being noted, ' however, that it is not essential that the timing element 80 have an instantaneous closing action as long as it assumes ‘a closed position before reopening of the timing element 88. Thus, where such ‘a short time delay as six seconds in estab lished for the timing element 88, then the timing element 60 would almost necessarily have an in stantaneous action also. A wire 88 connected. one electrode of the timing element 88 to wire 48 and a wire 90 connects the other electrode to the common wire 84. ‘The circuit from junction B of the parallel mesh to the transformer secondary is completed by a wire 92 connecting one end of a variable resistor 94 to junction B and a wire 98 connecting the other'end of the resistor 94 to the wire 28. The including a timing element 80 which is initially variable resistor is similar to the thermal re closed and has a speci?ed time delay of eighteen sistor 38 in having a positive temperature coe?l seconds before opening. Any suitably type of 60 cient of resistance and normal low resistance but‘ timing element may be used and, in this instance, is responsive only to the heating effect of the the mercury tube arrangement well known to current flow therein. The resistor accelerates those skilled in the art is preferred. One elec the closing of the electromagnetic valve i8 as trode of the timing element 88 is connected by disclosed in Patent No. 2,366,774 and is termed a wire 82 and a common wire 84 of the relay to a valve control resistor. the wire 52. The operation of the device is as follows: Manual or thermostatic closing of the main. The other electrode of the timing element 88 is connected by a wire 10 to one end of an electric resistance igniter 88 for the pilot burner. the opposite end of which is connected by a wire'12 to one end of a second constant re sistor 88. The opposite end of the second resistor 88 is connected by a wire 14 to junction B of the parallel mesh. Thus, timing element 80, igniter ' switch of valve I4 e?ects opening of this valve, as described, and permits fuel to ?ow in the main fuel pipe‘ 12 as far as the electromagnetic valve I8 which is initially closed. Electric energy from the transformer 24 is conducted from the second ary thereof by the wire 38 to junction A of the ' parallel mesh and by the wire 28, main switch 88 and resistor 88 are in series circuit and jointly establish a parallel circuit with cutout ‘a and 75 of valve I4, wire 28, wire 98, valve control resistor 53,411,6d2 84 and wire 32 to junction B of the parallel mesh. Although the operating coil 32 of the con— provided by the cutout 118 is required only dur trol relay 3!) is energized by the connection of one terminal thereof to the junction A by wire while they thermal resistor 38 is controlling the electromagnetic valve i6, and the parallel cir-v 34 and the opposite terminal to the main switch by wire 28, the delay periods of the timing ele ments 6B and 86 maintain the circuits which they are connected closed. Consequently, the coil M of the electromagnetic valve i6 remains short-circuited for six seconds by the shorter time delay element 85 and no fuel is supplied to the main burner to during the starting period. The ignitei' til is energized through the circuit from transformer secondary, wire as, main switch of valve l5, wire 96, valve control resistor 94; wire M, junction B, wire '14, second resistor 68‘ ing the running period oi’ the burner, that is, cuit or shunt provided for the cutout 48 during the starting period does not interfere with its essential function. The circuit arrangement described and shown herein permits considerable variation in the value ' 10 of the respective resistances without detracting from the desired operating characteristics. Moreover, while the preferred arrangement of parts has been illustrated and described it will‘ be apparent that the apparatus is not limited to this particular embodiment but various changes may be made within the scope of the appended claims. wire 12, igniter 555, wire tirning element 60, wires so and 9R3, timing element 86, wire88, I claim: ‘ junction A, and wire 85 ‘back to the transformer 1. A safety control system for fuel burners hav 24. During this starting period, the fuel flow— ing from the "pilot burner i3 is ignited by the igniter 65 but this period is too short for the thermal resistor 38 to become appreciably heated by the pilot burner flame and increase its rela ing a source of electrical energy, comprising elec trically operable means movable between posi tions for controlling the supply of fuel to a fuel burner, a thermal resistor having a preselected temperature coefficient of resistance located in tivelylovv resistance. At the end of the shorter time delay period the timing element lit opens and removes the short-circuit from the operat ing coil lid of the electromagnetic valve l6 and this valve is actuated to open position. it will be observed that the coil Q4 thus receives current proximity of the burner so as to be heated by‘ the ?ame produced by the burner and connected in parallel circuit with said controlling means for varying the energy value supplied thereto upon variations in the resistance of said thermal re sistor due to the presence or absence of said flame, current responsive lmeans in said circuit and operative for causing movement of said con controlling means to a position in which said fuel supply is prevented upon the occurrence of an open circuit in said thermal resistor, and ‘means electrically connected to said current re sponsive means and effective for preventing op eration thereof for a predetermined period dur ing which said thermal resistor has time to be come heated, said last means including a timing element operable upon expiration of said period for rendering said last means ineffective. of su?lcient value to cause opening of the elec tromagnetic valve l5 although the parallel circuit established by the thermal resistor 38 across junc tions A and B of the parallel mesh still exists. Such forced pick-up of the electromagnetic valve 16 is due to the combined resistance values of . the valve control resistor 9t, second resistor 68 and igniter lid being low enough for such pick--up to occur. Consequently, fuel then flows through the fuel pipe l2 to the main burner it! where it is ignited by the pilot burner l8. ‘ Upon the expiration of the longer time delay period of the timing element 60 which, as stated, may be eighteen seconds, the circuit of the ig niter 66 is discontinued causing deenergization 2. A safety control system for fuel burners hav- . ing a source of electrical energy, comprising elec ~ trically operable means for controlling the sup ply of fuel to a burner and being actuable to a thereof. In addition, the parallel circuit is re moved from the cutout E8 and first resistor 46 fuel supplying position when energy of sufficient by this opening operation of the timing element value is supplied thereto and being movable to a 60. The total circuit resistance is thus increased su?lciently to reduce the value of the current to the operating coil 4d of the electromagnetic valve i6 and cause this valve to close, unless the thermal resistor 38 is heated by the flame from the pilot burner i8 and its resistance increased sui?ciently to compensate for this increase in to tal circuit resistance. if at any time during the operation of the apparatus the flame of the pilot burner l 8 becomes extinguished, then the thermal position for preventing said fuel supply when energy of insu?lcient value is supplied thereto, resistor 38 will cool and its resistance be de creased sumciently to render the value of the current to the valve coil-44 insumcient to main tain the electromagnetic valve it in open posi - tion, whereupon this valve will close to terminate the supply of fuel to the main burner to. a thermal resistor having a preselected tempera ture coei?cient of resistance located in proximity of the burner so as to be heated by the flame produced by the burner and connected in a par allel circuit with said controlling means for vary ing the energy value supplied thereto upon varia tions in the resistance of said thermal resistor due to the presence or absence of said flame, current responsive means in said circuit and oper tin ative for causing movement of said controlling means from fuel supplying to fuel supply pre venting position upon the occurrence of an open circuit in said thermal resistor, and means elec trically connected to said current responsive It is apparent that the temperature‘ condition ' means and‘ effective for preventing operation of the thermal resistor does not in?uence the actuation of the electromagnetic valve l8 to open thereof for a predetermined period during which said thermal resistor has time to become heated, position, but does control the holding and ‘re said last means including a timing element oper lease of the valve. Should this thermal resistor 38 become open-circulted and. discontinue its branch of the parallel mesh, then the provision of the cutout which would consequently re ceivecurrent of operating value, serves to open the circuit of the operating coil 13-5 in the other said last means ine?ective and increasing the to tal circuit resistance to cause energy of said in su?icient value to be supplied to said controlling means unless said thermal resistor has varied due branch of the mesh. Hence, this safety feature 3. A safety control system for fuel burners hav~ able upon expiration of said period for rendering ' to the presence of the burner ?ame. - - . _ 2,411,642 ,ing‘a source of electrical energy, comprising elec trically operable means for controlling the sup ply of fuel to a burner and being actuable to a in series circuit with said controlling means for causing movement thereof from fuel supplying to fuel supply preventing position upon the occur rence of an open circuit in said thermal resistor, said current responsive means being short-cir value is supplied thereto and being movable to a cuited by said timing element and igniter for said position for preventing said fuel supply when predetermined period, and means cooperable with energy of insufficient value is supplied thereto, said current responsive means for establishing a a thermal resistor having a preselected tempera second circuit for said controlling means upon ture coef?cient of resistance located in proximity of the burner so as to be heated by the flame 10 operation of said timing element to discontinue said short-circuit and increase the total circuit produced by the burner and connected in a par resistance to cause energy of said insu?lcient ‘ allel circuit with said controlling means for vary value to be supplied to said controlling means ing the energy value supplied thereto upon varia unless said thermal resistor has varied due to the tions in the resistance of said thermal resistor due to the presence or absence of said ?ame, cur 15 presence of the burner ?ame. _ 5. A safety control and ignition system for fuel rent responsive means in series circuit with said burners having a source of electrical energy, com controlling means and operable for causing move prising a parallel mesh circuit connected to said ment thereof from fuel supplying to fuel supply source, a thermal resistor in one branch of said preventing position upon the occurrence of an open circuit in said thermal resistor, and means 20 mesh having a preselected temperature coefiicient of resistance and located in proximity of a burner electrically connected to said current responsive ?ame for varying in resistance due to the presq means for short-circuiting the same for a pre ence or absence of said flame, electrically oper determined period during which said thermal re able means in another branch of said mesh for sistor has time to become heated, said last means including a timing element operable upon ex 25 controlling the burner fuel supply and being actuable to a fuel supplying position when energy piration of said period for discontinuing the said of sumcient value is supplied to said controlling short-circuit and increasing the total circuit re means and being movable to a position for pre sistance to cause energy of said insu?icient value venting said fuel supply when energy of insu?l to be supplied to said controlling means unless said thermal resistor has varied due to the pres 30 cient value is supplied thereto, a cutout operative to open saidother branch and cause movement ence of the burner ?ame. of said controlling means from fuel supply to fuel 4. A safety control and ignition system for fuel ' fuel supplying position when energy of sufficient supply preventing position upon the occurrence burners having a source of electrical energy, com of an open circuit in said one branch, a ?rst ' prising electrically operable means for control ling the supply of fuel to a burner and being 35 resistor in said other branch for adjusting 'the energy value to said cutout, an electric igniter actuable to a fuel supplying position when energy adapted when energized to ignite the fuel and of sufficient value is supplied thereto and being cause the same to produce a, ?ame at the burner, movable to a position for preventing said fuel a second resistor for adjusting the energy value supply when energy of insuf?cient value is sup plied thereto, an electric igniter adapted when 40 to said ‘igniter, and a control device having a timing element for connecting said igniter and energized to ignite the fuel and cause the same , second resistor in parallel circuit with said cutout to produce a ?ame at the burner, means estab and ?rst resistor for a predetermined period in lishing a ?rst circuit for supplying energy of said which said thermal resistor has time to become sufficient value from the source to said control heated and cause the supply of energy to said ling means and including said controlling means, other branch to decrease to a value insu?icient to said igniter, and a control device having a timing operate said cutout, said timing ‘element being I element operable after a predetermined period operable upon expiration of said period for elecfor electrically disconnecting said igniter from selected temperature coe?icient of resistance tically discounting said igniter and said second resistor and thereby increasing the total circuit located in proximity of the burner so as to be resistance to causeenergy of said insu?lcient " said circuit, a thermal resistor having a pre heated by the ?ame produced by the burner and‘ electrically connected in parallel with said ?rst circuit for varying the energy value supplied to value to be supplied to said controlling means unless said thermal resistor has increased in resistance due to the presence of said burner said controlling means upon variations in the ?ame. . resistance of said resistor due to'the presence or absence of said ?ame, current responsive means ' CHARLES K. STROBEL.