US2577787A - Gas burner control mechanism - Google Patents

Description

Dec. 11, 1951 c. M. MAYER EIAL. 2,577,787

GAS BURNER CONTROL MECHANISM 3 Sheets-Sheet l Filed-April 3, 1950 r M a w m w M M mtw ca% y 5 I. Ill-Ill Ill |llll|lln Dec. 11, 1951 c. M. MAYER ETAL 2,577,787

GAS BURNER CONTROL MECHANISM Filed April 3, 1950 3 Sheets-Sheet 2 i (1 I w W IN V EN TORS Lj y Charles M Mayer Dec, 11, 1951 Filed April 3, 1950 C. M. MAYER ETAL GAS BURNER CONTROL MECHANISM a Sheets-Sheet 5 LINE I A09 zlll v v 5'4 '1 .57 80 86 .9 g "I 27 83 Z J mw W IINVENTORS C'hczr/es MMa yer 9 John M. Hoff Patented Dec. 11, 1951 Gas-BURNER CONTROL Macnmsm Charles M. Mayer and John Hofl, Mansfield,

Ohio, assignors to The Tapl an Stove Company, Mansfield, Qhio, a corporation of Ohio Application April 3, 1950, Serial No. 153.664

This invention relates to an automatic electric 11 Claims. (Cl. l61-9) ignition and control mechanism for cooking range burners using gaseous fuel. It is especially designed and adapted for automatically igniting and controlling the operation of oven burners in cooking ranges; but it may be used equally well to control the operation of other gaseous fue bumers. It may be used in conjunction with a time control mechanism or independently thereof as desired.

The mechanism is designed for use. with a main gaseous fuel burner which is adapted to be ignited by a constantly burning gaseousfuel pilot burner. As long as the pilot burner is ignited it is immaterial whether or not the main burner burns constantly. It may be extinguished for some reason but it will be promptly re-ignited by the pilot burner if fuel is supplied thereto. 'But if the pilot burner is extinguished for any reason while the main control valve is still open to supply 2 tion. At other times the supply. of gas to both the main burner andv the pilot burner is cut oil .by a main control valvewhich is interposed in a anism gas will flow through a small branch congas to the main burner a very dangerous situation sometimes arises. Let us assume that both the pilot burner and the main burner are extinguished during operation for some reason. Gas can then flow to the main burner but since the pilot burner is extinguished the main burner will not be ignited and unburned gas will accumulate in the oven which may violently explode when an attempt is made to ignite either the main or pilot burner. This is likewise true if gas to the main burner is cut off by the main control valve when the oven is not in use and the constantly burning pilot burner becomes extinguished for any reason. It

- has been found by experience that both the pilot burner and the main burner are frequently extinguished during use while the main control explosion therefrom in the event the pilot'burner is extinguished for any reason while the control valve is still set to supply gas to the main burner, we provide in our improved apparatus safety control mechanism by which the supply of gas to both the main burner and the pilot burner is completely out off, independently of the main control valve, in the event the pilot burner is extinguished for any reason while the main gas control valve is open.

Our improved apparatus includes a main gaseous fuel burner by which the oven in a cooking range is heated. The main burner is adapted to be ignited'by a gaseous fuel pilotburner which burns only during the time the oven is in operaduit directly to the pilot burner; and through the main conduit and a standard thermostatically operated oven temperature control valve to the main burner. A normally open master control switch which is operatively associated with the main control valve is arranged to be closed by the opening of the main control valve and to be opened by the closing of the main control valve. The closing of the master control switch, as the main control valve is opened to supply gas to the burners, energizes through a normally closed thermostatically operated switch an electric resistance ignition element and a solenoid which is operatively connected to the safety control valve mechanism. The energization of the solenoid causes it to operate the safety control valve mechanism to permit the flow of gas to the pilot burner while cutting off the supply of gas to the main burner. The pilot burner is ignited by the electric ignition element and projects a flame against a thermostatic element, which controls the operation of the normally closed switch, and against a thermo couple which is operatively connected to the safety control valve mechanism. After the thermostatic element becomes heated it opens the normally closed switch which deenergizes the electric ignition element and the solenoid. As-soon as the solenoid is de-ener'gized the safety control mechanism is automatically operated by spring means to supply gas to the main burner through the oven temperature control valve. The main burner is then ignited by the pilot burner. The thermocouple, as long as it 'is heated by the pilotburner, maintains the safety control valve mechanism in condition to supply gas to both the main burner and the pilot burner.

reason the thermocouple will immediately cool and allow the safety control valve mechanism to automatically cut off thesupply of gas to both the main burner and the pilot burner. As an example of the manner of operation of the apparatus, let us assume that during operation the pilot burner is suddenly extinguished, for instance, by a momentary failure of the gas supply from the maniately cools, allowing the safety control valve mechanism to cut oil communication between the manifold and both the main burner and the pilot burner. The main control valve is still open and the master switch closed. Then after the thermostatic element has cooled, closing the normally closed switch, which is maintained open by the thermostatic element during normal operation of the oven, the electric ignition element and the solenoid are again energized. The energization of the solenoid will cause it to operate the safety control valve mechanism to establish communication between the manifold and the pilot burner only. Then when gas is again available the pilot burner will be ignited and reestablish normal operation of the oven as previously described. In the event of a power failure during normal operation of the oven, the main burner will continue to operate normally under the control of the oven temperature regulator valve until the burner is turned off by the main control valve, assuming of course that the pilot burner continues to burn. In the event of a power failure before gas is turned on by the main control valve, the

pilot burner can be manually ignited as will be hereinafter explained. The supply of gas to both the'main burner and the pilot burner will then be controlled by the pilot burner through the thermocouple and safety control valve mechanism as previously described.

In addition to the aforesaid possibilities of accumulating unburned gas in an oven, there-is one other condition under which unburned gas could collect in an oven. Our improved control apparatus is also designed to take care of thiscontingency and prevent the accumulation of unburned gas in an oven should this condition ever occur. For example, assume that while the main burner is operating normally the main control valve is closed and then immediately opened again before the thermocouple and the thermostatic element have had time to cool. The closing of the main control valve extinguishes both the main burner and the pilot burner by cutting off the supply of gas thereto. Then when the main control valve is immediately reopened gas is again supplied to both the main burner and the pilot burner since the thermocouple has not had time to cool sufiiciently to allow the safety control valve mechanism to operate to cut oif the supply of gas to both burners. But under this condition the pilot burner will not be ignited because the still hot thermostatic element is maintaining the normally closed switch open and preventing energization of the electric ignition element and of the soleniod. Thus unburned gas will escape from both the main burner and the pilot burner into the oven until the thermostatic element cools and closes the normally closed switch. As soon as the thermostatic element cools sufiiciently it will energize the ignition'element which will ignite the pilot burner and it in turn will ignite the main burner. But in the meantime enough gas may have escaped into the oven from the main burner and the pilot burner to cause a bad explosion when the pilot burner is again ignited. In order to eliminate the escape of any unburned gas into the oven whenever-this condition occurs, I provide an interrupter switch in the circuit between the thermocouple and the safety control valve mechanism. This switch is located in the same casing as the master control switch and is opened and closed by the closing and opening of the main control valve simultaneously with the opening and closing of the master control switch. Then when the main control valve. is closed to cut off the supply of gas to the burner the interrupter switch is simultaneously opened, breaking the circuit between the thermocouple and the safety control mechanism which permits the safety control switch mechanism to cut oil all communication to both the pilot burner and the main burner. Then when the main control valve is immediately opened after having been momentarily closed nothing will happen until the thermostatic element cools and closes the normally closed switch which occurs between six and ten seconds. After that the apparatus functions in its normal manner as has been explained. 1

When it is desired to use the apparatus in conjunction with any standard time control mechanism we provide a supplemental master switch and a supplemental interrupter switch which ar'e'simultaneously opened and closed at predetermined times by the time control mechanism. The supplemental master switch is inserted in the main circuit iniseries with the pri- 'mary master switch, and the supplemental interrupter switch is inserted ,-in the thermocouple circuit inseries. with the primary interrupter switch. In use the time control. mechanism is nism the apparatus will function in the same manner as previously described. When a range is equipped with a time control mechanism, means to lockthe supplemental switches closed is also provided in order that the apparatus may be used independently of the time control mechanism if desired.

Theprincipal object of the invention is to provide an improved electrical ignition and automatic control system for cooking range oven burners using gaseous fuel.

Another object of the invention is to provide in an electrical ignition and control system of the character described improved means for completely shutting off the supply of gas to both the main burner and the pilot burner in the event the pilot burner becomes extinguished for any reason before the supply of gas to both the main burner anld the pilot burner is cut off by the main control va ve.

Another object of the invention is to provide in an apparatus of the character described means to prevent the escape ofany unburned gas in the event the main contr'olvalve is turned off after a period of operation and is then immediately turned back. on-before the heat responsive elemerlits inthe system-have had an'opportunity to coo a Still another object of theinvention is to provide an improved electricalignition and control system of the character described which may be used conjunction with a time control mechanism or independently thereof as desired.

Other and more limited objects of the invention will be apparent from the following specification and the accompanying drawing forming a part thereof, wherein:

Fig. l is a diagrammatic view illustrating our improved electrical ignition and safety control mechanism as applied to a cooking range oven burner using gaseous fuel;

tical section throughthe safety control valve mechanism showing the various parts in the position they assume when-the oven burner is Fig. 3' is a view similar to Fig. 2 showing the various parts in the positions they are automatically moved to when the main control valve is first turned on to initiate the operation of the main oven burnerr v Fig. 4 is a horizontal section taken on the line 44'of F18. 1;

Fig. is a wiring diagramof'the apparatus as used independently of a time control mechanism; and y Fig. 6 is a wiring diagram of the apparatus as used in conjunction with a time control mech- Referring now to the drawings by reference characters, the numeral I indicates a gaseous fuel burner which is mounted in or in heating relation to a cooking range oven 2. Gaseous fuel is supplied to the burner I from a manifold (not shown) through a conduit 3. Interposed in the conduit 3 are a main control valve 4, a safety control valve mechanism generally indicated by the numeral 6, and an oven temperature control valve 6. The main control valve 4 is a cut off valve of standard construction which when in open or on position permits the flow of gas through the conduit 3 from the manifold to the burner I, and in closed or off position cuts oil flow of gas to the burner I. This valve is manually opened and closed by a handle I and a valve stem 8, and directly controls the operation of the entire apparatus in that it initiates the operation of the entire apparatus when it is turned to the on position and terminates the operation when it is turnedto the ofi position. From the main control valve 4 gas flows through a connector 3 to the safety control valve mechanism 5, to be described in detail hereinafter. From the safety control valve mechanism 5 the gas flows through a connector III, the oven temperature control valve 6 and the conduit 3 to the burner I. The oven temperature control valve 6 is operative to regulate the amount of gas flowing to the bumer I in order to maintain the oven at any desired set temperature. The valve 6 is set to any desired temperature by a handle II having a pointer I2 which cooperates with a graduated dial I3 carried by the valve 6. The valve 6 is controlled according to the temperature setting by a thermostatic element I4 which is mounted in the "oven 2 and is connected to the valve 6 as shown quently it is not shown in detail herein. Thereare many different constructions available any one of which will work equally well herein. Gas is also supplied to a pilot burner I6 through a branch conduit I! which extends between the safety control valve mechanism and the pilot burner I6. The pilot burner I6 is disposed adjacent the rear end of the main burner I in position to ignite the burner I when gas is supplied thereto. An electrical ignition element I3 is operatively associated with the pilot burner I6 in position to ignite the pilot burner I6 when gas is supplied thereto. A thermostatic element I8 and a thermocouple 26 .are mounted in position to be heated by a flame from the pilot burner. The thermostatic element I3 is operative to open and close a switch 2| which controls the energization of the electrical ignition element I8 severed ends.

and a solenoid 22 which when energized operates the safety control valve mechanism to 'sup-' ply gas to the pilot burner I6 as will be -described in connection with the description of the safety control valve mechanism and the operation of thewhole apparatus. The thermocouple 26 when heated is operative to holdthe safety control valve mechanism in condition to maintain the supply of gas to both the pilot burner I6 and the main burner I, as will also be described in connection with the description of the safety controlvalve mechanism and the operation of the apparatus. A switch mechanism 23 which is associated with the main controlvalve 4 is adapted to be opened and closed simultaneously with the closing and opening of the main control valve 4.' As the control valve 4 is turned from the off or closed position to the on or opened position the switch mechanism 23 is moved from the open position to the closed position by an operating lever 24 which 'cooperates with a cam section 25 on the main control valve stem 3. Conversely, when the main control valve 4 is turned from the open or on position to the closed or oil position the switch mechanism 23 is moved from the closed position to the open position.

An electric circuit between the thermocouple 26 and the safety control valve mechanism 5 is established by a copper tube 26 which encloses an insulated wire 21. The wire 21 is severed between the thermocouple 20 and the safety control mechanism 5 and an interrupter 26 having terminals 29 and 30 is interposed between the One of the severed ends of the wire 21 is connected to the terminal 23 and the other severed end is connected to the terminal 30. The purpose and function of the interrupter 28 will be explained in detail in connection with the description of the operation of the apparatus.

The construction of the safety control valve mechanism 5 and its connection to the solenoid 22 will now be described, reference being had to Figs. 2, 3 and 4 of the drawing. This mechanism comprises a casing 35 having a chamber 36 in one end thereof and a chamber 31 in the other end thereof. The chambers 36 and 31 are connected by a bore 33 of reduced diameter. A valve seat 33 is located at one end of the bore 33 and a similar valve seat 40 is located at the other end of the bore 36. The chamber 36 is closed by a removable cap H and the chamber 31 is closed by a removable cap 42. A sleeve 43, having end walls 44 and 46, is carried by the cap 4I and extends into the chamber 36. A valve stem 46 which is slidably mounted in a bushing 41 carried by theend wall 46 of the sleeve 43, extends from the chamber 36 into the sleeve 43. A valve disc 48 of suitable material is secured to one end of the valve stem 46 within the chamber 36, and a metal disc 43 is secured to'the other end of the stem 46 withinthe sleeve 43. A spring 60 disposed about the valve stem 46 between the valve disc 43 and the end wall 46 of the sleeve 43 normally holds the valve disc 48 against the valve seat 33. A horseshoe magnet BI is secured to one end of a hollow exteriorly threaded stud 62 which extends out through aligned apertures in the end wall 44, of the sleeve 43, and in the end of the cap M. A nut 53 screwed onto the outer portion of the stud 62 securely holds the magnet BI and the sleeve 43 in place. The legs of the magnet 6i have a winding 54 thereon one end of which is connected to the tube 26 and the other end of which is connected to the wire 2'! in the tube 29. The tube 26 is inserted into the hollow stud 32 and is held in place by a screw fitting 62a. A sleeve 66 is screwed into a threaded recess in the end of the cap 42, as indicated at 66, and extends into the chamber 31 a slight distance. One end of the sleeve 66 is closed by an end wall 61, and the other end which is open registers with a circular aperture 68 in the end wall of the cap 42. A plug 69 is slidably mounted in the sleeve 66 and extends out through the aperture 69 in the cap 42. The outer end of the plug 69 has a reduced extension 48 formed integral therewith, providing an annular shoulder 6I around the extension 69 at the outer end of the plug 69. A stem 62 which is secured to the inner end of the plug 69 extends out through an aperture 63, in the end wall 61 of the sleeve 66, and through the chamber 31 and into the bore 38. The stem 62 has a collar 64 rigidly secured thereon between the end wall 61 and the outer end of the stem. A valve disc 66 of suitable material is slidably mounted upon the stem 62 between the end wall 61 of the sleeve 65 and the collar 64. The valve disc 65 is adapted to engage the valve seat 48 to cut oil the flow of gas into the chamber 31 during the initiation of operation as will be hereinafter described. A compression spring 66 disposed about the stem 62 between the end wall 61 and the valve disc 66 normally yieldingly holds the valve disc 66 against the collar 64. A compression spring 61 which is stronger than the spring 66 is disposed about the stem 62 within the sleeve 66 between the inner face of the end wall 61 and the inner end of the plug 59. The spring 61 is operative to return the plug 59, stem 62 and valve disc 66 from the position shown in Fig. 3 back to their normal position as shown in Fig. 2, against the resistance of the spring 66. A port 68 in the casing 36 provides communication between the chamber. 36 and the connector 9 to allow gas to flow from the 'main control valve 4 through the connector 9 and into the chamber 36. During normal operation of the main burner I gas flows from the chamber 36 through the reduced intermediate bore 38 and into the chamber 31. A port 69 which establishes communicationbetween the conduit I1 and the bore 38 is provided to supply gas to the pilot burner I6; and a port 18 establishes communication between the chamber 31 and the connector I8 to permit the flow of gas from the chamber 31 to the main burner I through the oven temperature control valve and the conduit 3.

The safety control valve mechanism 5 is operatively connected to the solenoid 22 by a yoke 12 and a link 13. The yoke 12 which encompasses the safety control valve mechanism 5 as shown in Fig. 4 comprises a pair of spaced parallel arms 14 which are connected together at one end by a bridge 15. The bridge 15 has an aperture 16 therein through which the reduced end 68 of-- the plug 59 extends with the inner face of the bridge engaging the shoulder 6I between the plug 59 and the reduced ei'rtension 68 thereof. The other ends of the arms 14 terminate in a pair of spaced parallel ears 11 to and between which one end of the link 13 is pivotally connected. The other end of the link 13 is pivotally connected to the movable core 18 of the solenoid 22 as indicated at 19.

The switch mechanism 23 consists of the master control switch 88 and the interrupter switch 8|. The master control switch 88 comprises the contacts 82 and 83 which are adapted to be bridged by the conductor bar 84; and the interrupter switch 8| comprises the contacts 96 and 86 which are adapted to be bridged by the conductor bar 81. The switch 2I comprises three contacts 88, 89 and 98 which are adapted to be bridged by a conductor bar 9] when the switch is in its normal closed position.

The supplemental master switch which is shown at 92 in Fig. 6 comprises the contacts 93 and 94 which are adapted to be bridged by a conductor bar 95; and the supplemental interrupter switch which is shown at" in Fig. 6 comprises the contacts 91 and 98 which are adapted to be bridged by a conductor bar 99. The conductor bars 95 and 99 are mounted on a base I88, of insulating material, which is adapted to be moved toward and away from the contacts 93, 94, 91 and 98 at predetermined times by a time control mechanism I8I through a connecting link I82. When it is desired to operate the oven burner of a range which is equipped with a time control independently of the time control mechanism, the switches 92 and 96 are locked in closed position through the medium of a manually operable button I83 incorporated in the time control mechanism IN.

The operation of the apparatus will now be described in connection with Fig. 5 which is a wiring diagram showing the electrical circuits of our improved ignition and control apparatus without a time control mechanism incorporated therein.v To initiate the operation of the oven burner I it is only necessary to set the oven temperature control valve 6 to the desired temperature and to manually turn the main control valve 4 from the off position to the on position. After that the ignition and operation of the burner are automatically controlled until the operation of the-burner is terminated by manual y turning the main control valve 4 from the on position to the off position. As the main control valve 4 is turned from the off position to the on position the master switch 88 and the interrupter switch 8I are simultaneously closed by the cam 25 and lever 24. After the main control valve has been opened gas can flow from the manifold through the main control valve 4 and into the chamber 36 of the safety control valve mechanism 5, the various parts of which are in the position shown in Fig. 2. But the gas can go no farther since the valve disc 48 is being held against the valve seat 39 by the spring 58, thus closing the only exit from the chamber 36. As soon as the switch 88 is closed current flows from one side I of the line through the lead I86 to the terminal 82 and thence through the conductor bar 84 to the terminal 83. From the terminal 83 the current flows through the lead I81 to the terminal 88 of the normally closed switch 2|, and thence through the conductor bar 9| to the terminals 89 and 98. From the terminal 89 the current flows through the leadv I88 to the electrical resistance ignition element I8, thence through the ignition element I8 and back to the other side I89 of the line through the lead II8, thus completing a circuit through the ignition element I8 which energizes it and renders it operable to ignite the pilot burner I6 as soon as gas is supplied thereto. From the terminal 98 of the normally closed switch 2I the current also flows through the lead III to the solenoid 22, thence through the winding of the solenoid and back to the other side J89 of the line through the lead I I2, thus completing a circuit which energizes the solenoid 22. ,The energization of the solenoid 22 causes it, through the link 13 and yoke 12, to

' 9 shift the various parts of the safety control valve mechanism from the position shown in Fig. 2 to the position shown in Fig. 3. In this position the valve disc 43 is held away from the valve seat 39 and the metal disc 49 is held against the ends of the legs of the magnet 6| by stem 62 acting against the resistance of the spring 56. This allows gas to flow from the chamber 36 into the bore 38 and thence through the port 69 and conduit l1 to the pilot burner l6 where it is ignited by the ignition element I8. But the gas cannot yet flow to the main burner I since the valve disc 65 is being held against the seat 46 by the spring 66 which cuts oiT communication between the bore 33 and the chamber 31. As soon as the pilot burner I6 is ignited it projects a flame against and heats both the thermocouple .29 and the thermostatic element l3. The heating of the thermocouple 20 generates a minute current which energizes the magnet suiflciently for it to hold the metal disc 49 and the stem 46 and valve disc 48 secured thereto in the position shown in Fig. 3 against the pressure of the spring 50 after the disc 49 has been moved into engagement withthe magnet 5i by the solenoid 22.v But the magnet 5i when energized by the thermocouple 26 is not strong enough to attract and withdraw the metal disc 49, and the stem 46 and valve disc 46 secured thereto, from the position shown in Fig. 2 to the position shown in Fig. 3. It can only hold these parts in this position after they have-been moved thereto by the solenoid 22 through the medium of the link 13, yoke 12, plunger 59 and stem 62. The electric circuit between the thermocouple 26 and the winding 54 of the magnet 5| is through the copper tube 26, which extends unbroken between the thermocouple and the winding 54, and the wire 21 which is severed between the winding 54 and the thermocouple 29. One of the severed ends of the wire 21 is connected to the terminal 54. From the winding the current will flow back through the wire 21 to the terminal 29.

From the terminal 29 the current will flow through lead. II5 toand through the switch 3i,

and back to the terminal 30 through the lead I I 6. From the terminal 36 the current will flow back to the thermocouple 26 through the other section of the wire 21, completing the circuit between the thermocouple 20 and the winding 54 of the magnet 5|. This circuit will be maintained as long as the thermocouple is heated. After the thermostatic element I9 has been heated sufliciently, which is after the thermocouple has energized the magnet 5i, it will open the norma ly closed switch 2i, breaking the circuit to and de-energizing both the ignition element I6 and the solenoid 22. After the pilot burner has been ignited there is no further need to main- ,tainthe ignition element energized. As soon as the solenoid ,22 is de-energized the spring 61 will return the plunger 59, stem 62 and valve disc 65 back from the position shown in Fig. 3 to the position shown in Fig. 2 against the pressure of the spring 66., The valve disc 43 will be held in the position'shown in Fig. 3 by the magnet 5|.

Communication is then established between the chambers 36 and 31 through the bore 36. Gas will then flow from the chamber 36 into the chamber 31 through the bore 36. From the chamber 31 gas will flow through the oven temperature control valve '6 and conduit 3 to the main burner I where it will be ignited by the pilot burner I6. The apparatus is now operating normally, and in the absence of any abnormal conditions it will continue to do so, provided the pilot burner remains ignited, until the supply of gas to both the pilot burner and the main burner is cut off by the manual closing of the main control-valve 4.

In the event the pilot burner I6 is extinguished for any reason during operation, the thermocouple 20 will cool in a few seconds and de-energize the magnet 5|. magnet 5| will allow the spring 59 to move the valve disc 48 back into engagement with the valve seat 39, as shown in Fig. 2, which will cut of! the flow of gas from the chamber 36 into the bore 33 and chamber 31, and from them to the pilot light I6 and the main burner. l. The burner I will then be extinguished along with the pilot burner. As soon as the thermostatic element I9 cools it willclose the switch 2| which will energizeboth the ignition element I3 and the solenoid 22 as previously described since the main control valve 4 is still open and the switches and 8i are closed. The pilot burner I6 will then be reignited and the rest of the apparatus will again function as described, provided there is gas available. If no gas is available everything will remain in condition to ignite the pilot burner and re-initiate operation as 'soon as gas is again available. In the event of either a momentary or prolonged power failure during operation, the apparatus will continue to operate normally until terminated by the manual closing of the main control valve, provided of course that all other conditions are normal. In order to operate the apparatus during a prolonged power failure which occurred prior to operation, it is only necessary to hold a match to the pilot burner I6 and manually move the plunger 59 from the position shown in Fig. 2 to the positionshown in Fig. 3 and hold it in this position a suflicient time for the thermocouple 26 to become heated, after which the plunger 59 may be released and allowed to be returned to its initial position by the spring 61. The apparatus will then continue to function normally as described under the control of the pilot burner I6 and the oven temperature control valve 6. When the time control mechanism IOI is incorporated in the apparatus as shown in Fig. 6, we interpose -the supplemental master switch 92 in the lead I01,.between the contact 83 of the master switch 99 and the contact 86 of the normally closed thermostatically operated switch 2|, in series with the master switch 60; and we interpose the supplemental interrupter switch 96 in the lead H6, between the contact 91 of the interrupter switch 96 and the terminal 30 of the interrupter 28, in series with the interrupter switch 9'6. The time control mechanism when used is operative to close the switches 92 and 96 at a predetermined set time and to open the switches at a predetermined' set later time. After the switches 32 and 96 have been closed the mechanism functions in exactly the same manner as described in connection with Fig. 5, until at the predetermined set later time the time control mechanism opens theswtiches 92 and 9,6 which terminates The de-energizing oi' the the operation just as effectivelyas if the main control valve had been turned off. The opening of the supplemental master switch 82 by the time control mechanism at the predetermined later time has no effect upon the operation of the apparatus; but the opening of the supplemental interrupter switch 98 breaksthe circuit between the thermocouple 20 and the safety control valve mechanism which de-energizes the magnet and allows the spring to move the valve disc 48 from the position shown in Fig. 3

into engagement with the valve seat 39 as shown in Fig. 2. This closes the exit from the chamber 36 and completely cuts offthe 'supply-ofgas to both the main bumer land'the pilot burner l8.- The main control valve 4'can then be-manually.

event the pilot burner is extinguished for am! 7 herein as various modifications may be made "therein within-the scope of the appended claims.

closed at any time after the timecontr'ol mechanism has terminated operation. Operation cannot again be initiated until; the fmainf control" valve 4 is opened and '96 are closed; 2

As previously statedpit mitea'lyjhisatstthat afterthe apparatus has ,-been in op ration for.

the switches ill, 8],, and

sometime the operator turns the main control valve off and then im mediately turns it on again before the thermocohplelll and they thermostatic element have had 'ajn opportunity to=cool The closing of the maincont'rol.valvel cuts off th e i, supply of gas to and extinguishes'iboththe main burner l and the? pilot burner it. .*..Under this 'condition, if the interrupter switch fflfwas not interposed in the circuit between the thermocouple 20 andthe safety.control valve mechanism 5 and arrangedto be opened and closed by the closing and opening of the main control valve 4, unburned gas would escape into the oven from both the pilot burner and the main burner until the thermocouple cooled and cut off the supply of gasto' both burners as previously described. During this time sufficient gas could accumulate in the oven to cause abad explosion when the pilot burner or the main burner l What is claimed is:

' -1-. In an automatic ignition and control anparatus of the character described, the combination of a" main burner,. a pilot burner operative "to" ignite said 'main burner, a conduit through whichgaseous fuel "is supplied to said main burner; a; manually operable main control valve by fwhich 'the supply of fuel to said main burner and said pilot burner is primarily controlled, a

safety controlvalve mechanism interposed in said conduit between said main control valve and said "-m'ain burner, a secondary conduit extending between said safety control valve mechanism and q said pilot burner through which gaseous fuel is supplied to said pilot burner, said safety control valve mechanism. being operative to control the supply of fuel to said main burner and said pilot burner after the fuel leaves said main control valve, a solenoid operatively connected to said safety control valve mechanism, said solenoid being operative upon. energization to set said safety control valve mechanism in condition to supply fuel to said pilot burner while cutting off the supply of fuel to said main burner and upon subsequent de-energizationto set said safety control valve mechanism in condition to also supply fuel to said main burner, a normally closed switch operative to control the energization of said sole- I noid, and a thermostatic element adapted to be were again ignited; Therefore" we provide the interrupter switch 8| in order :to preventany escape of unburned gas when thiscondition occurs.

With the interrupter switch 8i arranged as shown a and described the momentary closing of the main heated by said pilot burner and operative to maintain said switch open when heated and closed when cool."

2. In anautomatic ignition and control apparatus of the character described, the combinacontrol valve 4 will simultaneously operrthe interrupter switch 8|. The opening of the interrupter switch ill will break the circuit between the thermocouple and the safety control valve mechanism and de-energize the magnet 5| even though the thermocouple is still hot. The deenergization of the magnet 51 allows the spring to move the valve disc 48 into position to cut off the supply of gas to both the main burner and the pilot burner "as previously described.

The immediate .opening of the control valve 4 under this condition will have no effect upon the apparatus until the thermostatic element l9 cools and closes the switch 2|. This is due to the fact that the magnetil when energized is not strong enough to shift the valve disc 48;'andthe connected *parts from the closed position shown in Fig. 2 to the open position showri-ginlFigB,

but can only hold them in this-position; after they have'been moved thereby the solenoid Z2."' Afte r the thermostatic element I9 cools and closes the switch 2|, which takes from six to ten seconds;

tion of a main .burner,- a pilot burner operative to ignite said main burner, a conduit through which gaseous fuel is supplied to said main burner, a manually. operable main control valve by whichvthe supply of fuelto said main burner and said pilot burner is primarily controlled, a safety control-valve mechanism interposed in said conduit between said main control valve and said main burner, a secondary conduit extending between said safety control valve mechanism and said pilot burner through which gaseous fuel is supplied to said pilot burner, said safety control valve mechanism being operative to control the supply of fuel to said main burner and said pilot burner after the fuel leavessaid main control valve, a solenoid operatively connected to said safety control valve mechanism, said solenoid being operative upon energization' to set said safety control valve mechanism in condition to 1 supply fuel to said pilot burner while cutting off the supply of fuel to said main burner and upon the ignition element l8 and the solenoid are again energized after which the operationipro'-'-' ceeds as previously described. v I r Operating current is supplied tothe'time control mechanism llil from the line l05i+l09bythe leads H1 and H8.

From the foregoing it will be seen that in the subsequent de-energization to set said safety control valve mechanism in condition to also supply fuel to said m'ain burner, a normally open master switchwhich is operative when closed to energize said solenoid,-a normally closed switch which is operative-when opened to de-energize said solenoid, and a thermostatic element adapted to be heated by said pilot burner and-op erative when heated to maintain said normally closed switch open and when coolto maintain said normally closed switch closed. v

3. In an automatic ignition and control apparatus of the character described, the combination of a main burner, a pilot burner operative to ignite said main burner, an electric ignition element operative when energized to ignite said pilot burner, a conduit through which gaseous fuel is supplied to said main burner, a manually operable main control valve. by which the supply of fuel to said main burner and said pilot burner is primarily controlled, a, safety control valve mechanism interposed in said conduit between said main control valve and said main burner, a secondary conduit extending between said safety control valve mechanism and said pilot burner through which gaseous fuel is supplied to said pilot burner. said safety control valve mechanism being operative to control the supply of fuel to said main burner and said pilot burner after the fuel leaves said main control valve, a solenoid operatively connected to said safety control valve mechanism, said solenoid being operative upon energization to set said safety control valve mechanism in condition to supply fuel to said pilot burner while cutting oil the supply of fuel to said main burner and upon subsequent de-energization to set said safety control valve mechanism in condition to also supply fuel to said main burner, a normally open master switch associated with said main control valve, operative connections between said main control valve and said master switch through which said master switch is closed by the opening of said main control valve and is opened by the closing of said main control valve, said master switch being operative when closed to energize said solenoid and said electric ignition element, a normally closed switch disposed in series with said master switch which is operative when opened to deenergize said solenoid and said electric ignition element, a thermostatic element adapted to be heated by said pilot burner and operative when heated to maintain said normally closed switch open and when cool to maintain said normally closed switch closed.

4. In an automatic ignition and control apparatus of the character described, the combination of a main burner, a pilot burner operative to ignite said main burner, a conduit through which gaseous fuel is supplied to said main burner. a manually operable main control valve by which the supply of fuel to said main burner through which gaseous fuel is supplied to said pilot burner, said safety control valve mechan sm including a normally open valve and a normally closed valve, a solenoid operatively connected to said safety control valve mechanism, said solenoid being operative upon energization to close said normally open valve andto open said normally closed valve and upon subsequent (18-811? ergization to reopen said normally open valve,-a

thermocouple adapted to be heated by said pilot burner and operative when heated to maintain said normally closed valve open after it has been opened by the action of said solenoid whereby fuel is first supplied to said pilot burner and then upon the subsequent de-energization of said solenoid fuel is supplied to both said pilot burner and said main burner, a normally open master switch which is operative when closed to energize said solenoid, a normally closed switch which is operative when opened to de-energize said solenoid, and a thermostatic element adapted to be heated by said pilot burner and operative when heated to maintain said normally closed switch open and when cool to maintain said normally closed switch closed.

5. In an automatic ignition and control apparatus of the character described, the combination of a main burner, a pilot burner operative to ignite said main burner, an electric ignition element operative when energized to ignite said pilot burner, a conduit through which gaseous fuel is supplied to said main burner, a manually operable main control by which the supply of fuel to said main burner and said pilot burner is primarily controlled, a safety control valve mechanism interposed in said conduit between said main control valve and said main burner and operative to control the supply of fuel'to said main burner and said pilot burner after the fuel leaves said main control valve, a secondary conduit extending between said safety control valve mechanism and said pilot burner through which gaseous fuel is supplied to said pilot burner, said' safety control valve mechanism including a normally openvalve and a normally closed valve, a solenoid operatively connected to said safety control valve mechanism, said solenoid being operative upon energization to close said normally open valve and to open said normally closed valve and upon subsequent de-energization to reopen sequent de-energization of said solenoid fuel is supplied to both said pilot burner and said main burner, a normally open master switch associ-.-.

ated withsaid main control valve, operative connections between said main control valve and said master switch through which said master switch is closed by the opening of said main control valve and is opened by the closing of said main control valve, said master switch being operative when closed to energize said solenoid and said electric ignition element, a normally closed switch disposed in series with said master switch which is operative when opened to de-energize said solenoid and said electric ignition element, a thermostatic element adapted-to be heated by said pilot burner and operative when heated to maintain said normally closed switch open and when cool to maintain said normally closed switch closed.

6. In an automatic ignition and control apparatus of the character described, the combination of a main burner, a pilot burner operative to ignite said main burner, a conduit through which gaseous fuel is supplied to said main burner, a manually operable main control valve by which the supply of fuel to said main burner and said pilot burner is primarily controlled, a safety control valve mechanism interposed in said conduit between said main control valve and said main burner, a secondary conduit extending between said safety con m chanism and said pilot burner through which gaseous fuel is supplied to said pilot burner, said safety control valve mechanism being operative to control the supply of fuel to said main burner and said pilot burner after the .fuel leaves said main control valve. a

solenoid operatively connected to said safety control valve mechanism, said solenoid being operative upon energization to set said safety control valve mechanism in condition to supply fuel to said pilot burner while cutting off the supply of fuel to said main burner and upon subsequent de-energization to set said safety control valve mechanism in condition to also supply fuel to said main burner, an electromagnet associated with said safety control valve mechanism and operative when energized to maintain said safety control valve mechanism in said set condition, a thermocouple adapted to be heated by said pilot burner, an electric circuit between said thermocouple and said electromagnet through which said magnet is energized by said thermocouple when heated, an interrupter switch interposed in said circuit and operative to open and close said circuit and thereby control the energization of said electromagnet, a normally open master switch which is operative when closed to energize said solenoid, a normally closed switch which is operative when opened to de-ener ize said solenoid, and a thermostatic element adapted to be heated by said pilot burner and operative when heated to maintain said normally closed switch open and when cool to maintain said normally closed switch closed.

7. In an automatic ignition and control apparatus of the character described, the combination of a main burner, a pilot burner operative to ignite said main burner, an electric ignition element operative when energized to ignite said pilot burner, a conduit through which gaseous fuel is supplied to said main burner, a manually operable main control valve by which the supply of fuel to said main burner and said pilot burner is primarily controlled, a safety control valve mechanism interposed in said conduit between said main control valve and said main burner, a secondary conduit extending between said safety control valve mechanism and said pilot burner through which gaseous fuel is supplied to said pilot burner, said safety control valve mechanism being operative to control the supply of fuel to said main burner and said pilot burner after the fuel leaves said main control valve, a solenoid operatively connected to said safety control valve mechanism, said solenoid being op rative upon energization to set said safety control valve mechanism in condition to supply fuel to said pilot burner while cutting off the supply of fuel to said main burner and upon subsequent de-energization to set said safety control valve mechanism in condition to also supply fuel to said main burner, an electromagnet associated with said safety control valve mechanism and operative when energized to maintain said safety control valve mechanism in said set condition, a thermocouple adapted to be heated by said pilot burner, an electric circuit between said thermocouple and said electromagnet through which.

said electromagnet is energized by said thermocouple when heated, an interrupter switch interposed in said circuit and operative to open and close said circuit and thereby control the energization of said electromagnet, a normally open master switch associated with said main control valve, operative connections between said main control valve and said master switch through which said master switch is closed by the opening of said main control valve and is opened by the closing of said main control valve, said master switch being operativewhen closed to energize said solenoid and said electric ignition element, a normally closed switch disposed in series with said master switch which is operative when opened to de-energize said solenoid and said electric ignition element, a thermostatic element adapted to be heated by said pilot burner and operative when heated to maintain said normally closed switch open and when cool to maintain said normally closed switch closed.

8. In an automatic ignition and control apparatus of the.character described, the combination of a main burner, a pilot burner operative to ignite said main burner, a conduit through which gaseous fuel is supplied to said main burner, a manually operable main control valve by which the supply of fuel to said main burner is primarily controlled, a safety control valve mechanism interposed in said conduit, a secondary conduit extending between said safety control valve mechanism and said pilot burner through which gaseous fuel is supplied to said pilot burner, said safety control valve mechanism being operative to control the supply of fuel to said main burner after said main control valve has been opened, means through which said safety control valve mechanism is set in condition to supply fuel to said pilot burner and said main burner, an electromagnet associated with said safety control valve mechanism and operative when energized to maintain said safety control valve mechanism in said set condition, a thermocouple adapted to be heated by said pilot burner, an electric circuit between said thermocouple and said electromagnet through which said electromagnet is energized by said thermocouple when heated, an interrupter switch interposed in said circuit and operative to open and close said circuit and thereby control the energization of said electromagnet, said interrupter switch being associated with said main control valve, and operative connections between said main control valve and said interrupter switch through which said interrupter switch is closed by the opening of said main control valve and is opened by the closing of said main control valve.

9. In an automatic ignition and control apparatus of the character described, the combination of a main burner, a pilot burner operative to ignite said main burner, a conduit through which gaseous fuel is supplied to said main burner, a manually operable main control valve by which the supply of fuel to said main burner and said pilot burner is primarily controlled, a safety control valve mechanism interposed in said conduit between said main control valve and said main burner and operative to control the supply of fuel to said main burner and said pilot burner after the fuel leaves said main control valve, a secondary conduit extending between said safety control valve mechanism and said pilot burner through which gaseous fuel is supplied to said pilot burner, said safety control valve mechanism including a normally open valve and a normally closed valve, a solenoid operatively connected to said safety control valve mechanism, said solenoid being operative upon energization to close said normally open valve and to open said normally closed valve and upon subsequent deenergization to reopen said normally open valve. an electromagnet associated with said safety control valve mechanism and operative when energized to hold said normally closed valve open after it has been opened by the action of said couple and said electromagnet through which said electromagnet is energized by said thermocouple when heated, an interrupter switch interposed in said circuit and operative to open and close said circuit and thereby control the energization of said electromagnet, said interrupter switch being associated with said main control valve, and operative connections between said main control valve and said interrupter switch through which said interrupter switch is closed by the opening of said main control valve and is opened by the closing of said main control valve.

10. In an automatic ignition and control apparatus of the character described, the combination of a main burner, a pilot burner operative to ignite said main burner, a conduit through which gaseous fuel is supplied to said main burner, a manually operable main control valve by which the supply of fuel to said main burner is primarily controlled, a safety control valve mechanism interposed in said conduit, a, secondary conduit extending between said safety control valve mechanism and said pilot burner through which gaseous fuel is supplied to said pilot burner, said s fety control valve mechanism being operative :2 control the supply of fuel to said main burner ter said main control valve has been opened, means through which said safety control valve mechanism is set in condition to supply fuel to said pilot burner and said main burner, an electromagnet associated with saidsafety control valve mechanism and operative when--:energized to maintain said safety control valve mechanism in said set condition, a thermocouple adaptedto be heated by said pilot burner, an electric circuit between said thermocouple and said electromag,

net through which said magnet is energized by' said thermocouple when heated, an interrupter switch interposed in said circuit and operative to open and close said circuit and thereby control the energization of said electromagnet, operative connections between said main control valve and said interrupter switch through which said interrupter switch is closedby the opening of said main control valve and is opened by the closing of said main control valve, a supplemental interrupter switch interposed in said circuit in series with said interrupter switch, and a time control mechanism operative to close and open said supplemental interrupter switch at predetermined mechanism interposed in said conduit between said main control valve and said main burner, a secondary conduit extending between said safety control valve mechanism and said pilot burner through which gaseous fuel is supplied to said pilot burner, said safety control valve 18 v mechanismbeing operative to control the supply of fuel to said main burner and said pilot burner after the fuel leaves said main control valve, a solenoid operatively connected to said safety con- 5 trol valve mechanism, said' solenoid being operative upon energization to set said safety control valve mechanism in condition to supply fuel to said pilot burner while cutting off the supply of de-energization to set said safety control valve mechanism in condition to also supply fuel to said main burner, an electromagnet associated with said safety control valve mechanism and operative when energized to maintain said safety control valve in said set condition, a thermocouple adapted to be heated bysaid pilot burner, an electric circuit between said thermocouple and said electromagnet through which said magnet is energized by said thermocouple when said thermocouple is heated, an interrupter switch interposed in said circuit and operative to make and break the circuit between said thermocouple and said electromagnet and thereby control the energization of said electromagnet, operative connections between said main control valve and said interrupter switch through which said interrupter switch is closed and opened by the opening and closing of the main control valve, a nor- -mally open master switch associated with said main control valve, operative connections between said main control valve and said master switch through which said master switch is closed by the opening of said main control valve and is opened by the closing of said main control valve,

said master switch being operative when closed to energize said solenoid and said electric ignition element, a normally closed switch disposed in series with said master switch which is operative when opened to de-energize said solenoid and said electric ignition element, a thermostatic element'adapted to be heated by said pilot burner and operative when heated to maintain said normally closed switch open and when cool to maintain said normally closed switch closed, a supplemental master switch disposed in series with said master switch and said normally closed switch, a

*supplemental interrupter switch interposed in said circuit in series with said interrupter switch, and a time control mechanism operative to simultaneously close and open said supplemental master siyitch and said supplemental interrupter switch at predetermined set times.

CHARLES M. MAYER. JOHN M. HOFF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name 7 Date 1,174,442 Phillips Mar. 17, 1916 1,178,272 Simke Apr. 4, 1916 2,249,442 'Thornbery July 15, 1941 5 2,276,909 Alfery Mar. 17, 1942 2,303,672 Wantz Dec. 1, 1942 2,307,871 Wantz Jan. 12, 1943 2,315,773 Couzens Apr, 6, 1943 2,318,136 Alfery May 4, 1943 2,318,801 Ray May 11, 1943' 2,353,042 Koch July 4, 1944 2,383,676 Paille Aug. 28, 1945 2,385,530 Paille Sept. 25, 1945 2,391,753 Strobel Dec. 25, 1945 2,409,947 Mantz Oct. 22, 1946 fuel to said main burner and upon subsequent

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