US2637392A - Oven burner control mechanism - Google Patents

Description

May 5, 1953' c. M. MAYER 2,637,392

i ovEN BURNER CONTROL NECRANISN v Filed May 5. 1952 5 Sheets-Sheet l Ni. [N

' A 1N VEN TOR. (7708.. M /V/cz/yc/A 3%. Aff/0% any May 5, 1953 c. M... MAYER 2,637,392

OVEN BURNER CONTROL MECHANISM Filed May 5. 1952 3 Sheets-Sheet 2 IN VEN TOR.

C7703. M Mayer May 5, 1953 c. M. MAYER 2,637,392

OVEN BURNER CONTROL MECHANISM Filed 'may 5. 1952 :s sheets-sheet s T@ JW? Patented May 5, 1953 OVEN BURNER CONTROL MECHANISM Charles M. Mayer, Mansfield, Ohio, assignor to The Tappan Stove Company, Mansfield, Ohio, a corporation of Ohio Application May 5, 1952, Serial No. 286,194

14 Claims. 1

This invention relates to an automatic electric ignition and control mechanism for cooking range burners using gaseous fuel and is a modification of the control mechanism shown in the patent to Charles M. Mayer and John M. Hoff No. 2,577,787 issued December 11, 1951, and in the co-pending application of Richard L. Perl and John M. Hoff filed December 19, 1951. Serial No. 260,906. It is especially designed and adapted for automatically igniting and controlling the operation of oven burners in cooking ranges, and 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 gaseous fuel 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 gas 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. It has been found by experience that both the pilot burner and the main burner are frequently extinguished during operation. This is some-` times due to a momentary failure of the gas supply or the slamming of the oven door or to Various other reasons.

In order to prevent any accumulation of unburned gas and thus eliminate danger of an explosion therefrom in the event the pilot burner is extinguished for any reason during operation, a safety control unit by which the supply of gas to both the main burner and the pilot burner is completely cut off, in the event the pilot burner is extinguished for any reason during operation, is provided.

As shown herein the 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 pilot burner which burns only during the time the oven is in operation. At other times the supply of gas to both the main burner and the pilot burner is cut off by the safety control unit which is interposed in a main conduit between the gas supply manifold and the main burner. During operation gas flows from the manifold into the safety control unit. From the safety control unit gas flows through a small branch conduit directly to the pilot burner; and through the main conduit, a manually operable normally closed main control valve, and a standard thermostatically operated oven temperature control valve to the main burner. A normally open master control switch which is associated with the main control valve is provided to initiate operation of both the pilot burner and the main burner. The master control switch 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 energizes, through a normally closed thermostatically opened switch, a solenoid transformer which is operatively connected to the safety control unit, and the solenoid transformer when energized energizes an electric resistance ignition element. 'Ihe energization of the solenoid transformer causes it to set the safety control unit to permit the flow of gas from the safety control unit to the pilot burner while cutting off the supply of gas from the safety control unit to the main burner. The pilot burner is ignited by the electric ignition element and projects a flame against a thermostatic element which is operatively connected to the normally closed switch, and against a thermocouple which is operatively connected to an electromagnet in the safety control unit. After the thermostatic element becomes heated it opens the normally closed switch which de-energizes the solenoid transformer and the electric ignition element. As soon as the solenoid transformer is de-energized the safety control unit is automatically operated by spring means to maintain the supply of gas to the pilot burner through the branch conduit and to also supply gas to the main burner through the main control valve and 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 pilot burner, maintains the safety control unit through the electromagnet in condition to supply gas to both the main burner and the pilot burner. The oven temperature control valve then regulates the supply of gas to the main burner so as to maintain the desired oven temperature. As long as the pilot burner is ignited the main burner will burn normally under the control of the oven temperature control valve.

But if during operation the pilot burner is eX- tinguished for any reason the thermocouple will immediately cool and allow the safety control unit to automatically cut oilE the supply 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 manifold to the burners. The thermocouple immediately cools, allowing the safety control unit to cut olf communication between the manifold and both the main burner and the pilot burner. 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 solenoid transformer and the electric ignition element are again energized, since the master control switch is still open. The energization ofthe solenoid transformer will cause it to operate the safety control unit to reestablish communication between the .manifold and the pilot burner only. Then when gas is again available the pilot burner will be re-ignited and-reestablish normal operation ofthe oven as previously described.

' When it is desired to use'the apparatus in conjunction with any standard time control mechanism, I provide a .normally closed supplemental control switch which is kdisposed in series with the master control switch. The supplemental control switch is adapted to be opened and closed at predetermined set'times by the time control mechanism. When the time controlmechanism is'used the normally closed supplemental control switch is opened and the time control mechanism is set to initiate operation of the oven burner at a predetermined time by closing the supplemental control switch, and to terminate-operation thereof at-a predetermined set later time by opening the closed supplemental control switch. The main control valve isk then manually opened and the -master control switch is simultaneously closed. At the set time the time control mechanism will close the supplemental control switch which will effect the energization of the solenoid transformer and the electric ignition element. The apparatus will then operate as previously described in connection with manual'control until the time control mechanism opens the `supplemental control switch at the set later time toterminate operation. The opening of the supplemental control switohwill causethe safety control unit to cut off the supply of gasto boththe main burner and the pilot burner, thus terminating operation.

Prolonged power failures of many hours and sometimes of even several days duration frequently occur in various parts of the country. In order to eliminate the necessity of either keeping the main burner burning constantly during a prolonged power failure or manually actuating the safety control unit, as is normally done by the solenoid transformer, and then lighting the pilotburner with a'match, I provide means by which the pilot burner may be arranged to burn constantly instead of being extinguished each time the supply of gas to the main burner is cut off. The operation of the main burner is then controlled by the openingr and closing of the main control valve.

'I'he .principal object of the invention is to provide an improved,electricalignition and autoa conduit 3.

matic 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 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'fforrany reason during operation.

Another object of the invention is to provide an oven burner ignition and control system of the character ,described wherein the pilot burner may be arranged to burn only when the main burner Vis turned onor to burn constantly if desired.

Another vobject of the invention is to provide in an vautomatic ignition and control system for oven burners means by which the system may be easily converted from a fully automatic system to a constantly burning pilot burner system.

Another object-of the invention is to provide an automatic ignition or control mechanism of the-character described in which the safety control unit and the thermocouple circuit are utilized toinitiate and `terminate operation -of the main burner by the time control mechanism.

Still another object of the invention is to provide an improved electrical'ignition and control systemof the charatcer vdescribed -which may be used `in conjunction with a timecontrol mechanism or independently thereof as desired.

Other and more limited objects of the invention will vbe apparent from the following specication and the accompanying drawingsv forming a -part thereof, wherein:

Fig. l is a diagrammatic layout showing my improved'electrical ignition and safety control mechanism applied to a cooking range oven burner lusing gaseous fuel;

Fig. 2 is .an enlarged central vertical section through the safety-control unit showing the various parts in position to cut off the supply of fuel to both the pilot burner and the main burner;

Fig. 3 vis a-view similar to Fig. 2 showing the various parts in the position they are automaticallyimoved to when the master-control switch is closed to initiate the operation of the main oven burner; and

-Fig. .4 is awiring diagram of the-apparatus.

Referring now to the drawings by'reference characterathe numeral .l indicates a gaseous fuel burner .which is mounted in-or in heating relation toa cooking range oven 2. Gaseous fuel issupplied to the burner l from amanifold M through Interposed in the conduit 3 are a safety control valve mechanism generally indicated by .the numeral 4, -a manually operable main control valve 5and `an oven temperature control valve 6. During operation gas flows from the manifold M through the conduit Y3 to the safety control unit 4, to be. described inv detail hereinafter. From the safety control unitvll the gasflows through the conduit 3, the main control valve `5. and the ,oven temperature control valve 6 to the burner l. The oven temperature control valve 6 is operative to regulate the amountof gas flowing to the burner l during operation in-order to maintain the oven 2 at any desired set temperature. The valve 6 is set to any desired temperature by a handle v7 having a pointer 8 which cooperates with a graduated dialS carried by the valve `(i. The valve G is controlled according to the temperature setting by a thermostatic element i0 which is mounted 'in the oven2 and is connected to the valve G 4as shown at Il. The

main control valve is a standard shutoff valve which is manually opened and closed by a handle I3 and a valve stem I2. The oven temperature control valve 5 is of standard well known construction. Consequently it is not shown in detail herein. There are many different constructions available any one of which will work equally well herein. If desired the shut ofi valve 5.and the oven temperature control valve 6 may be combined as a single unit and both actuated by the same handle and stem. Many such combined valves are available. Gas is also supplied to a pilot burner I4 through a branch conduit I5 which extends between the safety control valve mechanism 4 and the pilot burner I4. The pilot burner I4 is disposed adjacent the rear end of the main burner l in position to ignite the burner I when gas is supplied thereto. An electrical ignition element I6 is operatively associated with the pilot burner I4 in position to ignite the pilot burner I4 when gas is supplied thereto. A thermostaticA element I1 and a thermocouple I8 are mounted in position to be heated by a flame from the pilot burner. The thermostatic element I1 iS operative to open and close a switch I9 which controls the energization of electrical ignition element I6 and a solenoid transformer 20 which when energized operates the safety control unit to supply gas to the pilot burner I4 only, as will be described in connection with the description of the safety control unit and the operation of the whole apparatus. The thermocouple I8, when heated, is operative to hold the safety control unit in condition to maintain the supply of gas to both the pilot burner I4 and the main burner I, as will also be described in connection with the description of the safety control valve mechanism and the operation of the apparatus. An electriccircuit between the thermocouple I8 and the safety control unit 4 is established by a copper tube 2| and an insulated wire 22 within the tube 2I.

A master control switch 23 and an interrupter switch 24 which cooperate with each other and with the main control valve 5 are provided to control the operation of the apparatus. The master control switch 23 is associated with the main control valve 5 and is adapted to be opened and closed by a cam 25, carried by the valve stem I2, through a link 26. The arrangement is such that the switch 23 is simultaneously closed with the opening of the main control valve 5, and is simultaneously opened with the closing of the valve 5. The interrupter switch 24 is interposed in the thermocouple circuit as shown in Fig. 4. It is normally closed and is arranged to be maintained open by a relay 21 when the relay is energized. The energization of the relay 21 is controlled by the master control switch 23 as will be explained hereinafter.

The construction of the safety control unit 4 and its connection to the solenoid transformer 20 will now be described, reference being had to Figs. 2 and 3, of the drawings. This unit comprises a casing 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 38 of reduced diameter. A valve seat 39 is located at one end of the bore 38 and a similar valve seat 46 is located at the other end of the bore 38. The chamber 36 is closed by a removable cap 4I and the chamber 31 is closed by a removable cap 42. A sleeve 43, having end walls 44 and 45, is carried by the cap 4I and extends into the chamber 36. A valve stem 46 which is slidably mounted in a bushing 41 car- 6 ried by the end wall 45 of the sleeve 43, extends from the chamber 36 into the sleeve 43. A control valve 48 of suitable material is secured to one end of the valve stem 46 within the chamber 36. and an armature 49 is secured to the other end of the stem 46 within the sleeve 43. A spring 50 disposed about the valve stem 46 between `the control valve 48 and the end wall 45 of the sleeve 43 normally holds the control valve 48 against` the valve seat 39.l An electromagnet 5I is secured to one end of a hollow exteriorly threaded stud 52 which extends out through alignedapertures in the end wall 44, of the sleeve 43, and in the end of the cap 4I. A nut 53 screwed onto the outer portion of the stud 52 securely holds the magnet 5I and the sleeve 43 in place.` The legs of the magnet 5I have a winding 54 thereon, one end of which is connected to the tube 2| and the other end of which is connected to the wire 22 in the tube 2|. The tube 2I is inserted into the hollow stud 52 and is held in place by a screw fitting 52a. A sleeve 55 is screwed into a threaded recess in the end of the cap 42, as indicated at 56, and extends into the chamber 31 a slight distance. One end of the sleeve 55 `is closed by an end wall 51, and the other end, which is open, registers with a circular aperture 58 in the end wall of the cap 42. A plunger 59 is slidably mounted in the sleeve 55 and extends out through the aperture 58 in the cap 42'. A stem62, which is secured to the inner end of the plunger 59, extends out through an aperture 63 in the end wall 51 of the sleeve 55, and through the chamber 31 and into the bore 38. The stem 62 has a collar 64 rigidly secured thereon between the end wall 51 and the outer end of the stem. An interrupter valve 65 of suitable material is slidably mounted upon the stem 62 between the end wall 51 of the sleeve 55 and the collar 64. The interrupter valve 65 is adapted to engage the valve seat 40 to cut oi 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 51 and the valve 65 normally yieldingly holds the valve 65 against the collar 64. 'A compression spring 61 which is stronger than the spring 66 is disposed about the stem 62 within the sleeve 55 between the inner face of the end wall 51 and the inner end of the plunger 59. The spring 61 is operative to return the plunger 59, stem 62 and valve 65 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 35 provides communication between the chamber 36 and the conduit 3 to allow gas to flow from the manifold M through the conduit 3 into the chamber 36. Duringv normal operation of the main burner I gas ows from the chamber 36 through the reduced intermediate bore 38 and into the chamber 31. A port 69 which establishes communication between the branch conduit` I5 and the bore 38 is provided to supply gas to the pilot burner I4; and a port 10 establishes communication between the chamber 31 and the conduit 3 to permit the ow of gas from the chamber 31 to the main burner I through the main con-A trol valve 5 and the oven temperature control valve 6.

The solenoid transformer 20 comprises a spool 15 on which are wound the primary winding 16 and the secondary winding 11. An' armature 18 is slidably mounted in the bore 19 of the spool 15. The solenoid transformer 20 may be operatively associated with the safety control unit 4 control unit 4 and release the valve 48. The spring 50 will then close the valve 48 and cut oif the flow of gas to both the main burner I and the pilot burner I4. At any time thereafter the apparatus may be reset for manual control by closing the valve 5 and switch 85 and opening the switch 23. If during automatic operation the pilot burner I4 is extinguished for any reason the apparatus will function to cut off the supply of gas as described in connection with manual operation.

In order that the oven may be repeatedly used during a prolonged power failure without the necessity of manually lighting the pilot burner I4 with a match each time it is used, I provide means by which the apparatus can be quickly and easily converted from a fully automatic electric ignition system to a constantly burning pilot burner system. To this end I connect a normally closed switch in series with the interrupter switch 24 in the thermocouple circuit by the leads IOI and |02. In order to convert the apparatus to a constantly burning pilot burner system the normally closed switch |00 is opened and the safety control unit 4 is manually set and held in the condition shown in Fig. 3, by depressing the button |03 secured to the armature 13, in which condition gas can flow to the pilot burner I4 and be ignited by a match. The control unit 4 must be held as shown in Fig. 3 until the pilot burner I4 has heated the thermocouple I8 sufficiently for it to energize the electromagnet 5I after which the button |03 may be released. The electromagnet 5I will hold the control valve in the chamber 36 open as shown in Fig. 3 and the spring 61 will return the interrupter valve in the chamber 36 back to open position shown in Fig. 2. Then the operation of the burner I is manually controlled by the opening and closing of the valve 5. Obviously the apparatus cannot be automatically controlled by the time control mechanism 86 during a power failure.

From the foregoing it will be apparent to those skilled in this art that I have provided a very simple and efficient mechanism for accomplishing the objects of the invention.

It is to be understood that I am not limited to the specific construction shown and described herein as various modifications may be made therein within the scope of the appended claims.

What is claimed is:

l. 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 gaseous fuel supply manifold, a main conduit through which fuel is supplied to said main burner from said manifold, a safety control unit operative to cut off the supply of fuel to said main burner and said pilot burner` interposed in said conduit between said main burner and said manifold, a manually operable shut off valve interposed in said conduit between said safety control unit and said main burner, a branch conduit extending between said safety control unit and said pilot burner through which fuel is supplied to said pilot burner, a solenoid operatively associated with said safety control unit, said solenoid being operative upon energization to first set said safety control unit in condition to supply fuel to said pilot burner while cutting off the supply of fuel to said main burner and upon subsequent deenergization to set said safety control unit in condition to also fl il supply fuel to said main burner, an electromagnet associated with said safety control unit and operative when energized to maintain said safety control valve in said last 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 said thermocouple is heated, a normally closed interrupter switch interposed in said circuit between said thermocouple and said electromagnet in parallel with said electromagnet, said interrupter switch being operative when closed to shortcut said electromagnet and thereby control the energization of said electromagnet, a normally open master switch which is operative when closed to effect the energization of said solenoid and said electric ignition element, a normally closed switch disposed in series with said master switch which is operative when opened to effect deenergization of said solenoid and said electric ignition element, 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.

2. An automatic ignition and control apparatus as dened in claim l in which the closing and opening of said master switch effects the opening and closing of said interrupter switch.

3. An automatic ignition and control apparatus as dened in claim 1 in which a relay is disposed in series with said master switch and is operative when energized to maintain said interrupter switch open.

- 4. An automatic ignition and control apparatus as dened in claim 3 in which a supplemental control switch is disposed in series with said master control switch and said relay, and a time control mechanism is provided which is operative to open and close said supplemental control switch at predetermined set times.

5. An automatic ignition and control apparatus as defined in claim 3 in which a normally closed manually actuable switch is disposed in series with said interrupter switch.

6. An automatic ignition and control apparatus as defined in claim 1 in which a supplemental control switch is disposed in series with said master switch, and a time control mechanism is provided which is operative to open and close said supplemental control switch at predetermined set times.

7. An automatic ignition and control apparatus as defined in claim 6 in which means is provided which is rendered operative to open said interrupter switch by the closing of said supplemental control switch.

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, an electric ignition element operative when energized to ignite said pilot burner, a gaseous fuel supply manifold, a

umain conduit through which fuel is supplied to said main burner from said manifold, a safety control unit operative to cut off the supply of fuel to said main burner and said pilot burner interposed in said conduit between said main burner and said manifold, a manually operable shut olf valve interposed in said conduit between said safety control unit and said main burner, a branch conduit extending between said safety control unit and said pilot burner through which fuel is supplied to said pilot burner, a solenoid operatively associatedxwith rsai-d Asafety controlr unit,- said solenoidV being operativeyupon energization to rstset -said;safety control unit in condition to supply fuel to said-pilot .burner while cutting 01T the supply offuel to said main burner andl uponA subsequent deenergizationwto set saidy safety control unit in condition to'also supply fuel to said main burner; anY electromagnetl associated with said safety control unitandr operative when energized to maintain saidsaiety control valve in said last set condition.- a .thermocouple adapted to be heated by saidpilot burner, am` electriccircuit between said' thermocouple and saidelectromagnet through whichsaid magnet is energized by said. thermocouple when said thermocouple is heated,- a normallyvclosed intern rupter switch interposed insaid vcircuit `betweensaid `thermocouple g and .saidy electromagnet Ain paralleli with saidl electromagnet; said interrupter switch being operati-ve Awhenclosedto short out said electromagnetandthereby control the energization of said electromagnetya normally open;

masterswitchwhich is operative when Vclosed to effect the energization'oi fsa-id solenoid andsa id.

electricv ignition element@` ay normally` closed switch disposed in series withsaidmaster switch which: is operative when opened f to effect deenergization of. said solenoidy and-said electric ignition element, and means responsive to saidvpilot` burneryand operative to l maintain said normally closedL switchA `open whilesaid pilot burnerl is ignited.v l

Y 9., A n automatic ,ignition and control lapparatuses defined in c laimS in which the closing and opening of said master-.switch effects vthe openingjandclosing 4voi said interrupter switch.

10. Arr automatic ignition and `control appa-v ratus as denedfin claimf8 in .which a relay is= disposed in series with said master switch'ad is operativewhen venergized to maintain saidinter#l rupter switch open.

11. An automaticignitio'n and lcontrol ap'pa-' ratus as defined vin claim 10 in which a supple# mental control switch is vdisposed in seriesxwith said master controlswitch and said relay; and aV t .said master switch; and a :time control mecha# nism is provided which is opera-tive to open and close said supplementalv control' switch at prede# termined set times.vv

14. An automatic ignitionfand controlV appa# ratus as defined inzclaimy 13 in which-'mearisdsv provided which is rendered. Ioperativeftoopenf said interrupter switchtby the closingl oftsaid supplementalcontrol switch.

CHARLES MrMAYER.

Refr'en's 'cited in tir me of. this patent UNITED STATE'SPATENTS,

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