US2557927A

US2557927A - Oven lighting system

Info

Publication number: US2557927A
Authority: US
Publication date: 1951-06-26
Anticipated expiration: 1968-06-26

Description

June 1951 v. R. ABRAMS ET AL 2,

OVEN LIGHTING SYSTEM Filed June 20, 1946 3 Sheets-Sheet 1 Arrirs.

June 1951 v. R. ABRAMS ET AL 2,557,927

v OVEN LIGHTING SYSTEM Filed June 20, 1946 s Sheets-Sheet 2 7/ a INVENTORS if/t1 Mw ATTi s.

Patented June 26, 1951 OVEN LIGHTING SYSTEM Victor R. Abrams and Peter I. Hollman,

Ill., assignors to Geo.

Rockford, 111., a corpor Rockford,

D. Roper Corporation, ation of Illinois Application June 20, 1946, Serial No. 677,965

This invention relates generally to gas lightin devices and particularly to the automatic lighting of gas burning kitchen stoves or ranges.

A problem heretofore unsolved satisfactorily is presented in the lighting of the oven burner of the so-called table top kitchen stove where the oven burner is located at a substantial distance below the top cooking burners.

In the early constructions of table top stoves, the oven burner was lighted by hand, with a match or flint resulting in dangerous puffing or even a serious explosion if the gas was turned on before the match was lighted. Other disadvantages are attendant with this type of lighting in that the housewife or other operator must stoop down to an awkward position to reach the burner within the oven.

In later constructions this objectionable hand lighting has been eliminated by providing a second constantly burning pilot light in the oven, in addition to the one that is provided at the top of the stove for lightin the cooking burners. The oven burner is lighted simply by turning the temperature control knob, in the same manner as the cooking burners are lighted. While in some respects this construction does operate satisfactorily, it is objectionable from the standpoint of the extra cost requiredto supply this second pilot light with gas.

In still later constructions, a semi-automatic oven lighting system has been devised employing an intermittently lighted sub-burner or oven pilot which is lighted by flashback through a flashtube extending to the constantly burning cooking pilot when the oven temperature control knob is turned. Inasmuch as a certain time interval is required before the flashback tube can be filled with a flashable gas-air mixture to light the subburner, and, for safety, the gas must not be allowed to issue from the main burner ports until the sub-burner is lighted, the operation proceeds in two phases. The housewife first turns the control knob a small amount to a point where it encounters slight resistance to turning. At this position she pauses for a few seconds while the sub-burner is being-lighted. Then, second, when she hears the flash in the flashtube, or after she waits a length of time which by. experience she has found suflicient to light the sub-burner, she turns the knob further to the desired temperature setting thereby admitting gas to the main burner which is lighted from the sub-burner. While this construction alsooperatesflsatisfactorily in 'many respects and eliminates the need for a costly constantly burning second pilot, it would 18 Claims. (Cl. 158-117.1)

2 be preferable that it be fully automatic so that the housewife could light the oven simply by turning the control knob, in a single operation, to the temperature desired, instead of remembering each time to pause in the intermediate position long enough for the sub-burner to be lighted.

In a more recent construction, forming the subject matter of copending application, Serial No. 642,941, filed January 23, 1946, a completely automatic oven lighting system was disclosed in which an automatic timing mechanism was employed to carry out the required cycle of operations. The operation is simplified to the extent that the housewife merely turns the control knob to the desired temperature setting and the oven lights itself without further attention or thought on her part.

The present invention constitutes in a sense an improvement over the system of the above.- mentioned copending application in the respect that it is completely automatic in operation, yet

it eliminates the use of a separate timing system to carry out the lighting cycle.

An important object of the present invention is the provision of a simplified automatic oven lighting system in which a permanent magnet is employed to hold the main oven burner valve closed during the lighting of the oven pilot and, after the latter is lighted, its flame acts to heat a thermocouple or other thermoelectric generator to reduce the hold efl'ect of the permanent magnet to the extent that the oven valve is permitted to open to supply fuel to the oven burner.

A primary object of the present invention lies in the provision of a permanent magnet adapted to magnetically attract an armature connected to the main oven burner inlet valve for shutting off the supply of gas to the oven burner during the initial part of the lighting operation while the oven pilot is still unlighted.

Another object is the provision of an oven lighting system having permanent magnet means for maintaining the oven inlet valve closed until the pilot i lighted, and the provision of an electromagnet coil connected to a thermocouple positioned in the oven pilot flame, this coil being associated with the permanent magnet in such a manner as to neutralize the holding power of the magnet on the valve when the pilot is lighted and thereby permit the valve to'be opened by a spring or other suitable means to supply gas to the oven burner.

A specific feature of the invention lies in the provision, of 'an oven lighting system having an 3 electromagnet which is supplied by current generated in a thermocouple which is responsive to heat of the oven pilot flame, the electromagnet being adapted to neutralize the magnetic attraction of a permanent magnet for a main burner control valve when the oven pilot is lighted; another object incident to such a construction resides in positioning the permanent magnet a distance from the electromagnet suiilciently that the permanent magnet will not be permanently de-magnetized to any appreciable extent by the thermally generated current.

Another feature of the present invention resides in the provision of an automatic oven lighting system having a valve controlling flow of gas to the over burner, a valve controlling flow to a sub-burner, a main inlet valve controlling flow to the above-mentioned oven burner and sub-burner valves, a valve controlling flow to an oven pilot light, a permanent magnet for holding the valves in temporary positions to effeet the lighting of the sub-burner and oven pilot from a constantly burning remote pilot, and an electromagnet excitable in response to the heat of the oven pilot for counteracting the magnetic attraction of the permanent magnet to permit the valves to be moved to positions where the sub-burner supply is shut off and the oven burner is supplied with gas for ignition by the pilot.

Other objects and advantages will become apparent from the following description in connection with the drawings, in which Figure 1 is a schematic view in perspective of an automatic oven lighting system illustrating one embodiment of the present invention;

Fig. 2 is an enlarged view of the safetywalve unit shown in Figure 1;

Fig. 3 is a fragmentary sectional view of Fig. 2 taken on the line 3-3;

Fig. 4 is a view similar to Fig. 2 showing the.

elements of the safety valve unit as they will be positioned immediately after the control knob has been depressed to initiate the oven lighting operation;

Fig. 5 is a view similar to Fig. 4 but showing the parts at a later stage in the lighting operanon;

Fig. 6 is a view similar to Fig. 3 of a modified electromagnet construction, and

Fig. '7 is a sectional view of Fig. 6 taken on the line |-1.

The complete assembly shown in Figure 1 will be first briefly described to provide a general background for a subsequent detailed description of the components of the lighting system. Raw gas is supplied from a manifold 2| to an oven temperature control unit generally designated 22, which has a capillary tube 23 terminating in a bulb 24 which will be located in the ,oven and which is responsive to the temperature to be controlled. A rotary plug-type shut-off valve 25 is incorporated within the unit 22 and when it is turned to the on position gas is delivered through a pipe 26 to -a safety valve unit generally designated 21, from which gas is supplied through a main line 28 to a mixing box 29, a mixing tube 3|, and a main burner 32. Gas is also supplied from a safety valve unit 21 through an auxiliary gas line 33 to a mixing tube 34 which delivers an air-gas mixture to a sub-burner generally designated 36, and having a plurality of jets 31 for burning a number of individual flames. Gas is supplied to the oven pilot burner valve 39 from two sources: the line 5| wherein the rate of flow is controlled by the throttle valve 52; and the line 51a from the heat control unit 22. Both lines SI, 5112 feed into a line 53 entering the safety valve unit and their combined flow normally passes to the oven pilot burner 39 through line 54 and passage 148 formed in the sub-burner arm 38. The sub-burner is preferably located outside the oven or in close proximity to the oven with the lateralburner arm 38 extending into the oven, or into a compartment within the general boundaries of the oven, and the pilot light or burner 39 will be located in lighting proximity to the main oven burner 32. This pilot 39 is adapted to be lighted from the flames of the sub-burner jets 31, as will be presently described. Heat from the pilot light 39 acts against a thermoelectric generating means which in this case comprises a pair of thermocouples 4| and 41a. Thermocouple II is connected through a two-wire lead 42 which connects with an electromagnet coil I00 in the front end of the safety valve unit 21. Thermocouple dla connects through a two-wire couple lead 42a with an electromagnet coil I92 positioned in the rear end of the safety valve unit. As will be described in detail subsequently, the safety valve unit 21 is controlled through the electromagnets and the thermoelectric generating means to maintain the main gas supply to the oven shut off until the oven pilot burner 39 is ignited and then serve to direct flow to the oven burner 32 for ignition by the pilot light.

The usual constantly burning pilot 43 located at the top of the stove serves to light any one of the top or cooking burners 44 in the conventional manner through its flash tube 46. This pilot 43 also serves to light the sub-burner jets 31 by flashback through the flashtube 41; and the sub-burner in turn serves to light the oven pilot 39 by flashback through the passage 48 in the arm 38. The particular flashtube 41, which is shown in connection with the present invention, is substantially the same as that described. in copending application Serial No. 642,941, filed January 23, 1946, and divisional application Serial No. 91,373 filed May 4, 1949, to which reference may be had for the details of its construction and operation.

Referring now in detail to the components of this automatic oven lighting system, the oven heat control 22 and the control knob 49 may be of any suitable or preferred construction, for ex ample, of the type disclosed in Patent 2,303,011, granted November 24, 1942, to which reference may be had for a more detailed'description. Briefly, the operation is such that the housewife first depresses the control knob in the order of it; or A; of an inch and then rotates it to select the proper temperature setting, this rotation causing the plug 25 to be opened and admit gas simultaneously to the safety valve inlet line 26 and the oven pilot burner inlet line 53 through line Sta which will be in addition to that already supplied through oven pilot inlet line 5| direct from the manifold.

The oven burner 32, oven pilot burner 39, subburner 36, and a constantly burning pilot burner 43are identical with those disclosed in copending application Serial No. 642,941, and reference may be had to that application for details concerning their construction and operation. Briefly, for the purpose of explaining the present invention, the safety valve unit 21, presently to be described in detail, admits gas simultaneously to the subburner and pilot burner when manually initiated by depression of the operating shaft I03. Gas

passes upwardly from the sub-burner into the flashtube 41 and upon issuing proximate to the constantly burning pilot burner 43, flashes back and ignites a sub-burner. Gas by this time has issued from the pilot burner 39 and filled the passage 48 through an oven burner side jet (not shown) wherein it will flash from the sub-burner and light the oven pilot 39. A thermoelectric generating means, such as a pair of thermocouples M and Ma, positioned responsive to the heat of the oven pilot-burner, will then energize electromagnets within the safety valve unit, as will be explained, to shut off flow to the subburner and simultaneously admit gas to the main oven burner 32, which will be ignited by the'oven pilot burner.

The safety valve unit 21, wherein an important part of the present invention resides, comprises a casing I which to facilitate assembly may be divided into portions 56 and 51 joined with a gasketing joint at 58 by any convenient means, as, for example, bolts (not shown). The casing is provided with the following ports: main inlet port 59 connected to the regulator 22 through line 26; main outlet port 6I connected to the oven burner 32 through line 28; sub-burner outlet port 62 connected to thesub-burner 36 through line 33; pilot valve inlet port 63 connected directly to the manifold and to the temperature regulator 22 through lines 5| and 5I a; and pilot valve outlet port 64 connected to the oven pilot burner 39 through line 54 and passage I48. The front casing member 5'! is formed with an intermediate bore 66 terminating in the seats 61 and 68.

The main inlet valve 69 which controls the flow of gas from the regulator 22 to the sub-burner 36 and the oven burner 32 has a soft leather-like face 1| which is normally pressed against the seat 61 by the helical spring I2 which is seatedat its rear end upon the backing plate 13 which is threadedly engaged with the casing portion 56. A bolt I4 serves to hold the soft face II in place and, as will be seen, subsequently it also serves as a contacting means for moving the valve 69 in opposition to the spring 12. A valve stem, generally designated 16, operatively engaged with the main inlet valve 69 comprises in this instance three assembled parts: the extension II which may or may not be integral with the disk 69 as shown; the tubular member I8 having one end threadedly engaged with the extension 11 and the other end flanges at I9 for engagement with the pilot valve toggle 8|; and the rod 82 having one end fastened .within the tube I8 by pin or rivet 83 and the other end attached loosely to the armature 84 by flaring the end of rod 82, as at 86. An annular, flexible diaphragm 81 of metal or rubber-like material which separates the main inlet valve inlet chamber 88 from the pilot valve chamber 89, has its inner periphery compressibly interposed between the valve stem portions '11 and I8 and has its outer periphery compressibly interposed between the backing plate I3 and the casing portion 56. A U-shaped electromagnet 9| is mounted by means of a rivet 92 onto a plate 93 which presses the gasket 94 against the inner end' surface of the casing portion 56. The plate 93 has an axial portion 96 extending through the casing end portion opening 91 and is threadedly engaged with the lock nut 98 which holds it in place. The plate extension 96 is internally threaded at 99 to receive an inner lock nut I04 which serves to hold in place the connector I06 which conveys the current generated in thermocouple 4Ia through the electromagnet coil I02 when the thermocouple 4 la is heated by the flame of the pilot burner 39. A cup-shaped member I 01 formed-of sheet metal, attached at one end to the plate 93 and apertured and fitted with the stufling retainer I08 at the other end, prevents the entrance of substantial-amounts of moisture or dust or other gas-carried foreign material into the electromagnet chamber I09.

The main outlet valve III-is engageable with the seat 68 to start and stop the flow of gas to the oven burner through line 28. It is fitted with a leather-like disk II2 held in place by lock nut H3 and is normally held in the open position by helical spring I I4 which seats at one end against the valve flange I I6 and at the other end against the casing.

The valve stem III, with which the main outlet valve I II is associated, is an assembly of the following four parts: the rod II8 which is reciprocably engaged within the bore II 9 formed 3 in the valve threaded extension I 2I; the extension I22, threaded onto one end of the rod II8; the coupling I23 threaded onto the other end of the rod H8, and the rod I 24 threaded into the other end of the coupling I23. The extension I22 carries a flange I26 which is engageable with the sub-burner valve toggle I21 and is of sufficient length that when moved to its innermost position it engages the bolt head I4 and opens the main inlet valve 69. The rod H8 is provided with a shoulder I28 and a spring I29 bears at one end on one side of the shoulder I 28 and at the other end upon an inner surface of the valve extension I2I. The other side of the shoulder I28 has, interposed between it and the coupling I23, the inner periphery of an annular diaphragm I3I, the outer periphery being mounted between the ring I32 and the valve flange I I6, as by means of screws (not shown). The purpose of the diaphragm I3I is to prevent the flow of gas between the chambers I33 and I34 through the valve bore II9 when the valve is in the closed position, as shown in Fig. 4, thereby preventing leakage of gas .to the oven burner 32 during the initial part of the lighting operation before the pilot burner 39 is ignited. The rod I24 is likewise formed with a shoulder I36 having, interposed between itself and the coupling 123, the inner periphery of the diaphragm I3'I, the outer periphery of which is compressed between threaded plate I38 and the casing 51. The shoulder serves, further, to limit outward movement of the rod I24 and the parts mounted on it. The diaphragm I31 functions to prevent the leakage of gas from chamber I34 through the plate bore I39. The end portion of the rod I24 is formed with an outwardly facing shoulder I4I for carrying the armature I42 and has a reduced extension I43 reciprocable within the armature bore I44. A flanged bell housing I46 is mounted on the flange I4I of the casing as by means of screws (not shown) and has at its end an axial opening I48 within which is engaged the end of an operating rod I49, which, in turn, is threadedly engagedwith the operating shaft I03. The operating rod I 49 is flanged at I5I for the dual purpose of retaining it within the housing I46 and for providing a bearing for the spiral spring I 53, the other end of which bears against the armature. The rod reduced extension I 43 is reciprocably engaged within the bore I54 so that the operating rod I49 can push the entire assembly to its inwardlimit and then be moved back to its initial position without drawing the rod I24 or the armature I42 back with it.

A U-shaped magnetically permeable electromagnetic core I56, together with a terminal bracket 157 and a pair of permanent bar magnets I58, is mounted on a base plate I59 by means of a rivet I6I, the latter being hollow for the passage of valve stem rod I24. The bracket I51 has a right angled portion I62 upon which is mounted a terminal or connector I63 for the thermocouple lead 42 which energizes the coil I when the thermocouple 4I is heated. The positioning of the permanent magnets I58 is such that when the coil I00 is non-energized the flux of the permanent magnet will permeate the U-shaped core I56 and induce magnetism in it suflicient to hold the armature I42 when the latter is pressed against it, as shown in Fig. 4. The coil I00 is wound so as to set up magnetic flux in opposition to the permanent magnet so that as the thermocouple 4! is heated by the pilot burner 39 during the lighting cycle the current in the electromagnetic coil I00 will neutralize the induced magnetism in the U-shaped core I56 and, therefore, neutralize the magnetic attraction exerted on the armature I42, to the extent that the armature I42 will be released and pressed to the Fig. 5 position by Spring I I4.

The core I56 is spaced from the permanent magnets I58 by a spacer I64 which may be any non-magnetic material, such as brass, aluminum, fiber, etc. This is preferred to minimize the demagnetizing effect of the thermocouple current on the permanent magnets and also to regulate the intensity of the induced magnetism to any preferred value.

In the present instance, the auxiliary valves I66 and IBM, controlling the flow of gas to the sub-burner 36 and oven pilot burner 39 respectively, constitute leather-like seat contacting members I61 and I 61a and are normally closed by springs I68 and I 68a. Screwed caps I69 and I 6911 provide access for assembly and disassembly.

The provision of supply lines SI and 5Ia for the oven pilot burner 39 forms the subject matter of copending application Serial No. 677,137, filed June 17, 1946. During normal baking operation, the pilot burner 39 will be supplied by both lines SI and 5I a and will support a flame large enough to heat the thermocouples 4| and Ma and energize, respectively, the electromagnet coils I00 and I02. When the control knob 49 is turned back to the oil position, as at the end of the baking period, the oven pilot burner will be supplied only through line 5I and the flow therethrough will be regulated by throttling valve 52 at a rate small enough to support only a small bead of flame which is out of contact with the thermocouples, thereby allowing them to cool. This is a safety feature providing a temporary bead flame to re-ignite the oven burner in case the housewife decides to relight the oven a few seconds after turning it off and sooner than the thermocouple Me has cooled sufficiently to release the armature 84 and allow the main inlet valve 69 to be closed under the urgence of spring 12. When the main inlet valve is closed in this mannor, the pilot valve I66a will likewise be closed under the urgence of its spring IBM to shut oil further flow of gas to the oven pilot burner which will then be extinguished entirely and use no further amount of gas until the oven is again turned on.

As shown in the modified form in Figs. 6 and 7, the front electromagnet which is associated with the permanent magnet need not necessarily have a U-shaped core. It may, for example, com- 8 prise a pair of separate-core bars I56a wound by coils I00a and mounted on a non-magnetic plate "I and spaced a distance A from the permanent magnets I58 which are likewise mounted on the plate Ill. The spacing A in this case is an air gap and serves the same purpose as the non-magnetic spacer I64 shown in the previous figures, namely, to prevent the permanent demagnetization of the permanent magnets I58 to any substantial extent by the current in the thermocouple circuit as well a to control the'extent of the magnetism induced in the bars I56a. The coil IIII'Ia will be wound to oppose the magnetism induced in the core bars I56a by the permanent magnets, so that when the armature I42 ismagnetically attracted to the bars I56a it will be released by thermocouple current flowing through the coils. One advantage of employing the core member in two separate pieces at the ends of the permanent magnet I58 as shown in Figs. 6 and 7, is that minimum sized permanent magnets may be used, for none of the available magnetic flux will be short-circuited through the base of the core, as will occur to a certain extent in the U-shaped modification. When the armature I42 is placed upon the core bars I56a, in the absence of thermocouple current flowing through the coils I00a, the magnetic circuit will be a substantially closed one (except for the spacing A), consisting of the permanent magnet, the core bars, and the armature.

While the particular thermoelectric generating means shown comprises a pair of thermocouples M and M a, a single thermocouple may be used in some cases, as where the total current requirement of both electromagnet coils I00 and I02 is very small. In other cases, where relatively large currents are required, with a single source, a thermopile with any desired number of junctions may be employed,

Operation In considering the operation of the present invention, assume, for example, that the oven is cold and the housewife desires to light it.- She does this simply by depressin and turning the control knob 49 to the proper temperature setting. The lighting operation itself will be carried on from there automatically by the abovementioned apparatus without further thought or action by the housewife.

As shown in Patent 2,303,011, granted November 24, 1942, where thestructure of the control knob 49 and temperature regulator 22 is described in detail, the control knob cannot be rotated without first depressing it. This is a safety feature which is preferred by many people to prevent the oven from being inadvertently turned on and also to make is diflicult for very small children to operate it.

In the Figure 1 and 2 position, which is prior to turning the knob to light the oven, the flow of gas into the main supply line 26 and pilot supply line 5Ia will be positively shut off by the plu valve 25 which is incorporated in the temperature control casing; and flow to the oven pilot burner through the pilot supply line 5| will be shut oil by the pilot valve IBBa, which is closed.

The first operation in turning the knob then will be to push it inwardly, thereby depressing the operating shaft I03. This will move the armature I42 into abutment with the electromagnet core I56 which will be magnetized by the permanent magnets I56 sufiiciently that the armature will be held in the position shown in Fig. 4 where the oven burner valve III is pressed against the seat 68 and the other three valves 69, I 66, I661: are held in an open position against the opposing forces exerted by the springs 12, I63, and IBM respectively. At this time the rear armature 34 will be pressed against its electromagnet core 9|, but it will not be held thereby magnetic force as yet because the thermocouple Ma has not yet been heated.

As soon as the valves are moved to the Fig. 4 position to initiate the lighting operation, gas will fiow through the regulator 22, main supply line 26, sub-burner valve I66, and line 33, to the sub-burner 36, where it will issue through the ports 31 into the flashtube 41 together with primary and secondary air drawn through the mixing tube 34 and the space I56 beneath the mixil'lg tube I59. At the same time, gas will flow from lines 5| and 5Ia into line 53, through pilot valve I66. .1, line 54 and passage I48 to the pilot burner 39. A portion of the pilot valve stream will issue through a side jet (not shown) and flow into one end of the auxiliary flash passage 48. When the gas passing upward through subburner jets 31 into the flash tube 41 emerges in the constantly burning top pilot 43 it will be ignited and will flash back, first, to the sub-burner, ghen to the pilot burner 39, through the passage As soon as the pilot burner 39 is ignited, it will burn with a flame supplied through both tubes 5| and SI a and will preferably impinge directly upon both thermocouples M and Ala. Electrical current will then be generated by the thermocouples and will flow to their respective electromagnet coils. The current generated by thermocouple 4| will reach a point where it will neutralize the holding efiect of the permanent magnets I58 and cause the armature I 42 to be released. This will open the main oven burner valve III and close the sub-burner valve I66. Valves 69 and H361; will be held open by the magnetic attraction of armature 84 to the electromagnet 9I which is energized by the hot thermocouple Ma.

The valves will now be in the baking position shown in Fig. 5 wherein gas is allowed to flow through the main supply line 28 to the burner 32 and will be ignited by the oven pilot burner 39. The sub-burner 36 will have been extinguished by the closing of the sub-burner valve I 66. The lighting operation will now be completed and the oven temperature will be maintained at the desired setting by the heat regulator 22 throughout the baking period.

At the conclusion of the baking period the oven is turned off simply by turning the control knob back to the off or zero position. The fiow of gas through the regulator will at once be shut off by the closing of 'plug 25 which will extinguish the main oven burner flame. It will also shut ofi that portion of the pilot burner gas supplied through line 5Ia so that only a head of flame, out of impingement with the thermocouples, is maintained and is supplied through line 5| directly from the manifold 2 I. Pilot valve I66a will still be held open to permit the passage of this bead supply for a few seconds until thermocouple Ila cools sufiiciently to release armature 84 and allow the pilot valve I66a as well as the main valve 69 to be closed under the urgence of springs I68a and I2, respectively. The existence of this head flame in lighting proximity to the oven burner 32 until thermocouple 4Ia cools sufllcientlyto permit the main valve 69 to close is an important safety feature, which permits the oven to be relighted immediately after it has been turned oil. Assume that it is desired to re-light the oven burner 32 before the thermocouple 4Ia has cooled sufficiently to release the armature 84. As above described the pilot valve I66a is maintained in. an open position so thatthe oven pilot burner 39 continues to burn The housewife on turning the knob 49 to re-ignite the oven burner 32 causes gas to fiow from the manifold 2| through the valve 69 which is held in an open position, the valve III which is in the open position, through the line 28 to the oven burner 32. Gas issuing from the oven burner 32 will be ignited from the oven pilot burner 39 and the oven is againready for use.

While particular forms of the present invention "have been shown and described, it will be apparent that minor changes therein will readily suggest themselves to others skilled in the art without departing from the spirit and scope of the invention. Having thus described the invention, what isclaimed as new is:

1. In an oven lighting system for a gas stove or range, the combination of, an oven burner connected to a gas supply, an oven pilot burner connected to a gas supply, a constantly burning pilot burner in spaced relation to the oven pilot burner, means for lighting said oven pilot burner from said constantly burning pilot burner, a valve for controlling the flow of gas to said oven burner having an open and a closed position, manual means for positioning said valve in the closed position, permanent magnet means for holding the oven burner valve in the closed position, means responsive to the heat of said oven pilot burner for neutralizing the effect of said permanent magnet when said ovenrpilot burner is lighted, and means for urging said valve to the open position whereby gas flows to said oven burner.

2. In an oven lighting'system for a gas stove or range, the combination of, an oven burner arranged to be connected to a gas supply, an oven pilot burner for lighting said oven burner, means for lighting said oven pilot burner, a first valve having an open and a closed position for controlling the flow of gas to said oven burner, means for moving said first valve to the closed position, a second valve for controlling the flow of gas to said oven pilot burner and having an open and a closed position, means acting between said first and second valves for moving said second valve from its closed to, its open position in re sponse to movement of the first valve from its open to its closed position, permanent magnet meansior holding the first valve in the closed position and the second valve in the open position for a limited period of time after the @VGII pilot burner is lighted, means responsive to the heat of said pilot burner for neutralizing said permanent magnet when said oven pilot burner is lighted and holding said second valve in its open position, and means for opening said first valve to supply gas to said oven burner when said permanent magnet is neutralized.

3. An oven lighting system for a gas stove or range having in combination, an oven burner arranged to be connected to a gas supply, an

oven pilot burner for ignitin said oven burner, a constantly burning pilot burner, flash-back means for igniting said oven pilot burner from said constantly burning pilot burner, valve means for controlling the flow of gas to said oven burner and having an armature of magnetic material, said valve means having an open and a closed position, a permanent magnet for attracting said armature to maintain said oven burner valve means in its closed position, control means for moving said armature to a position whereby the attractive force between the magnet and the armature maintains the valve in its closed position, an electromagnet disposed adjacent said magnet and arranged to neutralize the magnetic force of said magnet, a thermocouple disposed adjacent said oven pilot burner and capable when heated to a predetermined temperature of producing a current for energizing said electromagnet to neutralize the attractive force of said permanentmagnet, and means for moving said valve to the open position when said permanent magnet is neutralized whereby to supply gas to said oven burner.

4. The combination as recited in claim 3 wherein the electromagnet includes a core comprising a U-shaped soft iron member that is readily permeable by the flux of said permanent magnet and said permanent magnet is spaced from the bridging portion of the U-shaped memher.

5. The combination as recited in claim 3 wherein the electromagnet includes a core comprising a pair of spaced parallel bars and said permanent magnet is positioned across one end of said pair of bars, the other end of said pair of bars being engageable by said armature to form a magnetic circuit comprising the permanent magnet, the bars, and the armature.

6. An oven lighting system for a gas stove or range having in combination, an oven burner adapted to be connected to a gas supply, an oven pilot burner for lighting said oven burner, a constantly burning pilot burner, means for igniting said pilot burner by flash propa ation from said constantly burning pilot burner, valve means for controlling the flow of gas to said oven burner having an open position wherein gas flows to said oven burner and a closed position, means for urging said valve from the open position to the closed position and from a closed to an open position, said valve means having an armature of magnetic material, a core of magnetizable material positioned to be engaged by said armature when said valve means is in the closed position, a permanent magnet operatively associated with said core to magnetize it to the extent that it attracts said armature and holds said valve means in the closed position, a coil encircling said core to form an electromagnet, a thermoelectrical generating means connected to said coil and responsive to the heat of said pilot burner for neutralizing the magnetism in said core induced by said permanent magnet whereby said valve moves to the open position.

7. The combination recited in claim 6 wherein the core and permanent magnet are spaced from one another to an extent suflicient to prevent substantial permanent demagnetization of said permanent magnet by said electromagnet coil.

8. An oven lighting system for a gas stove or range having in combination an oven burner arranged to be connected to a gas supply, an oven pilot burner, a constantly burning pilot burner, means for igniting said oven pilot burner by flash propagation from said constantly burning pilot burner, valve means having an open and a closed position for controlling the flow of gas to said oven burner, biasing means for normally holding said valve means in the open position, control means for moving said valve means to the closed position, means for holding said valve means in the closed position for a limited period after said pilot burner is ignited, and means responsive to the heat of said pilot burner including an electromagnet for counteracting said holdin means when said oven pilot burner is ignited whereby said valve means moves to the open position to supply said oven burner with gas.

9. In an oven lighting system for a gas stove or range, the combination of, a constantly burning pilot burner, an oven burner adapted to be connected to a. gas supply, a first valve for controlling the iiow of gas to the oven burner having an open and a closed position, means for biasing said valve to the open position, a subburner, a second valve for controlling the flow of gas to the sub-burner having an open and a closed position, means for biasing said valve to the closed position, a main inlet valve for controlling the fiow of gas to said first valve and said second valve and having an open position and a closed position, means for biasing said main inlet valve to the closed position, an oven pilot burner for lighting the oven burner, a third valve for controlling the flow of gas to the oven pilot burner having an open and a closed position, means for biasing said third valve to the closed position, said first valve shaped to control said main inlet valve, said second valve and said third valve, means for moving said first valve to the closed position whereby said second valve, said main valve and said third valve respectively move to their open position, a permanent magnet operatively associated with said first valve for holding it in the closed position, flash-back means for lighting the sub-burner from the constantly burning pilot burner and the oven pilot burner from the sub-burner, an electromagnet operatively associated with said permanent magnet, a thermocouple connected to the electromagnet and disposed in the flame of said oven pilot burner, said thermocouple ar-- ranged to generate a current to be supplied to said electromagnet for neutralizing the force of said permanent magnet whereby said first valve moves to the open position and said second valve moves to the closed position, and means for holding said main inlet valve and said third valve in their open position whereby gas fiows to said oven burner and said pilot burner.

10. In an oven lighting system for a gas stove or range, the combination of, a constantly burning pilot burner, an oven burner adapted to be connected to a gas supply, a first valve for controlling the fiow of gas to the oven burner having an open and a closed position, means for biasing said valve to the open position, a subburner, a second valve for controlling the flow of gas to the sub-burner having an open and a closed position, means for biasing said second valve to the closed position, a main inlet valve r' for controlling the fiow of gas to said first valve and said second valve and having an open position and a closed position, means for biasing said main inlet valve to the closed position, an oven pilot burner for lighting the oven burner, a third valve for controlling the flow of gas to the oven pilot burner having an open and a closed position, means for biasing said third valve to the closed position, said first valve controlling the movement of said main inlet valve, said second valve and said third valve, means for moving said first valve to the closed position whereby said second valve, said main valve and said third valve respectively move to their open position, a permanent magnet operatively associated with said first valve for holdingit in the closed position, flash-back means for lighting the subburner from the constantly burning pilot burner and the oven pilot burner from the sub-burner,

,an electromagnet operatively associated with said permanent magnet, a first thermocouple connected to the electromagnet and disposed in 11. In an oven lighting system for a gas stove or range, the combination of, a constantly burning pilot burner, an oven burner adapted to be connected to a gas supply, a first valve for controlling the fiow of gas to the oven burner having an open and a closed position, means for biasing said valve to the open position, a subburner, a second valve for controlling the flow of gas to the sub-burner having an open and a closed position, means for biasing said second valve to the closed position, a main inlet valve for controlling the flow of gas to said first valve and said second valve and having an open position and a closed position, means for biasing said main inlet valve to the closed position, an oven pilot burner for lighting the oven burner, a third valve for controlling the flow of gas to the oven pilot burner having an open and a closed position, means for biasing said third valve to the closed position, said first valve controlling the movement of said main inlet valve, said second valve and said third valve, means for moving said first valve to the closed position whereby said second valve, said main valve and said third valve respectively move to their open position,

a permanent magnet operatively associated with said first valve for holding it in the closed position, flash-back means for lighting the subburner and the oven pilot burner from the constantly burning pilot burner, an electromagnet operatively associated with said permanent magnet, a thermal responsive means connected to 14 means for biasing said valve to the open position. a sub-burner, a second valve for controlling the flow of gas to the sub-burner having an open and a closed position, the closed position. a main inlet valve for controlling the flow of gas to said first valve and said second valve and having an open position and a closed position, means for biasing said main inlet valve to the closed position, an ovenpilot burner for lighting the oven burner, a third valve for controlling the flow of gas to the oven pilot burner having an open and a closed position, means for biasing said third valve to the closed position, said first valve controlling the movement of said main inlet valve, said second valve and said third valve, means for moving said first valve to the closed position whereby said second valve, said main valve and said third valve respectively move to their open position, a permanent magnet operatively associated with said first valve for holding it in the closed position, first flash-back means for lighting the sub-burner from the constantly burning pilot burner, second flash-back means for lighting the oven pilot burner from the sub-burner, an electromagnet operatively associated with said permanent magnet, a thermocouple connected to the electromagnet and disposed in the flame of said oven pilot burner, said thermocouple arranged to generate a current to be supplied to said electromagnet for neutralizing the force of said permanent magnet whereby said first valve moves to the open position and said second valve moves to the closed position, and means responsive to the heat of the flame of said oven pilot burner'for holding said main inlet valve and said third valve in their open position whereby gas flows to said oven burner and said pilot burner.

13. In an oven lighting system for a gas stove orrange, the combination of, an oven burner arranged to be connected to a gas supply, an oven pilot burner for lighting said oven burner, a constantly burning pilot burner, means for lighting said oven pilot burner from said constantly burning pilot burner, a first valve having an open and a closed position for controlling the flow of gas to said oven burner, means for moving said valve from the open to the closed position, resilient means for urging said valve to the open position,

a magnetizable armature connected to said valve and movable between preselected positions, a

the electromagnet and disposed in the flame of said oven pilot burner, said thermal responsive means arranged to generate a current to be supplied to said electromagnet for neutralizing the force of said permanent magnet whereby said first valve moves to the open position and the second valve to its closed position, and means for holding said main inlet valve and said third valve in their open position whereby gas flows to said oven burner and said pilot burner including a second electromagnet adapted to be under the control of said thermal responsive means.

'12. In an oven lighting system for a gas stove or range, the combination of, a constantly burning pilot burner, an oven burner adapted to be connected to a gas supply, a heat control unit having a manual control unit, a first valve positioned to be actuated by said control unit for controlling the fiow of gas to the oven burner and said valve having an open and a closed position,

magnetizable core mounted to maintain said armature in one of said positions by magnetic attraction, a permanent magnet operatively associated with said core for inducing magnetism in said core to hold said armature in one position against the action of said means for urging the valve to the open position, means for controlling the induced magnetism in said core by the permanent magnet, a coil operatively associated with said -core, electric generating means connected to said coil and responsive to a predetermined condition of said oven pilot burner for producing a current to flow through said coil to neutralize the magnetism induced in said core by said permanent magnet whereby said armature moves to its other position and the valve moves to the open position.

14. The combination recited in claim 13 in which said means for controlling the extent of the magnetism induced in said core by said permanent magnet comprises an air gap betweenthe core and the magnet. I

15. The combination recited in claim 13 in which the means for regulating the extent of the means forbiasing said valve to magnetism induced in the core by the permanent magnet comprises non-magnetic material interposed between the core and the permanent magnet.

16. In a lighting system for a gas stove or range, the combination of, a burner connected o a gas supply, a pilot burner in lighting proximity with said burner, a valve for controlling the flow of gas to said burner having an open and a closed position, means for positioning said valve in the closed position, permanent magnet means for holding the valve in the closed position, means responsive to the heat of said pilot burner for neutralizing the eiTect of said permanent magnet when said pilot burner is lighted, and means for urging said valve to the open position whereby gas flows to said burner.

17. An oven lighting system tor a gas stove or range having in combination, an oven burner arranged to be connected to a gas supply, an oven pilot burner, a constantly burning pilot burner, means for igniting said oven pilot burner by flash propagation from said constantly burning pilot burner, valve means having an open and a closed position for controlling the flow of gas to said oven burner, biasing means for normally holding said valve means in the open position, control means for moving said valve means to the closed position, magnetic means for holding said valve means in the closed position for a limited period of time after the pilot burner is ignited, and means including an electromagnet for counteracting said latter means when said oven pilot burner is ignited whereby said valve means moves to the open position to supply said oven burner with gas.

18. In a main burner lighting system for a gas range, the combination of a main burner arranged to be connected to a gas supply, ignition means for lighting said main burner, valve means for controlling the flow of gas to said burner having an open and a closed position, means for moving said valve to its closed position, permanent magnet means for holding the valve means in its closed position, means responsive to the heat of said ignition means for neutralizing the effect of said permanent magnet means when said ignition means is operative for lighting said main burner, and means for urging said valve to its open position upon neutralization of said permanent magnet means to cause gas to flow to said burner.

VICTOR R. ABRAMS. PETER I. HOLLMAN.

REFERENCES CITED The following references are of record in the Weber et a1. Dec. 7, 1948