US2637390A

US2637390A - Automatic ignition and control mechanism for oven burners

Info

Publication number: US2637390A
Application number: US260906A
Authority: US
Inventors: Richard L Perl; John M Hoff
Original assignee: TAPPAN STOVE CO
Current assignee: TAPPAN STOVE Co
Priority date: 1951-12-10
Filing date: 1951-12-10
Publication date: 1953-05-05
Anticipated expiration: 1970-05-05

Description

May 5, 1953 w l 3 a 7 m 3 s 6 .v 2 a m S 3 R. L. PERL ETAL AUTOMATIC IGNITION AND CONTROL MECHANISM FOR OVEN BURNERS Filed Dec. 10, 1951 INVENTORS RZC/7CZ/"d L Per/ BY 9J0/m M. Hoff May 5, 1953 R. L. PERL ETAL 2,637,390

- AUTOMATIC IGNITION AND CONTROL MECHANISM FOR OVEN BURNERS Filed Dec. 10, 1951 4 v5 Sheets-Sheet 2 i Qawzzzd! 1N VEN TORS Fiona/d1. Per/ BY 9J0/1r7 N. H077 44M. wt'wmb y 1953 R. PERL EI'AL 2,637,390

- AUTOMATIC IGNITION AND CONTROL MECHANISM FOR OVEN BURNERS Filed Dec. 10, 1951 5 Sheets-Sheet 5 lfi 2/ 5 a M 93 /4- um INVENTORS Pic/lard 1.. Perl gal/0hr? M. Hoff .wfi I 6??? not the main burner burns constantly.

Patented May 5, 1953 UNITED STATES PATENT OFFICE Richard L. Perl, Galion, and John Hoff, Mansfield, Ohio, assignors to The Tappan Stove Company, Mansfield, Ohio, a corporation of Ohio Application December 10, 1951, Serial No. 260,906

26 Claims.

This invention relates to an automatic elec tric ignition and control mechanism for cooking range burners using gaseous iuel and is a modification of the control mechanisms shown in the co-pendin'g applications of Charles M. Mayer and John M. Hoff filed April 3, 1950, Serial No. 153,664- new Patent No. 2,577,787, and our co-pending application, Serial No. 269,356, filed February 1, 1952. 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 burnerwhich is adapted to be ignited by a gaseous fuel pilot burner. As long as the pilot burner is ignited it is immaterial whether or 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 new 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 sometimes 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, we provide in our improved apparatus a safety control unit by which the supply of gas to both the main burner and the pilot burner is completely out off, in the event the pilot burner is extinguished for any reason during operation.

Our improved apparatus includes a main gaseous fuel burner by which the oven in a cool:- ing 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 2 conduit between the gas supply manifold and the main b'u'rner. During operation gas flows from the manifold into a safety control unit. From the safety control unit gas flows through a 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. The energization of the solenoid transformer causes it to set the safety control unit to permit the flow of gas from the safety eontro1 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 (is-energized the safety control unit is automatically operated by spring means to 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 extinguished for any reason the thermocouple will immediately cool and allow the safety control unit to automatically cut off the supply of gas to both the main burner and the pilot burner. A 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 off com munication 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 of the 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 reignited and re-establish normal operation of the oven as previously described.

When it is desired to use the apparatus in conjunction with any standard time control mechanism, we provide a normally closed supplemental control switch which is disposed 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 used the time control mechanism is set to initiate operation of the oven burner at a predetermined time and to terminate operation thereof at a predetermined later time which will open the normally closed supplemental control switch. The main control valve is 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 to terminate operation. The opening of the supplemental control switch will cause the safety control unit to cut off the supply of gas to both the 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 pilot burner with a match, We 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 opening and closing of the main control valve.

The principal 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 means for completely shutting off the supply of gas to both the main burner and the pilot burner in the event the pilot iii 4 burner becomes extinguished for any 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 is turned on or to burn constantly if desired.

Another object of the invention is to provide in an automatic 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.

Still another object of the invention is to provide an improved electrical ignition and control system of the character described which may be used in 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 accompanyingdrawing forming a partthereof, wherein:

Fig. l is a diagrammatic layout showing our improved electrical ignition and safety control mechanism applied to a cooking range oven burner using 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 is a view similar to Fig. 2 showing the various parts in the position they are automatically moved to when the master control switch is closed to initiate the operation of the main oven burner; and

Fig. 4 is a wiring diagram of the apparatus.

Referring now to the drawings by reference characters, the numeral I indicates a aseous 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 M through a conduit 3. Interposed in the conduit 3 are a safety control valve mechanism generally indicated by the numeral 4, a manually operable main control valve 5, and an oven temperature control valve 6. During operation gas flows from the manifold M through the conduit 3 to the safety control unit 6, to be described in detail hereinafter. From the safety control unit 4 the gas flows 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 amount of gas flowing to the burner 1 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 l having a pointer 8 which cooperates with a graduated dial 9 carried by the valve 6. The valve 6 is controlled according to the temperature setting by a thermostatic element Hi which is mounted in the oven 2 and is connected to the valve 8 as shown at l I. The main control valve 5 is a standard shut off valve which is manually opened and closed by a-handle l2 and a valve stem [3. 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 off 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

a caaeoo is also supplied to a pilot burner i4 through a branch conduit l5 which extends between the safety -'control valve mechanism t and the pilot "burner 14. The pilot burner I4 is disposed adja'cent the rear end of the main burner i in position to ignite the burner -I when gas is supplied thereto. An electrical ignition element It is operatively' associated with. the pilot burner I l in position to ignite the pilot burner ill when gas is supplied thereto. A. thermostatic element H and a multiple thermocouple it are mounted in position to be heated by a name from the pilot burner. The thermostatic element i'l' is opera-- tive to open and close a switch it which controls the energization of electrical ignition element It and a solenoid transformer Zll which when energized operates the safety control unit to supply gas to the pilot burner l 4 only as will be described in connection with the description of the safety control unit and the operation of the whole apparatus. The thermocouple 18, when heated, is operative to hold the safety control unit in condition to maintain the supply of gas to both the pilot burner Hi and the main burner l, as will also be described in connection with the description of the safety control valve mechanism and the operation of the apparatus. An electric circuit between the thermocouple ill and the safety control unit 4 is established by a copper tube 2| and an insulated wire 22 within the tube 2!.

A master control switch 23 and an interrupter sw' ch 24 which cooperate with each other and with the main control valve ii 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 12, through a link 25. The arrangement is such that the switch 23 is simultaneously closed with the opening of the main control valve ll, and is simultaneously opened with the closing of the valve The interrupter switch A l is interposed in the thermocouple circuit as shown in Fig. 4. It is normally open and is arranged to be maintained closed by a relay 2i 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 t and its connection to the solenoid transformer Ell will now be described. reference being bad to Figs. 2 and 3, of the drawings. This unit comprises a casing having a chamber 35 in one end thereof and a chamber 37 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 at is located at the other end of the bore 38. The chamber at is closed by a removable cap 4! and the chamber 31 is closed by a removable cap 42. A sleeve 43, having end walls 4 5 and 45, is carried by the cap 4| and extends into the chamber 3%. A valve stem M which is slidably mounted in a bushing l-i carried by the end wall of the sleeve 43, extends from the chamber 35 into the sleeve 43. A control valve 48 of suitable material is secured to one end of the valve stem 45 Within the chamber 36, and an armature 49 is secured to the other end of the stem 46 within the sleeve M. A spring 58 disposed about the valve stem ie between the control valve 48 and the end wall 45 of the sleeve it normally holds the control valve 48 against the valve seat 39. An electromagnet 5| is secured to one end f a hollow exteriorly threaded stud 52 which extends out through aligned apertures in the end wall 44', of the sleeve 43, and in the end of the cap 41. A not 53 screwed onto the outer portion of the stud 52 securely holds the magnet 5| and the sleeve 43 in place. The legs of the magnet 51 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 2i. The tube 21 is insorted into the hollow stud 52 and is held 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 37 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 stem which is secured to the inner end of the plunger 59, extends out through an aperture 53 in the end wall t! of the sleeve 55, and through the chamber at and into the bore 38. The stem s2 has a collar Ell rigidly secured thereon between the end wall 5! and the outer end of the stem. An interrupter valve 55 of suitable material is slidably mounted upon the stem 62 between the end wall 51 of the sleeve 55 and the collar M. The interrupter valve is adapted to engage the valve seat lll to out off the flow of gas into the chamber 37 during the initiation of operation as will be hereinafter described. A compression spring 56 disposed about the stem E52 between the end wall 5'! and the valve 65 normally yieldingly holds the valve 65 against the collar M. A compression spring e1 which is stronger than the spring 65 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 chain'- ber 36. During normal operation of the main burner i gas flows from the chamber 3% through the reduced intermediate bore as and into the chamber 31. A port 59 which establishes communication between the branch conduit 15 and the bore 33 is provided to supply gas tothe pilot burner l4; and a port ll) establishes communication between the chamber 3'! and the conduit 3 to permit the fiow of gas from the chamber 3? to the main burner 1 through the main control valve 5 and the oven temperature control valve 6.

The solenoid transformer 20 comprises a spool '15 on which are wound the primary winding it and the secondary winding ll. An armature it is slidably mounted in the bore ill of the spool 'iii. The solenoid transformer 26 may he oporatively associated with the safety control unit l in any suitable manner. As shown herein it is secured to the cap 42 of the safety control unit 6i, with the armature 78 thereof in axial alignment with the plunger 59 of the safety control unit l.

In order to accommodate the apparatus for automatic control whereby operation of the main oven burner i may be automatically initiated at a predetermined set time and automatically terminated at a, predetermined set later time, we provide a normally closed supplemental master switch 85 which is adapted to be opened and closed by a standard time control mechanism 86.

The operation of the apparatus will now be described, particular reference being had to Fig. 4 of the drawings. For manual control it is only necessary to manually open the main control valve 5 and close the master switch 23 to initiate operation, and then manually close the main control valve 5 and open the master switch 23 to terminate operation. When the switch 23 is closed current will flow from one side 90 of the line through the lead 9| to the switch 23, thence through the switch 23 and lead 92 to the normally closed thermally opened switch 19. ihe current then flows through the switch l9 and lead 93 to the primary winding 16 of the solenoid transformer 29 and from there back to the other side 94 of the line through the lead 95. The relay 2! is connected to the

leads

92 and 95 between the switches 23 and i9 by the leads 92a and 95a 50 that it will always be energized when the master switch 23 is closed. The solenoid transformer Eli and the relay 2? are now energized, and the electric ignition element i9, which is connected to the secondary winding ll of the solenoid transformer by the leads 95 and 9? is also energized. The relay 2? being energized closes the switch 24 in the thermocouple circuit and the solenoid transformer ll being energized shifts the various parts of the safety control unit from the positions shown in Fig. 2 to the position shown in Fig. 3. Gas can now flow to the pilot burner M where it is ignited by the ignition element 16, but gas cannot yet flow to the main burner I since the interrupter valvernechanism in the chamber 31 of the safety control unit is maintaining the entrance thereto closed. The pilot burner being ignited heats the thermo couple l3 and the thermal element ll. The

thermocouple being heated generates a minute current of the order of 200 to 250 millivolts which flows from the thermocouple through the tube 2! to the winding 54 of the electromagnet 5i and from there through the wire 22 and switch 24 back to the thermocouple l8. current energizes the electromagnet 5i sufficiently for it to hold the control valve mechanism in the chamber 36 in the position shown in Fig. 3 after it has been moved to this position by the solenoid transformer 2s, but not enough for the electromagnet to attract the mechanism from the position shown in Fig. 2 to the position shown in Fig. 3. The heating of the thermal element ll causes it to open the normally closed switch 59 which breaks the circuit to and de-energizes the solenoid transformer 28 and consequently the electric ignition element l6. As soon as the solenoid transformer is de-energized the spring 67 returns the interrupter valve mechanism in the chamber 37 back from the position shown in Fig. 3 to the position shown in Fig. 2 while the electromagnet 5i holds the control valve mechanism in the chamber 36 in the position shown in Fig. 3. Gas can now flow through the main control valve 5 to the main burner l where it is ignited by the pilot burner I 4. Under normal conditions the burner I will now operate under control of the oven temperature control valve 6 until its operation is terminated by the opening of the switch 23 and the simultaneous closing of the valve 5. The closing of the manually operable valve 5 cuts off the flow of gas from the control unit 4 to the main burner I, but it does not cut ofi the flow of gas to the pilot burner 14. This is efiected by the The thermocouple opening of the master control switch 23 which breaks the circuit to the relay 21 and allows the interrupter switch 24 to open. The opening of the interrupter switch 24 breaks the thermocouple circuit and tie-energizes the electromagnet 5| after which the spring 50 returns the control valve mechanism in the chamber 36 back from the position shown in Fig. 3 to the position shown in Fig. 2, thus cutting off the flow of gas from the safety control unit 4 to both the main burner and the pilot burner. If the pilot burner is extinguished for any reason during operation, then the thermocouple l8 and the thermal element I! will cool. The electromagnet 5| will then be de-energized and release the control valve mechanism in the chamber which will then be returned by the spring to the position shown in Fig. 2 cutting off the supply of gas to both the pilot burner H and the main burner I. When the thermal element H cools, which is after the thermocouple I8 has cooled, the switch! 9 will close. The apparatus will then re-cycle as described as soon as gas is available.

In order to adapt the mechanism for automatic operation of the burner i we interpose the normally closed supplemental control switch i the lead 9! in series with the main control switch 23 and provide the standard time control mechanism 86 which is operative to close and open the switch 85 at predetermined set times. During manual control of the burner I the switch 85 is maintained closed. For automatic control the time control mechanism 87 is first set to initiate operation at a predetermined time and to terminate operation at a predetermined later time. The setting of the time control 8? automatically opens the switch 85. The valve 5 is then manually opened and the switch 23 closed. The opening of the valve 5 and the closing of the switch 23 will have no effect as long as the switch 85 open since the safety control unit t is in the condition shown in Fig. 2 with the valve 43 in the chamber 38 cutting oil the flow of gas from the safety control unit A to both the main burner l and the pilot burner hl. At the set time the time control mechanism will close the switch 85 after which the mechanism will function exactly as described in connection with manual control until time to terminate operation. At the predetermined set time for terminating operation the time control mechanism 85 will open the switch 35 which will break the circuit to the rela 2'! and allow the switch 2 to open. The opening of the switch 24 in the thermocouple circuit will ole-energize the electromagnet 5! in the safety control unit 4 and release the valve 48. The spring 56 will then close the valve 48 and out 01f the flow of gas to both the main burner I and the pilot burner M. At any time thereafter the apparatus may be re-set for manual control by closing the valve 5 and switch 85 and opening the switch 23. If during automatic operation the pilot burner it 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 be repeatedly used during a prolonged power failure without the necessity of manually lighting the pilot burner i l with a match each time it is used, we 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 we connect a normally open switch I06 in parallel with the interrupter switch 24 in the thermocouple circuit by 9 the leads 1 Ill and I 82. In order to convertthe apparatus to a constantly burning pilot burner system the normally open switch W3 is closed and the safety control unit t is manually set and held in the condition shown in S, by depressing the button m3 securedto the armature is, in which condition gas can flow to the pilot burner- Hi and. be ignited by a match. The control unit must be held as shown in until the pilot burner it has heated the thermocouple id sufficiently for it to energize the electromagnet 5| after which the button its may be released. The electromagnet M will hold the control valve in the chamber 35 open as shown in Fig. 3 and the spring 67 will return the interrupter valve in the chamber 35 back to open position shown in 2. Then the operation of the burnerl ismanually controlled by the opening closing of the valve 5. Obviously the apparatus cannotbe automatically controlled by the time control mechanism 88 during a powerfailure.

From the foregoing it will be apparent to those skilled in this art that we have provided a Very simple and efficientgmechanisin for accomplishing the objects of the invention.

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

What is claimed is:

1. 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 controlunit operative to out off the supply of fuel to said main burner and said pilot burner interposed in said conduit between said main lbllll'lEI 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 de-energization to set said safety control unit in condition to also 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, 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 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 de energization 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 nor- 1'0 mally closed switch open andwhen cool to maintain said normally closed switch closed.

2. An automatic ignition and control appara tus as defined in claim 1 in which said master control switch and said shut off valve are connected together to be actuated in with each other.

3. An automatic ignition co troi apparatus as defined in claim 2 v the closing and opening of said master switch effects the closingand opening of said interrupter switch.

4. An automatic ignition and control apparatus as defined in claim v1 in which the closing and opening or" saidmaster switch eifects the closing and opening of said interrupter switch.

5'. An automatic i nition and control apparatus as defined in claim I in which a relay is disposed in series with said master switch and is operative when energized to maintain said interrupter switch closed.

6. An automatic ignition and control appara tus as. defined in claim 5 in which a time control switch is disposed in series with said master switch and said relay, and a time control mechanisrn is provided which is operative to open and close said time control switch at predetermined set times.

7. An automatic ignition and control apparatus as defined in claim 5' in which a normally open manually actuable switch disposed in parallel with said interrupter sw ch.

8. An automatic ignition controlappara tus as defined in claim 1. in which time 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 time control switch at predetermined set times.

9. An automatic ignition and control apparatus as defined in claim 8 in which means is provided by which said master switch and said shut off valve are actuated in unison.

10. An automatic ignition and control apparatus as defined in claim 8 in which means is provided which is rendered operative to close said interrupter switch by the closing of said master switch.

11. An automatic ignition'and control apparatus as defined in claim 10 in which means is provided by which said master switch and said shut ofi valve are actuated in unison.

12. 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 encr gization 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 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, 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 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 efiect de-energization of said solenoid and said electric ignition element, and means responsive to said pilot burner and operative to-maintain said normally closed switch open while said pilot burner is ignited.

13. An automatic ignition and control apparatus as defined in claim 12 in which said master control switch and said shut off valve are connected together to be actuated in unison with each other.

14. An automatic ignition and control apparatus as defined in claim 13 in which the closing and opening of said master switch effects the closing and opening of said interrupter switch.

15. An automatic ignition and control apparatus as defined in claim 12 in which the closing and opening of said master switch effects the closing and opening of said interrupter switch.

16. An automatic ignition and control apparatus as defined in claim 12 in which a relay is disposed in series with said master switch and is operative when energized to maintain said interrupter switch closed.

17. An automatic ignition and control apparatus as defined in claim 16 in which a time control switch is disposed in series with said master switch and said relay, and a time control mechanism is provided which is operative to open and close said time control switch at predetermined set times.

18. An automatic ignition and control apparatus as defined in claim 16 in which a normally open manually actuable switch is disposed in parallel with said interrupter switch.

19. An automatic ignition and control apparatus as defined in claim 12 in which a time 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 time control switch at predetermined settimes.

20. An automatic ignition and control apparatus as defined in claim 19 in which means is provided by which said master switch and said shut off valve are actuated in unison.

RICHARD L. PERL. JOHN M. HOFF.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,303,672 Wantz Dec. 1, 1942 2,353,042 Koch July 4, 1944 2,478,386 Gauger Aug. 9, 1949 2,483,191 Gauger Sept. 27, 1949 2,552,536 Mayer July 31, 1951 2,564,869 Weber Aug. 21, 1951 2,577,787 Mayer et a1 -1 Dec. 11, 1951 2,578,717 Mayer et al Dec. 18, 1951 2,578,718 Mayer Dec. 18, 1951 2,584,147 Mayer Feb. 5, 1952