US2705531A - Ignition system for multiple fuel burners - Google Patents

Description

P 1955 H. w. RICE ETAL 2,705,531

IGNITION SYSTEM FOR MULTIPLE FUEL BURNERS Filed Jan. 6, 1951 2 She'ts-Sheet 1 INVENTORS Harold Wflz'ceqzd By lbbe t C-Mauz.

THEIR ATTORNFY' April 5, 1955 H. w. RICE ETAL IGNITION SYSTEM FOR MULTIPLE FUEL BURNERS Filed Jan. 6, 1951 2 Sheets-Sheet 2 INVNTOR Hanoi W Ewq qmd BY Robert C. Mauz.

YWHR AFWGQYEY United States Patent IGNITION SYSTEM FOR MULTIPLE FUEL BURNERS Harold W. Rice, Los Angeles, and Robert C. Main, San

Gabriel, Calif., assignors to Robertshaw-Fulton Controls Company, Greensburg, Pa., a corporation of Delaware Application January 6, 1951, Serial No. 204,792 2 Claims. (Cl. 158-124) This invention relates to ignition systems for fuel burners and more particularly to electrically operated systems for multiple fuel burners.

Systems of the type indicated have been arranged so that a switch may be closed to energize an igniter circuit when a manually operable valve is opened to admit fuel to a burner. The fuel is then ignited by the electric igniter andatter the expiration of a starting period the igniter is disconnected by the operation of a timing device. It 1s apparent that controls for multiple burners would involve the use of a plurality of switch actuating and tim ng mechanisms and that the cost of a multiple burner ign tion system would be substantially reduced if a single tim ng mechanism were made to serve a number of igniters. It is a principal object of this invention to provide an ignition system wherein a multiplicity of electric igniters are controlled by a single timing means.

A preferred embodiment of this invention takes the form of a gas range with electric igniters for the top and oven burners connected in parallel and the energization of the igniter circuit under the control of a relay operated main switch. A number of normally open switches are respectively associated with the fuel control valves to be closed when the valves are opened, the switches being connected in parallel and the parallel switch circuit being connected in series between a source of electric current and the relay coil so that closure of any one of these switches will energize the coil to actuate the main switch and energize the igniter circuit. A holding circuit, completed upon closure of the main switch, maintains a voltage across the relay coil until the holding circuit is broken by a timing device. To prevent energization of the oven igniter each time a top burner igniter is energized, a switch is connected in series with the oven igniter and is connected to the oven burner supply valve in such a way that it is closed only when the valve is in open position. Thus, as will appear hereinafter, the necessity of a timing device for each igniter is eliminated.

Another object of this invention is to provide a simple ignition system including a single timing mechanism and a plurality of electric igniters wherein the igniters may be selectively energized.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings wherein:

Fig. 1 is perspective view of a fuel supply and ignition apparatus for gas range top and oven burners embodying this invention; and

Fig. 2 is a wiring diagram for the apparatus of Fig. 1.

Referring more particularly to Fig. 1 of the drawings, the ignition apparatus is shown in connection with a cooking range having the usual oven burner and top burners 12, 14, 16 and 18. As is customary in equipment of this nature, the various burners receive fuel from a manifold 20 connected to a source of fuel supply.

The main oven burner 10 is supplied with fuel from the manifold 20 by a fuel pipe 22 and the fuel supply there in is under the control of means comprising a fuel cock 24 which may also embody the usual thermostatic control device adjustable, together with the cock 24, by a knob 26 and being responsive to temperatures in the oven where the burner 10 is located. As combined fuel cocks and thermostatic control devices are well known, further description is deemed unnecessary.

The flow of fuel in the pipe 22 to the oven burner 10 is also under the control of a safety shut-off device,

2,705,531 Patented Apr. 5, 1955 designated generally by the reference numeral 28, here shown as being responsive to the presence of a flame at a pilot burner 30 disposed in lighting relation with the oven burner 10. The safety shut-off device 28 may be of any known type and includes a thermal element 32 disposed adjacent the pilot burner 30 to be subjected to the heat of a flame emanating therefrom. The pilot burner 30 is supplied with fuel from the manifold 20 by a conduit 34, the supply of fuel therein being under the control of the fuel cock 24 but not under the control of the thermostatic control device associated with the cock 24 in a manner well known in the art.

Means are provided for supplying fuel to the top burners 12, 14, 16 and 18 and since the structure and operation of each means is similar to the other, a description of one will suffice to show the structure and operation of all. Corresponding parts of such similar means are designated by corresponding reference numerals followed by the suffixes a, b, and 0 respectively.

The top burner 14 may be supplied with fuel from the manifold 20 by a fuel pipe 36 and the fuel supply therein is under the control of a cock 38 manually operable between open and closed positions by means of a knob 40.

Fuel issuing from the top burners 12 and 14 is adapted to be ignited through corresponding flash tubes 42 by an electric resistance igniter 44 and similarly fuel issuing from the top burners 16 and 18 is adapted to be ignited through similarly corresponding flash tubes 42 by an electric resistance igniter 46. Fuel issuing from the pilot burner 30 is adapted to be ignited by an electric resistance igniter 48. As will more fully appear, energization of the igniters 44, 46 is under the control of switches 50, 50a, 50b, and 500 operatively associated with cocks 38, 38a, 38b, and 38c respectively, and energization of the igniter 48 is under the control of switches 52 and 62 operatively associated with the cock 24.

Referring now to Fig. 2, the igniters 44, 46 and 48 are shown as being connected in parallel across wires 56 and 58 connected to the upper and lower terminals respectively of the secondary winding of a step-down transformer 60. A switch, indicated generally by the reference numeral 62, is connected in series with the oven burner igniter 48. It will be apparent that if electric current is supplied to the primary winding of the transformer 60 the above described circuit including the igniters 44, 46 and 48 will be energized to permit the igniters to perform their igniting function.

The primary coil of the transformer 60 is connected to a source of electrical energy by wires 64 and 66 under control of a main switch 68. The main switch 68 is adapted to be actuated by control means or a relay designated generally by the reference numeral 70. The control relay 70 is of the electromagnetic type having a solenoid winding 72 and a movable core 74 cooperable therewith. The movement of the core 74 to attracted position is designed to operate the main switch 68 to its closed position to connect the primary winding of the transformer 68 with a source of commercial current here shown as line wires L1 and L2.

Movement of the core 74 of the relay 70 to attracted position is also adapted to operate a time delay switch 76 which will open after a specified time delay and have an instantaneous reset characteristic. The switch 76 is preferably of the mercury tube type well known to those skilled in the art and is so indicated in the drawing. The switch 76 is arranged to be closed when the core 74 of the relay 70 is in its unattracted position and to open after a predetermined time delay following movement of the core '74 to its attracted position. The switch 76 is provided with a pair of electrodes 78, 80 and an electrical connection is established therebetween by a body of mercury 82 when the core 74 of the relay 70 is in its unattracted position.

Means are provided to maintain the main switch 68 in its closed position in order that the igniters 44, 46 and 48 will remain energized to effect fuel ignition. This means takes the form of a holding circuit which is completed when the main switch 68 is moved to the closed position and may be traced as follows: line wire L1, wire 84, electrode 78 of time delay switch 76, body of mercury 82, electrode 80 of time delay switch 76, wire 86, solenoid winding 72 of relay 70, lower switch blade of main switch 68, and wire 88 to line wire L2. Since the holding circuit thus traced includes the time delay switch 76, the time delay switch 76 will break the holding circuit after a predetermined period to provide an effective means for setting the period during which the igniters 44, 46, 48 will be energized as will more fully appear.

Means are provided for causing the control relay 70 to close the main switch 68 when any one of the cocks 24, 38a, 38b, or 380 is moved from the closed to an open position. These means may comprise the switches 50, 50a, 50b, 50c, and 52 connected in parallel between wires 90 and 92, wires 90 and 92 being connected to the solenoid winding 72 of the relay 70 and to the Wire 88 respectively. Each of the switches 50, 50a, 50b, 50c, and 52 are identical and a description of one will suffice to show the structure and mode of operation of all, corresponding parts of similar switches being designated by corresponding reference numerals followed by the suffixes a, b, c and d respectively.

The switch 50 includes an element 94 rotatable with the knob 40 and gas cock 38 and a cam element 96 is carried by the element 94. The cam element 96 is adapted to engage a resilient switch arm 98. The switch arm 98 carries a contact 100 which is adapted for operative engagement with a relatively fixed contact 102 when the knob 40 is rotated from closed toward open position. It will be apparent that the engagement between the contacts 100 and 102 is momentary only and that the cam element 96 will slip past the resilient switch arm 98 upon further rotation of the knob 40. Moreover, when the knob 40 is rotated in the reverse direction, the contacts 102, 100 cannot become engaged.

When the contact 100 engages the contact 102 a circuit is established as follows: line wire L2, wire 88, wire 92, wire 104, contact 102, contact 100, resilient switch arm 98, wire 106, wire 90, solenoid winding 72 of control relay 70, wire 86, electrode 80 of time delay switch 76, body of mercury 82, electrode 78 of time delay switch 76, and wire 84 to line wire L1. Thus, the solenoid winding 72 of the control relay 70 will be energized to move the main switch 68 to the closed position to energize the primary winding of the transformer 60 and complete the holding circuit of the control relay 70 as hereinbefore described.

The rotatable element 94d, associated with the oven burner cock 24 may carry a second cam element 108 adapted to operate the switching means 62 during rotation of the knob 26 between closed and open positions.

The switching means 62 may comprise a toggle arrangement having a switch lever 110 pivoted intermediate its ends and engaged by a coil spring 112 for causing the switch lever 110 to remain in the position to which it has been moved. Thus, upon rotation of the knob 26 in a counterclockwise direction from closed to open position, the cam element 108 will engage the switch lever 110 and cause rotation thereof on its pivot in a clockwise direction. When this movement is completed, the switch lever 110 makes engagement with a relatively fixed contact 114. When the knob 26 is rotated in the reverse direction, the switch lever 110 is moved out of engagement with the contact 114 by the cam element 108 and, under bias of the spring 112, will remain in contact disengaged position until the knob 26 is again rotated in counterclockwise direction.

In the operation of the apparatus, assuming that there is no flame present at any of the burners and that it is desired to ignite a top burner, one of the knobs 40, 40a, 4017, or 400 is rotated in a counterclockwise direction to admit fuel to the burner associated therewith. One of the switches 50, 50a, 50b, 500 is momentarily closed to energize the solenoid coil 72 of the control relay 70 to cause the main switch 68 to be moved to the closed position thus energizing the primary winding of the transformer 60 and completing the holding circuit of the control relay 70. Current will now flow through the igniters 44, 46 and their temperatures will be raised sufficiently to cause ignition of the fuel. At the expiration of a period of sufficient length to permit fuel ignition to take place, the time delay switch 76 will interrupt the holding circuit of the control relay 70 permitting the core 74 to move to its unattracted position. Movement of the core 74 to the unattracted position opens the main switch 68 to break the supply circuit for the primary winding of the1 transformer 60 and thus deenergize the igniters 44 an 6.

If it is desired to ignite the oven burner 10, the knob 26 is rotated in a counterclockwise direction to open the cock 24 to admit fuel to the pilot burner 30 through the conduit 34. Switch 62 will be closed to connect the igniter 48 across the terminals of the secondary winding of the transformer 60 to a circuit which may be traced as follows: lower terminal of the secondary winding of the transformer 60, wire 58, wire 116, contact 114, switch lever 110 of switch 62, wire 118, igniter 48, wire 120, and wire 56 to the upper terminal of the secondary winding of the transformer 60. counterclockwise rotation of the knob 26 will also cause momentary closing of the switch 52 to cause operation of the control relay 70 and energization of the primary winding of the transformer 60 in the same manner as would the closing of one of the switches 50, a, 50b, and 500.

Since the igniter 48 is now connected across the terminals of the secondary winding of the transformer current will flow through the igniter 48 raising its temperature sutficiently to provide for the ignition of fuel flowing from the pilot burner 30. The igniter 48 will remain energized until the time delay switch 76 interrupts the holding circuit of the control relay to cause opening of the main switch 68 and deenergization of the primary winding of the transformer 60. The thermal element 32 of the safety shut-off device 28 will respond to the presence of flame at the pilot burner 30 to condition the safety shut-off device 28 to admit fuel to the oven burner g3 where it will be ignited by the flame at the pilot burner It will be apparent that switching means may be connected in series with the igniters 44 and 46 and operatively associated with the cooks 38, 38a, 38b, and 380, in the same manner as the switch 62 is associated with the oven burner cock 28 so that the igniters 44, 46 may be selectively energized.

While a relatively simple ignition system for multiple fuel burners has been described and shown it will be apparent that many changes can be made in the arrangement and combination of parts and in the details of construction herein disclosed within the scope of the appended claims without departing from the spirit of the invention.

It is claimed and desired to secure by Letters Patent:

1. An ignition system for a plurality of fuel burners having a source of electrical energy and comprising a plurality of electrical resistance igniters in parallel circuit, at least one switch means movable between open and closed positions and connected in series with at least one of said igniters, a plurality of manually operable fuel controlling means adapted to be connected respectively with said burners and being respectively movable between fuel flow permitting and fuel flow preventing positions, main switch means movable between open and closed positions for controlling the energization of said circuit, an electrical relay for actuating said main switch means, a plurality of normally open switches in parallel circuit, said last named circuit being connected in series with the coil of said relay and with said source, a plurality of means respectively associated with said fuel controlling means and said normally open switches for momentarily closing each of said normally open switches upon movement of the fuel controlling means associated therewith from fuel flow preventing position to fuel flow permitting position to thereby energize said relay and close said main switch means, a holding circuit for said relay adapted to be completed with the closing of said main switch means, a time delav switch in said holding circuit for interrupting said holding circuit upon the expiration of a predetermined period initiated at the completion of said holding circuit, and means oneratively associated with at least one of said fuel controlling means and with said at least one switch means for moving said at least one switch means to closed position upon movement of the fuel controlling means associated therewith from fuel fiow preventing position to fuel flow permitting position.

2. An ignition system for gas ranges having top and oven burners, a plurality of manually operable valves adapted to be connected respectively with the burners and being respectively movable between fuel flow preventing and fuel flow permitting positions, and a source of electrical energy comprising an electrical resistance 35 igniter for said top burners, an electrical resistance igniter for said oven burner, switching means movable between open and closed positions and connected in series circuit with said oven igniter, said top burner igniter being connected in parallel circuit with said oven burner igniter and said switching means, main switch means for controlling the energization of said parallel circuit, an electrical relay for controlling said main switch means, a plurality of normally open switches in parallel circuit, said last named circuit being connected in series with the coil of said relay and with said source, a plurality of means respectively associated with said fuel controlling means and said normally open switches for causing momentary closing of each of said normally open switches upon movement of the valve associated therewith from fuel flow preventing position to fuel flow permitting position to thereby energize said relay and close said main switch means, means operatively associated with said switching means and with that one of said valves connected with said oven burner for moving said switching means to closed position upon References Cited in the file of this patent UNITED STATES PATENTS 1,493,070 Evans May 6, 1924 1,635,104 Woods July 5, 1927 1,940,127 Herthneck Dec. 19, 1933 2,120,841 McSherry Jan. 6, 1938 2,194,634 Betz Mar. 26, 1940 2,212,875 Camp Aug. 27, 1940 2,417,667 Strobel Mar. 18, 1947 2,513,257 Strobel June 27. 1950

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