USRE22554E - Electrical ignition system for - Google Patents

Description

Oct. 10, 1944. v. WEBER Re. 22,554

sum-men. min-non SYSTEM FOR GASE'OUS m1. mmusns:

Original Filed Ilay 7, 194] luvm Vm'mR Wmaz Reiaou'e'dOctIO, 1944 ELECTRICAL IGNITION SYSTEM FOB GASIOUS FUEL BURNEBS Pa, a corporation of Pennsylvania Original No. 2,310,910, dated April 20, 194:, Berhl No. 892,290, May I, 1941.

August 12, 1944, Serial No. 549,22.

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Application for re- '-'.lhisinventionrelalestoignitionsystemsand, more particularly, to electrical ignition systems for gaseous fuel burners. In systems employing for ignition of a gaseous fuel burner, it is necessarytohcatthewlretoincandescenceinorder to obtain a flame at the burner. The line voltage of commercial current is subiect to fluctuation inmost localities and also varies between different sections of the country. Such variations obviously cause changes in the current supplied to the i tion device unless means are provided in thecircuitofthesecondarycoiloftheusual transformer to maintain substantially constant current flow and protect the ignition wire against excessive current values.

Resistors which increase in temperature with increases in the current, and thus increasing theirresistancearewellknm. Ithasbeen proposed to include such so-called ballast resistors in the circuit with the secondary coil of electrically heated wires ballast resistor to control the current in the circuit within relatively narrow limits.

, It ha been found, however, thatthe use of a ballast resistor to re late the current results in high inrush current before the resistor can heat suillciently. Although this inrush is of momentary duration, it may heat the igniter wire to a temperature close to the fusion point. Hence, while the regulation of the current by such devices is of considerable value, the disadvantage of the high inrush current detracts therefrom.

It is an object of this invention to regulate the current flow within close limits while preventing any inrush from reaching the ignition device.

Another object of this invention is to prevent continued ilow of fuel upon failure of the electric circuit of the system or of the power supply.

Another obiect of the invention is to ensure satisfactory ignition of the fuel at the lowest voltage which may be encmmter'ed.

Another oblect of the invention is to increase the efliciency of the system without detracting from its simplicity.

Other objects and advantages will become apschematically in conjunction with a wiring diagram of the ignition circuit.

Referring more particularly to the drawing.

the transformer II has its-primary coil ll con- 'other terminal of the switch of the thermostat It carries a wire 2| connected to one terminal of a delayed action switch I! which is open when the circuit is deenergised. In this embodiment of the invention the switch a is of the thermoresponsive type, comprising a bi-metal switch arm 24 adapted to warp when heated by energization of the circuit and make contact with the substantially fixed contact ll.

The bi-metal arm fl is connected at all times with a resistance element 28 by means of a conductor Ill. The resistance element 2' is of the type which does not change its resistivity when energized but which remains substantially constant. Connected-in series with the constant resistance element 28 is a ballast resistor If, an electromagneticv fuel valve is and an electric resistance igniting coil 3}. A wire 38 completes the circuit from the igniting coil to the secondary coil of the transformer.

As shown in the drawing. the ballast resistor 82 i enclosed within the constant resistance element 28. This preferred embodiment of the invention lncrem the eihciency of the system by utilizing the ambient heat due to the constant resistance element 2! to bring the ballast resistor more rapidly to operating temperature. It will be apparent, however, that where this fea- 'ture is not desired the two elements may be otherwise arranged as long as both remain connected in series with the secondary circuit of the transformer ll.

- The igniting coil II, in this embodiment, is positioned within the oven or other chamber of a domestic range, a portion of which is shown diagrammatically at ll. The conduit it conveys gaseous fuel from a source of supply to a burner P I 42 connected thereto and which may be podtioned within the oven or other chamber it in poution to be by the igniting coil 8!.

. tion' will cause the As previously mentioned herein, the ballast resistor 32 is adapted to vary its resistance with.

V consequently, in the secondary circuit described.

Such variations in the supply voltage will be re ulated by'the-ballast resistor and a substantially constant current will fiow to the ignition coil during operation of the system.

This invention .is more particularly directed toward the provision of means for protecting the ignition coil from the effects of high inrush current which may occur due to the use of the ballast resistor without reducing the amount of current available during normal operating conditions. To this end, the constant resistance element 28 is provided and serves to prevent the current surge from reaching the igniting coil 3'. The resistance of the element 28 is, consequently, relatively high compared with that of the ballast resistor. It will be apparent, therefore, that when the inrush current has dropped to a safe value, the constant resistance element 28 has served its purpose and continued operation thereof would detract from the value of the current available in the secondary circuit for energizing the igniting coil 28.

In carrying out this feature of the invention means are provided to discontinue current fiow through the constant resistance element 28 after the ballast resistor 32 becomes operative and the current surge due to its presence has ceased. This means comprises a wire 44 for the fixed terminal 28 of the delayed action switch 22 which connects to the end of the constant resistance 28 opposite the conductor 38 and places the switch 22 in parallel with the secondary circuit for shunting the resistance 28 at appropriate times.

The operation of the system is as follows: movement of the main switch It to closed posimain fuel valve.in conduit II to be opened. Current then flows through the secondary circuit by way of the wire 20. bi-metal arm 24, conductor Ill, constant resistance element 28 and ballast resistor 32 to the electromagnetic valve 34. The solenoid of the electro-' magnetic valve 84 will be energized to open this valve and permit gas to flow to the burner 42. At the same time, the current will fiow to the ignition coil 36 which will become incandescent and serve to ignite the fuel at the burner 42.

The high inrush current which may occur before the ballast resistor approaches operating temperature will not reach the igniter coil 35 due to the presence of the constant resistance ele-f ment 28. After the expiration of a few seconds, the ballast resistor becomes sufficiently heated and thus operative to reduce any current variations in the secondary circuit due to variation in the supply voltage. During the time that the ballast resistor is becoming operativethe bi-metal arm 24 of the delayed action switch 22 is simultaneously becoming heated and warping toward closed position with the fixed contact 26.

Thus, when the ballast resistor isfully operative and the current surge due to its presence in the circuit has ceased, then the delayed action I switch 22 shunts out the constant resistance element 28 from the secondary circuit. A stabilized current of full voltage is thus available at the ignition coil 26 providing satisfactory operation of the system over long periods of time. Should the ignition coil fall, or the secondary circuit otherwise become deenergized, then the electromagnetic valve 34 will close to shut off the supply units could obviously be substituted. This'and other modifications could be made without departing from the spirit of the invention which generally consists in an arrangement capable of carrying out the objects of the invention set forth and in the combination defined in the ppended claims. I

Iclaim:

1. An electric ignition device for fuel burners having a source of current supply subject to voltage variation, an electric igniter adapted to be energized from said source, means in circuit with said igniter for reducing current variations.

through said igniter, said means producing high inrush current conditions before becoming opera? tive, means in said circuit for preventing said inrush current from reaching said igniter-,and means operable to discontinue current flow throughthe last said means after the first said means becomes operative.

2. An electric ignition device for fuel burners having a source of current supply subject to voltage variation, an electric igniter adapted to be energized from said source, a ballast resistor in circuit with said igniter for reducing current variations through said igniter, a constant resistance element in said circuit for preventing high inrush current due to the ballast resistor from reaching said igniter, and means operable to shunt said constant resistance after the ballast resistor becomes operative.

3. An electric ignition device for fuel burners having a source of current supply subject to voltage variation, an electric igniter adapted to be energized from said source, a ballast resistor in circuit with said igniter for reducing current variations through said igniter, a constant resistance element in said circuit for preventing high inrush current due to the ballast resistor from reaching said igniter, and switching means operable to shunt said constant resistance after the ballast resistor becomes operative.

4. An electric ignition device for fuel burners having a source of current supply subject to voltage variation,. an electric igniter adapted to be energized from said source, a ballast resistor in circuit with said igniter for reducing current variations through said igniter, a constant resistance element in said circuit for preventing high inrush current due to the ballast-resistor irom'reaching said igniter, and a normally open switch adapted to close and shunt said constant resistance after the ballast resistor becomes operative.

5. An electric ignition device for fuel burners having a source of current supply subject to voltage variation, an electric igniter adaptedto be energized from said source, a ballast resistor in circuit with said igniter for reducing current variations through said igniter, 'a constant-iresistance element in said circut for preventing high inrush current due to the ballast resistor from reaching said igniter, and a delayed action switch connected across said resistance element, said switch being adapted to close after the ballast resistor becomes operative.

6. An electric ignition device for fuel burners having a source of current supply subject to voltresistance coil in series with said igniting coil having a substantially constant resistivity, said second coil being adapted to prevent high inrush current due to the first said coil from reaching said igniting oofl, and a temperature responsive switch connected across said second resistance coil and being normally open, said switch being adapted to delay closing until after the first said resistance coil becomes operative.

7. An electric ignition device for fuel burners having a source of current supply subject to voltage variations, an electric igniter adapted to be energized from said source, a ballast resistor in circuit with said igniter for reducing current variations through said igniter, a constant resistance element in said circuit for preventing high inrush current due to the ballast resistor from reaching said ia'niter, said resistance element being in proximate relation to the ballast resistor to increase the ambient temperature therearound, and means operable to discontinue current flow through said resistance element after said ballast resistor becomes operative.

' 'VICI'OR WEBER.

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