US3561900A

US3561900A - Igniter system

Info

Publication number: US3561900A
Application number: US805719A
Authority: US
Inventors: Lyman H Walbridge
Original assignee: Fenwal Inc
Current assignee: BLOOM-1 Inc A CORP OF; Fenwal Inc; Kidde Fenwal Inc
Priority date: 1969-03-10
Filing date: 1969-03-10
Publication date: 1971-02-09
Anticipated expiration: 1988-02-09
Also published as: FR2037895A5; GB1240957A; JPS5025659B1

Abstract

THE ELECTRONIC IGNITER SYSTEM DISCLOSED HEREIN EMPLOYS A HIGH VOLTAGE SPARK GENERATING CIRCUIT WHICH IS ADAPTED TO PROVIDE IGNITING SPARKS TO PLURALITY OF BURNERS WHEN ANY ONE OF THE BURNERS IS TURNED ON, BUT NOT LIT. THE SPARK GENERATING CIRCUIT CAN BE TRIGGERING INTO OPERATION BY ANY ONE OF A PLURALITY OF TRIGGERING CIRCUITS, THERE BEING ONE TRIGGERING CIRCUIT FOR EACH BURNER. ASSOCIATED WITH EACH TRIGGERING CIRCUIT IS A MEANS FOR DISABLING THAT TRIGGERING CIRCUIT WHEN THE RESPECTIVE BURNER IS EITHER TURNED OFF OR IS LIT.

Description

Feb. 9, 1971 l.. H. WALBRIDGE IGNITER SYSTEM Filed March lO INVENTOR. WALBRlDGE LYMAN H.

M781?, M f WMM 1 lUnited States Patent O U.S. Cl. 431-256 11 Claims ABSTRACT OF THE DISCLOSURE The electronic igniter system disclosed herein employs a high voltage spark generating circuit which is adapted to provide igniting sparks to a plurality of burners when any one of the burners is turned on, but not lit. The spark generating circuit can be triggered into operation by any one of a plurality of triggering circuits, there being one triggering circuit for each burner. Associated with each triggering circuit is a means for disabling that triggering circuit when the respective burner is either turned off or is lit.

BACKGROUND OF THE INVENTION This invention relates to igniter systems and more particularly to an electronic igniter system adapted for use with a plurality of burners.

Various igniter systems have been suggested for use with gas burners. One such system is disclosed in U.S. Pat. No. 3,377,125 issued to R. I. Zielinsky on Apr. 9, 1968. Such prior art systems, however, are typically adapted only for use with a single burner. Thus, in the case of a typical domestic cooking stove having four burners, four complete igniter systems must be provided.

Among the several objects of the present invention may be noted the provision of an .electronic igniter system which can be used with a plurality of burners; the provision of such a system which will provide igniting sparks when any one of the burners is turned on but not lit; the provision of such a system which is highly reliable; and the provision of such a system which is relatively simple and comparatively inexpensive. Other objects and features will be in part apparent and in part pointed out here and after.

SUMMARY OF THE INVENTION Briefly, the igniter system of the present invention is adapted for use with a plurality of burners. A high voltage spark generating circuit is provided which includes a spark coil and a triggerable semiconductor current switching device interconnected with the coil. The spark generating circuit is operative to generate igniting sparks adjacent the burners when the switching device is triggered. The system also includes a plurality of timing capacitors, one for each of the burners, and a plurality of charging circuits, one for each capacitor, for applying a charging current to the respective capacitor. A plurality of triggering circuits, one for each capacitor, are provided for triggering the switching device when the voltage on the respective capacitor reaches a predetermined level. A respective means associated with each burner shunts the respective capacitor when the fuel supply to that burner is turned otf or when a flame is present at that burner. Accordingly, the spark generating circuit is energized to generate igniting sparks when any one of the burners is turned on but not lit.

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BRIEF DESCRIPTION OF THE DRAWING The single ligure is a schematic circuit diagram of an igniter system according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, a plurality of conventional gas burners are indicated at 11-14. Fuel is provided to these burners through a common supply line or pipe 17 and respective valves 21-24. The burners are assumed to -be electrically grounded as indicated at 27. Associated with each of the valves 21-24 is a respective switch S1- S4. Each switch is mechanically coupled to the respective valve in such a way that the switch is opened when the 0 valve is opened to admit fuel to the burner and is closed when the valve is closed. One side of each switch is grounded as indicated.

A high voltage spark generating circuit is indicated generally at 29. This circuit includes a spark coil 30 having a pair of primary windings W1 and W2 and a pair of secondary windings W3 and W4 and also includes an SCR (silicon controlled rectier) Q1. The anode-cathode circuit of SCR Q1 is interconnected with the primary windings W1 and W2 in a series circuit which includes an energy storage capacitor CE, the cathode of the SCR and one side of the capacitor being grounded as indicated. The spark generating circuit is energized through a pair of supply leads L1 and L2 which may be connected to any appropriate A.C. source, e.g., conventional volt 60-cycle supply mains. The lead L2 is assumed to be grounded as indicated.

Charging current is supplied to capacitor CE from lead L1 through a current-limiting resistor RL and a rectifying diode D1. Once capacitor CE is charged, triggering SCR Ql will generate a high voltage pulse across each of the spark coil secondary windings W3 and W4, as is understood. The ends of the secondary windings W3 and W4 are connected to respective electrodes 31-34 which are positioned adjacent respective ones of the burners 11-14. Each electrode thus denes, with the respective burner, a spark gap adjacent that burner. Accordingly, the high voltage pulse generated across each secondary winding when the SCR Q1 is triggered causes an igniting spark to be produced adjacent each burner.

A plurality of capacitors, one for each burner, are indicated at C1-C4. Charging current is provided to each of the timing capacitors C1-C4 through a respective charging circuit. Each charging circuit, as illustrated, comprises a respective resistor R1-R4. For reasons eX- plained, hereinafter, the resistors R1-R4 are preferably of relatively high value. Each of the capacitors C1-C4 is connected, through a respective neon lamp N1-N4, to the gate of SCR Q1. As is understood by those skilled in the art, neon lamps N1-N4 are voltage breakdown devices which will conduct only after the voltage applied thereto exceeds a predetermined threshold and will cease conducting only when the applied voltage drops to a substantially lower level. When any one of the lamps N1-N4 breaks into conduction, a triggering pulse is applied to the gate of SCR Q1. The gate-cathode circuit of the SCR is shunted by a resistor R6 for bleeding ott any leakage currents.

The junction between each capacitor C1-C4 and the respective charging resistor R1-R4 is connected to the ungrounded side of a respective one of the switches S1-S4. Thus, when any one of the valves 21-24 is closed, the

respective timing capacitor C1-C4 is discharged or shunted by the switch.

The junction between each timing capacitor C1-C4 and its respective charging resistor R1-R4 is also connected to an electrode 41-44 associated with the respective burner 11-14. As is understood by those skilled in the art, the ionized gases present in a flame will conduct a detectable amount of current. The electrodes 41-44 employ this principle for ame sensing, each of the electrodes being positioned relative to the respective burner so that a conductive path to ground is established when the burner is lit. As may be seen, this conductive path shunts the respective timing capacitor C1-C4.

Although the conductive path through the llame is of relatively high impedance, the current drawn from one of the electrodes 41-44 is suicient to prevent the respective timing capacitor C1-C4 from charging to the ring threshold of the respective neon lamp N1-N4 since the charging resistors R1-R4 are likewise of relatively high value. Thus, the electrode and switch associated with each burner together form a control circuit for shunting the respective capacitor when the fuel supply to that burner is turned off or when the flame is present. Thus, in either case the respective capacitor is prevented from charging.

An alternate method of preventing each capacitor from charging when the fuel supply to the respective burner is cut off is to place a normally open switch in series with each charging resistor, the switch lbeing closed lwhen the respective valve is opened.

The operation of this system is substantially as follows. Assuming initially that all of the valves 21-24 are closed, the spark generating circuit is quiescent even though the energy storage capacitor CE is charged from the supply leads through resistor RL and diode D1. When any one of the valves 21-24 is opened, the respective timing capacitor C1-C4 begins to charge through the respective resistor R1-R4. When the voltage on that capacitor reaches the firing threshold of the respective neon lamp N1-N4, a triggering pulse is delivered to the gate of SCR Q1. Firing of the SCR causes the energy stored on capacitor CE to be delivered, through the spark coil 30, as a high voltage spark at the spark gaps existing between the electrodes 31-34 and the respective burners. If the burner which is turned on is not lit by this first sparking impulse, the energy storage capacitor CE and the respective timing capacitor C1-C4 will recharge after each spark discharge and the cycle will repeat indefinitely. However, if the burner which is turned on ignites, as may be expected in normal operation, the flame present at the rburner will prevent the respective timing capacitor from again recharging due to the shunting conduction path established through the ionized gases from the respective sensing electrode 41-44.

Since a separate triggering circuit is provided for ea'ch burner and since each of the triggering circuits has the I power to produce sparking discharges at the electrodes 31-34, it can be seen the spark generating circuit is energized when any one of the burners is turned on but not lit. This is true even though other of the burners may already be turned on and lit. In other words, the spark generating circuit will be deenergized only if all the burners are either turned off or ignited.

The present invention may also be used with single 'burners which are of such size that it is desirable to provide flame sensing and ignition at several different points v or locations. In such a case, the separate switches for preventing charging of the dilerent timing capacitors may be omitted and a single switch for deenergizing the entire circuit may be used. Thus, the phrase a plurality of burner locations should be understood to mean diifer ent points on a single burner as well as a plurality of separate burners.

In view of the above, it will be seen that the several objects of the invent-ion are achieved and other advantageous results are attained.

As various changes could 'be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. An igniter system for a plurality of burner locations, said system comprising:

a high voltage spark generating circuit, including a spark coil and a triggerable semiconductor current switching device interconnected with said coil, for generating igniting sparks adjacent said burner locations when said switching device is triggered; l

a plurality of timing capacitors, one for each burner location;

a plurality of charging circuits, one for each of said capacitors, for selectively applying a charging current to the respective capacitor;

a plurality of triggering circuits, one for each of said capacitors, for triggering said switching device when the voltage on the respective capacitor reaches a predetermined level; and

a respective means associated with each burner location for preventing charging of the respective timing capacitor when a llame is present at that burner location whereby said spark generating circuit is energized when any burner location is not ignited.

2. An igniter system as set forth in claim 1 wherein said spark generating circuit includes an energy storage capacitor which is discharged into said coil when said switching device is triggered.

3. An igniter system as set forth in claim 2 including a supply circuit for charging said energy storage capacitor, said supply circuit having a rectifying diode whereby said energy storage capacitor can be charged from an A.C.

source.

4. An igniter system as set forth in claim 1 wherein each of said charging circuits includes a resistor of re1- atively high value.

5. An igniter system as set forth in claim 1 wherein said triggerable semiconductor current switching device is an SCR.

6. An igniter system as set forth in claim 5 wherein each of said triggering circuits comprises a neon lamp connecting the respective timing capacitor to the gate of said SCR.

7. An igniter system for a plurality of burners, said system comprising:

a high voltage spark generating circuit, including a spark coil and a triggerable semiconductor current switching device interconnected with said coil, for generating igniting sparks adjacent said burners when said switching device is triggered;

a plurality of timing capacitors, one for each of said burners;

a plurality of charging circuits, one for each of said capacitors, for applying a charging current to the respective capacitor;

a plurality of triggering circuits, one for each of said capacitors, for triggering said switching device when the voltage on the respective capacitor reaches a pre' determined level; and

a respective means associated with each burner for preventing charging of the respective timing capacitor when the fuel supply to that burner is turned olf or a flame is present at that burner whereby said spark generating circuit is energized when any burner is turned on but not lit.

8. An igniter system as set forth in claim 7 wherein each of said burners is selectively supplied with fuel through a respective valve and wherein each of said means for preventing charging of a respective timing capacitor includes a switch for shunting that capacitor, which switch is opened when the respective valve is opened.

9. An igniter system as set forth in claim 7 wherein each of said means for preventing charging of a respective timing capacitor includes at least one electrode adjacent the respective burner for providing a shunting conduction path through the burner flame when the burner is lit.

10. An igniter system for a plurality of burners, said system comprising:

a high voltage spark generating circuit including a spark coil, an energy storage capacitor and a triggerable semiconductor current switching device for discharging said capacitor into said coil thereby to generate igniting sparks adjacent said burners when said switching device is triggered;

a plurality oftiming capacitors, one for each of said burners;

a plurality of charging circuits, each of which includes a resistor of relatively high value, for applying charging currents to respective ones of said capacitors;

a plurality of triggering circuits, each of which includes a voltage breakdown device, for triggering said switching device when the voltage on a respective one of said capacitors reaches a predetermined level;

a respective switch associated with each burner for preventing charging of the respective timing capacitor when the fuel supply to that burner is turned off; and

a respective means, including at least one electrode adjacent the respective burner, for shunting the respective timing capacitor when a llame is present at the respective burner whereby said spark generating circuit is energized when any burner is turned on but not lit.

11. An igniter system for a plurality of burners, said system comprising:

a respective spark gap defining means for each burner;

at least one spark coil having at least one secondary 6 winding interconnected with said spark gap defining means;

an energy storage capacitor connected in series with said primary winding;

means for charging said energy storage capacitor;

an SCR the anode-cathode circuit of which is connected across said primary winding and said energy storage capacitor thereby to discharge said capacitor into said primary winding when said SCR is triggered;

a plurality of timing capacitors, one for each of said burners;

a respective charging circuit including a resistor of relatively high value for applying a charging current to each timing capacitor;

a respective neon lamp connecting each timing capacitor to the gate of said SCR thereby to trigger said SCR when the voltage on the respective timing capacitor reaches a predetermined level;

a respective switch associated with each burner for shunting the respective timing capacitor when the fuel supply to that burner is turned olf; and

a respective circuit for each burner for shunting the respective timing capacitor through any flame present at that burner, whereby said SCR is repetitively triggered to generate sparks adjacent the burners when any burner is turned on but not lit.

References Cited UNITED STATES PATENTS 3,358,474 12/1967 Liesse 43l-125X EDWARD G. FAVORS, Primary Examiner U.S. Cl. X.R.