US3588302A - Electrically-operated igniter - Google Patents

Abstract

AN ELECTRICALLY OPERATED IGNITER FOR GAS AND OTHER FLAMMABLE MIXTURES COMPRISING A CONTROLLED SWITCH IN THE FORM OF A RELAY WHICH, UPON CLOSING, CONNECTS A SOURCE OF DIRECT CURRENT IN THE FORM OF A BATTERY TO AN AUTOTRANSFORMER. THE BATTERY CAN BE CONNECTED TO THE RELAY CONTROL WINDING IN A MANNER SUCH THAT A SQUARE WAVE OR PULSATING DC VOLTAGE APPEARS ON THE OUTPUT OF THE AUTOTRANSFORMER WHICH IS CONNECTED TO ARC-INITIATING ELECTRODES INCLUDES IN AN ELEMENT WHICH IS CONSTRUCTED SO AS TO TRAP OR COLLECT A SMALL, IGNITABLE

QUANTITY OF GAS. ALTERNATIVELY, A SECOND BATTERY AND SERIESCONNECTED RESISTANCE CAN BE CONNECTED ACROSS THE FIRST BATTERY WHEREBY A SINGLE OUTPUT VOLTAGE IS PROVIDED.

Description

United States Patent [72] Inventor Alton G. Herlan Cheektowaga, N.Y. [21] Appl. No. 829,367 [22] Filed June 2, 1969 [45] Patented June 28, 1971 [73] Assignee Robert .1. Barry Tonawanda, N.Y.

fractional part interest [54] ELECTRICALLY OPERATED IGNITER 11 Claims, 7 Drawing Figs.

[52] U.S.Cl 431/254, 317/96, 431/263 51 1m.c| F23q 3/01 [50] FieldotSearch 317/81,?9, 96; 431/254, 263, 258

[56] References Cited UNITED STATES PATENTS 2,995,685 8/1961 Lord 317/79 Primary Examiner- Edward G. Favors Attorney-Christel and Bean ABSTRACT: An electrically operated igniter for gas and other flammable mixtures comprising a controlled switch in the form of a relay which, upon closing, connects a source of direct current in the form of a battery to an autotransformer. The battery can be connected to the relay control winding in a manner such that a square wave or pulsating DC voltage appears on the output of the autotransformer which is connected to arc-initiating electrodes included in an element which is constructed so as to trap or collect a small, ignitable quantity of gas. Alternatively, a second battery and series-connected resistance can be connected across the first battery whereby a single output voltage is provided.

PATENTEU JUN28 15m SHEET 1 [IF 2 FIGJ IN V EN TOR.

ALTON G. HERLAN A TTOR NE Y5 PATENTEU JUN28 I97! SHEET 2 OF 2 INVEN'H m. ALTON 6. HERLAN A TTOQNEYS ELECTRICALLY OPERATED IGNITER BACKGROUND OF THE INVENTION The present invention relates to electrically operated igniters for gas and other flammable mixtures and, more particularly, to a novel igniter which is portable and adapted for low current operation.

In recent times gas-operated devices and appliances have come into widespread use, for example ranges, furnaces, clothes dryers, cooking grills, lanterns and torches to mention a few. A common method of igniting the gas or other flammable mixture is to insert a' flame burning on a match, candle or taper into the gas stream. This method obviously presents a safety hazard arising from the proximity of the operator's hand to the ignited mixture. In addition, when matches or other means for providing. a flame are not readily accessible, this method causes undesirable effort and delay.

An electrically operated igniter of the type wherein a spark or are discharge is developed between two electrodes can overcome many of-the difficulties associated with the method whereby a flame is inserted by hand. In particular, the electrodes can be positioned in the path of the gas stream and the operator remotely therefrom, and items such as matches and tapers are of course not needed. With most gas-operated devices, especially appliances with which people often come into physical contact such as cooking grills, an electrically operated igniter is advantageous only if it does not pose the hazard of dangerous electrical shocks. In particular, a highly desirable electrically operated igniter would require current only at a low, safe level. In addition to safety, portability is an important feature in hand-carried devices such as torches for metal working whereby the igniter can be carried on the device and into small spaces.

SUMMARY OF THE INVENTION The present invention provides an electrically operated igniter for gas and other flammable mixtures including an electrically controlled switch connected to a source of direct current and to an autotransformer in a manner causing an alternate buildup and collapse of the transformer field. A square wave or pulsating DC output voltage obtained fromthe transformer is applied to arc-initiating electrodes exposed to a small, ignitable quantity of the gas.

By way of illustration the present invention will be described with particular reference to igniters for gasoperated devices and appliances although the principles of the invention may be variously applied to devices and appliances operated by other flammable mixtures. While several specific embodiments of the principles of the present invention are illustrated in the accompanying drawing and described in detail in the following specification, it is to be understood that such embodiments are by way of example only and that various mechanical modifications may be made without departing from the spirit of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an igniter constructed in accordance with the present invention as it would be used with one type of device, for example a gas-operated cooking grill;

FIG. 2 shows an igniter constructed in accordance with the present invention as it would be used with another type of device, for example a gas torch;

FIG. 3 is a schematic diagram of one embodiment of an electrically operated igniter constructed in accordance with the present invention;

FIG. 4 is a schematic diagram of another embodiment of an electrically operated igniter constructed in accordance with the present invention;

FIG. 5 is an elevational view, partly in section, of an igniter head provided by the present invention;

FIG. 6 is a schematic diagram showing one arrangement wherein the igniter of the present invention is connected to control circuitry ofthe device in which it is included; and

FIG. 7 is a schematic diagram showing another arrangement wherein the igniter of the present invention is connected to control circuits of the device in which it is included.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS FIG. 1 shows an igniter constructed in accordance with the present invention as it would appear in use with, for example, a gas-operated cooking grill designated G. Such grills which are used widely for home cooking purposes include a burner element B within a housing elevated from the ground by a pedestal P to which burner gas is supplied through a pipe' under control of a valve. The igniter provided by the present invention includes three main components or parts: a control or energizing circuit 10, a high voltage cable 11 and an element 12 for housing the arc-initiating electrodes and for trapping small quantities of gas. As shown in FIG. 1 control 10 is conveniently attached to the grill pedestal P so as to be reached easily, and element 12 extends into the grill housing so as to be near the stream of gas. It is apparent that grill G will be touched often by people standing on the ground, which frequently is damp, and it therefore is important that the igniter pose no hazard of dangerous electrical shocks. An important feature of the igniter provided by the present invention is its low current operation which will be described in detail presently.

FIG. 2 shows an igniter constructed in accordance with the present invention as it is used with another device, a gas torch designated T. Torch T is of the portable, hand-carried type which is carried often into small spaces for metal cutting, soldering, welding, brazing and other operations. Igniter control or energizing circuit, here designated 10 is attached to the base of torch T, cable 11 extends along the body of torch T to the nozzle thereof where it isconnected to an element 12 housing arc-initiating electrodes and including a gas trapping region, which element 12 is located in the gas stream.

Because the igniter provided by the present invention is operative on low currents it can be battery powered which.

renders it portable. The arrangement with torch T thus described is one illustration of the many advantageous uses of an electrically operated igniter which is portable and operable on low currents.

FIG. 3 is a schematic diagram of one embodiment of an electrically operated igniter constructed in accordance with the present invention. The control or energizing circuit 10 of the igniter includes an electrically controlled switch in the form of relay 13 having a control winding 13a and movable contact arm 13!) adapted to be moved between contacts 13c, 13d in response to the flow of current in winding 13a. Controlled switch 13 is adapted to be connected in controlled relation to a source of direct current, in this particular illustration battery 14. As shown in FIG. 3, the positive terminal of battery 14 is connectedthrough a manually operated, momentary contact switch 15 to one end of relay control winding 13a, and the negative terminal of battery 14 is connected directly to the other end of relay control winding 13a. When switch l5 is closed, the entire voltage of battery 14 will be impressed on coil 13a energizing it and causing a movement of switch arm 13b. Relay 13 is normally open as indicated in FIG. 3 with arm 13b engaging contact 13c, so that in response to the flow of current in coil 13a arm 13b is moved to contact 13d which is included in the remainder of the circuit. The end of relay winding which is connected through switch 15 to the positive terminal of battery 14 also is connected to relay switch arm 13b. By virtue of this arrangement, battery 14 will be connected to the remainder of the circuit when controlled switch 13 is closed.

lgniter control or energizing circuit 10 further includes an autotransformer 16 wherein the terminals or taps through which electrical connections are made to the single coil or winding of the transformer 16 are designated 16a, 16b, and 16c. A distinguishing characteristic of autotransformers is that the single coil or winding thereof is common to both input and output or primary and secondary circuits, in other words the input and output or primary and secondary coils or windings are portions of the-same coil which portions often are overlapping. In the circuit of FIG. 3, the input portion of the coil of transformer 16 is the portion thereof between terminals 16a and 16b, and the output portion is included between terminals 16a and 16c. Terminal 16a of autotransformer 16 is connected to relay contact 13d and transformer terminal 16b is connected to the negative terminal of battery 14. By virtue of this arrangement, battery 14 is connected across the input coil of transformer 16 when switch 13 is closed.

Element 12 which houses the arc-initiating electrodes and functions to trap a' small quantity of gas and expose it to them is connected through high voltage cable 11 to the output coil portion of autotransformer 16. In particular, one lead or wire 11a of the cable is connected to winding terminal 16a and the other wire 11b is connected to terminal 160, leads 11a, 11b being connected to corresponding electrodes in element 12 as will be shown in more detail presently.

The nature of autotransformers, such as transformer 16, is such as to provide no direct current isolation between input and output or primary and secondary windings. Direct current isolation is a significant characteristic, on the other hand, of all transformers having two separate windings. In addition, autotransformers are known to have lower leakage reactances, lower losses,'and require smaller exciting currents than twowinding transformers under certain conditions.

The control or energizing circuit thus described operates in the following manner. When button 15 is depressed by hand, current flows from battery 14 into relay winding 13a, and when the winding is energized sufficiently, arm 13b moves from contact 130 to contact 13d. Then' current flows through the coil of autotransformer 16 causing a voltage drop across the coil. This, in turn, reduces the voltage drop across relay winding 13a by an amount sufficient to deenergize the winding and cause arm 13b to return to contact 13c. Switch 13 being opened stops the flow of current into autotransformer 16 which terminates the voltage drop thereon. Assuming that button 15 has remained depressed so that battery 14 still is connected across relay winding 13a, the winding is energized again causing arrn 13b to be moved again from contact 130 to contact 13d. The opening and closing of relay 13 will continue until switch 15 is opened.

The inductance of autotransformer 16 opposes any instantaneous change in the current so that at each instant that the circuit through relay 13 is opened, the current in transformer 16 is the same as when the relay l3 closed the circuit. The open relay contacts present a relatively high leakage resistance so the current stored in the winding of transformer 16 takes the path of least resistance which is the air gap between the arc-initiating electrodes in element 12. Relay 13 and autotransformer 16 both have resistance which aids in providing the alternate rise and fall of the field and arcing. The are resulting therefrom will ignite gases and other flammable mixtures, and the reason why the gap provides a smaller resistance will be described presently. The voltage waveform on leads 11a, 11b connected to the output coil portion of transformer 16 is a square wave, the pulses of which continue at regular in tervals as long as switch 15 is closed, the duration of each pulse being determined by the resistance and inductance of the winding in transformer 16. In other words, the igniter control or energizing circuit takes DC voltage from battery 14 and converts or chops it into a square wave voltage or pulsating DC voltage which appears on leads 11a, 11b.

By way of example, the electrical ratings of the various circuit components will be given from a circuit found to operate especially well. Battery 14 delivers 9 volts DC switch 13 is a Potter-Brumfield RSSD relay having a resistance of 2500 ohms and rated at 12 volts, and autotransformer 16 is a Stancor VO-l03. With these ratings, the current in the circuit is about milliamperes. The resistance of the open relay contacts is nearly infinite, and the electrodes in element 12 are spaced to provide a l/32-inch airgap. The instantaneous valve of the voltage developed is approximately 7,500 volts which produces an excellent arc across the gap. The structure of element l2 and operation thereof will-be described in detail further on in the specification. A preferred ratio for autotransformer 16 is 16:1, but the igniter of the present invention can operate with autotransformers having different ratios.

Igniter control or energizing circuit 10 can be provided with additional components or branches for performing auxiliary functions. As shown in FIG. 3 a solar cell 17 can be connected across battery 14, which in this case should be rechargeable. A solar cell designated SP9G13C and rated at 9 volts will keep rechargeable battery 14 charged and will charge at a rate of about 13 milliamperes in daylight. This renders the igniter maintenance free by eliminating the need for battery replacement, and thus makes its use especially advantageous in gasoperated street lamps, for example.

An indicator lamp 18 and series-connected resistance 19 can be connected in parallel with relay winding 13a as shown in FIG. 3. When switch 15 is closed, lamp 18 will glow if battery 14 is fully charged; and an absence of any glow in response to the closing of switch 15 will inform the operator that battery 14 is low and requires more charging time.

The igniter control or energizing circuit 10 shown in FIG. 3 will provide square wave output voltage pulses on line 11 as long as switch 15 is closed by the operator. In some applications, however, it would be desirable to have an igniter which will fire or provide a single output voltage pulse regardless of how long the control switch thereof is closed. Such an igniter is shown schematically in FIG. 4 and includes a control or energizing circuit 30, high voltage cable 31 and electrode containing element 32, the latter being identical to element 12 shown in FIG. 3.

Circuit 30 includes a first source of direct current in the form of battery 33, the positive terminal of which is connected through a manually operated switch 34 to a controlled switch in the form of relay 35, in particular to one end of the control winding 35a thereof. Relay 35 is identical to relay 13 included in the circuit of FIG. 3. The other end of relay control winding 35a is connected to the negative terminal of battery 33. A second source of direct current in the form of battery 36 and a resistor 37 are connected in series with each other and across battery 33. In particular, the negative terminals of batteries 36 and 33 are connected together, the positive terminal of battery 36 is connected to one terminal of resistor 37, and the other resistor terminal is connected to the positive terminal of battery 33. The positive terminal of battery 36 is connected through a lead 38 to the movable contact arm 35b of relay 35. A solar cell 39, identical to solar cell 17 included in the circuit of FIG. 3, can be connected across battery 36 in which case both batteries 33 and 36 should be of the rechargeable type.

Circuit 30 further includes an autotransformer 40 having winding taps or terminals 40a, 40b and 400. Autotransformer 40 is identical to autotransformer 16 included in the circuit of FIG. 3 and includes an input coil portion between terminals 40a and 40b and an output between taps 40a and 40c of the coil. Winding terminal 40a is connected to relay contact 35d and winding terminal 40b is connected to the negative terminals of batteries 33 and 36. The output coil portion of autotransformer 40 is connected to element 32 through high voltage cable 31. In particular, winding terminal 40a is connected to one of the arc-initiating electrodes in element 32 by lead or wire 31a of cable 31 and winding terminal 400 is connected by lead or wire 31b to the other arc-initiating electrode in element 32. If desired, an indicator lamp 41 and series-connected resistance 42 can be connected between autotransformer winding terminals 40a and 40b as shown in FIG. 4.

The circuit of FIG. 4 operates in the following manner. When switch 34 is closed, relay control winding 35a is energized causing arm 35b to move from contact 35c to contact 35d whereupon autotransformer 40 is energized. In particular, current flows to the winding of transformer 40 through lead 38 from the point common to the positive tenninal of battery 36 and one terminal of resistor 37. An output voltage appears on leads 31a, 31b and causes an arc discharge between the electrodes in element 32. Because autotransformer 40 is energized from one battery, in particular battery 36, and from one end of resistor 37, the voltage across both batteries 33 and 36 remains at the samelevel which is sufficient to keep relay 35 energized. With batteries 33 and 36 both rated at 9 volts, with switch 35 a Potter-Brumfield R55D relay having a resistance of 2500 ohms and rated at 12 volts, and with autotransformer a Stancor VO-103, a satisfactory value for resistor 37 was found to be 570 ohms. .With these ratings the current in the circuit is about milliamperes, and the instantaneous value of the voltage developed across the 1/32-inch airgap between the arc-initiating electrodes in element 32 is approximately 7,500 volts which produces an excellent arc.

FIG. 5 shows in detail a preferred form of the element which houses the arc-initiating electrodes and functions to trap a small, ignitable quantity of gas, which element is designated schematically at 12 and 32 in FIGS. 3 and 4, respectively. The element comprises a first or inner conductor in the form of steel rod 50, a second or outer conductor in theform of steel sleeve 51, the two conductors having an insulating medium therebetween in the form of ceramic sleeve 52;and spacing the conductors apart a distance'equal to the desired airgap which as previously mentioned is about one thirty-second inch. Conductors 50 and 51 function as arc-initiating electrodes. The

element further comprises a gas receiving chamber 53 in which the arc exists which chamber in this embodiment is defined by sleeve 51 which extends a short distance beyond the coterminal ends of rod 50 and insulator sleeve 52. Sleeve 51 is provided with ports 54 at the end thereof which communicate with recess 53, and this end of the element would be positioned in a stream of gas or other flammable mixture which is to be ignited.

An arrangement for providing an electrical connection to sleeve 51, which preferably is the ground or low potential electrode and rod 50, which preferably serves as the high potential electrode, is shown also in FIG. 5. A disc or plate 55 and T-shaped coupling element 56 are threadably connected on sleeve 51 at the other end thereof. Coupling 56 and plate 55 are both of electrically conducting material, the latter serving to connect sleeve 51v to ground. For example when the ig' niter is used in combination with a gas cooking grill as shown in FIG. I, sleeve 51 extends through the housing to position recess 53 in the gas stream to the grill burner element, and plate 55 is in contact with the grill housing which serves as an electrical ground. A connector element 57 of electrically conducting material, to which the low potential lead of high voltage cable 11 or 31 is connected, is threadably connected in coupling 56. A conductor rod 58, to which the cable high potential lead is connected, is provided with an outer jacket or sleeve 59 of insulating material and extends through connector 57 and into the hollow interior ofT coupling 56 where it is connected by means of a tab and screw to the end of conductor rod 50 as shown in FIG. 5.

When the end of the element including recess 53 is positioned in a stream of gas or other flammable mixture, a small ignitable quantity thereof is collected or trapped by recess 53 which collection is facilitated by the ports 54 provided in sleeve 51. Sleeve 51 is spaced from rod 50 so as to provide a l/32-inch airgap which, as previously described, with an operating current of about 15 milliamperes provides about 7500 volts across the gap which results in a satisfactory arc. The cable connecting the element shown in FIG. 5 with the ig niter control or energizing circuit shown in FIGS. 3 or 4 should be capable of withstanding about 10,000 volts.

The igniter provided by the present invention thus operates satisfactorily on a relatively low current of about 15 milliamperes which makes it completely safe for use in devices or appliances often touched by humans. In addition, the fact that the igniter is powered by one or two 9-volt batteries renders it light in weight and completely portable. The components included in the circuits designated 10 and in FIGS. 3 and 4,

respectively can be included in a plastic case having the approximate dimensions of 3.75 inches by 6.0 inches by 2.0 inches.

FIGS. 6 and 7 show two electrical circuits wherein the igniter provided by the present invention is operatively connected to the controls of the device or appliance in which it is included. As shown in FIG. 6, an igniter energizing circuit 70 comprises a first source of direct current in the form of battery 71, the positive terminal of which is connected through a manually operated switch 72 to a controlled switch in the form of relay 73, in particular to one end of the control winding 73a thereof. The other end of control winding 73a is connected to the'negative terminal of battery 71. A second source of direct current in the form of battery 74 and a resistor 75 are connected in series with each other and across battery 71. In particular, the negative terminals of batteries 71 and 74 are connected together, the positive terminal of battery 74 is connected to one terminal of resistor 75, and the other resistor terminal is connected to the positive terminal of battery 71. The positive terminal of battery 71 also is connected through switch 72 to the movable contact arm 73b of relay 73.

Circuit 70 further comprises an autotransformer 76 having winding taps or terminals 76a, 76b and 760, wherein an input coil portion is included between terminals 76a and 76b and an output coil portion between terminals 76a and 76c, the ratio again being about 16:1. Winding terminal 76a is connected to relay contact 73d, and winding terminal 76b is connected to the negative terminals of batteries 71, 74. The output coil portion is connected to an element 77 housing arc-initiating elec trodes and adapted to expose the electrodes to an ignitable quantity of gas, the element 77 being connected by a high voltage cable 78 to transformer 76. In particular, winding terminal 76a is connected to one of the electrodes in element 77 by lead or wire 78a of cable 78 and winding terminal 760 is connected by lead or wire 78b to the other electrode in element 77. A pilot or indicator lamp 79 can be connected across winding terminals 76a and 76b.

The energizing circuit 70 is connected to a solenoid-.

operated valve 80 which controls the flow of gas or other flammable mixture. In particular, the positive terminal of battery 74 and one side of resistor 75 are connected by a lead 81 through a manually operated switch 82 to one end of the winding of valve 80. The other end of the winding of valve 80 is connected through aresistor 83 to the negative terminals of batteries 71 and 74.

The circuit of FIG. 6 thus allows valve 80 which controls the flow of gas or other flammable mixtures in a device or appliance and igniter energizing circuit 70 to be powered electrically from a single source. In operation, switch 82 would be closed to complete a circuit including battery 74, the coil or winding of valve 80 and resistor 83. Igniter switch or button 72 is then depressed to operate the igniter in the manner described in connection with the circuit of FIG. 3. Arcing will be sustained between the electrodes of element 77 as long as switch 72 is closed. Valve 80 having been opened in response to the closing of switch 72 provides a flow of gas or other flammable mixtures for ignition.

In the circuit of FIG. 6, batteries 71 and 74 can have a 9-volt rating, relay 73 can be identical to relays 13 and 35 in the circuits of FIGS. 3 and 4, respectively. A suitable value for resistor 75 was found to be 570 ohms, the magnitude of resistor 83 depending upon the electrical characteristics of valve 80. Element 77 can be constructed in the manner shown in FIG. 5.

In the circuit of FIG. 7, an igniter energizing circuit comprises a source of direct current in the form of transformer 91 having a primary winding 92 and a secondary winding 93, and a rectifier consisting of series-connected diodes 94, 94a and capacitor 95, the source of direct current being connected through a manually operated switch 97 to a controlled switch in the form of relay 98. Transformer primary winding 92 is adapted for connection to a source of alternating current in the voltage range of about 24 to 440 volts. One end of secondary winding 93 is connected to the anode of diode 94, the

cathode of diode 94a being connected to one terminal of capacitor 95 and to switch 97. The other terminal of capacitor 95 is connected to the other end of transformer secondary winding 93. Switch 97 is connected to one end of relay control winding 98a. the other end of which is connected to the point common to capacitor 95 and secondary winding 93. The contact arm 98b of relay 98 is connected through switch 97 to the point common to diode 94a and capacitor 95. Energizing circuit 90 further comprises an autotransformer 99 having winding taps or terminals 99a, 99b and 990. An input coil portion is included between terminals 99a and 99b, and an output coil portion is included between terminals 99a and 99c, the winding ratio again being about 16:1. Winding terminal 99a is connected to relay contact 98d, and winding terminal 99b is connected to the point common to transformer secondary winding 93 and capacitor 95. The output coil portion is connected to the point common to transformer secondary winding 93 and capacitor 95. The output coil portion is connected to an element 100 housing arc-initiating electrodes and adapted to expose the electrodes to an ignitable quantity of gas, the element 100 being connected by a high voltage cable 101 to transformer 99. In particular, winding terminal 99a is connected to one of the electrodes in element 100 by lead or wire 1010 of cable 101 and winding terminal 1010 is connected by lead or wire l01b to the other electrode in element 100. A pilot lamp 102 and series-connected resistance 103 can be connected across winding terminals 990 and 99b as shown in FIG. 7. v

The energizing circuit 90 is operatively connected to a solenoid-operated valve 104 which controls the flow of gas or other flammable mixture. In particular, one end of transformer secondary winding 93 is connected by a controlled switch in the form of relay 105, winding 93 being connected to contact arm 105b, to one end of the winding of valve 104. The other end of the winding of valve 104 is connected through a resistor 106 to the other end of transformer secondary winding 93. Electrical power to operate valve 104 and control the flow of gas thus is obtained from transformer 91 under control of switch or relay 105.

The controlled switch 105 is connected in controlled relation to igniter energizing circuit 90 in the following manner. One end of relay control winding 105a is connected by a lead 107 to contact 98d of controlled switch or relay 98 of energizing circuit 90. This same end of winding 105a is connected by lead 108 and a normally open, thermally responsive switch 109 to the point common to capacitor 95 and the cathode of diode 94a, in other words to the DC side ofthe power supply.

The circuit of FIG. 7 operates in the following manner. The manually operated igniter switch is closed causing igniter energizing circuit 90 to provide an arc between the electrodes in element 100. The arcing will continue as long as switch 97 is closed, energizing circuit 90 operating in a manner similar to energizing circuit 10 shown in FIG. 3. When contact arm 98b of relay 98 is moved into engagement with contact 98d to supply direct current to autotransformer 99, current flows also through lead 107 and into relay control winding 105a with the result that contact arm 10512 is moved into engagement with contact 105d. A circuit thus is completed including transformer secondary winding 93, the coil or winding of solenoidoperated valve 104 and resistor 106. As a result, valve 104 opens causing a flow of gas or flammable mixture which is ignited by the electrical arc discharge in element 100. After ignition occurs, the resulting heat closes thermally responsive switch 109 to keep relay coil 105a energized so that valve 104 is continued to be supplied with electrical power. Should ignition fail to occur or the burning cease, switch 109 opens to deenergize relay 105 causing valve 104 to close.

It was found that the two series-connected diodes 94, 94a provide a better smoothing action in the rectifier as compared to a single diode. A suitable value for capacitor 95 is 30 pi, and relay 98 and autotransformer 99 are identical to relay 13 and autotransformer 16 respectively, included in the circuit of FIG. 3. Relay 105, in turn, can be identical to relay 98. Element can be constructed in the manner shown in FIG. 5, and the value of resistor 106 will vary depending upon the electrical characteristics of valve 104.

Iclaim:

1. An electrically operated igniter for gas and other flammable mixtures comprising:

a. an electrically controlled switch adapted to be connected in controlled relation to a source of direct current;

b. an autotransformer having input and output coil portions;

c. the input coil portion of said autotransformer being connected to said controlled switch and the source of direct current in a manner whereby the source is in series with the input coil portion when said controlled switch is closed; and

d. an element containing a pair of arc-initiating electrodes connected in series with the output coil portion of said autotransformer, said element adapted to expose the electrodes to an ignitable quantity of gas or other flammable mixture.

2. The igniter defined in claim 1 wherein said electrically controlled switch comprises a relay, the contacts of which are connected in series with said autotransformer input coil portion and the control winding of which is adapted to be connected across the source of direct current.

3. The igniter defined in claim 2 further including a battery connected across the control winding of said relay and a manually operated switch connected in series with said battery and said relay control winding.

4. The igniter defined in claim 3 wherein said battery is rechargeable and wherein said igniter further includes a solar cell connected across said battery and an indicator lamp and series-connected resistance connected across the control winding of said relay.

5. The igniter defined in claim 2 further including a first battery and a manually operated switch connected in series with each other and together across the control winding of said relay, a second battery and a resistance connected in series with each other and together across said first battery, and means connecting one contact of said relay to the point common to said resistance and said second battery.

6. The igniter defined in claim 5 further including a solar cell connected across said second battery.

7. The igniter defined in claim 1 wherein said element containing arc-initiating electrodes comprises:

a. a rod of electrically conducting material defining a first arc-initiating electrode;

b. a sleeve of insulating material surrounding said rod; and

c. a sleeve of electrically conducting material surrounding said insulating material and extending axially a short distance beyond said rod and said insulating sleeve to define a chamber, said conducting sleeve defining a second arc-initiating electrode.

8. The igniter defined in claim 7 wherein a plurality of ports are provided in said sleeve of conducting material and communicating with said chamber.

9. The igniter defined in claim 5 further including a solenoid-operated valve operatively connected to said second battery and said resistance.

10. In combination:

a. an electrically operated valve for controlling the flow of gas or other flammable mixtures;

b. an element containing a pair of arc-initiating electrodes and adapted to expose the electrodes to an ignitable quantity of gas or other flammable mixtures;

c. a transformer having a primary winding adapted to be connected to a source of alternating current and having a secondary winding;

d. a rectifier connected to the secondary winding of said transformer;

e. a first electrically controlled switch adapted to be connected in controlled relation to said rectifier;

f. an autotransformer having input and output coil portions, said input coil portion being connected to said controlled means connecting the arc-initiating electrodes in said element in series with said autotransformer output coil portion; and

. a second controlled switch connected to said transformer secondary winding and said valve for completing a circuit between said transformer and said valve, said second controlled switch being connected in controlled relation to said autotransformer.

11. The combination defined in claim 10 further including a thermally responsive switch for connecting said rectifier in controlling relation to said second controlled switch.

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