US3318358A

US3318358A - Burner igniter system

Info

Publication number: US3318358A
Application number: US531906A
Authority: US
Inventors: William F Potts
Original assignee: Liberty Combustion Corp
Current assignee: Liberty Combustion Corp
Priority date: 1966-03-04
Filing date: 1966-03-04
Publication date: 1967-05-09
Anticipated expiration: 1984-05-09

Description

May 9, 1967 w, P s 3,318,358

BURNER IGNI TER SYSTEM Filed March 4, 1966 2 Sheets-Sheet 1 err INVENTOR. WILLIAM F. POTTS BY BM M-9- ang May 9, 1967 w. F. POTTS 3,318,358

BURNER IGNITER SYSTEM Filed March -l, 1966 2 Sheets-Sheet 2 /NVEN TOR WILLIAM F. POTTS United States Patent 3,318,358 BURNER IGNITER SYSTEM William F. Potts, Ottawa, Ontario, Canada, assignor to Liberty Combustion Corporation, Syracuse, N .Y., a corporation of New York Filed Mar. 4, 1966, Ser. No. 531,906 7 Claims. (Cl. 158-28) This invention relates to an electrical system for the ignition of a fluid fuel burner andmore particularly to a system in which ignition is obtained by an electronically produced spark.

In electrical ignition systems for oil and gas burners it is important to assure reliable, non-critical ignition initially, when the burner is first turned on. In the event that the burner is inadvertently extinguished for whatever reason while the gas or other fuel remains on, it is important that dependable re-ignition be provided for. Furthermore, it is important that the ignition system operate with minimum periods of operation and current flow and that the system be simple and inexpensive. The present invention contemplates the use of high voltage spark discharges for igniting the fuel at the burner, the discharges being produced repetitively at the supply line frequency. Alternative system arrangements provide for various system parameters. In some arrangements, more slowly recurring spark discharges may be produced after the initial ignition, the reduced spark rate being adequate to re-ignite the burner in case of extinction of the flame while the burner is turned on, thus reducing the duration of periods of operation of the ignition system and thereby increasing the life of the system and decreasing the current drawn from the electrical power source. This reduction in rate may 'be produced manually or automatically. In another arrangement automatic means is provided for shutting off the ignition and the flow of fuel to the burner should the burner fail to ignite in a predetermined period and to again recycle the ignition arrangement after another predetermined period.

The primary object of the present invention is to provide electronic means for producing a rapidly repetitive high voltage spark discharge at the burner.

Another important object is to provide a less rapid repetitive spark discharge after initial ignition of the burner.

Still another object is to provide means for automatic cessation of the flow of fuel to the burner and the repetitive ignition spark should ignition not be obtained.

Other objects and advantages will become apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a schematic circuit diagram of the sparkproducing circuit according to the invention in a simple manually controlled system;

FIGURE 2 is a diagram similar to FIGURE 1 and including a relaxation oscillator for triggering purposes which is controlled by a manually operated switch;

FIGURE 3 is a diagram similar to FIGURE 2 in Which the relaxation oscillator is automatically controlled by heat sensing means; and

FIGURE 4 is a diagram similar to FIGURE 1 and including time delay shut-off means for the spark and fuel together with flame-sensing means for control thereof.

With reference to FIGURE 1, the spark producing circuit includes terminals 11 and 12 which are connected to the wires of an alternating current line, typically 110 volts. Terminal 11 is connected through a manually operated switch 13 in a series combination to the anode of a rectifier 14 Whose cathode is connected through a current limiting resistor 15 to one terminal of a capacitor 16 for purposes of charging the capacitor. The other "ice terminal of capacitor 16 is connected through the primary winding of a transformer 17 to a reference point 18 and thence to the other line terminal 12.

Each terminal of the secondary winding of transformer 17 is connected to a respective electrode of a spaced pair of electrodes forming a spark gap at 19 in proximity to a gas burner 20. One electrode at the spark gap is grounded and may be the burner itself for convenience sake, as shown. Burner 20 is supplied through the fuel line 21 which is provided with a manually operated shutoff valve 22 whose handle is shown at 23.

Since the sparking device of the present invention may equally well .be used for igniting an oil flame, burner 20 might be shown as an oil burner provided with a blower in its fuel supply, the motor for the blower being provided with a control switch. Additional spark gaps wired in series with the electrodes at 19 may be provided if there is more than one burner.

The junction of resistor 15 and capacitor 16 is connected to the anode 24 of a silicon controlled rectifier 25. The cathode 26 and the gate terminal 27 thereof are each separately connected to the reference point 18 in the connection between line terminal 12 and the primary winding of transformer 17, the cathode being connected through the anode-cathode combination of another rectifier 28 so that a discharge path for capacitor 16 is set up through rectifier 25, rectifier 28 and the primary of transformer 17.

Cathode 26 of rectifier 25 is also connected through another resistor 29, for limiting current in the gate circuit, to the junction between switch 13 and the anode of rectifier 14 for connecting cathode 26 to line terminal 11. A state of conduction of the silicon controlled rectifier 25 is produced in response to voltage being supplied between its gate 27 and its cathode 26, the polarity of the voltage being such that the gate is positive with respect to the cathode. The magnitude of this voltage is sufiicient to cause adequate current flow between gate 27 and cathode 26 necessary to allow the anode 24 and cathode 26 combination to become conductive.

In operation, the switch 13 is first closed and then gas supply valve 22 opened by turning handle 23. lmmediately upon closing the switch a path to charge capacitor 16 is set up as soon as the polarity of terminal 11 becomes positive with respect to terminal 12, through the series combination of terminal 11, the closed switch 13, the anode and cathode of rectifier 14, resistor 15, capacitor 16, the primary winding of transformer 17, to terminal 12.

Upon terminal 12 of the supply voltage becoming positive with respect to terminal 11 positive voltage is sup plied to the gate terminal 27 of the silicon controlled rectifier by reason of its connection to terminal 12 through reference point 18. Negative voltage is supplied at the same time from terminal 11, through the closed switch 13, and resistor 29 to the cathode of rectifier 25. When the voltage differential between terminal 12 and terminal 11 reaches a suflicient magnitude it will cause adequate current flow between gate 27 and cathode 26 of the rectifier 25 and allow conduction between anode 24 and cathode 26 and a discharge path is set up for capacitor 16 from the positively charged terminal of the capacitor through anode 24, cathode 26, anode and cathode of rectifier 28, reference point 18 and through the primary winding of transformer 17 through its connection to the other terminal of the capacitor.

Capacitor 16 having been charged to the peak value of the supply line voltage during the previous half-cycle period when terminal 11 was positive with respect to terminal 12, it is now discharged through the primary winding of transformer 17 and a high voltage is induced in the transformer secondary winding which causes a high voltage spark to jump across the gap at 19.

During the next cycle in the supply line voltage the same half-cycle charging of capacitor 16 and subsequent half-cycle discharge of the capacitor through the transformer 17 takes place. In this fashion a rapidly repetitive spark at the gap 13 is produced at the same rate as the supply line frequency, typically sixty per second. This high voltage sparking continues until switch 13 is opened.

In FIGURES 2 and 3 modifications of the circuit are shown with provision for an initial high sparking rate when the switch is first turned on and then a sparking rate less rapid for so long as the burner is burning after the flame is first lit.

FIGURE 2 shows the circuit 30 in which the elements shown in FIGURE 1 and identified by the same reference numbers are present except that a double pole triple throw switch 31-32-33 takes place of switch 13 and provision has been made in the connection of gate terminal 27 of silicon controlled rectifier 25 to the line terminals to provide for a reduced sparking rate. I

The

blades

31 and 32 and the manual control handle 33 of the switch 31-32-33 have three positions denoted Ignite, Burn and Off, respectively, in that order from top to bottom. The switch is arranged to be springbiased in its Ignite position toward the Burn position. Blade 31 of the switch is connected to line terminal 11 and both the Ignite contact 31a, which is in contact with blade 31 when the switch is in Ignite position, and the .Burn contact 31b, which is in contact with this blade when the switch is in its Burn position, are connected to the anode of rectifier 14 whose cathode is connected through resistor 15 to one terminal of the capacitor 16. The other terminal of the capacitor is connected through the primary winding of transformer 17 to reference point 18 and thence to the line terminal 12 so that, during the first half-cycle while terminal 11 is positively charged, the capacitor 16 becomes charged.

Each terminal of the secondary winding of transformer 17 is connected to a respective spark electrode at gap 19 in close proximity to the burner 20. The burner is supplied with fuel from the line 21 controlled by handle 23 of the valve 22.

The junction of resistor 15 and capacitor 16 is connected to the anode 24 of rectifier 25 and the cathode 26 of this rectifier is connected through the anode-cathode combination of rectifier 28 to reference point 18.

The gate terminal 27 of rectifier 25, however, is connected through another resistor 35 to one terminal of a breakdown device comprising a neon tube 36'. The other terminal of tube 36 is connected to one terminal of another capacitor 37 and, through still another resistor 38, to the cathode of a rectifier 39 whose anode is connected to reference point 18.

The other terminal of capacitor 37 is connected to cathode 26 and is also connected through resistor 29 to both contacts 31a and 31b of the switch.

The gate terminal 27 of rectifier 25 is also connected to the contact 32a with which blade 32 of the switch makes contact when it is in its Ignite position. Blade 32 of the switch is connected to line terminal 12.

In operation, when switch 31-32-33 is turned manually to its Ignite position and valve 22 is turned on, a capacitor charging circuit is set up when a first half-cycle in the line renders terminal 11 positive, terminal 11 being connected through blade 31, contact 31a, rectifier 14 and resistor 15 to one terminal of capacitor 16. The other terminal of this capacitor is connected through the primary of transformer 17 to reference point 18 and the other line terminal 12.

Upon terminal 12 becoming positive with respect to terminal 11, positive voltage is applied from terminal 12, through blade 32, and switch contact 32a, to the gate terminal 27 of the rectifier 25. Negative voltage is applied from terminal 11 through blade 31, switch contact 31a, and resistor 29 to the cathode 26 of rectifier 25 and when the difference in potential is great enough rectifier 25 becomes conductive. A path for the discharge of capacitor 16 is thus set up through anode 24, cathode 26, rectifier 28, reference point 18 and the primary winding of transformer 17 just as described in connection with FIGURE 1. A rapidly repetitive spark is produced at the gap 19 and, when valve 22 is turned on, a flame is initiated at the burner 20.

When the burner is lit, handle 33 is released and, by reason of the spring bias on switch 313233, blade 31 moves into contact with cont act 31b and blade 32 moves from contact with contact 32a to an open position.

Now the charging of capacitor 16 takes place as before, this time through blade 31 and contact 31b, but the discharge during the second half-cycle is initiated in a different manner because blade 32 has broken from contact 32a. As terminal 12 becomes positive its potential is connected through reference point 18, rectifier 39 and resistor 38 to one terminal of the neon tube 36 and one terminal of the capacitor 37. The other terminal of capacitor 37 is connected through resistor 29, contact 31b, and blade 31 to line 11 so that capacitor 37 is charged incrementally during a plurality of second half-cycle until it reaches the firing voltage of the neon tube 36.

When the tube 36 fires, positive voltage is applied to the gate terminal 27 from tube 36 through resistor 35. Negative voltage is continually applied during the second half-cycle from terminal 11 through blade 31, contact 31b, and resistor 29 to the cathode 26 of rectifier 25 and to the other terminal of capacitor 37.

When the built-up positive voltage from the neon tube 36 is applied to gate terminal 27, current flows between gate 27 and cathode 26 placing the silicon controlled rectifier in a conductive state. Capacitor 16 will then discharge through rectifier 25, rectifier 28, reference point 18 and the primary winding of transformer 17, in-

ducing a sparking voltage in the transformer secondary and across the gap at 19.

When the capacitor 37 has been discharged so that its voltage falls below the minimum voltage required by the breakdown device 36 to remain ionized, the tube 36 will cease to conduct current and current will cease to flow between gate 27 and cathode 26 and rectifier 25 will no longer be conductive. The triggering of the silicon controlled rectifier 25 is thus dependent upon the time constant determined primarily by the value of resistor 38 and capacitor 37. Resistor 35 serves as a current limiting resistor to limit current flow through tube 36 and the gate 27-cathode 26 section of rectifier 25 ,to a safe value.

The next spark at gap 19 will occur when capacitor 37 has again been sufficiently charged so that its voltage causes breakdown device 36 to again conduct current. In practice, the reduced sparking rate may be arranged to provide spark rates varying from once each fraction of a second to as much as once every 30 seconds. This sparking at reduced rate will continue until handle 33 of the switch is turned to Off position.

Much the same result may be obtained automatically by the addition of a thermo-couple operated'relay instead of the manual switch 31-3233 as shown in the circuit 40 shown in FIGURE 3.

A capacitor charging series combination in FIGURE 3, like that shown in FIGURE 1, comprises the terminal 11 being connected through the normally open manual switch 13 to rectifier 14, and resistor 15, in that order, to one terminal of capacitor 16, the other capacitor terminal being connected through the primary winding of transformer 17 to reference point 18 and thence to terminal 12.

The junction between switch 13 and rectifier 14 is connected through a resistor 29 to one terminal of a capacitor 37 and to the cathode 26 of a silicon controlled rectifier 25, just as in the circuit 30 of FIGURE 2. The

j'unction of resistor 15 and capacitor 16 is connected to the anode 24 of rectifier 25 and the cathode 26 thereof is connected through a rectifier 28 to reference point 18, as shown.

The gate terminal 27 of rectifier 25 is connected to one terminal of the neon tube breakdown device 36 through resistor 35 and the other terminal of tube 36 is connected to the other terminal of capacitor 37 and also, through resistor 38 and the cathode-anode of rectifier 39, in that order, to reference point 18, just as in FIGURE 2.

Gate 27, instead of being connected to a line terminal through the manual switch of FIGURE 2, is connected to reference point 18, and therefore to terminal 12, through the normally closed contacts 41-42 of a relay 43.

Relay 43 is operated by a thermocouple 44 connected to the coil 45 of relay 43 and having its heat sensing portion 46 located in proximity to the burner 20. Thermocouple 44 is operated by heat at the burner to open the

relay contacts

41 and 42.

Burner 20 is supplied through line 21 having a control valve 22 just as in the other figures. Also in proximity to burner 20 is a gap 19 having its terminals connected respectively to the terminals of the secondary winding of transformer 17.

In operation, when switch 13 is closed, during the first half-cycle capacitor 16 is charged as described above. During the second half-cycle, gate 27 of the rectifier 25 is supplied with positive voltage through the

closed contacts

41 and 42 of the relay from reference point 18 and line terminal 12.

Cathode 26 is connected through resistor 29 and the closed switch 13 to the other line terminal 11 so current flows between cathode 26 and gate 27 rendering the anode 24-cathode 26 combination conductive and a peak voltage discharge of capacitor 16 takes place through transformer 17 and initially a rapidly recurring spark is induced at the gap 19, as described above.

However, when a flame is ignited at burner 20, the sensing portion 46 of thermocouple 44 is heated and operates the relay to break the circuit between

contacts

41 and 42. Now the only connection between gate 27 and terminal 12 is through the series combination of resistor 35, tube 36, resistor 38, the cathode-anode combination of rectifier 39, reference point 18, and terminal 12. Tube 36 requires the triggering circuit including capacitor 37 in order to operate, as described in connection with FIG- URE 2, so that after burner 20 is ignited the recurring spark at gap 19 is induced at a slower rate.

The spark, even at the reduced rate, is suflicient to reignite the flame at burner 20 should it he accidentally exinguished. Should the flame go out because of a defect in the supply line, cooling of the thermocouple again closes

contacts

41 and 42 producing sparking at the higher or ignition rate which may be clearly heard by a person standing near.

In one specific form of the invention the elements used in the circuit 40 were:

Capacitor 16 2 microfarads, 200 volts. Capacitor 37 5 micnofarads, 200 volts. Rectifier 14 200 milliamperes, 200 volts. Rectifier 28 200 milliamperes, 200 volts. Rectifier 39 200 milliamperes, 200 volts. Resistor 15 150 ohms, 5 watts, Rectifier 29 10,000 ohms, 10 watts, 10%. S.C. rectifier 25 200 volts, 7.2 ampere R.M.S. Switch 13 Single pole, double throw. Transformer 17 Miniature ignition coil. Resistor 35 10,000 ohrns, /2 watt, 10%. Resistor 38 1 megohm, /2 watt, 10%. Neon tube 36 Type NE-83.

In still another modification, shown in FIGURE 4, time delay safety means are provided for shut down of the system when the burner fails to ignite and flame sensing means are provided at the burner for preventing the shut down of the system when the burner is properly ignited.

In circuit 50, the terminal 11, of the pair of line terminals 11-12, is connected through a switch 51, which may be thermostat-operated, to a heater switch 52 having normally closed contacts 53, 53 arranged, by the use of a bimetal contact arm, for instance, to open when subjected to heat. The series connection through contacts 53 to terminal 11 is then connected through the heater coil 54 of switch 52 to reference point 55. Heater coil 54 is disposed near contacts 53 and arranged to open the contacts after current flows through the coil for a predetermined time.

Reference point 55 is connected, through the coil 56 of a solenoid operated control valve 57 in the fuel supply line 21 to burner 20, to a reference point 18 and thence to line terminal 12.

A by-pass connection is provided for heater coil 54 of switch 52 by connecting the junction between contacts 53 and coil 54 to reference point 55 through the normally open contacts 59 of a relay 60.

For operating relay 60, a series combination is made by connecting reference point 55 through the coil 61 of relay 60 to one terminal of a flame sensing device 62, the other terminal of the device being connected to reference point 18. Device 62 is a cadmium sulfide cell sensitive to yellow light and characterized by having its internal resistance reduced when subjected to light sufliciently to allow enough current to flow through coil 61 to operate the relay and close contacts 59.

The remainder of circuit 50 is similar to circuit 10 shown in FIGURE 1, and has the same component elements indicated by the same reference numbers. Reference point 55 is connected to the anode of rectifier 14, its cathode being connected through resistor 15 to one terminal of the capacitor 16. The other terminal of capacitor 1-6 is connected through the primary winding of transformer 17 to reference point 18 which is connected to line terminal 12.

The secondary Winding of transformer 17 has each terminal connected to a respective electrode at gap 19 adjacent the burner 20.

The junction of resistor 15 and capacitor 16 is connected to the anode 24 of the silicon controlled rectifier 25 whose cathode 26 is connected through the anodecathode combination of rectifier 28 to reference point 18. Cathode 26 is also connected through resistor 29 to reference point 55.

The gate terminal of rectifier 25 is connected directly to reference point 18.

In operation, when switch 51 is closed, either manually or thermostatically, line current is applied from terminal 11 through contacts 53 and coil 54 of the heater switch 52 and through the solenoid coil 56 of valve 57 which, in turn is connected through reference point 18 to terminal 12. Upon operation of solenoid 56, the valve 57 is opened and fuel is supplied to the burner 20.

At the same time, during the first half-cycle, voltage is applied to one terminal of capacitor 16 from terminal 11, through switch 51, contacts 53, coil 54, reference point 55, rectifier 14, and resistor 15. Voltage from the other terminal 12 is applied to the other terminal of capacitor 16, through reference point 18, and the primary winding of transformer 17.

At the next half-cycle, voltage from terminal 11 is applied to cathode 26 of rectifier 25 through reference point 55 and resistor 29. At the same time voltage from terminal 12 is applied to gate terminal 27 through reference point 18. When the voltage differential is sufficient current passes through the gate 27-cathode 26 combination and rectifier 25 becomes conductive. Capacitor 16 discharges through the primary of transformer 17, reference point 18, rectifier 28, cathode 26, anode 24 to capacitor 16. As current passes through transformer 17 a high voltage spark is induced at the gap 19 from the secondary winding of the transformer, the spark rapidly recurring at line frequency, and burner 20 is ignited.

Should the burner not become ignited before coil 54 the switch 52 heats up, the contacts 53 of the switch separate and the circuits to both the solenoid of valve 57 and to the transformer 17 are interrupted until coil 54 cools.

Should the burner 20 be ignited, the device 62 becomes conductive and a circuit is completed from reference point 55 through relay coil 61, device 62, reference point 18, and terminal 12 and relay 60 is operated. Operation of the relay closes the contacts 59 providing -a by-pass around coil 54 from the contacts 53, closed contacts 59 to reference point 55, thus preventing the opening of contacts 53 once flame is sensed by the device 62, unless the flame is extinguished and the circuit through the device 62 is thereby interrupted.

While the contacts 53 are closed the sparking at gap 19 continues and valve 57 remains open. Should the flame become extinguished for any reason it will be reignited unless reignition does not take place within the time delay period in which coil 54 is adapted to open contacts 53, since the contacts 59 of relay 60 are now open.

It will be apparent that the rectifiers, resistors, capacitors, transformers and tubes of the above described circuits may conveniently be housed in a small space and connected in a variety of heating or other flame-control systems.

As will be apparent to those familiar with the art, the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The embodiments disclosed therefore are to be considered in all respects as illustrative, rather than restrictive, the scope of the invention being indicated by the appended claims.

What is claimed is:

1. An electrically operated igniter device for a burner having a fluid fuel supply, comprising: a source of alternating electric current; a transformer; a first series combination of one source terminal, a switch, the anode and cathode of a first rectifier, and a firs-t resistor connected in that order to one terminal of a capacitor; a second series combination of the other terminal of the capacitor and the primary winding of the transformer connected in that order through a point of reference potential to the other source terminal; a silicon controlled rectifier having its anode connected to the junction of the first rectifier and the capacitor, having its gate terminal connected to the point of reference, and having its cathode connected through the anode and cathode, in that order, of a second rectifier to the point of reference, the cathode of the silicon controlled rectifier being also connected through a second resistor to the junction of the switch and the first rectifier; and spaced electrodes adapted to be fixed in proximity to the burner, said electrodes being'in series circuit with the secondary winding of the transformer, one electrode being grounded, and the electrodes forming therebetween a gap for a rapidly recurring spark for igniting the burner whenever the switch is closed.

2. A flame ignition system, comprising: fluid fuel burner means; means for controlling the supply of fuel to the burner; spaced electrodes forming a spark gap disposed adjacent the burner, one electrode being grounded; a transformer having its high voltage secondary winding connecting the electrodes in series, one terminal of the primary winding of the transformer being connected in a first series combination of a capacitor, the anode of a silicon con-trolled rectifier, the cathode of said rectifier, the anode of a first diode rectifier, and the cathode of the first diode rectifier, in that order, the other terminal of the primary winding being connected to the cathode of the diode rectifier; the gate electrode of the silicon controlled rectifier being connected to the cathode of the first diode rectifier; a second series combination of a first resistor, the cathode of a second diode rectifier, the anode of the second rectifier, and a second resistor connected in that order from the anode to the cathode of the silicon controlled rectifier; and a course of alternating current, the anode of the second diode rectifier being connected through a switch across the source to the cathode of the first diode rectifier.

3. The flame ignition system defined in claim 2 characterized by having the fuel control means operable by a solenoid operated valve; having a third series combination including the anode of the second diode rectifier, the solenoid coil and the cathode of the first diode rectifier connected in that order; having the heater coil and the normally closed heat responsive contacts of a timer switch included in series in that order in the connection between the anode of the second diode rectifier and the cathode of the first diode rectifier across the source and disposed between the second diode anode and the switch; having a fourth series combination including a pair of normally open relay contacts connecting the junction between the heat responsive contacts and the heater coil to the anode of the second diode rectifier; having a flame sensing device adjacent the burner, the device being normally nonconductive and being conductive when subjected to light; and a fifth series combination of the device and the coil of the relay connecting the cathode of the first diode rectifier to the anode of the second diode rectifier.

4. A flame ignition system, comprising: fluid fuel burner means; means for controlling the supply of fuel to the burner; spaced electrodes forming a spark gap disposed adjacent the burner; one electrode being grounded; a transformer having its high voltage secondary winding connecting the electrodes in series; one terminal of the transformer primary winding being connected in a series combination of a first capacitor, the anode of a silicon controlled rectifier, the cathode of the latter rectifier; the anode of a first diode rectifier, and the cathode of the diode rectifier, in that order, the other terminal of the primary winding being connected to the cathode of the diode rectifier; the gate electrode of the silicon controlled rectifier being connected to the cathode of the diode rectifier by a second series combination of first resistor, a breakdown device having a gas filled tube, a second resistor, the cathode of a second diode rectifier, and the anode of the second rectifier, in that order; the junction of the breakdown device and the second resistor being connected by a second capacitor to'the cathode of the silicon controlled rectifier; a third series combination of a third resistor, the cathode of a third diode rectifier, the anode of the third rectifier, and a fourth resistor connected in that order from the anode to the cathode of the silicon controlled rectifier; and a source of alternat ing current, the anode of the third rectifier being connected across the source through first switch means to the cathode of the first diode rectifier; the gate electrode of the silicon controlled rectifier being connected through second switch means across the source then through the first switch means to the anode of the third diode rectifier.

5. The flame ignition system as defined in claim 4 in which said first and second switch means are connected and have at least two positions, the first switch means in either position connecting the anode of the third diode rectifier to one terminal of the source of current, and the second switch means connecting the gate electrode of the silicon controlled rectifier to the other terminal of the source in its one position and breaking said connection in its other position, the second switch means being spring biased from its one position to its other position.

6. The flame ignition system as defined in claim 4 having flame sensing means disposed adjacent the burner pera le to automatically open said second switch means to break the connection between the gate electrode of the silicon controlled rectifier and the source of current.

7. A flame ignition system, comprising: fluid fuel burner means; a solenoid operated means for controlling supply of the fuel to the burner; spaced electrodes forming a spark gap disposed adjacent the burner, one electrode being grounded; a transformer having its high voltage secondary winding connecting the electrodes in series; one terminal of the transformer primary winding being connected in a first series combination of a capacitor, the anode of a silicon controlled rectifier, the cathode of said rectifier, the anode of a first diode rectifier, and the cathode of the diode rectifier, in that order, the other terminal of the primary Winding being connected to the cathode of the diode rectifier; the gate electrode of the silicon controlled rectifier being connected to the cathode of the first diode rectifier; a second series combination of a first resistor, the cathode of a second diode rectifier, the anode of the second rectifier, and a second resistor connected in that order from the anode to the cathode of the silicon controlled rectifier; a source of alternating current; the anode of the second diode rectifier being connected by a third series combination of the heater coil and the heat responsive normally closed pair of contacts of a heater switch and a second switch across the source to the cathode of the first diode rectifier; another series connection between the anode of the second diode rectifier and the cathode of the first diode rectifier including the coil of the solenoid of the fuel control means; and a light sensitive cadmium sulfide cell disposed adjacent to the burner for sensing when the burner is lit, the cell being in series with a relay coil and connected between the cathode of the first diode rectifier and the anode of the second diode rectifier, the normally open contacts of the relay being connected in a by-pass connection between the junction of the heat responsive pair of con tacts and the heater coil to the anode of the second diode rectifier.

References Cited by the Examiner UNITED STATES PATENTS 3,142,332 7/1964 Weber et a1 15828 X 3,223,887 12/1965 Brown 315-223 3,238,992 3/1966 Forbes l5828 3,251,351 5/1966 Bowers.

JAMES W. WESTHAVER, Primary Examiner.

Claims

1. AN ELECTRICALLY OPERATED IGNITER DEVICE FOR A BURNER HAVING A FLUID FUEL SUPPLY, COMPRISING: A SOURCE OF ALTERNATING ELECTRIC CURRENT; A TRANSFORMER; A FIRST SERIES COMBINATION OF ONE SOURCE TERMINAL, A SWITCH, THE ANODE AND CATHODE OF A FIRST RECTIFIER, AND A FIRST RESISTOR CONNECTED IN THAT ORDER TO ONE TERMINAL OF A CAPACITOR; A SECOND SERIES COMBINATION OF THE OTHER TERMINAL OF THE CAPACITOR AND THE PRIMARY WINDING OF THE TRANSFORMER CONNECTED IN THAT ORDER THROUGH A POINT OF REFERENCE POTENTIAL TO THE OTHER SOURCE TERMINAL; A SILICON CONTROLLED RECTIFIER HAVING ITS ANODE CONNECTED TO THE JUNCTION OF THE FIRST RECTIFIER AND THE CAPACITOR, HAVING ITS GATE TERMINAL CONNECTED TO THE POINT OF REFERENCE, AND HAVING ITS CATHODE CONNECTED THROUGH THE ANODE AND CATHODE, IN THAT ORDER, OF A SECOND RECTIFIER TO THE POINT OF REFERENCE, THE CATHODE OF THE SILICON CONTROLLED RECTIFIER BEING ALSO CONNECTED THROUGH A SECOND RESISTOR TO THE JUNCTION OF THE SWITCH AND THE FIRST RECTIFIER; AND SPACED ELECTRODES ADAPTED TO THE FIXED IN PROXIMITY TO THE BURNER, SAID ELECTRODES BEING IN SERIES CIRCUIT WITH THE SECONDARY WINDING OF THE TRANSFORMER, ONE ELECTRODE BEING GROUNDED, AND THE ELECTRODES FORMING THEREBETWEEN A GAP FOR A RAPIDLY RECURRING SPARK FOR IGNITING THE BURNER WHENEVER THE SWITCH IS CLOSED.