US3734676A

US3734676A - Electrically energizable control system for a fuel burner

Info

Publication number: US3734676A
Application number: US00154311A
Authority: US
Inventors: A Wyland
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1971-06-18
Filing date: 1971-06-18
Publication date: 1973-05-22
Anticipated expiration: 1990-05-22

Abstract

An electrically energizable control system for a burner for a combustible fluid. The control system includes a valve control and igniter circuit for opening the control valve to allow fluid to flow from the burner and generating an electric arc or spark for igniting the fluid. In the event ignition is not accomplished the valve control and igniter circuit automatically turns off after a predetermined period of time. A recycle timer circuit causes the valve control and igniter circuit to repeat the try for ignition a predetermined number of times after which a lockout timer circuit prevents further ignition trial, assuming the fluid has not become ignited. A detection circuit maintains the valve control and igniter circuit in its valve open condition upon the fluid being ignited. The control system includes a safety check circuit which allows the initial valve opening and spark energization only if the control system is in proper condition at the beginning of its operation. Also there is a precycle purge timer for providing an initial period of the operation of the control system before ignition is attempted.

Description

United States Patent 1 Wyland [11] 3,734,676 May 22, 1973 [54] ELECTRICALLY ENERGIZABLE CONTROL SYSTEM FOR A FUEL BURNER [75] Inventor: Alvin D. Wyland, Morrison, Ill.

[73] Assignee: General Electric Company, Fort Wayne, Ind.

[22] Filed: June 18, 1971 [21] Appl. No.: 154,311

[52] US. Cl. ..43l/79 [51] Int. Cl ..F23n 5/08 [58] Field of Search ..43l/67, 66, 72, 79; 317/96 [56] References Cited UNITED STATES PATENTS 3,574,496 4 1971 Hewitt ..431/79 3,338,288 8/1967 Walker.... ..431/71 3,400,302 9/1968 Miller ..3l7/96 3,445,173 5/1969 Malavasi et a1 ..43 1/25 3,446,565 5/1969 Hantack ..43l/70 3,349,284 10/1967 Roberts ..3l5/223 Primary ExaminerEdward G. Favors Attorney-John M. Stoudt, Redford M. Reams, Ralph E. Krisher, Jr. et al.

[ 57] ABSTRACT An electrically energizable control system for a burner for a combustible fluid. The control system includes a valve control and igniter circuit for opening the control valve to allow fluid to flow from the burner and generating an electric are or spark for igniting the fluid. In the event ignition is not accomplished the valve control and igniter circuit automatically turns off after a predetermined period of time. A recycle timer circuit causes the valve control and igniter circuit to repeat the try for ignition a predetermined number of times after which a lockout timer circuit prevents further ignition trial, assuming the fluid has not become ignited. A detection circuit maintains the valve control and igniter circuit in its valve open condition upon the fluid being ignited. The control system includes a safety check circuit which allows the initial valve opening and spark energization only if the control system is in proper condition at the beginning of its operation. Also there is a precycle purge timer for providing an initial period of the operation of the control system before ignition is attempted.

18 Claims, 1 Drawing Figure VAL VE CON TROL AND IGN/IEA I CHECK l rims ELECTRICALLY ENERGIZABLE CONTROL SYSTEM FOR A FUEL BURNER BACKGROUND OF THE INVENTION The present invention relates to an electrically energizable control system for a fuel burner and, more particularly, to such a control system of the direct ignition type.

Automatic control systems for fluid fuel burners, such as gas furnaces for instance, normally provide means for automatic ignition of the fuel. For a number of years the most common approach for such ignition was a standing pilot. In such igniters, a small pilot flame burns continuously and is used to ignite the fuel mixture at the main burner when heat is called for. Such systems have a number of drawbacks including the possibility of the pilot flame being accidentally extinguished.

Over the past several years there has developed the practice of using spark or arc igniters in such control systems in order to directly ignite the fuel at the main burner. Some control systems of this type-provide a continuous sparking action, that is, when the thermostat or other master control calls for heat a spark is provided continuously until the master control device turns the system off. Other systems provide sparks or arcs for a predetermined period of time and then turn the burner system off unless a flame detector senses ignition of the fuel. With such systems a failure to ignite the fuel during the one ignition trial results in the system being disabled until manually reset.

Many fluid fuel burners, such as gas furnaces for instance, include a fan which forces air through the combustion chamber both to avoid an excessive build up of heat within the combustion chamber and to provide proper ventilation to assure that an explosive accumulation of fuel does not occur within the combustion chamber. With such arrangements the control thermostat normally has multiple contacts so that the fan is turned on prior to the fuel and igniter and is turned off later than the fuel control valve to assure that the fan is energized the entire time there may be a flame.

It is also desirable in these kinds of installations to provide what is known as a prepurge, that is to have the fan operating for some set period of time before ignition is tried. This is to evacuate the combustion chamber of excess fuel in the event the fuel valve has leaked. In the past complicated and expensive arrangements have been provided so that the control system is not energized for this prepurge period of operation.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide. an improved electrically energizable control system for a fuel burner.

Another object is to provide such a control system which, upon initial energization, renders the fuel valve control and igniter inoperative for a prepurge period.

A further object of the present invention is to provide such a control system in which the fuel valve and igniter can be energized only if the control components of the system are'in the proper condition upon energization of the system.

Yet another object of this invention is to provide such a control system which provides an ignition trial for a predetermined period of time and then automatically turns the igniter and fuel valve off in the event ignition has not occurred, While maintaining at least the fuel valve energized in the event ignition has occurred.

Still another object of the present invention is to provide such an improved control system in which the ignition trial is repeated a predetermined number of times and then the control system is locked out in the event ignition is not achieved.

Still a further object of the present invention is to provide such a new and improved control system which is relatively simple in form and utilizes components of proven reliability.

The present invention, in accordance with one embodiment thereof, provides an electrically energizable control system for a fuel burner, including an igniter and a controlled switching device effective, when gated, to connect the igniter to a source of electrical energy for providing pulses of electrical energy to the igniter. There is a gate circuit, including a capacitance, for providing gate signals to the control switching device so long as the capacitance has a charge belowa predetermined level. The capacitance initially is provided with a charge of at least a predetermined level. A timing means is provided and is effective, after a predetermined period of energization of the control system, to reduce the charge on the capacitance below the predetermined level so that the control switching device is gated to operatively connect the igniter to the source of electrical energy only after the predetermined period of energization of the control system.

The above mentioned and other features and objects of this invention and the manner of attaining them will become more apparent, and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawing, wherein:

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE of the drawing is a schematic electrical circuit representation of a fuel burner control system incorporating one form of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the FIGURE there is illustrated an electrically energizable control system 10 for a fuel burner. The fuel burner is schematically illustrated at 11 and is supplied with a combustible fluid, such as a gas, through supply conduit 12 and control valve 13. The burner 11 is mounted in a combustion chamber which is schematically illustrated by the broken line box 14.

The control system is provided with electrical energy from a suitable source through a step up transformer 15 having a primary 16 and a secondary 17. A thermostatically controlled switch 18 is provided in one supply line for the primary 16 so that electrical energy is provided to the primary when switch 18 is closed. It will be understood that the control system could be provided with electrical energy directly from the usual volt; domestic supply. However, such a control system provides great benefit when used in a thermostatically regulated system. Thus, it is shown with the step up transformer as thermostats normally are constructed to beprovided with a relatively low voltage such as 24 volts and the control system is then provided with high voltage such as l20 volts A.C. supply by means of the transformer 15. It will be understood that, for use with gaseous combustible fluids, the thermostat controlling switch 18 normally will turn on a fan (not shown) to provide a stream of air through the combustion chamber 14 at all times when switch 18 is closed.

The secondary 17 of transformer is connected to a pair of supply lines or conductors 19 and 20 with the supply conductor 20 being connected to a point of ref erence potential, such as ground. One side of valve 13 is connected to the supply conductor 19 through switch arm A-1 and contact 13a while the other side of the valve is connected to ground. Thus when switch arm A-l engages contact 13a, electrical energy is provided to the valve and causes the valve to be open. This allows the flow of suitable combustible fluid, such as a gas, from the burner 11. Often it will be desired to use a valve having a low voltage coil. In such instances the valve can be connected to the circuit through a step down transformer.

A switch arm A-2 is connected to the conductor 19 and is movable between a contact 21 and a contact 22. From contact 21 a safety check circuit extends through resistor 23, diode or rectifier 24, the coil B of a reed switch and a resistor 25 to the reference conductor 20. A filter capacitor 26 is connected across the reed switch coil B so that, when the switch arm A-2 is connected to contact 21 the relay coil will operate on the half-wave voltage provided through the safety check circuit.

Reed switch coil B controls a switch arm B-l which is positioned between the conductor 19 and a contact 27. Thus a point D in the control system may be connected to the supply conductor 19 either through switch arm A-2 and contact 22 or switch arm B-l, contact 27, a diode or rectifier 28 and resistor 29. From circuit point D a first'supply circuit extends through a rectifier or diode 30, a relay coil A, a resistor 31 and the anode 32A to cathode 32C path of a controlled switching device such as controlled rectifier 32 to the reference conductor 20. The relay coil A controls the switch A-1 so that switch A-l is open when the coil is de-energized and is closed when the coil is energized. Coil A also controls switch arm A-2 so that it is connected to contact 21 when the coil is de-energized and connected to contact 22 when the coil is energized. A filter capacitor 33 is connected across the coil A so that the coil may be effectively energized by half-wave energy provided through the diode 30.

From circuit point D a second supply circuit extends through a capacitor 34, a resistor 35, a resistor 36, rectifier or diode 37 and a storage capacitor 38 to the reference conductor 20. Another diode or rectifier 39 is connected between the reference conductor 20 and the junction between resistors and 36 and is poled to conduct current of the opposite polarity than diode 37. Thus, with circuit point D energized, current will flow from reference conductor 20 through diode 39, resistor 35 and capacitor 34 to circuit point D when reference conductor 20 is positive with respect to conductor 19. This builds a charge on capacitor 34. On the reverse half cycle, that is when conductor 19, and thus circuit point D, is positive with respect to reference conductor 20, the charge on capacitor 34 is added to the supply voltage and builds a charge on capacitor 38 through resistor 36 and diode 37. This charge builds toward double the peak supply voltage; however, the actual maximum voltage to which the charge on storage capacitor 38 may build is clipped or controlled by Zener diodes 40 and 41 which are connected in series across the storage capacitor 38, with negative temperature coefficient thermistor 42 connected across Zener diode 41.

The thermistor is utilized so that the two Zener diodes 40, 41 in series provide a stable platform voltage. Zener diodes are somewhat sensitive to changes in temperature and a burner control may be operated under conditions where the temperature of the control system may vary widely. Thus assuming that 240 volts is the peak voltage to which it is desired to charge capacitor 38, Zener diode 40 may be picked to have a nominal avalanche or breakdown voltage of 240 volts and will maintain such peak voltage when the control system is in a hot or warm environment. At this time the negative temperature coefficient thermistor 42 has a very low resistance and effectively shunts the thermistor 41, which may have a nominal avalanche or breakdown voltage of 20 volts by way of example. If the environment of the control system is cold, the breakdown voltage of thermistor 40 will be less than 240 volts; however, the resistance of the negative coefficient temperature thermistor will rise so that the Zener diode 41 comes into play and compensates. This keeps the zenered voltage across storage capacitor 38 at approximately 240 volts.

The storage capacitor 38 is connected between reference conductor 20 and the controlled rectifier anode 32A. The reed switch coil B of the safety check circuit is connected to the control rectifier anode 32A through diode 43 and 44 so that the coil B is connected in parallel with the anode-cathode path of the controlled rectifier. A gate circuit, including resistor 45, diode 46, capacitor 47, diode 48 and a voltage breakdown device in the form of a neon tube 49, is connected between the anode 32A and gate 320 of the controlled rectifier 32. The capacitor 47 is connected through a resistor 50 and capacitor 51 to the reference conductor 20.

The switch arms A-l, 8-1, and A-2 are shown in their initial positions so that, when thermostatic switch 18 initially closes, a circuit is completed between the conductors 19 and 20 through the safety check circuit. The voltage on capacitor 26 quickly builds to the pick up voltage of coil B and closes switch arm B-1 and contact 27. The

resistors

29 and 31 limit the current through the arm B-1 and contact 27. The storage capacitor 38 then is charged by the capacitor 34 to a maximum voltage determined by the Zener diode circuit. Simultaneously capacitors 47 and 51 are charged to approximately the peak line voltage with the vast majority of this charge appearing across the capacitor 47. The capacitor 47 and neon tube 49 are chosen so that the initial voltage on capacitor 47 plus the breakdown or firing voltage of neon tube exceeds the peak line voltage. This initially prevents gate current flow through the circuit including resistor 45, diode 46, capacitor 47 diode 48 and neon tube 49. Thus the controlled rectifier 32 will remain in the nonconducting condition.

If the controlled rectifier 32 initially is in a conducting condition, a low resistance path would be provided through the diodes 43, 44 and the anode-cathode path of the controlled rectifier 32 to the reference conductor 20. Such a path would prevent the voltage across the coil B from reaching its pick up voltage and the contact arm B-l would not be connected to contact 27. This would prevent completion of the connections for the two supply circuits. This provides a safety check,

that is the first and second supply circuits are not completely connected into the circuit if the control rectifier is conductive at the beginning of operation of the control system.

The control rectifier 32 may be turned on or gated through the gate circuit only when the charge on capacitor 47 is below a predetermined level, that is, when the charge on capacitor 47 plus the breakdown or firing voltage of neon tube 49 is below the voltage level of the charge on storage capacitor 38. To this end, a switch arm C-1 and contact 50a are connected across the capacitor 47 and resistor 50. When switch arm C-l is engaged with contact 50a the charge on capacitor 47 is discharged through the resistor 50. A recycle timer circuit for operating the switch arm C-l extends from the contact 21 through a resistor 52, a diode 53, a resistor 54, a voltage breakdown device, in the form of neon tube 55, and coil C to reference conductor 20. A timing capacitor 56 is connected across the neon tube 55 and coil C. The coil C actuates the switch arm C-1 and, in practice, coil C, switch arm C-1 and contact 50a may be components of a reed switch. Upon energization of the control system charging current for capacitor 56 flows from contact 21 through resistor 52, diode 53, and resistor 54. When the capacitor 56 charges to the firing voltage of neon tube 55, it discharges through the neon tube and coil C. During the discharge time (which may be a matter of milliseconds for instance) the switch arm C-l engages contact 50a, so that capacitor 47 discharges through resistor 50 and capacitor 51 is charged to near peak line voltage.

This initiates an ignition trial. Since capacitor 47 is discharged, gate current can flow through resistor 45, diode 46, capacitor 47, diode 48, and neon tube 49 to the gate 32G of the control rectifier. The control rectifier is gated and the first supply circuit from point D through diode 30, coil A, resistor 31 and the anodecathode path of controlled rectifier 32 to reference conductor 20 is completed. The current flow through coil A causes switch arm A-l to engage contact 13a and switch arm A-2 to move from contact 21 to contact 22. Engagement of switch arm A-1 and contact 130 completes the circuit to energize the valve 13 so that fuel is provided to the burner 11. Connection of switch arm A-2 to contact 22 completes the circuit from conductor 19 to reference point D when switch B-l opens as a result of coil B being de-energized.

Capacitor 38 is repeatedly charged to the Zener voltage. Each time the control rectifier 32 is gated the voltage at the anode of the control rectifier drops to within about 1 volt of ground potential, cutting off continued flow of gate current. Each time gate current flows the capacitor 47 is charged incrementally and this incremental charge is retained on the capacitor 47 by the latching action of diode 46. Capacitor 47 charges incrementally in this manner each gating cycle until the voltage on capacitor 47 plus the firing voltage of neon tube 49 equals the Zener voltage. In the exemplification control system, this ignition trial time is approximately seconds.

Each time the control rectifier 32 conducts it completes a circuit from the storage capacitor 38 through the primary 57 of a step up transformer T. The secondary 58 of the step up transformer T is connected to a pair of

spark electrodes

59 and 60 which are in the vicinity of the burner 11 and one of which may be grounded. The step up transformer T has a high ratio of secondary turns to primary turns for inducing a high voltage ignition are or spark between the

electrodes

59 and 60 each time the storage capacitor 38 discharges through the primary 57. A diode 61 is positioned in the reference conductor in parallel with the primary 57 so that the magnetic field generated in the primary may collapse during periods when the control rectifier 32 is nonconductive. Under normal conditions the sparks or arcs generated between the electrodes 59 and will cause the fuel emitted from burner 11 to be ignited.

A detection circuit is provided from the anode 32A through a negative temperature coefficient thermistor 62, a flame detector in the form of an ultraviolet cell 63, and a capacitor 64 to the reference conductor 20. The junction between the ultraviolet cell 63 and capacitor 64 is connected to the gate 32G through a diode 65 and the neon tube 49. Filtered direct current voltage for operation of the ultraviolet detector cell is provided by the storage capacitor 38 (zenered to approximately 240 volts by the Zener diode circuit). When the fuel emitted from the burner 11 is ignited, the filter DC. voltage on capacitor 38 will cause the ultraviolet cell 63 to turn on or conduct and charge capacitor 64 to a voltage level sufficiently high to cause neon tube 49 to conduct and gate the control rectifier 32. Each time the control rectifier gates, the voltage of capacitor 38 falls to about one volt and thus removes the voltage from the ultraviolet cell until the controlled rectifier turns off and the voltage on capacitor 38 builds up again. This removal of voltage from the ultraviolet cell insures that the ultraviolet detector cell will turn off or stop conducting after each gating of the controlled rectifier. The cycle rate is dependent on the percent of time the voltage on capacitor 38 is present and the percent of conduction of the ultraviolet cell. Thus the controlled rectifier is not gated on each positive half cycle, as it takes several line cycles to charge the capacitor 38 to a sufficient level. The filter capacitor 33 is such that the coil A will remain energized with this somewhat intermittent gating of the control rectifier to maintain the supply circuits energized in the manner described above so long as the ultraviolet cell is detecting flame at the burner. As long as the thermostat switch 18 is closed and the detector senses flame, the control system will continue to operate as described. When the. thermostat determines that sufficient heat has beenprovided and opens switch 18, the entire system is de-v energized and valve 13 closes.

The junction between the ultraviolet cell 64 and capacitor 63 is connected to the conductor 19 through a diode 66 and resistor 67 and is connected to the reference conductor 20 through a resistor 68. The circuit:

rectifier. The control rectifier will turn off, which causes switch arm A-l to open and switch A-2 to move from contact 22 to contact 21. The recycle timer circuit slowly charges the capacitor 56. This slow charging;

of the capacitor 56 allows the fan (not shown) to purge the combustion chamber 14.

Resistors

69 and 70 are connected in series across capacitor 51 so that during the recycle time the voltage on capacitor 51 will be bled off. At the end of the ignition trial the storage capacitor 38 will be charged to the zenered voltage (approximately 240 volts in the exemplification). With such a high charge across the anodecathode path of controlled rectifier there is a possibility of an inadvertent conduction of the rectifier which would cause an unwanted sparking action; A resistor 71 is connected between the anode and cathode of the control rectifier so that during the recycle time the voltage on storage capacitor 38 is reduced to approximately peak line voltage. Presently the most economically desirable controlled rectifier for use in the exemplification is a silicon controlled rectifier of a type which tends to pass a small leakage current even when it is not gated. If such a leakage current is allowed to flow between the anode and cathode, the controlled rectifier may act as if it is gated and turn on. This could cause a-random sparking action. To avoid this a resistor 72 is connected between the gate and cathode of the control rectifier so as to shunt any leakage current.

When the charge on capacitor 56 reaches the firing voltage of neon tube 55, it discharges through the coil C and momentarily engages switch arm C-l with contact 50a. This again reduces the charge on capacitor 47 below the predetermined level, in fact substantially discharging capacitor 47. It also charges capacitor 51 to substantially peak line voltage. This again places the control system in a condition for another ignition trial with the controlled rectifier 32 being repeatedly gated through the gate circuit (resistor 45, diode 46, capacitor 47, diode 48 and neon tube 49). Upon each gating action the capacitor 47 is provided with an incremental charge which is latched by the diode 46 and eventually the charge on capacitor 47 reaches a level that prevents further gating of the control rectifier through the gate circuit. Again if ignition has occurred, the controlled rectifier will continue to be gated through the flame detection circuit and will maintain the coil A energized. In the event ignition has not occurred the controlled rectifier will turn off and coil A will be de-energized. In most installations it is desirable that ignition attempts be limited to a predetermined number, with the control system then automatically becoming locked out or inactivated until manually reset, as by opening and then reclosing the thermostat switch 18. To this end there is provided a lockout timer circuit. One portion of this circuit extends from circuit point E through diode 73 and capacitor 74 to reference conductor 20. An additional circuit portion extends from the point E through a diode 75, a resistor 76 and a capacitor 77 to the reference conductor. Yet another portion of the lockout timer circuit extends from the conductor 19 through a diode 78, a resistor 79 and a Zener diode 80 to the reference conductor 20. The junction between diode 73 and capacitor 74 is connected to one side of a coil F through a switch F-l and a diode 81, the other side of the coil F being connected to the reference conductor 20. The coil F and switch F-l may conveniently form an additional reed switch. The junction of coil F and diode 81 is connected to the junction of resistor 76 and capacitor 77 through a voltage breakdown device in the form of a neon tube 82 and this junction is further connected to the junction between resistor 79 and Zener diode 80 through a diode 83. Additionally the junction between resistor 79 and Zener diode 80 is connected to a junction between diode 73 and capacitor 74 by a conductor 84. The basic lockout timer action is provided by the diode 75, resistor 76, capacitor 77,

neon tube 82 and coil F. Each time the contact 21 is connected into the circuit so as to charge the recycle timer capacitor 56, the lockout timer capacitor 77 is also connected in circuit and is charged through the diode and resistor 76. Once the capacitor 77 is charged to a level equal to the breakdown or firing voltage of the neon tube 82 it discharges through the neon tube and coil F. This causes the coil F to pick up or close the switch F -1. Once the switch F-l closes the coil F is maintained in its energized state by the D.C. current provided via diode 81, filtered by capacitor 74. With the switch F-l closed, resistance 52 and resistance 79 are connected in parallel via conductor 84. This parallel arrangement is connected in series with coil F and forms a voltage divider which lowers the Y voltage at point E below the firing voltage of neon tube 55. The recycle timer circuit then cannot cause the neon tube 55 to tire and so as to momentarily close switch arm C-1 and contact 50i a. Additional recycling attempts are prevented and the circuit will stay in this condition until the thermostatic switch 18 is opened so as to remove electrical power from the control system. When electrical power is removed, the capacitor 77 will drain through the diode 83, capacitor 74 will drain through diode 81 and coil F, and switch F-l will open.

The number of unsuccessful ignition trials prior to lockout is dependent upon the relative charging time between capacitor 77 and capacitor 56, assuming the firing voltage is of neon tubes 55 and 82 or approximately the same. The charging time for capacitor 77 is determined by the values of resistor 76 and capacitor 77 while the charging time for capacitor 56 is determined by the values of the resistor 54 and capacitor 56. With the values of the exemplification elements listed hereinafter the relative charging times turn out to be approximately 2.6 which would give two recycles before lockout.

In a number of installations the control system may go for an extended period of time, as long as several weeks, between operations. In the event such a period of time has elapsed since the last operation, the capacitor 56 will be completely discharged when the control system is energized for a first ignition attempt. On the other hand, in the event of each subsequent ignition attempt the capacitor 56 will start with some residual charge. If not compensated for, this could cause an erratic operation by providing a very long time delay before the initial ignition attempt. To prevent this, a voltage divider circuit including diode 85, resistor 86 and resistor 87 is connected across the capacitor 74 and is connected to the junction between resistor 79 and Zener diode through the conductor 84. With this arrangement the Zener 80 will provide a reference voltage, a portion of which is applied across the capacitor 56 by means of the voltage divider network to compensate for a lack of residual voltage. This provides capacitor 56 with a stable starting voltage for each of its timing operations.

By way of exemplification only, and without limitation thereto, I have found that the below listed values and components are suitable for one control system as described above.

diodes

24, 28, 39, 43, 44, 46, 48, 53, 61, 65, 66, 73,

75, 78, 81, 83, 1 mp, 200 PIV JEDEC Type lN5059 diodes 30, 37 1 amp., 400 PIV JEDEC Type capacitor 26 100 MFD, 50 volts ELECTRO- LYTlC capacitor 33 20 MFD, 150 volts ELECTRO- LYTlC capacitor 34 1.0 MFD, 200 volts capacitor 38 1.0 MFD, 200 volts capacitor 47 0.22 MFD, 200 volts capacitor 51 0.47 MFD, 200 volts capacitor 56 1.0 MFD, 200 volts capacitor 64 500 PFD, 100 volts MICA capacitor 74 20 MFD, 160 volts ELECTRO- LYTlC capacitor 77 1.0 MFD, 200 volts SCR General Electric part number C106B neon lamp 49 General Electric Type 5AG neon lamp 55 General Electric Type 4AD neon lamp 82 General Electric Type 4AD Zener diode 40 240 volts, 1 watt Zener diode 41 20 volts, 0.5 watt Zener diode 80 170 volts, 1 watt resistor 23 1.2 kilohms, 5 watts resistor 25 2.7 kilohms, 1 watt resistor 29 150 ohms, 0.5 watt resistor 31 10 ohms, 0.5 watt resistor 35 270 ohms, 0.5 watt resistor 36 3.3 kilohms, 5 watts resistor 45 18 kilohms, 0.5 watt resistor 50 l5 kilohms, 0.5 watt resistor 52 l kilohms, 0.5 watt resistor 54 5.6 megohms, 0.5 watt resistor 67 22 megohms, 0.5 watt resistor 68 l8 megohms, 0.5 watt resistor 69 l0 megohms, 0.5 watt resistor 70 22 megohms, 0.5 watt resistor 71 1 megohm, 0.5 watt resistor 72 l kilohm, 0.5 watt resistor 76 l megohms, 0.5 watt resistor 79 l0 kilohms, 0.5 watt resistor 86 390 kilohms, 0.5 watt resistor 87 100 kilohms, 0.5 watt While in accordance with the Patent Statutes, I have described what, at present, is considered to be the preferred embodiment of my invention, it will be obvious to those skilled in the art that numerous changes and modifications may be made therein without departing from the invention, and it is therefore aimed in the appended claims to cover all equivalent variations as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electrically energizable control system for a fuel burner, including:

a. an igniter;

b. a controlled switching device effective, when gated, to connect said igniter to a source of electrical energy for providing pulses of electrical energy to said igniter;

c. a gate circuit for said controlled switching device, said gate circuit including a gate capacitancefor providing gate signals to said controlled switching device so long as said capacitance has a charge below a predetermined level, said capacitance initially being provided with a charge of at least the predetermined level; and

d. first timing means effective, after a predetermined period of energization of said control system, to reduce the charge on said gate capacitance below the predetermined level whereby said controlled switching device is gated to operatively connect said igniter to the source of electrical energy only after the predetermined period of energization of said control system.

2. A control system as set forth in claim 1, wherein:

a. said gate capacitance is provided with an incremental charge each time said gate circuit provides a gate signal to said controlled switching device so that gate signals to said controlled switching device through said gate circuit stop upon the total incremental charge reaching the predetermined level;

b. said first timing means thereafter being effective to again reduce the charge on said gate capacitance below the predetermined level after another predetermined period of energization of said system whereby said controlled switching device again is gated to operatively connect said igniter to a source of electrical energy.

3. A control system as set forth in claim 2, further including second timing means effective, after said first timing means has reduced the charge on said gate capacitance a predetermined number of times, to disable said first timing means from again effecting reduction of the charge on said second capacitor to below the predetermined level.

4. An electrically energizable control system for a fuel burner, including:

a. an igniter;

b. a storage capacitance for providing pulses of electrical energy to said igniter;

c. a controlled switching device connected in controlling relationship between said capacitance and said igniter;

d. a circuit for connecting said storage capacitance to a source of electrical energy to build a charge on said storage capacitance for thereafter providing a pulse of electrical energy to said igniter; said circuit including switch means;

e. actuating means for said switch means to cause said switch means to be closed only when said actuating means is energized;

f. said actuating means being connected in parallel with said controlled switching device so that said switch means is maintained open in the event said controlled switching device conducts upon initial energization of said system.

5. A control system as set forth in claim 4, further including:

a. a gate circuit for said controlled switching device, said gate circuit including a gate capacitance for providing gate signals to said controlled switching device so long as said gate capacitance has a charge below a predetermined level, said gate capacitance initially being provided with a charge of at least the predetermined level; and

b. first timing means effective, after a predetermined period of energization of said control system, to reduce the charge on said gate capacitance below the predetermined level whereby said controlled switching device is gated to operatively interconnect said storage capacitance and said igniter only after the predetermined period of energization of said control system.

6. A control system as set forth in claim 5, wherein:

b. said first timing means thereafter being effective to again reduce the charge on said gate capacitance below the predetermined level after another predetermined period of energization of said system whereby said controlled switching device again is gated to operatively interconnect said storage capacitance and said igniter.

7. A control system as set forth in claim 6, further including second timing means effective after said first timing means has effected reduction of the charge on said gate capacitance a predetermined number of times, to disable said first timing means from again effecting reduction of the charge on said gate capacitor to below the predetermined level.

8. An electrically energizable control system for a fuel burner, including:

a. valve actuating means for a fuel valve to enable flow of combustible fuel from the burner;

b. a spark igniter for igniting fuel emitted from the burner;

c. a first supply circuit for connecting said valve actuating means and a controlled switching device to a source of electrical energy to energize said actuating means upon conduction of said controlled switching device;

d. a storage capacitance; a second supply circuit for connecting said storage capacitance to the source of electrical energy to build a charge on said storage capacitance;

e. an ignition circuit interconnecting said storage capacitance, said igniter and said controlled switching device for discharging electrical energy from said storage capacitance through said igniter to cause ignition of fuel emitted from the burner upon conduction of said controlled switching device;

f. a gate circuit for said controlled switching device, said gate circuit including a gate capacitance for providing gate signals to cause said controlled switching device to conduct so long as said gate capacitance has a charge below a predetermined level, said gate capacitance initially being provided with a charge of at least the predetermined level; and

g. first timing circuit including means effective, after a predetermined period of energization of said control system, to reduce the charge on said gate capacitance below the predetermined level whereby gate signals are provided to said controlled switching device through said gate circuit only after the predetermined period of time.

9. An electrically energizable control system as set forth in claim 8, further including: first switch means for selectively connecting said first and second supply circuits to the source of electrical energy and electrically energizable actuating means for said first switch means, said first switch actuating means being connected in parallel with said controlled switching device so that said first switch means will be closed to supply electrical energy to said first and second supply circuits only if said controlled switching device initially is nonconductive.

10. An electrically energizable control system as set forth in claim 8, wherein:

b. a detection circuit, including a flame detection means, for providing gate signals to said controlled switching device independent of the incremental charge on said gate capacitance, upon said flame detection means sensing combustion of fuel emitted from the burner.

11. An electrically energizable control system as set forth in claim 8, wherein:

b. second switch means connected across said gate capacitance and effective, when closed, to reduce the charge on said gate capacitance below the predetermined level;

c. said first timing circuit including a series arrangement of a voltage breakdown device and an electrically energizable actuating means for said second switch means, said first timing circuit also including a timing capacitance connected in parallel with said series arrangement to energize said second switch actuating means for momentarily closing said second switch means upon the charge on said timing capacitance reaching the firing voltage of said voltage breakdown device;

d. third switch means effective upon substantial nonconduction of said controlled switching device to connect said first timing circuit to the source of electrical energy for charging said timing capacitance.

12. An electrical energizable control system as set forth in claim 11, further including a second timing circuit effective, after a period of time longer than said predetermined period of time, to prevent the charge on said timing capacitance from reaching the breakdown voltage of said voltage breakdown device.

13. An electrically energizable control system for a fuel bumer,including:

b. a spark igniter for igniting fuel emitted from the burner;

c. a first supply circuit for connecting said valve actuating means and a controlled rectifier to a source of electrical energy for energizing said valve actu ating means upon conduction of said controlled rectifier;

d. a storage capacitance; a second supply circuit for connecting said storage capacitance to the source of electrical energy and capable of charging said storage capacitance to a level in excess of the voltage of the electrical supply;

e. an ignition circuit interconnecting said storage capacitance, said igniter and said controlled rectifier for discharging electrical energy from said storage capacitance through said igniter to cause ignition of fuel emitted from the burner upon conduction of said controlled rectifier;

f. a gate circuit for said controlled rectifier including a gate capacitance and a first voltage breakdown device, said gate circuit being connected between said storage capacitance and said controlled rectitier to provide a gate signal to cause conduction of said controlled rectifier upon the charge on said storage capacitance exceeding sum of the charge on said gate capacitance and the firing voltage of said first voltage breakdown device, said gate capacitance initially being provided with a charge sufficient to prevent gate signals;

g. discharge switch means connected across said gate capacitance and effective, when closed, to reduce the charge on said gate capacitance to a level allowing gate signals to said controlled rectifier;

h. first timing circuit including a series arrangement of a second voltage breakdown device and an electrically energizable actuating means for said discharge switch means, said first timing circuit also including a timing capacitance connected in parallel with said series arrangement to energize said actuating means for said discharge switch means for momentarily closing said discharge switch means upon the charge on said timing capacitance reaching the firing voltage of said second voltage breakdown device.

14. An electrically energizable control system as set forth in claim 13, further including other switch means effective to connect said first timing circuit to the source of electrical energy only when said controlled rectifier is substantially nonconductive.

15. An electrically energizable control system as set forth in claim 14, further including: a second timing circuit having means effective, after said first timing circuit has effected momentary closing of said discharge switch means a predetermined number of times, to prevent the charge on said timing capacitance from reaching the firing voltage of said second voltage breakdown device.

16. An electrically energizable control system as set forth in claim 13, further including a detection circuit, including flame detection means, for providing gate signals to said controlled rectifier independent of the level of charge on said gate capacitance upon said flame detection means sensing combustion of fuel emitted from the burner.

17. An electrically energizable control system as set forth in claim 16, wherein: said controlled rectifier includes an anode, a cathode and a gate; said flame detection means includes an ultraviolet detector; and said flame detection circuit is connected between said anode and said gate and the voltage at said anode falls below the holding voltage of said ultraviolet detector each time said controlled rectifier is gated into conduction.

18. An electrically energizable control system as set forth in claim 13, further including additional switch means for selectively connecting said first and second supply circuits to the source of electrical energy and electrically energizable actuating means for said additional switch means; said additional switch actuating means being connected in parallel with said controlled rectifier so that said additional switch means will be closed to supply electrical energy to said first and second supply circuits only if said controlled rectifier initially is nonconductive.

Claims

1. An electrically energizable control system for a fuel burner, including: a. an igniter; b. a controlled switching device effective, when gated, to connect said igniter to a source of electrical energy for providing pulses of electrical energy to said igniter; c. a gate circuit for said controlled switching device, said gate circuit including a gate capacitance for providing gate signals to said controlled switching device so long as said capacitance has a charge below a predetermined level, said capacitance initially being provided with a charge of at least the predetermined level; and d. first timing means effective, after a predetermined period of energization of said control system, to reduce the charge on said gate capacitance below the predetermined level whereby said controlled switching device is gated to operatively connect said igniter to the source of electrical energy only after the predetermined period of energization of said control system.

2. A control system as set forth in claim 1, wherein: a. said gate capacitance is provided with an incremental charge each time said gate circuit provides a gate signal to said controlled switching device so that gate signals to said controlled switching device through said gate circuit stop upon the total incremental charge reaching the predetermined level; b. said first timing means thereafter being effective to again reduce the charge on said gate capacitance below the predetermined level after another predetermined period of energization of said system whereby said controlled switching device again is gated to operatively connect said igniter to a source of electrical energy.

4. An electrically energizable control system for a fuel burner, including: a. an igniter; b. a storage capacitance for providing pulses of electrical energy to said igniter; c. a controlled switching device connected in controlling relationship between said capacitance and said igniter; d. a circuit for connecting said storage capacitance to a source of electrical energy to build a charge on said storage capacitance for thereafter providing a pulse of electrical energy to said igniter; said circuit including switch means; e. actuating means for said switch means to cause said switch means to be closed only when said actuating means is energized; f. said actuating means being connected in parallel with said controlled switching device so that said switch means is maintained open in the event said controlled switching device conducts upon initial energization of said system.

5. A control system as set forth in claim 4, further including: a. a gate circuit for said controlled switching device, said gate circuit including a gate capacitance for providing gate signals to said controlled switching device so long as said gate capacitance has a charge below a predetermined level, said gate capacitance initially being provided with a Charge of at least the predetermined level; and b. first timing means effective, after a predetermined period of energization of said control system, to reduce the charge on said gate capacitance below the predetermined level whereby said controlled switching device is gated to operatively interconnect said storage capacitance and said igniter only after the predetermined period of energization of said control system.

6. A control system as set forth in claim 5, wherein: a. said gate capacitance is provided with an incremental charge each time said gate circuit provides a gate signal to said controlled switching device so that gate signals to said controlled switching device through said gate circuit stop upon the total incremental charge reaching the predetermined level; b. said first timing means thereafter being effective to again reduce the charge on said gate capacitance below the predetermined level after another predetermined period of energization of said system whereby said controlled switching device again is gated to operatively interconnect said storage capacitance and said igniter.

8. An electrically energizable control system for a fuel burner, including: a. valve actuating means for a fuel valve to enable flow of combustible fuel from the burner; b. a spark igniter for igniting fuel emitted from the burner; c. a first supply circuit for connecting said valve actuating means and a controlled switching device to a source of electrical energy to energize said actuating means upon conduction of said controlled switching device; d. a storage capacitance; a second supply circuit for connecting said storage capacitance to the source of electrical energy to build a charge on said storage capacitance; e. an ignition circuit interconnecting said storage capacitance, said igniter and said controlled switching device for discharging electrical energy from said storage capacitance through said igniter to cause ignition of fuel emitted from the burner upon conduction of said controlled switching device; f. a gate circuit for said controlled switching device, said gate circuit including a gate capacitance for providing gate signals to cause said controlled switching device to conduct so long as said gate capacitance has a charge below a predetermined level, said gate capacitance initially being provided with a charge of at least the predetermined level; and g. first timing circuit including means effective, after a predetermined period of energization of said control system, to reduce the charge on said gate capacitance below the predetermined level whereby gate signals are provided to said controlled switching device through said gate circuit only after the predetermined period of time.

10. An electrically energizable control system as set forth in claim 8, wherein: a. said gate capacitance is provided with an incremental charge each time said gate circuit provides a gate signal to said controlled switching device so that gate signals to said controlled switching device through said gate circuit stop upon the total incremental charge reaching the predetermined level; b. a detection circuit, including a flame detection means, for providing gate signals to said controlled switching device independent of the incremental charge on said gate capacitance, upon said flame detection means sensing combustion of fuel emitted from the burner.

11. An electrically energizable control system as set forth in claim 8, wherein: a. said gate capacitance is provided with an incremental charge each time said gate circuit provides a gate signal to said controlled switching device so that gate signals to said controlled switching device through said gate circuit stop upon the total incremental charge reaching the predetermined level; b. second switch means connected across said gate capacitance and effective, when closed, to reduce the charge on said gate capacitance below the predetermined level; c. said first timing circuit including a series arrangement of a voltage breakdown device and an electrically energizable actuating means for said second switch means, said first timing circuit also including a timing capacitance connected in parallel with said series arrangement to energize said second switch actuating means for momentarily closing said second switch means upon the charge on said timing capacitance reaching the firing voltage of said voltage breakdown device; d. third switch means effective upon substantial nonconduction of said controlled switching device to connect said first timing circuit to the source of electrical energy for charging said timing capacitance.

13. An electrically energizable control system for a fuel burner, including: a. valve actuating means for a fuel valve to enable flow of combustible fuel from the burner; b. a spark igniter for igniting fuel emitted from the burner; c. a first supply circuit for connecting said valve actuating means and a controlled rectifier to a source of electrical energy for energizing said valve actuating means upon conduction of said controlled rectifier; d. a storage capacitance; a second supply circuit for connecting said storage capacitance to the source of electrical energy and capable of charging said storage capacitance to a level in excess of the voltage of the electrical supply; e. an ignition circuit interconnecting said storage capacitance, said igniter and said controlled rectifier for discharging electrical energy from said storage capacitance through said igniter to cause ignition of fuel emitted from the burner upon conduction of said controlled rectifier; f. a gate circuit for said controlled rectifier including a gate capacitance and a first voltage breakdown device, said gate circuit being connected between said storage capacitance and said controlled rectifier to provide a gate signal to cause conduction of said controlled rectifier upon the charge on said storage capacitance exceeding sum of the charge on said gate capacitance and the firing voltage of said first voltage breakdown device, said gate capacitance initially being provided with a charge sufficient to prevent gate signals; g. discharge switch means connected across said gate capacitance and effective, when closed, to reduce the charge on said gate capacitance to a level allowing gate signals to said controlled rectifier; h. first timing circuit including a series arrangement of a second voltage breakdown device and an electrically energizable actuating means for said discharge switch means, said first timing circuit also including a timing capacitance connected in parallel with said series arrangement to energize said actuating means for said discharge switch means for momEntarily closing said discharge switch means upon the charge on said timing capacitance reaching the firing voltage of said second voltage breakdown device.