US1872880A - Fuel burner control system - Google Patents

Description

23, 1932- J. v. BREISKY ET AL FUEL BURNER CONTROL SYSTEM Filed Jan. 10. 1929 I 4 \lllilllllllll" INVENTORS John VBrezs/ry 2E 7'77 0711 55 Draper.

ATTORNEY Patented Aug. 23, 1932 UNITED STATES PAITEN'IQ OFFICE JOHN V. BBEISKT, OI PITTSBURGH,

AND THOMAS'DBAPER, OI WILKINSBURG, PENN- BYLVANIA, ASSIGNOBS TO WESTINGHOUSE ELECTRIC & MANUFACTURING COM- PANY, A CORPORATION 01 PENNSYLVANIA FUEL BURNER CONTROL SYSTEM Application filed January 10, 929. Serial No. 881,484.

Our invention relates to control systems and, particularly, to control systems for fuel burners.

An object of our invention is to provide a 5 relatively sim le and highly efficient control system for a uel burner.

Another object of our invention is to provide a control system that shall embody relatively simple means for effecting substantially instantaneous deenergization of the igni tion means upon appearance of a flame of the burning fuel and for effecting reenergization of the ignition means instantaneously,

or substantially so, upon disappearance o the flame.

' Another object of our invention is to provide a control system applicable to a fuelburner assembly having a short time-delay action, and embod ing a grid glow tube and 2a a flame electrode or efi'ecting control of the system.

A still further object of our invention is to provide a control system embodying means for desensitizing the grid glow tube to ensure that it will respond to predetermined changes in operating conditions only.

In racticing our invention, we rovide, in combination with a furnace, a uelfeeder means, preferably motor driven, electric igni- 20 tion means, a plurality of circuit-controlling devices, a grid glow tube embodying a control electrode which is connected to a flame electrode normally in electric-conducting relation to a flame of the burning fuel. We provide also a condenser connected across certain electrodes of the tube. a

The single figure of the drawing illustrates schematically a room to be heated, a heating furnace shown schematically in horizontal section and a diagram of connections of the system embodying ourinvention.

A source of supply of electric energy comprises supply-circuit conductors 11 and 12 which may be of any suitable or desired voltage and which are energized by analternating-current source of supply (not shown).

A room or space to be heated is illustrated schematically only, as embodying a room 13 having a hot-air register 14 located in the.

floor, which register is connected, by a hot air pipe 16, to a furnace 17 illustrated generally only. It is to be understood that the furnace 17 embodying a furnace chamber 18, may be of any suitable or desired kind that is effective for the purpose of heating one or more rooms and in which a suitable find, preferably, fluid fuel is to be burned.

A fuel-feeding means 19 is shown, generally only, as comprising a suitable motor 21 and a pump 22 or other similar means that is effective to receive fuel oil, for instance, and to deliver it into the chamber 18 under pressure and in a vaporized condition. The motor f 21 is shown schematically only, as any motor suitable for driving the device 22 may be employed.

A room thermostat 23 is located in the room 13 and has one terminal thereof connected by a conductor 24 to the supply-circuit conductor 11. The other terminal of the thermostat 23 is connected, by a conductor 26, to one contact terminal of a time-delay circuit interrupter 27 embodying, as here shown, a bimetallic strip 28, one end of which is secured to a substantially fixed contact terminal 29. The interrupter 27 embodies also a heating element 31 and a latching means 32 so arranged that, when the bi-metallic strip 28 has been actuated by the heating of element 31 to its open position, it will be held therein by the latch 32 wh ch must be manually actu ated in order to permit release of the strip 28 and its return to the closing position.

A contactor 33 embodies an actuating coil 34, a core member 36, two contact- bridging members 37 and 38 and a plurality of substantially fixed contact terminals 39 and 41 cooperating, respectively, with the bridging members 37 and 38.

One end of the heating element 31 is connected to the fixed contact terminal 29 of the device 27 while the other end of the element 31 is connected, by a conductor 42, to one each of the terminals 39 and 41. The outer end of the heating element 31 is also connected, by a conductor 43, to one terminal of the energizing winding of the motor 21, the other terminal of which is connected, by a conductor 44, to supply-circuit'conductor 12. I

The other contact terminal 39 is connected, by

a conductor 45, to the fixed terminal 29 of the device 27.

An ignition transformer 46 embodies a primary winding 47, a core 48 and a secondary winding 49. One terminal of the primary winding 47 is connected, by a conductor 51, to the other contact terminal 41 of the contactor 33. The other terminal of winding 47 is connected, by a conductor 52, to supply-circuit conductor 12.

A second transformer 53 comprises a primary winding 54, a core 56, and a secondary winding 57. One terminal of the primary winding 54 is connected, by a conductor 58, to conductor 43, while the other terminal of winding 54 is connected, by a conductor 59, to supply-circuit conductor 12.

We provide also a grid glow-tube 61 'embodying a suitable casing 62 and an anode 63, a cathode 64 and a control electrode 66. We prefer to use what is called a grid glow tube in which the anode 63 is relatively small in volume and superficial area, the cathode 64 is relatively large in superficial area and in which the control electrode 66 is also relatively small in area and is located closely adjacent to the anode 63. An electrical-discharge device of this kind has the property that, when the anode and cathode are connected to a source of supply of alternating current of a suitable voltage and if the control electrode is not connected to an outside element, or if. it is connected to an outside element, the latter is thoroughly electrically insulated, the discharge device will not be traversed by a current unless a voltage much higher than normal is imposed. However, upon a change in the condition of the control electrode, either directly or because of a change in the connection or in the electrostatic condition thereof, as by permanent or momentary groundingeither complete or partialthe tube will become and remain conducting until the original conditions are restored.

A sparking electrode 67 is mounted in a suitable electric-insulating bushing 68 which is supported in the body of the furnace 17 to cooperate with an end portion of the conduit for the fuel-feeding means 22 or with another sparking electrode provided thereon, as may be desired or necessary.

A flame electrode 69, of electric-conducting material, is mounted in a suitable electric insulating bushing 71, its location being such that it will be either in direct engagement with a flame of the burning fuel or in electrio-conducting relation with a flame of the burning fuel, by reason of its operative engagement with air ionized by the flame.

The outer terminal of the sparking elec-- trode 67 is connected, by a conductor 72, to one terminal of the secondary winding 49, the other terminal of which is connected to ground. A ground connection 73 is connected to the fuel-feeding means 22 and also to the body of the furnace 17.

One terminal of the secondary winding 57 of the grid-glow-tube transformer 53 is connected, by a conductor 74, to one terminal of the actuating coil 34, the other terminal of which is connected, by a conductor 76, to One terminal of a current-limiting resistor 77. A condenser 78 is connected in circuit in parallel relation to the coil 34.

The other terminal of the resistor 77 is connected, by a conductor 79, to the cathode 64. The anode 63 is connected to the other terminal of the secondary winding 57 and also to a round 81.

he control electrode 66 is connected, by a conductor 82, to the outer terminal of the flame electrode 69 and also to one terminal of a desensitizing condenser 83, the other terminal of which is connected to the cathode 64. The condenser may be made adjustable, if desired or necessary.

The system is shown in its deenergized condition, the temperature of the room or space 13 being sufliciently high to maintain the thermostat 23 in its open condition. Upon cooling of the air in the room 13 to a predetermined value, the room thermostat 23 will close and establish a circuit or circuits as follows: from supply-circuit conductor 11, through conductor 24, thermostat 23, conductor 26 and bi-metallic strip 28, to heating element 31 and from there through a plurality of parallel-connected circuits as follows: One circuit embodies the conductor 42, bridging member 38, conductor 51, primary winding 47 and conductor 52 to supply-circuit conductor 12. This effects energization of the ignition transformer and provides a plurality of sparks across the spark gap between the sparking electrode 67 and the end of the fuelfeeding tube.

A second circuit embodies conductor 43, motor 21 and conductor 44 to supply conductor 12. This circuit energizes the motor to actuate or drive the fuel-feeding means 22 to provide a supply of vaporized fuel in the furnace chamber 18 to be ignited by the sparking established by the ignition transformer 46, in the manner hereinbefore set forth.

A third circuit comprises conductors 43 and 58, primary winding 54 and conductor 59 to supply-circuit conductor 12. This energizes the grid-glow-tube transformer 53 and provides for the, energization of the tube 61.

If it be assumed that the respective devices have operated properly so that sparking will occur adjacent to the inner end of the fuelfeeding means, that the fuel feeding means is properly operative to provide a supply of vaporized fuel in the chamber 18 and that the fuel is ignited to provide a flame which is either directly in operative engagement with the flame electrode, as by enveloping it, or indirectly in electric connection therewith because of the ionized air surrounding the flame and providing an electric-conducting ath therebetween, the electrostatic char e w ich initially accumulated on the electro e 66 before appearance of the flame will be dissiated. This causes the tube 61 to be traversed by a current, the value of which is adjusted to a predetermined one by the resistor 77, As this current traverses the actuating COll 34, the core member 36 and the contact-bridging members connected therewith will be actuated to their upper positions, whereby the circuit through'the primary winding 47 of the ignition transformer is interrupted so that the ignition transformer is deenergized, and further sparking i'n',the furnace chamber is prevented.

The engagement of the bridging member 37 with the contact members 39 effects short-circuiting of the heating element 31, whereby ultimate actuation of the bimetallic strip 27 is prevented.

The time-delay circuit interru ter 27 is shown schematically only as em odying a heating element and a circuit-interrupting switch actuated thereby after a predetermined length of time. The system embodying our invention is applicable, particularly, to fuel-feedingmeans having a relatively short time delay between the energization of the motor and the appearance of vaporized fuel in the furnace chamber. If all of the steps in the sequential operation, as hereinbefore set forth, have been effected properly, a flame will appear, and the tube will become electric conducting, the contactor 33 will be energized as above set forth and the heating element 31 will be short-circuited to render the time-delay circuit interrupter inactive.

While we have illustrated and described a specific embodiment of a time-delay circuit interrupter, we do not desire to be limited thereto, as any device that is effective for the same purpose may beemployed, such as a mercury switch actuated to its respective positions by suitable thermally-actuable means and controlled by a time-delay member or its equivalent.

The condenser 78 is of help in causing proper operation of the contactor 33 by aiding to smooth out the ripples in the rectified current traversing the tube 61 and the coil 34.

The condenser 83 is connected, as shown in the diagram, in order to desensitize the tube 61 so that minor variations in the flame in the furnace will not cause a change in the op- 4 erating condition of the tube 61. The condenser 83 may be considered broadly as an impedance connected between the cathode and the control electrode for desensitizing purposes.

The condenser 83 ,or an equivalent reactance or resistance, cooperates with the circuit connected between the control grid and the cathode, which includes the flame electrode and the flame, to fix the electrical condition ofthe control grid and, when proper adjustment of its impedance'has been made relatively to the other part of the circuit, the grid glow tube will respond substantially instantaneously to predetermined major changes of condition only, more particularly to cessation of the flame.

The furnace 17 will continue to provide heated air for the room 13 until such time as the room thermostat 23 again opens the circuit, upon reaching a predetermined maximum temperature, whereupon the system will return to the condition shown in the drawing. If it should happen that the sparking should be deficient in strength or be wholly absent, the vaporized oil provided by the fuelfeeding means would not be ignited and, in order to ensure that sufficient current will traverse the heating element 31, it may be desirable to provide a resistor 84: connected in parallel-circuit relation to the primary winding 47 of the ignition transformer. If no flame should appear, either by reason of faulty ignition or by reason of lack of fuel 31 will energize the strip 28 so thatit will finally move to its open position, in which position it will be latched by member 32. It is then necessary for an operator to inspect the system and remedy the defect, after which the system can be again placed in operation.

If the flame should be extinguished, for any reason, during the ordinary normal operation of the system, the electric-conducting pat-h provided between ground 81, anode 63, control electrode 66, conductor 82, flame electrode 69 and through ground 73 back to ground 81 would be interrupted, and the control electrode would be electrically insulated so that a'blocking charge would accumulate thereon to render the tube electrically nonconducting.

This action would interrupt the circuit through the tube and through the coil 34, whereby the short circuit of heating element 31 would be interrupted, and the ignition means would be reenergized substantially instantaneously to provide sparking between the sparking-gap electrodes. If the supply of vaporized fuel is continued, it will be ignited again and the system will resume or to reenergize the ignition means, immediately if the flame is extinguished b accident when it should not have been so extinguished. Our system provides also a means for desensitizing the discharge device to render it nonresponsive to minor variations in the operation condition of the burning fuel.

Various modifications may be made in the system embodying our invention without departing from the spirit and scope thereof, and we desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art or are set forth in the ap pended claims.

\Ve claim as our invention:

1. In a fucl-burner-control system of' the type including a fuel-feeding means, an ignition means, and means including a tri leelectrode glow tube having its control e ectrode controlled in accordance with the conductivity of a flame of the burning fuel for.

causing substantially instantaneous deenergization of the ignition means u on appearance of a flame of the burning uel and for causing substantially instantaneous reenergization of the ignition means upon cessation of the flame, means directly operatively associated with the glow tube for ensuring that it will be unresponsive to minor variations in the conductivity of the flame of the burning fuel.

2. In a fucl-burner-control system of the type including a fuel-feeding means, an ignition means, and means including a tripleelectrode glow tube having its control electrode controlled in accordance with the conductivity of a flame of the burning fuel for causing substantially instantaneous deenergization of the ignition means upon appearance of a flame of the burning fuel and for causing substantially instantaneous reenergization of the ignition means upon cessation of the flame, an impedance directly electrically connected to two of the electrodes of the glow tube for rendering the glow tube unresponsive to minor variations in the conductivity of the flame of the burning fuel.

3. In a fuel-burner-control system of the type including a fuel-feeding means,an ignition means, and means for effecting deenergization of the ignition means upon appear ance of a flame of the burning-fuel and for effecting reenergization of the ignition means upon cessation of the flame, said means including a glow tube having an anode, cathode, and control electrode, and a flame electrode in electric-conducting relation to the flame of the burning fuel and electrically connected to the control electrode, an impedance connected to the cathode and the control electrode and eflective to render the glow tube unresponsive to minor variations of the flame of the burning fuel.

4. In combination, a voltage-responsive electric discharge device having an anode, 11

cathode and a control-electrode, means for establishing between said control electrode and said anode a conductive path constituted by combustion products of a fuel, ignition means and a burner for said fuel, connections whereby major changes in the conductivity of said path control the functioning of said ignition means, and means whereby minor changes in the conductivity of said path are prevented from affecting said ignition means.

5. In combination, a voltage-responsive electric discharge device havin an anode, a cathode and a control-electro e, means for establishing between said control electrode and said anode a conductive path constituted by combustion products of a fuel, ignition means and a burner for said fuel, connections whereby major changes in the conductivity of said path control the functioning of said ignition means, and impedance means connected between the th0de and a the control electrode of said discharge device for preventing minor changes in the conductivity of said path from affecting said ignition means.

6. In combination, a voltage-responsive electric discharge device having an anode, a cathode and a control-electrode, means for establishing between said anode and said control-electrode a conductive path constituted by the products of combustion of a fuel, ignition means and a burner for said fuel, connections whereby major changes in the conductivity of said path control the functioning of said ignition means, and reactive means connected between the cathode and the control electrode of said discharge device for preventing minor changes in the conductivity of sai path from affecting said ignition means.

7. In a fuel burner, an ignition device, control means instantaneously responsive to large variations in the condition of a flame within said burner for regulating the activity of said ignition device, and means for rendering said control means unresponsive to small variations in the condition of said flame.

8. In a fuel burner, an ignition device, control means instantaneously responsive to large variations in the condition of a flame within said burner for regulating the activity of said ignition device, said means including an electrode positioned in the region of said flame, and means for rendering said control means unresponsive to small variations in the condition of said flame.

9. In a fuel burner, an ignition device, control means instantaneously responsive to large variations in the condition of a flame within said burner for regulating the activity of said ignition device, means for rendering said control means unresponsive to small variations in the condition of said flame and means responsive to the action of said control means for controlling the flow of fuel to said burner.

10. In a fuel burner, an ignition device, control means instantaneously responsive to largle variations in the condition of a flame wit in said burner for regulatin the activity of said ignition device, means or rendering said control means unresponsive to small variations in the condition of said flame, means for feedin fuel to said burner, said ignition device an said last means being supplied with current through the heater element and contact points of a thermal relay, and means re onsive to said control means for shunting sai heater element so long as said ignition device is rendered inactive.

11. In a fuel burner, an ignition device, control means instantaneously responsive to large variations in the condition of a flame wit in said burner for regulating the activity of said ignition device, means for rendering said control means unresponsive to small variations in the condition of said flame, means for feeding fuel to said burner, said ignition device being supplied with current t rough a transformer primary winding shunted by an impedance element, said winding and said-last means being supplied with current through the heater element and contact points of a thermal relay and means responsive to said control means for shunting said heater element so long as said ignition device is rendered inactive.

In testimony whereof, we have hereunto subscribed our names this 8th day of January,

JOHN V. BREISKY. THOMAS DRAPER.

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