US1984572A

US1984572A - Electric pilot for hydrocarbon fuel

Info

Publication number: US1984572A
Authority: US
Publication date: 1934-12-18
Anticipated expiration: 1951-12-18

Description

Dec. 18, 1934. J FRAME 1,984,572

ELECTRIC PILOT FOR HYDROCARBON FUEL BURNERS Filed Oct. 18, 1930 2 Sheets-Sheet l AugustusJFrame Dec. 18, 1934.

A. J. FRAME ELECTRIC PILOT FOR HYDROCARBON FUEL BURNERS Filed Oct. 18, 1950 2 Sheets-Sheet 2 gwuantoo A ugustus JHamc Patented Dec. 18 1934 ELECTRIC PILOT FOR HYDROCARBON FUEL BURNERS Augustus J. Frame, Columbus, Ohio, assignor to Franklin Oil Heating, Inc., Columbus, Ohio, a corporation of Ohio Application October 18, 1930, Serial No. 489,635

4 Claims. (01. 15s 2s This invention relates to electric ignition means for efiecting combustion in hydrocarbon fuel burners of the automatic type utilized for residence and building heating purposes. In the operation of automatic vaporizing oil combustion burners or heating units employed for residence heating purposes, it has been customary heretofore to employ a small constantly burning pilot flame which usesa gaseous fuel. Such pilots have not been satisfactory for the reason that they are very readily accidentally extinguished by drafts or other causes, such as the failure of the gas supply and, in addition, since such a gas pilot is kept in a constant state of use, the sustained maintenance thereof is a matter of some added expense in the total fuel consumption of the heating system.

"1t is therefore an outstanding object of the present invention to provide automatic oil mechanism which functions through a thermostatic switch to operate intermittently for the purpose of maintaining the rooms of the residence or other area to be heated at a substantially constant temperature and wherein mechanism is provided, in conjunction with the thermostatic switch and an oil flow regulating valve, for energizing a spark producing ignition circuit for the purpose of igniting in an economical and emcient manner a combustible mixture developed by or supplied to an associated burner.

With these and other objects in view, which will appear as the description proceeds, the invention consists in the novel features of construction, combination of elements and arrangements of parts hereinafter fully described and pointed out in the appended claims.

In the accompanying drawings:

Fig. 1 is a side elevation of an automatic oil burning heating unit in connection with which the electric ignition means, comprising the present invention, is employed; Fig. 2 is a diagrammatic view of the circuits utilized in governing the operation of the electric pilot; Fig. 3 is a view in side elevation and partly in vertical section showing the oscillated mercury switches in different operating positions from the positions which they arewdisclosed as occupying in Fig. 2;

Fig. 4 is a vertical sectional view taken through the combustion. chamber of the oil burning heater disclosing the employment of the electrode used in my improved electric ignition apparatus, and

Fig. 5 is a modified form showing a hot wire igniter.

In the drawings there has been disclosed an automatic oil burning heating mechanism which is designated generally by the letter A and which is especially adapted for installation in conjunction with residence and house heating furnaces. The base of such a furnace is indicated at 1, and the wall structure thereof at 2.

Arranged exteriorly of the furnace is a frame 3 which effects the support of a fan 4 driven by means of an electric motor indicated at 5 in Fig. 2. The outlet of the fan 4 communicates with a conduit 6 which extends to a burner unit '7 disposed in the combustion chamber 8 of the furnace. Also mounted on the frame 3 is a valve 9 which is mounted to control the flow of fuel oil through a pipe line 10. This pipe line, after passing through the valve 9, extends through the conduit 6 and enters the bottom of an open topped vaporizing vessel 11, which is supported in the casing 12 of the burner unit '7. Liquid oil is allowed to flow into the bottom of the vessel 11 where it vaporizes and is commingled with air supplied to the mixing chamber 13 of the vessel 11 by the fan 4. Due to the manner of supplying air under pressure to the oil and the high temperatures of combustion, the mixture is gasified and the mixture discharged from the open top of the vessel 11 where active combustion thereof takes place above and exteriorly of said vessel. In the particular form of burning unit under discussion, the vessel 11 is provided 1 centrally with a riser 14 which is provided at a point intermediate of its height with a circular head 15 containing a number of radial ports 16. Air, under pressure from the fan 4, passes through the conduit 6 and thence into the riser 14 and spreads radially across the mixture chamber 13 coming into intimate contact with the vaporized oil released from the body of oil contained in the bottom of the chamber 13. The top of the riser 14, which terminates in a plane above that of the upper edge of the vessel 11, is also provided with a corresponding outlet head 1'7 provided with an annular passage for the release of air from the riser across the combustible mixture issuing from the top of the vessel 11. To secure a more efiicient mixture, the vessel is formed with an annular flange 18 which rests upon the upper edge of the casing 12. The flange 18 is provided with a plurality of circularly arranged inclined ports 19 which causes air to issue in an upward yet generally inward direction to combine with the combustible products issuing from the top of the burner vessel, the velocity of the air issuing from the ports 19 being such as to produce turbulence in the gaseous mixture and effect highly efficient combustion thereof with but negligible deposit of carbon.

Of course, the present invention is not limited to its use in conjunction with a burner of the type specifically shown and above described as the present invention relates more broadly to the provision of an electric ignition means for initiating combustion in hydrocarbon burners employed for house heating purposes but a specific description of the construction and operation of the mixing vessel 11 has been given merely for the purpose of facilitating a clear understanding of the operating features of the invention and not with the view of in anyway limiting the latter.

The main control valve 9 for governing oil flow through the line 10 is of the automatically oper-' ated type and for this reason, as shown in Figs. 2 and 3, formed with a stem 20 which extends into and forms the core or armature of a solenoid 21. Referring more particularly to the circuit arrangement disclosed in Fig. 2, the leads of an ordinary volt house circuit areindicated at 22. One of these leads is connected with a wire 23 which extends to a low voltage transformer 24. The secondary side of, this transformer is connected with a wire 25 which extends to a thermostatic switch 26. Ordinarily, the switch 26 is disposed in that portion of a house to be heated and functions in the usual manner to regulate automatically the operation of the burner mechanism to maintain a substantially constant temperature in the room or other areas to be heated. When the temperature falls, the switch 26 closes and provides for the passage of current from the lead 25 through a wire 27 which leads to a terminal 28 connected to the windings oi the solenoid 21. Following passage through the windings, the returnis provided by way of the conductor 29 which extends back to the transformer 24 and a conductor 30 which leads from the primary side of this trans-g former to the return lead 22. Thus the closing of the switch 26 energizes the solenoid 21, and thereby moves the valve stem 20 in a direction providing for the opening of the valve 9 and permitting of oil flow, from the source of supply (not shown) either under the influence of gravity or pressure to the bottom of the vaporizing vessel 11.

To effect the simultaneous operation of the motor 5 upon the opening of the oil line, there is arranged on the top of the solenoid case an arm 31 which is pivotally mounted as at 32. The bottom of the arm is provided with a resilient finger 33 disposed in registration with the extreme upper end of the stem 20. When the field of the solenoid is unexcited, the arm 31 assumes the position disclosed in Fig. 2 with the stem 20 removed from engagement with the finger 33 which allows the arm 31 to assume the downwardly inclined position disclosed in Fig. 2. However, when the solenoid is energized, the stem is raised contacting with the resilient finger 33 and rocking the arm 31 to the elevated position disclosed in Fig. 3. The arm 31 carries a glass shell 34 in which is arranged a suitablequantity of mercury, and one end of the shell 34 is provided with spaced terminals 35 which are so disposed that when the shell is in the position dis- One of the terminals 35 is connected with a lead;

36 which extends to the wire 23 and one conductor 22, while the other terminal 35 is connected with a Wire 37 which leads to the motor 5. The return side of the motor is connected with a conductor 38 which extends back to the second lead 22. By this arrangement the opening and closing of the valve functions to operate switch mechanism for automatically governing the operation of the motor 5, the arrangement being such that when the valve 9 is open, the motor and its associated fan 4 are in operation and conversely when the valve is closed, the operation of the motor and fan is arrested.

It is desirable to delay the stopping of the operation of the motor and fan upon the closing of the valve 9 and the deenergizing of the solenoid 21 in order that a continued supply of air may be given to the oil which remains in the burner unit for the purpose of insuring the complete combustion of this relatively small quantity of oil so that the burner will not smoke and produce objectionable carbon deposit. To secure the sustained operation of the motor and fan for a predetermined interval of time following the closing of the valve 9, I employ a warping bar 39 which consists of a plurality of metal strips wherein the individual strips are formed from relatively different materials having differing coeflicients of expansion. The bar 39 is wrapped with a winding capable of developing heat when electrical current is passed therethrough so that the bar will warp or bend from its normal or vertical position, as shown in Fig. 2, to the bent or warped position disclosed in Fig. 3. Current is supplied to the windings of the warping bar by means of leads 40 which are connected with the terminals 28 of the solenoid and whereby when current is flowing through the windings of the solenoid a portion thereof is shunted and passed through the windings on the warping bar, causing the change in operating position of the bar as indicated. Thus when the solenoid is energized, the stem 20 thereof moves rapidly in an upward direction closing the mercury switch 34 and energizing the motor 5. The mercury switch is positively maintained in this position by the stem 20 as long as the solenoid remains energized. However, when the thermostatic switch 26 opens and the solenoid is deem ergized, the mercury switch is maintained in its circuit closing positionfor a predetermined time by the warping of the bar 39 which, due to its heating, has been moved to a position underlying the outer portion of the arm 31 so that the motor continues its operation even though the valve 9 is closed and the stem 20 has assumed its lowered position. This permits air to be supplied to the burner to effect efficient combustion of that body of oil disposed between the valve 9 and the burner unit. The deenergizing of the solenoid winding correspondingly deenergizes the winding of the warning bar so that the latter gradually attains its normal vertical position as shown in Fig. '2 and releases the arm 31 by moving past its outer edge. This allows the arm 31 to drop and to open the circuit leading to the motor 5. The resilient finger 33 prevents injury to the glass shell arranged on the arm while the latter drops after its release from association with the upper end of the bar 39.

The lower end of the .bar 39 is connected with an adjustable bracket 41 which is slidably mounted and capable of being maintainedin set positions of adjustment on the top of the frame. The bracket 41. is formed with .an

upright-42 from which is pivotally suspended a; cradle 43 which carries a second mercury switch 44.I The cradle 43 is connected by means of an adjustable rod 45 withthe upper end of the Warping bar 39, the said rod being provided with a threaded union. 46 for controlling its efiective length. The switch 44 includes spaced terminals 47, and a wire 48 leads from-the wire 37 to one of said terminals, while a second wire 49 leads from theother of the terminals 47 to the primary side of a high voltage transformer 50, the return lead 51, of, the transformer being connectedwith the return lead 38 of the motor 5. The secondary or high voltage side of the transformer 50 includes a lead 52 which extends to an'electrode 53 supported in conjunction with the burner unit 7. One end of this electrode is spaced from:a carborundum block 54 which is mounted in the bottom of the vessel 11 adjacent to the riser 14. Theblock 54 is thus grounded as is likewise the return terminal-of the secondary side of the transformer, as shown in Fig. 2.

In operation, when the solenoid 21 is energized and the mercury switch 34 closed, current passes through the second mercury switch by way of the wire 48 and thence to the primary side of thehigh voltage transformer 50, producing a high tension spark in the gap formed between the electrode 53 and the carborundum block 54, thereby initiating combustion of the vaporized mixture produced in the burner unit. After this combustion has been thoroughly initiated, it is no longer necessary to maintain the spark and for this reason I connect the cradle 43 directly with the warping bar which does not assume its bent or warped position until sometime after the energizing of the solenoid 21, as previously explained. Therefore, the movement of the bar 39 results in rocking the mercury switch from its circuit closing position, as shown in Fig. 2, to its circuit opening position as disclosed in Fig. 3. When in the position shown in Fig. 3, the ignition circuit is open and the flow of high tension current to the electrode 53 interrupted or arrested. It is important to note, however, that when the solenoid is deenergized, and oil flow through the valve 9 stopped, the warping bar 39 will then slowly return to its vertical position. However, before the bar 39 is warped sufiiciently, when cooling, to release the arm 31, the cradle 43 will have been rocked sufliciently to close the circuit through the switch 44 to again reestablish the ignition circuit. This has been found desirable in insuring complete combustion of any gases, vapors or oils remaining in the burner unit '7 after normal oil flow to this unit has been stopped by the closing of the valve 9. The combustion of these final remaining traces of oil and gas prevents the accumulation or formation of objectionable carbon deposits in the burner unit.

In view of the foregoing, it will be appreciated that the present invention provides an automatic electric pilot or ignition device especially adapted for oil or hydrocarbon burners. The system is essentially automatic in its operation and requires no manual attention or control. In certain respects this invention constitutes a continuation in part of the disclosures contained in my prior patent No. 1,781,453, granted November 11, 1930 and supplements the disclosure in that application by the inclusion of the electric ignition means.

While I have shown in the preferred form of my invention an electric igniter which includes a spark gap, nevertheless it will be appreciated that I may employ in lieu thereof a resistance wire 55 capable of becoming heated to a sufficient extent upon the passage of current there,- through to effect combustion of an oil vapor mixture. The carborundum block 54 possesses a wick-like action in that liquid oil is absorbed thereby to an extent sufficient to permit of th liberation of a vapor from its surface, and this vapor is readily ignitible by the high tension spark released from the electrode 53. While I am aware of the fact that it has been proposed heretofore to use electric igniters for automatic hydrocarbon burners, it is novel so far as I am aware to automatically operate such igniter to effect complete combustion of that oil which remains in the burner unit immediately following the cessation of active operation of said unit whereby to prevent objectionable carbon formation. I preferably secure this result by utilizing a circuit control by the operation of the thermal bar 39 although of course I do not limit myself to this specific construction but reserve the right to employ all such modifications and variations thereof that may be said to fall fairly within the scope of the following claims.

What is claimed is:

I.- In automatically controlled oil burning heating apparatus, a burner unit, means for supplying oil to the burner unit including an electrically operated valve, a motor and a fan driven thereby for supplying air under pressure to said burner unit, a switch for said fan motor, a circuit including a thermostatic switch operable when closed to open said valve and simultaneously close the switch for said motor to operate said fan, an ignition device cooperative with said burner unit for initiating combustion therein, a circuit for said ignition device including a rockable switch, and an electrically heated warping bar having its free end connected to said rockable switch and operable at the beginning of its movement to keep the latter switch closed for a predetermined time period until combustion has been initiated in said burner unit, said bar upon further movement serving to rock said switch to an open position and maintain it open during the operation of the burner and upon return movement of the bar to again rock the switch to a closed position for effecting the operation of the ignition device until the switch for the fan motor is opened.

2. In automatically controlled oil burning heating apparatus, a burner unit, means for supplying oil to the burner unit including an electrically operated valve, a motor and a fan for supplying air under pressure to said burner unit, a switch for said motor, a circuit including a thermostatic switch operable when closed to open said valve and simultaneously close the switch for said motor to operate said fan, an ignition device cooperative with said burner unit for initiating combustion therein, a circuit for said ignition device including a rockable switch, and electrically heated warping bar having its free end connected to said rockable switch and operable at the beginning of its movement to keep the latter switch closed for a predetermined time period until combustion has been initiated in said burner unit, said bar upon further movement rocks said switch to an open position and maintains it open during the operation of the burner, said bar also serving to hold the switch for the fan motor closed for a predetermined time period after the closing of said valve by the thermostatic switch and upon its return movement to again rock the switch, for the ignition device, to a closed position for the operation of the latter until the switchfor the fan motor is opened by said bar.

3. In automatically controlled oil burning heating apparatus, a burner unit, means for supplying oil to the burner unit including an electrically operated valve, a motor and a fan driven thereby for supplying air under pres-- sure to said burner unit, a circuit for, said motor, a switch in said circuit, a circuit including a thermostatic switch operable when closed to open said valve and simultaneously close the switch for said motor to operate said fan, an ignition device cooperative with said burner unit for initiating combustion therein, said ignition device being in circuit with said inotor switch, a second switch normally closed in said motor circuit for the operation of said ignition device until combustion has been initiated in said burner, an electrically heated warping bar in circuit with the electrically controlled valve and having its free end connected to said second switch for the operation thereof, said bar operating to open the second switch for the ignition device after a predetermined time period and to maintain it open during the operation of the burner, said bar also serving to hold the switch for the fan motor closed after the closing of said valve to shut off the fuel supmy to the burner by the operation of the dim mostatic switch and to again close the switch for the ignition device for the operation of the latter until the switch for the motor is opened by the movement of said bar.

4. In an automatic control apparatus for mm: fuel burners, a burner, fuel and air supply eonduits leading to said burner, a control valve in said fuel conduit, said valve including 'a movable solenoid surrounded arr-nature, an electric motor and a fan driven thereby for delivering air to said burner through said air supply eon-- duit, a power circuit for said motor, 'a pivatauy movablemotor switch for said power circuit, said switch being arranged contiguous to the aimsture of said controlvalve, a control circuit including said control valve and its solenoid, a thermostatic switch in said control circuit onerable when closed to energize said solenoid to open said control valve and close said motor switch by the engagement of the control valve armature thereof, a warping bar having a heater arranged in said control circuit and operable when heated to engage with said motor switch to hold the latter closed independently of the operative position of the control valve arma ture, an igniter, a rockable igniter switch, a circuit for said igniter switch joining the latter in series with said motor switch and in parallel with said motor, and a direct connection uniting the warning bar with said igniter switch.

AUGUSTUS J. FRAME.