US2982351A

US2982351A - Heater pilot relighter

Info

Publication number: US2982351A
Application number: US610335A
Authority: US
Inventors: Thomas W Scott
Original assignee: United Gas Corp
Current assignee: United Gas Corp
Priority date: 1956-09-17
Filing date: 1956-09-17
Publication date: 1961-05-02
Anticipated expiration: 1978-05-02

Description

May 2, 1961 T. w. scoT'r HEATER PILOT RELIGHTER Filed se i. 17, 1956 THERMOP/LES COUNTER 7770/7705 M 5calfz IN V EN TOR.

BY M

5 4211M rTOk/VEY drop in the temperature of the gas occurs.

. bath of the heater.

United States Patent "ice HEATER PILOT RELIGHTER Thomas W. Scott, Shreveport, La., assignor to United Gas Corporation, Shreveport, La., a corporation of Delaware a Filed Sept. 17, 1956, Ser. No. 610,335

' 4 Claims. 01. 158-123) This invention relates to gas burner controls and more especially to a novel ignition circuit for igniting the pilot burner.

The delivery of natural gas to customers requires the reduction of pressure from whatever the transmission pressure line may be to a pressure low enough to satisfy the requirements of the customer. This pressure reduction is accomplished .by a reducing valve or regulator. When the reduction in pressure is made, a corresponding This temperature drop in the gas stream can cause failure of the reducing valve by the formation of ice or hydrates in the passages of the valve. This condition is aggravated by low ambient temperatures necessitating heating of the gas at delivery points during the winter months.

In view of the above conditions, it has been made a.

practice to install heaters at these points. These heaters are equipped with a main burner and a pilot burner. The

main burner is controlled by a thermostat in the water When the water bath attains a predetermined temperature, the thermostat extinguishes the main burner flame. The pilot burner is not extinguished by the thermostat and must remain ignited so that it may relight the main burner when the temperature of the water bath falls below the predetermined temperature called for by the thermostat. The pilot burners will fail from time to time for various reasons. The heater is then inoperative and the aforementioned freezing conditions will occur in the reducing valve and the gas supply to the customer will be shut off. It has been a practice in the past to set up inspection routes and have each heater checked once each day to be certain that the heater Patented May 2, 1961 r '2 I operated valve 14. A pilot burner '16 which is designed to always remain ignited is supplied with gas through a line 18 which communicates with the line 12 at a point in advance of the main valve 14.

The main 'valve 14 is provided. with a valve seat 20 and a valve 22 which is carried by a valve stem 24 on which is carried the core 26 of the solenoid 28. The valve 14 is biased toward closed position but is normally held in open position, as shown in the drawing, by the is functioning. This practice is expensive and time consuming without assurance of continuous operating of the equipment.

Accordingly, it is an object of this invention to provide a simplified ignition circuit for'relighting the pilot burner intermittent operation conserving battery power.

Still anotherobject of the inventionis the provision of counting means to record the number of times the heater has been ignited.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawing forming a part thereof, wherein an example of the invention is shown, and wherein a schematic view shows the example of the invention in use with a main burner and pilot burner.

Referring more particularly to the drawing, the main burner of a gas heating system is shown broadly designated at 10. The main burner 10 is supplied with gas through a line 12 into which is interposed a solenoid solenoid 28 pulling its core 26 upwardly when energized by suitable thermoelectric means in the form of

thermopiles

30 and 32 which are positioned adjacent the pilot flame 16. The electrical energy from the

thermopiles

30 and 32 is supplied to the solenoid 28 through the lines 34.and 36. It will be noted that a thermostat 38 is interposed in the line 36 so as to open the circuit supplying electrical .energy to the solenoid 28 to close the valve 14 and thus extinguish the main burner when the predetermined temperature called for by the thermostat 38 is attained.

When the pilot burner 16, which is designed to remain burning at all times, is extinguished for any reason whether or not the main burner 10 is extinguished the valve 14 will close as explained above. It is then necessary to ignite the pilot burner 16 by means of the ignie tion probes 40 and 42 which are positioned closely adjacent the pilot burner 16.

For this purpose anignition circuit, which is provided with electrical energy by any desired type electrical battery 44, is provided. When the pilot burner 16 is extinguished the relay 46, which is connected across the

lines

34 and 36, closes a switch 48 to engage the contact 50. The circuit is then complete from the battery 44, through the line 52, through a heating coil 54, through the switch 56 and the primary 58 of the spark coil 60, through the line 62, the switch 48 and line 64 to the positive terminal of the battery 44. Switch 56 is electro-magnetically operated by spark coil primary 58. Switch 56 provides interrupting action to the primary current of the primary winding 58 of spark coil 60 so that a high voltage may be obtained across spark 'coil secondary 76 to initiate the spark between ignition probes 40 and 42. During this time one side of the capacitor 66 is being energized through the line 68 into which is interposed the resistor 70.

It will be noted that the heating coil 54 and a .bi-metallic strip 72 form a timer broadly designated at 74. Upon being heated sufiiciently by the coil 54 the bi-metallic strip 72 will bend sufliciently to engage the contact 74a thus shorting out thehigh resistance heating coil 54 to induce electrical energy into the secondary 76 of the spark coil 60. One end of the secondary 76 is grounded through the line 78 and the other end of the secondary 76 is connected through the line 80 to the ignition probe 40. The other ignition probe 42 is grounded through the line 82. p

When the pilot burner has been relit for a suflicient duration of time to cause the relay 46 to open the switch 48 so as to engage the contact 84 the capacitor 66 will discharge through the line 86, through the relay 88 and the line 90, through the switch 48 and the line 92. The relay 88, will then momentarily cause the contact 94 to engage the contact 96 energizing the solenoid 98 through the line 100 to actuate the core 102 operating the counting mechanism 104, by completing the circuit through the line 106 which is connected to the line 68 from the negative terminal of the battery 44. r

In operation, therefore, in the event of pilot flame failure, the

thermopiles

30 and 32 will cool off. The resulting current loss causes the closing of the main gas valve 14 through the operation of solenoid 28 and the release of the relay 46. Such release causes the movable contact 48 to close the circuit supplying power from the battery 44 to the condenser 66 and also to operate the heating coil 54 on the timer 74. The function of the timer 74 is to allow any unburned gas to escape from the combustion chamber prior to ignition and to provide intermittent operation to conserve battery power. After approximately two minutes, the heating coil 54 causes the bi-metallic contact 72 to close, shutting out the heating coil 54. The resistance of the heating coil 54 is relatively high and will not allow the coil 60 to produce a spark prior to closing of the contact 72.

The spark coil 60 then causes the ignition probe 40 to spark to ground through the escaping gas of the pilot burner 16. This spark will continue until the bi-metallic element 72 of timer '74 cools off breaking the circuit through contacts72 and 74a to the spark coil 60. After a few seconds the heating coil 54 on timer 74 has again closed its

contacts

72 and 74a operating spark coil 60 and causing the spark to ground as described above.

This sequence outlined above will continue until the pilot frame 16 has reheated the

thermopiles

30 and 32 sufiiciently to open the solenoid valve 14, if thermostat 38 demands a rise in temperature, resuming operation of the main burner 10. At the same time the thermopiles -30 and 32 will also energize the relay 46, breaking the igniter circuit and causing the charge on the condenser 66, to discharge operating relay 88 which in turn advances the counter 104, thus giving a record of the number of times the pilot has been relit.

The invention is not limited to the preferred embodiments herein disclosed. Various changes within the scope of the following claims will occur to those skilled in the art.

What is claimed is:

1. A gas heating system having a main burner and a pilot burner, an ignition circuit for igniting said pilot burner including, a battery source energizing said ignition circuit, switch means closing said ignition circuit when the pilot burner is extinguished, a timing device interposed in said ignition circuit to delay igniting said pilot burner until unburned gas from the main burner has escaped and to conserve battery energy, circuit means including a capacitor adapted to be energized upon closing of said switch means and a circuit including a switch which closes when said first mentoined switch opens and a counting device operated in response to the discharge of the capacitor when said switch means opens said ignition circuit after the pilot burner is ignited recording the number of times the pilot burner is ignited.

2. A gas heating system having a main burner, a pilot burner, a valve biased toward closed position controlling the flow of gas to the main burner only, means operable when said pilot burner is ignited maintaining the valve in openposition, an ignition circuit for igniting said pilot burner including, a battery source energizing said ignition circuit, switch means closing said ignition circuit when the pilot burner is extinguished, a timing device intererated in response to the discharge of the capacitor when said switch means opens said ignition circuit after the pilot burner is ignited recording the number of times the pilot burner is ignited.

3. A gas heating ssytem having a main burner, a pilot burner, a valve biased toward closed position controlling the flow of gas to the main burner only, electromagnetic means operable in response to thermopiles positioned adjacent said pilot burner for maintaining the valve in open position when the pilot burner is ignited, an ignition circuit for igniting said pilot burner including, an electric battery energizing said ignition circuit, electromagnetic switch means also operating in response to said thermopiles closing said ignition circuit when the pilot burner is extinguished, a timing device interposed in said ignition circuit to delay igniting said pilot burner until unburned gas from the main burner has escaped and to conserve battery energy, a spark coil interposed in said ignition circuit which operates intermittently responsive to the timing device to conserve electrical energy, circuit means including a capacitor adapted to be energized upon closing of said switch means and a circuit including a switch which closes when said first mentioned switch opens and a counting device operated in response to the discharge of the capacitor when said electromagnetic switch means opens said ignition circuit after the pilot burner is ignited recording the number of times the pilot burner is ignited.

4. A gas heating system having a main burner, a pilot burner, a solenoid operated valve biased toward closed position controlling the fiow of gas to the main burner only, thermopiles positioned adjacent said pilot burner for maintaining the main valve in open position while the pilot burner is ignited, an ignition circuit for igniting said pilot burner including, a battery source energizing said ignition circuit, electromagnetic switch means also operating in response to said thermopiles interposed in said ignition circuit, a heating element interposed in said ignition circuit, a bi-metallc arm positioned adjacent said heating element which, when sufiiciently heated, will short out said heating element to delay igniting said pilot burner until unburned gas from the main burner has escaped and to conserve battery energy, a spark coil interposed in said ignition circuit operating when said heating element is shorted out, circuit means including a capacitor adapted to be energized upon closing of said switch means, and a circuit including a switch which closes when said first mentioned switch opens and a counting mechanism actuated by said capacitor when pilot burner is ignited.

References Cited in the file of this patent UNITED STATES PATENTS 1,050,328 Arnhorst Jan. 14, 1913 1,575,170 Knopp Mar. 2, 1926 2,192,631 Beam Mar. 5, 1940 2,192,632 Beam Mar. 5, 1940 2,255,672 Mason Sept. 9, 1941 2,261,458 Bailey et al Nov. 4, 1941 2,290,048 Hildebrecht July 14, 1942 2,409,492 Jones Oct. 15, 1946 2,500,663 Cleveland Mar. 14, 1950 2,710,056 Parrett June 7, 1955 a UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION May 2 1961 Patent No. 2,982,351:

Thomas W0 Scott It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column 3, line 20, for "frame" read flame column 3 line 44, for 'mentoined" read mentioned column 4 line 5, for asytem" read system line-":39, for "hi metallic?!- read bi-metallic Signed and sealed this 24th day of October 19616 (SEAL) Attest:

DAVID L. LADD Commissioner of Patents USCOMM-DC ERNEST W. SWIDER Attesting Officer