US2549633A - Gas burner ignition and safety control system - Google Patents

Description

April 17, 1951 J, OTTMAR 2,549,633

GAS BURNER IGNITION AND SAFETY CONTROL SYSTEM Filed Dec. 22, 1945 2 Sheets-Sheet l M MM!!! J. OTTMAR April 17, 1951 GAS BURNER IGNITION AND SAFETY CONTROL SYSTEM 2 She ets-Sheet 2 Filed Dec. 22, 1945 FIGS.

Patent ed Apr. 17,3951

GAS BURNER IGNITION AND SAFETY CONTROL SYSTEM Jerome Ottmar, Attleboro, Mass, assignor to Metals & Controls Corporation,

Attleboro,

Mass., a corporation of Massachusetts Application December 22, 1945, Serial No. 636,996

7 Claims.

This invention relates to gas burner control systems and more particularly to safety control systems for gas burners.

Among the various objects of the invention are the provision of gas burner control systems providing a time delay between pilot ignition and main burner ignition; the provision of a control system which avoids chattering of the main fuel supply valve in case of flame failure; the provision of a control system which automatically shuts off the flow of gas upon fiame failure; the provision of a control system which upon flame failure recycles .to relight the flame; the provision of a control system which affords multiple recycling; and the provision of a control system of the type referred to which is sturdy, reliable and constructed of few parts. Other objects will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which several of various possible embodiments of the invention are illustrated,

Fig. l is a diagram of a control system of the present invention;

gig. 2 is a diagram of an alternative system; an

Fig. 3 is a diagram of a further alternative system.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

Referring to Fig. l, a gas burner control of this invention is shown to include a main gas burner I. Flow of gas to the main burner is under control of a solenoid valve 3 in a main burner gas supply line 5. A branch line I is connected into supply line 5 ahead of valve 3 for supplying gas to a pilot burner 9, the latter being located in position to ignite the main burner l. Flow oi gas to the pilot burner 9 is under control of a pilot valve H in branch line 1. An electrical igniter l3, of the conventional hot wire type, is positioned to ignite gas flowing from the pilot burner when energized.

The main burner valve 3 includes'a solenoid coil 4, which when energized, operates upon a plunger 23 to open the valve. The valve is biased to closed position by a spring 29. Plunger 28 also controls 'a secondary switch llassociated with valve 3, a stem 30 on the plunger opening this switch in response to opening of the valve and closing the switch upon closure of the valve.

The pilot burner valve H is controlled by a thermal relay, generally designated N3, of the type disclosed in Wilson Patent 2,203,558. Generally, the relay comprises a pair of snap-acting thermostatic discs [2 and I4 confined at their edges and centrally attached to a stem 16 for actuating the valve. These discs are controlled by an electrical resistance heating element 2| so as to snap from one position of curvature to an opposite position of curvature. When heater 2] is deenergized and the discs cool, they snap to a position wherein valve I l is closed. When heater 2| is energized and the discs are thereby heated, they snap to the opposite position and open the valve. p

The solenoid coil :3 is connected across the wires 2'! and 47 of a power supply circuit M. This is done by means of a circuit includinga main control switch 25 and the contacts of a thermal time-delay relay 3?, to be described. As illustrated, one terminal of the coil is connected by a line 3! including the main control switch 25 to line 41. The other terminal of the coil is connected by a line 33 to one of the terminals for contacts 35. The other terminal for con-, tacts 35 is connected by a line 39 to line 21 of the power supply circuit. The main control switch 25 may be either manually or automatically controlled. The circuit is such that when switch 25 and contacts 35 are closed, current flows from power supply line 4'! through line 31, solenoid coil 4, line 33, contacts 35 and-line 3G to the other power supply line 2'! to energize the solenoid 4 and open valve 3. This also opens switch I1. The switch H, the heater 2! and the hot wire igniter [3 are connected in series with one am other and across lines 3! and 21, being under primary control of main control switch 25. As .illustrated, one terminal of heater 2: is connected by a line 23 to line 3i between switch 25 and sole-, noid coil 4. The other terminal of the heater is connected to one terminal of switch H by aline IS. A line l5 including the igniter I3 is connected between the other terminal of switch it and power line 2?. The circuit is such that with switches 25 and it closed, current flows from line 3! through line 23, heater 2!, line 59, switch l7, line and igniter 13 to line 21.

The thermal time-delay relay 3?, like relay it,

is also of the type disclosed in Wilson Patent; 3,558. It comprises a pair of snap-acting v thermostatic discs l2 and |4 confined at their edges and centrally attached to a stem it for actuating the contacts 35. The discs are controlled by an electrical resistance heating element 45 to snap from one position of curvature to an opposite position of curvature. The relay 3'! is so constructed that when heater 45 is deenergized and the discs cool, they snap to a position wherein contacts 35 are open. When heater 45 is energized, and the discs are thereby heated, they snap to the opposite position and close the contacts. Fig. 1 illustrates the latter condition.

The heater 45 is connected in series with a flame-sensitive current controller 4| in the power circuit M. As illustrated, line 47 of the power circuit is connected to one terminal of the heater. The other terminal of the heater is connected to one terminal of current controller 4| by a line 43. Line 27 is connected to the other terminal of controller 4|. The flame-sensitive current controller 4| is of the type which is normally substantially nonconductive but which becomes conductive when heated in the reducing atmosphere of a flame, reverting to its normal nonconductive condition when the flame is out. Such a current controller is fully disclosed in Hower Patent 2,106,249. Controller 4| is so positioned that both the pilot and main burner flames will act upon it. Thus, when either pilot burner 9 or main burner is ignited, controller 4| will be heated in a reducing atmosphere to cause it to become conductive. When both pilot burner 9 and main burner I are extinguished, controller 4| is non-conductive. Since heater 45 will not be energized to close contacts 35 unless controller 4| is conductive, solenoid coil 4 will not be energized and valve 3 will not open unless the pilot burner 9 is ignited at the initiation of a cycle.

Operation of the Fig. 1 control is as follows:

Assuming that main burner valve 3 is closed, that pilot alve II is closed and main control switch 25 is open, switch I! will be closed since valve 3 is closed and contacts 35 will be open with heater 45 cold. To start the burner, switch 25 is closed. This closes a circuit through line 23 to heater 2| of pilot relay I8, and through line i9, switch ll, line I5, pilot igniter 3 and line 21 back to the supply circuit. After a predetermined period of time (preferably about 5 seconds), igniter l3 has become heated and heater 2| causes discs l2 and I4 of relay l8 to snap open pilot burner valve This lights the pilot burner and its flame plays on flame-sensitive current controller 4| which thereupon becomes conductive and permits current to pass through it and energize heater 45 of time-delay relay 3?. After a period of time, heater 45 causes discs |2 and M of relay 3! to snap to their opposite position of curvature and close contacts 35. This closes a circuit through solenoid coil 4 which moves plunger 28 to its Fig. 1 position to open main valve 3.

Gas flowing through valve 3 into the main burner I is ignited by the pilot flame and the flame from burner I then also plays upon flamesensitive current controller 4|. As alve 3 opens, switch I! is opened, thereby breaking the circuit to igniter I3 and to heater 2|. After a predetermined time thermostatic discs |2 and M of re ay I 8 cool and snap to their position of opposite curvature closing pilot valve II. This turns on the pilot but does not affect the conductivity of flame-sensitive current controller 4| as it is now heated by the main burner flame.

To extinguish the main burner flame, switch is opened to break the circuit through line 3|, solenoid 4, line 33, contacts and line 39 from the supply circuit M. This releases plunger 28, and spring 29 thereupon biases valve 3 to cut oil. further flow of gas to main burner This also closes switch l1. As soon as flame-sensitive current controller 4| reverts to its non-conducting state, it breaks the circuit to heater of timedelay relay 37. After a predetermined period of time thermostatic discs 12 and 4 in relay 3'! snap to their position of opposite curvature opening contacts 35.

All the contacts are thus reset to the off condition described above by the opening of switch 25 and the device is ready for recycling.

In case the main burner is blown out, flamesensitive current controller 4| will revert to its non-conducting condition and will not pass current to heater 45 of time-delay relay 3! which will subsequently open contacts 35. This breaks the circuit to solenoid coil 4 permitting spring 29 to close valve 3. Closing valve 3 closes switch I? so that, since switch 25 is still closed, the control will recycle in an attempt to relight main burner I.

If hot-wire igniter |3 should rupture, causing a break in the circuit, heater 2| of pilot relay |8 will receive no current, pilot valve U will not open and the cycle described will not occur.

Fig. 2 illustrates another embodiment of the invention. As in the Fig. 1 embodiment, the gas burner control is shown to include a main gas burner and a solenoid valve 3 in the main gas burner supply line 5. A branch line is again connected into the supply line 5 ahead of valve 3 for supplying gas to a pilot burner 9 located in position to ignite the main burner. Flow of gas to the pilot burner, however, is under control of pilot valve MI in line 1, rather than under control of relay-operated valve With valve 4| open, pilot burner 9 is ignited in any desired manner.

The solenoid coil 4 of solenoid valve 3 is connected across power supply circuit M under control of a thermal time-delay relay 38 like relay 31 of Fig. 1. As illustrated, relay 38 comprises a pair of snap-acting thermostatic discs 2 and I4 attached to a stem It carrying a contactor bar 65. These discs are controlled by an electrical resistance heating element 45 to snap from one position of curvature wherein bar bridges contacts 61 and 39 to anopposite position of curvature wherein these contacts are open. When heater 45 is deenergized and the discs cool, they snap to a position wherein the contacts are open, as illustrated in Fig. 2. When heater 45 is energized and the discs are thereby heated, they snap to the opposite position and move bar 65 to bridge the contacts. A line I41 connects one side of the power supply circuit M and contact 61. A line |5| connects contact 69 and one terminal of solenoid coil 4. The other terminal of coil 4 is connected by a line I53 to the other side of the power supply circuit.

The relay heater 45 is connected across the power supply circuit M in series With the flamesensitive current controller 4|. As illustrated, heater 45 is in a line 45 connected between line l4! and one terminal of controller 4|. A line I43 connects the other terminal of the controller to the other side of the power supply circuit. The controller 4| in this instance is positioned to be acted upon only by the flame 0f the pilot burner.

The operation of the Fig. 2 control is as follows:

' Inltially,.valve I41 is closed and the. pilotburner 8 and main burner I, are not ignited. Since the pilot burner is extinguished, flame-sensitive current controller II is non-conductive and heater 45, connected in series therewith, is deenergized. Discs I2 and I4 of relay 38 are therefore, cool and in their Fig. 2 position, having moved bar '65 away from contacts 61 and 69. 1

To start the burner, valve MI is, opened and the pilot burner 9' ignited in any suitable way. The controller M is thereupon acted upon by the pilot burner flame to become conductive. This completes a circuit from one side of supply circuit M through line I4I, relay heater 45, line I45, controller 4| and line. I43 to. the other side ofthe supply circuit. Thus, heater 46 is energized.

After a predetermined interval, heater 45 heats discs I2 and I4 of relay 38 until they snap .to their opposite position wherein bar 65 bridges contacts 61 and 69. This closes a circuit from one side of supply circuit M through line I41, contact 61', bar 65, contact 69, line I5I, solenoid coil 4 and line I53v to. the other side of the supply circuit. This opens valve 3, admitting gas to main burner I, which is ignited by pilot burner 9.

When the main burner I is to be extinguished, valve I41 is closed to turn off the pilot 9. Flamesensitive current controller 4i thereupon becomes non-conductive and heater '45 is deener-. gized. After a predetermined interval, discs I2 and I4- cool position, movingbar 65 away from [contacts 61 and 69.. This breaks the circuit through solenoid coil 4, whereupon spring 29. closes valve 3,.- shut.- ting ofithe flow of gas to burner I.

Fig. 3; illustrates another and third embodiment of the invention including a main gas burner I and a solenoid valve 3 in the main burner supply line 5. A branch line I is again connected into supply line 5 ahead of; valve 3 for supplying gas to pilot burner 9. The latter is located in position. to ignite the main burner I. As in the Fig. 1 form, flow of gas to the pilot burner is under control of a relay-operated pilot valve III corresponding to valve I I" of Fig. 1.

An electrical igniter I3 is provided, as in Fig. 1,, to ignite the pilot burner. The igniter is connected across the power supply circuit in series with a switch III associated with the valve. As illustrated, discs I2 and I4 of a thermal relay MB for the valve are attached to a stem 64 carrying a contactor bar I65 adapted toclose and open, contacts I61" and I 69 of, switch III. .Stem M. has. a kno 65 fa te m n a ua on thereof. The discs, are controlled byelectrical resistance. heating element z-I to snap from one position of curvature to an opposite position of curvature. When heater 211 is deenergized and the discs cool, they snap to a position wherein valve III is closed, as in the case of valve II in, Fig. 1. When heater ZI is energized and the discs are thereby heated, they snap to a position wherein valve HI is opened. When valve II I is closed; bar I65 is disengaged from contact v I61 and 169 (Fig. 3-). When valve III is open, bar I65 bridges the contacts. The valve I I i is biased closed by a spring 'I-I. When the valve is open, a circuit is completed from one side of the power supply circuit M through lines I5, II, contact Ifil, bar 165 contact I69, line I9, igniter l3 and line 8,-I to. the other side of the supply circuit.

The relay heater 2| isconnected across the power supply circuit M in series with flame-sensitiye cur nt oo tr le iltthela ter ing so.

sufficiently to snap to their normal ting gas to pilot. burner 3.

positioned that both the 'm in rner and p lot ,minal'. of heater 2-I and one; terminal of cone troller 41:, the other terminal of controller 4|. being connected; by line '81 to the other side of the power supply circuit.

The coil 4. of solenoid valve 3' is connected in series with controller 4| and with a room thermostat As: illustrated, a line 91 connects the terminal of controller II to. which line is C011,! nected and one terminal of the.- solenoid coil 4. The. other terminal. of this coil is connected by a line. 89 including" thermostat I3, and its sta-. tionary contact. 93 to the side of the Supply circuit; Mother than that to: which. l n 8 i nected. I

The operation of the Fig. 3' embodiment is 'asfollows;

Upon a. demand for heat, room thermostat, I3 closes. This does not. establish a circuit through solenoid coil. 4, since. flame-sensitive current controller M is: not. being acted upon by a flame and is non-conductive. If knob 63' is now prshed down and held for a. few seconds, a circuit is completed from one side of supply circuit M through lines I5 and Ti, contact I61, bar I65, contact I69, line 19, ig-niter I3 and line 8%- to the other side of the supply circuit. Valve- EII i also manually opened against the bias of spring II, admit- As soon as, igniter I3 heats su-fiiciently, it will ignite the pilot burner.

The flame of the pilot burnerthen acts upon controller 4 I; t0v cause it to become conductive. This completes a circuit from one side of supply circuit M through. lines t5 and 83, heater 2|, line 85, controller ll and line 81 to the. other side of the supply circuit. Simultaneously, a circuit is completed from one. side of supply circuit lVi through room thermostat. 13, line 89, solenoid coil 4. of valve 3, line SH, controller 41 and line 81 to the other side of the supply circuit. Solenoid valve. 3 thereupon opens, permitting gas to flow to. burner I where it is ignited by pilot 9.

As soon as controller 4i becomes conductive and closes the circuit which includes heater 2I, this heater takes over the holding of discs I2 and I4 in the position to which they were pushed against the resistance of spring II. Knob 63 can therefore be released at this point.

If now room thermostat I3 is satisfied it moves away from its stationary contact 93 and breaks the circuit through solenoid 4. This permits spring 29 to close, valve 3; to shut on the, flow of gas to. burner I. Pilot 9, however, remains lighted so that. controller II remains conducting and valve 3 will promptly reopen when room thermostat I3 subsequently calls for heat.

If now the flames of both pilot 9 and burner I are extinguished, controller 4| will become nonconducting and the circuits through solenoid 4 and through heater 2| are each broken. This permits spring 29 to close valve 3 immediately and after a predetermined time interval, discs the invention, the valve 3 does not open to admitees. o he. b rn unt l h fiame sensi ive c rrent controller 4| has become conductive due to ignition of the pilot burner 9. In the event of flame failure, controller 4| becomes non-conductive and valve 3 closes to shut off the flow of gas to the main burner. Controller 4| is not merely heat-sensitive, but become conductive only in response to flame, hence will not become conductive because of residual heat in the absence of ignition of one or the other of main burner I or pilot burner 9.

Each embodiment of the invention also includes a thermal time-delay relay for delaying the opening of the valve 3 for a substantial interval after initiation Of operation of the system. Thus, in Fig. 1, relay 3! does not close contacts 35 immediately upon closure of switch 25, but delays closure of these contacts until controller 4| has become conductive and heater 45 has been energized long enough to heat discs l2 and M to cause them to snap. In Fig. 2, relay 38 does not move bar 65 to close contacts 51 and 69 immediatel upon ignition of the pilot burner, but delays closure of the contacts until controller 4| ha become conductive and heater 45 has been energized long enough to heat discs l2 and I4 to cause them to snap. In Fig. 3, valve 3 does not open immediately upon closure of room thermostat 13, but opens after the period of time required for controller 4| to become conductive. This period is in turn determined by the length of time it takes heater 2| of thermal relay M8 to heat discs l2 and M sufiiciently to cause them to snap to and remain in the position wherein bar I65 bridges contacts I61 and N59. The provision for delayed action of the main burnervalve 3 in each instance prevents chattering of the valve in the event of any current leakage through controller 4|.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. A gas burner control system comprising a main gas burner and a pilot burner for igniting said main burner, a gas supply line for said main burner, a main valve in said line, a gas supply line for said pilot burner, a pilot valve in said pilot supply line, a main control switch, a thermal time-delay relay including contacts and a heater which, when energized, closes said contacts after a time delay, electrically controlled means for operating said main valve connected in a circuit in series with said ma n control switch and the contacts of said time-delay relay, a flame-sensitive current controller positioned to be acted upon at least by the flame of the pilot burner, said controller being normally non-conductve but adapted to become conductive when acted upon by said flame, said heater being connected in a circuit in series with said controller whereby said heater is energized in response to ignition of the pilot burner and closes said contacts after a time delay thereby to open said main valve, a thermal pilot relay for operating said pilot valve, said pilot relay including a heater which when energized actuates the pilot relay to open the pilot valve, a secondary switch, said pilot relay heater being connected in a circuit under control of said main control switch in series with said 8. secondary switch, and means for'open'in'g'said secondary switch in response to opening of said main valve and for closing it in response to closure of said main valve.

2. A gas burner system as set forth in claim 1, further including an electrical igniter for the pilot burner in series with the pilot relay heater and secondary switch.

3. A gas burner control system comprising a main gas burner and a pilot burner for igniting said main burner, a gas supply line for said main burner, a main valve in said line, a gas supply line for said pilot burner, a pilot valve in said pilot supply line, a main control switch, a normally non-conductive flame-sensitive current controller, the latter being positioned to be acted upon at least by the flame of the pilot burner and adapted to become conductive when acted upon by the flame, electrically controlled means for operating said main valve connected in a circuit in series with said main control switch and said current controller, a thermal time-delay relay controlling said pilot valve having a cold position whereinit closes said pilot valve and a hot position wherein it holds said pilot valve open,

4. A burner control system as set forth in claim 3, further including a pilot burner igniter con nected in a circuit in series with a set of contacts controlled by said pilot valve, said contacts being open when said pilot valve is closed, and closed when said pilot valve is open.

5. A gas burner control system comprising a main gas burner and a pilot burner for igniting said main burner, a gas supply line for said main burner, a valve in said line, electrically controlled means for opening and closing said valve, a flame-sensitive current controller which is normallv non-conductive but which becomes conductive when acted upon by a flame, said controller being po itioned to be acted upon by the flame of the pilot burner, a thermal time-delay re ay compris n normally open thermostatically controlled contacts and an electrical heater which after being energized for a time delay interval acts to hold said contacts closed, and a c rcuit system including said electrically operated means, current controller and relay with the heater of the relay and the current controller being connected in series in a circuit in the system so that the heater is energized whenever the controller has be n rendered conduct ve due to be ng acted upon by the flame of the pilot burner, and with the contacts of the relay connected in another circuit in the sy tem controlling the operation of the burner so that there is a time delay between initiat on of operation of the burner and opening of the valve.

6. A gas burner control system comprising a main gas burner and a pilot burner for igniting said main burner, a gas supply line for said main burner, a valve in said line, electrically controlled means for opening and closing said valve, a flame-sensitive current controller which is normally non-conductive but which becomes conductive when acted upon by a flame, said con i anaese troller being positioned to be actedupon by the flame of the pilot burner, a thermal time-delay relay comprising normally open thermostatically controlled contacts I and an electrical heater which after being energized for a time delay interval acts to hold said contacts closed, said heater and current controller being connected in series in a circuit so that the heater is energized whenever the controller has been rendered conductive due to being acted upon by the flame of the pilot burner, said contacts and electrically controlled means being connected in series in a circuit with said means being adapted to hold said valve open only upon closure of said contacts.

7 A gas burner control system comprisinga main gas burner and a pilot burner for igniting said main burner, 'a gas supply line for said main burner, a valve in said line, electrically controlled means for opening and closing said valve, a flame sensitive current controller which is normally non-conductive but which becomes conductive when acted. upon'a flame, said controller being positioned to be acted upon by the flame of the pilot burner, a thermal time-delay relay comprising contacts, snap-acting thermostatic means controlling said contacts, said thermostatic means, when cold, holding said contacts open,

I and an electrical heater which after being energized for a time delay interval heats said thermostatic means tocause it to snap to a position wherein it holds said contacts closed, said heater and current controller being connected in series in a circuit so that the heater is energized whenever the controller has been rendered conductive due to being acted upon by the flame of the pilot burner, said contacts and electrically controlled REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,106,249 Hower Jan. 25, 1938 2,200,908 Beggs May l4, 1940 2,275,279 Beam May 3, 1942

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