US2493889A - Ignition system for gas or liquid - Google Patents

Description

Jan. 10, 1950 B. MATTHEWS Er A1.

IGNITION SYSTEM FOR GAS 0R LIQUID FUEL APPLIANCESA Filed June 29. 1945 2 ,Sheets-Sheet l INVENTORS` Arroknfr.

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\. IGNITION SYSTEM FOR GAS OR LIQUID FUEL APPLIANCE` Filed June 29, 1945 2 Sheets-Sheet 2 'SOLENOID VALVE tlf/Y6. V.

RELAY I Patented Jan. l0, 195()v UNITED STATES vPATENT oEFicE l IGNITION s jm ron Gnisson mourn of Ohio Application June 20.71945, Serial No. .02.241

This invention relates to safety control and ignition systems for gas or liquid fuel heating or cooking appliances employing a main burner.

It has been common practice to employ a pilot light or other ignition means, such as a hot wire or spark, for lighting the main burner of such appliances but much difficulty has been experis claim. (ci. iss-111.1)

enced with the safety controls employed with I these pilots due to the adverse effect which arnbient heat has had upon such prior controls.

One of the principal objects of the invention is to reduce the hazards encountered with prior safety pilot controls incident to current failure, fuel failure, or extinguishment of the pilot light.

Another object is to provide positive fuel shutoff in case of pilot extinguishment, which will not be interfered with by the heretofore troublesome factor of ambient heat.

2 ment wherein a heating or cooking burner is employed.

The range i comprises a burner section or compartment 2, housed within-a casing 3 and containing the burner I, which gets its ignition from a constant burning pilot Il, described more in detail hereinafter. A pipe I connected at one end to a gas manifold 'I and at its other end to the pilot II, supplies gas to the latter, while the mixing tube l of burner l receives its supply from the manifold 1, through the medium of a fuel pipe or line l. The inlet end of this line 9 is connected to the manifold 1. A thermostatically controlled valve ii and an electrically controlled valve Il, both of conventional construction, are interposed in the fuel line I, between the manually operated shut offy valve lo and the mixing tube l. Valve i I, which is supported in the front It is a further object of the invention to provide for fuel shut-off to the main burner when from the pilot orifice slowly closing off due'to v foreign matter in the fuel.

Still another object of the invention is to provide an automatic ignition system in which a time interval will occur between the lighting of the pilot and the ignition of the burner, thus assuring the person lighting the pilot sufficient time to perform this operation and remove his hand from the combustion chamber before fuel is allowed to flow to the main burner. y

Other objects and advantages will be in part described and in part obvious as the description is considered in connection with the accompanying drawings, in which:

Figure 1 is a horizontal section view of the top portion of a gas range, equipped with thel improved ignition system;

'Figure 2 is a sectional view of the solenoid valve employed in the system;

. Figure 3 is a sectional view of a modified for wail i8, of the casing I and connected to a thermo-bulb I3, positioned within the burner section or compartment 2, automatically regulates the oven temperature without interfering with the valve il for manually turning the burner 4 on or off. Valve II could be readily replaced by an electric thermostat (not shown) that would operate the solenoid valve i2, in response to temperature changes in the oven chamber when the ignition system, about to be described, is functioning properly. A

Electrically operated control valve i2, described more in detail hereinafter, automatically controls the flow of gas to the main burner but not to the pilot It. A photo-electric tube and housing 29 therefor is located outside the oven or comof ignition pilot which is relatively adjustable with respect to the light tube; and

Figure 4 is a diagrammatic view of the electric circuits employed in the system.

Having more particular reference to the drawing wherein, for the purpose of convenience, we have shown our improved ignition system applied to a range I, having a burner 4 for which, in the embodiment of the invention herein shown, safe ignition is to be provided. However, it willbe understood that the invention is applicable for bustion chamber l, inthe space 30 between the division walls Il, and a light tube Il, fixedly mounted in bracket $3, is positioned between the photo-tube illi and the ignition pilot i6, for directing light from the pilot flame I2 of pilot`4 i6, to the photo-tube il.. In the event the pilot flame 32 decreases in height, beyond a predetermined safe height for positive ignition, the flame 32 will no longer appear across the opening at that end of the tube, as illustrated in Figure 1.

In Figure 3 I have disclosed a modified form of the invention wherein a pilot it is connected to a light tube Il. for relative movement with respect to each other, by means of a bracket 33'.

' One end of the bracket I3' is bolted to the free end of the tube 3|', and at its other end is adiustably confined between lock nuts 34 and 35 threadedly mounted upon the outlet end of the pilot il', which projects loosely through the opening 2lln that 4end of the bracket 33'. This use with all forms of heating and cooking equip- 56 enables the operator to accurately position the silience of the' pipe 9 on which the pilot Is.-l

mounted is sufilcient to permit slight movement of the pilot relatively to the light tube. Pilot It is identical with pilot I with the exception that it employs the lock nuts I4. and is physically connected to the light tube.

Suitably secured to the back wall of range I, remote from the combustion or oven chamber 2, as by bolts 21, is a housing Il, for containing an amplifying `tube I9. relay and transformer 4I which, together with the solenoidvalve I2 and' photo-tube I0., receives current from a, 110 volt source of supply 49, through the medium of wir-` ing about to be described. The operation of the system is as follows: v Y

Assuming that the constant'burning pilot I9,l

. which receives gas direct from the manifold 1,

has been ignited by hand, and that the valves I0 and II are in full open position, fuel will flow through the supply line 9, of the main burner 4, up to but not beyond the electric control valve I2. The pilot Il burning in front of the light tube 9| actuates the photo-cell |00 which, in turn, allows current to be passed through the amplifierl tube 99, thereby actuating the relay 40 which operates the electric control valve I2. This valve then assumes an open position, allowing fuel to be supplied to the main burner 4 which is ignited by the pilot IG.

Photo-cell will continue allowing current to flow through the amplifying tube as long' as the photo-cell |00 receives light from the .ignition pilot I6. In the event pilot I l is extinguished,` light is no longer received by photo-cell |00. thereby preventing the amplifying tube 39 from supplying current to the relay 40, which assumes 4 operation of the solenoid valve I2. The phototube |50 is a two-element tube having a cathode 4I and an anode 50. The amplifying tube Il has an anode 5| commonly knownfas ythe plate of the tube, a cathode 52. and a grid 5I.

In the circuit shown, the three-step '-110 volt A. C. transformer 4I is used to supply the .proper voltage to the various parts in the circuit. A voltage of approximately` six volts is taken from the transformer betweenthe points 54 and 55 to .supply current forcathode heating. The proper lvoltage for the plate circuit is taken from the transformer 4I-'between the yconnections 59 and f54. The voltage required for the grid circuit is vtaken from the transformer between the points and 51. A resistance 59 and a condenser 59 are connected in the grid circuit as shown.' The Vphoto-tube |00 is connected across the grid 5I and the plate 5I of the amplifying tube 39. 'I 'he photo-tube |00, as previously described, is conv nected so that it will pass current source is directed on to it. I

The photo-tube |00 illustrated is type of tube such as the PJ-23 or 930 put out by the General Electric Company. The amplifying tube 39 is acommony low powerradio receiving 4when a light type of tube. It is not the intent of this descriptive material, however, to limit the device to these particular types of tubes.

In the device shown, which includes a common type of amplifying circuit, the photo-tube |00 will not pass current unless it is receiving a beam of light. The amplifying tube 39 will not pass current except under proper conditions of negative charge on the grid 53. Using this type of amplifying tube, a negative charge or biasis maintained on the grid 53 to prevent current ow across the plate circuit from cathode 52 to plate 5I until such time as the current flow is dell! sired. 'Ihe resistance 59 is included' in the circuit to obtain the desired negative charge on the an open position and causes electric control valve I2 to shut off. When a thermostaticallyv controlled valve, such yas the valve II, is also-placed in theA main fuel line, the system can continu` ously function in response `tothe temperature of the combustion chamber as long as pilot I0 is ignited.

In the event of fuel failure, there will be no` iight source I6 in front of the light tube ll: which prevents the electric control valve I2 from opening. If the valve I2 is in an open position at the time of fuel failure, it will immediately assume a closed position. Furthermore, in the event of electric power failure, the solenoid valve I2 will also close. If the appliance had been in operation at the time of power failure, it will automatically resume operation when the current supply is resumed. In this case. the pilot Il has either continued to burn or can be ignited;y

` Upon resumption of the power, therefore, the

pilot I8 will atonce, actuate the photo-tube .IIII

` and thereby automatically effect ignition'of the 3 main burner 4. It will be understood that when the electric power is on the coil 44 of electric valve I2 will be energized thus causing the" plunger 45 to be lifted from its seat 40, against the tension of spring 42, to'place the inlet opening 41 in communication 'with outlet opening 49.

' Having reference to Figure 4, it will be noted grid V53. The purpose of the grid condenser 59 is to decrease the grid bias required to reduce the plate current to a given value when the photo- 45 cell is dark. The negative grid voltage is out'of phase with the plate voltage when high values of grid resistance are used, thus making ineffective thegrid control. This is due to the input capacity of the tube in combination with the grid resist- '6.0 ance. The condenser 59 brings more nearly in phase the effective grid bias and the plate voltage. The primary coil B0 of the transformer 4I is Vconnected to the domestic voltage supply. When v the system is put into use, therefore, current flows from the secondary coil 6I at 51 through wire 00 the grid circuit as long as the photo-tube is dark. A t

B2, grid resistance 58 and wires53 and 64 to con- Y denser 59 and will continue to ow until the latter is charged. After the condenser charge has -reached equilibrium, there is no voltage drop in as there is no iiow of current from the grid 53 of the amplifying tube 39. connected to the resistor 59 and condenser 59 thru wire 65 a negative bias or charge is maintained on the grid 53 of suflicient magnitude to prevent electrons owing from the cathode 52 to plate 5I of tube 39. It will also be seen that current at the same time flows from the low voltage point .5S-thru wire 66, cathode heater 52 and returnsby wire61 to transformer 4I at point 54 and brings the cathode 52 upto the required temperature for operatingvthe amplifying tube 99. The very low resistance type relay 40 is installed in the plate circuit'between the plate 5| and the 7 6 transformer connection 5I. `'I'o operate this relay.

an emissive Since the grid 52 isk it is necessary to have a current now in the plate circuit of the amplifying tube 39.

By igniting the constant-burning pilot light Il, a source of light is directed on to photo-tube |00. Electrons will then flow from wire 65 thru wire 88 to cathode 49, across vacuum tube to anode 50 and thence thru wires 69 and 10, the coil of relay 40, and wire 1| to transformer tap 56. The low current from the photo-tube passing through the coil of the relay is not of suillcient strength to cause the relayto close contacts 13 and 14. This flow of current thru the photo tube |00 lessens or decreases the negative bias that has been maintained on grid 53 which immediately allows electrons to flow thru the amplifying tube 39 from the cathode 52 to the node or plate 5|. The plate circuit then has current flowing from the transformer tap 55 thru conductor 66, amplifying tube 39, fuse 12, relay 40, and back to transformer connection 56. This current flow will actuate relay 40 so as to make contacts 13 and 14. Current will then flow from the volt source 43 thru wire 15 contacts 14 and 13, wire 11 thru coil 44 of solenoid valve I2 and thence back thru wire 16 to said source 43. The coil 44 will then be energized, magnetically raising valve plunger 45 against the pressure of spring 42, thus opening passageway 49 of valve l2 and permitting fuel to flow to main burner.

When the photo-tube |00 is illuminated, it acts as a resistance in the circuit, and when passing current through the photo-tube to reduce the negative bias on the grid 53, a delay in the reduction of negative bias is caused until the condenser discharges. It is seen, therefore, that there is a time factor directly related to the resistance flow of the photo-tube and the size of the grid condenser, delaying the action of the amplifying tube 39 and the actuation of the relay 40. This delay time factor is a product of the resistance of the photo-tube in megohms and the condenser value in microfarads. By using the proper size condenser, it is possible to get a relay action on the operation of the relay of from a few seconds to as long as four or flve minutes. It is apparent that, without a time delay on the starting of the cycle, the device would operate so quick that gas would be allowed to flow to the main burner the instant that a flame from a match was placed in front of the light tube when igniting the pilot. A delay in the starting cycle of sufficient time to allow the person to ignite the pilot and'withdraw his hand from the combustion chamber is therefore highly desirable.

Extinguishment of constant-burning pilot I instantly stops of the ow of electrons between the cathode 49 and the anode 50 of the phototube. The negative bias on grid 53 of the amplifying tube 39 is immediately raised, and thereby instantly cuts off electron flow from the cathode 52 to the anode 5| of the amplifying tube, thereby causing relay 40 to open contacts 14 and 13 shutting off current flow to the solenoid valve |2, which then assumes a closed position, stopping the flow of gaseous fuel to the main burner. It is seen, therefore, that pilot extinguishment or fuel cut-off will instantly cause the ignition system to assume a safe condition by shutting oil! the flow of fuel to the burner. And, should the current foil, the relay 40, which is normally in anv open position, immediately assumes this position.

In the event of failure of the life of the phototube no electrons will pass across its cathode 49 to its anode 50 and, as explained above, the negative bias on grid 53 is immediately raised, thereby stopping flow of electrons from the cathode I2 to the anode 5| of the amplifying tube. It is seen, therefore, that in the event of failure ot the life of the photo-tube |00 the system will operate to a safe condition, as no current will ow to the relay 40.. Its contacts 13 and 14 will remain open and the electric control valve I2 will assume a closed position.

It is also apparent that, in the event of failure of the life of the amplifying tube 39, there can be no current flow from the plate circuit of the tube which results in the relay assuming its open position and causing the solenoid valve |2 to close.

The fuse 12 is installed in the plate circuit as shown. This is to make the system safe in the event of a short circuit of the photo-tube. If the photo-tube is short circuited, a heavier flow of current results in the plate circuit. A fuse, therefore, can be properly sized in the plate circuit to blow if current in the circuit is raised above a predetermined value.

Having thus described our invention. what we claim is:

1. An ignition system for a gaseous or liquid fuel appliance comprising a fuel supply source, a main burner, a constant-burning pilot burner for said main burner, electrically operated main cont trol valve for controlling the flow of fuel to said main burner from said source of supply, photoelectric cell responsive to the light from the pilot burner, a light tube positioned with respect to the constant burning pilot burner so that if the pilot decreases in height beyond a predetermined height light rays cannot be received by the photocell, actuating means responsive to said photocell for operating said electric main control valve, said means including a delay means to prevent the electric control valve from opening until a predetermined time interval has elapsed after lighting the pilot burner.

2. An ignition system comprising a fuel supply, a main burner, a constant-burning pilot burner, a photo-electric cell so located as to receive and be responsive to the steady source of light from the pilot burner, and means responsive to photo-cell for controlling the ow of fuel to the main burner said means including a delay means to prevent the said responsive means from opening until a predetermined time interval has elapsed after lighting the pilot.

3. An ignition system for gas and liquid fuel appliances having a fuel supply source, a main burner, a constant burning pilot burner, an electrically operated control valve controlling the i'iow of fuel to said main burner from said source of supply, a photo-electric cell located so as to receive and be responsive to the light from the pilot burner and actuating means responsive to the photo-cell for operating said electric main control valve, said means including a delay means to prevent the said responsive means from opening until a predtermined time interval has elapsed after lighting the pilot burner.

BIRCHARD L. MA'I'IHEWS. EDWARD J. ZARYBNICKY.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,880,871 Denison .c Oct. 4, 1932 (Other references on following page) 11m A Date Gohan nb. 20. 1044 Ray Sept. 5. 1044 'Schumann et al. Oct. 10, 1944 Ray Oct. 8, 1046 Inn! Apr. 15. 1947 rI'DRIKIN PATENTS Cmmtry 'Dn Y Great Britain Jan. 4, 1038' Germany Feb. 12, 1,933

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