US2493890A - Ignition system for gas or liquid fuel appliances - Google Patents

Description

Jan. l0, 1950I B. L. MATTHEWS ET AL.

IGNITION SYSTEM FOR GAS OR LIQUID FUEL APPLIANCES 2 sheets-sheet l1 Filed June 29, 1945 lllHllIlllIlIllllllh BYl Jan. 10, 1950 B. 1 MATTHEWS Er AL IGNITION SYSTEM FOR GAS 0R LIQUID Fur-:L APPLIANCES 2 sheets4sheet 2 Filed June 29, 1945 RELAY Pno'ro Tues Annu-[ER SOLE Non n I9 l CowoENsoR VA we I' 4]/ nov.

' INVENTORS W 3; wwf,

'ri-MLM' W Wvg-.AD

Patented Jan. 10,, 1950 IGNITION SYSTEM FOR GAS OR LIQUID FUEL APPLIANCES Birchard L. Matthews and Edward J. Zarybnicky,

Cleveland, Ohio, assignors to The W. J. Schoenberger Company, Cleveland, Ohio, a corporation of Ohio Application June 29, 1945, Serial No. 602,242

4 claims. 1

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 experienced with the safety controls employed with these pilots due to the adverse effect which ambient 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 shutolf in case of pilot extinguishment, which will not be interfered with by the heretofore troublesome factor of ambient heat.

It is a further object of the invention to provide for fuel shut-off to the main burner when the height of the pilot flame has decreased to such an extent that it does not give instant ignition, as in the case where delayed ignition results from the pilot orifice slowly closing off due to 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.

A still further object is to provide a photocell ignition system for a gaseous liquid fuel appliance in which the life of the photo-cell is ex` tended to a maximum degree.

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

Figure 1 is a horizontal sectional View of the top portion of a gas range equipped with the improved ignition system;

Figure 2 is a sectional view of the electrically operated control valve; Y p

, Figure 3 is a sectional view of a modied form of ignition pilot for the main burner; and

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

j Referring more particularly to the drawings wherein, for the purpose of convenience, we have shown our improved ignition system applied to a conventional gas range I, having a main enclosed oven burner I5 for which, in this particu-VA of main burner I5 receives its supply through' (Cl. 15S-117.1)

lar embodiment of the invention, safe ignition is to be provided. The range 'I comprises atop burner section or compartment 2, and an oven burner section or compartment 3, separated by a double division wall vIl. Suitably mounted in the section 2 are the front and rear top burners 5 and 6, respectively, to which gas is supplied from a manifold 1, valves 8 and 9 on the mani-v fold being employed to regulate the ow of fuel to and through the top burner mixing tubes I0 and I I. A constant burning pilot I2, which receives a continuing supply of gas from a supply pipe I3, extending between the manifold I and pilot I2, provides for the ignition of top burners 5 and 6, through the medium of flash tubes I4.

The main enclosed oven burner I5 gets its ignition from a sub-burner or pilot I6, having communication with the constant burning pilot I 2, through the medium of a flash tube I1. A pipe I8 connected-atene end to a manually controlled shut-off valve-I9 mounted4 on and communicatingwith the manifold .'I and at` its other end connected to and supporting main burner pilot I6, supplies gas tothe latter when valve I9 is in open position, while the mixing tube 25 shut-olf valve |9pipes 20, 2| vand 22.

The pilot I6 extends from adjacent to the main burner I, to a point, just outside the oven housing 26, where it is connected with the flash tube I1 extending between the pilots I2 andr I6. Consequently when gas is supplied to the main burner pilot I6, a portion of the gas supply will be injected through the ash tube I1 and ignited by the constant burning pilot I2. After the ignition takes place at one end of the sub-burner or pilot I6, gas lwill burn throughout: its entire length thus causing the mainburner to be; ignited.

A conventional thermostaticvalve 23, supported in the front wall 2 4 of the range I andconnected to a thermo Ybulb2'I, positioned within.

' pipes 2| and 22, automatically controls the ow of gas to the main lumrnerl I5 but not to the subburner or pilot I6. Alphoto-electric tube |00 and housing 29 therefor is located` outsidethe oven or combustion chamber 3, in the space 30 between.

creases in height, beyond a predetermined safe,

height for positive ignition, the flame 32 will no* longer appear across the openingatgthat end of the tube, as illustrated in Figure 1. Howevenrin y also close.

the Figure 3 modification, embodying a single..

port ignition pilot I6 a liglrttuberl is adjustable, as to height, with respect'tdthe pilot flame 32'. We accomplish this bysuppo'rting the light tube on one end of a bracket 33', the other end of which is adjustably connedbetween-lock nuts 34 and 35 threadedly mounted on the outlet .end of ignition pilot I6. This enables the operator to accurately positionY the restricted orifice 35 of lightA tubev 3| l" with 4respectto theI pilotjiiame, vso that the moment the-'latter drops below the open-V ing' the devicewillshutcoff. The opening 'Hi in bracket 33', through 'which the outlet end of pilot y'- extendsisof suililcentsize vand the pipe vI8 IQisA sufficiently-resilient Yto permit slight: raising or lowering of thefpilot through the bracket Ywhen the "lock Ynuts 34 and 35 are appropriately manipulated.Y Y 1 suitably: secured to the back wall of range I, remote from the combustiony or oven chamber 3, as by bolts 3.1, is amr-housing 38, for containing an amplifying'tube 39, relay wand transformer 4| which; together with 'the-solenoid Valve 28` and photo-tubel-,receive current'from a 110 volt source. of supply-.43, through thel medium of Vwiring: about tbedescribed'.' The operation ofthe systemzis asfoll'ows:V .f

Assuming thattha constantlburning pilot I2 for thetop.; hurnershasfbeen ignited, its source;

of :the .oven ignition system, and` izhatrthe valves i3. and Hare in; fullgope'mposition, this would'- allow fuel, to ow'irrthemain burner supply line up to,v butl notbeyondithepelectric controlvalve 28. It also would prorideaso'urce cffuel supply` to the sub-burnenpiloti iorrtheisingleport ignitioir pilot |65; as 'the caseimayf. be. 5 A portion" of thefuelthussuppliedewouldibe directed up the flash .tube Ll' b'erfignited by the. .constant-Q burning vpilot |2; The ignition would occurV at thev external: end of `4thesub--burnerzl Scand' carryover. to. the opposite: endi .of "the subelcmrn'erv lo-V cated;y adjacent to the Imain:.burneri1|'51andalso. adjacenttotheflight tube'. 3| .g .The pilotV l5 burningvin front: ottime-light tube3| actuates the photo-.cellvt t. which; inturn, allows current to be passeditlnough` theY amplifier tube 39, thereby actuating the-relay4i-Uiwhich operates the electric control 'valve 28:V This fvalvethn: assumes-V an open position; allowingfuelto. be supplied to the main burner"v f5 'which' ignite'dby -the sub-i burner. i6. Y l fr* f i The photo-cell: l| Mwilll" continuel allowing current j to flow=througlr the ampiiffying tube as long` as the main controlvalve 49 remains in anfopen positionV so thatr fuel can befsupplied:tothe-subn l burner |61 Whenthe main valve` |9 is closed,

4 main fuel line, the system can continuously func-v tion in response to the temperature of the combustion chamber.

In the event of fuel failure, there will be no light source l5 in front of the light tube 3| which prevents the electric control valve 28 .from opening. If the valvey 23 is in an open position at the itime of fuel failure, it will immediately assume a closed position. Furthermore, in the event of velectric power failure, the solenoid valve 28 will If the appliance had been in operation at the time of power failure, it will autoymatically resume operation when the current supply is resumed. In this case, the constant- Vburning 'pilot `|`2 Vhas not been extinguished and the sub-burner l5 has either continued to burn orA can be ignited. Upon resumption of the power, therefore, the sub-burner It will at once actuate Athe photo-tube |95 and'thereby automatically v4e ofiuellbeinggimnoway impaired bythe controls the sub-burner iG-lfisrextinguished and the light i Y 70' 5| until such-timeA as the vcurrent'iiow.isjdesiredf sourcel is removedlfrcmthelight tube'3l, thereby ingL 'current tothe relay, which-assumes an 'openVv to shutoff; 1 When' athermos,taticallyA controlled 1 valvefsuchfasthe'lvalvelkisalso placed in the position and-causes-the electric control Valve 287-' effect ignition of the main burner l5. It will be understood that when fthe' electric power is on the coil 44 ,of` electric valve'willbe energizedthus' causing the plungerv to be lifted from itsl seat 46, against'the tension of spring #2; to place the inlet opening il-in communication with outlet' opening 48.' I Having reference'to Figure 4, itwill be noted that the diagram there shownI consists cfa phototube |98 controlling the-'current ow'throughami plifying tube 33. The' amplifying tube 39 oper# ates the relay 4% '-which, in turn, controls theV operation of the solenoid valve 23. The photo? tube |00 is a two-element tube having a cathode 49 and an anode Y55; The amplifying tube-39 hasan anode 5|, commonly known as the plate ofthe tube, a-cathode 52, anda grid 53; Y n

In the circuit shown, the Athree-step 110 volt A. C. transformer 43| is 'used to supplythe proper. voltage to the various parts in the circuit. A voltage of approgimatelysixvolts'istaken fromk the transformer between the points 54=and 55 to supply current for vcathode heating.-V The properr voltage for the plate circuit'` is taken from the' transformer-'4t between theccnnections'55 and 54. The voltage required for the Vgrid circuit is taken from the transiormerbetween the points 55 and 51. Aresistance fanda condenser 55 are connected in the grid. circuit as shown. The photo-tube` |35 is connected across the grid 53| and the plate 5| of the amplifying tube 39. Thel photo-tube H33; as. previously. described; is con nected so that. it: will pass. current whena lightsource is directed ontoit.y f y Y The` photo-,tube lllfillustrated isk an emissive type of tubesuch as thePJ-ZBaor 9301put-out byl negative-charge on the grid 53.y VvT'sing-jlthis offamplifyingf-tub'e, avrnegative'charge or biais'is 4maintained onthe grid'53 to'prvent current ilov across the plate'v circuit-from cathodeV 52 to plate1- The resistance 5'8 is 'included irithef'circuit to, obtain; the desirednegative ,charge on I*the gridf` 53j. The purpose of the grdconden'sersiis tofY decrease the gridbas-required to 'reduce lthe plate'jV current to a given valuei when' the photo-cell' i's sacaste dark. r'Ihe negative grid voltage is out of phase with the plate Voltage when high values of grid resistance are used. thus making ineffectivethe grid control. `This is due to the input capacity of the tube in combination with the grid resistance. The condenser 59 brings more nearly in phase the effective grid bias and the plate voltage.

The primary coil 60 of the transformer 4| is connected to the house currents. When the system is put into use, therefore, current flows from the secondary coil 6| at 51 through Wire 62, grid resistance `58 and wires 63 and 64Ato condenser 59 and will continue to flow until the latter is charged. After the condenser charge has reached equilibrium, there is no voltage drop in r:e

the grid circuit as long as the photo-tube is dark, as there is no flow of current from the grid 53 of the amplifying tube 39. Since the grid 53 is connected to the resistor 58 and condenser 59 thru wire 65 a negative bias or charge is maintained on the grid 53 of sufficient magnitude to prevent electrons flowing from the cathode 52 to plate 5| of tube 39. It will also be seen that current at the same time flows from the low voltage point 55 thru wire-66, cathode heater 52 and returns by Wire 61 to transformer 4| at point 54 and brings the cathode '52 up to the required temperature for operating the amplifying tube 39. The very low resistance type relay 40 is installed in the plate circuit between the plate and the transformer connection 56. To operate this relay, it is necessary to have a current flow in the plate circuit of the amplifying tube 39.

' By igniting the constant-burning pilot light I2, a source of light is directed onto photo-tube |00. Electrons will then flow from wire 65 thru wire 68 to cathode 49, across photo tube |00 to anode 50 and thence thru wires 69 and'10, relay 40, and wire 1| to transformer tap 56, .this current not being sufficient to operate relay 43. This flow of current thru the photo-tube |00 lessens or decreases the negative bias that had been maintained on grid 53 which immediately allows electrons to flow thru the amplifying tube 39 from the cathode 52 to the anode or plate 5I. The plate circuit then has current flowing from the transformer tap 55 thru conductor 66, amplifying tube 39, fuse 12, relay 40,A 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 110 volt source 43 thru wire 15 contacts 14 and 13, wire 'VI thru coil 44 at solenoid valve 28 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 46 of valve 28 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 delay action on the operation of the relay of from a few seconds to as long as four or five minutes. Itis 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 llame from a match was placed in front of the light tube when ignitingy the pilot. A delay in the starting cycle of sumcient 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 I2v instantly stops the flow of electrons between the cathode 49 and the anode 50 of the photo-tube. 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 l5| of the amplifying tube, thereby causing relay 40 to open contacts 14 and 13 shutting olf current flow to the solenoid valve 28,

which then assumes a closed position, stopping' to its anode and, as explained above, the nega'-A tive blason grid 53 is immediately raised, thereby stopping flow of electrons from theY cathode 52 to theV anode 5| of the amplifying tube. ItV is seen, therefore, that in the event of failure of the life of the photo-tube |00 the system will operate' to a safe condition, as no current will flow to the relay 40 it will assume an open position and shut off the solenoidvalve 28. Y

--It is also apparent that, in the event of fail-r ure of the life of the amplifying tube 39, there can be nocurrent flow from the plate circuit' ofthe tube which results in the relay assuming its open position and causing the solenoid valve 28 to close. l

The fusev 12 is installed in the plate circuit as shown. This is to make the system safe in the event of a short circuitof' 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 circuitis raised above a predetermined value.

It will be noted that by having the photo-tube |00 responsive to a secondary pilot, it is not subject to light rays except when the appliance is in use. Consequently the tube is not deteriorating when the appliance is not in use.

Having thus described our invention, what we claim is:

1. An ignition system for a gaseous or liquid fuel appliance having a fuel supply source, a main burner, a constant-burning pilot remote from main burner, an ignition pilot adjacent to the main burner, a flash tube positioned between the remote pilot and the ignition pilot for lighting the ignition pilot when it receives a supply of fuel, an electrically operated control valve controlling the ow of fuel to said main burner from said source of supply, a photo-electric cell so located as to receive and be responsive to the light from the ignition pilot, and actuating means responsive to the photo-cell for operating said electric main control valve said actuating means including a delay means to prevent the actuating 7; eansfrom opening.; the. electric. valve untilA ai predetermined time;` interval-.has elapsed after lighting the pilot. Y 1

2.y An ignition system having a. mainV fuel source, a main burner, aconstant-burning pilot remote from the. said main burner, an ignition pllotilocated adjacent.Y to said main burner a shutoff valve ink the fuel supply controlling, thel gas to the mainburner andv the ignition pilot.. a iiash tube positioned 'between the remote pilot. andthe ignition pilot for lighting the ignition pilot when. it receives a. supply of gasan electrically operated main control valve in the fuelsup-` ply line, iorcontrolling the flow of fuel to said' main burner, a photo-electric cell responsivey to the flame of tl'ie ignition pilot, a light tubeloey tween the ignition pilot and the photo-electric cell, actuating means responsive to the photo-cell for opening the electric: valve, said actuating means including. ardelay means to prevent the actuatingrmeans from opening the. electric valve until a predetermined time interval has elapsed' after lighting the pilot. e

3. An ignition system having a main fuel source, a main burner, a. constant-burning pilot remote `from the said main burner, an ignition pilot located adjacent to said main burner, a.. shutoi valve in the fuel supply controllingr the gas to the main burner and the ignition pilot, a vash tube positioned between the remote pilot andthe ignition pilot for lighting the ignition pilot when it receives a supply of gas, an electri cally operated main control valve in the fuel'` supply line, for controlling the flow ofY fuel, toy

said main burner, a photo-electric cell responsive.

tothe flame ot theignition pilot, a light tube between the ignition pilot and photo-cellposi tioned with respect to the ignition pilot so that. if the pilot decreases in height beyond a prede-v termined safe height for positive ignition light rays cannot be received by the photo-cell, actu-- ating means responsive to the photo-cell for operating said electric main controlA valve, -said'` means including a delay means toprevent the electric control valve from opening until a pre-i determinedtime interval has elapsed after lighting the pilot. f

4. An ignition system having a main fuel source, a main burner, a: constant-,burning pilot remote from the said main burner, an ignition pilot located adjacent to said main burner, a thermostatically operated temperature control valve in the. fuel supply controlling the fuel to the main burner, a. :dash tube positioned between the remote pilot and the ignition pilot for lighting the ignition pilot when it` receives a supply of fuel, an. electrically operated main control valve in. thevfuel supply line for controlling the supply of; fuelr to said main burner, a photo-electric cell responsive.- to theI flame. of the. ignition pilot, a light tube.v betweenthe. ignition pilot and the photo-electric cell, actuating means responsive to. the photo-cell for operating said electric main control valve, said means includingy a delay means to prevent the electric control valve from opening until a predeterminedtime interval has elapsed after lighting the pilot.

Y BIRCHARD L. MATTHEWS. EDWARD J. ZARYBNICKY.

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

UNITED STATES PATENTS NumberV Name D'ate 1,880,871 VDenison Oct. 4,193.2v 2,072,552- Gauger Mar. 2,1937 2,073,966 Kahn Mar. 16, 1937 2,087,433 rI-Iollman July 20,1937 2,098,192 Matthews Nov. `2,1937 2,112,736 Cokrell Mar. 29,1938 2,274,384 Scanlan Feb. 24, 1942 2,295,045 Mettler Sept. 8,1942- 2,304,641 ,Y Jones'r Dec. 8,1942` 21,343,001 i Cohen Feb. 29,1944 2,357,609 Ray' Sept. 5, 1944 12,360,166' ySehlllilanll et a1. Oct. 10, 1944 Y 2,408,954 'Ray Oct. 8, 1946 234183,84'5. 'Long Apr. 15, 1947 FOREIGN PATENTS Number Country Date 477,679 Y Great Britain Jan. 4, 1938: 657,890

Germany Feb. 12,1933-

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