US2372564A - Burner control apparatus - Google Patents

Description

Mmh 27, 1945. R. K ENGHoLD'r BURNER CONTROL APPARATUS Fild July 21, 1941 v INVENTv Elle/card Af. .5gg/2 Patented Mar. 27, l l

UNITED `STATES PATENT omet:

nUaNna'couAPPAaA'rUs l Richard K. Engholdt, Milwaukee, Wis., assigner to Milwaukee Gas Specialty Company, Milwauf kee, Wis., a corporation of Wisconsin application July 21, 1941, serial Nc. 403,256 zo clpnns. (ci. s-111.1)

This invention relates, generally, to burner contion with the accompanying drawing', one 'pre-l trol apparatus and it has particular relation to. ferred embodiment of the invention.

`means for varying the proportioning ofthe gasl In the drawing:

or other fuel and air in the fuel-air mixture for Figure 1 is a diagrammatic view showing an aburner. 5 embodiment of the present invention in a main Heretofore in the art, quiet and effective ig-- burner and pilot burner gas supply system;

nition and shut-down of. the burner were not l Figure 2 is a vertical section through the theralways assured, especially where the fuel and mo'electric control valve shown in Figure 1; and i air, and particularly the gas and air, have been Figure 3 is an enlarged elevational view showproportioned to give best results during no1-'mal 10 ing the thermocouple in more detail.

or continued burner operation. Instead, such The invention can be embodied in a wide vasystems have been subject to dangerous and anriety of forms for use with a wide variety of,

noying explosions upon ignition and shut-down systems, but for 'purposes of illustration the inofthe burner. ventionohas been shown as embodied in a thery One of the main objects of the present inven- 15 moelectric safety shutoff and Condition respon- .tion is to provide a system for varying the prosive control system including a complete safety portioning of the gas or other fuel and air in shutoff and condition responsive control which the fuel-air mixture for the burner, which sysis Operative to enrich the fuel mixture, and partem is operative to enrich the fuel mixture, and ticularly the gas-air mixture, for e gas burner particularly the gas-air mixture for a gas burner upon ignition and shut-down of the burner for upon ignition and shut-down of the burner. the purposes set forth.

The enrichment of the fuel-air mixture is se- Referring to the drawing, the burner l0 is any cured by supplying excess fuel to the burner upon Suitable O1 preferred mein burnerit may be ignition and shut-down, and one cf the chief adthe main burnerior a room 0r. Space heater. 0r vantages thereof is the ability to provide quiet l Z5 if' may be the burner OI' 9' Wat@r heater. 0l' e flOOr andcnectlve ignition and shut-down cf the burnfurnace, an Oven burner. one or more top burncrwithout dangerous or annoying expiosi-ons, and ers for a gas range, 0r any other burner. with the burner adjusted to give best results dur A gas or other fuel supply pipe ll leeds to the ing normal or continued burner operationI burner l0 for the delivery of gas or other fuel Another object of thomvention is to prothereto-#for example, through an outlet or devide a burner control apparatus having safety livery orifice into a mixing chamber l2 in which shutoff and condition responsive control means the fuel is mixed with air which enters the mix.

for the burner, which safety shutoff and` condilng chamber through one 01' lllol'e Ports usually tion responsive control means is operative to -en- Provided al' the Outer end |30f the mixing Chemrich the fuel mixture and, particularly, the gashelaas Well understood in the alt- The 60mair mixture for the burner ,uponignition and bustible mixture of gas 'and air passes from the shut-down of the burnermixing chamber I2 through a conduit Il to the Another object of the invention is to provide' burner I0 where it is delivered through the ports an improved safety shutoff and condition respon- 4uf the burner and lgulted by a' Pllot burner l5 sive control means for the burner. 40 The pilot burner |5- Whlch ls located ln lllxta" Another object of the invention is to provide poslllou t0 the ma'ln burner lo t0 maintain a Pilot burner control apparatus of' theharacter deflume l5 ful' lgultlug the mail! burner, l5 Supplied scribed which is of simple character, effective in With gaseous fuel by 9 Pilot Supply Pipe l1 The operation, and which Wm fail safey pilot supply pipe I1 is shown as receiving its fuel while the particular structuren features and 45 from the main fuel Supply pipe Il thrvush the combinationsA by which I obtain a device of the Pilot Outlet I8 0f the thermoelectric valve. indivcharacter set forth are important features withcated ln its entirety at 2. The Pilot burner l5, in the more specific aspects of the invention, it when ignited, is shown as maintainin a Second is to be understood that meipfooiso futures pilot flame 2l for heating the.hot' junction of shown and described may be varied within the the-thermoelectric generator which is shown in broader aspectsof the invention v 'f the `form 0f a thermocouple 22. :It is understood, `In order to acquaint those skilled in the art of course, that the thermoelectric generator may with the manner of constructing and operating be in the form of a vthermopileaor of any other burner control apparatus inaccordance with the desired form, and that the pilot burner l5 may 'present invention, I will now describe, in connec- 55 maintain only a single pilot flame for igniting the for heating the thermoelectric control valve 25 shown in the form of a diaphragm valve.- This valve is responsive to the pilot burner I 5. It may also be responsive to other control devices shown, for purposes of illustration, in Figure 1 as a thermostat 26 and a limit switch 2l. In the case of a room or space heater or noor furnace, the thermostat 26 may be in the form of. a room thermostat mounted in appropriate position within the room or other space heated by the main burner I0, or, in the case of a. hotvwater heater, the thermostat may be subject to the temperature oi' the water in the tank.

The limit switch 2l may be of a character to operate upon the occurrence of any abnormal. defective, or insumcient functioning of the apparatus, as, for example, upon the occurrence of an abnormal pressure in the tank of a hot water heater, or upon the occurrence of an abnormal temperature.

The diaphragm valve 25 comprises a main valve body part 2t having an inlet chamber il@ and a pair of outlet chambers 3i and 32. The outlet chamber 3i is interposed between the inlet chamber 3B and the other outlet chamber 32, and is 'adapted to supply gas from the inlet chamber 3@ to the outlet chamber 32 as will presently appear.'

Contiguous sections of the fuel supply pipe "il are.

connected at 3 and 35, respectively, in communication with the inlet chamber @t and outlet chamber 3 I.

The valvebody part 2t has at one`end of the outlet chamber or passage @I a valve seat llt for a main shuto valve member 39. At the other end of the outlet chamber or passage the valve body part 2t has a valve seat #it for an excess gas shutoi valve member d2. The valve members 39 and l2 may be in the form of valve disc members carried by a valve stem t5 which may be guided, `as desired, in the valve body, and which is shown as connected at it to a exible diaphragm t. i

The periphery of the diaphragm E8 is clamped between the valve body part 28 and a hood or cover 439 which may be secured in place to the valve body part 28 by screws-or other suitable means. between the hood or cover A9 and the diaphragm 48. A restricted bleed port 52 is provided for bleeding the gas from the diaphragm chamber into the chamber 32 to relieve the head pressure on the diaphragm upon shutting oil the delivery of gas to the diaphragm chamber 50, as

` will presently appear.

An excess gas supply pipe 54 leads, at 55, from the outlet chamber 32 for the delivery of 'excess gas to the main burner I0, for example -through the mixing chamber I2, upon ignition and shutdown of the main burner.

The particular thermoelectric valve 28 selected for illustration is similar to that more fullydisclosed in the copending application of Stanley S. Guelson, Serial No. 334,159, illed May 9, 1940.

For the purpose of the present description; suice it to state that the thermoelectric valve 28 comprises a. valve body having an inlet 6I, the pilot outlet port I8 for delivering fuel to the pilot burner I 5, and a second outlet port 62 and a pipe A diaphragm chamber so is provided` 63 connected 'thereto through which gas is adapted to be delivered into the diaphragm chamber 50. A pipe 6l, connected at one end tothe inlet 6I of the thermoelectric valve 20 land at its other and to the main zal Supply Pipe II anterior body 60. Fixed in the mounting cup 66, as, for

example, by molding the insulating' material of the cup thereto and extending endwise from the cup, are a pair of spaced metallic terminal menibers 6l' and 68 having aligned openings 69. The terminal members 8l and 68 are split outwardly of the openings G9, and the split portions are adapted to be clamped together by screws lil.

A magnet housing in the form of an outwardly opening metal cup ll, is mound upon the mounting cup 66, for example, by pressed iit engagement of its outer end in the mounting cup. The magnet cup FI is reduced at its inner end, and the armature housing, which is also in the form of an outwardly opening metal cup l2, m mounted on the cup li, for example, by pressed nt engagement of its outer open end telescopically over the reduced inner end of the cup li. The inner end of the cup l2 is preferably reduced, as shown.

The electromagnet is shown as comprising a generally U-shaped magnet frame E3 positioned Within the cup I I, with its legs extending through openings in the inner end of the cup il and presenting pole ends within the armature cup l2. The form of the magnet frame may be varied, and variations in the other parts of the apparaatus are also contemplated within the scope of the present invention. The particular magnet frame TIS selected for illustration has a threaded stud it integral therewith, or welded or otherwise secured thereto. This stud 'i4 'extends into an opening or recess l5 in the mounting cup at, and has threaded engagement with a nut f 'it for clamping the magnet frame rigidly and, at the same time, removably in place. The nut i6 has a kerf'for engagement by a screw driver or other tool, and a sealing washer may be provided at lll.

The magnet coil 'i8 surrounds the legs of the magnet frame 13, and the leads of this coil have their bared ends connected to the terminal members 61 and 68 in a manner to have good conducting contact therewith, as, for example, at 'IQ and 80. The coil I8 is preferably covered with insulation between its bared ends. If desired, additional insulation may be provided between the turns of the coil and the legsof the magnet frame, and between the inner end of the cup il and the adjacent end of the coil.

The armature 82 is disposed in the armature cup 12, and is adapted to be held in attracted position against the pole ends of the magnet frame I3 when the electromagnet is energized. The armatureBZ is of disc-like form and is secured to one end of a reciprocatory stem 33. The attachment of the armature 82 to the stem 83 may :be suiliciently loose or otherwise of a character to permit self-accommodation of the armature to the pole ends of the magnet frame. The stem 83 is disposed'generally concentrically of the armature housing 'l2 and extends inwardly for reciprocatory movement through an opening 84 in the inner end of the housing l2.

The valve member 85 is ilxed by a pin 86 upon the opposite end of the stem 83, preferably for some relative movement thereon so as to have self-accommodating seating engagement with the cooperating valve seat 81 at the adjacent end of .the valve seat member 88 which is shown as -sealsthe device against the escape nient therewith is a reset member 91 abutting engagement witha spring disc 98. The

y the disc 88 and the valve seat member 88.

. fuel flow interruptor spring y of the valve seat member material is interposed bethe armature housing 12 ,and a valve spring seating disc 90. The valve spring 9| is inthe form of a coil spring surrounding the inner end of the stem 83 and interposed between the valve member 85 and the spring seating disc 80. The spring 9| moves the armature 82 to retractedposition and the valve member 85 to closed position, seating upon the valve seat 81 to shut off the ow of fuel to the pilot outlet I8 and to theoutlet 82 when the electromagnet is deenergized. y

The disc- 90 seats inwardly upon a shoulder 92, andthe action of the spring 9| compresses the packing 89 and maintains same in sealing engagement with the bore within the valve body 80 and with the stem 83. The interior of the armature housing is thus sealed from the gas or other fuel which passes through the valve body, and the escape of fuel out around the armature housing is prevented. A washer at 93 further of fuel. A reset stem 95 extends out through the opposite end of the valve body 80. This reset stem is mounted coaxial with the valve member '85 and for reciprocatory movement. The stem 95 is provided at its outer end with a reset knob or button 88.

Fixed upon the stem 95 for reciprocatory movewhich has spring disc 98 is slidable inthe cooperating cylinder part of the housing and constitutes Aa reset guide in the resetting operation. A spring 99, shown as of coiled form, is interposed between A is interposed between the spring disc 98 and a flow interrupter disc valve |02. A retainer is provided at |03 for limiting inward movement of tite disk valve |02 relative to the reset stem 95.

. The flow interrupter valve |02 is adapted to seat upon the valve seat |84 at the adjacent end 88 to shut off or interrupt the flow of fuel to the outlet 82 during the resetting operation and until the valve member 85 is held in open position by the thermoelectric current and the reset stem 95 is released. The reset member 91 has a tapered or generally conical portion which, under the `action of the spring means, is heldseated against a cooperating annular shoulder or'seat on thevalve body to seal the opening through which the reset stem'95 extends lwhen the'reset stem is positionedl as shown in Figure 2.

While any othery suitable or preferred thermol couple, thermopile, or other thermoelectric generator and lead connection may be employed within the scope of the present inventionI the particular thermocouple and lead connectionl shown in the drawing are of the general char-y acter. disclosed and -claimed in Oscar J. Leins Patent No. 2,126,564, granted August 9; 1938.

The thermocouple designated in its entirety at 22v comprises an outer tubular metallic thermocouple member ||0 and an inner metallic thermocouple member ||2 disposed within the outer thermocouple member and joined at one end to the outer thermocouple member to form the thermal junction ||4 which is positioned to be heated by the pilot flame 2|.

therxnocouple member-for example, through a sleeve ||8to form a H9. The outer lead conductor and outer tubular thermocouple member enclose the inner lead conductor and inner thermocouple member. The inner lead conductor ||5 is insulated from the outer lead conductor l1, for example, by a wrapping of insulation on the inner lead conductor.

The thermocouple may be supported with the hot" junction ||4 thereof in position to be heated by the pilot flame 2 |for example, by a bracket on the pilot burner, or otherwise as desired. The pilot burner l5 may likewise be supported in position to ignite the main burner and to heat the hot junction of the thermocouple by any f suitablel or preferred means.

To start the operation of the system as thus far described, the following sequence is followed:

The reset stem 95 is pressed inwardly to actuate the valve member 85 to open position and position in contact with the pole faces of the magnet frame 13. This allows gas to flow from the gas supply pipe through the pipe 84, inlet 6|, inlet chamber 55,

pilot outlet |8, and pilot supply pipe |1, to the pilot burner I5 where the same is ignited. The stem 95 is held in depressed position until the pilot flame 2| has heated the thermocouple sufiiciently to energize the magnet 13 so that it will hold the armature 82 attracted thereto and thereby the valve member 85 in open position.

The flow interrrupter disc |02 seats upon the A seat |04 to shut off the flow of fuel to the outlet 52 'as long as the stem 95 is pressed inwardly.

When the magnet is energized sufficiently' to hold the armature 82 in attracted position and the valve member 85 in open position, the reset stem 95 is released, thus allowing the flow interrupter disc to return to open or normal operating position. Fuel then flows out through the outlet 62 and pipe 83, assuming that the small solenoid valve |20 interposed liin thev pipe 63- is open, to the chamber 50 of the diaphragm valve. 'I'he flow of gas into the diaphragm chamber 50 forces the diaphragm 48 in a downward direc.

tion as the apparatus is viewed in Figure l. As the diaphragm 48 is forced downwardly, the lower valve disc 89 is opened, and gas ows from the lower valve chamber 30 into the intermediate and upper valve chambers 3| and 82. A

Gas thereupon flows out through the outlet 85 to the main burner orifice, and before the upper valve disc member 42 seats upon the seat 40 to shut off the upper valve chamber 32 gas also flows out through the outlet 55 and the excess gas pipe 54 to the burner. Momentarily, therefore, there is an excess amount of gas forced into the primary air stream for the main burner, and a soft ignition flame results. As the diaphragm 48 continues down, the upper valve disc member 42 seats upon the valve seat 40 and closes off the upper valve vchamber 32, and, consequently, the excess gas supplyfor the main burner. Gas then flows to the main burner through the central valve chamber 3| and outlet 35 to supply fuel for -An inner lead condgctor ||5 is joined to the lconductor ||1 is connected to the outer tubularf ive best results urner operation.

during normal or continued The excess'gas which is dis- .l charged into the valve chamber 32 throughthe bleed port 52 as long as there is head pressure in chamber 50, and which passes through the pipe 54 into the mixing chamberv I2 along with they fuel delivered through the orifice or pipe I may be consideredas apart of the metered gas for normal operation.

third thermal junction .the 1imit switch 2l.

If the pilot burner is not lighted to produce the thermoelectric current for holding the armature in attracted position and the valve member 85 open, the armature 82 willbe actuated to retracted position and the valve member 85 to closed position upon release of the reset stem 95.

If, following normal or continuous burner operation, the pilot burner is extinguished so that the thermal junction il@ is no longer heated sufficiently to set up the thermoelectric current for energizing the electromagnet to hold the armature 82 attracted and the valve member 35 open, the armature 82 is released and the spring 9| moves the armature to retracted position and the valve member 85 to closed position, shutting off the flow of gas not only through the pipe il to the pilot burner, but also the iiow of gas through the pipe 63 to the diaphragm chamber 60. With the supply of gas to the diaphragm chamber 50 shut off, the head pressure on the diaphragm 48 is bled oi` through the bleed port 52, and the spring |25 in the diaphragm valve moves the valve disc members 39 and l2 in an upward direction as the device is viewed in Figure 1.

As the lower valve disc member 39 starts to close, the upper valve disc member 42 immediately opens, allowing excess gas to iiow to the burner, thus softening the flame momentarily upon shut-down of the main burner. Further movementof the lower valve disc member 39 in an upwarddirection seats the same upon lthe valve seat 38, thereby shutting down the supply of fuel to the main burner.

The small solenoid valve in the gas supply pipe leading from the outlet 62 of the thermoelectric valve 20 to the chamber Si! of the diaphragm valve constitutes a part of the additional condition responsive control.

This additional condition responsive control is provided by connecting the solenoid valve i2@ into a condition responsive circuit |30, which is shown as including therein the thermostat 25 and The thermostat 26 comprises a bimetallic element 26a having a contact arm 2Gb. The contact arm 26h is moved by the bimetallic element 26a into engagement with a contact |32 when the temperature drops to a predetermined value, and when the temperature to whichl the bimetallic element 26a is subject rises to a predetermined value the contact arm 26o moves out of engagement with the contact |32 to open the circuit for the solenoid valve |26. A

The limit switch 2l is shown asvcomprising a contact arm 21a which moves out of contact with the contact 2lb upon the occurrence of the limiting temperature, limiting pressure, or other abnormal condition for which the limit switch is set, and remains in contact with the contact 2lb as long as the limiting temperature, pressure, or other abnormal condition is not reached.

A step-down transformer |35 supplies power for the condition responsive circuit i3d. Thistransformer is shown as comprising, for ex= ample, a line voltage primary winding |36 and a llow voltagesecondary winding |31. The primary winding |36 is connected to line wires |38 leading to any suitable source of power (not shown), and the secondary winding |31 is connected into 'the condition responsive circuit |30.

As long as the condition responsive circuit is closed, the solenoid valve |20 is held in open position, and the system' operates as already described. n p

Upon opening of either thev thermostatic switch at 26 or the limit switch at 2li, the condition responsive circuit |30 is opened. This deenergizes the solenoid valve |20 which is closed, for example, by a spring (not shown), shutting o the supply of gas to the chamber Ei@ of the diaphragm valve 25, which together with the seating of valve 39 on seat 38 results in shutting down of the fuel supply to the main burner. At this time, however, the valve member t5 of the thermoelectric valve 20 remains open for the supply of fuel to the pilot burner i5 as long as the pilot burner is ignited.

If the main burner fuel supply is shut down by the operation of either the thermostatic switch 26 or the limit switch 2,1 with the pilot burner lighted, then, assuming that the pilot burner remains lighted, when the thermostatic switch at 26 or the limit switch at 2l again closes the condition responsive circuit |30, the solenoid valve |20 will open and ignition of the main burner will follow in the manner already described.

The embodiment of the invention shown in the drawing is for illustrative purposes only, and it is to be expressly understood that said drawing and the accompanying specification are not to be construed as a definition of the limits or scope of the invention, reference being had to the appended claims for that purpose.

I,clalm:

1. A burner control apparatus comprising, a burner, a fuel supply pipe for supplying fuel to said burner, an excess fuel supply pipe for supplying excess fuel to said burner, a valve member controlling admission of fuel to said excess fuel pipe having open position upon starting the burner and operable t0 closed position to shut off the excess fuel supply to the burner as the burner reaches substantially normal or continuous burner operation, and means for moving said valve to open position upon starting the burner and. to closed position as the burner reaches substantially normal operation, said means preventing starting the burner without an excess flow of fuel to the burner through said excess fuel supply pipe simultaneously with the supply of fuelto the burner through said mst-mentioned fuelv supply pipe.

I 2. A burner control apparatus comprising, in combination, a burner, a fuel supply pipe for supplying fuel to said burner, an excess fuel supply pipe for supplying excess fuel to the burner upon ignition and shut-down thereof, a main shutoff valve member for shutting off the supply of fuel to the burner, and a second valve member connected to said first valve member for controlling tne excess fuel supply to the burner.

3. A burner control apparatus comprising, in combination, a burner, a fuel supply pipe for supplying'fuel to said burner, an excess fuel supply pipe for supplying excess fuel to the burner upon ignition and shut-down thereof, a main shutoff valve member for shutting off the supply of fuel to the burner, and a secon-d valve member connected to said first valve member for controlling the excess fuel supply to the burner, said second valve member being open when said rst valve member is closed, and closed when said first valve member is completely open.

4.a. A burner control .apparatus comprising, a burner, a valve having a pair of outlets for supplying fuel to said burner and an inlet, a fuel supply pipe leading to said inlet, shutoff valve means for shutting off the supply of fuel to both said outlets, and a valve member for shui oil through the outlet ber for supplying tinuous burner operation,

l body and said hood and positioned between end of said main I pressure chamber,

er through the outlet not shut off by said valve member when said shutoff valve means is open.

5. A burner' control apparatus comprising a burner, a valve having a pair of outlets for supplying fuel to said burner 'and an inlet, a fuel supply pipe leading to said inlet, shutoff valve means for shutting off the supply of fuel to both said outlets, a valve member for shutting off the supply of fuel to one of said outlets without shutting off the supply of fuel to the other outlet so as to permit the supply of fuel to the burner through the outletnot shut off by said valve member when said shutoff valve means is open. and condition responsive means controlling both of said valve members.

6. A burner control apparatus comprising, a burner, a valve havinfxa pair of outlets for supplying fuel to said burner and an inletl, a fuel supply pipe leading to said inlf. t, shutoff valve means for shutting off the supply of fuel to both 'said outlets, a valve member for shutting off the sbutsupply'of fuel to one of said outlets without ting oil? the supply of fuel to the other outlet so as to permit the supply of fuel to the burner not shut off by said valve member when said shutoff valve means is open. and a safety shutoff and additional condition responsive means controlling said valve means.

7. A burner control apparatus comprising a burner, `a valve body having a main outlet chamber forsupplying fuel to said burner for continuous burner operation, said valve body having a second chamber for supplying excess fuel to the burner upon ignition and shut-down thereof and an inlet chamber, a fuel supply pipe leading to said inlet chamber, a hood for said valve body, a flexible diaphragm clamped between said valve body and said hood and positioned between said excess fuel outlet chamber and a head pressure chamber on the other side of said diaphragm, said diaphragm having a bleed port opening from said head pressure4 chamber into said excess fuel outlet chamber, a pair of'valve seats, one at each end of. said main outlet chamber', a pair of connected valve members one cooperable with each of said valve 'seats and connected to said diaphragm. and means for supplying fuel from said fuel supply pipe anterior of said valve to said head pressure chamber.

8. A burner control apparatus comprising, a burner, a valve body having a main outlet cha-mfuel to said burner for consaid valve body having a second chamber. for supplying excess fuel to the burner upon ignition and shut-down thereof 4and an inlet chamber, a fuel supply pipe leading to said inlet chamber, ahood for said valve body, a flexible diaphragm clamped between said valve said excess fuel outlet chamber and a head pressure chamber on the other side of Vsaid diaphragm, said diaphragm having a bleed port opening from said head pressure chamber into said excess fuel outlet chamber. a pair of valve seats, one at each outlet chamber, a pair of connected valve members one cooperable with each of. said valve seatsV and connected to I'said diaphragm, a pipe for supplying fuel from said fuel supply pipe anterior of said-valve to said head a safetyshutofi' valve intermcntioned pipe and having an burner in juxtaposition to the posed in said last outlet for a pilot 'to said inlet chamber, a

main burner, said safety shutoff valve having an electromagnet for maintaining said valve open for the supply of fuel to the pilot burner and to said head pressure chamber, and a thermoelectric generator positioned to be heated by the :pilot burner and connectedrin circuit with said electromaget.

9. A burner control apparatus comprising, a burner, a valve body having-eJ main outlet chamber for supplying fuel to said burner for continuous burner operation, said valve body having a second chamber for supplying excess fuel to the burner upon ignition and shut-down thereof and an inlet chamber, a fuel supply pipe leading hood for said valve body. a flexible diaphragm clamped between said valve body and said hood and positioned between said excess futl outlet chamber and a head pressure chamber on the yother side of said diaphragm.' said diaphragm having a bleed port openingl from said head vpressure chamber into said excess' fuel o utlet chamber, a pair of valve seats, one at'each end of said main outlet of connected valve members one cooperable lwith each of said valve seats and connected to said diaphragm, a pipe for supplying fuel from said fuel supply pipe anterior of said valve to said- .head pressure chamber, a safety shutoff valve interposed in said last mentioned pipe and having an outlet for a pilot burner in juxtaposition to the main burner, said safety shutoff valve having an electromagnet for maintaining said valve'open for the supply of fuel to the pilot burner and to said head' pressure chamber, a thermoelectric generator positioned to be heated by the pilot burner and connected in circuit with said electromagnet, a solenoid valve interposed in the pipe for .supplying fuel from said safety shutoff valve to said head pressure chamber, a,

condition responsive circuit for said solenoid valve, a thermostat in said switch in said circuit.

l0. The method of burnervcontrol which coinprises delivering to the burner a supply of fuelair mixture with ture proportioned' to give satisfactory results during continuous burner operation, and automatically delivering an additional supply of fuel to enrich the fuel-air mixtureupon' ignition and shut-down of the burner prior `to extinguishment thereof to assure proper ignition and shutdown of the burner with the Aair supply remaining substantially the same as for continuous burner operation.

11. The method of burner control which com' prises delivering to the burner a supply of fuelair mixture with the fuel and air of said mixture proportioned to give satisfactory results during continuous burner operation and automatically delivering an additional suonlv of fuel to enrich the fuel-air mixture upon shut-down of the burner prior to extinguishmentthereof to' assure proper ,shut-down lof 'the burner with the air supply remaining substantially continuous burner operation.

the ,same as for 12. A burner control apparatus comprising. in

combination, a burner, valve controlled means for supplying a fuel-air mixture to said burner with tl'icfuel` and air of said mixture proportioned to give satisfactory results duringr continuous burner operation, and supplementarymeans for automatically delivering an additional supply of fuel to enrich the fuel-air mixture upon ignition and shut-down of the burner prior to extinguishment thereof to assure proper ignition and shutchamber, a pair circuit, and a limit g the fuel and air of such mixdown of the burner with the air supply remaining substantially the same as for continuous burner operation.

13. A burner control apparatus comprising, in

A combination, a burner, valve controlled means for supplying a fuel-air mixture to said burner with the fuel and air of-said mixture proportioned to give satisfactory results during continuous burner operation, and automatic means for delivering an additional supply of fuel to enrich the fuel-air mixture upon shut-down of the burner prior to extinguishment thereof to assure proper shut-down of the burner with the air supply remaining substantially the same as for continuous burner operation.

14. A burner control apparatus comprising, in combination, a burner, means for supplying a fuel-air mixture to said burner with the fuel and air of said mixture proportioned to give satisfactory results during continuous burner operation, means for delivering an additional supply of fuel to enrich the fuel-air mixture upon ignition and shut-down of themburner to assure proper ignition and shut-down of the burner with the air supply remaining substantially the same as for continuous burner operation, and means responsive to variations in temperature controlling the means for delivering the additional supply of fuel.

l5. A burner control apparatus, comprising, in combination, a main burner, means for supplying a fuel-air mixture to the burner with the fuel and air of said mixture proportioned to giver' satisfactory results duringv continuous burner operation, a pilot burner in juxtaposition to the main burner, safety shutoff` means responsive to the pilot burner for shutting off the main burner and the pilot burner upon extinguishment of the pilot burner, temperature responsive means operative in conjunction with said safety shutoff means for shutting olf only the main burner, and means constituting a part of said safety shutoff means for delivering an additional supply of fuel to enrich the fuel-air mixture upon ignition and shut-down of the burner to assure proper ignition and shut-down of' the burner with the air supply remaining substantially the same as for continuous burner operation.

16. A burner control apparatus comprising, in combination, a burner, a fuel supply pipe for supplying fuel to said burner, a second fuel supply pipe for supplying additional fuel to said burner, and a valve member' controlling said second fuel supply pipe, said valve member having a closed position shutting o the supply of fuel through said second fuel supply pipe and an open position to supply an additional supply .of fuel to the burner through said second fuel supply pipe, and means for closing and maintaining closed said valve member upon continuous operation of the burner and for opening said valve member upon shut-down of the burner, said valve member preventing an operation of the burner other than continuous burner operation' without an additional supply of fuel to the burner 'through said iirst fuel supply pipe.

17. A burner control apparatus comprising, in combination, a burner. a fuel supply pipe for supplying fuel to said burner, a second fuel supply pipe for supplying additional fuel to said burner, a valve member controlling said second fuel supply pipe, said valve member having a closed position shutting oi the supply of fuel through said second fuel supply pipe and an open position to supply an additional supply of fuel to the burner through said second fuel supply pipe, means for delivering a supply of air which is substantially constant both during continuous burner operation and when said valve member is open to supply additional fuel for the burner through said second fuel supply pipe, and means for closing and maintaining closed said valve member upon continuous operation of the burner and for opening said valve member upon shut-down of the burner.

18. The method of burner controLwnich comprises delivering to the burner fuel under positive pressure, mixing the fuel with a substantlally constant amount of air to produce a fuelair mixture for the burner with the fuel and the air proportioned to give satisfactory results during continuous burner operation, and delivering to the burner responsive to variation in the fuel pressure incident to shutting-down of the burner an additional amount of fuel to assure proper shut-down of the burner with the air supply remaining substantially the same as for continuousJ burner operation.

19. The method of burner control, which comprises delivering to the burner fuel yunder positive pressure, mixing the fuel with a substantially constant amountof air to produce a fuelair mixture for the burner with the fuel and the air proportioned to give satisfactory results during continuous burner operation, and delivering -of the burner, and means controlling said last means, said controlling means having a position shutting oil' the additional supply oi fuel and a position in which an additional supply of fuel ows to the'burner, said controlling means preventing starting and shut-down of the burner Without an additional oW of fuel to the burner simultaneously withy the supply of fuel for continuous burner operation through said fuel supply pipe.

RICHARD K. ENGHOLDT.

assure proper ignition and shut-down of theV

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