US2823741A - Multiple burner control - Google Patents

Description

Feb. 18, 195s J. H. THORNBE RY 2,823,741

MULTIPLE BURNER CONTROL 2 Sheets-Sheet 1 Filed Marfih 26. 1953 M $0 W r m J n /M Feb, 18 1958 .v. H. THQRNBERY 2,823fi4l MULTIPLE BURNER CONTROL 2 Sheets-Sheet 2 Filed. March 26., 1953 [Ana-w, daily 1042440 United States Patent MULTIPLE BURNER CONTROL John H. Thornbery, Whitefish Bay, Wi's., assigno'r'to 'Baso Inc., Milwaukee, Wis., a corporation of Wisconsin Application Mal-ch26, 1953, Serial N 0. 344,758

20 Claims. (Cl. 158- 123) This invention relates to improvements in multiple burner control systems.

'It is a general object of the present invention to provide an improved multiple burner control system wherein a plurality of main burners are supplied from a single main fuel supply line through a thermoelectrically operated fuel control valve, there being a pilot burner for each main burner and thermoelectrically operated means responsive to extinguishment of one of the pilot burners for providing one hundred percent shut-oft of the flow of fuel to all of the burners.

Another object of the invention is to provide an improved multiple burner control system provided with a thermoelectrically operated fuel shut-off valve for each pilot burner and a thermoelectric generator at each pilot burner, the shut-off valve for each pilot burner being powered by the thermoelectric generatorat another pilo't burner, and the main burnerfuel control valve also being powered by said thermoelectric genera'tors, so that 'extinguishment of one pilot burnercauses sequential shutoff of all pilot burner valves as well as closure of "the main fuel control valve.

Another object of the invention is to provide an improved control system of the character described in which the main burner fuel control valve is one of thecycling type which opens and closes in response to variations in the flow of thermoelectric current therethrough, there being condition responsive means in circuit with said valve for controlling the flow of'thermoelectric current through said valve and thereby controlling the flow "of fuel to the main burners.

A more specific object of the invention is to provide, in -a control system of 'the character described, a main fuel control valve having a pair of :coils each connected in parallel circuit relationship with a separate thermoelectric generator, as well as with one of the pilot burner fuel shut-off valves, the connections to said pair of coils being such that flow of thermoelectric current there- -through from said generators provides magnetic :fields which complement each other to actuate said main burner tu'el control valve.

Another object of 'theinvention is to provide an improved control system of the character described which is operated solely by thermoelectric power andwhic h is adapted for operation under the control'of either timing and/ or temperature responsive'devices.

With these and other objects in view, the invention consists of the improved multiple burner control system and all of the parts and combinations set forth in the claims and all equivalents thereof.

In the accompanying drawings illustrating two forms of the invention:

Figure 1 is a'fragmentary semi-diagrammatic elevational view of the invention embodiedin a wall type space heater;

Figure .2 is .a schematic diagram of the electrical circuit for the form otthe invention shown inFig'ure 1;

Figure 3 is .a semi-diagrammatic elevational view the invention embodied in a kitchen range; and

Figure 4 is a schematic diagram of the electrical circuit forrthe 'formof the invention shown in Figure 3.

Referring now to Figure 1 of the drawings illustrating one application of the invention, the numeral indicates :a wall type space heater having a casing 11 provided with opposite side walls 12 and 13. The illustrated heater 1-0 is adapted to be mounted within an interior wall of a building so that the casing side walls 12 and 13 are contiguousrwit'h the opposite :sides of said wall. The lower portion of the casing .11 forms a cold air return and combustion chamberl t above which is a heat exchanger 15. The .heat exchanger 15 has passages 16 for hot "gases ofconibustion, said;passages communicating with a'vent 17 at the upper end of the casing 11. Outwardly of .the passages 16, .there are fresh air passages "17' which communicate .at their upper ends with louvered openings '20 and 21. Louvered openings 18 and 19 .provide for the.admission of fresh air .into both the chamber l tandthe lower ends of the passages 17' as shown.

Mainfburners 22 and .23aremounted in the upper .portion of the chamber 14 below the passages 16, said burners being fed through supplylines 24 and 24a. Line.24 :may be provided with a manually operated shut-off valve 3.6. A mainburner fuel control valve-25 is interposed between supply lines 24 and 24a as shown. A. pair of pilot burners 26 and'27 are mounted adjacent the main burners22 and .23, respectively, and mounted in coacting relationship with said pilotburners are thermoelectric generators 28 and 29, respectively, which generators may .take the "form of thermocouples. The pilot "burners .26 and -27 are fed through fuel supply pipes 30 and 31 which connect 'with the main fuel supply line 24 ahead of the control valve 25 as shown.

A pair of manually resettable thermoelectrically actuated shut-off valves 32 and 33 are .located in pilot fuel lines 30 and 31 respectively. Valves 32 and .33 .may

be identical and are preferably of the type shown and described in the copeuding patent-application of Gerald E. Dietz, Serial No. 296,83 1, lfiled July 2, 1952, and assigned 'to the 'assignee of the present application. .A detailed description of the structure and operation of the valves 32 and 33 will not be included herein, reference being 'hadto the.above cited patent for this purpose. Forthe purposes of this application, it willbe sufiicient to state the valves 32 and 33 each .have .a casing ,60 .provided with. afuel inlet connection and a fuel outlet connection, 'between which -is interposed a valve seat 61. A valve member 62 is positioned within each casing and is spring urged into sealing engagement withthe-adjacent valve seat 61. Each valve 62 is carried by an axially-slidably mounted stem .63 which has one end projecting through the casing end wall to permit manual actuation thereof. At their inner ends thesterns 63 are each fixed to an-armature 64. An electromagnet v is mounted within each .valve casing 60 and coacts with the adjacentarmature 64 to'hold open the valve 62 connected to said armature whentsaid electromagnet is energized. The electromagnet 65 of the valve 32 is provided with a coil 34,.and the .valve'33 'is provided with a similar electromagnet coil 35.

A thermostat '37.may.be suitably mounted in the chamber 14 in aposition to sensethe temperature of the cold air entering the chamber through the openings .18 and 19. The thermostat 37 is preferably of the type shown and described in the copendingapplication for patent of AdolphLHilgert, Serial No. 291,047,.filed May3 1, 1952, and assigned to the assignee of the present application, now..Patent No..2,724,0-30. This type of thermostath-as extremelyhigh sensitivity .and very low differential, and

itis well adaptedfor the contro 'l of thermoelectric circuits by reason of the low contact resistance of said thermostat.

Sufiice it to state, for the purposes of this application, that the thermostat 37 has a pair. of coacting electrical contacts 38 and 39 which are mounted within an expansible and contractible bellows 40 having a movable wall 41 and an opposite fixed end wall. A compression spring 42 is interposed between the movable bellows wall 41 and an eccentric cam 43 which is fixedly mounted on a transverse shaft 44. The shaft 44 is rotatably mounted in suitable bearings, such as the bearings 45 and 46, and is provided withhandles 47 and 48 outwardly of the casing walls 12 and 13 respectively.

The thermostat 37 preferably contains a volatile fill which expands and contracts in response to temperature changes and causes corresponding expansion or contraction of the bellows and movement of the bellows wall 41. The contact 39 moves with the wall 41 toward and away from the contact 38, which is fixed to the opposite wall of the bellows. The temperature control point of the thermostat 37 can be readily varied by turning handles 47 and 48 to vary the compressive force exerted on the bellows by the spring 42.

The main burnerfuel control valve 25 is preferably of the type shown and described in the copending application for patent of Gerald E. Dietz and Adolph J. Hilgert, Serial No. 292,488, filed June 9, 1952, and assigned to the. assignee of the present application. This type of valve can be operated on thermoelectric power exclusively, said valve being normally closed, and being movable to open position in response to the flow therethrough of a predetermined thermoelectric current. Thus, the valve 25 can not only provide safety shut-on. on pilot failure, but can also operate under the control of the thermostat 37 to provide highly sensitive temperature responsive main burner control.

The structure of the valve will not be described in detail herein, reference to the application Serial No. 292,488 being had for this purpose. Suflice it to state for the purposes of this application that the valve 25 has a casing 66 provided with a fluid inlet and a fluid outlet connection, there being an annular valve seat 67 at the outlet connection. A valve member 68 normally sealingly engages the valveseat 67 to prevent the flow of fuel to .the, burners 22 and 23, said valve being movable to a retracted open position. The valve member 68 is carried by a pivotally mounted arm 69 which is urged by a spring 70 in a direction to move the valve member 68.toward the seat 67. The arm 69 and spring 70 form a part of an electromagnetic valve operator which also includes an electromagnet 71 having a pair of coils 49 and 50 (see Figure 2). The valve operator also includes an armature (not shown) having a resilient connection with the arm 69, said connection providing an energy storing means, the structure and operation of which is more specifically described in the referred to copending application, Serial No. 292,488.

The coils 49 and 50 preferably surround separate pole pieces of the electromagnet 71 and are interconnected at one end and connected in circuit with the contact 39 of the thermostat. The contact 38 of the thermostat is suitably grounded, as is one side of each of the thermoelectric generators 28 and 29 and one side of each of the pilot fuel shut-off valve coils 34 and 35. The ungrounded side of the generator 28 is connected to the ungrounded side of the coil 35 and to free end of the coil 49, as shown, whereas the ungrounded side of the generator 29 is connected to the ungrounded side of the coil 34 and to the free end of the coil 50.

It is apparent that the coils 35 and 49 are connected in parallel circuit relationship with the generator 28, and that the coils 34 and 50 are in parallel circuit relationship with the generator 29. The connections to the coils 29, magnetic fields are provided which complement each other to cause actuation of the valve 25. It is also apparent that the pilot fuel shut-off valve 32 is under the control of the pilot burner 27, and that the pilot fuel shutoff valve 33 is under the control of the pilot burner 26.

During operation of the improved burner control system the pilot burners 26 and 27 normally burn continuously and heat the thermoelectric generators 28 and 29. Thermoelectric current from the generators 28 and 29 flows through the coils 34, 35 to hold the normally closed pilot burner fuel shutoff valves 32 and 33- in open position. Thermoelectric current from the generators 28 and 29 also flows through the coils 49 and 50 under the control of the thermostat 37, so that the valve 25 is opened and closed in accordance with the temperature of the air entering the chamber 14 through the openings 18 and 19 so long as the pilot burners 26 and 27 are functioning properly.

The thermostat 37 may function as a variable resistance device wherein a decrease in contact pressure increases the contact resistance, and when the contact resistance increases to a predetermined point where the thermoelectric current can no longer flow therethrough in sufficient quantity to maintain the electromagnetic operator of valve 25 energized, said operator closes said valve. Conversely, an increase in Contact pressure decreases the contact resistance, and when this resistance decreases to a predetermined point, the thermoelectric current can flow therethrough in sufficient quantity to energize the operator of the valve 25, whereupon said operator opens said valve.

A highly sensitive automatic control of the thermoelectric current in the circuit can be efiectecl in response to changes in temperature by merely varying the contact pressure of the contact 39 against the contact 38. The inherent differential required to open and close the valve 25 is very small, and, neglecting thermal lag of thethermostat 37, is dependent upon the electrical constants of the apparatus as determined by the relationship of the current values which will cause opening and closing of the valve 25 in relation to the contact pressure in the thermostat. This inherent differential is so minimal as to be within the thermal lag range of the thermostat 37. It is apparent, therefore, that the thermostat 37 serves as a very sensitive condition responsive means which cycles the valve 25 in response to predetermined relatively low temperature differentials.

The copending applicationfor patent of Adolph J. Hilgert and Russell B. Matthews, Serial No. 289,242, filed May 22, 1952, and assigned to the assignee of the present application, now Patent No. 2,717,123, showsand describes a thermoelectric control circuit incorporating an encapsulated thermostat and an electromagnetically oper ated valve similar in structure and operation to the thermostat 37 and valve 25. Reference may be had to this copending application for additional specific structural details.

When one of the pilot burners is extinguished, for example, the burner 26, the adjacent generator 28 cools and deenergizes the coil 35 of the shut-off valve 33 for the other pilot burner (burner 27), closing valve 33 and ex tinguishing said other pilot burner. This, of course, causes cooling of the generator 29, which deenergizes the coil 34 of the shut-off valve 32 for the pilot burner 26, closing the latter valve. With both generators in a cooling state, coils 49 and 50 of the valve 25 are both deenergized, and the valve member 68 of valve 25 moves to closed position, if open, to provide one hundred percent shut-off of the fuel. The valve member 68 will remain in closed position until after the pilot burners 26 and 27 are relighted to cause generation of current by the generators 28 and 29.

In Figure 3 the improved burner control system is shown embodied in a range 51 having a broilerburner 22' and an oven burner 23', both supplied with fuel through supply lines 24' and 24a. A three-way valve 52 may be interposed in the line 24', as shown, to provide for selective operation of either or both of the burners 22' and 23. A thermostatically operated valve 53 of any well known type is located in the branch of the line 24a connected to the burner 23 and has a sensing bulb 54 located in the range oven.

A cycling type of thermoelectrically operated shut-off valve 25', which may be identical with the valve 25 of Figure l, is interposed between supply lines 24' and 24a, said valve having an electromagnetic operator provided with two coils 49 and 50' (see Figure 4). Parts of the valve 25' corresponding to parts of the valve 25 in Figure 2 are indicated by the same numerals primed. A pair of pilot burners 26 and 27' are mounted adjacent the main burners 22 and 23 respectively, and a pair of thermoelectric generators 28 and 29' are mounted in coacting relationship with the pilot burners 26' and 27' respectively. The pilot burners 26 and 27' are supplied with fuel through a branched line 55 which communicates with the main fuel supply line 24' ahead of the valve 25' as shown. The main fuel supply line 24 may also be provided with a manual shut-off valve 36.

The flow of fuel to the pilot burner 26' is controlled, by a thermoelectrically operated shut-off valve 32' which may be identical with the valves 32 and 33 and has a coil 34' corresponding to the coil 34 of valve 32. The fiow of fuel to the pilot burner 27' is controlled by a thermoelectrically operated shut-off valve 33 which may be identical with valves 32, 32' and 33 and has a coil 35 corresponding to the coil 35 of valve 33. As shown in Figure 4, the coil 35 is connected in parallel circuit relationship with the generator 28', and the coil 34 is similarly connected to the generator 29. The coils 49 and 50 are interconnected at one end, and the interconnected ends are also connected in circuit with one side of a manual switch 56, as well as with one side of a switch 57 which is actuated by an oven clock control 58. The other side of each switch 56 and 57 is grounded.

One side of each of the generators 28' and 29' and of coils 34 and 35' is grounded, the ungrounded side of the generator 28 and of the coil 35' being connected in circuit with the free end of the coil 49. The ungrounded side of the generator 29 and of the coil 34 is connected to the free end of the coil 50. The connection to the coils 49 and 50' are such that the flow of current therethrough-from the generators 28' and 29' provides magnetic fields which complement each other to actuate the valve 25'.

The pilot burners 26 and 27' normally burn continuously and heat the generators 28 and 29 to cause current to flow therefrom through the coils 34' and 35. This holds open the normally closed pilot burner shut-off valves 32 and 33. Upon closure of either of the switches 56 and 57, the current from the generators flows through the coils 49 and 50' to thereby move the valve member 68' of the valve 25 to open position. With the valve 52 positioned as shown, fuel flows to the main burners 22' and 23, the flow to the latter being under the control of the thermostatic valve 53.

When one of the pilot burners, for example, the burner 26, becomes extinguished, the adjacent generator 28' cools and deenergizes the coil 35' of the shut-off valve 33' for the pilot burner 27 closing said valve extinguishing the latter burner. This cools the generator 29 and deenergizes the coil 34' of the pilot burner shut-off valve 32', closing said valve. With both generators 28 and 29' in a cooling state, the coils 49 and 50' of the valve 25' are deenergized and the valve member 68 of said valve closes, if open, to provide one hundred percent shut-off of the fuel. The valve member 68' remains closed until after the pilot burners 26 and 27 are relighted to cause generation of current by the generators 28' and 29'.

It is apparent that whenever both of the switches 56 and 57 are open, the flow of current through the coils 49 and 59 is interrupted, and the valve 25 is therefore closed. The clock control 58 may be set to close the switch 57 at any predetermined time, thereby opening the valve 25 and placing the selected main burner in operation at the selected hour. The clock control 58 may also be set to close the valve 57 after a predetermined period of burner operation. When it is desired to operate the oven or broiler without the clock control, the manual switch 56 is closed and the range is operated in the conventional manner.

In both of the illustrated forms of the invention a multiple burner control system is provided in which one hundred percent shut-off of fuel flow to the main burners, as well as to the pilot burners is automatically effected in response to extinguishment of one of the pilot burners. The improved system operates entirely on thermoelectric power generated within the system.

The illustrated embodiments of the invention are for the purpose of disclosure only, and are not to be construed as in any way defining the limits or scope of the invention. Various other changes and modifications may be made Without departing from the spirit of the invention, and all of such changes are contemplated as may come within the scope of the appended claims.

What I claim as the invention is:

1. Apparatus for controlling the flow of fuel in a fluid fuel burning unit, comprising: a plurality of ignition burners; an electromagnetically operated fuel shut-off valve for each of said burners; a separate thermoelectric generator at each of said burners, each of said generators being connected to and powering the fuel shut-off valve of one of said burners other than the one associated with the respective generator, whereby extinguishment of one of said burners causes sequential closure of the fuel shutoff valves of all of said burners.

2. In apparatus for controlling the flow of fuel in a fluid fuel burning unit; a pair of pilot burners; a thermoelectric generator at each pilot burner; an electromagnetically operated shut-off valve for each pilot burner, said valves each having a coil connected in circuit with the generator at the other pilot burner; and an electromagnetically operated main burner fuel shut-off valve having a pair of coils each connected in parallel circuit relationship with a separate one of said generators, the connections to said pair of coils being such that the flow of a predetermined thermoelectric current from said generators through said coils provides magnetic fields which complement each other and cause actuation of said main burner fuel shut-off valve.

3. In apparatus for controlling the flow of fuel in a fluid fuel burning unit: a pair of pilot burners; a thermoelectric generator at each pilot burner; an electromagnetically operated shut-off valve for each pilot burner, said valves each having a coil connected in circuit with the generator at the other pilot burner; an electromagnetically operated main burner fuel shut-off valve having a pair of coils each connected in parallel circuit relationship with a separate one of said generators, the connections to said pair of coils being such that the flow 'of a predetermined thermoelectric current from said generators through said coils provides magnetic fields which complement each other and cause actuation of said main burner fuel shut-off valve; and a condition responsive circuit controlling device in circuit with said pair of coils and controlling the flow of current thereto from said generators.

4. In apparatus for controlling the flow of fuel in a fluid fuel burning unit: a pair of pilot burners; a thermoelectric generator at each pilot burner; an. electromag netically operated shut-off valve for each pilot burner, said valves each having a coil connected in. circuit with ene a r "a t e: other p o burn r; an, e e trqmagr" neticall'y operated main burner fuel shut-off valve havingburner fuel shut-off valve; and a switch in circuit with said: pair of coils controlling the flow of thermoelectric current thereto from said" generators.

5. In apparatus. for controlling the flow of fuel in a fluid fuel burningunit: a pair of pilot burners; a thermoelectric generator at each-pilot burner; an electromagnetically' operated, shut-off valve for each pilot burner, said valves each having a, coil connected in circuit with the generator atthe other pilot burner; an electromagnetically operated, main burner fuel shut-off valve having a pair of; coils, each connected in parallel circuit relationship, with a separate one of said gene rators,.the connections to said pair of coils being such that, the flow of a predetermined; thermoelectric current from said generators through said, coils provides magnetic fields which complementeach other and cause actuation of said main burner fuel shut-off valve; and a temperature responsive variable resistance device in circuit with said pair of coils controllingthe flow of thermoelectric current thereto from said. generators, said device comprising coacting electrical contacts encapsulated within an expansible and contractible bellows.

.6. In apparatus for controlling the flow of fuel in a fluidfuel burning unit: a pair of pilot burners; a thermoelectric generator at each pilot burner, each generator having; one, side, grounded; an electromagnetically operated shut-ofinvalve for eachpilot burner, said valves each havinga coil-with one, side connected to the ungrounded side ofthe generator; at the other pilot burner, the other side of. said; coils being grounded; and an electromagnetically operated main burner fuel shut-off valve having a pair of coilswhich are interconnected at one end and grounded, said coils having their other ends respectively connected to the ungrounded. sides of said generators, the connections to said pair of coils being such that the flow of a predetermined thermoelectric current from the generators through said coils provides magnetic fields which complement each, other and cause actuation of the main burner, fuel shut-off valve.

7; In, apparatus for controlling the flow of fuel in a fluid fuel burning unit: a pair of pilot burners; a thermoelectric generator. at each pilot burner, each generator haying one-side grounded; an electromagnetically operated shut-off valve for each pilot burner, said valves each having a coil with one side connected to the ungrounded side of the generator at the other pilot burner, the other side of-gsaidicoils being, grounded; an electromagnetically operated mainburner fuel shut-off valve-having a pairof coils whichv areinterconnected at one end and grounded, said coils; havingtheir other ends respectively connected to theungrounded: sides. of said generators, the connections to.said:pair'of coilsbeing suchthat the flow of a predeterminedtthermoelectric current from the generators through said;coils providesimagnetic fields which complement each other and, cause actuation of the main burner fuel shutoff valve; and, a condition responsive circuit controlling device connected in the circuit between the interconnected endsof the pair of'coils and the ground, said device controlling the flow of thermoelectric current to said coils from said: generators.

8; In. apparatus for controlling the flow of fuel in a fluid fuel burning unit: a pair of pilot burners; a thermoelectric. generator at each pilot burner, each generator havingone sidegrounded; an electromagnetically operated shuteoffrvalve for each pilot burner, said valveseach havingz a coilwilth onezside connected: to the ungrounded side of, the generator atthnother pilot, burner, the other side of sa dlcorils heinsz r unded; an ele ncmagne ca lx op rated main burner-fuel shutj ofivalve havipg a pair; of; toilswhich are interconnected at one end and grounded, said coils having: their other ends respectively connected to the ungroundedv sides of said generat0rs,ythe connections to said pair of coils being such that the flow of a predetermined thermoelectric current from. the; generators through said coils provides magnetic fields which complement each other and cause actuation of the main burner fuel shut-off valve; and a switch connected in the circuit between the interconnected ends of the pair of coils and the ground, said switch controlling the flow of thermoelectric current to said coils from said generators.

9. In apparatus for controlling the flow of fuel in a fluid fuel burning unit: a, pair of pilot burners; a thermoelectric generator at each pilot burner, each generator having one side grounded; an electromagnetically. operatedv coilswhich are interconnected at one end and grounded, said coils havingtheir other. ends respectively connected to the ungrounded sides of said generators, the connections to said pair of coils. being such that the flow of a predetermined thermoelectric currentfrom the generators through said coils provides magnetic fields which comple ment each other and cause actuation. of the main burner fuel shut-off valve; and a temperature responsive variable resistance device connected in the circuit between theinterconnected ends of the pair of coils and the gro nd, saiddevice controlling the flow. of thermoelectric current to saidcoilsfrom said generators and comprising coacting electrical contacts encapsulated within an expansible and contractiblebellows.

10. Apparatus for. controlling the flow of fuel in a fluid fuel burning unit, comprising, a plurality of fuel burners having individual fuel supply conduits, an electrically operated fuel shut-off valve in each of; said conduits for. control of'fuel supply to its respective burner, a thermoelectricgenerator for each of said burners to be heated respectively thereby, each of said generators being in circuit with one of said shut-off valves other thanthe one controlling fuel supply to its respective burner, extinguishment of any one of said burners effecting successive closure ofthe valves of all of said burners.

11. Apparatus for controlling the flow of fuel in a fluid fuel burning unit, comprising, a plurality of fuel burners having individual fuel supply conduits, an electrically controlled, fuel shut-off valve in each of said conduits for control of] fuel. supply to its respective burner, thermoelectric generators roman shut-off valves heated by said burners, each of said generators having individual connection with one ofsaid valves other'than the one controlling the' fuel supplyto the burner afford-ing heat for the respective generator whileat least one of said generators hasarr additional connection with another of said valves, and condition responsive means controlling said last-mentioned valve for control of the fuel supplied thereby tQ-i'tS, respective burner in. response to variations in the condition, extinguishment of any one of, said burners other than the burner controlled by said last-mentioned valve effecting closure of all of said valves.

12. Apparatus for controlling the flow of fuel in a fluid fuel burning unit, comprising, at least three fuel burners having individual fuel supply conduits, an electrically controlledfuel shut-off valve in each of said conduits for control offuel supply to its respective burner, and a thermoelectric generator for each of' two of said three burners to beheated respectively thereby, each of said generators having operating connection with the heat for the other generator, at least one of said generators; also having-- operative connection with the valve:-

controlling fuel supply to the carrier tear ng heat-affording relation with either of said generators, extinguishment of either of said burners affording heat for one of said generators effecting closure bfall ofs'aid valves 13. Apparatus for controlling the How of "fuel in a fluid fuel burning unit, comprising, at least three fuel burners having individual fuel supply conduits, an electrically controlled fuel shut-off valve in each of said conduits for control of fuel supply to its respective burner, a thermoelectric generator for each of two of said three burners to be heated respectively thereby, each of said generators having operative connection with the valve controlling fuel supply to the burner affording heat for the other generator, at least one of said generators also having operative connection with the valve controlling fuel supply to the burner lacking heat-affording relation with said generators, and condition responsive means controlling said last-mentioned valve to control the fuel supplied thereby to its respective burner in response to variations in the condition, extinguishment of either of said burners affording heat for said generators effecting closure of all of said valves.

14. Apparatus for controlling the flow of fuel in a fluid fuel burning unit, comprising, at least three fuel burners having individual fuel supply conduits, an electrically controlled fuel shut-off valve in each of said conduits for control of fuel supply to its respective burner, a thermoelectric generator for each of two of said three burners to be heated respectively thereby, each of said generators having operative connection with the valve controlling fuel supply to the 'burner affording heat for the other generator, at least one of said generators also having operative connection with the valve controlling fuel supply to the burner lacking heat-affording relation with said generators, and temperature responsive means having connection with said last-mentioned valve to thermostatically control the fuel supplied thereby to its respective burner, extinguishment of either of said burners affording heat for said generators effecting closure of all of said valves.

15. Apparatus for controlling the flow of fuel in a fluid fuel burning unit, comprising, a plurality of fuel burners having individual fuel supply conduits, an electrically operated fuel shut-off valve in each of said conduits for control of fuel supply to its respective burner, a thermoelectric generator for each of said burners to be heated respectively thereby, each of said generators being in circuit with one of said shut-off valves other than the one controlling fuel supply to its respective burner, extinguishment of any one of said burners effecting successive closure of the valves of all of said burners, and at least one additional burner having an electrically operative cycling valve for control of fuel supplied thereto, said cycling valve being in circuit with at least one of said generators, whereby said cycling valve shuts off supply of fuel to said additional "burner upon extinguishment of any of said first-mentioned burners.

16. Apparatus for controlling the flow of fuel in a fluid fuel burning unit, comprising, a main fuel burner and main fuel supply line therefor, an electrically perated main shut-off valve in said fuel supply line, a plurality of pilot burners having individual fuel supply conduits having connection with said main fuel supply line upstream of said main valve, an electrically operated auxiliary fuel shut-off valve in each of said conduits for control of fuel supply to its respective pilot burner, a thermoelectric generator for each of said pilot burners to be heated respectively thereby, each of said generators being in circuit with one of said auxiliary shut-off valves other than the one controlling fuel supply to its respective pilot burner, and with said main shut-off valve, whereby extinguishment of any one of said pilot burners effects successive closure of the auxiliary valves of all of said pilot burners and closure of said main shut-off valve.

17. Apparatus for controlling the flow of fuel in 9.

, 10 "'flui'd fuel burning "unit, comprising, at least one rimai'n burner and main fuel supply line therefore, an electrically operated "main shut-off valve in said main supply line, said main shut-off valve having "a new control member and condition responsive means associated therewith for controlling said flow control member in response to a given condition, a plurality of pilot burners having individual rust supply conduits independent of said rriain valve, an electrically operated auxiliary-fuel shut-off 'v'alv e in each of said conduits for control of fuel supply to its respective pilot burner, a thermoelectric generator for each of said pilot burners to be heated respectively thereby, each of said generators being in circuit with one of said auxiliary shut-off valves other than the one controlling fuel supply to its respective pilot burner and with said main shutoff valve, whereby extinguishment of any one of said pilot burners effects successive closure of the auxiliary valves of all of said pilot burners, and renders said condition responsive means ineffective to control said main valve.

18. Apparatus for controlling the flow of fuel in a fluid fuel burning unit, comprising, a plurality of main burners, a main fuel supply line and electrically operated main shut-off valve therein for supply of fuel to said main burners, thermostat means comprising a pair of cooperating electric contacts positioned within an expansible and contractible enclosure in circuit with said main shut-off valve to render said valve responsive to predetermined temperature variations, a pilot burner for each of said main burners in heating relation respectively therewith, said pilot burners having individual fuel supply conduits independent of said main supply line, an electrically operated auxiliary fuel shut-off valve in each of said conduits for control of fuel supply to its respective pilot burner, a thermoelectric generator for each of said pilot burners to be heated respectively thereby, each of said generators being in circuit with one of said auxiliary shut-off valves other than the one controlling fuel supply to its respective pilot burner, at least one of said generators also having electrical connection with said main shut-off valve whereby extinguishment of any one of said pilot burners effects successive closure of the auxiliary valves of all of said pilot burners and closure of said main valve to thereby provide one hundred. percent shutoff.

19. Apparatus for controlling the flow of fuel in a fluid fuel burning unit comprising, a plurality of main burners, a main fuel supply line and electrically operated main shut-off valve therein for supply of fuel to said main burners, a pilot burner for each of said main burners in heating relation respectively therewith, said pilot burners having individual fuel supply conduits independent of said main supply line, an electrically operated auxiliary fuel shut-off valve in each of said conduits for control of fuel supply to its respective pilot burner, a thermoelectric generator for each of said pilot burners to be heated respectively thereby, each of said generators being in circuit with one of said auxiliary shut-off valves other than the one controlling fuel supply to its respective pilot burner, said main shut-off valve having a coil and at least one of said generators being also in circuit with said coil of said main shut-off valve, a switch also in circuit with said coil controlling the flow of thermoelectric current therethrough from said one of said generators, and thermostatic means controlling flow of fuel to at least one of said main burners, extiuguishment of any one of said pilot burners effecting successive closure of the auxiliary valves of all of said pilot burners and closure of said main valve to thereby provide one hundred percent shut-oif, interruption of flow of fuel to said main burners being effected also by opening of the circuit to the coil of said main valve at said switch and by operation of said thermostatic means even though fuel is being supplied to said pilot burners and said generators are heated.

20. Apparatus for controlling the flow of fuel in a fluid fuel burning unit, comprising: a plurality of ignition burners, an electromagnetically operated fuel shut-off valve operatively associated with each burner, 21 separate thermoelectric generator at each of said burners, each of said generators being connected to and powering the fuel shut-off valve directly controlling another burner whereby extinguishment of one of said burners causes sequential closureof the fuel shut-off valves of all the said burners.

References Cited in the file of this patent UNITED STATES PATENTS

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