US1546640A - Electrical control mechanism for oil and other fuel-burning equipment - Google Patents

Description

July 21, 1925. 1,546,640

. F. FISCHER ET AL ELECTRICAL CONTROL MECHANISM FOR OIL AND OTHER FUEL'BURNING EQUIPMENT Filed April 11, 1925 3 Sheets-Sheet 1 Fig.1

W TNESSE INVENTORS July 21,1925.

F. FISCHER ET AL ELECTRICAL CONTROL MECHANISM FOR OIL AND OTHER FUEL BURNING EQUIPMENT 3 Sheets-Sheet 2 Filed April 11, 1925 Fig. II

W- INVENTORIS Wffi flat July 21; 1925.

F. FISCHER ET AL ELECTRICAL CONTROL MECHANISM FOR OIL AND OTHER FUEL BURNING EQUIPMENT Filed April 11 1925 s Sheets-She et s PatentedJuly 21, 1925. T

1 UNITED STATES PATENT; OFFICE.

FRANK FISCHER, F LARCHMONT, NEW YORK, AND ARNOLD F. VAN FELT, OF INTER- I LAKEN, NEW JERSEY.

ELECTRICAL, oonprnor. MECHANISM T 0 all whom it may concern.

' Be it known that we, FRANK FISCHER and ARNOLD F. VAN PELT, citizens of the United States, residing at Larchmont, in the county of WVestchester and State of New .York, and at Interlaken, inthe county of Monmouthand State, of New Jersey, respectively, have invented certain new and useful Improvements in Electrical Control Mech nection with burners for domestic use, hecause the control is fully electrical and does not depend upon unreliable drip-pans or similar mechanisms to shut down the e uipment in case of failure to ignite; an because it does not requireexpert attendance. The general object of this invention is to provide a fully automatic control which is safe, economical, and infallible for governing oil or similar fuel burning equipment. One specific object is to automatically start the fuel-supply motor and the ignition system of the burner when the circuit is closed by any means such as a manually operated switch or a thermostat, boiler control, or similar device. The operation of these devices is well known and is controlled by the temperature of the place to be heated, or by the temperature. or pressure of the boiler or furnace. v

Another object is to automatically stop the fuel-supply motor and the ignition system of the burner whenthecircuit is opened by any means such as a manually, operated switch, 'or a thermostat, boiler-control or similar device. P I 0 Another object is to shut off the ignition system in a predetermined. time after the burner is lighted.

FOB OIL AND OTHER FUEL-BURNING Ecum- MENT.

Application filed April 11,1925. Serial No. 22,499.

system again automatically if the burner should go out for any reason whatsoever, other than the complete shutdown of the burner.

Another object is to shut down the fuelsupply motor and the ignition system automatically in a predetermined time if the oil or other fuel has failed to ignite. In order to prevent the depositing of an excessive amount of unburned fuel in the combustion chamber, the predetermined time of shut down may be set from 30 seconds to 10 minutes-as desired. I

Another object isto shut down the fuelsu'pply motor and ignition system automatically upon the failure of any one of the elements in the control circuit in a predeter- 'mined time (as above noted).

Another object is to shut down the burner and ignition system automatically if the fuel supply should fail.

Another object is to prevent the 'burner from auton'iatically starting after 'it has shut itself down because of failure to obtain ignition, or failure of any of the elements in the circuit, or failure of the fuel supply as aforesaid,-said shut-down to be maintained until the equipment is inspected and the control manually reset.

Other objects will hereafter appean.

The nature and scope of this invention are more fully explained in the following description taken in connection with the accompanying drawings forming part of this specification, in which:

Fig. I is a diagram of our control mech anism adapted to alternating current, and

having a low voltage thermostat and boilercont-rol properly connected to our circuit.

Fig. II is a diagram of our control mecha nism for operating on direct or alternating current without the low voltage element of the -circuit. The thermostat and boiler-control shown are designed for operation on the normal lighting or power circuit.

Fig. III shows an oil-burning furnace equipped with our control mechanism.

Similar numerals refer to similar parts \throu hout the several figures.

60. Another object -is -t0 start the ignition In ig."I, 1 and 2 are alternatingcurrent 2 being preferably the grounded side of the line, if the line is grounded.

3 and 4 are terminals of electric motor 5.

which drives the pump or other apparatus supplying fuel to the burner. 6 is a solenoid with terminals 7 and 8, and movable core 9, although a rotary form of motor could readily be substituted here for performing the ndechanical work of operating a valve, switch, or other ignition apparatus. 6 will therefore be referred to hereafter as the ignition-motor,

10 is a gas valve operated by ignitionmotor 6. v

11 to 21 inclusive comprise a time-limit cut-out. A time-limit cut-out permits an electric current of .a given strength to fiow through it for only a limited period of time.

In this particular time-limit cut-out, 11 is a resistance wire or heating coil; 12 is a piece of thermostatic. metal with oneend fastened rigidly at 13 and the other end bearing against brass member '14 which is pivoted at 15.

,Thermostatic metal 12 is superimposed above the resistance wire or heating-coil 11 and bends upward when heated, as indicated by dotted lines 12. Member 14 is connected through flexible lead 16 to coil 11, and carries contactor 17 which is held against contactor '18 by the end of thermostatic metal 12. 19 is a compression spring bearing against brass member 14 at one end andagainst fixed piece 20 at the other. Compression spring 19 provides a quick break between contactors 17 and 18 when thermostatic metal 12 has been heated by coil 11, and has moved above the end of member 14 as indicated by broken lines 12.

21 is a. re-setting member which passes through a hole in fixed piece 20, through compression spring 19, and fastens to member 14. Its purpose is to enable member 14 with its contactor 17, to be pulled over against contactor 18 so as to allow thermostatic metal 12 to spring downward and reset against member 14 when thermostatic metail 12 has cooled sufiiciently.

22 to 37 inclusive are parts of a commercial relay, a thermostat, and a transformer, all interconnected for the'purpo'se of automatically closing and opening the power circuit, at predetermined temperatures or pressures. 22 is the rela armature, carrying an insulated hook for lifting relay arms 23 and 24.

25 and 26 are contactors on the relay in the main power circuit. 27 and 28 are low voltage contactors. 29 is an electro-magnet. 30 is a resistance coil. 31,32 and 33 are contactor points on a low voltage thermostat. 34 and 35 are the terminals of the secondary winding of a transformer; 36 and 31 are terminals of primary winding of the said transformer. 38 and 39 are terminals of a switch or similar device usually connected mechanically or electricall in some suitable manner to the boiler Or furnace or apparatus which contains the burner.

40 is a fuse which is connected in series with a shunt box which is indicated by numerals 41 to 46 inclusive, both of which are shunted around the ignition-motor 6 and heating coil 11.

The shunt-box, which constitutes part of our invention, acts as a monitor over the time-limit relay, preventing it from functioning or permitting it to function according to whether the burner is ignited or not ignited, respectively. This shunt-box consists of a fixed insulated member 41 through which is passed adjusting screw 42 carrying contactor 43. 44 is a contactor fastened to thermostatic metal 45 which in turn is fastened rigidly to fixed insulated member 46..

The shunt-box is conveniently placed in the stack of the furnace, but it can be put in vmany places near the furnace or boiler and.

still be effective. Other materials which expand or become otherwise distorted by heat, may be substituted in the place of the thermostatic metal members 12 and 45, although certain commercial metals are usually considered most practical for this purpose.

Hereafter, 6 to 9 will be referred to as an ignition-motor; 11 to 21 will be referred to as atime-limit cut-out; 22 to 29 will be referred to as a relay; 31 to 33 will be referred to as a thermostat; 34 to 37 will be referred to as transformer; 38 to 39 will be referred to as a boiler-control; and 41 to 46 will be referred to as a shunt-box.

The descriptive name time-limit cut-out explains the function of this cut-out apparatus; which function is to open an electric circuit passing through it, and thereby cut out any other apparatus connected in series with it, after the lapse of a certain predetermined time constituting the time-limit factor. The operation of the time-limit cutout is hereinafter more fully described.

Fig. II contains no additional parts over Fig, I, but on the other hand shows our control circuit without the relay and lowvoltage circuit previously described.

Fig. III shows a convenient arrangement of the devices enumerated in which:

The solenoid ignition-motor, gas valve, time-limit cut-out, relay, transformer, boilercontrol switch, and fuse may be considered as located on a suitable panel-board all enclosed in a metal case or panel-box. These parts are enlarged in the drawing to enable the circuit to be traced more readily.

Thefuel-supply motor 5 and pump 47 are placed convenlently .'with relation to the boiler or furnace 48.

The shunt-box is most conveniently placed in the stack 49 of the furnace 48. The

'of the boiler if preferred.

57 may be actuated thermostat isplaced'in the particular room or place the temperature of which is to be controlled.

Oil supply tank is connected by means of pipe 51 with the pump 47 which entrains. oil from tank 50 and air through port 52; and after mixing them in the proper. proportions, discharges them through burner supply pipe 53 and nozzle 54 into the firebox of the furnace.

Gas pilot flame 55 is fed through gas pipe 56 and gas valve 10, the latter being controlled b solenoid ignition-motor 6.

In Fig. I I the boiler-control is shown as a diaphragm piston 57 connected, through Weighted lever 58 and chain or cable 59 passing over pulleys 60 and 61, with switch 62; although the whole boiler-control apparatus may be installed as aunit on the top The diaphragm piston by the pressure of steam in the boiler, or by the pressure of any trapped fluid which expands when heated. In the latter case the boiler-control may be considered as operated by the temperature, rather than the pressure of the boiler.

The operation of our oil-burner control mechanism is as follows:

The power current is always presumed to be on lines 1 and 2.

Assuming vthat the temperature or pressure of the boiler or furnace is below a predetermined point, above which it is to be 'maintained,'the lower temperature contacts 31 and 32 of the thermostat and boiler-control leads 38 and 39 will be closed. The transformer, usually of the type to trans form the normal 110 volt lighting current to 1 a lower voltage, usually 24 volts, is energized, and is therefore in a position to sup- I ply current to the relay. At the predetermined temperature, the thermostatic member 31 of the thermostat makes contact with 32 which energizes the magnet 29 which in turn pulls up the armature 22 and the adjacent contactor arms 23 and 24 which in turn close contactors 25 to 26 and 27to 28. The closing'of contactors 27 and '28 magnet ically locks the armature 22 in place and the closing of. the main line contactors 25 and 26 completesthe circuit for the current to travel from the supply line 2, through the fuel-supply motor 5, through the solenoid 6,

through the time-limit cut-out, through the maincontactors 25' and 26 of the relay, and back'to line 1.

This forms a series circuit inwhich'the breaking of any of the lines orv connections in theicir'cuit would cause the entire circuit to become open and therefore inoperative.

The instant the relay picks up, the motor 5 starts, whichnin'turnstarts the pump and sprays oil into the furnace; thexsolenoid 6 is energized, which forces plunger 9 upward is thereby ignited.

started in operation by the thereby opening the gas valve 10 (or any other similar device) and the'heating coil 11 of the time-limit cut-out begins to heat up. If nothing further takes place, the heatgenerated in the coil 11 of the time-limit cut-out will cause thermostatic metal 12 to bend upward and pass the end of member 14. This in turn will allow compressionspring 19 to force member 14 out of its position and break contactors 17 and 18 which open the circuit and thereby de-energize the" solenoid 6 and the motor 5. The plunger 9- falls to its normal position thereby closing the gas valve 10 (or other mechanism) and the fuel-supply motor stops, thereby stopping the fiow of oil into the boiler or.

furnace.

However, when the motor 5 is started and.

thesolenoid 6 opens the gas valve 10, it exands the pilot'light 55, Fig. III which is ein'g fed by this gas valve,

oil which is being sprayed into the furnace At a predetermined time after ignition has taken placethermostatic metal 45 in the shunt-box in the stack 49 starts to move and closes contactors 44 and 43. This has the effect of.shunting out the solenoid 6 and the heating coil 11 in the time-limit cut-out.

Shunting out the solenoid in this manner so that the fuel allows the gas valve 10 to close thereby cone.

tracting the pilot to its normal position.

Shu'nting out the heating coil 11 permits it to cool down and there ore thermostatic member 12 does not move and contactors 17 and 18 are thereby unable to be forced apart by compressing spring 19, and the burner continues to function normally.

If the gas pilot, which is expanded by the solenoid 6 pressing against the gas-valve 10, has'for any reason been blown out, or the electric orother ignition system which is solenoid 6, fails to operate, sprayed into the furnace but not ignited. Under these circumstances the thermostatic metal 45 of the shunt-box would receive no heat, and consequently would not move .to bring contactors 43 and 44 together, so that the current taken. to operate the motor 'wouldcontinue to pass through; the timelimit cut-out (particularly through the heating coil 11) and through the solenoid 6. The heat generated in the resistance wire of heating coil 11 under these circumstances would be suflicient, in a predetermined time, to cause thermostatic member 12 to move upward allowing compression spring 19 to 'act and break the contact at 17 and 18 therebyopen the circuit and shut down all of the apparatus.

If the burner should be functioning nor:- mally hausted, combustion would of course cease. This would allow thermostatic metal 45 in and the oil supply should become exthe shunt box to cool and assume its normal position, opening contactors 43 and 44. This would then permit all of the current which is being taken by the motor to pass through the coil 11 of the time-limit cut-out and through solenoid 6a This would have the effect of heating coil 11, which would in turn cause thermostatic member 12 to move up out of the way of member 14, and in a predetermined time circuit would be open between contactors 17 and 18, and all of the apparatus would shut down.

If it should happen that contactors 43 and 44 should stick together freeze, and the burner then be started up with these contactors closed, the. larger starting current of the motor 5, in attempting to take the path of least resistance, would blow the fuse 40 which is in the shunting circuit, thereby opening the shunt circuit. The coil 11 of the time-limit cut-out would immediately be energized, and inasmuch as the shunt circuit is open, the motor 5 would shut down in a predetermined time as heretofore explained. The precise location and resistance of this fuse in the circuit is of considerable importance in this invention.

It is to be understood that this invention is not limited to the exact form or arrangement of parts shown in the accompanying drawings but that modification therein may be made without departing from the spirit of the invention as defined by claims.

We'are aware that prior to this invention,

relays solenoids and various forms of thermostatic controls have been used commerciall for sundry purposes, and do not claim tiiese individual circuits in detail. What we do claim and desire to secure by Letters Patent is 1. In an electrical control mechanism for burners, the combination of a fuel-supply motor, an ignition motor, and a time-limit cut-out tending to de-energize the motor in a predetermined time, all connected in series in an electric circuit, and means for preventing the cut-out from tie-energizing the fuel-supply motor when the burner is ignited. J

2. In an electrical control mechanism for burners, the combination of a "fuel-supply motor, a heat-coil and a pair of contactors, all connected in series, a yielding means for separating the contactors, and a thermostat metal member inproximity to the heat-coil to hold the contactors together when said member is cool, but to permit the contactors to separate and de-energize the motor after said member is heated, and means for shunting out the heat-coil when the burner is ignited.

3. In an electrical control mechanism for burners, the combination of a, fuel-supply motor, an ignition motor, a heat-coil and a 'ture-actuated dc-energize the motors when said member is heated, and means for shunting out the heatcoil and the ignition-motor when the burner is ignited. 1

4. In an electrical control mechanism for burners, the combination of a fuel-supply motor, an ignition-motor, a heat-coil, and a pair of contactors, all connected in series, a yielding means for separating the contactors,'and a thermostat metal member in proximity to the heat-coil to hold the contactors together when said member is cool, but to permit the contactors to separate and de-energize the motors when said member is heated, and means for shunting out the heat-coil when the burner is ignited.

5. In an electrical control mechanism for burners, the combination of a fuel-supply motor, an ignition-motor, a heat-coil, and a pair of contactors, all connected in series, a yielding means for separating the contactors, and a thermostat metal member in proximity to the heat-coil to hold the contactors together when said member is cool, but to permit the contactors to separate and de-energize the motors When said member is heated, and means for shunting out the ignition-motor when the burner is ignited.

6. In an electrical control circuit for burners the combination of a fuel-supply motor, an ignition-motor, and a time-limit cut-out all connected in series, a temperature actuated shunt-box forming when closed by heat from the burner, a shunt 'circuit around the ignition-motor and time-limit cut-out so as to substantially de-energize the ignition-motor and the time-limit cut-out.

7. In an electrical control circuit for burners the combination of a fuel-supply motor, an ignition-motor and a time-limit cut-out all connected in series, a temperature actuated shunt-box forming when closed by heat from the burner, a shunt circuit around the ignition motor so as to substantially deenergize the ignition-motor.

8. In an electrical control circuit for burners the combination of a fuel-supply motor, an ignitionmotor and a time-limit cut-out all connected in series, a temperashunt-box forming when closed by heat from the burner, a shunt circuit around the time-limit cut-out so as LO substantially de energize the time-limit cutout.

9. In an electrical control circuit for burners, the combination of a fuel-supply motor, an ignition-motor, and a time-limit cut-out all connected in series, and means cut-out, all connected in series in an-electric' for shunting out and thereby substantially de-energizing" the time-limit cut-out and the ignition motor when the burner is ignited,

10. In an electrical control circuit for burners, the combination of a fuel-supply motor, an ignition-motor, and a time-limit cut-out all connected in series, and means for shunting out the ignition-motor when the burner is ignited.

11. In an electrical control circuit for burners, the -combination of a fuel-supply motor, an ignition-motor, and a time-limit cut-out all connected in series, and means for shunting out the time-limit cut-out whenthe burner is ignited.

12. In an electrical control circuit for burners the combination of a fuel-supply motor, an ignition-motor, and a time-limit circuit, a temperature-actuated shunt-box and a fuse connected in series with each other but forming, when the shunt-box is closed by heat from the burner, a shunt or short circuit around the ignition-motor and the time-limit cut-out so as to substantially de-energize the ignition-motor and the time-limit cut-out.

13. In an electrical control circuit for burners, the combination of a fuel-supply motor, an ignition-motor, and a time-limit cut-out, all connected in series in an electric circuit, a temperature actuated shuntbox and a fuse connected in series with each other but forming, when the shunt-box is closed by heat from the burner, a shunt or ition-motor so motor. p p

14:. In an electrical control circuit for burners, the combination of a fuelssupply motor, an ignition-motor, and a time-limit cut-out, all connected in series in an electric circuit, a temperature-actuated shuntbox and a fuse connected in series with each other but forming, when the shunt-box is closed by heat from the burner, a shunt or short circuit around the time-limit,cut-out soyas to substantially de-energize the time limit cut-out.

15.- In an electrical control circuit for I burners the combination of a fuel-su ply motor, an ignition motor, and a time- 1m1t cut-out, allconnected in series in an electric circuit, a temperature actuated shunt-box and a fuse connected 1n series with each other but forming, when the shunt box is closed by heat from the burner, a shunt or short circuit around the ignition-motor and the time-limit cut-out, the fuse being-designed to carryits shunted proportion of the currentnecessary to run but not to start the fuel-supply motor. 7

16. In an electrical control circuit for burners the combination of a fueLsupply motor, an ignition-motor, and a time-limit cut-out, all connected in series in an electric circuit, a temperature actuated shunt-box and a fuse connected in series with each other but forming, when the shunt box is closed by heatfrom the burner, a shunt or short circuit around the time-limit cut-out,

the fuse being designed to carry its shunted proportion of the current necessary to run at not to start the fuel-supply motor.

17. In an electrical control circuit for burners the combination ofa fuel-supply motor, an ignition-motor and a time-limit cut-out, all connected in series in an electric circuit, a temperature actuated shuntbox and a fuse connected in series with each other but forming, when the shunt, box is closed by heat from the burner, a shunt or. short circuit around the ignition-motor, the.

fuse being designed to carry its. shunted proportion of the current necessary to run but not to start the fuel-supply motor.

18. In an electrical control mechanism for burners, the combination of a fuel-supply motor, an ignition-motor, and a time-limit cut-out, all connected'in seriesin an electric circuit, a temperature-actuated shunt-box consisting of a pair of contactors and a thermostatic metal member located in proximity to the burner and arranged to open the contactors when said member is cool and to close them when said member is heated,

said shunt-box being so connected as to shunt {out or 'short' circuit the ignitionmotor and the time-limit cut-out when the burner is ignited. i r

19. .In an electrical control mechanism for burners, the combination of a fuel-supply motor, an ignition motor, and a time-limit cut-out, all connected in series in an electric circuit, a temperature-actuated shunt-box consisting of a p'air'of contactors and a thermostatic metal member located in proximity to the burner and arranged to open 1' the contactors when said member is cool and to close them when said member is heated, said shunt-box being so connected as to shunt out or short circuit the ignition-motor when the burner is ignited. v

20'. In an electrical control mechanism for burners, the combination of a fuel-supply motor, an ignition-motor, and a timelimit cut-out, all connected in series in an electric circuit, a temperature-actuated shunt-box consisting of a pair of contactors and a thermostatic metal member located in proximity to the burner and arranged to open the contactors when said member is cool and to close them when said member is heated, said shunt-box being so connected as to shunt out or short circuit the time-limit cut-out when the-burner is'i ted.

21. In an e ectrical control circuit for burners, the combination of a fuel-supply motor, a time-limit cut-out, and an ignitionmotor, all connected in series, means operated by said ignition-motor for igniting the fuel supplied by said fuel-supply motor.

22. In an electrical control circuit for burners, the combination of a fuel-supply motor, a time-limit cut-out, and an ignitionmotor, all connected in series, means operated by said ignition-motor for igniting the fuel supplied by said fuel-supply motor, and other means for preventing said cut-out from de-energizing the fuel-supply motor when the burner is ignited.

23. In an electrical control circuit for burners, the combination in series, of a fuelsupply motor, an ignition-motor, a timelimit cut-out consisting of a heat-coil, a fixed contactor, and a movably mounted contactor connected in series, a yielding means tending to separate the two contactors. a thermostatic member in proximity to the heat-coil and arranged to hold the contactors together when said member is cool, but to allow them to separate when warmed by the heat-coil, and manually operated means for re-closing said contactors after said thermostatic metal member has cooled, and other means for preventing said contactors from separating when the burner is ignited.

24. In an electrical control mechanismfor burners the combination, in a series circuit, of a fuel-supply motor, an ignition-motor, a time-limit cut-out, and a thermostat operated means for opening and closing the circuit between desired limits of temperature, a temperature-actuated shunt-box forming a shunt circuit around the ignition-motor and the time-limit cut-out so as to shunt out the ignition-motor and the time-limit cut-out when the burner is ignited.

25. In an electrical control mechanism for burners the'combination, in a series circuit, of a fuel-supply motor, an ignition-motor, a time-limit cut-out, and a thermostat operated means for opening and closing the circuit between desired limits of temperature, a temperature-actuated shunt-box forming a shunt circuit around the ignition-motor so as to shunt out the ignition motor when the burner is ignited.

26. In an electrical control mechanism for burners the combination, in a series circuit, of a fuel-supply motor, an ignition-motor, a time-limit cut-out, and a thermostat operated means for opening and'closing the circuit between desired limits of temperature, a temperature-actuated shunt-box forming a shunt circuit around the time-limit cut-out so as to shunt out the time-limit cut-out when the burner is ignited.

27. In an electrical control mechanism for burners the combination, in a series circuit, of a fuel-supply motor, an ignition-motor, a time-limit cut-out, and a thermostat operated means for opening and closing-the circuit between desired limits of temperature, a temperature-actuated shunt-box and a fuse in series therewith forming a shunt circuit around the ignition-motor and the timelimit cut-out.

28. In an electrical control mechanism for burners the combination, in a series circuit, of a fuel-supply motor, an ignition-motor, a time-limit cut-out, and a thermostat operated means for opening. and closing the circuit between desired limits of temperature, a temperature-actuated shunt-box and a fuse in series therewith forming a shunt circuit around the ignition-motor.

29. In an electrical control mechanism for burners the combination, in a series circuit, of a fuel-supply motor, an ignition-motor, a time-limit cut-out, and a thermostat operated means for opening and closing the circuit between desired limits of temperature, a temperature-actuated shunt-box and a fuse in series therewith forming a shunt circuit around the time-limit cut out.

30. In an electrical control mechanism for burners, the combination, in a series circuit, of a fuel-supply motor, an ignition-motor, a time-limit cut-out, and a boiler controlled means for opening and closing the circuit under predetermined conditions, and a temperature-actuated shunt-box forming a shunt circuit around the ignition-motor and the time-limit cut-out.

31. In' an electrical control mechanism for burners, the combination, in a series circuit, of a fuel-supply motor, an ignition-motor, a time-limit cut-out, and a boiler controlled means for opening and closing the circuit under predetermined conditions, and a temperature-actuated shunt-box forming a shunt circuit around the ignition-motor.

32. In an electrical control mechanism for burners, the combination, in a series circuit, of a fuel-supply motor, an ignition-motor, a time-limit cut-out, and a boiler controlled means for opening and closing the circuit under predetermined conditions, and a temperature-actuated shunt-box forming a shunt circuit around the time-limit cut-out.

33. In an electrical control mechanism for 1 of a fuel-supply motor, an ignition-motor,

a time-limit cut-out, and a boiler controlled means for opening and closing the circuit under predetermined conditions, a temperature-actuated shunt-box and a fuse connected in series therewithand forming a shunt cir-' cuit around the ignition-motor.

35. In an electrical control mechanism for burners the combination, in a series circuit, of a fuel-supply motor, an ignitionmotor, a time-limit cut-out, and a boiler controlled means foropening and closing the circuit under predetermined conditions,

a temperature-actuated shunt-box and a fuse connected in series therewith, forming a shunt circuit around the time-limit cut-out.

motor, an ignition-motor, a time-limit cut-- out and a main-circuit switch all connected in series, and a temperature-actuated shunt box forming when-closed by the heat from the burner, a shunt circuit around the ignition-Inotor. i 1

38. In an electrical control circuit for burners, the combination of a fuel-supply motor,.an ignitiommotor, a time-limit. cutout, and a main-circuit switch all connected in ser es, and a temperature-actuated shunthox forming when closed by the heat from the burner, a shunt circuit around the timelimit cut-out.

box and a fuse connected in series with each other but forming, when closed by heat from the burner, a shunt or short circuit around the ignition-motor and the time-limit cutout.

40.- In an electrical control circuit for burners, the combination of a fuel-supply motor, an ignition-motor, a time-limit cutout and a 'main circuit switch all connected in series, 'a temperature-actuated shunt-box and a fuse connected in series with each other but forming, when closed by heat from the burner, a shunt or short circuit around the ignition-motor.

41. In an electrical control circuit for burners. thecombination of a fuel-supply motor, ignition-motor, a time-limit cut-out and a main-circuit switch all connected in series, a temperature-actuated shunt-box with a fuse connected in series therewith, forming when closed by heat 'from the burner, a shunt or short circuit around the time-limit cut-out.

FRANK FISCHER. ARNOLD F: VAN PELT.

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