US2220257A - Fluid fuel burner ignition control - Google Patents

Description

5 Sheets.Sheet 1 Filed June 12, 1939 lNVENTdR. IRA E.M C/|EE Nov. 5, 1940. 1, E, McCABE 2,220,257

FLUID FUEL BURNER IGNITION CONTROL Filed June 12, 1939 a Sheets-Sheet 2 INVENTXOR. l/M .5. MC @455 ATTORNEY.

' NOV. 5, 1940. cc I 2,220,257

FLUID FUEL BURNER IGNITION CONTKQL I Filed June 12 1939 3 Sheets-Sheet 3 Patented Nov. 5, 1940 UNITED STATES PATENT OFFICE 2,220,257 FLUID FUEL BURNER, IGNITION CONTROL Ira E. McOabe, Chicago, Ill.

Application June 12, 1939, Serial No. 278,673

17 Claim.

operation of an ignition switch is controlled by the conjoint action of a fuel pressure responsive means and an electro-thermal timing mechanism being adapted to open the ignition switch a. predetermined time after the starting of the burner the pressure responsive means and those maintained at the burner.

It is another object of this invention to so arrange the electro-thermal switch operating mechanism of such an ignition control in combinationwith an oil burner motor control that when the burner motor 'control stops the motor it will reset the ignition control to insure an ignition period at each starting of the burner motor.

With these and other objects in View, reference is made to the accompanying sheets of drawings which illustrate a preferred form of this invention, with the understanding that detail changes may be made without departing from the scope thereof.

In the drawings: 1

Figure 1 is a schematic view illustrating the application of this invention to a pressure type oil burner forming a part of a domestic heating system, including a wiring diagram therefor including an enlarged wiring diagram of the instrument panel projected from the panel casing as it appears upon the oil burner.

Figure 2 is an enlarged detail view in front elevation of the instrument panel, with the side walls of the cover shown in section, and illustrating the construction and wiring connections of this improved ignition control in association with a burner motor control.

mechanism but dependent upon the pressure tained between the pressures which operate upon' Figure 3 is an enlarged top plan view of this improved ignition control.

Figure 4 is a view in end elevation of Figure 3, looking at the right end thereof, and with parts broken away and partly in section. 6

Figure 5 is a detail view of the ignition control shown in Figure 2 with parts broken away and partly in section with the ignition switch in closed position.

switch open.

Figure '7 is a view in rear elevation of Figure 5.

In some forms of electrically operated and controlled fluid fuel burning devices, such as oil burners forming a part of domestic heating systems, the fluid is supplied under pressure to the burner nozzle and an electrical igniter is provided to ignite the fuel during an ignition period when the igniter is energized.

An ignition control for creating the ignition period is disclosed in this applicants prior Patent No. 2,140,708, December 20, 1938, which is partially operated by the fuel pressure and the period of ignition discontinued by the passage of the current through the igniter or ignition cir-v cuit for a predetermined time. Such a control employs an electro-thermal means'for opening the ignition circuit and may be so adjusted that the fuel pressure responsive means acts only when a predetermined pressure is exceeded to cause the opening of the ignition switch and upon a drop in the predetermined pressure to restore the ignition circuit irrespective of the operative state of the electro-thermal means.

In the pressure type 011 burners, the normal operating pressure maintained in the burner nozzle is usually about. 100 pounds per square inch and the capacity of the various sizes of nozzles in gallons per hour is based upon the delivery of fuel at this pressure. Frequently-it'is desirable to increase or decrease the burner flame in accordance with the demands of particular heating systems and this can be accomplished, within certain limits without changing the size of the nozzle, by varying the pressure of the fuel. The operating pressure of the fuel may be varied by adjusting the pressure regulating device employed in all pressure burners interposed between the fuel pump and the nozzle to maintain a constant pressure at the nozzle.

When the fluid fuel burner ignition control of Patent No. 2,140,708, is employed with a pressure type oil burner. and the adjustment of the pressure regulator is changed toadapt the burner mechanism to the demands of a particular heat- Figure 6 is a similar view with the ignition ing system, as above described, a compensating change must be made to the operating mechanism of the ignition control. While such manual adjustments may be made: in the said patented ignition control, failure to make them might result in a failure to provide ignition upon a delivery of oil at the nozzle following an extinguishment of the burner flame, as is possible where a drop in fuel pressure due to a leak or pump failure causes extinguishment of the flame, but is insufllcient to operate the ignition control.

The embodiment of the invention illustrated upon the accompanying drawings provides a pressure responsive ignition control which will auto-' matically adjust itself to compensate for variations made in the pressure regulating device. Figure 1 is a diagrammatic illustration of an oil burning heating system in which a pressure type of oil burner O of a commercial form is installed in a domestic heating furnace F, located in the basement of a dwelling. The wires L, L from the commercial source of electricity pass through a hand switch H to an instrument panel I, located on the rear of the oil burner under the cover C. The wire L preferably passes through a commercial boiler control B on its way to the panel. The wires L, L are connected through the panel to the burner motor M and to the ignition transformer I, as will hereinafter be described. A room thermostat T of commercial form for controlling the operation of the oil burner is shown in a room above.

As shown in the wiring diagram in Figure 1 and in the detail of theinstrument panel I is shown in Figure 2, the wire L from the commercial source of electricity is connected to the binding post 2 which is connected by the wires 8 through a normally closed safety switch SS and through the windings of the primary coil PC of a commercial type of repulsion relay to the binding post 4 to which the wire L is connected. The repulsion relay includes a secondary coil SC. The windings of the secondary coll SC are connected to binding posts I and I4, located in a terminal post supporting plate above the relay. Posts 8 and I are connected by wires I to the room thermostat T while posts 8 and I4 are connected to a safety switch electrical resistance heater SH which cooperates with a thermostatic arm I2 to release the normally closed safety switch SS to open, upon energization of the heater, for a predetermined time. The secondary. coil SC is mounted upon one end of a pivoted arm 8 which carries the motor switch MS so mounted on the other end that the weight of the dead or deenergized coil SC will open the switch, as shown in Figure 2. With the circuit closed through the r elay primary coil PC and the room thermostat calls for heat, the circuit through the secondary coil SC of the relay is closed and the coil is repelled to close the motor switch MS, as shown in Figure 1. The circuit established by the closing of the room thermostat through wires 5 passes through post 8, resistance heater SH, post I4, windings of the secondary coil SC to post I. With the motor switch closed the current from wires 3 divides and passes through wires 8, binding post I 8, through the burner motor M, and binding post II to binding post 4 which is connected to wire L. When the room thermostat closes the secondary coil circuit, the safety switch heater SH is also energized and after a predetermined time, provided for the purpose of establishing combustion, will operate to cause the opening of the safety switch SS and stop operation of the burner.

In order to allow the safety switch SS to remain closed after establishment of the burner flame visible rays of light emanating from the burner flame to close the circuit therethrough, whereby in the event of the failure of the fuelto ignite,

the shunt circuit remains open and the heater SH will operate to allow the safety switch SS to open, which will result in a complete shut down of the burner mechanism.

. In order to ignite the fuel in the nozzle within the predetermined time allowed by the .above safety device, an electrical ignition device is provided which in common practice is actuated by the energization of an ignition transformer I. In this embodiment of this invention an ignition switch IS and an ignition heater IH are provided and are connected in circuit on the instrument panel, as shown in Figure 1. The current from the motor switch MS is divided at binding post III and-part passes through wire I5, through the ignition switch IS, when closed, through binding post I8, through the ignition transformer I and back through binding post I I to binding post 4 which is connected to wire L. Part of the cur.- rent passing through wire I! from the closed ignition switch IS divides at binding post I6 and passes through wire I1, through the electrical resistance igniter heater 11-1, the purpose of which will hereinafter be described, through binding post II to binding post 4 which is connected to wire L. If desired thewiring of the control may be revised so as to connect the heater III in series with the ignition transformer.

Like the fluid fuel burner ignition control described in this applicant's pror Patent No. 2,140,708, December 20, 1938, this improved control is partially operated by fuel pressure through the response of a Bourdon tube I8 to changes in oil pressure. One end of the Bourdon tube I8 is mounted on a block l8 through which it is connected by a nipple 28, shown in Figures 2, 3 and 5, i

to a pipe 2I leading from the pressure gauge G of the pressure regulator R interposed in the oil line between the burner nozzle, not shown, and the burner motor operated oil pump OP, as shown in Figure 1. Oil is supplied to the oil pump by pipe P leading from an oil tank located wherever most desirable.

The block I8 is mounted upon the upper left portion of the panel I by screws 22 passing through apertures provided therefor in the block. A base plate 23 is secured to the front of the block I9 by the screws 24- and extends to the right thereof substantially in line with the Bourdon tube I8. The upper lefthand portion of the base plate 23, as shown in Figure 5, is provided with an extension 25 bent at right angles thereto to form an arm to which is attached a bracket 26 supporting depending clips 21 for engaging and supporting the ignition switch IS. The free end of the Bourdon tube I8 terminates in a closed end between thelupper portion of the base plate 28 and the panel I. The closed end of the Bourdon tube I8 includes an arm 28 extending axially in prolongation thereof and is pivotally connected at its end to a link 29. The other end of the link 29 mounts a disc 30 adapted to bear upon the apex of a bell crank lever, the lower arm 3| of which is pivotally mounted upon a stud 32 mounted on the rear of the base plate 23, with the other arm 33 terminating in a portion 34 bent at right angles thereto to extend over an indentation 35 formed in the base plate 23. The disc 39 on the end of the link 29 is provided with an axial stud 36 adapted .to pass through and travel within a slot 31 formed in the apex body portion of the bell crank lever. The surface of the disc 39 is held in engagement with the body portion of the apex of the bell crank lever by a spring 39 secured at its lower end to the arm 3| adjacent its pivotal point 32. .The portion of the base plate 23 spaced apart from the shoulder 35 is provided with an arm 39 bent at right angles thereto adapted to be engaged by one end of an adjustable pin 49 carried in the portion 34 of the arm 33 of the bell crank lever which extends over the shoulder 35 of the base plate and acts as a stop therefor.

The ignition switch IS is preferably a mercury tube switch which is mounted at an angle, as shown in Figures 2 and 5, whereby a pool of mercury is maintained in the lower end. This switch is preferably of the magnetically operated type, such as disclosed in this applicant's prior' Patent No. 2,140,708, December 20, 1938, Figure 8, in which one electrodesupporting an armature, is resiliently mounted so that its contact point 42 will normally be out of engagement with the pool of mercury. The switch is closedby a movable permanent magnet 43 when it is brought adjacent the side of the tube of the ignition switch IS to bring the armature 4| within its field and opened when the magnet is moved away sumciently to remove the influence of its field upon the armature. The magent 43 ismounted adjacent the lower end of anoperating arm 44, the upper end of which is pivotaily mounted upon a stud 45 extending between the base plate 23 adjacent the shoulder 35 and a front plate 48 spaced apart from the base plate 23 by posts 41, as shown in Figure 3. The lower extremity of the operating arm 44 mounts a counterweight 48 which will cause the arm, when free, to rotate about its pivot to move the magnet away from the ignition switch to open the ignition circuit. The base plate 23 mounts a stop 49 between the tube of the switch IS and the operating arm 44 to limit its travel and prevent the magnet 43 from bearing against the tube. The upper portion of the operating arm is provided with two shoulders 50 and 5|. The shoulder 50 is so formed that it will engage the upper post 41 supporting the front plate 46 to limit the swing of the magnet away from the switch IS'and the shoulder, 5! is adapted to be engaged .by the lower end of the pin 40' carried in the portion 34 of the Bourdon tube or pressure controlled bell crank lever 3 |-33. With the contraction of the Bourdon tube l3 through its connection to the bell crank lever 31-33 the pin 40 is caused to move toward the operating arm 44 until the pin 49 engages the shoulder 5| whereupon movement is imparted to the operating arm toward the switch. When the operating arm 44 engages the stop 49 and further contraction of the Bourdon tube continues. the disc 30 will slide over the bell crank lever 3l- -33 under the tension of the spring 38 until the axial stud 36 sliding within the slot 31 of the bell crank lever reaches the bottom thereof. With ,the applicamovement of the end of the Bourdon tube in the opposite direction will immediately impart a counter-rotation to the bell crank lever through the clutch formed by the disc 39 and spring 33-. Upon increasing the pressure within the Bourdon tube the pin 49 wiil move to free the operating arm 44 and will continue in its movement until it engages the stop arm 39 whereupon continued movement of the Bourdon tube may occur by reason of the aforementioned clutch arrangement. The slot 31 in the bell crank lever is so arranged as to permit unrestricted movement of the Bourdon tube when subjected to its highest operating pressures. As it is necessary to maintain the ignition switch IS closed for a predetermined time to provide for an ignition period,

it is necessary to provide means, independent of the Bourdon tube l8, to hold the magnet 43 in oparm 44 engages the stop 49. In order to release the operating arm 44, the pawl 54 is rotated about its pivot to lift the tooth 53 from engagement with the notch 52 so that the counterweight 48 may rotate the magnet 43 into its inoperative position, as shown in Figure 6. To accomplish this, a strip of thermal or bi-me'tallic metal 55 is bent about a spool 55a of an electrical resistance heater IH, shown in Figure 1, with the ends of the strip extending therebelow in parallel relation. One end l3 of the strip is secured to a right angular extension 51 of a supporting plate 58 rotatably mounted upon a stud 59 extending into the base plate 23 to the right of and below the stop 39 and supports the spool 55a at right angles to the plate 23. The other'end 60 of the strip 55 dependsbelow the end of the pivoted pawl 54. The end of the pawl is provided with a nose 9| adapted to be engaged by the end 69 of the thermal strip when moved in that direction upon energizing the heater 11-1 to lift the pawl 54 to release the operating arm 44. The base plate 23 below the heater IH is provided with an angular extension 82 to mount an adjustable stop 83 adapted to be engaged by the end 50 of the thermal strip'when cold. The heater support ing plate 58 is preferably struck up to form a small bearing surface about its pivot and is pressed into engagement with the surface of the base plate 23 by the free end of a leaf spring 65 engaging an extension 64 of the pivot 59; the other end of the spring being secured to the base plate 23 by screw 66. The tension of the spring plate is such that normally, heating and cooling of the bi-metallic metal 55 will cause only the free end 69 to move. The portion of the leaf spring 65 between the spool 55a and the supporting plate 58 preferably mounts a sheet of mica 61 or other insulating material.

By proper arrangement of the operative structure and through adjustment at the factory of the pin 40 carried upon the pressure actuated bell crank lever, the. magnet operating arm 44 will be caused to close the ignition switch at a predetermined drop in fuel pressure and upon the establishment of a predetermined pressure within the Bourdon tube move the pin from engagement with the arm 44 and at the same time by proper adjustment of the stops 63 with the end 80 of the thermostatic strip 55 in engagement therewith andthe heater IH energized, the time thereafter required to lift the pawl 84 to release the operating arm 44 may be determined.

In the operation of fluid fuel burners there are times when for some reason or other, as in the case of a momentary power failure or failure of the burner flame, the normal operation of the burner is interrupted and when this occurs as to cause a cessation of combustion with a subsequent opening of the burner motor circuit it is most desirable that an operative igniter behad when operation is resumed, particularly so should the interruption and resumption of operation take place within a very short time. This inven- 'tion contemplates meeting these contingencies to the extent that with each opening of the motor switch MS while the thermostatic strip 55 is heated and expanded the ignition control is reset to starting position to provide an ignition period toaccompany the re-starting of the burner. In order to accomplish this an arm 8, shown in dotted lines on Figure 2, is mounted on the secondary coil SC of the repulsion relay and so arranged that each time the coil falls the free end of the arm 68 will engage the end 60 of the thermostatic strip 55 to cause the supporting plate 58 to rotate about its pivot and allow the end 8' to be brought into engagement with the stop 63, the same as would be accomplished by the normal cooling of the strip 55.

As above said, a commercial pressure regulatoris interposed between the fuel pump and the nozzle of the burner to maintain a substantially constant pressure at the nozzle to atomize the fuel. It is in connection with the use of these regulators employed in all fluid fuel burner mechanisms of the liquid fuel pressure type that this improved form of ignition control proves most advantageous. One type of pressure regulator is provided .with a manually adjustable means by whichthe pressure of the fuel delivered at the nozzle may be varied having a delivery port with means to maintain the port closed up to a predetermined pressure, usually pounds per square inch, and thereafter allow the delivery of fuel to the nozzle at a pressure not to exceed the predetermined setting which means also acts to antomatically cut off the delivery of fuel whenever the pressure of the fuel drops 25 pounds per square inch below the predetermined setting. Another type of pressure regulator, in addition to the manual adjustment for predetermining the delivery pressure at the nozzle, is provided with means to adjust the pressure at which the cut-oi! automatically acts in relation .tothe predetermined pressure. In other words, one form includes a constant diiferential at which the cut-off automatically acts, while the other formincludes means for varying this diiferential. In these commercial pressure regulators the minimum pressure adjustment is 60 pounds per square inch and the minimum diiferential is 25 pounds per square inch. In the ignition control disclosed herein, the pin 40 is movable between the shoulder SI of the operating arm 44 when in operative position with the ignition switch and the fixed arm 39, moving from one limit to the other upon an increase or decrease in pressure of less than the customary 25 poundsminimum diiferential maintained in the commercial pressure regulators between the pressure at which fuel is delivered and maintained at the burner nozzle and the pressure at which fuel by engagement with stop arm 39 or by shoulder 5|, when the arm I is against stop pin 4.9, the Bourdon tube clutch mechanism permits continued movement of the Bourdon tube as the pressure within the tube increases or decreases, but immediately upon reversing the pressure condition the movement of the tube is imparted to the pin 40 so that regardless of the operating pressures established by the pressure regulators the ignition switch IS is automatically closed on a drop in pressure less than that required to cause the regulator to cut-ofl the supply of fuel to the burner nozzle. Since during-a normal period of burner operation the ignition switch is opened after the expiration of the ignition time period,. the electrical resistance heater ll being in the circuit controlled by the ignition switch is deenergized and with the cooling of the bi-metallic member 55 the free end 60 thereof moves back to engage the adjustable stop 63. Thus if through some abnormal circumstance the burner flame should be extinguished through loss of fuel pressure it will be preceded by the closure of the ignition switch and as the heater IH has cooled to starting position any resumption of burner operation will be accompanied by a period of ignition.

When the extinguishment of the burner flame has.been caused by a loss inpressure resulting from the interruption of the burner circuit, from any cause, beforethe bi-metallic member 60 returns to starting position against the stop 63, the arm 68, secured to the secondary coil SC will, as the coil falls to its deenergized position, engage the member 60 to cause the supporting bracket therefor to move about its pivot until the arm 60 engages stop 63 and ignition is also assured upon resumption of burner operation when the burner circuit is again restored.

What I claim is':

1. In an electrically operated and controlled fluid pressure burner mechanism including an electrical igniter, an ignition circuit, a switch in the ignition circuit, and means for operating the switch, including a fuel pressure-responsive means, and an electrically operated thermal means co-acting therewith and arranged upon initiation of operation of the burner mechanism to operate the switch a predetermined time render the opening means partly effective dependent upon the establishment of a predetermined fuel operatlng pressure and additional means to complete the opening of the switch dependent upon the establishment of the ignition circuit, said means to render the opening means partially effective provided with means allowing a predetermined decrease in pressure after the ignition switch has opened to insure the prompt closing thereof.

3. In an electrically operated and controlled fluid fuel pressure burner mechanism including is cut off. When movement of the pin is limited an electrical igniter, an ignition circuit, a northose required to operate the switch, said last named means acting upon a predetermined decrease in pressure after the ignition switch has been opened to insure the prompt closing of said switch.

4. In an electrically operated and controlled fluid fuel pressure burner mechanism including an electrical ignition, an ignition circuit and a normally closed ignition switch therein when the burner mechanism is idle, means for operating the switch to open the igmtion circuit,

means responsive to the pressure of the fluid fuel, a connection between the operating means and pressure responsive means arranged upon the establishment of a predetermined fluid fuel Ipressure upon initiation of operation of the burner mechanism to partially effect the operationof the switch operating means, and thermally operated means actuated by the passage ofcurrent through the normally closed ignition circuit to cause the operating means to open the ignition circuit, said connection having an override means allowing movement of the pressure means upon pressure changes in excess of those required to operate the switch and adapted upon a predetermined decrease in pressure after the Ignition switch has been opened to insure a prompt closing of said switch.

5. In an electrically operated and controlled fluid fuel pressure burner mechanism including an electrical ignition device, an ignition circuit and a magnetically operated switch therein, a magnetic actuator therefor, a locking member normally locking the magnetic actuator when the switch is closed, means responsive to the pressure of the fluid fuel arranged to engage said magnetic actuator and close the ignition switch upon a predetermined differential drop in fluid fuel pressure and arranged upon a predetermined increase in fluid fuel pressure upon initiation of operation of the burner mechanism to be disengaged therefrom, and thermally operated means actuated by the continued passage of the current through the normally closed ignition circuit to unlock the magnetic actuator to open the ignition switch.

6. In an electrically operated and controlled fluid fuel pressure burner mechanism including an electrical ignition device, an ignition circuit and a magnetically operated switch therein, a magnetic actuator therefor, means responsive to the pressure of the fluid fuel arranged to act upon said magnetic actuator and close the ignition switch upon a predetermined differential drop in fuel pressure and arranged upon a predetermined increase inpressure upon initiation of operation of the burner mechanism to be inactive upon said means, means delaying the action of the magnetic actuator to open the switch when rendered active by the pressure means including an electrically operated time actuator in the ignition circuit, said pressure responsive means including an override connection allowing unrestricted movement of the pressure means over its entire operating range beyond the pressures required to operate the switch.

7. In an electrically operated and controlled fluid pressure burner mechanism including an electrical igmter, an ignition circuit, a switch in the ignition circuit, means for operating the switch, means responsive to the pressure of the fluid fuel arranged to act upon said operating means and close the ignition switch upon a predetermined differential drop in fuel pressure and arranged upon a predetermined increase in pressure upon initiation of operation of the burner mechanism to be inactive upon said means, means delaying the action of the operating means to open the switch when rendered active by the pressure means including an electrically operated time actuator in the ignition circuit, said pressure responsive means including an override connection allowing unrestricted movement of the pressure means overits entire operating range beyond the pressures required to operate the switch.

8. In an electrically operated and controlled fluid pressure burner mechanism including an electrical igniter, an ignition circuit, a switch in the ignition circuit, means for operating the switch, a locking member normally locking the operating means when the switch is closed,

'means responsive to the pressure of-the 'fluid fuel arranged to engage the operating means and close the ignition switch upon a predetermined differential drop in fuel pressure and arranged upon a-predetermined increase in fluid fuel pressure upon initiation of operation of the burner slip connection between the pressure responsive member and operator to allow continued movement of the pressure member beyond the limited ally operated means, upon stopping the operation of the burner mechanism, to reset the electrothermal means substantially to the beginning of its timed period of operation.

10. In a fluid fuel burner mechanism, electrically operated means controlling the operation thereof, an electrical igniter, an ignition circuit, a magnetically operated switch in the ignition circult, a magnetic actuator therefor, including a.

fuel pressure-responsive means, and an electrothermal means co-acting therewith and arranged upon initiation of operation of the burner mechanism to operate the switch a predetermined time thereafter, adjustable means fordetermining the said switch means, and means cooperating with the electrically operated means, upon stopping the operation of the burner mechanism, to reset the electro-thermal means substantially to the beginning of its timed period of operation.

11. In a fluid fuel burner mechanism, electrically operated means controlling the operation thereof, an electrical igniter, an electrical ignition circuit, a normally closed ignition switch tnerein for establishing said circuit upon operation of the burner mechanism, means toopen the ignition switch actuated a predetermined time after establishment of the ignition circuit including means to render the opening means partly effective dependent upon the establishment of a predetermined fuel operating pressure and additional means to complete the opening of the switch, dependent upon the establishment of the ignition circuit, including an adjustable timed actutaor in the ignition circuit adapted to complete the opening of the switch, and means cooperating with the electrically operated means upon stopping operation of the burner mechanism to reset the timed actuator substantially to the beginning of its timed period of operation.

12. In a fluid fuel burner mechanism, electrically operated means controlling the operation thereof, an electrical igniter, an electrical ignition circuit, a normally closed ignition switch therein for establishing said circuit upon operation of the burner mechanism,. means for operating the switch, means responsive to the pressure of the fluid fuel arranged to act upon said operating means and close the ignition switch upon a predetermined diflerential drop in fuel pressure and arranged upon a predetermined increase in pressure upon initiation of operation of the burner mechanism to be inactive upon said means, means delaying the action of the operating means to open the switch when rendered active by the pressure means including an electrically operated time actuator in the ignition circuit, said pressure responsive means including an override connection allowing unrestricted movement of the pressure means over its entire operating range beyond the pressures required to opertion of operation of the burner mechanism to partially effect the operation of the switch actuator, an adjustable timed actuator arranged to cause the switch actuator to open the ignition switch upon establishment of the ignition circuit,

and means cooperating with the electrically oper-- ated means upon stopping the operation of the burner mechanism to resetthe timed actuator substantially to the beginning of its timed period of operation. v

14. in a fluid fuel burner mechanism electri cally operated means controlling the operation thereof, an electrical igniter, an ignition circuit, a switch in the ignition circuit and means for time of action of the electro-thermal means upon operating the switch including a fuel pressure responsive means and a timed actuator in the ignition circuit co-acting therewith and arranged upon initiation of operation of the burner mechanism to operate the switch a predetermined time thereafter, said pressure responsive means including an override connection allowing unrestricted movement thereof upon pressure changes in excess of those required to operate the switch, adjustable means for determining the time of action of the electro-thermal means, and means cooperating withthe electrically operated means upon stopping the operation of the burner mechanism to reset the timed actuator substantially to the beginning of its timed period of operation.

15. In a fluid fuel burner mechanism, electrically operated'means controlling the operation thereof, an electrical igniter, an ignition circuit, a normally closed ignition switch therein for establishing said circuit upon operation of the burner mechanism, means to open the ignition' switch actuated 'a predetermined time after establishment of the ignition circuit including means to render the opening means partly effective dependent upon the establishment of a predetermined fuel operating pressure and additional means to complete the opening of the switch dependent upon the establishment of the ignition circuit, said pressure responsive means provided with means to allow unrestricted'movement thereof upon pressure changes in excess of those required to operate the switch, said last named means acting upon a predetermined decrease in'pressure after the ignition switch has been opened to insure the prompt closing of said switch, adjustable means for determining the time of action of the thermally operated means, and means cooperating with the electrically operated means upon stopping the operation of the burner mechanism to reset the thermally operated means substantially to the beginning of its timed period of operation.

16. In a fluid fuel burner mechanism, electrically operated means controlling the operation thereof, an electrical igniter, an ignition circuit and a magnetically operated switch therein, a magnetic actuator therefor, a locking member normally locking the magnetic actuator when the switch is closed, means responsive to the pressure of the fluid fuel arranged to engage said magnetic actuator and close the ignition switch upon a predetermined differential drop in fluid fuel pressure andarranged upon a predetermined increase in fluid fuel pressure upon initiation of operation of the burner mechanism to be disengaged therefrom, and thermally 0perated means actuated by the continued passage of the current through the normally closed ignition circuit to unlock the magnetic actuator to open the ignition switch, adjustable means for determining the time of action of the thermally operated means, and means cooperating with the electrically operated means upon stopping the operation of the burner mechanism to reset thethermally operated means substantially to the beginning of its timed period of operation.

17. In a fluid fuel burner mechanism, electrically operated means controlling the operation thereof, an electrical igniter, an ignition circuit and a magnetically operated switch therein, a magnetic actuator therefor, means responsive to the pressure of the fluid fuel arranged to act upon said magnetic actuator and close the ignition switch upon a predetermined diiferential drop in fuel pressure and arranged upon a predetermined increase in pressure upon initiation of operation of the burner mechanism to be inactive upon said means, means delaying the action of the magnetic actuator to open the switch when rendered active by the pressure means including an electrically operated time actuator in the ignition circuit, said pressure responsive means including an override connection allowing unrestricted movement of the 0 pressure means over its entire operating range beyond the pressures required to operate the switch, adjustable means for determining the time of action of the thermally operated means, and means cooperating with the electrically operated means upon stopping the operation of the burner mechanism to reset the thermally operated means substantially to the beginning of its timed period of operation.

IRA E. McCABE. 10

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