US2142530A

US2142530A - Safety control means for oil burners

Info

Publication number: US2142530A
Application number: US136774A
Authority: US
Inventors: Stahl John; Fischer Hans
Original assignee: Fairlie & Wilson Coal Co
Current assignee: Fairlie & Wilson Coal Co
Priority date: 1937-04-14
Filing date: 1937-04-14
Publication date: 1939-01-03
Anticipated expiration: 1956-01-03

Description

Jan. 3, 1939. J STAHL ET AL V 2,142,530

SAFETY CQNTROL MEANS FOR OIL BURNERS Filed April 14, 1937 4 Sheets-Sheet l r051. PUMP A6 10.4 TIA/9 "070R.

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SAFETY CONTROL MEANS FOR OIL BURNERS vim/62211, az-zj p zgzmm'z ATTORNEY.

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SAFETY- CONTROL MEANS FOR 011. BURNERS Jan. 3, 1939.

Filed April 14, 1937 4Sheets-Sheet. 3

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Jan. 3', 1939.

J. S' l' AHL 1- AL 2,142,530

SAFETY CONTROL MEANS FOR OIL BURNERS Filed April 14, 1957 4 Sheets-Sheet 4 INVENTORS;

ESCZIZZ,

ATTORNEY.

Patented Jan. 3, 1939 UNITED s'rAT-ss PATENT OFFICE sen-:1! CONTROL mums Fort OIL BUBNEBS Application April 14, 1937, Serial No. 136,774

9 Claims.

This invention relates, generally, to improvements in safety control means for oil burners; and the invention has reference, more particularly, to a novel electro-mechanical means adapted to automatically arrest operation of an oil burner in the event of any failure of its operating elements to properly function, or in the event of the interruption or if improper delivery of fuel thereto.

This invention has for an object to provide novel electro-mechanical means to govern the operation of the fuel pump acuating motor of an oil burner apparatus so that delivery of fuel to the burner nozzle cannot occur unless and until the electrical ignition means serving the burner nozzle is operative.

This invention has for another object to provide an electrical-mechanical control system comprising a main circuit serving the electrical devices of the burner apparatus, said main circuit including a normally closed tripable cut-out or safety switch; that part of said main circuit which serves the fuel pump motor including a normally open motor control switch in series with said cut-out or safety switch; that part of said main circuit which serves the electrical ignition means including a transformer, the primary winding of which is also in series with said cut-out or safety switch; an

electro-mechanical trip means for said cut-out or safety switch, the circuit of which includes a trip control -switch also in series with said cut-out or safety switch; thermostatic actuating means for closing said motor control switch; and means governed by normal flow of fuel to the nozzle of the burner apparatus for opening said trip control switch.

Other objects of this invention, not at this time more particularly enumerated, will be understood from the following detailed description of the same.

An illustrative embodiment of the invention is shown in the accompanying drawings, in which Fig. l is aside elevation of the tubular mixing chamber or gun of an oil burner apparatus as equipped with the novel electro-mechanical safety control means according to this invention, this view also including a wiring diagram showing the electrical circuits employed; Fig. 2 is a horizontal sectional view of the same; Fig. 3 is in parta side elevation and in part a vertical sectional view of the same; and Fig. 4 is an enlarged fragmentary detail view of the clutch connection between the thermostatic actuating means and the motor control switch carrier. Fig. 5 is a simplified wiring diagram showing the electrical circuits of the safety. control means according to this invention.

Similar characters of reference are employed in the hereinabove described views, to indicate corresponding parts.

Referring to the drawings, the reference character 5 indicates the tubular mixing chamber or gun of an oil burner apparatus. Disposed within the interior of said mixing chamber or gun, to extend axially therein, is the fuel burner pipe 8, the same being provided at its outer end with a suitable burner nozzle I which is located within the outer open end of said mixing chamber or gun 5. The outer end of said mixing chamber or gun 5 is provided with a mixer ring 8 having internal spiral vanes 9 which serve to swirl the air, delivered through the mixing chamber or gun 5, about the burner nozzle 1 so as to mix such air with the fuel such as oil, discharged from the burner nozzle, and thus produce the necessary combustible mixture of oil and air which is ignited and discharged into the fire-box or combustion chamber of the furnace or the like which is served by the oilburner apparatus. The burner pipe 6 is supported within the mixing chamber or gun 5 by a suitable standard l0 aflixed to the latter. Said standard Ill is-provided with oppositely disposed laterally and upwardly offset bracket members II and B2 in which are respectively supported electrode holders I3 and H from the forward ends of which extend electrical ignition electrodes l5 and l6. Said ignition electrodes are provided with inwardly offset free'end portions l1 and is having spark gap forming terminals 18 and 20 .locate'd adjacent to and overhanging theburner nozzle 1. Also provided'in connection with saidstandard it, to extend longitudinally above the supported burner pipe 6 and between the bracket members i i and I2 is a slideway member 2 I. Movable longitudinally on said slideway member 2| is a slide plate 22, the movements of which are guided'by slots 23 formed therein which ride on guide screws 2t afiixed to said slideway member 2|. Afilxed to the forward end portion of said slide plate 22 is a spark gap insulator, the same comprising an inverted T-shaped member formed by an upstanding central portion 25 bordered by oppositely extending horizontal portions 26 which respectively underlie the offset free end portions I1 and I 8 of the ignition electrodes 15 and 16. At its forward .free end, said central portion 25 isprovlded with a wedge-shaped extremity 21. The spark gap insulator may be made of any suitable electrical insulating material, such e. g. as steatite. When the oil burner apparatus is not operating, said spark gap insulator occupies a forwardly .projectedposition so that the front end part of said boss 68 of reduced diameter.

the spark gap terminals I9 and 28 of the ignition electrodes (see Fig. 2), thus preventing arcing therebetween when current is initially served thereto until other starting operations assure proper delivery of oil to the burner nozzle for operative discharge therefrom.

Suitably mounted on an external side'of the mixing chamber or gun 5, so as to be preferably disposed in a vertical plane, is a panel 28. Extending through said panel 28, and through the adjacent wall of the mixing chamber or gun 5,

is a metallic casing 29. This casing 29 is provided with an annular shoulder portion 38 which abuts the outer face of said panel 28. Extending rearwardly from said shoulder portion 38 and through the panel is a threaded boss 3| which receives a keeper nut 32, whereby the casing 28 is affixed to the panel 28. Said casing 29 'is provided at its outer end with a forwardly proiecting'tubular extension 33. ,One of the electrode holders, as I3, is provided at its rearward end portion with a diametrically enlarged cham-" bered member 34. The rearward end portion of said casing 29 passes inwardly through the wall of said chambered member 34 so as to extend transversely into the interior of the latter. Arranged within the caslng 29 is a helical bimetallic thermostatic element 35, the rearward end portion of which is fixedly anchored to said casing. Suitably afllxed to the forward free end portion of said thermostatic element 35 is a shaft 38 which extends forwardly and outwardly through the tubular extension 33. Aillxed to the outer end portion of said shaft 36, and so as to rotatably abut the outer extremity of said tubular extension 33, is a clutch-piece 3'! having an interrupted peripheral flange 38 to form spaced clutch-shoulders 39 and 48. Loosely pivoted on said shaft 38 is pendant lever arm 4| which extends between the clutch-shoulders 39 and 48 of said clutch-piece 31. Said lever arm 4| is retained'in assembled relation to 'said shaft 38 and clutch-piece 31 by a keeper member 42 and nut 43, the latter being engaged upon an outer externally threaded portion of said shaft. A split washer 44 is preferably interposed between said keeper member 42 and the pivoted end portion of said lever arm 4|. Amxed to said lever arm 4|,

intermediate its ends, is a clip 45 adapted to I embrace and carry a mercury tube contactor switch 46, which constitutes a motor control switch. The lower free extremity of said lever arm 4| is formed to provide a transverse latchtongue 41. ,Mounted on the panel 28 is a suitable stop means 48 which is engageable by said latchtongue 41 at proper times to limit movement of said lever arm 4|.

Mounted on the extension 33 of casing 39 is a bearing plate 49 having at its inner face a hearing The bearing plate 48 is retained in abutting relation to the outer face of the shoulder portion 38 of said casing 29 by means of a compression spring 5|, washer 52 and nut 53, the latter being engaged upon an externally threaded portion of said casing extension 33. Fulcrumed on said bearing boss 58 is a carrier plate 54, an upwardly extending portion of which is provided with a clip adapted to embrace and carry a mercury tube contactor switch 56, which constitutes a trip control switch. A downwardly extending arm 51 of said carrier plate 84 is provided with an outwardly, projecting ject outwardly from the panel 28, is a longitudinally reciprocable slide-bar 88, the same being disposed beneath the above described switch assemblies. Connected with said slide bar 68 to move therewith is anmpwardly extending arm 8| having a bifurcated free end portion 62 to operatively embrace and engage said crank pin 58. Aflixed to the slide-bar 68 is a downwardly yieldable spring-arm 63 having a notched latch-piece 64. which at proper times coacts with the latch-'- tongue 41 of the lever arm 4| by which the motor control switch is carried. Extending from said panel 28 is a depressor member or roller 65 which at proper times coacts with the springarm 63 to release the notched latch-piece 84 from engagement with the latch-tongue 41 of said lever arm 4|.

Suitably afllxed to said panel 28, below said slide-bar 68, is a switch and, oil flow control means, the same comprising a cylinder 66 having an internally threaded outer end portion 61 and a diametrically reduced chambered portion 68 forming an intermediate annular shoulder '69. Located within the chambered end portion 68 is an expansible and contractible bellows member 69, having an anchor flange 18 at its outer end seated upon said shoulder 69' and clamped thereto by a clamp ring I2 which is screwed into the threaded portion 61. The forward end of said cylinder is closed by a cap-piece I3 screwed into the end of the same. Ailixed to the closed free end of said bellows member 69 is a stem or rod 14 which projects outwardly through an opening 15 with which said cap-piece I3 is provided. A compression spring 16 which is interposed between the closed end of said bellows member 69 tracting movement of said bellows member 69 maybe engaged over said stern or rod 14 intermediate the cap-piece l3 and the free end of said bellows-member. Said cylinder 88 is provided with an inlet port 88 leading into the chambered portion '68 of cylinder 66. Connected with said inlet port 88 is an oil delivery pipe 8| leading from a motor driven oil pump (not shown), which operates to deliver oil from a source of supply to the oil-burner.

At its rearward end the cylinder 68 is provided with a reduced outlet end portion 82, to the end of which is connected a valve housing 83 having discharge passage 84 across which is disposed an apertured valve seat 85. Cooperative with said valve seat 85 is a valve member 86, the same hav ing a stem 81 slidably supportedthrough a chaneled bushing 88 connectedwith the inner end of said valve housing 83. A compression spring 89 arranged between said bushing 88 and valve member 88 yieldably holds the latter seated against said valve seat 85 in closed relation to the aperture or port thereof. The stem 81 is loosely coupled with the end of the bellows member 69 by means of a coupling thimble 98 which is secured to the latter, and through the end wall of which said stem 81 extends. The stem 81 has an enlarged head 9| engageable by said end wall of the coupling thimble 98. This coupling arrangement is such, that an initial contraction of the bellows member 69 can occur, before the 7g movement thereof is operative through the coupling connection, upon the valve stem 01 with consequent withdrawal of the valve member 86 from the valve seat 35 to open the aperture or port of the latter. Connected in communication with the outlet end of the discharge passage 04 is an oil delivery conduit or pipe 92, which extends into the interior of the mixing chamber or gun 5 into coupled communication with the rearward end of the burner pipe 6.

Movements of the slide-bar 60 are utilized to retract and advance the spark gap insulator means, and to this end a transverse shaft 93 is Journaled in and across the mixing chamber or gun 5. One end of the shaft 93 extends outwardly through the panel 26. Afllxed on the outwardly projecting end portion of the shaft 93 is a dependent lever arm 94 having a bifurcate free end portion. Flxedly secured upon the forward end portion of the slide-bar 60 is the base-block 95' of a forwardly projecting link 96 having a cross-pin 91 operatively engaged in the bifurcate end of said lever arm 94. Fixed on said shaft 93 is an upwardly extending lever arm '90 also.

' closed position. This is accomplished by means of a pivoted detent member I04, the dependent. arm I05 of which is provided with a perforation I06 in which isnormally engaged a tongue or lug I01 with which the free extremity of said carrier plate IN is provided. Said detent member I04 is spring urged against a stop pin I08 whereby the same is disposed in the described supporting relation to said carrier plate IOI. Said detent member I04 is provided with a horizontal tripper arm I09, which is engageable by means for tripping the detent member I04 to release the carrier plate IOI for gravitation to switch opening position. The tripping means comprises a cylinder IIO, the interior of which is divided by a partition I II to form an upper compartment and a lower compartment. The upper compartment is closed by a cap I I2 having a bore H3 in which a plunger H4 is vertically slidable. The upper compartment is supplied with a liquid content I I5 having a high coefficient of expansion when heated- The lower or inner end of said plunger H4 is exposed within the lower end of the bore II3 to engagement by said expansible liquid H5. The outwardly projecting upper end of said plunger II4 -underlies the tripper arm I09 of the detent member I04. Arranged within the lower compartment of said cylinder H0 is an electrical resistance coil II6.

. Means is provided for manually returning said carrier-plate I 0| to normal up-tilted position, the same comprising a pivoted lift lever III having a transverse stop pin 3 at one end to underlie the free end portion of said carrier Aflixed to said carrier plate IN is a schematically, in Fig. l, and are also more simply shown in Fig. 5. For convenience in connecting up the safety control devices, a suitable insulated binding-post support or base H9 is afl'ixed to the panel 26. Referring to Fig. 1 and to Fig. 5, the reference character I indicates the ingoing branch of a main service circuit leading from a suitable source of current supply, this input branch including one or more room thermostats I2I of any well known circuit make and break type adapted to be responsive to and actuated by fluctuations of temperature in the vicinity of their selected location. Said ingoing branch I20 of the main service circuit is connected to binding post A'of base II9. Leading from binding post A to one pole of the cut-out or safety switch I03 is a conductor I22, and leading from the other pole of said cut-out or safety switch I03 to binding post B of base H9 is a conductor I23.

Leading from binding post B to one pole of the motor control switch 46 is a conductor I24, and leading from the other pole of said motor control switch to binding post C of base H9 is a conductor I25. Leading from binding post C to one pole of a fuel pump actuating motor M is a conductor I26, and leading from the other pole of said motor M to binding post E of base I I9 is a conductor I2'I.

Leading away from binding post E is the outgoing branch I28 of the main service circuit.

It will be noted that the connections are such that the motor control switch 46 is in series with the safety or cut-out switch I03.

Also leading from binding post B to one pole ,of the trip control switch 56 is a conductor I29,

and leading from the other pole of said trip control switch 56 to one pole of the resistance coil H6 is a conductor I30. Leading from the other pole of resistance coil II6 to binding post E for connection with the outgoing branch I28 of the main service circuit is a conductor I3I. It will be noted that said safety or cut-out switch I03,

trip control switch 56 and resistance coil II6 are connected in series.

The binding post D of base H9 is connected electrically by coupling strip at with binding post 13. Leading from binding post D to one pole of the primary winding of a transformer T is a conductor I32, and leading from the other pole of said transformer primary winding to binding post E for connection with the outgoing branch I28 of the main branch circuit is a conductor I33. It will be noted that transformer T is connected in series with said safety or cut-out switch I03.

The current output of the secondary winding of transformer T is delivered to one of the ignition spark gap electrodes, as I5, by a conductor I34. which is suitably connected to the electrode tail-piece I which extends through the electrode holder I3. The tail-piece (not shown) of the other electrode I6 is suitably connected to ground. This may be done by leading therefrom r conductor I36 having an end electrically connected tothe wall of the mixing chamber or gun 5 (see Fig. 2). The tail-piece I35 of electrode I5, where passing through the chambered member 34 of electrode holder I3, is bent to by-pass around the casing 29 containing the thermostatic element 35, thus forming an int( rmediate secondary electrical gap, since the casing 29 is electrically grounded by reason of its connection and contact with said mixing chamber or gun 5.

When the oil burner apparatus stands idle, i e.

inactive, the cold and contracted thermostatic element 35 holds shaft 38 in an anti-clockwise turned direction, thus swinging lever arm H to the right (as shown in Fig. l) and thereby tipping the motor control switch 48 to a normal open position. During such idle condition of the burner apparatus, the fuel pump actuating motor M is stopped and consequently no oil is/delivered to cylinder 68 so that the bellows member 59 is expanded by the spring 19. Under such conditions the rod 14 is retracted and the slidebar 60, actuated by the bellows member 59 through said rod 14, stands likewise retracted, while at the same time the valve 88 is released to occupy its closed position under the urge of its spring 89. Retraction of the slide-bar 88 also turns the carrier plate 54, 'through the intermediate connections 8 I6258, so as to tip the trip control switch 55 to a normally closed position. Retraction of the slide-bar 50 also operates, through the intermediate lever arms 94 and 98, to advance the slide-plate 22 and the spark-gap insulator 2525 carried thereby, so that the latter is interposed between the electrode terminals I9 and (see Fig. 2). Under normal conditions, the safety or cut-out switch I93 is held, by the detent engaged carrier plate IIlI, tilted to closed condition. I

When current is delivered to the control means, as e. g. by the closing of the room thermostat I2I or other corresponding means, current immediately passes through the normally closed safety or cut-out switch I03 to the primary coil of transformer T, the circuit path being closed between ingoing branch I20 and outgoing branch I28 of the main service circuit through conductor I22, closed cut-out switch I03, conductors I 23, d and I32, transformer primary and conductor I33. The primary of transformer T being energized by the iiow of current therethrough, the induced current output of the transformer secondary is delivered through the conductor I34 and electrode tail-piece I35 to electrode I5. Owing to the interposition of the spark-gap insulator -28 between the terminals l9-28 of the electrodes I5-I6, the delivered energy cannot jump the ignition spark gap between said electrodes I 5I9 to ground, and consequently the electrical charge in the tails-piece I of the input electrode I5 is diverted so as to jump the secondary electrical gap between the same and said thermostat casing 29 to ground, and the resultant arcing immediately begins to heat up said casing 29. The heat thus induced in the interior of the chambered member 34 of electrode holder I3 and transmitted to the casing 29 is in turn communicated to the contained helical thermostatic element 35. Heating of thermostatic element 35 expands the same with a torsional effect which is transmitted to shaft 36, thereby turning the latter in clockwise direction and thus moving the clutch-piece 31 in like direction so that the clutch shoulder 39 of the latter pushes against the lever arm M to swing the same to the left and against the stop 48, thus tilting-the motor control switch to a closed position (see Fig. 3). As soon as the motor control switch closes, current is delivered to the fuel pump actuating motor M, the circuit path being closed between ingoing branch I20 and outgoing branch I28 of the main service circuit through conductor I22, closed cut-out switch I83, conductors I23, I24, closed motor control switch 45, conductors I25, I26, motor M and conductor I21.

Operation of the fuel pump, as actuated by the energized motor M, immediately delivers 011 through the delivery pipe II into the interior of v cylinder 88 behind the expanded bellows member 39. The pressure of the insoing oil exerts a contractive force upon the bellows member 83, which, in contracting, pushes outward the rod I4 and,

through its connections with the slide-bar 98, operates to advance the latter from right to left.

The forward movement of the slide-bar 89 operates, through the lever arms 94-98 to retract the slide-plate 22 and spark-gap insulator 25-29, thus withdrawing the latter from between the terminals of the electrodes I5-I8 so that arcing between the latter is initiated. Owing to the loose connection provided by the coupling between the bellows member 59 and the valve stem 81, the initial movement of said bellows member 89 is not effective to open the oil discharge valve 88, until the spark'gap insulator has been sufiiciently retracted to permit ignition sparking between the electrode terminals. By the time this occurs, however, the slack in the coupling connection is taken up and further contracting movement of the bellows member 69 is transmitted as a pull on the valve stem 81 so that the valve 85 is pulled open against the tension of its closing spring 89. The valve 85 being thus opened, the delivered oil is allowed to flow to the burner nozzle 1 through the conduit 92 and burner pipe 8. By this arrangement a lag in the operation of the valve 88 relative to the operative withdrawal of the sparkgap insulator is provided so that igniting sparks across the electrode terminal gap are assured somewhat in advance of the moment that oil actually reaches and is discharged from the burner nozzle 1. It will be understood that air is also delivered through the mixing chamber or gun in any usual way to supply and mix with the oil sufficient oxygen to assure good and thorough combustion, as well as to direct the flame into the interior of a fire-box served by the burner.

As the slide-bar 80 is advanced it carries with it the spring supported latch piece 54 the notch of which springs over the extremity 41 of the lever arm 4I thus holding the same in forwardly .swung position adapted to keep the motor control switch 46 in closed condition and uninfiuenced by anti-clockwise rotation of shaft 33 under the torsional contraction of the thermostatic element 35. This is desirable, for immediately the current output of the transformer can pass to ground by jumping the gap between the electrode terminals, the heating effect upon the electrode tail-piece I35 ceases, the temperature within the chambered portion 34 of electrode holder I3 drops, and the thermostatic element 35 cools and contracts to normal initial condition.

It will be understood that the normal delivery of oil by the motor actuated pump will produce and maintain within the cylinder 98, during continued operation of the burner, sufficient pressure to maintain the bellows member 59 contracted with consequent continued maintenance of the various actuated parts of the safety control means in the several conditions assumed thereby during the starting operations.

If, in connection with the starting operations as above described, ,or, for that matter, at any time during progress of operation of the burner, there should occur a failure of proper functioning of the motor M or of the pump driven thereby, or a failure, through exhaustion of supply or other cause, of proper delivery of oil to and through the cylinder 88, then the oil pressure effective to maintain the bellows member 69 contracted will cease, and thereupon the spring I6 will expand said bellows member. Any such expension of the bellows member 69 will retract the rod I4 and with it the slide-bar 50. The retraction of the slide-bar 60, under such circumstances, by reason of the latched connection thereof with the lever arm 4| through the medium of the spring supported notched latch-piece 64 will immediately swing the lever arm to the right, thereby tilting-the motor control switch 46 to normal open condition, thus interrupting delivery of current to motor lVL As the slide-bar 60 approaches the limit of retraction, whereby it is returned to normal initial position, the spring 63 is engaged by the depressor member or roller 65, which withdraws downwardly the notched latch-piece 64 so as to release thesame from engagement with the end 41 of lever arm 4| leaving the latter free to be again actuated by the thermostatic element 35 under proper conditions. The retraction of the slide-bar 60 also reversely moves the carrier plate 54 so that the trip control switch 50 is thereby returned to normal closed condition. As a consequence of the latter effect, current is delivered through the closed switch 56 to the resistance coil IIG, the circuit path being closed between the ingoing branch I20 and outgoing branch I28 of the main service circuit through conductor I22, closed cutout switch I03, conductors I23, I29, closed trip control switch 56, conductor I3, resistance coil H6 and conductor I3I. Continued delivery of current through resistance coil H6 generates heat which is communicated to the expansible liquid H5, causing the latter to expand. As the liquid II5 expands it presses upon the plunger II4, causing the same to rise so as to swing upwardly the arm I09 of the detent I04, so turning the latter on its pivot as to swing the dependent arm I05 thereof out of engagement with the lug I01 of the carrier plate IN. The carrier plate IOI, being no longer supported by the detent, drops downwardly thereby tilting the safety or cut-out switch I03 to open condition, thus interrupting service of current to the various switches and to the transformer T, and consequently completely preventing all further operation of the burner apparatus, until the safety or cut-out switch I03 is manually closed again. It is also to be noted that retraction of the slide-bar 60 also reversely operates the levers 94 and 98, thereby advancing the spark gap insulatormeans, to initial interposed relation to the electrode terminals I9 and 20,

It may also be pointed out that if, during operation of the burner apparatus, there should occur a break down of the transformer T which interrupts service of sparkingcurrent to and across the electrode terminals I9-20, the burner will nevertheless continue to operate so long as oil is delivered to the burner nozzle I, since combustion of the oil will continue, without necessity for electrical ignition, until supply to the nozzle 7 isdiscontinued. If, however, during such operation, the room thermostat I2I or other similar control interrupts the main service circuit, then the burner operation will be stopped and the safety control device will resume normal initial condition. If following this,- the room thermostat I2I or other like control again. closes the main service circuit, current will only, effectively flow through the trip control switch 56 and resistance coil H6, whereby the cut-out switch I03 will be tripped and opened, and consequently oil cannot be served to the burner nozzle I while the ignition system is defective or inoperative due to transformer break down'or other cause,

From the above description it will be understood that thepresent invention provides a very effective safety control means for oil burners, the same being responsive to break downs in any phase or part of the burner operating devices so as to interrupt and prevent improper or partial operation thereof, and consequentlythe safety control means is ,well calculated to prevent risk of explosions, puff-backs or fire from oil flooding, as well as dangerous short circuits or other accidents likely to involve serious injury to the apparatus or to the furnace served thereby.

-It will also be understood that many widely different embodiments of this invention could be, made without departing from the scope thereof; it is therefore intended that all matter contained in the above description or shown in the accompanying drawings shall be inte preted as illustrative and not in a limiting sense. 4

We claim:

1. In combination with an oil-burner apparatus having a burner nozzle, electrical ignition means including ignition spark-gap forming electrode devices, and an electric fuel pump actuating m0- tor; safety control means comprising a retractible ignition spark-gap insulator means, an expandible and contractibl'e thermostatic means having an electrically grounded portion disposed to form a secondary electrical gap in conjunction with the input electrode device, an initially open fuel pump motor control switch adapted to be closed by expansion 10f said thermostatic means, and pump supplied oil delivery means leading to the burner nozzle including means responsive to oil under pump pressure operative to retract said ignition spark-gap insulator means and to hold said motor control switch closed during normal flow of oil to said burner nozzle but to open said switch upon interruption of proper oil flow to the latter.

2. In combination with an oil-burner apparatus having a burner nozzle, electrical ignition means including ignition spark-gap forming electrode devices, and an electricfuel pump actuating motor; safety control means comprising a retractible ignition spark-gap insulator means, a torsionally expandible and contractible thermostatic means having an electrically groundedportion disposed to form a secondary electrical gap in conjunction with the input electrode device, an initially closed cut-out switch, a normally open fuel pump motor control switch in series with said cut-out switch, means actuated by expansion of said thermostatic means for closing said motor control switch, pump supplied oil delivery means leading to the burnernozzle including means responsive to oil under pressure opera-' tive to retract said ignition spark-gap insulator means and to hold said .motor control switch closed during normal flow of oil to said burner nozzle but to open said motor switch upon inter- 3. In safety control means for oil-burner appa-' ratus as defined in claim 2, manually operative 6 2,14s,ss o

means for restoring said cut-out switch to normal closed condition.

4. In combination -with an oil-burner apparatus having a burner nozzle, electrical ignition means including ignition spark-gap forming electrode devices, and an electric fuel pump actuating motor; safety control means comprising a retractible ignition spark-gap insulator means, a torsionally expandible and contractible thermostatic means having an electrically grounded portion disposed to form a secondary electrical gap in conjunction with the input electrode device, a normally closed cut-out switch, a transformer having its primary in series with said cut-out switch and its secondary connected to the input electrode device, an initially open iuel pump motor control switch also in series with said cut-out switch, means actuated by expansion of said thermostatic meansior closing said motor control switch, pump supplied oil delivery means leading to the burner nozzle including means responsive to oil under pressure operative to retract said ignition spark-gap insulator and to hold said motor control switch closed during normal flow of oil to said burner nozzle but to open said motor control switch upon interruption of proper oil flow to the Iatten'eIectro-mebhanical trip means adapted to open said cut-out switch, said latter means including an initially closed trip control switch, and means actuated by said oil pressure responsive means to open said trip control switch during normal flow oi oil to said burner nozzle but to close the same upon interruption of proper oil flow to the latter.

5. In a safety control means for oil-burner apparatus as deilned in claim 4, manually operative means for restoring said cut-out switch to normal closed condition.

6. In a safety control means for oil-burner apparatus as defined in claim 1, wher'ein said oil delivery means is provided with a valve initially closed against flow of oil to said burner nozzle, and a coupling connection between the oil pressure responsive means and said valve whereby the former may move the latter to open position.

7. In a safety control means for oil-burner apparatus as defined in claim 1 wherein said 011 delivery means is provided with a valve initially closed against ilow of oil to said burner nozzle, a coupling connection between the oil pressure responsive means and said valve whereby the tormer may move the latter to open position and means to provide play between cooperative parts of said connection whereby a lag in valve opening movement occurs to permit retraction of said ignition spark-gap insulator means prior to delivery or oil at the burner nozzle.

8. In combination with an oil burner apparatus having a burner nozzle and electrical ignition means including spark-gap forming electrode devices, a spark-gap insulator means movable into and out o! the gap between the electrode devices, said insulator means being of inverted T-shape in cross-section, whereby its vertical web is adapted to pass between said electrode devices while its horizontal webs are respectively adapted to pass beneath the respective terminals of the latter, and oil delivery means leading to said burner nozzle including means responsive to oil pressure operative to withdraw said insulator means from said spark-gap when oil flows through said delivery means at normal pressure and to insert the same into said spark-gap when oil pressure fails.

9. In combination with an oil burner apparatus having a burner nozzle, electrical ignition means including ignition spark-gap forming electrodes, a movable spark-gap insulator means, an electric fuel pump actuating motor, a fuel pump motor control switch, a pump supplied oil delivery means leading to the burner nozzle including spring retracted means responsive to oil pump pressure through said delivery means, and means cooperative with the pump motor control switch and spark-gap insulator means adapted to be operated by reaction of said oil pressure responsive means upon failure of oil pressure, thereby to substantially simultaneously interpose said insulator means between the spark-gap forming electrodes and open said pump motor control switch.

JOHN STAHL. CARL REED. HANS FISCHER.