US2076768A - Modulating oil burner system with intermittent ignition - Google Patents

Description

April 13, 1937. F. s. DENlsoN MODULATING OIL BURNER SYSTEM WITH INTERMITTENT IGNITION Filed Nov. ll, 1955 3 Sheets-Sheet l @N wo s wm WE 7 an ,M I m w D F- M, R .r ad

April 13, 1937. F. s. DENlsoN.

I MODULATING *OIL BURNER SYSTEM WITH-INTERMITTENT IGNITION Filed Nov. 1l, 1933 3 Sheets-Sheet 2 gnvmo AFREDERICK S. DEN I SON dbtoz M14 April 13, 1937. F, s. DENlsoN 2,076,768

MODULATING OIL BURNER SYSTEM WITH INTERMITTENT IGNITION Filed Nov. 11, 195s s sheets-sheet 's duca wut Patented Apr. 13, 1937 UNITED STATES ATENT OFFICE MODULATING OIL BURNER SYSTEM WITH NTERMITTENT IGNITION of Delaware Application November 11, 1933, Serial No. 697,687

15 Claims.

The present invention relates to the automatic control of fuel burning systems and particularlyr systems for burning fluid fuels such as the now well-known oil burning systems for domestic period to establish combustion upon the supplying of fuel after the supply of fuel has been previously terminated, the ignition means there- 0 after being deactivatedand remaining deactivated during the continued supplying of fuel.

In many fuel burning systems of the fluid type, it is difficult to establish combustion unless there is an initial relatively large flow of fuel.

: 5 A further object of the invention therefore, is the provision of a fuel burning system in which fuel is supplied in varying quantities and so arranged when no fuel is being supplied that upon the resumption of fuel feedA a sufficiently large 30 flow will initially be established as to insure proper ignition together with means for activating an ignition means upon such initial supplying of fuel.

Preferably the fuel is supplied in a large or :i5 infinite number of stages but it will be readily appreciable that a small number of stages such as two. in addition to the condition of no fuel supply, could beutilized if desired.

Other objects of the invention are the prom vision of a fuel burning system in which thefuel is supplied in a plurality of stages and the ignition means is activated each time the fuel supply is turned on from zero flow together with the usual safety features including a shutdown until manual intervention if combustion is not established and a recycle of the operations upon a power failure of long or-short duration and upon a flame failure after combustion has been successfully established.

Other objects of the invention will become apparent from the following description, accom- I panying drawings, and appended claims.

For a more complete understanding of the invention reference may be had to the following description and accompanying drawings, in which:

Fig. 1 is a diagrammatic showing of the preferred form of my improved automatically controlled fuel burning system, l

Fig. 2 is a side View, with parts broken away,y showing the details of the combustion responsive switching mechanism utilized in the stem of Fig. 1,

Fig. 3 is a front view of the combustion re- -10 sponsive switching mechanism of Fig. 2, and

Fig. 4 is a diagrammatic showing of a modified form of my improved automatically controlled fuel burning system.

Referring first to Fig. 1 of the drawings, a 15 uid fuel burning apparatus is herein illustrated as an oil burning mechanism comprising an oil supply pipe II having therein a shut-off valve I2 which is adapted to be opened upon energization of a cooperating electromagnetic winding 9 20 and closes upon deenergization of electromagnetic winding 9. The oil line II also is provided with a proportioning or modulating fuel iow controlling valve I3 which vincludes a stem I4 that is pivoted to a link I5 as shown at I6. 25 The link I5 is pivoted as indicated at I1. The oil burning mechanism further includes as electrical motor I8 which drives the shaft I9 of a blower 20. The casing of the blower is provided.with a ypair of arcuate inlet openings 2| 30 through which air enters and is then discharged from the discharge opening 22.` The inlet openings 2| cooperate with a shutter 23 which is pro- A vided with an operating member 24. Upon rotation of operating member 24, theshutter 23 35 is adapted to uncover thearcuate inlet openings 2l to vary the amount of air delivered by blower 20 through outlet 22. The link I5 and operating member 24 are positioned in accordance with changes in a. condition in a. manner which will now be described.

A condition responsive device is herein indicated as a potentiometer room thermostat which comprises a bimetallic element 25 having one of its ends secured and its other end being movable in accordance with changes in the temperature to which the bimetallic element 25 is subjected. The movable end of bimetallic element 25 operates a movable contact member 26 so as to move the same back and forth across a cooperating resistance 21 upon rise and fall in the temperature to which bimetallic element 25 responds. The movable contact member 26 and resistance 21 comprise a controlpotentiometer.

The control potentiometer is adapted to `con- 75 63 also operates a f trol the operation of a solenoid operated switching mechanism comprising a pair`of oppositely acting solenoids 23 and 23 which conjointly control the position of a plunger 33. Plunger 33 is connectedto a flexible switch arm 3| by means of a rod 32 and la light coiled spring 33. Flexible switch arm 3| carriesa pair of contacts 34 and 35 which cooperate with relatively stationary contacts 36 and 31. The solenoidvswitching lO'mechanism in turn controls a relay comprising a pair of oppositely acting relay coils 33 and 33 which condointly control the position of a'plunger 43. The plunger 43 is connected to a flexible relay switch arm 4| through a rod 42 and a light coiled -spring 43. Relay switch arm- 4| carries a pair of contacts 44 and 45 which coop- Y, erate with relatively stationary 'contacts 46 and 41. 's f The relay switching mechanism controls the operation of a motorized controlling means which includes a lower frame plate or base plate 43, an upper frame plate 43 andvtwo side plates 53 and 5|. The rotor 52 of an induction motor 53 is mounted upon a rotor shaft 54 that extends through side plate 53 and 4terminates between sideplates 53 and 5|. The extended end of rotor shaft 54 carries a pinion 55. In a similar manner, an induction motor, generally indicated at 56, mcm'des a. rotor 51 mounted upon a rotor shaft 53 which extends through side plate 5| and terminates between side plates 53 and 5|. This extended end of rotor shaft 53 carries a pinion 53. Pinions 55 and 53 mesh with the gears of two gear and pinion assemblies 63 which are mounted upon a shaft 6| that is journalled in side plates 53 and 5|. The pinlons of gear and pinion assemblies 63 mesh with a pair of gears 62 which are vlocated between side plates 53 and 5| and are secured to a main operating shaft 63 which extends' through side plates 53 and'5l. A main operating pinion 64 is also secured to main shaft 63 and cooperates with teeth formed in the lower portion of a vertically movable actuating rod 65.. Upon rotation of main operating shaft 63 in one direction, the actuating rod '65 is moved upwardly and upon reverse rotation of main operating shaft 63, actuating rod 65 is moved downwardly.

A bracket' 66 is secured to the upper side of frame plate 43 and pivotally receives one end of a lever 61 which extends across frame plate 43 and is received within an opening formed in the upper end of actuating rod 65. A roller 63 is mounted within theopening in actuating rod 65 55 and is adapted to engage lever 61 upon upward movement of actuating rod 65. A stop bracket 63, which is mounted upon the upper surface of frame plate 43, serves to limit the downwardv movement of the free end of lever 61 and is provided with a stop pin 13 which limits the upward movement of free end of lever 61. The outer free end of lever 61 is connected to actuating link |5 and to the operating member 24 of shutter 23 by a cable means 1|. @5 Main operating shaft 63 is provided with a limit'- switch actuator 12 which, uponl clockwise rotation of operating shaft 63 as 'viewed from lthe left, is adapted to engage a switch arm 13 and open a limit switch 14. Main operating 70 shaft 63 also carries a' second limit switch actuator 15 which, upon counter-clockwise rotation -of main operating shaft 63 as viewedjfrom the left, is'adapted to engage a switch arm -16 and open a limit switch 11. Main operating shaft balancing contact flnger13 which sweeps back and forth across a balancing vresistance 13 upon reverse rotations of main operating shaft 63. l

High or line voltage electrical power is supplied by line wires 33 and 3| and low voltage electrical power is supplied by the secondary 32 of a transformer 33 having a primary 34 which is connected to line wires 33 and 3|.

Balancing resistance 13 and control resistance 21 are connected in parallel by means of wires 35 and 36. These two resistances are likewise connected in parallel with solenoid windings 23 and 23 (in series) through protective ' resistances 31 and 33 by means of wires 33, 33, 3| and 32. The outer end of solenoid windings 23 and 23 are connecteddirectly across secondary `32 by means of wires 33, 34, 35 and 36. The junction of solenoid windings 23 and 23, movable contact member 26, and balancing contact finger 13 are interconnected by wires 31 and 33. The junction of relay windings 33 and 33 `is connected to flexible switch arm 3| through aA protective resistance 33 by means of a wire |33 and the outer ends of relay windings '33 and 33 are connected across the secondary 32 by wires 33, |3|, |32 and 35. Contact 36 is connected to a small number of turns of solenoid winding 23 by a wire |33 and the contact 311s similarly connected to a small number of turns of solenoid Winding 23 by a wire |34. Theremainlng circuit connections for the mechanism by which link |5 and operating member 24 are positioned in accordance with changes in the temperature to which bimetallic element 25 responds will be described during the description of theoperation of this particular modification of the invention.

Blower motor |3 and electromagnetic coil 3 are controlled by a main switch which is responsive to the same condition to which the control potentiometer responds. In this particular instance, the main switch comprises a pivoted flexible blade |35 to which is secured a second blade |36, the flexible blade |35 `being connected to movable contact member 26 by a link |31. Blade |35 cooperates with arelatively stationary contact |33 and vblade |36 cooperates with a `relatively stationary contact |33. The oil burner control system further includes a relay 3 which comprises a relay coil and a cooperating armature ||2 which operates switch varms ||3, ||4 and ||5.` Upon energization of relay coil and resulting attraction of armature H2, switch arms ||3, ||4 and ||5 are moved into engagement with contacts ||6,- |1 and ||3. Whenever relay coil is deenergized, the parts return by gravity to the position shown in Fig, 1-of the drawings wherein switch arms ||3, |14 and 5 are disengaged from contacts ||6, ||1 and ||3.

The oil burner contror system also includes `a thermal electric safety switch of usualconstruction which includes a heating element ||3 which, when energized for a predetermined length of time, is adapted to open a switch |23, the switch |23 thereafter remaining open until manually reset. This thermal electric safety is adapted to be ignited by a spark mechanismv comprising electrodes |2| and |22 which are connected to the high voltage secondary |23 of `a step upiignitlon transformer |24 having va line voltage primary |25. Line voltage electrical power is supplied to' this part of the control system by line wires |26 and |21 and low voltage electrical power is supplied thereto by the secondary '|28 of a step down transformer |29 having a line voltage primary |30 that is suitably connected to line wires |26 and |21.

The system also includes a combustion responsive switching mechanism which is shown in detail in Figs. 2 and 3. Referring to Figs. 2 and 3, a casing |3| is provided with a tubular lateral extension |32 that is provided with an opening |33. A collar |34 receives tubular extension |32 and is adapted to coverV varying amounts of opening`l33, depending upon the position of tubular extension |32. Collar |34 is provided with a flange |35 whichmay be secured to the stack of a furnace or boiler in a manner well known in the art. A helically coiled bimetallic element |36 has one of its ends secured to tubular extension |32 and its other end is secured to one end`of a torsion rod |31 which extends axially through helically coiled bimetallic element |36, tubular extension |32 and terminates within case |3l.

A collar k|38 is secured to torsion rod |31 just inside the case |3I. The torsion rod |31 next receives a friction washer |39 and then a switch carrier |40 followed by a coiled spring |4|, one end of which bears against switch carrier |40 and the other end of which is received in a spring retainer |42. A similar spring retainer |43 which faces in the opposite direction is next mounted upon torsion rod |31 and is spaced from spring 35 retainer |42 by means of a loosely fitting bushing |44. Spring retainer |43 receives one end of a coiled spring |45 and the other end of this coiled spring abuts a switch carrier |46. Another frictiony washer |41 is adjacent to the outer face of 40 switch carrier |46 and all of these parts are held in place on torsion rod |31 by a nut |48a which is threaded on the outerextremity of torsion rod |31. In this manner, the switch carriers |40 and |46 are frictionally connected to torsion rod |31 4.5 and while this frictional connection normally causes switch carriers |40 and |46 to rotate with torsion rod |31 they allow unrestricted movement of torsion rod |31 independently of switch carriers |46 and |41 if the motion of these switch 50 carriers is restrained, A stop pin |48 which is non-adjustably secured to the back of casing |3| lies in the path of movement `of both switch carriers |40 and |46 upon counter-clockwise rotation thereof as viewed in Fig. 3. This counterclockwise rotation is imparted to torsion rod I 31 upon a lowering in the temperature to which bimetallic element |36 responds, i. e., the temperature of combustion.

An adjustable stop |49 lies only in the path of movement of switch carrier .|40 so as to limit-its movement when rotating in a clockwise direction as the result of an increase in the temperature to which bimetallic element |36 responds. A similar stop member which is also adjustable in casing |3| is indicated at |50 and lies only in the path of movementof switch carrier |46 and limits its clockwise rotation upon an increase in the tem-f perature to which bimetallic element |36 responds. Switch carrier |46 supports a. mercury switch clip |5| which receives a mercury switch |52 that is provided with the usual electrodes I 53 and a globule of mercury |54, the arrangement being such that the circuit through mercury.

switch |52 is opened when switch carrier |46 is in engagement with stop |48. Switch carrier |40 is provided with a pair of mercury switch clips |55 and |56, the former of which is mounted above torsion shaft 31 and the latter of which is mounted below torsion shaft |31. Mercury switch clip I 55 carries a mercury switch 51 which is of slightly bent or humped formation as will be seen from an inspection of Fig, 3. This mercury switch |51 is provided with the usual electrodes |58 and a globule of mercuryv |59, the arrangement being such that the circuit through mercury switch |51 is closed when switch carrier |40 is engaged with stop |48. The lower mercury switch clip 56 supports a mercury switch |60,

`having electrodes |6| and a globule of mercury |62 and this switch is arranged so as to be in closed circuit position when switch carrier |40 is engaged with stop |48. Mercury switch |51 is the cold switch of the combustion responsive switching mechanism, mercury switch |52 is the hot switch thereof, and mercuryswitch |60 is th ignition switch.

Upon a decrease in the temperature to which bimetallic element |36 responds, the various parts of the combustion responsive switching mechanism move to the position shown in Figs. 2 and 3 and continued decrease in temperature thereafter is accompanied by continued rotation of torsion shaft 31 but the various mercury switches and switch carriers are restrained from further movement by reason of stop |48. Upon an increase in temperature to which bimetallic element |36 responds both switch carriers 40 and |46 immediately begin clockwise rotation as viewed in Fig. 3. This clockwise rotation of these switch carriers first causes the mercury |54 and |62 in mercury switches |52 and |60 to roll from the left hand ends thereof to the right hand ends thereof whereupon the circuit through mercury switch` |52 is closed and the circuit through mercury switch |60 is opened. The mercury |56 in mercury switch |51 remains in the left hand end thereof at this time due to the curved or humped formation of mercury switch |51. However, upon further temperature increase and resulting further clockwise rotation of the switch carriers 40 and |46, the mercury |59 in mercury switch |51 rolls over the hump and moves to the right hand end of mercury switch |51 to break the circuit therethrough. Upon further temperature increase, mercury switch carrier |46 engages v stop |50 whereupon a further clockwise` movement of mercury switch carrier |46 and mercury switch |52 is interrupted. However, further temperature increase results in continued clockwise movement of switch carrier |40 until the same engages its adjustable stop |49. The parts are now in their hot position and it will be noted that the circuit through mercury switch |52 was closed prior to the opening of the circuit through 1 mercury switch |51. Upon'a decrease in the tem- Perature to which bimetallic element |36 responds, the switch carriers 40 and |46 will immediately begin to rotate in a counter-clockwise direction. After a relatively small amount of such counter-clockwise rotation the mercury |54 in mercury switch |52 -moves to the left hand end thereof to break the circuit through mercury switch |52. A relatively larger movement of switch carrier |40 in a counter-clockwise direction will be necessary to cause the mercury, |62 in mercury switch |60 to move to the left hand end thereof inasmuch as the stop |49 formerly allowed a larger clockwise'rotation of switchfcarrier |40. The mercury |59 in mercury switch 51 will remain in its right handr end thereof substantially until switch carrier |40 is again moved into engagement with stop |46 by reason of the curved or humped formation of mercury switch |51. It will be noted that during cooling of bimetallic element |36, the circuit through mercury switch |52 is opened relatively quickly but thatv there is a long delay before the circuit through mercury switch |51 is reclosed. The .circuit through mercury switch |60 is closed after opening of the circuit through mercury switch |52 but prior to the closing of the circuit through mercury switch |51. The various devices and elements of which the system of Fig. 1 is composed having beenmentioned will be specilically traced during the description of the operation.

'Operation of the system of Fig. 1

With the parts in the position shown in Fig. 1, the room temperature is at its highest desired point as indicated by the fact that movable contact member 26 is engaging control resistance 21 substantially at the right hand end thereof. At this temperature, blade |05 has just moved from engagement with contact |08. Electromagnetic coil 9 is therefore deenergizedvas is blower vmotor I8. Flow controlling valve I3 is closed and the shutter 23 completely covers the inlet openings 2| in blower casing 20. Balancing contact linger 19 i's engaging balancing resistance 19 substantially at its left hand end. Solenoid winding 28 is substantially short-circuited bynthe following circuit; one end of solenoid winding 2 6, wire 92,

protective resistance 88, wire 9|, wire 86; balancing contact finger 18, wire 98, and wire 91 to the other end of solenoid winding 28. Similarly solenoid winding 29 is substantially shortcircuited bythe following circuit: one end of vsolenoid winding 29. wire 90, protective resistance 61, wire 89, movable contact member 26, bimetallic element 25, and wire 91- to the other end of solenoid winding 29. Solenoid windings 26 and 45.29 are thus substantially equally 'energized and plunger 30v is in a central position wherein contacts 34 and 35 are disengaged from contacts 36 and 31. Relay windings`38 and 39 are therefore equally energized so that plunger 40 is in a central position wherein contacts 44 and 45 are disengaged from contacts 46 and 41. Field windings |65 and |61 of motors 53 and 56 respectively are both deenergized and limit switch 11'is'open. Inasmuch as no heat isbeing furnished to the space to be heated, the temperature thereof will soon begin to fall and movable contact member 26"will therefore begin to move along control resistance 21 towards the left end thereof. Such movement of movable contact member 26 will change the current iiows through solenoid windings 28 and 29 in such manner that solenoidwinding 29 becomes the more highly energizedwhereby plunger 30 will be moved to the right to bring contact 34 into engagement with contact 36.

Such engagement of contact 34 with contact 36v bringsprotective resistance 99 and a small number of turns of solenoid winding 29 in parallel with relay winding 39 so thatrelay winding 39 is substantially short circuited whereupon relay winding 39 becomesconsiderably more highly energized than relay winding 39 and plunger 40 is moved to the right. Movement of plunger 40 to the right brings contact 44 into engagement with contactA 46 whereupon an energizing circuit for field winding |65 is established as follows: line 6|, wire |68, relay switch arm 4|, contact 44, contact 46, wire |69, limit switch 14, wire |10, ileld winding |65, wire |1|, and wire |12 to line 30.L

Energization of fleld winding |65 causes motor rotor. 52 to rotate in such a direction that main operating shaft 63 is rotated in a clockwise direction as viewed from the left in Fig. 1. It should be noted that the circuit through protective resistance 99 and the small number of turns of solenoid 29 biases plunger 30 additionally to the right to increase the contact pressure between contacts 34 and 36. This clockwise rotation of main operating shaft 63 moves balancing contact finger 19 along balancing resistance 19 towards the right end thereof to again change the respective energlzations of solenoid coils 26 and 26 in sucia manner that they become substantially equally energized whereupon plunger 30 is returned to its vcentral positionl and contact 34 is separated from` contact 36. This separation of contacts 34 and `36 opens the circuit through protective resistance 99 and the small number of a small upward movement of actuating rod 65' whereupon the extreme left end of lever 61 moves upwardly to slightly open oil proportioning valve I3 and to move shutter 23 in such manner as to uncover a small part of inlet openings 2|. Each increment of temperature fall in the spaceto be heated-l is accompanied by a further movement of movable contact member 26 along control resistance 21 toward the left hand end thereof and the above described action will be repeatedso that oil proportloning valve AI3 is gradually moved toward its full open position and the shutter 23 gradually uncovers more and more of inlet openings 2I in blowerV casing 20. During this time however, no oil is fed to the oil burning mechanism inasmuch as electromagnetic coil 9 isfdeenergized and shut-off valve |2 is therefore closed. When movable contact member 26 reaches the left hand end of control resistance 21, .solenoid winding 26 is substantially short-circuited by wire 92, protective resistance 66, wire 9|, movable contact member 26, bimetallic element 25 and wire 91. lMain operating shaft 63 is then operated until limit switch 14 is opened. At this time, .balancing contact ilnger 16 has been moved lto the extreme right hand endof balancing resistance 19 whereby solenoid winding 26 is substantially Ilo..

short-circuid by wire 60, protective resistance v 91, wire 89, wire 65, balancing contact finger 16, wire 98 and wire 91. Plunger 40 therefore returns to its central position. At this time oil proportioning valve I3 will be completely opened l and shutter 23 will have uncovered enough of inlet openings 2| in blower casing 20v to allow the Engagement of blade |66 with contact |66 esg l' tablishes an energizing circuit for relay coil III, 475

.it being remembered ythat bladev |05'has in CII l energizing circuit for relay coil traverses cold switch |51 so that this circuit cannot be completed unless the temperature of combustion to which bimetallic element |36 responds has dropped a predetermined amount depending upon l the adjustment of stop |49. Energization of relay coil H attracts armature H2 which in turn moves switch arms H3, H4 and H5 into engagement-.with contacts H6, H1, and H8. Engagement of switch arm H4 with contact H1 Z0 establishes a holding circuit for relay coil H! which is independent of blade |06 and contact |09. This holding circuit is as follows: secondary |28, wire |13, saty switch |20, wire |14, contact |08, blade |05, wire |82, contact H1, 25 switch arm H4, wire |83, wire |16, wire |11, cold switch |51, wire |18, heating element H9, wire |19, wire |80, relay coil and wire |8| to the other side of secondary |28. Engagement of switch arm H3 with contact H6 establishes i0 energizing circuits for blower motor |8, electromagnetic winding 9, and the line voltage primary |25 of ignition transformer |24. The energizing cil cuit for blower motor |8 is as follows: line |21, wire |84, contact H6, switch arm H3, wire |85, 55 wire |86, wire |81, blowerA motor |8, and wire |88 to line |26. The energizing circuit for electromagnetic winding 9 is as follows: line 21, wire |84, contact H6, switch arm H3, wire |85, wire |86, wire |89, electromagnetic winding 9 and l0 wire |90 to line |26. The circuit for the line voltage primary |25 of ignition transformer |24 is as follows: lineA |21, wire |84, contact H6, switch arm |3, wire |85, wire |9|, ignition switch |60, wire |92, line voltage primary |25 of trans- |5 former |24, and wire |93 to line |26. vThe high tension secondary |23 of ignition transformer |24 is connected to electrodes |2| and |22 by wires |94 and |95.

Energization of electromagnetic winding 8 i0 opens shut-olf valveb |2. Inasmuch'as oil proportioning valve 3 is in wide open position a full supply of oil will be furnished to the oil burning mechanism. Energization of blower motor |8 operates the blower 20, it being remem- 5 bered that shutter 23 has been operated to a.l

bustible mixture with the oil delivered from oill l0 supply line H. 'I'his combustible mixture will be ignited by the spark created by the electrodesv |2| and 22 if the system is functioning properly.

If combustion is not established, the combustion responsive switching mechanism remains in the position shown in the drawings with the result that heating element H9 remains energized and, after a predetermined time, safety switch |20 will open rendering the oil burning mechanism completely inoperative by deenergizing re- 0 lay coil |H. 'I'he oil burning mechanism will then remain inoperative until safety switch |20 is manuallyreset.

fAssuming however that combustion is properly established, the temperature of combustion will increase and hot switch |52 will rst close as Vmoves to the left.

previously described. Closure of hot switch |52 establishes awmaintaining circuit for relay coll I which does not traverse heating element H9, cold switch |51, or blade |06 and contact |09. This maintaining circuit for relay coil |H is as follows: secondary |28, wire |13, safety switch |20, wire |14, contact |08, blade |05, wire |82,

contact H1, switch arm H4, wire |83, wire |16, wire. |96, hot switch |52, wire |91, switch arm H5, contact H8, wire |98, wire |80, relay coil and wire |8| to the other side of secondary |28. It will be noted that this maintaining circuit shunts the circuit through heating element H9 so as to operatively deenergize the same and render it incapable of supplying further heat to safety switch |20 whereby the safety switch |20 will not be operated to open circuit position to shut down the oil burning mechanism. As the combustion temperature continues to increase, ignition switch |60 will open to deenergize the ignition transformer |24 and thereafter cold switch |51 will open to interrupt both the original energizing circuit for relay coil |H and the previously described holding circuit therefor. The circuit through heating element H9 is now completely broken. I

The oil burning mechanism is now operating at full capacity to supply maximum heat. As a result, the room temperature will begin to rise and movable contact member 26 will start moving along control resistance 21 towards the right hand end thereof. Initial movement of movable contact member 26 in this direction will separate blade |06 from contact |09, thereby interrupting the original energizing circuit for relay coil H but the oil burning mechanism remains in operation by reason of the previously described maintaining circuit. This initial movement of movable contact member 26 along control resistance 21 to the right unbalances the energization of solenoid coils 28 and 29 opposite to the manner heretofore described so that solenoid coil 28 becomes the more highly energized and plunger 30 moves to the left thereby bringing contact 35 into engagement with contact 31. Such engagement of contacts 35 and 31 completes a circuit through protective resistance 99 and a small number of turns of solenoid winding 28, this circuit being in parallel with `relay winding 38 whereupon relay winding 39 becomes more highly energized than relay winding 38 and plunger 40 This parallel circuit which traverses the small number of turns of solenoid winding 28 pulls plunger 30 more strongly towards the left to increase the contact pressure Y between contacts 35 and 31. Movement of plunger 40 to the left brings contact 45 into engagement with contact 41 to complete an energizing circuit for eld winding |61, it being remembered that limit switch 11 moved to closed position upon initial clockwise rotation of main operating shaft 63 during decrease in the space temperature. This energizing circuit for eld winding |61 is as follows: line 8|, wire |68, relay' switch arm 4|; contact 45, contact -41, wire |99, limit switch 11, wire 200, field winding |61, wire 20|, and wire |12, to line 80.

Energization of field winding |61 causes ro tation of motor rotor 51 in such direction that operating shaft 63 moves in counterclockwise direction as viewed from the left in Fig. 1. Initial counterclockwise rotation 4of main operating shaft' 63 allows limit switch 14 to close'and also begins moving balancing contact linger 1l along balancing resistance 19 toward the lett end 10 become equal and plunger 40 returns to its central position moving contact 45 from engagement with contact 41. In this manner, the circuit for field winding |61 is `interrupted and further. rotation of main operating shaft 63 ceases. This. rotation of main operating shaft 63 in counterclockwise direction has slightly lowered actuating rod 65 so that lever 61 moves downwardly and partially closes oil modulating valve I3 and allows less air to flow through in- A let openings 2| into the blower 20. In this manner, as the space temperature increases, 'the supply of oil and air to the oil burning mechanism isdecreased. The spacetemperature may now fluctuate between its desired limits and will be accompanied by a corresponding uctuationvin ,the amount of heat delivered by the oil burning mechanism. During normal weather conditions, when the weather is not too mild, the room temperature should level off at some point with- ,30 in its desired range so that the oil burning mechanism operates continuously at just vsufficient capacity to maintain the space temperature hconstant or at least within the permissible limit of fluctuation.

A decrease in the amount of oil supplied to the burner may result in a slight decrease inV vthe temperature of combustion with the result that switchcarrier |46 moves a small amount in a countercloekwise direction as viewed in Fig. 0 3. However, it will be noted that this` switch carrier |46 must move considerably from stop |50 before the circuit through hoty switch |52 is'opened and, by proper adjustment of stop |50, the lowering of the temperature of combustion 45 by reason of a decrease in the amount ofv o`il and air supplied to the oil burning mechanism will not be sufficient to cause hot switch |52 to open and thereby shut down the oil burning mechanism. If the space temperature should con- 50 tinue to rise so that movable contact member is again brought to the extreme right end of control resistance 21 as shown in Fig.1 of the drawings, the blade |05- will be moved from engagement with contact |06 4and the maintain- `|55 ing circuit for re y coil will be interrupted.

The oil burning mechanism will therefore be rendered inoperative, electromagnetic coil 9 being deenergized and blower motor |8A also being deenergized. 'I'he oil burning mechanism will thereafter only be placed in operation when the -roorn temperature has returned to' its lowest desired limit so as to again bring blade |06 into engagement with contact |09 and when the temperature of combustion has dropped sumciently to cause cold switch |51 to again move to closed circuit position. If there should be a failure of electrical power at any tim'ewhile the oil burningV mechanism is in operation, the system will immediately shut down and cannot again be placed into operation -until the .temperature of combustion has lowered sumciently to close the circuit through cold switch 51 and if, atthe time of such power failure,4

n blade |06 is disengaged from contact |09, the Aoil burning mechanism will remain out of operation until such time as the cold switch |51 has returned to closed position by lowering of the temperature of combustion and the space temperature has lowered'sumciently to bring blade |06 again into engagementwith contact |09. When these conditions are satisfied, the oil burning mechanism control system will recycleand again attempt to establish combustion. Similarly, if there should be a failure of ame during operation of the oil burning mechanism, the system will be rendered inoperative as soon as the temperature of combustion lowers sufiiciently to open the circuit through hot switch |52. Again, the system remain-s inoperative until cold switch |51 recloses and until blade |06 again engages contact |09. At 'such time, the oil burning mechanism will recycle in an attempt to reestablish combustion.

From the foregoing description of the operation of the-system of Fig. 1, it will be seen that the present invention provides a system for burning fluid fuel wherein the demand for heat must be such as to require the delivery of suillcient fuel for initially establishing combustion without dif- `iiculty before anyA fuel whatsoever can be supplied."-f"When this amount of fuel is supplied, ignition means are rendered operative only long enough to ignite the fuel and are thereafter rendered inoperative untilthe next attempt to establish combustion. Combustion having been established, the flow of fuel is modulated:l or proportioned in accordance with the"demand until some predetermined minimum demand is reached whereupon the fuel burning mechanism is again shut down and cannot be -estarted until the above mentioned relatively la ge demand is again required. While the system ofl Fig. 1 has been described in connection with the system wherein no fuel is supplied initlally untilthere is a demand for full heat delivery capacity, it will readily be appreciated that it is only necessary for the demandto be such as to supply sufficient fuel for proper ignition. This maximum demand for initially feeding fuel and the minimum demand at which fuel feeding ceases is determined by the making and breaking of blades |05 and |06 with contacts |00 and |00 in respect to the movements of movable member 26 which is hereinlshown as being controlled by space temperatures. It will also be'noted that in the system of Fig. 1, the ow of fuel is controlled by the cooperation of two valves, one of which is a shut-01T valve that either permits no fuel flow or permits maximum fuel flow, the other valve being a modulating or proportioning valve which is continuously positioned in accordance with demands for heat but fuel can only flow, even though the proportioning valve isA opened, at suchptimes as the shut-off valve is opened. I'he system. of Fig. 1 additionally provides all of the usual safety features such as a shut-down until `manual^ intervention upon a failure of combustion initially to be established and recycling of the Vcontrols after a stand-by period upon theoccurrence `of either a flame failure or a power failure and if combustion, is not successfully established uponsuch recycling of the system, the system is shut. down until manual Fig. 4, the proportioning valve I3 and shutter 23 are again cohstantly changed in position in accordance with uctuations in the space temperature through a mechanism which is mechanically the same as the mechanism of Fig. 1 but which is rearranged slightly as to its electric connections. It will be noted that the secondary 82 of transformer 83 is connected to the outer ends of solenoid windings 28 and 29 by wires 2I6, 2|I, 2|2, 2I3, 2I4 and 2I5. Contact 36 is connected to a small electromagnetic winding 2I6 by a wire 2I1 and contact 31 is connected to a small electromagnetic winding 2| 8 by a wire 2|9. Field windings |65 and |61 in the .system of Fig. 4 are low voltage and replace the relay windings 38 and 39 of the system of Fig. 1. It will be noted that field windings |65 and |61 are connected in series across secondary 82 by wires 2I6, 226, 22|, 222, 223, 224, 225 and 2I5. This series circuit includes limit switches 14 and 11. Flexible switch arm 3| is connected by a wire 226 to the junction of wires 222 and 223 and is thereby connected to one end of each of the eld windings |65 and |61.

The control system for blower motor I8 and electromagnetic winding 9 of valve I2 in Fig. 4 is controlled by switching mechanism operated by lever 61 rather than by a switching mechanism directly controlled by the movements of thermostatic` element 25 as in Fig. 1. Lever 61 supports a clip 221 which carries a mercury switch 228 that may be termed the holding switch and likewise supports a clip 229 which carries a bent or curved switch 236 which may be termed a starting switch. The system of Fig. 4 includes a direct current relay coil 23| which upon energization attracts an armature 232. Armature 232 controls switch arms 233 and 234 which re-l coil 231 which, upon energization, attracts an4 armature 238 that in turn moves a switch arm 239 into engagement with 'a contact 24|, the

' switch arm 239 thereafter disengaging a contact 246. Such movement of armature 238also moves switch arms 242 and 243 from engagement with contacts 244 and 245. An ignition means is indicated at 246.

In the system of Fig. 4, the safety mechanism does not inc de a'combustion temperature responsive device ut instead includes means which respond directly to the actual presence or absence of flame. This means includes an electrode 241 which is placed in such manner as to be impinged by the :dame produced by the oil burning mechanism and also includes a grid flow tube 248 which is provided with a grid 249, an .anode 256, and a cathode 25|. Power is supplied to the control system for the oil burning mechanism by a transformer 252 which has aline voltage primary 253 connected to line wires |26 and |21. The transformer 252 is provided with a high voltage secondary 254 which supplies approximately 440 volts. The transformer 252 is also provided with a tapped low voltage secondary comprising portions 255 and 256 which are so connected that their polarities are additiveV and total about 20 volts, each portion furnishing approximately 10 volts. A copper oxide rectifier indicated diagrammatically at 2l1 hasecurent paths 26|, 269,

266and 26|. A condenser 262 is utilized for purposes to be hereinafter described.

The remaining circuit connections will be com-- pletely described during the detailed description of the operation of the system of Fig. 4.

Operation of the-system of Fig. 4

The system of Fig. 4 is shown with the parts inthe position they assume when the space temperature is at its upper limit so that the oil burning mechanism is inoperative. As the room temperature falls, movable contact member 26 will begin moving along control resistance 21 towards the left end thereof and thereby unbalance the current ows through solenoid coils 28 and 29 so that solenoid coil 29 becomes the more highly'energized whereupon plunger 36 will move to the right and bring contact 34 into engagement with contact 36. Closing of contacts 34 and 36 places the small electromagnetic winding 2I6 in series with field winding |65 whereupon field winding |65 and small electromagnetic coil I|6 are energized as follows: secondary 82, wire 2|5, wire 225, limit switch 14, wire 224, field Winding |65, wire 223, wire 226, exible switch arm 3|, Contact 34, contact 36, wire 2I1, small electromagnetic coil 2I6, wire 2|| and wire 2| 6 to the other side of secondary 28. Energization of small electromagnetic coil 2I6 increases the pull on plunger 36 to increase the contact pressure between contacts 34 and 36. Energization of field winding |65 causes rotation of rotor 52 in such direction that main operating shaft 63 is rotated in a clockwise direction as viewed from the left in Fig. 4.

Initial clockwise rotation of main operating shaft 63 allows limit switch 11 to close whereupon field winding I 61 is placed in parallel with the small electric winding 2| 6. Field winding |65 is thereupon traversed by thev full current ilow which traverses field winding |61 and small electromagnetic coil 2I6 so that although rotor 51 tends to rotate main operating shaft 63 in a counter-clockwise direction, the torque exerted by rotor 52 to rotate main operating shaft 63 in a clockwise direction will be the greater and the shaft 63 will rotate in a clockwise direction. Balancingl contact nger 18 is thereby moved along balancing resistance 19 toward the right end thereof and will reach a point wherein the energi'zation of solenoid coil 28 has been increased suiciently in respect to solenoid coil 29 to return plunger 36 to its middle position whereupon contact 34 disengages contact 36. Field windings |65 and I 61 are thereby connected in series directly across secondary 82 by the following circuit: secondary 82, wire 2| 5. wire 225. limit switch 14, wire 224, eld winding |65, wire 223, wire 222, eld winding |61, wire 22|, limit switch 11, wire 226, wire 2| 6' to the other side of secondary 82. Field windings |66 and |61 are therefore equally energized with the result that main operating shaft 63 ceases rotating and remains stationary. 'I'he rotation of main operating shaft 63 which has just taken place caused pinion 64 to raise actuating rod 65 and lift the extreme left end of lever 61 whereby proportioning oil valve I3 opens slightly, shutter 23 is moved to uncover a small portion of inlet openings 2| in the casing of blower 26, and switches 228 and 236 are moved slightly in closing direction.

As the temperature in the space continues to fall, lever 61 will be raised higher and higher whereby mercury switch 236, the holding switch,

will rst close and thereafter proportioning oil.-

, 40 switch arm 242 and contact 244.

oil valve I3 to full open position, the shutter 23 will be moved to a position uncovering the cor- 5 rect amount of inlet openings 2| and starting switch 228 will be moved to closed position. Also, at this time, or upon further slight movement limit switch 14 will be opened by limit switch actuator 12 so as to prevent further energization of l0 eld lwinding |65. Closure of starting switch 228 establishes an energizing circuit for relay coil 23|. and electric heating element ||9 of safety switch during one halfv cycle of the alternating current` as follows: secondary 256, secondary l5 255, wire 2 65, holding switch 236, wire 266, starting switch 228, wire 261, contact 244, switch arm 242, wire 268, wire 269, safety switch |26, wire 216, current path 258 of rectifier 251, wire 21|, relay coil 23|, wire 212, current path 26| of recc0 tifier 251, wire 213, switch arm 239, contact 246, wire |14, heating element ||9 and wire 215 to the other side of secondary 256. During the other half cycle of alternating current supplied by secondaries 255 and 256, the circuit for relay 2523i and heating element Ils will be as follows;

secondary 255, secondary 256, wire 215, heating element II9, wire 214, contact 246, switch arm 239, wire 213, current path 259 of rectifier 251, wire 21|, relay coil 23|, wire 212, current path 266 of rectifier 251, wire 216, safety switch |26, wire 2 69, wire 268, switch arm 242, contact 244, wire 261, starting switch 2 28, wire 266, holding ,switch 236, and wire 265 to the other side of secondary 255.' Energization of relay coil 23| moves switch arms- 233 and 234 into engagement with contacts 235 and 236. Engagement of switch arm 234 with contact 236 establishes a holding circuit for relay coil 23| and heating element I9 which is independent of This holding circuit during one half cycle of alternating current delivered by secondaries 255 and 256 is as follows: secondary 256, secondary 255,l wire l265, holding switch 236, wire 216, contact. 236, switch 45,arm 234, .wire 211, wire 269, safety switch |26.

wire 216, current. path 258 of rectier 251, wire 21|, relay coil 23|, wire 212, current path 26| of rectifier 251, wire 213, s'witch arm 239,V contact 246. wire 214, heating element ||9 and wire 215 v to the other side of secondary 256. During the other half cycle this holding circuit is as follows: secondary 255, secondary 256, wire 215, heating element |l9. wire 214, contact 246,'switch' arm 239, wire-213, current path 259 of rectifier 251,'`

wire 21|. relay coil 23|, wire 212, current path 266, rectifier 251, wire 216, safety switch |26, wire 269, wire 211, switch arm 234, contact 236. wireV 216, holding switch 236 and wire 265 to the other side of secondary 255.

60. Movement of switcharm 23,3 into engagement with contact 235 establishes energizingvcircuits for blower motor I8, electromagnetic winding 9 and ignition means 246. The blower motor circuit is as follows: line |26, wire 218, contact 235, switch arm 233, wire 219, wire 286, blower m'otor I8, wire 28| and wire 282 to line |21. 'I'he energizing circuit .for electromagnetic winding 9 is as follows: wire |26, wire 218, contact 235, swi h arm 233, wire 219, wire 286, wire 263, electro netic c0119 and wire284, to line |21. The energizingcircuit for ignition means 246 is as follows:

.line |26, wire 218, contact 235, switch arm 233,

wire 219, wire 285, `switch arm 243, contact 245, wire 286, ignition means 246, wire281, andwire zu to line-|21.

A fun supply of 0111s therefore supplied to the.

oil burner since proportioning oil valve |3`has been moved to full open position by lever 61 and shut-oil' valve I2 has been opened by energization of electromagnetic coil 9. The proper amount of air is drawn in through inlet openings '2| by reason of operation of blower motor I8 and the ignition means should ignite the mixture thus delivered. If combustion should not take place, heating element ||9 remains energized and at a rectified direct current circuit through relay coil 231 as follows: secondaryv 254, wire 29|, wire 292, relay coil 231,wire 293, anode 256. cathode 25| and wire 294 to the other side of secondary 254. Condenser 262 is connected in parallel with relay 231- by meansl of wires 295 and 296 and serves to smooth out the half-way rectified current supplied -by grid glow tube 246 to relay coil 231. y

Energization of relay coil 231 attracts armature 238 whereupon switch arm 243 moves fromy engagement with contact 245 to deenergize ignition means 249. Switch arm 242 likewise disengages contact 2,44 so that the original energizing cir- -cuit forrelay coil 23| is interrupted. Switch arm 239 is moved into engagement with contact 24| and thereafter disengages contact 24,6.- Engagement of switch arm .239 with contact 24| establishes a maintaining circuit for relay coil 23| which only utilizes the secondary 255 and Isindependent of heating element ||9. During half the cycle of alternations, this maintaining circuit for relay coil 23| is as follows: secondary 255,

The grid. glow ltube thereupon allows current flow from the anode 256 to the cathode 25| and establishes the end of a. predetermined time period, safety wire 265, holding switch 236, wire 216, contact 236, switch arm 234, wire 269, safety switch |26, wire 216, current path 258 of rectifier 251, wire 21|, relay coil '23|, wire .212, current path 26| of rectiflerj251, wire 213, switch'armA 239, contact 24| and wire 291 tothe other side of secondary 255. During the other half cycle this maintaining circuit for relay coil 23| is as follows: Secondary 255, wire 291, contact 24|, switch arm 239, wire 213, conducting path 259 of rectifier 25.1, wire 21| Vrelaycoil 23|, wire' 212, conductingpath 266 'of rectier 251, wire 216, safety switch |29, wire 269, Wire 211, switch arm 234, contact 236, wire l216, holding switch 236 and wire 265 to the other side of secondary 255.

The oil burning apparatus is now operating at full capacity and as the result the temperature of the space being heated will slowly begin to rise As the room temperature rises, movable contactmember 26 will start travelingA along control` re sistance 21 from the left hand end thereof toward the right hand end. 'I'his action increases the currentilow through solenoid winding 29= in respect to the current flow through solenoid winding 29l and plunger 36 pioves to the left whereby contact `361s brought into engagement with con'- tact 31. Engagement of contact 35 with contact 31 establishes a circuit as follows: Vsecondary 92, wire 2|5, wire 2|4, small electromagnetic winding 2|8. wire 2|9, contact 31, contact 35, switch arm 3|, wire 226, wire 222, field winding |61, limit switch 11, wire 220 and wire 2I0 to the other side of secondary 82. The current ow through small electromagnetic winding 2| 8 increases the leftward pull upon plunger 30 whereby contact 35 is held firmly in engagement with contact 31. Energization of eld winding |61 causes rotation of rotor 'in such direction that main operating shaft 63 rotates counterclockwise as viewed from the left in Fig. 4; Initial counterclockwise rotation of main operating shaft 63 moves limit switch v actuator 12 out of engagement with limit switch arm 13 whereupon limit switch 14 closes. Field winding |65 is thereby placed in lparallel with small electromagnetic winding 2I8 and the current flow through both field winding |65 and small electromagnetic coil 2I8 now traverses eld winding |61. Rotors 52 and 51 will thereupon attempt to rotate main operating shaft 63 in opposite directions but since field winding |61 is more highly energized than field winding |65, the rotor 51 will continue rotating main operating shaft 63 in a counterclockwise direction until balancing contact finger 18 has moved along balancing resistance 19 towards the left end thereof to such position that the current flows through solenoid coils 28 and 29 are again substantially equalized whereupon plunger 36 returns to its mid-position and moves contact from engagement with contact 31. Separation of contacts 35 and 31 breaks the parallel circuit through small electromagnetic winding 2 I 8 whereupon field windings |65 and |61 are placed in series across secondary 82 by the circuit previously traced. Rotors 52 and 51 therefore just balance each other and further rotation of main operating shaft'63 ceases.

During this counterclockwise rotation of main operating shaft 63 pinion 64 has lowered actuating rod 65 accompanied by a lowering of the extended left end of lever 61. This downward motion of lever 61 moves proportioning oil valve I3 towards closed position and operates shutter 23 to decrease the effective areas of inlet openings 2|. f

This downward movement also causes starting switch 228 to o-pen but holding switch 230 remains closed because of its humped or curved formation and the amount of heat supplied to the space is correspondingly decreased. Now as the space temperature fluctuates up and down, the oil and air supply will be gradually varied in accordance with these fluctuations and, under normal weather conditions, the space temperature should level olf at some point within its permissible range of variation and be maintained thereat by continuous operation of theoil burning mechanism at a rate whichl just compensates for the demand for heat.

If, during this operation, the flame should become extinguished, the charge on grid 249 will again build up and stop the flow of current from anode 250 to cathode 25| whereupon relay coil 231 will be deenergized and the ,formerly described holding circuit including heating element II9 will be reestablished and after a predetermined period of heating, the system-will be shut v down unless combustion is reestablished by reenergizing of ignition means 246. In this particular system, there is no stand-by period and then a subsequent recycle to reestablish combustion. If there should be a failure of electrical power during operation of the system, the oil burning control mechanism will return to the position shown in Fig. 4 and combustion cannot again be reestablished until starting switch 228 is closed as the result of a demand for full capacity as previously explained.

If the space temperature should again reach its upper desired limit, the lever 61 will be returned to the position shown in Fig. 4 and at this `time the curved or bent holding switch 23D will again be tilted at such an angle that its circuit willopen and the system Will be shut down.

In this system, it will be noted that operation of the oil burning mechanism is not only dependent upon movement of movable contact member 26 but is also dependent upon proper operation of lever 61 so that shut-off valve I2 cannot be opened unless lever 61 has actually moved to a position in which oil proportioning valve I3 is fully opened and shutter 23 has been operated to allow delivery of the proper amount of combustion supporting air. The starting switch 228 closes when lever 61 has been fully raised and opens immediately upon initial lowering thereof. The bent or curved holding switch 23|! closes when the lever 61 has been fully raised and remains closed until the lever 61 returns to its lowermost position. The use of a combustion responsive mechanism which responds to the actual presence or absence of iiame rather than combustion temperatures may be particularly desirable in proportioning systems of this typel wherein llame may be continuously present but the temperature of combustion may vary considerably by reason of the oil burning apparatus operating at varying capacities. It should again be understood in connection with the syste-m of Fig. 4 that the oil burning apparatus need not necessarily be maintained inoperative until there is a demand for full capacity. It is only necessary that the demand should be such that suflicient oil and air will be supplied so as to permit of proper ignition. Likewise, the arrangement should be such that the holding switch 230 opens whenever the minimum demand reaches a predetermined point which point must necessarily vary with diierent types of fuel burning apparatus.

While two specic embodiments of the inven tion have been herein described', it will be apparent to those skilled in the art that many changes could be made therein without departing from the spirit of the invention and I therefore intend to be limited only in thepurview of the appended claims.

I claim as my invention:

l. An automatic fuel burning system of the class described, comprising, in combination a burner, fuel feeding means therefor, a fuel supply controlling device, ignition means for igniting the fuel supplied thereby, a main control, and means associated with the main control, fuel supply controlling vdevice and ignition means arrangedrto operate said fuel supply controlling device to supply fuel at at least two different rates besides no supply and to activate said ignition means each time the rate of fuel supply is changed from no fuel iiow to a fuel ilow, and means operative to renderthesystem inoperative until manual intervention if combustion is not successfully established upon an initial supplyingof fuel.

2. In combination with a burner, a iluid fuel supply line; a shut-oft valve and a flow propor-V tioning. valve in series therein, a movable member which moves throughout a given range upon predetermined changes in the value of a condition, and means associated with said valves and movable member operative to position said flow proportioning valve in accordance with the position of said movable member at all times, to open said shut-off valve when the movable member reaches a given point in its range of movement when moving in a flow proportioning valve opening direction and to close the shut-off valve when the movable member reaches a given point, spaced from said rst point, when moving in the opposite direction.

3. In combination with a burner, a fluid fuel 0 supply line, a shut-off valve and a flow proportioning valve in series therein, a movable member which is moved throughout a given range upon lpredetermined changes in the value of a condition, means associated with said valves and movable 5 member operative to position said flow proportioning valve in accordance with the position of said movable member at all times, to open said shut-off valve when the movable member reaches a rst point in its path of travel while moving in one 0 direction and to close the same when the movable member reaches a second point in itsy path of travel while moving in the opposite direction, ignition means, and means associated with said movable member and ignition means operative to valve is moved to open position.

4. In combination with a burner, a iiuid fuel supply line, a shut-off valve and a flow proportioning valve in series therein, a movable member which is moved throughout a given range upon predetermined changes in the value of a condition, means associated with said valves and movable member operative to position said flow proportioning valve in accordance with the position of said movable member at all times and to respectivelyopen and close said shut-off valve at two spacedpoints in the travel of said movable member, ignition means, means associated with the ignition means and shut-off valve operative to activate said ignition'means when said shut-off valve is opened, and means responsive to the successful establishment of combustion operative to deactivate said ignition means. l

5. An electrical rcontrol system for fuel burning systems comprising, in combination, electrically controlled means for supplying fuel and air to a burner, electrically controlled ignition means for igniting the fuel supplied to the burner, a condition responsive main control, and electrical means actuated thereby for controlling said electrically controlled fuel and air supplying means to vary the supply lthereof as the value of said condition fluctuates and for energizing said electrically controlled ignition means each time there is an initial supply of fuel'and air.

6. cAn electrical control system for fuell burning systems comprising, in combination, electrically controlled means for supplyingv fuel and air to a burner, electrically controlled ignition means for actuated thereby for controlling said electrically controlled fuel and air supplying means to vary 5 the supply thereof as the value of said condition nuctuates and for energizing said electrically controlled ignition means each time there is an initial supply of fuel and air, and ignition control means for -thereafter terminating energization of the activate the ignition means when said shut-off y ligniting the fuel supplied to the burner, a conditionresponsive main control, and electrical means Y which is moved throughout a given range upon predetermined changes in the value of a condition, and connections between said movable member, flow proportioning valve, air supply controlling means, and shut-01T valve operative to vary the supply of fuel and air in accordance with the varying positions of said movable member, to open said shut-olf valve at one position of the movable member and to close the same at another position of the movable member.

8. In combination with a burner, a fuel supply line, a shut-off valve and a flow proportioning valve in series therein, an electrically operated blower, a damper for controlling the output of the blower, a condition responsive member movable between predetermined limits in response to predetermined changes in condition to which it responds, and connections between said member, valves, and damper effectuating simultaneous and proportionate movement of said flow proportioning valve and damper in accordance with 'themovements of said member, opening of said shutoif valve and energizing the blower at one limit of movement ofsaid member, and closing said shut-off valve and deenergizing the blower when said member is at the other limit of its movement.

9. In combination with a burner, a fuel supply line, an electrical shut-off valve and a flow proportioning valve in series therein, a condition responsive element movable throughout a given range in response to predetermined changes in the condition to which it responds, means controlled thereby ,operative to position said flow proportioning valve in accordance with the movements of said thermostatic element, a starting switch moved to closed position upon movement of said element to such position that said flow proportioning valve is moved toa. predetermined flow position, a holding switch moved to open position when said element is in such position that the flow proportioning valve is moved toa predetermined minimum flow position, and starting and holding circuits controlling the operation of rmined changes in the temperature to which it Vresponds, means controlled thereby operative to position said flowproportioning valve in accordance with the movements of said thermostatic,v element, ignition means, a starting switch moved to closed position upon movement of said thermostatic element to such position that said flow proportioning valve is moved to its maximum flow position, a holding switch moved to open position when said thermostatic element is in such position that the flow proportioning valve is moved to closed position, starting and holding circuits controlled by said starting and holding switches and operative to open .said shut-off valve and to actlvate the ignition means and means independent of said holding switch operative to terminate operation of said mnition means.y

11. In combination with a burner, fuel supply controlling means, a member movable throughout a predetermined. range in response to predetermined changes in the value of a condition, connections between the fuel supply controlling means and movable member operative to vary the supply of fuel in accordance with the movements of the movable member whereby the temperature of combustion will vary, and means responsive to the actual presence of flame and independent of the temperature of combustion operative to discontinue the supply of fuel upon extinguishment of the flame While fuel is being supplied at any rate.

l2. In combination with a burner, a fuel ow proportioning valve and a fuel shut-oi valve connected in series, a controlled member connected to the ow proportioning valve, a controller associated with the controlled member and operative to variably position the same upon variations in the demand for fuel, and connections controlled by the control member arranged to quickly and completely open the shut-Off valve only when the flow proportioning valve has been moved to a predetermined open position after having been closed and to quickly and completely close the shut-off valve when the ow proportioning valve is moved to a second predetermined flow position which is less than said rst flow position.

13. In combination with a burner, a fuel flow proportioning valve and an electrically operatedl fuel shut-off valve, a controlled member, connections between the controlled member and flow proportioning valve by which the latter is positioned according to the position of the-former, a first switching means moved to a new circuit controlling position by the controlled member whenthe same moves to a first position in which the iiow proportioning valve is opened to a predetermined position, a second switching means moved to a. new circuit controlling position when the controlled member returns to a second position in which the ow proportioning valve is moved to a second predetermined position, circuit operative to determine the extent and direction of movement of the motor means.

14. In combination with a burner, a fuel ow proportioning valve and an electrically operated fuel shut-olf valve, a controlled member, connections between the controlled member and ow proportioning valve by which the latter is positioned according to the position of the former, a rst switching means moved toa new circuit controlling position by the controlled member when the same moves to a rst position in which the ow proportioning valve is opened to a predetermined position, a second switching means moved to a new circuit controlling position when the controlled member returns to a second position in which the flow proportioning valve is moved to a second predetermined position, circuit connections controlled by said switching means operative to open the shut-off valve when the controlled member moves to said first position and to close the shut-off valve when the controlled member moves to said second position, reversible motor means in control of said controlled member, a variable resistance means associated with the motor means to determine the extent and vdirection of movement of the motor means, and a condition responsive controller operative to vary the variable resistance means in response to changes inv the condition to which it responds.

15. In combination with a burner, a uid fuel supply line, a shut-off valve and a ow proportioning valve in series therein, a movable member which is moved throughout a-given range upon predetermined changes in the value of a condition, means associated with said valves and movable member operative to position said flow' proportioning valve in accordance with the position of said movable member at all times and-to respectively open and close said shut-01T valve at two spaced points in the travel of said movable member, ignition means, means associated with the ignition means and shut-off valve operative to activate said ignition means when said shuto valve is opened, and means to thereafter automatically de-actuate said ignition means.

FREDERICK S. DENISON.

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