US2649148A

US2649148A - Air-atomizing oil burner

Info

Publication number: US2649148A
Application number: US182952A
Authority: US
Inventors: Harry F Tapp; Richard M Cochrane
Original assignee: Gilbert and Barker Manufacturing Co Inc
Current assignee: Gilbarco Inc
Priority date: 1950-09-02
Filing date: 1950-09-02
Publication date: 1953-08-18
Anticipated expiration: 1970-08-18

Description

H. F. TAPP ETAL AIR-ATOMIZNG OIL. BURNER Aug. 18, 1953 4 Sheets-Sheet 1 Filed Sept. 2, 1950 c HUIT Aug. 18, 1953 H, F, TAPP ETAL 2,649,148

" AIR-ATOMIZING OIL BURNER Filed Sept. 2, 1950 4 Sheets-Sheet 2 1 152 w x41 'l I 135 INVENToRs I3! Kga HXRRYEIPP mm BY (Za gb 1- ATTO EYS 4 sheets-sheet 3 A NN R. www m m m. s NNN H @N WA dro N n QN mNM. n y@ A n N H HR m www KN.

Aug. 18, 1953 H. F. TAPP ET A1.

AIR-ATOMIZING OIL BURNER Fired sept. 2, 195o' Aug. 18, 1953 H. F. TAPP ETAL 2,649,148

AIR-ATOMIZING OIL BURNER Filed sept. 2, 195o 4 sheets-met 4 INVENToR s HARRYE )EPP Alm- R/CHAFD MCM/1M Patented Aug. 18, 1953 2,649,148 AIR-ATOMIZING OIL BURNER Harry F. Tapp,

Longmeadow, Cochrane, West Springfield,

and Richard M. Mass., assignors to Gilbert & Barker Manufacturing Company,

Massachusetts Springfield, Mass.,

a corporation of Application September 2, 1950, Serial No. 182,952 3 Claims. (C1. 158-76) This invention relates to an improved oil burner of the so-called air-atomizing type.

The invention has for its general object the provision of a burner, which will burn fuel oils of various grades, including heavier grades, such as No. fuel oil, for example, under conditions that can be controlled with precision to yield eflicient and clean combustion, and which may be used to fire very small furnaces, such for example as have heretofore been red by pot type burners, and even the small fire boxes of stoves and kitchen ranges.

The burner utilizes an air-atomizing type of nozzle to enable low firing rates to be secured with nozzle passages and orices, which are large enough to `avoid clogging, and to enable effective atomization to be effected at relatively low pressures. Oil, primary air and secondary air are respectively supplied by a pump, compressor and fan, all driven by an electric motor, usually under automatic thermostat control and the rate of now of oil and primary and secondary air to' the nozzle is regulable with precision as is the pressure of the oil and primary air supply, so that combustion conditions can be accurately controlled.

The invention has for other objects to provide in a burner features of construction which enable manufacture at relatively low cost and at the same time provide for eiiicient and controlled combustion, and to improved construction and arrangement of parts that provide for convenience of assembly and also of disassembly, when required for easy servicing in the field.

These objects will best be understood from the detailed description of one illustrative example of the invention in the accompanying drawings, in which:

Figs. l and 2 are small scale elevational views showing opposite sides of an oil burner embodying the invention;

Fig. 3 is a rear elevational View of the burner;

Fig. 4 is a sectional elevational View, taken on the line 4 4 of Fig. 3 and drawn to a larger scale;

Fig. 5 is a fragmentary cross-sectional view taken on the line 5 5 of Fig. 4;

Fig. 6 is an enlarged fragmentary sectional view taken on the line 6 6 of Fig. 4, showing the atomizing nozzle and the supply conduits for oil and primary air;

Fig. 7 is an enlarged cross on the line 1 1 of Fig. 6;

Fig. 8 is a sectional plan view taken on the line 8 8 of Fig. 1

sectional view taken provide features involving Fig. 9 is a full-size fragmentary sectional plan view taken on the line 9 9 of Fig. 4;

Fig. 10 is a cross-sectional view taken on the line l0 l0 of Fig. 9;

Fig. 11 is a cross-sectional view taken on the line H Il of Fig. 8;

Fig, 12 is a fragmentary sectional elevational View taken on the line I2 I 2 of Fig. 8;

Figs. 13, 14, 15, 16 and 17 are cross-sectional views taken on the lines |3 l3, I4 |4, l5 |5, |6 I6 and Il ll of Fig. 12; and

Fig. 18 isa cross-sectional view taken on the line i8 |8 of Fig. 6.

Referring to these drawings; the burner includes a central casing (Fig. l), designated generally as l and affording in its lower portion a housing for the fan 2, which supplies secondary air to the burner. This casing, as shown in Figs. 1, 2, 3 and 4, is made up of two sections 3 and ii, which are so constructed that they may be made by die casting. The larger section 3 has a curved bottom wall 5, forming part of the volute for the fan, two nat parallel upstanding side walls E and l with relatively narrow rectangular

upward extensions

8 and 9, respectively, which bulge outwardly slightly, and a front wall I0 which is tangential to the end of larger radius of the volute wall 5 and which upstands at right angles to the side walls 6 and 'I and their

respective extensions

8 and 9. The other end of the curved wall 5 terminates in a horizontal plane passing through the axis of revolution of fan 2. That portion of each side wall 6 and 1, which is disposed below said plane, has a curved margin integrally connected to the curved wall 5. Each side wall is further bounded by a short horizontal edge, disposed in said plane and extending inwardly a short distance from the end of smaller radius of wall 5; a curved edge, which is a 90 arc concentric with the axis of fan 2 and extending from said horizontal edge; a horizontal edge tangent to the upper end of the curved edge and which is substantially equal to the radius of the fan; a vertical edge forming the inner edge of

extension

8 or 9, a horizontal edge forming the a curved wall ii (Figs. 1 and 4), which extends from said plane and the last-named end of Wall 5 upwardly, over and across toward wall lo and completes the volute of the fan housing; integral, spaced, side walls i 2 and i3 (Figs. 1, 2 and 8) a connecting end or rear wall Hi, which parallels the front Wall lil; and a narrow top wall l5. The side walls l2 and I3 serve as continuations of the side walls 6 and l, and their

extensions

8 and 9, respectively, and each has a short radial and horizontal edge; a curved edge; and a longer horizontal edge to rest upon and abut the corresponding edges of section 3, together with a vertical edge to abut the rear edge of the

extensions

8 or 9, as'the case may be, of the adjacent side wall. The sections 3 and li are held together by two screws l5 which pass one through side wall 6 and one through side wall 1 and thread into the wall ll.

The front and rear walls` lll and I4'. of the casing (Figs. 4 and 3), have coaxial cylindrical openings therein. the rear end of an air supply tube lBds suitably fixed as indicated in Fig. 8. lThe opening in wall It is closed by a circular disk l1, 'suitably fixed to such wall, as by screws i8 (Fig. 4 This casing i is supported from the iioor in any suitable way, as by a short standard i9 (Figs. 1 and 4)', fixed at its upper end in the lower iront part of the section '3 of the casing and adjustably secured at its lower end in the Ycross bar portion of a U-shaped foot piece 26, which rests on the floor. The upper end of the casing i is closed in any suitable way, as in the example shown, by the bottom wall 2l or a box 22, which houses certain electrical equipment as will later appear and which has two downwardly extending parts 23 overlapping the side walls of the casing and secured by screws 23`,`on'e to side wall l2 and the other to side wall i3. The inner end of wall Il (Fig. 4) of the casing section 5 is spaced from wall i8 to formthe'outlet 241i of the ian, which outlet communieatefs with the upper portion of the interior of casing l and with air tube i6. The side walls 6 and, 1 o the casing have large circular openings therein, that on wall 6 (Fig. 4) being larger than the outside diameter of fan rotor 2 and that in wall'i (Figs. 3 and 13) forming vthe inlet to the fan housing. The opening in wall 6L (Figs. 2, 3 and 4) is closed by the end Flange 25 oij an electric motor 26, which drives then fan 2 and an air compressor and oil pump tobe laterfdescribed. Flange 25 is secured by screws 21 to wall 6. The motor has its drive shaft` 25A (Fig. 3)v extending into casing l and secured in thehoilowsendof a'stud 23', fixed to the'hubof ian 2, als, indicated. The opening in wall A1.`(1-figs 3 and 12) forms the inlet to the fari. A deiiector 290i irusto conical shape has an outer annular flange, which rests in a seat in side` wall 1 and is clamped between the latter and an annular ring Scby screws 3i. rilhis ring 361s integrally connectedby a series of horizontal arms 32y to a circular end plate 33 of thevair compressor and serves to support both the compressor and the cil pump. There is a space between the plate 33 and ringl 36 for the admission of air to the, deflector 29 which directs they airy axially to ian rotor 2. A shield, comprising a plurality of wire rings 35, mounted in axially spaced relation inther gap between the ring and end plate, is provided, and these rings aresuitably secured tothe arms 32.

Theair compressor (Fig. 12) includes a central body 35 clampedgbetween the end plate 33 and an endplate 36by screws 31. The body 35, has a cylindricalchamber 38 (Fig. 17) extending through it and located eccentrically thereof. 1n this chamber 38 is a rotor 38 having a plurality of angularly-spaced radially-slidable vanes 13, the inner ends of which ride on rings 4l, 2 4formed in the endsof the rotor. The chamber 38 may have a liner (i3 of suitable oil-impreg- In the. Opening in Wall w disposed one in each of two recesses l nated material. An O-ring l is mounted in a circular groove in each

end plate

33 and 36 to press against the adjacent end face of body 35. These rings 43 prevent leakage between the end plates and body of thev compressor. The rotor 36 is fixed as indicated to a drive shaft 35, which is rotatably mounted in suitable bearings, one in each of the end plates, and projects beyond the end plate. 3,3 and into the fan housing where it is connected by a suitable 'flexible coupling te, (rigs) to the outer end of the described stud 28' vand thus to motor shaft 28. The inlet and outlet'ports of the compressor are shown in Fig. 17 at fit1, and 5,3, respectively. rThey are arcuate grooves formed in the inner face or" the end plate 36j The outlet port 118 is connected by a horizontal passage 49 (Fig. 16) to two radial passages 50 and 5l formed in end plate 36. The outer end of passage 5l is normally closed by a plug 52 and is adapted for connection to a pressure gauge when the plug is removed. The outer end of passage 5i) is adapted for connection by a pipe 53 to the primary air supply passage of the atomizing nozzle as will later be described in detail. The inlet port 41v is connected to one end ofy a passage 54 which extends horizontally through end plate 36 (Fig. 1.6) and part way into a boss 55 (Fig. 14) formed on an abutting plate 56, which ask shown in Fig. 12 is secured by screws 51 to endl plate 3:26,. Plate 56 has projecting from it an inner boss 53 housing the oil pump and an outer annular marginal rim 59. The boss 55 described merges with boss 58 and has radial holes 611 connecting hole 56 to the space between the bossk 58 and flange 53.

A muiiler of the labyrinth type is provided on the intake side ofthe compressor. The space between the described hub 56 and r-im 59 (Fig.14) is subdivided by a series of angularly-spaced bafes, 6l, 62, 63, 63'65 and S6 which extend radially from the hub to the rirnandwhich project longitudinally from

plate

5,5 tothe same extent as rim 59 and boss 53 (see Fig. 12). The baiiies 62 and65 (Fig. 14) are formed, on radial bosses 61 and 6 8-, respectively, on plate 56. A thin plate 66 (Fig. 12), having on its inner face a layer of suitable sound-deadening material 16, abuts the outer end facesv of the rim 59, the bossL 53 and all the baffles and is secured by four screws 1l (Fig.14). The baiilesthus subdivide. the space between rim 53 andv hub 5S and between

plates

56 and 69 into al series of compartments` 12, 13, 14, 15;, 16 and 11. The baiies 62- and63 and the baiiies 6 5 and 66 have a plurality of notches1 in their outer end faces but the baiiies 6l and 64 are imperforate. Air inlet openingsr19 (Fig. 14) are, provided in plate 69, to admit air to the

chambers

12 and 15 on opposite sides of the imperforate baille 6l. Air from chamber 12 followsa clockwise path, passing through the opening 18 in barile 62 into chamber 13, through the openings 13.in baile 63 into chamber 14 and thence through the right hand radial hole` Gli-into vhorizontal hole 54 and thence into the inlet port 41:0f theraircompressor. Air from chamber 15v follows a counterclockwise path, passing through the openings 18cm baffle 65 into chamberf16, then through the.- openings 13 in baiile 66 into chamberi11 Yand'. thence through the left hand radialhole 69 into the horizontal hole 54 and 'thence to the inl-et vport 41 of the air compressor.

The oil pump is shown in Figs, 12 and.15. It is of the variable-capacity type and is mounted in a cylindrical recess 8|? in the boss 58, which recess is coaxial with shaft 45 and extends from its rear face toward but not through the front face of the boss. The end plate 36 of the air compressor has a portion 58 of its central and bearing-containing hub entering the aforesaid recess to close it on the air compressor side and the joint between the abutting faces of this boss and hub is suitably sealed as indicated. Into this recess is pressed a ring 3|, having centrally in its inner face two grooves 32 and 33 (Fig. 15), which are separated by two diametrically opposed lands and which form the inlet and outlet ports of the oil pump. A cup-shaped rotor 84, rotatably ts within ring 3| and between the end walls of the lrecess 83. This rotor has a slot of non-circular shape in its end wall to receive a key 35 which is of similar shape (see also Fig. 16) and is formed .on the outer end of shaft 45.

Two cylinderforming holes are provided through the annular part of the rotor in diametrically opposed relation to receive the ends of a piston 86. This piston is xed centrally between its ends in a cylindrical piece 8l which ts within the cupshaped rotor and may be moved t0 various positions of eccentricity relatively thereto. The piece 81 has a groove in its outer face to receive a slide 88. The latter has a hole therein to receive a pin 89 eocentrically located on the inner end of a shaft 93 which is mounted in hub 58 and a smaller hub 9|, integrally connected thereto, to turn about an axis eccentric to shaft 45. Suitably, fixed as by welding to the outer end of shaft 93, is a plate S3, having a curved slot therein, and this plate may be held in various positions of angular adjustment by a screw S4 which passes through the slot and threads into boss 3|. By moving shaft Si? as by a tool inserted in the hexagonal depression :":2 in the end of shaft 9|! the pin 89 may be moved to Vary the radial position of the piston 83 and thus the capacity of the pump. A cup-shaped pressed-metal cover 95 conceals the oil-pump-adjusting means described and is held to a lug 95 on boss 9| by a screw 97. The oil inlet for the pump is formed in the described boss 58 (Fig, l5). It includes a radial passage 98, having a counterbore, in which is received a filtering screen 99 having an open inner end surrounded by a flange that is pressed against a seat in the counterbore by means of a spring |33, acting against a plug IDI, threaded in and closing the outer end of the counterbore. A passage IGZ connects this counterbore to an inlet |33, into which is threaded one end of suction pipe IEB/i adapted for connection at its other end to an oil supply tank (not shown). The outlet port 83 is connected to a radial passage I 05 having a counterbore, the threaded outer end of which is normally closed by a plug |06 that is removable to enable attachment of a pressure gauge, when desired. A diagonal passage Il connects the last-named counterbore to an outlet |33 into which is threaded a pipe |09 for supplying oil to the nozzle of the burner.

It will be noted from Fig. l2 that the left hand bearing II of the air compressor adjoins the oil pump and is positioned to receive some of the pumped fuel oil and utilize such oil for lubricating purposes. A sealing ring III is provided on the right hand side of bearing II to tightly seal the bearing and prevent oil from the pump from entering the compressor and to prevent air from the compressor from reaching theV oil pump. The oil pump is used as a metering pump as well as a transfer pump to draw fuel from a low level supply tank and it is' important for the latter purpose to provide the seal described to prevent loss of suction.

Referring next to Figs. 4 and 8, the disk I'I is secured, as by screws II2, to a casting II3. The latter supports one end of a tube II4, which extends coaxially through the described secondary air tube I 6 and terminates near the forward end of such tube with an atomizing nozzle, the body and cap of which are designated II5 and IIB respectively. The casting I I3 has a lateral extension II'I (Fig. 8) which extends into and fills a slot in the side wall I3 of the casing section 4 (see also Figs. l and 3) and into which the described air and oil pipes 53 and |09 are screwed. These pipes have unions I I 8 and I I9, respectively, which are located near member I I7 and which .can be disconnected whenever it is desired to remove the assembly comprising disk I1, members H3 and II'I, together with the tube II|| and the atomizing nozzle and other parts connected thereto, as will be later described in detail.

Referring next to Fig. 9, it will be seen that the member I I3 and its lateral extension I I1 have radial passages |23 and |2| which at their outer ends respectively connect with the air and oil supply pipes 53 and |09 and which at their inner ends respectively connect with annular chambers |24 and |25 formed in member ||3 coaxially of tube I I 4. Within the tube H4, which at its outer end is screwed into member I|3, is an oil supply tube I 26. This tube carries an O-ring |21, which partitions the chambers |24 and |25. Tube |26 has xed thereon a snap ring |28 which together with a shoulder I 29 confine the O-ring to an axial position such as is effective to seal the oil Chamber |25 from the air chamber |24. The air chamber I 24 connects with the annular space between tubes II 4 and |26 and the oil chamber |25 connects with the space within tube |26.

Referring next to Fig. 6, the forward end of air tube I I4 is counterbored to receive and closely fit a disk |30. The nozzle body |I5 has a threaded portion I3I, which screws into the forward end of tube II4 and clamps the disk |30 between its end wall and the end wall of the counterbore. This disk has an integral and rearwardly extending hub |32, which tightly 'lts into the forward end of oil tube |26 and which has inside the tube a valve seat |33. The latter is adapted to be en- `'gaged by a valve |34 on the end of a rod |35 located within tube IZE and slidably supported from the inner periphery of the tube in any suitable way as by the radial projections |36 on the rod. An oil passsage |37 extends axially through the disk |33, hub |32 and seat |33 to receive oil from tube |26, when valve |34 is moved to the left away from its seat. This oil passage |31 registers with a central passage |38 in the nozzle -body IIE. The disk |33 also has in its forward face an annular groove |39 and a plurality of holes I 43 which extend from the bottom of the groove to the rear face of the disk and there communicate with the annular space between tube I I4 and pipe |26 to receive primary air. The nozzle body I|5 has extending longitudinally ltherethrough a plurality of passages I4I arranged in angularly-spaced relation about the central oil passage |38. These air passages I4| communicate at their rear ends with annular groove |39 and at their forward ends with an annular chamber |42 formed Within cap IIB and the forward Vend I 43 of the nozzle body which end is of reduced diameter. The cap I I 6 is threaded onto a part I 44 of the nozzle body and its front wall has a central orifice |45 which leadsfrom a coni- -oal recess |46, formed in the face ofthe front wall, to the outer face of such. wall. The iront end of the nozzle part |43 is counterbored to receive the inner flanged end of a cylindrical piece |41 which terminates with a frusto-conical end |48- projecti-ng into the conical recess |46 in spaced relation therewith to form an annular Whirl chamber |49 which converges to the oriiice |45. The part |41 has an axial oil passage |50 which at one Vend communicates with oil passage |38 and which extends closely adjacent to but stops short of the front endof part |41. Here, the passage 50 communicates with the inner ends of a plurality of holes which extend radially outward to the outer periphery of part |41. Encompassing the cylindrical part |41 is an annular ring |52, which is pressed into and held in abutment with the outer end face of the part |43 by the cap ||6 and which in turn hol-ds the inner flanged end of member [41v in its seat in the counterbore. This ring |52 has in its front face an annular groove |53 closed at the front by cap H6 and a plurality of angularly spaced slots |54 locatedy tangentially of the groove |53 and connecting at their outer ends with the air chamber |42. The primary air enters tangentially into the chamber |53 at a plurality of angularlyspaced locations andI meets the oil streams, issuing radially from holes |5|, intercepting these oil streams at right angles and eiecting an intimate mixture of fuel and air. This mixture, whirling in the chamber |53,v advances into the conicaly whirl .chamber |49` where it is caused to whirl at rapidly increasing velocity as it advances. toY the outlet orice |45. This rapidlyrotating stream of mixed fuel and air is conned peripherallyuntil it emerges from the orifice |45, where bei-ligV released from peripheral coniinement. it. ies apart. by centrifugal force into a fog-like spray.

Referring again to Fig. 9, it will be noted that the members: |1v and ifi-3 have flat annular faces, between. Which,- isi Aclamped the marginal portion oi a circular diaphragm |55. |Ihe latter is central-ly perforated to receive the threaded hub of a plate |155., which abuts one face of the diaphragm U55.` An annular ring |51, engaging the opposite face of the diaphragm, receives. the threaded hub-of plate .L56 and a nut. |158, threaded on .such hub draws the ring and plate together to. clamp the diaphragm therebetween. The valve rod 1.3.5 .above described, isxed at its rear .end as indicated in the hub of plate 1.5.6. An

Q-ring. |.59 on the valve rod'prevents leakageof oil from chamber into the chamber |60 which is formed in member l|3 on the right side of the diaphragm. Chamber |60 is connectedy to air passsage Il@v 4by a passage |6| (see also Fig. l0). The .chamber .L62 on the other `side of -the diaphragm is connected t0 the atmosphere by a hole |63, iormedin anlug |64, threaded into and closing the outer end .oi an axialpassage `|f5 in disk -|1., which passagecommunicateswith chamber |52. A spring |66 acting between plug |64 andplate |56 tends to Imove valve rod L35 tothe right and vhold Mali/.e134 to seat |33, thus pre- Venting uill iromentering the nozzle until sumcient air pressure hasbeen built up .by the compressor to force diaphragm. |55, to the left against the force of' the spring [66 to. open the Valve. The pressure, at which valve |341 opens, is. ,variable 'by Aadjustment of' screw |64, which is accessible from outside 'the 'burner casing as shown in Fig. 3 for the purpose.

Theair pressure is regulated by an adjustable relief valve |61 shown in Fig. 9. This valve` is mounted for axial sliding movement in the counter-'bored outer end of a passage |68, formed in the extension ||1 and paralleling air passage |26. The inner end of passage |68 intersects the passage |6| andreceives air therefrom (see also Fig. 10). The seat for valve |61 is the shoulder at the intersectionof passage |68 with its counter-bore. The Valve is held to this seat by a spring |69, having a seat in a plug |10 which is threaded into and closes the outer end of the counterbore. A ventv passage |1| (see also Fig. l0) connects the counterbore at a point between the valve seat and plug |16 with the exterior of extension i1, opening into the air chamber in the upper part of the fan housing. The force exerted by spring |63 on Valve |61 is variable by turning screw plug |10, which is accessible from outside the burner casing, as will be clear from Fig. 1, and enables the air pressure to be readily adjusted. As at present contemplated, the burner may operate with an air pressure between 11/2 and 4 p. s. i.

Secondary air isy supplied by the ian through tube I6, as will be clear from Figs. l and 8. Fixed to the tube i5 at a point intermediate its ends, as by screws 1.12, is an annular ring |13, having projecting inwardly therefrom a circular series of helical varies |14.. The inner edges of these varies engage the outer peripheral wall oi a cylindrical tube |15 and support it in coaxial relation with tube i6. The front end of tube |15 is open and terminates adjacent and slightly to the rear of the atomizing nozzle. The rear end of tube |15 is closed by a plug |16, which is secured to the tube as indicated and which has a rounded rear end to divert the air stream issuing from the outlet 24 of the fan into the annular passage |11 between the tubes i6 and |15. As wil1 be clear from Fig. ll, successive helical blades |14 in the series overlap so that all air traveling through the annular passagey |11 is engaged by the blades and caused to whirl as it moves rorward in such passage. The whirling air stream, emerging from passage |11 is deiiected toward the central stream of fuel and air, which is emitted from the nozzle orifice |45, by means of a frusto conical air director |18 on the outlet end of tube |45. Substantially all the secondary air is whirled as described. There is a single small vent passage |15 (Figs. 4. and 5) formed in plug |16 for the purpose ofpreventing the forma-tion of a vacuum in the interior of tube |15. Except for the insignificant amount of air entering tube |15 through this Vent passage, all the secondary air supplied by fan 2 is whirled. The plug lil-S, has. a central opening therethroughwhich re vceives and closely fits the described nozzle* carrying tube |.|;4. A set scr-ew |86, threaded in the plug |15, `lolds` tube |14 in place. Thus, the varies v|14 support tube |15, the conduit for secondary air and the oil conduit togetherwith the ignitionelectrodes.

The ignition electrodes are sh-own at. |8| (Figs. 4, 8 and ll). `They are mounted in insulators |82 which in turn extend through holes in plug |16. Each insulator is held. in place by a set screw |'8'8, threaded in plug |16 and acting against a thin split sleeve |84 (Fig. 5), which surrounds the insulator. On the rear end ofv each electrode (Figs. 4 and 8.) isa metal terminal, |85 which. progressively increases yin diameter rearwardly to form a cam. These cam terminals |85 are engaged, one by each of two spring-pressed metallic plungers |86 (Fig. 4), mounted in an insulator |81, which is xed in bottom wall of casing l2| and carries the high tension terminals of an ignition transformer |88, which is mounted in the front half of the described :box 22. These terminals suitably connect electrically, one with each of the spring-pressed plungers |86. It will be clear that, when the disk I1 is unfastened and pulled rearwardly it will carry with it the assembly of tubes for primary air and oil and the ignition electrodes and that the connection between the transformer and electrodes will be broken before the electrodes are withdrawn from the tube I6. This entire assembly can readily be removed from tube I5 for inspection, adjustment or repair and may as readily be replaced in the tube. As this assembly is replaced the cam terminals |85 engage and force upwardly the springpressed plungers |86, thus remaking the connection between the high tension terminals of the transformer and the ignition electrodes. These electrodes are suitably located so as to produce an arc between them to ignite the spray of fuel mixture. Preferably, the tips of the electrodes are located above and out of the path of the fuel spray and the arc produced between these tips is blown into such path by the secondary air.

The rate of flow of the secondary air stream is varied by means of a damper |89 (Fig. Il), which is pivctally mounted at its lower end on a rod |99, suitably fixed at its ends in the side walls ii and 1 and extending therebetween.. This damper may be swung toward or away from the fan rotor 2 in order to vary the effective area of the outlet 24 of the fan. Conveniently, the damper may be moved by means of a screw i9! having a knurled head is?, which is located outside the housing and by means of which the screw may be turned. The front wall l i! of the fan housing has an opening, through which the shank of screw itl passes. The peripheral wall of this opening closely nts a ball-like part |93 on the shank of the screw. On the outer face of wall lil is a rounded part-cylindrical projection |94 which is engaged by an end face of the knurled head l 92. A coil spring |95, acting between the inner face of wall lll and a washer |99 fixed to the screw, draws the head 92 against the rounded part |94. The screw is thus able to swing up and down about ball |93 as a fulcrum, as may be necessary as the screw 59| is turned. The screw is threaded into a nut |91, held in place by curved prongs |98, formed on the damper, in a manner such as to allow the nut to turn relatively to the damper as required, when the damper is moved in and out by turning the screw.

The described box 22 may as indicated in Fig. 4, contain, in its rear compartment, some of the controls for the burner, such as the relay 99, the thermal safety switch 299 and the reset button 20| for the safety switch. This button is accessible through a hole 292 in the rear wall of casing 22 (see also Fig. 3). The wires enter this casing through an opening 293 (Fig. 2) and a cable 294 (Figs. 2 and 3) extends from controls inside the casing to the motor 26.

In operation, when the motor 2t is started, usually automatically, on a demand for heat, as by the well known thermostat control, the fan, air compressor and oil pump are simultaneously started up and driven but the emission of oil from the nozzle is delayed until conditions of air flow and pressure, suitable for good combustion, are established, The valve |34 prevents oil from entering the nozzle until the primary air has been placed under suiiicient pressure to overcome the force of spring |66 and move the diaphragm |55 to open the valve. This helps in avoiding smoke during the starting interval of operation of the burner. Flow of primary air through the nozzle passages and out through the nozzle orifice and flow of secondary air in the annular passage |11 and out through the open end of tube I 6 will be established before valve |34 opens. Hence, when the valve does open, the oil issuing in radial jets through passages |5| of the nozzle will be met and impinged by jets of primary air issuing tangentially through passages |54 into the chamber |53. In this chamber, the oil and air will be mixed and the mixture will be whirled at considerable velocity. The whirling oil and air mixture advances into the whirl chamber |49, where its velocity rapidly increases as it approaches the outlet orifice |45. As this rapidly-rotating oil and air mixture emerges from the orifice and is freed from peripheral confinement, it flies apart by centrifugal force into a cone-like spray of finely divided particles and fog-like form. The spray is met by a stream of secondary air, whirled by the turbulator vanes |14, and the mixture is ignited by a spark producedvbetween the electrodes I 8|. The whirling of the secondary air produces a short and wide flame having much the shape of an umbrella, adapting it for use in small nre boxes. Combustion continues until the demand for heat is satisfied, when the motor 26 is stopped. As the motor decreases in speed, the pressure of the primary air will soon drop sufficiently to enable valve |34 to be closed by spring 5t. The oil flow is very quickly and sharply cut olf from the nozzle, preventing any dribbling therefrom. However, flow of primary air continues which purges the nozzle. The early closure of the oil valve, well ahead of the cessation of air flow, helps in avoiding smoke during the stopping interval of operation of the burner.

It is to be noted that the conditions contributing to combustion may all be accurately controlled. The oil pump is a metering pump, as well as a transfer pump, and provides for oil flow at a definite rate, which is variable by adjustment of the member 92. The desired rate of oil flow, once obtained by this adjustment, will be maintained. The supply of primary air from the positively-acting compressor is at a constant rate but this rate and the pressure of the primary air are adjustable by turning screw |19, which controls the force of spring |69 which holds Valve |61 closed. By by-passing some of the air, forced by the compressor into the passages |20, IGI, |68, and |1|, the rate of low of primary air and the pressure thereof may be varied. The air pressure at which the oil valve |34 will open is regulable by turning the screw |54 which varies the force of the spring |66 that holds the oil valve closed. The pressure of spring |69 must of course, be somewhat less than the air pressure secured by adjustment of screw |19. The rate of flow of secondary air is adjustable by the swinging shutter |39 in the fan housing. All the adjustments are readily accessible from outside the burner housing, except for the adjustment which varies the rate of oil flow, and for considerations of safety it has been thought best to conceal this oil-flow adjustment from unskilled persons who possibly might tamper with it. However, to the service man the adjustment is readily accessible by removing the cover 95, after the one screw 91 which holds it in place has been removed.

As one illustrative example, to illustrate how small a fire the burner will produce,A a burner constructed according to the disclosure satisfactorily fired a combustion chamber seven inches long, five inches wide and ten inches high, using oil at the rate of .3 gallon per hour and at a pressure slightly less than 2.5 p. s. i., and primary air at a pressure of 2.5 p. s. i. The motor used was rated at one twentieth of a horse power.

The construction of the housing in two sections enables these sections to be manufactured economically by die casting and also facilitates the assembly of parts within the fan housing and also servicing of the fan. With the upper section 4 removed and the motor 2G bolted to the lower section 3, the fan rotor 2 may be placed on shaft 28 in proper position and secured thereto. Then, the assembly of oil pump and compressor may be bolted to the lower section and the connection between the drive shaft 45 and coupling 46 may be made, working from above. Also, the shutter |89 may be assembled and connected to its adjusting screw. Then, the upper section t may be put in place and secured by the two screws I5. The top of the housing is then closed by fastening the transformer and control box 22 to the top of the upper section 4 by means of two screws 23. This leaves the opening in the end wall Ui of the housing and, through this opening, is passed the assembly of atomizing nozzle, electrodes7 tube H5, primary air and oil pipes, the oil valve, oil-valve-actuating means, primary air regulating valve and closure disk. When this unit is pushed into the housing and tube I5, the tube H5 will engage the inner peripheral edges of the turbulator varies |14, whereby the tube and nozzle will be supported in proper coaxial relation with tube I6. The connection between the ignition electrodes and the high tension terminals of the ignition transformer will be automatically made by the cams |85 engaging the spring-pressed plungers It` during the last stage of inward movement of the unit. The closure disk will finally fit into and close the opening in wall M, after which the screws i8 are applied to fasten disk I1 in place and the assembly is complete.

It will be clear that the burner is readily disassembled for servicing. By removing screws |8 and disconnecting the air and oil pipes 53 and |09 at their unions i8 and |I9, respectively, the disk ll may be removed, carrying with it as one unit, the atomizing nozzle, ignition electrodes, tube H5, oil valve, oil and primary air pipes, oilvalve actuating means and primary air regulating means. All these parts may be removed without disturbing their cooperative relationship. If the parts of this unit are disassembled, they may be replaced in the desired relationship before the unit is replaced and such relationship will be retained during the replacement of the unit. The connections between the ignition electrodes and transformer terminals are automatically broken and made as the described unit is respectively withdrawn and replaced. After the described unit has been withdrawn, the upper section 4 may be removed to give full access to the fan and fan housing for cleaning.

The invention thus provides an improved oil burner of the air-atomizing type, whi-ch is capable of manufacture at relatively low cost and yet provides for clean and eicient combustion under conditions that are accurately regulable, and which provides for convenient assembling and disassembling of parts and for convenient 12 adjustment of flow rates and pressure of the air and oil.

What is claimed is:

1. In an oil burner, a fan housing, an openended tube having its inlet end connected to the housing and providing a passage for combustionsupporting air, said housing having a chamber continuous with said passage and in alignment therewith, a first fuel conduit extending longitudinally in said chamber and passage, a fuel nozzle on one end of said conduit and located in said passage near the outlet end thereof, a support to position the outlet end of the conduit in said tube. said chamber having a relatively large opening in its end wall of sufficient size to enable axial withdrawal of said conduit and nozzle and a relatively small slot in its end wall extending from said opening outwardly through said end wall and having in a side wall a continuation of said slot extending inwardly from said end wall, a closure for said opening fixed to the other end of said conduit, said closure having a lateral extension entering into and filling said slot and the continuation thereof, said extension having a fuel passage connected to said conduit and extending to the outer face of said extension, and a second fuel -conduit connected to the outer end of said fuel passage and including a union, whereby on severance of the second fuel conduit at said union, the said closure and its extension may be respectively removed from said opening, slot and the continuation thereof, and the rst fuel conduit and nozzle may be Withdrawn from the air passage and chamber.

2. In an oil burner, a fan housing, an openended tube having its inlet end connected to the housing and providing a passage for secondary air, said housing having a chamber continuous with said passage and in alignment therewith, an air-atomizing nozzle located in said passage near the outlet end thereof, -conduits for supplying primary air and oil to said nozzle and connected at one end to the latter and extending rearwardly in said passage and chamber, means for supporting the conduits near their nozzle ends from said tube, said chamber having an opening in its end wall of suicient size to enable axial Withdrawal of said conduits and nozzle and a slot in its end wall extending from said opening outwardly through said end wall and having in a side wall a continuation of said slot extending inwardly from said end wall, a closure for said opening fixed to the other ends of said conduits, said closure having a lateral extension entering into and filling said slot and the continuation thereof, said extension having air and oil passages respectively connected at their inner ends to the air and oil conduits and extending outwardly and opening into the outer face of said extension, and air and oil supply pipes respectively connected to the outer ends of said air and oil passages and each including a union, whereby on severance of the pipes at their unions, the closure and its extension may be respectively withdrawn from said opening, slot and the continuation thereof and the nozzle and its oil and air conduits may be withdrawn from said passage and chamber.

3. In an oil burner, a fan housing, an openended tube having its inlet end connected to the housing and providing a passage for secondary air, said housing having a chamber continuous with said passage and in alignment therewith, an air-atomizing nozzle located in said passage near the outlet end thereof, conduits for supplying primary air and oil to said nozzle and connected at one end to the latter and extending rearwardly in said passage and chamber, means for supporting the conduits near their nozzle ends from said tube, said chamber having an opening in its end wail of suiicient size to enable axial Withdrawal of said conduits and nozzle and a slot in its end wall extending from said opening outwardly through said end wall and having in a side wall a continuation of said slot extending inwardly from said end wall, a closure for said opening xed to the other ends of said conduits, said closure having a lateral extension entering into and lling said slot and the continuation thereof, said extension having air and oil passages respectively connected at their inner ends to the air and oil conduits and extending outwardly and opening into the outer face of said extension, a Valve mounted in said extension for regulating the flow of primary air, an adjusting means for said valve mounted in the slot-fitting part of said extension and accessible from the outer face thereof, and air and oil supply pipes respectively connected to the outer ends of said air and oil passages and each including a union, whereby on severance of the pipes at their unions, the closure and its extension may be respectively withdrawn from said opening, slot and the continuation thereof andthe nozzle and its oil and air conduits may be withdrawn from said passage and chamber.

HARRY F. TAPP.

RICHARD M. COCHRAN E.

References Cited in the file 0f this patent UNITED STATES PATENTS Number Name Date 1,716,325 Rogers June 4, 1929 1,840,744 Scott June 12, 1932 2,215,941 Smoot Sept. 24, 1940 2,262,525 De Lancey Nov. 11, 1941 2,300,903 Beckett Nov. 3, 1942 2,460,370 Stauffer vFeb. 1, 1949 2,502,210 Demuth Mar. 28, 1950 2,502,664 Nest Apr. 4, 1950 2,553,130 Cadella May 15, 1951 2,585,081 Bernhard Feb. 12, 1952