US2637375A - Fuel supply control for airatomizing oil burners - Google Patents

Description

4 Sheets-Sheet l IMVENToRs IIAMYETW ma H. F. TAPP ET AL .laid-.link N IITL FUEL SUPPLY CONTROL FOR AIR-ATOMIZING OIL BURNERS May 5, 1953 Original Filed Sept. 2, 1950 May 5, 1953 H. F. TAPP ErAL 2,637,375

FUEL SUPPLY CONTROL FOR AIR-ATOMIZING OIL BURNERS Original Filed Sept. 2, 1950 4 sheets-sheet 2 ATTORNEYS May 5, 1953 H. F. TAPP ETAL FUEL SUPPLY CONTROL FOR AIR-ATOMIZING OIL BURNERS` 4 Sheets-Sheet 3 Original Filed Sept. 2, 1950 www5 m Wn m ww m wr. m IIE u. A Y' mm an m s N.. a S/bv a a. Q NN N51 .inn Q NN WNW i V. Q Nm. NNIT. N $4 s, QN O A -w......4,......w Q @wh .wh Illlqlldllrnl "Il" N3 1 ..wm .N U m L ,i v au $1 @NN u l l l n 1r XWNN fus. NNY RN May 5, 1953 H. F. TAPP ETAL FUEL SUPPLY CONTROL FOR AIR-ATOMIZING OIL BURNERS Original Filed Sept. 2 1950 4 Sheets-Sheet 4 INvl-:NToR s HARRY!! 7h Alm Patented May 5, 1953 FUEL SUPPLY CONTROL FOR AIR- ATOMIZING OIL BURNERS Harry F. Tapp, Longmeadow, and Richard M. Cochrane, West Springfield, Mass., assignors to Gilbert & Barker Manufacturing Company, West Springfield, Mass., a corporation of Massachusetts Original application September 2, 1950, Serial No.

182,952. Divided and this application September 19, 1951, Serial No. 247,272

(Cl. S-42.2)

2 Claims. 1

This invention relates to an improved oil burner oi the so-called air-atomizing type.

This application is a division of our application Serial No. 182,952, filed September 2, 1950, and entitled Air-Atomizing Oil Burner.

. The invention has Lfor its general object the provision of a burner, which will burn fuel oils of various grades, including heavier grades, such as No. 5 fuel oil, for example, under conditions that can be controlled with precisen to yield efficient and clean combustion, and which may be used to fire very small furnaces, such for example as have heretofore been fired by pot type burners, and even the small re 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 orifices, which are large enough to avoid clogging, and to enable eiiective atomization to be enected 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 flow 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 laccurately controlled. y

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

These objects Willbest be understood from the detailed description of one illustrative example of the inventionin the accompanying drawings, in which:

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

.-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 thel atomizing lnozzle and` the supplyconduits for oil and primary air;

Fig. 7 is an enlarged cross sectional view taken on the line 'I-l of Fig. 6;

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

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 Ili-IU of Fig. 9;

Fig. l1 is a cross-sectional view taken on the line H-H of Fig. 8;

Fig. l2 is a fragmentary sectional elevational view taken on the line I2|2 of Fig. 3;

Figs. 13, 14, 15, 16 and 17 are cross-sectional Views taken on the lines l3-l3, lli-I4, |5-I5, lG-IB and ll-I'l of Fig. 12; and

Fig. 18 is a cross-sectional view taken on the line I8--I8of Fig. 6.

Referring t0 these drawings: the burner includes a central casing (Fig. 1), 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 4, 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 at parallel upstanding side walls 6 and 'l with relatively narrow rectangular upward extensions 8 and 9, respectively, which bulge voutwardly slightly, and a front wall I6 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 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 substantiallyv equal to the radius of the fan; a vertical edge forming the inner edge of extension 8 or 9, a horizontal edge forming the top of such extension and a vertical edge united to the front wall l0. The smaller section 4 has a curved Wall LI (Figs. l and 4), which extends from said plane andthelast-named end of wall 5 upwardly, over and across toward wall l0 and completes the volute of the fan housing; integral, spaced, side walls I2 and I3 (Figs. 1, 2 and 8); a connecting end or rear wall I4, which parallels the front wall I9; and a narrow top wall I5. The side walls I2 and 1.3 serve as continuations of the side walls and 1, and their extensions 8 and 9, respectively, and each has a short radial and horizontal edge; a curved edge; and Va 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 exten.- sions 8 or 9, as the case may be, .of the ,adjacent side Wall. The sections 3 and k4l are held together by two screws I5 which pass one through side wall t and one through side wall 'I and thread into the wall II.

The front and rear walls .Iii A and I4 of the .casing (Figs. 4 and 8), have coaxial cylindrical openings therein. In the opening in wall I0 the rear end of an air supply tube I6 is suitably fixed as indicated in Fig. 8. rThe opening in wall I4 is closed fby a `circular -disk i1, suitably -xed to such wall, as by screws I8 (Fig. 4). This casing 1 is supported `from the floor -i-n any suitable way,

as by a short standard I9 (Fig-s. 1 and 4), iixed at its upper end in the .lower front part of section 3 of the casing and adjustably secured at its lower end in the cross -bar portion 4of a U-shaped foot piece 2li, which rests on the door. rThe uppcr end of the casing I lis closed i-n any suitable way, as in the example shown, by the bottom wall 2I of a -box 22, which houses lcertain `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', one to side wall lI2 `and the other to side wall 13. The inner end of wall -l-l (Fig. 4) of the casing section 4 is 'spaced from w-all I0 to form the outlet 24 of the fan, which outlet communicates with the xupper portion -of the interior of lcasing I and with air tube IAE. The side walls 6 and 1 lof the casing fhave lar-ge circular openings therein, that 'on wall 6 (Fig. 4") being larger than -the outside dia-meter of fan rotor 2 and that in wall l1 (Figs. 3 and '12) rfor-ming the inlet 'to the ian housing. vThe opening in wall 6 (Figs. 2, 3 and 4) is closed by ythe end flange 25 of an electric motor 26, which kdrives the fan I2 and an air compressor and oil pump to be later described. Flange '25 is secured :by Iscrews 21 to wall 6. The motor'has its drive shaft `28 (Fig. 3) extending into vcasing I and secured -in `the hollow end of a stud 28', nxed to the 'hub of fan 2, as indicated. The open-ing in wall 1 (Figs. 3 and 12) forms the inlet to the flan. A -deector 29 Aof rvfrustoconical shape 'has an louter annular flange, which rest-s in a -fsea-t in side wall 1 and is clamped between -t-he latter and an annular ring 3U by screws 3|. This ring 38 Ais integrally connected by -a series of horizontal arms 32 -to a circular end plate 3-3 of the air compressor 'and serves to support both 4the compressor and the oil pump. There is a space between the plate 33 and Iring 35 for the admission of air -to the deflector 29 which 'directs the air axially -to fan rotor v2. A shield, comprising a plurality of -wire rings 34, kmounted in axially spaced relation in the 'gap between the ring and end plate, is provided, and these rings are suitably secured to the arms 32.

The air compressor (Fig. 12) includes a central body 35 clamped between the end plate 33 andan end plate 35 fby screws 31. The body 35 has -a cylindrical chamber 38 (Fig. 17) extending tlnlough -it and located eccentrically thereof.

4 In this chamber 38 is a rotor 39 having a plurality of angularly-spaced radially-slidable vanes 40, the inner ends of which ride on rings 4I, disposed one in each of two recesses 42 `formed in the ends of the rotor. The chamber '38 may have a liner 43 of suitable oil-impregnated material. An O-ring 44 (Fig. 12) 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 44 prevent leakage between the end plates and'body vof the compressor. The rotor `3.9 is ixed as indicated to a drive shaft 45, which is rotatably mounted in suitable bearings, one

r-i-n each of the end plates, and projects beyond the end plate '33 and into the fan housing where it is connected by .a suitable exible coupling 46 (Fig. 3.) @to the outer end of the described stud 28 and thus to motor shaft 28. The inlet and outlet ports of the compressor are shown in Fig. 17 at 41 and 48, respectively. They are arcuate grooves formed in the inner face of the end plate 316. The outlet port v48 is connected by a horizontal passage 49 (Fig. 16) to two radial passages 50 and 5I Aformed in end plate 36. The outer end of 'passage 51 is normally vclosed by fa. plug 52 and is ladapted for connection to a pressure gauge vwhen the plug is removed. The outer end of passage 50 is ladapted for connection by a pipe 53 to the vprimary air supply passage of the atomizing nozzle as will later be described in detail. The inlet port 41 is connected to one end of a passage 54 which extends horizontally through end plate 36 (Fig. 16) and part way into a boss 55 (Fig. 14) formed on an abut-ting plate 56, which as shown in Fig. V12 is Isecu-red by screws 51 to end plate 36. Plate '56 has projecting from it an inner boss v58 housing the oil pump and an outer annular marginal rim 5S. The boss 55 described merges 'with boss 58 and has radial holes j yconnecting -hole 54 to the space between the boss 5B and flange 59.

A m-u-iller -of the labyrinth type is provided on the intake side of the compressor. The space 'between the described hub 58 and 'rim 59 (Fig. 14) is subdivided Jby a series of angularly-spaced baiiles, 61, 62, AE3, 64, vand 66 which extend radially from the hub to 'the lrim and which project longitudinally -from plate 5'6 to the same 'extent as rim 53 and boss 58 (see Fig. '12). The baffles 62 and 65 (Fig. 14) are formed, on radial bosses 51 and 687, respectively, on plate 56. A thin pla-te 59 (Fig. 71,2), having `on its inner face a layer of vsuitable sounddeadening material '10 abuts the outer end races of the rim 59, the 'boss 58 land all the baffles and is secured by four screws 1I (Fig. 14). 'lhe bailies thus subdivide the 'space between rim 59 'and hub 58 and between plates 55 and A69 winto a series of compartments 12, 13, 14, 15, 16, and l1'1. The baffles 62 and A63 and the baiiles '65 and 86 have a plurality of notches `18 in their outer end faces but the bames 6I and 64 are imperforate. Air inlet openings 19 (Fig. 14) are provided in plate 69, to admit air tothe chambers 1'2 and 15 on opposite 'sides of the vimperforate baille GI. Air from chamber 12 follows a clockwise path, passing through the open-ings t18 in baiiie 62 into chamber 13, through the openings 18 vin 'baille '63 into chamber 14 'and thence through the right hand radial hole 60 into horizontal hole 54 and thence into the inlet port -60 into the horizontal hole 54 and thence to the inlet port 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 80 in the boss 58, which recess is coaxial with shaft 45 and extends from its rear face toward but not through the front face ofzthe boss. The end plate 36 ofthe 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 8|, having centrallyin its inner face two grooves 82 and 83 (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 8| and between the end walls of the recess 80.' This rotor has a slot of non-circular shape in its vend wall to receive a key 85 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 f the rotor in diametrically opposed relation to receive the ends of a piston 86. This piston is fixed centrally between its ends in a cylindrical piece 81 which ts within the cup-shaped rotor and may be moved to various positions of eccentricity relatively thereto. The piece-81 has l a groove in its outer face to receive a-slide 08. The latter has a hole therein to receive a pin 89 eccentrically located on the inner end of a shaft 90 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 90, is a plate 93, having a curved slot therein, and this plate may be held in various positions of angular adjustment by a screw 34 which passes through the slot and threads into boss 3|. By moving shaft 90 as by a tool inserted in the hexagonal depression 92 in the end of shaft 90 the pin 89 may be moved to vary the radial position of the piston 86 and thus the capacity of the pump. A eu-p-shaped pressed-metal cover 95 conceals the oil-pumpadjusting means described and is held to' a lug 96 on boss 9| by a screw 91. The oilk inlet for the pump is formed in the described boss 58 (Figi 15). 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 |00, acting against a plug |0I, threaded in and closing the cuter end of the counterbore. A passage |02 connects this counterbore to an inlet |03, into which is threaded one end of suction pipe |04 adapted for connection at its other end to an oil supply tank (not shown). The outlet port 83 is connected to a radial passage |05 having a counterbore, the threaded outer end of which is normally closed by a Aplug |06 that is removable to enable attachment of a pressure gauge, when desired. A diagonal passage |01 connects the last-named counterbore to an outlet |08 into which is threaded a pipe |09 for supplying oil to the nozzle of the burner.

` It will be noted from Fig. 12 that the left hand bearing ||0 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 is provided on the right hand side of bearing |0 to tightly seal the bearing and prevent oil from the pump entering the compressor and to prevent air from the compressor from reaching the 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 purposeto provide the seal described to prevent loss of suction. Referring next to Figs. 4 and 8, thedisk I1'is secured, as by screws ||2, to a casting |I3. The latter supports' one end of a tube II4, which extends coaxially through the described secondary air tube I6 and terminates near the forward end of such tube with an atomizing nozzle, the body and cap of which are designated l5 andA I9- respectively. The 'casting |I3 has a lateral extension ||1 (Fig. 8) which extendsinto and lls a slot in the side Wall I3 of the casing section 4 (see also Figs. l and 3) andinto which the described air and oil pipes 53 and |09 are screwed. These pipes have unions |B and I I9, respectively, which are located near member ||1 and which can be disconnected whenever it is desired to remove the assembly comprising disk I1, members 3 and |I1, together with the tube |I4 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 ||1 have radial passages |20 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 I4. Within the tube I4, which at its outer end is screwed into member |I3, is an oil supply tube |26. This tube carries an O-ring |21, which Ipartitions the chambers |24 and |25. lTube |26 has fixed thereon a snap ring |28 which together with a shoulder |29 confine the O-ring to an axial position such as is eifective to seal the oil chamber |25 from the air chamber |24. The air chamber |24 connects with the annular space between tubes ||4 and |28 and the oilA 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 closelyt a disk |30. The nozzle body ||5 has a threaded portion I3 I, which screws into the forward end of tube I I4 and clamps the disk |30 between its end wall and the end Wall of the counterborej. This disk has an integral and rearwardly extending hwb |32, which tightly fits vinto the forward end of oil tube |23 and which has inside the tube -a valve seat |33. The latter is adapted to be engaged by a valve |34 on the end of a rod|35 located within tube |25 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 passage |31 extends. axially through the disk |30, hub |32 and seat |33 to receiveoil from tube |25, 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 ||5. The disk |30 also has in its-.forward face an annular groove |39 and a plurality of holes |40 which extend from the bottom of the groove to the rear face of the disk and there corn.- municate with the annular space between tube |4 and pipe |26 to receive primary air. The nozzle body ||5 has extending longitudinally therethrough a plurality of passages `|4I arranged in angularly-spaced relation about the central oil passage |38. These air passages |4| communicate at their rear ends with annular groove |39 and at their forward ends with Yan annular cham,- ber |42 formed within cap ||6 and the forward acens 7 cud |48 or the nozzle bodywhich end is of reduced diameter. `The cap H is threaded onto a part of the nozzle body and its front wall a central -oriiiee 445 which rlea-ds from a conical res cess Il-S, Vformed in the inner face of the front wall, to the outer face of such wall. The iront end xof the nozzle ypart M3 is counterbored to receiye the inner flanged end .of a cylindrical piece llt! whiclrterminates with a frustonconical Aend I. projecting into the conical i/ecess IM in spaced relation 'therewith to form an annular Whirl chamber IAG .which converges to :the `oriee |45, The .part Ml has an axial oil passage |.5 which at one end .mmunicates with oil lpassage |33 and which extends .closely adjacent to .but stops yshort of 'the frontend of part JM. Here, the passage communicates with the inner ends ci a plof rality of holes ll which .extend radially outward tothe outer periphery or part 1.41. .Encompassins the cylindrical part Jil?! is an annular .rips |52; which is pressed into and held in abutment with the outer .end face .of :the part 4.4.3 by :the can 14.6 and which in turn holds the .in-.nerfflaneed .end of member .M1-inns seat :in the countcrbore.. This ring |52 'has in its viront :face an annu-.lar .groove |53 closed fot the .iron-t by .cap .i l .and a plurality of .singularly spaced slots .|154 .located taneentiolly of the .groove |53 ariel .connecting .et their outer .ends with the air chamber |42.. The primary air enters taugentially into .tl-.1e chamber |53 at a Q.

plurality of angularlyfsoaced locations ,and meets the .oil streams. issuing .radially from .holes |51, intercepting these oil streams .at right anales and eiecting an intimate mixture of fuel and air. This mixture, whirling Lin the chamber |53, advancesiinto the con-ical whirl chamber |49 where it is caused to whirl at rapidly 'increasing velocity as it advances to the outlet oriiiee |45. This rapidly-rotating stream of mixed fuel and air is confined peripherally .until it emerges from the orifice V45, :where being `released `from peripheral confinement it flies apart by centrifugal force into a tegel-ilse spray.

Referring again to Fig.. 9, it will be noted :that the members H .and H3 have flat annular faces. between which is clon-ined the marginal portion of a circular diaphragm |55. The 'latter is een.. trall'y perforated to receive the threaded hub of `a plate .il-5.6, which abuis .one face of the diaphragm 4.5.5. An ,annular ring |51, engaging the opposite .face of the diaphragm, receives the threaded hub of plate :|56 and 'a 'mit |58. threaded on `such hub .draws the yring and plate Vtogether to .clamp the diaphragm therebetween.

The valve rod |35, above described, is xed at rear end as indicated in the hub .of plate 1156;. An `O-ring i5@ en `the lvalve rod prevents leakage ofv oil from chamber |25 into Vthe chamber |613 which is loi-med in member |3 on the right side ofthe diaphragm. vCharn'lzier |56 is connectedto air passage |253 by a passage |6| (see also Fig. 10'). The chamber |62 onthe'cther side of lthe diaphragm is connected Jto `the atmosphere by ahole |63, Jformed in a plug |64, threaded into and closing the outer end of an axial passage vH in `disl; I7, which passage communicates with chamber |62. A spring |6 acting between plug `64 and plate 15E `tends to move valve rod |35 Ito theright and hold 4valve |34 -to seat |33, thus preventing oil from entering rthe nozzle until sulficien't air pressure has been built up by -the vcoinpressor to force diaphragm |55 to the left against the force ofthe spring |6 to open the valve. The pressure, at which valve |34 opens, is variable by adjustment of screw |54, which is accessible from outside the burner casing as in Rig. 3 for the purpose.

The air `pressure is regulated by an adjustable relief valve |81 shown in Fig. 9. This yvalve is mounted for yatrial sliding movement in the counterbored Iouter end of a vpassage |68, formed in the lextension IH `sind para-Heling air passage |20. The inner end of passage |68 intersects 1the passage |5| and receives air therefrom A(see also Fig. lo). The seat for valve i|61 is the shoulder at the intersection of passage |68 with its counterbore. The vvalve Vis held to this lseat 'by a spring |83, having a seat 'ina ping HB which is threaded into and closes .the outer end of the counterbore. A yent passage lsee ralso Fig'. 10) connects the Lcounterbore vat a point :between the -valye seat and plug y|1|| with the exterior of extension IH, opening into the air chamber -i-n the upper part of .the fan housing. The Yforce exerted by spring IB@ .on 'valve |61 is variable by turning screw plug HB, which is accessible lfrom 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 l'l/z 4and i p. s. i.

,Secondary air is .supplied by Vthe fan I.through tubo 6. as will .be clear from Fiss. e and .8, Fixed to lthe tube vit at a point .intermediate its ends. as by :screws |72, is an annular :ri-ng |13, baume projecting .inwardly therefrom a .circular series of helical vanos A| i4. The :inner edges .of these venes engage the outer peripheral wall yof .a cylindrical tube |i5 and supi-Jort it in coaxial relation Awith tube Hi.. @The .front enel of tube U15 .is onen .and .terminates adjacent .slieiitly to .the rear o! the atoiniailie nozzlehe rear end .of tube |15 is .closed by a :plus |16. which is secured. to the tube os indicated which has a :rounded rear end to divert the air stream issuing from the out let .2A of the the. .polar passage -lr'il be. tween lthe tubes l E .and |75, As will be clear Yfrom Fie. 11 successive helical blades il! .the series overlap .so that ,all ,air vtravolti-ig tlno-ugl'i the l,annular passage |751 is engaged by the blades and Caused vto whirl as it .mo-.Ves forward .in such pas sage. The whirling air stream, emerging from passage |11 -isdeilectedtoward the ceutralsileam oi fuel and .airJ which is emitted .from the .nozzle orifice 1.45 by Vmeans of .a frusto conical air di rector HB .on the outlet .end .of :tube A| .6.. Substao tially .all the secondary .airis whirled as described. There is a Single .small vent passage .|19 (Fisce ands) formed :in plus .il .for .the purpose of preventing .the formation ofc vacuum .in the .interior of tube ,115. Except for the insignificant .amount of air enter-iris .tube ilo .through this yent pas.- sae'e, all the .secondary air Supplied by fan 3 .is whirled. The plus .|15 has a Control .Opening therethrough which receives .and closely fits the described .nozzle-.carrying tube |14. .A set screw |89., threaded in the plus |.f'|6ho1.ds tube H4 in place- Thus, the `varices ilisuzoport tube |15. the conduit .for secondary airond the oil conduit together with the ignition electrodes.

The ignition electrodes are .shown .at 18| .(Fies.. e1, 8 11),. They are mounted in insulators |82 which in turn .extend .through .holes in plus |76. Each insulator `is held in place by a set screw 18.3, .threaded in plus .H6 and acting against a @am Asplit sleeve |34 (Fig. 5), which .surrounds the electrodes.. .On theroar'erid .of .each electrode (ses. i .and .si is a mete-,1 seminaires .which progressively .increases in diaeooter rearwardly to form a cam. These cam terminals .|85 are engaged. one by each of two serios-pressed .mee

taille Dllmgors u|86 (Fig. 4j) mounted .in 4an 111511 lator |81, which is xed in bottom wall of casing 2| and carries the high tension terminals of an ignition transformer |88, which is mounted in the front half of the described box 22.

each of the spring-pressed plungers |36. It will be clear that, when the disk is unfastened and pulled rearwardly it will carry with it the assem- These terminals suitably connect electrically, one with bly 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 IB. This entire assembly can readily be removed from tube I6 for inspection, adjustment or re'- pair and may as readily be replaced in the tube. As this assembly is replaced the cam terminals I 85 engage and .force upwardly the spring-pressed plungers |86, thus remaking the electrical 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.r 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 IBB (Fig. 4), which is pivotally mounted at its lower end on a rod |90, suitably fixed at its ends in the side walls S and l 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 |9| having a knurled head |92, which is located outside the housing and by means of which the screw may be turned.

The front wall lll of the fan housing has an opening, through which the shank of screw |9| passes. The peripheral' wall of .this opening closely ts 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 |92. A coil spring |95, acting between the inner face of wall It and a washer |95 fixed to the screw. draws the head |52 against the rounded part |94. The screw is thus able to swing up and down about ball |33 as a fulcrum, as may be necessary as the screw lili is turned. The screw is threaded into a nut |3l, 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 2.2 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 200 and the reset butu ton 28| for the safety switch. This button is accessible through a hole 202 in the rear wall of casing 22 (see also Fig. 3). wires enter this casing through an opening 203 (Fig. 2) and a cable 2M (Figs. 2 and 3) extends from controls inside the casing to the motor 26.

In operation, when the motor 2B 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 |35. prevents oil from entering the nozzle until the primary air has been placed. under sufiicient pressure to overcome the force of spring 866 and move the diaphragm |55 1o 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 Ill and out through the open end of tube i@ will be established before valve |365 opens. Hence, when the valve does open, the oil issuing in radial jets through passages l5| of the nozzle will be met and impinged by jets of primary air issuing tangentially through passages ifl 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 |69, 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 iiies apart by centrifugal force into a cone-like spray of nely divided particles and fog-like form. The spray is met by a stream of secondary air, whirled by the turbulator vanes HM, and the mixture is ignited by a spark produced between the elecf trodes li. rlhe whirling of the secondary air produces a short and wide llame having much the shape of an umbrella, adapting it for use in small fire boxes. Combustion continues until the demand for heat is satisfied, when the motor 25 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 |66. y The oil flow is very quickly and sharply cut oir from the nozzle, preventing any dribbling therefrom. However, flow of primary air con? tinues 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 stop-ping interval 'of operation of the burner.

Itis to be noted that the conditions contributiing to combustion may all be accurately con# trolled. 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 Sil. 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 HEB, which controls the force of spring |69v which holds valve |61 closed. By by-passing some of the air, forced by the compressor into the passages iZ, ll, |63', and lli, the rate of flow of primary air and the pressure thereof may be varied. The air pressure at which the oil Valve i3d will open is regulable by turning the screw IM which varies the force of the spring ifi@ that holds the oil valve closed. The pressure of spring it@ must, of course, be somewhat less than the air pressure secured by adjustment of screw |13. The rate of flow of secondary air is adjustable by the swinging shut# ter |89 in the fan housing. .All'theadjustments 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 S5, after the one screw di which holds it in place has been removed.

As one illustrative example, to illustrate how small a nre the burner will produce, 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 l in two sectionsl 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 26 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 4 may be put in place and secured by the two screws l5. The top of the housing is then closed by fastening the transformer and control box 22 to the top of the upper section d by means of two screws 23. This leaves the opening in the end wall 4 of the housing and, through this opening, is passed the assembly of atomizing nozzle, electrodes, tube [15, primary air and oil pipes, the oil valve, oil-valveactuating means, primary air regulating valve land closure disk. When this unit is pushed into the housing and tube i 6, the tube |75 will` engage the inner peripheral edges of the turbulator vanes 114, 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 135 engaging the spring-pressed plungers |86 during the. last stage of inward movement of the unit. The closure disk llwill nally t into and close the opening in wall i4, after which the screws I8 are applied to fasten disk l'l in place and the assembly is complete.

It will be clear that the burner is readily disassembled for servicing. By removing screws I8 and disconnecting the air and oil pipes 53 and |519 at their unions H8 and l E9, respectively, the disk I'l may be removed, carrying with it as one unit, the atomizing nozzle, ignition electrodes, tube H5, oil valve, oil and primary air pipes, oil-valve 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 hasr 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, which is capable of manufacture at relatively low cost and yet provides for clean and efficient combustion under conditions that are accurately regulable, and which provides for convenient assembling and disassembling of parts and for convenient adjustment of ow rates and pressure of the air and oil.

What is claimed is:

l. In an air-atomizing oil. burner, of the type wherein oil and primary air are respectively supplied through inner and outer coaxial pipes to an air-atomizing nozzle, fixed to the outer ends of said pipes and located in one end of an openended draft tube through which secondary air is supplied to mix with the atomized oil emitted from said nozzle and wherein the flow of oil to said nozzle is controlled by a valve located in the inner pipe near the nozzle and having a rod extending through such pipe and xed to a diaphragm actuated in one direction by pressure of the primary air and in the other direction by a spring; a closure for the otherend of said tube having a recess in its inner face, a member located within said tube having a recess in its outer face and to which member the inner ends of said pipes are connected, said closure and member being ii-xed together and clamping between them the marginal portion of said diaphragm, the inner portion of the diaphragm separating said recesses one from another, said spring being located in the recess in said closure, said member having a supply passage for primary air communicating with the inner end of saidv outer pipe and with the recess in said member and an oil supply passage communicating with the inner end of said inner pipe,l and a spring-closed relief valve adapted to open on excess pressure of the primary air, said relief valve and its spring being mounted in said member, the latter having a passage connecting said air-supply passage to one side of said relief valve and a vent passage connecting the other side of said relief valve to the space within said draft tube.

2. An air-atomizing burner, as claimed in claim l, having means accessible from outside said draft tube for adjusting the pressure of both valve springs the one independently of the other.

HARRY F. TAPP. RICHARD NI. COCHRANE.

References Cited in the iilev of this patent UNITED STATES PATENTS Number Name Date 1,287,253 Discher Dec. l0, 1918 1,640,728 Scott Aug. 30, 1927 1,716,244 Sager June 4, 1929 1,716,325 Rogers June 4, 1929 2,489,823 Senninger Nov. 29, 1949

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