US2405196A - Oil burner - Google Patents

Description

m1611946. D. C. ELUOT 'my 2,405,196

RNEYS Aug 5, 1946 D. c. ELLIOT` ETAL 2,405,196

' OIL BURNER Filed May 11, 1944 3 Sheets-Sheet 2 ATTO R N EYS 'Aug 6 1946- l." c. ELLIOT ETAI.- 2,405,196

OIL BURNER Filed May 11, 1944 s sheets-sheet s `mvE'N-romi .Zio/mw Eu/or Afm BY OFDM E PAW.

ATTORN EYS Patented Aug. 6, 1946 OIL BURNER` Donald C. Elliot, West Springfield, and Oreas H.

Paul, Chicopee, Mass., assignors to Gilbert & Barker Manufacturing Company, West Springfield, Mass., a corporation of Massachusetts ApplicaeonMay 11,1944, serial No. 535,034

(c1. s-1s) 3 Claims.

This invention relates to improvements in oil burners of the so-called gun type adapted for residential heating purposes as distinguished from industrial furnaces.

More particularly, the invention is concerned with improvements having to do with the manner in which the air is supplied to and mixed with a spray of atcmized oil issuing from a pressureatomizing nozzle. In general, the air is supplied in a stream, which whirls around and around the conical oil spray, mixing therewith and burning with a relatively short flame. It is well known that if the air is supplied to the oil spray in a whirling manner, a more nearly perfect mixture of air and cil result with better and more efficient combustion.

This invention has for an object to provide improved means for supplying the air to the oil spray in a whirling stream without turbulence and effecting improved distribution of it around the oil spray so that the resulting mixture of oil and air is substantially uniform and the name is of substantially uniform density throughout.

The invention has for another object to provide in a burner of the class describedan air tube of substantial length which is of circular cross section and smooth from its inlet to its outlet end and to provide in the inlet end of the tube a circular series of slots and a plenum chamber surrounding the slotted end of the tube together with means for forcing air into the plenum chamber and through said slots in a whirling stream of substantially uniform thickness and advancing such stream without turbulence' to the outlet end of the air tube to envelop a spray of oil issuing from a nozzle located in the tube at said outlet end.

The invention has for another object the provision in an arrangement such as has just been described, of slots which are helical with a steep pitch to assist in whirling the air and advancing it in the desired helical path.

The invention has for another object to combine with the slotted tube a valve sleeve movable on the tube to vary the effective area of the slots through which air may enter the tube.

A further object of the invention is to provide in the air tube a support for the oil nozzle andk The invention will be disclosed with reference to theV accompanying drawings, in which,

Fig. 1 is an elevational view, with parts in section and parts broken away, of an oil burner embodying the invention;

Fig. 2 is an end elevational View thereof;

Fig. 3 is a cross sectional view taken on the line 3-3 of Fig. 1;

f Fig. 4 is a sectional plan view taken on the line 1 -4 of Fig. 1;

Fig. 5 is a fragmentary cross sectional view taken on the line 5-5 of Fig. 1;

Fig. 6 is a fragmentary end view showing the cuter end of the air tube as it appears when its end closure is swung open; and

Fig. 7 is a fragmentary view of the air valve showing a diierent mounting of the same.

Referring to these drawings and first to Figs. l and 4 thereof; the burner includes an air tube I, through which all of the air for combustion is supplied to Ithe burner. This tube is of circular cross section and usually it is of uniform diameter, thus being cylindrical as shown. However, the true cylindrical form is not necessarily essential for all purposes. The important characteristic is that the internal peripheral surface of the ltube is smooth from end to end so that air, which is whirled as it enters the tube at one end, may advance through the tube in a. whirling layer or stream, hugging its smooth wall, and

may issue from the tube in a whirling stream' without turbulence. One end of :tube I is closed, as by a plate 2. The other end is open but usually carries a more or less conical air nozzle 3 which condenses the air stream and directs it inwardly toward the oil spray.

Such spray is emitted from a pressure-atomizing nozzle 4 located centrally of the tube, near its outlet end. This nozzle is carried by a longitudinally-disposed member 5, which forms a pari; of the oil supply conduit for the nozzle. To the rear endof member 5 is connected a pipe 6 which eX- tends rearwardly of the tube and outwardly therefrom, Vin a manner later to be described, for connectionY to an oil pump. Ignition electrodes 1 are also mounted in tube I with their spark gap located in operative relation with nozzle A. Each electrode has a conductor `Il which extends rearwardly of the tube and is supported by an insulating tube 9. These'insulators' 9 and the member 5 are properly located within the tube I by a support, which includes a central massilll and a plurality (preferably three) of pin-like members II, for engaging the inner peripheral surface 'of the tube'. This mass I0 is streamlined, having 3 the curved surface I3', to guide any air, which may advance in the central portion of the tube along the oil pipe 5, member or electrode insulators 9, outwardly toward the peripheral part of the tube to merge with the whirling stream. This guide insures that all the air in the tube is forced into the whirling.k peripheral layer which hugs the wall of tube I. The streamlined guide also directs the air smoothly as it leaves the pins and passes on toward the nozzle 4, preventing the eddies which might otherwise occur. The pins I i present very little obstruction to the whirling air stream. Except for the pins I I, there are no obstructions of a kind to create turbulence in the air stream. Very little turbulence is created by the not persist long enough to have any effect on the air stream at the location where it acts on the oil ,A

spray.

The air is admitted to tube I through slots I2 which are formed in the peripheral' wall of the tube near its closed end.` Each slot extends generally lengthwise ofthe tube and preferably is of the' helical form shown. The pitch V.of the helix may be right or left hand as desired. AThese slots are equally-spaced angularly around the tube in a circular series. Rotatably mounted on the tube I, near its outer end, is a sleev'eval've I3. Preferably, this sleeve has slots I3', Fig. 3, which match the slots I2 and register therewith when the valve is in lone position. The valve may be moved to various other positionsto partially close slots I2 (see Fig. 3) and cut down the eiective area of the openings through which air can enter tube I.

Air is fed into the described slots in a manner best shown in Fig. A fan I4 rotating in the direction of the arrow in a scroll chamber I5 forces air through the conduit I6 into a plenum chamber Il. This chamber completely surrounds the outer end of tube I and its only outlet is by way of slots I2 and I3 into tube I. The only inlet'to chamber I'I is by way of conduit I6, which is disposedv tangentially of the chamber, whereby the air entering the latter is caused to whirl around the tube and to enter through the slots as indicated by the arrows and continue to whirl in tube I, advancing in a helica1 stream, hugging the peripheral wall of tube I,` to meet the oil spray.V

The helical form of theslots is preferred as this will assist in the whirlingaction and in causing the air to travel forwardly in a helical path, as is desired. The valve may also be arranged as shown in pari; in Fig. 7. With this arrangement the air enters the slots more smoothly and produces a somewhat better whirling stream of air within the tube I. A Y

Referring now'more .particularly to the details of the exemplary apparatus, the scroll chamber I5, conduit I6 and part of the plenum chamber Il are formed in a casting I8, which is supported vertically by an adjustable leg I9 from a base V23 as will be clear from Figs. 1 and '2. This casting has y a at end wall 2l from which projects the marginal flange 22 (Fig. 3) which denes thechambers I5 and I'I and their connecting conduit I6. A thin plate 23is secured to flange 22 with a gasket 24 interposed between them,'as by a series of screws 25. This plate closes the scroll chamber recess in casting I8, except for an inlet 26, Fig. 1, opening axially ofrfan I4. It also closes the reber I'I. Fixed with this plate to the casting I8 is the end flangev of a tube 21 which encompasses part of tube I in spaced relation therewith, 'form-L.

.70.: cess in the Vcasting which forms'conduit I6 and' part of the recess which forms the plenum chaming an annular chamber which is part of the plenum chamber I'I, above described. This tube 21 is connected by a frusto-conical part 29 to a cylindrical sleeve 30 which closely ts tube I and closes one end wa11 of the plenum chamber. The sleeve 30 is fastened as by welding, to tube l and serves to support the latter from the panel-like frame casting I8.

The sleeve valve I3, Fig. 4, extends from the closure plate 2 to the part 29 and may be frictionally held in place between these parts. This sleeve valve I3 has an annular ring 3| of angle section suitably fastened thereto, as by welding. One face of this ring serves as a closure for plenum vchamber I'I while the other seats in a circular opening in the wall of casting I8. The clo- Sure plate 2 (Fig. 2) is large enough to close the last-named opening. This plate may abut the adjacent ends of tube I, sleeve valve I3 and ring 3l, as shown in Fig. 4. The end plate 2 is hinged as at 32 to a support 33, Fig. 2, xed as by screws 34 to a plate 35, which in turn is fastened by screws 38 to the casting I8. When closed, plate 2 is held in place by a screw 37, threaded into casting I8.

For operating the sleeve valve I3, a handle 38 is provided. The inner end of this handle is fixed, as by welding, to the ring 3l of the valve (Fig, 6). The ange 39 is recessedat 40 to4k enable handle 38 to move through the range necessary to move I8 beneath plate 35. The high tensionterminalsI of the transformer are'shown at 4I and their insulators at 42. When the cover plate 2 is swung open to expose the outer end of the air tube, the terminals 4I of the transformer move away from the ends of the conductors 8 and thus break the high tension circuit.

When closure`2 is open, the assembly'of nozzle 4, member 5, electrodes 7, conductors 8, insulators 9, streamlined guide I0 and support pins II,.may

be removed as a unit from tube I` by pulling out-v wardly on oil pipe 6 after the latter has iirstbeen disconnected at the union-'43 `(Fig.Y 1). pipe, at the outer end of tube I ,extends radially outward through a notch 44 in tube IV (Figf) slots 45 and 4G in sleeve'valve" I3 and ring 3|, respectively, and a notch 41 in flange 38. The slots 45 and 46 enable the valve'I3 to turn through the desired range. notch 4l enters a recess 48,V Fig. 4,in wall 2U,

which lies beneath closure plate 2, and extends upwardly to the union 43.'

An electric motor 49 islmounted on theframe i3 to drive the fanV I4 Aand an' oil pump. The Y motor casing is cylindrical and one end thereof lies in a circular opening 50 in the frame I8 but is spaced therefrom, A gutter 5I surrounds .part

of this opening 5B. The motor "has a series of' ears 52'Which Llie in this gutter. Each ear has a' rubber Ybushing 53 therein and on either side of the ear are 'rubber' washers 54'. A steel 'plate 55l of arcuate form closes the gutter v5I and ieper-'- forated to 'receive'screwsfonefor 'each ear.

Each screw passes throughplate4 55, and threadsv into the base'wall ofthe guttei'gl The plate 553 The oil Y The cil pipe 6, on Vleaving' closely fits the outer and circular wall of gutter I but it does not engage the motor casing although it comes very close to it. The motor is thus resiliently supported from frame I3.

The motor has a single long bearing yEil for its shaft 58. The rotor is indicated at 5g and the stator at til, The fan iii is fixed to the one end of shaft 58 which projects from the motor casing and it has its hub connected to the fan by a conical part el, which enables the motor bearing to lie partly within it. A substantial part of the motor casing lies inside the frame, thereby materially lessening the part which projects outwardly from the frame. The motor casing houses in its outer end a fuel-supply unit which includes the pump, pressure-regulating and cut-off valves and iilter and may, for example, be constructed as shown in the application of Virgil E. Duemler, iiled April l, i944, under Serial No. 529,048, which application is owned by the assignee of the present application. For the present purposes, it will suiiice to state that 62 indicates the pump, the outlet of which is suitably connected to the pipe e, and 53 its drive shaft.

The oil pump is driven from the motor through a speed-responsive coupling, comprising a drum Gli fixed to pump shaft t3, and a pair of weight segments S5, pivotally mounted on pins t6 fixed to the rotor. The coupling is shown in more detail in Fig, 5. A spring el' connects a pin t8 on each segment to the outer end of pivot pin 5E. Each segment has a suitable facing Sii to engage the inner periphery of the rim of drum da. It will be clear that as the motor reaches a certain speed. the centrifugal force acting on the segments will overcome the force of springs 6l and swing the segments outwardly, pressing their facings t9 against the drum and causing the latter and the pump shaft to rotate. The motor and fan are thus enabled to start up without the load of the oil pump and to acquire speed more rapidly than they wouid otherwise be able to do. Thus, the fan can have time to clear the dead air out of tube I and establish the desired whirling stream of air adjacent the nozzle before any oil issues from the nozzle. On deenergization of the motor, the coupling will soon operate to disconnect the pump, which will then stop almost instantly, while the fan it. will continue in motion due to its momentum and that of the heavy rotor 59. Thus, the emission of oil from the nozzle d will be stopped before the air supply in order to avoid poor combustion during the stopping interval of operation of the burner.

The frame i3 has a marginal flange 1I cf inverted U-shape to receive the correspondinglyshaped flange i2 on a cover 13. This cover has a slot I of inverted U-form to f t over the tubular wall 2l. The cover is connected near its upper end by a hook l5 on its inner wall engaging in an eye i6 on plate 23. The cover is further held in place by two screws ll', one adjacent each lower corner, which screws thread into the ange 'I I.

ln operation, on energization of motor 19, the fan It is brought nearly up to full speed before the speed-responsive coupling picks up the oil pump. The result is an establishment of substantially full air flow in sufficient volume and at suflicient velocity to create the desired whirling air stream at and near the oil nozzle 4 before oil issues therefrom in an atomized spray. lThis is an important improvement for the reasons fully pointed out in the copending application of Warren H. DeLancey, filed May l, 1944, under Serial No. 535,036, which application is owned by the assignee of the present invention and in which application said improvement is claimed.

According to the present invention, the air is admitted from the fan by passage IE5 into plenum chamber I1 in a stream which enters the plenum chamber and is subdivided into a plurality of streams, one for each slot of the circular series. These air streams enter the slots, one through each, and a much better distribution of the air eircularly is obtained than would be possible without it. Aside from uniform distribution ofthe air, the slots of the preferred helical form assist in advancing the air in a spiral path through the tube. That is, air which enters any slot, as indicated in Fig. 1 by the arrow in the case of one slot, is free to move forwardly (to the left as viewed in Fig. l) and the stream thus has a tendency to move in a helical path as is desired. The several streams passing through slots in tube I merge inside the tube in a single layer or stream of air which hugs the interior wall of the tube and advances in a helical path to the nozzle of the burner. The stream is substantially uniform in thickness due to the uniform feeding in of air through the slots at evenly distributed points around tube l. If any of the air flow lies inside the stream nearer the axis of tube I, the streamined guide iE! will direct it outwardly and into the stream and without'creating turbulence. As the air passes the supporting pins I I it has te be di- 'Vided to some extent but the obstructions offered by these pins are so small as to be negligible. The air unites after passing the pins II and the uniform annular stream is guided to the oil spray by the cone 3 and by the forward streamlined part of guide Iii. The air issues from tube l, whirls around and around the oil spray, enveloping it, penetrating it and mixing with it. The mixture formed is exceptionally uniform as evidenced from observation of the resulting flame which shows uniform density throughout. A solid mass of flame of uniform color throughout is obtained, indicative of a most effective and uniform mixing of the oil and air. These results are secured, it is believed, because the air when formed into a whirling stream at the inlet end of the air tube is uniformly distributed around the circular wall of the tube so that the air stream is of uniform thickness. Then the stream, so formed, is maintained in its formation while advancing along the tube to meet the oil spray, by making the tube smooth from end to end to avoid turbulence such as would destroy the uniform distribution of air in the stream. And the streamlined guide offers help if and when needed by insuring that all air which passes it lies in the stream. The desired results are secured by a substantially uniform distribution of air in the whirling envelope which surrounds the spray and this, 0f course, results in a flame showing uniform density at all parts of it.

We claim:

1. In an oil burner, an air tube having an internal peripheral surface which is smooth froml one end to the other, a closure for one end'of the tube, the other end of the tube being open and constituting the outlet for air for combustion, a pressure-atomizing nozzle mounted in the outlet end of the tube and adapted to emit a conical spray of atomized oil, said tube having in its periphery near its closed end and remote from said outlet a plurality of slots through which all the air for combustion is admitted to said tube, said slots extending generally lengthwise of the tube and being angularly spaced about the periphery of the tube in a circular series; a housing having near its" lower end a chamber enveloping the slottedvend of said tube, a scroll chamber near its upper end and a conduit between said chambers; and a fan in said scroll chamber, said conduit directing the air from the fan tangentially into said lower chamber whereby the air whirls therein around the slotted portion of said tube enters the tube through said slots and is uniformly distributed around the tube and formed into a whirling stream which is advanced through said tube substantially Without turbulence to mix with the oil spray from said nozzle.

2. In an oil burner, an air tube having an internal peripheral surface which is smooth from one end to the other, a closure for one end of the tube, the other end of the tube being open and constituting the outlet for air for combustion, a pressure-atomizing nozzle mounted in the outlet end of the tube and adapted to emit a conical spray of atomized oiLsaid tube having in'its periphery near its closed end and remote from said outlet a plurality of slots through which all the air for combustion is admitted to said tube, said slots being helical and angularly spaced about the periphery of the tube in a circular series; a housing having near its lower end a chamber enveloping the slotted end of said tube, a scroll chamber near its upper end and a conduit between said chambers; and a fan in said scroll chamber, said conduit directing the air from the fan tangentially into said lower chamber whereby the air whirls therein around the slotted portion of said tube enters the tube through said slots and is uniformly distributed around the tube and formed into a whirling stream which is advanced through said tube substantially without turbulence to mix with the oil spray from said nozzle.

3. In an oil burner, an air tube having an inte'rnal peripheral surface which is smooth from one end to the other, a closure for one end of the tube, the other end of the tube being open and constituting the outlet for air for combustion, a pressure-atomizing nozzle mounted in the outlet end of the tube and adapted to emit a conical spray of atomized oil, said tube having in its periphery near its closed end and remote from said outlet a plurality of slots through which all the air for combustion is admitted to said tube, said slots being helical and angularly spaced about the periphery of the tube in a circular series; a housing having near its lower end a chamber enveloping the slotted end of said tube, a scroll chamber near its upper end and a conduit between said chambers; and a fan in said scroll chamber, said conduit directing the air from the fan tangen` tially into said lower chamber whereby the air whirls therein around the slotted portion of said tube enters the tube through said slots and is uniformly distributed around the tube and formed into a whirling stream which is advanced through said tube substantially without turbulence to mix with the oil spray from said nozzle, a sleeve rotatably mounted on the tube and having helical slots to match the slots in the tube and to register with the tube slots when the sleeve is in one position, said sleeve being movable on the tube to vary the effective area of the openings through which air enters said tube.

DONALD C. ELLIOT.

OREAS H. PAUL.

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