US2539778A - Rotary, internal-mixing, air-atomizing nozzle for oil burners - Google Patents

Description

Jan. 30, 1951 H. o. GRIMMEISEN ROTARY, INTERNAL-MIXING, AIR-ATOMIZING NOZZLE FOR OIL BURNERS Original Filed May 3, 1947 INVENTOR HERMAN 0 GR/M/vz/sz/Y CZa/um. 9'

ATTORN Ys Patented Jan. 30, 1951 ROTARY, INTERNAL-MIXING, AIR-ATOMIZ- ING NOZZLE FOR OIL BURNIEBS Herman 0. Grimlneisen, West Springfield, Mass, assignor to Gilbert & Barker Manufacturing Company, West Springfield, Mass, a. corporation of Massachusetts Original application May 3, 1947, Serial No. 745,760. Divided and this application February 19, 1948, Serial No. 9,383

2 Claims. 1

This invention relates to improvements in atomizing nozzles which are especially adapted for oil burners and which are of the internal-mixing, air-atomizing type. v

This application is a division of my application Serial No. 745,760, filed May 3, 1947, now Patent No. 2,480,019, dated August 23, 1949.

The invention has for a particular object the provision of an improved nozzle in which oil and air are efiiciently mixed and from which the oilair mixture is emitted in a spray to be mixed with more air and burned.

The invention has for another object the provision in a nozzle of the type described, of an arrangement for expelling residual oil from the nozzle passages after the oil feed has been cut off, the arrangement including revolving the nozzle to throw oil from the oil feed passages of the nozzle into the air passage from which'it is swept out of the nozzle by a high velocity air streamv and including also a bellmouth outlet flaring outwardly from the nozzle orifice and adapted to remove oil therefrom by centrifugal force due to the nozzles rotation.

The invention has for another object the provision of a rotatable atomizing nozzle having an annular venturi, formed between two conical parts and converging at one end to a discharge orifice, and passages for the introduction of oil radially into the throat of the annular venturi and passages for the introduction of high pressure air into the other end of the annular venturi, whereby the oil fed into the throat of the annu Iar venturi is mixed with the high velocity air stream flowing through the annular venturi and emitted from the discharge orifice as an atomized spray.

The invention will be disclosed with reference to the accompanying drawings, in which:

Fig. 1 is a sectional elevational view of an atomizing nozzle embodying the invention; and

Fig. 2 is a fragmentary sectional elevational view, drawn to a larger scale, showing one way of mounting the nozzle for rotation and for supplying it with air and oil.

Referring to these drawings; Fig. 2 shows a portion of an oil burner with which the nozzle of this invention may be used. The burner includes ahorizontally-disposed tubular housing A, having a passage 4' through which a flow of primary or low pressure air is produced by a fan 5, rotatably mounted near the rear end of housing I. The front end of housing I is open but the rear end is closed by a housing 1 which in its rear face is recessed. to provide a chamber for a pump,

which supplies secondary or high pressure air to the nozzle. Secured to housing 1 is a hollow housing 12 and secured to the latter is a housing It. The housings l2 and it afford within them oil receiving chambers l5 and I6, respectively, separated by a suitable oil filter ll, clamped between the housings i 2 and I4.

Rotatably mounted in housing I and disposed coaxially of passage t is a shaft 2!, suitably supported, as by ball bearings 22 and 23. The bearing 22 is mounted in the pump housing 1. The bearing 23 is mounted in a tubular housing 24, integrally connected by inclined blades 25 to an annular rim 25, which is slidably engaged with a cylindrical Wall portion of passage 4. A pin 25 in housing I engages in a slot 26' in rim 26 to prevent the latter from'turning. The blades 25 form a turbulator serving to whirl the air forced through passage by fan 5. The fan 5 is fixed to shaft 2i, as by the set screw 2?. Keyed to shaft 2! is a driving pulley 28, which is held in axial position between a shoulder on the shaft and the inner race of bearing 22. The shaft 2| extends into the chamber It and has fixed thereto the rotor 29 of the ar pump. This rotor and the inner race of bearing 22, both fixed to shaft 2|, engage opposite faces of the bearing-supporting wall of housing I and thus hold the shaft against any substantial axial displacement therein. The drive pulley 28 may be driven-by a belt 32 from any suitable power source (not shown).

The shaft 2! serves to revolve the atomizing nozzle of the burner and contains within it the supply passages for air and oil. The front end of shaft 2i is turned down and threaded, as at 33 (Fig. 1), to receive a cap 34, which forms the outer part of the nozzle and which engages a shoulder 35 on the shaft. This can has a cylindrical inner wall 35 and a frusto-conical inner wall 3? which connects wall 36 to the outlet orifice 38 of the 1102"- e. This orifice has an outwardly flaring wall forming a small spinning cup. The front end of shaft 2! forms the inner part of the nozzle. This shaft is turned down to provide a cylindrical part 39, a frusto-conical part til, the outer surface of which closely fits the wall 3'! of the nozzle cap, and two frustoconical portions M and 62, each of diiferent slope and of a slope different from that of wall 31. Between these frusto-conical portions ll and 42 and the frusto-conical wall 31 is formed an annular venturi i3. A plurality of radial openings M connect the throat of the venturi to a central oil feed passage 45, which isformed in shaft 2t and leads from those openings rearwardly to" a larger bore 46 in the shaft (the rod 48 and packing 5|] is considered absent for the moment). This bore 46 extends to the rear end of the shaft (see Fig. 2). At the intersection of bores 45 and 45 is a square shoulder 41 (Fig. 1). A rod 48, having an axial passage 49 therethrough is pressed into bore 46 with its inner end pressing against an annular rubber gasket 50. The rod may be fixed to shaft 2| in any suitable way as by a set screw 48'. The other end of rod 48 extends beyond shaft 2| and through a sleeve bearing 5| in housing l2 into the oil chamber I5. Oil may thus flow through passage 49, the hole in gasket 50, passage 55, and to and through the radial jets 44 into the throat of the annular Venturi passage 43. The rod 48 has two longitudinal slots 52 at diametrically opposite locations in its external periphery. These slots are formed like keyways in a shaft and, when the rod 48 is in place in the bore 45, of shaft 2|, these slots form passages for conducting air from the air pump to the atomizing nozzle. These slots 52 extend from the bearing 5| nearly to the front end of rod 48, terminating just short of such end and communieating one with each of two inclined holes 53, formed in the threaded end of shaft 2| at diametrically opposite locations and opening into an annular chamber 54. This chamber communicates with the annular venturi 43 by means of a plurality of slots 55 formed in the frusto-conical part 40. These slots are inclined to the axis of revolution of part 49 so that air from chamber 54 will enter the annular venturi with a helical motion. The whirling air, as it advances in the annular venturi, increases in velocity until it reaches the throat of the venturi where it is met by oil ejected from radial passages 44 by the rotating inner part of the nozzle, The oil and air mix in the venturi forming an emulsion, which is allowed to expand as it advances, finally leaving the nozzle orifice in a finely atomized conical spray of air and oil. This spray meets and mixes with the whirling stream of primary air which is forced by fan 5 through passage 4 and which is turned into the spray by the cone 56 on the outlet end of the air tube The combustible mixture of air and oil will be ignited in any suitable way, as by an electric spark produced between a pail of spark electrodes 5! (Fig. 2). Air is drawn in by air pump rotor 29 through the filter l8, passage l1 and inlet port and forced out through port 15 into recess 74, slots 52 and passages 53 (Fig. 1) into the annular air chamber 54 of the ato-mizing nozzle. Oil

will be supplied to the chambers l6 and |5 and thus to the nozzle feed passage 49 by gravity fiow from a suitable source such as a constant level reservoir, not shown. The flow of oil to the chambers l6 and 55 will be delayed by a suitable control until the nozzle, air pump 29 and fan 5 are rotating at full speed and the flow of oil to such chambers is stopped before the nozzle and air pump. The control means for this purpose, the oil supply means, the air pump, ignition means and the driving means for all moving parts of the burner together with a control systern for such driving means, are all disclosed in the parent application above identified.

In the operation of the atomizing nozzle, on a demand for heat, the shaft 2| is immediately revolved to drive the air pump, fan and nozzle. In a very brief time, say about one second, these elements will be rotating at full speed and, soon thereafter, the pump will have established flow of air through the nozzle and flow of air through passage 4 outside of the nozzle at the desired rates. The air fed into chamber 54 by the air pump is forced through the slots 55 and caused to whirl as it enters the annular Venturi passage 43 (Fig. 1). As the whirling air streams advance in this venturi, their velocity increases until they reach the throat of the venturi. Subsequently, the velocity is reduced somewhat as the air streams advance to the end of the venturi and issue from the nozzle orifice 38. After the described air fiow has been established within the nozzle and the whirling air flow has been established through passage '5 outside of the nozzle, oil is allowed to flow into chambers l6 and I5 and will advance, under gravity head, through the central oil passage 49, 45, and when oil reaches the end of passage 45, it is thrown outwardly through radial passages 44 by centrifugal force aided also by the suction effect created by the rush of air at high velocity through the throat of the venturi across the outer ends of passages 54. The jets of oil, issuing into the whirling air stream moving at maximum velocity through the throat of the venturi, mix with the air and form an emulsion. This emulsion advances through the venturi and the mixing of air and oil continues as the mixture progresses and expands. The emulsion leaves the venturi and enters the outlet orifice 38, expanding in a conical spray. This spray is met by the whirling air stream outside the nozzle (Fig. 2). which stream is directed into the spray by cone 56 and caused to mix therewith. The combustible mixture is ignited by a spark produced between the electrodes 51 and combustion occurs and continues until the demand for heat is satisfied. When this occurs, the oil flow will be immediately cut oil. However, air continues to flow through the nozzle and outside the nozzle for a time to avoid smoky combustion. The oil remaining in the passages 44 (Fig. 1) will be thrown outwardly into the venturi by centrifugal force and such oil will be carried through the venturi by the rushing air stream and discharged through orifice 38. Any oil remaining on the outwardly flaring wall 38 will be thrown outwardly by centrifugal force and discharged by the knife edge terminus of the wall. The effect is to clean the surface 38 free of oil film and leave nothing there to carbonize from the heat reflected back on the nozzle from the hot walls of the combustion chamber after combustion has stopped. The continued movement of air at high velocity through the venturi, after the oil flow has been cut off, has the eiTect of wiping the walls of the venturi free of oil film. The nozzle is thus cleaned of oil back to the passage 45. In particular, the narrow passage of the venturi, the small orifice 38 and its cup like discharge mouth 38' are cleaned of oil to avoid carbonization and the resulting clogging of the nozzle passages from soot and the depositing of soot on the wall of cup 38. The continued fiow of air after cessation of oil flow, tends to cool the nozzle at a time when it is most needed to counterset the efiect of reflected heat from the combustion chamber. Also, the latter is thoroughly scavenged and to some extent cooled. There is never a time when oil can issue from the nozzle without meeting air streams moving at the rate necessary for complete combustion at full rate of oil flow. Consequently, smoky operation during acceleration and deceleration of the rotating parts, is avoided.

I claim:

1. An internal-mixing air-atomizing nozzle forv 5 oil burners, comprising, a hollow outer member having a discharge orifice, a coaxial conical recess with its smaller end intersecting the rear end of the orifice, and a coaxial cylindrical opening intersecting at its forward end with the larger and rear end of said recess; an inner member having a cylindrical part filling the other and rear end of said opening and a conical part located in and coaxially of said recess, the conical surfaces of said part and recess being spaced one from another and one such surface having two difierent slopes intersecting at an obtuse angle and forming with the other conical surface an annular venturi leading to said orifice, said venturi in longitudinal section converging from its larger and entrance end to a narrow throat and then diverging to said orifice, said inner memher having an oil passage extending longitudinally from its rear end forwardly toward but terminating short of its front end and a plurality of branch passages communicating at their inner ends with said first-named passage and radiating therefrom, said plurality of passages opening at their outer ends into the narrow throat of said venturi at a plurality of angularlyspaced points, said inner member having an air conduit therethrough connecting with the entrance end of said annular venturi.

2. An internal-mixing air-atomizing nozzle for oil burners comprising, a hollow outer member having a discharge orifice, a coaxial conical recess with its smaller end intersecting the rear end of the orifice, and a coaxial cylindrical opening intersecting at its forward end with the larger and rear end of said recess; an inner member having a cylindrical part filling the other and rear end of said opening and a conical part located in and coaxially of said recess, the conical surfaces of said part and recess being spaced one from another and one such surface having two different slopes intersecting at an obtuse angle and forming with the other conical surface an annular venturi leading to said orifice, said venturi in longitudinal section converging from its larger and entrance end to a narrow throat and then diverging to said orifice, said inner member having an oil passage extending longitudinally from its rear end forwardly toward but terminating short of its front end and a plurality of branch passages communicating at their inner ends with and radiating from said central passage and opening at their outer ends into the throat of said venturi at a plurality of angularlyspaced points, said inner member having a groove therein forming with a portion of the outer member an annular air chamber, and an air supply conduit leading to said chamber, and a series of helical blades on said inner member located between the annular air chamber and the throat of the venturi for whirling the air through the latter.

HERMAN O. GRIMMEISEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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