US 2984420 A
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Description (OCR text may contain errors)
May 16, '1961 J. w. HESSION, JR 2,984,420
AEROSOL DEVICES Filed Nov. 20, 1959 FIG.6.
. INVENTOR y JOHN W. HESSION JR.
ATTORNE United States Patent AEROSOL DEVICES John W. Hession, Jr., 9 Homewood Place, Darien, Conn.
Filed Nov. 20, 1959, Ser. No. 854,363
2 Claims. (Cl. 239-405) My invention relates to aerosol fog spray devices and more particularly to a new nozzle construction in which gas entering a frusto-conical chamber adjacent the final outlet orifice is induced to rotate at a high accelerating velocity and form a whirlpool, the converging center of which is adjacent a centrally located fluid dispensing nozzle.
The term aerosol used herein is commonly defined in the art as a frog or cloud of particles, either liquid or solid, which by reason of extremely small sizes and consequent small masses, will remain suspended in still air for varying periods of time depending on the size of the particle, in accordance with Stokes law for the rate of fall of a small sphere in a viscous fluid. To come within the aerosol range, a sample of the cloud under microscopic examination must show the largest particle to be no more than 50 microns in diameter, and the mass average of all particles in the sample to be not more than 20 microns. Since the particles increase in mass as the cube of the diameter, it is readily seen that if the mass average is for example, microns, nearly all of the particles must be Well below this figure if any particles on the order of 40 to 50 microns are found in the sample.
In general, purely hydraulic nozzles of conventional design are not capable of producing such fine particles except under conditions of impractically great pressures of 12 to 30 thousand p.s.i. Therefore liquids are generally diluted in the nozzles by air, steam, or combinations of gases, and generally compressed air is used, the objective being to produce a fog having the maximum amount of liquid at the finest possible particle average to the minimum amount of air compressed to the lowest usable pressure.
Most of the conventional high pressure nozzles being manufactured are designed to operate at about 40 psi. or more, relying on the high axial velocity of the liquidgas dispersion to achieve a satisfactory fog, resulting in a relatively large air-liquid ratio. The nozzle described herein on the other hand, although still in the high pressure class, is such as will produce the desired fine average size particles with an air consumption of only about /2 c.f.m. at about to p.s.i., to about .85 to 1.0 oz. per minute of liquid converted to aerosol.
An object of the present invention is to construct an improved aerosol fog spray nozzle operable at a pressure of about 15 to 20 psi. to give a relatively high percentage of liquid having extremely small particle sizes.
Another object of the invention is to simplify the construction of aerosol nozzles which are manufactured to extremely close tolerances by providing -a three part nozzle having means for accurately maintaining critical dimen sions therein.
A further object of the invention is to provide an improved aerosol nozzle by constructing a nozzle body having a frusto-conical shaped chamber in which a whirlpool of air is produced, the converging center of which is adjacent the centrally positioned liquid outlet, so that ice 2 the liquid is injected into said swirling air while same is accelerating.
Yet another object of the invention is to improve aerosol nozzles by providing a simplified assembly of parts which individually are readily machined to close tolerances and adapted to fit together to provide the required gas passages and chambers.
A still further object of the invention is to facilitate cleaning and assembly of aerosol nozzles by providing a three-part construction having chambers and passages which become readily accessible on disassembly.
For a more complete understanding of my invention, reference may be had to the accompanying drawing illustrating a preferred embodiment of the invention in which like reference characters refer to the parts throughout the several views and in which Fig. 1 is an enlarged longitudinal cross-sectional View of a preferred structure embodying the invention.
Fig. 2 is an elevation-a1 end view of the structure as seen from the line 22 of Fig. 1.
Fig. 3 is a cross-sectional view taken on the line 33 of Fig. 1.
Fig. 4 is a cross-sectional view of the orifice plate por tion of the structure of Fig. 1.
Fig. 5 is an elevational view of one face of the orifice plate as seen from the line 55 of Fig. 4, and
Fig. 6 is an elevational view similar to Fig. 5 but illustrating a modified construction.
Nozzles of this type are rather small, the small dimension across the hexagonal illustrated in Fig. 3 being preferably only about inch. In the drawing, the preferred aerosol device is illustrated as comprising a body structure 10 comprising a three part assembly of a nozzle body 11, an orifice plate 12, and a retaining collar 13.
The nozzle body 11 has a gas inlet recess 14 at one end preferably as illustrated and is preferably threaded as at 15, being adapted for connection with a pipe, conduit, or tube leading from any preferred source of gas pressure supply (not shown). The other end of the nozzle body 11 has an annular flat surface 11a in which is cut groove 16, communicating with the inlet 14 by means of longitudinally drilled passages17.
The nozzle body 11 also has a stepped fluid inlet recess 20 preferably adapted for the insertion of a fir tree type of fitting 21 suitable for connection with plastic or rubber tubing which leads from any preferred source of liquid supply (not shown) at atmospheric pressure. A longitudinal fluid passage 22 communicates with the fluid inlet 20 and terminates in an outlet opening 23 at the axial center of an outwardly extending nozzle tip 24, which is provided with an annular shoulder 25 accurately concentrically related to the outlet 23.
The orifice plate 12 is preferably constructed as illustrated in Figs. 4 and 5, having an annular fiat face 12a adapted to abut the flat surface 11a of the end of the nozzle body 11. A centrally disposed frusto-conical recess 3% preferably of about a 45 slope to the longitudinal axis is provided at the edge adapted to fit closely on the shoulder 25 of the nozzle body 11, thus piloting the nozzle tip 24 accurately concentrically in the frustoconical recess 30. This concentricity preferably should be within a tolerance not exceeding .001 inch for the most eflicient functioning of the device. The vertex of the frusto-conical recess 30 terminates at an axially straight outlet orifice 32. which is preferably about /2 the axial length of the frusto-conical means 30 and about .010 to .015 inch larger on the diameter than the end of the nozzle tip 24, said nozzle tip being axially spaced from the outlet orifice 32.
A plurality of slots 33 are also provided on the inner face 12a of the orifice plate .12, these slots extending tangentially outward from the edge of the frusto-conical recess 30 as illustrated in Fig. 5 to a position such as will intersect the annular groove 16 of the nozzle body 11 when the parts are assembled.
Fig. 5 illustrates the slots 33 as of a milled type, but coined depressions 34 as illustrated in Fig. 6 may be preferred in the interests of economical manufacture.
The nozzle end of the nozzle body 11 is externally threaded as at 35, and the collar 13 is provided with matching internal threads 36, and an internal shoulder 37 is adapted to abut an outer annular shoulder 38 provided on the orifice plate 12, such that when assembled, the orifice plate 12 Will be firmly clamped to the nozzle body 11 as illustrated in Fig. 1, their abutting faces serving to close the respective grooves and recesses so that. continuous gas passages are provided from the gas inlet 14 to the conical recess so that continuous gas passages are provided from the, gas inlet 14 to the frustoconical recess 30 and out the orifice 32, and the collar 13 serving to seal the juncture of the orifice plate and the nozzle body.
The axial dimension from the flat surface 11a of the nozzle body 11 to the outer end of the nozzle tip 24 is accurately held to within about .0005 inch tolerance of a dimension that will position the fluid outlet 23 a distance of about .004 to .006 inch from the orifice opening 32. Obviously this distance will be different if the assembly is a different size; that is, if the frusto-conical recess 30 is of a different slope or if the orifice 32 or nozzle tip 24 is of a diflerent diameter, but the positioning of the nozzle tip 24 within the frusto-conical recess 30 is a critical factor as will be described.
Gas under a pressure of about 15 to psi. being tangentially directed into the conical chamber 30 by the slots 33 or depressions 34, is caused to rotate, creating a whirlpool efiect within the recess 30. The angular velocity of the gas increases as it approaches the converging center just at the orifice 32. As is seen in Fig. 1, the closeness of the nozzle tip 24 to the orifice 32 provides a restriction just at this position, where the gas is still accelerating, creating an area of optimum low pressure adjacent the fluid outlet 23 which serves to aspirate fluid which is at atmospheric pressure into the rapidly spinning vortex of the whirlpool, effectively breaking the fluid up into minute particles of the size desired. The still rotating mixture of gas and fluid then moves axially out the orifice, where the combined eifect of sudden expansion, high axial velocity and centrifugal forces cause an immediate dispersal, such that the rapid increase in microscopic distance between fluid particles reduces any tendency to coalesce.
As noted before, the positioning of the nozzle tip 24 is critical. When the tip 24 is too close to the orifice 32, the axial motion of gas past the tip is too great and will not eflectively intersect the fluid being drawn outward in time to produce the desired breakup of fluid into particles small enough to form a fog as heretofore described. Moreover, at this point the gas is no longer accelerating. When the tip 24 is too far from the orifice, it is too far inwardly 'of the converging center of the whirlpool, such that the angular velocity of gas is not great enough to produce the desired disassociation of fluid particles. The fact that the suction at the tip rapidly goes to positive pressure is important, since the nozzle is intended to aspirate the fluid without the aid of pumps or other devices.
It will be apparent that the particular dimensions noted herein as being critical will of course be somewhat different for devices of a different size and/or purpose. The main concept of the particular relationships of parts is to provide a fluid outlet at atmospheric pressure positioned at that part of the accelerating whirlpool of gas formed in the conical recess which causes an optimum suction on the fluid outlet and produces the most eflicient disassociation of fluid into particles of the size desired.
Although I have shown but one preferred embodiment of the invention, it will be apparent to one skilled in the art to which the invention pertains that various changes and modifications may be made herein without departing from the spirit of the invention or the scope of the appended claims.
1. An aerosol fog spray device comprising a body structure having a gas passage adapted for connection with a source of gas pressure supply, said structure having a frusto-conical chamber and an axial outlet orifice openly connected to the vertex thereof, said structure further provided with intermediate gas passages openly connecting said first passage with the larger end of said conical chamber, said intermediate gas passages being constructed and arranged to impart rotary motion to gas passing into said frusto-conical chamber to produce a swirling of the gas therein about the axis thereof with the converging center at the vertex adjacent the inner end of said outlet orifice, said body structure having a nozzle element extending axially and concentrically within said frusto-conical chamber and provided with a fluid passage terminating at a fluid outlet opening disposed within the frusto-conical chamber and spaced axially inwardly of the inner end of said outlet orifice a predetermined distance, said nozzle element constructed and arranged to provide a constricted annulus in said conical chamber adjacent to and concentric with respect to said fluid outlet, and said fluid passage being adapted for connection with a source of fluid supply, said outlet orifice comprising a cylindrical passage of an axial length of about one-half the axial length of said frusto-conical chamber, said frusto-conical chamber having a slope angle With respect to the axis of about 45 degrees, said outlet orifice being about .010 to .015 inch larger on the diameter than the outlet end of said nozzle element, and said fluid outlet being disposed about .004 to .006 inch inwardly from the inner end of said orifice.
2. An aerosol fog spray device comprising a nozzle body structure and an orifice plate structure adapted to be secured to one end of said nozzle body structure, said nozzle body structure having a gas passage adapted for connection with a source of gas pressure supply and with an annular groove in the end facing said orifice plate structure, said orifice plate structure having a centrally disposed conical recess in the side facing said nozzle body structure and axially spaced therefrom to provide a frusto-conical chamber, an axial outlet orifice openly connected to the vertex of said frusto-conical recess, said orifice plate structure having grooves in the side facing said nozzle body structure and arranged to communicate the larger end of said frusto-conical chamber with the annular groove of said nozzle body structure, said orifice plate grooves constructed and arranged to impart rotary motion to gas passing from said annular groove into the larger end of said frusto-conical chamber to induce the gas to swirl therein with the converging center of the swirl adjacent the inner end of said outlet orifice, said nozzle body structure having a nozzle element extending axially into said frusto-conical chamber and provided with a fluid passage terminating at a fluid outlet opening disposed within saidfrusto-conical chamber and spaced axially inwardly of the inner end of said outlet orifice a predetermined distance, said nozzle element constructed and arranged to provide a constricted annulus in said frusto-conical chamber adjacent to and concentric to said fluid outlet, and said fluid passage being adapted for connection with a source of fluid supply, said orifice plate structure having an annular recess ,in the portion facing the nozzle body structure, said nozzle body structure being provided with an extension having an annular shoulder adapted to fit closely within said annular recess, said annularrecess References Cited in the file of this patent UNITED STATES PATENTS Reichenbach July 28, 1925 Kraps June 26, 1945 Simmons Aug. 28, 1951 Gustafson Dec. 30, 1952