CA1057339A - Nebulizers and method - Google Patents

Abstract

Abstract of the Disclosure Pneumatic nebulizer and method for uniformly introducing variable small amounts of flowable liquid into a gas flow to form a stable dispersion having the appearance of a natural fog and consisting essentially of microscopic liquid particles of said liquid dispersed in said gas. The nebulizer comprises a mixing element for introducing the liquid in uniformly fine amounts into the gas flow. The mixing element, which preferably is a replacable unitary element, comprises two superposed members which provide therebetween at least one shallow liquid orifice, at least a portion of the surfaces of said members either being in conforming surface contact with each other in the area between the entrance and the exit of said liquid orifice during use, or being capable of flexing towards or away from such conforming surface contact in said area under the effects of the force of said liquid and/or said gas during use. The liquid orifice has its entrance in communication with a liquid supply chamber and has its exit in communication with a gas passage for metering uniform predetermined amounts of liquid into a gas flowing through said gas passage. The shallow liquid orifice is formed between the said superposed members by providing the surface of one or both members with at least one narrow shallow recess such as formed by a scratch, grind, etch, press, discontinuous coating etc., or by using a flexible member, to provide at least one shallow liquid orifice which has a depth of about 0.01 inch or less, during use for introducing uniform fine amounts of liquid from a liquid supply into the gas passage for admixture with the gas flowing from a gas supply.

Description

; CllO-~_ - ~ ~ S~7 '' m e present invention relates to improved pneumatic nebulizers, including humidifiers, fuel burners, carburetors, and to methods for producing an ultrafine stable dispersion of a flowable liquid in a gas using such nebulizers.
A varlety of pneumatic nebulizers are known to the art for the dispersion of flowable liquids in a gas. In general, , such devices are based upon the atomizer principle whereby the ;~ propellant gas is forced through a narrow orifice into contact with the liquid which is fed to the outer surface of the ;
orifice either by capillary action or gravity flow.
' Such known pneumatic neblllizers have several disadvantages. From the standpoint of effectiveness, most such nebulizers fail to provide a fog in which there is not substantial fallout of liquid unless an impactor, shroud or other barrier i8 provided in the path of the emitted spray to ~eparate out those dispersed liquid partioles having particle sizes above about 50 microns. -rn other words, such known pneumatic nebulizers cannot directly produce a fog having dispersed liquid particles having a maximum diameter of 20 microns or less but rather produce a fog or spray having a sub-stantial content of dispersed particles up to about 50 microns .
~ or more in size, , Nebulizers which feed the liquid by gravity or capillary action have the disadvantage that the supply of liquid must be unconfined in order to have access to the gas , orifice. Thus, in their basic form, such nebulizers are limited in the extent they may be moved during operation or tilted or inverted or vibrated without causing interrup~ion of the supply ; of liquid to the gas orifice and cessation of the fog.
.
~0 Another disadvantage of known gravity-feed and capillary action nebulizers is the inability to control and .. _ 1, . I ~
:
;' ' . .
~; - . .. .. . . . ..
.~, . .. . .

CllO~
~ ~ 5 ~

vary the liquid concentration in the dispersed fog, or such con¢entration can only be controlled and varied by varying the pressure of the propellant gas. Some nebulizers provide no control means and are unsatisfactory for use in applications where~ varying concentrations of liquid are required such as for ~arious degrees of humidity, densities of pai~t, concen-trations of fuel, and the like. In other nebulizers, liquid concentration can only be increased by increasing the pressure - of the gas flow. mis causes a greater volume of the gas to flow out of the nebulizer in a given period of time, which is a disadvantage in the case of confined areas being treated, such as face masks, patient tents, incubators, etc., where the increased gas volume requires compensation.
In other known nebulizers, where both the liquid and the gas are fed under pressure, it is possible to vary the concentratlon of the liquid by varying the pressure thereof relative to the gas pressure. However such known nebulizers are incapable of producing uniform ultrafine fogs for one or more important reasons. In some such nebulizers the width of the liquid orifice i~ either too large or is not stable or is ad~ustable. In the latter case proper ad~ustment can be made if the operator is experienced but such ad~ustment may be lost during operation due to the pressures involved or the flexibility and instability of the liquid passage.
The principal object of the present invention is to provide an improved pneumatic nebulizer which is capable of directly and uni~ormly generating an ultrafine stable fog of liquid particles, preferably having a maximum diameter of about 20 mi~rons or less and having an average diameter of 1~ microns or less, in a propellant gas.

- 2 -" .

CllQ~A
105'733~ -Another ob~ect of this invention is to provide an apparatus for generating an ultrafine fog of liquid particles in a propellant gas whereby the total weight of the li~uid -particles for a given weight of the propellant gas can be `
varied and contro~led within close limits independently of the pressure of the propellant gas.
Another ob~ect according to one embodiment of the present invention is to provide a pneumatic nebulizer in which all the li~uid supplied to the liquid orifice means is nebulized and dispersed as a stable fog, i.e. there is no liquid run-off and no drippage of liquid from the orifice means or from other parts of the nebulizer.
Another ob~ect of the present invention i3 to provide a pneumatic nebulizer having a confined liquid supply whereby the nebulizer may be moved, tilted, inverted or vibrated during use without interrupting the supply of liquid to the propellant gas or interfering with the fog emission.
It is yet another ob~ect according to one embodiment of the present invention to provide a pneumatic nebulizer which has a unitary mixing element comprising a fixed liquid passage and a fixed gas passage9 preferably having a sharp-edged gas orifice, the relative size~ of said liquid passage and said gas passage being predetermined and fixed, and said mixing element preferably being replacable when worn or contaminated.
These and other objects and advantages of the present invention will be apparent to those skilled in the art in the , light of the present ~isclosure, including the drawing in which:
; FIG. 1 is a perspective Yiew of a nebulizer assembly,. ..
according to one embodiment of the present invention, the elements thereof being shown spaced for purposes of illustration, , ., , . ~ . ' , CllO-~
` lOS~33~3 FIG. 2 is a diagrammatic cross-section of the nebulizer device of FIG. l, illustrating t~e elements in assembled position and in operation, FIGS. S and 4 are perspective views of nebulizer j~ discs suitable for use in the nebulizer assembly of FIG. l or FIG. 5, , FIG. 5 is a diagrammatic cross-section of a nebuli~er-burner structure accor~ing to one embodiment of the invention, ElG. 6 is a plan view o~ the baffle plate of the nebulizer-burner structure of FIG. ~ taken along the line ~-6, FIGS. 7 to 13 are perspective and side views of various mixing elements suitable for use according to different embodi-ments of the present invention.
FIG. 14 is a diagrammatic cross-section of a nebulizer-carburetor structure according to yet another embodiment of the present invention, and FIG. 15 is a plan view of the lower ring disc of ,` the nebulizer carburetor of FIG. 14.
,,, The present invention is based upon a number of principles and discoveries which are employed in cooperative . ,.
manner to provide an improved pneumatic nebulizer which accomplishes the ob~ects and advantages discussed hereinbefore.
; The most important discovery is that an ultrathin i~.
film of liquid may be formed by forcing the liquid with a contin-.
; UOU8~ uniform force through a small orifice between conforming surfaces which are in contact with each other or are adapted to - be brought into contact with each other by the pressure of the ,; . .
;, li~uid a~d/or the gas, sa~d orifice providing the smallest width or diameter which will pass said liquid, i.e. preferably 0.01~ inch or less, and that said ultrathin film of liquid will be dispersed as an ultrafine fog of said liquid when struck by :

~, CllO,-~ -105733~ :
a flow of gas, preferably flowing substantially perpendicular to said ultrathin film of liquid.
Another related discovery is that if the activated liquid enters the flow of gas substantially simultaneously with the dispersion of said gas flow into a large receptacle or open space, the expansion of the gas disperses the ultrafine fog of said liquid preventing the fine particles of liquid from coalescing into large droplets.
Another related discovery is that the amount of a liquid dispersed in a gas, i.e. the density of the fog created, can be varied and controlled within close limits independently of the pressure or volume of the gas by varying the rate of flow of the liquid which is fed to the gas flow through a confined stable orifice of restricted s~ze.
Still another related discovery is that a liquid will not drip from or form droplets beside an orifice having a width of 0.010 inch or less if a constant flow of gas of ~ufficient velocity is caused to contact the liquid as it exits said orifice and the flow of gas does not thereafter come into contact with any surface.
Still another related discovery is that if a gas is forced to flow with sufficient pressure through an orifice and a thin film of liquid is caused to enter the flowing gas as -the gas exits the orifice, a sonic shock wave will form in the liquid particle-gas flow exterior of the gas orifice. The sonic shock wave causes the small liquid particles in the liquid particle-gas ~low to undergo severe vibrations, breaking the ; liquid particles into even smaller particles.
FIGS. 1 and 2 of the drawing illustrate a unitary nebulizer device adapted to be connected to pressurized sources of a liquid and a gas to cause atomization of the liquid in the , . : . . , ~, . . .

CllO-A
; 11~5~33~
form of an ultrafine stable fog. The device 10 comprises a circular base plate 11 having a central opening 12 adapted to be connected to a pneumatic conduit 13 and having an offset open:Lng 14 connected to a liquid-supply tube 15. m e base plate i3 sealingly connected to a circular top plate 16 by means of a compressible outer ring gasket 17 and a compressible inner washer gasket 18 which sealingly confines between itself and the undersurface of top plate 16 circular nebulizer discs 19 and 20. Four bolts 21 and nuts 22 unite plates 11 and 16 with an adjustable pressure, due to the compressibility of gaskets 17 and 18. The p~ates 11 and 16 and gasket 18 are -~-provided with central openings 12, 23 and 24 respectively, and .: the nebulizer discs are also provided with central openings 25 and 26 which are smaller in diameter than openings 23 and 24 but larger than 0.01 inch, and which form a restricted gas orifice through which the gas from the pneumatic conduit 13 . must pass. A11 five openings are coaxial in the assembled device to form a gas-flow passage and the flow of the gas through the restricted orifice 26, 25 causes the gas to form a vena contracta at a distance beyond orifice 26 equal to one-half the diameter thereof, and then to expand in a pattern as illustrated by FIG. 20 As illustrated, the sealed confinement of gaskets . 17 and 18 between plates 11 and 16 provides a circular chamber 27 to which liquid supplied to the device through supply tube 15 has accessO
The circular discs 19 and 20 with their central openings 25 and 26 are spaced from each other in the assembled device e~cept in the areas of shims 28 on disc 20 which have a thickness of 0~010 inch or less. m e close spacing between CllO-A

the discs 19 and 20 provides a narrow liquid orifice 29 between the discs in all directions, which orifice 29 has its exit communicating with central openings 25 and 26 of the discs and has 'Lts entrance communicating with the circular chamber 27 between plates 11 and 16.
In operation, a gas is supplied under pressure through pneumatic conduit 13 so that it flows forcefully through openings 12, 24, 26, 25 and 23 and exits into the atmosphere, : forming a vena contracta and an unobstructed flow pattern as shown by FIG. 2. A liquid is supplied under pressure through supply tube 15 to circular chamber 27 where it is sealingly ;i confined except for escape through the narrow orifice 29 between discs 19 and 20, which orifice 29 opens into central disc open-ings 25 and 26 from all directions. The pressure of the liquid ,........................................................................ .
is sufficient to force the liquid through the orifice 29 where it undergoes severe swirling action due to the ~n-radial alignment of the shims 28. m e liquid is believed to also ., .
undergo severe "boundary layer turbulence" due to friction with the inner surfaces of the discs 19 and 20 before escaping into the area of the central openings 25 and 26 of the discs as an excited, very thin ~ilm of the liquid having a thickness of less than 0.010 inch, such phenomenon being described in the book Introduction to Hydraulics and Fluid Mechanics, by Jones, Harper Bros., New York (1953). Such turbulence causes minute, finite masses of the liquid in the thin film to swirl and eddy in an erratic manner in all directions and with various velocities. As the liquid emerges from the srifice, each of the innumerable, minute, finite masses of the liquid has its own independent velocity and direction.
It is at this point of greatest excitement and turbulence that the thin liquid film exits orifice 29 and is ''~'' .
;

Cllr ''``.
1~5~733~
exposed to the blast of the gas flow from pneumatic conduit 13.
The e!xcited, turbulent liquid film is immediately reduced to an ultrafine dispersion of liquid particles having an average diameter of 10 microns or less and carried through opening 25 by the propellant gas in the form of a stable fog. In the embodiment illustrated by FIG. 2, the thin liquid film enters the gas flow as the gas flow approaches its vena contracta and the liquid is reduced to the ultrafine dispersion. Thereafter the gas expands in a pattern, as illustrated, and flows unobstructed lnto the atmosphere due to the chamfered structure of orifice 23 of the top plate 16. If orifice 23 was not !' chamfered the gas flow might strike the inner surface of the orifice depending upon the gas pressure and the thickness of plate 16. This would cause the dispersed liquid particles to wet said surface and flow back into orifice 25 and would create a vacuum in orifice 23 above disc 19.
;According to the embodiment illustrated by FIG. 2, the bottom nebulizer disc 20 is formed of a flexible thin metal which distorts under the effect of the applied gas flow to further restrict the width of the orifice 29 between the discs ;in the area of central openings 25 and 26, thereby producing a still finer fog. The flexibility of the disc 20 causes the disc to return to flat condition when the gas flow is cut off, and the pressure of the gas and/or the liquid can be adjusted to produce any desired degree of flex of the disc 20 and therefore any desired reduced spacing between di~cs 19 and 20 and even se~ling contact therebetween in the area of central openings 25 and 26.
It appears that the improved performance of the ~ 30 present nebulizer devices is due to a number of important cooperative features. First the forcing of the liquid from ' .

CllO-A
~o~tj733~

between the closely-spaced, parallel nebulizer discs 19 and 20 causes the liquid to exit into the area of the central disc openings 25 and 26 as an exceptionally thin film having a thickness of 0.010 inch or less, more preferably a thickness of 0.003 inch or less, as determined by the spacing between the discs. The thin liquid film is in a prestressed condition - after being forced through the narrow orifice 29 into the area of the central disc openings, in which condition it is capable of being reduced to a multiplicity of extremely fine liquid ; 10 particles. In similar known pneumatic nebulizers where the .,.~
superposed members or discs are closely spaced but are out of contact with each other in the area between the entrance of the liquid orifice and the exit thereof or the entrance to the gas orifice and are not capable of flexing into or towards contact in said area, the width of the liquid orifice will vary because the precise narrow spacing required between the members or discs cannot be achieved with accura~y. mese problems do not ..
i~ occur in cases where the members or discs are in face-to-face contact or are capable of being forced into or towards such contact by the pressure of the liquid and/or the gas.
A second cooperative feature of the present devices is the provision of a continuous gas flow at an angle to, preferably substantially perpendicular to, the direction of flow of the liquid film which gas flow passes through the central disc openings and strikes the liquid film as it exits the orifice between the discs. m e introduction of the thin liquid film into the gas flow causes the thin liquid film to be blown apart ~; into a multiplicity of microscopic liquid particles having an average diameter of about 10 microns or less which are carried along in the gas flow.
''' ;, _ g _ .,.
-,:
'','' Cllf ~
105'7;~3~ ~
A third cooperative feature of the present device according to a preferred embodiment of the present invention is the abrupt restriction in the gas flow provided by hole 26 in disc 20 which forms a sharp-edged orifice. The gas flow pattern contracts as it flows from the relatively wide area under disc 20 through the relatively narrow area of hole 26 in disc 20. The gas flow pattern continues to contract for some distance beyond disc 20. The point of greatest contraction is known as the vena contracta of the gas flow pattern and ~, 10 is shown in FIG. 2 as the most narrow portion of the illustrated gas flow pattern. The gas flow reaches its greatest velocity at this point of greatest contraction and thereafter the gas flow pattern diverges. Because the gas flow pattern is contracting as it leaves hole 26 in disc 20, none of the molecules of gas which are part of the gas flow come into contact with disc 19 as the gas flow passes through hole 25.
This is because holes 25 and 26 are of the same diameter and as the gas flow pattern is contracting as it leaves hole 26, the gas flow pattern will have contracted to a diameter which is slightly smaller than the diameter of hole 25 by the time it passes through hole 25. Because the gas flow flows past orifice 29 at a slight distance from it, the gas does not ~- resist the exit of liquid from orifice 29. The present device may be operated with the fluid pressure in orifice 29 substantially below the gas pressure in opening 12.
A fourth co-operative feature of the present device is that it is not essential that the gas orifices through the discs b~ of the same diameter. For example, hole 25 in disc 19 of FIG. 1 or 2 may be of greater or lesser diameter than hole 26 in disc 20. If hole 25 is of greater diameter than ., ;

CllO-A
105733~ `
hole 26, the liquid will emerge from between discs 19 and 20 as a thin film and spread on the top surface of disc 20 around and about hole 26. A partial vacuum exists in the gas flow as it exits hole 26. The partial vacuum sucks the thin liquid film spread on disc ZO into the gas flow. If hole 25 is of smaller diameter than hole 26, the liquid will emerge from between discs 19 and 20 as a thin film and spread on the under-surface of disc 19 around and about hole 25. The gas passed through hole 26 in disc 20 presses against the film of liquid spread on the undersurface of disc 19. The gas flows along the ; underside of disc 19 to reach and eventually pass through hole 7 25, drawing with it the thin liquid film spread on the under-surface of disc 19.
A fifth cooperative feature according to a preferred embodiment of the invention, is the unobstructed passage of the liquid-particle-carrying gas flow into the atmosphere or into a larger chamber by excluding from the path of the air flow any portion of the device which could be contacted by the diverging gas flow pattern. Thus if the device has a top plate or other element beyond the central discs which would normally be contacted by the expanding gas flow the central orifice of such top plate or other element must be sufficiently large or must be outwardly cham~ered, as shown by FIG. 2, to prevent the gas flow from striking the surface of the plate or other element before it escapes into the atmosphere. Otherwise the dispersed liquid particles will strike and coalesce on that surface and increase in size forming droplets th~reon. Many of said droplets will be blown off the surface on which they form by the flowing gas,there-; by contaminatin~r with relatively large droplets the fine dispersed ~0 liquid particles contained in the flowing gas. In addition, if the expandin; gas flow pattern strikes the central orifice . -- 11 --'.' CllO-A
: 1~5733'3 of the top plate, some of said droplets will run down the sides of the central orifice and onto disc 19, eventually obstructing central opening 25. This is a second source of large liquid part~cles in the gas flow because the liquid which collects " in the area of the central disc opening 25 enters the gas flow and sputters from the area of the central disc opening 25 ";
' under the force of the gas flow as sizable droplets.
In cases where the escaping expanding gas flow pattern strikes a surface which is in continuous, closed association with the gas orifice, i.e. with central disc opening 25 of FIGS. 1 and 2, a partial vacuum is created in the area adjacent the vena contracta of the gas flow and this partial vacuum causes the gas flow to diverge faster than it would in open space, with the result that an increa~ed number of the dispersed liquid particles strike the surface, form droplets, etc., as discussed supra. However these disadvantages are avoided, according to the preferred embodiment of this invention, by forming the present nebulizer devices in such a manner that the pattern of the escaping gas flow, containing finely divided liquid particles, is permitted to undergo its normal expansion beyond the vena contracta and into the container or atmosphere being treated without striking any obstruction.
A sixth co-operative feature of the present device .
according to various preferred embodiments of the present invention is the forcing of the gas th~ugh its orifice with such pressure that a sonic shock wave forms exterior of the gas orifice in the liquid particle-gas flow, causing the liquid particles to undergo severe vibration, breaking the ; liquid particles into very fine particles.
In some instances where the ~tmosphere being treated is itself contained within a confined receptacle, such as in ' .:-, CllO-A
l~S7~3~

the case of automobile carburetors, face masks, etc., the advantages discussed above resulting from the unobstructed passage of the liquid-containing gas flow or fog must be compromised to some extent, but in all cases the liquid is in the form of a fine film or jet having a thickness of 0.010 inch or less when the gas flow contacts the liquid. The gas then flows into a larger area so that the gas may expand for at least some distance to permit at least a substantial percentage of the fine liquid particles to become widely dispersed.
As discussed supra the passage of the gas flow from a large space to a confined, narrow space as it passes from the space under disc 20 to the central opening 26 of the nebulizer disc Z0 causes the formation of a vena contracta and then a su~stantial dispersement of the gas flow, with attendant reduction in gas pressure. The thin liquid film or jet is partly in~ected and partly drawn into the gas flow in the vicinity of the vena contracta. This appears to cause -the already-thin film or jet of liquid to be torn apart by the fast moving gas in the vena contracta with resultant formation of exceptionally fine liquid particles to the ; apparent ex~lusion of liquid particles greater than about 20 microns in diameter and probably even to the exclusion of li~uid particles greater than about 10 microns in diameter.
The liquid particles are immediately dispersed by the expansion of the gas flow beyond the vena contracta. me emitted liquid dispersion has the appearance of a fine, stable fog.
It is an important requirement of the present invention that the gas flow must be continuous and of sufficient ~0 velocity that the liquid can be carried away from the area of the disc openings 25 and 26. Preferably the gas and liquid "
; - 13 -':

CllO-~
, . ~
~573~3~

supply are pressurized but this is not necessary in cases ` wher~e there is a vacuum in the receptacle or atmosphere being ; treated such as in the case of an automobile manifold. The manifold vacuum creates a suction in the area of the gas orifice and the liquid orifice, causing the gas, i.e. air, to be sucked through its orifice and causing the liquid, i.e.
gasoline, to be sucked through its orifice and dispersed into the air flow for dissolution and perfect combustion.
FIGS. 3 and 4 of the drawing illustrate other suitable flexible metal nebulizer discs 30 and 31, each of which may be substituted for lower disc 20 of the device of FIG. 1 to provide excellent results in association with the upper disc 19. It should be pointed out that the upper disc 19 may be omitted and discs 20, 30 or 31 may be used along in association with the undersurface of top plate 16 provided that said undersurface is smooth and the central opening 23 of plate 16 is in alignment with the central opening of said discs, such ; as opening 26 of disc 20.
The flexible disc 30 of FIG. 3 is provided with ridges 32 which may be formed by impressing the underside of the flexible disc in the areas shown. The height of the ridges 32 need be just sufficient to admit the fluid between the discs.
The flexibility of the disc and the adjustability of the tightness of plates 11 and 16 permits the disc to be adjustably compressed and/or separated, as shown by FIG. 2, so that the width of the orifice 29 adjacent the central disc opening, 33 of disc 30, will be 0.010 inch or less.
According to another embodiment disc 30 of FIG. 3 may be a flexible or non-flexible disc providsd with grooves or recesses 32 which may be formed by gouging or scratching the upper surface of the disc along its outer peripheral edge as .:

,. .

CllO-A
i ~ S ~ ~ 3 ~

shown. The grooves do not extend to central opening 33. The adjustability of the tightness of plates 11 and 16 permits the disc to be adjustably compressed so as to seal disc 30 against disc 19. The depth of the grooves 32 is such as to be sufficient to admit fluid from chamber 27 between disc 30 and disc 19 along their outer edge. m e liquid supply pressure may be adjustably increased to cause the liquid to seep as an extremely fine film between disc 30 and disc 19 to central openings 33 and ; 25 where the liquid comes into contact with the gas passing `through central openings 33 and 25 in discs 30 and 19. The liquid supply is totally shut off from the gas flow in this ; embodiment of disc 30 regardless of the pressure of the flow of gas in conduit ~3 when the liquid pressure is below that required to force the liquid to seep between disc 30 and 19.
According to yet another embodiment disc 30 of FIG. 3 is a non-flexible disc 30 with one or more grocves or recesses which may be formed by gouging or scratching the upper surface of disc 30. The grooves extend from the peripheral edge of disc 30 to central opening 33 to provide a continuous recessed passage. The ad~ustability of the tightness of plates 11 and 16 permits disc 30 to be adjustably compressed, sealing disc 30 against disc 19 except for the continuous grooves across ;, ; disc 30. The depth of the grooves need be just sufficient to permit the fluid to flow through the grooves. The grooves form a multiplicity of thin orific~s for the passage of liquid from chamber 27 into contact with the gas flow through the central disc opening 33 of disc 30.
'~ The flexible disc 31 of FIG. 4 is provided with a , diametric crease 34 which passes through the central opening 35. The crease 34 prevents the disc 31 from lying flat against :
,`; upper disc 19 of FIG. 1 so that a thin orifice space, similar '~

CllQ-A
lOS7~

to 29 of Fig. 2, is provided for the passage of the liquid from chamber 27 into contact with the gas flow. Washer gasket 18 deforms about crease 34 so as to perfectly seal dîsc 31 to gasket 18. The flexibility of the disc and the adjustability of the tightness of plates 11 and 16 permit the height of the crease 34 to be adjustably compressed, as shown by FIG. 2, so that the height of the thin orifice space formed by the crease will be 0.010 inch or less.
It appears that forming the liquid as an ultrathin layer between two fixed, contacting, parallel members such as the discs 19 and 20 of FIGS. 1 and 2 and plates 30 and 31 of FIGS. 3 and 4, and the introduction of the liquid in the form of an ultrathin film or jet at the point of contact with a continuous, uniform, expanding pneumatic force, is responsible for the ultrafine size of the resulting liquid particles as all of the liquid is bro~en into small particles and none of the liquid is broken into particles of larger size, as can occur when the liquid is unconfined or if the ga8 flow i8 interrupted or insufficient. As the liquid is confined to almost the point of its introduction to the pneumatic force, the present nebulize~
may be used in any position in space, including upside down, without any spillage or drippage of the liquid or any interrupt-ion of the spray activity. m us such nebulizers are useful as hand-held devices for the spraying of paint, l~quid fungicides and fertilizers and other materials where complete freedom of alteration of the spray direction is necessary.
; It should be pointed out that regardless of the direction of the spray action, it is preferred that the direction of the flow of the gas be substantially perpendicular to the direction of the liquid as it exits the thin orifice. This causes the vena contracta of the gas to form in a direction ;', ~ Cll~-`
~.~S733~ :
perpendicular to the direction of the liquid flow in those ~ -emboldiments of the present invention which utilize a vena i contracta, and produces the finest fog possible with the present devices.
The nebulizer of FIGS. 1 and 2 of the drawing, per se or incorporating the other mixing elements disclosed herein in place of discs 19 and 20, can be adjusted to provide the most perfect ultrafine fog for a wide range of viscosity of the flowable liquid which is being dispensed.
FIG. 5 of the drawing illustrates a nebulizer 40 which is preferred for use as a burner element such as an oil burner or the like. Nebulizer 40 has a base unit which may be similar in structure and function to the unit illustrated by FIGS. 1 and 2 of the drawing. m us the base unlt comprises a ; circular top plate 41, a circular base plate 42, a compressible inner washer gasket 43, a compressible outer ring gasket 44 and a mixing element comprising thin contacting nebulizer discs ~; 45 and 46 which are confined between the inner gasket 43 and the undersurface of top plate 41 in such a manner as to prevent relative movement or slippage therebetween. Discs 45 and 46 are provided with central openings or holes which are aligned ~ to provide a restricted, sharp-edged central gas passage 47.
J'.`,' The plates of the base unit are held together by means of four bolts 4~ and nuts 49 which are sufficiently tightened with an adjustable pressure to compress gaskets 43 and 44 and to ," .
urge the nebulizer discs 45 and 46 into intimate discontinuous surface contact. The upper surface of lower disc 46 is provided , .
with a series of spaced shallow radial recesses such as grooves or scratches which extend from the outer edge to the central opening and which are up to about 0.01 inch in depth and preferably are about 0.001 inch or less in depth. Alternatively .,, ~ - 17 -., ' ,: ' CllO--A
~ ~ S ~ 3 3~

discs 45 and 46 may be as illustrated by FIGS. 3 or 4 or 7 to 13 of the drawing. In all cases the conforming members or disc3 which form therebetween the liquid orifice comprising recesses, such as grooves, scratches, depressions, etched areas, uncoated areas, etc., or the area between spacing means such as shims, etc., have or are adapted to have contacting i areas between the entrance and exit of the liquid orifice, such as surfaces which are normally in contact or which are adapted to flex into contact during use, so that one or more liquid orifices of the smallest possible width are provided between the discs or plates to permit passage of the liquid as ultra-thin films or jets.
; The assembled lower unit provides a sealed circum-ferent~al liquid chamber 50 defined by the space between the inside surface of ring gasket 44, the outer edges of discs 45 and 46 and inner gasket 43 and the inside surfaces of plates ; 41 and 42. Plate 42 is provided with a hole 52 communicating ~ ,, with chamber 50 and with a liquid supply tube 51 adapted to supply the liquid to be nebulized, such as fuel oil, to chamber 50 under any desired pressure, Base plate 42 is also provided with a central hole ; 53 and has attached thereto an air supply conduit 54 adapted to supply air at any desired pressure through hole 53, through disc passage 47, and through the central hole 55 in the upper plate 41, the latter being beveled as shown at 56.
As with the nebulizer of FIGS. l-and 2, the supply of air under pressure through conduit 54 and liquid under pressure through tube 51 causes the air to pass through restricted gas passage 47 while the liquid passes as a thin film between discs 45 and 46 into the air flow. The liquid is dispersed as a multiplicity of fine particles as it enters the CllO-A
i~S733S~
air ~Elow in the area of the vena contracta of the gas within hole 55 of top plate 41 and subsequently broken into even finer partLcles as the fine particles pass through the sonic shock wave in the gas flow.
According to the improved embodiment of FIGS. 5 and 6, the base unit is provided with an overlying baffle plate 57 such as a reflective metallic plate having a central hole 58 in alignment with hole 55 of plate 41, baffle plate 57 being spaced from plate 41 by means of washers 59 to provide an air passage space 60 therebetween which communicates with the atmosphere. Plate 57 is provided with outer holes which communicate with the bolts 4~ as shown by FIG. 6, and nuts 49 are applied to secure plate 57 in place.
A combustion cone or chimney 61 is provided over baffle plate 57 in alignment with hole 55 of plate 41, plate 57 serving as the floor of the combustion chamber. Finally, an optional exterior chimney element 62 may be applied, the ..
~, latter being positioned to extend from the surface of the baffle plate 57 to a height greater than cone 61, as illustrated.
2~ The liquid particle/air flow exits central gas passage .,, 47 and forms a vena contracta which extends above disc 46.
me pressure in the vena contracta is substantially less than ~tmospheric pressure, thereby creating a partial vacuum in the area of hole 55. me air above plate 41 in the vicinity :
of hole 55 is aspirated into and becomes part of the liquid particle/air flow in the area of its vena contracta. The ~, spacing of baffle plate 57 and top plate 41 permits external ;~.
atmospheric air to be draw~ through air passage 60 therebetween - and enter the liquid particle/air flow as the latter exits ~0 Gentral hole 55 in plate 41. Baffle plate 57 and air passage 60 permits external atmospheric air to satisfy the partial CllO--A
lUS7;~
..
vacuum created by the liquid particle/air flow and prevents liquid particles and gas located above baffle plate 57 being drawn into the space below baffle plate 57. m us, when the nebulized liquid, such as fuel oil, is ignited within combustion cone 6~, it burns evenly and continuously entirely above baffle plate 57. m e fact that baffle plate 57 shields t top plate 41 from the flame and the fact that cool atmospheric air is drawn through air passage 60 prevents top plate 41 and discs 45 and 46 from becoming hot.
When the nebulized liquid, such as fuel oil, is ignited, part of it burns above combustion cone 61 and part burns within combustion cone 61, causing combustion cone 61 to become very hot~ me heat radiated inward from combustion cone 61 causes the fine particles o~ liquid fuel oil emerging from central gas passage 47 to vaporize almost instantaneously.
The vaporized fuel mixes perfectly in the combustion cone with the air which had passed through central gas passage 47 and the air which had been drawn through air passage 60 into ~ , the liquid particle/air flow. m e vaporized fuel burns with a uniform, translucent, nonluminous blue flame.
If a heat-resistant enclosure, such as metal chimney 62~ i5 placed over combustion cone 61, as shown in FIG. 5, much of the heat of the flame is radiated to chimney 62, causing the latter to glow red hot. It is necessary to provide a small passage for atmospheric air such as a series of c~rcumferential holes 63 near the base of chimney 62 to permit additional air to be drawn into chimney 62 and maintain an even continuous blue flams in and above combustion cone 6~.
Home heating oil (No. 2 fuel oil~ was burned at the ; 30 approximate rate of one pint per hour in a working model of the nebulizer shown in FIG. 5 and the exhaust gas analyzed ;

CllO-~
~1~S733~'~

with a BACHARACH Fyrite Co2 Analyzer. The exhaust gas contained 14.5% Co2 at a BACHARACH Smoke No. between 1 and 2, indicating near:Ly perfect combustion.
Since much of the air needed for complete combustion i8 drawn from the atmosphere through air passage 60 into the liquid particle/gas flow exiting central gas passage 47, only a relatively small amount of compressed air is required to " supply air conduit 54 with sufficient air to operate the nebulizer shown in FIG. 5 as an efficient fuel burner.
The structure of the nebulizer or burner device of FIGS. 5 and 6 makes it possible to use the device as a relatively small automatic, i.e. electrically-controlled, oil burner capable of burning fuel oil in a very efficient manner at a rate as low as about one pint per hour. m is is in contrast to currently-available automatic oil burners which burn a minim~m of approximately six pints of fuel oil per hour.
An important advantage of the burner device of FIGS.
5 and 6 is that it is possible to control the ratio of the amount of liquid fuel to the amount of the air (including air drawn from the atmosphere) in the liquid fuel particle/air ; flow passing into the combustion chamber above baffle plate 57, thereby permitting such ratio to be adjusted for perfect combustion. Home heating oil (No. 2 fuel oil) requires 107 lbs. of air (approximately 1,400 cubic feet at atmospheric pressure) be supplied to the flame for perfect combustion of each gallon of fuel oil burned. Combustion will be incomplete if insufficient air is supplied to the flame. If excess air is supplied to the flame, the flame temperature will be reduced - because heat is drawn from the flame to heat the excess air.
The rate at which atmospheric air i6 drawn through air passage '', ,~.
., Cll~-A

; ~ 0 5'7~ ~ ~
60 into the liquid fuel particle/air flow is directly related to the rate at which the liquid fuel particle/air flow flows from central gas passage 47. Because of this, regulating the rate at which liquid fuel enters the burner device through conduit 51 and regulating the rate at which air enters the burner device through conduit 54 regulates both (1) the rate at which liquid fuel particle/air flow (including air drawn ; from the atmosphere) enters the combustion chamber above baffle plate 57 and (2) the ratio of the amount of liquid fuel to the amount of air (including air drawn from the atmosphere) ; in the liquid fuel particle/air flow entering the combustion chamber.
Another important advantage of the burner device of FIGS. 5 and 6 arises from the fact that only a relatively small air pump is requ~red to furnish sufficient compressed air to the burner device to operate the nebulizer and to cause sufficien~
additional air to be drawn into and mixed with the liquid fuel particle/air flow for complete combustion. m is is so because a low pressure zone or partial vacuum is created in the liquid fuel particle/air flow as it exits the nebulizer orifice, due to the creation of a vena contracta, and atmospheric air is sucked into the liquid fuel particle/air flow as it exits the nebulizer. A relatively large air pump is required to operate prior known pneumatic atomizer-type oil burners because all ~- or almost all of the air required for combustion is forced through or around the atomizer or nozzle.
Another important advantage of the burner device of FIGS. 5 and 6 arises from the fact that the nebulizer orifice 47 is spaced from the flame, shielded therefrom by baffle plate 57 and cooled by atmospheric air drawn through air passage 60 and as a consequence remains relatively cool.

:;

CllO-~

1~ 5 ~
Many known fuel oil burner nozzles are exposed to heat and encounter problems because the fuel oil remaining in the nozzle when the burner shuts off evaporates leaving troublesome residue.
Yet another important advantage of the burner device of FIGS. 5 and 6 arises from the fact that the burning of the fuel oil occurs partly within the confines of combustion cone ; 61, causing the cone to become hot. The introduction of the fuel oil/air flow into the interior of the heated cone causes the fine fuel oil particles to almost instantaneously evaporate -and mix completely with the a:ir within the cone.
As can be understood from the foregoing, the mixing element used according to the present invention comprises two cooperating members having aligned transverse holes and having conforming surfaces which are in contact or are adapted to flex into contact, a portion of the surface area of one or both contacting members being provided with thin spacing means such as shims or with shallow recesses or interstices, or said members flexing together during use, to provide one or more thin liquid orifices between said members which communicate with a liquid supply chamber and with the aligned transverse holes, the members supportingly contacting each other in the area between the entrances of the orifices and the transverse holes either normally or under the effects of the passage of the liquid and/or the gas.
:, The cooperating members preferably are flat stainless steel plates or discs having a thickness between about 0.005 inch and .05 lnch. However the members may be of arcuate or ; other shape provided they have corresponding conforming surfaces which contact each other in supporting engagement over a portion of their surface areas lying between the entrances and exits of the liquid orifices or are sufficiently flexible to flex - 2~ -:`~
''' Cl10-4 1()S'73;~`

towards such contact during use. Similarly the members may be formed of glass, plastic or other inert~ liquid-impervious materials.
The cooperating members may be of similar or different th~ckness. For instance the top member may comprise plate 16 of FIGS. 1 or 2 and disc 19 may be omitted provided that the undersurface of plate 16 conforms to the upper surface of disc 20, and hole 23 is aligned with hole 26 in disc 20.
m e holes through the co-operating members may be of the same or different diameters. For instance, hole 25 in upper disc 19 of FIG. 1 or 2 may be of greater or lesser diameter than hole 26 in disc 20.
Also it is not necessary that the recesses formed in the lower disc or plate extend to the periphery thereof so long as it communicates with the liquid supply chamber.
For example the lower disc may be provided with a transverse liquid hole, spaced from the transverse gas hole, which -communicates with the liquid supply chamber.
The use of flexible orifice means, such aR contacting ; 20 members or discs formed of flexible impervious materlal such as thin steel, aluminum, plastic, or the like, represents an important embodiment of the present invention since the ability of the discs to flex to a substantially open or closed position under the pressure of the liquid flow or the gas flow causes the ; liquid to be supplied to the gas flow as the thinne~t film ,:~
possible~and results in the finest and most stable fog.
In cases where the discs are normally in spaced position, held a uniform small distance apart such as by means of a thin peripheral washer or the like, the flow of gas under ., .
pressure through the gas conduit causes the lower disc to be flexed up against the undersurface of the upper disc due to the : ~llO-A
~OS7339 restricted diameter of the gas opening in the center of the lower disc. m is narrows the liquid orifice in the area adjacent gas orifice and can cause it to close completely de~
pending upon the gas pressure and the degree of flexibility of the discs. The liquid is unable to pass through the restricted or closed liquid orifice unless the pressure of the liquid is increased to force it between the discs, i.e. to force the liquid orifice into the smallest open position which will permit the liquid to pass through to the central gas orifice into contact with the propellant gas. Alternatively the pressure of the liquid can be maintained low and the pressure of the gas can be reduced to reduce the pressure of the lower flexible disc against the upper flexible disc and to permit the discs to separate as they attempt to return to normal flat position. As the pressure is gradually reduced, the size of the orifice adjacent the gas orifice will reach a spacing, less than 0.010 inch wide, and possibly less than 0.001 inch wide at which the liquid will begin to pass there-through for contact with the propellant gas.
In cases where the discs are normally in contacting or closed position the liquid or gas must be supplied under sufficient pressure to flex the discs out of contact and provide the smallest possible liquid orifice which will permit said liquid to pass into the gas orifice. Liquid pressure may be used to force the liquid between the contacting discs while gas pressure may be used to push the top disc away from the .
bottom disc, in cases where the gas orifice opening of the top dis¢^is smaller in diameter than the gas orifice opening of ~;~
the lower disc and thus provides greater resistance to the gas flowing through the gas orifice.

CllO-A
105~335~

In the case of flexible discs which provide a thin liqu:id orifice only under the effects of applied liquid pressure and/or gas pressure, such discs may be free of spacing means such as shims or grooves or may be provided with partial spacing mean~ which are present at the entrance of the liquid orifice but which do not extent across the entire sur~ace of the disc to the exit of the liquid orifice or to the gas orifice. Thu~
the facing surfaces of the discs adjacent the gas orifice of the flexible discs are capable of coming into contact with each other to close the liquid orifice completely until an ad~ustment is made in the liquid pressure and/or the gas pressure.
Thus, for contacting or closely-spaced discs of any particular high degree of flexibility, the pressure of the liquid and/or the pressure of the gas may be adju~ted to flex one or both discs until the size of the orifice is the smallest possible space which will permit the liquid to pass. This is important because the greatest possible boundary layer turbulence occurs and the thinnest possible liquid film is formed under this condition and the finest possible fog is produced, regardless of the viscosity of the flowable liquid being dispensed. Low viscocity liquid such as water can be dispensed t' as ultrafine fogs through orifices of 0.010 inch or less in width or diameter whereas higher viscosity liquids such as heavy , , oils require more narrow ori~ices of 0.003 inch or less in width or diameter.
:~ .
Preferably the mixing element comprises a unitary ; element which is easily removable and replacable and which comprises upper and lower plates or discs which are attached to each other to prevent relative movement or slippage therebetween such as the embodiment of FIGS. 7 and 8 of the drawings. m us "' CllO-~
~05~339 if the mixing element becomes worn or contaminated it can be disca~rded and replaced with a new one. Attachment of the eleme!nts, or other means of preventing relati~e movement or slippage such as illustrated by FIGS, 9 and 10 of the drawings, is most important in cases where the trans~erse gas holes are not centered în the discs or plates, or where several gas holes are present, whereby alignment can be lost if the discs or plates move relative to each other. -FIGS. 7 to 13 illustrate other forms of mixing elements -- 10 which can be used according to the present in~ention.
Thus FIGS. 7 and 8 illustrate a unitary mixing element 70 such as a thin stainless steel plate which is folded over in a central position after one end thereof has been pressed, coated or shimmed to form smooth~surfaced flat raised areas 71 leaving therebetween spaced recesses 72. When the plate is folded over, as shown by FIG. 8, the undersurface of the top plate 73 makes intimate sealing contact with the raised surfaces 71 of the lower plate 74 whereby the only passages therebetween are the shallow recesses 72. In f~lded-over position the central opening 75 in plate 7~ is aligned with the central opening 76 in plate 74 to provide a gas passage wh~ch communicates with the recessed areas of the lower plate 74 to receive a thin film of liquid for nebulization.
FIGS. 9 and 10 illustrate a mixing element comprising ., correspondingly notched discs provided with a multipllcity of gas passages. Thus the upper disc 80 comprises four gas openings 81 and two opposed peripheral notches 82 corresponding in size and location to four gas openings 8~ and two peripheral notches 84 on the lower plate 85. The gas openings 81 and 8~ and the notches 82 and 84 are in alignment with each other when the discs CllO-~ ~
~oS7339 ::

80 and 85 are assembled, as shown in FIG. 10. The nebulizer device, such as the inner gasket washer 18 of FIG. ~ is pro~ided with means for extending into the aligned notches 82 and 134 to prevent relative slippage or rotation of discs 80 and 85, or this result may be accomplished by the washer 18 per se due to its compressibility in areas adjacent the nstches.
As shown, the lower plate 85 is provided with a series of spaced recesses 86 comprising fine scratches which extend -from the periphery of disc 85 and communicate with the gas openings 83 to convey liquid from the liquid supply chamber to the gas flow. Obviously, the nebulizer device must be so con~tructed that all of the gas openings are unobstructed by the gasket 18 and by the central opening 23 of top plate 16.
FIGS. 11 and 12 illustrate another mixing element f., comprising a smooth upper disc 90 haYing a central gas opening 91 and a low~r disc 92 having a central opening 93 and spaced recesses comprising diametric creases or presses 94 which pass < through the central opening 93. The creases 94 prevent the disc g2 from lying flat against upper disc 90 in the creased ; 20 areas so that thin shallow orifice spaces 95 are provided for the passage of the liquid from the liquid supply chamber into contact with the gas flow. The washer gasket 18 of FIGS. 1 and 2 deforms about creases 94 so as to perfectly seal disc 92 to gasket 18 while the upper surface of disc 92, adjacent the creases 94, contacts and sealingly engages the undersurface of upper disc 90.
FIG. 13 illustrates yet another mixing element somprising a smooth upper disc 100 having a central gas opening 101 and a lower disc 102 ha~ing a central opening 103 and an upper surface comprising a multiplicity of interconnected " recessed areas 104 of uniform depth surrounded by a multiplicity " .

.
, ,~
'',.

CllO-~
10573;~
of peaks or plateaus 105 of uniform height corresponding to the original thickness of the disc 102. Such disc surfaces may be formed by sandblasting or otherwise chemically or mechanically etching the surface in a uniform and controlled manner whereby the original thickness of the disc is substantially retained in spaced areas or plateaus 105 surrounded by valleys or recessed areas 104 which are interconnected and which extend from the periphery of the disc to the central opening 103, as illustrated.
Uniformly roughened surfaces of this type are particularly resistant to becoming clogged because of the myriad of liquid orifices which provide alternative routes or passages for the liquid.
Suitable surfaces of this type may also be formed by pressing the disc against a die having an inversely-corresponding rough surface or, in the case of plastic discs, casting or molding the disc against a casting or molding surface having an inversely-corresponding rough surface.
~` As an alternative means for forming spaced recesses , in the present discs or plates it is possible to apply a discontinuous layer of suitable material in a thickness of 0.01 inch or less to the surface of the discs or plates rather than removing surface material from the discs or plates. The end result is similar in appearance and function to the disc 20 of FIGS. 1 and 2, for instance, the raised areas or shims sur-rounding the shallow recessed areas 28 being formed by applying a uniformly-thin discontinuous coating of inert material such as synthetic resin or metal to the smooth surface of the disc.
This may be done using photosensitive resinous compositions which are exposed through a negative and then removed from the unexposed areas which will correspond to recessed areas 28, or ;

', :

CllO-A
lOS7339 by vacuum deposition of a metallic layer using a stencil to prevent deposition in the spaced areas which will correspond to recessed areas 28. The discontinuous coating may also be applied by speckle coating techniques where specks of suitable composition are sprayed onto the surface of the plate or disc to form a multiplicity of spaced peaks of uniform height equal to 0.01 inch or less over the entire surface of the plate or disc. A similar result may be obtained by applying uniformly-sized particles of heat-fusible powder to the disc surface, such as by electrostatic techniques, and then heat-fusing the particles to the disc surface to form spaced peaks which are 0.01 inch or less in height. Also discs or plates cast or otherwise formed with uniformly rough surfaces having raised areas and recesses of the required depth may also be used.
~; Other suitable methods will be apparent to those skilled in the art in the light of the present di~closure, and the discs of FIGS. 7 to 13 may be attached to each other as unitary elements.
FIG~o 14 of the drawing illustrates a carburetor nebulizer according to another embodiment of the present invention comprising a gasoline supply element 110 sealingly engaged within an air flow chamber 111. Chamber 111 consists of a pipe 112 such as a manifold pipe of an automobile engine having a restricted section 113. The gasoline supply element 110 is mounted within pipe 112 so as to emit gasoline at the restricted section 113 within the pipe.
Supply element 110 comprises a liquid supply conduit 114 which passes through the wall of pipe 112 to a supply of gasoline from outside pipe 112, a restricted flow member 115 which threadably engages the conduit 114, and a conical cap member 116 which threadably engages the restricted flow member CllO-A
`~ : lOS7`335~
.. .
115 to hold the cap member 116 down against the upper surface - of the restricted flow member 115.
The underside of the conical cap member 116 is provided with a gasket 117 having attached thereto a thin rigid or , pliable disc 118 while the top surface of the restricted flow member 115 i5 provided with an outer ring gasket 119 having ~ attached thereto a thin rigid or pliable ring disc 120 which ~' is provided with a series of recesses, similar to those present , .
on any of the discs of FIGS. 7 to 13, which provide liquid , 10 orifices between discs 118 and 120 having a fixed stable depth ~ of 0.010 inch or less.
."
In operation, the cap 116 is screwed into flow member 115 to compress gaskets 117 and 119 and urge the surfaces of discs 118 and 120 into intimate surface contact, When the engine is cranked to start, a vacuum is created ~n chamber 111, drawing gasoline through conduit 114 and air downward through pipe 112. m e gasoline is drawn through the passage 121 in restricted flow element 115, into circular chamber 122 and out through the narrow liquid orifice comprising the recesses 123 : 20 (shown in FIG. 15) between discs 118 and 120 into the air flow.
- The escaping gasoline forms a multiplicity of thin films within the circular space between the restricted section 113 of the pipe 112 and the exits of theliquid orifices 123 ' and explodes as an ultrafine gasoline fog upon contact with the air flow as the air forms it vena contracta and than . expands into the wider chamber of pipe 112 below the restricted pipe section 113.
; The ring disc 120, shown more clearly in FIG. 15 , .
. preferably comprises flexible stainless steel having a smooth flat contacting surface 124 and a downwardly-tapered centering lip 125. Surface 124 is provided with a multiplicity of . - 31 -,~;

CllO-A
iO57339 evenly-spaced radial grooves or recesses 123 which form the liquid passages or orifices and have a depth of 0.01 inch or less and preferably 0.003 inch or less. Surface 124 makes intimate contact with the undersurface of upper disc 118 of FIG. 14, which is also preferably formed of smooth flexible stainless steel. The periphery of disc 118 projects beyond the periphery of disc 120 and causes the gasoline exiting recesses 123 to be drawn into a fine thin film on the projecting under-surface of disc 118 under the effects of the partial vacuum (air flowing) within the vena contracta of the air ~low in the narrow gap between the outer edge of disc 118 and the restricted section 113 of pipe 112. Preferably the width of the narrow gap is adjustable, either by movement of pipe 112, section 113 thereof or supply element 110, 80 that the velocity of the air flowing past the liquid orifices can be varied independently of the amount of air flowing past the liquid orifices. In the event of contamination of the recessed areas 12~, the cap 116 , can be unscrewed and the contacting surfaces of discs 118 and -~
120 can be cleaned. If necessary either or both discs 118 and 120 can be replaced in simple fashion when damaged or worn.
As will be apparent to those skilled in the art, ~ariations may be made in the various structures illustrated by the drawing and the nebulizer mixing elements of one structure may be interchanged with those of the other illustrated structures, obvious slight modifications being made where necessary. m us the present invention encompasses the use of nebulizer discs or plates which make discontinuous contact with each other over a substantial portion of their surface areas or are capable of flexing towards or away from contact to provide a-t least one ~0 thin liquid orifice therebetween. me discs or plates may be ' .

CllO-~
~05~335~ `

of identical or different thicknesses and function with either a pressurized liquid or gas supply or a vacuum-drawn liquid or gas supply.
In all cases, the devices of the present invention pro~ide at least one and preferably a multiplicity of very shallow, narrow orifices between contacting discs or plates, each orifice being 0.01 inch or less in depth, and most pre-ferably less than 0.003 inch in depth to restrict the flow o~
a liquid into a gas flow so that the liquid forms a thin film or jet within the gas flow at a point where the gas if flowing at a substantial velocity. According to one embodiment, the contact between the plates or discs o~er the portion of their surface areas intermediate the entrances of the liquid orifices and the exits thereof or the gas orifice enables the plates or discs to support each other across their entire surface areas againqt flexing together in the areas of the narrow recesses and reducing the spacing in such recessed areas, thereby providing stable liquid orifices. According to another embodiment the plates or discs are flexible and are mounted either in contact with each other or closely-spaced from each - other. In the former case the pressure of the liquid and/or the gas causes the plates or discs to flex apart gradually until they provide therebetween the smallest possible liquid orifice which will permit the liquid to pass therebetween.
In the latter case the flexible plates or discs are adapted to ` be flexed together to close or seal the liquid orifice by means of the pressure of the liquid and/or the ~as, which pressure can then be relaxed gradually to permit the flexible plates or discs to flex apart gradually to form the smalles-t possible liquid orifice which will permit the liquid to pass therebetween.
:

.:
' CllO-A
05733~

It should be understood that the specific structures of the nebulizer devices set forth in the figures of the drawing ; are not critical except with respect to accommodating the present mixing elements and that variations will be apparent to those skilled in the art for purposes of simplification or modification of the devices to a particular use where size, shape, appearance or other factors are to be considered.
:

,:
"

:' '1'` :

'''' ..:

Claims (32)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a nebulizer device capable of reducing a flowable liquid to an ultrafine dispersion of liquid particles in a pro-pellant gas, comprising a liquid passage having an entrance and and exit orifice, said passage being adapted to permit a supply of liquid to pass therethrough and exit said exit orifice as a thin liquid stream, a gas orifice in communication with said liquid exit orifice and adapted to admit a continuous flow of gas into communication with the exit of said liquid passage whereby said flowable liquid which passes through said liquid passage forms a thin stream of said liquid which contacts said gas flowing through said gas orifice to form said ultrafine dis-persion, the improvement which comprises a mixing element com-prising two superposed members which provide therebetween at least one said liquid passage, at least one of said members being a flexible member and at least a portion of the surfaces of said members either being pressed into conforming surface contact with each other in the area between the entrance and the exit of said liquid passage during use, or being capable of flexing towards or away from such conforming surface contact in said area under the effects of the force of said liquid and/or said gas during use.

2. A nebulizer device according to claim 1 in which said mixing element comprises at least one removable, replaceable mem-ber.

3. A nebulizer device according to claims 1 or 2 in which said mixing element includes both said gas orifice and said li-quid orifice, each of said superposed members having at least one transverse hole which is aligned with a corresponding hole in the other member to form said gas orifice through said mixing element which communicates with said liquid orifice.

4. A nebulizer device according to claims 1 or 2 in which the superposed members of said mixing element are attached to each other as a unitary element.

5. A nebulizer device according to claims 1 or 2 in which said superposed members comprise a single plate which is folded over onto itself.

6. A nebulizer device according to claim 1 in which said mixing element comprises a pair of relatively flat members which have parallel, smooth, contacting surfaces which sealingly engage each other in the contacting areas, at least one of said members being provided with at least one recess comprising said liquid passage.

7. A nebulizer device according to claims 1 or 6 in which said liquid passage is a shallow recess comprising an area from which material has been removed from the surface of said member.

8. A nebulizer device according to claims 1 or 6 in which said liquid passage is a shallow recess comprising an impression made in the surface of said member.

9. A nebulizer device according to claim 1 in which each liquid passage comprises the space provided by an inert material interposed between said surfaces.

10. A nebulizer device according to claim 9 in which said inert material comprises a discontinuous coating present on the surface of one of said members to form a part thereof.

11. A nebulizer device according to claim 9 in which said inert material comprises at least one shim element inter-posed between said members.

12. A nebulizer device according to claims 1, 6 or 9 in which said liquid passage extends from the periphery of said mixing element to said gas orifice.

13. A nebulizer device according to claim 1 in which at least one of said superposed members has on the surface there-of a multiplicity of means which contact the surface of the other member in the area between the entrance and the exit of said liquid passage to provide spacing between said members in the order of 0.010 inch or less.

14. A nebulizer device according to claim 13 in which said means comprise raised elements on the surface of one of said members.

15. A nebulizer device according to claims 13 or 14 in which the spacing between said members is less than about 0.003 inch.

16. A nebulizer device according to claims 1 or 6 which further comprises means for varying the rate of flow of said gas through said conduit, predetermined variations in the rate of the flow of said gas causing various predetermined amounts of liquid and gas to combine in the gas orifice of said device to produce ultrafine dispersions having variable predetermined concentra-tions.

17. A nebulizer device according to claims 1 or 6 which further comprises means for varying the rate of flow of said liquid through said liquid exit orifice, predetermined variations in the rate of flow of said liquid causing various predetermined amounts of liquid and gas to combine in the gas orifice of said device to produce ultrafine dispersions having variable pre-determined concentrations.

18. A nebulizer device according to claims 1 or 6 in which at least one of said superposed members is a flexible member which is adapted to move into or out of contact with the other member to gradually further change the spacing of the li-quid exit orifice of said liquid passage under the effect of gradual changes in the force of said gas and/or of said liquid whereby the force of said gas and/or said liquid can be adjusted to provide the smallest spacing of said liquid exit orifice means which will permit said liquid to pass therethrough at the desired thinness.

19. A nebulizer device according to claim 1 in which said gas orifice is a restricted, sharp-edged gas orifice asso-ciated with a conduit which is adapted to supply a continuous flow of gas through said gas orifice whereby said flowable li-quid which passes from said passage and out said thin liquid exit orifice forms a very thin stream of said liquid which con-tacts said flowing gas.

20. A nebulizer device according to claim 19 in which said conduit terminates at said restricted, sharp-edged gas orifice and said device is devoid of any surface beyond said gas orifice which is capable of being contacted by said ultra-fine dispersion.

21. A nebulizer device according to claim 19 capable of reducing a flowable combustible liquid such as fuel oil or gasoline to an ultrafine dispersion of particles of said liquid in air, comprising a combustion compartment adapted to receive said ultrafine dispersion for combustion therein.

22. A nebulizer device according to claim 21 in which said combustion compartment overlies said gas conduit and is provided with a floor element having an opening adapted to per-mit said ultrafine dispersion to enter said combustion compart-ment, said floor element being spaced from the exit of said con-duit to provide means for permitting atmospheric air to enter said combustion compartment with said ultrafine dispersion through said opening in the floor element.

23. A nebulizer device according to claims 1 or 6 in which one of said superposed members of said mixing element extends beyond the other of said members to provide a surface between said liquid exit orifice and said gas orifice, said surface being adapted to permit the liquid exiting said liquid orifice to be drawn into a thin film thereon during movement of said liquid into said gas orifice.

24. Method for reducing a flowable liquid to an ultra-fine dispersion of liquid particles in a propellant gas com-prising the steps of:
(a) confining a flowable liquid within a chamber having an exit comprising the entrance of at least one liquid passage, said passage comprising the restricted spacing between two mem-bers having conforming surfaces, at least one of said members being a flexible member and at least a portion of the surfaces of said members either being pressed into contact with each other in the area between the entrance and the exit orifice of said liquid passage during use, or being capable of flexing towards or away from such surface contact in said area under the effects of the force of said liquid and/or said gas during use, said liquid exit orifice communicating with a gas orifice;
(b) causing said liquid to pass through said liquid passage and exit said exit orifice as a continuous thin liquid stream having a thickness of 0.010 inch or less; and (c) causing a continuous supply of gas to flow at suffi-cient velocity through said gas orifice and against said thin liquid stream which exits the liquid exit orifice to cause said thin stream to be reduced to said ultrafine dispersion of parti-cles of said liquid in said gas.

25. Method according to claim 24 which comprises apply-ing sufficient variable pressure to said liquid and/or to said gas to vary the amount of said liquid passing through said li-quid orifice relative to the amount of said gas passing through said gas orifice to vary the amount and/or concentration of said liquid particles dispersed in said gas.

26. Method according to claims 24 or 25 in which said gas orifice is a restricted sharp-edged gas orifice and said continuous flow of gas is forced therethrough so as to cause the formation of a vena contracta in said gas flow, and intro-ducing said continuous thin liquid stream into said continuous flow of gas substantially simultaneously with the formation of the vena contracta of said gas flow to form an ultrafine dis-persion of particles of said liquid in said gas.

27. Method according to claims 24 or 25 which comprises permitting said ultrafine dispersion of said liquid particles in said gas to be released directly into a larger receptacle without striking any solid surface.

28. Method according to claims 24 or 25 in which the pressure applied to said liquid and/or to said gas is gradually adjusted to cause said flexible member to flex and gradually change the spacing of said liquid exit orifice until a film of said liquid of any desired thinness passes therethrough.

29. Method according to claim 24 in which a compressible element is superposed with said members and in surface contact with said flexible member and adjustable pressure is applied sufficient to compress said compressible element against said flexible member to flex said flexible member into intimate sur-face contact with said other member.

30. Method according to claims 24 or 29 in which one of said contacting members has a surface which extends beyond the other of said members between said liquid exit orifice and said gas orifice, and said liquid is caused to pass out of said liquid exit orifice and to be drawn into a fine thin film on said extend-ed surface during movement of said liquid into said gas orifice.

31. Method according to claim 24 in which said liquid passage comprises the space provided by a discontinuous material present on the surface of one of said members.

32. Method according to claim 24 in which said liquid passage comprises a groove in the surface of one of said members.