US3473530A - Nebulizers - Google Patents

Description

Get. 21, 1969 N. N. URBANOWICZ NEBULIZERS 2 Sheets-Sheet 1 Filed June 21, 1965 FIG. 4

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INVENTOR. NICK N. URBANOWICZ mmw ma ATTORN EYS Patented Oct. 21, 1969 3,473,530 NEBULIZERS Nick Nikodem Urbanowicz, 151 Albion St., Brantford, Ontario, Canada Filed June 21, 1965, Ser. No. 465,672 Int. Cl. A61m /00; A611 9/00; 1305b 3/14 US. Cl. 128194 7 Claims ABSTRACT OF THE DISCLOSURE A nebulizer characterized by a nebulizing action which is gained by passing a carrier gas through a small aperture in a horizontally disposed plate surface on which has been formed a thin film of the liquid or fine powder to be nebulized. The nebulization results from the turbulence in the carrier gas as it emerges from the aperture and turbulence can be increased by the use of a bafii'e placed immediately above the aperture. A fine mesh screen may be placed on the plate surface to reduce surface tension in the film. Other embodiments employ a diaphragm plate surface which is vibrated by the gas passing through the aperture and a liquid reservoir beneath the plate subjected to the gas pressure to feed liquid to the plate surface.

This invention relates to the manufacture of nebulizing devices and is particularly concerned with a nebulizer which is not subject to clogging.

A nebulizer essentially consists of a device for atomizing liquids. Such devices have been used widely for many years as a means of creating beneficial atmospheres in sick rooms. In effect, the atmosphere breathed by a patient is used as a means for administering drugs through inhalation.

The majority of nebulizers now available on the market operate on the principle wherein air or oxygen or other base gas is forced through a venturi throat and the liquid to be atomized is drawn upwardly through a capillary tube having its upper end positioned at the venturi throat. The disadvantage of this arrangement is that the capillary tubes often become clogged after varying periods of usage, either through a build-up of solids precipitated from the fluids being nebulized or impurities inadvertently included in the fluids. More often than not, it is impossible to determine the likelihood of a blockage occurring in the capillary tube in advance and it is occasionally found that a patient who is supposed to be receiving medication through nebulization of the surrounding atmosphere has not been receiving medication due to clogging of the nebulizing device and this can on occasion have serious effects on the recovery of the patient. It is, therefore, most desirable in certain cases that nebulization be guaranteed.

A further disadvantage of the nebulizers now available is that they are capable of nebulizing only liquids. There has been a recent trend to the provision of extremely fine powders as medicants to be dispersed in the atmosphere. There are advantages to the dispersion of powders directly into the atmosphere as contrasted with first dissolving the powder in a liquid. Unfortunately, the presently available nebulizers are capable of atomizing only liquids.

It is the chief object of this invention to provide a nebulizer which does not employ the principle of passing the air through a venturi throat while drawing the liquid to be nebulized upwardly through a capillary tube as to avoid the danger of blockage of the tube.

It is a further object of the invention to provide a nebulizer which is capable of atomizing powders as well as liquids.

It is a more specific object of the invention to provide a nebulizer which in its simplest form consists of a receptacle adapted to hold liquid to be nebulized, which receptacle includes a bottom wall having at least one aperture extending therethrough and further including means for forcibly passing air or other carrier gas upwardly through the aperture whereby the gas picks up the substance to be nebulized at it emerges from the aperture.

The above and further objects of the invention will be understood from the following description of preferred embodiments thereof as read in conjunction with the accompanying drawings.

In drawings which illustrate these embodiments:

FIG. 1 is a frontal perspective view, partly broken away, of a nebulizer in accord with the simplest embodiment of the invention;

FIGS. 2, 3 and 4 are cross-sectional views taken along the vertical plane through modified forms of the nebulizer illustrated in FIG. 1;

FIG. 5 is a frontal perspective view, partly broken away, of a nebulizer in accord with a second embodiment of the invention;

FIG. 6 is a perspective view of a screen and an alternative diaphragm employed in the embodiment of FIG. 5; and

FIG. 7 is a cross-sectional view taken through a vertical plane of a further embodiment of the invention characterized by means for automatically feeding liquid to be nebulized.

Referring to FIG. 1, the nebulizer in accord with this simplest form of the invention essentially consists of a receptacle 10 adapted to hold a quantity of liquid to be nebulized in which the receptacle includes a bottom wall 12 having a single central aperture 14 extending therethrough and an air tube 16 connectible to a source of air under pressure and adapted to feed pressurized air upwardly through aperture 14. The connection of tube 16 to the underside of wall 12 might be effected by any one of a number of known ways. As illustrated, this connection is effected by enlarging the lower end of aperture 14, providing a female thread on the inside surface of this enlarged portion and providing a male threaded connector on the end of tube 16 and a suitable locking element such as 17. The wall of the receptacle is preferably extended downwardly beneath the bottom wall 12 simply to provide a footing for resting the nebulizer on a flat surface without interference from tube 16.

The substance to be nebulized, which in the normal course will be liquid but could also be a fine powder, can be fed into the receptacle in any one of a number of ways. Thus, for example, a fluid feeding device operating on the burette principle might be positioned above the nebulizer to drop liquid at regularly timed intervals through the open upper end of the receptacle onto bottom plate 12, preferably at such a rate to maintain a relatively thin film of the liquid on the bottom plate. Alternatively, the liquid or powder to be nebulized may be fed at a predetermined rate through a separate feeding tube 18 rather than through the open upper end of the receptacle.

It will be appreciated that nebulization of the liquid or powder resting on the upper surface of bottom plate 12, in the form of a thin film thereof, takes place as the air or other carrier gas emerges from aperture 14 with a certain amount of turbulence creating action sufiicient to break up the liquid into extremely fine droplets which are then carried by the air out through the open upper end of the nebulizer and into the surrounding atmosphere. In the case of powder, the action is not a true nebulizing action as the word nebulizer implies breaking a liquid into fine particles whereas with a powder, the fine particles already exist and the action is largely one of creating turbulence as to pick up the particles from a thin film thereof that has been formed on the top surface of plate 12 so as to disperse the particles through the carrier gas which will then carry particles into the surrounding atmosphere.

FIGS. 2, 3 and 4 show modified forms of the nebulizer illustrated in FIG. 1. These forms differ from one another primarily in the shape of the top surface of bottom wall 12. They are illustrated to emphasize the fact that the shape of this top surface is not critical, with the exception that extreme shapes such as those which would make it impractical to feed the substance to be nebulized to the outlet orifice of aperture 14 at an even rate could not be used.

For the purposes of illustration, aperture 14 is shown in the drawings much larger in diameter than would be actually employed in a bottom plate of the dimensions shown in the drawings. It is to be noted, however, that apart from the fact that the aperture must have a diameter no less than a certain practical minimum size, the diameter and even the shape of the outer orifice is large ly determined by such considerations as the overall size of the nebulizer concerned, the nature of the substance being nebulized and the pressure under which the air or other carrier gas is forced upwardly through the aperture. For all practical purposes, however, the minimum operative diameter of the aperture (more specifically, the outlet orifice) is in the order of 0.0005 inch. It is also to be noted that while the forms of the invention illustrated in FIGS. 1 to 4 all employ a single, centrally positioned aperture, two or more apertures may be used provided, of course, that means is also employed for forcibly feeding air or other carrier gas upwardly through each of the apertures. In this regard, it is mentioned that in accord with the invention, nebulization of a liquid or pickup of fine powder particles is believed to be the result of turbulence created within the liquid or powder receptacle and with certain liquids or powders, the proper amount of turbulence might be better effected by the use of a plurality of apertures rather than the single aperture illustrated.

The embodiment of the invention illustrated in FIG. employs several refinements on the simple form of the invention illustrated in the preceding figures. In this case, the receptacle is formed of two parts, namely a base 20 on which an upstanding cylindrical part 22 is removably fixed as by the use of holding screws 24. One advantage of this two-piece arrangement is that the bottom wall, which in this case takes the form of a thin metal membrane, may be readily removed from the nebulizer for cleaning or replacement. Thus, for example, it might be desired to change the bottom wall from one having a single aperture such as shown in FIG. 5 to one having a plurality of apertures such as shown in FIG. 6.

In using the membrane type of replaceable bottom wall, as shown in FIGS. 5 and 6, it is not practical to directly connect the air feeding tube 16 to the underside of the bottom wall. Accordingly, the lower half 20 of the receptacle is provided with an air chamber 28, with the tube 16 being connected to chamber 28 through a vertical bore 30 and a horizontal bore 32 in the lower end of portion 20. With the use of an air chamber and a relatively thin bottom wall 26, it has been found that as the air is forced under pressure upwardly through the aperture in the wall, the latter is caused to vibrate at a very high frequency. It is believed that this action assists in both urging the liquid to be nebulized across the top surface of the bottom wall towards the aperture and in creating additional turbulence to assist break-up of the liquid into fine droplets. It is also found that movement of the liquid towards the aperture is assisted by the use of a fine mesh screen 34 on top of the bottom wall. It is believed that the effect of this screen is to break up surface tension between the thin film of fluid being nebulized and the top surface of the bottom wall which can have the tendency to retard movement of the fluid towards the aperture or apertures. Screen 34 is also held in place between the lower edge of the top portion of the receptacle and the mating portion of the lower part 20. As previously mentioned, the two parts of the receptacle can be separated which also provides access to the screen as well as the bottom wall 26 for cleaning or replacement. The screens illustrated in both FIGS. 5 and 6- are provided with a central slot 36 to expose the aperture or apertures. In fact, any suitably shaped opening in the screen may be used, it only being required that the egress of air from the upper orifice of the aperture should not be interfered with by the screen.

The embodiment of the invention shown in FIG. 5 further differs from the simpler form of the invention illustrated in FIGS. 1 to 4 in the use of a baffie 38 which is positioned above but somewhat spaced from the outlet orifice of the aperture. The use of such a battle is a preferred expedient as it has been found that more often than not improved nebulization will be gained by the use of a baffle which is believed to have the elfect of providing additional turbulence within the lower end of the fluid holding receptacle. Baffles of various shapes and sizes have been successfully employed and it does appear that the actual shape of the baffle is not critical, provided the selected shape does accomplish the desired creation of additional turbulence. The bafile illustrated simply consists of a rod-like member which extends across the lower end of the receptacle directly above the aperture. The rod might be made of any one of a different number of materials but, as with all the materials used in the nebulizer, it should be of a material capable of being cleaned, having in mind the ultimate purpose of the nebulizer which is to provide beneficial atmospheres to be breathed by hospital and other sickroom patients. Thus, for example the baflie would preferably be manufactured of glass, stainless steel or a hard plastic. As illustrated, bafile 38 is held in position by means of a pair of screws 40 which hold the ends of the bafile against the underside of a flange 42 carried on the inside surface of the wall of receptacle 22. However, it will be appreciated that various alternative means might be employed for mounting the bafile at the desired position. Further, the baflie may be mounted in such a way to permit adjustment of its height above the aperture. In using a diaphragm type bottom wall such as the member 26a shown in FIG. 6 and having a plurality of apertures, the baflle would be properly oriented as to be positioned above each of the apertures. Similarly, in using a bottom wall having a number of apertures which are not necessarily arranged along a single line, the baffle means employed will be shaped and sized as to be positioned over each of the apertures. It has been found that the actual size of the baflie is not critical, although it will be appreciated that a bafiie which is so large as to virtually block off upward flow of air emerging from the aperture or apertures would not be acceptable. Thus,, it has been found that, generally speaking, the lateral dimension of the baflie relative to the size of the aperture should not exceed a ratio of approximately 7 to 1. The term lateral dimension could have different interpretations depending upon the shape of the bafile concerned and in the case of a rod-like baflle, such as the one illustrated in FIG. 5, it is the diameter of the rod which would be described as the lateral dimension. Should the baflle selected comprise a square plate, the lateral dimension would be the same as the length dimension. Generally speaking, therefore, the lateral dimension will constitute the smallest dimension impeding upward flow of air emerging from the aperture over which the batfie is positioned.

Referring now to FIG. 7, the nebulizer according to this embodiment of the invention incorporates features of the previously described embodiment and is characterized by means wherein the liquid to be nebulized is automatically fed to the top surface of the bottom wall of the receptacle. To this end, the receptacle 20 is attached at its lower end to a fluid container 50 through any type of fluid-tight connection such as the threaded connection illustrated. A feeding tube extends through bottom wall 52 of receptacle 2t} and extends downwardly to a point close to the lower end of container 50.

As will be readily appreciated from FIG. 7, feeding of the liquid contained in container 50 is elfected through the build-up of air pressure on the top surface of the contained liquid which forces the liquid upwardly through tube 51 onto the top surface of botom plate 52. The chief advantage of this arrangement is that no separate liquid feeding arrangement is required and the same air pressure which is used to force air upwardly through the aperture in bottom plate 52 is used to feed the liquid onto the surface of this bottom plate. Thus, it can be seen that the rate of nebulization can be effectively controlled simply by varying the air pressure. To vary the rate of nebulization with the previously described embodiments, both the air pressure forcing air upwardly through the aperture and the rate at which liquid is fed onto the top surface of the bottom plate of the receptacle must be separately controlled. This has the disadvantage that if the feeding rate of the liquid is not stepped down at the same rate as the reduction in air pressure, an excessive build-up of liquid on top of the bottom plate is likely to occur. On the other hand, the embodiment of FIG. 7 is not adapted to the pick-up of powders as are the embodiments of the FIGS. 1 to 6. Should additional control of the feeding rate of the liquid be required in the FIG. 7 embodiment, a needle valve control 54 may be attached to the upper end of tube 51.

FIG. 7 shows one additional feautre which might also be adapted in the embodiments of the other figures of the drawings. This is the shaping of the outer edge of bottom plate 52 so that the latter is curved upwardly. It has been found that under certain circumstances, this particular shaping of the lower end of the receptacle aids in creating turbulent fiow through the setting up of eddy currents within the lower end of the receptacle.

Nebulizing devices in accord with this invention have the advantage of simplicity which makes the devices relatively inexpensive to manufacture as compared with nebulizing devices heretofore available. Most important, however, is the fact that this simplicity of construction and operation renders the devices of the invention virtually fool-proof in operation. Specifically, the devices are not subject to clogging which has been a chief drawback of the nebulizing devices operating on the principle wherein the substance to be nebulized is drawn upwardly through a capillary tube which terminates at a venturi throat through which the carrier gas is passed. Further, of course, the nebulizing device of two embodiments of this invention are adapted to pick up fine powders so that their utility is not restricted to the nebulization of liquids.

What I claim as my invention is:

1. A nebulizer comprising a receptacle adapted to hold a quantity of a substance to be nebulized, said receptacle including a bottom wall which extends substantially horizontally when the nebulizer is arranged in its normal operative position, whereby said bottom wall is adapted for the formation and retention thereon of a. thin film of said substance to be nebulized, means for forming a thin film of the substance to be nebulized on the top surface of said wall, an aperture extending through said bottom wall, turbulence inducing bafile means positioned above the outlet orifice of said aperture, means carried by said nebulizer and connectible to a source of pressurized carrier gas for directing carrier gas upwardly through said aperture whereby said carrier gas picks up said substance, from a thin film thereof that has been formed and retained on said bottom wall, as it emerges from the outlet orifice of said aperture, said receptacle further including outlet means for the egress of the resultant mixture of carrier gas and nebulized substance.

2. A nebulizer as claimed in claim 1, in which the ratio of the minimum lateral dimension of said baffle to the cross-sectional dimension of the outlet orifice of said aperture is less than 7 to 1.

3. A nebulizer as claimed in claim 2, in which the outlet orifice of said aperture has a minimum crosssectional dimension of 0.0005 inch.

4. A nebulizer comprising a receptacle adapted to hold a quantity of a substance to be nebulized, said receptacle including a membrane-like bottom wall which extends substantially horizontally when the nebulizer is in its normal operative position, whereby said bottom wall is adapted for the formation and retention thereon of a thin film of said substance to be nebulized, means for forming a thin film of the substance to be nebulized on the top surface of said wall, a fine mesh screen positioned on the top surface of said bottom wall for reducing surface tension between a liquid substance to be nebulized and the top surface of said bottom wall, said receptacle further including a chamber beneath said bottom wall; means for connecting the interior of said chamber with a source of pressurized carrier gas; an aperture in the center of said membrane-like bottom wall having a lower inlet orifice in fluid communication with said chamber and an upper outlet orifice whereby carrier gas forced into said chamber under pressure passes upwardly through said aperture and picks up the substance to be nebulized, from a thin film thereof that has been formed and retained on said bottom wall, as it emerges from said outlet orifice of said aperture, a rod-like turbulence creating baffie means positioned above the outlet orifice of said aperture, said receptacle further including outlet means for the egress of the resultant mixture of said carrier gas and said nebulized substance.

5. A nebulizer as claimed in claim 4, in which said receptacle is formed of two parts removably connected together along a parting line substantially corresponding to the plane of said bottom wall and in which both said bottom wall and said screen are held in position by engagement of their outer edges between said two parts of the receptacle.

6. A nebulizer as claimed in claim 5, in which said bottom wall has a plurality of apertures.

7. A nebulizer as claimed in claim 6, in which said plurality of apertures are arranged along a line and in which said rod-like baflle is positioned above and spaced from the outlet orifices of all of said apertures.

References Cited UNITED STATES PATENTS 3,105,104 9/1963 Neiss 128-l86 XR 3,189,405 6/1965 Fulton et a1. 21-121 3,206,124 9/ 1965 Drayer et a1 239-4 XR FOREIGN PATENTS 1,147,355 4/ 1963 Germany.

WILLIAM E. KAMM, Primary Examiner US. Cl. X.R.

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