the present invention a pneumatic nebulizer in which aerosol mist is produced in a downwardly flowing direction , the aerosol mist then leaves the nebulizer through a downwardly projecting aerosol outlet , that is to say , a downdraft nebulizer . the principles and operation of downdraft nebulizer according to the present invention may be better understood with reference to the drawings and the accompanying description . by way of introduction , the nebulizers presently in general use are configured for discharge of medication mist either into an inhalation interface or directly into the environment . typically , the intention of nebulizers used for extended time administration is produce a flow of droplets of medication in atmospheric suspension to an inhalation interface , usually a mouth piece . the medicated mist is generally discharged in an upward or sideward direction since this is the easiest way to deal with the problem of trapping drops that are too large to be aspirated by a patient . there are , however , applications where a downward flow may be advantageous and even preferred . an application in point is the aerosol inhalation interface that is suspended above the patient , disclosed in wo0202052 , to the present inventor . an intention of wo0202052 is to use the force of gravity to draw a medicated mist down to a patient lying beneath a nebulizer within a controlled environment . referring now to the drawings , fig1 illustrates the exterior of a first preferred embodiment of a nebulizer , generally referred to herein by 2 , constructed and operative according to the teachings of the present invention . high velocity gas , typically compressed air , is introduced into the nebulizer through the air inlet 4 medicated mist is discharged from the nebulizer through the downwardly projecting aerosol outlet passage 20 in the outlet tube 6 , which extends downwardly from the lower housing 8 . as used herein , the terms “ down ” and “ downward ”, refer to a direction aligned with the force of gravity . as mentioned above , fig2 serves to establish cross - sectional lines a — a , along which fig3 , 8 , and 10 are taken , and b — b , along which fig4 is taken . a first preferred embodiment , as discussed herein , includes four structural elements , the deployment of which is illustrated in fig3 and 4 , which are cross - sections across the diameter of a substantially cylindrical housing taken along different lines ( see fig2 ). a substantially cylindrical lower housing 8 includes a downwardly projecting aerosol outlet passageway 20 ( for clarity see fig1 ). supported above the opening of the aerosol outlet passageway 20 is an atomization baffle 50 ( fig1 and 12 ). a substantially cylindrical upper housing 40 ( fig6 ) is inserted into the lower housing 8 . the inside diameter of the lower housing 8 and the outside diameter of the upper housing 40 as substantially the same so as to create a seal between them . each of the two housing elements is configured with corresponding threads about their circumferences in region 12 so as to provide for secure interconnection of the two as the upper housing is turned using handle 10 . the cylindrical wall of the upper housing extends substantially to the lower interior surface of the lower housing . when thusly interconnected , the two housing elements define within them an interior volume 70 , the bottom of which serves as a reservoir 90 for the liquid 92 being , dispensed by the nebulizer . deployed within the volume 70 is a substantially cylindrical fluid passageway insert 30 ( fig8 ) configured to substantially abut the cylindrical wall of the upper housing 40 . the lower edge of the cylindrical wall of the fluid passageway insert 30 is spaced above the lower interior surface of the lower housing 8 enough to allow liquid 92 to flow beneath it . the upper housing 40 is configured with two structural features . one of these features is a terminal opening 46 ( see fig7 for clarity ) of the compressed air inlet 4 . an outlet of the passageway 46 , which is an upper portion of a venturi orifice 44 , is circumscribe by a spacer extension 48 that serves to limit the height to which the fluid passageway insert 30 may be inserted into the upper housing 40 . the space created between the fluid passageway insert 30 and the upper housing 40 serves as an upper portion of a fluid passageway 42 . another feature is spaced apart grooves 42 ( see fig6 ) in the surface of the cylindrical wall that works in concert with the fluid passageway insert 30 to define vertical portions of fluid passageways 42 . thus , with the fluid passageway insert 30 deployed within the upper housing 40 , fluid passages 42 , through which fluid communication between the fluid reservoir region 90 of the interior volume 70 of the housing and the venturi orifice 44 may be established , are defined . note that for graphic purposes , the fluid passages 42 ′ are illustrated in black in fig3 . the lower portion 46 ′ of the venturi orifice 44 is configured in the upper wall 32 of the fluid passageway insert 30 . it should be noted that the four grooves 42 that partially define the fluid passageways 42 ′ may be implemented as any number of grooves . is should be further noted that the grooves 42 described here , and with regard to a second embodiment of the present invention discussed below , may alternately be configured in the fluid passageway insert 30 . deployed with in the internal volume of the nebulizer , below the opening of the venturi orifice 44 is an atomization baffle 50 . the atomization baffle 50 is configured substantially as a disk deployed at an orientation substantially perpendicular to the cylindrical wall defining the side of the internal volume . as illustrated here , and in fig4 and 12 , the atomization baffle 50 is supported by four radially spaced apart legs 54 that rest of the upper end 120 of the aerosol outlet tube 6 . it should be noted that the baffle may alternatively be supported by connection to the fluid passageway insert . the upper surface of the atomization baffle 50 is configured with a semispherical protrusion 52 located substantially below and adjacent to the opening of the venturi orifice 44 . it should be noted that the protrusion may be of any functionally appropriate shape , such as , but not limited to , conical , geodesic , or flat . the remainder of the upper surface of the atomization baffle 50 is downwardly sloping such that liquid that collects on the surface during the atomization process will flow to the extreme radial edge 56 of the atomization baffle 50 and fall back into the fluid reservoir region 90 of the internal volume 70 . a second embodiment of a nebulizer , generally referred to as 100 constructed and operative according to the teachings of the present invention is illustrated in fig1 - 15 . the operational principles of this second embodiment are the same as the first embodiment described above , therefore , structural elements effecting the operation are similar to the first embodiment and therefore are numbered accordingly . the differentiating feature of this second embodiment is the sloping bottom 102 of the lower housing 108 . the sloping bottom 102 creates a region of liquid confluence 104 in the liquid reservoir 190 . this allows more of the liquid 192 to be aspirated by the fluid passageway 142 which is configured with a bottom opening substantially corresponding to the lowest point in the reservoir . that is , the inside surface of the cylindrical wall of the upper housing has a groove extending upward from an area adjacent to the lowest point to the top of the wall , and the outer surface of the cylindrical wall of the fluid passageway insert abuts substantially the rest of the inside surface of the cylindrical wall of the upper housing . the sloping bottom also allows for proper operation of the nebulizer at varying orientations other than vertical . in this embodiment the slope of the bottom is preferably 30 degrees from vertical and allows full operation of the nebulizer within a range of orientations between vertical and about 25 degrees from vertical . in this second embodiment the lower extremities of each of the cylindrical walls of the upper housing 140 and fluid passageway insert 130 lie within planes that are substantially parallel to the plane of the sloping bottom 102 of the lower housing 108 . the upper and lower housing elements may be secured by friction or pressure when press together . the operation of a nebulizer constructed and operative according to the teachings of the present invention , is substantially as follows : 1 — liquid to be atomized in placed in the reservoir region 90 of the lower housing 8 , in which the atomization baffle 50 is deployed . 2 — the upper housing 40 , containing the fluid passageway insert 30 , is inserted into the lower housing 8 and secured by turning the upper housing 40 using handle 10 . 3 — a tube connected to a source of compressed air is connected to inlet 4 and a high velocity flow of air is introduced into the nebulizer . 4 — as the high velocity air passes through the venturi orifice 44 , liquid from the reservoir 90 is aspirated up through the fluid passageways 42 ′, by a venturi effect , and into the air flow . 5 — the introduction of the liquid into the flow of high velocity air causes the liquid to form drops . 6 — as the drops flow out of the venturi orifice 44 they are impinged on the surface of the semispherical protrusion 52 of the atomization baffle 50 . this causes some of the drops to break up into smaller droplets so as to form a mist . 7 — the mist follows a flow path that flows radially outward around the atomization baffle 50 . 8 — the flow path of the mist turns radially inward toward the top 120 of the downwardly projecting aerosol outlet passageway 20 . 9 — the mist flows down through the aerosol outlet passageway 20 and out of the nebulizer with a downward flow path . 10 — liquid from drops that where to large to be suspended in the mist fall , by the force of gravity , onto the upper surface of the atomization baffle 50 or directly into the liquid reservoir 90 . any liquid that condenses on the upper surface of the atomization baffle 50 flows to the outer or extreme radial edge 56 of the baffle and fall into the liquid reservoir 90 . liquid that condenses on other surfaces within the interior volume of the nebulizer flows by the force of gravity back into the liquid reservoir 90 . it will be appreciated that the above descriptions are intended only to serve as examples , and that many other embodiments are possible within the spirit and the scope of the present invention .
disclosed is a nebulizer having a downwardly facing aerosol outlet that is structurally configured so as to produce aerosol mist in a downward direction and that delivers a downwardly directed flow of medicated aerosol mist for a period of time . that is to say , a downdraft nebulizer .