U.S. patent number RE33,717 [Application Number 07/527,957] was granted by the patent office on 1991-10-15 for liquid atomizing device and method.
Invention is credited to Steven A. Svoboda.
United States Patent |
RE33,717 |
Svoboda |
October 15, 1991 |
Liquid atomizing device and method
Abstract
A device and method for aerosolizing a liquid in a gas using a
pressurized gas by creating the fog or "steam" at atmospheric
pressure and room temperature. The liquid is drawn into the gas
stream using a venturi pipe. The amount of entrained liquid is
enhanced by directing the flow of liquid and gas against a
deflector. Liquid entrainment is further enhanced by directing the
flow past projections causing turbulence in the stream. The device
may be operated in either a horizontal position or vertical
position by providing a liquid passage to the perimeter of the
liquid reservoir by means of an angled liquid conduit formed
between a pair of cone members.
Inventors: |
Svoboda; Steven A.
(Soulsbyville, CA) |
Family
ID: |
27062563 |
Appl.
No.: |
07/527,957 |
Filed: |
May 24, 1990 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
928842 |
Nov 7, 1986 |
04746067 |
May 24, 1988 |
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Current U.S.
Class: |
239/338;
128/200.21; 239/370; 239/498; 128/200.18; 239/500; 239/432 |
Current CPC
Class: |
A61M
11/002 (20140204); A61M 11/06 (20130101); B05B
7/0012 (20130101); A61M 2205/21 (20130101); B05B
7/2435 (20130101) |
Current International
Class: |
A61M
11/06 (20060101); B05B 7/00 (20060101); A61M
11/00 (20060101); A61M 011/00 () |
Field of
Search: |
;239/338,370,498,524,432,500,518 ;128/200.18,200.21 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kashnikow; Andres
Assistant Examiner: Merritt; Karen B.
Attorney, Agent or Firm: Shoemaker and Mattare, Ltd.
Claims
I claim: .[.1. A device for aerosolizing a liquid with a gas
comprising:
a. a container for holding said liquid;
b. a venturi tube having an upstream opening adapted for connection
to a source of pressurized gas, a throat portion, a gas discharge
opening, and a liquid and gas discharge opening;
c. liquid conduit means connected to said container holding said
liquid and having a liquid discharge opening adjacent the
downstream end of said throat portion of said venturi tube;
d. said venturi tube is dimensioned and positioned to withdraw said
liquid fluid from said container through said conduit means and to
project a mixture of said liquid and gas out said liquid and gas
discharge opening at high velocity in a directed stream in a first
direction;
e. a deflector member positioned adjacent and disposed from said
discharge opening of said venturi tube and having a surface formed
with a generally planar surface intersecting said directed stream
and causing a dispersion of said liquid and gas forming a flow mass
in a second direction at an angle to said first direction; and
f. said deflector member is formed with a projection member
disposed at an angle to said deflector surface and disposed at an
angle from said liquid and gas discharge opening of said venturi
tube, causing turbulence in said flow mass;
g. said structure resulting in said liquid being dispersed as a
fine mist in a flow of said gas;
h. said liquid and gas discharge opening is formed in a discharge
surface which is generally parallel with said deflector surface;
and
i. said discharge surface is formed with a plurality of concentric
ring projections for creating turbulence in said flow mass..].
.Iadd.2. A device for aerosolizing a liquid with a gas
comprising:
a. a container for holding said liquid;
b. a venturi tube having an upstream opening adapted for connection
to a source of pressurized gas, a throat portion, a gas discharge
opening, and a liquid and gas discharge opening;
c. liquid conduit means connected to said container holding said
liquid and having a liquid discharge opening adjacent the down
stream end of said throat portion of said venturi tube;
d. said venturi tube is dimensioned and positioned to withdraw said
liquid fluid from said container through said conduit means and to
project a mixture of said liquid and gas out said liquid and gas
discharge opening at high velocity in a directed stream in a first
direction;
e. a deflector member positioned adjacent and disposed from said
discharge opening of said venturi tube and having a surface formed
with a generally planar surface intersecting said directed stream
and causing a dispersion of said liquid and gas forming a flow mass
in a second direction at an angle to said first direction; and
f. said deflector member is formed with a projection member
disposed at an angle to said deflector surface and disposed at an
angle from said liquid and gas discharge opening of said venturi
tube, causing turbulence in said flow mass;
g. said structure resulting in said liquid being dispersed as a
fine mist in a flow of said gas;
h. said deflector member being a disc whose perimeter is
substantially encircled by said projection member and from which
disc a plurality of concentric projecting rings depend, disposed
inwardly from said projection member, said projecting rings
projecting a lesser distance from said surface of said deflector
member than said projection member. .Iaddend.
Description
BACKGROUND OF THE INVENTION
This invention relates to those devices which mix a gas under
pressure and a liquid so that the liquid is formed in minute
droplets and is carried on the stream of gas. The invention further
relates to those devices which incorporate a venturi device to draw
the liquid into the gas stream.
Much of the early work in this field occurred in an attempt to
construct carburetors for automobiles. One of the earliest
spray-nozzle carburetors utilizing a venturi was invented by
Maybach in 1893.
Another application of this type of device is the hand pump sprayer
for applying many types of fluid in droplet form from perfume to
paint.
Still another application is the nebulizer which is used to spray
medicinal solutions. Much work has been done in this area by Victor
E. Lester.
SUMMARY OF THE INVENTION
The gist of the present invention is the provision of a structure
for increasing the turbulence in the gas/liquid mixture downstream
from the discharge opening in the venturi tube.
A further improvement is the structure which increases the attitude
angle at which the device will operate and consists of a tapered
capillary conduit between the liquid reservoir and the downstream
conduit opening.
A still further improvement is the structure which causes a
decrease in the droplet size in the aerosol produced by the
elongation of the constant diameter throat section of the venturi
pipe.
The purpose of this invention is to provide a device and method for
inexpensively creating an aerosol from a liquid and a gas which
maximizes the liquid content of the mixture.
Another object is to provide an atomizer which will continue to
operate even though the liquid container is turned on its side in a
horizontal plane.
Still another object is to provide an aerosol device which produces
a smaller droplet size than other comparable aerosol devices.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal cross sectional view of the aerosol device
of the present invention illustrating operation in a vertical
position.
FIG. 2 is an enlarged cross sectional view of the device taken
generally in the area of line 2--2 in FIG. 1.
FIG. 3 is an enlarged cross sectional view of the device taken
along line 3--3 in FIG. 1.
FIG. 4 is a cross-sectional view of the device taken along line
4--4 in FIG. 1.
FIG. 5 is an end view of the deflector member taken along line 5--5
of FIG. 2.
FIG. 6 is .[.is.]. an end view of the discharge surface taken along
line 6--6 of FIG. 2.
FIG. 7 is a cross sectional view taken along line 7--7 of FIG.
2.
FIG. 8 is a partial cross sectional view similar to FIG. 1, but
with the device shown on its side to illustrate operation on a
horizontal plane.
DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION
The present invention consists of a device for aerosolizing a
liquid with a gas including a container 1 for holding the liquid; a
venturi tube 2 having an upstream opening 3 adapted for connection
to a source of pressurized gas not shown, a throat portion 4 and a
discharge opening 5; liquid conduit means 6 connected to a
container 1 holding a liquid 7 and having an outlet opening 8
adjacent the downstream end 9 of the throat portion 4 of the
venturi tube 2; a venturi tube 2 dimensioned and position to
withdraw the liquid from the container 1 through the conduit means
6 and to project a mixture of liquid and gas out the outlet opening
5 at high velocity in a directed stream in a first direction
indicated by arrow 10; a deflector member 11 positioned adjacent
and disposed from the discharge opening 5 of the venturi tube 2 and
having a surface 12 intersecting the directed stream which may be
represented by the directional arrow 10 and causing a dispersion of
the liquid and gas forming a flow mass in a second direction 13 at
an angle to the first direction; and a deflector member 11 formed
with a projection member 14 disposed at an angle to the deflector
surface 12 and disposed at an angle from the discharge opening 5 of
the venturi tube 2, causing turbulence in the flow mass; and the
aforesaid structure resulting in the liquid fluid being dispersed
as a fine mist in a flow of the gas fluid.
In the structure illustrated, a substantial portion of the liquid
will be atomized as the liquid and gas leave the discharge opening
5 due to the pressure drop as the gas leaves the pressurized
venturi tube 2 into a chamber substantially at atmospheric
pressure.
The atomized stream striking the surface 12 causes further
reduction in liquid droplet size and in the structure illustrated,
the flow mass is turned at an approximately 90 degree angle and
flows in a 360 degree flow path. Additional arrow 13a has been
added to indicate this 360 degree flow path.
In a preferred form of the invention as illustrated in the
drawings, the surface 12 of the deflector member 11 is a .[.a.].
generally planar surface.
In a further preferred form of the invention, the deflector member
is a disc with the projection member 14 having a dimension
substantially encircling the perimeter of the disc. The purpose of
the projection 14 is to cause further turbulence to the flow mass
to retain the liquid in the tiny droplet state and reduce the
tendency of the droplets to coalesce and fall back into the liquid
reservoir.
In a still further form of the invention, a plurality of concentric
projection rings 15 project a lesser distance from the surface 12
of the deflector 11 than the projection member 14 and are disposed
inwardly from the projection member. These concentric projection
rings 15 also add to the turbulence in the flow mass.
In another form of the invention, the discharge opening is formed
in a discharge surface 16 which is generally parallel with the
deflector surface 12 and the discharge surface 16 is formed with a
plurality of concentric ring projections 17 for creating turbulence
in the flow mass.
As shown in the illustrations, a flange member 18 is connected to
the deflector member and projects radially outwardly from the
projection member 14 and is disposed downstream from the surface 12
of the deflector member. This flange, which may be annular in
shape, prevents the unobstructed flow of gas and liquid directly
out of the container.
A unique feature of the present atomizing device is the use of a
unique structure to feed liquid from the liquid reservoir to the
point where it joins the pressurized high velocity gas stream. All
atomizers known to applicant use a conduit having a constant cross
section and thus the liquid moves through the conduit at a
relatively constant velocity. In contrast, the present device is
furnished with a conduit which decreases in cross section as the
liquid approaches the juncture with the gas stream. As previously
stated, the conduit means 6 is connected to the liquid reservoir
19. Rather than consisting of a single conduit such as a small
pipe, the conduit means 6 consists of a pair of cones 20 and 21
which create an opening 22 having an annular conical configuration
of gradually decreasing tapered cross section.
As an example, the width of opening 22 at the inlet opening 23 is
approximately 0.014" and narrows to 0.008" adjacent the apexes of
the cones in the vicinity of point 24. The decrease in cross
section of the liquid conduit causes the movement of the liquid to
increase in velocity as the liquid moves from the reservoir to the
liquid discharge opening 8.
A novel feature of the present device is that it will withdraw
fluid from the reservoir and operate in every position between a
vertical and horizontal attitude. This feature is made possible by
providing a liquid conduit opening adjacent the entire outer
perimeter of the liquid reservoir of the container. Furthermore,
the lower portion of the liquid reservoir narrows to a cone
configuration with the apex 25 of the cone occurring adjacent the
liquid inlet opening 23. Thus, as the liquid reservoir empties, the
liquid flows into the narrowing portion 25 of the reservoir 19 and
thus almost all of the liquid may be withdrawn from the reservoir
in all attitudes of the device between the vertical and the
horizontal.
The novel structure which makes the nearly complete emptying of the
reservoir possible is the construction of the conduit means with an
inner and an outer cone wherein the outer cone 20 forms the bottom
wall of the container and the inner cone 21 forms the inner wall of
the liquid reservoir and the space 22 between the cones forms the
liquid conduit 6 between the reservoir 19 and the liquid discharge
opening 8.
The liquid conduit opening is formed by the inner walls 26 and 27
of the cones with the walls spaced so closely together that
movement of the liquid through the liquid conduit actually occurs
by capillary action. Thus a supply of liquid is applied to the
pressurized air stream in the venturi up to the nearly total
emptying of the reservoir.
It has been found that a substantially greater percentage of liquid
is entrained in the gas using the present device. Applicant is not
certain of the reason for this fact, but believes that the
structure of the liquid conduit means 6 contributes substantially
to this result. As shown in the illustration, the liquid conduit
means 6 is positioned at a substantial angle to the longitudinal
axis of the device. Thus, liquid is never required to move
vertically against the force of gravity regardless whether the
device is positioned vertically or horizontally.
Applicant is not able to explain the nearly complete atomization of
the liquid into the gas, but it is believed that one of the
contributing factors is the structure which causes a nearly laminar
flow of gas to occur in the throat portion 4 of the venturi tube
and then an abrupt decrease in pressure immediately followed by a
violent turbulence of the mixture of liquid and gas.
As shown in the drawings, the throat portion 4 of the venturi tube
is formed with a constant cross section for a distance greater than
its diameter. Thus, the gas flowing in air tube 28 moves at a
faster velocity as it moves through the necked down portion 29.
Some turbulence takes place in the gas as the velocity increases.
The throat portion 4 of the venturi tube, however has a
.[.contant.]. .Iadd.constant .Iaddend.cross section for about
0.060" in length for a diameter of 0.025". The smooth bore constant
cross section is believed to return the gas to a more laminar flow.
As the gas passes the liquid discharge opening 8, the reduced
pressure caused by the venturi, causes liquid to be picked up in
the gas stream. Immediately thereafter, the liquid and gas travel a
very short distance of about 0.010" through a portion of the
venturi of constant cross section of about 0.035" in diameter and
length of about 0.010". As the liquid and gas exit the liquid and
gas discharge opening 5, a great reduction in pressure occurs and
the liquid becomes entrained in the gas stream.
The method of aerosolizing a liquid with a pressurized gas may be
carried out by a number of different apparatus and here consists of
the steps of directing a pressurized gas through a venturi tube 2
in a pressurized flow; directing a flow of liquid into the flow of
gas adjacent the downstream throat portion 4 of the venturi tube
forming a mixture of the liquid and gas in a rapidly moving stream;
directing the mixture of liquid and gas in the stream through a
chamber of reduced pressure; directing the mixture of liquid and
gas in the stream against a surface 12 angularly related to the
direction of flow of the mixture and causing a dispersion of the
liquid and gas and a volumetrically increasing flow mass; directing
the flow mass over a projection thereby causing a rapid increased
turbulence of the flow mass; and the steps resulting in the liquid
being dispersed as a fine mist carried by the flow of gas.
When used as a nebulizer, the container 1 is preferably made of
plastic and the entire unit is designed to be used only once before
disposal. It is essential, therefore, to construct the device as
inexpensively as possible. The container 1 is constructed with an
outer cylindrical tapered wall having a base diameter of about
1.400" and an upper wall about 1.125" in diameter. A tube 31 having
a diameter of about 9/16" protrudes from the top of the container.
The tube 31 is adapted for connection to a face mask or other type
of manifold for administering the aerosolized liquid and gas to a
patient.
As previously stated, the bottom wall of the container consists of
a cone 20 which is attached to the outer wall 30 by any suitable
method. The outer cone 20 is formed with a protruding pipe member
28 which is adapted for connection to a gas pressure source. The
gas should be pressurized to about 12 to 25 psi. An inner cone 21
is spaced from the outer cone by nibs molded in one or both
matching cone faces to maintain a proper spacing to form the
conical liquid opening 22. The inner cone 21 is held in position by
three elongated ribs 33 molded or connected to the inside of wall
30 with lower ends 34 resting on shoulders 35 formed in inner cone
21. Liquid flows from reservoir 19 to inlet opening 23 through
annular openings 43 as best shown in FIG. 4. It should be noted
that a radius is formed in the inside wall of outer cone 20 forming
a concave depression 36 therein. A radius is also formed in the
edge of inner cone 21 forming a convex edge 37. This construction
reduces the space in the bottom of the container so that
essentially all of the liquid can be aerosolized and provides a
smooth transition between the liquid reservoir 19 and the liquid
conduit means 6. Additional ribs 38 extend from the inside of wall
30 and support deflector member 11.
The deflector member is preferably circular with a diameter of
about 0.500". The outer portion 39 of the disc slants downwardly
preventing liquid and gas flow directly through tube 31 and
creating a space downstream of projection 14 creating further
turbulence of the stream of liquid and gas fog.
It has been found that capillary movement of the liquid through the
liquid conduit means 26 is enhanced if the surfaces 26 and 27 of
the cones have a slight texture of 16 to 200 rms. A finish of 64
rms have been found to be optimal. The textured finish may be
obtained by sand blasting the mold. The texture may be further
defined by the commercial name "Mold Tech 1055".
Operation of the atomizing device is as follows. Liquid is poured
into the container until the level of the liquid is at any level
below the gas and liquid discharge opening 5. Pipe member 28 is
then attached to a source of pressurized gas by a hose or other
suitable means. The gas should be pressurized to about 12 to 25
psi. The pipe member 28 is sized to give a flow of gas of about 8
liters per minute. The gas moving at high velocity through the
throat portion 4 of the venturi pipe results in a reduction in
pressure which picks up the liquid at annular liquid discharge
opening 8. As the liquid and gas exit the liquid and gas discharge
opening 5, the sudden reduction in pressure causes the liquid to be
atomized and be carried in a fine mist or fog in the rapidly moving
gas. This fog is sometimes referred to as "steam", but unlike steam
which is caused by boiling water at high temperature, the "steam"
produced by the nebulizer is at a room temperature unless the
liquid in the reservoir 7 has been warmed. The rapidly moving
liquid and gas strikes deflector surface 12 where it is immediately
changed in direction 90 degrees to its initial direction. As the
stream of fog moves over the surface 12 of the deflector, ridge
projections about 0.005" in height cause turbulence in the flow.
Similar projections 17 are formed in the discharge surface 16 and
add to the turbulence. These projections in the discharge surface
16 may be a series of concentric ring projections about 0.005" in
height.
The structure which gives the greatest degree of turbulence as the
liquid and gas stream moves over the above surfaces is a projection
ring 14 which depends approximately 0.015" below the surface 12 of
the deflector. The stream of fog or "steam" then passes around the
outer edge 40 of the deflector and passes out tube 31. The "steam"
is then carried by various pipes, masks and other means to a person
who breaths in the fog which may contain medicines or merely be a
saline solution.
The liquid may be water or a volatile liquid for any purpose in
which the liquid is to be carried in minute droplet form in an
exceedingly fine vapor in a gas such as air or any other type of
gas.
The present device is capable of producing up to 50% more "steam"
than similar nebulizers on the market. Most of this increase in
"steam" is due to the use of the projection member 14 which was
discovered by accident when a molding error left a thin flashing of
plastic around the deflector. Subsequent testing with the flashing
left in place resulted in finding the greatly increased production
of "steam".
As previously set forth, inner and outer cones were used to form
the liquid conduit means. While this is the preferred form, the
cones could actually be hemispherical or parabolic in shape for
example.
* * * * *