Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION
IMPROVED CONCENTRICITY FOR LONG CONCENTRIC NEBULIZERS
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims priority under 35 U.S.C. 119(e)
to U.S. Prov. Pat. Appl. No. 60/757,923 filed January 10, 2006,
the disclosure of which is incorporated herein by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR
DEVELOPMENT
N/A
BACKGROUND OF THE INVENTION
Concentric nebulizers have been in use for over 100 years
as furnace burners, paint spray guns, medical nebulizers,
analytical nebulizers and for many other uses. Concentric
nebulizers have a central capillary that usually carries the
liquid, and an outer capillary that surrounds the central
capillary and usually carries the gas. As gas flows out of the
outer capillary, it sucks the liquid out of the inner capillary
and creates an aerosol. Ideally, the inner capillary should be
perfectly centered in the outer capillary to provide the best
gas flow around the inner capillary and produce the best mist.
There are many variations of concentric nebulizers, each
developed according to its purpose. But many designs require
that the concentric nebulizer should be much longer than wider
on the end where the atomized liquid is sprayed out.
The efficiency of the nebulizer relates to many factors
such as the gas pressures, gas flow rates, liquid flow rates,
liquid viscosity, and others. One factor that is often
difficult to deal with is how closely the central capillary
sits in the center of the gas orifice in the end of the outer
capillary. This is a factor that has a large influence on the
consistency of the aerosol produced. Due to the difficulty of
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holding the central capillary perfectly centered, it is rare
that it is actually centered in commercially available
concentric nebulizers.
When the central capillary is not concentric, then there
will be more gas flow on one side of the gas orifice than on
the other side. This will lead to turbulence which will
produce larger droplets than occurs with non-turbulent flow.
In most applications, smaller droplets are desired.
Analytical concentric nebulizers used in Inductively
Coupled Plasma (ICP) and IC/Mass-Spectroscopy (MS)
spectrometers are particularly effected by such non-
concentricity, as their aerosols must be consistent from one
nebulizer to another, and the sensitivity of the spectrometer
depends largely on the droplet sizes produced by the nebulizer.
Analytical concentric nebulizers are available from many
sources, and are usually made of glass or inert plastics. Due
to historical reasons, most analytical nebulizers are made with
a long front cylindrical section approximately 6 mm in outside
diameter and about 25 mm long, and a back section of various
sizes and configurations to attach the liquid and gas lines.
This allows the nebulizers to fit most spectrometers without
requiring special adapters. There is no other intrinsic reason
for the sizes to be used, but the present art is such that most
or all are made with this front size and shape. It is
desirable to continue using the standard sizes in future
designs to allow easy usage of the nebulizers in present
systems. It is also desirable to enable concentric nebulizers
used for other purposes to be able to have very long bodies
while maintaining the central capillary as close as possible to
the exact center of the gas orifice.
The present art for analytical nebulizers uses glass
blowing, molding and machining techniques to make the
nebulizers. They are commonly made of glass, plastic, or non-
corrosive materials such as stainless steel. In all present
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commercially available designs, the inner capillary is attached
in the middle or at the back of the nebulizer body and extends
forward to the tip of the nebulizer. The strength of the
material of the inner capillary is all that holds the inner
capillary in place in the center of the outer capillary. In
most cases, the inner capillary does not get positioned in the
center of the outer capillary as the material is not strong
enough to hold the tiny inner capillary exactly in place. In
many designs, the inner capillary will vibrate as the gas flows
around it, further effecting the quality of the mist.
Fig. 1 and Fig. 2 show cross-sections of glass concentric
nebulizer designs that are presently commercially available for
analytical usage. For both, there is a liquid sample entry
section 103; a connecting point 105 of the central capillary
109 to the main body of the nebulizer; an outer tube portion
(outer capillary) 107 that carries the gas flow and comprises
the nose of the nebulizer, an inner, central lumen within the
central capillary 109 that carries the liquid to the gas
orifice at the nebulizer tip 111; and a gas inlet 113 which is
typically designed as a barb fitting or as a threaded fitting
for the gas input lines. Fig. 1 shows a glass blown design in
which the inner capillary 109 is thick at the junction point
105, and very narrow from there to the tip 111. The thin glass
tube is very fragile and easy to break. It is also difficult
for the central glass tube to remain positioned in the center
of the tip. It usually leans to one side in the tip. Fig. 2
shows a glass nebulizer with the inner central capillary 109
ground to a conical shape. This provides a stronger support
for the central capillary, but still is not strong enough to
keep the capillary 109 centrally placed close to the nebulizer
tip 111.
Fig. 3 shows a cross-section of a molded nebulizer
presently available for analytical usage. This is a plastic
molded design in which a central capillary is made of three
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separate concentric capillaries, a first central capillary 109,
a second central inner capillary 112, and a third central inner
capillary 123. This provides more support at the base
(connecting junction) 105. However, the innermost capillary
123 is very thin and very soft, and often bends away from the
tip 111, producing a very poor mist.
In standard analytical nebulizers, the common practice is
to make the nebulizer with a 6mm OD nose (outer capillary) that
is about 25 mm long. With such a long, thin nose, the central
liquid passage has been typically very long and very thin, and
not rigidly held in place.
It is apparent that the diameter and the unsupported
length of the central capillary are critical to determine its
strength and ability to be held correctly in the center. If
analytical nebulizers were made with a short, thick central
capillary, then the mist produced would be more consistent and
the nebulizer much less likely to break. However,
standardization in equipment receiving nebulizers has resulted
in the less optimal long, thin form factor.
Long concentric nebulizers typically are manufactured
with long, unsupported, central capillaries. The central
capillaries often vibrate during use, causing irregularities in
the mist produced. Owing to their length, the central
capillaries often break very easily. Should any particle
become lodged in the central capillary, it is usually
impossible to remove the particle without breaking the central
capillary due to the fragility of the central capillary.
BRIEF SUMMARY OF THE INVENTION
The present invention allows the production of concentric
nebulizers with better central positioning of an inner central
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capillary within the nebulizer with minimal complicating
factors in the design.
The present invention provides a process and apparatus
for stabilizing the central positioning of an inner capillary
of concentric nebulizers, optionally along the entire length of
the inner capillary but necessarily near the tip of the outer
capillary (i.e., near the tip of the nebulizer) This allows
the inner central capillary to be more exactly centered in a
gas orifice at the tip of the nebulizer, and it dramatically
decreases any vibrations in the inner capillary as the gas
flows through the outer capillary.
One embodiment of the present method comprises the steps
of providing: a body to hold outer and inner capillaries
including means to attach gas and liquid supplies to the
device, a passage to convey a gas stream, an inner capillary to
convey a liquid, and a support in the body near the tip of the
nebulizer to hold the inner capillary more centered.
A further embodiment of the invention provides a method
for maintaining the centricity of a central capillary of a
concentric nebulizer, comprising the steps of providing a
concentric nebulizer having an outer capillary, which outer
capillary comprises a length, external and internal diameters,
a bore, and an inner wall, said outer capillary terminating at
a tip and having an orifice in said tip for gas and/or liquid,
providing at least one central capillary having external and
internal diameters disposed within the outer capillary; and
providing a support of the at least one central capillary
sufficiently near the orifice to maintain the central capillary
centered within the outer capillary and with respect to a
center of the orifice.
The support for an inner member comprising a central
capillary may be of many various styles and shapes. The
support may be in the form of an inner member comprises a
central capillary in contact with the nebulizer body near the
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tip of the nebulizer, or the support may comprise an additional
support element interposed between the body of the nebulizer
and an inner member comprising a central capillary. The
essence is simply that the inner capillary should be supported
very close to the nebulizer tip rather than from the back or
middle part of the nebulizer body. It can be advantageous to
make the inner capillary of larger outside diameter than
presently is standard, to allow some portion of the inner
capillary to be securely positioned by the inner support. If
the inner capillary is too small in outer diameter, then the
support may not work as well.
In one embodiment of the invention, a preferred method of
support is to have the inner central capillary secured in the
body of the nebulizer for the majority of the nebulizer's
length, leaving only a small enough portion at the tip
unsecured to allow the gas to flow smoothly around the inner
capillary as it leaves the gas orifice.
A further embodiment of the invention provides for a
nebulizing device comprising a nebulizer body with gas and
liquid inputs, an outer capillary having external and internal
diameters, a length, a wall, an inner wall surface and a distal
tip, a linear bore through the outer capillary having a
diameter; a substantially linear, cylindrical, central
capillary disposed within the linear bore, said central
capillary having an external diameter, an outer surface and at
least one substantially linear feature on the outer surface
thereof for conveying a gas flow; at least one lumen within the
central capillary; a gas/liquid orifice in the tip of the outer
capillary; a support positioned in a support region
sufficiently proximate the orifice to maintain the central
capillary substantially centered within the outer capillary
adjacent to the orifice; and an open volume within the outer
capillary intermediate the orifice and the support dimensioned
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to allow the gas flow to spread substantially evenly around the
central capillary.
The invention further provides for, within the outer
capillary of a nebulizer, a central capillary having a wall,
wherein the thickness of the wall tapers without changing a
diameter of a central lumen contained within the central
capillary along a distance from the support to a point adjacent
the orifice, such that at the termination of the central
capillary the external diameter of the central capillary is
substantially equal to the diameter of the central lumen.
One embodiment of the invention further provides for the
support is located entirely in a half of the outer capillary
that contains the gas orifice.
Other aspects, features and advantages of the present
invention are disclosed in the detailed description that
follows.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be more fully understood by reference
to the following detailed description of the invention in
conjunction with the drawings, of which:
Figs. 1 and 2 illustrate conventional glass analytical
nebulizers currently in production;
Fig. 3 illustrates a conventional perfluoro-alkoxy (PFA),
copolymer-resin, analytical nebulizer currently in production;
Fig. 4A illustrates a concentric nebulizer according to
an embodiment of the invention with a support at the tip to
help center a central capillary;
Fig. 4B illustrates a similar design of support as
illustrated in Fig. 4A, but with a nebulizer body similar to
that illustrated in Fig. 3;
Fig. 5 illustrates a method of supporting a central
capillary by using a wider central capillary fully supported
for the majority of the length of the nebulizer, with either a
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notch in the central capillary or additional holes in the
central capillary to convey the gas;
Figs. 6A and 6B illustrate an insert supporting a first
inner central capillary with a smaller, second inner capillary
within the first inner central capillary;
Figs. 7A and 7B illustrate an insert supporting the tip
of a central capillary that has been shaped to a point at its
tip;
Figs. 8A-8D illustrate a molded tip of the outer
capillary with a non-circular inner surface cross-section,
enabling the molded tip to center the central inner capillary
while allowing the gas to pass the capillary support;
Figs. 9A and 9B illustrate a body similar to that
illustrated in Fig. 5 with a central capillary fully supported
for the majority of the length of the nebulizer, but with a
notch on one side to allow the gas to flow to the tip; and
Figs. 10A and lOB illustrate a body similar to that
illustrated in Fig. 5 with a central capillary fully supported
for the majority of the length of the nebulizer, but with one
or more additional lumens in the central capillary tube to
allow the gas to flow to the tip.
DETAILED DESCRIPTION OF THE INVENTION
According to embodiments of the present invention, long
concentric nebulizers can be produced with better concentricity
than previously possible, which improves the aerosol produced.
It is one of the objectives of the presently disclosed
invention to provide for concentric nebulizers with an inner
capillary that is very long in length and that is well
supported and well held in line with the center of the exit
hole of the nebulizer.
The inner capillary can be firmly held centrally in place
by a support close to the tip of the nebulizer. However long
the nebulizer body is, if the central capillary is well
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supported, especially at or proximate to the tip of the
nebulizer, the tip of the capillary can remain centered. The
difficulty in providing support along the length of the central
capillary or at the tip of the nebulizer is that the support
must be able to allow the gas to pass through it, or the
nebulizer will not function. Further, the gas must flow with
minimal or no turbulence as it exits the tip of the nebulizer.
Turbulence in the gas flow would cause larger droplets to be
formed, degrading the mist.
Figs. 4A and 4B show variations on how a support 15 can
be employed according to embodiments of the invention to
improve the support of the central, inner capillary. Support
can be provided as an insert near the tip of the nebulizer
or as a molded part of the inside wall of the tip of the
15 nebulizer.
Referring to Fig. 4A, one embodiment provides for a
nebulizer body with gas input 13 and liquid input 3, comprising
a back section 5 of various sizes and configurations to attach
liquid and gas lines and an outer nose portion 7 of the
nebulizer (e.g., a long, front cylindrical section, or outer
capillary). This outer portion 7 can have, inter alia, (a) an
external diameter 28, (b) a wall, (c) an inner wall surface,
(d) a linear bore passing through the outer portion, which bore
has an internal diameter, and (e) a distal tip. The nebulizing
device of this preferred embodiment may further comprise a
substantially linear, cylindrical, inner member 9 disposed
within the linear bore, said inner member 9 having an external
diameter, an outer surface and having at least one
substantially linear feature on the outer surface thereof for
conveying a gas flow. Said inner member 9 can comprise a first
inner, central capillary. In addition, a second inner
capillary 12 may be formed within the inner member 9 for
conveying a liquid flow, and a gas/liquid orifice 11 may be
located in the tip of the outer nose portion 7 of the nebulizer
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body. In this preferred embodiment of a nebulizer device
according to the invention, a support 15 exists in a support
region sufficiently close to the gas/liquid orifice 11 to
maintain the second inner capillary 12 substantially centered
in the outer nose portion close to the orifice 11. Passages
around, beside or through said support 15 exist to allow gas to
flow past or through the support region with minimal
turbulence, and an open volume 17 exists within the outer
portion near the orifice 11, said volume dimensioned to allow
the gas flow to spread reasonably evenly around the inner
member 9 and second inner capillary 12.
The invention, as depicted in Fig. 4A, also provides
further for a device wherein a first inner central capillary 9
is supported by and terminates closely after the support 15,
and a second inner central capillary 12 extends beyond the
termination of the first central capillary 9 substantially
through the volume 17 to terminate near the orifice 11. One
exemplary embodiment provides, measured at a cross-section
within the first half of the support 15 away from the orifice
11, an inner member 9 having an external diameter of about 2 mm
and disposed within said inner member 9 a secondary inner
capillary 12 having external diameter about 0.5 mm or less and
having an inner diameter about 0.25 mm or less.
In another embodiment, shown in Fig. 4B, the first
central capillary 9 contains a secondary inner capillary 12,
which extends beyond the termination of the first central
capillary 9 substantially through the open volume 17 such that
the secondary inner capillary 12 is centered within the outer
nose portion 7 and terminates close to the gas/liquid orifice
11. A third central capillary 23 can be disposed outside the
first central capillary 9 and can terminate before the support
15 and is not directly supported by the support 15, but the
first central capillary 9 is supported directly by the support
15 and terminates close after the support.
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Referring still to Fig. 4B, a further exemplary
embodiment provides, measured at a cross-section at the
beginning end of the outer nose portion 7 away from the end
containing the orifice 11, an inner member (or third inner
central capillary) 23 having an external diameter about 3.0 mm,
wherein disposed within the inner member 23 is a first central
capillary 9 having an external diameter about 2.0 mm, and
disposed within said first central capillary 9 is a secondary
inner capillary 12 having an external diameter about 0.5 mm or
less and having an inner diameter about 0.25 mm or less.
A further preferred embodiment, referring still to Figs.
4A and 4B provides for a nebulizer having a support 15 and a
supported region 75. In these examples, the support 15 is
positioned entirely in the end of the outer nose portion 7 of
the nebulizer that contains the orifice 11.
Figs. 5 and 9A illustrate how a bore can be provided in
said nebulizer body dimensioned to receive a central capillary
9 and to support the capillary 9 along a majority of its length
centered in said outer portion 7. If the central capillary has
a linear notch along one side, such as notch 19 shown in Fig.
5, the central capillary 9 will be supported by the inner wall
of bore 10, and the notch will allow the gas to flow to the tip
of the nebulizer. In this example, at least one notch 19 is
provided along the outer surface of the central capillary and
in communication with the gas input 13 to allow gas to flow
from the gas input 13 to the gas/liquid orifice 11 through the
at least one notch 19 along the capillary with minimal
turbulence. The central capillary 9 is supported by the bore
sufficiently close to the orifice 11 to maintain the central
capillary centered within the outer portion 7 close to the
center of said orifice 11. An expansion space, or open volume
17, can be provided close before the orifice 11.
To allow a non-turbulent gas flow, a support must have
sufficiently large holes or other pathways in it for the gas to
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pass through smoothly. Also, the support must leave some room
(open volume) at the tip of the nebulizer to allow the gas flow
to spread evenly around the central capillary. Figs. 4A, 4B
and 5 show open volume 17 at the tip of the nebulizer. This
open volume 17 must be large enough to allow the flow of the
gas to spread reasonably evenly, and the length of this volume
must be short enough to maintain support for the central
capillary 9. Exact sizes are determined by the materials in
use, inter alia.
In some exemplary embodiments of the invention, the outer
nose portion 7 of the nebulizer can have a length of about 20
to 40 mm and an external diameter about 6.0 mm.
As long as the cross-sectional space for the gas flow
within the support 15 is enough and the final open volume 17
around the terminating tip of the inner capillary 9 is large
enough, then the gas flow will remain sufficiently non-
turbulent.
Figs. 6A and 6B illustrate one embodiment that provides
for a support 15 with a cross-section similar to a bicycle
wheel, i.e., with radial spokes. The spokes are formed of
longitudinal fins or vanes, which extend from the outer surface
of the central capillary, or from a support hub surrounding the
capillary, to the inner surface of the outer capillary 7. Fig.
6A is an expanded detail view of the tip end of an outer
capillary 7 with a support 15 holding a first inner central
capillary 9, where inside the first inner capillary 9 is
disposed a second inner capillary 12. The first inner
capillary 9 is supported by the support 15 proximate to the
terminating tip of the inner capillary 9, and the smaller
second inner capillary 12 extends through the short open volume
17 to the nebulizer tip 11. This minimizes the volume occupied
by the capillaries within the open volume 17, thus facilitating
the spread of gas flow. Fig. 68 shows a cross-section of Fig.
6A along line 6B-68, where the cross-section of support 15 is
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similar to spokes of a bicycle wheel, but with proportionally
thicker fin-like supports 16.
Fig. 7A and 7B show a cross-sectional support similar to
that illustrated in Fig. 6A and 6B, but with a different style
of central capillary 9. In Fig. 7A, the central capillary 9 is
made of a thicker outside dimension and has a tapered tip. The
thickness of the central capillary wall tapers without changing
the diameter of its lumen or of a secondary inner capillary
disposed inside said central capillary 9. In one embodiment,
this taper can occur along a distance from the support 15 to
the gas orifice 11, such that at the termination of the inner
member 9 near the orifice 11 the wall of the inner member 9 is
almost a knife-edge and at the termination point the external
diameter of the central capillary 9 is substantially equal to
the diameter of its lumen or of a secondary inner capillary.
At least a portion of the non-tapered part proximate to the
nebulizer tip 11 is supported and the tapered part extends the
short distance past the support 15 to the tip 11.
Shown in Fig. 7A, wherein the outer portion 7 has an
external diameter 28 and an internal wall 4, a support 15 can
be inserted about the central capillary and within the outer
portion 7, said support 15 having a length and comprising a hub
portion 26 that in cross-sectional aspect has an internal
diameter approximately equal to the external diameter of the
central capillary 9, and said support further comprising, in
cross-section, a plurality of fins 16 integral with and
extending spoke-like from the hub portion 26 to contact the
internal wall of the outer portion 7 of the nebulizer, wherein
each fin 16 has a base where the fin integrally connects with
the hub portion 26 and a tip where the fin 16 contacts the
inner wall 4 of the outer portion 7 of the nebulizer.
With reference to Fig. 6A, a further exemplary embodiment
provides, measured at a cross-section within that half of the
support 15 away from the orifice 11, a first inner capillary 9
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having an external diameter 14 of about 2.0 mm. Disposed
within the first inner capillary 9 is a second inner capillary
12 having an inner diameter of about 0.5 mm or less.
With reference to Fig. 7A, another exemplary embodiment
provides, measured at a cross-section within that half of the
support 15 away from the orifice 11, an inner capillary 9
having an external diameter of about 2.0 mm. However, as one
moves along the inner capillary 9 toward the gas orifice 11,
the outer diameter of the inner capillary 9 becomes
progressively smaller.
In both Figs. 6B and 7B, the support is shown in cross-
section with ten fins 16. The number and thickness of fins 16
in the support 15 is not critical. The critical aspect is that
the gas flows with minimal turbulence and at a desired rate.
The open space of the cross-sectional shape of the support 15
can be varied depending on the flow rates intended to be used
in the operation of the nebulizer.
As shown in Fig. 7B, the fins 16 can have a cross-
sectional aspect tapering from relatively greater thickness at
their base to relatively lesser thickness at their tip.
Figs. 8A, 88, 8C and 8D show different cross-sections,
more appropriate for a molded support. Fig. 8A shows how a
molded support 15 can be included as part of a molded tip of a
nebulizer, with the central capillary 9 pressed into the
support. The inner wall 4 of the outer capillary 7 of the
nebulizer can be formed or molded such that the formed or
molded wall contacts the inner central capillary 9 in a support
region 75 close to the orifice 11. The capillary 9 is
centrally supported by contact with the molded inner wall of
the outer capillary 7 to maintain the inner central capillary 9
centered within the outer capillary 7 close to the orifice 11.
Figs. SB, 8C and 8D show various configurations of cross-
sections that could be used as a support 15. In all of the
configurations shown, there are differences in the cross-
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sectional area allowed for the gas flow in the support region,
so some configurations would be more appropriate for lower gas
flows and some for higher gas flows. Referring to Fig. 8B, the
inner wall 4 of the outer portion 7 can be formed such that, in
cross-section, an open volume shaped as an equilateral polygon,
such as, for example, a triangle, is formed within the inner
wall 4, and the inner capillary can be disposed, in cross-
section, as an incircle of said polygon.
In another embodiment, as shown in Fig. 8C and 8D, the
inner wall can be formed into, in cross-section, a plurality of
ridges 30 that project from the inner wall of the outer portion
to contact the inner member 9, wherein each of the ridges has a
base where the ridge integrally connects with the inner wall of
the outer portion and a tip where the ridge contacts the outer
surface of the inner member 9, and each ridge runs the length
of the support region 75 (see Fig. 8A). The support region 75
formed by the molded inner wall can be three ridges (see, for
example, as in Fig. 8C) or six ridges (see, for example, as in
Fig. 8D) or any other number of ridges symmetrically disposed
about the inner member.
Referring to Figs. 8A, 8B, SC and 8D, one embodiment of
the invention provides, measured at a cross-section within that
half of the support 75 away from the orifice 11, an inner
member 9 having an external diameter of about 2 mm, and
disposed within the inner member a secondary inner capillary
having an inner diameter of about 0.5 mm or less.
Figs. 9A and 9B show details and cross-sections of a
nebulizer tip 11 similar to the tip 11 shown in Fig. 5. In
Fig. 9A, one embodiment provides for a central capillary 9 that
has been inserted into a bore extending through the nebulizer.
The central capillary 9 may be glued or press-fit at the back
where the liquid input is provided, to prevent the gas from
exiting at the liquid input. The central capillary 9 has at
least one notch 19 cut from the outer surface of a central
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capillary 9 such that a cross-sectional profile of the
capillary 9 comprises a circle from which a chord segment notch
19 is removed (see Fig. 9B). In one embodiment, said chord
segment notch 19 is, at its thickest point, about 4% to 5% of
the outer portion external diameter 28. Alternatively, the
central capillary 9 may have more than one notch 19, as long as
enough of the capillary 9 remains to be properly supported by
the inner walls of the bore 10. The notch or notches 19 will
extend from the gas input to the terminating tip of the
capillary 9, and not all the way back to the liquid input area.
The central capillary 9 and bore 10 extending through the
nebulizer can each be of a non-circular shape, so long as the
central capillary 9 remains supported.
As shown in Figs. 10A and lOB, an extruded multilumen
central capillary 20 can comprise the inner member with a
central lumen 22 and at least one non-central lumen 24. The
multilumen capillary 20 is a capillary with several holes
running along its length rather than one hole in the center. A
liquid flow can be conveyed in the central lumen 22 and a gas
flow can be conveyed in the at least one non-central lumen 24,
said at least one non-central lumen 24 being sized to allow a
desired volume of gas to flow at a desired rate with minimal
turbulence. If the central extruded capillary 22 is tapered at
the tip, then the holes 24 conveying the gas will end before
the tip of the nebulizer and allow the gas to spread evenly
around the central portion of the capillary in open volume 17.
To have the gas flow in the additional holes 24 for the gas,
the back portion of the gas holes must be plugged and holes or
notches must be provided in the sides of the capillary to allow
the gas to flow from the gas input of the body into the holes
24 for the gas in the multilumen central capillary 20.
A bore 10 in said nebulizer body is dimensioned to
closely receive said central capillary 20 and to support the
inner member by contact along a majority of its length. The
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bore 10 supports the capillary 20 centered in the bore
sufficiently close to the gas/liquid orifice 11 to maintain the
central lumen 22 centered within the outer portion 7 close to
the center of said orifice 11. In a further exemplary
embodiment, the support of said bore is continued along the
length of the central capillary 20 to a point a short distance
from the orifice 11. Within the inner member 9 a central lumen
22 can be provided and at least one non-central lumen 24 having
relatively small diameters. The radius of the capillary 20
diminishes toward the nebulizer tip so that only a radius of
the inner member enclosing the central lumen 22 is remaining
proximate the orifice 11.
According to embodiments of the present invention, very
long nebulizers can be made if they have support for the
central capillary 9. The method shown in Figs. 5, 9A and 10A
are easily adapted to unlimited length nebulizers - the support
may extend for the entire length of the inner central capillary
9. The capillary can be any length desired, as it is not
dependent upon the structural strength of the central capillary
9.
In other embodiments, as shown for example in Figs. 4A
and 6A a short unsupported length of the second inner capillary
12 (or, as shown in Fig. 4B, of the third inner capillary 23)
can extend through the open volume 17 toward the orifice 11.
In one preferred embodiment, the nebulizer can have an
outer nose portion (i.e., the long, front cylindrical section,
or the outer capillary) that can have a length about 25 mm and
an external diameter about 6 mm, and a back section of various
sizes and configurations to attach the liquid and gas lines.
A method according to the present disclosure maintains
smooth gas flow in the nebulizer by providing passages around,
beside or through the support that allow the nebulizer gas to
flow past or through the support region with minimal turbulence
and by providing an open volume comprising a cross-sectional
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CA 02571032 2006-12-12
open area and a length near the gas orifice, which volume is
large enough to allow the gas flow to spread substantially
evenly around the inner capillary near the gas orifice.
The foregoing discussion, for convenience, has referred
to gas flowing in the outer capillary and liquid flowing in the
inner central capillary (and/or through secondary or tertiary
inner central capillaries); however, the same advantages of the
invention can be observed in nebulizers in which the gas and
liquid flows are switched. The gas may be conveyed in the
inner central capillary and the liquid in the outer capillary,
although it is more common and more efficient to have the gas
outside (flowing within the outer capillary) and the liquid in
the center (flowing within the inner capillary).
While the invention has been described in connection with
specific methods and apparatus, those skilled in the art will
recognize other equivalents to the specific embodiments herein.
These and other embodiments of the invention illustrated above
are intended by way of example and should not be viewed as
limiting the scope of the disclosure or of the claims. The
actual scope of the invention is to be limited solely by the
scope and spirit of the following claims.
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