Note: Descriptions are shown in the official language in which they were submitted.
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FREE FLOW AEROSOL VALVE
BACKGROUND OF THE DISCLOSURE
1. Field of Disclosure
[0001] The present disclosure is related to the field of aerosol delivery
of
high-solids product formulations. More particularly, the present disclosure
relates
to an aerosol valve having a valve stem and compression spring geometry that
create shorter flow paths/fewer changes in flow direction to minimize
agglomeration of solids in the flow paths and thereby reduce product failures.
2. Description of Related Art
[0002] Valve structures for product formulations that have a high solids
content can fail due to agglomeration of the solids in the flow passages in
the
internal space of the valve stem housing. Existing designs of such valves
typically employ flow paths that have long, narrow channels, abrupt changes in
flow direction, and areas of recirculation flow ¨ any of which can cause the
solids
in the product formulation to agglomerate and clog the flow paths.
[0003] As used in this application, agglomeration (or any of its forms)
is
used interchangeably with clumps (or any of its forms) without a change in
meaning.
[0004] Also, existing aerosol valves have a compression spring that is
fully
compressed (i.e., the individual coils are pressed together) when the valve
stem
is fully pressed by the consumer to spray the product. However, the compressed
coils act as a barrier to the product formulation that is passing upward, and
so
forces the product formulation to follow a flow path that is nearly entirely
on the
outside of the fully-compressed spring, since there is little or no space
between
the individual coils that allow the product formulation to flow in the space
in the
center of the spring.
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SUMMARY OF THE DISCLOSURE
[0005] The present disclosure is an aerosol valve that provides a free
flow
aerosol delivery of high-solids product formulations with reduced
agglomeration
and product failure from clogging.
[0006] The aerosol valve of the present disclosure includes a valve stem
that has large cross-section passageways that allow the product formulation to
flow directly from the dip-tube through the center of the compression spring.
This
configuration allows the product flow to be gently deflected around the valve
stem, which reduces back pressure (resistance).
[0007] The valve stem and compression spring geometry of the present
disclosure creates a shorter flow path, and a flow path that fewer changes in
flow
direction, as compared with conventional aerosol valves.
[0008] The valve stem of the present disclosure also has large cross-
section flow passageways that minimize drag of product flow in the
passageways.
[0009] These shorter, large cross-section, non-tortuous flow paths of the
aerosol valve of the present disclosure minimize agglomeration of solids in
the
flow paths, and reduce product failure from blockage of the flow paths, even
when used for difficult high-solids product formulations.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 (Prior Art) is a conventional aerosol valve in full stroke,
illustrating the flow paths around the outside of the springs.
[0011] FIG. 2 is a side view of an exemplary embodiment of an aerosol
valve of the present disclosure.
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[0012] FIG. 3 is a cross-section of the aerosol valve in FIG. 2 in a
closed
(resting) position.
[0013] FIG. 4 is a three-quarters-perspective view of the cross-section
of
the aerosol valve in FIG. 3 in a closed (resting) position.
[0014] FIG. 5 is a perspective view of an exemplary embodiment of a
valve
stem of the present disclosure.
[0015] FIG. 6 is a bottom view of the valve stem in FIG. 5, illustrating
the
cross-shaped configuration of the four (4) flow passageways.
[0016] FIG. 7A is another perspective view of the valve stem in FIG. 5,
but
adding the compression spring to show its position in relation to the four (4)
flow
passageways and aerosol valve. FIG. 7B is the identical view shown in FIG. 7A,
with shading to clearly show the compression spring.
[0017] FIG. 8A is another bottom view of the valve stem in FIG. 6, but
adding the compression spring to show its position in relation to the four (4)
flow
passageways and aerosol valve. FIG. 8B is the identical view shown in FIG. 8A,
with shading to clearly show the compression spring.
[0018] FIG. 9 is a perspective view of a cross-section of the aerosol
valve in
FIG. 2 in mid-stroke, illustrating primary and secondary flow paths, upon
partial
compression of the compression spring.
[0019] FIG. 10 is a side view of a cross-section of the aerosol valve in
FIG.
2 in full stroke, without showing the flow paths.
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[0020] FIG. 11 is a perspective view of a cross-section of the aerosol
valve
in FIG. 8 in full stroke, illustrating the primary and secondary flow paths,
upon full
compression of the compression spring.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0021] FIG. 1 is a conventional aerosol valve generally represented by
reference numeral 10. Valve 10 is illustrated in FIG. 1 in full stroke,
illustrating
the long, tortuous flow path of the product formulation around the outside of
the
compression spring before the formulation is able to enter the center hole of
the
valve stem.
[0022] Aerosol valve 10 includes a dip tube 12, valve stem 16, valve
stem
housing 18, mounting cup 20, seal 22, and compression spring 32. Valve stem
16 is enclosed in valve stem housing 18. Valve stem 16 has a pair of apertures
(not shown in FIG. 1) through which a pressurized high-solids product
formulation
passes in order to enter center hole 24 of valve stem 16. Mounting cup 20
orients and stabilizes aerosol valve 10 in its proper position on the product.
Valve stem 16 contacts compression spring 32 at contact point 26.
[0023] Compression spring 32 exerts an upward pressure on valve stem
housing 18, which is pressed against seal 22 that is located on the inner
aspect
of mounting cup 20. Valve stem 16 has an upper portion that protrudes through
seal 22 and mounting cup 20, and which is pressed by the consumer to spray the
product formulation.
[0024] When valve stem 16 is pressed down by the consumer to spray the
product, the product formulation flows upward through the internal space of
valve
stem housing 18 in a flow path 30.
[0025] As shown in FIG. 1, compression spring 32 is fully compressed,
pushing together the individual coils of compression spring 32 so there is
little or
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no space between any of the individual coils. In this configuration, the coils
of
compression spring 32 act as a barrier to the space that is inside the
compression spring, requiring the product formulation to travel upwardly by a
long
path through valve stem housing 18 almost entirely along the outside of
compression spring 32. This long, tortuous primary flow path 30 increases the
probability that the solids in the product formulation will agglomerate and
clog the
flow path, causing the passage of the product formulation in the flow path to
be
slowed or blocked altogether, leading to product failure.
[0026] FIGS. 2 through 9 illustrate an exemplary embodiment of an
aerosol
valve 40 of the present disclosure. Referring to FIGS. 2 to 4, aerosol valve
40
includes a dip tube 42, compression spring 44, valve stem 46, valve stem
housing 48, mounting cup 50, and seal 52. Valve stem 46 is enclosed in valve
stem housing 48. Valve stem 46 has a valve stem aperture 58 through which a
pressurized high-solids product formulation passes in order to enter center
hole
54 of valve stem 46. Mounting cup 50 orients and stabilizes aerosol valve 40
in
its proper position on the product. Valve stem 46 contacts compression spring
44
at contact point 56.
[0027] Compression spring 44 exerts an upward pressure on valve stem
housing 48, which is pressed against seal 52 that is positioned on an inner
aspect of mounting cup 50. Valve stem 46 has an upper portion that protrudes
through seal 52 and mounting cup 50, and which is pressed by the consumer to
spray the product formulation.
[0028] Seal 52 is a flexible material that seals the space between
mounting
cup 50 and valve stem housing 48. Seal 52 is preferably made of rubber or
similar flexible material. Seal 52 is preferably shaped as a gasket. A seal
between seal 52, valve stem housing 48 and mounting cup 50 occurs by
compression during crimping of cup 50. Pressing on valve stem 46 can
somewhat deform the gasket-like seal between seal 52 and valve stem housing
48 as well as between seal 52 and mounting cup 50.
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[0029] Dip tube 42 is the access point for the stored product
formulation in
the container (not shown) to aerosol valve 40.
[0030] Aerosol valve 40 has fewer abrupt changes in flow direction, as
compared with the flow paths of aerosol valves in the prior art. This reduces
the
propensity of the solids in the product formulation to agglomerate in the flow
paths, by providing fewer loci at which the particles may accumulate, and
thereby
reduces product failures.
[0031] FIGS. 5 and 6 illustrate an embodiment of valve stem 46 having
four
(4) passageways 64, 66, 68, 70 that are perpendicular to each other.
Passageways 64, 66, 68, and 70 are large in cross-section to minimize drag and
thereby reduce agglomeration of the solids in the product formulation as the
product passes through, reducing the incidence of product failure.
[0032] The passageways readily allow the product formulation to flow
directly from dip tube 42 through the center space inside compression spring
44
(shown clearly in FIGS. 3 and 4), and to be gently deflected around valve stem
46. Valve stem 46 is preferentially a thinned valve stem body. These
structures
and configuration reduce back pressure (resistance) to the flow of the product
formulation before it reaches valve stem aperture(s) 58. This is an advantage
over conventional valve flow paths, which require abrupt changes in flow
direction
and passage through long, narrow channels prior to arriving at the valve stem
apertures.
[0033] Aerosol valve 40 preferentially forms the largest possible flow
path
cross-sections that are viable, given the constraints of the valve stem
housing,
compression spring geometry, and valve stem molding capability (for strength
and moldability). In an exemplary embodiment, expressed as the % cross
section of the flow paths (passageways) versus the full inside diameter of the
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compression spring coils, about 49% of the available cross-section inside of
the
compression spring coils is divided into the four passageways.
[0034] FIG. 7A illustrates a view of aerosol valve 40 that shows the
position
of compression spring 44 in relation to passageways 64, 66, 68, 70.
Compression spring 44 is shown in FIG. 7A as fully-compressed (open), as the
spring would be when aerosol valve 40 is fully-actuated. FIG. 7B is an
identical
view to FIG. 7A, but with shading to clearly illustrate these components.
[0035] FIG. 8A illustrates another view of aerosol valve 40 to show the
position of compression spring 44 in relation to passageways 64, 66, 68, 70.
Compression spring 44 is shown as fully-compressed in FIG. 8A, as the spring
would be when aerosol valve 40 is fully-actuated. FIG. 8B is an identical view
to
FIG. 8A, but with shading to clearly illustrate these components.
[0036] FIG. 9 illustrates valve 40 in mid-stroke, which is an
intermediate,
short-lived position of the valve as the valve transitions from an unactuated
(closed) position to its fully-actuated (open) position when the valve stem is
pressed by the consumer to spray the product. While the valve is in this
intermediate position, the product formulation is propelled upward primarily
by
primary flow path 60 through the center of compression spring 44. However, in
this brief transition time, some of the product formulation is moving around
spaces 45 between the coils of compression spring 44 in secondary flow path
62.
[0037] FIGS. 10 and 11 show a cross-section of valve 40 in its fully-
actuated position. Valve stem 46 fully compresses compression spring 44, which
reduces or eliminates spaces 45 between the coils. Thus, as shown clearly in
FIG. 11, at full-stroke, nearly all (or all) of the product formulation moves
upward
in aerosol valve 40 through the center of compression spring 44, which is
shown
as primary flow path 60. Primary flow path 60 is shorter and less tortuous as
compared with the flow paths in existing aerosol valves (for example, as
compared with the primary flow path 30 in the prior art described above). This
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shorter, less tortuous flow path reduces the likelihood of agglomeration of
the
solids in the product formulation, and reduces produce failures.
[0038] As shown in FIG. 11 (as well as in FIGS. 7A-7B and 8A-8B), the
geometry of compression spring 44 and large passageways 64, 66, 68, 70 direct
the ingress of the product formulation to flow upward almost exclusively along
primary flow path 60 through the center of compression spring 44, and to exit
the
upper end of compression spring 44 still within the space circumscribed by the
spring coils.
[0039] Conversely, as also shown in FIG. 11, the interaction between
valve
stem 46 and compression spring 44 when valve 40 is actuated allows very little
or
none of the product formulation to move upward via secondary flow path 62,
which is a path along the outside of compression spring 44 and between the
individual coils. Again, this is because there is little or no space between
individual coils when the aerosol valve is fully actuated. Since there is much
less
of the product formulation moving along this longer, tortuous (secondary)
route,
there is reduced incidence of agglomeration of solids in the flow paths and,
consequently, fewer product failures.
[0040] In an exemplary embodiment, the product formulation of the present
disclosure is a mixture of two types of media, such as a mixture of a powder
(solids) and propellant.
EXPERIMENTAL
[0041] Testing the proposed aerosol valve with high-solids product
formulations has resulted in no recordable instances of failure of the product
to
dispense throughout full-life testing. This is in contrast to laboratory
testing with
known, existing aerosol valve designs that failed due to agglomeration with a
difficult, high-solids formulation that showed a propensity to agglomerate.
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[0042] A method of using the free flow aerosol valve described above for
delivery of high-solids product formulations is also provided. The method uses
the aerosol valve having shorter flow paths, fewer direction changes, and
larger
passageways as compared with existing aerosol valves to minimize
agglomeration of solids in the flow paths and reduce product failures due to,
for
example, blockage of flow paths.
[0043] As used in this application, the word "about" for dimensions,
weights,
and other measures means a range that is 10% of the stated value, more
preferably 5% of the stated value, and most preferably 1% of the stated
value, including all subranges therebetween.
[0044] It should be understood that the foregoing description is only
illustrative of the present disclosure. Various alternatives and modifications
can
be devised by those skilled in the art without departing from the disclosure.
Accordingly, the present disclosure is intended to embrace all such
alternatives,
modifications, and variances that fall within the scope of the disclosure.
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