Note: Descriptions are shown in the official language in which they were submitted.
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CHECK VALVE FOR VENTING AN ENCLOSURE USING SURFACE TENSION BETWEEN DIFFERENT
FLUIDS
FIELD OF THE INVENTION
THIS INVENTION relates to a pressure
equalization valve for venting a flow of fluid from a
fluid containing space such as a container. In a
particular, the valve allows the inflow of air to balance
the outflow of liquid from a container without
interrupting the fluid flow.
The invention finds particular application in
venting the flow from a container of viscous liquids,
such as oil or syrup, as well as low viscosity liquids,
such as milk.
BACKGROUND TO THE INVENTION
A wide variety of different venting
arrangements are known for assisting the dispensing of
fluid from a container. The simplest arrangement is to
provide an air inlet port above the fluid level. For
instance, a fuel container often has two ports on a top
portion. One port is for dispensing fuel and the other
port allows air into the container to replace the
dispensed fuel. The fuel must be poured carefully to
ensure the fluid level does not get above the air inlet
port. If this happens, fuel spills from both ports and
causes a hazard.
In many applications, however, the above
arrangement cannot be used. For example, there are
situations in which it is desirable to completely invert
a container when dispensing a fluid within to avoid
problems of directing a stream of the fluid into a narrow
opening of a receiving vessel. If such inversion does
not take place, the stream of fluid often strays outside
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the opening, either due to the size of the opening or to
an unsteady hand.
One example in which container inversion is
required is the pouring of oil into a car engine . To
minimize spillage, an oil bottle is usually completely
inverted with the neck of the bottle inserted into the
oiI inlet. As the oil flows from the bottle, the
pressure within the bottle drops due to inadequate
venting, and flow slows until an air bubble bursts
through the oil against the flow. Since conventional oil
bottles can be inserted into the oil inlet of an engine,
this is not much of a problem. However, larger oil
containers, as for example 4 liter oil containers, are
not provided with necks sufficiently long for insertion
into the oil inlet. Therefore, complete inversion of
such oil containers would typically result in spillage
of the oil. This means that larger oil containers must
be partially and carefully inverted to direct a stream
of oil into the oil inlet. However, the inadequate
venting problem associated with conventional oil
containers remains, leading to an uneven flow of oil and
even surges of flow that generally cause splashing and
spillage of the oil.
Moreover, larger containers such as those used
for transfer of cooking or machine oils, cleaning fluids,
pesticides, fertilizers, and even biological substances
suffer another disadvantage. When fluid is being poured
from such containers, the turbulence created by surges
of flow of fluid can shift considerably the weight of the
container making it difficult to hold steady and/or to
dispense a particular volume of fluid.
Disadvantages associated with container
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inversion also apply to nursing or baby's bottles. The
infant sucks the liquid from a baby's bottle thereby
generating a vacuum in the bottle. Eventually the vacuum
generated in the bottle prevents continued flow of the
liquid. At this point a bubble bursts through the liquid
to equalize the pressure and flow continues. Sometimes,
the bubbles are entrained by the liquid flow and ingested
by the baby. This can contribute to colic.
A number of attempts have been made to produce
a valve that regulates flow from a baby's bottle. One
such attempt is described in United States patent number
US 5,399,971 in the name of Rbhrig. This patent
discloses a feeding bottle having a microporous air inlet
in the base. The micropores are sufficiently small to
prevent liquid leaking from the bottle but sufficiently
numerous to provide adequate venting of the bottle.
Production of a container incorporating a microporous
base is difficult and therefore expensive. In many
applications the additional production cost renders the
solution nonviable.
Another option is described in United States
patent number US 5,284,261 to Zambuto. Zambuto describes
an insert placed between the bottle and the teat that
provides a path to allow air to enter the bottle but to
prevent liquid exiting the bottle. Operation of the
Zambuto arrangement relies on holes in the insert being
small enough that liquid will not flow through.
The problem of venting a baby's bottle has not
yet been satisfactorily addressed. A very recent United
States patent (US 5,699,921) in the name of Rodriguez
seeks to address the problem of letting air into a baby's
bottle by providing a one way valve in the base of the
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bottle. However, the Rodriguez arrangement is unduly
complex which would substantially inflate production
costs.
As mentioned above, the venting problem is not
restricted to baby's bottles. United States patent
number US 4,753,546, to Witz et aI, describes a pressure
balanced stylographic pen. Witz et al describe a vent
channel of varying cross-sectional area that exactly
balances the capillary pressure on the meniscus of a
column of ink against the gravitational pressures forcing
the ink from the pen. Although not directly related to
the venting problems described above, the Witz patent
includes a useful analysis of the LaPlace equation as it
relates to the net pressure at a curved air/liquid
interface.
OBJECT OF THE INVENTION
It is an object of the present invention to
substantially overcome one or more of the problems
identified in the known prior art.
Further objects will be evident from the
following description.
DISCLOSURE OF THE INVENTION
According to one aspect of the invention, there
is provided a valve for inhibiting egress therethrough
of a first fluid in a first fluid-containing space and
for permitting entry therethrough of a second fluid in
a second fluid-containing space, said valve comprising:
a port formed in a wall separating the first
fluid-containing space and the second fluid-containing
space, said port communicating between the first fluid
containing space and the second fluid containing space;
a working space adjacent the port, said working
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space diverging from the port towards the first fluid-
containing space; and
a fluid interface forming in said working
space, in use.
5 Preferably, the working space is frusto-
conical.
In use, the second fluid from the second fluid-
containing space moves across the interface to the first
fluid-containing space to equalize a pressure difference
between the first fluid-containing space and the second
fluid-containing space. Typically, the first fluid in the
first fluid-containing space is a liquid and the second
fluid in the second fluid-containing space is air. In
this instance, it will be appreciated that the fluid
interface forming in the working space is a meniscus.
Preferably, the first fluid-containing space
has an outlet associated therewith through which the
first fluid is dispensed thereby causing a reduction in
pressure within the first fluid-containing space.
Suitably, the first fluid-containing space may
define the interior of a container. In such a case, the
wall separating the first fluid-containing space and the
second fluid-containing space may define a wall
associated with the container. For example, in this
instance, the wall may be a wall of the container, or a
wall of a discharge member associated with the container.
Alternatively, the first fluid-containing space
may define the interior of a conduit member for conveying
the first fluid from a fluid source. In this case, the
wall may define a wall of the conduit member. The
conduit member may comprise any suitable tubing, hose,
pipe, vessel and the like. Alternatively, the conduit
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member may comprise a hollow connecting piece for
connecting two or more conduits in fluid communication
therebetween.
In another aspect, the invention resides in a
container having at least one valve comprising:
a port formed in a wall of the container and
communicating between an interior of the container and
an exterior of the container;
a working space adjacent the port, said working
space diverging from the port towards the interior of the
container; and
a fluid interface forming in said working
space, in use:
The at least one valve may project outwardly
of the container. In such a case, the at least one valve
may extend from a recessed portion of the container wall
such that the port of the valve is coextensive with, or
inwardly of, an exterior surface of the container wall
adjacent the recessed portion.
The at least one valve may be disposed at any
suitable location in the container. In preference, the
at least one valve is located in a top portion of the
container and more preferably, adjacent a fluid outlet
of the container.
Suitably, the at least one valve is sealable
by a sealing means. For example, the sealing means may
comprise a cover or collar adapted to engage the
container and to seal the at least one valve.
The container may be used for any suitable
application which requires fluid to be dispensed
therefrom. For example, the container may be a nursing
or baby's bottle. Alternatively, the container may be
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an oil bottle or container.
In yet another aspect, the invention provides
a discharge member for discharging a fluid from a
container, said discharge member including at least one
valve comprising:
a port formed in a wall of the discharge member
and communicating, in use, between an interior of the
container and an exterior of the container;
a working space adjacent the port, said working
space diverging, in use, from the port towards the
interior of the container; and
a fluid interface forming in said working
space, in use.
Preferably, a fluid outlet of the discharge
member is adjacent said wall.
Suitably, a plurality of said valves are formed
in said wall and are concentrically disposed adjacent the
periphery of the fluid outlet.
In preference, the discharge member comprises
a nozzle, spout, mouthpiece and the like. Alternatively,
the discharge member may comprise an aperture through
which a nursing teat is projectable.
In a further aspect, the invention provides a
conduit member for conveying a fluid from a fluid source,
said conduit member including at least one valve
comprising:
a port formed in a wall of the conduit member
and communicating between an interior of the conduit
member and an exterior of the conduit member;
a working space adjacent the port, said working
space diverging from the port towards the interior of the
conduit member; and
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a fluid interface forming in said working
space, in use.
In yet another aspect, the invention resides
in a method of venting flow of a first fluid from a first
fluid-containing space, said method including the step
of
forming a fluid interface in or adjacent a vent
associated with the first fluid-containing space such
that the fluid interface inhibits egress of the first
fluid from the vent and permits entry of a second fluid
from a second fluid-containing space exterior of the
first fluid-containing space.
In a still further aspect of the invention,
there is provided a method of venting flow of a liquid
into a container having a liquid inlet port and having
at least one valve comprising a port formed in a wall
associated with the container and communicating between
an interior of the container and an exterior of the
container, a working space adjacent the port, said
working space diverging from the port towards the
interior of the container, and a fluid interface forming
in said working space, in use, said method including the
step of
dispensing the liquid into the container
through the liquid inlet port to cause egress of a gas
within the container through the at least one valve.
Throughout this specification and the appendant
claims, unless the context requires otherwise, the words
"comprise", "comprises" and "comprising" will be
understood to imply the inclusion of a stated integer or
group of integers but not the exclusion of any other
integer or group of integers.
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B RIEF DESCRIPTION OF THE DRAWINGS
To assist in understanding the invention
preferred e mbodiments will now be described with
reference to the following figures in which .
FIG 1 is a perspective view of a first
embodiment of a valve employed on a
container;
FIG 2 is a cross-sectional view of the
embodiment of FIG 1;
FIG 3 is an enlarged view of a portion of
FIG 2;
FIG 4 is a cross-sectional view of another
embodiment of the invention showing
the method of operation;
FIG 5 is a cross-sectional view of yet
another embodiment of the invention
applied to a baby's bottle;
FIG 6 is a cross-sectional view of a
further embodiment of the invention
applied to an oil container;
FIG 7 is a top view of the embodiment of
FIG 6;
FIG 8 is an enlarged view of a portion of
the last mentioned embodiment;
FIG 9 is a cross-sectional view of yet a
further embodiment of the invention
applied to a tube; and
FIG 10 is a cross-sectional view of a still
further embodiment of the invention
applied to a hollow connecting a
pair of tubes.
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DETAILED DESCRIPTION
In the drawings, like reference numerals refer
to like parts. In FIG's 1 - 3 there is shown a valve 1
formed in the wall of a container 2 holding a liquid 3.
5 The container 2 has an outlet 4 from which fluid 3 flows
when the container 2 is inverted (as shown in FIG 2) or
partially inverted.
The valve 1 comprises a port 5 communicating
between the interior of the container and the exterior
10 of the container. The wall 6 of the container 2 in the
vicinity of the port 5 slopes away from the port so as
to form a working space 7 in which an air pocket is
formed. The working space 7 has a smaller cross-sectional
area near the port 5 than at the interior of the
container 2. The working space is shown as frusto-conical
although other shapes, such as pyramidal, will be
suitable. The port may also take different shapes such
as circular, square or hexagonal.
In the present embodiment, the valve 1 projects
outwardly of the container 2 extending from a recessed
portion 100 such that the port 5 is substantially
coextensive with an exterior surface 101 adjacent the
recessed portion 100.
A meniscus 8 forms at the interface between the
liquid 3 in the container 2 and the gas (normally air)
in the working space 7. The meniscus prevents the liquid
3 from leaking from the container 2 through port 5.
The position of the meniscus 8 in the working
space 7 will be determined by the pressure difference
between the interior and the exterior of the container.
As fluid 3 flows from the container 2 the pressure within
the container drops. In the absence of the valve 1 the
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flow would cease or be slowed until a bubble of air
bursts through outlet 4 against the flow. However, as
shown in FIG's 2 - 3, the valve allows air to enter the
container through the port thereby equalizing the
pressure difference and allowing flow of fluid through
outlet 4 to continue without disruption.
The process of pressure equalization can best
be described by reference to a second embodiment of the
valve shown in FIG 4. In FIG 4, the valve 9 has been
simplified to a port 10 in wall 11 of a container (not
shown) opening to a working space 12 formed in the wall
11. The liquid on the space side of the wall has been
omitted for clarity.
Due to surface tension, a meniscus 13 forms in
the working space 12 at a position determined by the
properties of the fluid in the container, the gas outside
the container, the wall material and ambient pressure,
as shown in FIG 4(a). The analysis provided in US
4,753,546 is useful for calculating the position of the
meniscus, if desired. As fluid flows from the container,
the pressure within the container drops and the position
of the meniscus moves, as depicted in FIG 4(b). Air
fills a larger portion of the space 12. At some point,
a bubble 14 forms and breaks away from the valve 9, as
shown in FIG 4(c). The meniscus 13 reforms and the
process is repeated as long as fluid flows from the
container and the fluid level remains above the level of
the valve 9. The bubbles of air from the exterior of the
container replace the fluid flowing from the container
so flow continues without disruption, as indicated in FIG
2.
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The inventor has found that the valve may
usefully be employed on a baby's bottle as depicted in
FIG 5. FIG 5 shows a bottle 20 to which a teat 21 is
attached by nut 22. The teat is protected by cap 23
which clips to the bottle, such as in the manner shown.
In conventional manner, the bottle 20 is open at one end
to allow flow of liquid from the bottle and out the teat
21.
A valve 24 is formed in the neck 25 of the
bottle 20. When the bottle 20 is inverted, liquid in the
bottle covers the valve and a fluid interface is formed,
as described above. It will also be appreciated that
when cap 23 is clipped onto the bottle as shown, it seals
the valve 24 against entry of air exterior of the bottle
20.
Another application found by the inventor is
shown in FIG 6. In FIG 6 there is shown a container 30
holding a viscous fluid 31, such as oil. Part of one
wall of the container is formed by a cap 32 screwed onto
the container 30. The cap has an outlet 33 for
dispensing fluid 31 by inverting the container 30. Oil
is typically dispensed by inverting the container so that
an outlet 33 is inserted into the oil reservoir of a
vehicle (not shown).
A plurality of valves, such as 34, are formed
in the cap 32. It is convenient to form the valves
concentrically around the outlet, as shown in FIG 7,
although not essential to do so. Each valve has the
configuration shown in FIG 8. A port 35 communicates
between the exterior and interior of the container. A
meniscus 36 forms in the working space 37 adjacent the
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port 35. The working space 37 is formed by the wall 38
of the cap 32 diverging away from the port 35.
As fluid 31 flows from the outlet 33, a stream
of bubbles, such as 39, carry air into the container to
replace the fluid. In the absence of the valves, the
fluid flow slows until a bubble bursts through the fluid
against the flow.
The embodiment shown in FIG~s 6-8 has the
advantage of having the valves as near as possible to the
outlet. This ensures that the fluid covers the valves
for as long as possible. The inventor has found that the
valves self-regulate the flow of fluid from the container
so there is advantage in,positioning the valves close to
the outlet. Once the fluid level gets below the position
of the valve, air is able to flow directly into container
and the rate of flow of fluid from the container
increases.
The inventor has also found that the valve may
be employed advantageously in a conduit such as a tubing,
as for example shown in FIG 9 for conveying a fluid. In
FIG 9, a plastics tubing 200 is shown conveying a fluid
201A from a container 201 in the direction of the arrow
to a fluid destination (not shown). A valve 202 is
formed in the wall of tubing 200, comprising a port 203
opening to a working space 204 in which a meniscus 205
forms. The inventor has found that application of the
valve to conduits such as tubing and the like assists
venting of fluid flow from a suitable fluid source such
as a container. In this embodiment, when fluid flows
from the container 201 along tubing 200, a decrease in
pressure will result within the tubing 200 relative to
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the tubing exterior. This will cause an inflow of air
into the tubing and consequent formation of bubbles 206.
The bubbles so formed will then travel along the tubing
against the flow of fluid 201A to replace the fluid
flowing from the container 201 so that flow continues
without disruption. Those of ordinary skill in the art
will appreciate that the diameter of tubing will be
selected to be substantially greater than the diameter
of the bubbles 206 entering the tubing from valve 202.
This is important so that the bubbles entering the tubing
do not interfere with fluid flow in the opposite
direction.
The valve does not have to be formed in the
wall of the tubing. In this regard, the valve may be
applied to a hollow tubing connector as for example shown
in FIG 10. The tubing connector shown generally at 300
fluidly connects two pieces of tubing 301, 302 which are
fluidly connected to a fluid source (not shown) for
conveying a fluid 303 in the direction of the arrow to
a selected destination (not shown). Connector 300 has
a substantially cylindrical body 304 and a pair of
tapered ends 305, 306 to which are sealingly fitted ends
301A and 302A of tubes 301, 302. A pair of valves 307,
308 are formed in the wall of body 304. Each valve
comprises a port 309 communicating between the exterior
and interior of the connector 300. In use, a meniscus
310 forms in a working space 311 adjacent the port 309
as described in the aforementioned embodiments. The
present embodiment provides a relatively facile means
by which fluid flow from a fluid source can be adequately
vented. In this regard, a connector, as for example
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shown in FIG 10, can be fitted with relative ease to an
existing conduit by cutting the conduit at a desired
location to form two free ends and subsequently
connecting the connector therebetween.
5 The valve is useful for venting gravity
assisted flows, such as the oil container embodiment, or
vacuum assisted flows, such as the baby bottle example.
The valve is also useful when filling a container. When
a container, for example the container of FIG 6, is
10 upright the valve will be above the fuel level and
therefore a fluid interface will not form. Liquid may
then be poured in the outlet with air in the container
being expelled through the valve. The valve may also be
employed in conduits, conduit connectors and the like for
15 venting fluid flow from a fluid source such as a
container.
The inventor has also found that the rate of
fluid flow from a fluid source may be regulated by the
application of different numbers of valves. For example,
a single valve may be provided for applications in which
the rate of fluid flow from a fluid source is desired or
required to be relatively low. Alternatively, a
plurality of valves may provided for applications in
which the rate of fluid flow is desired or required to
be high.
As will be appreciated, the valve is
particularly simple to manufacture but very effective.
It substantially overcomes the problems of venting the
flow of fluid from a container, for example, and is self
regulating. The valve can be formed in virtually any
container, discharge member or conduit member.
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Throughout the specification the aim has been
to describe the preferred embodiments of the invention
without limiting the invention to any one embodiment or
specific collection of features. It will therefore be
appreciated by those of skill in the art that, in light
of the instant disclosure, various modifications and
changes can be made in the particular embodiments
exemplified without departing from the scope of the
invention. All such modifications and changes are
intended to be included within the scope of the appended
claims.
