Note: Descriptions are shown in the official language in which they were submitted.
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METERING VALVE FOR DISPENSERS
The invention relates to improvements in metering
valves for use in dispensing apparatus.
Dispensing apparatus, for dispensing metered
doses of product, generally comprise a valve attached
to a dispensing container in which the product to be
dispensed is stored. The valve is held in position
relative to the dispensing container by means of a cap
or ferrule which is crimped to an open neck of the
container.
Tn metered dose valves, a metering chamber is
provided sealed at respective inner and outer ends by
inner and outer seals. The outer seal prevents
leakage of product between the metering chamber and
atmosphere when the apparatus is in a non-dispensing
position. The inner seal prevents leakage of product
between the container and the metering chamber when
the dispensing apparatus is in an operative,
dispensing position. In addition in order~to provide
an adequate seal to prevent loss of the stored
product, an elastomeric sealing gasket is provided
between the cap or ferrule and container.
Assembly of the inner and outer seals and the
elastomeric gasket with the remainder of the
components of the metering valve requires a number of
assembly steps which can be time consuming and
difficult to achieve, in part due to the small size of
the components. In particular, the assembly of the
inner seal and the elastomeric gasket with the valve
body of the metering valve firstly requires inner and
outer members of the valve body to be assembled,
sandwiching the inner seal between the inner and outer
members. Up until this point in the assembly process,
the inner seal is held in position relative to the
valve body only by frictional forces set up between
the inner seal and the inner member of the valve body.
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A problem found with this arrangement is that during
manipulation of the inner member in preparation for
assembly with the outer member the inner seal may
potentially be displaced from its correct position.
The elastomeric gasket is then push-fitted onto
the valve body.
The outer seal is assembled with the outer member
and the cap or ferrule is then placed over the valve
stem to retain the outer seal on the valve body. A
problem found with this arrangement is that during
manipulation of the valve body in preparation for
assembly with the cap or ferrule the outer seal may
potentially be displaced from its correct position.
The metering valve is then attached to a
dispensing container by crimping the cap or ferrule
over the open end of the dispensing container such
that the neck portion of the container engages the
elastomeric gasket. Up until this point in the
assembly process, the elastomeric gasket is retained
on the valve body only by frictional forces set up
between the elastomeric gasket and the inner member.
A problem with this arrangement is that during
manipulation of the inner member during assembly with
the outer member, and during manipulation of the
assembled valve body during assembly with the
dispensing container, the elastomeric gasket may
potentially be dislodged from its correct position on
the valve body.
According to the present invention there is
provided a metering valve for assembly with a
pressurised dispensing container, the valve comprising
a valve stem co-axially slidable within a valve body
defining a metering chamber, inner and outer seals for
sealing between the valve body and the valve stem, and
a gasket located on the valve body for sealing against
a neck portion of a pressurised dispensing container,
wherein at least one of the inner seal, outer seal or
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gasket is formed as a co-moulding with at least a part
of the valve body.
There is also provided a co-moulding for use in a
metering valve comprising at least a part of a valve
body, inner seal and gasket formed as a unitary
component.
There is also provided a co-moulding for use in a
metering chamber comprising at least a part of a valve
body and a seal formed as a unitary component.
The present invention also discloses a method of
manufacturing a co-moulding for use in a metering
valve comprising the steps of forming a first mould
shape, injection moulding a first material to form a
part of a valve body, forming a second mould shape
containing the part of the valve body, and injection
moulding a different material to form at least one
sealing element in intimate relationship with the part
of the valve body.
Embodiments of the present invention will now be
described, by way of example only, with reference to
the accompanying drawings in which:
Figure 1 shows a cross-sectional side elevation
of a metering valve according to the present
invention;
Figure 2a shows a perspective view of a sectioned
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inner member of a valve body of the metering valve of
Figure 1;
Figure 2b shows a perspective view of the inner
member of Figure 2a from a different angle;
Figure 3 shows a perspective view of a sealing
gasket and inner seal of the metering valve of Figure
1;
Figure 4a shows a plan view of the inner member
of Figure 2a moulded with the sealing gasket and inner
seal of Figure 3;
Figure 4b shows a perspective view of the
arrangement of Figure 4a sectioned on line IVB-IVB of
Figure 4a;
Figure 5a shows a perspective view of a sectioned
outer member of the valve body of the metering valve
of Figure 1;
Figure 5b shows a perspective view of the outer
member of Figure 5a from a different angle;
Figure 6 shows a perspective view of an outer
seal of the metering valve of Figure I;
Figure 7a shows a plan view of the outer member
of Figure 5a moulded with the outer seal of Figure 6;
and
Figure 7b shows a perspective view of the
arrangement of Figure 7a sectioned on line VIIB-VIIB
of Figure 7a.
The metering valve 10 of the present invention,
as shown in Figure 1, is connectable in use to a
dispensing container (not shown] in which a product to
be dispensed in metered doses is stored. The product
may, for example, be a liquid or a drug substance held
in suspension or in solution and expelled using a
volatile liquified propellant such as a CFC or an HFA
or blends thereof.
The valve 10 is held in position to seal the
dispensing container by a cap or ferrule 13 which is
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crimped to the open neck of the container.
The valve 10 comprises a valve stem 20 which
extends coaxially within a generally cup-shaped outer
member 17 so as to be externally accessible.
In the following description and claims the term
"inner" is used to mean being relatively remote from a
dispensing end of valve stem 20. The term "outer" is
used to mean being relatively proximate a dispensing
end of valve stem 20.
The valve 10 further comprises an inner member
16, a gasket 14, an inner seal 25 and an outer seal
18.
The inner member 16 and outer member 17 together
define a valve body 12.
The outer member 17, preferably of a polymeric
material, has at an outer end a base 21, in which is
located an aperture 22, and side walls 23 defining an
open end to the outer member 17. Sandwiched between
the base 21 of the outer member 17 and the ferrule 13
is the outer sliding seal 18 of an elastomeric
material which also has an aperture therein.
The valve stem 20, preferably of a polymeric or
metallic material, has at one end. a generally hollow
section 25 defining a dispensing channel in which
portion 25 is located a port 26, and at its other end
a piston 27 having a larger cross-sectional area than
the hollow section 25. The hollow section 25 extends
from the container and the piston 27 is received in
and is slidable relative to the outer member 17. The
external diameter of the piston 27 is selected to be
smaller than the internal diameter of the outer member
17 thus leaving a radial clearance 28.
The inner member 16 covers off the open end of
the outer member 17 and is secured in position by a
flange portion 30 which is clamped between the ferrule
13 and the gasket 14 when the valve 10 is assembled
with the dispensing container. The inner member 16
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has entry ports 31 to allow the liquefied product to
access the inside of the valve 12.
A return spring 19, preferably of stainless
steel, is located between a base of the inner member
16 and the piston 27 thereby urging the piston 27 into
contact with the base 21 of the outer member 17.
In known metering valves the inner member, outer
member, gasket, inner seal and outer seal are provided
as separate components which must be assembled with
20 one another during assembly of the metering valve 10.
According to the present invention a co-moulded
inner member, generally referenced in the accompanying
Figures by numeral 11, and a co-moulded outer member,
generally referenced in the accompanying drawings by
numeral 61, are provided.
The co-moulded inner member 11 and co-moulded
outer member 61 together define a valve body 12.
The co-moulded inner member 11 comprises an inner
member 16, inner seal 15 and gasket 14 formed as a
single unitary component by means of a co-moulding
manufacturing process. The co-moulded outer member 61
comprises an outer member 17 and an outer seal 18
formed as a single unitary component by means of a co-
moulding manufacturing process.
The co-moulded inner member 11 is formed using
two moulding steps. A first mould shape is formed by
a mould tool and a first material is injection moulded
into the mould shape to form the core component of the
inner member 16 as shown in Figures 2a and 2b. A
second mould shape is then formed which contains the
core component. Preferably the same mould tool is
used to form the first and second mould shapes by
means of actively controlled components of the mould
tool which may be moved relative to one another to
vary the configuration of the mould shape and to
provide the necessary flow paths for the injection
process.
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A second material is then injected into the
second mould shape to form the inner seal 15 and
gasket 14. Since the core component of the inner
member 16 is present in the second mould shape the
inner seal 15 and gasket 14 are intimately moulded
with the inner member 16 such that a strong mechanical
bond is achieved between the inner seal 14, gasket 15
and inner member 16 as shown in Figures 4a and 4b.
The form of the gasket 24 and inner seal 15 is
shown in Figure 3 and the form of the finished co-
moulded valve body 11 is shown in Figures 4a and 4b.
The gasket 14 and inner seal 15 are provided with
keyed portions 33 which matingly engage with keyways
34 in the inner member 16. The keyed portions 33 and
keyways 34 improve the mechanical bonding between the
inner member 16 and the gasket 14 and inner seal 15.
Similarly, the co-moulded outer member 61 is
formed using two moulding steps. A first mould shape
is formed by a mould tool and a first material is
injection moulded into the mould shape to form the
core component of the outer member 17 as shown in
Figures 5a and 5b. A second mould shape is then
formed which contains the core component. Preferably
the same mould tool is used to form the first and
second mould shapes by means of actively controlled
components of the mould tool which may be moved
relative to one another to vary the configuration of
the mould shape and to provide the necessary flow
paths for the injection process.
A second material is then injected into the
second mould shape to form the outer seal 18. Since
the core component of the outer member 17 is present
in the second mould shape the outer seal 18 is
intimately moulded with the outer member 17 such that
a strong mechanical bond is achieved between the outer
seal 18 and outer member 17 as shown in Figures 7a and
7b.
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The form of the outer seal 18 is shown in Figure
6 and the form of the finished co-moulded outer member
61 is shown in Figures 7a and 7b. The outer seal 18 is
provided with keyed portions 63 which matingly engage
with keyways 64 in the outer member 17. The keyed
portions 63 and keyways 64 improve the mechanical
bonding between the outer member 17 and the outer seal
18.
An advantage of this method of forming the co-
20 moulded inner member 11 and co-moulded outer member 61
is that a first material may be used to form the inner
member 16 and outer member 17 and a different material
used to form the sealing elements, namely the gasket
14, inner seal 15 and outer seal 18. Thus the optimum
material for each portion of the metering valve 10 may
be utilised. A further advantage is that the finished
co-moulded inner 11 and co-moulded outer member 61 are
single unitary components wherein there is no risk of
the gasket 14, inner seal 15 and outer seal 18
becoming detached during manipulation and assembly
with the remainder of the metering valve 10. Thus,
the ease of assembly of the metering valve is much
improved and the number of assembly steps required in
assembling the metering valve is significantly
reduced. This has consequential time and cost
savings.
The inner member 16 and outer member 17 may be
formed, by way of example only, from any of:
acetal;
nylon; and
polyester.
The outer member 17 and inner member 16 may be
formed from different materials.
The gasket 14, inner seal 15 and outer seal 18
may be formed by way of example only, from any of:
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polyurethane (aromatic polyether or aromatic
polyester);
thermoplastic vulcanizates (being a blend of a
plastic part selected from polypropylene,
polyethylene or polystyrene and a crosslinked
elastomer selected from polyisprene,
polybutadiene, polyethylene propylene,
polychloroprene, polyacrylonitrile butadiene,
polyisobutyl or other crosslinkable elastomers);
polystyrene polyethylenebutylene block
copolymers;
polystyrene polybutadiene block copolymers;
thermoplastic polyolefin (such as ethlyene
propylene rubber);
co polyether ester;
polyether block amides: and
polyethylene copolymers.
The outer seal 18 may be formed from a different
material compared to the inner seal 15 and gasket 14.
In use, the valve stem 20 of the metering valve
10 is displaced axially relative to the remainder of
the valve 10 against the bias of spring 19. As this
occurs, a temporary chamber is created between the
valve stem 20 and the outer member 17. Product flows
through the radial clearance 28 between the piston 27
and the outer member 17 and flows into the chamber
until a lower edge of the piston 27 contacts the inner
seal 15 of the co-moulded inner member 11. A liquid-
tight seal is created at that point of contact which
prevents further ingress of product. The metered dose
of product to be dispensed is defined by the volume of
the chamber and the clearance 28. Further depression
of the valve stem 20 causes the port 26 in the hollow
section 25 of the valve stem 20 to pass through the
outer seal 18 and into the chamber. The preferred
propellant systems are liquified gases or combinations
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thereof having boiling temperatures significantly
below room temperature. As a result, the product
boils evacuating the contents of the chamber through
the port 26 into the dispensing channel in the hollow
section 25 of the valve stem 20 thus providing an exit
path for the product.
Release of the valve stem 20 allows the spring 19
to recover thereby forcing the valve stem 20 to return
to its rest position and the metering chamber
disappears as the piston 27 approaches the base 21 of
outer member 17.
In another embodiment the inner seal 15, outer
member 17 and outer seal 18 may be formed as a single
unitary component by means of a co-moulding.
Whilst the co-moulded inner member 11 and co-
moulded outer member 61 have been described in the
above embodiment for use in a metering valve having a
temporary metering chamber, it should be appreciated
that the co-moulded inner member 11 and co-moulded
outer member 61 are also suitable for use in metering
valves in general, for example those having permanent
metering chambers.
