Note: Descriptions are shown in the official language in which they were submitted.
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CLOSURE FOR A CONTAINER
TECHNICAL FIELD
This invention relates to a closure for a container, in particular a closure
for a beverage or other
foodstuff (although the closure can be used on other types of container).
BACKGROUND ART
A variety of closures for beverage containers are known. For example, cap-on-
collar closures as
described in W02006/000774 and W02007/091068 and one-piece twist-off closures
as described in
W02007/057659. Such prior art describes a variety of seal members, such as
compression gaskets,
for providing a seal between the closure and the container.
There is a requirement to provide a seal which is able to withstand high
pressures within the container,
eg when the container holds a carbonated beverage and is subject to high
temperatures, yet which
does not make it difficult for a user to remove the closure from the
container. A variety of problems can
arise with such seals, for example: high frictional engagement between the
seal and the container,
(particularly for wide-mouth containers), seals losing their resilience and/or
becoming adhered to the
container after prolonged storage and imperfections in the seal or the
container (particularly if a glass
container is used) leading to weak points in the seal.
The present invention provides an alternative form of seal for such closures
which seeks to reduce or
overcome one or more of the problems experienced with the prior art.
SUMMARY OF THE INVENTION
According to a first aspect of the invention, there is provided a closure for
a container having a
substantially circular opening defining an axis, the closure being securable
to the container so as to
close said opening, the closure having an o-ring sealing member mounted or
mountable thereon so as
to provide a seal with a sealing surface of the container, said sealing
surface extending around an
upper surface or an internal surface of the container.
It should be noted that the term o-ring seal as used herein is to be
understood to include a seal
comprising a toroid or loop of elastomer material having a circular cross-
section, as well as other cross-
sections, including an oval cross-section, a substantially square cross-
section and a x-shaped cross-
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section (sometimes referred to as an x-ring). It is also to be understood to
cover other forms of seal
which simulate the function of an o-ring (as described further below).
In addition to the elastomer toroid, an o-ring seal comprises a groove
(referred to as a gland) in which
the toroid is located. This groove typically has a substantially square cross-
section but other shapes
can be used, including triangular and semi-circular. The groove provides
locating means for locating
the o-ring and at least one side wall. The side wall is located so that when
one side of the o-ring is
subject to elevated pressure, the o-ring is pressed against the side wall so
as to seal a gap between
the side wall and the sealing surface of the container body. For a container
in which the internal
pressure is reduced, eg a vacuum pack, the side wall is on the inner side of
the o-ring and for a
container in which the internal pressure is elevated, the side wall is on the
external side of the o-ring. If
a side wall is provide on both sides of the o-ring, it can provide a sealing
function in both
circumstances.
The invention also relates to a closure as described above in combination with
a container adapted to
be closed by said closure.
The invention is particularly applicable to widemouth closures (eg with a
diameter of 50 to 80 mm) as
the larger the opening the more difficult it is to provide an effective and
reliable seal between the
closure and the container whilst ensuring the closure is still relatively easy
to remove. However, the
invention is also applicable to narrower openings, eg of a bottle such as
those having a 28 mm
diameter opening.
Directional terms, such as upper and lower, as used herein are to be
understood to refer to refer to
directions relative to a container standing on a horizontal surface with the
axis passing through its
opening being substantially vertical (unless the context clearly requires
otherwise).
Preferred and optional features of the invention will be apparent from the
following description and from
the subsidiary claims of the specification.
BRIEF DESCRIPTION OF DRAWINGS
The invention will now be further described, merely by way of. example, with
reference to the
accompany drawings, in which:
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Figure 1 is a part cross-sectional view of a first embodiment of a closure
according to the present
invention when fitted to a container body;
Figure 2 is a part cross-sectional view of a second embodiment of a closure
according to the present
invention when fitted to a container body;
Figure 3 is a part cross-sectional view of a third embodiment of a closure
according to the present
invention when fitted to a container body;
Figure 4A is a perspective view of a fourth embodiment of a closure according
to the present invention
and of a container body to which it can be fitted;
Figure 4B is a perspective view, part cut-away, of the fourth embodiment when
fitted to the container;
Figure 5A is a perspective view, part-cut-away, of a fifth embodiment of a
closure according to the
present invention when fitted to a container body;
Figure 5B is a perspective view, part-cut-away, of a modified version of the
fifth embodiment using a
different form of o-ring;
Figure 6A is a perspective view, part-cut-away, of a sixth embodiment of a
closure according to the
present invention when fitted to a container body;
Figure 6B is a perspective view, part-cut-away, of a modified version of the
sixth embodiment using a
different form of o-ring;
Figures 7A to 7C are schematic diagrams illustrating the function and
parameters of an o-ring seal.
Figures 8 and 9 are cross-sectional views of an embodiment of a closure
described in co-pending
GB1011800.8 which, as described therein, may be modified to include a bore
feature and an o-ring in
accordance with a further embodiment of the present invention; Figure 8 shows
the parts thereof prior
to securement to a bottle neck and Figure 9 shows the parts when the closure
has been moved into
secure engagement with the bottle neck;
Figures I OA and 10B show a side view and a cross-sectional view (taken on
line E-E of Fig IOA) of an
inner component of the closure shown in Figures 8 and 9;
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Figures 11A and 11B show perspective views from above and beneath of the inner
component of
Figure 10;
Figures 12A and 12B show a side view and a view from beneath of an outer
component of the closure
shown in Figures 8 and 9; and
Figures 13A and 13B show perspective views from above and beneath of the outer
component of
Figure 12.
The embodiments shown in Figures 1 to 3 comprise cap-on-collar closures. This
type of closure is
known from prior art, such as W02006/000774 and W02007/091068 mentioned above,
so will not be
described in detail.
Figure 1 illustrates an embodiment that comprises a closure for a container
body 1 having a
substantially circular opening with an axis A and with an outwardly projecting
lip 1A around the
opening. The closure comprises a cap 2 to close the opening and a collar 3,
the collar 3 being
arranged to engage beneath the outwardly projecting lip 1A and to fit between
the container body 1 and
the cap 2 so as to secure the cap 2 to the container body 1 in the manner
described in the prior art.
The cap, collar and container are typically formed of a plastics material eg
polyethylene terphthalate
(PET) but may be formed of other materials. The container may, for instance,
be formed of glass and
the closure formed of metal.
The cap 2 has a circular upper portion which extends across the container
opening and a skirt portion
2B depending therefrom. The cap also has a bore member 4 which, in use,
extends through the
opening into the interior of the container 1 and has an o-ring sealing member
5 on the outer surface of
the bore member 4 for providing a seal with an internal surface 1 B of the
container.
The bore member 4 may be an integral part of the cap 2 or, as shown, may be a
separate component
carried by the cap 2 and is arranged to be a close fit within the interior of
the container 1 (but slightly
spaced therefrom). A recess, eg in the form of a groove 4A, is provided in the
outer surface of the bore
member around the circumference thereof for receiving an o-ring 5 formed of
resilient elastomer
material, such as rubber.
The cap 2 is rotatable relative to the collar 3, eg by means of a screw thread
therebetween. The collar
3 has radially moveable parts 3B which engage beneath the lip 1A of the
container body I and as the
cap is rotated in the tightening direction it is arranged to press the parts
inward under the lip 1A and to
hold them securely in this position, eg by means of cam features at spaced
apart locations around the
internal surface of the cap. Alternatively, the moveable parts may be biased
inwards by their own
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resilience and the cap 2 rotated to a position in which it holds the parts
securely beneath the lip 1A by
preventing them from moving or flexing radially outwards.
Preferably, as the cap 2 is rotated in the tightening direction relative to
the collar 3, the cap 2 is drawn
axially downwards towards an upper surface 1C of the lip 1A. It may engage
this upper surface 1C
when in the closed position or, as shown (in an exaggerated form) in Fig 1,
may be spaced therefrom
to reduce the risk of becoming adhered thereto over time. If it is spaced
therefrom, the spacing is
preferably relatively small, eg less than 0.5 mm so as to minimise the scope
for vertical movement of
the closure relative to the container body when in the sealed position.
In a further arrangement (not shown), the cap 2 may engage the upper surface 1
C of the lip directly or
via a secondary sealing member 6 therebetween to provide a secondary seal
between the cap 2 and
the container body 1.
As indicated above, when the closure is mounted on the container body 1, the
bore member 4 extends
into the interior of the container body 1 and the sealing member 5 is a close
fit with the internal surface
1 B of the container body. As the cap 2 is rotated relative to the collar 3 in
the tightening direction, the
bore member 4 is drawn further into the container body 1 and the o-ring
provides a seal between the
bore member 4 and the interior of the container body 1.
The inner edge of the container lip is preferably chamfered so as to provide a
lead-in surface for the o-
ring 5. The o-ring 5 then engages a portion 1B of the internal surface of the
container body which
comprises a substantially parallel sided cylindrical surface. The function of
an o-ring 5 will be
described further below in relation to Figures 7A and 7B. The cylindrical
surface 1 B extends axially for
a distance (typically several millimetres), sufficient to accommodate axial
movement (up or down) of
the bore member 4, eg due to pressure differentials between the interior and
exterior of the container.
As this surface 1B is parallel sided, such movement can be accommodated
without affecting the seal
between the closure and the container body.
It will be seen that the groove 4A within the bore member 4 is three-sided
and, together with said
internal surface 113 of the container body, defines a four-sided enclosure for
constraining the cross-
section of the o-ring 5. The side walls of the groove 4A are preferably
substantially perpendicular to
the sealing surface 1B. As will be described further below, the enclosure only
needs to be 3-sided, ie
two sided (eg L-shaped or V-shaped groove) together with the sealing surface
of the container.
A shoulder 1D is optionally provided beneath the cylindrical surface 1B of the
internal wall of the
container leading to a reduced diameter portion 1 E of the container wall.
Beneath this, the container
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wall may have any desired shape. The reduced diameter portion 1E is provided
so that automatic
handling tools, eg in a filling line, can grip the interior of the container
without damaging the cylindrical
sealing surface.
The shoulder 1 D may also provide a stop feature for limiting the movement of
the bore feature into the
container.
It will be appreciated that in arrangements in which the thread form has an
inclined portion rotation of
the cap relative to the collar is converted into axial movement of the o-ring
within the container and so
provides a significant mechanical advantage in effecting this movement. In
addition, compression of
the o-ring is primarily in the horizontal direction so does not resist axial
movement of the ring. This
greatly reduces the torque required to tighten the closure.
As indicated above, the bore member 4 may be integrally formed with the cap 2
or may be a separate
component. In the latter case, there are more options for forming the bore
member 4 from a material,
eg a metal, different to that from which the cap 2 is formed. A metal bore
member is advantageous as
it is generally impermeable to gas. If a plastics bore member is used, it is
preferably formed of a plastic
material which has been modified to reduce its gas permeability. A metal bore
member also has the
advantage that it expands as the temperature increases and thus further
compresses/deforms the o-
ring seal to enhance the seal with the container.
A separate bore member 4 may be mounted to the underside of the cap 2 in a
variety of ways, eg by
being adhered or welded thereto or by simply being clipped therein (as shown
in Fig 1). The engaging
portions of the cap and bore feature are preferably provided at localised
areas around the
circumference to reduce the frictional engagement therebetween (the benefit of
which is discussed
below). The cross-section shown in Fig I is through one of these locations.
The bore member 4 may be arranged such that the cap 2 is rotatable relative to
the bore member 4 so,
once the o-ring 5 has frictionally engaged the sealing surface 1 B, the bore
member 4 no longer rotates
relative to the container body 1 as the cap 2 is rotated further relative to
the collar 3. Instead, if the
frictional engagement between the bore member 4 and the container body 1 is
greater than that
between the bore member 4 and the cap 2, the bore member 4 merely moves
axially within the
container body 1. This means that the o-ring 5 also only has to move axially
within the container,
rather than rotating relative thereto, as the cap is tightened or loosened on
the collar 3, and so greatly
reducing the torque required to tighten or loosen the closure. In such an
arrangement, rotation of the
cap thus serves to drive the bore member (and o-ring) axially further into the
container. In other cases,
this need not be the case.
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Figure 2 shows a closure which is similar to that of Figure 1 (with
corresponding parts having reference
numbers increased by 10) except that the bore member 14 is integrally formed
with the cap 12 and the
upper portion 12A of the cap has an annular form (rather than being circular
and extending across the
container opening). In this case, it is just the bore member 14 that extends
across and closes the
container opening.
This embodiment has the advantage of simplicity as it comprises fewer
components. The recess 12C
in the closure can also provide a location for a promotional item (not shown).
Figure 3 shows a third embodiment similar to that of Figure 1 (with
corresponding parts having
reference numbers increased by 20) but in this case, the o-ring sealing member
is part of a resilient
member 25 fitted to the underside of the bore member. The resilient member 25
is moulded to fit the
underside of the bore member 24 and has a portion 25A which simulates a
toroidal o-ring. This portion
25A has an approximately circular cross-section, eg square with rounded
corners as shown in Fig 3,
and is located in a groove 24A which extends around the circumference of the
bore member 24. As
shown, this groove 24A comprises an upper face and a rear face and these
faces, together with the
cylindrical face 21 B of the container body, constrain the cross-section of
said part 25A, at least when
subject to an elevated pressure within the container 21 (NB this embodiment
would not be suitable to
for use in applications in which the pressure in the container is reduced, ie
in a vacuum pack, as the
groove does not have a lower face to constrain said part against movement into
the container).
Figures 4 and 5 show embodiments in which the closure is secured directly to
the container, eg by
means of a thread on the exterior of the container, ie without the need for a
collar. These embodiments
also employ an o-ring to provide a seal between the closure and the container
and many features
correspond to those described above (and are given similar reference numbers
but increased by 30 or
40).
Figures 4A and 4B show a fourth embodiment with a one piece closure that is
rotatably secured to the
container by means of a threaded engagement therebetween. The closure
comprises a cap 32 with a
circular portion 32A that closes the mouth of the container 31 and a skirt
portion 32B. The skirt portion
32B has thread features 32C at spaced apart positions around its circumference
which engage with
thread features 31A spaced around the exterior of the container lip 31B. As
shown in Fig 4B, the
circular portion 32A is part of a bore member 34 that extends into the
container 31 and an o-ring seal
35 is provided in a groove 34A in the exterior of the bore member 34. The o-
ring seal 35 engages a
sealing surface 31C around the inner circumference of the container 31.
Preferably, this surface 31C
is substantially cylindrical (as discussed above) but, as shown in Fig 4B, may
also be part of a surface
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that reduces in diameter towards the mouth of the container 31. With this
arrangement, an elevated
pressure within the container 31 urges the cap 32 upwards so the o-ring 35
engages a sealing surface
31 C of reduced diameter so the sealing engagement therewith is increased.
The cap 32 shown in Figure 4 may be made from metal and the thread features
32C thereof formed by
a pressing operation. As shown, the thread form is preferably a multi-start
thread form, in this case an
eight-start thread form that requires a rotation of only about 45 degrees to
fasten or release the closure.
Figure 5A shows a fifth embodiment of a closure. This is similar to the one-
piece closure of Fig 4
except that the o-ring 45 is mounted in a groove which is positioned on the
bore feature 44 such that
the sealing surface 41C that the o-ring engages is a conical surface of the
container 41. In the
example shown, this conical surface 41C lies at an angle of substantially 45
degrees with the axis A
and comprises the chamfer which extends from an upper surface of the container
lip into the interior of
the container 41. The conical surface 41C may lie at other angles to the axis
A depending upon the
application, the nature and magnitude of the internal pressures and the
hardness of the o-ring material
45.
This embodiment has the advantage that the cap 42, and particularly the groove
used to housing the o-
ring, is easier to form by a pressing operation than the arrangement shown in
Fig 4.
Also, as the sealing surface 41C has a vertical component, the o-ring moves
down this surface as the
cap 42 is tightened onto the container 41. This reduces the force required to
tighten the closure
(compared to an arrangement in which the sealing surface is perpendicular to
the axis A) as this force
moves the o-ring downwards as well as compressing the ring. As the sealing
surface is inwardly
inclined, it also serves to compress the o-ring in the horizontal direction.
Figure 5B shows a modified form of the fifth embodiment in which an o-ring
seal 45' having a cruciform
cross-section (sometimes referred to as an x-ring) is used in place of an o-
ring with a circular cross-
section. This form of o-ring has the advantage that it seals at four points
rather than two.
Figure 6A shows a sixth embodiment of a closure. This is similar to the one-
piece closure of Fig 4
except that the o-ring 35 is mounted in a groove which is positioned so that
the sealing surface that the
o-ring engages is an upper surface of the container lip. Preferably, as shown,
the cap still has a bore
member that extends into the interior of the container. In the arrangement
shown, the sealing surface
is a radially inner portion of the upper surface which abuts the internal
surface of the container. If the
interior of the container is subject to reduced pressure, eg in a vacuum
container, the o-ring is thus
pressed into the gap between the bore member and the inner rim of the
container. The seal thus
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formed may thus be regarded as being formed with the interior surface of the
container if the corner
where this meets the upper surface is included as part of the interior
surface.
Figure 6B shows a modified form of the sixth embodiment in which an o-ring
seal 55' having a
cruciform cross-section (sometimes referred to as an x-ring) is used in place
of an o-ring with a circular
cross-section. As indicated above, this form of o-ring has the advantage that
it seals at four points
rather than two.
In a further modification (not shown) of the sixth embodiment, the upper
surface of the container lip
may be shaped so that the sealing surface that the o-ring engages is not the
uppermost surface of the
lip. This sealing surface may be provided on the inner side of the lip, in
which case the bore feature
and the o-ring carried thereby extend through the opening of the container
into the interior of the
container (in a similar manner to that shown in Fig 5).
Alternatively, the sealing surface may be around the exterior of the upper
surface of the container lip,
eg in the form of a recess or chamfer about the external diameter of the lip.
As indicated above, if the
sealing surface is inclined (so as to have a vertical component), the torque
required to tighten the
closure is reduced as the forces applied to compress the o-ring are at an
angle to the axis A so are not
directly opposed to the vertical movement (along axis A) of the closure.
Thus, in these modifications, the sealing surface is an upper surface of the
container lip (or an internal
surface of the container) but not necessarily the uppermost surface of the
lip.
Preferably, as will be seen that in each of these embodiments, the side walls
of the groove housing the
o-ring are substantially perpendicular to the sealing surface of the
container.
Figures 7A to 7C illustrate the function and parameters of an o-ring seal.
Figure 7A shows a cross-
section of an o-ring 75 with a circular cross-section in an undeformed state.
The cross-section has a
diameter or width CS. Figure 7B shows the o-ring 75 located in a groove or
gland 74A having a depth
D and compressed between the rear sealing face 74B of the groove and an
external sealing face 71 B
(such as the internal surface of the container body). In this case, the o-ring
75 is subject to equal
pressures on either side thereof (left and right in Fig 7B).
An o-ring has an inner and outer diameter and a cross-sectional diameter CS
(which is the difference
between the inner and outer diameters). The outer diameter is determined by
the diameter of the
container opening (and is typically slightly greater than the diameter of the
container opening). The
cross-sectional diameter CS will depend upon the application but for
containers having a diameter in
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the range 50 - 80 mm will preferably be in the range of 2.0-3.0 mm. For
narrower mouth containers,
eg with a 28 mm diameter opening, CS will preferably be in the range 1.0-2.0
mm. It should be noted
that CS refers to the cross-section of the uncompressed o-ring when mounted in
the groove. If the ring
is stretched when located in the groove this cross-section will be smaller
than the cross-section in an
unstretched condition.
O-rings are typically formed of elastomers. Elastomers may be synthetic or
natural resilient materials
with sufficient memory to return to their original shape after a major or
minor distortion. The resilience
is what enables an o-ring to provide a seal and the parameters of the seal and
the gland are selected
to make effective use of this.
The o-ring is positioned in an enclosed space which both compresses and
locates the o-ring. The
containment ensures that the sealing function is maintained and the o-ring
retained in the desired
position. The enclosed space is formed by the walls of the groove or gland and
a sealing surface
facing the open side of the groove or gland. Figure 7B illustrates an enclosed
space having a height H
and a width W. The gland is formed in a relatively rigid material (and thus
from a different material from
the o-ring). The o-ring positioned in this space is compressed so its cross-
sectional width is reduced
from CS (shown in Fig 7A) to H.
The term 'compressed' is used herein to describe this change of shape.
However, it should be noted
that elastomers are substantially incompressible so the term 'deformation' is
technically more accurate.
The cross-sectional area of the o-ring in the 'compressed' state is thus
substantially the same as it is in
the uncompressed state.
The opposing surfaces 71 B and 74B of the gland are sealing surface and their
spacing H is less than
the o-ring cross-section CS so the o-ring is compressed as shown resulting in
sealing forces between
the o-ring and each of the surfaces 71B and 74B.
The opposing surfaces 74A and 74C are containing surfaces and the distance W
between them is
equal to or larger than the diameter CS of the o-ring. The primary function of
these surfaces is to keep
the o-ring in place.
Two of the most important parameters that affect the performance of an o-ring
seal are the
compression squeeze and the compression ratio. The compression squeeze is
defined as;
Compression squeeze = CS -H
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And the compression ratio expresses what percentage the compression squeeze is
of the
uncompressed o-ring cross-section:
Compression ratio = (compression squeeze/CS) x 100
The compression squeeze should have a minimum value of 0.1 mm and is
preferably at least 0.15mm.
The compression ratio should be in the range 5% to 35% and preferably in the
range 20% to 25%.
Another parameter of an o-ring seal is the extrusion gap G which is the height
of the spacing between
the sealing surface 71B and the outer surface of the bore member (or other
component) adjacent the
opening of the groove formed therein. The gap G is the difference between the
dimensions H and D:
soG=H-D.
The gap G should be significantly smaller than the cross-section CS of the o-
ring, eg no greater than
20% of CS and preferably no greater than 10% of GS. In most cases, the gap G
is very small, eg
0.5mm or less and preferably 0.25mm or less. However, in some cases, the gap
may be slightly larger
due to manufacturing tolerances in the formation of the container and the bore
member of the closure,
or due to specific designs, such as food applications, whether it may be
desirable for the o-ring to be
allowed to extrude partially into the gap.
If the gap G is very small, this means that the depth D of the gland is thus
preferably 65% - 95% of the
o-ring cross section CS and preferably 75% to 80% of the cross-section CS.
In cases where the gap G is larger, the depth D of the gland should still be
at least 50% and preferably
at least 60% of the cross-section CS.
Another important parameter of an o-ring seal is gland fill. This is the
percentage of the gland that is
occupied by the o-ring. The cross-section area (CSA) of a circular o-ring is
pi x (CS/2)2 and the gland
cross-sectional area (CSA) is H x W. Thus, the gland fill is given by:
(o-ring CSA/gland CSA) x 100
The gland fill should lie in the range 50% to 90% and preferably in the range
65% to 85%.
Figure 7C illustrates how the o-ring 75 moves within the groove 74A and is
deformed when subject to
pressure P from one side (the right side of Fig 7C). The o-ring 75 moves
within the groove 74A away
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from the higher pressure P and is pressed against the side face 74C at the
other side of the groove
74A. It is deformed so as to seal the gap 76 between the component housing the
groove 74A and the
face 71B. Given the nature of the o-ring (and the size of the gap),
deformation of the o-ring into this
gap is usually minimal. It will also be seen that a substantial proportion'
(greater than 50%) of the o-ring
surface is engaged with a surface (71 B, 74B, 74C) of the gland so as to
provide a seal therewith.
The parameters described above have been described in relation to a
conventional o-ring with a
circular cross-section. However, similar parameters apply to other variants of
a o-ring, eg when the o-
ring has other cross-sectional shapes and/or when the gland has other forms
(eg a 3-sided gland as
shown in Fig 3, or an L-shaped or V-shaped gland formed by two inclined side
walls) with the
appropriate dimensions used in place of those illustrated in Fig 7. It will be
appreciated that when the
o-ring is subject to a pressure differential acting to move it in one
direction, the gland only need have
one side wall, eg so the groove is L-shaped.
The function of o-ring seals, and their technical parameters, are further
described in the Dichtomatik 0-
Ring Handbook published by Dichtomatik North America (and available in 2010 on
their web site at
http://www.dichtomatik.us/Literature/0-ring-Handbook.asi? x)
It will be appreciated that the sealing action of an o-ring is very different
to that of known beverage
container seals such as a sealing gasket which is trapped between two flat
surfaces, a seal with one or
more flexible sealing fins or a wedge seal trapped in a tapering gap between a
plug member and a
container bore. The principal sealing surfaces of an o-ring are the opposing
surfaces 71 B and 74B
between which the o-ring is compressed and the engagement of the o-ring
therewith.
Figures 8 to 13 illustrate a two-part closure as described in co-pending
GB1011800.8. The inner
and/or outer component of this two-part closure may, as described in
GB1011800.8, comprise a bore
feature (not shown) which projects through the mouth of the container into the
interior thereof and the
bore feature may be provided with an o-ring seal which engages and seals with
the interior of the
container (or an upper surface thereof). These further embodiments of the two-
part closure thus form
further embodiments of the present invention. The two-part closure will be
described with reference to
Figs 8 - 13 followed by description of the arrangements (not shown in these
Figures) having a bore
feature and an o-ring seal.
The closure shown in Figures 8-13 comprises an inner component having a collar
portion for
fitting about the exterior of a container 82, in this case a bottle neck
having a container opening
defining an axis A, and which has radially moveable parts 83 spaced around its
circumference for
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engaging beneath a lip 82A of the container 82, and an outer component having
a skirt part 84A for
locating about the radially moveable parts 83 of the inner component.
The outer component 84 is designed to be located over the inner component 81
by
substantially axial movement therebetween and comprises one or more cam
surfaces 84B on its inner
surface which engage the upper ends of the radially moveable parts 83 as the
components are moved
axially so as to progressively press the parts 83 inwards into tight
frictional engagement with the
exterior of the container beneath the lip 82A of the container 82. The cam
surfaces are thus arranged
to hold and/or press an expandable/contractable portion of the inner component
into secure
engagement with the container beneath said lip,
Once the outer component 84 has been moved axially over the inner component 81
so as to
press the radially moveable parts 83 inwards, it is twisted relative to the
inner component 81 about the
axis A so as to engage securement means which releasably secure the inner and
outer components
together in this position. In the embodiment shown, the securement means
comprises substantially
upwardly facing surfaces 85A of inward projections 85 at the lower end of the
skirt part 84A of the outer
component and substantially downwardly facing surfaces 83A of the radially
moveable parts 83. The
surfaces 85A and 83A may provide a bayonet-form of engagement between the
inner and outer
components and/or a thread-like engagement therebetween. The surfaces may be
shaped or inclined
such that said relative rotation between the inner and outer components also
causes axial movement
therebetween.
In the closure shown in Figs 8 and 9, the inner component 81 also comprises a
flexible sealing
portion 86 which extends over the opening in the bottle neck, over an upper
surface of the container lip
and extends down the exterior of the bottle neck. The flexible portion 86 is
preferably integrally formed
with the radially moveable parts, e.g. by a two-shot moulding process. The
radially moveable parts are
formed of a relatively rigid material, e.g. polyethylene terephthalate (PET),
and the flexible portion of a
relatively flexible material e.g. an elastomer. The function of the flexible
sealing portion 86 will be
described further below.
The outer component 84 comprises a top part from which the skirt part depends
and which
extends across the upper surfaces of the lip 82A and across the container
opening.
The inner component 81 will be described in more detail with reference to
Figures 10A and
10B. As shown in these figures, the inner component comprises two principal
parts: a collar portion
which comprises a ring 83B with a plurality of radially moveable parts 83
upstanding from the ring 83B
and circumferentially spaced around the ring 83B and a flexible sealing
portion (described further
below). Each of the moveable parts 83 has a rounded upper end 83C for
engagement with the cam
surfaces 84B described above and for engaging the underside of the container
lip 82A. Preferably, the
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upper end 83A of the moveable parts 83 is shaped to substantially match the
concave profile of the
container on the underside of the lip 82A (as shown in Fig 9).
The outer face 83D of each of the moveable parts is substantially flat so as
to be a snug fit
within the skirt 84A of the outer component 84 when the closure is in an
unsecured position (as shown
in Fig 8). Each moveable part 83 also has a lower, substantially downwardly
facing surface 83A as
described above. This acts to retain the inner component 81 within the outer
component 84 in the
unsecured position (as shown in Figure 8) so the inner and outer components
can be easily pre-
assembled; the inner component 81 being a snap fit within the outer component
84 as they are brought
together in the axial direction, the moveable parts 83 flexing as they pass
over the inward projections
85 until they snap outwards so the lower surface 83A of the moveable part
engages the upper surface
85A of the inward projections 85.
In the position shown in Fig 8, the surfaces 83A and 85A are substantially
horizontal i.e.
perpendicular to axis A. However when the inner and outer components are moved
axially relative to
each other to the position shown in Fig 9, the moveable parts 83 are flexed
inward. The lower surface
83A of the moveable part is thus tilted inwards so as to be inclined to the
horizontal. Accordingly, the
upper surfaces 85A are preferably shaped so that when the outer component 84
is twisted to the
secured position the surface 85A is similarly inclined to the surface 83A.
In addition, in many cases, is desirable for the engagement between the
surfaces 83A and 85A,
as the outer component 84 is rotated or twisted about axis A to a second
position, for the inner and
outer component to be drawn together axially whereby the outer component 84 is
drawn down towards
the upper surface of the container lip 82A and the moveable parts 83 drawn
tightly upwards beneath
the lip 82A of the container. The surfaces 83A, 85A are thus inclined in the
circumferential direction in
the manner of a screw thread to effect a tight securement of the closure to
the container as the inner
and outer components rotated relative to each other in a tightening or closing
direction about axis A.
As the outer component is rotated relative to the inner component, the outer
component is drawn down
so as to compress the flexible sealing portion of the inner component against
the upper surface of the
container lip and the moveable members 83 are pressed upwardly into secure
engagement with the
container beneath the container lip.
In the embodiment shown, the ring 83B projects beneath the skirt 84A of the
outer component
so is visible from the exterior (as shown in Fig 8 and 9). However, in other
embodiments, the ring may
be concealed by the skirt, at least when in a secured position corresponding
to that shown in Fig 9.
An important feature of the collar portion of the inner component is that the
upper ends of the
moveable components that are free to flex radially inwards and outwards, this
movement taking place
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about a pivot at or towards the lower end of the collar (in contrast to a
collar which is located the other
way up i.e. with the moveable parts extending downwards from a ring portion).
The other principal part of the inner component is the flexible sealing
portion 86. In the
embodiment shown, this is in the form of a cap with an upper end 86A extending
across the upper end
of the container 82 and an upper surface of the lip and a skirt portion
extending down the outside of the
bottle neck to the ring 83B of the collar.
The flexible portion 86 performs several functions. First, it acts as a
sealing component in that
it is sandwiched between the outer component 84 and the upper surface of the
lip 82A of the container
so as to provide a gasket seal therebetween. In the arrangement shown, it also
extends across the
mouth of the container and so closes the container opening. In addition the
flexible portion lies
between the substantially rigid moveable parts 83 and the outer surfaces of
the bottle neck and acts as
a high friction component between these surfaces.
As indicated, the collar portion and the sealing portion are preferably
integrally formed. This
can be achieved, for example, by a two-shot moulding technique in which the
different materials are
consecutively injected so they are integrally bonded or connected to each
other. This also has the
significant advantage that the closure comprises just two parts: the inner
component and the outer
component. In known cap-on-collar closures, it is usually necessary for the
sealing component to be
provided separately or secured in some manner to the underside of the outer
component.
The outer component 84 will now be described in more detail with reference to
Figures 12A and
B and Figures 13A and B.
In the embodiment shown, the outer component is in the form of a cap with an
upper portion
84C which extends over the upper surface of the lip 82A and extends across the
opening of the
container 82 and has a skirt portion 84A depending therefrom.
The skirt portion 84A is provided with inwardly extending projections 85 at or
toward the lower
end thereof. As described above, the upper surface 85A of each projection 85
is preferably inclined
circumferentially so it acts as a screw thread and tilts radially inwards to
an increasing extent along its
circumferential length so as to match the inclination of the lower surface 83A
of the moveable part 83
that it engages. This thread path may extend over two or three adjacent parts
83.
The closure is designed so that only a relatively small twist is required to
move it from an
unsecured (Fig 8) position to a secured (Fig 9) position. In the embodiment
shown, a twist of only
approximately 60 degrees is required. Accordingly, the inward projection 85
comprises six sections
around the inner circumference of the skirt portion 84A as shown in Figures
12B and 12B.
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As indicated above, the outer component engages downwardly facing surfaces of
the radially
moveable parts so as to secure and/or tighten the inner and outer components
together in the axial
direction. This is an important feature as it enables both the inner and outer
components to be
relatively short in the axial direction so they can be formed to resemble a
conventional cap-like closure.
This also means that the threaded engagement between the inner and outer
components comprises
circumferentially spaced apart features (the surfaces 83A of the respective
parts 83). This enables the
threaded engagement therebetween to require only a relatively small rotation
or twist (rather than
several complete rotations as required by a continuous helical thread form).
Furthermore, this provides
a very compact and robust construction. The upwardly facing surfaces 85A of
the outer component
apply an upward force which is directly transmitted via surfaces 83A through
parts 83 which have a
rigid, strut-like form to the underside of the lip 82A.
This high friction engagement can also be provided in other ways. The collar
component may
be provided with a lining of high friction material (irrespective of whether
this is connected to a sealing
component that passes over the upper surface of the container lip) or the
inner surface of the collar
component could be provided with a roughened finish which is sufficient to
increase the frictional
engagement with the container to the required level. In another alternative, a
high friction sleeve, eg of
rubber, could be fitted around the container neck.
In addition, the flexible sealing component extends over the upper surface of
the lip 82A and so
provides a sealing member between the closure and the container. The provision
of a single
component that acts both as a collar for fitting around the exterior of the
container and as a sealing
component between the closure and the container, is a significant feature of
this closure.
As described, when the outer component is moved with respect to the inner
component so as
to press the moveable parts 83 inwards, this movement is primarily axial. In
other embodiments, this
axial movement may be provided by means of a small twisting movement although
it is the axial
component that moves the cams downwards so as to press the parts 83 inwards.
The twisting
movement is preferably less than 360 degrees and more preferably less than 90
degrees or less than
60 degrees. This is in contrast to arrangements in which a small axial
movement is a consequence of
several complete rotations of the outer component relative to the inner
component, eg as provided by a
continuous helical threadpath.
In further embodiments (not shown) of the closure shown in Figs 8-13, in
particular closures for
widemouth containers, the inner and/or outer component may comprise a bore
feature which projects
through the mouth of the container into the interior thereof. The bore feature
preferably comprise a
relatively rigid component, eg formed of PET or metal, and may be integrally
formed with the outer
component or secured thereto. In a particularly advantageous arrangement, the
outer component is
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able to rotate about the axis A relative to the bore feature. The outer
component can thus be rotated,
eg to fasten or release the closure whilst the bore feature moves axially
within the bore without rotating
therein.
The bore feature may also be provided with an o-ring seal which engages and
seals with the
interior of the container (or an upper surface of the container lip). The bore
feature and o-ring may be
as described above. The o-ring may be in the form of a toroid of an elastomer
located in a groove or
gland on the outer surface of a bore feature. The o-ring may also be part of a
resilient member
moulded to fit the underside of the bore feature. The resilient sealing
portion described above in
relation to Figs 8 - 13 may include such a member. Thus, if the outer member
shown in Figure 9
projects into the bore of the container (rather than being flat) and the
resilient sealing portion follows
the underside of this feature (again, rather than being flat) the resilient
component may be formed with
a portion which simulates the function of an o-ring to provide a seal with the
interior of the container.
In such embodiments employing an o-ring seal, the seal provided by the
sandwiching of the
flexible part of the inner component between the outer component and the upper
surface of the
container lip may no longer be required. In this case, the outer component
need not engage and/or
compress the flexible sealing component against the upper surface of the lip.
These further embodiments thus provide a closure for a container having a
circular opening defining an
axis and a lip around said opening, the closure comprising: an inner component
having a collar portion
for locating about the exterior of the container beneath the lip of the
container and a sealing portion
which, in use, extends from said collar portion over an upper surface of said
lip; and an outer
component for fitting over the inner component and interacting therewith for
releasably securing the
collar portion thereof under said lip, the closure having an o-ring seal for
providing a seal between the
closure and an upper or interior surface of the container.
The o-ring may be provided on a bore feature which, in use, projects through
the opening into the
interior of the container, the bore feature being part of the inner and/or the
outer component.
In a preferred arrangement, the collar portion may be relatively rigid and the
sealing portion relatively
flexible and the collar portion and the sealing portion may be integrally
formed with each other, eg by a
two-stage moulding process.
Preferably, the outer component has a skirt part for locating about the collar
portion of the inner
component, the collar portion comprising a plurality of spaced apart radially
moveable parts around its
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circumference pivotally joined at their lower ends by a structure extending
around the entire
circumference of the collar portion.
The provision of an o-ring seal between the bore member and the internal
surface of the container
body has a number of advantages:
= It has relatively stable geometry when subject to pressure-induced lifting
of the closure
(compared to that of a seal provided on the upper surface of the container
lip)
= The degree of o-ring compression that is required is reduced (compared to a
seal on the upper
surface of the container lip) and the direction of the compression does not
increase the frictional
engagement of the thread so the torque required to compress the seal is
reduced
= Increased pressure within the container presses the o-ring seal more tightly
into the gap
between the closure and the cap so improving seal quality at higher pressures
= Positive internal pressure also assists in releasing the seal by applying an
upward force against
the underside of the closure so helping overcome the frictional engagement
between the o-ring
and the container wall.
= The sealing surface are spaced from the container lip and thus less
susceptible to damage, eg
during handling of the container.
= The bore member allows the head space within the container to be
significantly reduced.
= The o-ring (in an appropriately shaped gland) is able to provide a seal
irrespective of whether
the internal pressure is higher or lower than the external pressure so can be
used both for
carbonated beverages and for vacuum packs. Other forms of seal tend to be
designed cater
for one or the other application.
Using a bore feature which is formed separately from the cap also provides the
additional advantages:
= Further reducing the torque required as the bore feature (and hence the seal
carried thereby)
does not have to rotate with the cap
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= Allows the bore feature to be formed of a different material, eg a metal to
reduce its gas
permeability to almost zero
= Makes it easier to separate the different components of the closure for ease
of recycling
As described, the o-ring is preferably a separate component, typically having
a circular cross-section
(although other cross-sectional. shapes are possible) located within a recess
extending around the
circumference of a bore member. However, in other embodiments, the seal member
may have other
forms which simulate the sealing action of an o-ring and may be integrally
formed with a bore member,
for example by using an over-moulded elastomer to form a virtual o-ring
element.
An o-ring typically needs to be compressed by 10-30% to provide an effective
seal, whereas a
compression gasket can require a much higher degree of compression.
If the o-ring is located within a groove 4A as shown in Figure 8, it is
preferably able to move axially
within this groove in response to increases or decreases in pressure within
the container body. This
enables the o-ring to respond to the increase in pressure and adopt a
shape/position which is better
able to withstand the pressure.
In each of the embodiments described, an o-ring is used to provide a seal
between a closure and a
container. The o-ring preferably seals against an internal surface of the
container but, in some
embodiments, may seal against an upper surface thereof (particular at the
point where this meets the
internal surface). The sealing surface extends around either the internal or
the upper surface of the
container.
The o-ring is located in a groove which has at least one side wall, the
arrangement being such that,
when the closure is installed on the container, when subject to a pressure
differential, the o-ring is
moved and/or deformed so as to seal a gap between side wall and the container,
the width of said gap
being smaller than the cross-sectional width of the o-ring.
The closure may take a wide variety of forms including a cap-on-collar and
other two-part
arrangements such as those described as well as a one piece closure.
Preferably, the closure is
arranged to be installed and/or released from the container by rotation around
the axis passing though
the container opening.
An additional advantage of having a bore member which extends into the
interior of the container is
that this occupies space at the upper end of the container that in a beverage
container would usually
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otherwise be occupied by a gas or provide a 'headspace', above the beverage.
Reduction of the
volume of this headspace, if it is occupied by air, reduces the amount of
oxygen trapped within the
container so increasing the shelf-life of the beverage or, if it is filled
with an inert gas, reduces the
quantity of inert gas required.
In some cases, the cap or outer component may comprise an annular component
that has an upper
portion that overlies the upper surface of the container lip so that it can
provide a downward force on
the lip, or on a seal member located between the lip and the cap, and a skirt
portion which interacts
with a collar or inner component (as described above) whereby the cap is
secured to the container
body.
The thread form used between the cap and the collar or inner and outer
components (for a two-part
closure) or between the cap and the container (for a one-piece closure) is
preferably a multi-start
thread form such that less than 360 degrees of rotation is required to install
or remove the closure.
With an eight-start threadform, the closure needs to be rotated by only about
45 degrees to install or
release the closure.
Intermittent threadforms and bayonet style threadforms such as those described
in W02006/000774
and W02007/091068 may be used. In the case of a bayonet theadform,.the cap or
outer component
need not be moved axially as the outer component is rotatably secured to the
inner component. Similar
threadforms may also be used with a one-piece closure (with the thread form
provided on the container
neck rather than on a collar).
For the avoidance of doubt, the verb "comprise" as used herein has its normal
dictionary meaning, ie to
denote non-exclusive inclusion. The use of the word "comprise" (or any of its
derivatives) does not
therefore exclude the possibility of further features being included.
All of the features disclosed in this specification (including the
accompanying claims, and drawings)
may be combined in any combination (other than combinations where at least
some of the features are
mutually exclusive).
Each feature disclosed in this specification (including the accompanying
claims and drawings) may be
replaced by alternative features serving the same, equivalent or similar
purpose, unless expressly
stated otherwise. Thus, unless expressly stated otherwise, each feature
disclosed is just an example of
a generic series of equivalent or similar features.
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The invention is also not restricted to the details of the embodiments
described herein or to the specific
combinations of features of the embodiments described. In particular, the
invention includes
arrangements as described in the claims with the addition of any one or more
features described or
claimed herein including generalisations of which those feature(s) are
illustrative.
