Note: Descriptions are shown in the official language in which they were submitted.
094/1~871 ~ 15 ~ 31 ~ PCT/GB94/00022
FOAM PRODUCTION
This invention relates to the production of foam and is
particularly but not exclusively concerned with the production
of a head of beer dispensed from bottles, cans and the like.
Whilst many systems exist for ensuring a good, stable, tight
head on draught beer which is dispensed from casks and other
bulk containers, it has long been recognised that there are
problems if seeking to achieve the same effect on beer
dispensed from cans and bottles. Such containers are vented
to atmosphere when opened by e.g. removing a tab or cap. Any
head tends to come from the natural effervescence of the beer
as dissolved carbon dioxide comes out of solution, and from
excitation of the beer as it is poured into a glass. To a
certain extent the head formation can be improved by using a
combination of nitrogen and carbon dioxide, but simply doing
this does not produce a head as good as that on draught beers.
There is a particular problem in the case of canned beers
intended to provide similar qualities to traditional draught
beers, where there is a significantly lower CO2 content than in
other canned beers.
In GB-A-1,266,351 there is disclosed the use of a secondary
chamber in a can or bottle. This contains gas at above
atmospheric pressure. In one arrangement the chamber is in
permanent communication with the main body of beer. When the
bottle or can is opened, the gas is ejected from the secondary
chamber as a result of the excess pressure over atmospheric
pressure and this initiates bubble formation.
In GB-A-2,183,S92 there is disclosed a system in which beer is
said to enter a secondary chamber containing gas, and it is
stated that ejection of this beer initiates bubble formation.
In GB-A-1,266,351 and GB-A-1,331,425 there are also disclosed
systems in which a secondary chamber is provided with a valve
wo 94~15871 2~ PCT/GB94/00022 ~
which will open when the container is vented to atmosphere,
gas under pressure being injected into the primary chamber.
In WO-A-91/07326 there is disclosed a secondary chamber which
is charged with nitrogen under pressure, prior to insertion in
the can. A valve is provided which initially stays closed
against the pressure differential. After insertion in the
can, and sealing of the can, the valve properties are altered
and it will open when subsequently exposed to the pressure
differential again when the can is opened.
.
A commercially available can of beer marketed in the United
Kingdom contains an insert which is said to be in accordance
with GB-A-2,183,592. Another commercially available can of
beer marketed in the United Kingdom contains an insert which
is said to be in accordance with WO-A-91/07326. Both of these
inserts are of relatively complex construction. In the case
of the first mentioned insert it is believed that a
multi-stage flushing process with nitrogen is necessary, after
insertion into the can, to ensure the absence of oxygen which
might taint the beer. In the case of the second mentioned
insert, it is a two part moulding which has been filled with
nitrogen or another suitable gas before insertion.
Known secondary chamber designs in commercial use are of
relatively complex construction and present difficulties in
terms of handling and filling with gas.
An object of an invention disclosed herein is to provide an
insert which is more readily able to be filled with gas such
as carbon dioxide, nitrogen, a mixture of the two, or another
suitable "inert" gas.
Thus, according to an invention disclosed herein there is
provided a hollow insert for positioning in a container of
beverage which is to be sealed under pressure, the insert
being adapted to provide a flow of gas and/or beverage into
21533~
94/15871 PCTIGB94/00022
the beverage in the containercwhen the container is opened, so
as to promote the formation of foam, wherein the insert
comprises first and second portions which are joined together
and movable relative to each other from a first position in
which there is access to the interior of the insert through at
least one relatively large opening provided in one of the~
portions, to a second position in which the insert is
substantially sealed.
By "substantially sealed" is meant that the insert is in its
normal operative condition, in which there may be a permanent
but small aperture or e.g a valve, as in the prior art
devices.
Thus, in use the portions are initially in the first position
and it is a simple matter to fill the insert with gas. This
may be done by means of an injection tube or the like passing
through the large opening, or it may be done by evacuating and
flushing the insert and the bevérage container with gas as in
the prior art system. In the latter case, the large opening
considerably facilitates the flushing of the insert. When the
insert is full with the desired gas, the two portions are
moved together so as to seal the insert. The filling and
sealing operations may be performed inside the beverage
container, for example as part of an insertion operation, or
may be carried out prior to positioning the insert in the
container.
In WO-A-9l/07326 there are disclosed various types of insert
in two parts. In use, one of these is completely open and is
filled with gas before the other is attached to it as a
sealing cap, and neither part has an opening through which gas
can be passed into the insert after the parts are joined
together.
In a preferred embodiment of this present invention, one of
the portions has a relatively large aperture which is
.
WO94/15871 2~33 PCT/GB94/00022(~
positioned opposite a spigot ~n the other portion. When the
two portions are pushed together, the spigot enters and seals
the aperture. The spigot itself may be provided with an axial
opening, so that there is the opt-ion of filling the insert
from either direction. Such an arrangement of two openings
may be possible in other cases also. When two openings are
provided, when the insert is sealed there will be a passage
passing from one side to the other; this may be advantageous
as it will permit a flow of beverage during filling so as to
assist in filling the beverage container underneath the
insert.
When the insert is filled with gas by means of a tube, the
arrangement should preferably be such that the tube is in
sealing engagement with the opening through which it passes.
In the case of there being two openings, the tube preferably
seals the other opening also. In this manner, it is possible
to use the tube firstly to evacuate air from within the
insert, and then to inject the inert gas such as nitrogen. A
single such cycle will be sufficient. If there is no such
sealing, simply flushing the insert through with gas may
though be sufficient. By evacuating air from the insert, the
insert can be held onto the tube which assists in handling of
the insert.
According to a further invention disclosed herein there is
provided a method of inserting a significantly air free, gas
filled hollow enclosure into a container for beverage, where
gas and/or liquid is subsequently to be ejected from the
enclosure into the beverage. In general, the enclosure would
be full of an "inert" gas such as nitrogen. The method of
this further invention comprises the steps of passing a tube
into the enclosure in sealing engagement with an opening;
applying a reduction in pressure to the enclosure through the
tube, whereby to obtain significant removal of air from the
enclosure and to attach the enclosure to the tube; positioning
the enclosure in the container whilst attached to the tube;
094/15871 ~1 5 3 ~ ~ ~ PCT/GB94100022
ceasing application of the re~uction in pressure; passing a
gas into the enclosure by means of the tube; and withdrawing
the tube from the enclosure.
A gas injection tube arrangement may also be used to urge the
two insert portions together after filling with gas.
,~ .
Means are preferably provided to keep the two portions
together in the second position after filling and being urged
together. This could be by way of adhesive, heat bonding and
the like. Preferably, however the two portions snap or press
fit together. One of the portions may deform from e.g a
convex dished state in the first position to a concave dished
state in the second position to help keep the portions engaged
together.
Where the insert is to have a small permanent opening through
which gas and/or beverage is to be ejected in use, this may be
provided in one of the portions in advance. Preferably,
however, the opening is defined when the two portions are
urged together and is a small gap between them. Thus in the
case of a spigot extending into an aperture, there could be a
narrow space around the spigot. Alternatively, the spigot
could be sealed into the aperture around most of its
circumference, save one or more points where an opening is to
be provided. At such point(s) one of the portions could be
provided with a groove or the like.
In one preferred embodiment one of the portions has a
centrally disposed axially extending spigot, received in an
aperture in the other member. The aperture itself is in the
form of a tube. One of the spigot and tube has a
longitudinally extending groove which defines, with the wall
of the other, a longitudinally extending orifice through which
the gas and/or beverage will be ejected. The groove may for
example be in the form of a "V" notch with a 90 angle,
approximately 0.3 mm deep. The orifice may open out in the
WO94/15871 ~33~ PCTIGB94/00022
direction of gas/beverage flow. This can be achieved by
tapering the cross section of the tube or spigot in the
longitudinal direction, e.g making it of frustoconical form.
The groove may be formed by means of a suitable precision tool
before the portions are assembled together.
In a preferred embodiment, the insert comprises a first
portion in the form of a chamber having a first closed end, a
central hollow tube extending from the first end to the other
end and having an axial opening at both ends, and a second
portion in the form of a flexible cap sealed around its
periphery to the first portion at said other end, the second
portion having a central spigot axially aligned with the tube,
and the second portion being deformable so that the spigot
moves axially from a first position in which it is not in
sealing engagement with the tube, to a second position in
which the spigot is in sealing engagement within the tube.
In the preferred embodiment the first and second portions are
initially joined together, and supplied in such a manner but
with the spigot in the first position. The join between the
portions may be a press fit although adhesives, welding and so
forth could be used.
The general construction of such an arrangement has advantages
even if the two portions are not initially joined together,
and the cap is simply pressed into place, simultaneously
forming a circumferential seal and the seal between the spigot
and tube. A particularly advantageous arrangement is when
such a system is used in the context of an insert having a
permanent opening.
According to a further invention disclosed herein, there is
provided a hollow insert for positioning in a container of
beverage which is to be sealed under pressure, the insert
being adapted to provide a flow of gas and/or beverage into
the beverage in the container when the container is opened, so
~ 094/15871 2 1~ 3 ~ 1 B PCT/GB94/00022
as to promote the formation Gf foam, wherein the insert
comprises a first portion in the form of a chamber having a
first closed end, a central hollow tube extending from the
first end to the other end and having an axial opening at both
ends, and a second portion in the form of a cap sealed around
its periphery to the first portion at said other end, the
second portion having a central spigot extending axially into
the tube and forming a seal therewith, and there being defined
between the spigot and the tube at least one axially extending
orifice through which there will be the flow of gas and/or
beverage into the beverage in the container when the container
is opened.
Preferably the spigot is hollow whereby there is provided a
passage through the insert.
Preferably the tube is tapered, with increasing cross section
in the direction away from the spigot. The tube may have a
first relatively short portion of a first diameter (or in the
case of a taper, range of diameters) which receives the
spigot, and a second longer portion of a second, greater
diameter (or in the case of a taper, range of diameters).
In use, if the insert is positioned towards the bottom of a
beverage container such as a can, the first portion will be
uppermost with the tube pointing up the container.
The insert may be formed of any suitable plastics material
such as food grade HDPP (High Density Polypropylene), and the
two portions may be moulded by any suitable technique such as
injection moulding. They may be sealed around the periphery
by means of a press fit, adhesive, thermal or ultrasonic
welding, or by any other suitable technique. The material of
the insert will generally have a degree of resistance.
The insert may be located inside a container by any suitable
means. Preferably it is provided with a pair of laterally
W094/15871 ~ ~ PCT/GB94/OOOZ2(~
extending resilient wings of plastics material which will
engage the interior wall of the container. The wings will
have a natural extent exceeding the diameter of the container.
The insert could be passed into the container by means of a
tapering guide tube which will compress the wings inwardly,
the wings subsequently pressing out to grip the container
wall. The wings may be formed integrally with the first
portion. The wings preferably have apertures therein to
assist when filling the container, to permit free flow of
beverage and prevent gas pockets forming.
In one embodiment the wings are relatively rigidly attached to
the main chamber part of the insert, whilst providing
sufficient resilience to permit the insert to be forced into a
can or the like. In the preferred embodiment, however, the
wings are resiliently hingedly attached towards the bottom of
the insert. Preferably, the hinges permit the wings to fold
up from a lateral position to a vertical position, against the
main body of the insert. This reduces to a minimum the cross
section of the insert and facilitates insertion. In this
embodiment, the extremities of the wings are preferably
provided with lugs positioned below the plane of the hinge.
By the arrangement, once the insert is positioned in the can,
removal will be resisted by these lugs engaging the can wall.
It will be appreciated that with the preferred embodiment,
whilst the orifice communicating the interior of the insert
with the beverage may be towards the bottom end of the insert,
it can nevertheless direct the gas and/or beverage upwardly in
an axial direction. This may be advantageous.
Accordingly, in accordance with a further invention disclosed
herein there is provided a hollow insert for positioning in a
container of beverage which is to be sealed under pressure,
the insert being adapted to provide a flow of gas and/or
beverage into the beverage in the container when the container
is opened, so as to promote the formation of foam, wherein
.
215~3~ ~
094/15871 PCT/G~94100022
there is provided a relatively wide passage extending
downwardly through the insert, which at its upper end is open
to communicate with the main body of beverage within the
container and at its lower end communicates with the interior
of the insert through at least one relatively fine orifice
through which there will be the flow of gas and/or beverage
into the beverage in the container when the container is
opened.
Preferably the passage is also open adjacent its other end,
and preferably the wall of the passage tapers inwardly from
the upper to the lower end. Preferably the fine orifice
extends parallel to the axis of the passage, for example from
a step towards the lower end of the passage. The orifice
could be in the form of a fine annular gap.
In the most preferred embodiments, filling of the inserts is
carried out by a tube by an effective and simple manner.
Thus, according to a still further invention disclosed herein
there is provided a method of filling with gas a hollow insert
for positioning in a container of beverage which is to be
sealed under pressure, the insert being adapted to provide a
flow of gas and/or beverage into the beverage in the container
when the container is opened, so as to promote the formation
of foam, wherein the insert comprises first and second
portions which are joined together and movable relative to
each other from a first position in which there is access to
the interior of the insert through at least one relatively
large opening provided in one of the portions, to a second
position in which the insert is substantially sealed, the
filling method comprising the steps of positioning a filling
tube through the relatively large opening whilst the portions
are in the first position, injecti~g gas into the insert
through the filling tube, moving the portions into the second
position, and withdrawing the filling tube from the insert.
~33~6
WO94/1~871 PCT/GB94/00022
Preferably, the method comprises the further step of
evacuating the insert through the filling tube, prior to
injecting gas.
Preferably the filling tube has laterally extending orifices
to inject the gas into the insert. As noted earlier, it may
seal the opening or, if there are two openings, both of them.
To urge the two portions together, any suitable means may be
employed. In one arrangement, the insert is urged downwardly
against the base of the container, this serving to push the
portions together. In the case of an aluminium or other thin
walled can, this may require supporting the base of the can on
the outside.
Even where there is to be a permanent orifice, it will be
practicable to fill the insert in advance of covering with
beverage, so that insertion, filling and closing of the insert
may be carried out at an earlier stage in the process either
inside the container or separately. Little air will penetrate
the insert in the time intervals likely to be encountered in
practice.
In the case of using a permanent orifice the position of the
orifice and the volume and arrangement of the insert have to
be considered carefully. In such an arrangement the orifice
provides a permanent communication between the secondary
chamber and the main body of beverage, and beverage will enter
the insert. The arrangement could be as described as in
GB-A-2,183,592, in which it is alleged that ejection of
beverage initiates foam formation. However, it has been found
that it is advantageous to position the orifice to have an
alternative effect.
It has now been ascertained that froth initiation by ejection
of gas such as nitrogen, carbon dioxide or a mixture of the
two, can be achieved in a simple manner which does not require
094/1~871 ~ 3 ~ 6 PCT/GB94/00022
complex manufacturing conditions. The term 'linert gas" used
herein refers to such gases and any other suitable gases which
will not taint beer. The insert is therefore preferably
provided with the orifice at a position such that there will
be, below the level of the orifice, a substantial volume in
which beer will be trapped.
In this preferred method, the insert initially contains gas at
atmospheric pressure and is in permanent communication with
the body of the container. The container is filled with
beverage which will usually be at a temperature lower than a
normal dispensing temperature and typically close to O-C.
The beverage is supersaturated with gas, containing carbon
dioxide and nitrogen; the nitrogen may be obtained at least in
part by dosing the can with liquid nitrogen. Additionally or
alternatively the beverage may be pre-nitrogenated. The
container is sealed and the pressure inside rises as a result
of evolution of the gas from the beverage and the liquid
nitrogen dosing if applicable. The beverage enters the insert
through the orifice to compress the gas therein. The orifice
is spaced from the bottom of the insert by a distance
sufficient to define below the orifice a substantial
reservoir .
The orifice is portioned such that the liquid beverage
entering the insert will fill the reservoir and cover the
opening. Gas will be trapped and compressed above the
beverage in the insert.
In practice, pressure in the container at the time of opening
will also have risen due to temperature effects. Whilst
filling and sealing may have been carried out at about OC,
consumption may take place at about 7-lOC, say 8C, or even
at room temperature at about 20OC.
When the container is vented to atmosphere, the gas in the
insert first expels liquid beverage through the orifice, until
.
11
WO94/15871 ~ PCT/GB94/00022
the level drops to uncover the orifice. At this point the gas
is still under significant pressure because the free volume of
the insert is reduced by the volume of liquid trapped in the
reservoir below the level of the orifice. Thus, the original
mass of gas in the insert occupies a smaller volume. The gas
is ejected through the orifice until its pressure drops to
atmospheric. In a simple case, the volume ejected (at
atmospheric pressure) wil be approximately equal to the volume
of trapped beverage in the reservoir.
In such an arrangement the liquid beverage itself does not
initiate significant bubble formation to an extent sufficient
to generate a head. The jet of gas which is ejected
subsequently causes the bubble formation. The arrangement may
be such that a relatively small quantity of liquid is above
the orifice before the container is opened, so that it is
disposed of rapidly before the gas is ejected. With such an
arrangement, there may be an additional initial effect in
which some gas forces its way through the layer of liquid
above the orifice, as soon as the container is opened. This
causes foam to be ejected, and gives rise to bubble initiation
in the beverage in the container even before the main quantity
of gas is ejected through the orifice.
Furthermore, as the gas is ejected through the orifice, it
passes over the trapped liquid in the reservoir. This may
lead to some foam being ejected through the orifice together
with the main body of gas.
Experiments have shown that ejection of gas in this manner,
preferably with the foam, rather than ejection of liquid,
gives significant bubble formation and leads to a good head on
beverages such as beer and stout which are dispensed from cans
or bottles.
Thus, in the preferred embodiments a simple orifice is
provided in the tubular insert at a position between the top
094/15871 ~ 5 3 316 PCT/GB94/00022
and bottom extremities. The orifice is preferably on the side
which will point inwardly to the centre of the container. The
orifice may be provided by drilling, laser boring, punching or
as part of the initial forming process.
The orifice is preferably positioned such that between 25~ and
75% of the volume of the chamber is below the level of the
orifice. A preferred range is 30% to 40%, in particular
around 50%.
A preferred total internal volume of the secondary chamber,
for conventional beer can sizes in the range of 275 ml to 500
ml, is in the range of lO ml to 20 ml. A preferred size is
about 15 ml to 16 ml, which is appropriate for a number of
sizes including 440 ml and 500 ml containers.
After the container has been filled and sealed it may then be
pasteurised. Preferably, pasteurisation is carried out with
the can inverted, as is common practice in the brewing
industry. Preferably the quantity of beverage in the
container and the location of the orifice in the insert are
arranged such that during inverted pasteurisation the interior
of the insert is in communicatin with the head-space via the
orifice. It is believed that this may improve performance of
the insert by increasing the volume of gas trapped therein.
As noted above, there may be initial effects in which gas is
punched through the beverage in the insert. These may be
undesirable and it may be desired to have a more gradual
effect. This may particularly be the case where it is wished
to avoid adverse temperature dependent effects.
By making the walls of the insert from sufficiently flexible
material, when the container is first opened and the pressure
drops to atmospheric, any initial potentially "explosive"
effect within the insert can be avoided. Instead of the
contents of the insert being blown suddenly out of the insert,
WO94/15871 ~53 PCT/GB94/00022
the walls of the insert expand outwardly momentarily under the
action of the pressure difference. This increases the
internal volume of the insert momentarily, and thereby absorbs
some of the initial effect.
According to another invention disclosed herein there is
provided a method of promoting the formation of foam upon
opening a container of beverage containing gas in solution and
sealed under pressure, wherein there is provided within the
container an insert adapted to provide a flow of gas and/or
beverage into the beverage in the container when the container
is opened, as a result of a pressure difference between gas in
the insert and atmospheric pressure, and wherein a major part
of the volume of the insert is bounded by a wall which whilst
resistant to collapse is sufficiently flexible such that upon
opening the container a sudden initial pressure difference is
absorbed in part by transient flexing of the wall to increase
the volume of the insert, so as to prevent excessive sudden
expulsion of the contents of the insert, whereafter there is
controlled ejection of the gas and/or beverage to promote foam
formation.
Such an arrangement can considerably reduce unwanted
temperature effects. Existing systems tend to work reliably
only at low temperatures and it is recommended that the
beverage be chilled. At higher temperatures, the pressure in
the container and insert is higher, and there can be an
initial very explosive effect when the container is opened, as
the contents of the insert are expelled suddenly. By the
means described above, such initial effects are absorbed and
in suitable cases it is feasible to open the container at
normal ambient temperatures. Furthermore, in the preferred
system there is in any event substantial ejection of beverage
before the foam promoting gas (or gas and beverage) and this
also dissipates energy and helps to reduce the problems when
opening the container at higher temperatures.
14
~'094/15871 215 3 316 PCT/GB94/00022
Providing a flexible wall maycalso make it possible to vary
the volume of the insert by a manual operation to as to effect
a "pumping" action. This may be achieved by for example
squeezing the sides of a thin walled aluminium can one or more
times, so that members such as the supporting wings described
earlier act on the wall of the insert. Such an action may
permit additional pumping of gas and/or beverage into the main
body of beverage to facilitate foam formation on a second
occasion. Thus, when pouring out a second glass of beer for
example a better head may be obtained than with existing
arrangements.
As noted earlier, the insert may be provided with a valve type
of arrangement which opens when the container is opened,
rather than a permanently open orifice. This can be achieved
in the region of the join between the spigot and tube in the
preferred embodiment, so that a valve seat is formed. This
valve could operate in a known manner. However a preferable
arrangement would be one in which there is manual control over
the valve. Thus, whether the insert is used or not could then
be at the choice of the consumer. There would also be the
possibility of controlling the flow from the insert. Such an
arrangement could for example be provided by means of the
wings referred to above such that upon squeezing the sides of
a can there is distortion of the insert and opening of the
valve.
Thus according to another invention disclosed herein there is
provided a container of beverage sealed under pressure, the
container having a flexible wall and having therein a hollow
insert adapted to provide a flow of gas and/or beverage into
the beverage in the container when the container is opened, so
as to promote the formation of foam, there being a valve to
control the flow of gas and/or beverage from the insert, and
there further being movable portions of the insert which
engage the flexible wall of the container and whose movement
control the opening and/or closing of the valve, whereby a
~5~3~
WO94/1~871 PCT/GB94/00022
user can control the valve by.pressure on the flexible wall of
the container.
Some arrangements embodying a number of the above features
will now be described by way of example and with reference to
the accompanying drawings in which:-
Fig. 1 is an exploded perspective view of the insert.
Fig. la is a view of part of the insert to show a groovewhich defines an orifice.
Fig. 2 is a vertical section of the insert in one
configuration.
Fig. 3 is a vertical section of the insert in another
configuration.
Fig. 4 is a vertical section of the insert being filled
with gas.
Figs. 5a-5d are vertical sections of a can of beverage
containing the insert showing the flow of fluid into and out
of the insert.
Fig. 6 is a view showing an evacuation and gas filling
tube engaged in the insert.
Fig. 7 is a plan view of part of a second embodiment of
insert.
Fig. 8 is a section through this part.
Fig. 9 is a side view of this part.
Fig. lO is a section through a second part of this
embodiment of insert.
Fig. 11 is a plan view of this second part.
Fig. ll(a) is a detailed view of a portion of Fig. 11.
Fig. 12 is a section through this embodiment of insert,
with the parts in a first position.
Fig. 13 is a section with the parts in a second position.
Fig. 14 is a sectional view of insertion and gas filling
apparatus.
Fig. 15 is an enlarged sectional view through this
apparatus.
16
~ 094/15871 21~ 3 3 ~ ~ PCTtG~94/00022
Referring to Fig. 1, the insert 1 is made from two pieces of
injection moulded, resilient plastics material, such as food
grade high density polypropylene. The main, upper part 2 of
the insert has a chamber 3 and two wings 4.
.
The chamber is defined by a generally cuboid-shaped portion 5
in the centre of which is a hollow tube 6 of tapering circular
cross-section.
Below the cuboid portion 5 there is a downwardly extending
skirt 7 joined to the cuboid portion by a horizontal flange
7a. At the lowermost part of the flange there is an internal
groove 8 which forms part of a snap-fit mechanism which is
used to connect the two parts of the insert together in a
sealing fashion around their circumferences.
The base of the tube 6 is generally level with the flange 7a
and has two concentric, circular lips thereon. The outer lip
9 is provided with an annular rib 9a projecting from its outer
wall. The inner lip lO defines a hole in the base of the tube
6 and tapers outwardly in the upwards direction. The lips co-
operate with parts of the lower piece in a manner discussed
below.
The purpose of the wings 4 is to locate the insert within a
beverage container such as a beer can. Their outer faces 11
are therefore curved as shown in Fig. 1 and have a similar
radius of curvature to that of the container in which the
insert is to be used. The wings 4 extend from the cuboid
portion 5 on opposite sides thereof. Because of the resilient
nature of the material used, the insert 1 will wedge inside a
container with the outer faces of the wings pressing against
the inner walls of the container.
The second moulded piece 12 forms the base of the insert. It
is generally disc-shaped and has an outer rim 12 with a lip
12a which provides a sealing snap-fit into the groove 8 of the
WO94115871 2 ~ 3 3 ~ PCTIGB94/00022
main piece 2 (as illustrated~in the remaining figures). This
piece has two stable configurations. These are assisted by
incorporating an annular groove 13 into the disc which assists
the disc to snap between positions. In the first position (as
shown in Fig. 1) the disc is concave downwards. This an open
configuration in which the insert is assembled. In the second
configuration (as shown in Figs. 3 and 5a-d), the disc is
concave upwards to a closed configuration. These
configurations are discussed in more detail below in relation
to figures 2 and 3.
In the centre of the disc there is a hollow spigot 14, open at
both ends, having an external diameter approximately equal to
the interior diameter of the hole through the base of the lip
10 in the centre of the main piece, so that the spigot can
form a sealing press fit within the tube. Around the aperture
at the lower end of the spigot are projections 15 on the outer
face of the disc which may be used to space the insert
slightly from the base of a container in which it is placed.
Disposed around the spigot on the inside face of the disc
there are four further projections 17. When the insert is
assembled and the disc is in the closed configuration, grooves
17a on these projections form a snap fit with the rib 9a, thus
holding the centres of the two pieces together.
The spigot 14 is provided with a longitudinally extending "V"
shaped groove 14a shown more clearly in Fig. la. This is
about 0.3mm deep and has a right angle base. It is this that
will provide the orifice for gas and beverage discharge in the
manner described below.
An assembled insert with the disc in the open configuration is
illustrated in Fig. 2. From this figure it may be seen that
the chamber is closed except for the openings provided by the
apertures in the spigot and tube.
~ 094/15871 215 3 31~ PCT/GB94/00022
Once the insert has been asse~bled it may be filled with an
"inert" gas such as nitrogen, carbon dioxide or a mixture of
the two. This process is illustrated in Fig. 4. A tube 18
connected to a supply of gas is inserted through the spigot
from the bottom. The tube has a closed upper end and
laterally directed holes 19 near its upper end to allow the
gas to flow out sideways into the i,nsert. The insert is
flushed with inert gas in this manner in order to remove
oxygen which would taint a beverage such as beer.
After flushing the insert, the second part of the insert is
pushed upwards into its second configuration substantially to
close the chamber, as shown in Fig. 3. In this configuration
the spigot on the second piece fits closely within the lip 10
on the first piece, to form a seal around most of the
circumference. The exception is that the groove 14a forms a
longitudinal, upwardly directed fissure communicating the
chamber with the outside. Since the lip 10 tapers, the
fissure opens outwardly in the upwards direction.
The grooves 17a on the projections 17 of the lower piece form
a snap fit with the rib 9a on the lip 9 of the main part to
hold the two pieces together in this "closed" configuration.
The annular projections have spaces between them so that there
is free access for beverage and gas within the chamber to
reach the groove 14a when the gas and/or beverage is to be
ejected.
Below the groove 14a there is a significant volume of the
chamber, and this provides the effect described later.
The illustrated insert is most suitable for use with canned
beer. The insert is located within a standard beer can, as
shown in Figs. 5a-d and the can is,filled and immediately
sealed in the conventional manner. Beer containing carbon
dioxide gas in solution is tapped into the can at a
temperature just above its freezing point. The beer is able
19
wo 94~15871 ~33~ PCT/GB94/0002~ ~
to flow freely around the incert. Holes 21 in the top of the
ears prevent the formation of air pockets thereunder and beer
can also pass down through the tube in the centre of the
insert. A head-space is left above the beer. Fig. 5a shows
an insert immediately after the can has been filled.
When the can has been sealed, gas evolving from solution
builds up in the head-space causing a rise in pressure.
There may also be dosing of the head-space with liquid
nitrogen. The pressure will also increase as the can is
allowed to reach storage temperature and more gas comes out of
solution. The increase in pressure inside the can forces beer
into the insert via the fissure provided by groove 14a (see
Fig. 5b). This will continue until a pressure equilibrium is
reached between the inside of the insert and the remaining
part of the inside of the can. The result of this is the
insert becomes partly filled with beer and partly with
compressed gas, as shown in Fig. 5c. If the can is
pasteurised in its upright position, a further build-up of
pressure occurs, leading to even greater amounts of beer
entering the insert, but this effect is reversed upon cooling.
However, as discussed previously, the can may be inverted for
pasteurisation. In this case gas from the head-space may flow
directly into the insert, thereby increasing the final volume
of gas in the insert.
If the gas in the container is assumed to be ideal, the
following condition is satisfied:-
PV = constant or P1V1 = P2V2
T T1 T2
where:
P = Pressure
V = Volume
T = Temperature (in degrees Kelvin)
094/15871 ~ 3 3 ~ ~ PCT/GB94/00022
In a typical case, the volume-of the insert is 15.7ml and the
can is filled at approximately 0C, or 273K. The C02 level is
equivalent to 1.00 V/V (at s.t.p) at equilibrium. The
Nitrogen level is equivalent to 72.0 mg/litre at equilibrium.
After sealing, the pressure inside the can rises to 3.08 bar
(absolute). As the insert is originally at atmospheric
pressure (1 bar absolute), the new volume of gas inside the
insert, after equilibrium is reached at 0C will be:-
V2 = (lbar) x (15.7ml)
(3.08 bar)
= 5.lml
There is, therefore, 15.7-5.1 = 10.6ml of beer inside the
insert.
As the temperature rises, there will be an increase in
pressure leading to an increased volume of beer inside the
insert. At 4-C, 8C and 20C the pressures (bar absolute)
would be 3.22, 3.37 and 3.85.
As noted above the fissure provided by groove 14a is displaced
above the lowest part of the chamber and there is a
significant volume of the chamber below it. This volume acts
as a "reservoir" of beer. In fact, 5.4ml of the volume of the
chamber is below the fissure, so that at least 5.2ml of beer
is above it in this example.
When the can is broached, a sudden de-pressurisation occurs
and the pressure inside the can drops to 1 bar. This results
in a pressure differential between the can and the insert
which, in turn, results in the gas in the insert expanding.
Since beer is inside the insert above the fissure, this is
driven out by the expanding gas. This is shown in Fig. 5c.
The streaming beer may cause a very limited amount of foam
production, but its main effect is to delay the release of
gas. There is also a transient increase of the volume of the
.
21
WO94/15871 ~ 3~ PCT/GB94/00022
chamber, caused by bowing out of the flexible walls of the
cuboid portion and this helps reduce unwanted initial effects.
Once the beer drops to level with the fissure, gas or a gas-
beer mixture streams out as shown in Fig. 5d and most of the
beer below the fissure remains in the insert. The gas form
streaming out of the insert rapidly produces a large amount of
foam, such that when the beer is poured from the can an
attractive, creamy head is produced. The amount of gas which
flows out is roughly equal to the amount of beer left inside
the insert.
In practice these theoretical figures will not be achieved due
to transient effects and the gas "carrying" some beverage with
it. However, they serve to illustrate the principle of how
firstly liquid and then gas is ejected.
The filling and closing of the insert in the above embodiment
may be performed outside of the can, and involves flushing
through with gas. In an alternative arrangement shown in
Figure 6, an evacuation and filling technique is used and this
may be particularly advantageous if filling the insert when in
the can.
In this embodiment an evacuation and gas injection tube 22 is
pushed into the insert from above. A portion 23 forms a seal
with lip lO, and a portion 24 forms a seal with spigot 14.
Laterally directed apertures 25 are used to evacuate the
insert to purge it of air, and then to inject nitrogen into
it. During evacuation the insert is sucked onto the tube 22,
and held in place. Thus the tube can be used to position the
insert in a can.
The tube 22 has a shoulder 26 which engages a flange 27 at the
base of the main part of tube 6, to ensure correct
positioning.
2~3~1~
094/15871 PCT/GB94100022
The overall construction of the insert is such that it is easy
to manufacture, easy to assemble, and easy to fill with gas.
It is also designed for easy stacking for storage and
transportation purposes.
A second embodiment of the invention will now be described
with reference to Figures 7 to 15.
The insert 28 is made from two pieces of injection moulded,
resilient plastics material 29 and 30, such as food grade high
density polypropylene, with a wall thickness of e.g. 8mm. The
main, upper part 29 of the insert has a chamber 31 and two
diametrically opposed wings 32.
The chamber is defined by a generally cuboid-shaped portion 33
in the centre of which is a hollow tube 34 of tapering
circular cross-section.
Below the cuboid portion 33 there is a downwardly extending
skirt 35. At the lowermost part of the skirt there is an
internal groove 36 which forms part of a snap-fit mechanism
which is used to connect the two parts of the insert together
in a sealing fashion around their circumferences.
The base of the tube 34 is divided into two coaxial portions
37 and 38 by a step 39. The outer portion 37 is provided with
an annular rib 40 projecting from its outer wall. The inner
portion 38 defines a hole in the base of the tube 34 and
tapers outwardly in the upwards direction. These portions co-
operate with parts of the lower piece in a manner discussed
below.
The purpose of the wings 32 is to locate the insert within a
beverage container such as a beer can. Their outer faces 41
are therefore curved as shown in Fig. 7 and have a similar
radius of curvature to that of the container in which the
insert is to be used. The wings 32 extend from opposite sides
23
WO94/15871 ~3~ PCT/GB94/00022
of the lower part of the skir~ 35. Each wing comprises an
outer tab 42 attached to skirt 35 by a pair of flexible hinges
43. Thus, each tab can be folded upwardly against the
resilience of hinges 43 to permit insertion of the insert into
a container. The tabs 42 also have lugs 44 which project
below the plane of the hinges 43. Thus, once the insert is in
portion the tabs 42 will be pressed against the container
walls by the resilience of hinges 43, whilst the lugs 44 will
resist movement from this position. As shown in Figure 9,
each tab 42 has its outer face 41 cut away at 45 in an arcuate
manner. This matches the curvature of portions 46 of the
skirt. As a result, during insertion the tabs 42 can be
folded up to a vertical position with the cut away portion 45
receiving portions 46 on the skirt.
The main chamber 31 is defined by a portion of generally
square shape in plan view, as shown in Figure 7. The sides 47
are joined by curved portions 48. This arrangement
facilitates outwards bowing of the walls to absorb initial
pressure differential effects in use.
The tabs 42 are provided with apertures 49 to assist the flow
of beer during filling of a container provided with the
insert.
The second moulded piece 30 forms the base of the insert. It
is generally disc-shaped and has an outer skirt 50 with an
annular lip 51 which forms a snap-fit into the groove 36 of
the main piece 29, with skirt 50 in sealing engagement with
the inside of the lower portion of skirt 35 as shown in Figs.
12 and 13.
The second piece 30 has two stable configurations. These are
assisted by incorporating an annular groove 52 into the disc
which acts as a hinge region and assists the disc to snap
between positions. In the first position (as shown in Fig.
12) the disc is bowed outwardly in the downwards direction.
.
24
~ 094/15871 ~ 1~ 3 ~ t ~ PCT/GB94/00022
This is an open configuration~in which the insert is
assembled. In the second configuration as shown in Fig. 13,
the disc is bored upwards to a closed configuration. In this
closed configuration, pressure within the insert will act on
the upwardly bowed portion 53. The resultant force is
transmitted to the join between this and the skirt 50, at -
groove 52 and has a component in the horizontal direction
which urges the skirt 50 against the skirt 35 of the other
piece. Thus, sealing is enhanced to resist increases in
pressure.
In the centre of the disc there is a hollow spigot 54, open at
both ends, having an external diameter approximately equal to
the interior diameter of the hole through inner portion 38 in
the centre of the main piece 29, so that the spigot can form a
sealing press fit within the tube. Around the aperture at the
lower end of the spigot are proje~ctions 55 on the outer face
of the disc which are used to space the insert from the base
of a container in which it is placed. Spaces 56 between the
projections 55 permit the flow of beer during filling.
Disposed around the spigot 54 on the inside face of the disc
there are four further projections 57. When the insert is
assembled and the disc is in the closed configuration as shown
in Fig. 13, grooves 58 on these projections form a snap fit
with the rib 40, thus holding the centres of the two pieces
together.
The spigot 54 is provided with a longitudinally extending "V"
shaped groove 59 shown more clearly in Fig. lla. This is
about 0.3mm deep and has a right angle base. It is this that
will provide the orifice for gas and beverage discharge in the
manner described below.
An assembled insert with the disc in the open configuration is
illustrated in Fig. 12. From this figure it may be seen that
the chamber is closed except for the openings provided by the
wo 94~1~871 ~3~6 PCT/GB94100022 ~
apertures in the spigot and t~be.
Once the insert has been filled with an "inert" gas such as
nitrogen, carbon dioxide or a mixture of the two in the manner
disclosed below, the second part of the insert is pushed
upwards into its second configuration substantially to close
the chamber, as shown in Fig. 13. In this configuration the
spigot 54 on the second piece fits closely within portion 38
on the first piece, to form a seal around most of the
circumference. The exception is that the groove 59 forms a
longitudinal, upwardly directed fissure communicating the
chamber with the outside. Since the portion 38 tapers, the
fissure opens outwardly in the upwards direction.
The grooves 58 on the projections 57 of the lower piece form a
snap fit with the rib 40 on the portion 38 of the main part to
hold the two pieces together in this "closed" configuration.
The projections 57 have spaces between them so that there is
free access for beverage and gas within the chamber to reach
the groove 59 when the gas and/or beverage is to be ejected.
Below the groove 59 there is a significant volume of the
chamber, e.g. 5.4ml for a total internal value of 15.7ml.
The insert is used and operates in the same way as the first
embodiment described above, ejecting first beer and then the
gas which initiates head formation.
Apparatus for inserting the insert 28 into a can, and for
filling it with gas will now be described with reference to
Figures 14 and 15.
Figure 14 shows a view of one station for handling the insert
20 and inserting it into a can 60. The apparatus is supported
by a bottom plate 61. On this is a pneumatic cylinder 62
carrying a can support 63. The can support has an upwardly
domed support piece 64 to support the bottom of a conventional
26
~ 094/1~871 21~ 3 3 ~ ~ PCT/GB94/00022
can which is domed in this manner.
Vertically above the can support 63 is an upper support 65.
This is tubular, with a cut out portion 66 on one side. In
use, a can 60 is slid into position on the bottom support 63
and through the side cut out 66 of the top support 65.
Pneumatic cylinder 62 is then operated to push the can 60 up
inside the top support until it engages a shoulder 67. To
remove the can eventually the process is reversed.
Above the shoulder 67 is a downwardly tapering insert guide 68
of frustoconical form. At its upper end 69 this has a
diameter slightly exceeding that of the insert in its unused
state - with the wings 32 fully extended. At its lower end 70
it has a diameter slightly less than that of the opening 71
into the can. The insert can therefore be pushed downwardly
through the guide 68, into the can. The wings 32 will fold up
and then spring out again when the insert is inside the can,
to grip its walls. The insert can be pushed to the bottom of
the can but will resist upwards movement again.
The insert 28 is shown mounted on an insertion mechanism 72,
the lower end of which is similar in construction to that
shown in Figure 6. The insertion mechanism is supported from
a pneumatic cylinder arrangement 73 which is used to push the
mechanism downwardly and then retract it. The mechanism 72 is
shown more clearly in Fig. 15.
The mechanism 72 comprises a top flange 74 which is slidably
supported on rods 75 (Fig. 14) connected to the piston rod 76
of pneumatic cylinder arrangement 73, the rods 75 passing
through apertures 76 in flange 74. The lower ends of rods 75
are fixed to an outer cylinder 77. Coaxially arranged within
the outer cylinder 77 are an inner cylinder 78 and a central
tube 79. Inner cylinder 78 is fixed to the top flange 74. A
helical spring 80 acts between a shoulder 81 on the inner
cylinder 78, and a shoulder 82 on outer cylinder 77. The
27
wo 94~15871 ~33~ PCT/GB94/00022 ~
central tube 79 is slidably mQunted in the top flange 74 and
connected at its lower end to a head 83. The head has a
flange 84 which engages a stop 85 on the interior of inner
cylinder 78. A helical spring 86 extends between the upper
surface of this flange 84, and the top flange 74.
The head 83 has a bore 85, a lateral bore 86, an upper
frustoconical portion 87, an intermediate portion 88 (with the
lateral bore) and a lower portion 89. It may thus engage the
insert 28 in the condition shown in Fig. 12, with the upper
and lower holes sealed and the lateral bore 86 of the head in
communication with the interior of the insert. This is a
condition equivalent to that shown in Fig. 6, and Fig. 14
shows the insert 28 in this condition. Gaskets could be used
to improve sealing.
The bore 85 in the head 83 is connected sealingly to a gas
supply and vacuum pipe (not shown) which passes up central
tube 79 and, via a changeover valve, to a vacuum pump and a
nitrogen supply.
As shown in ~ig. 14, the insert 28 is in place. It is kept in
place by applying a vacuum to the bore 85, which both purges
the insert of air and holds it onto the apparatus.
To commence the insertion process, the can 60 is pushed up
into engagement with the shoulder 67. The insertion mechanism
72 is pushed down by the pneumatic cylinder arrangements 73 so
that the insert passes through guide 68, into the can and down
to the bottom (which is supported from outside despite its
domed shape). During this period the vacuum is maintained.
Just as the insert reaches the bottom,i.e. when the
projections 55 rest on the bottom, the changeover valve is
operated and nitrogen is supplied to the head 83. This passes
into the insert through side bore 86.
28
~ 094/15871 215 3 3 ~ ~ PCT/GB94/00022
Downwards motion is now continued. As this occurs, the outer
cylinder moves downwardly and presses around the periphery of
the upper part of the insert. This pressure causes the lower
part to bow inwardly to the closed condition as shown in Fig.
13, forming a sealed snap fit with the other part. During
this phase, the outer cylinder moves relative to the inner
cylinder through the spring 80, and the head 83 and central
tube 79 move upwardly against the spring 86.
Downwards motion is now terminated and the entire mechanism is
withdrawn. A stop is used to ensure that the insert cannot be
crushed. During the withdrawal period nitrogen continues to
be passed through, to ensure that the minimum amount of air is
allowed into the can.
The above description is in respect of a single station. In a
commercial installation, a number of such station would be
provided, e.g. mounted on a turntable.
Instead of using piston/cylinder arrangements, cam tracks
could be used to facilitate operation and synchronisation.
After the insert has been positioned, the can is moved by
means of a suitable transfer conveyor to another station for
filling with beer and sealing. The transfer time should be as
short as possible and periods of e.g. 15-20 seconds may be
preferred to prevent air entering the can. Dosing with liquid
nitrogen at this stage could be effected to reduce problems of
air contamination.
