WO1995009783A1

WO1995009783A1 - Beverage can with foam generating capsule

Info

Publication number: WO1995009783A1
Application number: PCT/GB1994/002108
Authority: WO
Inventors: Andrew John Reynolds; John Kelshaw Conway; John David Skingsley; Peter Erich Cox
Original assignee: Scottish & Newcastle Plc
Priority date: 1993-10-01
Filing date: 1994-09-28
Publication date: 1995-04-13
Also published as: CA2170027A1; DE69403224D1; GB9606134D0; AU678056B2; GB2298407B; CA2170027C; NZ273657A; AU7703894A; EP0720575A1; ATE152995T1; GB2298407A; EP0720575B1

Abstract

A sealed beverage can has fitted therein a capsule (10) forming a secondary chamber within the can, the capsule having an associated standpipe (12) apertured at (14) beneath the capsule and terminating at its upper end (16) just below a deformable roof (18) of the capsule, thereby to form an openable and closable valve at the upper end of the tube, whereby communication between the interior of the capsule and the contents of the can is restricted until at least after the can is inverted during pasturisation, whereafter pressurised gas in the gas headspace is able to enter the capsule through the said aperture after the said valve has opened. The restrictor may comprise a controlled leak across the valve which permits the slow ingress of fluid into the capsule. Alternatively at least part of the wall of the capsule is formed from gas permeable material, the permeability of which is such as to restrict the ingress of gas for a sufficient length of time as to prevent a balancing of the pressures to occur until at least after pasturisation has begun.

Description

Beverage can with foam generating capsule.

Field of the invention

This invention concerns devices for use in packaging beverages particularly alcoholic beverages, especially beers, ales, stout and lagers, containing dissolved gases such as nitrogen which on being dispensed into a glass or mug desirably form a frothy head some 1 or 2 cm deep on the surface of the beverage which is relatively permanent in that foam remains on the surface of the beverage at least for a minute or two if not longer. The invention is of particular application to beverages such as aforesaid when packed in two piece metal cans comprising a lower cannister typically of spun aluminium and a flat lid which is seamed around its periphery to the upper open end of the can after the latter has been filled with the beverage.

Background to the invention

It has been proposed to push-fit into such cans a small plastics insert, sometimes referred to as a hollow pod or capsule, forming a secondary chamber which when the can is filled with beverage will normally be immersed in the beverage but which, if the can -is inverted, will communicate with the gaseous headspace which normally exists over the beverage in the can through a small passage between the outside and inside of the plastics insert, so the secondary chamber formed by the insert can be primed with gas from the gaseous headspace while the can is inverted..

If the passage terminates in an opening which, when the can is stood on its base, faces downwards, there will be little tendency for any gas trapped within the capsule to leave the capsule as might otherwise be the case until such time as the lid of the can is broached when the gaseous pressure above the beverage is relieved to atmosphere and any excess pressure within the capsule causes gas within the capsule to be discharged as a stream of bubbles into the beverage thereby forming a foaming head on the beverage as the latter is dispensed.

More particularly, by inverting the can shortly after seaming whilst the liquid nitrogen is still evaporating the gas headspace at the upper end of the can will be transferred to the up-ended base of the can and if the insert or pod is secured at the bottom of the can, the insert will now be surrounded by gas instead of liquid. The increasing can pressure will therefore drive gas into the insert instead of beverage.

Depending on when the can is inverted so the insert will be more or less filled with beverage or gas respectively.

If, as is usual, the can is left in its inverted condition during pasteurisation when it is first heated and then cooled, there will be a further tendency for gas to be driven into the insert, and depending on the choice of hole position (it may for example be in a side wall of the insert) so there may be a gas-liquid exchange such that there is a net gain of gas in the insert .

If the can is thermally cycled as between normal house temperature and the temperature of a domestic refrigerator, with the can in its normal upright position, there may be a further liquid-gas exchange such that more liquid is left in the insert .

Since any liquid trapped in the insert reduces the volume of the insert available for gas and since it is the latter which creates the creamy foamy head, it is advantageous if the quantity of beverage entering the insert is constant so that a consistent head producing effect is obtained. In one proposed device the passage is simply an aperture in a wall of the capsule and the latter is shaped at least internally so as to provide a well such that, during the first stage during and after the can is filled with beverage, and liquid may be driven into the capsule, any liquid so driven in will flow into the well section of the capsule and when the can is upended (inverted) gas will flow through the small aperture into the capsule, bubbling through any beverage in the capsule if the latter, when the capsule is upside down, covers the hole. The invention of this arrangement is however that the hole is not covered by beverage when the can is standing in its normal upright position, but that any beverage is contained within the well so that when the can is broached it is the gas trapped above the liquid in the capsule which is jetted through the aperture and not the trapped beverage.

A later proposal provides a chimney or standpipe which extends upwardly within the capsule interior from the small aperture in the base of the capsule. The proposal is that the standpipe should extend to a position just below the top of the capsule so that even if the capsule were to become substantially filled with beverage the small aperture would always communicate with the gaseous headspace in the secondary chamber formed by the capsule by means of the standpipe. The only disadvantage of trapping a relatively large volume of beverage within the capsule concerns the waste that the trapped beverage represents. In general it has been found that only a relatively small volume of gas trapped under high pressure (typically 3 to 4 atmospheres) is sufficient to produce the head generating surge of gas bubbles.

The present invention seeks to overcome the problems of existing proposals and reduce the ingress of beverage into the secondary chamber whilst retaining all the advantages of the simplicity of the permanently open capsule and self priming features of such a design, when combined with the conventional step of inverting the can on a canning line, which has occurred for at least the past ten years or more for the purpose of checking for any leaks around the seam join between the lid and the can.

Summary of the invention

According to the present invention the capsule for securing within a can as aforesaid for creating a secondary chamber therein comprises a hollow enclosure having an underside aperture which communicates with the interior of the capsule through an upstanding tube or pipe the upper end of which is open and which is situated just below the underside of the roof section of the capsule, the said roof section being resiliently deformable under external or internal pressure so as to be movable towards and away from the said open upper end of the tube, the underside of the roof section cooperating with the upper end of the tube to substantially or completely close off the end of the tube when the roof is deformed inwardly but when deformed outwardly permitting gaseous exchange between the inside and outside of the capsule through the tube and aperture.

The aperture may be at the lower end of the tube, but not essentially so.

In general the capsule is adapted to be fitted into a can of the type which has a lid which is seamed in place after the can has been filled with beverage and pressurised as by dosing with liquid nitrogen or other liquefied gas. The mechanism by which the capsule is fitted into the can and retained therein is not the subject of this application and any known technique may be employed as by friction fit, adhesive, deformation of the wall of the can or by way of protrusions extending upwardly from the capsule so as to be engaged by the lid and thereby prevent the capsule from rising within the can after the lid has been -placed in Oosition. The deformability of the roof of the capsule is selected so as to determine the opening and closing of the valve at the upper end of the internal tube so that the capsule will communicate with the contents of the can in any desired manner.

In one arrangement the tension and deformability in the roof is selected so that the upper end of the tube is normally open to the interior of the capsule but a relatively small excess pressure on the outside of the capsule will tend to cause the roof to collapse against the upper end of the tube and thereby seal the ingress of liquid or gas into the interior of the capsule.

In another embodiment the roof is designed so that its natural resilience tends to close off the upper end of the tube so that the capsule is to all intents and purposes sealed when it is located within the can and means is provided within the capsule or associated with the roof to lift clear of the upper end of the tube after the can has been filled with beverage and pressurised. Thus for example the roof may have formed thereon a buoyant member which will cause the roof to be lifted as a result of the buoyancy of the buoyancy member associated therewith after the can has been substantially filled with liquid. Alternatively the capsule may be filled with a gas having a relatively low boiling point such that when the can is subsequently heated as during pasteurisation, the pressure within the capsule becomes greater than the gas pressure building up within the can and causes the roof to separate from the upper end of the tube.

Alternatively and preferably the roof is designed so that it is separate from the upper end of the tube but can and will be displaced downwardly into contact with the upper end of the tube inside the capsule as soon as the capsule externally is subjected to a pressure greater than the given threshold (for example if a relative pressure difference between the interior and exterior of the capsule is greater than one atmosphere) , and the sealing between the roof and the upper end of the tube is such as to admit a controlled leakage into the interior of the capsule between the upper end of the tube and the inside of the roof so that the external pressure acting on the capsule slowly becomes balanced by the internal pressure building up within the capsule due to leakage. Thus it will be seen that if the capsule interior starts at atmospheric pressure and the can after seaming rapidly rises three or four atmospheres, as may well be the case in a conventional line canning nitrogenated beer dosed with liquid nitrogen on seaming, the capsule will be rapidly exposed to an external net pressure of two or three atmospheres and the roof will deform and close off the upper end of the tube almost immediately the can has been seamed. Until the pressure within the capsule has built up (under the controlled leakage) to a value such that the net pressure across the capsule wall is less than one atmosphere (or whatever threshold is required to deform the lid) , the roof will remain deformed and the leakage will be controlled. As soon as the net pressure has become less than the critical threshold the roof will deform outwardly opening the upper end of the tube and enabling the pressure within the capsule to balance rapidly to whatever pressure is within the can.

It is to be noted that if the can has been inverted so that the capsule is now surrounded by the gaseous headspace rather than by liquid, the ingress of liquid into the capsule through the controlled leakage will cease and further controlled leakage into the capsule will be gaseous only. Since, due to surface tension, the ingress of liquid may well be substantially inhibited if the gap defining the controlled leakage is small enough, there will be little tendency for any liquid such as beer to permeate into the capsule, but as soon as the can has been turned upside down (as is conventional on most canning lines for leak detection) , the surrounding gas will more readily permeate into the capsule and the fluid exchange to effect pressure balancing between the interior and exterior of the capsule will be gaseous and not liquid. Clearly this is advantageous if the capsule is to jet gas as is desired in order to generate the head when the can is opened and the beverage is poured. Any liquid which has permeated into the capsule must be retained within the capsule and is wasted as far as the consumer is concerned and merely represents a reduction in the available volume of the capsule for the storage of a charge of gas for generating the head. Although only a relatively small volume of gas is actually needed (typically 3 to 5 millilitres) it is nevertheless undesirable for similar quantities or even larger quantities of beverage to be retained within the capsule due to unwanted leakage of the beverage into the capsule whilst the can is standing on its base and before it has been turned over. The invention clearly allows the ingress of such beverage during such a period of time to be limited and possibly eliminated if the leak can be designed so as to inhibit the ingress of liquid and only permit the ingress of gas.

In order to obviate entirely the ingress of gas, a particularly preferred arrangement is one in which the roof is deformed so as to close off the upper end of the tube by the pressure exerted on the interior of the can when the latter is initially clamped to a filler. Conventionally the can is filled under pressure, typically 20psi or thereabouts, and if the capsule has been inserted into the can at atmospheric pressure and the can is then subject suddenly to a pressure of some 20psi or more above atmospheric pressure, the roof will collapse inwardly against the upper end of the tube and close off the end of the tube very shortly after the can has been pressurised and before the beverage is jetted into the can by the filler. In this way the capsule will be sealed to all intents and purposes against any ingress of liquid while the can is being filled and seamed and pressurised. By arranging that the seal is a perfect seal with regard to the ingress of liquid the interior of the capsule will remain entirely liquid free whilst the can remains in its ordinary upright condition and the capsule is immersed below the level of the beverage. This is quite different from any previous proposals for such devices which are to be self primed by means of the internal pressure within the can since hitherto all such devices have had a permanent communicating aperture between the interior of the capsule and the contents of the can so as to enable the capsule to be primed at the appropriate time, and to jet gas therefrom when the can is opened.

In this last mentioned arrangement, the capsule preferably contains a device which is temperature sensitive or pressure sensitive and when actuated serves to create a small gap between the roof and the upper end of the tube or exposes a small aperture through the wall of the tube at the upper end thereof so as to enable the interior of the capsule to communicate with the surrounding gas. In this event the capsule remains sealed until after the can has passed into the pasteuriser and the temperature of the can has been raised which, if the device is temperature sensitive, will simply trigger the device due to the rising temperature and if the device is pressure sensitive the latter will be triggered as the internal pressure within the can rises due to the rising temperature thereof. Since the can is inverted in the pasteuriser and the capsule communicates with the gaseous headspace at the now upper end of the inverted can instead of the liquid contents of the can, when the temperature or pressure trigger occurs, and the capsule roof moves away from the tube or by some other means communication is established between the outside of the capsule and the inside of the capsule via an aperture or other device at the end of the tube near the roof, the only fluid which will pass into the capsule will be gas from the headspace so that the capsule will be charged wholly with gas and there will be little or no tendency for beverage to enter the capsule either at that stage or thereafter.

It is to be understood that once the can has passed through the pasteuriser and is once again turned into its normal attitude so that it is sitting on its base, the capsule will of course then be surrounded by beverage as is the case with other designs of can primed capsule. Since there is now a permanent communication between the inside and outside of the capsule due to the balanced pressure, thermal cycling of the can, as for example if it is placed in a refrigerator and then removed, may cause a very small quantity of beverage to be drawn up the tube and may even spill over the top of the tube into the capsule in precisely the same way as may occur with conventional designs of can primed capsule. However it will be appreciated that the quantity of beverage which is likely to enter the capsule at this stage due to such temperature cycling is very insignificant and can in fact be substantially eliminated if the can is normally stored in an upended state. Since the rim seal around the lid is relatively strong and the inversion of the cans on the canning lines has been performed historically not only to reveal any leak around the rim seal but also to reduce the damage to the relatively vulnerable base of the two part can as the can is shuffled at high speed along a conveyor, it will be seen that storing the can upside down on its lid will in fact present no problem in practice and may even improve the stability of the can when stored in the refrigerator etc . However it is to be understood that this particular method of storage is not essential for the invention since the invention is not aimed at preventing the ingress of beverage into the capsule during thermal cycling after the can has been pasteurised and is merely in storage but is aimed at preventing or substantially eliminating the ingress of beverage into the capsule when it is much more vulnerable to large scale intrusion of liquid as can occur while the can is being filled and pressurised in the initial stages before the can is turned over ready for pasteurisation.

A controlled leakage may be achieved by moulding a small groove onto one of the sealing surfaces either of the roof or the upper end of the tube. A temperature sensitive member may comprise an annulus of material made up of two segments of material having different temperature coefficients such that with rise in temperature the thickness of one segment of the annulus becomes somewhat greater than the increase in thickness of the other segment of the annulus so that a slit-like aperture begins to form around part of the annulus enabling gas to pass from the tube into the interior of the capsule.

Where one of the earlier described embodiments has been tested without a temperature sensitive element and the ingress of liquid has been controlled by means of a controlled leak of liquid or gas into the capsule, delays of between 15 seconds and some minutes have been achieved so that clearly using a controlled leak set to delay opening by a minute or so, will enable the capsule to remain substantially sealed to all intents and purposes until after the can is in the pasteuriser so that it matters not where the can is turned over on the line prior to entering the pasteuriser. Although from mechanical handling considerations it is usually desirable to upend the can relatively soon after seaming so that the can travels on its stronger rim seal rather than on its vulnerable base, the need to turn the can over quickly so as to prevent the ingress of excess beverage into the capsule (as is the case with designs in which the capsule interior is in permanent communication with the can interior) is obviated and if for operating reasons it is more desirable to turn the can over further down the line towards the pasteuriser, the twist can be put in the line at any desired or chosen position depending on the circumstances. In fact this is normally the case, since it is advantageous on high speed lines to locate the twist a reasonable distance from the seamer so that if a jam occurs, there is a "buffer" zone for filled and seamed cans.

Historically nitrogen has been used to fill the capsule so as to exclude oxygen, to purge the can of oxygen prior to filling, and to pressurise the can after it has been substantially filled with beverage. Typically many beers are stored under nitrogen and therefore contain nitrogen dissolved therein. Liquid nitrogen has been injected into the can just before the lid has been placed thereon so as to further generate pressure within the can as the liquid nitrogen boils in the closed environment and historically the rich foamy head associated with certain brands of beer and ale and stout has been found to be particularly acceptable and of long duration as a consequence of using nitrogen.

Experiments have indicated that argon can be substituted for nitrogen. It is an easier gas to control on the canning line and experiments also indicate that the same height and texture of frothy head can be obtained using a smaller volume of argon than if nitrogen had been used under the same conditions. The invention thus also envisages the use of argon instead of nitrogen at least as the gas to be initially trapped within the capsule after purging and in the headspace in the can and for liquid argon as opposed to liquid nitrogen to be injected into the can before sealing the can by seaming the lid into position.

In the description of the invention as thus far described, it is generally assumed that the capsule is fixed at or near the bottom of the upright (non-inverted) can. However, this is by no means essential.

Thus, according to a further feature of the present invention, in a can fitted with a hollow capsule as aforesaid, which includes a liquid trap internally thereof, the capsule is positioned generally in the middle of the can so that whether the can is upright or inverted the aperture in the capsule remains submerged. In this way, the capsule will only ever be charged by the entry of liquid forced in by the increasing can pressure, even when the can is inverted in the pasteuriser and/or is upright and thermally cycled as between refrigerator and ambient temperature. Where a liquid lock is employed any excess liquid entering the capsule (as during pasteurisation) will simply be forced out of the capsule as the internal can pressure drops so as to maintain equilibrium. The continued submersion of the capsule will mean that whatever proportions of liquid to gas are established in the capsule during the initial pressurisation of the can contents, those proportions will be maintained and merely altered slightly depending on the actual temperature of the can at opening so that if cans are always at the same temperature just before opening there will always be the same volume of gas trapped in the capsule whatever and whenever inversion of the can has occurred.

The only possible disadvantage of this feature is that a relatively large volume of beverage may be forced into the capsule in order to obtain equilibrium, since if the capsule never communicates with a gas space in the can there will be no possibility to partially charge the capsule interior with gas instead of beverage.

However, this is overcome if the capsule includes valve means such as a deformable section of the capsule wall which under external pressure deflects inwardly against spring means (or merely overcoming a natural resilience to occupy its undeflected condition) , so as to close off entry into the capsule as soon as the interior of the can begins to increase in pressure. This can for example be arranged to occur as soon as the can is attached to the filler and even before any liquid is forced into the can from the filler.

According to a further and preferred aspect of the invention at least part of the capsule wall or roof is formed from a material which has a predictable permeability to gases dissolved in the beverage such as carbon dioxide, nitrogen, or argon. Permeation of the gases into the interior of the capsule causes the internal pressure in the capsule to rise, until its internal pressure is at or a little less than chat within the can, at which point the valve opens (e.g. the wall region of the capsule lifts off the end of the tube opening the capsule interior to the can contents) , and a small volume of gas or beverage (depending on where the aperture is situated in the can) will enter the capsule to equilibriate the pressure within and without the capsule.

By placing the capsule generally in the middle of the can, only beverage will enter the capsule when the valve means opens, so that the effect can be standardised as between one can and another, and by including a liquid trap within the capsule, so any beverage entering the capsule at this stage will be prevented from interfering with the jet of gas leaving the capsule when the can is finally broached before pouring. However, if by deferring the opening of the valve until the pressure in the capsule has been largely baklanced by permeation of gas, the internal pressure is already almost equal to the pressure in the can, and only sufficient beverage has to be forced in to just balance the pressures.

It will be obvious that, when in accordance with the invention, the capsule includes an upstanding pipe or tube, the deformable section of the wall of the capsule may be constituted by the roof section, the underside of which can substantially or completely close off the open upper end of the pipe or tube as desired.

The invention overcomes many of the problems associated with earlier designs of can primed capsule for head production on dispensing and represents a significant technical advance in that, by substantially preventing the ingress of beverage into the capsule, the actual volume of the capsule for storing gas therein can be substantially reduced whether argon or nitrogen is used.

The invention is now further described by way of example with reference to the accompanying drawings, in which:- Figures 1 and 2 show a capsule for fitting in a beer can, respectively in two alternative operative conditions;

Figures 3 to 6 serve to show several methods of creating a small leak into the the capsule, at the top of an associated standpipe;

Figures 7 to 10 show steps in the procedure of filling a can in which a capsule has been inserted; and

Figures 11 and 12 respectively show a can incorporating a modified capsule and one possible construction of the modified capsule.

Description of embodiments

Figures 1 and 2 show a capsule 10 suitable for insertion in a can prior to filling the can with a beverage such as beer, nitrogenating, and sealing. The capsule 10 incorporates a standpipe 12, apertured near its lower end at 14 and having an open upper end 16. The roof 18 of the capsule is deformable. When the pressure in the can is equal to the pressure within the capsule, the latter assumes the condition shown in Figure 1 in which liquid and/or gas can enter the capsule through the aperture 14 and up the standpipe 12. When the external pressure (the can pressure) exceeds the internal pressure (the pressure within the capsule) , the roof 18 deforms substantially to close the upper end of the standpipe, as shown in Figure 2, except for a small controlled leak.

Referring now to Figure 3, it can be seen that the roof 18 of the capsule preferably has a thickened central region 20 for ensuring that, notwithstanding deformation of the remaining part of the roof, a flat surface is provided for closing against the upper end of the standpipe 12.

Figures 4 to 6 show by way of example three possible methods for achieving a minute controlled leak between the upper end of the standpipe 12 and the roof section which closes against it.

In the proposal of Figure 4, the undersurface of the central region 20 of the roof 18 has a surface finish manufactured to produce a controlled micro-leak. This surface finish may be a predetermined surface roughness, or a series of minute grooves.

Conversely, as shown in Figure 5, the upper end face of the standpipe 12 may be given a textured finish or, as shown in Figure 6, this upper end face of the standpipe 12 may be provided with a shallow groove 21.

The capsule is made of plastics material and the thickness and properties of this material determine the pressure required to deform the roof of the capsule sufficiently to close the upper end of the standpipe, and therefore to some extent the degree to which this closure is absolute, i.e., a sealed closure.

Figures 7 to 10 illustrate the method of use of the capsule on a production line and the way in which the capsule operates during the can filling, nitrogenating and can sealing process.

Referring first to Figure 7, an open, unlidded can 30 is shown, having a capsule 10 inserted therein and held in position, near the bottom of the can, by a spider 32.

Fitted to the top of the can 30 is a filling device 36 which comprises beer delivery nozzles 38, arranged to ensure minimum disturbance to the beer on filling, and a floating ball cage valve 40 through which gas exits as it is displaced from the can. The floating valve shuts off escape of gas when a predetermined fill level is attained, and thus prevents further ingress of beer. Filling is effected under pressure, e.g. 20 p.s.i., so that during the filling process the existing counterpressure substantially closes the standpipe 12 and there is substantially no flow of beer into the capsule 10 through the aperture 14 and up the standpipe.

Figure 7 shows the condition at the beginning of the filling cycle and Figure 8 shows the condition at the end of the filling cycle, just prior to release of the counterpressure when the can 30 is withdrawn from the filling device 36.

When the can 30 is withdrawn from the filling device 36, the roof 18 of the capsule 12 restores to its natural position, but there no longer exists any pressure to drive beer up the standpipe 12 and into the capsule 10. The can 30 can thus be conveyed to a seamer without ingress of beer into the capsule 10. At the seamer, the beer is nitrogenated with a dose of nitrogen under pressure and the lid is seamed in place under a nitrogen atmosphere. Under the pressure of nitrogenation, the roof 18 of the capsule 10 deforms again to close off the upper end of the standpipe 12.

A small ingress of fluid into the capsule will take place over a predetermined time period due to the controlled leakage provided for at the upper end of the standpipe 12, but the capsule is inverted ready for checking of the lid seam and pasteurisation before any significant ingress has occurred. The condition of the can 30 and capsule 10 immediately subsequent to can inversion is shown in Figure 9. It will be noted that the normal fill level is part-way up the capsule 10, which is disposed near the top of the now inverted can 30, and the aperture 14 is disposed in the gaseous headspace.

At the end of the predetermined time period, the pressure within the capsule 10 equates with that outside the capsule, whereupon the roof 18 of the capsule again reverts to its natural position, opening the interior of the capsule to the standpipe 12 and the can contents . The nitrogen gas in the headspace 44 above the beer in the inverted can completes charging of the capsule 10 with gas through the aperture 14. Figure 10 shows the can 30 and capsule 10 during pasteurisation, when the capsule is open.

Although the canned beer may subsequently be stored upright, and the capsule remains open, there is no tendency for the gas under the same pressure as that in the headspace to escape from the capsule 10 until the can is opened, as by means of a tear- out tab in the seamed lid. However, when the headspace pressure is relieved by opening the can, the gas will jet out of the capsule 10 through the opening 14 at the now bottom end of the standpipe 12, bubbling up through the beer to produce a foamy head thereon, e.g., as the beer is poured out.

In the arrangement of Figures 7 to 10, the capsule is located in position near the bottom of the upright can, but this is not essential to the invention.

Figure 11 shows a finished beverage containing can wherein the capsule is located generally mid-height in the can. The same reference numerals are used in this figure as in Figures 7 to 10, together with the suffix A.

When the can is opened,- the standpipe 12A prevents beer issuing from the aperture in the capsule 10A before the gas, which gas bubbles up through the beer to impart a foamy head thereto. The extension 12B of the standpipe 12A is to limit initial insertion of the capsule.

Figure 12 shows a modified capsule for use in the can 30A of Figure 11, in which the capsule 10A is provided with a gas- permeable wall section 50. Where a suitable plastics material is employed for the wal section of the capsule body or the roof (or both) , which possesses the required permeability, no special section such as 50 is required. Gas entering the capsule 10A through the gas-permeable wall or wall section 50, eventually causes pressure balance to occur and the roof of the capsule to revert from its inwardly deflected position (attained when the can 30A is pressurised) to its natural undeflected position, thereby opening the upper end of the standpipe 12A. Beer is now able to enter the capsule 32A through the aperture 14A and standpipe 12A, increasing the pressure in the capsule until the internal gas pressure in the capsule is substantially the same as the can pressure, thereby stopping any further ingress of beer.

An advantage of the arrangement of Figure 12 is that if the ingress of gas into the capsule is sufficiently slow as to prevent the pressure within the capsule from rising fast enough to open the valve between the tube and deformable lid until after pasturisation has been completed, and the can temperature has reverted to normal room temperature, there will be little tendency for beer in the can to enter the capsule after the lid has separated from the tube end, and the capsule will be substantially filled with gas when the can is subsequently opened. This not only means that there is a large volume of gas available to jet into the beer to form the foaming head on can opening, but the lack of opportunity for beer to be driven into the capsule means that most of the beer in the can will be outside the capsule and be available for consumption by the consumer.

Claims

1. A capsule for securing within a beverage can for creating a secondary chamber therein, comprising a hollow enclosure having an underside aperture which communicates with the interior of the capsule through an upstanding tube or pipe the inner end of which is open and is situated in close proximity to a resiliently deformable wall section of the capsule, which wall section is deformable under external positive pressure so as to move towards the said open end of the tube, and cooperates therewith to form a valve at least substantially close off the end of the tube when the wall section is deformed inwardly, but when not deformed inwardly permitting fluid exchange between the inside and outside of the capsule through the aperture and the tube.

2. A capsule according to claim 1, wherein the aperture is at the lower end of the tube.

3. A capsule according to claim 1 or claim 2, wherein the deformability of the wall section of the capsule is selected so as to determine the opening and closing of the valve at the end of the internal tube so that the capsule will communicate with the contents of the can in a predetermined manner.

4. A capsule according to claim 3 , wherein the tension and deformability in the deformable wall section is selected so that the end of the tube is normally open to the interior of the capsule but a relatively small excess pressure on the outside of the capsule will tend to cause the wall section to collapse against the end of the tube and thereby seal the further ingress of liquid or gas into the interior of the capsule.

5. A capsule according to claim 3 , wherein the deformable wall section is designed so that its natural resilience tends to close off the end of the tube so that the capsule is to all intents and purposes sealed when it is located within the can and means is provided within the capsule or associated with the said wall section to move it clear of the end of the tube after the can has been filled with beverage and pressurised.

6. A capsule according to claim 5, wherein the wall section has formed thereon a buoyant member which will cause the wall section to be displaced away from the tube end as a result of its buoyancy after the can has been filled with liquid.

7. A capsule according to any of claims 1 to 5, wherein the capsule includes a volume of a liquid having a boiling temperature which will be equalled or exceeded when the can is subsequently heated during pasteurisation, so that the vapour pressure within the capsule will approach or equal the gas pressure within the can, to cause the wall section to separate from the end of the tube and open the valve to thereby establish communication between the can and the interior of the capsule and permit the two pressures to equalise.

8. A capsule according to any of claims 1 to 7, wherein the wall section is designed to be spaced from the open end of the tube when no net force due to gas/liquid pressure is exerted thereon, but is displaceable into contact with the open end of the tube inside the capsule as soon as the exterior of the capsule is subjected to a pressure greater than a given threshold, and the sealing between the wall section and the open end of the tube is designed to leak fluid into the capsule in a controlled manner, so that the external pressure acting on the capsule slowly becomes balanced by the internal pressure building up within the capsule due to the controlled leakage.

9. A capsule according to any of claims 1 to 8, wherein the controlled leak is adapted to permit leakage of gas in preference to liquid.

10. A capsule according to any of claims 1 to 9, wherein the deformable wall section comprises part of a lid fitted to the capsule.

11. A capsule according to any of claims 1 to 10, which includes a downwardly extending leg or foot for locating the capsule at a predetermined height above the base of a can into which it is to be fitted.

12. A sealed beverage can, and a capsule according to any of claims 1 to 11 when fitted therein at a predetermined position and charged with gas from within the can, for issuing from the capsule through the said aperture, when the can is opened, to form or assist in forming a foamy head on the beverage.

13. A can according to claim 12, wherein the beverage in the can is gasified with nitrogen or argon.

14. A can according to claim 12 or 13, wherein the capsule is fitted at or near the middle of the height of the upright can.

15. A can according to claim 12 or 13, wherein the capsule is fitted at or near the bottom of the upright non-inverted can.

16. A can according to claim 15, having a rim seamed lid.

17. A can according to claim 16, wherein the can, after the lid has been seamed, is inverted at least for checking the lid seal, whereupon the said aperture is located in the gaseous headspace in the inverted can, so that after the deformable wall section moves out of contact with the tube end and it is gas which enters the capsule.

18. A method of packaging a beverage in a can when fitted with a capsule according to any of claims 1 to 11, wherein the can is filled with beverage under pressure prior to application of a lid, and the pressurisation applied during filling initially closes the valve formed between the tube and the deformable capsule wall section.

19. A method according to claim 18, wherein the can is pasteurised under elevated temperature after the application of the lid to close the can.

20. A capsule for use in a can as claimed in the method of claim 19, wherein the capsule carries a temperature and/or pressure sensitive device which when activated in response to elevated temperature and/or pressure in the can during pasteurisation, allows the interior of the capsule to communicate with the contents of the can to permit equalisation of the pressures in the capsule and the can.

21. A capsule according to claim 20, wherein the pressure and/or temperature sensitive device is associated with or forms part of the valve formed between the tube and the deformable wall section of the capsule and which opens in response to the over pressure or over temperature condition.

22. A capsule according to claim 20, wherein the pressure or temperature sensitive device is separate from the valve formed between the tube and the capsule wall .

23. A capsule for use in the method of claim 18 or 19, in which the capsule wall includes a gas-permeable section, so that after the application of the lid and the internal pressurisation of the can, gas, in preference to liquid, permeates therethrough so as to equalise the pressures inside and outside the capsule.

24. A capsule according to any of claims 20 to 23, wherein, after equalisation so that the interior of the capsule is at a pressure substantially equal to that in the can, the valve formed between the end of the tube and the capsule wall opens, and thereafter remains open.

25. A capsule according to claim 23 or 24, when fitted in a can so that it always remains submerged in the liquid independently of can orientation, whereby gas dissolved in the liquid permeates into the capsule to produce the said equilisation of pressures.

26. A can when fitted with a capsule as claimed in any of claims 20 to 25, wherein the capsule incorporates a liquid trap which enables substantially only gas to be expelled from the capsule when the can is opened.

27. A can according to claim 26, wherein the liquid trap is formed at least in part by the upstanding tube within the capsule.

28. A method of producing a foamy head on a beverage in a sealed can, when the can is opened, according to which there is fitted at or near the base of the can a capsule having in association therewith a tube extending through the capsule from the exterior thereof, where the tube is apertured, to a point in the capsule close to a pressure deformable wall section of the capsule, which wall section forms with the tube a valve by movement of the wall section into and out of engagement with the end of the tube, and wherein the filling and gassification of the can closes the said valve, and wherein a lid is seamed to the can after filling whereafter the can is inverted for checking the seamed lid and for pasteurisation, and while inverted the valve is opened to provide a communication between gas in a headspace in the can surrounding the capsule to allow gas to enter the capsule until the pressure in the capsule equates to that in the headspace, the said valve thereafter remaining open even when the can is re-orientated, to permit gas to escape from the capsule into the liquid in the can to form a stream of bubbles to produce the foamy head when the can is opened and the headspace pressure drops.

29. A production line for canned beverages, comprising: 1) a station at which a capsule including a valve and constructed according to any one of claims 1 to 11 or 20 to 25 is fitted in the can,

2) a station at which the can is filled with beverage under pressure so as to cause the said valve to close,

3) a station at which the beverage is gasified and a seamed lid is applied to the can,

4) a station at which the can is inverted, and

5) a station at which the beverage in the inverted can is pasteurised, and at which the said valve is opened so that a gaseous headspace in the filled can is able to communicate with the interior of the capsule through the said aperture.

30. A capsule for fitting in a can to contain a charge of gas under pressure for jetting into a beverage also under pressure contained in the can when the latter is opened, constructed arranged and adapted to operate substantially as herein described and/or with reference to and as illustrated in the accompanying drawings.

31. A beverage package containing a capsule as claimed in claim 1, substantially as herein described and/or with reference to and as illustrated in the accompanying drawings.