This invention relates to drinks containers of the kind in which first and second chambers defined within the container are separated by a partition wall and means is provided to form or open a passage means in the partition wall to provide fluid communication between the chambers.

The present invention provides inventive modifications and improvements upon the inventions set forth in our patent applications no. GB 88.25420 and 88.25421, and in particular various aspects of the present invention are concerned with the manner in which the passage means is formed or opened in the partition wall.

Nitrogen is valuable in promoting a good head on beer. When the beer is sold ^' in cans there is difficulty in introducing nitrogen into the beer, because nitrogen is relatively insoluble in beer as compared with the solubility of carbon dioxide. It has been proposed to provide a plastics nitrogen-containing vessel inside a can of stout at the bottom, with a small hole through which the pressurised nitrogen escapes when the can is opened. Whilst that proposal is feasible, it requires the manufacture of the special vessel which must then be retained in place at the bottom of the can in some way.

According to one aspect of the invention set forth in application no. 88.25420, a drinks container assembly comprises a cylindrical wall, first and second end walls at opposed ends of the container assembly, and a partition wall extending substantially parallel to the end walls and being positioned axially closer to said first end wall to provide a gas reservoir between the partition wall and the first end wall, the second end wall comprising an area which is adapted to provide a normally closed pouring opening to enable drink to be poured from the main chamber defined between the second end wall and the partition wall, and passage-producing means arranged to enable a passage means to be formed or opened in the partition wall

just prior to pouring of the drink to provide restricted communication between the gas reservoir and the main chamber to enable gas under pressure in the reservoir to pass into drink in the main chamber. Such a drinks container assembly will hereinafter be referred to as ^' a drinks container assembly of the first type'.

In the embodiment, illustrated in no. 88.25420 the passage-producing means comprises a rigid, fluted spike carried by a cup-shaped member attached to the bottom of a more or less conventional drinks can. On urging of the cup member relative to the can, such that the cup member slides on the outside wall of the can, the spike pierces the can base, and the passages defined between the flutes of the spike permit gas in the cup member to enter the can in a controlled manner.

Patent application no. 88.24521 relates to a drinks container assembly suitable for dispensing a mixed drink, such as whisky and soda, or gin and tonic, comprising a mixture of a spirit and a mixer drink.

Such drinks are usually made up by taking a measure of spirits and adding a larger volume of the mixer drink, which has been separately stored, often in a can. It is not generally satisfactory to store such drinks in a pre-mixed condition.

According to the invention set forth in application no. 88.25421 a drinks container assembly comprises a substantially cylindrical wall, first and second end walls at opposed ends of the container, and a partition wall extending substantially parallel to the end walls and being positioned axially closer to the first end wall to define a spirits chamber between the first end wall and the partition, and a mixer drink chamber between the second end wall and the partition, one of the end walls comprising an area which is adapted to provide a pouring opening, and means operable from the exterior of the can for producing or opening a passage means in the partition wall to provide fluid communication between the chambers

and thereby permit both the spirits and the mixer drink to be poured through the pouring opening following operation of said means and opening of the pouring opening. Such a drinks container assembly will hereinafter be referred to as 'a drinks container of the second type ^' .

In the embodiment of Figure 1 of no. 88.25421 the means for producing the passage means in the partition is a sharpened punch which is carried by the base of the container assembly, the base being formed with coaxial corrugations to enable the centre of the base to be pressed axially relative to the fixed margin of the base, in the manner of barometer bellows, so as not to provide any substantial resistance to axial movement of the punch.

One aspect of the present invention is concerned with an arrangement for controlling the axial displacement of a passage-producing means in a drinks container assembly of the first type.

According to the first aspect of the present invention in a drinks container assembly of the first type, the passage-producing means comprises a punch located in the gas reservoir and which is arranged to be urged towards the partition wall on the application of an external force to the central region of the first end wall, the first end wall being shaped and arranged such that once the first end wall has been pressed inwardly of the container assembly to a deflected position in which the punch has formed or opened the passage means, the central region of the first end wall is held in the deflected position by the rigidity of the material of the first end wall .

Whilst it may be arranged that the first end wall is permanently deformed, in a substantially non-resil ent manner, by the user pressing inwardly on the central region of the first end wall, preferably the first end wall is shaped and arranged such that the first end wall 'pops' from a substantially convex-outwards configuration to a substantially concave-outwards configuration when

sufficient force is applied to said central region.

The popping action can help to displace the punch in a relatively controlled manner which is repeatable from one container assembly to another identical container assembly.

The first end .wall may be of substantially part-spherical, convex-outwards shape prior to popping, whereafter the first end wall assumes a part-spherical concave-outwards shape.

In an alternative construction the first end wall comprises a central disc portion integral with a radially outer portion of frusto-conical shape, of large cone angle, the frusto-conical outer portion inverting its shape on popping.

Once the first end wall has been popped, the plunger will be held in a fully-displaced, inward position by the first end wall.

The plunger may be a piercing or non-piercing plunger depending on the application, and the plunger may or may not be secured to the first end wall .

A second aspect of the present invention is concerned with a novel form of piercing plunger to constitute the passage-producing means.

According to the second aspect of the invention in a drinks container assembly of the first type, or in a drinks container assembly of the second type, the passage-producing means comprises a piercing plunger, the plunger being formed with a bore which extends from a piercing tip of the plunger to a communication port displaced from the piercing tip, the arrangement being such that when the plunger is urged against the partition wall the piercing tip pierces the partition wall, and the bore in the plunger provides the passage means which then provides communication between opposite sides of the partition wall.

The plunger is therefore akin to a hypodermic needle.

The plunger bore conveniently comprises an axially-extending hole, and a radially-extending hole remote from the piercing tip and leading into the axially-extending hole.

The plunger is preferably of tapered external shape such that it jams in the hole which it creates in the partition wall.

Another advantage of a tapered piercing plunger over a parallel-sided piercing plunger, when the plunger is secured to the first end wall, is that whereas the latter may produce a non-round hole in the partition wall if the plunger is not centrally positioned, this should not happen with a tapered plunger.

A third aspect of the present invention is concerned with a novel plunger arrangement which may be used as the passage-producing means in drinks container assemblies of either the first or second types.

According to the third aspect of the invention in a drinks container assembly of the first type, or in a drinks container assembly of the second type, the passage-producing means comprises a plunger having a substantially parallel-sided first plunger portion which normally extends through an opening in the partition wall so as to seal the opening, and a second plunger portion so shaped that when the plunger is displaced inwardly of the container assembly from the normal position, to bring the second plunger portion into the partition opening, the second plunger portion defines with the partition wall said passage means extending through the partition wal1.

In one embodiment in accordance with the third aspect, the second plunger portion is tapered and provided with a series of longitudinally-extending flutes, the taper providing an increased diameter of the second plunger portion in the direction away from the first portion. When that plunger is urged inwardly of the

container assembly, the fluted and tapered second portion is urged partially through the partition opening, thereby enlarging the partition opening and defining a series of passages of predetermined dimension through the partition wall provided by the spaces between the flutes. This embodiment is particularly suitable for use with beer in a container assembly of the first type, since the passages of controlled size are suitable for controlling the flow of gas into beer.

In a second embodiment in accordance with third aspect, the second plunger portion is of substantially reduced transverse dimensions compared with the transverse dimensions of the first plunger portion, such that when the plunger is pushed inwardly of the container assembly the second plunger portion only partially fills the partition opening, whereby a passage of substantial size is provided in said partition opening. This embodiment is particularly suitable as a container assembly of the second type.

The plunger of the assembly in accordance with the third aspect may e secured at its outer end to the first end wall but preferably the plunger is not secured to the first end wall, the plunger being located in its normal position by an interference fit between the first portion of the plunger and the partition wall.

This arrangement has the advantage that the manufacturing step of securing the plunger to the first end wall is avoided.

When the plunger is unattached to the first end wall it is preferred to provide a clearance between the free end of the second portion of the plunger, in its normal position, and the undisplaced first end wall. This can help to avoid inadvertent operation of the plunger. Also, when the first end wall is shaped to be popped in accordance with the first aspect, the popping action can be assisted by such clearance, since the first end wall can be pushing to the position at which it pops without incurring any resistance from the plunger. This should help to provide a repeatable plunger action.

When the second portion of the plunger is of reduced diameter compared with the first portion, the free end of the second portion may be provided with a suitable radial projection to prevent the plunger from passing right through said opening. This is desirable for a plunger of small dimensions which might otherwise fall through the pouring opening.

A fourth aspect of the present invention is concerned with a method of charging a drinks container.

According to the fourth aspect of the invention, we provide a method of charging a drinks container of the kind comprising a cylindrical wall, first and second end walls at opposed first and second ends of the container, the second end wall being an independently-formed member, a partition wall extending substantially parallel to the end walls and being positioned axially closer to said first end wall to provide a first chamber of small volume between the partition wall and the first end wall, and a second chamber of larger volume between the partition wall and the second end wall, one of the end walls (preferably the second end wall) comprising an area which is adapted to provide an openable pouring opening, the partition wall being formed with an opening which is normally sealed by a closure means fast with the partition wall, the method comprising the steps of taking the container with the second end open, charging the first chamber with gas or with liquid and gas, the gas being under super- atmospheric pressure, assembling the closure means to the partition wall by inserting the closure means through the open second end, thereby to seal the partition opening, charging the second chamber with a liquid or with gas and a liquid, and attaching the second end wall to the cylindrical wall to seal the second chamber.

Thus the first chamber is pressurised prior to assembling the closure means to the partition wall, and the closure means is readily inserted through the second end of the container.

The closure means may be a plug or plunger which is an interference fit in the partition opening. Alternatively the margin of the partition around the partition opening may be formed with a lip, and the closure means can then be a cap which is secured on the lip.

The method in accordance with the fourth aspect is applicable both to pressurised beer containers and to containers for mixed drinks.

The partition wall may, according to a fifth aspect of the present invention, be so shaped and arranged that, instead of charging the first chamber under super-atmospheric pressure, the first chamber is pressurised after filling of the first chamber, and after the closure means has been secured in place, by applying a force to the partition wall to deflect it permanently towards the first end wall.

The partition wall could be shaped and arranged to pop, as discussed hereinbefore in relation to the popping of the first end wall in accordance with the first aspect.

According to a sixth aspect of the present invention a drinks container assembly comprises a partition wall dividing the interior of a drinks container into first and second chambers of smaller and larger volume respectively, the partition wall being formed with an opening which is normally closed by a closure member, the co-operation between the closure member and the partition wall, and the pressure of the contents in the first chamber, being such that when a pouring opening is made in the container to vent the second chamber, the pressure in the first chamber is sufficient to unseat the closure member to permit fluid (gas and/or liquid) from the first chamber to enter the second chamber.

Thus it may be arranged that the closure member becomes completely detached from the partition wall. This would generally be acceptable when the closure member is large enough, such as a \ ^" diameter disc, not to pass through the pouring opening.

The closure means can therefore be arranged to unseal itself when the container is opened for pouring, without the need for the user to apply a force to open the closure means.

As well as using such a pressure-displaceable closure means in a container for pressurised beer, the arrangement may be used in a mixed drink container in which said first chamber provides a spirits chamber, and said second chamber provides a mixer drink chamber. The spirits chamber would then need to contain in addition to the spirits some gas under pressure, for example one-third of the volume of the first chamber could be filled by gas under super-atmospheric pressure, two-thirds being filled by spirits.

The container may have more than two chambers, adjacent chambers being sealed by a respective pressure-displaceable closure means. i

Some embodiments of the invention will now be briefly described, by way of example only, with reference to the accompanying schematic drawings, in which:

Figure 1 is a vertical cross-section of a beer can having a poppable base, the initial position of the base being shown in full outline, and the popped position being shown by discontinuous lines,

Figure 2 is a cross-section of a similar can but showing a different configuration of base,

Figure 3 is a vertical sectional partial view of a modification of the can of Figure 2,

Figure 4 i s a vertical cross-section of a beer can simil ar to that of Fi gure 1 but incorporati ng a pl unger whi ch is an interference fit i n a hol e i n the di aphragm of the can, the pl unger being shown 1n its normal condition , prior to popping of the can base, and

Figure 5 is a vertical cross-sectional partial view of a plunger which is a modification of that shown in Figure 4, but for use in a mixed-drink container.

Figure 1 shows a drinks can which is particularly, but not exclusively, suitable for containing stout. The can 1 has a substantially conventional external appearance, comprising a deep-drawn aluminium alloy side wall 2, a conventional top 3 provided with a ring-pull member 4 attached to an openable portion of the top 3, to enable a pouring opening to be provided on operation of the ring-pull 4 in the conventional way.

A partition wall 5 is provided in the can to define a gas chamber 6 between the wall 5 and the can base 7. A piercing plunger 8 is carried by the centre of the base 7 and its tip 9 is normally spaced from the partition wall 5.

Base 7 has its margin 10 swaged to the lower margin of the side wall 2 which, in this example, is conveniently integral with a skirt 11 on partition wall 5.

The central region of base 7 is of substantially part-spherical shape of a radius which permits popping of the base by the application of thumb pressure to the centre of base 7. The popped position is indicated at 7 . The popping of the base will result in the plunger tip 9 piercing the partition wall, and then jamming in the partition wall 5. The tapered portion 12 is provided with a series of circumferentially-spaced longitudinal flutes, not shown, to define passages therebetween which provide restricted communication between the chamber 6 and the main chamber 13.

In this embodiment chamber 6 contains pressurised gas, such as nitrogen, for initiating bubble development in the stout 13, which contains dissolved carbon dioxide. Thus, ring-pull 4 is operated to open the pouring opening, and base 7 is popped by the user to initiate bubble formation in the stout.

The initial curvature of base 7, and its initial thickness and resilience, are chosen such that, once popped, the base 7 remains in the displaced position.

The tapered shape of the plunger 8 provides for firm jamming of the plunger 8 in the partition wall. Also, the tapered shape helps to avoid the production of an elongated hole in the partition wall 5 in the event that the plunger 8 is not positioned precisely centrally of the base 7 and, consequently, does not move precisely axially during popping.

In Figure 2 parts corresponding to those of the container of Figure 1 have been given corresponding reference numerals.

In Figure 2 the base 7, rather than being of part-spherical shape, comprises a central flat portion 14 and a frusto-conical portion 15 of 1 arge cone angle.

Figure 3 shows a piercing plunger 8 having an axial bore 16 communicating with a cross hole 17. When the base 7 is pushed to urge the sharpened tip 9 of the plunger through the partition 5, the bore 16 and cross hole 17 provide a passage of predetermined dimensions connecting chambers 6 and 13.

Figure 4 shows a further container of similar construction to that of Figure 1 , and corresponding parts have been given corresponding reference numbers.

In the arrangement of Figure 4 the upper end of the plunger 8 is an interference fit in a central hole in the partition 5 to seal said hole. An intermediate portion 18 of the plunger, of substantially the same external diameter as the upper end, is formed with a series of circumferentially-spaced longitudinal flutes 18 such that, when the base 7 is popped, the fluted portion bridges the partition 5, whereby the spaces between the flutes provide restricted communication between chambers 6 and 13.

Figure 5 shows a yet further plunger 8, which is suitable for a mixed drink container, in which chamber 6 contains spirits and main chamber 13 contains a mixer drink. The plunger 8 has an enlarged head 19 and a reduced diameter lower end 20, the head 19 being an interference fit in a central hole in diaphragm 19 to seal the hole, and to hold the plunger 8 in position, in readiness for operation.

When the base 7 is popped, the reduced portion 20 is brought into the hole, and an annular passage of relatively large dimensions will thereby be provided around portion 20 to enable spirits from chamber 6 to enter the main chamber 13. Pin 21 prevents the plunger 8 from falling through the pouring opening of the container.