GB2286812A - Device for inclusion in a pressurised fluid container - Google Patents

Abstract

A device for inclusion in a pressurised fluid container for releasing a substance into the fluid in response to a depressurisation of the fluid caused by opening the container, comprises two body members which are compressible together and together define a chamber for the substance. One way motion means, such as detents adjacent holes 43 in one of the members 21 engaging with abutments 44 - 46 on legs 40 passing through the holes, permit compression of the members but prevent them moving apart. Means, such as channels adjacent a groove in the end wall 21 of one member which receives the leading portion 26 of the wall of the other member when the members are compressed, allow the substance to exit from the chamber in response to the depressurisation. <IMAGE>

Description

"Device for inclusion in a pressurised fluid container" This invention relates to pressurised fluid containers such as cans for beer and soft drinks.

A number of devices are available for insertion in beverage cans to produce a creamy head on the beverage when dispensed. Many of these rely on the device having a closed chamber containing gas, typically nitrogen, and means responsive to the pressure drop in the beverage when the can is opened to cause the gas to be ejected through a restricted orifice into the beverage to induce the formation of fine bubbles in the beverage. Typically, a pressure responsive valve is used to release the gas. An alternative approach used in a device recently marketed by the present applicants makes use of a two-part device in which the pressure drop on opening the can causes relative movement between the two parts, which movement causes tearing of a partition to allow the gas to exit the device via a plug assembly providing an accurately restricted orifice.

It will be appreciated that devices of this nature, to be commercially acceptable, must be produced in very high volumes at low cost and have a very low rate of failure or malfunction. These requirements pose severe problems of production engineering design, and the improvements of the present invention are directed towards mitigating such problems.

According to the present invention there is provided a device for inclusion in a pressurised fluid container for releasing a substance into the fluid in response to depressurisation of the fluid caused by opening the container, the device comprising first and second members which together define a chamber, and one-way motion means provided on one of said members adapted to engage the other of said members in such manner as to permit compressive movement of the members together while preventing movement apart of the members when the members have reached a predetermined compression, the members being provided with fluid control means which, in response to a predetermined decrease in pressure external to the device, defines a conduit through which fluid may exit said chamber.

Preferably the one-way motion means has means to prevent movement apart of the members in a plurality of positions of varying compression of the two members.

The one-way motion means may comprise an external arm member projecting from one of the members and engagement means disposed on the other of the members, wherein the arm member has means to prevent the disengagement of the arm member from the engagement means when the two members have attained a predetermined compressed position.

The engagement means may be in the form of an aperture and the one-way motion means is in the form of a detent disposed on the arm member.

Preferably, the one-way motion means allows compression of the two members to a first predetermined compressed position wherein the device, filled with said substances, is introduced into the container.

Preferably, a second predetermined compressed position is a position in which the members are compressed after insertion of the device into the container and filling of the container.

Preferably, a third predetermined compressed position is a position of maxium compression of the members as a result of pressurisation of the container after sealing of the container.

Leg means may be provided between the two members and on compression of the two members, said leg means engage with an inside surface of the container.

The fluid control means may be provided by a free edge of one of the members engaging over a channel in a surface of the other member such that the predetermined decrease in pressure external to the device allows the substance to pass through the channel.

Preferably, the members are in the form of nestable open ended cylinders.

Embodiments of the present invention will now be described, by way of example, with reference to the drawings, in which: Fig. 1 is an illustrative cross-sectional view through a unit in accordance with the invention in a first predetermined position of relative extension; Fig. 2 is an illustrative side sectional view of the unit of Fig. 1, in a container and in a third predetermined position of relative extension, i.e.

inwardly constrained to the maximum extent; Fig. 3 is an underneath plan view to an enlarged scale of the unit of Fig. 1 when in the position of Fig. 2; Fig. 4 is a section on the line 4.4 of Fig. 1; Fig.5 is an enlarged fragmentary section of part of the unit of Figs 1 and 2 in the position of Fig. 1; Fig. 6 is an enlarged fragmentary section of another part of the unit of Figs 1 and 2 in the position of Fig. 1; Fig. 7 is an enlarged fragmentary section of the part of the unit of Figs 1 and 2 as shown in Fig.

5 but in the position of Fig. 2; and Fig. 8 is a developed side view of part of one of the members of the unit of Figs 1 and 2.

Referring to the drawings, there is shown a unit 10 embodying all aspects of the invention which is intended for inclusion in a pressurised fluid container 11 such as a pressurised drinks container for releasing a substance, for example a pressurised gas such as nitrogen, into the fluid when the pressure in the container 11 is substantially or suddenly reduced by opening the container 11, and thereby exposing the interior of the container 11 to atmospheric pressure.

The unit 10 comprises a first member 12 having a generally hollow tubular portion 13 with generally cylindrical external and internal surfaces 14,15, respectively, and at one end 16 of the tubular portion 13, a circular chamfered leading end 17 is provided to facilitate receiving the end 16 within a second member 20 of the unit 10.

The wall of tubular portion 13 of the first member 10 is thus provided by a single thickness of material and is integrally formed with a transversely extending end wall 21 which extends transversely outwardly of the tubular portion 13. The thickness of the wall 13 increases from the leading end 16 to a maximum thickness adjacent the end wall 21.

The second member 20 also has a generally hollow tubular portion 22 of a slightly greater diameter than the tubular portion 13 of the first member 12, with generally cylindrical external and internal surfaces 23 and 24 respectively.

The tubular portion 22 is also provided by a single thickness of material.

At one end 25 of the tubular portion 22 of the second member 20, a slightly inwardly flared and chamfered leading edge part 26 is provided, as can best be seen from Fig. 5, so that a seal is provided between the leading edge part 26 of the second member 20 and the external generally cylindrical surface 14 of the first member 12 during relative telescoping of the first and second members 12,20, as hereinafter described. The edge 26 undergoes slight outward compression when the tubular portion 13 of the first member 12 is inserted into the tubular portion 22 of the second member 20 thereby affording an efficient seal within that tubular portion 13.

The second member 20 also has at its other end to leading edge 26, a transversely extending end wall 27.

The first and second members 12,20, thus provide between them a chamber C for storing substance, the volume of which is variable depending upon the relative telescoped positions of the first and second members 12,20.

In an alternative embodiment it is envisaged that the two members could be in the form of an open ended cylinder member and a plunger member which are together compressible and together define a chamber for storing a substance, the volume of which is variable depending upon the position of the plunger member within the cylinder member. The plunger and cylinder arrangement has fluid control means in the form of a valve between the edge of the plunger and the internal cylinder wall.

The internal cylinder wall can have a plurality of grooves through which the substance within the chamber can be ejected when the predetermined reduction in pressure external to the chamber takes place.

Returning to the first embodiment of the invention, the unit is provided with locating leg means comprising a plurality of flexible legs 28, three in this example, formed integrally with the end wall 27 of the second member 20. Each leg 28 is attached to the end wall 27 by a hinge part 29 and at its opposite free end 30, each leg 28 is received by a receiving formation of the first member 12, provided in the end wall 21 and comprising a pocket 21 disposed outside of the tubular slidable portion 13.

Intermediate the hinge parts 29 and the free ends 30, the legs 28 each comprise a plurality of sections 32-36 which are at least flexible relative to one another, to permit the legs 28 to deform by bulging outwards to grip the inside of the container 11 in which the unit 10 is received in use to locate the unit therein as shown in Fig. 2.

The unit is also provided with restraining leg means comprising a plurality of flexible legs 40, three in this example, formed integrally with the end wall 27 of the second member 20.

The legs 40 of the restraining leg means are disposed circumferentially alternately with the legs 28 of the locating leg means. The leg 28, 40 of both leg means are equi-angularly disposed and hence each adjacent leg is angularly separated by 60 .

Each leg 40 is attached to the end wall 27 by a connecting part 41 and at its opposite, free, end 42 extends through an aperture 43 provided in the end wall 21 circumferentially between the pockets 31.

Each leg 40 is provided with longitudinally spaced first, second and third abutments 44-46 respectively.

Each abutment comprises an abutment surface 47 which extends perpendicular to a longitudinal axis X-X of the unit and an inclined surface 48.

As best shown in Fig. 5, the free end 42 of each leg 40 extends through the aperture 43 and, in a first predetermined position shown in Figs 1 and 5, the first abutment surface 47 is engaged by a detent element 50 which is connected to adjacent positions 51 of the end wall 21 by bridge portions 52 thereby permitting deflection of a free end part 53 of the detent element 50 as a result of engagement with the inclined surface 48 to a passage of the leg 40 through the opening 43 and snap engagement of the free end 53 with the abutment surface 47.

The free ends 42 of the restraining legs 40 are passed through the apertures 43 so that the detent elements 50 engage with the first abutment surfaces 47 of the first abutment means so as to restrain the members 12,20 in a first predetermined extended position A groove 60 is provided in the end wall 21 around and adjacent to the tubular portion 13 of the first member 12, radially inside the pockets 31 and apertures 43.

The groove 60 comprises at least at one, but preferably at a plurality of discrete positions around the slidable position 13, a channel 61. In this example, four such channel formations 61 are provided. Also, the groove 60, at the bottom is of a slightly wedge configuration. Consequently, as the first and second members 12 and 20 are contracted together to their full extent, as seen in Fig. 2, the leading edge 26 will be urged away from the wall 13 of the slidable portion, so that a small gap 62 is provided between the external surface 14 of wall 22 around substantially the entire periphery of the wall 13. Thus passages will be provided along the gap 62, and past the leading edge 26 of the wall 22, through the channels 61.

The unit is orientated so that the end wall 22 of the second member 20 in use, lies adjacent the bottom wall 65 of the container 11.

The bottom wall 65 of the container 11 has a domed or convex configuration so as to add rigidity to the container 11 which is only a thin walled metal can.

The undersurface 66 of the end wall 27 of the unit 10 has a central region 67 which is of a concave configuration corresponding closely to the convex configuration bottom wall 65 of the container 11. Thus the end wall 27 sits substantially with the central region 67 of the undersurface 66 in contact with the bottom wall 65 of the container 11.

In use, the first and second members 10,20 are provided initially as separate components. The interiors of the hollow tubular portions 13 and 22 of the respective first and second members 12,20 are purged of air or the like in conventional manner, for example under the action of a pressurised nitrogen gas jet.

Immediately after the purging, whilst the interiors of the members 12 and 20 are still occupied by the nitrogen gas which, in the present example, is at atmospheric pressure but which may be above atmospheric pressure, the members are brought together to the condition shown in Fig. 1 in which the leading edge 26 of the second member 20 is forced outwardly to provide a seal with the external surface 14 of the tubular portion 13 of the first member 12. The free ends 30 of the locating legs 28 are received in the pockets 31 of the first member 12. The free ends 42 of the restraining legs 40 are passed through the apertures 43 until the free ends 53 of the detent elements 50 can move into position for engagement with abutment surfaces 47 of the first abutment means 48 so that extension of the members 12,20 beyond a first predetermined position is prevented.

At this stage, the chamber C is at a maximum volume and thus contains nitrogen gas at atmospheric or substantially atmospheric pressure or at such other high pressure as desired. In the latter case, for example, by assembling the members into the first predetermined position in an environment of nitrogen at a desired pressure above atmospheric pressure.

Generally however it is preferred that the pressure is atmospheric pressure or substantially atmospheric pressure. The thus assembled together members which are restrained from extension from the first predetermined position may then be stored and/or transported to a site where they are introduced into containers 11 without loss or at least significant loss of gas.

When a unit is introduced into the container 11, it may be acted upon, for example, by a suitable mechanically operated plunger acting upon the end wall 21 to position the end wall 27 on the bottom wall 65 of the container 11, as shown in Fig. 2 and as previously described and to cause the members 12,20 to be contracted, i.e. moved telescopically together until the second abutment means 46 are moved past the detent elements 50. Such contraction will increase the pressure of the gas in the chamber C above the previous pressure, and in particular in the present example, above atmospheric pressure and there will be a tendency for the members to be relatively extended until such movement is arrested in a second predetermined position of extension as a result of engagement of the detent elements 50 with the abutment surfaces 47 of the second abutment means.Accordingly the displaced volume of the unit is accurately fixed so as to be constant for each unit.

In the present example, the container 11 is a beverage can such as a beer can, but the container 11 may be any other suitable container such as a bottle made of glass or plastics material, with the unit 10 and the locating legs 28 being appropriately dimensioned to suit the internal configuration of the container 11, the desired volume of substance to be dispensed from the unit 10.

When the assembled unit 10 has been inserted into an empty fluid container 11, and telescopically compressed to the second predetermined position so as to achieve an initial compression of the nitrogen gas in the interior chamber C of the unit 10, the interior of the container 11 into which the unit 10 has been inserted is purged of air or the like, for example under the action of a jet of compressed nitrogen gas, and the fluid to be stored in the container e.g. beer is then admitted into the container 11 and the container sealed in conventional manner. Because the displacement volume of the unit is constant, simply by filling the container to the brim a known and fixed volume of beer is put into each container without the need to meter the beer.

The container 11 thus containing the unit 10 and the fluid which is pressurised by virtue of containing nitrogen, carbon dioxide or the like in solution, is subjected to a pasteurising operation involving substantial heating of the container 11, the result of which is that any residual nitrogen purging gas in the container 11 or gases that have dissolved in the fluid in the container 11, for example beverage, become heated and thereby increase the pressure within the container 11. The effect of this pressure increase is to force the first and second members 12 and 20 telescopically to contract further so that the members 12,20 may be restrained in a third predetermined position of extension by engagement of the detent elements 50 with the abutment surfaces 47 of the third abutment means 46.In this position, the leading edge 26 of the tubular portion 22 of the second element is received in the groove 60.

The final compression of the members 12,20 also causes the locating legs 28 to occupy the positions shown in Fig. 2 where at least the sections 34 of the legs 28, engage the inside surface of the side wall of the container 11, and as a result, the unit 10 is securely held in the container 11, preferably adjacent the bottom wall 65 thereof. Also, the change in the volume of the unit between the second and third positions creates a head space in the container above the fluid therein.

At this stage, the pressure of the gas in chamber C will be generally the same as in the container 11.

This condition will be maintained during storage of the container.

When the container 11 is opened so as to expose the initially pressurised fluid content of the container to atmospheric pressure, the pressure of the gas within the chamber C of the unit, is sufficiently greater than atmospheric pressure, for gas to be forced from the chamber C into the gap 62 between the tubular formations 13 and 22 of the first and second members 12,20 downwardly towards the leading edge 26 of the second member 20 and past the leading edge 26 of the second member 20 through the channels 61 into the fluid contents of the can. The number of and dimensions of the channel formations 61 are carefully arranged to release the gas from chamber C at a controlled rate.

The release of the compressed nitrogen into the fluid, such as beverage, has the effect of causing the formation of a head or "frothing" of the beverage.

If desired, the abutment surface 47 of the third abutment means may be disposed so that after pasteurisation a small gap is provided between the free end 53 of the detent element 50 and the surface 47.

Accordingly upon the substantial or sudden release of pressure within the container 11, the first and second members 12 and 20 are permitted to move apart from the fully compressed telescopic position a small amount, to facilitate the escape of pressurised gas from the chamber C into the fluid content of the container 11.

Of course if desired, substances other than pressurised nitrogen gas may be stored in the unit 10, and the container 11 may comprise another fluid to beverage or beer as described in this specification.

The longitudinal position of the abutments means may be varied as desired for any particular application as may other dimensions, for example to vary the displacement volume of the unit.

The features disclosed in the foregoing description, or the accompanying drawings, expressed in their specific forms or in the terms or means for performing the desired function, or a method or process for attaining the disclosed result, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims (11)

1. Claims

   1A device for inclusion in a pressurised fluid container for releasing a substance into the fluid in response to depressurisation of the fluid caused by opening the container, the device comprising first and second members which together define a chamber, and one-way motion means provided on one of said members adapted to engage the other of said members in such a manner as to permit compressive movement of the members together while preventing movement apart of the members when the members have reached a predetermined compressed position, the members being provided with fluid control means which, in response to a predetermined decrease in pressure external to the device, defines a conduit through which fluid exits said chamber.
2. 2 A device as claimed in Claim 1, wherein the one way motion means has means to prevent movement apart of the members in a plurality of positions of varying compression of the two members.
3. 3 A device as claimed in Claim 1 or Claim 2, wherein the one-way motion means comprises an external arm member projecting from one of the members and engagement means disposed on the other of the members, wherein the arm member has means to prevent the disengagement of the arm member from the engagement means when the two members have attained a predetermined compressed position.
4. 4 A device as claimed in Claim 3, wherein the engagement means is in the form of an aperture and the one-way motion means is in the form of a detent disposed on the arm member.
5. 5 A device as claimed in any one of the preceding Claims, wherein the one-way motion means allows compression of the two members to a first predetermined compressed position wherein the device, filled with said substance, is introduced into the container.
6. 6 A device as claimed in any one of the preceding Claims, wherein a second predetermined compressed position is a position in which the members are compressed after insertion of the device into the container and filling of the container.
7. 7 A device as claimed in any one of the preceding Claims, wherein a third predetermined compressed position is a position of maxium compression of the members as a result of pressurisation of the container after sealing of the container.
8. 8 A device as claimed in any one of the preceding Claims, wherein leg means are provided between the two members and on compression of the two members, said leg means engage with an inside surface of the container.
9. 9 A device as claimed in any one of the preceding Claims, wherein the fluid control means is provided by a free edge of one of the members engaging over a channel in a surface of the other member such that the predetermined decrease in pressure external to the device allows the substance to pass through the channel.
10. 10 A device as claimed in any one of the preceding Claims, wherein the members are in the form of nestable open ended cylinders.
11. 11 A device substantially as herein before described with reference to the drawings.