GB2322614A

GB2322614A - Foam-Producing Insert

Info

Publication number: GB2322614A
Application number: GB9704132A
Authority: GB
Inventors: Karl Mondszein
Original assignee: Lawson Mardon USA Inc
Current assignee: Amcor Specialty Cartons Americas LLC
Priority date: 1997-02-27
Filing date: 1997-02-27
Publication date: 1998-09-02
Also published as: EP1007441A1; JP2000512958A; WO1998038111A1; AU6302298A; CN1258258A; GB9704132D0

Abstract

A foam-producing insert for a pressurised beverage container comprises separate inlet 16 and outlet 37 passages and a chamber 50 for containing gas. The inlet passage communicates with the headspace and the outlet passage communicates with the liquid. The chamber communicates with both passages via a thin gap 42. The inlet passage has greater resistance to gas flow than the outlet passage, preferably by being longer. During pressurisation of the container, the chamber is filled with gas through the inlet passage, rather than with liquid via the outlet passage, due to the liquid having a higher viscosity than the gas. On opening the container, the pressure within it is released, and gas is jetted out of the insert via the outlet passage in preference to the inlet passage, due to the greater resistance of the inlet passage. Preferably, the insert includes a tube 14 extending into the chamber, with the inlet passage provided at its inner end wall 15. The insert may comprise a cup-shaped portion 34 surrounding the outlet that receives the end of the tube, with the thin gap formed in between. As the gap may be convergent toward the outlet, a venturi effect may be produced, thus increasing the jetting power. The insert may float and be self-righting, and may comprise two mouldings 10, 30 snap-fitted together.

Description

LIQUID-FOAMING INSERT The present invention relates to a foaming insert for containing a gas inside a pressurised container of liquid, such that when the container is opened, the gas is jetted from the insert to cause foaming of the liquid.

Such inserts are useful, in particular, for beverages containing dissolved gas and especially for beer, to form a head on the beer.

Inserts for this purpose are disclosed in W095/22049; W095/04689; W094/ 16966; GB-A-2283792 and GB-A-2280887.

GB-A-2280887 discloses an insert, which floats on the liquid in the pressurised container with a closed jetting orifice immersed in the liquid and a closed charging orifice in the headspace above the liquid. The orifices are closed by one-way valves.

The charging orifice valve opens when external pressure exceeds the internal pressure, so that gas from the headspace can enter the insert from the pressurised container. The valve closes when equilibrium between the insert and the headspace is reached.

The jetting orifice valve opens when the internal pressure exceeds the external pressure, so that this valve remains closed during charging.

When the container is opened, pressure is released, so that this valve is caused to open to jet gas into the liquid.

The insert comprises two moulded plastics shells, which snap fit together, each shell having a central aperture. Each aperture receives an elastomeric, duck-bill type valve, fitted into the aperture and defining the respective orifices.

The insert is simple to make, except for the need to provide and fit the duck-bill valves. This adds substantially to the cost and there is also a risk of the valves becoming detached, or failing to operate properly.

The present invention overcomes this problem by avoiding the necessity for valves to be provided.

In accordance with this invention, there is provided an insert having a body defining a chamber for containing gas and usable in a pressurised liquid container, such that when the container is opened the gas escapes from the insert to cause foaming of the liquid, the insert comprising a gas inlet passage to allow gas to enter the insert from a headspace in the container and a gas outlet passage to allow gas to be jetted from the insert into the liquid in the container, the inlet and outlet passages being provided in respective wall formations, a gap being defined between the formations and providing communication between the chamber and both the inlet and the outlet passages, whereby in use, lower viscosity gas from the headspace enters the gap and hence the chamber through the inlet passage in preference to higher viscosity liquid entering the outlet passage, and wherein the inlet passage provides greater resistance to passage of gas then the outlet passage, so that, on release of the pressure in the container, gas is preferentially jetted through the outlet passage.

The insert is preferably designed to float on the liquid in a container, but it may be provided with projections, which engage the sides of the container, to secure the insert in position.

An insert according to the present invention will now be described in further detail with reference to the accompanying figures, in which: Fig 1 shows a cross-sectional view of an assembled insert according to the invention; and Fig 2 shows a cross-sectional view of a container containing a liquid and the insert of Fig 1.

Referring to Fig 1, the insert comprises an upper moulding 10 and a lower moulding 30, each roughly of hemispherical form, although they may be elongate. Each one-piece moulding 10,30 is injection moulded from plastics, such as polypropylene. The peripheral edge of the upper moulding 10 has a shaped, peripheral flange 13 and this snap fits into a corresponding peripheral recess 33 formed in the edge of the lower moulding 30, so as to form a generally spherical housing with a flattened top 40 and flattened bottom 41. Alternative means of connection, e.g.

gluing or heat bonding of the mouldings 10,30 may, however, be used.

When connected together, the mouldings 10,30 form a chamber 50 for containing a gas. The upper moulding 10 has a central, generally cylindrical tube 14 extending axially from the top 40 of the moulding 10 into the chamber 50.

The tube 14 is slightly frustoconical, with its wall converging towards the interior of the housing. The tube 14 terminates in an end portion 15 having an end wall 15a. The end wall has a flat surface 12 external of the tube 14. The end wall has an axial, elongate, inlet passage 16 extending therethrough.

The lower moulding 30 has an external recess 31 in the bottom 41, the end of the recess being defined by a generally annular wall 36 projecting into the recess 31 and closed by an end wall 38. this forms a cup-shaped formation 34 in the interior of the chamber 50. The cupshaped formation 34 conforms to and receives the end portion 15 of the tube 14 of the upper moulding 10. The bottom surface 35 of the cupshaped formation 34 is located adjacent to, but spaced from, the end surface 12 of the tube. The bottom wall 38 has an outlet passage 37 extending through it and axially aligned with the inlet passage 16 in the end wall 15a of the tube 14. The outlet passage 37 is substantially shorter than the inlet passage 16.

A thin gap 42 is defined between the peripheral exterior of the end portion 15 of the tube and the peripheral interior of the cup-shaped formation 34. The gap communicates the chamber 50 with the inlet passages 16,37.

The end portion 15 of the tube has a more pronounced taper than the rest of the tube and the interior peripheral surface of the annular wall 36 is correspondingly frustoconical, so that the gap 42 converges on the space 43 between the two passages 16,37. The side wall 44 of the space 43 is also shaped frustoconically and converges on the outlet passage 37.

In one embodiment, the inlet passage 16 and the outlet passage 37 are 3mm in diameter. The narrow gap 42 is about 0.5mm in depth. The inlet passage 16 is at least twice the length of the outlet passage 37, the length of the outlet passage preferably between less than imam.

The inlet and outlet passages (16,37) may be otherwise differently formed to provide greater resistance to gas passage through the inlet passage (16).

The insert is designed to float on liquid and is self-righting due to its shape and because the lower moulding 30 is made heavier than the upper moulding 10.

It is envisaged that the inlet and outlet passages 16,37 need not be located on the axis of the insert, but may be offset from the axis.

In use, the insert is inserted in a container of liquid, such as a can of beer, prior to sealing and pressurising the container. Such a sealed container 60 is shown in Fig 2, with the insert 100 floating on the liquid 61. The inlet passage 16 is open, via the tube 14, to the headspace 62, whereas the outlet passage 37 is open to and immersed in the liquid 61.

Gas enters the insert through the tube 14 and the inlet passage 16 from the headspace 62, due to the lower pressure in the chamber 50. The gas in the inlet passage 16 opposes the liquid adjacent the outlet passage 37 and primarily, gas enters the chamber 50 through the gap 42, until equalisation of pressure between the chamber 50 and the interior of the container is achieved. The gas preferentially enters the chamber over the liquid, due to its lower viscosity, the resistance to entry of liquid being greater.

On opening of the container 60 to atmosphere, pressure is relieved, so that the gas in the chamber 50 is at a higher pressure than the container interior. Gas, therefore, passes through the gap 42, from where it is jetted through the outlet passage 37 into the liquid. The greater length of the inlet passage 16 relative to the outlet passage 37 provides a higher resistance to passage of gas, so that it is preferentially jetted from the outlet passage 37. The jetted gas causes nucleation, so that dissolved bubbles are released from the liquid. Where the liquid is beer, this produces a head on the beer.

The power of the jet is increased by the convergent configuration of the gap 42, which produces a venturi effect, and the side wall 44 of the space 43 between the passages 16,37.

The insert has only two parts, which can be simply connected together, so that assembly is extremely simple. Furthermore, the insert has no valves, which may become detached, or fail to operate properly.

Claims

1. An insert having a body defining a chamber for containing gas and usable in a pressurised liquid container, such that when the container is opened the gas escapes from the insert to cause foaming of the liquid, the insert comprising a gas inlet passage to allow gas to enter the insert from a headspace in the container and a gas outlet passage to allow gas to be jetted from the insert into the liquid in the container, the inlet and outlet passages being provided in respective wall formations, a gap being defined between the formations and providing communication between the chamber and both the inlet and the outlet passages, whereby in use, lower viscosity gas from the headspace enters the gap and hence the chamber through the inlet passage in preference to higher viscosity liquid entering the outlet passage, and wherein the inlet passage provides greater resistance to passage of gas then the outlet passage, so that, on release of the pressure in the container, gas is preferentially jetted through the outlet passage.

2. An insert according to Claim 1, wherein the inlet passage is longer than the outlet passage to provide said greater resistance.

3. An insert according to Claim 2, wherein the inlet passage is at least twice the length of the outlet passage.

4. An insert according to Claim 2 or 3, wherein the length of the outlet passage is less than lmm.

5. An insert according to any preceding claim, wherein the gap is 0.5mm in depth.

6. An insert according to any preceding claim, wherein the outlet passage has a diameter of 0.3mm.

7. An insert according to any preceding claim, wherein the body includes a tube extending into the chamber and having an end portion for defining the wall formation with the inlet passage, the tube having an end wall provided with the inlet passage.

8. An inset according to Claim 7, wherein the body of the insert has a cup-shaped portion defining the wall formation with the outlet passage, the end portion of the tube being received in the cup-shaped portion and the gap being defined between the inner and outer peripheral walls respectively of the cup-shaped portion and the end portion.

9. An insert according to Claim 8, wherein said inner and outer peripheral walls have portions which converge towards the outlet passage.

10. An insert according to any preceding claim, wherein the inlet and outlet passages are in mutual axial alignment.

11. An insert according to any preceding claim wherein the body comprises two mouldings snap-fitted together to define the chamber.

12. An insert according to any preceding claim, wherein the insert is floatable and self-righting, so that the inlet passage communicates in use with a headspace in a container, with the outlet passage in communication with liquid in the container.

13. A pressurised container of liquid, having a headspace and containing an insert according to any preceding claim located with the inlet passage in communication with the headspace and the outlet passage in communication with the liquid.