AU6302298A

AU6302298A - Liquid-foaming insert

Info

Publication number: AU6302298A
Application number: AU63022/98A
Authority: AU
Inventors: Karl Mondszein
Original assignee: Lawson Mardon Sutton Ltd
Current assignee: Amcor Packaging UK Ltd
Priority date: 1997-02-27
Filing date: 1998-02-24
Publication date: 1998-09-18
Also published as: WO1998038111A1; CN1258258A; GB2322614A; EP1007441A1; GB9704132D0; JP2000512958A

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 WO95/22049; WO95/04689; 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 d e 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 mis 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 cup- shaped 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 cup- shaped 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 d rough 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 me 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 1mm.

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 mat the inlet and outlet passages 16,37 need not be located on the axis of me 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 me headspace 62, whereas die outiet 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 die lower pressure in the chamber 50. The gas in me inlet passage 16 opposes the liquid adjacent die outlet passage 37 and primarily, gas enters the chamber 50 dirough me gap 42, until equalisation of pressure between the chamber 50 and me interior of the container is achieved. The gas preferentially enters me chamber over the liquid, due to its lower viscosity, the resistance to entry of liquid being greater.

On opening of me container 60 to atmosphere, pressure is relieved, so mat 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 dirough 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 mat dissolved bubbles are released from me liquid. Where me liquid is beer, mis produces a head on die beer.

The power of the jet is increased by die convergent configuration of the gap 42, which produces a venturi effect, and die side wall 44 of the space 43 between me 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 mat when the container is opened the gas escapes from the insert to cause foaming of the liquid, me 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 me liquid in the container, the inlet and oudet 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 me outlet passages, whereby in use, lower viscosity gas from ie headspace enters me gap and hence ie 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 me outlet passage, so that, on release of die pressure in the container, gas is preferentially jetted dirough die oudet 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 e length of die outlet passage.

4. An insert according to Claim 2 or 3, wherein die lengm of the outlet passage is less than 1mm.

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

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

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

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

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

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

11. An insert according to any preceding claim wherein me body comprises two mouldings snap-fitted toge ier to define d e chamber.

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