| 摘要 |
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. |
