| 摘要 |
A cap (10) for closing a liquid beverage container is disclosed for allowing the beverage to be sucked out of the container through a spout (20), while preventing spillage when no suction takes place. The cap includes a demand valve (16,18) which is incorporated into the cap (10), and has an inlet port (184,186) communicating with the interior of the container. The cap also includes a discharge port communicating with the spout (20) and a control port communicating with the ambient atmosphere through a hole (101) in the cap. The valve includes a valve seat (184) and a closure element (164) controlling the flow from the inlet port to the discharge port. The closure element (164) is urged by the pressure in the container in a direction to seal against the valve seat (184) and is urged to move to an open position in dependence on the excess of the pressure in the control port over that in the discharge port. The movement of the closure element (164) to open the valve is in the opposite direction to that of the flow of liquid through the valve. The demand valve is formed by two members that are mounted on the inner surface of the cap. The first member (18) is rigid and defines the valve inlet port and the valve seat (184). The second member (16) incorporates the valve closure element (164) and a resilient membrane, which is connected to the valve closure element and serves as a pressure sensitive diaphragm. The second member (16) seals against the first member (18) and around the hole (101) in the cap. The cap is characterised in that the second member (16) surrounds and seals against the entire outer rim of the first member (18).
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