| 摘要 |
Gas is vented from within a container neck 12 (neck features are dashed lines in the cross-section) at least when the closure 16 (dotted lines in the cross-section) is in a venting position (fig 4D). The closure 16 has circumferentially overlapping screw thread segments 26 which engage lugs 20 in the container neck 12 and forms a seal 46, 48 when closed. When opening the closure 16, the lugs 20 can engage shoulder blocks 44 in the thread segments 26, which locks the closure in the venting position while under axial pressure (e.g. for safety), whereby recesses 34 adjacent the lugs 20 in the container neck 12 (see fig 4D) cooperate with the gaps between the threads 26 to allow the gas inside to escape. After venting, when there is no upwards axial pressure on the closure, the closure can drop down so lugs 20 disengage from shoulder blocks 44 (fig 4E) to allow further unscrewing of the closure (fig 4F). The neck may have a guide 64 to engage with the threads 26 of the closure to urge the closure away from the neck during unscrewing. Locking ribs 68 may cooperate with ramps 70 to prevent unwanted opening and there may be a tamper evident ring 56. |
