Sealing mechanism for vessel and cap to be used in the mechanism

摘要

A cap has a plug portion, a seal plug and a sleeve. At the plug portion a side and a cylindrical wall project from a top board. An inner circumferential surface of the side wall fits on an outer circumferential surface of an opening portion of a vessel and covers the opening portion with the top board. The cylindrical wall forms a receiving chamber having an opening mouth at its under end face. The seal plug seals the opening mouth. The sleeve is loosely fitted on the cylindrical wall and opens the opening mouth by separating the seal plug from the cylindrical wall at relative movement of the cap. A sepal portion on the outer circumference of the sleeve is larger than inner diameter of the opening portion at its outer diameter and has flexibility to pass the inner diameter bending so as to avoid backward moving.