Airtight cover

Abstract

An airtight cover aims to cover an opening edge of a container and includes an upper rigid lid and an airtight flexible plate located below the upper rigid lid. The airtight flexible plate includes a sealing rim in contact with the opening edge and a central portion and a peripheral portion located respectively on an inner side and an outer side of the sealing rim. The sealing rim and upper rigid lid are interposed by a gap. When the airtight flexible plate contacts with the opening edge through the sealing rim to make the central portion continuously move downward, the peripheral portion is forced to warp upward, and the upper rigid lid presses the peripheral portion to bend downward. Hence the contact area between the sealing rim and opening edge increases, which can securely seal the container to meet requirements of usage.

What is claimed is: 
     
         1 . An airtight cover for covering an opening edge of a container, comprising:
 an airtight flexible plate including a sealing rim in contact with the opening edge and a central portion and a peripheral portion located respectively on an inner side and an outer side of the sealing rim; and   an upper rigid lid which is located above the airtight flexible plate, and includes an annular grasp portion which is extended upward from the upper rigid lid and includes an installation hole, wherein the airtight flexible plate includes an annular flange corresponding to and latching on the installation hole, and wherein the sealing rim and a distal end of the upper rigid lid are interposed by a gap.   
     
     
         2 . The airtight cover of  claim 1 , wherein the airtight flexible plate includes a groove formed on the peripheral portion, and the upper rigid lid includes a flange corresponding to the groove. 
     
     
         3 . The airtight cover of  claim 2 , wherein the airtight flexible plate includes an inverse flange extended from the groove. 
     
     
         4 . The airtight cover of  claim 1 , wherein the airtight flexible plate includes an air vent formed in the annular flange to hold a check valve. 
     
     
         5 . The airtight cover of  claim 4 , wherein the check valve is gradually shrunk to form a duck-beak end with a crevice formed therein.