Container closure provided with automatic opening-closing mechanism

Claim 1

A closure adapted to be applied to the mouth-neck portion of a container for holding a liquid at least a body portion of which can be elastically pressed out of shape, said closure comprising an automatic opening-closing mechanism to be mounted on the mouth-neck portion of the container and an outside closure member covering the automatic opening-closing mechanism and having a pour opening, said automatic opening-closing mechanism comprising a plug member having a centrally formed air introduction hole and a plurality of liquid discharge ports formed around the air introduction hole, a first valve member for opening and closing the liquid discharge ports and a second valve member for opening and closing the air introduction hole, said first valve member being formed of a flexible material and annular in shape and disposed over the plug member, and said first valve member being adapted to normally close the liquid discharge ports but when the pressure in the container is increased as a result of its body portion being pressed out of shape, to be elastically bent at its inside circumferential edge portion and to open the liquid discharge ports, and said second valve member having a base portion and a central valve portion connected to the base portion via an elastically bendable linking portion and disposed beneath the plug member, and said second valve member being adapted to normally close the air introduction hole by its central valve portion, but when the body portion of the container elastically returns to its original shape from its pressed state and a negative pressure is created in the container, to be elastically bent at its linking portion thereby displacing the central valve portion and thus to open the air introduction hole.