Patent ID: 7775394

Claim:
An opening-force-maximizing device of an underpressure-activated valve structured for connection to a drinking container having an outlet opening, said device comprising: a partition wall provided with a wall opening and structured to be able to cover and pressure-sealingly enclose the outlet opening in the drinking container; a peripherally continuous membrane positioned at an outside of the partition wall and subjected to ambient pressure, the membrane being arranged about a valve axis through the wall opening in the partition wall, the valve axis defining the axial direction of the underpressure-activated valve; and an axially movable valve sealing member connected to the membrane and provided with a valve head positioned upstream of the wall opening for the opening and closing thereof; wherein an upstream side of the partition wall is provided with a valve seat formed around the wall opening for pressure-sealing and valve-closing contact with said valve head when the membrane is in an inactive position; wherein the membrane has an axial extent so as to form a sleeve-like body having two axial termination ends represented by an attachment end and a maneuvering end; wherein the attachment end is fixedly connected to the partition wall at a peripheral rim thereof; wherein the movable maneuvering end is positioned at an axial distance from the attachment end and is connected in a tensile-force-transmitting manner to the valve sealing member; wherein one side of the membrane is structured for receiving an underpressure which, together with said ambient pressure, creates a differential pressure across the membrane; wherein the sleeve-like membrane, when in its inactive position, is arranged with a maximum axial extent; wherein the membrane is radially flexible and therefore able to deflect in a radial direction relative to said valve axis; and wherein the membrane is arranged in a manner inhibiting axial stretching causing it to be insignificantly extendable in said axial direction when subjected to said differential pressure, which generates a tensile force in the membrane causing the membrane to contract axially and assume an active position, thereby causing a valve-opening, axial movement of the valve sealing member.