US Patent 7350666 Self regulating spout

A drinking spout for beverage cans, bottles, cups or handheld containers that temporarily hold a drinking fluid (beverage), which can be carbonated or a hot drink under pressure and which is closed off by the spout. Spilling of the fluid held therein is prevented during awkward drinking situations such as in cars while driving, walking or other less controlled drinking conditions. The fluid in the container, remains under pressure while permanent access is possible through the spout. The spout comprises a suction piece that is leak tight attached to a valve housing which holds a spring, a centrally perforated inverted membrane and a valve. When suction is applied to the spout, the inverted membrane moves downwards thereby opening the valve against the internal pressure of the bottle or container and allowing fluid to pass to the mouth. When the suction stops, a spring closes the valve. Air venting is provided, through the same valve, when the internal gas pressure drops below the atmospheric pressure.