US Patent 7731067 Device for the metered dispensation of a medium

A device for the dosed output of a medium from a container through an opening in an upper housing part. A valve piston tip is associated with said opening for the closing thereof. A piston surface, which is pressed against a spring, is adjacent to the valve piston tip and is used as part of a valve piston, which is sealingly guided in a piston chamber in the upper part of the housing and forms a filling chamber which is connected to the container, between the upper part of the housing and the opening.