Patent ID: 8087553

Claim:
A one way valve assembly for dispensing a flowable substance comprising: a source for the flowable substance having an opening, a valve assembly connected to the opening for receiving the flowable substance from said source and for dispensing the flowable substance, said valve assembly comprising: an axially extending inner core, an axially extending flexible membrane tightly fitted over an outer surface of said inner core, said inner core having an axially extending passageway in communication with said source, at least one port opening from said passageway to an inner surface of said flexible membrane for expanding said membrane outwardly from said outer surface of said inner core, an axially extending cover enclosing an outer surface of said membrane, said cover having an outlet orifice at an end of said inner core spaced axially from said inlet opening for dispensing the flowable substance from the valve body assembly when pressure is applied to the source for flow from the source into the passageway in said inner core and out of said at least one port for expanding said membrane and for flow of the substance between said outer surface of said core and said inner surface of said membrane into said outlet orifice in said cover and when the pressure on said source is released said membrane moves back into tightly fitting contact with the outer surface of said inner core and returns any flowable substance between said membrane and inner core back into said source while preventing any contamination of the flowable substance remaining in the container, wherein said flexible membrane has a variable wall thickness that is greater at the axial end of said membrane adjacent the outlet in said cover.