US Patent 7497356 Fluid dispenser device

A fluid dispenser device includes a chamber provided with an inlet valve and with an outlet valve, and defining a sealed slide cylinder; a piston disposed inside the chamber and including a lip capable of sliding in sealed manner in the slide cylinder. A bearing flange for coming to bear against a reservoir neck; and a ferrule against which the piston is resiliently urged in the rest position. The device being characterized in that the sealed slide cylinder is situated above the bearing flange so that it cannot be inserted into the reservoir neck.