Patent ID: 7837070

Claim:
A simplified pump for dispensing fluid substances withdrawn from a container of said substances, comprising a cup-shaped body defining a cylindrical chamber into which a hollow stem extends, an endpiece mounted on an open first end of the cup-shaped body, said cup-shaped body presenting at its second end a passage, sealedly closable by a unidirectional valve, and a seat for housing one end of a dip tube for withdrawing the fluid substance from the container, a piston sealedly slidable along the surface of the cylindrical chamber, said piston being rigid with said stem and being disposed in proximity to a first end of the stem within said chamber and projecting towards the inner surface of the cup-shaped body, the endpiece being provided both with a hole through which said stem emerges and by which it is guided, and with at least one element sealing against said piston, an elastic member which acts in the sense of urging said piston towards said endpiece, and a movable valve for closing a stem cavity, wherein positioned in the interior of the cup-shaped body there is an elongated rod, a first end of which projects below the unidirectional valve and is inserted into and retained in a seat provided at the second end of the cup-shaped body below the unidirectional valve, an intermediate portion of the rod having a cylindrical profile of diameter less than the diameter of said stem cavity into which said rod portion extends, said movable valve for closing the stem cavity comprising a continuous elastic lip projecting from a second end of the rod towards the outside of said cylindrical chamber, said lip being sealedly slidable in contact with the cylindrical surface of the stem cavity and expanding radially outward in a direction away from said cylindrical chamber, whereby pressure in the cylindrical chamber causes the lip to flex away from contact with the cylindrical surface of the stem cavity to relieve the pressure.