A finger actuated pump dispenser mounted on a fluid containing vessel and comprising:
- a vertical hollow elongated body having an upper section defining a first hollow vertical cylinder with a first diameter and an open upper end and an integral lower section defining a second hollow vertical cylinder with a second diameter smaller than the first diameter and a closed lower end with a central opening, the first cylinder having a lower end which is joined to an open upper end of the second cylinder;
- an outer hollow stem open at upper and lower ends with a vertical bore therebetween, the outer stem having a first outwardly extending enlargement intermediate these ends, a portion of the first stem intermediate the upper end and the first enlargement extending upwardly through the upper end of the first cylinder with the first enlargement and a remaining portion of the first stem being disposed within the first cylinder;
- a hollow vertical main piston having an upper open end, the main piston having a lower closed end with a central opening and an inwardly extending horizontal bead, the main piston being disposed and vertically slidable along the outside of the first stem within the first cylinder;
- an inner stem having an upper vertical section and an integral lower section, the lower section having a cross sectional area which is larger than the cross sectional area of the upper section of the inner stem and is smaller than the cross sectional area of the second cylinder, the upper section of the inner stem extending upwardly through the first piston and through the bore and being spaced inwardly from the inner surface of the outer stem, thus defining a vertical fluid discharge path therebetween, the upper end of the lower section of the inner stem engaging the lower end of the main piston in such manner that, during downstrokes, at least one horizontal channel is disposed between the upper end of the lower section of the inner stem and the lower end of the main piston and connects the region between the inner wall of the first cylinder and the lower section of the inner stem with the fluid discharge path, the upper section of the inner stem adjacent but above the lower section of the inner stem having an inner horizontal recess engaged by said bead, the depth of the bead being smaller than the depth of the recess;
- port means cooperating with the upper ends of the outer stem and the upper section to define a fluid discharge port which has an open position for allowing fluid discharge therethrough and a closed position for blocking fluid discharge therethrough;
- a vertical inner piston vertically slidable in the second cylinder with an upper end adjacent and engagable with the lower end of the lower section of the second cylinder, the inner piston having a second outer enlargement which engages the inner wall of the second cylinder;
- first biasing means disposed within the first cylinder between the lower end of the main piston and the first enlargement, the first biasing means causing the port means to close the discharge port except during a downstroke, the port being opened at a selected point during said downstroke;
- second biasing means disposed within the second cylinder between the lower end of the second cylinder and the second enlargement;
- and
- means associated with the inner piston and the second cylinder which when actuated during an upstroke following said downstroke establishes a fluid transfer path between the fluid in the container and a pump chamber formed by the space subtended by the inner wall of the first cylinder, the inner stem and the two pistons when the inner piston attains a selected position with respect to the second cylinder.