Piston displacement liquid spray pumps

Claim 1

A piston displacement liquid spray pump comprising in combination a container; a pump supporting ferrule engaged on the neck of said container; a hollow cylindrical housing having an upper end provided with an outwardly extending lip, the lower edge of said lip being supported on said ferrule and its upper edge pressing a packing washer against the cover portion of said ferrule, at least one outwardly directed radial slit being provided through said lip of the housing whereby venting of the said container is permitted through said at least one slit to the atmosphere; a stem within said housing; a hollow stem extension telescopically engaged outwardly of the upper section of said stem; an actuator engaging the upper end of said stem extension and capable of biasing the same and said stem downwardly, said actuator being provided with an outlet passage and nozzle in communication with the bore of said hollow stem extension; a check valve comprising a valve chamber, a valve seat at the lower end of said valve chamber, and a bullet-shaped hollow floating valve member cooperating with said valve seat and within which the lower end of said stem is received on its downward movement; a longitudinal groove along the upper section of said stem and forming a passage with the complementary bore of said hollow stem extension communicating the interior of said housing with said nozzle; a piston slidably movable within said housing and forming therewith a pumping chamber and a venting chamber, said piston being mounted on the lower end of said hollow stem extension with a longitudinal lost motion engagement thereto; an outwardly directed annular flange on the middle portion of said stem; the lower end of said stem extension being spaced from the upper surface of said annular flange so as to form a span communicating said groove with said pumping chamber; said lost motion engagement of the piston enabling said piston to fully obstruct said span during its upward or charging stroke and to clear the same during its downward or pumping stroke; said piston when the stem is at its uppermost position, being capable of firmly bearing against the lower surface of said packing washer thus blocking said at least one slit to prevent leakage from the container; and spring means to bias said stem and said stem extension upwardly in unison.