Pump for hand-held dispensers

Claim 1

A pump construction for hand-held dispensers and the like, comprising in combination: a. a cylinder having a side vent opening in its upper portion, b. means providing an annular sealing shoulder on the cylinder inner wall at a location above said vent opening, c. a hollow plunger reciprocatively mounted at the top of the cylinder and movable in the direction of its axis in the upper portion of the cylinder, said plunger having a discharge passage, carrying a valve head at its lower portion, and having a slide bearing surface above the valve head, d. a hollow tubular piston carried by the plunger and movable in the cylinder between raised and lowered positions, said piston having a cylindrical body portion which is engageable with and slidable longitudinally on the bearing surface of the plunger between high and low positions thereon, and spaced from the walls of the cylinder, said piston having a lower skirt portion engageable with the cylinder walls and provided with a valve seat engageable with the valve head when the piston is in said low position on the plunger, and e. means providing a fluid passage from the lower valve seat of the piston to the discharge passage of the plunger when the valve seat is disengaged from the valve head, f. said plunger having an annular valve seat located above its slide bearing surface and engageable with an upper portion of the piston when the latter is in its high position on the plunger, g. the upper edge portion of the piston body portion constituting a valve which engages the sealing shoulder in the cylinder when the piston is in its raised position in the cylinder, h. the said upper portion of the piston having an inwardly-extending flange located at the upper piston end and extending toward the plunger axis, said plunger having a body portion disposed under said flange, and having means maintaining it spaced from the flange, i. the upper surface of said flange constituting a valve face adapted for engagement with the annular valve seat of the plunger, j. said annular valve seat of the plunger being conical and snugly receiving the piston flange, k. the upper surface of the piston flange and the said upper edge portion of the piston body portion constituting essentially a single continuous conical surface, l. the annular sealing shoulder in the cylinder being conical for engagement with said single continuous conical surface of the piston body portion.