摘要：

A leakproof pump construction for hand-held dispensers, comprising a pump cylinder, an annular piston having a hollow bore which is slightly conical, said piston being reciprocatible in the cylinder between high and low positions therein, and a hollow ducted plunger carrying the piston and extending through the bore thereof. The plunger has a side orifice and discharge passage or duct through which liquid product can flow to be dispensed from a spray head. The piston is movable between high and low positions on the plunger to control the discharge through the latter. For the non-dispensing condition, the piston seals against an internal shoulder in the cylinder while a valve head at the lower portion of the plunger seals against a cooperable valve seat on the lower body portion of the piston. The sealing surface of the valve head and the valve seat are both of conical configuration such that the valve head normally applies radially inward pressure on the walls of the piston. The action on the piston is thus a double-ended one tending to squeeze the piston radially inward to closely hug the plunger, causing the walls in the bore of the latter, especially the smaller diameter portion thereof, to sealingly embrace with added force the cylindrical wall of the plunger, and effectively preventing liquid from leaking past the two parts.

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