Patent ID: 7472809

Claim:
A liquid jetting pump comprising: a mounting cap fitted to a container neck portion; a cylinder fixed to a container through said cap and including a suction valve provided in a lower edge part extending downward into said container; a hollow stem having a lower edge surface closed and provided so that said stem is vertically movable in a central portion within said cylinder in an upward biased state and including a discharge valve with a valve hole so holed in an upper part of an interior of the hollow stem as to be closed by a valve member vertically moved by a liquid pressure; an annular piston so fitted to a lower side edge part of an outer periphery of said hollow stem as to be vertically movable at a predetermined stroke, the annular piston having an outer peripheral surface slidably fitted to an inner surface of said cylinder and so provided as to make openable or closable a through-hole holed in the lower side edge part of said hollow stem in communication with the interior of the hollow stem; and a head, with a nozzle, so provided in continuation from an upper edge of said stem as to be vertically movable above said mounting cap, a liquid within said cylinder being led into said stem via said opened through-hole and jetted out of said nozzle through the discharge valve by pushing down said push-down head, and the liquid within said container being sucked into said cylinder and into the interior of said hollow stem through a suction valve by negative-pressurizing the interior of said cylinder when said push-down head is raised, wherein said annular piston is always biased upward with respect to said stem, and said through-hole is so formed as to be closable only in a maximum ascent position of said stem.