Patent ID: 8157134
Filing Date: 2012-04-17
Classification: B05B,F04B,F16J

Abstract:
1. A pump for dispensing fluid from a reservoir, comprising: a piston chamber-forming member having a cylindrical chamber, said chamber having a chamber wall, an outer open end and an inner end in fluid communication with the reservoir; a piston-forming element slidably received in the chamber extending outwardly from the open end thereof; said the piston-forming element being generally cylindrical in cross-section with a central axially extending stem having an inner end in the chamber and extending from the inner end outwardly to an outer end; a first seal disc extending radially outwardly from the stem proximate the inner end, the first seal disc having an elastically deformable edge portion proximate the chamber wall circumferentially thereabout, wherein in operation: (a) on the piston forming element sliding outwardly in said chamber, the first seal disc substantially preventing fluid flow past the first seal disc in an inward direction, and (b) on the piston forming element sliding inwardly into the chamber the first seal disc elastically deforms away from the chamber wall to permit fluid flow past the first seal disc in an outward direction; a first locating disc on said stem located axially on the stem proximate to the first seal disc, the first locating disc extending radially outwardly from the stem to an edge portion which engages the chamber wall over a circumferential sector greater than 180 degrees to guide the piston-forming element in sliding axially centered and aligned within the chamber, the first locating disc having an opening axially therethrough radially outwardly of the stem permitting fluid flow past the first locating disc in both an inward direction and an outward direction.