Patent ID: 7861898
Filing Date: 2011-01-04
Classification: B05B

Abstract:
1. A pump for dispensing fluids from a reservoir, comprising: a piston-chamber forming member having a chamber wall defining a cylindrical piston chamber therein disposed about an axis and bounded by a cylindrical, radially inwardly directed inner surface of the chamber wall, the chamber wall having a distal outer end defining an outer open end of the piston chamber, the piston chamber having an inner end in communication with the reservoir; the chamber wall having a cylindrical, radially outwardly directed outer guide surface, a piston forming element coaxially slidably received in the piston chamber extending outwardly from the open end thereof; said piston forming element having an axially extending stem having a distal inner end forming a piston received in the chamber and engaging the chamber wall circumferentially thereabout to prevent fluid flow therepast at least one of inwardly and outwardly, a locating member secured to the stem radially outwardly of the piston, the locating member having a guide wall defining a coaxial cylindrical guide chamber therein bounded by a cylindrical, radially inwardly directed inner guide surface of the guide wall, the guide wall having a distal inner end defining an inner open end of the guide chamber, the chamber wall extending outwardly through the inner end of the guide chamber with the chamber wall coaxially received within the guide chamber with the radially inwardly directed inner guide surface of the guide wall in coaxial, axially sliding engagement with the radially outwardly directed outer guide surface of the chamber wall to guide the piston-chamber forming member and the piston forming element in sliding axially, while maintaining the piston centered coaxially relative to the piston chamber, wherein in any position of the piston in the piston chamber, the radially inwardly directed inner guide surface of the guide wall engaging with the radially outwardly directed outer guide surface of the chamber wall over an axial extent substantially equal to an axial extent the piston extends into the piston chamber, and wherein the chamber wall forms an inner tube, the piston-chamber forming element including an outer tube spaced radially outwardly of the inner tube with the inner tube and outer tube coupled together proximate their inner ends providing an annular space therebetween open axially outwardly, the guide wall forming a guide tube coaxially received in the annular space.