Blow molded bottle with self-supporting base reinforced by hollow ribs

Claim 1

A container comprising an upright hollow tubular body having an upright longitudinal axis and a side wall terminating at its lower end in an integral aligned base which closes the lower end of the side wall, the outer surface of the base having an upwardly concave surface located centrally of the base and a convex bottom surface of annular shape surrounding the concave central surface and merging therewith and with said side wall at the lower end thereof, the lowermost points of said convex bottom surface lying in a common plane, said upwardly concave surface projecting upwardly into the interior of the tubular body from said convex bottom surface and having an apex centrally thereof, a plurality of indentations on the convex body surface forming a plurality of hollow ribs extending upwardly and interrupting said convex bottom surface, said ribs being substantially symmetrical with respect to said axis and extending radially with respect to said axis, said ribs being positioned substantially below the apex of said concave surface and spaced a small distance upwardly from said bottom surface relative to said apex, and said bottom surface between said ribs forming a plurality of container support feet, said ribs and feet being proportioned in a direction circumferentially of said bottom surface so that said ribs are narrow and said feed at substantially wider than said ribs throughout their length to provide firm support of said container on said feet when standing on a horizontal surface, said ribs providing also for symmetrical arrangement of said feet to thereby assure a balance support of said container on said feet.