Volume-variable container for fluids

Claim 1

A dispensing apparatus for fluids which comprises a variable-volume container, said container comprising: (A) a body portion and an outwardly extending end portion at each end thereof; (B) said body portion comprising four rigid walls, each wall being joined to the next adjacent wall by a longitudinal fold line, said longitudinal fold lines being parallel to one another, said body portion being deformable between a first, collapsed position, and a second, open position wherein said container is deformable by the movement of two opposite pairs of adjacent walls away from each other during expansion and toward each other during compresion; and (C) said end portions each comprising four sets of two geometrically arranged triangular portions constituting means permitting the expansion and compression of said body portion without mechanical strain and substantial longitudinal motion of the end portions, said end portions each having a midpoint and four fold lines extending therefrom to each end of the longitudinal fold lines of said rigid walls, two of said fold lines lying along a line of symmetry, each set of two triangular portions having a first triangular portion having a base coterminous with the end of one of said walls, said base and said end of said wall joining along an edge fold line having first and second ends, and a second triangular portion having a base lying between said second end of the edge fold line and said midpoint along said line of symmetry, said first and second triangular portions having a common side at a common fold line, said common side extending from the second end of the edge fold line to one fold line of said other two fold lines at a point spaced between the first end of said edge fold line and said midpoint.