Interlocking stackable bottles

Claim 1

In a bottle of the type having: (a) a liquid container made of a plastic material, the container being generally symmetric in shape about a symmetry axis and having a container opening in it for filling and discharging liquid, the container opening being located so that the symmetry axis passes centrally through the opening; (b) a top closure for sealing the container opening; and (c) a base cup joined to the liquid container at an end of the container generally opposite to the container opening, the base cup being made of a plastic material and being shaped to permit the bottle to stand upright on a horizontal surface with the symmetry axis of the container extending in a substantially vertical direction, a bottle-rest reference surface being defined to be a plane tangent to the points of the base cup on which the base cup rests when the bottle is standing upright on a horizontal surface; the improvement which comprises: (i) a base-cup interlock band joined to the base cup, the interlock band extending generally parallel to the bottle-rest reference plane and around an outer surface of the base cup, the interlock band including a plurality of interlock band segments, each interlock band segment corresponding to a side of a reference equilateral polygon defined to be lying in the reference plane and centered on the symmetry axis, the number of interlock band segments being equal to four times an integer greater than one, an outwardly facing surface of each interlock band segment defining an interlock facet, each interlock facet extending in a direction generally parallel to the corresponding side of the reference polygon and in a direction generally parallel to the symmetry axis, an intersection between each pair of adjacent interlock-band segments being generally rounded, each interlock facet having a plurality of grooves passing through it extending generally parallel to the symmetry axis of the liquid container to define vertical facet grooves, the width of the vertical facet grooves being greater than the spacing between adjacent grooves to permit the vertical facet grooves of two facets on different bottles to mesh, each pair of adjacent facets having a plurality of grooves extending generally parallel to the reference plane to define horizontal facet grooves, the horizontal facet grooves extending between a first vertical facet groove located on a first facet of a pair of adjacent facets and closest to a second facet of the pair and a second vertical groove located on the second facet and closest to the first facet, the width of the horizontal facet grooves being greater than the spacing between adjacent grooves and the spacing between boundaries of the facet and horizontal facet grooves adjacent to the boundaries to permit the horizontal grooves of two facets of the different bottles to mesh, the horizontal and vertical grooves of the interlock facets thereby cooperating to prevent bottles from moving relative to one another in two directions when the bottles are placed in alignment facet-to-facet with facet grooves engaged; and (ii) a bottle-stacking support connected to the base cup and abutting a base portion of the liquid container, the bottle-stacking support being located symmetrically with respect to the symmetry axis of the liquid container and spaced apart from the bottle-rest reference plane, the base cup being shaped to define a closure guide which opens from the bottle-stacking support to the bottle-rest reference plane, the closure guide being shaped to receive the top of a closure of a second bottle whose symmetry axis is generally colinear with the symmetry axis of the bottle having the bottle-stacking support and to guide the closure top to the bottle-stacking support, the bottle-stacking support being adapted to transmit the weight of the bottle having the bottle-stacking support to the top of the closure of the second bottle.