Molded plastic water storage tank
View Patent ↗The cover of a plastic tank suitable for containing water is attached to the tank base by means of alternative joints, including elastically engageable features and lock features to prevent unwanted release. The base of a plastic water tank is comprised of a substrate and a liner and is formed by means which include injection molding into a mold where the core part of the mold is surrounded in part or full by the film which forms the liner.
1. A plastic water storage tank comprising:
a base having a circular wall centered on a longitudinal axis of the base, a lengthwise first end having a circular terminus, a closed-bottom lengthwise second end, and a tub shape interior for holding water, the base shaped to be nestable within like bases for shipment or storage, each base having a central longitudinal axis and a circular rim integral with said circumscribing wall, the rim centered on the longitudinal axis of the base;
a cover shaped to be nestable within like covers for shipment or storage, each cover having a circular rim which includes a plurality of outwardly extending tabs;
the rim of the cover and the rim of the base having mating features which enable formation of a joint therebetween when the cover rim is mated with the base rim and rotated relative to the base about said longitudinal axis;
wherein said base circular rim comprises a flange extending in a first portion radially outwardly from said base wall, and in a second portion extending in the longitudinal axis direction, the flange portions thereby defining a circumscribing cavity within the rim facing in the longitudinal direction; and,
a plurality of lip segments, spaced apart by cutouts, extending radially inwardly from said longitudinal portion of the flange in the direction of said longitudinal axis;
wherein the tabs of the cover fit within the cutouts of the flange when the cover and base are mated; and wherein when mated with the base so each cover tab enters a cutout, the cover is then rotatable to relocate the tabs within said cavity, so that each cover tab is positioned within said circular cavity beneath a lip segment, cover thereby held in place on the base; and,
wherein the tabs of the cover have upper surfaces which are sloped relative to the plane of the circle of the rim, so that when the tabs are relocated by rotation of the cover relative to the base, the tabs are thrust in a direction which urges the rim of the cover to move closer to the rim of the base.
2. The plastic water tank of claim 1 further comprising at least one lock key which is integral with the cover, the lock key shaped to engage one of the said flange cutouts when the cover is rotated relative to the base to relocate the tabs.
3. The plastic water tank of claim 2 wherein the inwardly extending lip segments of the flanges have wedge shaped edges.
4. The plastic water storage tank of claim 1 wherein the flange has a plurality of downwardly extending openings, each opening located beneath one of said radially extending lip segments and having, in a plane which is perpendicular to said longitudinal axis, the same shape as the lip segment.
5. The plastic water tank of claim 1 wherein the cover further comprises a circular groove shaped for holding a resilient seal, the groove mating with the terminus of the rim.
6. A plastic water storage tank comprising:
a base having a circumscribing wall and an integral bottom that define a tub shape interior for holding water, the base shaped to be nestable within like bases for shipment or storage, the base having a central longitudinal axis and a circular rim integral with said circumscribing wall and centered on said central longitudinal axis of the base;
a cover shaped to be nestable within like covers for shipment or storage, each cover having a circular rim which includes a plurality of outwardly extending tabs;
the rim of the cover and the rim of the base having mating features which enable formation of a joint therebetween when the cover rim is mated with the base rim and rotated relative to the base about said longitudinal axis;
wherein said base circular rim comprises a flange having a first portion extending radially outwardly from said base wall with a plurality of circumferentially spaced apart openings, the flange having a second portion extending in the longitudinal axis direction, the flange first and second portions together with a longitudinally extending portion of said base circumscribing wall thereby defining a circular cavity of the rim, the cavity facing in the longitudinal axis direction;
a plurality of lip segments, spaced apart by cutouts, extending radially inwardly toward said central longitudinal axis from said second portion of the flange;
wherein each said circumferentially spaced apart opening in the first portion of the flange of the rim is longitudinally spaced apart from one of said lip segments; and,
wherein the tabs of the cover fit within the cutouts of the flange when the cover and base are mated; and wherein when mated with the base so each cover tab enters a cutout, the cover is then rotatable to relocate the tabs within said circular cavity, so the each cover tab is positioned within said circular cavity beneath a lip segment, so the cover is thereby held in place on the base.
7. The plastic water tank of claim 6 wherein the tabs of the cover have upper surfaces which are sloped relative to the plane of the circle of the rim, so that when the tabs are relocated by rotation of the cover relative to the base, the tabs are thrust in a direction which urges the rim of the cover to move closer to the rim of the base.
8. The plastic water tank of claim 7 further comprising at least one lock key which is integral with the cover, the at least one lock key shaped to engage one of the said flange cutouts when the cover is rotated relative to the base to relocate the tabs.
9. The plastic water tank of claim 8 wherein said inwardly extending lip segments of the flange have wedge shaped edges.
10. The plastic water tank of claim 6 wherein the cover further comprises a circular groove shaped for holding a resilient seal, the groove mating with the rim of the base.
11. A plastic water storage tank comprising:
a base having a circular wall centered on a longitudinal axis of the base, a lengthwise first end having a circular terminus, a closed-bottom lengthwise second end, and a tub shape interior for holding water, the base shaped to be nestable within like bases for shipment or storage, each base having a central longitudinal axis and a circular rim integral with said circular wall, the rim centered on the longitudinal axis of the base;
a cover shaped to be nestable within like covers for shipment or storage, each cover having a circular rim which includes a plurality of outwardly extending tabs;
the rim of the cover and the rim of the base having mating features which enable formation of a joint therebetween when the cover rim is mated with the base rim and rotated relative to the base about said longitudinal axis;
wherein said base circular rim comprises a flange extending in a first portion radially outwardly from said base wall at a location which is longitudinally displaced in the direction of said base second end from said circular terminus of said base wall at the first end of the base, and in a second portion extending in the longitudinal axis direction away from said base second end, the flange first and second portions thereby defining within the rim a circumscribing cavity facing in the longitudinal direction; and,
a plurality of lip segments, spaced apart by cutouts, extending radially inwardly from said second portion of the flange in the direction of said longitudinal axis;
wherein the tabs of the cover fit within the cutouts of the flange when the cover and base are mated; and wherein when mated with the base so each cover tab enters a cutout, the cover is then rotatable to relocate the tabs within said cavity, so the each cover tab is positioned within said circular cavity beneath a lip segment, so the cover is thereby held in place on the base.
12. The plastic water tank of claim 11 wherein the tabs of the cover have upper surfaces which are sloped relative to the plane of the circle of the rim, so that when the tabs are relocated by rotation of the cover relative to the base, the tabs are thrust in a direction which urges the rim of the cover to move closer to the rim of the base.
13. The plastic water tank of claim 12 further comprising at least one lock key which is integral with the cover, the lock key shaped to engage one of the said flange cutouts when the cover is rotated relative to the base to relocate the tabs.
14. The plastic water tank of claim 13 wherein the inwardly extending lip segments of the flanges have wedge shaped edges.
15. The plastic water storage tank of claim 11 wherein the flange has a plurality of downwardly extending openings, each opening located beneath one of said radially extending lip segments and having, in a plane which is perpendicular to said longitudinal axis, the same shape as the lip segment.
16. The plastic water tank of claim 11 wherein the cover further comprises a circular groove shaped for holding a resilient seal, the groove mating with the terminus of the rim of the base.