Dynamically expandable container
A container having an expandable thickness for better insulation. The container has two walls which may be expanded to form an insulating air space therebetween. The expansion may be caused by compressible foam, an expandable strip material, a projection running on an inclined surface arrangement or by a gas generating material. The expansion may be activated by removing a vacuum, pulling a physical strip, by rotating one layer within the other or by crushing microcapsules to release gas. The expanded container provides better insulation for hot foods but allows a smaller thickness for storage.
1 . An expandable container comprising:
a inner wall;
an outer wall, said inner wall being nested in said outer wall; and
an expander between the walls so that the walls, the expander increasing distance between the inner wall and outer wall to provide greater heat insulation.
2 . The container according to claim 1 , wherein the container is a bowl.
3 . The container according to claim 1 , wherein the container is a plate.
4 . The container according to claim 1 , wherein the container is a bag.
5 . The container according to claim 1 , wherein the container includes an expandable lid.
6 . The container according to claim 1 , wherein the means for expanding includes at least one foam material compressed under pressure, which expands on the release of the pressure to force the inner wall and the outer wall apart.
7 . The container according to claim 6 , wherein the foam material is compressed using a vacuum seal and is allowed to expand by breaking the seal.
8 . The container according to claim 6 , wherein the foam is held in a compressed state by a strap and is released by removing the strap.
9 . The container according to claim 1 , wherein the expander is a sheet of material having slits which forms an expanded material by being pulled.
10 . The container according to claim 1 , wherein the expander includes projections on one wall and sloping recesses on the other wall which meet, with the projections sliding on the sloped walls of the recess to push the walls apart.
11 . The container according to claim 1 , wherein the expander includes a layer of material which generates gas when activated.
12 . The container according to claim 11 , wherein the material includes microcapsules of citric acid and bicarbonate.
13 . The container according to claim 1 , wherein the expander is a set of screw threads on each wall.
14 . The container according to claim 1 , wherein the expander is an accordion mechanism between the two walls.
15 . The container according to claim 14 , where the outer wall is a film which is stretched when corrugations of said accordion are unfolded.
16 . A method of expanding a container to increase its thermal insulation, comprising:
providing an inner wall and an outer wall which are nested;
providing an expandable device between the inner wall and the outer wall; and
activating said expandable device to create a larger space between said inner wall and said outer wall.
17 . The method according to claim 16 , wherein the expandable device is a foam material.
18 . The method according to claim 16 , wherein the expandable device is a slitted material.
19 . The method according to claim 16 , wherein the expandable device is an arrangement of projections from one wall and recesses having a sloped bottom on another wall.
20 . The method according to claim 16 , wherein the expandable device is a material which is capable of generating gas.