Base of a plastic container
A plastic container has a base portion adapted for vacuum absorption, the container including a base and a body extending up from the base along a central axis to a finish portion defining a mouth. The base includes an outside wall, a chime connecting the outside wall to an annular contact ring, an inside wall extending upward from the contact ring to a hinge, and a diaphragm connected to the hinge. The diaphragm can move between first and second positions in response to pressure change within the container. The diaphragm includes a central region and a flexible wall having a curved profile in cross section. The flexible wall curves downward from the hinge to the central region. In some embodiments, the flexible wall is asymmetric and includes a first portion having a curved profile and a second portion having a linear profile. A container wall structure is also disclosed.
1. A plastic container having a base portion adapted for vacuum absorption, the container comprising a base and a container body extending up from the base along a central axis to a finish portion defining a mouth, the base including
an outside wall;
a chime connecting the outside wall to an annular contact ring;
an inside wall extending upward from the annular contact ring to a circular hinge; and
a diaphragm connected to the circular hinge, the diaphragm movable between a first position and a second position in response to pressure change within the plastic container, the diaphragm including a central region and a flexible wall around the central region, wherein the flexible wall includes a first portion having a curved cross-sectional profile between the central region and the hinge, a second portion having a linear cross-sectional profile between the central region and the hinge, and transition portions extending radially between the central region and the hinge and positioned circumferentially between the first portion and the second portion.
2. The container of claim 1 , wherein the inner wall extends linearly between the annular contact ring and the hinge.
3. The container of claim 1 , wherein the transition portions between the first portion and the second portion of the flexible wall include a first transition portion and a second transition portion arranged on opposite sides of the central region, wherein the first transition portion includes a convex profile between the first portion and the second portion, and wherein the second transition portion incudes a concave profile between the first portion and the second portion.
4. The container of claim 1 , wherein when the diaphragm is in the first position the central region is axially closer to a plane of the annular contact ring than the flexible wall.
5. The container of claim 1 , wherein the first portion of the flexible wall includes a first radial portion having a first radius of curvature and a second radial portion having a second radius of curvature less than the first radius of curvature, wherein the second radial portion is radially between and connects to the first radial portion and to the central region.
6. The container of claim 5 , wherein the second radius of curvature is from 0.15 to 0.25 inch and the first radius of curvature is from 1.1-1.2 inches when the diaphragm is in the first position.
7. The container of claim 1 , wherein the central region is oriented perpendicular to the central axis when the diaphragm is in the first position and is oriented transversely to the central axis when the diaphragm is in the second position.
8. The container of claim 7 , wherein the container body has a first wall thickness and the diaphragm has a second wall thickness that is less than the first wall thickness.
9. The container of claim 1 , wherein the container body includes a plurality of wall sections interspersed axially with ribs extending radially inward, wherein each of the ribs includes at least three protrusions distributed circumferentially along the rib and protruding radially outward between adjacent wall sections, wherein protrusions of axially adjacent ribs are circumferentially offset.