PRESSURE CONTAINER WITH DIFFERENTIAL VACUUM PANELS

Abstract

A plastic container (1) has a first set of flex panels (2) and a second set of flex panels (3) one set being adapted to react to pressure changes within the container to a different degree than the other set. This can be achieved by different curvature and/or size and/or different distance from a central longitudinal axis of the container. At least one of the panels has at least two different extents of curvature. In some embodiments one or more of the panels may be flat.

Claims

1. A container for accommodating volume contraction within the container after being filled with a heated liquid, having a sidewall portion including four flex panels spaced apart around the circumference of a body portion, and arranged as a first pair of opposed panels and a second pair of opposed panels, at least one of said flex panels having at least two different extents of curvature wherein the panels can deform inwardly to accommodate vacuum pressure caused by volume contraction of the heated liquid and wherein the panels are formed so the first pair of panels deforms inwardly at a different rate than the second pair of panels.

2. The container of claim 1 wherein one said pair of panels has a different amount of outward curvature to the other said pair of panels.

3. The container of claim 1 wherein one said pair of panels is substantially flat.

4. The container of claim 1 wherein one said pair of panels is substantially concave.

5. The container of claim 1 wherein one said pair of panels has a variable outward curvature.

6. The container of claim 1 wherein one said pair of panels has a generally even outward radius of curvature, excluding any ribs or grip features on said panels.

7. The container of claim 6 wherein one said pair of panels has a variable outward projection.

8. The container of claim 7 wherein a substantially central section of said panels projects outward to a greater extent.

9. The container of claim 7 wherein a substantially central section of said panels projects outward to a lesser extent.

10. A container substantially as herein described with reference to any of the embodiments of the invention and as shown in any one or more of the accompanying drawings.

11. The container of claim 1 wherein said at least two different extents of curvature comprise varying amounts of projection from a plane defined by a longitudinal axis of said at least one panel.

12. The container of claim 11 wherein a substantially constant arc of curvature is provided along said longitudinal axis of said at least one panel.

13. The container of claim 11 wherein a variable arc of curvature is provided along said longitudinal axis of said at least one panel.

Description

DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 shows a side view of the container showing the embodiment having a series of symmetrical ribs on the larger controlled deflection flex panels.

[0032] FIG. 2 shows a front view of the container shown in FIG. 1.

[0033] FIGS. 3a-c show rendered side, front, and perspective solid views of the container shown in FIGS. 1 and 2.

[0034] FIG. 4a shows a Finite Element Analysis view of the container shown in FIG. 1 under vacuum pressure Step One.

[0035] FIG. 4b shows a Finite Element Analysis view of the container shown in FIG. 2 under vacuum pressure Step One.

[0036] FIG. 5a shows a Finite Element Analysis view of the container shown in FIG. 1 under vacuum pressure Step Two.

[0037] FIG. 5b shows a Finite Element Analysis view of the container shown in FIG. 2 under vacuum pressure Step Two.

[0038] FIGS. 6a-e show Finite Element Analysis cross-sectional views through line B-B of the container shown in FIG. 1 under vacuum pressure Step One to Five.

[0039] FIGS. 7 a-e show front, side and cross-section views of an alternative embodiment of the container having 2 sets of panels having variable curvatures.

[0040] FIGS. 8 a-e show front, side and cross-section views of an alternative embodiment of the container having 2 sets of panels having variable projecting curvatures.

[0041] FIGS. 9 a-e show front, side and cross-section views of an alternative embodiment of the container having 2 sets of panels having variable curvatures.

[0042] FIGS. 10 a-e show front, side and cross-section views of an alternative embodiment of the container having 2 sets of panels with one set having an even outward curvature and one set having a variable outward curvature.

[0043] FIGS. 11 a-e show front, side and cross-section views of an alternative embodiment of the container having 2 sets of panels with one set of panels having variable outward curvatures and one set being substantially flat.

[0044] FIGS. 12 a-e show front, side and cross-section views of an alternative embodiment of the container having 2 sets of panels with one set of panels having variable projecting curvatures and one set being substantially flat.

[0045] FIGS. 13 a-e show front, side and cross-section views of an alternative embodiment of the container having 2 sets of panels with one set of panels having variable outward curvatures and one set of panels being substantially concave.

[0046] FIGS. 14 a-e show front, side and cross-section views of an alternative embodiment of the container having 2 sets of panels with one set of panels having even outward curvatures and one set of panels having variable inward curvatures.

DETAILED DESCRIPTION OF THE INVENTIONS

[0047] A thin-walled container in accordance with the present invention is intended to be filled with a liquid at a temperature above room temperature. According to the invention, a container may be formed from a plastic material such as polyethylene terephthalate (PET) or polyester. Preferably, the container is blow molded. The container can be filled by automated, high speed, hot-fill equipment known in the art.

[0048] Referring now to the drawings, a preferred embodiment of the container of this invention is indicated generally in FIG. 1, as generally having many of the well known features of hot-fill bottles. The container (1), which is generally round or oval in shape, has a longitudinal axis (C) when the container is standing upright on its base. The container comprises a threaded neck (5) for filling and dispensing fluid. Neck (5) also is sealable with a cap (not shown). The preferred container further comprises a substantially circular base (8) and a bell (4) located below neck (5) and above base (8). The container of the present invention also has a body (9) defined by substantially round sides containing a pair of narrower controlled deflection flex panels (2) and a pair of wider controlled deflection flex panels (3) that connect bell (4) and base (8). A label or labels can easily be applied to the bell area using methods that are well known to those skilled in the art, including shrink wrap labeling and adhesive methods. As applied, the label extends either around the entire bell of the container or extends over a portion of the label mounting area.

[0049] Generally, the substantially rectangular flex panels (3) containing one or more ribs (6) are those with a width greater than the pair of flex panels adjacent (2) in the body area (9). The placement of the controlled deflection flex panel (3) and the ribs (6) are such that the opposing sides are symmetrical. These flex panels (3) have rounded edges. The vacuum panels (3) permit the bottle to flex inwardly upon filling with the hot fluid, sealing, and subsequent cooling. The ribs (6) can have a rounded outer or inner edge, relative to the space defined by the sides of the container. The ribs typically extend most of the width of the side and are parallel with each other and the base. The width of these ribs is selected consistent with achieving the rib function. The number of ribs on either adjacent side can vary depending on container size, rib number, plastic composition, bottle filling conditions and expected contents. The placement of ribs on a side can also vary so long as the desired goal(s) associated with the interfunctioning of the ribbed flex panels and the non-ribbed flex panels is not lost. The ribs are also spaced apart from the upper and lower edges of the vacuum panels, respectively, and are placed to maximize their function. The ribs of each series are noncontinuous, i.e., they do not touch each other. Nor do they touch a panel edge.

[0050] The number of vacuum panels is variable. However, two symmetrical panels, each on the opposite sides of the container, are preferred. The controlled deflection flex panel (3) is substantially rectangular in shape and has a rounded upper edge (10) and a rounded lower edge (11).

[0051] As shown in FIG. 1, the narrower side contains the controlled deflection flex panel (2) that does not have rib strengthening. Of course, the panel (2) may also incorporate a number of ribs of varying length and configuration. It is also preferred that any ribs positioned on this side correspond in positioning and size to their counterparts on the opposite side of the container.

[0052] Each controlled deflection flex panel (2) is generally outwardly curved in cross-section. Further, the amount of outward curvature varies along the longitudinal length of the flex panel, such that response to vacuum pressure varies in different regions of the flex panel. FIG. 6a shows the outward curvature in cross-section through Line B-B of FIG. 1. A cross-section higher through the flex panel region, i.e. closer to the bell, would reveal the outward curvature to be less than through Line B-B, and a cross-section through the flex panel relatively low on the body and closer to the junction with the base of the container would reveal a greater outward curvature than through Line B-B.

[0053] Each controlled deflection flex panel (3) is also generally outwardly curved in cross-section. Similarly, the amount of outward curvature varies along the longitudinal length of the flex panel, such that response to vacuum pressure varies in different regions of the flex panel. FIG. 6a shows the outward curvature in cross-section through Line B-B of FIG. 1. A cross-section higher through the flex panel region, i.e. closer to the bell, would reveal the outward curvature to be less than through Line B-B, and a cross-section through the flex panel relatively low on the body and closer to the junction with the base of the container would reveal a greater outward curvature than through Line B-B.

[0054] Importantly, the amount of arc curvature contained within controlled deflection flex panel (2) is different to that contained within controlled deflection flex panel (3). This provides greater control over the movement of the larger flex panels (3) than would be the case if the panels (2) were not present or replaced by strengthened regions, or land areas or posts for example. By separating a pair of flex panels (3), which are disposed opposite each other, by a pair of flex panels (2), the amount of vacuum force generated against flex panels (3) during product contraction can be manipulated. In this way undue distortion of the major panels may be avoided.

[0055] In this preferred embodiment, the flex panels 2 provide for earlier response to vacuum pressure, thus removing pressure response necessity from flex panels 3. FIGS. 6a to 6e show gradual increases in vacuum pressure within the container. Flex panels (2) respond earlier and more aggressively than flex panels (3), despite the larger size of flex panels (3) which would normally provide most of the vacuum compensation within the container. Controlled deflection flex panels (2) invert and remain inverted as vacuum pressure increases. This results in full vacuum accommodation being achieved well before full potential is realized from the larger flex panels (3). Controlled deflection flex panels (3) may continue to be drawn inwardly should increased vacuum be experienced under aggressive conditions, such as greatly decreased temperature (deep refrigeration) or if the product is aged leading to increased migration of oxygen and other gases through the plastic sidewalls, also causing increased vacuum force.

[0056] The improved arrangement of the present invention provides for a greater potential for response to vacuum pressure than prior art. The container may be squeezed to expel contents as the larger panels (3) are squeezed toward each other, or even if the smaller panels (2) are squeezed toward each other. Release of squeeze pressure results in the container immediately returning to its intended shape rather than remain buckled or distorted. This is a result of having the opposing set of panels having a different response to vacuum pressure levels. In this way, one set of panels will always set the configuration for the container as a whole and not allow any redistribution of panel set that might normally occur otherwise.

[0057] Vacuum response is spread circumferentially throughout the container, but allows for efficient contraction of the sidewalls such that each pair of panels may be drawn toward each other without undue force being applied to the posts (7) separating each panel. This overall setup leads to less container distortion at all levels of vacuum pressure than prior art, and less sideways distortion as the larger panels are brought together. Further, a higher level of vacuum compensation is obtained through the employment of smaller vacuum panels set between the larger ones, than would otherwise be obtained by the larger ones alone. Without the smaller panels undue force would be applied to the posts by the contracting larger panels, which would take a less favourable orientation at higher vacuum levels.

[0058] The above is offered by way of example only, and the size, shape, and number of the panels (2) and the size, shape, and number of the panels (3), and the size, shape, and number of reinforcement ribs is related to the functional requirements of the size of the container, and could be increased or decreased from the values given.

[0059] FIGS. 7 a-e, show front, side and cross-section views of an alternative embodiment of the container having 2 sets of panels, the primary panels (2) having variable curvatures whereby their middle portion is relatively flat, or has a lesser amount of curvature than the portions in the upper or lower regions of the panel. The secondary panels (3) also have variable curvatures whereby the middle portion has a greater amount of curvature than the regions above and below. This middle region also projects outwardly to a lesser extent or degree than the region of the panel above or below. By providing a central portion having a greater amount of curvature, or a lesser radius of curvature, the central portion is somewhat strengthened against flexure compared to the regions having lesser amounts of curvature, or a greater radius of curvature.

[0060] By providing such variable curvatures within a panel, a great degree of control can be exhibited over the panel and how flexure occurs under vacuum pressure. A certain rate of flexure can be obtained with a high degree of accuracy.

[0061] Additionally, by providing for the secondary panel to have a lesser projecting region in the middle portion, the amount of resistance introduced already by the increased amount of curvature can be further modified. The lesser projection causes a degree of lesser resistance to vacuum pressure and ensures the central portion flexes at the correct rate.

[0062] The primary panels (2) have a lesser outwardly projecting portion in the centre, and this region also has a lesser amount of curve, or larger radius of curvature than the regions above and below. Therefore, the combined effect is to control the overall flexure of the four panels under vacuum pressure, such that the primary panels flex readily despite having a smaller surface area and being further displaced from the centerline than the secondary panels.

[0063] Importantly, the rate of flexure can be controlled between the 2 sets of panels to create a better balance and allowing the container to avoid uncontrolled collapse, and to provide for greater vacuum absorption.

[0064] As shown in FIGS. 8 a-e, 2 sets of panels having variable projecting curvatures whereby the primary panels (2) have a similar construction to the primary panels in FIGS. 7 a-e, but the secondary panels are constructed to respond at a slightly lower vacuum threshold than the secondary panels in FIGS. 7 a-e. This is achieved by having the secondary panels in this instance have the same radius of curvature through the middle portion rather than the smaller radius of curvature in FIGS. 7 a-e.

[0065] FIGS. 9 a-e show an alternative embodiment of the container again, having 2 sets of panels having variable curvatures. In this example the secondary panels (3) have a middle region that is further weakened against vacuum pressure by having a lesser amount of arc, or increased radius of curvature, than the regions above or below. Thus, the four panels are constructed in a similar manner to those in FIGS. 8 a-e, but the secondary panels will respond to vacuum pressures earlier by comparison.

[0066] FIGS. 10 a-e show an alternative embodiment of the container having 2 sets of panels with one set having an even outward curvature and one set having a variable outward curvature. By comparison to the previous example in FIGS. 9 a-e, the secondary panels (3) are somewhat more resistant to vacuum pressure as the middle portion shares a common radius of curvature, and a common projection with the regions above and beyond. This creates a panel that is stiffer and slower to respond to vacuum pressure. Subsequently, the primary panels (2) respond significantly faster than the secondary panels, but overall response within the container is different to all the previous examples.

[0067] FIGS. 11 a-e show a further alternative embodiment of the container having 2 sets of panels with one set of panels (3) having variable outward curvatures and one set of panels (2) being substantially flat. In this example the primary panels (2) will not have the same total volume extraction available as in the previous examples and will respond initially at a similar rate, but then slow in extraction and cause the secondary panels to in fact speed up in response to vacuum after the initial volume compensation is achieved.

[0068] FIGS. 12 a-e show another alternative embodiment of the container having 2 sets of panels with one set of panels having variable projecting curvatures and one set being substantially flat. Again, the combination provides for alternative speed responses between the panels.

[0069] FIGS. 13 a-e show front, side and cross-section views of an alternative embodiment of the container having 2 sets of panels with one set of panels having variable outward curvatures and one set of panels being substantially concave. In this embodiment, the primary panels react earlier to vacuum pressure due to being concave, particularly in the middle regions, but overall extraction from the primary panels is limited due to the lack of any outward curvature. This causes the secondary panels (3) to need to provide for a greater amount of the extraction required, whereby the panels are drawn closer to the centerline and therefore closer together, under vacuum pressure.

[0070] FIGS. 14 a-e show an alternative embodiment of the container having 2 sets of panels with one set of panels having even outward curvatures and one set of panels having variable inward curvatures. The primary panels (2) are particularly predisposed to reacting in the initial stages in this embodiment. The concavity is more pronounced in the middle portion, wherein the inward radius of curvature is smaller, such that this region reacts more quickly. The secondary panels are further configured to encourage this as they are more stiffly constructed, having a more even outward curvature. Thus, the secondary panels resist the early vacuum pressures at the same time the primary panels more readily respond to vacuum. This creates a greater difference in response at early stages of vacuum pressure between the panels.

[0071] It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

[0072] All references cited in this specification are hereby incorporated by reference. The discussion of the references herein is intended merely to summarize the assertions made by their authors and no admission is made that any reference constitutes prior art relevant to patentability and the applicant reserves the right to challenge the accuracy and pertinency of the cited references.

[0073] Although this invention has been described by way of example and with reference to possible embodiments thereof, it is to be understood that modifications or improvements may be made thereto without departing from the scope of the invention as defined in the appended claims.