Patent Application
20100018889
1. Field of the Invention
This invention relates generally to the field of packaging bulk products such as paint, bulk chemicals or bulk foodstuffs. More specifically, this invention relates to an improved stackable container assembly that is configured to ensure accurate positioning and registration between respective container assemblies when they are stacked.
2. Description of the Related Technology
In the past, bulk substances such as paint, bulk chemicals such as granular chlorine or bulk foodstuffs such as grains or sugar were typically packaged using rigid metal containers. Recently, however, plastic containers have been introduced for use in such applications.
Plastic containers tend to be less expensive than metal containers, but are not as strong and are more prone to flexure than a metal container of comparable volume. Such flexure may occur as a result of internal pressure changes relative to ambient external pressure, or as a result of physical loads that are applied to the containers. One common physical load that is applied to containers is the vertical top load that is created when like containers are stacked on top of each other. When plastic containers are stacked, it is very important that each container be accurately centered with respect to the underlying container so that forces are evenly distributed on the contact surfaces and in the sidewall portions of the respective containers. Asymmetry during stacking can contribute to container failure, particularly when exacerbated by unwanted flexure that is caused by other factors. In addition, accurate centering during stacking is important for aesthetic reasons, especially in retail settings.
A need exists for an improved plastic container assembly that is configured so as to ensure accurate registration during stacking and so as to minimize unwanted container distortion that might otherwise occur as a result of relative pressure changes between the interior of the container and ambient conditions.
Accordingly, it is an object of the invention to provide an improved plastic container assembly that is configured so as to ensure accurate registration during stacking and so as to minimize unwanted container distortion that might otherwise occur as a result of relative pressure changes between the interior of the container and ambient conditions.
In order to achieve the above and other objects of the invention, a stackable container assembly that is constructed according to a first aspect of the invention includes a main body; an upstanding rim portion having an upper surface; and a flexible bottom portion, the flexible bottom portion having a lower surface comprising at least one support surface for supporting the container assembly on a horizontal surface, the lower surface further comprising at least one projection that is disposed radially inwardly from the support surface, and wherein the flexible bottom portion is configured so that the projection will flex downwardly into a position that is adjacent to an upstanding rim portion of an underlying container assembly when said container assembly is stacked on top of another container assembly.
According to a second aspect of the invention, a stackable container assembly includes a main body; an upstanding rim portion having an upper surface; and a flexible bottom portion, the flexible bottom portion having a lower surface comprising at least one support surface for supporting the container assembly on a horizontal surface, the lower surface further comprising at least one projection that is disposed radially inwardly from the support surface, and wherein the flexible bottom portion is configured so that the projection will flex radially outwardly into a position that is adjacent to an upstanding rim portion of an underlying container assembly when the container assembly is stacked on top of another container assembly.
A stackable container assembly according to a third aspect of the invention includes a main body; a removable lid portion, the removable lid portion comprising an upstanding rim portion having an upper surface, the removable lid portion further comprising a flexible diaphragm that is constructed and arranged to accommodate relative pressure changes between an interior of said container assembly and ambient conditions by flexing, whereby flexure of the rest of the container assembly as a result of such relative pressure changes is minimized; and a flexible bottom portion, the flexible bottom portion having a lower surface comprising at least one support surface for supporting said container assembly on a horizontal surface, the lower surface further comprising at least one projection that is disposed radially inwardly from the support surface, and wherein the flexible bottom portion is configured so that the projection will flex into a position that is adjacent to an upstanding rim portion of an underlying container assembly when the container assembly is stacked on top of another container assembly.
These and various other advantages and features of novelty that characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.
Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views, and referring in particular to
The removable lid portion 14 preferably has a flexible diaphragm 15 that is constructed and arranged to accommodate relative pressure changes between an interior of the container assembly 10 and ambient conditions by flexing. As a result, flexure of the rest of the container assembly 10 as a result of such relative pressure changes will be minimized.
The entire stackable container assembly 10 is preferably fabricated from a plastic material such as polyethylene or polypropylene. Alternatively, a portion of the stackable container assembly 10 could be constructed from a metallic material, while the rest of the container assembly is fabricated from a plastic material. For example, the removable lid portion 14 could be constructed from a metallic material such as steel.
Stackable container assembly 10 further preferably includes a flexible bottom portion 18 that has a lower surface 20 that defines at least one support surface 22 for supporting the container assembly 10 on a horizontal surface. In the preferred embodiment, support surface 22 is configured as an annular standing ring. Alternatively, however, support surface 22 could be constructed as a plurality of support feet, or other structure that is not continuous about the periphery of the flexible bottom portion 18.
Flexible bottom portion 18 is further configured so as to define at least one projection 24 that is disposed radially inwardly from the support surface 22. The flexible bottom portion 18 is constructed so that the projection 24 will flex downwardly and radially outwardly in response to the weight of material within the container into a position that is adjacent to the upstanding rim portion 16 of an underlying container assembly 10 when the container assembly 10 is stacked on top of another container assembly 10.
In the preferred embodiment of the invention, a plurality of projections 24 are provided. Specifically, four projections 24 that are discontinuous with respect to reach other are symmetrically provided within an annular area on the flexible bottom portion 18 that is positioned radially inwardly from the support surface 22. This contributes to ensuring secure and accurate registration of the container assemblies 10 during stacking by providing secure guidance between the flexible bottom portion 18 of one container and the upstanding rim portion 16 of an underlying container. In the preferred embodiment, each projection 24 has a symmetrical counterpart position diametrically opposite on the other side of the flexible bottom portion 18. Alternatively, the projections could be asymmetrically positioned, such as may be the case if an odd number of projections were provided. Symmetrical positioning is preferred if there are an even number of projections. As few as two projections could be provided.
As is best shown in
In the preferred embodiment of the invention that is shown in
As may also be visualized by viewing
Preferably, the upper surface 17 of the upstanding rim portion 16 is substantially flat, and the support surface 22 is convexly curved. When the convexly curved support surface 22 contacts the substantially flat upper surface 17, a camming or rocking action is created that urges the adjacent part of the flexible bottom portion 18, including the projection 24, to pivot about the point of contact will tend to move the projection 24 downwardly and radially outwardly toward the second contact surface 28 of the upstanding rim portion 16. The projections 24 will accordingly end up adjacent to the second contact surface 28 but will preferably not all be in contact with the second contact surface 28 after this movement. Some portions may make contact, but the primary function of the projections 24 is to be a positioning guide, which does not require continuous contact.
In the preferred embodiment, the support surface 22 extends downwardly beyond the projection 24 when the container assembly 10 is not stacked on top of another container assembly 10. Accordingly, when the container assembly 10 is placed on a flat horizontal surface it will be supported solely by the support surface 22, and the projections 24 will not make contact with the horizontal surface.
Alternatively, the projections 24 could be formed to extend downwardly in response to the weight of the container assembly to an extent where they will also make contact with the horizontal surface when sufficient weight is provided within the container assembly 10.
In another alternative embodiment, the support surface 22 will extend downwardly about the same extent as the projection 24 when the container assembly 10 is not stacked on top of another container assembly 10. The support surface 22 and the projection 24 would in this embodiment be positioned substantially within a common horizontal plane when the container assembly 10 is not stacked on top of another container assembly 10.
Referring now to
Although in the preferred embodiments the upstanding rim portions are located on a removable lid, it should be understood that they could alternatively be part of the upper portion of the main body of the container.
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.
