Covered food container

Abstract

A food container comprising a tray section having a cover section of the same material is formed with secure latches constituted by portions of a strengthening rim on one of the sections which cooperate with slots in a depressed flute on an opposed section when the container is closed.

Description

BACKGROUND OF THE INVENTION

The invention is concerned with a preformed package of general utility but particularly adapted to enclosure of prepared foods. Illustrative examples herein include packaging of complete meals and of hot sandwiches such as hamburgers or other fillings of sandwiches utilizing buns.

Prepackaged prepared foods are presently available in a great variety of contained food products and nature of packages. Frozen foods, either raw or prepared, must be enclosed by means which inhibit transfer of gases and vapors, for example, to prevent excessive loss of moisture resulting in "freezer burn". It will be recognized from the description hereinafter that the package of this invention is not inherently vapor-tight, in fact, for some purposes herein discussed, it is desirable to afford a substantial measure of ventillation. Such packages may be enclosed by bags, coated wrappers or the like known in the art, if freezing is desired.

The invention is, accordingly, more in the field of permeable or ventilated packaging which may be optionally wrapped for freezer storage. Such packages may contain sandwiches, such as those on a bun in which the filling is anyone of a variety of tasty meats and other foods, e.g., hamburgers, cheeseburgers, barbecued beef or pork, chicken, fish, sliced beef, etc. Depending on the election of the consumer, the so packaged food may be consumed immediately on the sales premises (where permitted); carried to automobile, home or picnic grounds for consumption after a relatively short interval; stored under refrigeration for consumption within a few days; or frozen for storage over a longer period of time to be consumed at a time suiting the convenience or emergency of the consumer.

Some of such packages use metal trays or dishes, generally aluminum, of light gauge and low cost, suitable for discard after consumption of the contained food. Such packages are heated, when desired, in radiant heat ovens over a period of time suitably long for raising the interior of the food to a desired elevated temperature without application of such intense heat radiation as to adversely affect the surface of the food. These metal packages are not suited to rapid heating in microwave ovens.

Other known food packages are bags of metal foil, paper, plastic film and the like. These are very effective for "carry-out" foods, such as hamburgers. They provide essentially no protection of physical integrity of the contained food and must be handled with care to avoid abrasion, crushing or other mechanical impairment of surface, form and arrangement of elements of the food, all of which are detrimental to the original appetizing appearance of the food, if not of its nutritive value.

Plates and other dishes of greater depth are often formed of pulp or plastic. A more recent development, described in U.S. Pat. No. 3,684,633, Haase, provides a variety of tableware which is thermoformed of foamed plastic having a layer of plastic film on at least one surface. The technology so described is applicable to formation of plates, bowls, cups, saucers, in fact of tableware generally. Covers suitable for such vessels are described in copending application of N. D. Commisso, Ser. No. 271,864, filed July 14, 1972.

The rigid dishes of plastic, like those of china, glass etc., intended for repeated reuse may be covered by a sheet of protective material, such as foil, paper or plastic film to protect the contents from contamination. Such fragile elements leave the contents subject to physical damage or disarrangement, though to a lesser extent than the three-dimensional insecurity found with bags as above described.

SUMMARY OF THE INVENTION

A two piece container comprising a bottom member and a top member, at least the top member having a lower rim portion with a pair of depressions or flutes in the rim area which are separated about 180.degree. around the rim of the top member. The flute is further characterized by having a horizontal slot cut across its width. The slots in the flutes are adapted to lockingly engage horizontally projecting flange portions located around the upper periphery of the container bottom member. Although a wide variety of materials may be used to produce the containers of the present invention including polystyrene, impact or rubber modified polystyrene, foam polystyrene, polyethylene including low density and high density materials, polyvinylchloride, molded pulp and the like, polystyrene foam is a preferred material. Although a variety of forming techniques may be employed, however, when polystyrene foam is being used, thermoforming is a particularly preferred method of fabricating the containers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of one form of the container structure of the present invention.

FIG. 2 is an overhead planar view of only the top cover member of the container shown in FIG. 1.

FIG. 3 is a cross-sectional view taken on line 3--3 of FIG. 2.

FIG. 4 is an overhead planar view of only the bottom tray member of the container shown in FIG. 1.

FIG. 5 is a cross-sectional view taken on line 5--5 of FIG. 4.

FIG. 6 is an overhead planar view of the container structure shown in FIG. 1.

FIG. 7 is a cross-sectional view taken on line 7--7 of FIG. 6.

FIG. 8 is a schematic perspective view of another embodiment of the container structure of the present invention.

FIG. 9 is an overhead planar view of the container shown in FIG. 8.

FIG. 10 is a cross-sectional view taken through line 10--10 of FIG. 9.

DESCRIPTION OF SPECIFIC EMBODIMENTS

It is a principal object of the invention to provide a package, particularly for foods, which is readily fabricated on automatic, high-speed machinery of low cost materials having substantial heat insulating qualities. It is a further object that the open package, as supplied for filling and closing shall be nestable in the sense that a large number of empty packages can be stacked together, each within the cavities of an adjacent carton, such that the volume occupied is very little more than the sum of the thicknesses of walls of the packages. Such nesting results in major economies in shipping and storage. It is a further object that the empty packages be readily denested; that is, the empty packages in a stack should be capable of easy, rapid and uniformly smooth removal from the stack at either end for convenience and low cost of the filling and closing operation.

Further objects contemplated include easy latching of the package and a secure mechanical detent when latched. It is further contemplated that the package shall be easily opened when desired and that it be capable of reclosing and reopening many times without substantially impairing security of closure.

The invention has, as additional objects, a rugged structure resistant to mechanical damage and capable of protecting the contents of the closed package against air-borne contamination without major inhibition of ventilation; it being understood that the package may be totally enclosed by films or like which are impervious to gases and vapors. A still further object is of particular importance when the package is so enclosed. That further object is provision of a package free of sharp corners and spurs on its exterior to avoid damage to the carton by "catching on" fabrics or projecting elements and to avoid danger of puncture to enclosing films.

The achievement of all these objectives simultaneously requires a particular combination of structural elements as provided by this invention. Constraints on available options are imposed by such features as the need for production on high speed molding machinery to provide for manufacture at an acceptable cost.

Typical materials of construction which will provide the desired heat insulation and strength are foamed resins, such as foamed polystyrene, and pulp. The former is supplied as a web of foamed resin to a thermoformer in which the web is heated to a temperature high enough to permit reformation and drawing operations and is then pressed between cooled matching molds to the desired form. Pulp articles are formed from a suspension of paper fibers in water supplied to a screen conforming to the desired shape. A vacuum applied to the side of the screen opposite to the supply of water suspension causes the fibers to felt on the screen in the desired form. Upon drying, the finished product is removed from the screen.

Both forming operations here briefly described require that the form of the article be such that it is readily stripped at high speed from the forming element with a high degree of assurance. Faulty stripping of a single article, even to the extent of misalignment, results in jamming of the machine and costly shut-down to clear the jam. For that reason, surfaces of the formed article must be sloped such that stripping involves merely release from the surface of the forming element, as contrasted with sliding friction between surfaces parallel to the direction of withdrawal. There should be no undercuts, unless costly forming elements having retractable parts are provided.

These limitations on structure arising from the manner of manufacture are satisfied and the other objects are fulfilled by packages having features shown in the annexed drawings, wherein like parts are referred to by the same reference numerals.

A very useful form of the containers of the present invention is embodied in the "hamburger package" shown in the accompanying drawings. This structure is adapted for dispensing of the well-known hamburger constituted by ground beef in a bun and is subject to wide variation by addition of cheese, vegetables, condiments and the like. The package comprises a vessel 10 and a cover 11. In the embodiment of the invention illustrated in FIGS. 1 through 7 inclusive vessel 10 and cover 11 are of substantially identical structure. Such an arrangement allows an end user the convenience of stocking identical tray elements, two of which will combine to form the desired container. This is a real advantage over prior art containers where the top and bottom were of distinctly different structures forcing an end user to inventory both tray tops and tray bottoms.

Container members 10 and 11 are of generally rectangular shape in horizontal cross-section with rounded corners and curved, bulging sides. For the sake of clarity of description, the carton section which assumes the position as cover "top" member 11 will be described hereinbelow (FIGS. 2 and 3), it being understood that the container "bottom" member 10 (FIGS. 4 and 5) is identical in structure but has been inverted to "act" as the container bottom. The structural elements of the container bottom are identified by primed numerals and corresponding to the numerals which identify elements of the container top. The walls 13 of cover 11 slope outwardly from the top 14 to meet a horizontal flange 15 at the base of walls 13. As shown in FIGS. 1 and 2, on opposed sides of cover 11, flange 15 has a depending skirt 20. Skirt 20 is a downwardly depending extension of flange 15. The central portion of skirt 20 is depressed to form a flute 21. A slot 22 is punched through the flute 21 at this area of intersection such that, on closure of the package by bringing top member 11 in closing engagement with bottom member 10, the adjacent portions of flange 15 of bottom 10 are received into the pair of slots 22 at opposed ends of cover 11 while, simultaneously, opposed slots 22 on bottom member 10 receive adjacent flange portions 15 of top member 11. Thus a secure, four point lock is achieved between the sections which sercurely protects against inadvertant opening while slight outward digital pressure on depending skirt portions 20 by the user easily unlocks the container.

FIG. 6 is an overhead planar view of the container sections in assembled and locked position. Note that the depending skirt members 20, with their associated flutes 21 and slots 22, at opposed ends of cover 11 are spaced at about 90.degree. from the skirt members 20 on container bottom member 10.

Another embodiment of the container structures of the present invention is illustrated in FIGS. 8, 9, and 10. As more clearly shown in FIG. 8, the container comprises a cover member 31 and a bottom member 32. A container cover 31 and bottom member 32 are of generally rectangular shaped in horizontal cross-section with rounded corners and curved bulging sides. The walls 34 of the container slope outwardly and downwardly from the top 33 to meet rim member 38 which encircles the periphery of the lower portion of the cover top 34. Rim member 38 generally comprises a first horizontally projecting ledge, a secondly vertical wall member extending downwardly from the periphery of the first horizontal edge; and finally a third horizontal ledge projecting around the base of the second vertical ledge. This rim construction arrangement is clearly shown in FIG. 8. The container bottom number 32 shown in cross-section in FIG. 10 comprises a substantially flat base 39 and upwardly and outwardly extending wall members 20. A horizontal rim 35 projects outwardly around the upper periphery of wall members 40 container bottom member 32. On opposite side walls of cover member 38, a depressed flute 37 is formed in rim portion 38. Two of such depressed flutes 37 are located on rim 38 and are spaced 180.degree. apart. Each of said flutes 37 has a slot 36. Slot 36 is adapted to receive a portion of rim 35 located around the upper portion of bottom number 32. As clearly shown in FIGS. 8, 9 and 10, when top member is brought into locking engagement with bottom number 32, rim 38 expands slightly to allow for the passage over rim 35, and when rim 35 is adjacent to the slot 36 in flute 37, it projects therethrough, as shown in FIGS. 8 and 10. The container is now securely locked and may be easily reopened by applying digital pressure to draw flute 37 outwardly from engagement with rim 35.

While a presently preferred embodiment of the invention has been shown and described with particularity, it will be appreciated that various changes and modifications may suggest themselves to those of ordinary skill in the art upon being apprised of the present invention. It is intended to encompass all such changes and modifications that fall within the scope and spirit of the appended claims.

Claims

What is claimed is:

1. A packaging container which comprises (A) a container bottom member having four-side walls which flare upwardly and outwardly from a flat substantially rectangular, bottom wall, at least two opposite walls of said container bottom side walls terminating in a flange which projects outwardly in a horizontal plane from the upper edge of said bottom member side walls; and (B) a container cover member having a substantially flat rectangular top member having four downwardly depending and outwardly flaring side wall members, at least two opposite walls of said cover side wall members terminating in a flange which projects outwardly in a horizontal plane from the lower edge of said cover side walls and each of the alternate opposing side walls of said cover terminating in a depending skirt member which extends from the container cover side wall edge in a direction away from said cover; a recessed surface extending across the face of said skirt providing a flute across said face adapted to ride over the opposing portion of said bottom flange upon closure of the container; and a slot across said flute adapated to receive said opposing portion of said bottom flange upon closure of the container and thereby provide a mechanical latch.