Container for shipping perishables

Abstract

A closable box of insulating material spacedly surrounds a closed compartment having walls of heat-transmitting material. Dry ice is supported in the box above the compartment and as it sublimes carbon dioxide passes down around the compartment to cool perishables enclosed therein and exits from the box through an outlet opening in the floor thereof which is of variable cross-sectional area. The compartment is made of sheet metal and has one open side snugly pressing against an openable insulating door constituting a side of the box. This door is formed with at least one small pressure-equalization orifice opening into the freight compartment.

Description

FIELD OF THE INVENTION

The present invention relates to a shipping container for a perishable fare shipment. More particularly this invention concerns an insulated cold-type container for air freight.

BACKGROUND OF THE INVENTION

In the shipping of perishable foodstuffs, chemicals, and pharmaceuticals it is often necessary to refrigerate the freight to a temperature well below 0.degree.C.

As a rule it is possible to surround the freight completely with carbon dioxide (CO.sub.2) so that such freight is simply loaded loosely into refrigerated containers and so-called dry ice is placed on top of the freight and the container is closed. Dry ice is solidified carbon dioxide which suplimes at a minus 78.5.degree.C so that outlet holes are provided in the insulated container to allow the evolved gas to escape. With foodstuffs it is often desirable to surround them with carbon dioxide gas, since this provides an atmosphere which inhibits the growth of many undesirable organisms. Many chemical products, however, should not be exposed to such gas, so that they must be packed in airtight containers within the shipping container. This double packing is expensive and time-consuming, and also is rarely highly effective as the packages tend to draw in the surrounding gas as they are cooled and their interior pressure drops.

OBJECTS OF THE INVENTION

It is therefore an object of the present invention to provide an improved cold-type shipping container.

Another object is the provision of such container which will maintain the enclosed freight at a very low temperature, but wherein gas evolving from the cooling means is kept out of contact with the freight.

A further object is an insulated air freight container which is inexpensive to make and easy to use for the shipment of refrigerated freight.

SUMMARY OF THE INVENTION

These objects are attained according to the present invention in a shipping container comprising an outer box in which the freight is held in a compartment which is substantially closed. An ice compartment above the freight compartment holds the ice and a vertical passage is provided in the chamber formed by the box next to the freight compartment and terminating at the floor of the box in an outlet opening into the outside. The ice melts as sublimes and evolves fluid which flows down in the passage past the freight compartment and then leaves the box through the outlet.

Thus the objects to be shipped are enclosed in the freight compartment which is cooled by the fluid evolved from the ice in an overhead compartment as this fluid runs down past the freight compartment. The fluid exits from the container after it has been warmed up by the freight compartment. Of course once the temperature is dropped to a sufficiently low level the ice will melt or sublime very slowly, only fast enough to compensate for heat leakage through the walls of the container.

According to other features of this invention the box has walls made of insulating material and the compartment has walls made of heat-conducting material such as metal so that little heat is picked up through the walls of the box, but much is passed through the compartment walls. The freight compartment has at least two side walls spaced inwardly from two respective side walls of the box. The space between these side walls is the passage, and a similar space is provided between the bottom wall of the freight compartment and the bottom wall of the box with the outlet in the middle of the box bottom wall. The compartment and the box are both rectangularly parallelopipedal with at least one side of the compartment being one side of the box, this side constituting an openable portion allowing the freight compartment to be loaded. The ice compartment is formed between an openable cover forming a top wall of the box and a screen or perforated support overlying the freight compartment.

In accordance with further features of this invention the outlet is of variable cross-sectional area so that the flow rate through it can be varied to in turn vary the cooling rate. The freight compartment is vented to the outside also so as to prevent cooling of this compartment from sucking evolved carbon dioxide in as a result of a pressure drop in the freight compartment. The outlet according to yet another feature of the present invention can be connected to an apparatus which collects the cold carbon dioxide and uses it to precool, impregnate, or otherwise treat articles such as foodstuffs about to be loaded into other containers.

DESCRIPTION OF THE DRAWING

The above and other objects, features, and advantages of the invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is a vertical section partly in schematic form through a container according to the present invention; and

FIG. 2 is a horizontal section through the container.

SPECIFIC DESCRIPTION

The container comprises basically a box 10 having side walls 11a-d, a bottom wall 11e, and a top wall formed as a cover 12 hinged at 24. This box 10 is formed of heat-insulating material such as rigid polystyrene foam lined internally with a reflective coating 25. The upper part of the box 10 is formed by a removable collar 26 which defines an ice compartment 14. A plate 13 secured to the walls 11a-c is formed along these walls with notches 13a and is provided with short spacers 27 which support a perforated metal sheet 16 along with a central holding pin 28. A mass of frozen carbon dioxide 15 is supported on the plate 16 in the compartment 14 bounded by walls 11a-d, the plate 13, and the cover 12.

A freight compartment is formed in the housing 10 between three side walls 19a-c of sheet metal, a bottom wall 18 also of sheet metal, and a metal top wall 20 under which is supported an insulating top wall 21. The walls 19a-c are spaced inwardly of the walls 11a-c and spacers 19f serve to maintain this spacing constant and define three vertical passages 23a-c which are connected through the cutout portions 13a to the upper compartment 14. Rollers 18a support the bottom wall 18 of the compartment 17 on the bottom wall 11e of the outer box 10. The walls 19 b and 19c are provided with upper racks 19 d formed as inwardly bent ridges and with lower racks 19 e formed of brackets welded to the interiors of these walls, plates 22 serving to support objects 0 in the freight compartment 17. The compartment 17 is open on one side and the walls 19b, 19c, 20, 21 and 18 all snugly abut this wall 11d of the box 10 so that this side 11d, which is actually a door hinged at 30, forms a side of both the ice compartment 14, the freight compartment 17, and forms ends of the passages 23b and 23c. Small holes 29 are formed in the upper third of the hinged door 11d. It should be noted that the wall 11a can also be formed as a door, in which case the compartment 17 would be opened at both ends and the space 23 a and wall 19a would not exist.

The bottom wall 11e of the box 10 is formed with a central hole 10a which is at least partially blocked by an apertured plug 10b having a central hole 10b' whose cross-sectional area determines the amount of fluid, gas or liquid, that can flow out of the compartment 14 through the passages 23a-c which terminate at the passage 24 between walls 18 and 11e. As the dry ice 15 sublimes, carbon dioxide gas, which is substantially denser than air, passes through the perforated plate 16 and descends from the compartment 14 through the notches 13a in all three passages 23a-c, collecting in the passage 24 and passing out of the box 10 through the hole 10b' in the plug 10b. Since the walls 23a-c are thermally insulating and reflective, and the walls 23a-c are thermally conductive, this evolving fluid takes on heat from the freight compartment 17, thereby cooling the objects 0 on the shelves 22. The cooling rate is partially dependent on the size of orifice 10b', so that before the compartment 17 is loaded in place the packer merely inserts the appropriately sized plug 10b in the hole 10a, in this manner having a simple means of controlling the cooling. The freight compartment 17 can breathe through the holes 29 so that as its contents are cooled it will not suck carbon dioxide in.

It is possible as shown at 31 to catch the evolved carbon dioxide, and use this gas for example to precool other containers before they are charged with particulate dry ice as shown at 15, to serve as a protective gas or to form an impregnating gas.

Claims

We claim:

1. A shipping container comprising: an outer box forming a substantially closed chamber having a base formed with an outlet opening outside said box and into said chamber;

means in said chamber forming a substantially closed compartment adapted to receive freight;

means in said chamber above the freight compartment for supporting ice and forming an ice compartment;

means in said chamber defining a vertical passage next to and in heat-exchanging juxtaposition with said freight compartment and extending downwardly therepast from said ice compartment to said outlet, whereby fluid evolved from ice in said ice compartment flows down in said passage over said freight compartment to cool same and flows out of said chamber at said outlet, said box having a plurality of connected side walls, a top wall bridging said side walls above said ice compartment, and a bottom wall bridging said side walls below said freight compartment at said base, said walls being of insulating material, said means forming said freight compartment having at least two side walls spaced from two respective side walls of said box, a bottom wall spaced from the box bottom wall, and a top wall spaced from the box top wall and defining therewith said ice compartment, said side walls of said freight compartment beigh of heat-conducting material, said outlet being a throughgoing hole in the box bottom wall, said means forming said ice compartment including a rigid perforated support plate for said ice secured to said box side walls, at least one of the box side walls constituting a side wall of said compartment and being formed with an openable door, the latter wall being formed with at least one throughgoing hole opening on one side into said freight compartment and on the other side outside said box;

means for collecting gas leaving said box through said outlet; and

means for controlling the rate of evolution of fluid in said container by varying the cross-section of said outlet.