GB2193301A

GB2193301A - A heat insulated container

Info

Publication number: GB2193301A
Application number: GB08714158A
Authority: GB
Inventors: Alan John Austin
Original assignee: AJA REFRIGERATION Ltd
Current assignee: AJA REFRIGERATION Ltd
Priority date: 1986-06-17
Filing date: 1987-06-17
Publication date: 1988-02-03
Also published as: GB8714158D0

Abstract

A heat insulated container (10) to be used for carrying commercial loads has a lid (12) with a tank (22) containing a refrigerant liquid which does not completely fill it. The tank is removed for cooling but the liquid (e.g. a glycol) is not frozen so it can flow within the tank to maximise cooling. Containers with chilled or frozen goods can be dropped off at different destinations. Alternatively, a larger container can have a non- removable tank, with inlet and outlet for the replacement of the liquid with fresh chilled liquid. <IMAGE>

Description

SPECIFICATION A heat insulated container This invention relates to heat insulated containers, suitable in particular for the transport of goods.

Refrigerated vehicles are known which carry a refrigeration plant on board, and have an insulated container which is chilled by the plant. Such vehicles can be of any size, but whatever the size of container available it is often too large and is used wastefully at the same time for carrying non-perishable goods.

On any one vehicle, the refrigerated space is predetermined.

At the domestic level, insulated containers are known which are portable and used for picnics, drinks and the like. These are not themselves refrigerated or chilled, and rely upon the insertion in the container, with the contents, of a removable pre-chilled cooling block. This is normally a sealed plastic container of water which is frozen in a domestic freezer.

The invention aims to reduce the capital and running cost of chilled transport on vehicles, by the use of insulated containers without vehicle borne refrigeration plant.

Accordingly, the invention provides a heat insulated container having insulated walls, floor and top, wherein at least the top includes a tank or set of tanks containing a liquid of low freezing point which largely but not completely fills the tank or tanks.

In a preferred form, the liquid tank has an inlet and an outlet connection which allow the contents to be extracted and fresh chilled liquid to be fed in.

In order that the invention shall be clearly understood, an exemplary embodiment thereof will now be described with reference to the accompanying drawing, in which: Figure 1 shows a section in a vertical plane through an insulated container according to the invention; and Figure 2 shows a section at a corner, to an enlarged scale.

An insulated container 10 consists of a box 11 and a lid 12. The box 11 is formed by an outer skin 13 of sheet aluminium, reinforced if required at corners and/or edges, an insulating layer 14 of polyurethane foam, and an inner skin 15 of stainless steel. The top edge of the box 11 is capped all the way round by a plastics moulding 16 which is slightly resilient and forms both a seal over the sandwich wall construction and a sealing surface to receive the lid 12.

The lid 12 has an outer skin 20 of aluminium, also reinforced if required, and an insulating layer 21 of polyurethane foam. A sealed metal tank 22, preferably stainless steel, fits exactly into the recess formed by the insulating layer 21 within the lid. The tank 22 thus forms the whole inner layer of the lid, and contains a liquid of low freezing point, preferably glycol. A spring metal strip 23 extends around the lower edge of the lid, having an upturned rim 24 and a down-turned lip 25.

The strip 23 extends very slightly over the edge of the tank 22, thus holding it in position. It can also be seen that the lip 25 lies above the inner edge 17 of the moulding 16.

As a result, when the strip 23 is rested on moulding 16, edge 17 meets lip 25 first and forces it resiliently upwards forming an airtight seal. The container has any suitable, e.g overcentre locking closures (not shown).

The dimensions of an insulated box which would be commercially useful and portable are 1 metre high and 1 metres80 cms in extent.

In use, the whole lid 12 including the sealed tank is placed for some hours e.g. overnight, in a cold store or chest freezer. This cools the liquid in the tank which however does not freeze. Perishable goods such as meat can be placed in the box 11 and the lid 12 then clamped in place. The full container can be loaded by two men in a van or on a lorry. It is strong enough to be stacked.

The chilled glycol will absorb heat from the contents, keeping them cool, and the insulation layer prevents heat entering. The contents can therefore be transported for a number of hours without deterioration. The small container size has the advantage compared with a single refrigerated vehicle body that limited quantities of goods can be delivered to a number of different destinations, one container being dropped at each. The clamps can be locked to prevent tampering or theft, so allowing deliveries at times when expert personnel are not present.

Because the glycol remains liquid its cooling effect is much more efficient since convection currents within the liquid ailow continuous removal of heat.

Preferably, the tank is not completely full e.g. 5% air space is left, so that on movement of the container the liquid will flow about the tank. This also promotes efficient cooling over the whole area of the lid.

If a larger container is required it may not be feasible to physically lift it on and off a vehicle. In that case a different arrangement is required. The lid with its tank must become a fixed top or roof, and access be provided from a side. The door(s) must be insulated.

The tank which may now for reasons of weight and manufacturing difficulties be split into separate sections, is provided with a liquid inlet and outlet both with shut-off valves.

A static supply tank of chilled glycol with a refrigerator unit is maintained at suitable places e.g. at the garage of the proprietor, or at a seaport. When cooling of a container is required, the connections are made to the inlet and outlet and the glycol in the tank is caused to flow out. Fresh pre-chilled glycol is then put in its place, and the container is then ready.

There may be more than one container on a single vehicle which can then be chilled by different amounts or at different times. Alternatively, only one part of a vehicle body may be an insulated container, the remainder being for transport of goods not needing to be chilled.

In certain circumstances, it may be advantageous to form also the floor of the container with a coolant tank, either removable or fixed.

In order to cope with the expansion and contraction of the tank 22, it may be designed with a slight spacing around it, instead of being an exact fit in the recess in the insulating layer 21.

In some cases the lid can be rather too large to fit in some refrigeration units or freezers.

To meet this problem, the tank or set of tanks may be removable from the box top so that it can be more conveniently put in a freezer. The tank(s) can be of plastics material, rather than stainless steel. In a preferred form, there are two tanks side-by-side, held in place by a stainless steel sheet which forms the inner surface of the lid. The sheet may have hinges along one side, and catches at the opposite side, which together allow the sheet to be opened and closed for removing and replacing the tanks. The sheet then acts as the hygienic inner surface of the box.

In a further modification, the lid, which may be hinged or still be completely removable, has a plastics material seal around its outer edge to mate with the top edges of the sides of the box. In addition, the four top corners of the lid may be provided with corner pieces which project upwardly to locate a box stacked on top and to prevent it siiding off.

Claims

1. A heat insulated container having insulated walls, floor and top, wherein at least the top includes a tank or set of tanks containing a liquid of low freezing point which largely but not completely fills the tank or tanks.

2. A heat insulated container as claimed in claim 1 wherein the top is completely removable from the container.

3. A heat insulated container as claimed in claim 1 or 2 wherein the tank or tanks is/are removable from the top.

4. A heat insulated container as claimed in any preceding claim wherein each tank has a valved inlet and outlet for the liquid which allows the warmed liquid to be replaced by freshly cooled liquid.

5. A heat insulated container as claimed in claim 1 wherein the tank or tanks has/have a surface facing the inside of the container made of stainless steel.

6. A heat insulated container as claimed in claim 3 wherein the tank or tanks in the top are covered by a stainless steel sheet which forms the inside surface of the container on that side.

7. A heat insulated container as claimed in claim 6 wherein the stainless steel sheet is openable and held in place by clips.

8. A heat insulated container as claimed in claim 4 wheren appendent to claim 1, whereinn the container is built onto the chassis of a vehicle, and access to the inside of the container is by a door or doors in the walls.

9. A vehicle having a heat insulated container as claimed in claim 8, the container forming only a part of the load carrying capacity of the vehicle.

10. A heat insulated container substantially as herein described with reference to the accompanying drawings.