GB2089325A - Immobilizing a load within a container - Google Patents

Abstract

In packaging a load within a container having well-defined rigid edges (2) and a base (1) the load to be packaged is placed on the base (1) and at least one sealed deformable membrane (5) is located between the load and the rigid edges (2) of the container. A pressure difference is then established between across the membrane (5) preferably by creating a vacuum within the interior (10) of the container such that the membrane (5) presses against the load and presses the load against the base (1). <IMAGE>

Description

SPECIFICATION A method and apparatus for packaging a load The present invention relates to a method and apparatus for packaging loads in a container having a well-defined rigid contour.

The term "container" is to be understood hereinafter and in the claims to mean an enclosure such as a transportation container, a lorry body, a ship's hold, an aircraft hold, a tank, a silo etc., and generally any container able to serve for packing a product, whether the latter is generally in a solid, powdered or more or less liquid form. The term "container having a well-defined rigid contour" is to be understood to mean a container whereof at least the edges are rigid and occupy relative stable positions.

Conventional containers of this type comprise rigid walls occupying relative stable positions, which walls define internally a constant volume inside which the product to be packed is directly placed.

It is known that the immobilization of a load inside an enclosure frequently causes problems, if the load does not occupy the entire inner volume of the enclosure. Such immobilization is essential if, during transportation, one wishes to prevent accidental movements which in certain cases would mean a danger of damaging the load and would render this transportation dangerous by throwing the load off balance.

If the load is in the form of a rigid block, it is immobilized by being fastened with ties which are also secured to the walls of the container, an operation which is tedious and sometimes difficult to carry out and which also requires the provision of anchorage points inside the container. When the packed load is in a powdered form, loose or in a more or less liquid state, its immobilization is virtually impossible.

Furthermore, currently known containers are not easily evacuated of air to create a vacuum in order to allow direct packing of loads at a pressure less than atmospheric pressure.

In fact it is difficult to seal conventional containers in an adequate manner. In view of the fact that the walls of these containers are usually constructed with just sufficient strength to withstand the static and dynamic stresses generated by the material container therein, i.e. the stresses due to the pressure of the material on the walls, in order to keep the actual weight of the container to a minimum, they would not withstand the additional stresses imposed by creation of a vacuum in their inside. Containers with rigid walls intended to withstand a vacuum are generally very heavy, since their walls have a considerable thickness in order to be sufficiently rigid to withstand the atmospheric pressure which is exerted on the outer sides and which results in stresses which are proportional in size to the volume of the enclosure.Despite the advantage of keeping certain products under vacuum, it would generally be inconceivable to construct rigid enclosures to withstand a vacuum and which are intended for transporation, since their weight would remove the advantage of the ease and cost of this transportation.

The object of the present invention is to overcome or substantially mitigate the aforementioned drawbacks.

According to a first aspect of the present invention there is provided a method for packaging a load comprising the steps of providing a container having a well-defined rigid contour and a base locating a load within the container, locating at least one sealed deformable membrane between the load and the said contour, and establishing a pressure difference between the sides of the membrane such that the membrane presses against the load and presses the load against the base of the container.

According to a second aspect of the present invention there is provided apparatus for packaging a load, comprising a container defining a base and rigid edges, at least one sealed deformable membrane located within the container and defining therein two regions whereof one is also defined by the base and defines a first chamber able to receive the load, and means for applying a pressure difference between the sides of the membrane such that the membrane tends to reduce the volume of the said chamber and to be pressed against the load when located therein.

The method facilitates the immobilization of the load in the container. Furthermore, if a sealed chamber is defined by means of the membrane and certain areas of the wall of the container, around the load to be packaged, which is much easier to achieve effectively than establishment of a good seal between the rigid walls of a traditional container, it is possible to create a vacuum in the enclosure thus defined, on the one hand for pressing the membrane against the load and on the other hand for ensuring packaging of the latter under vacuum.Means may thus be provided for maintaining this vacuum over a period of time, after packaging either at a fixed point in a storage area, or on the various appliances used for transporting the container, or even in the form of a self-contained pump permanently connected to the container with a pressure gauge to control the pressure within the container. If the vacuum maintained in this way is sufficiently great, this pump also ensures slow dehydration of the product, i.e.

a dehydration in the vapour phase excluding any type of mould, even when the packed product tends particularly towards this, as in the case of-cocoa for example.

Despite the above the container may still be constructed with a reduced weight over conventional containers since it is possible to employ a set of sectional members forming its edges and to a floor for supporting the load and against which the membrane presses the latter. In particular, the very heavy rigid walls of currently known containers intended for packing under vacuum are no longer necessary, since the stresses owing to the vacuum act on the flexible membrane and on the floor of the container.

Nevertheless, the container still has a rigid well-defined contour, suitable for allowing stacking and juxtaposition of severai containers in a traditional manner, in the case where they are constructed as transporation containers.

Furthermore, it may be noted that it is easy and inexpensive to equip all existing containers of rigid well-defined contour, according to the invention.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a perspective view, in partial section, of a container according to the invention; Figure 2 is a transverse sectional view of the container shown in Fig. 1 after filling but before the creation of a vacuum therein; Figure 3 is a view similar to that of Fig. 2, after creation of the vacuum; Figure 4 is a view similar to that of Fig. 3 showing the packaging of a different load; and Figures 5 and 6 are similar views respectively to those of Figs. 2 and 3, showing a variation of the invention.

Fig. 1 shows a container of standardised type, for transportation by boat, railway and lorry. Externally this container has the known parallelepipedal shape, with a standardised length of 20 or 40 feet, other shapes of container naturally being able to be used without diverging from the scope of the invention.

This container comprises a rigid rectangular horizontal base 1, connected to the periphery of which in an integral manner is a rigid framework 2 formed by connected rigid sectional members defining in particular the various horizontal and vertical edges of the container. The spaces existing between the sectional members of the framework 2 corresponding to the same side of the container are closed off by rigid walls 3 provided with orifices 4 allowing a free circulation of air therethrough, which walls could also be absent or replaced by canvas sheets, gratings, lattice work, since the sole function of these walls is to protect them against impact and to prevent the perforation of the flexible impermeable membranes and in the example illustrated elastically extensible membranes 5 which line them in this example over virtually their entire surface area, on the inside of the container.These membranes 5 are made for example from rubber, this material being able to undergo an elongation of up to 800%.

The membranes 5 are connected by their respective periphery to the framework 2 in the vicinity of the edges of the container and also in the immediate vicinity of the periphery of the base 1 of the latter. On the other hand, on certain walls, the framework 2 demarcates and reinforces orifices respectively filling orifices 6 and emptying orifices 7, provided in these walls 3 and in the areas of the membranes 5 opposite thereto, the membranes 5 are connected to the walls 3 and the framework 2 at the periphery of these orifices.

When they are not in use, i.e. respectively outside filling and emptying periods, these orifices 6 and 7 are closed in a tight manner respectively by covers 8 or by a door 9 preferably made from rigid materials and provided with gaskets on their periphery.

Advantageously, in the example illustrated, the filling orifices 8 are provided on the upper side of the container, in order to allow filling by gravity and the orifice 7 is provided in the lower part of one of the small vertical sides of the container, in order to allow emptying of the latter by tipping. In this case it is a question of a container more particularly intended for conveying powdery materials in bulk, but naturally, without diverging from the scope of the invention, one could adapt the example described to the case where one wishes to pack other types of materials.

The connection of the various hermetic membranes 5 to each other, possibly by the intermediary of certain areas of the framework 2 and with the base 1 itself gas tight is ensured in an equally gas-tight manner, so that the membranes 5, the base 1, the covers 8 and the door 9 define a sealed chamber 10 inside the container, which is able to receive the product to be packed In the example illustrated, this product is introduced into the chamber 10 through the orifices 6, the door 9 being closed then, when all the product to be packed is located inside the chamber 10, whether or not the latter is completely full, the covers 8 are closed then a vacuum is created inside the chamber 10. In view of the fact that the side of the membranes 5 facing the rigid walls 3 remains at atmospheric pressure owing to the presence of the orifices 4 in these walls 3, this creation of a vacuum puts the inner side of the membranes 5 under reduced pressure with respect to their side facing the wall 3, which due to progressive extension of these membranes 5 has the effect of causing a movement of the latter in their area located between their regions of connection to the framework 2, until they are pressed against the product to be packed and press the latter against the rigid base 1 of the container.

Fig. 2 shows the state of the system after the material 11 to be packed has been introduced into the chamber 10. Fig. 3 shows the state of the system after a sufficient vacuum has been created inside the chamber 10 in order to press the membranes 5 against the product 11 and the product against the base 1 of the container.

The creation of the vacuum within the chamber 10 is advantageously carried out in an area where the membranes 5 are connected to the framework 2, or through the covers 8 or the door 9 of the container. The pump used for creating this vacuum within the chamber 10 may be independent of the container and for example carried by a vehicle or appliance intended for conveying the latter, or may even form part of a fixed or movable installation. Advantageously, this pump may form an integral part of the container, as in the example illustrated where the suction pump 1 2 is housed within the framework 2 in the immediate vicinity of one of the transverse ends of the container, outside the chamber 10.

It is thus possible to maintain the vacuum created within the chamber 10 at the time of packing of the product 11, automatically over a period of time by locating a pressure gauge inside the chamber 10, which gauge controls the operation of this pump 1 2. The latter thus ensures progressive removal of gas from the material 11 in the chamber 10, the resulting decrease in the apparent volume of the material 11 resulting in a further movement of the membrane 5 inwards.

It should be noted that effective pressing of the membranes 5 against the material 11 and of this material 11 against the base 1 of the container is obtained even if, before creating the vacuum in the chamber 10, this chamber 10 were not completely filled with material 11. In fact, the membranes 5, made from rubber, extensible plastics material or any other similar product, have an extensibility such that an effect of this type can be obtained even if the chamber 10 were initially only half filled.

It should be noted that the fact that the membranes 5 press the material 11 forcibly against the base 1 of the container, tends to make this base rigid, which base may be constructed in a much lighter form than if one wished to produce a container with rigid sealed walls, required to withstand an internal reduced pressure of equal value.

These figures are given as a non-limiting example and good results have been obtained in tests by increasing the vacuum inside the chamber 10 up to a value of the order of 1 mum Hg.

When one wishes to empty the container, the vacuum inside the chamber 10 is broken, the membranes 5 thus resuming their initial shape illustrated in Fig. 2, then the door 9 is opened and the container is tipped in order to empty the latter by gravity.

According to a variation of the container.

the membranes 5 would not be extensible but, connected to the framework 2 of the container in the same manner as the extensible membranes described above, would have shapes and dimensions such that they are able to project towards the inside of the container when the chamber 10 is placed under vacuum.

The container which has been described can be used not only for packing powdered materials in bulk, as in the example illustrated in Figs. 2 and 3, but also for packing monolithic products such as machines, statues etc.

Since the shape of these monolithic products is in certain cases ill-suited to effective pressing of the membranes 5 against the latter, one can advantageously resort to the expedient illustrated in Fig. 4 where the same reference numerals are used as in Figs. 1 to 3 to designate the various parts of the container, which may be identical to that of Fig.

1 apart from the dimensions of the door 9 which must be sufficient to allow loading and unloading of the product 1 3 to be packed, which consists for example of a statue.

In this case, after having placed the product 1 3 on the base 1 of the container, via the door 9 in the latter, this door 9 is reclosed and, a loose material 14 is poured through the orifices 6 into the chamber 10 so that the chamber 10 is more or less completely filled.

After having closed the orifices 6 in an air tight manner, a vacuum is created in the chamber 10, which on the one hand causes compression of the material 1 4 from which gas is thus progressively removed and pressing by the membranes 5 of the material 14 against the product 13, which is thus itself pressed against the base 1 of the container and perfectly immobilized within the latter.

According to another variation illustrated in Figs. 5 and 6, the filling material 1 4 may be replaced by balloons 1 5 of flexible and extensible material, closed in a gas tight manner and containing either a gas at a pressure less than 1 atmosphere, or a liquid having a high vapour pressure. At atmospheric pressure, when they are introduced into the chamber 10 at the same time as the product 1 3 to be packed, these bags have a reduced volume, but, when the vacuum is created inside the chamber 10, they expand and fill up the free spaces between the product 1 3 and the membranes 5, which themselves tend to curve inwards towards the inside of the chamber 10 in order to fill the latter around the products.

In the case of these two examples illustrated in Fig. 4 and in Figs. 5 and 6, maintaining the vacuum by the pumping unit 1 2 integrated in the container throughout the period of transportation or storage makes it possible to ensure constant immoblization of the product 13, in particular in the case of Fig. 4 where possible compression of the material 14, for example due to the removal of gas from the latter, does not result in a release of the product 1 3 owing to the fact that it is immediately compensated by an extension of the membranes 5.

Naturally, one could also envisage numerous other variations for carrying out the method according to the invention without diverging from the scope of the latter.

In particular these variations could relate to the shape of the container. Depending on this shape and the dimensions of the container, one could possibly provide a different method of constructing the membranes 5 and in particular a method of construction according to which a single membrane 5 connected by certain areas to a framework 2 and/or a rigid base 1 would define the chamber 10, possibly complementing the rigid base 1.

One could also envisage different means for creating the pressure difference between the sides of the membranes, leading to the deformation of the latter towards the inside of the chamber 10 which it defines. In particular one could envisage this deformation due to the inflation of members located between these membranes 5 and the walls 3 of the container, if we refer to the example illustrated, possibly complementing the creation of a vacuum within the chamber 10.

Claims (12)

1. A method for packaging a load comprising the steps of providing a container having a well-defined rigid contour and a base, locating a load within the container, locating at least one sealed deformable membrane between the load and the said contour and establishing a pressure difference between the sides of the membrane such that the membrane presses against the load and presses the load against the base of the container.

2. A method as claimed in claim 1, in which a sealed chamber is defined around the load by the membrane and said pressure difference is established by creating a vacuum inside said chamber.

3. A method as claimed in claim 1 in which a sealed chamber is defined outside the load by the membrane and the membrane is pressed against the product by expanding said chamber.

4. A method as claimed in claim 3, in which a sealed chamber is defined around the membrane and around the load and a gas at a pressure less than atmospheric pressure and/or a liquid with a high vapour pressure is introduced into the chamber defined by said membrane, said expansion being caused by the creation of a vacuum around the load and said membrane.

5. A method as claimed in any one of claims 1 to 4 for packaging a solid load in which a loose material is inserted between the membrane and the load before establishing the said pressure difference.

6. Apparatus for packaging a load comprising a container defining a base and rigid edges, at least one sealed deformable membrane located within the container and defining therein two regions whereof one is also defined by the base and defines a first chamber able to receive the load and means for applying a pressure difference between the sides of the membrane such that the membrane tends to reduce the volume of the said chamber and to be pressed against the load when located therein.

7. Apparatus as claimed in claim 6, in which at least part of the membrane is connected to at least one rigid area of the container.

8. Apparatus as claimed in claim 7, in which the base is sealed and the periphery of the membrane is connected in a sealed manner to the periphery of the base, means being provided for alternately providing access to the inside of said first chamber in order to introduce a load or remove the latter therefrom, and for closing the said chamber in a sealed manner.

9. Apparatus as claimed in claim 8, in which the means for establishing the said pressure difference comprise means for creating a vacuum inside said first chamber.

1 0. Apparatus as claimed in any one of claims 6 to 9 in which the said membrane defines inside the container a sealed second chamber, outside which is the said first chamber suitable for receiving the load to be packaged.

11. Apparatus as claimed in claim 10, in which the container defines internally the sealed first chamber inside which is located the said second chamber and the means for applying the said pressure difference to the membrane comprise a gas at a pressure less than atmospheric pressure and/or a liquid having a high vapour pressure inside the second chamber which is defined by the membrane, means also being provided for creating a vacuum inside the first chamber defined by the container.

12. Apparatus as claimed in any one of claims 9 to 11, in which the means for creating a vacuum are incorporated in the container.

1 3. Apparatus as claimed in any one of claims 6 to 12, in which the vacuum is created for bringing about dehydration of the load.

1 4. A method for packaging a load substantially as hereinbefore described with reference to the accompanying drawings.

1 5. Apparatus for packaging a load sub stantially as hereinbefore described with reference to the accompanying drawings.