OF INSULATING A DOUBLE WALL OF A CONTAINER

FIELD OF THE INVENTION

The invention generally relates to the art of thermally insulated containers (e.g. freight containers) or cabinet structures (such as refrigerators) and especially relates to a container comprising at least one double wall provided with insulation material.

The invention in particular relates to a container comprising at least one double wall, said double wall having a bottom wall member and an inner and an outer wall member, said inner wall member and outer wall member each having a bottom edge and an upper edge, said inner wall member and outer wall member being spaced from each other and connected to each other by the bottom wall member at their respective bottom edges, said bottom wall member, inner wall member and outer wall member enclosing an intermediate space, wherein said intermediate space contains at least a first and a second hermetically sealed bag which partly overlap each other, each bag being of flexible, air tight material, each of said bags having at least one sealed opening, each of said bags further being filled with insulation material, each bag being evacuated, each of said bags having a first side edge and a second side edge, the side edges of one and the same bag being spaced from each other, said side edges extending substantially perpendicular to the bottom wall member.

BACKGROUND ART Such a container is for example known from JP-A-2006/161834.

According to JP-A-2006/161834 a lightweight heat insulation block is prefabricated by filling an airtight bag with a granular material and reducing the inside pressure. The heat insulation block thus manufactured can have a plate like form having a profiled outer contour. A plurality of such

prefabricated profiled heat insulation blocks can be arranged in the

intermediate space of a double wall such that the ends of two different blocks are in contact with each other forming a joint there between. In case of profiled blocks an overlap between two blocks is formed.

One of the disadvantages of such a heat insulation block is that in most instances the outer surfaces of the block are not completely flat as a result of evacuating the bag filled with granular material. Due to these irregular surfaces the joint formed between two juxtaposed blocks therefore can display gaps leading to reduce heat insulation. This problem occurs in particular in corner areas of a container or a cabinet structure leading to a less favourable insulation. In addition such prefabricated heat insulation blocks provide the problem that due to the predetermined dimensions of the blocks it is not always possible to correctly insulate containers or cabinets with non- matching dimensions. Due to these problems such insulation blocks do not provide the heat insulation as required for use in professional construction environment, for e.g. vacuum insulated air freight containers.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a container comprising at least one double wall which is insulated in accordance with the requirements of daily use, in for example the air transport sector, with respect to

construction, durability and maintenance. In addition it is an object of the invention to provide a correct and durable insulation of containers or cabinets also in corner areas of such containers or cabinets and irrespective of the dimensions of such containers or cabinets. Furthermore it is an object of the invention to provide a method of insulating a double wall of a container which provides the possibility of insulating containers in-situ. In order to obtain at least part of at least one of these problems the present invention provides a container comprising at least one double wall, said double wall having a bottom wall member and an inner and an outer wall member, said inner wall member and outer wall member each having a bottom edge and an upper edge, said inner wall member and outer wall member being spaced from each other and connected to each other by the bottom wall member at their respective bottom edges, said bottom wall member, inner wall member and outer wall member enclosing an intermediate space, wherein said intermediate space contains at least a first and a second hermetically sealed bag which partly overlap each other, each bag being of flexible, air tight material, each of said bags having at least one sealed opening, each of said bags further being filled with insulation material, each bag being evacuated, each of said bags having a first side edge and a second side edge, the side edges of one and the same bag being spaced from each other, said side edges extending substantially perpendicular to the bottom wall member,

characterized in that each bag is provided on its inner side with a first profiled element having a first engagement surface near the first side edge and with a second profiled element having a second engagement surface near the second side edge, said profiled elements extending in the direction of the respective side edge thereof, said engagement surfaces extending substantially

perpendicular to the inner and outer wall member and said engagement surfaces being directed towards the inner side of the respective bag, wherein one of the profiled elements of one of the first or second bags is positioned between the first and the second profiled element of the other one of the first or second bags, the engagement surface of said one of the profiled elements of said one of the first or second bags being in contact with the engagement surface of one of the profiled elements of said other one of the first or second bags. Since the bags overlap one another and the engagement surfaces of profiled elements of one of the bags are in contact with engagement surfaces of another bag it is possible to position the bags in a double wall such that no gap is formed between two juxtaposed bags, so that all the space between the inner and outer wall member is insulated thereby reducing thermal leakage. In this way also in case the container is subjected to extreme vibration or handling, the overlap of the two overlapping bags persists.

In case the double wall of the container comprises a corner, an improved thermal insulation is obtained in the embodiment of a container of the invention in which a first side edge and the first profiled element of a bag are positioned on one side with respect to the corner and the second side edge and the second profiled element of said bag are positioned on the other side of the corner.

A particular suitable insulation material for a container according to the invention is a granular material, preferably composed of silica grains.

In still a further embodiment of a container according to the invention, the at least one sealed opening is fitted with a tubular connection, said tubular connection being recessed. In this way the tubular connection does not protrude which makes the hermetically sealed bag less fragile, and thus the thermal insulation more durable. In addition a more durable insulation can be obtained when said flexible, air tight material is an impact resistant plastic material.

Please note that from US-A-2004/0069789 profiled elements are known per se. However, in the heat-insulating container described in US-A- 2004/0069789 these profiled elements are attached to the outer peripheral edge of gas filled bags. When two juxtaposed bags are positioned within a double wall and engage one another by means of their profiled elements a part of the intermediate space within the double wall is at the location of the profiled elements is not filled within insulating gas filled bags and thus comprises is a gap which present a place of thermal leakage. The profiled elements are furthermore fixed to protrusions of the walls of the container.

The invention further relates to a method of insulating a double wall of a container, said method comprises the steps of: - providing a container comprising at least one double wall, said double wall having a bottom wall member and an inner and an outer wall member, said inner wall member and outer wall member each having a bottom edge and an upper edge, said inner wall member and outer wall member being spaced from each other and connected to each other by the bottom wall member at their respective bottom edges, said bottom wall member, inner wall member and outer wall member enclosing an intermediate space, said intermediate space being accessible from an upper side of the double wall defined by the upper edges of the inner wall member and the outer wall member;

- providing at least two bags of flexible, air tight material, each of said bags being hermetically sealed with the exception of at least one opening;

- arranging the at least two bags in the intermediate space such that the at least one opening is accessible from the upper side, and such that the bags overlap each other partly;

- after a bag has been arranging in the intermediate space filling the bag with insulation material via the at least one opening;

- after the bag has been filled with insulation material, connecting the at least one opening to an evacuation system and applying an evacuation pressure on the inside of the bag; and

- after a sufficient vacuum has been reached hermetically sealing the at least one opening of the bag. In this way it is possible to in-situ and custom made insulate containers having double walls without relying on prefabricated insulation blocks or plates.

In an embodiment of a method according to the invention, in which the method comprises the steps of:

- providing said double wall with a corner,

- providing each of the bags with a first side edge and a second side edge, the side edges of one and the same bag being spaced from each other, and - arranging one bag in the corner of the double wall such that its first side edge is positioned on one side with respect to the corner and its second side edge is positioned on the other side of the corner, it is effectively and easy possible to correctly insulate corner areas of containers or cabinets.

In a further embodiment of a method according to the invention, the method further comprises the steps of:

- providing each bag on its inner side with a first profiled element having a first engagement surface near the first side edge and with a second profiled element having a second engagement surface near the second side edge, said engagement surfaces being directed towards the inner side of the respective bag;

wherein the step of arranging said bags in the intermediate space is performed such that said profiled elements and said engagement surfaces extend substantially perpendicular to the inner and outer wall member, such that one of the profiled elements of one of the first or second bags is positioned between the first and the second profiled element of the other one of the first or second bags, and such that after the evacuation pressure has been applied on the bags the engagement surface of said one of the profiled elements of said one of the first or second bags is in contact with the engagement surface of one of the profiled elements of said other one of the first or second bags. As a result of the contact between engagement surfaces of different bags an overlap between the bags as realized such that thermal leakages paths from the inner wall member to the outer wall member and vice versa are at least largely prevented.

Although at least one opening in a bag suffices for filling the bag with insulation material and evacuating the bag, for larger bags it is advantageous when the method comprises the step of providing at least one bag with at least one filling opening for filling the bag with insulation material and with at least one separate evacuation opening, and the step of sealing all said openings after a sufficient vacuum has been reached. By using more openings the method can be performed faster and thus more economical. Preferably an embodiment of a method according to the invention comprises the step of closing the double wall by connecting a top wall member to the upper edges of the inner wall member and the outer wall member.

A very reproducible and effective filling of the bag with insulation material leading to an optimal thermal insulation can be obtained in a preferred embodiment of a method according to the invention in which during the step of filling the at least one bag with insulation material the double wall is vibrated. Preferably the method comprises the step of using granular material, preferably silica grains, as insulation material and/or the step of using impact resistant plastic as flexible material.

Further features and advantages of the present invention will appear from reading the description which follows, provided by way of non- limiting example and with reference to the accompanying drawing, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic view partly in cross-section, partly in perspective of a corner part of a double wall of a container in accordance with the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

With reference to Figure 1 a method of insulating a double wall of a container in accordance with the present invention will now be elucidated.

In said method a container 1 is provided, which container 1 comprises at least one double wall 2. The double wall 2 has a bottom wall member 3, an inner wall member 4 and an outer wall member 5. The inner wall member 4 and outer wall member 5 each has a bottom edge 6; 7 and an upper edge 8; 9. The inner wall member 4 and outer wall member 5 are spaced from each other and connected to each other by the bottom wall member 3 at their respective bottom edges 6; 7. The bottom wall member 3, the inner wall member 4 and outer wall member 5 enclose an intermediate space 10 which is accessible from an upper side of the double wall 2 defined by the upper edges 8; 9 of the inner wall member 4 and the outer wall member 5.

In the embodiment shown in Figure 1 two bags 11, 12 (partly) of flexible, air tight material are indicated. It will be clear for a person skilled in the art that in dependency of the dimensions of the double wall and the bags more bags can be used to insulate the complete intermediate space.

Both bags 11, 12 are hermetically sealed with the exception of at least one opening 13 (only the opening 13 for the bag 11 is visible in Figure 1), which is accessible from the upper side. In the shown embodiment only one opening 13 is present for both evacuation and filling (to be discussed later), but it is apparent that more openings can be present and that separate openings for evacuation and filling can be present in different embodiments of the invention. An impact resistant, flexible plastic is used for the bags which is impervious for air. In different embodiments of the inventions other materials for the bags which allow the long-term evacuation of the bags can be used.

As can be seen in Figure 1 the first bag 11 comprises a first side edge 14 and a second side edge 15, and the bag 11 is arranged such that said first side edge 14 is positioned on one side with respect to the corner 16 and said second side edge 15 is positioned on the other side of the corner 16. The bag 11 thus extends over the corner area of the double wall 2. The second bag 12 also comprises side edges (one of which with reference number 17 is visible in Figure 1). All these side edges 14, 15; 17 extend substantially perpendicular to the bottom wall member 3 of the double wall 2.

The bags 11, 12 are arranged in the intermediate space 10 such that the bags 11, 12 overlap each other at respective side edges 15; 17. In the embodiment shown in Figure 1 each bag 11, 12 is provided on its inner side with a profiled element 18, 19; 20 (in other words each bag contains in its interior the profiled elements) which profiled elements extend in the direction of the side edge 14, 15; 17 thereof. Each profiled element 18, 19; 20 has an engagement surface 18a, 19a; 20a which is directed towards the interior or inner side of the respective bag. In the shown embodiment the profiled elements 18, 19 and 20 are formed by an L-shaped profiles extending substantially perpendicular to the plane of the inner and outer wall members 4, 5. The profiled elements comprises rounded of edges to prevent damaging the bags. Please note that it will be clear for a person skilled in the art that other profiled elements comprising engagement surfaces can be used in different embodiments.

As shown in Figure 1 the bags 11, 12 are arranged in the intermediate space 10 such that one of the profiled elements 20 of the second bag 12 is positioned between the first 18 and the second profiled element 19 of the first bag. The engagement surface 20a of the profiled element 20 thus faces the engagement surface 19a of the profiled element 19 of the first bag 11.

After the bags 11, 12 have been correctly arranged in the intermediate space 10 of the double wall 2 as shown in Figure 1, each of the bags 11, 12 is filled with insulation material, in the present embodiment with silica grains, via the opening 13. 14. During filling the bags 11, 12 with insulation material the double wall construction 2 is vibrated by moving a platform 21 on which the double wall construction 2 is supported in different directions as indicated by the arrows. This vibration results in a proper filling of the bags with granular material.

After each of the bags 11, 12 has been filled with insulation material, the opening 13 is connected to an evacuation system (known per se) and an evacuation pressure is applied on the inside of the bags 11, 12. As a result of the application of an evacuation pressure the dimension of the bags 11, 12 is reduced, thereby causing the profiled elements 19, 20 to move in opposite directions with regard to each other towards each other. At a certain moment the engagement surfaces 19a, 20a come in contact with each other and engage one another so that the initially realized overlap of the two bags 11, 12 remains. Consequently, since the profiled element 20 of the second bag 12 is engaged with the profiled element 19 of the first bag 11 the bags 11, 12 are coupled to each other without any gap there between. In addition, because of the mutual coupling it is not necessary to provide the walls of the container with additional elements for coupling with the insulation bags to ensure correct insulation.

After a sufficient vacuum has been reached in the bags 11, 12, the opening 13 is hermetically sealed by any known means, resulting in a vacuum insulated container.

The upper side of the double wall 2 can be closed by connecting a top wall member (not shown in Figure 1) to the upper edges 8, 9 of the inner wall member 4 and the outer wall member 5.

Please note that in the rare case one of the bags is damaged and the hermetical seal is compromised replacement of said bags can be easily performed. In addition since the insulation is realized by a plurality of bags, it is only necessary to replace a defective bag while the undamaged bags still provide insulation.

Thus a container 1 with an isolated double wall 2 is obtained in which said double wall 2 has a bottom wall member 3 and an inner wall member 4 and an outer wall member 5. Said inner wall member 4 and outer wall member 5 each has a bottom edge 6, 7 and an upper edge 8, 9 and are spaced from each other and connected to each other by the bottom wall member 3 at their respective bottom edges 6, 7. The bottom wall member 3, inner wall member 4 and outer wall member 5 enclose an intermediate space 10, in which at least one hermetically sealed bag 11, 12 of flexible, air tight material is arranged. The bags 11, 12 are arranged in the intermediate space 10 and have at least one sealed opening 13, which is recessed in order not to protrude from the bag. Each bag 11, 12 is filled with insulation material (preferably silica grains) and is evacuated. Each bag 11, 12 contains in its interior a first profiled element 18; 20 having a first engagement surface 18a; 20a near the first side edge 14; 17 and a second profiled element 19 having a second engagement surface 19a near the second side edge 15. The profiled elements 18, 19; 20 extend in the direction of the respective side edge 14, 15; 17 thereof. The engagement surfaces 18a, 19a; 20a extend substantially perpendicular to the inner and outer wall member 4, 5 and are directed towards the interior or inner side of the respective bag 11; 12. One of the profiled elements 20 of one 12 of the first or second bags 11, 12 is positioned between the first 18 and the second profiled element 19 of the other one 11 of the first or second bags 11, 12. The engagement surface 20a of said one 20 of the profiled elements of said one 12 of the first or second bags is in contact with the engagement surface 19a of one 19 of the profiled elements of said other one 11 of the first or second bags. It will be clear that although Figure 1 only shows two bags 11, 12 this is for illustration purposes only. To ensure a complete insulation of the double wall the intermediate space is to be filled with a sufficient number of overlapping bags.