A FLEXIBLE RECEPTACLE

Abstract: The invention relates to a flexible receptacle comprising a cylindrical support portion (1) of a durable fabric and an inner bag (4) of a thin plastic film. Known inner bags have a low durability in comparison with the support portion. The chances of the inner bag (4) of remaining undamaged in case of a push in the longitudinal direction of the receptacle are improved, if the inner bag has the form of an ellipsoid, the greatest diameter of which considerably exceeds the diameter of the support portion (1).

Description: A flexible receptacle The present invention relates to a flexible re¬ ceptacle comprising a substantially cylindrical bear- ing support portion and an inner bag, which is posi¬ tioned within the support portion, manufactured of a flexible film and provided with valve means for fil¬ ling and emptying the inner bag. Receptacles of this kind in sizes of 500... 1500 litres are previously known. In most cases, the bearing support portion consists of a strong fabric, while the inner bag is manufactured of a relatively thin plastic film. The film shall function as a barri¬ er for a material transported in the receptacle and simultaneously, it shall be as flexible as possible. In general, no film can be found which fulfils both requirements entirely and therefore, the film selected constitutes a compromise in most cases. Receptacles of this kind are in most cases mounted on a pallet in such a way that the centre line of the receptacle is perpendicular to the main level of the pallet. The inner bag is usually manufactured of three portions, i.e. two end portions and one man¬ tle portion, which are welded together. The inner bag is thus provided with two joints situated in the vici¬ nity of the ends of the receptacle. These joints con¬ stitute the weakest points of the inner bag, because the durability at these points usually comes up to appr. 75 % of the durability of the film only. When the receptacle is transported, it can be exposed to pushes in the longitudinal direction of the receptacle. This happens e.g. when the receptacle falls in the direction of the centre line. At the mo¬ ment of a push, the receptacle takes a form reminding of a pear with the narrow portion upwards and the broad portion downwards. The lower weld joint of the inner bag is thus exposed to big strains and if the support portion yields much the inner bag can burst at the lower joint, whereby the contents run out. In case of a strong push it can occur that the lower part of the support portion bursts entirely so that it does not give any support to the inner bag at all. Then, it is of great importance that the inner bag is as far as possible prevented from bursting, too. The object of the present invention is to pro¬ vide a flexible receptacle, whereby the chances of maintaining the inner bag undamaged in case of a push in the longitudinal direction of the receptacle are greater than in known receptacles of the same kind. The receptacle of the invention is characterized in that the inner bag in a free filled state has substan¬ tially the form of an ellipsoid, the biggest diameter of which considerably exceeds the diameter of the support portion, and that the inner bag is situated in the support portion in such a way that its greatest diameter is substantially perpendicular to the centre line of the support portion. When an inner bag of the form and size stated above is situated within the support portion, it forms folds along the mantle surface of the support portion. This means that the film is not streched to the same extent as in known receptacles, in which the diameter of the inner bag corresponds to the diameter of the support portion, when the support portion due to a push expands laterally. The feature given above re¬ sults to that when the support portion bursts entire¬ ly, the inner bag takes its free ellipsoid form. The liquid column in the inner bag is then very low, and consequently, the pressure is low, which gives the inner bag greater chances of remaining undamaged than previously. In known receptacles, the inner bag has also in a free state the same height as the recepta¬ cle, which causes a high pressure within the inner bag. Moreover, it shall be noted that a high and nar- row inner bag is not held up by itself, without outer support, but it falls down, whereby it can easily be damaged. It is also realized that an inner bag of the form stated above can easily be manufactured of only two pieces of film joined together along the edges. The inner bag has then only one joint, which naturally is advantageous from the viewpoint of durability. According to an advantageous embodiment of the receptacle of the invention, the joint of the inner bag is flush with the greatest diameter of the bag. The joint will then be situated at the mantle surface of the receptacle at equal distances from the ends of the receptacle. This improves the durability of the inner bag, because the strains are at this point con- siderably less than the strains in the vicinity of the ends of the receptacle, where the joints were situated before. The folds of the inner bag can be made to be distributed evenly along the periphery of the recepta- cle by giving the joint the shape of a polygon. A preferable embodiment of the receptacle of the invention is described in more detail in the fol¬ lowing with reference to the drawing enclosed, in which Figure 1 shows a longitudinal section of a re ¬ ceptacle of the invention schematically, Figure 2 shows the inner bag in a free filled state, Figure 3 shows an end view of an empty inner bag and . Figure 4 shows a cross section of the inner bag according to Figure 3. The flexible receptacle of Figure 1 comprises an outer, substantially cylindrical bearing support portion 1, which can consist e.g. of one layer or two layers of a strong fabric of plastic threads. The sup¬ port portion is by means not shown fastened to a pal¬ let 2 in such a way that the centre line of the sup¬ port portion is perpendicular to the main level of the pallet. Both ends of the support portion have an open¬ ing situated in the middle, in which opening is ar¬ ranged a valve 3. The upper valve is used for filling and the lower for emptying the receptacle. Within the support portion 1 there is an inner bag 4 of a thin flexible plastic film. The inner bag is dimensioned in such a way that it bears against the inner surface of the support portion when the recepta¬ cle is filled. The valves 3 are fastened to the upper and lower end of the inner bag. In accordance with the invention, the inner bag 4 has substantially the form shown in Figure 2, when it is filled with gas or fluid without high over-pres¬ sure and when it is in a free state, i.e. the form is not influenced by any external restrictions. In the first place, the form can be characterized as an el¬ lipsoid, but it can also be described well as a discus or a round cushion. It is essential that the inner bag is low and broad in a free state and that its greatest diameter or, if the inner bag is angular, the greatest distance between opposite sides considerably exceeds the diameter of the mantle surface of the support por¬ tion 1. The inner bag is placed in the support portion in such a way that its greatest diameter, i.e. its main level, is perpendicular to the centre line of the support portion. Because the diameter of the inner bag is 1,5...3,0 times greater than the diameter of the support portion, the inner bag forms folds 5 parallel to the centre line of the support portion and situated at the mantle of the support portion, while the end portions of the inner bag are substantially even. In the embodiment shown, the inner bag 4 is manufactured of two pieces of film, which are joined together along a joint 6 running along the edges of the pieces. The film pieces can be circular or angu¬ lar, while the joint 6 preferably consists of a series of connected straight portions, see Figure 3. The film pieces are preferably even in accordance with Figure 4. If the inner bag 4 is manufactured in the way described above, the joint 6 will be situated on the transversal middle level of the support portion, i.e. midway between the ends, which is of decisive impor¬ tance for the durability of the inner bag in case of pushes, because this part of the receptacle is seldom exposed to great stresses. Because the inner bag fur¬ ther has only one joint, it has a better durability than previous inner bags with two joints. When filling the receptacle with fluid, it is at first filled with air, which is then blown out concurrently with feeding fluid into the receptacle. In case of pushes in the vertical direction, a pres¬ sure directed horizontally outwards is created in the lower half of the receptacle, due to which this part of the support portion expands. On account of the folds 5, the inner bag 4 can follow the expansion without being damaged. If the support portion splits to such a degree that it does not support the inner bag any more, the inner bag takes the form shown in Figure 2, whereby the pressure within the inner bag is as low as possible, which contributes to maintain the inner bag undamaged.

Claims: Claims ! 1. A flexible receptacle comprising a substan¬ tially cylindrical bearing support portion (1) and an inner bag (4), which is positioned within the support portion, manufactured of a flexible film and provided with valve means (3) for filling and emptying the in¬ ner bag, c h a r a c t e r i z e d in that the inner bag (4) in a free filled state has substantially the form of an ellipsoid, the biggest diameter of which considerably exceeds the diameter of the support por¬ tion (1), and that the inner bag is situated in the support portion in such a way that its greatest dia¬ meter is substantially perpendicular -.to the centre line of the support portion. 2. A flexible receptacle according to claim 1, c h a r a c t e r i z e d in that the inner bag (4) comprises two films joined together along the edges. 3. A flexible receptacle according to claim 2, c h a r a c t e r i z e d in that a joint (6) of the inner bag is flush with the greatest diameter of the bag. 4. A flexible receptacle according to claim 2, c h a r a c t e r i z e d in that the joint (6) forms a polygon situated at the edge. 5. A flexible receptacle according to claim 1, c h a r a c t e r i z e d in that the greatest dia ¬ meter of the inner bag (4) is 1,5...3 times greater than the diameter on the mantle of the support portion (1).

Inventors: BJOERK PETER, BJOERK, PETER
Applicants: FLUID BAG AB OY, OY FLUID-BAG AB
Application year: 1989
Main classification: B65D88
IPC codes: B65D88