TECHNICAL FIELD:

The present invention relates to an inflatable construction ranging from a construction element to assembled con¬ structions for various purposes .

BACKGROUND OF THE INVENTION:

One example of an inflatable construction which can be built up is described in GB 2 105 264. This construction creates a slide for emergency evacuation, for example for transporting people in an emergency situation from the deck of a ship or the exit of an aeroplane to a water surface or the ground. This slide arrangement is made from a flexible fabric material which is air-tight and which forms chan¬ nels. In a stand-by condition, the slide is stored in a rolled-up or folded-up condition in a compartment provided with a door. If the arrangement is mounted on a ship, the compartment is positioned on the side of the ship beneath an evacuation opening or a deck section. If the slide arrangement needs to be used in an emergency situation, the door of the compartment is opened and the slide made from fabric material begins to unfold. At the same time, a valve to a pressure vessel is opened so that the said channels are filled with air or another gas. In this manner, the slide is inflated to a stiff condition and forms a slideway from the evacuation location to a lower point. When used on a ship, the lower point is the water surface around the ship.

It may be necessary that such a slide arrangement bridges a long gap. When loaded, the arrangement will thus be

subjected to large bending forces. In order to withstand these, the channel system must be given a great stiffness by the provision of large cross-sectional dimensions and high pressure of the contained air. This in turn creates demands for a substantial fabric material which withstands this pressure. In addition to the high costs and bulkiness which such a construction implies, a high sensitivity to damage arises. Even if slightly punctured, the majority of the stiffness is lost.

Despite the great advantages which an inflatable construc¬ tion provides for certain uses, above all the possibility to be stored folded-up in a small space when it is not needed to be employed, the use has been very much restricted because of said disadvantages of insufficient loading capacity when of reasonable dimensions as well as sensitivity to external damage.

SUMMARY OF THE INVENTION: In accordance with the invention, the channel system consists not only of fabric material but also includes inner elements of a bendable sheet material. The system can be rolled-up or folded from a flat state. As long as the channel system is not inflated, the element can thus be rolled-up in a standby condition. When the slide is inflated, the sheet material adopts a curved condition and thus forms a stiff body due to its tube-like shape which thus requires substantial forces to be bent.

With such an arrangement, a construction which is very stiff in its use condition can be attained without the dimensions being particularly large and without any more complicated structural solutions needing to be adopted. In addition, the risk of piercing the wall of the pressurized chamber resulting in leakage is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS:

The invention will be described in the following with reference to four embodiments relating to both a simple construction element and a number of assembled construc- tions for various purposes. Reference will be made to the attached drawings in which there is shown in

Fig. 1 a portion of the arrangement in the form of a construction element and in a non-inflated condition;

Fig. 2 the same element portion in inflated condition; Fig. 3 a section along line III-III in Fig. 5 of a bridge construction; Fig. 4 an enlarged cross-section of a portion of the bridge construction;

Fig. 5 the bridge construction in elevation; Fig. 6 the bridge construction in plan view; Fig. 7 an elevational view of a slide for emergency evacuation; Fig. 8 a cross-section of the slide along line VIII-

VIII in Fig. 7; Fig. 9 an end view of a barrier in inflated condition and Fig. 10 a perspective view of the barrier from the side during erection by inflation.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS:

In Fig. 1 a portion of a tube 1 of a flexible fabric material is shown, preferably woven-reinforced rubber. The tube can be said to consist of two side portions 2 and 3 which, in the non-inflated condition of the tube shown in Fig. 1, lie against each other with their inwardly facing sides 4. In this manner, two longitudinally extending fold- edges 5 are formed. The fabric material in the sides 2 and 3 is doubled between the fold-edges 5 such that each side delimits a pocket.

A sheet 6 of a relatively stiff though bendable material is inserted in each of the two pockets. Preferably, the material is a semi-rigid plastic . The thickness of the sheets depends on the size of the tube, the larger the tube the greater the thickness should be, as well as the size of the intended bending load. Generally, the thickness can be considered to range from a few to a few tens of millimetres .

In the inflated condition of the tube which is shown in Fig. 2, the sides 2 and 3 are forced away from each other and their inner surfaces 4 form the inner wall of the now substantially cylindrical tube. Those regions 5 which previously formed fold-edges will now be accommodated in the cylindrical outer wall of the tube.

Since the fabric material is tensioned and adopts the described shape through inflation with an inner air- pressure, the sheets 6 are forced to follow this change in shape and form two opposed semi-cylindrical mantels in the cylindrical tube 2. With this shape, the sheets attained a substantial stiffness even if the material is only semi¬ rigid and make the tube substantially stiffer than a conventional construction consisting only of fabric material.

In a flattened condition, however, as shown in Fig. 1, the semi-rigid sheets can be bent if the tube is rolled-up or folded-up for storage.

As mentioned, the tube shown in Figs. 1 and 2 is only a short piece and the tube is intended to have a length of a number of meters . Its ends are thus sealed so that the enclosed air cannot flow out. One or more valves 8 are provided for inflation.

If a tube of such a length is to be collapsed, the rolling- up in its longitudinal extension is easily possible. If however it is desired to fold-up the tube, the sheets 6 can be split up so that folding locations are formed between sections of the sheets. This does of course result in a weakening of the bending resistance in the longitudinal direction, though the tube will in any event be substan¬ tially stiffer than a tube consisting solely of fabric material, since the ends of the sheets are substantially held together by the fabric material.

Figs. 3-6 show how a bridge construction can be constructed by tubes of the described type. If such a bridge construc¬ tion has a relatively large span, the construction in the drawings can have a span of about 16 meters, the individual tubes would require a considerable cross-sectional dimen¬ sion despite the stiffening effect of the sheets. In order to permit easier handling, according to the embodiment at least the primary supporting tubes are thus split up into a number of tubes with each being constructed in a manner as shown in Figs. 1 and 2. In this manner, the individual tubes can be made supporting, which can be of considerable importance since a bridge of this type is intended for emergency situations and also for military purposes where it may be necessary to rely solely on manpower for the erection.

As shown in the drawings, the bridge is in the form of two upper curved tube elements 10, the ends 11 of which are anchored in the ground and with the help of tensioning wires 12 tensioned in the shown curved-shape. It is these substantially supporting elements which preferably are an assembly of several tubes 13 which are kept together by a number of equally spaced apart rings 14. During inflation of the tubes 13, these are pressed against the ring 14 which may also consist of fabric material which is non-

extendable. In this manner, the tubes cannot be displaced with relation to each other, which increases the bending stiffness. With the help of support wires 15, the two supporting tubes support a bridge path 16 which has been shown in the form of panels placed one after the other. The panels are supported with the help of lower tubes 17 having the construction as shown in Figs. 1 and 2.

A slide for emergency evacuation is shown in Fig. 7. In Fig. 7, the slide is shown extending from the side 21 of a ship to a lifeboat 22. The slide is constructed of two side portions 23 each consisting of two tubes 24 arranged one over the other. A fabric sheet 25 is suspended between these sides and forms the floor portion which serves as the path or slide for the people who are to be evacuated.

The slide arrangement shown in the drawings is further provided with sides consisting of upper, double tubes 26 and angled cross-pieces 27 between the sides and the tubes 26 in order to build a framework.

For very long evacuation slides, such as those on large, high ships, such a framework can be necessary in order to impart sufficient stiffness without the tube dimensions as such being too large. In other words, a handier construc¬ tion can be attained if the stiffness of the slide is imparted by a framework rather than by imparting stiffness through increased dimensions of individual tubes.

In the standby condition, the entire construction is rolled up and accommodated in a compartment 29 on the side of the ship. During use, the compartment is opened so that the rolled-up slide can fall out. At the same time, the construction is inflated with gas, in this case carbon dioxide, and thus attains the shape shown in Fig. 7. Thereafter, the life-raft 22 can be moved to its outer end.

Alternatively, the life-raft can be comprised in the construction and can be accommodated in the same compart¬ ment as the slide so that it reaches the position shown during the inflation.

A barrier is shown in Figs. 9 and 10. In its stand-by condition, it is folded-up and stored in a box 30. It consists of a number of tubes 31 which are affixed at 32 to the *<ase of the box so that they can pivot between a collapsed position against the base of the box and an erect position. The tubes 31 are united with the top 33 of the construction. Each of the tubes 31 is constructed according to Figs . 1 and 2 and the inner sheets are folded at a hinge point 34 half way up the barrier. In addition to the inner sheets, the lower portion of the tubes can be supported by a frame construction 35 which can pivot about a bearing for each frame at the base 32 of the box. The described supporting construction is covered by a fabric envelope 38. In the standby state, the tubes 31 are emptied of air and can be folded at the point 34 and at the base of the box so that in this double-folded condition they can be laid in the box. The frames 35 are thereby swung downwardly as a layer between the upper and lower regions of the tubes .

When the barrier is to be erected, the tubes 31 are filled with air so that they straighten out and form upright straight post-like elements which erect the fabric envelope and tension it.

In Fig. 9, it is indicated that the box can be recessed and provided with flaps which swing upwardly due to the inner pressure when the construction begins to erect itself.

A barrier of this type can be used in different connec- tions. One use is as a barrier against the spreading of fire or smoke or gases or liquids . The fabric envelope must

thus be adapted to the specific field of use and, for example, made of inflammable material if the barrier is to be used for restricting fire. Such a use is suitable where the risk arises for such spreading and where this can lead to serious damage.

The basic idea behind the invention, that an inflatable structure is stiffened by inserting sheets of a semi-rigid material in its pressure channels, can thus be adapted for many different purposes of which only a few of the most important have been mentioned here. Particularly advantage¬ ous is the application of such inflatable constructions which are exposed to large bending forces due to loads or wind forces. Thus, use in connection with marine travel is particularly important and in particular primarily as a slide for emergency evacuation, an embodiment which has also been described here.

It can be added that the construction element does not need to have the form of an individual tube as described in connection with Figs. 1 and 2. Alternatively, the elements can be integrally included in units with a plurality of gas chambers . Such a unit can for example be formed by two fabric sheets which are joined together along a number of seams so that a plurality of chambers are formed side by side. According to the invention, some or all of these chambers will include the said sheets.