Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
INFLATABLE TUBE STRUCTURE FOR ROOF TRUSS CONSTRUCTION AND A METHOD FOR BENDING SUCH A STRUCTURE
Document Type and Number:
WIPO Patent Application WO/2014/163564
Kind Code:
A1
Abstract:
The invention concerns an inflatable tube structure (1) for roof truss construction comprising a tube sheet (2) extending in a longitudinal direction and a transverse direction. Said tube sheet (2) comprises longitudinal sealing means (3) along the longitudinal edges (4) such that a tube (5) is formed when the tube sheet (2) is folded over itself and the longitudinal sealing means (3) are joined together. The inflatable tube structure (1) further comprises at least one bend arrangement (7) comprising an attachment area (8) of the tube sheet (2) extending in a longitudinal direction and a transverse direction on the tube sheet (2), an attachment arrangement (9) comprising at least four attachment means (201, 201', 301, 301') arranged in a first pair (201, 301) and a second pair (201', 301') and a bending means (103, 203, 303) comprising at least four engagement means arranged in a first pair (202, 302) and a second pair (202', 302').

Inventors:
MCCULLOUGH ROBERT (SE)
Application Number:
PCT/SE2014/050390
Publication Date:
October 09, 2014
Filing Date:
April 02, 2014
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
FORSSTROM HIGH FREQUENCY AB PUBL (SE)
International Classes:
E04H15/20; E04B7/14
Foreign References:
US5570544A1996-11-05
JP2009263979A2009-11-12
JP4093518B22008-06-04
EP0042582A11981-12-30
US4197681A1980-04-15
Attorney, Agent or Firm:
ZACCO SWEDEN AB et al. (Stockholm, SE)
Download PDF:
Claims:
CLAIMS

1 . Inflatable tube structure (1 ) for roof truss construction comprising a tube sheet (2) extending in a longitudinal direction and a transverse direction said tube sheet (2) comprising longitudinal sealing means (3) along the longitudinal edges (4) such that a tube (5) is formed when the tube sheet (2) is folded over itself and the longitudinal sealing means (3) are joined together

characterized in that

the inflatable tube structure (1 ) further comprises at least one bend arrangement (7) comprising:

- an attachment area (8) of the tube sheet (2) extending in a longitudinal direction and a transverse direction on the tube sheet (2),

- an attachment arrangement (9) comprising at least four attachment means (201 , 201 ', 301 , 301 ') arranged in a first pair (201 , 301 ) comprising a first and second attachment means arranged longitudinally relative each other at a first distance on said attachment area (8) of the tube sheet (2) and a second pair (201 ', 301 ') comprising a third and fourth attachment means arranged longitudinally relative each other at a third distance on said attachment area (8) of the tube sheet (2) and wherein said first (201 , 301 ) and second pairs (201 ', 301 ') are arranged diagonally offset from a central longitudinally extending line of the attachment area (8) and in opposite direction relative each other such that a first imaginary line extending between the first and second attachment means and a second imaginary line extending between the third and fourth attachment means intersect, and

- a bending means (103, 203, 303) extending in at least a longitudinal direction wherein the bending means (203, 303) comprise at least four engagement means arranged in a first pair (202, 302) comprising a first and second engagement means arranged longitudinally relative each other at a second distance upon said bending means (103, 203, 303) and a second pair (202', 302') comprising a third and fourth engagement means arranged longitudinally relative each other at a fourth distance upon said bending means (103, 203, 303) and wherein said first (202, 302) and second pair (202', 302') are arranged diagonally offset from a central longitudinally extending line of the bending means (203, 303) and in opposite direction relative each other such that a first imaginary line extending between the first and second engagement means and a second imaginary line extending between the third and fourth engagement means intersect, wherein the first pair of engagement means (202, 302) is adapted to engage the first pair of attachment means (201 , 301 ) and the second pair of engagement means (202', 302') is adapted to engage the second pair of attachment means (201 ', 301 '), before inflation of the tube structure (1 ), and wherein said second distance is shorter than the first distance and the third distance is shorter than the fourth distance such that the tube sheet (2) creases over at least part of the attachment area (8) upon inflation of the tube structure (1 ) causing the inflatable tube structure (1 ) to form a bend over the attachment area (8).

2. Inflatable tube structure (1 ) according to claim 1 wherein said attachment area (8) of said tube sheet (2) is flanked in said longitudinal direction on each side by a first and second flanking area (10) of said tube sheet (2) wherein, after inflation of the tube structure (1 ), said flanking areas (10) form an angle relative each other by means of engagement of the engagement means (102,

202, 202', 302, 302') of the bending means (103, 203, 303) and the attachment means (101 , 201 , 201 ', 301 , 301 ') in the attachment area (8) and wherein said angle is determined by the difference between the first distance and the second distance.

Inflatable tube structure (1 ) according to claims 1 or 2, wherein at least one engagement means is permanently engaged to at least one attachment means.

Inflatable tube structure (1 ) according to any of the above claims, wherein the first distance and the third distance are equal, and the third distance and the fourth distance are equal.

5. Inflatable tube structure (1 ) according to claim 7 wherein the attachment arrangement (9) comprises a third pair of attachment means (301 ") comprising a fifth and a sixth attachment means arranged on a transverse extending line of the attachment area (8) in between the first and third and the second and forth attachment means respectively, and wherein the bending means (303) comprises a third pair of engagement means (302") comprising a fifth and sixth engagement means arranged on a transverse extending line of the bending means (303) and wherein the fifth engagement means is adapted to engage with the fifth attachment means and the sixth engagement means is adapted to engage with the sixth attachment means.

6. Inflatable tube structure (1 ) according to claims 5 or 6 wherein the first (201 , 301 ) and second pair (201 ', 301 ') of attachment means are arranged at the corners of the attachment area (8).

7. Inflatable tube structure (1 ) according to any of the claims 5-7 wherein the bending means comprises at least two strings wherein a first string is arranged between the first pair of engagement means and a second string is arranged between the second pair of engagement means such that the first and second strings intersect.

8. Inflatable tube structure (1 ) according to any of the claims 5-9 wherein the bending means (203, 303) comprises at least four strings wherein the third string is arranged longitudinally across the bending means (203, 303) between the first engagement means of the first pair of engagement means (202, 302) and the fourth engagement means of the second pair (202', 302') of engagement means and the fourth string is arranged longitudinally across the bending means between the third arrangement means of the second pair (202', 302') of arrangement means and the second arrangement means of the first pair (202, 302) of arrangement means respectively.

9. Inflatable tube structure (1 ) according to any of the above claims wherein the bending means (103, 203, 303) comprise a bending means sheet material extending in a longitudinal direction and a transverse direction.

10. Inflatable tube structure (1 ) according to claim 10 wherein the engagement means (102, 202, 202', 302, 302' ) are arranged at the corners of said bending means (103, 203, 303) sheet material.

1 1 . Inflatable tube structure (1 ) according to any of the claims 10-1 1 wherein the sheet material of the bending means (103, 203, 303) comprise a first and a second cut out wherein the first cut-out is arranged at a first traverse side of the bending means (103, 203, 303) and the second cut-out is arranged at a second traverse side of the bending means (103, 203, 303) such that a waist is formed along the central longitudinal line of the bending means (103, 203, 303).

12. Inflatable tube structure (1 ) according to claim 12 wherein the said first and second cut-out is crescent-shaped.

13. Inflatable tube structure (1 ) according to any of the above claims comprising at least two bend arrangements (7) and wherein the at least two bend arrangements (7) are arranged along a central longitudinal line of the tube sheet (2).

14. System of inflatable tube structures (1 ) according to any of the above claims.

15. Method for bending an inflatable tube structure (1 ) for roof truss construction comprising the steps of:

- providing a tube sheet (2) with longitudinal sealing means along the longitudinal edges of the tube sheet (2);

characterized in that it further comprises:

- providing a tube sheet (2) with an attachment area (8) extending in a longitudinal direction and a transverse direction on the tube sheet (2); arranging an attachment arrangement (9) comprising at least two attachment means (101 , 201 , 201 ', 301 , 301 ') longitudinally relative each other at a first distance on said attachment area (8) of the tube sheet (2); folding the tube sheet (2) over itself and joining the longitudinal sealing means such that a tube is formed;

providing a bending means (103, 203, 303) with at least two engagement means (102, 202, 202', 302, 302') arranged longitudinally relative each other at a second distance upon said bending means (103, 203, 303); engaging the engagement means (102, 202, 202', 302, 302') of the bending means (103, 203, 303) with the attachment means (101 , 201 , 201 ', 301 , 301 '); and

inflating the tube structure (1 ) such that the tube sheet (2) creases over the attachment area (8) thereby causing the inflatable tube structure (1 ) to form a bend over the attachment area (8).

Description:
INFLATABLE TUBE STRUCTURE FOR ROOF TRUSS CONSTRUCTION AND A METHOD FOR BENDING SUCH A STRUCTURE

TECHNICAL FIELD

This invention relates to an inflatable tube structure for roof truss construction comprising a tube sheet extending in a longitudinal direction and a transverse direction. The tube sheet comprises longitudinal sealing means along the longitudinal edges such that a tube is formed when the tube sheet is folded over itself and the longitudinal sealing means are joined together.

BACKGROUND

Inflatable tube structures are commonly used for forming the scaffold and/or the roof trusses of temporary tents e.g. used by the army. The inflatable tube structures are commonly sealed airtight at their bases, the tube ends, and do not require additional air supply after inflation. A sheet of material is arranged upon the roof truss construction in order to function as the roof itself.

Inflatable tube structures used for roof truss constructions may be arranged to take different shapes; for example they may be curved, triangular or rectangular or have three angles. Three angled roof trusses are most common, and the angles of the roof truss bends are chosen depending on the area of use and the requirement on the roof. Commonly, the angles of the inflatable tube structure forming a roof truss must be planned and taken into account already during the designing of the tube structure. Two tube sheets which are intended to be formed into the tubes forming a bend relative each other are joined together at their traverse ends at an angle to each other. Thereafter the sheets are joined along their longitudinal edge in order to create one continuous inflatable bent tube structure. Consequently this means that the tube sheets from which the inflatable tube structure of the finished product is made must be pre-cut and pre-sealed into the required angle. Pre-cutting the tube sheets in order to facilitate sealing them into an angle often leads to wasting tube sheet material. Sealing the tube sheets both at the transverse edge to perform the angle and along the longitudinal edge to form the tube structure is time- and labour consuming and requires specially adapted equipment. Also; not only must the longitudinal seal of the tube be airtight, but also the seals of the sheets forming the angles must be airtight in order for the inflatable tube structure to be airtight and work properly. Making sure that the bonds are properly sealed during the manufacturing process is time- and labour consuming because any detected leaks must be repaired.

There is therefore a need for improved inflatable tube structures in which the above mentioned disadvantages are overcome.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an improved inflatable tube structure for roof truss constructions with means for forming bends. It is also an object of the present invention to provide an inflatable tube structure which is bent and stable when inflated. It is also an object of the present invention to provide an inflatable tube structure which is easy to manufacture and is user-friendly. The features of the present invention are set out in claim 1 .

It is also an object of the present invention to provide a method for forming a bend on an inflatable tube structure for roof truss constructions as set out in claim 15. The invention concerns an inflatable tube structure for roof truss construction comprising a tube sheet extending in a longitudinal direction and a transverse direction the tube sheet comprising two longitudinal edges such that a tube with two tube ends is formed when the tube sheet is folded over itself and the longitudinal edges are joined together. Such a design may be used for roof trusses or scaffolds in temporary tents or any other area of use in which bended inflatable tubes structures are beneficial. The inflatable tube construction may therefore be adapted to receive and uphold a sheet of material such that a roof or a wall may be formed between at least two inflatable tube structures. The tube sheet may be made of a plastic material such as PVC, PU, polyester fabric coated with PVC or any other suitable material. The longitudinal sealing means may be welding means, adherent means or any other suitable non-puncturing means for sealing the longitudinal edges of the tube sheet in order to form a tube contraction which is air-tight. High-frequency welding is a preferred longitudinal sealing means. The tube ends may be open or sealed, i.e. the inflatable tube structure may comprise end sealing means for sealing the tube ends such that the tube becomes airtight when the tube ends are sealed. The inflatable tube structure may also be provided with valves such that the tube structure can be deflated or provided with additional air when needed. The valves are preferably arranged at or adjacent the tube ends.

In one example not according to the invention, the inflatable tube structure further comprises at least one bend arrangement comprising an attachment area of the tube sheet extending in a longitudinal direction and a transverse direction on the tube sheet, an attachment arrangement comprising at least two attachment means arranged longitudinally relative each other at a first distance on the attachment area of the tube sheet, a bending means extending in at least a longitudinal direction wherein the bending means comprises at least two engagement means arranged longitudinally relative each other at a second distance upon the bending means, wherein the engagement means are adapted to engage with the attachment means of the attachment arrangement before inflation of the tube structure, and wherein the second distance is shorter than the first distance such that the tube sheet creases over part of the attachment area upon inflation of the tube structure causing the inflatable tube structure to form a bend over the attachment area. End of example.

The invention is characterized in that the inflatable tube structure further comprises at least one bend arrangement comprising an attachment area of the tube sheet extending in a longitudinal direction and a transverse direction on the tube sheet, an attachment arrangement comprising at least four attachment means arranged in a first pair comprising a first and second attachment means arranged longitudinally relative each other at a first distance on said attachment area of the tube sheet and a second pair comprising a third and fourth attachment means arranged longitudinally relative each other at a first distance on said attachment area of the tube sheet and wherein said first and second pairs are arranged diagonally offset from a central longitudinally extending line of the attachment area and in opposite direction relative each other such that a first imaginary line extending between the first and second attachment means and a second imaginary line extending between the third and fourth attachment means intersect, a bending means extending in at least a longitudinal direction wherein the bending means comprise at least four engagement means arranged in a first pair comprising a first and second engagement means arranged longitudinally relative each other at a second distance upon said bending means and a second pair comprising a third and fourth engagement means arranged longitudinally relative each other at a second distance upon said bending means and wherein said first and second pair are arranged diagonally offset from a central longitudinally extending line of the bending means and in opposite direction relative each other such that a first imaginary line extending between the first and second engagement means and a second imaginary line extending between the third and fourth engagement means intersect, wherein the first pair of engagement means is adapted to engage the first pair of attachment means and the second pair of engagement means is adapted to engage the second pair of attachment means, before inflation of the tube structure, and wherein said second distance is shorter than the first distance such that the tube sheet creases over at least part of the attachment area upon inflation of the tube structure causing the inflatable tube structure to form a bend over the attachment area.

By such a design it is possible to bend an entire tube structure formed from one single tube sheet into a desired bend instead of predetermining the angle between two separate tube sheets before joining them. Therefore, pre-cutting and pre-sealing of two tube sheets to create a bend is not necessary and the manufacturing process is simplified. Since the bend is formed from a single tube instead of two tubes joined by welding the tube structure minimizes the risk of air leakage at the joints. The inflatable tube structure is easy to use in roof truss constructions due to the design of the bend arrangement, enabling predetermined bends forming upon inflation.

The angle of the bend is determined by the positioning of the attachment means upon the tube structure, as well as on the size of the bending means, i.e. the first and second distances. The positioning direction of the attachment means upon the attachment area of the tube structure determined the direction of pulling force of the bending means when being engaged, thereby controlling the angle of the bend.

The attachment area is preferably an area of the tube sheet itself. The attachment area is defined as an area of the tube sheet on which the attachment arrangement is positioned. The area of the tube sheet intermediate the attachment means of the attachment arrangement is at least part of the attachment area. The attachment area may also be a separate arrangement integrated with the tube sheet consistent with the definition above. The attachment means are attached to the tube sheet, within the attachment area, by non-destructive means such as adhesives, high-frequency welding, hot wedge and/or hotair.

The attachment area, and hence also the attachment means, are arranged upon the tube sheet such that they are located on the outside of the tube formed when the tube sheet is folded over itself and the longitudinal edges are joined together.

The inflatable tube structure may comprise any number of attachment means and any number of engagement means, such as four, five, six etc. The first distance is the distance between two attachment means arranged longitudinally relative each other and the second distance is the distance between two complementary engagement means arranged longitudinally relative each other which engage with the two the attachment means. Longitudinally does not exclusively mean arranged upon a central longitudinal line. Because the second distance is shorter than the first distance the bending means will cause contraction of the attachment area intermediate the attachment means when engaged. The contraction of the attachment area will force the inflatable tube structure to bend at the attachment area, creating an angle between the two areas flanking the attachment area upon inflation. The angle is determined by the positioning of the attachment means and the size of the bending means (i.e. the first and second distance).

The bending means may be of any suitable material such as moulded plastic, PVC, rope, metal or cardboard, any other suitable material or a combination of materials.

The attachment area of the tube sheet may be flanked in longitudinal direction on each side by a first and second flanking area of the tube sheet wherein, after inflation of the tube structure, the flanking areas form an angle relative each other by means of engagement of the bending means and the attachment means in the attachment area and wherein the angle is determined by the difference between the first distance and the second distance. The extension of the flanking areas in longitudinal and transverse direction is not discrete. For example, the flanking area may be the entire area intermediate the attachment area and the side edge of the tube sheet or part of that area. The flanking areas are defined as the areas on either side of an attachment area which form, with their imaginary planes, an angle relative each other when the tube structure is bended by means of the bend arrangement.

The imaginary planes of the two flanking areas intersect and may have the same angle relative each other along the entire intersecting line, or a varying angle relative each other along the intersecting line.

It is possible to adjust the angle of the bend of the inflatable tube structure by adjusting the first and second distance. A shorter second distance in relation to the first distance gives a smaller angle i.e. a more distinct bond. The attachment means may comprise a loop and the engagement means comprise a hook or the attachment means may comprise a hook and the engagement means comprises a loop. This has the benefit that the bending means may be disengaged and exchanged if needed. The attachment means may be portions of the tube sheet, within the attachment area, upon which the engagement means are engaged, e.g. the engagement means are engaged by adhesive means directly upon the tube sheet. Similarly the engagement means may be portions of the bending means upon which the attachment means are engaged e.g. by adhesive means, high-frequency welding, hotair and/or hot wedge. Engagement by such means minimizes the risk of damaging the tube sheet, causing possible leakage. Thereby the manufacturing process and assembly process is simplified.

In one aspect of the invention the engagement between the engagement means and the attachment means is achieved by high-frequency welding.

At least one engagement means may also be permanently engaged to at least one attachment means. Thereby, the bending means may be permanently engaged such that the inflatable tube structure comprises a bending means arranged upon the tube sheet by means of attachment means and engagement means. In one aspect of the invention the engagement means are engaged to the attachment means prior to inflating the tube structure. The engagement means may be engaged to the attachment means by high-frequency welding.

The attachment arrangement may comprise one pair of attachment means arranged on a central longitudinally extending line of the attachment area and at least two engagement means are arranged upon a central longitudinally extending line of the bending means.

In such a design the bending means may comprise a piece of string extending in a longitudinal direction. The engagement means are thus arranged at a second distance from each other upon the string, and thereby the length of the string determines the bend of the inflatable tube structure by creasing the attachment area. A shorter string results in more creasing of the attachment area, and hence a more distinct bend to the tube structure.

The attachment arrangement may comprise at least two pairs of attachment means arranged on a longitudinally extending line of the attachment area and at least two pairs of engagement means are arranged upon a longitudinally extending line of the bending means, wherein the first pair of attachment means engage the first pair of engagement means and the second pair of attachment means engage the second pair of engagement means, the first distance of one pair of attachment means being shorter than the second distance of the corresponding pair of engaging engagement means such that, upon inflation of the tube structure, the tube structure bends by creasing the attachment area.

A design with at least two pairs of attachment means and at least two pairs of engagement means results in a better force distribution across the bending means as well as a more stable bend of the inflatable tube construction. The position of the imaginary planes of the flanking areas relative each other is stabilized i.e. the design eliminates the risk of twisting of the tube structure. A tube structure of such design is thereby generally capable of standing alone, without support structures. Arranging the attachment means and the engagement means in pairs and arranging the pairs crosswise also function to hold the excess tube sheet present at the attachment area i.e. the creases, up thus hindering it from bulging downwards. The visual impact is thus improved. The distance between the two attachment means of each pair does not have to be equal. Similarly the distance between the two engagement means of each pair does not have to be equal. The longitudinal extension of the bending means may vary and the shape of the bending means may take a variety of shapes. If the distances between the pairs differ then the distance between the third and fourth engagement means is a third distance and the distance between the third and fourth attachment means is a fourth distance. The third distance is preferably shorter than the fourth distance such that the tube sheet creases over the attachment area upon inflation of the tube structure causing the tube structure to bend. The distances between the pairs are set such as to determined the bend; equal distances (first vs third and second vs fourth) form a straight bend and non-equal distances (first vs third and second vs fourth) form a displaced or twisted bend. If the distances between the pairs are the same then the third distance is equal to the second distance and the forth distance is equal to the first distance. This allows for symmetry of the bending means and the attachment arrangement.

The attachment arrangement may also comprise a third pair of attachment means comprising a fifth and a sixth attachment means arranged on a transverse extending line of the attachment area in between the first and third and the second and forth attachment means respectively, and wherein the bending means comprises a third pair of engagement means comprising a fifth and sixth engagement means arranged on a transverse extending line of the bending means and wherein the fifth engagement means is adapted to engage with the fifth attachment means and the sixth engagement means is adapted to engage with the sixth attachment means. According to the invention the bending means may have an extension in transverse direction.

One benefit with the third pair of engagement means is that the bending means may be snugly arranged to the tube structure at the corner of the bend, i.e. to the intersection line of the planes between the first and second flanking areas, by adjusting the distance between the third pair of engagement means. Also, the third pair of engagement means helps holding the excess tube sheet material in the attachment area such that it does not bulge downwards. Thus, the visual impact of the bended corner of the tube structure is improved.

The attachment arrangements and engagement means with one or more pairs described above may be freely combined.

The first and second pair of attachment means may be arranged at the corners of the attachment area. Thereby the entire attachment area creases upon engagement with the engagement means of the bending means. The extension of the attachment area is thus defined by the attachment arrangement.

The bending means may comprise at least two strings wherein a first string is arranged between the first pair of engagement means and a second string is arranged between the second pair of engagement means such that the first and second strings intersect. Such a design is easy to manufacture.

The bending means may comprise at least four strings wherein the third string is arranged longitudinally across the bending means between the first engagement means of the first pair of engagement means and the fourth engagement means of the second pair of engagement means and the fourth string is arranged longitudinally across the bending means between the third arrangement means of the second pair of arrangement means and the second arrangement means of the first pair of arrangement means respectively. Thereby the bend of the inflatable tube structure is stabilized in longitudinal and transverse direction. Also, the excess material of the attachment means is kept up, improving visual impression of the tube structure.

The bending means may comprise a bending means sheet material extending in a longitudinal direction and a transverse direction. The sheet material will collect the excess tube sheet in the creased attachment area when the bending means is engaged to the attachment means by its engagement means, e.g. by high frequency welding. Thereby, the excess tube sheet material is not visual to an observer. If the bending means is provided with six engagement means the bending means sheet material may be arranged snug to the corner of the bend such that overall visual impact of the inflatable tube structure is improved. Six attachment means; two pairs of which exert a cross-wise pulling force to enforce the bend and one pair which is arranged transverse, will provide stability in longitudinal and transverse direction to the tube structure once inflated. It will also minimize the risk of rotational movements of the tube structure.

The design of the bending means, that is the distance upon which the engagement means are positioned relative each other, predetermines the angle of the bend. The desired bend angle predetermines the positioning of the attachment means upon the attachment area. The attachment means cooperate with the bending means, via the engagement means, in order to achieve the desired, predetermined bend once the tube structure is inflated. The engagement means may preferably be arranged at the corners of the bending means sheet material, determining the longitudinal extension of the bending means and such that the entire bending sheet material is held up by the engagement means. The engagement means may however also be arranged at a distance from the corners. The engagement means of the two pairs exerting a cross-wise pulling force are arranged diagonally relative a longitudinal direction of the bending means.

Further, sheet material of the bending means may have a first and a second cut out wherein the first cut-out is arranged at a first traverse side of the bending means and the second cut-out is arranged at a second traverse side of the bending means such that a waist is formed along the central longitudinal line of the bending means. The cut-outs are intended to be arranged adjacent the transition between the attachment area and the first and second flanking areas such that the cut-outs facilitates the centre of the bending means being arranged closer to the corner of the bend. The first and second cut-out is preferably crescent-shaped as it allows for improved fit of the bending means relative the creased attachment area of the tube sheet.

The distance between the fifth and sixth engagement means may determine the transverse extension of the bending means. Thus, the fifth and sixth engagement means are arranged at the longitudinal edges of the bending means or on a transverse protruding part of the bending means. However, they may also be arranged at a distance from the longitudinal edges.

The inflatable tube structure according to the invention may comprise at least two bend arrangements and the at least two bend arrangements are preferably arranged along a central longitudinal line of the sheet such that symmetry is achieved. An inflatable tube structure with several bend arrangements arranged symmetrically may form an arch. The bend arrangements may however also be arranged offset from the central longitudinal line of the tube sheet. The number of bend arrangements determines the shape of the arch of the roof truss construction, e.g. two bend arrangements results in a rectangular arch and three bend arrangements results in a more curved arch.

The longitudinal position of the bend arrangement determines the position of the bend along the inflatable tube structure.

The invention also concerns a system of inflatable tube structures. The system of inflatable tube structures may for example be used as roof trusses in an inflatable house or tent construction, or in any other suitable construction. The system of inflatable tube structures are preferably arranged such that a sheet of material may be provided upon the system such that the sheet span between the inflatable tube structures thereby forming a roof or wall.

The invention also concerns an inflated tube comprising an inflatable tube structure as disclosed above wherein the engagement means are engaged to the attachment means, wherein the tube structure is inflated and wherein the inflated tube comprise a bend over the attachment area. The inflated tube is provided with sealed ends and is airtight. The invention also concerns a method for bending an inflatable tube structure for roof truss construction comprising the steps of providing a tube sheet with longitudinal sealing means along the longitudinal edges of the tube sheet, providing a tube sheet with an attachment area extending in a longitudinal direction and a transverse direction on the tube sheet, arranging an attachment arrangement comprising at least two attachment means longitudinally relative each other at a first distance on the attachment area of the tube sheet, folding the tube sheet over itself and joining the longitudinal sealing means such that a tube is formed, providing a bending means with at least two engagement means arranged longitudinally relative each other at a second distance upon the bending means, engaging the engagement means of the bending means with the attachment means and inflating the tube structure such that the tube sheet creases over the attachment area thereby causing the inflatable tube structure to form a bend over the attachment area. The method further comprises the step of positioning the attachment means upon the attachment area relative each other such as to form a predetermined bend upon engagement with engagement means of the bending means and positioning the engagement means upon the bending means. In one aspect of the invention arranging the attachment means on the attachment area of the tube sheet and engaging the engagement means of the bending means with the attachment means is achieved by high-frequency welding. The attachment means and the engagement means may be permanently engaged prior to inflating the tube structure.

The term "creases" used herein to describe the present invention is used to represent any type of reaction a part of a tube sheet displays upon pulling that part closer together such that there is no longer any tension in the sheet material of that area. Hence the term should not be seen as limited but be interpreted as creases, bulges, folds inwards or outwards, constricts, relaxes or any other plausible reaction upon removal of tension.

The core of the invention is that at least a first distance, defined as the distance in longitudinal direction of the tube structure between the attachment means arranged upon the tube sheet, is longer than at least a second distance, defined as the distance in longitudinal direction of the tube structure between the engagement means arranged upon the bending means being engaged to the attachment means. Thereby, the portion of the tube structure intermediate the attachment means is pulled together such that it creases. The tube structure therefore bends around this portion upon inflation such that an angle is formed.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described in detail with reference to the figures, wherein:

Figure 1 shows a tube sheet according to the invention;

Figure 2a-b shows a tube structure according to Figure 1 without and with bending means;

Figure 3 shows a tube sheet according to the invention;

Figure 4a-b shows a tube structure according to Figure 3 without and with bending means;

Figure 5 shows a tube sheet according to the invention;

Figure 6 shows a tube structure according Figure 5;

Figure 7a shows a bending means according to the invention; and

Figure 7b shows a tube structure with three bend arrangements according to the invention. DETAILED DESCRIPTION OF THE DRAWINGS

In the following the invention will be described in conjunction with the figures. The figures are simply ways of illustration different modes of carrying out the invention. The invention is not limited to the examples in the figures. Figure 1 shows a tube sheet 2 extending in a longitudinal direction (y direction) and a transverse direction (x direction) comprising longitudinal sealing means 3 along the longitudinal edges 4. It further shows an attachment area 8 of the tube sheet 2 extending in a longitudinal direction (y direction) and a transverse direction (x direction) on the tube sheet 2 and is arranged along a central longitudinal line. Two attachment means, forming a pair of attachment means 101 , are arranged longitudinally relative each other at a first distance on the attachment area 8 of the tube sheet 2. These two attachment means 101 represents an attachment arrangement 9. The attachment area 8 is a portion of the tube sheet 2 upon which the attachment means 101 are arranged, and the attachment area 8 extends between the two attachment means 101 such that part of the attachment area is intermediate the two attachment means 101 .

Figure 2a shows inflated tube structure 1 in which the longitudinal sealing means 3 along the longitudinal edges 4 are joined and sealed. The tube structure 1 has two tube ends 6. These tube ends comprise joined tube end sealing means such that the tube structure 1 is airtight and inflatable. The attachment means 101 seen in figure 2a are illustrated as loops. These loops are arranged along the traverse edges of the attachment area 8, and the longitudinal distance between the two loops is the first distance.

Figure 2b shows a bend arrangement 7 comprising bending means 103 engaged to the attachment arrangement 9 upon the attachment area 8 of the tube sheet 2 of figure 1 and the inflated tube structure 1 of figure 2a. The bending means 103 is extending in a longitudinal direction, i.e. in the same direction that the attachment means 101 are arranged relative each other. The bending means 103 is represented by a string in figure 2b. The bending means 103 comprises two engagement means 102 arranged longitudinally relative each other at a second distance upon the bending means 103. In figure 2b the engagement means 102 are represented by hooks adapted to engage with the loops of the attachment arrangement 9. In figure 2b the second distance is shorter than the first distance and the tube sheet 2 thus creases over the attachment area 8, between the attachment means 101 in longitudinal direction of the tube sheet 2, the upon inflation of the tube structure 1 causing the inflatable tube structure 1 to form a bend over the attachment area 8.

Another attachment arrangement 9, comprising four attachment means arranged at the four corners of the attachment area 8 is shown in figure 3. The attachment area 8 is flanked at its two transverse extending edges by two flanking areas 10. These flanking areas 10 are not discrete, but represented by the portions of the tube sheet 2 flanking the attachment area 8.

The four attachment means in figure 3 are arranged in a first pair 201 comprising a first and second attachment means and a second pair 201 ' comprising a third and fourth attachment means. The first and second pairs 201 , 201 ' are arranged diagonally offset from a central longitudinally extending line of the attachment area 8 and in opposite direction relative each other such that a first imaginary line extending between the first and second attachment means of the first pair 201 and a second imaginary line extending between the third and fourth attachment means of the second pair 201 ' intersect.

In figure 4a the tube sheet 2 of figure 3 is formed into a tube structure 1 by sealing the longitudinal sealing means 3 along the longitudinal edges 4. Figures 4a-b shows a bending arrangement 7 before and after a bending means 203 is engaged.

In Figure 4b the bending means 203, in the form of a first and a second crosswise arranged string, are engaged to the attachment arrangement 9. The bending means 203 further comprises four engagement means. The first and second engagement means are arranged in a first pair 202 at opposite ends of the first string and a third and fourth engagement means are arranged in a second pair 202' at opposite ends of the second string. Thereby, the first and second pair 202, 202' are arranged diagonally offset from a central longitudinally extending line of the bending means and in opposite direction relative each other. The first pair of engagement means 202 engages the first pair of attachment means 201 and the second pair of engagement means 201 ' engages the second pair of attachment means 202'. The second distance, being the distance between engagement means of the first pair 202, is shorter than the first distance, being the distance between attachment means of the first pair 201 . Similarly the second distance, being the distance between engagement means of the second pair 202', is shorter than the first distance, being the distance between attachment means of the second pair 201 '. The tube sheet 2 creases over the attachment area 8 and the tube structure 1 form a bend over the attachment area 2 as seen in figure 4.

The imaginary planes of the flanking areas 10 of the tube structure 1 relative each other shown in figure 4 determine the angle of the bend.

Figure 5 shows a tube sheet 2 comprising three attachment arrangements arranged upon three attachment areas 8. Each attachment arrangement comprises six attachment means arranged in three pairs 301 , 301 ', 301 " wherein the first pair 301 and second pair 301 ' is consistent with the attachment means pairs 201 , 201 ' of figure 3. The first and second pairs 301 , 301 ' are arranged diagonally offset from a central longitudinally extending line of the attachment area 8 and in opposite direction relative each other such that a first imaginary line extending between the first and second attachment means of the first pair 301 and a second imaginary line extending between the third and fourth attachment means of the second pair 301 ' intersect. This means that the attachment means of the first and second attachment means pairs extend in a diagonal direction relative to a central longitudinally extending line of the bending means. The third pair of attachment means 301 " comprising a fifth and a sixth attachment means arranged on a transverse extending line of the attachment area 8 in between the first and third and the second and forth attachment means respectively.

Each attachment area 8 in figure 5 is flanked in longitudinal direction on each side by a flanking area 10, wherein two of the flanking areas 10 being common between two attachment areas 8.

Figure 6 shows the tube structure 1 formed by joining the sealing means 3 of the longitudinal extending edges 4 of the tube sheet 2 of figure 5. The tube ends 6 are also seen in figure 6.

In figure 7a, a bending means 303 in the form of a sheet material is seen. The bending means 303 comprises three pairs of engagement means 302, 302', 302" arranged at the protruding parts of the sheet material wherein the first pair 302 comprise a first and second engagement means and the second pair 302' comprising a third and fourth engagement means. The first and second engagement means extend in a diagonal direction relative to a central longitudinally extending line of the bending means. The first and second pair 302, 302' are arranged diagonally offset from a central longitudinally extending line of the bending means and in opposite direction relative each other such that the pulling force extending between the first and second engagement means which occur when the first pair of engagement means 302 engages a first pair of attachment means and the pulling force extending between the third and fourth engagement means which occur when the second pair of engagement means 302' engages a second pair of attachment means intersect. Thereby the forces are distributed over the bending means 303.

The bending means 303 as shown in figure 7a further comprise a first cut-out arranged at a first traverse side of the bending means 303 in between the first engagement means of the first pair of engagement means 302 and the first engagement means of the second pair of engagement means 302' and the second cut-out is arranged at a second traverse side of the bending means 303 in between the second engagement means of the first pair of engagement means 302 and the second engagement means of the second pair of engagement means 302' such that a waist is formed along the central longitudinal line of the bending means 303. Such a waist facilitates a snug fit of the bending means 303 upon an attachment area of a tube sheet as well as facilitates the force distribution. The bending means 303 further comprise a third pair of engagement means 302" arranged in a transverse direction across the bending means 303. These engagement means are arranged transversely on protruding parts of the bending means 303. Figure 7b shows an inflated tube structure 1 comprising three bend arrangements 7. The three bend arrangements 7 each comprise an attachment arrangement 9 according to figure 5 and a bending means 303 according to figure 7a. The tube sheet 2 thereby crease over three attachment areas 8 causing the tube structure 1 to form three bends i.e. the tube structure 1 arches. The creases of the three attachment areas 8 are not seen in figure 7b because the attachment areas 8 are located underneath the sheet material of the bending means 303 upon engagement of the engaging means 302, 302', 302" of the bending means 303 to the attachment means 301 , 301 ', 301 " of the attachment arrangement 9. The first distances, that of the first pair 301 and second pair 301 ' of the attachment means, are longer than the respective second distances, that of first pair 302 and second pair 302' of the engagement means, thereby causing the tube structure to form a bend over the attachment areas. The distance between the attachment means of the third pair 301 " and the distance between the engagement means of the third pair 302" are the same, thereby not causing the tube structure 1 to bend in transverse direction. Their function in the example shown in figure 7b is to support the sheet material of the bending means 303 and improve the visual aspect of the tube structure 1 . The cutouts of the bending means 303 are arranged adjacent the transition between the attachment area and the first and second flanking areas such that the centre of the bending means 303 is arranged close to the corner of the bend. This improved the visual impact of the tube structure 1 once inflated.

The invention is not limited to the specific embodiments presented, but includes all variations within the scope of the present claims.

As will be realised, the invention is capable of modification in various obvious respects, all without departing from the scope of the appended claims. For example, the bending means may comprise of rope, paper, plastic etc. and have other shapes then the ones exemplified herein. The engagement means may be arranged at positions different from the ones shown in the embodiments above. Accordingly, the drawings and the description thereto are to be regarded as illustrative in nature, and not restrictive.

Reference signs mentioned in the claims should not be seen as limiting the extent of the matter protected by the claims, and their sole function is to make claims easier to understand.