Expandable tubular element for an inflatable cylinder

Abstract

The present invention relates to an expandable tubular element (3, 37) for a fluid-inflatable cylinder, the perimeter wall (7) being fluid-tight and comprising a plurality of panels (9) connected in pairs by substantially linear links (11) each representing a pivot axis, the panels (9) being more rigid than the links (11) so that two panels (9) adjacent to a link (11) can rotate about the pivot axis represented by that link (11), each end of the links (11) being connected to at least two ends of other links (11) to define nodes (13), each node (13) having a thickness greater than the smallest thickness of the adjacent links (11). The present invention also relates to a method for manufacturing such an expandable tubular element (3, 37) as well as a fluid-inflatable cylinder (1, 35, 39) comprising such an expandable tubular element (3, 37).

Description

[Technical field]

[0001] The present invention relates to the field of inflatable cylinders. [Background technology]

[0002] These inflatable cylinders are commonly used in devices such as shock absorbers or actuators.

[0003] Such inflatable cylinders are generally inflated with air, but can also be used with water, oil, glycol or more generally with fluids. These inflatable cylinders, also called airbags, are generally composed of an expandable tubular element made of rubber or plastic material, optionally covered with an end piece or placed between two end pieces. The tubular element generally comprises a peripheral wall in the form of a cylindrical bellows, obtained for example by blow molding a parison of thermoplastic elastomer material. The end pieces are generally made of metal and engage with a mechanical element configured to be driven by the inflatable cylinder. To allow good compressibility of the tubular element and to limit the size of the inflatable cylinder, the peripheral wall of the tubular element has a variable thickness.

[0004] However, such thickness variations are difficult to manufacture and result in areas of low pressure resistance, especially when the inflatable cylinder is fully expanded. In the event of excessive pressure, in fact the peripheral wall of the tubular element has a variable thickness, so that the tubular element can undergo significant local deformation beyond its maximum desired shape in its thinnest area, i.e. in the circular cross section of a cylindrical bellows. The pressure resistance of a tubular element for such an inflatable cylinder is therefore low taking into account the minimum thickness of the peripheral wall of the tubular member.

[0005] Therefore, due to their design, current inflatable cylinders are unable to have both small size and optimal pressure resistance. Summary of the Invention

[0006] The present invention has in particular an object to provide an expandable tubular element for an inflatable cylinder which has both limited size and optimal pressure resistance.

[0007] To this end, the invention provides a peripheral wall, the peripheral wall being fluid-tight and formed by a plurality of panels, the panels being connected in pairs by substantially linear links each of which represents a pivot axis, The panel is more rigid than the link, so that the two panels adjacent to the link can rotate around the pivot represented by this link, Each end of a link is connected to at least two ends of other links to define a node; Each node is associated with an expandable tubular element for a fluid-inflatable cylinder having a thickness greater than the minimum thickness of the adjacent links.

[0008] It is therefore proposed to implement the invention by providing an expandable tubular element in which the nodes reinforce the structure. Even with links of small thickness, the radial deformations undergone by the expandable tubular element are in fact limited due to the presence of the nodes. This improves the pressure resistance of the expandable tubular element. The structure made up of panels, links and nodes allows a maximum compressibility of the expandable tubular element and therefore a minimum size of the expandable tubular element in compressed state.

[0009] According to other optional features of the expandable tubular element, the following may be employed alone or in combination: - the link is made mainly of plastic material. "Mainly" means mainly by weight, therefore making it easier to manufacture. the panels have a polygonal, preferably triangular, shape, which improves the compressibility and resistance of the expandable tubular element; The panels have a substantially uniform thickness, thus simplifying manufacture. The nodes have substantially the same thickness as the panels, thus further reducing the size of the expandable tubular element. at least one of the links has the same composition as at least some of the panels adjacent said link and, at least in places, a thickness less than the thickness of these panels, which simplifies the manufacture of the expandable tubular element and makes it easier to compress the expandable tubular element; -The panels and links have the same composition, therefore simplifying the manufacturing. - The panels consist mainly of plastic material, "mainly" meaning mainly by weight, therefore making them easier to manufacture. The peripheral wall consists mainly of plastic material, "mainly" meaning mainly by weight, which makes it easier to manufacture. The perimeter wall is formed by panels and links. the peripheral wall preferably consists of a composite or multi-layer material comprising a polymeric and / or elastomeric material, more preferably polypropylene and / or polyethylene, which increases the pressure resistance of the expandable tubular element; The circumferential wall is made of a composite or multi-layer material, preferably including a metallic material, which increases the pressure resistance of the expandable tubular element. the peripheral wall is made of a multi-layer material and comprises a conductive layer, preferably made of metal, more preferably made of a conductive ink and / or a metal film, arranged on the inner and / or outer surface of the peripheral wall, so that the expandable tubular element can, for example, conduct electricity to a supply element located downstream of the expandable tubular element for a source of electrical energy and / or act as a sensor, since the electrical resistance of the expandable tubular element is modified depending on its deformation state; The conductive layer is the innermost layer, thus simplifying the connection to devices located inside the expandable tubular element, such as electrical energy sources, transducers or antennas. the conductive layer is the outermost layer, thus allowing easy connection to devices located outside the expandable tubular element, such as electrical energy sources, transducers or antennas; - At least one of the links is formed by an adhesive film connecting two adjacent panels, thus simplifying the manufacture of the tubular element.

[0010] The invention also relates to a fluid-inflatable cylinder comprising an expandable tubular element of the type described above and an end piece attached to one end of the expandable tubular element.

[0011] According to other optional features of the inflatable cylinder, the following may be employed alone or in combination: - the end pieces are provided with means for supplying and / or discharging a fluid, and the extendable tubular element is configured to switch from a contracted mode with a first internal volume to an extended mode with a second internal volume and a substantially cylindrical shape, the second internal volume being preferably at least 10 times, more preferably at least 100 times larger than the first internal volume. Thus, by providing an inflatable cylinder with an extendable tubular element, the end pieces of which are provided with means for supplying and / or discharging a fluid, the structure of the extendable tubular element in the form of panels, links and nodes allows a maximum compressibility of the extendable tubular element, and thus a minimum size of the extendable tubular element, when the inflatable cylinder is in a contracted state, while ensuring a high pressure resistance when the inflatable cylinder is in an extended state. The extendable tubular element has a substantially bent cylindrical shape in the extension mode, so that actuation can be obtained in any desired spatial direction. When the expandable tubular element is in contraction mode, the fluid pressure inside the expandable tubular element is 0-1 bar. When the expandable tubular element is in the extension mode, the fluid pressure inside the expandable tubular element is 1-12 bar. the inflatable cylinder further comprises guide means, preferably telescopic guide rods, for guiding the displacement of the telescopic tubular element between its contracted mode and its extended mode and vice versa; the guide means are arranged in an internal space bounded by the peripheral wall of the extensible tubular element; the guide means are arranged outside the internal space bounded by the peripheral wall of the extensible tubular element and are preferably evenly distributed around the circumference of the extensible tubular element; The inflatable cylinder has two end pieces, each attached to one end of an expandable tubular element. The inflatable cylinder comprises a means for limiting the stroke, for example consisting of a sheath, preferably a fabric, arranged outside the circumferential wall of the expandable tubular element. The inflatable cylinder comprises means for transmitting energy, preferably fluid transfer pipes and / or electrical cables, arranged in the internal space of the expandable tubular element. The inflatable cylinder comprises at least two extendable tubular elements. The expandable tubular elements are arranged in series. Adjacent expandable tubular elements arranged in series are connected to one another via at least one end piece. The inflatable cylinder comprises at least three extendable tubular elements. The expandable tubular elements are arranged in parallel. The parallel-arranged, extendable tubular elements each have an end piece and jointly support the plate. The peripheral wall is joined to the end pieces. It is therefore particularly easy to attach the extendable tubular element to the end pieces. the end piece comprises a flange and a mounting element, the peripheral wall being held in the end piece by a clamp between the flange and the mounting element, it is therefore particularly easy to mount the extendable tubular element in the end piece;

[0012] Finally, the invention relates to a method for manufacturing an expandable tubular element of the above-mentioned type, said method comprising the following steps: - manufacturing a tube consisting essentially of plastic material, - generating a plurality of patterns on the tube by engraving and / or marking means; - a step of deforming the pattern in such a way that the pattern in the deformed state forms links, which is carried out by reducing the pressure inside the tube, preferably to a pressure of 0-0.5 bar, and / or by simultaneously mechanically pressing the pattern located on a given cross section of the tube.

[0013] The manufacture of the expandable tubular element is therefore simple and cheap.

[0014] According to other optional features of the manufacturing method, the following are employed, alone or in combination: The pattern is, for example, a cylindrical pattern of the type known under the names Yoshimura, Waterbomb, Kresling or Chicken Wire patterns, preferably a Kresling type pattern. The step that transforms the pattern is the folding step. The step of producing a tube consisting essentially of plastic material is a step of producing a tube consisting exclusively of plastic material. The step of producing the tube, which is mainly made of plastic material, is carried out by thermoforming, injection blow molding, moulding or rotational moulding. the engraving means comprises a laser; The marking means comprises a wheel. The step of generating a plurality of patterns on the tube by engraving and / or marking means is carried out by laser engraving followed by marking with a wheel. The method preferably comprises, after the step of deforming the pattern, a step of hardening the expandable tubular element thus obtained by annealing, so that its rest mode is a contracted mode.

[0015] The invention will be better understood on reading the following description, given purely by way of example and with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 is a schematic front view of an inflatable cylinder according to a first embodiment in an extended state. [Diagram 2] FIG. 2 is a schematic front view of an inflatable cylinder with an extendable tubular element according to a first embodiment in a contracted state; [Diagram 3] FIG. 11 is a schematic perspective view of an end piece according to a first modified example. [Figure 4] FIG. 13 is a schematic perspective view of an inflatable cylinder according to a second embodiment in an extended state. [Diagram 5] FIG. 13 is a schematic perspective view of an inflatable cylinder according to a third embodiment in an extended state. [Figure 6] FIG. 13 is a schematic front view of an inflatable cylinder according to a fourth embodiment in an extended state. [Figure 7] FIG. 11 is a schematic perspective view of an inflatable cylinder according to the fifth embodiment in an extended state, with an end piece according to a second variant. [Figure 8] FIG. 2 is a partial schematic front view of an inflatable cylinder according to a variant of the first embodiment in an extended state. [Figure 9] FIG. 2 is a schematic front view of an expandable cylinder according to a variant of the first embodiment in an extended state; [Figure 10] FIG. 2 is a partial schematic front view of an inflatable cylinder according to a variant of the first embodiment in an extended state. [Figure 11] FIG. 2 is a partial schematic front view of an inflatable cylinder according to a variant of the first embodiment in an extended state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Fig. 1 shows an inflatable cylinder 1 according to a first embodiment. The inflatable cylinder 1 can be inflated by a fluid, for example air or water. The inflatable cylinder 1 comprises an extendable tubular element 3 and an end piece 5 according to a first variant attached to one end of the extendable tubular element 3. In the example shown in Fig. 1, the inflatable cylinder 1 comprises two end pieces 5, each end piece 5 attached to one end of the extendable tubular element 3.

[0018] The expandable tubular element 3 comprises a peripheral wall 7 .

[0019] The peripheral wall 7 is fluid tight. The peripheral wall 7 is formed by a number of panels 9 connected in pairs by substantially linear links 11 each representing a pivot axis.

[0020] The panels 9 are more rigid than the links 11. Thus, the two panels 9 adjacent to a link 11 can rotate about a pivot axis represented by this link 11. In the example shown in FIG. 1, the panels 9 have a triangular shape. More generally, the panels 9 may have a polygonal shape. In the example shown in FIG. 1, the panels 9 have a substantially uniform thickness.

[0021] Each link 11 has two ends, each end of which is connected to at least two ends of other links 11 so as to define a node 13. In the example shown in Figure 1, the links 11 have the same composition as the composition of the panels 9 adjacent to said link 11, and at least in places have a thickness less than the thickness of these panels 9.

[0022] Each node 13 has a thickness that is greater than the smallest thickness of the adjacent links 11. Moreover, in the example shown in FIG.

[0023] As shown in Figures 1 and 3, each end piece 5 comprises a flange 15 and a mounting element 17. The peripheral wall 7 is thus held in the end piece 5 by a clamp between the flange 15 and the mounting element 17. The mounting element 17 and the flange 15 each comprise a thread, so that the mounting element 17 is attached to the flange 15 by screwing. In this example, the flange 15 has a substantially cylindrical shape.

[0024] At least one end piece 5, e.g. each end piece 5, comprises means 19 for supplying and / or draining a fluid, e.g. a central hole 21 opening into an interior space bounded by the peripheral wall 7 of the expandable tubular element 3. In the example shown in Figure 1, the central hole 21 is threaded to allow connection to a fluid supply and / or drainage element, e.g. a flexible pipe end fitting.

[0025] The expandable tubular element 3 is thus configured to switch from a contracted mode having a first internal volume as shown in Figure 2 to an expanded mode having a second internal volume and a substantially cylindrical shape as shown in Figure 1, or vice versa. The second internal volume is preferably at least 10 times, more preferably at least 100 times, larger than the first internal volume.

[0026] The fluid pressure inside the expandable tubular element 3 is preferably between 0 and 1 bar when the expandable tubular element is in contracted mode. The fluid pressure inside the expandable tubular element 3 is between 1 and 12 bar when the expandable tubular element is in extended mode.

[0027] The peripheral wall 7 consists mainly of a plastic material. The peripheral wall 7 is therefore formed by the panels 9 and the links 11, the links 11 consisting mainly of a plastic material and the panels 9 consisting mainly of a plastic material. In the example shown in FIG. 1, the peripheral wall 7 consists of a multi-layer material, preferably including a polymeric and / or elastomeric material, more preferably polypropylene and / or polyethylene. More precisely, the peripheral wall 7 comprises a main layer consisting mainly or completely of a plastic material, preferably a polymeric and / or elastomeric material, more preferably polypropylene and / or polyethylene. The peripheral wall 7 also comprises a conductive layer 23, preferably made of metal, more preferably consisting of a conductive ink and / or a metal film, arranged on the inner and / or outer surface of the peripheral wall 7. The conductive layer is the innermost layer and / or, as shown in FIG. 1, the conductive layer 23 is the outermost layer.

[0028] Alternatively or additionally, the peripheral wall 7 or its main layer may consist of a composite material. Thus, the peripheral wall 7 or its main layer may consist of a material selected from the group comprising thermoplastics, preferably polypropylene and / or polyethylene, preferably reinforced with carbon fibres, glass fibres, natural fibres and / or Kevlar®.

[0029] Each end piece 5 consists, for example, of a plastic, composite or metal material. If the end piece 5 consists of a composite material, it may consist of a thermosetting resin, preferably an epoxy, polyurethane or polyester resin, preferably reinforced with carbon fibres, glass fibres, natural fibres or Kevlar.

[0030] In the second embodiment shown in Fig. 4, the inflatable cylinder 25 comprises three extendable tubular elements 3 arranged in parallel, each of which is provided with an end piece 5 at each end and jointly supports the plates 25, 27. Thus, the inflatable cylinder 25 according to this second embodiment comprises three inflatable cylinders 1 according to the above-mentioned first embodiment arranged in parallel between two plates 25, 27.

[0031] The inflatable cylinder 25 can obviously be made with four or more extendable tubular elements 3 .

[0032] In a third embodiment shown in Fig. 5, an inflatable cylinder 31 comprises two extendable tubular elements 3 arranged in series and equipped at each end with an end piece 5. The two extendable tubular elements 3 are thus connected to each other via the two end pieces 5 mounted opposite each other, for example by means of mounting bolts engaging in mounting holes 33 of the end pieces 5, as shown in Fig. 5. An inflatable cylinder 31 according to this third embodiment thus comprises two inflatable cylinders 1 according to the above-mentioned first embodiment arranged in series.

[0033] The inflatable cylinder 31 can obviously be made with more than two extendable tubular elements 3. In this case, adjacent extendable tubular elements 3 are connected to one another via at least one end piece 5, preferably via two end pieces 5.

[0034] The fourth embodiment shown in Fig. 6 differs from the first embodiment shown in Fig. 1 in that the inflatable cylinder 35 comprises an expandable tubular element 37 having a substantially bent cylindrical shape in the expanded mode. Apart from this special shape of the expandable tubular element 37, the inflatable cylinder 35 is similar to the inflatable cylinder 1, in particular comprising an end piece 5 at each end of the expandable tubular element 37. Apart from this special shape, the expandable tubular element 37 is therefore similar to the expandable tubular element 3 described above. Moreover, in the contracted mode, the inflatable cylinder 35 takes a shape similar to that shown in Fig. 2 for the inflatable cylinder 1.

[0035] The fifth embodiment shown in figure 6 differs from the first embodiment shown in figure 1 in that the inflatable cylinder 39 comprises an end piece 41 according to a second variant, arranged to replace the end piece 5 described above. Each end piece 41 comprises a flange 43, in this example substantially cuboid shaped, and a mounting element 17. The peripheral wall 7 of the extendable tubular element 3 is thus held in the end piece 5 by a clamp between the flange 43 and the mounting element 17. The mounting element 17 and the flange 43 each comprise a screw thread 15, so that the mounting element 17 is attached to the flange 43 by screwing.

[0036] At least one end piece 41, e.g. each end piece 41, comprises a means 19 for supplying and / or draining fluid, e.g. a lateral hole 45 opening into an internal space bounded by the peripheral wall 7 of the expandable tubular element 3. In the example shown in Fig. 7, the lateral hole 45 is threaded to allow connection to a fluid supply and / or drainage element, e.g. a flexible pipe end fitting. Each end piece 41 further comprises a mounting hole 47 which serves a similar function as the mounting hole 33 described above. Each end piece 41 is, for example, made of a similar material as described above for the end piece 5.

[0037] Different variants of the first embodiment are shown in Figures 8 to 10, with the expandable tubular element 3 being omitted in Figures 8 and 10 in order to clearly show the internal space bounded by the peripheral wall 7 of the expandable tubular element 3.

[0038] In the variant shown in figure 8, the inflatable cylinder 1 comprises guide means 49 for guiding the displacement of the telescopic tubular element 3 between its contracted mode and its extended mode and vice versa. The guide means 49 are arranged in the interior space bounded by the peripheral wall 7 of the telescopic tubular element 3. The guide means 49 comprise telescopic guide rods 51, for example made of metal.

[0039] In the variant shown in FIG. 9, the inflatable cylinder 1 comprises guide means 49 for guiding the displacement of the telescopic tubular element 3 between its contracted mode and its extended mode and vice versa. The guide means 49 are arranged outside the internal space bounded by the peripheral wall 7 of the telescopic tubular element 3 and are preferably evenly distributed around the telescopic tubular element 3. The guide means 49 comprise guide rods 53, for example made of metal, which are mounted, for example, in the mounting hole 33 of one end piece 5 and slide in the mounting hole 33 of the other end piece 5 to provide a linear guide. At least one guide rod 53 can comprise an end stop for acting as a stroke limiter of the inflatable cylinder 1 by preventing the telescopic tubular element 3 from sliding beyond a desired distance to obtain the extended mode, the end stop being in contact with the end piece 5 which thus slides relative to the guide rod.

[0040] In the variant shown in Fig. 10, the inflatable cylinder 1 comprises a means for transmitting energy 55, preferably a fluid transfer pipe and / or an electric cable, arranged in the inner space of the expandable tubular element 3. The means for transmitting energy 55 are used to transmit energy from one end piece 5 to the other end piece 5, for example to another inflatable cylinder and / or a sensor and / or an actuating element such as a valve or distributor connected to the inflatable cylinder 1. The means for transmitting energy 55 can also act as a stroke limiter of the inflatable cylinder 1, for example if the means for transmitting energy 55 consists of a cable. The means for transmitting energy 55 can have the shape of a coil, as shown in Fig. 10.

[0041] In the variant shown in FIG. 11, the inflatable cylinder 1 comprises stroke limiting means, for example consisting of a sheath 57, preferably of a woven fabric, arranged on the outside of the circumferential wall 7 of the telescopic tubular element 3. These stroke limiting means can be used to limit the displacement of the telescopic tubular element 3 between the contracted and extended modes. They therefore prevent the telescopic tubular element 3 from sliding more than the desired distance to obtain the extended mode, without hindering the displacement of the telescopic tubular element 3 between the extended and contracted modes. The sheath 57 is attached at its ends to the end pieces 5, for example by ties that tighten the diameter of the sheath 57 at its ends. It is therefore particularly easy to assemble the sheath 57 to the inflatable cylinder 1. The sheath 57 thus passes through the end pieces 5 and then the ties are tightened to hold the sheath 57 to the end pieces 5. In the example shown in FIG. 11, the telescopic tubular element 3 is in the extended mode and therefore the sheath 57 is stretched between the end pieces 5 so as to act as a stroke limiter.

[0042] Next, an example of a method for manufacturing an expandable tubular element will be described.

[0043] Such a method includes the following steps: - manufacturing a tube consisting essentially of plastic material, - generating a plurality of patterns on the tube by engraving and / or marking means; - a step of deforming the pattern so that the pattern in the deformed state forms links, which is carried out by reducing the pressure inside the tube, preferably to a pressure of 0-0.9 bar, and / or by simultaneously mechanically pressing the pattern located on a given cross section of the tube.

[0044] The pattern may be, for example, a cylindrical pattern of the type known by the names Yoshimura, Waterbomb, Kresling or Chicken Wire patterns, preferably a Kresling type pattern.

[0045] The step of deforming the pattern is for example a folding step. The step of producing a tube mainly made of plastic material is for example a step of producing a tube exclusively made of plastic material.

[0046] The step of manufacturing a tube made mainly of plastic material is performed by thermoforming, injection blow molding, molding or rotational molding. The engraving means comprises a laser. The marking means comprises a wheel. The step of generating a plurality of patterns on the tube by the engraving and / or marking means is performed by laser engraving followed by marking with a wheel.

[0047] If the required rest mode of the inflatable cylinder is a contracted mode, the method preferably includes, after the step of deforming the pattern, a step of hardening the expandable tubular element thus obtained by annealing, so that its rest mode is a contracted mode.

[0048] To manufacture the inflatable cylinder, the expandable tubular element manufactured as described above is attached to the end pieces. More precisely, one or each end of the expandable tubular element is placed on a flange of the end piece and clamped thereon by a mounting element of the end piece. Alternatively, the expandable tubular element can be joined to the end piece.

[0049] Next, an example of the operation of the expansion cylinder according to the first embodiment will be described.

[0050] As shown in Fig. 1, the expandable tubular element of the inflatable cylinder 1 is in the extension mode. The fluid pressure inside the expandable tubular element 3 is then between 1 and 12 bar. Fluid is discharged from the expandable tubular element 3 via the fluid supply and / or discharge means 19 arranged on the end piece 5. As a result, the fluid pressure inside the expandable tubular element 3 decreases, causing the expandable tubular element 3 to contract until the expandable tubular element 3 is in the contracted mode shown in Fig. 2. In the contracted mode, the fluid pressure inside the expandable tubular element 3 is between 0 and 1 bar.

[0051] Conversely, when the expandable tubular element 3 is in the contracted mode and it is desired to switch the expandable tubular element 3 to the extended mode, fluid is introduced to the expandable tubular element 3 via the fluid supply and / or exhaust means 19 arranged on the end pieces 5. As a result, the fluid pressure within the expandable tubular element 3 increases, causing the expandable tubular element 3 to extend until it is in the extended mode shown in FIG.

[0052] The invention is not limited to the described embodiments, and other embodiments will be apparent to those skilled in the art.

[0053] Instead of or in addition to holding the peripheral wall 7 in the end pieces 5, 41 by clamps as described above, the end pieces 5, 41 and the peripheral wall 7 can also be joined to each other. The end pieces 5, 41 may also be provided with fluid and / or electrical energy connections.

[0054] Furthermore, at least one of the links 11 may be formed by an adhesive film connecting two adjacent panels 9 .

[0055] Finally, at least one of the panels 9 can be made from an insert with a stiffness greater than that of the links 11, the insert being, for example, made of metal, which is encapsulated in a plastic material to form the panel 9. This makes the manufactured panel 9 stiffer. [Explanation of symbols]

[0056] 1 Expandable cylinder 3 Expandable tubular elements 5 End Piece 7 Peripheral wall 9 Panel 11 Link 13 Nodes 15 Flange 17 Mounting elements 19 Means for supplying and / or discharging fluids 21 Central hole 23 Conductive layer 25 Plate 27 Plate 29 Expandable Cylinder 31 Expandable Cylinder 33 Mounting hole 35 Expandable Cylinder 37 Expandable tubular element 39 Expandable Cylinder 41 End Piece 43 Flange 45 Lateral hole 47 Mounting hole 49 Guide means 51 Telescopic guide rod 53 Guide rod 55 Means of transmitting energy 57 Sheath

Claims

1. a peripheral wall (7), the peripheral wall being fluid-tight and formed by a plurality of panels (9), the plurality of panels (9) being connected in pairs by substantially linear links (11), each of the panels representing a pivot axis; said link (11) being mainly made of plastic material; said panels (9) being more rigid than said links (11), so that the two panels (9) adjacent to a link (11) can rotate about a pivot axis represented by said link (11); Each end of a link (11) is connected to at least two ends of other links (11) to define a node (13); Each node (13) has a thickness greater than the minimum thickness of the adjacent links (11). An expandable tubular element (3, 37) for a fluid-expandable cylinder, characterized in that

2. 2. An expandable tubular element (3, 37) according to claim 1, wherein said nodes (13) have substantially the same thickness as said panels (9).

3. An expandable tubular element (3, 37) according to claim 1 or 2, wherein at least one of the links (11) has the same composition as at least some of the panels (9) adjacent to said link (11) and, at least in places, has a thickness less than the thickness of these panels (9).

4. An expandable tubular element (3, 37) according to any one of claims 1 to 3, wherein said peripheral wall (7) consists of a composite or multi-layer material.

5. An expandable tubular element (3, 37) as described in claim 4, wherein the peripheral wall (7) comprises a polymer and / or an elastomeric material.

6. An expandable tubular element (3, 37) as described in claim 5, wherein the peripheral wall (7) comprises some polypropylene and / or polyethylene.

7. An expandable tubular element (3, 37) according to any one of claims 4 to 6, wherein the peripheral wall (7) is made of a multi-layer material and comprises a conductive layer (23).

8. An expandable tubular element (3, 37) as described in claim 7, wherein the peripheral wall (7) includes a metal layer.

9. An expandable tubular element (3, 37) as described in claim 8, wherein the metal layer consists of a conductive ink and / or a metal film arranged on the inner and / or outer surface of the peripheral wall (7).

10. An expandable tubular element (3, 37) according to any one of the preceding claims, wherein at least one of said links (11) is formed by an adhesive film connecting two adjacent panels (9).

11. A fluid-expandable cylinder (1, 35, 39) comprising an expandable tubular element (3, 37) according to any one of claims 1 to 10 and an end piece (5, 41) attached to one end of the expandable tubular element (3, 37).

12. 12. A fluid-inflatable cylinder (1, 35, 39) as claimed in claim 11, wherein the end piece (5, 41) comprises means (19) for supplying and / or discharging a fluid, and the expandable tubular element (3, 37) is configured to switch from a contracted mode having a first internal volume to an extended mode having a second internal volume and a substantially cylindrical shape, the second internal volume being larger than the first internal volume.

13. A fluid-expandable cylinder (1, 35, 39) as described in claim 12, wherein the second internal volume is at least 10 times larger than the first internal volume.

14. A fluid-expandable cylinder (1, 35, 39) as described in claim 13, wherein the second internal volume is at least 100 times larger than the first internal volume.

15. A fluid inflatable cylinder (1, 35, 39) according to any one of claims 11 to 14, wherein the peripheral wall (7) is joined to the end piece (5, 41) or the end piece (5, 41) comprises a flange (15, 43) and a mounting element (17), and the peripheral wall (7) is held within the end piece (5, 41) by a clamp between the flange (15, 43) and the mounting element (17).

16. A method for manufacturing an expandable tubular element according to any one of claims 1 to 10, comprising the steps of: - manufacturing a tube mainly made of plastic material, - generating a plurality of patterns on said tube by engraving and / or marking means, - a step of deforming said pattern so that in the deformed state said pattern forms links, which is carried out by reducing the pressure inside the tube, preferably to a pressure of between 0 and 0.9 bar, and / or by mechanically pressing simultaneously said patterns located on a given cross section of the tube.

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