Low pressure tubular system comprising an expansion joint

Abstract

The invention relates to a low pressure tubular system, such as a vacuum tube train transportation system, comprising: a plurality of mutually connected tube segments having a longitudinal axis; wherein each tube segment comprises a central part and two outer end parts; wherein the tubular system is configured to maintain a low pressure environment within the connected tube segments; wherein the system further comprises a plurality of expansion joints connecting the tube segments; wherein each expansion joint comprises a sleeve made of a flexible sheet material, the sleeve comprising an annular endless central part and two annular endless outer end parts; and wherein each outer end part of the expansion joint is arranged to extend coaxially with an adjacent tube segment and to surround and sealingly engage an outer end part of the adjacent tube segment.

Description

TECHNICAL FIELD

[0001] The present invention relates to a low-pressure tubular system, such as a vacuum tube train transportation system (such as a Hyperloop), comprising a plurality of mutually connected tube segments having a longitudinal axis, wherein each tube segment comprises a central part and two outer end parts, and wherein the tubular system is configured to maintain a low-pressure or near-vacuum environment within the connected tube segments. Such a system is for example disclosed in international patent application publication no. WO2017 / 155980A1 and WO2016 / 126505A1, which are incorporated herein by reference. BACKGROUND

[0002] In such a system, trains or other vehicles will travel at high speed through the near-vacuum tube segments, while the tube segments can experience movements caused by thermal expansion of the ground and / or the tube itself, or other movements caused by e.g. structural movements, settlement, dynamic loads, etc. Therefore, a flexible airtight joint between the tube segments is required, which is safe and robust, and which must for example be able to withstand high stresses caused by the vacuum inside the tube segments, and / or which must be able to withstand a certain degree of possible external impacts, for example caused by people. SUMMARY

[0003] Therefore, according to an embodiment, the system further comprises a plurality of expansion joints connecting the tube segments; wherein each expansion joint comprises a sleeve made of a flexible sheet material and comprising an annular endless central part and two annular endless outer end parts; wherein each outer end part of the expansion joint is arranged to extend coaxially with an adjacent tube segment and to surround and sealingly engage an outer end part of the adjacent tube segment. In this respect, annular must be understood to include any circumferentially closed shape, such as a circle, a rectangle or a polygon.

[0004] According to a further embodiment, each outer end part of the expansion joint is provided with an annular endless retainer cable fixed to the flexible sheet material and extending coaxially with the adjacent tube segment; wherein each outer end part of the tube segment is provided with an annular radially outwardly extending flange near the outer end of the tube segment, the flange having a radially outer surface, an axially inwardly facing surface extending on the side of the central part of the respective tube segment, and an axially outwardly facing surface extending on the side of the outer end of the respective tube segment; wherein the radially outer surface of the flange engages the radially inner surface of the respective outer end part of the expansion joint; wherein the inner diameter of each annular endless retainer cable is designed such that the respective outer end pair of flanges of the expansion joint exerts a force on the axially inwardly facing surface of the flange. Preferably, the inner diameter of each annular endless retainer cable is smaller than the outer diameter of the respective flange. Preferably, the retainer cable is made of steel, glass fiber reinforced plastic, or aramid.

[0005] According to a further embodiment, the central part of the sleeve of the expansion joint each has a substantially V-shaped or U-shaped cross-section as seen from the tangent direction, such that the central part has a diameter substantially smaller than the central parts of the two outer end parts.

[0006] According to another embodiment, the flexible sheet material of at least the central part of the sleeve of the expansion joint each has at least two separate layers, comprising: a first layer of gas-impermeable flexible material; a second layer of flexible material having a higher tensile strength in the axial direction of the tubular system than the first layer. Preferably, the flexible sheet material of at least the central part of the sleeve of the expansion joint each further has a third layer of flexible material having a higher cut resistance and / or a higher puncture resistance to impacts from external sharp objects than the first and second layers, wherein the third layer surrounds the first layer. Preferably, the third layer surrounds the second layer. Preferably, the second layer surrounds the first layer. Preferably, the second layer comprises at least two overlapping sub-layers of the same material. Preferably, the material of the first layer is rubber, preferably SBR, EPDM, NR or CR rubber. Preferably, the material of the second layer comprises aramid, carbon, nylon and / or polyester fibers. Preferably, the material of the third layer comprises aramid fibers, glass fibers, steel mesh, or steel fibers. Preferably, the tensile strength is measured by the ASTM D7003 standard method, the cut resistance is measured by the ASTM F1790 standard method, and / or the puncture resistance is measured by the ASTM D4833 standard method.

[0007] The pipe segments can be made of concrete or metal, e.g. steel, and can have a diameter of at least 2.5 m. BRIEF DESCRIPTION OF DRAWINGS

[0008] The application will now be further explained by means of preferred embodiments as shown in the drawings, in which:

[0009] Figure 1 is a side view of a system according to the application, shown in longitudinal cross-sectional parts;

[0010] Figure 2 is a detail of the system as shown in Figure 1 ; and

[0011] Figure 3 is a perspective view of a cross-section of an expansion joint used in the system of the application. DETAILED DESCRIPTION

[0012] Reference is made to Figure 1 , a (near) vacuum tube train transportation system 1, such as a Hyperloop, comprising a plurality of interconnected pipe segments 2 having a longitudinal axis 3. The pipe segments 2 can for example be made of steel or concrete and can have an inner diameter allowing a Hyperloop passenger train (not shown) to be driven through the system 1.

[0013] As indicated by the schematic installation symbols 4, 5, the pipe segments can be installed such that at one outer end (at installation symbol 4) they are fixed to the ground, but allowed to rotate, and at their other outer end, the sliding support (installation symbol 5) allows the pipe segment 2 to translate and rotate relative to the ground. Thus, thermal expansion of the pipe segment 2 and (small) ground movements can be accommodated by the system.

[0014] With reference to Figure 1 , Figure 2 and Figure 3 , the expansion and movement of the ends of the pipe segment 2 requires the outer end portions 21 of the pipe segment 2 to be connected to each other by a flexible expansion joint 6. The expansion joint 6 comprises a sleeve of flexible sheet material having a central portion 61 and outer end portions 62. The outer end portions 62 of the expansion joint 6 extend coaxially with the axis 3 of the adjacent pipe segment 2 and are sealingly engaged with the outer end portions 21.

[0015] The outer end portions 62 of the expansion joint 6 are provided with annular endless retainer cables 621 of steel which can or can not be fixed to the flexible sheet material and which extend coaxially with the axis 3 of the adjacent pipe segment 2. The outer end portions 21 of the pipe segment 2 are provided with a flange 211 and the radially outer surface of the flange 211 engages the radially inner surface of the outer end portions 62 of the expansion joint 6. The inner diameter of each annular endless retainer cable 621 is smaller than the outer diameter of the flange 211, such that the material of the outer end of the expansion joint 6 around the retainer cable 621 exerts a force on the axially inward facing surface 2111 of the flange 211, thereby preventing the expansion joint 6 from sliding towards the outer end portion 21 of the pipe segment 2. The outer end portions 21 of the pipe segment 2 and their flanges 211 have a smaller outer diameter than the central portion of the pipe segment 2, such that the outer diameter of the outer end portions 62 of the expansion joint 6 around the outer end portions 21 is still smaller than (or approximately equal to) the outer diameter of the pipe segment 2. However, the expansion joint 6 can also be positioned on the outer surface of the pipe segment 2 such that the expansion joint 6 is larger than the outer diameter of the pipe segment 2.

[0016] The flexible and movable central portion 61 of the expansion joint 6 has a generally V-shaped or U-shaped cross-section, which central portion 61 is subjected to forces caused by the pressure difference between the environment of the pipeline system and the low pressure or (near) vacuum inside the pipe segment 2. Thus, the central part of the central portion 61 has a much smaller diameter than the two outer end portions. As Figure 2 indicated, the inner diameter of the central part of the central portion 61 can be approximately the same as the inner diameter of the pipe segment 2, or even smaller than the inner diameter of the pipe segment 2, but preferably, the expansion joint 6 does not interfere with the inner envelope of the pipe.

[0017] As Figure 2 indicated, the inner diameter of the central part of the central portion 61 can be approximately the same as the inner diameter of the pipe segment 2, or even smaller than the inner diameter of the pipe segment 2, but preferably, the expansion joint 6 does not interfere with the inner envelope of the pipe. Figure 3As shown, the flexible sheet of the expansion joint 6 comprises several separate layers. A first layer 601 is made of a flexible rubber material, for example made of SBR, NR or CR (EPDM and NBR or other conventional elastomers), and is air impermeable. At the outer end portion 62, the first layer 601 is provided with a radially inward rib 6011 that can be compressed completely against the flange surface, thus providing an additional seal to prevent possible air leakage from the environment to the pipe system 1. Alternatively, the flange 211 can be provided with a matching groove 2111, as shown, which engages and is filled by the rib 6011.

[0018] A second layer 602 of reinforcement is composed of at least two superimposed sub-layers 602a, 602b, each made of a flexible material, for example a woven fabric of aramid, carbon, nylon and / or polyester fibers, which has a higher tensile strength in the axial direction of the tubular system than the first layer 601.

[0019] A third layer 603 of flexible material, for example a woven fabric of aramid fibers, at least surrounds the first layer 601 and the second layer 602 in the central portion 61 of the expansion joint 6 and has a higher cut resistance and a higher puncture resistance to impacts from sharp objects (for example knives) from the outside than the first layer 601 and the second layer 602.

[0020] The outer end of the second layer 602 is wrapped around the cable 621 so that the cable 621 holds said outer end, thus holding the entire sleeve firmly against the flange 211 of the pipe segment 2.

[0021] Another rubber layer 601a, continuous with the first layer 601, surrounds the previous layers 602, 603 so that these layers 602, 603 and the cable 621 are enclosed in rubber and isolated from the environment. The outer rubber layer 601a can be vulcanized / adhered to the third layer 603 by means of an intermediate layer 604.

[0022] Accordingly, the present application has been described by preferred embodiments. It is understood, however, that the disclosure is merely illustrative. Various details of the structures and functions have been presented for purposes of illustration, but changes can be made in full scope of the terms expressed in the language of the appended claims which are to be interpreted in their broadest reasonable manner, and the specification and drawings are to be used to explain the claims. The claims are not to be construed as limiting the scope of the application as it is to be understood that the scope of the application is to be interpreted only as limited by the language of the claims, the specification and drawings being for explanation only. For the purpose of determining the scope of the claims the disclosure should be properly construed to read into the claims any element not specifically stated in the claims which is equivalent in scope to an element specifically stated in the claims. An element is equivalent in scope to another if it performs substantially the same function in substantially the same way to achieve substantially the same results as the element specified in the claims.

Claims

1. A low-pressure tubular system, comprising: a plurality of mutually connected pipe sections having a longitudinal axis; wherein each of the pipe sections comprises a central portion and two outer end portions; wherein the tubular system is configured to maintain a low-pressure environment within the connected pipe sections; wherein the tubular system further comprises a plurality of expansion joints connecting the pipe sections; wherein each of the expansion joints comprises a sleeve made of a flexible sheet material and comprising an annular endless central portion and two annular endless outer end portions; wherein each outer end portion of the expansion joint is arranged to extend coaxially with an adjacent pipe section and to surround and sealingly engage an outer end portion of the adjacent pipe section, wherein the flexible sheet material of at least the central portion of the sleeve of the expansion joint has at least three separate layers, the at least three separate layers comprising: a first layer of a gas-impermeable flexible material; a second layer of a flexible material having a higher tensile strength in the axial direction of the tubular system than the first layer; and a third layer of a flexible material having a higher cut resistance and / or a higher puncture resistance to impacts from external sharp objects than the first and second layers, wherein the third layer surrounds the first and second layers and the second layer surrounds the first layer.

2. The system of claim 1, wherein, each of the outer end portions of the expansion joint is provided with an annular endless retainer cable fixed to the flexible sheet material and extending coaxially with an adjacent pipe section; wherein each of the outer end portions of the pipe sections is provided with an annular radially outwardly extending flange near the outer end of the pipe section, the flange having a radially outer surface, an axially inwardly facing surface extending on the side of the central portion of the respective pipe section, and an axially outwardly facing surface extending on the side of the outer end of the respective pipe section; wherein the radially outer surface of the flange engages a radially inner surface of the respective outer end portion of the expansion joint; and wherein the inner diameter of each of the annular endless retainer cables is designed such that the respective outer end portion of the expansion joint exerts a force on the axially inwardly facing surface of the flange.

3. The system of claim 2, wherein, The inner diameter of each of the annular endless retainer cables is smaller than the outer diameter of the respective flange.

4. The system of claim 2, wherein, The retainer cable is made of steel, glass fiber reinforced plastic, or aramid.

5. The system of claim 1, wherein, The central portion of the sleeve of the expansion joint has a generally V-shaped or U-shaped cross-section as seen from the tangential direction, such that the central portion has a diameter that is substantially smaller than the central portions of the two outer end portions.

6. The system of claim 1, wherein, The second layer consists of at least two overlapping sub-layers of the same material.

7. The system of claim 1, wherein, The material of the first layer is rubber.

8. The system of claim 7, wherein, The material of the first layer is SBR, EPDM, NR, or CR rubber.

9. The system of claim 1, wherein, The material of the second layer comprises aramid, carbon, nylon, and / or polyester fibers.

10. The system of claim 1, wherein, The material of the third layer comprises aramid fibers, glass fibers, steel mesh, or steel fibers.

11. The system of claim 1, wherein, The tensile strength is measured by the standard method ASTM D7003, wherein the cut resistance is measured by the standard method ASTM F1790, and / or wherein the puncture resistance is measured by the standard method ASTM D4833.

12. The system of any one of claims 1 to 11, wherein, The pipe sections are made of concrete or metal.

13. The system as recited in claim 12, wherein, The low-pressure tubular system is a vacuum tube train transportation system.

14. The system of any one of claims 1 to 11, wherein, The low-pressure tubular system is a vacuum tube train transportation system. The low-pressure tubular system is a vacuum tube train transportation system.

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