EXPANSION JOINT

Abstract

An expansion joint for flexibly joining two tube segments for producing a tube for an evacuated tube transport system (ETT), wherein the expansion joint includes two annular rims and an annular flexible and airtight sleeve for rendering the expansion joint airtight wherein the sleeve includes two annular bead sections connected by an annular flexible carcass wherein each annular bead section includes a bead wire, and wherein the bead sections are designed to airtightly co-operate with rims that are fixed to the outside perimeter of each of the tube segments, wherein the rims are fixed at, or close to the opening of the tube segments.

Claims

1. An expansion joint for flexibly joining two tube segments for producing a tube for an evacuated tube transport system (ETT), wherein the expansion joint comprises two annular rims and an annular flexible and airtight sleeve for rendering the expansion joint airtight wherein the sleeve comprises two annular bead sections connected by an annular flexible carcass wherein each annular bead section comprises a bead wire, and wherein the bead sections are designed to airtightly co-operate with the rims that are fixed to the outside perimeter of each of the tube segments, wherein the rims are preferably fixed at, or close to the opening of the tube segments.

2. The expansion joint according to claim 1, wherein the flexible carcass comprises rubber.

3. The expansion joint according to claim 1, wherein the flexible carcass is reinforced with fibres or cords, such as steel cords, polyester cords or aramid cords.

4. The expansion joint according to claim 1, wherein the bead wire is a steel wire, or cords produced from aromatic polyamide fibres such as aramid fibres.

5. The expansion joint according to claim 1, wherein the outer surface of the expansion joint is provided with an UV-protective coating.

6. The expansion joint according to claim 1, wherein the inner annular circumference of the bead section is smaller than the outer annular circumference of the corresponding rim hump on the tube segment.

7. The expansion joint according to claim 1, wherein the rim is provided with a rim profile comprising a rim top a rim bead for receiving the bead section of the sleeve, and optionally a rim bead hump.

8. A method for producing a tube for a evacuated tube transport system (ETT) comprising expansion joints according to claim 1 and prefabricated tube segments, wherein the tube segments are provided with the annular rims which are provided with a rim profile on the outside perimeter of the tube segments, and wherein the rim profile is designed to cooperate with the bead sections of the sleeve, the method comprising the steps of positioning two tube segments with the open ends of the segments facing each other with a gap between the tube segments; optionally applying a bead lubricant and/or a sealant on the rims of the adjoining tube segments; slide the bead sections of the sleeve over the rims of the tube segments, thereby flexibly connecting the tube segments; lower the internal pressure in the tube to the operating pressure of an ETT-system, thereby sucking the flexible carcass of the sleeve inwardly between the gap between two adjoining tube segments and allow the bead sections to become seated in the respective rims provided on the tube segments and thereby providing an airtight seal.

9. The method according to claim 8, wherein the pressure inside the tube for the evacuated tube transport system is less than 0.1 bar.

10. A method of using the expansion joint according to claim 1 in the production of a tube segment for an evacuated tube transport system (ETT) using tube segments, comprising providing the expansion joint and tube segments, wherein the tube segments are provided on the outside perimeter with the rims provided with the rim profiles airtightly co-operating with the bead sections of the sleeves.

11. The method according to claim 9 wherein, when the internal pressure in the tube segment is at the operating pressure of the ETT-system, the flexible carcass is sucked inwardly between two adjoining tube segments due to the pressure difference between outside the tube (Pout) and inside the tube (Pin), and wherein the carcass is loaded in tension as a result of said pressure difference, and wherein the bead sections become seated in the rims provided on the outside perimeter of the tube segments due to said tension.

12. The method according to claim 10 to produce a tube segment for an evacuated tube transport system (ETT) wherein the rims on the outside perimeter of the open ends of the tube segments are provided by means of welding a metal annular rim to the outer perimeter, and wherein the metal rim is provided with the rim profile.

13. The method according to claim 9, wherein the rim is a solid metal rim provided with the rim profile, or wherein the rim is a metal strip which is formed, e.g. by roll-forming, into a rim profile.

14. The method according to claim 9, wherein the height of the rim bead hump h1 is larger than the height h3 of the lowest point of the rim bead to prevent the bead sections of the expansion joint to move out of the rim beads if Pin equals Pout.

15. The method according to claim 9, wherein one end of each tube segment is fixedly connected to a support structure, e.g. a pylon or a foundation, and wherein the other end of the tube segment is movably connected to a support structure to allow the tube segment to expand, contract and bend, and wherein the flexible carcass of the expansion joint between two subsequent tube segments absorbs the dimensional changes of the contracting, expanding or bending tube segment.

16. The method according to claim 9, wherein a sealant is provided between the rim profile of the tube segment and the bead section of the sleeve to further improve the airtightness, and/or wherein a bead lubricant is provided between the rim profile of the tube segment and the bead section of the sleeve to facilitate the sliding of the bead section over the rim top of the corresponding rim on the tube segment and/or to facilitate the sliding of the bead section into the rim bead.

17. The method according claim 10, wherein the pressure inside the tube for the evacuated tube transport system is less than 0.1 bar.

18. The expansion joint according to claim 1, wherein the flexible carcass comprises a synthetic rubber such as butyl rubber or a mixture of rubber composites.

19. The expansion joint according to claim 1, wherein both the flexible carcass and the bead sections comprises rubber.

20. The expansion joint according to claim 1, wherein both the flexible carcass and the bead sections comprises a synthetic rubber such as butyl rubber or a mixture of rubber composites.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The invention will now be explained by means of the following, non-limiting figures.

[0051] FIG. 1 shows a schematic drawing of an ETT-tube consisting of three tube segments 1 and two expansion joints 2. The ETT-tube is mounted on foundations 3.

[0052] FIG. 2 shows an enlarged section of the part in the circle of FIG. 1. The two adjoining ends of the consecutive tube segments 1 are shown as well as the expansion joint 2 in between the two adjoining tube segments. The foundation 3 is the support on which the mounting 4 to fixedly mount the left-hand tube segment to the foundation 3 is positioned, as well as the flexible mounts to dynamically mount the right-hand tube segment. The flexible mounts are, in this non-limiting embodiment, formed by a pair of supports 7 for vertical alignment, one on either side of the tube segment (the foot of the other one is just visible below the tube segment), and a support 10 for horizontal alignment. The spring blades 6 and 8 in the vertical supports, and 9 in the horizontal support eliminate vibrations (e.g. when a pod passes in the tube) and allow for slow movement due to expansion, contraction and geological movement. Support 7 consist out of a rod with at one end right-handed thread and at the other end left-handed thread. By turning support 7 the height can be adjusted.

[0053] FIG. 3 shows a side view and FIG. 4 an orthogonal view, which clearly shows the horizontal support 10 and the two vertical supports 7. FIG. 4 also shows that the pressure in the tube (P.sub.in) is much smaller in use than the pressure outside the tube (P.sub.out), the latter being atmospheric pressure, and the former being the operating pressure of the ETT-system. It will be clear that during construction, when the inside is still open to the atmospheric conditions, that the pressure in the tube segment equals the outside pressure.

[0054] FIG. 5 shows a cross section of the annular expansion joint 2 according to the invention and the two ends of the tube segments 1, each provided with a rim 15. The expansion joint comprises two bead sections 11, with a bead wire 12 in each bead section. The bead wire in the bead section is an annular member or hoop and has the function of locating and anchoring the bead section into the rim bead. The bead wire is a continuous and uninterrupted annular member, i.e. a closed hoop or coil, such as the bead wire in a tyre.

[0055] The flexible carcass 13 connects the two bead sections. The rims, in this example, consist of a weldable and roll-formed annular profile that is welded to the end of the tube segments. The welds are indicated with w. The rim may also be a solid material, but this makes the rim heavier, more expensive, and more difficult to handle. FIG. 8 shows that if there is a rim bead hump 18 the circumference of the rim bead 17 (h3) is smaller than the circumference of the highest point of the rim bead hump (h1, in short: the hump) around the tube segment over which the bead section must be slid. The height h2 must be determined such that when the pressure differential P.sub.out−P.sub.in is maximal (i.e. about 1 bar), that the force exerted on the bead section by the inward pull of the flexible carcass never exceeds the force needed to pull the bead section over the rim, which would break the airtight seal and lead to failure of the expansion joint. The height h2 is a function of parameters such as the elasticity and strength of the wire cord, the elasticity and strength of the bead section as a whole, the friction between the sleeve and the rim and the pressure differential (which never surpasses about 1 bar). The height h2 is a compromise between the ease of mounting the sleeve over the rim top and the prevention of sucking the bead section over the rim top when the expansion joint is in use.

[0056] FIG. 6 shows a schematic view of the expansion joint mounted on a solid rim 13, and it also shows the curvature of the expansion joint as it surrounds the tube segments. FIG. 7 shows a similar view, but with the hollow rim 13 of FIG. 5.

[0057] FIG. 8 shows a cross section of the rim and an indication of the different relevant heights h1 to h4 in the presence of rim bead hump 18. The rim top 16, rim bead 17 and rim bead hump 18 are indicated, and the shape of the rim profile has a thick and rounded L-shape comprising a rim top (16) on the top of the upstanding leg of the L, a rim bead (17) for receiving the bead section of the sleeve in the corner of the L and optionally a rim bead hump (18) at the end of the horizontal leg of the L. The height of the rim bead hump as measured from the bottom surface of the L, which is the surface that will be connected to the tube segment, is defined as h1. The lowest point of the rim bead is defined as h3. The height difference between the rim bead and the rim top is defined as h2. The rim profile must have a minimal height h3 to allow the installation of the sleeve on the rim. If h3 is too low, then there is insufficient slack in the bead section to mount the sleeve onto the rims (see FIG. 9 and the accompanying description). If h3 is too high, then it will be very difficult to slide the bead section into the rim bead during installation of the sleeve. It is noted that in the absence of a rim bead hump h3=h1, and h4-h1=h2.

[0058] FIG. 9 shows a sequence of 6 steps by means of which the sleeve can be installed on the rims. It should be noted that the bead wires in the bead sections of the sleeves have a high Youngs' modulus, so these must be considered for the purpose of installing the sleeve as being practically inelastic. The bead wires are also continuous and uninterrupted and the wires cannot be opened during installation of the sleeve and closed afterwards. By using the sequence in FIG. 9 it is possible to install the sleeve despite the inelasticity of the bead wires and despite the fact that the bead wires are continuous and uninterrupted.

[0059] FIG. 9a shows that the sleeve is inserted in the gap between the two adjoining tube segments, each provided with an annular rim with a rim profile such as the one depicted in FIG. 8. FIG. 9b shows the first step which is to position the top right bead section on the tube segment against the rim. The length of the bead wire is such that this will (just) allow to lift the bead section on the opposite side (bottom right) over the rim top and seat the bead section in the rim bead as indicated by the arrow. This step shows the importance of the correct height of h3. If h3 is too low, then the bead section cannot be slid over the rim top on the opposite side. If h3 is too high, then the seating of the bead section in the rim bead will become very difficult. The left-hand side of the sleeve can be lifted over the rim and positioned on the tube segment against the rim as indicated by the arrow. FIG. 9c shows that the length of the bead wire is such that this will (just) allow to lift the bead section on the opposite side (top left) over the rim and seat the bead section in the left-hand rim bead as indicated by the arrow. The bead section on the right-hand side can now be seated in the rim bead, which results in the right-hand bead section to be seated in the rim bead along the entire circumference of the rim. In the presence of a rim bead hump, the last portion of the bead section may need some persuasion to be slid over the hump. FIG. 9d completes the installation by sliding the left-hand bead section in the rim bead, thereby seating the left-hand bead section in the rim bead along the entire circumference of the rim. In the presence of a rim bead hump, the last portion of the bead section may need some persuasion to be slid over the hump. FIG. 9e shows the result. It should be noted that these figures show a 2-D representation, but that the sleeve and the rim are annular in shape, just like a bicycle wheel rim and a bicycle tire. The dashed lines connecting the left-hand bead sections and the right-hand bead sections illustrate the 3-D character of the sleeve. In FIGS. 9a-9e the pressure inside the tube equals the outside pressure. FIG. 9f shows the expansion joint in its full glory, and in use, where the flexible carcass is sucked inwardly by the pressure differential (P.sub.in<<P.sub.out), providing an airtight seal and a flexibility to expand, contract, bend and rotate.

[0060] It should be noted that this sequence is a non-limiting example, and there may be other sequences to achieve the result of FIG. 9f.