TUBULAR MAST ASSEMBLY, RELATED KIT, AND METHODS
20200011083 ยท 2020-01-09
Inventors
Cpc classification
E04H12/342
FIXED CONSTRUCTIONS
International classification
Abstract
A connector element for a tubular mast assembly, a tubular mast assembly and a kit therefore, methods of assembling and disassembling, a guide device and a spreader are provided. In an aspect, a tubular mast assembly comprises first and second members each comprising a shell resiliently biased in the form of an elongate tube having longitudinal edges defining a slit along its length. A connector element comprising a first socket receives an end of the first member and a second socket receives an end of the second member so as to connect the first and second members into an extended tubular form. Each member can be disconnected from its socket and its shell opened out at the slit to assume a flattened form in which it can be wound into a coiled form for stowing the assembly.
Claims
1. A tubular mast assembly comprising: first and second members each comprising a shell resiliently biased in a form of an elongate tube having longitudinal edges defining a slit along its length; and, a connector element comprising a first socket which receives an end of the first member and a second socket which receives an end of the second member so as to connect the first and second members into an extended tubular form, wherein each member can be disconnected from its socket and is constructed and arranged such that the shell can be opened out at the slit to assume a flattened form in which it can be wound about an axis extending transversely to its longitudinal direction to assume a coiled form for stowing the tubular mast assembly.
2. The tubular mast assembly of claim 1, wherein each member exhibits bi-stability in its coiled and extended forms.
3. The tubular mast assembly of claim 1, comprising a second connector element comprising a first socket and a second socket, wherein the first socket of the second connector element receives an end of the first member that is opposed to the end of the first member that is received in the first connector element, and wherein the second socket of the second connector element is adapted to provide a first foot element at an end of the second connector element for supporting the tubular mast assembly on an object or on the ground.
4. The tubular mast assembly of claim 3, wherein the second socket of the first connector element further has a second foot element, such that the first connector element and second connector element are interchangeable in the tubular mast assembly in that they are both able to provide a foot element to support the tubular mast assembly and both able to connect the first and second members.
5. The tubular mast assembly of claim 4, wherein the first sockets of the first and second connector elements further provide respective third foot elements.
6. The tubular mast assembly of claim 3, wherein the first foot element comprises a ring shape, castellated surface surrounding the second socket for gripping an object or surface.
7. The tubular mast assembly of claim 3, wherein the first foot element comprises a rubber or high friction material surrounding the second socket for gripping an object or surface and/or for gripping a member inserted in the second socket.
8. The tubular mast assembly of claim 1, wherein at least one member is biased in the form of a tube having an external diameter larger than an internal diameter of the corresponding socket in which it is received, wherein when received in the corresponding socket, the tube is compressed against the bias of the tube to fit in the socket.
9. The tubular mast assembly of claim 1, wherein the connector element has projecting features inside each socket for guiding at least one edge portion of its member when it is inserted into the corresponding socket, and/or for interacting with the edge portion when fully inserted into the corresponding socket to help retain its member in place.
10. The tubular mast assembly of claim 1, wherein the connector element comprising a tubular sleeve and at least one stop element fixed within the tubular sleeve, wherein one or both sockets are defined by an open end of the tubular sleeve and the stop element such that a leading edge of the corresponding member when fully inserted into the or each socket abuts the at least one stop element.
11. The tubular mast assembly of claim 10, wherein the tubular sleeve is corrugated in profile, wherein the stop element is engaged with corrugations in the tubular sleeve.
12. The tubular mast assembly of claim 10, wherein the stop element is fixed by at least one fastener that passes through a hole in the tubular sleeve and clips to the stop element.
13. The tubular mast assembly of claim 10, wherein the tubular sleeve comprises a plastics material, and at least one member has a foot element comprising plastics material, wherein the foot element is adhered or welded to the tubular sleeve.
14. The tubular mast assembly of claim 1, wherein the tubular mast assembly comprises three or more members joined by connector elements.
15. The tubular mast assembly of claim 1, comprising a support element fixed to a free end of one of the members that is not inserted into one of sockets of a connector element, the support element being adapted to support a load.
16. The tubular mast assembly of claim 15, wherein the support element comprises a third socket for receiving the free end of one of the members.
17. The tubular mast assembly of claim 15, wherein the support element comprises fixtures for attaching tethers to tether the tubular mast assembly in a deployed position.
18. The tubular mast assembly of claim 15, comprising a flexible sheet or netting supported by the tubular mast assembly, wherein the support element is a spreader element comprising a surface having an increased cross sectional area relative to the members and gripping elements or surface treatment for gripping the flexible sheet or netting.
19. The tubular mast assembly of claim 18, wherein the gripping elements comprise a plurality of blunt cylindrical studs extending from the surface of the spreader element.
20. The tubular mast assembly of claim 1, wherein the members are reversibly received in the sockets permitting disassembly of the tubular mast assembly by withdrawing the members from the sockets.
21. A tubular mast assembly in a kit form, the kit comprising: first and second members each comprising a shell in a coiled form in which the shell has a flattened form and is wound about an axis, wherein each shell is configurable between its coiled form and an extended form in which it is resiliently biased in a form of an elongate tube extending transversely to the axis having longitudinal edges defining a slit along its length; and, a connector element comprising a first socket for receiving an end of the first member and a second socket for receiving an end of the second member, so as to connect the first and second members into the tubular mast assembly.
22. The tubular mast assembly in the kit form of claim 21, further comprising a guide device, the guide device comprising: a base; a concave portion conforming generally to a curved surface of a coiled portion of the first or second member, wherein the concave portion has a low friction surface such that with the first or second member being in a partially extended state, having a coiled portion and an extended portion, with the coiled portion received in the concave portion of the guide device, a force applied on the extended portion towards the concave portion causes the coiled portion to rotate against the low friction surface thereby progressively adding the extended portion to the coiled portion.
23. The tubular mast assembly in the kit form of claim 21, comprising a container in which the kit form is stowed, wherein at least one part of the kit form at least partly occupies a space defined inside an interior coil of at least one member.
24. A connector element, comprising: a body comprising first and second sockets constructed and arranged to receive tubular elements so as to connect together the tubular elements into the tubular mast assembly, wherein at least the first socket is additionally constructed and arranged as a foot element adapted to interface to the ground or another object on which the tubular mast assembly is to be supported, such that where the second socket receives a tubular element and the first socket does not, the foot element is accessible at an end of the tubular mast assembly to provide support to the tubular mast assembly, such that where a plurality of connector elements are supplied in a kit, the connector elements is selectively used to connect together tubular elements and to act as the foot element.
25. A connector element according to claim 24, wherein the foot element comprises one or more of: a ring shape encircling the first socket; projections or an uneven surface arranged to provide increased traction on the ground or the another object; a fastener for attaching the foot element to an object or surface; and a rubberized or high grip surface for providing traction on the ground or another object, wherein the rubberized or high grip surface optionally extends to an inner surface of the first socket to help secure a tubular element inserted into the first socket.
26. A spreader for supporting a flexible sheet or net, comprising: a socket for receiving an end of a tubular member; the spreader having a greater surface area than that of the end of the tubular member; and, a plurality of blunt, cylindrical studs on a surface of the spreader.
27. A guide device, comprising: a base; a concave portion conforming to a curved surface of a coiled portion of the first or second member, wherein the concave portion has a low friction surface such that with the first or second member being in a partially extended state, having the coiled portion and an extended portion, with the coiled portion received in the concave portion of the guide device, a force applied on the extended portion towards the concave portion causes the coiled portion to rotate against the low friction surface thereby progressively adding the extended portion to the coiled portion.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0064] Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which:
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DETAILED DESCRIPTION
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[0082] The shell 21 is generally thin to aid coiling, e.g. typically between 0.5 mm and 5 mm for most applications. Such members are sometimes referred to as STEMs (Slit Tubular Extendable Members).
[0083] Typical lengths of the extended members 20 may be between 1 m and 5 m and typical diameters may be between 5 cm and 15 cm. It will be appreciated that in principle almost any length and diameter can be used according to the application.
[0084] In the present example, the shell 21 may be formed from a thermoplastic matrix with fiber reinforcements, such as a fiber reinforced polymer (FRP hereafter). The fibers may be glass, carbon, or aramid, while the polymer may be polypropylene, polyethylene, a polyamide, polyester thermoplastic, poly-ether-ether-ketone or any other polymer suited to the particular requirements of the task at hand. The composite material may comprise a single layer or plural layers with fibers oriented in different directions in each lamina. The use of fibrous materials mechanically enhances the strength and elasticity of the plastic matrix. The extent that strength and elasticity are enhanced in a fiber reinforced plastic depends on the mechanical properties of both the fiber and the matrix, their volume relative to one another, and the fiber length and orientation within the matrix. FRPs are widely used in many areas such as aerospace and automotive industries, and are not described in detail herein.
[0085] In the present example, the member 20 is a bistable reelable composite (BRC). Such a bistable member has a first stable state in the coiled form 22, where the cross section of the member 20 is generally flat and a second stable state in the extended form 23, where the cross section of the member is curved as previously described. The bistable member 20 may be capable of reversible configuration between its coiled and extended forms a plurality of times. Suitable structures are disclosed in the following international patent applications, each of which is incorporated here by reference: WO88/08620A1, WO97/35706A1, WO99/62811A1, WO99/62812A1 and WO2012/168741A1. Such bistable structures are available from RolaTube Technology Limited of Lymington, the United Kingdom.
[0086] In general, there are two ways to make a tube bistable: either by altering the bending stiffness of the structure so that it is no longer isotropic, for instance by using a fiber-reinforced composite, or by setting up an initial prestress in the structure. The BRC in the present example uses the first technique. This involves arranging the fibers to increase the torsional stiffness, and increase the coupling between bending in the longitudinal and transverse directions.
[0087] Normally when something is bent the amount of energy stored by that bending (the total strain energy) rises as the degree of bending increases. In BRCs, once the initial curvature is straightened as the tube is opened, the stiffness along the longitudinal axis drops and the forces acting on the material of the tube arising by the deformed surface layer fibers can act to flip it into the coiled form. As this second curvature forms, the total strain energy drops, thereby forming a second stable form, or more stable form, for this section.
[0088] These principles operate in reverse when moving from the coiled state to the extended state.
[0089] Thus, structural members are formed that exhibit a stable geometry in both the extended and coiled states. These manage the problems of difficult handling and complicated mechanisms by forming STEM type structures from materials that have been engineered so as to make them easy to coil and handle.
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[0091] The inside diameter of the socket 41 is preferably slightly less than the unconstrained diameter of the extended tube, for instance, the tube diameter may be 0.5% to 5% greater than the socket diameter. Thus, to insert the member 20 into the socket, the member 20 is first uncoiled to its slit tubular form and then the end of the member is compressed by the user to reduce its diameter against the residual bias of the member. The end of the member 20 can then easily be inserted into the socket 41. Once fully inserted up against the stop element 48, the pressure can be released and the tube will expand outwardly due to the resilient bias against such that friction helps hold it in place against the interior surface of the socket. The member 20 can be removed from the socket 41 using the reverse technique of compressing the end of the member. The socket 41 may be arranged such that the member 20 can be introduced in any circumferential orientation. The slit tube member 20 may subtend an angle of slightly less than 360 degrees (e.g. between 340 and 358 degrees) to leave a gap 27 to aid compression. In other examples, the member 20 may subtend an angle of over 360 degrees (e.g. between 362 and 450 degrees) to create overlapping edges 26 to aid compression. Nonetheless, members with edges 27 that meet will also work.
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[0093] The rubber portion 50 also extends onto the inner surface 55 of the ring shaped body 48 to help grip the member 20 inserted into the socket 41. The plastics body has a groove 57 adapted to receive the end of the sleeve 42 and may be keyed to the corrugations in the sleeve. The foot element 44 may be glued or welded into position on the sleeve end, or by using mechanical fasteners.
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[0095] The fastener 46 comprises a plastics body having a head 70 portion and two reliantly biased legs 72 extending from the head portion 70, each having a lug 74 on the end opposite the head portion 70.
[0096] To manufacture the connector element 40, the stop element 46 is introduced into the sleeve 42 until holes 64 in the body 60 align with the holes 47 in the sleeve 45. The fasteners 46 are inserted through the holes 47 from the outside of the sleeve 45. The resilient legs 72 are compressed together allowing the protruding lugs to pass through the hole, aided by the leading edge of the lugs being tapered. When the fastener is fully inserted, the head 70 lies against the surface of the sleeve 42 within a corrugation preventing further ingress, and the lugs latch with the far lip 66 of the hole 64 or a lip provided by a suitable recess in the hole, thus securing the stop element 45 in place in the sleeve 41. The foot elements 44 are then attached to the ends of the sleeve by gluing or welding them in place.
[0097] It will be appreciated that other construction techniques can be used. For instance, other mechanical fasteners, i.e. a threaded fastener or rivet, or glue could be used to attach the stop element 46 to the sleeve 42 or the foot elements 44 to the sleeve 42.
[0098] The connector elements 40 are preferably symmetric in function such that each end can be used as a socket 41 for receiving a member 20 or as a foot 44 to support the assembly 11. The connector elements 40 thus have dual functionality in that they can be used interchangeably as a foot, or to connect together extendible members 20. This increases the versatility of the kit, in that different configurations can be made. For instance, six members 20 and six connector elements 40 can be configured as two 3-length mast assemblies 11 or as three 2-length mast assemblies 11. Compared with a kit, where different elements are used as the connectors and the feet, to allow both mast configurations would require three feet and four connector elements, i.e. seven elements, compared with the six dual function elements 40 in the present example. This saves weight and space. Furthermore, the person assembling the kit 10 does not need to identify about which item is which, or which end to connect to the tubular members. Similarly, the members 20 are functionally symmetric, meaning that the person assembling the kit 10 does not have to identify which end is which. The dual function of the connector elements 40 also simplifies manufacture, in that fewer molds, tooling, etc., are needed.
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[0100] The upper surface 81 of the body has a plurality of blunt molded studs 86 extending from the surface. In the present example, the upper part has cut-outs 84 to save weight. Thus, the body forms a hub portion 87 with a first group of plural studs and a rim portion 88 with a further group of studs connected to the hub by spokes 89. The studs 86 may be arranged in a triangular pattern relative to neighboring studs with further cut-outs between the studs 86.
[0101] The studs 86 are preferably generally cylindrical or frustroconical with little or no taper (e.g. less than 10 degrees side slope to the direction of the stud 86). The end of the studs 86 are at least 1 mm wide and may be between 2 mm and 5 mm and be raised from the surface by between 4 mm and 10 mm in typical applications. The majority of studs 86 in any grouping of studs, i.e. on the rim 88 or on the hub 87, may be separated from its neighboring studs 86 by at least 10 mm and in some cases 20 mm or more. Thus, relatively blunt, well separated studs 86 are provided. It has been found that this arrangement is particularly useful with supporting new lightweight, high-tech, nets, which are designed to defeat a large range of sensors, e.g. radar, rather than just providing visual cover or camouflage. This has been found to support nets and other mesh fabrics with lower risk of damage to the materials and their coating compared with comparative net supports, which typically use a plurality of closely spaced, pointed pegs. These bristle type peg features on the upper surface engage with and prevent slippage of the nets, but are prone to cause damage to the materials and their coatings. Existing designs use pointed, raised features that are easy to throw a net over and then position and re-position, as the net does not need to be raised significantly to adjust it. The introduction of nets that are both lighter and coated in various anti-detection agents has shown that continuing this type of design damages the coatings and can damage the nets themselves. By replacing the raised pointed features with a solid stud of higher relief and without sharp features prevents such damage by providing a solid location point
[0102] In other examples, different support members 80 can be provided to support different types of loads.
[0103] The mast assembly 11 may additionally comprise a hook, clamp or other fixing means to allow further objects to be supported by the mast assembly. These might be provided by a support element 80 or a connector element 40 or a separate member included in the kit 10 which connects to an extended member 20 in place of the support member 80. For instance, a light may be supported by a mast assembly 11 by replacing the spreader element 80 with a support element adapted to supporting a light, or clamped in place by a spreader element 80 or connector element 40 with an additional light mounting fixture, or directly incorporated into those elements to provide illumination under a canopy or the like supported by the mast assembly 11.
[0104] A kit 10 for a tubular mast assembly 11 may comprise:
[0105] 4 approx. 2.6 m (8 feet) long BRC tubes 20
[0106] 4 approx. 1.3 m (4 feet) long BRC tubes 20
[0107] 6 Support elements 80
[0108] 8 Connector elements 40
[0109] 24 Ground Stakes
[0110] 1 Bag or case 100
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[0112] At least one part of the kit 10 may pack at least partially inside the space defined by the inner coil of a coiled member 20. The coil can naturally have an inner diameter large enough to accommodate the inner part. Alternatively, the inner part may act as a bobbin on which the outer coil can be wound, and so hold the outer open to the necessary extent.
[0113] For instance, at least one connector element 40 may be positioned within the interior coil of at least one coiled member 20. It is expected that a convenient length for the connector element 40 will be approximately twice the width of the coiled member 20, meaning that the connector element 20 can be packed within the interior space of two adjacent coiled members 20. Furthermore, one coil may be disposed within another coil. For example, one member 20 may form a tighter coil than another member 20 such that its outer diameter is less than the inner diameter of the other member 20. This might occur where members 20 of two different extended widths or lengths are provided. Alternatively or additionally, the outer coil can be wound on the inner coil which holds it open to the necessary extent. Thus, the less tightly coiled member 20 may accommodate the more tightly coiled member 20 within the space of its interior coil, which may in turn accommodate a connector element 40 within the space of its interior coil.
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[0115] Thus, a highly compact form of the kit 10 can be supplied, in this case achieving a packed volume of approx. 0.82 m cubed (2.9 feet cubed), i.e. approx. width=91 cmdepth=56 cmheight=16 cm (36 inch22 inch6.5 inch). These techniques can provide a packed volume of approximately 64% of current modular pole systems comprising aluminum based pole segments. It is expected that, were the packed volume is an important consideration, even more compact packing can be achieved using these techniques. The use of plastics materials in the mast assembly can also result in significantly a lighter weight than equivalent systems, up to approximately 20% lighter than comparative systems.
[0116] The kit 10 is also simple to deploy and stow. The user can simply uncoil the coiled members 20 into extended tubular members 20. To insert the extended member 20 into a socket 41,82 of the connector element 40 or spreader 80, the user can squeeze the slit tube causing a reduction in its diameter at the slit, allowing it to be inserted into the socket of the member or spreader. The pressure can then be released, allowing the tube 20 to expand towards its normal diameter due to its internal bias, thus forming a tight fit on the interior of the socket, which may be rubberised to help grip the member 20. Thus, the masts 11 can be quickly and conveniently assembled without tools. The spreader 80 and or connector elements 40 may have a fixture for attaching tethers to stake the mast 11 to the ground or tie the mast 11 to some other feature.
[0117] To disassemble, the user would again compress the ends of the tubular members 20, which due to the slit would become loose in their sockets 41,82 so they can be removed and then coiled, allowing rapid, tool-less disassembly.
[0118] The kit may additionally include a guide device 200 as shown in
[0119] To use the device, the user first begins coiling the tubular member 20 at one end e.g. at least a half turn, or complete turn 22. As shown by
[0120] The surface of the concave portion 204 may be smooth and low friction to aid slip between the coil 22 and concave portion. As shown in
[0121] The curvature of the cylindrical section 204 is preferably approximately matches that of the coil 22. As the radius of curvature of the member increases with each coil that is added, the radius of curvature R of the cylinder may be selected to be in the range defined by the radius of curvature of the middle coil of the fully coiled member 25%, or in some examples 10%. Preferably the angle subtended by the cylinder section is at least 90 degrees, and in some examples may be between 120 degrees and 180 degrees to more fully support the coiled member 22 as it rotates. The sides of the cylinder are closed by walls 210 formed in the body 206 of the device, with the length L of the cylinder equal to or slightly larger than the width of the coiled member, to help keep the coil in position during coiling. Thus, the concave portion cradles the coil whilst permitting slip, allowing a downward force to quickly and simply coil the entire member.
[0122] As discussed above, the system is capable of faster deployment and recovery. Different combinations and numbers of elements may be provided in the kits according to the application and multipole kits can be used in combination to create even further flexibility and variety of support masts. The use of plastics materials for the connector elements 40, support element 80 and members 20 also has the advantage of lower thermal signature and lower microwave signature compared with standard solutions employing metals. Shaped rubber feet to allow grip on all terrain and on vehicle external surfaces. The mast is also safer to use, e.g. against static charge build up and/or lightning strike.
[0123] Embodiments of the present invention have been described with particular reference to the example illustrated. However, it will be appreciated that variations and modifications may be made to the examples described within the scope of the present invention.