CASWELL, Tommy (23 The Glade, Fetcham, Surrey KT22 9TW, GB)
| Claims 1. A tubular member adapted for use as a structural member, the tubular member being flexible when deflated and substantially inflexible when inflated, and including reinforcing textile strands helically laid between two layers formed from a material selected from rubber, substitutes therefor and plastics, the strands being laid at an angle to the axis of the tubular member of 30° or less. 2. A tubular member according to Claim 1, wherein the said material is PVC and the reinforcing strands are formed of a textile material, preferably nylon. 3. A tubular member according to Claim 1 or Claim 2, wherein the reinforcing strands are helically wound in opposing senses about the axis of the tubular member so as to cross. 4. A tubular member according to Claim 3, wherein the strands wound in opposing senses are interwoven resulting in a woven textile reinforcing structure. 5. A tubular member according to any preceding Claim, wherein the reinforcing strands are laid at an angle of between 10 and 15°. 6. A tubular member according to any preceding Claim, wherein there are second reinforcing strands laid at a different angle to the first mentioned strands. 7. A tubular member according to Claim 6, wherein the first reinforcing strands are laid at an angle of between 10 and 15° and the second reinforcing strands are laid at an angle of about 45°. 8. A tubular member according to Claims 6 or 7, wherein there are further reinforcing strands extending parallel to the axis of the tubular member. 9. A method of making a tubular member adapted for use as a structural member, the tubular member being flexible when deflated and substantially inflexible when inflated, the method including the steps of: forming a first layer from a material selected from rubber, substitutes therefor and plastics; forming a reinforcing layer over said first layer, said forming step comprising laying reinforcing strands over the first layer at an angle of 30° or less to the axis of the tubular member; forming a second layer of said material over the reinforcing layer; and softening the material of at least one of the first and second layers to unite the first and second layers through interstices between strands of the reinforcing layer. 10. A method according to Claim 9, wherein the said material is PVC and the reinforcing strands are formed of a textile material, preferably nylon. 11. A method according to Claim 9 or Claim 10, wherein the reinforcing strands are laid helically over the first layer in opposing senses about the axis of the first layer so as to cross. 12. A method according to Claim 11, wherein the strands laid in opposing senses are interwoven resulting in a woven structure. 13. A method according to any of Claims 9 to 12, wherein the reinforcing strands are laid at an angle of between 10 and 15°. 14. A method according to any of Claims 9 to 13, wherein the step of forming a reinforcing layer includes the step of laying second reinforcing strands at a different angle to the first mentioned reinforcing strands. 15. A method according to Claim 14, wherein the first reinforcing strands are laid at an angle of between 10 and 15° and the second reinforcing strands are laid at an angle of about 45°. 16. A method according to Claims 14 or 15, wherein the step of forming a reinforcing layer includes the step of laying further reinforcing strands extending parallel to the axis of the first layer. 17. A sports goal comprising a plurality of struts interconnected to form nodes with netting optionally attached thereto, the struts including at least: one or more struts defining a crossbar; two or more struts defining respective goal posts; a plurality of ground struts adapted to lie along the ground to define the bottoms of respective left and right sides and a rear of the goal; and bracing struts interconnecting ground struts with the nodes at which crossbar struts and goal post struts are connected to form a corner of the goal, each said strut comprising a tubular member according any of Claims 1 to 8, said tubular members being adapted to be pneumatically filled from a pneumatic pump via one or more valves provided in the tubular members or in means connecting respective struts at the nodes. |
Background
This disclosure relates to tubular members.
Tubular members are usually employed as tubes or pipes for conveying fluids along the length of the tube or pipe. Flexible tubes are commonly termed hoses and are used for conveying fluids or to give added protection to electrical wiring. Rigid tubular members are generally employed either as rigid pipework for conveying fluids or as structural components, serving, for example, as hollow columns.
In our co-pending British Patent Application No: 0501474.1 filed 24 th January 2005 (published as GB 2422322 A), we disclosed a sports goal comprising a plurality of struts interconnected to form nodes with netting optionally attached thereto. The struts comprise: one or more struts defining a crossbar; two or more struts defining respective goal posts; a plurality of ground struts adapted to lie along the ground to define the bottoms of respective left and right sides and a rear of the goal; and bracing struts interconnecting ground struts with the nodes at which crossbar struts and goal post struts are connected to form a corner of the goal. The struts are formed of a tubular material adapted to be pneumatically filled from a pneumatic pump via one or more valves provided in the struts or in means connecting respective struts at the nodes.
We also disclosed an alternative arrangement of a kit of parts for assembly into a demountable sports goal. The kit comprises a plurality of lengths of tubular material adapted to form struts and a plurality of connectors adapted to form nodes interconnecting struts to form a unitary structure comprising a crossbar, goal posts, ground struts defining the bottoms of respective left and right sides and a rear of a goal, and bracing structures interconnecting the ground struts with the corners of the goal defined between the goal posts and ends of the crossbar. The tubular material is capable of being pneumatically filled from a source of pneumatic pressure through one or more valves provided in the tubular material or in the connectors. Netting may be attached to the assembly of struts and connectors. In both cases, the structures necessarily included one or more bracing structures interconnecting ground struts defining the rear of the goal with the crossbar at one or more points intermediate the length of the crossbar. Without such intermediate bracing structures, it would not have been possible, at the date of the said Application, to provide a structure formed from tubular material as then commercially available that was capable of ready inflation to provide a full size Association Football goal without significant sagging or distortion of the crossbar, which would cause the goalposts no longer to be vertical. Optional additional support in the form of hard curved plastics shells fastened to the inflated struts by hook-and-loop fastener strips was suggested for the goalposts. This, together with the obligatory bracing structure, has the effect of helping to keep them straight.
The material suggested for forming the tubular struts was natural or synthetic rubber, or plastics substitutes, preferably reinforced with nylon thread. Commercial embodiments have since been produced and sold under our Registered Community Trademark igoal®, and are formed with a thickness in the material of the struts of around 2mm, and a diameter for the goalposts and cross-bar of 3 inches (7.62cm), and work well when inflated with an applied pressure of around lBar. The tubular members employ inner and outer layers of soft polyvinylchloride (PVC) with nylon threads between the two layers helically wound in opposing senses about the axis of the tube so as to cross, being laid typically with an angle to the axis of 80° or more. The two plastics layers are softened to fuse together in the interstices between the nylon threads. We have found that this structure prevents the tube from ballooning (expanding diametrically) in use. An additional layer of parallel threads preferably runs along the length of the tubular member to prevent stretching lengthwise in use.
In our co-pending British Patent Application No: 0800703.1 (not yet published at the date of filing of the present Application), we disclosed a further application for tubular members that are inflated to form a structure and deflatable to allow them to be packed away. In our said Application we disclosed equipment, which might be temporary traffic signs or signals, public address speakers at a country show or for a travelling circus, satellite dishes for military communication, emergency lighting for roadworks, or temporary floodlights for emergency workers at the site of an accident or for sporting fixtures played after dark or in poor lighting conditions, especially on public grounds, that is temporarily supported above the ground by a self-supporting, readily erectable and transportable mast. The mast comprises a pneumatically inflatable elongate tube having a first end to which the equipment is coupled and a second end coupled to a ground support tripod with extendable legs. The mast necessarily included bracing structure to brace the tube when inflated, the structure including respective flexible members extending from each tripod leg to the first end of the tube. Without such bracing structure, the flexibility of inflatable tubes formed from material commercially available at the date of filing the said Application would have resulted in the equipment being incapable of being safely held aloft on the mast. Even in a modest breeze, the equipment would wave about without a bracing structure.
In practice, the mast would be made from the same material as the aforementioned goalpost struts.
Plastics hosepipes for watering gardens are commonly provided with reinforcing strands incorporated into the plastics material and extending helically about the axis of the hose at an angle of 45° to that axis.
Summary of the Disclosure
In accordance with a first aspect of the present disclosure, a tubular member, flexible when deflated and substantially inflexible when inflated, and adapted for use as a structural member, includes reinforcing textile strands helically laid between two layers formed from a material selected from rubber, substitutes therefor and plastics, the strands being laid at an angle to the axis of the tubular member of 30° or less.
In a second and alternative aspect of the present disclosure, a tubular member that is flexible when deflated and substantially inflexible when inflated, and is adapted for use as a structural member, is made by a method including the steps of forming a first layer from a material selected from rubber, substitutes therefor and plastics; laying reinforcing strands over the first layer at an angle of 30° or less to the axis of the tubular member; forming a second layer of said material over the reinforcing strands; and softening the material of at least one of the first and second layers to unite the first and second layers through interstices between the strands. Preferred embodiments have one or more of the following features: The said material is PVC. The reinforcing strands are formed of a textile material, preferably nylon. The reinforcing strands are helically wound in opposing senses about the axis of the tubular member so as to cross. The reinforcing strands are laid at an angle of between 10 and 15°. The strands with opposing sense may be interwoven, thereby resulting in a woven textile reinforcing structure. There is a second layer of reinforcing strands laid at a different angle to the first. The first layer of reinforcing strands are laid at an angle of between 10 and 15° and the second layer of strands are laid at an angle of about 45°. There is a further layer of reinforcing strands extending parallel to the axis of the tubular member.
Brief Description of the Drawings
Preferred embodiments of tubular member are described below by way of example only with reference to the accompanying drawings, in which:-
Fig. 1 shows a somewhat schematic and incomplete side elevational view of a tubular member with reinforcing strands wound at 45°;
Fig. 2 shows a similar side elevational view of a tubular member with reinforcing strands wound at 10°;
Fig. 3 shows a similar side elevational view of a tubular member with reinforcing strands wound as in both Fig. 1 and Fig. 2;
Fig. 4 is perspective view of a length of the tubular member of Fig. 3 with the strands shown between two plastics layers, one shown partly cut away to show the strands;
Fig. 5 is a perspective view similar to Fig. 4 for a tubular member with a further layer of reinforcing strands parallel to the axis of the tubular member.
Description of Preferred Embodiments
In Fig. 1, a tubular member 1 comprises a layer 2 of plastics, suitably a relatively soft plastics material such as PVC, or rubber, overlaid with reinforcing strands 3. The strands 3 comprise a textile material, preferably nylon. In Fig. 1, the strands 3 are wound helically about layer 2 in opposing senses at an angle of 45° to the axis of the tubular member. The opposing sense strands may be interwoven, forming a woven textile reinforcing structure 4. However, this arrangement is not in accordance with the teachings of the present disclosure.
In contrast, in Fig. 2, similar reinforcing strands 5 are laid at an angle of 10°, again in opposing senses, the opposing sense strands being interwoven, thereby resulting in a woven textile reinforcing structure 6. Our experiments have shown that a tubular member as illustrated in Fig. 2 would be substantially more rigid when inflated to the same operating pressure than a structure as shown in Fig. 1, and that a significantly improved rigidity can already be detected at an angle reduced from the 45° angle of Fig. 1 to about 30°.
Fig. 3 and 4 show a preferred structure with two superposed reinforcing layers comprising the woven textile reinforcing structures 5 and 6.
It will be understood that in each of Figs. 1 to 4, the reinforcing structures are shown incomplete for the purpose of illustration and explanation, and that in practice the reinforcing structures would extend along the entire length of the tubular member.
As best shown in Fig. 4, a second layer 7 of plastics, suitably a relatively soft plastics material such as PVC, or rubber overlies the reinforcing structures. As can be seen from the drawings, the textile strands are spaced so that, even with two superposed reinforcing structures, as in Figs. 3 and 4, there are interstices between the strands. During application of the second layer 7, or subsequently thereto, the two layers 2 and 7 are warmed sufficiently to fuse together through the interstices of the reinforcing layers.
Fig. 5 shows a variation on the structure of Figs. 3 and 4, in which a further layer of reinforcing strands 8 is employed, the strands, in this case, extending parallel to the axis of the tubular member. These strands help to prevent the tubular member stretching lengthwise.
For a tubular member 9 as shown in Figs. 3 and 4 or in Fig. 5, intended when inflated to serve as a goalpost, the diameter of the tubular member is preferably 3 inches (7.62cm) and has an overall thickness of 2mm. It will be appreciated that for such a structure, the textile strands must be in the form of thin textile thread. The textile thread may comprise conventional nylon sewing thread. It will be understood, however, that for other applications, different diameters and thicknesses may be chosen. The tubular member 9 when deflated is readily flexible, allowing a complete goal, even a full size Association Football (soccer) goal formed from struts consisting of such tubular members to be packed away in a bag that can be easily carried by one person, and placed in the boot (trunk) of a motor vehicle. Employing experimental 3 inch diameter tubular members as shown in Figs. 3 and 4 on a simple test rig, we have shown that at a typical inflation pressure of around 1 Bar, namely between 10 and 20 psi (6.89 to 13.79 *10 4 pascals), realisable with a foot pump or with an inexpensive tyre pressure pump operating from the cigar lighter socket of a vehicle, the tubular member, readily flexible when deflated is substantially inflexible when inflated, being capable of extending over a horizontal span in excess of 12 feet (3.66 m), the approved size for a mini-soccer goal under Association Football Rules, without any noticeable sag.
In contrast, tubular member 1 of Fig. 1 has reinforcing strands laid at an angle commonly used for garden hosepipes. Garden hosepipes are not intended to be rigid when filled. Indeed, in order to serve their purpose, hosepipes (even of 3 inch diameter, which would generally correspond to firemen's hoses) must necessarily still be capable of bending sufficiently to go round obstacles when inflated. Without significant additional bracing, a tubular member 1 as shown in Fig. 1 would not be suitable to serve as a structural member when inflated, in contrast to the embodiments of tubular member shown in Figs. 2 to 4.
The adoption of tubular members, especially as shown in Figs. 3 and 4, which possess enhanced rigidity when inflated, raises the prospect of providing Association Football goals generally of the kind disclosed in GB 2422322 A but with a reduced number of intermediate bracing structures for the crossbar, or none at all. It also raises the prospect of providing masts for equipment to be mounted aloft in the manner of our co- pending Application No: 0800703.1, where the mast is significantly taller than heretofore, or where the bracing structure is reduced.