Patent Application
20160298328
This application is claims priority under 35 U.S.C. §119(a) to Great Britain Patent Application No. GB 1506027.0, filed Apr. 9, 2015, which is incorporated by reference in its entirety.
1. Field of the Invention
The present invention relates to a joint for a collapsible support structure. The collapsible support structure can, for example, form part of an assembly for supporting a net, screen, display board or tent.
2. Description of the Related Technology
Support structures which are assembled to support a net in a vertical orientation are known. WO-93/01866A describes a net support structure which provides for easy assembly and disassembly at any location. The net support structure includes a plurality of modules which are joined together by an elastic cord. The modules are connected together to tension the elastic cord and form a support structure for the net. The support structure can be collapsed by disconnecting the modules, allowing the modules to be folded relative to each other whilst at the same time keeping the modules joined by the elastic cord.
According to the present invention, a collapsible support structure is provided with a hollow member with an open end wherein the end includes a leading portion and a trailing portion. A resilient flexible member extends through at least part of the hollow member and out of the open end into a second hollow member.
Such a construction reduces the likelihood of the resilient flexible member breaking or snapping in use.
When the collapsible support structure is folded, the resilient flexible member is exposed between the two ends of the hollow members. It has been observed that the resilient flexible member in support structures such as those discussed in WO-93/01866 is prone to breakages. The applicant has identified that one factor in breakage of the resilient flexible member is that when it is exposed by collapsing and folding the support structure, the resilient flexible member extends across the edge of an open end of the two members. The resilient flexible member may also be tensioned by this action. Should the folded structure be dropped, or otherwise impacted, the resilient flexible member can form the first point of impact. The force and impulse of the impact can cause conventional flat/straight ended hollow members to sever or weaken the resilient cord. For example, the hollow members may have a relatively high mass giving them considerable momentum. The leading edge of the hollow member provides protection against such damage for the resilient flexible member. According to a first embodiment of the invention there is provided a collapsible support structure comprising a first hollow member defining an axis. The first hollow member comprises an open end. A second hollow member is adapted to engage the open end when the support structure is assembled. A resilient flexible member extends at least partially through the first hollow member and the second hollow member. A perimeter of the open end comprises a leading portion and a trailing portion, the leading portion being positioned further along the axis than the trailing portion.
The reference to a hollow member includes a member of any cross section, and the cross section can vary or remain constant over the length of the tube. The perimeter is defined by the outer edge of the hollow member end. Consequently, in some embodiments, when the first hollow member is tubular, the perimeter may be elliptical. In other embodiments the first hollow member has a square or rectangular cross section, so the perimeter may be defined by a square or rectangle. Any suitable cross section can be used including elliptical, circular, square or rectangular.
The axis of the first hollow member may, for example, be a longitudinal axis, a centroidal axis or a neutral axis of a cross section of the hollow member. The hollow member may be straight or curved. Should the hollow member be curved, the axis may be defined as tangential to the curve at the open end of the hollow member.
The resilient flexible member may have a single piece, twisted, braided or composite structure for example it may be a cord. The resilient flexible member may extend completely through the first hollow member and the second hollow member in some embodiments. In other embodiments it extends completely through one member and at least partially through the other.
In some embodiments the open end of the first hollow member could define one or more points or peaks when viewed from the side. In this case an apex of the point or peak forms a leading portion, and the trailing portion is located at a position away from the apex. For example, the trailing portion may be a trough in comparison with the peak defined by the apex.
When the structure is collapsed, the first and second hollow members may be folded relative to each other so the resilient flexible member extends from the open end of the first hollow member. Should the end of the first hollow member be subject to an impact, the leading portion of the perimeter provides a degree of protection to the resilient flexible member. The leading portion is positioned further along the axis than the trailing portion, this has the benefit that the leading portion is more likely to receive the impact first, protecting both the trailing portion and the exposed flexible member.
It has been found that when the open end of a hollow member has a leading portion and a trailing portion, a resilient flexible member naturally settles or rests towards or near the trailing portion when the structure is collapsed and folded. The resilient flexible member is then less likely to impact the ground before any other part of the hollow member. In contrast, a hollow member without a leading portion and trailing portion may cut or sever the cord on impact when the member crushes the cord between itself and the impact surface.
The distance between the leading portion and the trailing portion along the axis may be greater than or equal to or less than a largest cross sectional dimension of the resilient flexible member. In some embodiments, where the resilient flexible member is substantially cylindrical, the distance between the leading portion and the trailing portion along the axis is greater than a diameter of the resilient flexible member. This provides improved protection for the resilient flexible member because the leading portion will be the first point of impact for impacts with surfaces in the direction of the axis. This is advantageous to protect the flexible member from impact or wear. If the distance is less than the diameter of the flexible member, but is non-zero, the flexible member may be the point of first impact when the structure is impacted along the direction of the axis when folded. However, the leading portion will normally then impact the surface before the trailing member as the flexible member is compressed during the impact and act to limit compression exerted by the trailing edge. The compression exerted by the trailing portion on the resilient flexible member may then not be enough to cause the cord to sever or wear.
In some embodiments the perimeter of the open end defines a surface disposed at an acute angle relative to the axis. When the surface defined by the perimeter is at an acute angle it is not perpendicular to the axis defined by the hollow member. A surface which is perpendicular to the axis can cause the cord to be damaged on impact, as discussed above.
In some embodiments the perimeter defines a surface which is planar. A planar surface can be manufactured simply, for example by making a mitred cut to the end of the tube. In other embodiments the perimeter defines a surface which is curved in one dimension. The surface may also be curved in two or three dimensions.
In some embodiments the perimeter of the open end has at least two leading portions and at least two trailing portions. This may be advantageous when the support structure comprises more than one resilient cord extending at least partially through the first hollow member.
In some embodiments the second hollow member defines a second axis and comprises a second open end having any or all of the features of the first hollow member discussed above. For example, a second perimeter of the second open end comprises a second leading portion and a second trailing portion, the second leading portion being positioned further along the second axis than the second trailing portion. When both the first and second hollow members have an open end with a perimeter comprising leading and trailing portions, the protection provided to the resilient cord is increased.
The support structure of the invention can form part of an assembly for supporting a generally planar or sheet-like member. For example it can be used in a sports net, a safety net, a display stand or a screen. Thus, the generally planar member can be a poster, board, sheet, screen or net in some embodiments. An assembly using the support structure may have one or more support structures.
A sports net comprising one or more of the support structures may be part of a sports kit including at least one additional item of sporting equipment. For example the sports kit may include one or more rackets, balls, shuttlecocks and other equipment.
The support structure of the invention can form part of an assembly for a tent. For example, a tent pole may comprise one or more support structures.
According to another aspect of the invention there is provided a method of manufacturing a collapsible support structure. The method comprises providing an open end of a first hollow member with a perimeter comprising a leading portion and a trailing portion. The first hollow member defines an axis and the leading portion is positioned further along the axis than the trailing portion. The method further comprises extending a resilient flexible member at least partially through the first hollow member, through the open end and into a second hollow member.
The method of providing an open end to the first hollow member with a perimeter may comprise cutting the open end of the hollow member at an acute angle relative to the axis of the hollow member. In one embodiment a machine tool is used that can cut through the hollow member at any specified angle. For example, the end of the first hollow member may be given a mitred cut. This provides a simple and effective way to make the leading portion and trailing portion of the perimeter. However, other methods may also be used, for example, in another embodiment an angled surface may be produced by filing the open end of the hollow member.
The method of providing an open end to the first hollow member with a perimeter may comprise affixing a cap to the hollow member, the cap having the perimeter comprising the leading portion and the trailing portion. In one embodiment the hollow member has a cap fitted to the open end wherein the cap comprises a leading portion and a trailing portion. The cap may be constructed from a different material to that from which the hollow member is made. The cap may also be made of the same material as the hollow member. The cap may also be removable and replaceable. This may be advantageous if the cap, particularly the leading edge of the cap, wears down through use. Any suitable method can be used to affix the cap, including a friction-fit, adhesive and welding depending on the materials of the cap and the hollow member.
In some embodiments the method of manufacturing a collapsible support structure may also comprise swaging at least an end portion of the first or second hollow member. The swaging of at least a portion of the first or second hollow member occurs before or after providing an open end of the first or second hollow member. Swaging is the process of reducing or increasing the diameter of at least a portion of a hollow member. When the support structure is assembled, the second hollow member is adapted to engage the open end of the first hollow member. In one embodiment the second hollow member is swaged, reducing the diameter of at least a portion of the second member. This allows the reduced diameter portion of the second member to be inserted into the open end of the first member. In other embodiments the first hollow member is swaged and fits inside the second hollow member.
In another embodiment, there is provided a collapsible support structure comprising a first hollow member defining an axis, wherein an open end of the first hollow member is mitred; a second hollow member adapted to engage the open end when the support structure is assembled; and a resilient flexible member extending at least partially through the first hollow member and the second hollow member. The mitred end can provide protection for the resilient flexible member in the event of an impact. This embodiment can be combined with the features of the embodiments described above.
Further features and advantages of the invention will become apparent from the following description of preferred embodiments of the invention, given by way of example only, which is made with reference to the accompanying drawings.
A resilient cord 8 extends at least partially through the first and second hollow members 4 and 6 respectively. In this embodiment the resilient cord is made from natural latex rubber threads forming a multi-stranded core surrounded by a monofilament polyethylene (PT) outer coating. In other embodiments, the resilient cord may comprise any other suitable material, including elastomers, springs or other stretchable material capable of tensioning a support structure. It will also be appreciated that the monofilament outer coating is not essential and can be omitted or replaced with other outer coatings, for example a polyester (PE) outer coating. The cord 8 is tensioned by being fixed or anchored at both ends. This anchoring could be within the first or second hollow members 4, 6 or it may be fixed elsewhere.
When assembled, the second hollow member 6 is adapted to engage the first hollow member 4. A portion 12 of the second hollow member 6 has a diameter that is smaller than the opening 10 defined by the first hollow member 4. For example, the diameter of the second support member can be reduced by swaging. This allows the reduced diameter portion 12 to fit inside the open end 10 of the first hollow member 4. To assemble, the second hollow member 6 is moved in the direction of the arrow 16 to be fit inside the open end 10 of the first hollow member 4. The resilient cord 8 is then concealed within the two members 4, 6. A second portion 14 of the second hollow member 6 may have the same size diameter as the first hollow member 4 so that movement in the direction of the arrow 16 is restricted when the second portion 14 abuts the open end 10 of the first hollow member 4. Once in this assembled position, structural integrity is maintained by tension in the resilient cord 8 acting to hold the two members together.
Other methods of connecting the two hollow members together can be used in other embodiments. For example, the first and second hollow members 4, 6 may have the same diameter, and a collar, or sheath (not shown) is placed around the joint to retain them in place.
To collapse the structure, the first and second hollow members 4, 6 are pulled apart against the tension of the resilient cord, exposing the resilient cord 8, to the original position shown in
The first hollow member 4 defines an axis 24. In this embodiment, the axis 24 is a longitudinal axis of the first hollow member 4.
The perimeter 40 of the open end 10, shown most clearly in
In this embodiment the perimeter 40 is elliptical. In other embodiments the perimeter 40 defines an ellipse, circle, square or rectangle.
The perimeter 40 of the open end 10 comprises a leading portion 30 and a trailing portion 32 (shown in
In some embodiments, the surface defined by the perimeter 40 is disposed at an acute angle 34 relative to the axis 24. In one example, the angle is 45 degrees. In other examples the angle is less than about 70 degrees, less than about 65 degrees, between about 55 and 70 degrees, or between about 60 and 65 degrees. Other angles may be used in other embodiments, the scope is not limited only to these ranges. In some embodiments the angle is selected based on the diameter of the resilient cord 8. For example, the angle may be selected with knowledge of the diameter of the resilient cord 8 and the diameter and wall thickness of a tubular hollow member so as to ensure that the distance between the leading edge and the trailing edges is greater than or equal to the diameter of the resilient cord 8. In some embodiments the distance between the leading and trailing edges is between about 4 mm and about 2 cm, for example about 4 mm, 6 mm, 8 mm, 1 cm or 2 cm. In some embodiments the diameter of the resilient cord 8 is approximately 4 mm to 2 cm, for example about 4 mm, 6 mm, 8 mm, 1 cm or 2 cm. In some embodiments the diameter of the hollow member is approximately 19.1 mm (¾ inch) or approximately 22.2 mm (⅞ inch). In some embodiments the wall thickness of the hollow member is approximately 1.2 mm or 0.91 mm.
In embodiments where the surface is a curved surface, the tangent of the curved surface at any position is disposed at an acute angle 34 relative to the axis 24.
In some embodiments, the distance 38 between the leading portion 30 and the trailing portion 32 along the axis 24 is greater than a diameter of the resilient cord 8. This is advantageous to ensure that when the leading portion 30 contacts a surface, such as the ground, the resilient cord 8 is unlikely to contact the surface, thus protecting it from impact or wear. If the distance is less than the diameter of the cord, but is non-zero, the cord may impact the ground first when the support structure is dropped. However, the leading portion is then likely to collide with the ground as the cord is compressed due to the motion of the hollow member and the compression already experienced may not be substantial enough to cause the cord to sever.
In this embodiment both the first and second hollow members 4, 6 have a leading portion and a trailing portion. In other embodiments the second hollow member 6 may have a perimeter which defines a surface disposed at a right angle to a second axis 36. Therefore there will be no leading or trailing portion and the distance 38 will be zero. Such a configuration will still provide some protection to the cord 8 in the event of an impact.
The above embodiments are to be understood as illustrative examples of the invention. Further embodiments of the invention are envisaged. For example, although the invention has been described in the context of a single joint of a structure, a structure can comprise two or more such joints. Although the first and second hollow members have been shown in particular relative orientations in the drawings, other orientations may also be used. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1506027.0 | Apr 2015 | GB | national |
