TRAMPOLINE

Background

This disclosure relates to trampolines, and more particularly to support structures for supporting a trampoline sheet.

A typical trampoline comprises a sheet, usually, though not invariably, circular supported around its periphery within a frame like support structure by spring connections (usually a plurality of helical springs or an elastic cord) under tension which link apertures around the edge of the sheet to openings in the frame. The frame will generally have a configuration that matches that of the trampoline sheet. Thus, when the trampoline sheet is circular, the frame will usually take the form of a generally circular ring with a diameter larger than that of the sheet in order that the sheet is stretched. When the trampoline sheet is rectangular in shape, the frame will usually comprise a ring of generally rectangular form that is similarly larger than the sheet in order that the sheet may be supported by helical springs under tension. The frame must be supported above the ground or floor. A typical trampoline support structure comprises a plurality of tubular members adapted to fit together to form the frame. At least some of the tubular members have a stub pipe welded thereto, which is adapted to interfit with an upper end of a respective leg, the several legs together supporting the frame and the trampoline sheet above the ground or floor. The respective legs are suitably tubular and pairs of legs will typically be formed from a single tube bent into a generally U- or W-shape in which the uprights of the U or W form the legs proper, the lower ends of which are interconnected by the bight portion of the U or the central portion of the W. In the case of a U-shaped structure, the bight portion of the U provides support from the floor or ground, whereas in a W-shaped structure the lower angular corners of the "W" serve the same purpose.

Trampolines in normal use are subjected to repeated stress. When used contrary to the manufacturer's instructions, for example on an uneven surface, by being dragged from one position to another, by a user jumping from an off-centre position, and when more than one person is on the trampoline at any one time, they

are stressed unevenly, and often excessively. Moreover, they are often treated as garden equipment and left out in the cold and wet. As a result, corrosion or splitting of the welds between the tubular members and the stub pipes may occur over time, weakening the structure, potentially giving rise to a dangerous accident for a trampoline user.

In one attempt to overcome this problem, Thomas A James proposes a structural coupler for joining the tubular members and the legs in US 2004/0091307. The coupler is substantially T-shaped, providing a cross member support tube of square cross-section for receiving square cross-section ends of tubular members of the frame and an intersecting support tube of generally circular cross-section for receiving the upper end of a leg. The coupler avoids welds by starting from a single piece of pre-formed metal, bending it to create a complete tube and a complete cross member. Seams are formed at overlapping edges, the seams running up sides of the intersecting tube member and then along the undersides of the cross-member. Either the seaming must be performed on site about butted or overlapping ends of two tubular members and about the upper end of a leg to form the coupler in situ, or the coupler is preformed and seamed off site and ends of tubular members and the upper end of a leg are force fitted on site into the ends of the cross member and into the intersecting support tube. This requires a number of skilled fabrication steps. The configuration of the connections provided by James's coupler can only be female- female-female.

Arthur Chu in AU2006100018 also avoids welds. His coupler comprises a sleeve into which respective ends of tubular members forming the frame are loosely received with the end of one such tubular member located within the other. The sleeve is incomplete, its bottom wall being split, each half thereof being integral with one half of a split tubular portion, the two halves of which are adapted to be forced into the female opening at the upper end of a leg. The interfitted ends of the frame tubular members have through apertures. These are aligned with inwardly directed studs on the sides of the sleeve so that, as the split tubular portions are forced into the upper end of a leg, the sides of the sleeve are drawn together and the inwardly directed studs interengage with the aligned apertures. In this arrangement satisfactory holding of the frame tubular members is dependent upon the apertures

and studs being aligned and upon the extent by which the split tubular portions are received within the leg. Chu's arrangement requires skilled fabrication. His coupler necessarily has a male connection where it couples to the leg. Chu's described embodiment is of female-female-male configuration.

Summary

The present disclosure provides alternative solutions to the assembly of trampolines without welds.

In accordance with a first aspect of this disclosure, a trampoline comprises a trampoline sheet supported around its periphery from a support structure by spring couplings (preferably a plurality of helical springs) under tension; the support structure comprising a tubular frame supported by a plurality of legs, the tubular frame being formed from a plurality of tubular members and respective couplers that both couple end portions of the tubular members together to form the said tubular frame and couple upright ends of the legs to the frame, each coupler comprising a single piece of metal or plastics formed without welding generally into a T-shape having a cross-piece and an upright piece, in which ends of the cross-piece are received in male fashion within ends of the tubular member, and in which the upright piece is received in male fashion within a female end of a leg.

Preferably at least end portions of the tubular, members are of generally four sided (preferably generally square) cross-section, and the upright ends are also of four sided (preferably square) cross-section.

Each coupler may be formed from a flat sheet metal or plastics blank by no more than folding along straight lines to provide a hollow generally T-shaped box form having a hollow cross piece and a hollowupright piece.

In an alternative arrangement, the coupler may be injection moulded from plastics as a solid unitary structure.

In a second and alternative aspect of this disclosure, a trampoline comprises a trampoline sheet supported around its periphery from a support structure by spring couplings (preferably a plurality of helical springs) under tension; the support structure comprising a tubular frame supported by a plurality of legs, the tubular frame being formed from a plurality of tubular members, and respective couplers that both couple end portions of the tubular members together to form the said tubular frame and couple upright ends of the legs to the frame, each coupler comprising a pair of separate and complementary coupler members each consisting of a single piece of metal or plastics formed without welding, the coupler members, when placed together, meeting generally in a medial central plane of the coupler to form a generally T-shape having a cross piece and an upright piece, ends of the cross piece being received in male fashion within ends of the tubular member, and ends of the upright piece being received in male fashion within a female end of a leg.

Preferably at least end portions of the tubular members are of four sided

(preferably generally square) cross-section, and the upright ends are also of four sided (preferably square) cross-section.

Each coupler member may be formed from a flat sheet metal or plastics blank by no more than folding along straight lines to provide half of a hollow generally T-shaped box form having a hollow cross piece and a hollow upright piece.

In an alternative arrangement, each coupler member may be injection moulded from plastics as a solid unitary structure.

Where the tubular members of the support structure together define a generally circular ring, the respective T-shaped couplers have cross pieces that are slightly curved to follow the shape of the circular ring. In arrangements with a coupler formed of two coupler members of complementary form, the two members may meet on a slightly curved surface rather than in a true medial plane. The expression "meeting generally in a medial central plane of the coupler to form a generally T-shape" is used herein with the intention of encompassing such arrangements.

Trampolines in accordance with the teachings herein have a support structure coupled together with couplers that do not require welding either in manufacture or use and provide all male coupling connections, a configuration that would be impossible with either James's or Chu's teachings.

The all-male connections allow the couplers to be force-fitted into ends of the tubular members and into the upright ends of tubular legs.

While the spring couplings are preferably helical springs, it will be understood that other forms of spring may be substituted, including the possibility of an elastic cord interlaced between apertures around the periphery of the trampoline sheet and openings in the tubular frame.

Brief Description of the Drawings

A number of embodiments are described in more detail hereinbelow with reference to the accompanying drawings in which: -

Fig.l is an exploded perspective view of portions of a trampoline support structure including tubular members and a coupler that form a frame, and a leg; Fig 2 is an enlarged view of the portion, of Fig 1 shown in a circle; Fig 3 is a further enlarged perspective view of the coupler from one end; Fig 4 shows the coupler of Fig 3 in end elevation;

Fig 5 shows a flat blank fro m which the coupler of Figs 2, 3 and 4 may be formed;

Figs 6 to 8 are views respectively, similar to Figs 1 to 3 for an alternative embodiment of coupler;

Fig. 9 is a view similar to Fig 8 but with the two halves of the coupler separated; and Fig. 10 is a view similar to Fig. 2 for a further embodiment of coupler.

Description of Preferred Embodiments

Referring first to Fig 1, a support structure 1 for a trampoline comprises a plurality of tubular members 2 coupled together to form a complete frame, supported above the ground or a floor by legs 3. As illustrated in Fig 1, both the tubular members 2 and the legs 3 have four sided, (preferably square) cross-sections, but only their respective ends need have these cross-sections. While a four-sided cross-section for the ends of the tubular members is generally to be preferred, since this prevents rotation of a coupler within a tubular member end, a four-sided cross- section is not essential. The tubular members are coupled together to form the frame and the frame is coupled to the legs by respective T-,couplers 4, of which only one is shown.

It will be understood that a trampoline sheet is stretched within the frame, which may be generally circular if the sheet is circular, by spring couplings in conventional fashion. The spring couplings preferably comprise a plurality of helical springs coupled between eyelets formed in a reinforced edge of the sheet and respective openings in the tubular members 2 making up the frame. The openings for the springs may be provided on the radially inner side of the tubular members or on the vertically upper side thereof. Alternatively, an elastic cord may interlace the eyelets with the frame. The trampoline sheet and its manner of fixing to the support structure are entirely conventional, and will be known to all persons of ordinary skills in the trampoline field; and it is therefore deemed unnecessary to particularly describe examples of such components or to illustrate them in the accompanying drawings.

Coupler 4 is best shown in Figs 2, 3 and 4 and comprises a hollow T-shaped structure with a cross piece 5 and an upright piece 6. Coupler 4 is formed from a single sheet metal or plastics blank 7, shown in Fig. 5, by folding along lines 8, 8a, 9, 9a, 10 and 11 to form a box section cross piece 5; and folding along lines 12, 13, 14 and 15 to provide a box section upright piece 6. Construction of the coupler is thus extremely simple.

Box-shaped ends 16 of the cross piece 5 are sized to fit in male fashion within four sided female end portions of tubular members 2. Similarly, box section upright piece 6 is sized to fit in male fashion within four sided end portion of leg 3.

In the drawings, coupler 4 is a shown operating in a male-male-male configuration, a configuration that would not be possible with the teachings of either James or Chu.

A generally T-shaped coupler formed simply by folding along straight lines, whether used for coupling a trampoline support or for other purposes, is believed novel per se.

The way in which the upright piece is formed in the illustrated embodiment from the blank 7 by folding necessarily means that upright piece 6 has longitudinal splits 17 extending along both opposed sides of the upright piece throughout its whole length.

Figs 6 to 9 illustrate an alternative embodiment for the male-male-male configuration coupler. For convenience like reference numerals are employed for like parts. The difference between coupler 104 of this embodiment and previously described coupler 4 is that it is formed in two separate pieces 104a and 104b. As can be seen from Fig. 9, these separate pieces are not only complementary mirror images of each other, but are actually identical, which makes manufacture simple. A sheet metal or plastics blank for forming the ;pieces' 104a, 104b comprises half of the blank of Fig 5. The two pieces 104a and 104b are brought into confronting relation, as in Figs 7 and 8, and inserted together into the female openings respectively provided by the ends of the two tubular members 2 and the upper end of leg 3. Although we prefer the fit to be tight, this is not essential with a male-male- male configuration because, provided that the! male: etids remain inserted, the tension in the spring couplings supporting the trampoline sheet will tend to hold the frame together, while gravity will ensure that the upright piece remains within the upper end of the leg.

Fig. 10 illustrates another alternative male-male-male coupler employed in forming a support structure for a trampoline. In this arrangement, T-shaped coupler 204 is simply injection moulded from plastics as a solid unitary structure. A suitable structural plastics material is Nylon 6. Ends of cross-piece 205 may be force-fitted into ends of the tubular members 2. Similarly, the end of upright piece 206 may be force-fitted into the upper end of leg 3. Hie ..embodiment of coupler 204 illustrated

in Fig. 10 has a generally four-sided (preferably square) cross-section to both cross- piece 205 and upright piece 206, which helps to prevent rotation of the coupler relative to the tubular members 2 or leg 3, this is not essential. In alternative arrangements the cross-piece 205 and upright 206 may be of circular cross-section intended to fit in male fashion within generally cylindrical ends of the tubular members 2.

With a trampoline support structure of generally circular ring form mounting a circular trampoline sheet, the cross-piece of any coupler is preferably slightly curved to follow the circular shape of the ring, and hence the curved shape of any tubular member.