CN101102821B - Trampoline - Google Patents

Abstract

A trampoline comprises a flexible mat (1) and a plurality of resilient flexible rods (2), wherein the lower ends of the flexible rods (2) are retained in a frame (3) of the trampoline and the upper ends of the flexible rods (2) are connected to the mat at the periphery of the mat to support the mat, wherein the bending stiffness of the rods is 1200-3000 N/m and the deflection of the upper ends of the rods (2) from a naturally placed state in which the lower ends of the rods (2) are located in the frame (3) but the upper ends of the rods are not connected to the edge of the mat to a state in which the upper ends of the rods are connected to the mat is a maximum of about 450 mm.

Description

trampoline

technical field

The present invention relates to improvements in trampolines for sports and/or recreation which are soft-sided as compared to conventional trampolines which support the trampoline by a solid perimeter frame with springs exposed between the frame and the mat mat.

Background technique

US 6,319,174 discloses a soft-sided trampoline form, wherein the mat of the trampoline is supported by a plurality of elastic flexible rods, the lower ends of the flexible rods are received in the trampoline frame, and the upper ends of the flexible rods are connected to the periphery of the bounce mat of the trampoline, which This trampoline does not require a strong frame on the outside of the bounce mat and exposed springs around the frame and mat perimeter.

Contents of the invention

The present invention provides an improved or at least alternative form of such a soft-sided trampoline.

In summary, one aspect of the present invention provides a trampoline comprising a flexible mat and a plurality of elastic flexible rods, the lower ends of the flexible rods are retained in the frame of the trampoline, the upper ends of the flexible rods surround the periphery of the mat and the mat Connected to support the mat, wherein the rods have a bending stiffness of greater than about 1200 N/m and may be as high as about 3000 N/m.

Preferably, the upper end of the rod deflects greater than about 300mm up to about 450mm from the natural resting state (the lower end of the rod in place in the frame but its upper end not attached to the edge of the cushion) to the upper end attached to the mat.

According to the present invention, the rods supporting the mat are deflected so as to apply the optimum load radially or laterally outwards to properly tension the mat for the usual function of a trampoline, while at the same time the length and diameter of the rods give the mat edges sufficient Resilient, shock-absorbing and vertical stiffness for safety against bouncers who might lose control and fall over the edge.

In the description (including the claims), the term "trampoline" is intended to extend to small trampolines commonly known as bouncers, and also to large trampolines of all sizes. The trampoline of the present invention can be circular, square, rectangular or other shapes, such as octahedral in plan view.

As used in the specification and claims, the term "comprising" means "consisting at least in part of". That is, when interpreting an independent claim that includes this term, the features prefaced by this term in each claim need to be present, but other features may also be present.

Description of drawings

Refer to the accompanying drawings to further illustrate the present invention by referring to the accompanying drawings below, in the accompanying drawings:

Figure 1 is a perspective view of a preferred form of trampoline;

Fig. 2 is a side view of the trampoline of Fig. 1;

Figure 3 is similar to Figure 1, but only shows one side of the trampoline, and shows a portion of the edge of the trampoline with sliced layers, and

Figure 3a shows an enlarged view of the cut away edge portion of the trampoline;

Figure 4 shows the rod deflection measurement at the edge of the trampoline;

Figure 5 shows the range of rod stiffness and rod deflection required to achieve the edge and pad performance required by the present invention;

Figure 6 shows the symbol notation for the cantilever bar used in the formula given below, and

Figure 7 shows the rod length versus diameter for GRP rods to achieve the indicated stiffness.

Detailed ways

Referring to Figures 1-3, a preferred trampoline comprises a flexible mat 1 on which a user bounces, a plurality of resilient flexible rods 2 and a base frame 3. The preferred form of the trampoline shown is circular, but the trampoline could be of other shapes, such as oval, square, rectangular or similar.

The base frame 3 of the preferred form of trampoline comprises a circular beam 4 formed, for example, of steel or aluminium, which is supported by legs 5 on the ground.

The rod 2 is typically a fiberglass rod and may be a pultruded (pultruded) glass reinforced plastic rod, but may also be made of eg spring steel. The lower ends of the rods are held by the bottom frame 3, while the upper ends of the rods are connected to joints 6 (described below). Joints 6 are connected to the periphery of the mat 1 . In the preferred form, the lower end of the rod 2 enters a tubular sleeve 7 secured to a circular beam (as shown), but the lower end of the rod 2 may be connected to the circular beam in any suitable manner, or to any other form of The bottom frame of the trampoline.

In a preferred form, the mat, typically a heavy canvas or woven synthetic material, is folded over itself and secured, for example, by sewing on the periphery of the mat to form one continuous pocket 8 extending around the periphery of the mat. A plurality of joints 6 are provided in pockets along the periphery of the mat, as shown in particular in Figures 3, 3a. The tab can be held loosely in the pocket or can be sewn to the mat within the edge pocket, or can be mechanically secured to the mat by, for example, rivets.

The rods of the preferred form each have a spherical upper end 12 which connects into a socket cavity below a joint 6 . Typically, the joint 6 is formed from a plastic material, eg by injection moulding. The fitting may optionally include a gently sloped dome on the fitting body above the socket cavity on the underside of the fitting. Also, in a preferred form, the joint has an outer edge which in use is closest to the outer periphery of the mat, which is wider in plan than the inner edge of the joint, so that the joint has an approximately truncated triangular shape and has, in plan view, Concave sides, but this is not limiting and the joint may have other shapes.

When building a trampoline from its components, the lower ends of the rods 2 are inserted into the sleeves 7 after the bottom frame 3 is assembled as required. At this point, the upper ends of the rods are free so that the rods will be in a non-deflected position, as indicated at 2a of FIG. 4 . Subsequently, the mat 1 is placed on the frame and the rods, and the upper ends of the rods are connected to the joints 6 one by one at the periphery of the trampoline. After the first few bars have been attached, then later when the upper ends of the bars are attached to the mat of the trampoline, the bars will deflect inwards towards the center of the trampoline to the deflected position shown in 2b of FIG. 4 . All rods are in deflected position 2b when the upper ends of all rods are connected to joints around the perimeter of the mat. The distance between the upper end of each rod in its deflected position (as indicated by 2b) and its undeflected position (as indicated by 2a) when it is not connected to the mat (the mat is held by other rods) is the deflection x of the rod (as shown in Fig. 4 shown). According to the invention, the deflection is up to about 450 mm, preferably between about 300-450 mm. At the same time, the rod is selected such that the rod has a stiffness against cantilever bending of between about 1200-3000 N/m.

Typically, the length of the rod is between 0.1-1.5 m, more typically between about 0.5-1 m.

We have found that such trampolines have good balance properties, first, that there is sufficient vertical stiffness at the edges of the mat so that when a jumper lands on the edge, the edges do not "collapse", and second, that the mat is stretched laterally so that when jumping The latter can provide good bounce performance when jumping in the center of the mat. That is, within these parameters, the rods are deflected such that the optimal load is applied radially outward to stretch the mat to provide good trampoline jumping performance. At the same time, the length and diameter of the rods give the edge of the mat a vertical stiffness that is sufficiently resilient, shock-absorbing, and safe for a bouncer who loses control and falls over the edge. Figure 5 plots these two measurements that define the scope of the invention.

The following further analysis uses the rod stiffness given above:

First, use the simple cantilever deflection formula. Symbol designations are shown in Figure 6 and are defined below. The deflection x is given by:

$x=\frac{{\mathrm{<figure-callout\; id="3"\; label="SL"\; filenames="H05846951120070724E000021.png,H05846951120070724E000041.png"\; state="\{\{state\}\}">SL</figure-callout>}}^3}{3\mathrm{EI}}$ (Formula 1)

where the second moment I of the area is given by:

$I=\frac{\mathrm{\&pi;}{d}^4}{64}\&Center\; Dot;C_I$ (Formula 2)

The stiffness k can be derived from Equation 1:

$k=\frac{S}{x}=\frac{3\mathrm{EI}}{L^3}$ (Formula 3)

The above formula can be expanded by formula 2 to get:

$k=\frac{3\mathrm{E\&pi;}{d}^4}{64{\mathrm{<figure-callout\; id="3"\; label="L"\; filenames="H05846951120070724E000021.png,H05846951120070724E000041.png"\; state="\{\{state\}\}">L</figure-callout>}}^3}\&Center\; Dot;C_I$ (Formula 4)

Rearranging, the length of the rod can be derived from:

$L=\sqrt[3]{\frac{3\mathrm{E\&pi;}{d}^4}{64k}\&CenterDot;C_I}$ (Formula 5)

Assuming that the stiffness k is known, as stated above, the nominal stiffness is 700 N/m, and the value of C _I is given below, then for any given rod diameter d and Young's modulus E, one can obtain by the formula 5 to calculate the length L of the rod.

In the formula:

I - the second moment of the actually measured area (corrected for GRP if appropriate) (m ⁴ );

S-bar tip load (N);

L - the free length of the rod from the outlet of the socket to the center of the ball (m);

d-rod diameter (m);

C _I - correction factor to the actual measured I value

(For pultruded GRP with a glass composition of 70%+, C _I =0.83; and for a homogeneous material like steel, C _I =1);

x-rod tip deflection, perpendicular to the undeflected centerline (m);

E-Young's modulus (for GRP rods, E=41Gpa);

k - "spring rate" of the cantilever, typically 700N/m.

For a rod stiffness in the range of 1200N/m-3000N/m, with a nominal stiffness of 2000N/m, Equation 5 for an example is plotted in Figure 7. This is a pultruded rod for glass reinforcement. Other materials require other graphs to define the length versus diameter relationship. Figure 7 shows the combinations of rod length and rod diameter that provide performance for a trampoline edge according to the present invention. With a specified initial deflection x (nominally 220mm), these combinations will simultaneously give the trampoline mat the best performance.

Thus, the figure shows the combination of rods required to achieve the two critical functions of mat tension and edge stiffness. These two functions can be achieved with different materials in the same manner as shown in the example, but with appropriate Young's modulus E and coefficient C _I .

The above describes the invention including the preferred forms. Alternatives and modifications obvious to those skilled in the art are intended to be incorporated within the scope of the invention as defined in the appended claims.

Claims (7)

1. trampoline, comprise a flexible mat and a plurality of resilient flexible link, the lower end of described flexible link is maintained in the framework of trampoline, the upper end of described flexible link is connected with mat with the supporting mat around the periphery of mat, and the bending rigidity of its king-rod is for can reach 3000N/m greater than 1200N/m and maximum.

2. according to the trampoline of claim 1, the length that it is characterized in that bar is 0.3-1.5m.

3. according to the trampoline of claim 1, the length that it is characterized in that bar is 0.45-1m.

4. according to the trampoline of claim 1, it is characterized in that described bar is the extruding fiberglass bar.

5. according to the trampoline of claim 2, it is characterized in that described bar is the extruding fiberglass bar.

6. according to the trampoline of claim 3, it is characterized in that described bar is the extruding fiberglass bar.

7. according to any described trampoline in the claim 1 to 6, it is characterized in that, but the natural laying state that the correct position bar upper end that is arranged in framework from the bar lower end is not connected with mat edge is connected with mat to the bar upper end, and bar upper end deflection can reach 450mm greater than 300mm and maximum.

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