Field of the art

The presented invention is a construction of mobile sports goal of increased safety, thanks to which the risk of injury during sports activities, especially football (soccer), is reduced.

State of the art

While doing some sport activities, especially football (soccer), mobile goals made of steel or duralumin are currently used. The disadvantage of these gates is that their stabilization, according to the standards, requires use of heavy weights, or other anchoring systems, which is inconvenient in case of frequent relocation of the goal and very often this is neglected, which leads to serious injuries, often resulting in death, particularly among children, which are used to hang on the goal structure, swing on it and otherwise disrupt its stability. It is therefore necessary to develop mobile sports goal of increased security.

A published international application No. WO 2008/152175 describes a sports goal having reduced risk of injury for sporting people, as well as standard features as regards balls bouncing. Its two side bars and beam contain a solid core of metal, wood or similar material, which is surrounded by a spongy porous shell based on EPDM (ethylene-propylene-diene-monomer), which in turn is covered with an outer layer of polyethylene bearing polyurethane coating.

A published international application No. WO 2007/096435 describes a sports goal that prevents injuries that could be caused due to an impact of the structure of the goal. This goal contains bars and beam, which are made of flexible material such as rubber, which may be filled with sand, gravel, liquids, iron sawdust or similar material. A published international application No. WO 2009/129257 describes an anchoring device and a method of anchoring of a mobile goal.

Document FR 2 610 205 relates to a mobile device used in a sporting environment, made of tubular aluminum sections. It also includes a system of wheels, an anchoring system for fixing the goal to the ground at two places. The device is equipped with a system of carabines for attaching a net.

Summary of the invention

The aim of the presented invention is to provide mobile sports goal construction of increased safety without the need for additional anchoring or use of weight systems. Goal of increased safety within the meaning of the invention means a goal that cannot tip over or it may tip over, but only with difficulties, and if it tips over, it goes down with the lowest possible energy.

This task is solved, according to the presented invention, through the design of mobile sports goal, which in working position comprises:

• two vertical bars,

• a horizontal beam that connects the upper ends of the vertical bars

mentioned above,

• a pair of bottom horizontal side bars, each of which is attached to the lower end of one of the vertical bars,

• rear bottom horizontal bar, an end of which is connected to an end of one of the pair of the bottom horizontal side bars, the other end of the rear bottom horizontal bar being connected to an end of the other of the pair of the bottom horizontal side bars,

characterized in that the weight and lengths of all its parts are designed for ensuring that the center of gravity of the goal in it ^' s working position is at a distance of at least 40% of the depth from the plane defined by the vertical bars and at a distance of less than 50% of the height of the goal from the plane defined by the bottom side bars and at a distance of 40 to 60% of the width of the goal from the plane defined by the vertical bar and the neighboring bottom side bar.

Other preferred embodiments are presented in the dependent claims. The above mentioned arrangement of the center of gravity is preferably achieved by increasing the weight of the rear bottom bars, which can be, like all the other bars hollow, but unlike them, at least partially filled with a filling material, preferably concrete, to increase its weight, preferably in such a way that the center of gravity of this bar in working position is approximately in the middle of the bar length.

The structure of the goal of the presented invention is defined using an open definition and therefore it may also contain additional components or bars, for example for attaching and / or straining the net and / or for facilitating any transport of the goal. In one embodiment the goal of the presented invention may contain means for attaching and/or straining the net such as bars, hooks, carabines, eyelets, wires etc. The net may be attached to the goal of the presented invention permanently, by means of adhesives or processes using heat, such as melting and welding. Another embodiment of the goal according to the present invention may contain means for simplifying the relocation of the goal, such as wheels and handles.

All terms used to define the placement and the direction of the construction of the goal of according to the invention, such as "vertical ", "horizontal", "parallel", include also respective deviations from these conditions, for example deviations caused by technical limits for manufacturing. All the properties described independently in respect of individual parts (such as bars) of the goal according to the present invention as such apply for each and every of these parts individually. For example one embodiment may comprise a horizontal beam and vertical bars being circular in cross-section and the bottom rear bar and the bottom side bars being of a square cross-section.

The term "bar" or "beam" means straight pole preferably, but the invention includes any possible types of embodiments, such as curved poles, which may be used on different occasions, according to the rules of a sport. Horizontal beam and vertical bars are usually, and preferably, straight, but the rear bottom bar and side bottom bar may be curved differently and may form an arc for example. Bars and beams can be of any cross-section, for example circular, square, rectangular, oval, preferably they are of square or circular cross-section, most preferably circular. Bars and beam (and the corners) may be hollow, partially filled or completely filled with the same material they are made of, or filled with other materials. The vertical bars and the horizontal beam have a standard features in terms of balls bouncing. Similarly, the term 'corner' defines not only sharp right-angle corner, but the invention includes other possible shapes of corners, such as an arc, which may be used on different occasions, according to the rules of a sport. The weight of the rear bottom bar to the weight of the horizontal beam is greater or equal to a ratio of 2.5:1. Preferably, this ratio is 3:1 to 7:1 , more preferably 3:1 to 5:1 , most preferably 3.5:1 to 4: . All those ratios within the above mentioned range are to be understood as if they were individually and explicitly mentioned. For example, the range of 3:1 to 5:1 , includes ratios 3,1 :1 , 3,2:1 , 3,01:1 , 3,11 :1 , etc. Goals known from prior art have said ratio 2:1 (steel goal) and 1 :2— 2:1 (duralumin goal). The ratios listed above will be achieved by making the rear bottom horizontal bar heavier than the horizontal beam and / or by making the rear bottom corners heavier than the top corners. The weight of the bars, beams, and corners can be influenced for example by using materials with different densities, using the same material with different wall thickness, using fillings, or by adding (bolting, welding) extra weight into the bottom rear corners and / or the rear bottom bar.

The vertical bars, side bars and the front bottom corners will also have an impact on the stability of the goal of the presented invention, but their influence is lower than the ratio described above. The influence is negligible in case of a usual ratio of the length of the vertical bar to the length of the side bar, which is about in a range of 4:1 to 1:1.

Preferably, the structure of the mobile goal according to the invention is not heavier than 100 kilograms, such that it is not too heavy to carry.

Although the structure of the goal according to the invention may be made generally of any suitable material such as metals and metal alloys (steel, aluminum, duralumin etc.), it is preferably made of plastic, for example polyamide (PA), teflon (PTFE), polyester (PES), polypropylene (PP), polyvinyl chloride (PVC), polyphenyl sulfide (PPS), acrylonitrile-butadiene-styrene (ABS). It is preferably reinforced with fibers such as fiberglass (E-glass, S-glass), carbon fibers, aramid fibers, basalt fibers, dynema fiber or natural fibers, the plastic materials may contain 20 to 99% by weight of matrix and 80 to 1 % by weight of reinforcing materials. Another embodiment is made of composite materials, wherein a preferred composite material is resin, for example epoxy resin, polyester resin, vinyl-ester resin, or methyl-methacrylate resin, which is reinforced with fibers such as fiberglass (E- glass, S-glass) , carbon fibers, aramid fibers, basalt fibers, dynema fibers or natural fibers.

According to a preferred embodiment of the goal the horizontal beam is made of composite material, which comprises:

20 - 75 % by weight matrix made of epoxy resin

80 - 25 % by weight reinforcing material, containing

10 - 40 % by weight carbon fibers

90 - 60 % by weight fiberglass

According to a preferred embodiment of the goal the vertical bars are made of composite material, which comprises:

20 - 75 % by weight matrix made of epoxy resin

80 - 25 % by weight reinforcing material, containing

5 - 20 % by weight carbon fibers

95 - 80 % by weight fiberglass

According to a preferred embodiment of the goal the rear bottom horizontal bar and the bottom horizontal side bars are made of composite material, which comprises: 20 - 75 % by weight matrix made of epoxy resin

80 - 25 % by weight reinforcing material, containing

00 % by weight fiberglass

The composite material may contain additional ingredients such as additives and / or fillers, heat stabilizers, UV stabilizers, UV absorbers, antioxidants, pigments, dyes, etc.

The construction of the goal according to the invention may be produced by using any standard way of production that is appropriate for the type of material from which the goal is made, such as drawing, welding, injection molding, pressing, blow molding, knitting, winding, fabric winding, etc.

The structure of the goal according to the invention may be used wherever mobile sports goals are needed, for example in sports facilities like sports clubs or public sports facilities, playgrounds and school playgrounds. The goal according to the invention may be used as a fixed goal after it has been attached to the ground. The presented invention will be described further in more detail while using examples and attached drawings, which, however, do not limit the scope of protection of the presented invention. Even though the presented invention will be described by using the football (soccer) goal embodiment, the invention is not limited to the footbal (soccer) goal and the invention covers also goals used in other sports such as handball, hockey, lacrosse etc. or in further modifications of these sports for example indoor soccer, beach soccer, the national handball, beach handball, floorball, inline hockey; wherein the dimensions of the goal of the presented invention depend on the rules of the sport that it is made for, or the goal may have universal size for a use in public sports facilities, playgrounds or school playgrounds. An skilled person will be capable to adopt the goal of the presented invention for any sport as well as for 'non-standard' use, such as preparing reduced size embodiment for kids playgrounds.

Brief description of the drawings

Fig. 1 shows a perspective top front side view on the construction of the mobile goal of the presented invention.

Fig. 2 schematically shows a side view on the construction of the goal of the presented invention in stable positions S1 and S2 and an unstable position L

Exemplifying embodiments of the invention

Example No. 1 : construction of a mobile sports goal

An embodiment of the construction of the mobile sports goal of the presented invention (see fig. 1 ) contains:

• two vertical bars 3; • a horizontal beam 1 which connects the upper ends of said vertical bars, wherein the joints formed by each of the side ends of the horizontal beam and the upper ends of the vertical bars are called the upper corners A;

• a horizontal rear bottom bar 2 arranged behind a vertical plane passing

through said vertical bars 3 and said horizontal beam 1, wherein said horizontal rear bottom bar is parallel to a line passing through the bottom ends of said vertical bars;

• bottom side bars 4 passing from the lower ends of said vertical bars in the direction behind the vertical plane of said vertical bars 3 and of said horizontal beam 1 , wherein the bottom side bars 4 connect the bottom ends of the vertical bars 3 and the side ends of the horizontal rear bottom bar 2, while the joints formed by the front ends of the vertical bars 3 and the lower ends of the vertical bars 3 are called the front bottom corners B, and the joints formed by the rear ends of the bottom side bars and by the side ends of the rear bottom horizontal bar 2 are called the rear bottom corners C.

The center of gravity of the goal in its working position is in a distance of 65% of the depth from a plane passing through the vertical bars. It is also in a distance of 28 % of the height of the goal from a plane passing through the bottom side bars and it is in a distance of 50% of the width of the goal from a plane passing through the vertical bar and through the adjoining bottom side bar.

Example No.2: construction of a mobile football (soccer) goal

A construction of the mobile football (soccer) goal was made with following parameters:

length of the vertical bars 3: 2 m

length of the horizontal beam 1 and the rear bottom bar 2: 5 m

length of the bottom side bars 4: 1.5 m

weight of the beam V. 7.5 kg

weight of the upper corner A: 1.5 kg

total weight of the beam 1 + upper corners A: 10.5 kg

weight of the vertical bars 3: 3 kg

weight of the bottom side bar 4: 2.25 kg

weight of the front bottom corner B: 1.5 kg weight of the rear bottom bar 2: 7.5 kg

weight of the rear bottom corner C: 13.25 kg

total weight of the rear bottom bar 2 + rear bottom corners C: 35 kg

The weight ratio of the weight of the bottom rear bar 2 and the rear bottom corners C to the weight of the horizontal beam and the upper corners A is 3,33: 1.

The horizontal beam 1 contains: 25% by weight matrix of epoxy resin SCHELL, 75% by weight reinforcing material containing 30% by weight carbon fiber (Toray T700) and 70% by weight fiberglass (E-glass, OWENS CORNING)

The vertical bars 3 contain: 25% by weight matrix of epoxy resin SCHELL, 75% by weight reinforcing material containing 10% by weight carbon fiber (Toray T700) and 90% by weight fiberglass (E-glass, OWENS CORNING)

The rear bottom bar 2 and the bottom side bars 4 contain: 25% by weight matrix of epoxy resin SCHELL, 75% by weight reinforcing material containing 00% by weight fiberglass (E-glass, OWENS CORNING)

Example No.3:

The construction of the goal according to the example No.2 (Goal I - composite) was tested along with normally used goals (Goal II - steel, Goal III - duralumin). The purpose of these tests was to find the center of gravity (T) and to test other features (see fig. 2) linked to the center of gravity. The results are shown in the following tables.

Table No.1

Center of Weight Diameter of the Shape of the gravity- position beam beam in cross- section xt yt m R

(m) (m) (kg) (m)

Goal I - composite -0,67 0,61 59 0,094 Circular cross- section

Goal II - steel -0,56 0,96 78 0,049 Circular cross- section

Goal III - duralumin -0,24 1,39 50 0,1-0,117 Oval cross- section Table No.2

These tests clearly show that the goal of the presented invention has the center of gravity furthest in the back (position in the x-axis) and the center of gravity is lowest (position in the y-axis).

The results from these tests were then used to calculate the energy needed for tipping over the goal (E_S1-L) and to calculate the minimal kinetic energy at the impact. All these results are listed in the table down bellow.

Table No.3

The results show that the goal of the presented invention has the best stability and the energy needed for tipping the goal over is highest. However if the goal tips, the kinetic energy at the impact is the lowest. That proves again the safety of the goal of the presented invention.

Example No. 4

An assessment of the goals according to the technical standard EN 748 as to their safety and of the related characteristics of the material (steel, duraluminium, composite), especially an assessment of the dynamics of fall of the goals has been made and the results are listed bellow.

Table No. 4 - Kinetic energy of a falling goal, person 50kg (holds

Table No. 5 - Kinetic energy of a falling goal, person 50kg (quits holding)

Table No. 6 - Kinetic energy of a falling goal, person 30 kg (holds

Both tests with a 50 kg person show that the composite goals have the lowest kinetic energy, which only proves the increased safety of their. The test with a 30 person shows that the composite goal does not even lean forward, so it is not possible that the goal falls down. List of reference numerals

1 horizontal beam

2 rear bottom bar 3 vertical bar

4 bottom side bar

A upper corner

B front bottom corner

C rear bottom comer