WO2000009218A1

WO2000009218A1 - Ball, composed of two types of flat equilateral parts

Info

Publication number: WO2000009218A1
Application number: PCT/NL1998/000459
Authority: WO
Inventors: Pieter Huybers
Original assignee: Pieter Huybers
Priority date: 1998-08-12
Filing date: 1998-08-12
Publication date: 2000-02-24
Also published as: AU8753098A

Abstract

Ball (1, 21), composed of flat equilateral parts of a first type (2; 22) and a second type (3; 23), which are identical in terms of each type and where the parts of the first type are triangular, the sides of a triangular part are longer than the sides of a part of the second type, the parts are arranged three-dimensionally around a ball centre in such a way that each side of a triangular part, on either side of an intermediate point (7; 27) on the side, from each end of the side to the intermediate point respectively adjoins one side of another triangular part (2; 22) and one side of a part of the second type (3; 23). The ball is suitable for containing a pressurized medium. The sides of the triangular parts (2; 22) are so much longer than the sides of the parts of the second type (3; 23) that each part of the second type (3; 23) and each of four triangular subsections (8, 9; 28, 29) which are formed between the corners and intermediate points of each triangular part (2; 22) can be circumscribed by substantially identical circles.

Description

Short title: Ball, composed of two types of flat equilateral parts

The invention relates to a ball, composed of flat equilateral parts of a first type and a second type, which are identical in terms of each type and where the parts of the first type are triangular, the sides of a triangular part are longer than the sides of a part of the second type, the parts are arranged three-dimensionally around a ball centre in such a way that each side of a triangular part, on either side of an intermediate point on the side, from each end of the side to the intermediate point respectively adjoins one side of another triangular part and one side of a part of the second type, and the ball is suitable for containing a pressurized medium.

A ball of this type is known from the document which forms German Utility Model DE-U-89 08 027. The known ball comprises twelve equilateral pentagons and twenty equilateral triangles . The sides of the triangles are twice as long as those of the pentagons. This achieves the effect that, by comparison with even earlier balls comprising twelve pentagons and twenty hexagons, the number of seams along which the parts have to be attached to one another is smaller, with the result that the ball can be assembled more quickly and more inexpensively.

In many cases, such as for a ball used in games, it is desirable for the ball to be as close as possible to the shape of a sphere. If the pressure inside the ball is higher than the pressure outside the ball, the parts which form the ball will seek to deform to achieve a maximum volume in order to even out the pressure difference, a (true) sphere providing the smallest pressure difference for a given volume of gas. As a consequence of the deformation, stresses are produced in the material of the originally flat parts of the ball, which stresses are greater for parts, which in the absence of a pressure difference have smaller distances to the centre of the ball by comparison with other parts. Depending on the size and shape of the parts, the differences in stresses within the parts will also increase as the distance from the centre of the ball decreases. Furthermore, if the internal pressure in the ball is increased, the parts will bulge out unevenly, increasing the out-of-roundness of the ball. The unequal material stresses and the irregular shape of the parts after the pressure has risen increase the susceptibility of the ball to wear and, in the case of a football, when a player kicks the ball, will alter the flight of the ball and an effect imparted to the ball depending on where contact is made with the ball. Therefore, the behaviour of the ball as a result of it being kicked or the like is less predictable, which is a drawback particularly for professional players. The ball which is known from the initial DE-U-89 08 027 has the drawback that, if there is no pressure difference, the distance of each triangular part from the centre of the ball is relatively great compared to the distance of each pentagonal part from the centre of the ball, with the result that, if a pressure difference is present, there will be relatively great differences in material stresses and the ball will be deformed to an undesirable extent by comparison with a true sphere, so that its susceptibility to wear is relatively high.

The object of the invention is to eliminate the abovementioned drawbacks.

To this end, the invention provides a ball of the type mentioned in the preamble which is characterized in that the sides of the triangular parts are so much longer than the sides of the parts of the second type that each part of the second type and each of four triangular subsections which are formed between the corners and intermediate points of each triangular part can be circumscribed by substantially identical circles. If the circumscribing circles are equal, then, after the ball has been assembled but in the absence of a pressure difference, the centres of the circles, and consequently the flat parts of the second type and the triangular subsections will be at equal distances from the centre of the ball . As a result, the ball more closely approximates the shape of a sphere circumscribed by the corners of the ball than was previously the case. Furthermore, if the pressure of the medium inside the ball is increased with respect to the pressure outside, differences in stress in the material of the parts which occur will be less pronounced and expansion of the ball towards the shape of a true sphere will be uniform. As a result, the ball is less susceptible to wear and the flight of the ball and the effect imparted to the ball by a player will be more predictable and controllable.

The invention will be explained in more detail below with reference to the appended drawings, in which:

Fig. 1 shows a view of a first embodiment of a ball according to the invention, in the absence of a pressure difference;

Fig. 2 shows a combination of different parts of the ball shown in Fig. 1 in the flat, folded-open state;

Fig. 3 shows a combination similar to that of Fig. 2, with a different orientation of the parts with respect to one another;

Fig. 4 shows an illustration for explaining the dimensions of the different parts of the ball;

Fig. 5 shows the ball shown in Fig. 1 in the folded-open, flat state;

Fig. 6 shows a view of a second embodiment of a ball according to the invention, with a shape similar to that of Fig. 1; and

Fig. 7 shows a view of a third embodiment of a ball according to the invention.

The ball 1 which is shown in Fig. 1 is composed of two types of flat, equilateral parts which are identical in terms of each type and which comprise triangular parts 2 and pentagonal parts 3. The equal sides of the triangular parts 2 are longer than the equal sides of the pentagonal parts 3. One side of a triangular part 2 lies against each side of a pentagonal part 3, one corner of the pentagonal part 3 coinciding with one corner of the adjacent triangular part 2. As a result, a ring of five triangular parts 2 is formed around each pentagonal part 3, adjacent triangular parts 2 of which ring lie partially against one another. Fig. 2 shows an illustration of this, with the parts 2, 3 folded out into a flat plane. The orientation of the triangular parts 2 around the pentagonal part 3 in accordance with Fig. 2 can be referred to as a left-hand orientation. Fig. 3 in that case shows a right-hand orientation of a combination of the parts shown in Fig. 2. For the sake of clarity, in Fig. 1 a combination of the parts 2 , 3 as shown in Fig. 2 is illustrated by lines which are thicker than those delineating the other parts 2 , 3 of the ball 1.

Using the arrangement of the parts 2, 3 which is explained above, it is possible to assemble the ball 1 from twelve pentagonal parts 3 and twenty triangular parts 2. Each corner of a pentagonal part 3 coincides with an intermediate point 7 on one side of a triangular part 2 which lies against the pentagonal part 3. If lines are drawn between the intermediate points 7 of a triangular part 2, as shown by the dashed lines, these lines divide the triangular part 2 into four triangular subsections which comprise one central, equilateral subsection 8 between the intermediate points 7 and three subsections 9 which lie between two intermediate points 7 and one corner of the triangular part 2.

It is assumed that the sides of the pentagonal part 3 have a length a and that the sides of the triangular part 2 have a length b. As explained above, a < b.

DE-U-89 08 027 has disclosed a ball 1 as explained above where a = 0.5 b. This ratio has the drawbacks which were explained in the introduction.

According to the invention, the ratio a/b used is such that both the pentagonal part 3 and each of the triangular subsections 8 and 9 can be circumscribed by the same circle. This is illustrated in Fig. 4, in which a thick solid line delineates a pentagonal part 3 and a dashed line delineates a central triangular subsection 8. The corners of the pentagonal part 3 and of the triangular subsection 8, as shown in Fig. 4, coincide with a common circumscribing circle 10. According to Fig. 4, every other triangular subsection 9 is delimited by one side of the pentagonal part 3, one side of the central subsection 8 and a line 11 which connects the ends of these sides. In Fig. 4, a subsection 9 of this kind is situated to the left of the line 11.

For a ratio a/b = 0.3716, the corners of the pentagonal part 3 and of the triangular subsections 8, 9 all lie on the same circumscribing circle 10. As a result, the centres of the circumscribing circles of all the pentagonal parts 3 and all the triangular subsections 8 and 9 are at the same distances from the centre of the ball 1 shown in Fig. 1. As a result, all the pentagonal parts 3 and all the triangular subsections 8 and 9 are also at equal distances from the centre of the ball. This counteracts the occurrence of considerable differences in stress in the material of the parts if the internal pressure of the ball 1 is increased and also counteracts irregular expansion. Although the abovementioned ratio a/b = 0.3716 is the optimum ratio for the ball 1 shown in Fig. 1, it is possible, in order to allow a practical design of the ball, to select a ratio which lies within a range of from 0.3 to 0.45. Fig. 5 shows all the parts 2 , 3 of the ball 1 shown in Fig. 1 in a folded-open, flat state, comprising a regular arrangement of the twenty triangular parts 2 and the twelve pentagonal parts 3.

The dashed lines shown in Figures 1 to 5 can be considered as fold lines about which the triangular subsections 9 can be folded with respect to a central triangular subsection 8.

However, the fold lines between the triangular subsections 8 and 9 can also be made, as shown for the ball 15 illustrated in Fig. 6, by assembling the triangular parts 2 from separate flat, triangular pieces 18, 19 which are identical to the triangular subsections 8 and 9, respectively, of the ball 1 shown in Fig. 1. For the sake of clarity, in Fig. 6 the pentagonal parts 3 are delineated by heavier lines.

If it is assumed that a circumscribing sphere passing through the corners of the faces of the ball, which is a polyhedron, in accordance with Figures 1 to 6 has a radius of R = 110 mm (which is the dimension for a football of type 6X S) , it is possible to compile the following Table 1 showing the distances d of the parts 3, 8, 9, 18, 19 from the centre of the ball for a ratio of a/b of 0.5 and 0.3716.

TABLE 1

Owing to the fact that the parts 3, 8, 9, 18, 19 of the ball according to the invention are at equal distances from the centre of the ball 1, 15, the ball substantially approximates to the shape of a true sphere, even if the internal pressure is increased, in which case, moreover, the ball will expand more evenly and become worn more uniformly than known balls. Furthermore, the said distances are relatively large, in particular by comparison with known balls (polyhedra) other than that which is known from DE-U-8908027. A major advantage of these characteristics is that, if the ball is a football, the flight and an effect imparted to the ball can be predicted and controlled more easily.

Fig. 7 shows a third embodiment of a ball 21 according to the invention which, in accordance with the principle explained above, is composed of eight triangular parts 22 and six square parts 23. The square parts 23 determine intermediate points 27 on the sides of the triangular parts 22. It is possible to draw lines between the intermediate point 27 of each triangular part 22, which lines, in this case too, may be formed by fold lines or seams and divide the triangular part 22 into a central triangular subsection 28 and three triangular subsections 29. An optimum value for the ratio between the length of the sides of the square parts 23 and the (greater) lengths of the sides of the triangular parts 22 is 0.4226. For a practical design of a ball of this kind, it is possible to select a ratio lying within a range of from 0.3 to 0.45.

Claims

1. Ball (1; 21), composed of flat equilateral parts of a first type (2; 22) and a second type (3; 23), which are identical in terms of each type and where the parts of the first type are triangular, the sides of a triangular part are longer than the sides of a part of the second type, the parts are arranged three-dimensionally around a ball centre in such a way that each side of a triangular part, on either side of an intermediate point (7; 27) on the side, from each end of the side to the intermediate point respectively adjoins one side of another triangular part (2; 22) and one side of a part of the second type (3; 23) , and the ball is suitable for containing a pressurized medium, characterized in that the sides of the triangular parts (2; 22) are so much longer than the sides of the parts of the second type (3; 23) that each part of the second type and each of four triangular subsections (8, 9 ; 28, 29) which are formed between the corners and intermediate points (7; 27) of each triangular part can be circumscribed by substantially identical circles.

2. Ball according to claim 1, characterized in that a ratio (a/b) between the length (a) of the side of a part of the second type (3; 23) and the length (b) of the side of a triangular part (2; 22) lies within a range of from 0.3 to 0.45.

3. Ball according to claim 2, characterized in that parts of the second type are pentagonal parts (3) and the ratio is 0.37.

4. Ball according to claim 2, characterized in that parts of the second type are square parts (23) and the ratio is 0.42.

5. Ball according to one of the preceding claims, characterized in that each triangular part (2; 22) is composed of four flat triangular pieces which form the subsections (8, 9; 28, 29) .