GB2296447A - Golf balls with isodiametrical dimples - Google Patents

Abstract

A golf ball has in its spherical surface a plurality of dimples, in which each dimple has the shape, when viewed from above, of a regular isodiametrical figure with an odd number of sides and arcuate apices, and wherein dimples of two or more of said isodiametrical shapes are present in said spherical surface. Preferably, the two or more, e g three, isodiametrical shapes are selected from three-, five-, seven-, nine-, eleven- and thirteen-sided shapes. <IMAGE>

Description

GOLF BALLS WITH ISODIAMETRICAL DIMPLES This invention relates to golf balls with isodiametrical dimples.

It has been known for many years to provide a golf ball with a plurality (multiplicity) of dimples in order to optimise the aerodynamic properties of the balls. Such dimples usually are circular in plan view although polygonal shapes have been proposed, such as triangular, rectangular, pentagonal and hexagonal shapes.

The rules laid down by the governing bodies of the game require that golf balls should behave relatively uniformly from an aerodynamic point of view while the requirements of the golfer also place great emphasis on increased distance to be achieved by reducing the drag force on the ball during flight. Golf ball dimple patterns are of the most profound importance in meeting these requirements both in terms of dimple shape and dimple pattern arrangement.

The use of circular dimples imposes undesirable constrains on surface coverage and on maintaining the optimum relationship between adjacent dimples for reducing the drag force acting on the ball to a minimum, but constant diameter is a desirable feature in creating uniformity in aerodynamic behaviour.

It has been found that dimples which are non-circular but isodiametrical in plan view can not only provide far greater efficiency of surface coverage but also result in improved aerodynamic properties.

In our UK Patent Specification No. GB 2242363B there are described golf balls having in their spherical surfaces a plurality of dimples, in which each dimple has the shape, when viewed from above, of a regular isodiametrical figure having an odd number of sides and arcuate apices.

It is now found that an advantageous species of the dimpled golf balls defined in that patent specification comprises a golf ball having in its spherical surface dimples of two or more isodiametrical shapes.

Employment of dimples of more than one isodiametrical shape in a golf ball surface provides greater latitude for varying and improving playing characteristics of the ball. One advantage is that a higher level of coverage of the ball surface with dimples can be achieved. A further advantage comprises greater ability to confer desired aerodynamic properties and other playing characteristics on a ball by selection of isodiametrical dimple combinations and their relationship in a dimple pattern in the ball surface.

Typical examples of suitable non-circle isodiametrical figures for the dimple shapes are three-sided, five-sided, seven-sided, nine-sided, elevensided and thirteen-sided figures. Isodiametrical figures having a higher number of sides could be employed although as the number of sides is increased above about thirteen the dimple shapes would bear an increasing resemblance to a circle in appearance.

The sides of an isodiametrical figure have equal curvature and the apices at the junctures of adjacent sides are arcuate. The sides and arcuate apices may be created by arcs of circles centred at the apices of an imaginary corresponding regular polygon (for example, a three-sided isodiametrical figure corresponding to an equilateral triangle, a five-sided isodiametrical figure corresponding to a regular pentagon, etc).

The golf ball surface may comprise dimples of two, three or more different isodiametrical shapes.

The isodiametrical dimples in the golf ball surface may be all of the same diametrical size or may be of two or more diametrical sizes.

Preferably, the dimples are arranged in the spherical surface of the ball in a uniform repeating pattern.

The pattern conveniently may be defined by projecting the edges of a regular polyhedron on to the spherical surface of the ball. Examples of regular polyhedra for the dimple pattern include the cube, the octahedron, the dodecahedron, the icosahedron and the icosi-dodecahedron.

The present invention will be illustrated, merely by way of example, in the following description and with reference to the accompanying drawings, in which: Figs 1. to 4 show, diagrammatically, examples of isodiametrical dimple shapes and means for deriving the shapes geometrically.

In particular: Fig. 1 illustrates a three-sided isodiametrical shape; Fig. 2 illustrates a five-sided isodiametrical shape; Fig. 3 illustrates a seven-sided isodiametrical shape; Fig. 4 illustrates a nine-sided isodiametrical shape; Figs. 5 and 6 are schematic views of golf balls having in the spherical golf ball surface a plurality of isodiametrical dimples of more than one isodiametrical shape arranged in repeating patterns defined by regular polyhedra.

In particular: Fig. 5 shows an assembly of three-sided, five-sided and seven sided isodiametrical dimples arranged in a dodecahedral pattern; Fig. 6 shows an assembly of three-sided, five-sided and seven sided isodiametrical dimples arranged in an icosahedral pattern.

In Fig. 1 there is shown an isodiametrical dimple shape having three curved sides S11, S12, S13 and arcuate apices All, A12, A13 at the junctures of adjacent sides. The shape may be derived geometrically from a nominal equilateral triangle with apices T1, T2, T3, as follows. A circle Cii is projected with its centre at apex T1 and having a radius R1 which is greater than the largest internal dimension of the nominal triangle. Two further circles are then projected having the same radius R' but with centres at apex T2 and apex T3 respectively. Curved side S11 is provided by an arc of the circle Cii and, similarly, curved sides S12 and S13 respectively are provided by arcs of the circles with centres at T2 and T3.A minor circle c13 is then projected with its centre at apex T3 and having a radius r1 such that the circle c13 is tangential to both the circle Cli and the circle of radius R1 with its centre at apex T2. The arc of minor circle c 3 between the tangential points provides the arcuate apex A13 at the juncture of the curved sides S11 and S12. Two further minor circles are then projected having the same radius r1 but with centres at the triangle apices Ti and T2, thereby providing, analogously to circle c13, the arcuate apices All and Awl 2 respectively.

In Fig. 2 there is shown an isodiametrical dimple shape having five curved sides S21, S22, S23, S24, S25 and arcuate apices A21, A22, A23, A24, A25 at the junctures of adjacent sides. The shape may be derived geometrically from a nominal regular pentagon with apices P1 to P5, analogously to the procedure described with reference to Fig. 1, as follows.

A circle C2l is projected with its centre at apex P1 and having a radius R2 which is greater than the largest internal dimension of the nominal pentagon, and four further circles are projected having the same radius R2 but with centres at apices P2 to P5 respectively. Curved side S21 is provided by an arc of the circle C21, and curved sides S22 to S25 are provided by arcs of the circles with centres at P2 to P5 respectively. A minor circle c24 is projected with its centre at apex P4 and having a radius r2 such that the circle c24 is tangential to both the circle C2i and the circle of radius R2 with its centre at apex P2. The arc of minor circle c24 between the tangential points provides the arcuate apex A24 at the juncture of the curved sides S21 and S22.Four further minor circles are projected having the same radius r2 but with centres at the pentagon apices P5, P1, P2 and P3, thereby providing the arcuate apices A25, A21, A22 and A23 respectively.

In Fig. 3 there is shown an isodiametrical dimple shape having seven curved sides S31, S32, S33, S34, S35, S36, S37 and arcuate apices A31, A32, A33, A34, A35, A36, A37 at the junctures of adjacent sides. The shape may be derived geometrically from a nominal regular heptagon with apices H1 to H7, analogously to the procedure described with reference to Fig. 1 or 2. In this analogous procedure, with reference to Fig. 3, C3i represents a projected circle with its centre at apex H1 and having the radius R3, an arc of which provides the curved side S31, and c35 represents a projected minor circle with its centre at apex H5 and having the radius r3, the tangential arc of which provides the arcuate apex A35.

In Fig. 4 there is shown an isodiametrical dimple shape having nine curved sides S41 to S49 and arcuate apices A41 to A49 at the junctures of adjacent sides. The shape may be derived geometrically from a nominal regular nonagon with apices N1 to N9, analogously to the procedure described with reference to Fig. 1 or 2. In this analogous procedure, with reference to Fig. 4, C4i represents a projected circle with its centre at apex N1 and having the radius R4, an arc of which provides the curved side S41, and c47 represents a projected minor circle with its centre at apex N7 and having the radius r4, the tangential arc of which provides the arcuate apex A47.

Isodiametrical dimple shapes having more than nine curved sides may be derived geometrically from the corresponding nominal regular polygon by an analogous procedure.

In Fig. 5, a golf ball 130 is provided with a plurality of isodiametrical dimples of three different kinds, namely: three-sided dimples 131, five-sided dimples 132 and seven-sided dimples 133. Each dimple has equal curved sides joined by arcuate apices. The dimples are arranged in a dodecahedral pattern as indicated by broken lines 134.

In Fig. 6, a golf ball 140 is provided with a plurality of isodiametrical dimples of three different kinds, namely: three-sided dimples 141, five-sided dimples 142 and seven-sided dimples 143. Each dimple has equal curved sides joined by arcuate apices. The dimples are arranged in an icosahedral pattern as indicated by broken lines 144.

It is to be understood that in Figs. 5 and 6 the isodiametrical dimples have curved sides and arcuate apices as are indicated more clearly in Figs.

1 to 4.

It is to be understood also that the embodiments shown in the drawings are solely by way of example and that there is a multitude of other embodiments falling within the invention as defined and described herein.

For instance, a golf ball in accordance with the invention may well have dimples of only two different isodiametrical shapes or of more than three different isodiametrical shapes, and/or may well have dimples arranged in a variety of patterns apart from dodecahedral and icosahedral patterns.

Furthermore it is to be understood that the isodiametrical shapes may be produced by means alternative to the geometrical procedure described with reference to Figs. 1 to 4.

Claims (18)

CLAIMS:

1. A golf ball having in its spherical surface a plurality of dimples, in which each dimple has the shape, when viewed from above, of a regular isodiametrical figure with an odd number of sides and arcuate apices, and wherein dimples of two or more of said isodiametrical shapes are present in said spherical surface.

2. A golf ball according to Claim 1, in which the said dimples comprise those whose regular isodiametrical figure is a three-sided figure.

3. A golf ball according to Claim 1 or 2, in which the said dimples comprise those whose regular isodiametrical figure is a five-sided figure.

4. A golf ball according to any of the preceding Claims, in which the said dimples comprise those whose regular isodiametrical figure is a seven-sided figure.

5. A golf ball according to any of the preceding Claims, in which the said dimples comprise those whose regular isodiametrical figure is a nine-sided figure.

6. A golf ball according to any of the preceding Claims, in which the said dimples comprise those whose regular isodiametrical figure is an elevensided figure.

7. A golf ball according to any of the preceding Claims, in which the said dimples comprise those whose regular isodiametrical figure is a thirteensided figure.

8. A golf ball according to any of the preceding Claims, comprising dimples of three different isodiametrical shapes.

9. A golf ball according to any of the preceding Claims, in which the said dimples are of more than one diametrical size.

10. A golf ball according to any of Claims 1 to 8, in which said dimples are all of the same diametrical size.

11. A golf ball according to any of the preceding Claims, in which the dimples are arranged in the spherical surface of the ball in a uniform repeating pattern.

12. A golf ball according to Claim 11, in which the uniform repeating pattern is defined by projecting on to said spherical surface the edges of a regular polyhedron.

13. A golf ball according to Claim 12, in which the polyhedron is a cube.

14. A golf ball according to Claim 12, in which the polyhedron is a regular octahedron.

15. A golf ball according to Claim 12, in which the polyhedron is a regular dodecahedron.

16. A golf ball according to Claim 12, in which the polyhedron is a regular icosahed ron.

17. A golf ball according to Claim 12, in which the polyhedron is a regular icosi-dodecahedron.

18. A golf ball, substantially as hereinbefore described, with reference to and as illustrated by the accompanying drawings.