Golf ball dimple profile

Abstract

The present invention concerns a golf ball having dimples with a cross-sectional profile comprising a conical top portion and a bottom portion. More particularly, the profiles of the present invention are defined by three independent parameters: dimple diameter (DD), edge angle (ΦEDGE), and saucer ratio (Sr). These parameters fully define the dimple shape and allow for greater flexibility in constructing a dimple profile versus conventional spherical dimples. The dimples optionally have a transition surface connecting the conical top portion to the land area of the golf ball and/or a transition surface connecting the conical top portion to the bottom portion.

Description

FIELD OF THE INVENTION

The present invention relates to a golf ball, and more particularly, to the cross-sectional profile of dimples on the surface of a golf ball.

BACKGROUND OF THE INVENTION

Golf balls were originally made with smooth outer surfaces. In the late nineteenth century, players observed that the guttie golf balls traveled further as they got older and more gouged up. The players then began to roughen the surface of new golf balls with a hammer to increase flight distance. Manufacturers soon caught on and began molding non-smooth outer surfaces on golf balls.

By the mid 1900's, almost every golf ball being made had 336 dimples arranged in an octahedral pattern. Generally, these balls had about 60 percent of their outer surface covered by dimples. Over time, improvements in ball performance were developed by utilizing different dimple patterns. In 1983, for instance, Titleist introduced the TITLEIST 384, which had 384 dimples that were arranged in an icosahedral pattern. About 76 percent of its outer surface was covered with dimples. Today's dimpled golf balls travel nearly two times farther than a similar ball without dimples.

The dimples on a golf ball are important in reducing drag and increasing lift. Drag is the air resistance that acts on the golf ball in the opposite direction from the ball flight direction. As the ball travels through the air, the air surrounding the ball has different velocities and, thus, different pressures. The air exerts maximum pressure at the stagnation point on the front of the ball. The air then flows over the sides of the ball and has increased velocity and reduced pressure. At some point it separates from the surface of the ball, leaving a large turbulent flow area called the wake that has low pressure. The difference in the high pressure in front of the ball and the low pressure behind the ball slows the ball down. This is the primary source of drag for a golf ball.

The dimples on the ball create a turbulent boundary layer around the ball, i.e., the air in a thin layer adjacent to the ball flows in a turbulent manner. The turbulence energizes the boundary layer and helps it stay attached further around the ball to reduce the area of the wake. This greatly increases the pressure behind the ball and substantially reduces the drag.

Lift is the upward force on the ball that is created from a difference in pressure on the top of the ball to the bottom of the ball. The difference in pressure is created by a warpage in the air flow resulting from the ball's back spin. Due to the back spin, the top of the ball moves with the air flow, which delays the separation to a point further aft. Conversely, the bottom of the ball moves against the air flow, moving the separation point forward. This asymmetrical separation creates an arch in the flow pattern, requiring the air over the top of the ball to move faster, and thus have lower pressure than the air underneath the ball.

Almost every golf ball manufacturer researches dimple patterns in order to increase the distance traveled by a golf ball. A high degree of dimple coverage is beneficial to flight distance, but only if the dimples are of a reasonable size. Dimple coverage gained by filling spaces with tiny dimples is not very effective, since tiny dimples are not good turbulence generators.

In addition to researching dimple pattern and size, golf ball manufacturers also study the effect of dimple shape, volume, and cross-section on overall flight performance of the ball. Conventional dimples are the shape of a section of a sphere. These profiles rely on essentially two independent parameters to fully define the dimple shape: diameter and depth (chordal or surface). Edge angle is often discussed when describing spherical dimple profiles but is not independent of diameter and depth. However, it is more commonly used in place of depth when describing spherical dimple shapes. Spherical dimples have a volume ratio (V_R) around 0.5 (see below for definition). For purposes of aerodynamic performance, it is desirable to have additional control of dimple shape by varying edge angle independently from dimple diameter and depth. This has been achieved in a number of ways. Examples include “dual radius,” dimple within a dimple, and catenary dimple profiles. These cross-sections allow for more control over spherical cross-sections and allow one to vary V_R to optimize aerodynamic performance. With the exception of catenary profiles, the mathematical descriptions are cumbersome or do not result in smooth continuous dimple profiles.

Several patents relate golf ball manufacturers' attempts to construct improved non-spherical golf ball dimples. U.S. Pat. No. 7,094,162 discloses a golf ball dimple comprising a top truncated cone part and a bottom bowl-shaped part. However, this dimple has a sharp demarcation line between these two portions of the dimples which shows a great distinction between them. U.S. Pat. Nos. 4,560,168, 4,970,747, 5,016,887, and 6,454,668 mention dimples having a frusto-conical or truncated cone portion but do not combine that with a bottom spherical portion.

Thus, there still remains a need to construct dimples with a conical portion having a smooth continuous profile and improved aerodynamic performance.

SUMMARY OF THE INVENTION

In one embodiment, the present invention is directed to a golf ball dimple comprising a top conical sidewall and a bottom portion, and having a saucer ratio (S_r), defined as the ratio of the bottom portion diameter (D_S) to the dimple diameter (D_D), of from about 0.05 to about 0.75. The bottom portion is defined by a function rotated about a central axis, the function being selected from the group consisting of polynomial, trigonometric, hyperbolic, exponential functions, and the superposition of two or more thereof. Excluded are linear functions and functions that result in a cone or sphere.

In another embodiment, the present invention is directed to a golf ball having a generally spherical surface and comprising a plurality of dimples separated by a land area formed on the surface. At least a portion of the dimples consist of a top conical sidewall and a bottom portion and have a saucer ratio (S_r), defined as the ratio of the bottom portion diameter (D_S) to the dimple diameter (D_D), of from about 0.05 to about 0.75. The bottom portion is defined by a function rotated about a central axis, the function being selected from the group consisting of polynomial, trigonometric, hyperbolic, exponential functions, and the superposition of two or more thereof. Excluded are linear functions and functions that result in a cone or sphere.

In another embodiment, the present invention is directed to golf ball having a generally spherical surface and comprising a plurality of dimples separated by a land area formed on the surface, at least a portion of the dimples being conical-protruding bottom dimples comprising a top conical sidewall, a protruding bottom portion, and an optional transition surface that connects the top conical sidewall to the land area. The protruding bottom portion consists of a protruding conical sidewall and a protruding spherical cap. The conical-protruding bottom dimples have a saucer ratio, defined as the ratio of the protruding bottom portion diameter (D_S) to the dimple diameter (D_D), of from about 0.05 to about 0.75. The conical-protruding bottom dimples have a protrusion saucer ratio, defined as the ratio of the protruding spherical cap diameter (D_PS) to the protruding bottom portion diameter (D_S), of from about 0.05 to about 0.75.

In a particular aspect of the embodiments disclosed herein, dimples of the present invention have an edge angle (Φ_EDGE) defined by1.33(S_r)²−0.39(S_r)+10.40≤Φ_EDGE≤2.85(S_r)²−1.12(S_r)+13.49.

In another particular aspect of the embodiments disclosed herein, dimples of the present invention have a chord depth (d_CHORD) defined by0.0009(S_r)²−0.0035(S_r)+0.0062≤d_CHORD≤0.0030(S_r)²−0.0069(S_r)+0.0113.

In another particular aspect of the embodiments disclosed herein, dimples of the present invention have a transition surface that connects the top conical sidewall to the land area, and have a transition ratio (T_r) of from 0.02 to 0.50, where the transition ratio (T_r) is defined by the equation T_r=1−(D_T/D_D), where D_D is the dimple diameter and D_T is the diameter at the point of intersection between the transition surface and the top conical sidewall. In a further particular aspect of this embodiment, the transition surface is defined by a circular arc rotated about a central axis, or is defined by a linear function rotated about a central axis.

In another particular aspect of the embodiments disclosed herein, dimples of the present invention have a secondary transition surface that connects the top conical sidewall to the bottom portion.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings which form a part of the specification and are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views:

FIG. 1 is a schematic diagram illustrating a dimple profile according to this invention;

FIG. 2 is a schematic diagram illustrating a method for measuring the edge angle of a dimple;

FIG. 3 is a schematic diagram illustrating a method for measuring the chord depth of a dimple;

FIG. 4 is a schematic diagram illustrating another dimple profile according to this invention;

FIG. 5 is a schematic diagram illustrating another dimple profile according to this invention;

FIG. 6 shows a dimple cross-sectional shape according to an embodiment of the present invention;

FIG. 7 shows a dimple cross-sectional shape according to another embodiment of the present invention;

FIG. 8 shows a dimple cross-sectional shape according to another embodiment of the present invention;

FIG. 9A is a schematic diagram illustrating a dimple profile according to an embodiment of the present invention;

FIG. 9B is a schematic diagram illustrating a dimple profile according to an embodiment of the present invention;

FIG. 9C is a schematic diagram illustrating two dimple profiles according to embodiments of the present invention;

FIG. 10 is a graphical representation of the relationship between saucer ratio and edge angle according to an embodiment of the present invention;

FIG. 11 is a graphical representation of the relationship between saucer ratio and chord depth according to an embodiment of the present invention; and

FIG. 12 is a graphical representation of the relationship between dimple volume and plan shape area according to an embodiment of the present invention.

FIG. 13 is a schematic diagram illustrating a dimple profile according to an embodiment of the present invention.

FIG. 14 is a schematic diagram illustrating a dimple profile according to an embodiment of the present invention.

FIG. 15 is a schematic diagram illustrating a dimple profile according to an embodiment of the present invention.

FIG. 16 is a schematic diagram illustrating a method for measuring the edge angle of a dimple having a transition surface that connects the top conical sidewall to the land area.

FIG. 17 is a schematic diagram illustrating a dimple profile according to an embodiment of the present invention.

FIG. 18 is a schematic diagram illustrating a dimple profile according to an embodiment of the present invention.

FIG. 19 is a schematic diagram illustrating a dimple profile according to an embodiment of the present invention.

FIG. 20 is a schematic diagram illustrating a dimple profile according to an embodiment of the present invention.

DETAILED DESCRIPTION

The present invention concerns a golf ball with dimples comprising a top conical sidewall and a non-conical bottom portion. In one embodiment, the bottom portion is a spherical cap with a prescribed point of tangency to the conical sidewall. In another embodiment, the bottom portion is defined by a function selected from the group consisting of polynomial, trigonometric, hyperbolic, exponential functions, and the superposition of two or more thereof, excluding linear functions and functions that result in a cone or sphere when rotated about a central axis. Functions resulting from the superposition of two or more different functions, and the use thereof for dimple profiles, are further disclosed, for example, in U.S. Patent Application Publication No. 2012/0165130 to Madson et al. and U.S. Patent Application Publication No. 2013/0172125 to Nardacci et al., the entire disclosures of which are hereby incorporated herein by reference. In another embodiment, the bottom portion is a protrusion consisting of a protruding conical sidewall and a protruding spherical cap. Dimples of the present comprising a top conical sidewall and a protruding bottom portion are referred to herein as conical-protruding bottom dimples.

The profiles of the present invention are further defined by three parameters: dimple diameter (D_D), edge angle (Φ_EDGE), and saucer ratio (S_r). These parameters further define the dimple shape and allow for greater flexibility in constructing a dimple profile versus conventional spherical dimples. Further, conical dimples provide a unique dimple cross-section which is visually distinct.

FIG. 1 is a cross-sectional view illustrating a dimple 10 on a golf ball 20 having an outer spherical surface with a phantom portion 30 and an undimpled land area 40. A rotational axis 50 vertically traverses the center of dimple 10. The dimple 10 comprises a top conical edge 12 (an edge with no radius) and a bottom spherical cap 14. More particularly, the dimple diameter (D_D) that defines the phantom spherical outer surface 30 acts as the base of a right circular cone. From that base, a conical edge 12 forms the top portion of the dimple 10. The bottom of dimple 10 is defined by a spherical cap 14. The diameter of the bottom spherical cap 14 is also referred to as the saucer diameter (D_S) and is preferably concentric with the dimple diameter (D_D).

In one innovative aspect of the present invention, dimple 10 has a defined tangent point 16, wherein the straight conical edge 12 meets the spherical bottom cap 14. The tangent point 16 is determined by the saucer diameter (D_S) and the edge angle (Φ_EDGE) of the dimple, which is defined below. At the defined tangent point 16, the difference in the slope of the straight conical edge 12 and the slope of the spherical arcuate cap 14, which is the slope of a line tangent to cap 14 at point 16, will be less than 2°, preferably less than 1°, and more preferably the slopes will be about equal at that connection to ensure tangency at that location.

The shape of dimple 10 can be modified by adjusting three parameters. The first of these parameters is the dimple diameter (D_D), and the second of these parameters is the saucer ratio (S_r), which is defined by equation (1):S_r=D_S/D_D  (1)If S_r=0, then the dimple would be a cone with no spherical bottom radius, and if S_r=1, then the dimple is spherical. For the purpose of this invention, the value of S_r preferably falls in the range of about 0.05≤S_r≤0.75, preferably about 0.10≤S_r≤0.70, more preferably about 0.15≤S_r≤0.65, more preferably about 0.20≤S_r≤0.60, more preferably about 0.25≤S_r≤0.55, more preferably about 0.30≤S_r≤0.50, and more preferably about 0.35≤S_r≤0.45. If S_r is less than 0.05 then the manufacturing of dimple 10 becomes more difficult, and the sharp point at the bottom of the dimple can diminish the aerodynamic qualities of golf ball 20 and is susceptible to paint flooding. If S_r is greater than 0.75 then it too closely resembles the shape of a spherical dimple and the qualities of conical dimples to adjust the flight performance of the golf ball 20 is diminished.

The third parameter to adjust the dimple shape can either be the edge angle (Φ_EDGE) or the chord depth (d_CHORD). Both parameters are dependent upon one another. The edge angle (Φ_EDGE) is defined as the angle between a first tangent line T1 and a second tangent line T2, which can be measured as shown in FIG. 2. Generally, it may be difficult to define and measure an edge angle (Φ_EDGE) due to the indistinct nature of the boundary dividing the dimple 10 from the ball's undisturbed land surface 40. Due to the effects of the paint and/or the dimple design itself, the junction between the land surface and dimple is not a sharp corner and is therefore indistinct. This can make the measurement of a dimple's edge angle (Φ_EDGE) and radius (R_D) somewhat ambiguous. To resolve this problem, the edge angle and radius of a dimple on a finished golf ball are measured according to the method shown in FIG. 2. FIG. 2 shows a dimple half-profile, extending from the dimple centerline to the land surface outside of the dimple. A ball phantom surface 30 is drawn above the dimple as a continuation of the land surface. A first line T1 is drawn as a line that is tangent to the dimple sidewall at a point that is spaced 0.003 inches radially inward from the phantom surface 30. In cases where the point on the dimple sidewall that is spaced 0.003 inches radially inward from the phantom surface 30 lies on a conical sidewall, the first line T1 is collinear with the conical sidewall. T1 intersects the phantom surface 30 at a point P1, which defines a nominal dimple edge position. A second line T2, tangent to the phantom surface 30 at point P1, is drawn. The edge angle is the angle between T1 and T2. The point P1 can be used to measure the dimple radius (R_D), calculated as the distance from P1 to the rotational axis of the dimple.

FIG. 10 is a graphical representation of the relationship between saucer ratio and edge angle according to an embodiment of the present invention. In a particular embodiment, dimples of the present invention have an edge angle (Φ_EDGE) defined by1.33(S_r)²−0.39(S_r)+10.40≤Φ_EDGE≤2.85(S_r)²−1.12(S_r)+13.49.

FIG. 3 illustrates a method of measuring the chord depth (d_CHORD). As illustrated therein, the chord depth (d_CHORD) is measured as the distance from the theoretical cone base, denoted by the line marking dimple diameter (D_D), to the bottom of the dimple.

With a desired chord depth (d_CHORD), the edge angle (Φ_EDGE) can be calculated by equation (2):Φ_EDGE=Φ_CAPΦ_CHORD  (2)Where: Φ_CAP=sin⁻¹(D_D/D_B)

Φ_CHORD=tan⁻¹{(d_CHORD−d_SAUCER)÷(R_D−R_S)}

And: D_B=Diameter of the golf ball

R_D=Dimple radius, (D_D/2)

R_S=Saucer radius, (D_S/2)

d_SAUCER=saucer depth=r_APEX−√{square root over ((r_APEX²−R_S²))}

r_APEX=R_S/sin(Φ_CHORD)

Alternatively, if the edge angle (Φ_EDGE) is known then the chord depth (d_CHORD) can be calculated by equation (3):d_CHORD=d_SAUCER+(R_D−R_S)×tan[Φ_EDGE−{cos⁻¹(D_D/D_B)}]  (3)

FIG. 11 is a graphical representation of the relationship between saucer ratio and chord depth according to an embodiment of the present invention. In a particular embodiment, dimples of the present invention have a chord depth (d_CHORD) defined by0.0009(S_r)²−0.0035(S_r)+0.0062≤d_CHORD≤0.0030(S_r)²−0.0069(S_r)+0.0113.

The dimple 10 also has a volume ratio (V_R), which is the ratio between the dimple volume (V_D) and the theoretical cylindrical volume (V_C). In other words, V_R=V_D: V_C. The volume ratio (V_R) preferably falls in the range of about ⅓≤R_R≤½. The dimple volume (V_D) can be calculated by equation (4):V_D=[⅓πR_D²(d_CHORD)]−[⅓πR_S²(d_SAUCER)]+[π(d_SAUCER)(3R_S²+d_SAUCER²)÷6]  (4)

The theoretical cylindrical volume (V_C) is the volume of a theoretical cylinder having a base diameter equal to that of the dimple diameter (D_D) and a height equal to the chord depth (d_CHORD) such that V_C is calculated by equation (5):V_C=πR_D²(d_CHORD)  (5)

FIG. 12 is a graphical representation of the relationship between dimple volume and plan shape area according to an embodiment of the present invention. For purposes of the present invention, the plan shape area is calculated as π(D_D/2)². In a particular embodiment, dimples produced in accordance with the present invention have a plan shape area and dimple volume within a range having a lower limit and an upper limit selected from the values within region 1 of FIG. 12. In another embodiment, dimples produced in accordance with the present invention have a plan shape area and dimple volume within a range having a lower limit and an upper limit selected from the values within region 2 of FIG. 12.

FIGS. 4 and 5 are illustrative examples of different dimple shapes 10′ and 10″, respectively, in accordance with the present invention, wherein the saucer ratio (S_r) is changed but the edge angle (Φ_EDGE) remains constant at a value of about 16°. More particularly, in FIG. 4, dimple 10′ has a saucer ratio (S_r) of about 0.05, a chord depth (d_CHORD) of about 0.0152 in., and a volume ratio (V_R) of about 0.341. By way of comparison, FIG. 5 illustrates a dimple 10″ with a saucer ratio (S_r) of about 0.75, a chord depth (d_CHORD) of about 0.0097 in, and a volume ratio (V_R) of about 0.403.

FIG. 9A is an illustrative example of dimple shape 60, according to an embodiment of the present invention, having a top conical edge and a bottom portion defined by a polynomial function. Dimple shape 60 has a dimple diameter (D_d), a saucer diameter (Ds₁), an edge angle (θ₁), and a chord depth (d_c1). The saucer ratio of dimple shape 60, defined by D_S1/D_d, of dimple shape 60 is about 0.05.

FIG. 9B is an illustrative example of dimple shape 65, according to an embodiment of the present invention, having a top conical edge and a bottom portion defined by a polynomial function. Dimple shape 65 has a dimple diameter (D_d), a saucer diameter (Ds₂), an edge angle (θ₂), and a chord depth (d_c2). The saucer ratio of dimple shape 65, defined by D_S2/D_d, of dimple shape 65 is about 0.75.

FIG. 9C shows an overlay of the dimple shape 60 of FIG. 9A and the dimple shape 65 of FIG. 9B to illustrate the effect that a change in saucer ratio may have on edge angle and chord depth, particularly showing that θ₁<θ₂ and d_c1>d_c2.

FIGS. 6-8 show various dimple cross-sectional shapes having a base portion defined by a simple plane curve, such as a polynomial, trigonometric, hyperbolic, or exponential function. To define the base portion according to such functions, it should be taken into account that the chord plane of the dimple represents y=0 and the vertical axis in the center of the dimple represents x=0.

FIG. 6 illustrates a dimple profile resulting from a combination of a conical top portion and a base portion defined by a polynomial function: y(x)=ax²+bx+c. The profile is then rotated 360° about the Y (vertical) axis to define the dimple surface. The highest order of the polynomial will dictate the overall shape of the base curve and the constants a, b, and c are used to modify the curvature intensity of the base curve. While FIG. 6 illustrates a base portion defined by a 2^nd order polynomial, it should be understood that a polynomial of any order and containing any number terms may be used.

FIG. 7 illustrates a dimple profile resulting from a combination of a conical top portion and a base portion defined by a trigonometric function: y(x)=a sin(bxⁿ). The profile is then rotated 360° about the Y (vertical) axis to define the dimple surface. While FIG. 7 illustrates a base portion defined by a sine function, it should be understood that any trigonometric or hyperbolic function may be used.

FIG. 8 illustrates a dimple profile resulting from a combination of a conical top portion and a base portion defined by an exponential function: y(x)=ce^xn. The profile is then rotated 360° about the Y (vertical) axis to define the dimple surface. While FIG. 8 illustrates a base portion defined by a specific exponential function, it should be understood that any exponential function may be used.

In another embodiment, the present invention is directed to conical-protruding bottom dimples comprising a top conical sidewall and a protruding bottom portion. In a particular aspect of this embodiment, the protruding bottom portion consists of a protruding conical sidewall and a protruding spherical cap. In a further particular aspect of this embodiment, no point of the protruding bottom portion extends beyond the phantom surface of the ball. In another further particular aspect of this embodiment, no point of the protruding bottom portion extends beyond the chord plane of the dimple.

The diameter of the protruding spherical cap is referred to herein as the protruding spherical cap diameter (D_PS). The diameter of the protruding bottom portion (D_PB) is referred to herein as the protruding bottom portion diameter. The ratio of the protruding spherical cap diameter (D_PS) to the protruding bottom portion diameter (D_PB) is referred to herein as the protrusion saucer ratio, and is preferably from 0.05 to 0.75. The ratio of the protruding bottom portion diameter (D_PB) to the dimple diameter (D_D) is referred to herein as the protrusion bottom portion ratio, and is preferably from 0.05 to 0.75. In a particular aspect of this embodiment, the difference between the protrusion saucer ratio and the protrusion bottom portion ratio is 0.05 or less. In another particular aspect of this embodiment, the difference between the protrusion saucer ratio and the protrusion bottom portion ratio is greater than 0.05.

Conical-protruding bottom dimples of the present invention have a protrusion angle θ_P between the chord plane of the dimple and the protruding conical sidewall of the protruding bottom portion. In a particular embodiment, conical-protruding bottom dimples of the present invention have a protrusion angle θ_P of from 10° to 30°. In a particular aspect of this embodiment, the difference between the edge angle θ_EDGE of the dimple and the protrusion angle θ_P of the dimple is 1° or less. In another particular aspect of this embodiment, the difference between the edge angle θ_EDGE of the dimple and the protrusion angle θ_P of the dimple is greater than 1°.

Referring now to FIGS. 19 and 20, conical-protruding bottom dimples of the present invention include a top conical sidewall 12 and a protruding bottom portion 114. In FIG. 19, the top conical sidewall 12 intersects with the protruding bottom portion 114 at a defined point of intersection 16. In FIG. 20, top conical sidewall 12 intersects with a transition surface 222 between the top conical sidewall 12 and the protruding bottom portion 114 at a defined point of intersection 16. The protruding bottom portion 114 consists of a protruding conical sidewall 112 and a protruding spherical cap 118. The protruding conical sidewall 112 intersects with the protruding spherical cap 118 at a defined point of intersection 116. The dimple diameter (D_D), transition diameter (D_T), protruding bottom portion diameter (D_PB), protruding spherical cap diameter (D_PS), protrusion angle θ_P, and, additionally, in FIG. 20, secondary transition surface length (L_2T) are identified.

In the particular embodiment illustrated in FIGS. 19 and 20, no point of the protruding bottom portion 114 extends beyond the phantom surface 30 of the ball, and no point of the protruding bottom portion 114 extends beyond the chord plane 120 of the dimple.

In the particular embodiment illustrated in FIG. 19, the dimple has an edge angle Φ_EDGE of about 17.0°, a protrusion angle θ_P of about 25.0°, a protrusion bottom portion ratio (D_PB/D_D) of about 0.25, a transition ratio (1−D_T/D_D) of about 0.08, and a protrusion saucer ratio (D_PS/D_PB) of about 0.20.

In the particular embodiment illustrated in FIG. 20, the dimple has an edge angle Φ_EDGE of about 17.0°, a protrusion angle θ_P of about 25.0°, a dimple diameter (D_D) of about 0.170 inches, a protruding bottom portion diameter (D_PB) of about 0.045 inches, a protruding spherical cap diameter (D_PS) of about 0.009 inches, a transition diameter (D_T) of about 0.156 inches, a secondary transition surface length (L_2T) of about 0.009 inches, a transition ratio (1−D_T/D_D) of about 0.08, and a protrusion saucer ratio (D_PS/D_PB) of about 0.20.

As shown in FIGS. 19 and 20, conical-protruding bottom dimples of the present invention optionally include a transition surface 22 connecting the top conical sidewall 12 to the land area of the ball. The transition surface 22 intersects with the top conical edge 12 at a defined point of intersection 18. The transition surface 22 shown in FIGS. 19 and 20 is defined by a spherical arc.

As shown in FIG. 20, conical-protruding bottom dimples of the present invention optionally include a secondary transition surface 222 connecting the top conical sidewall 12 to the protruding bottom portion 114. The secondary transition surface 222 intersects with the top conical sidewall 12 at a defined point of intersection 16. The secondary transition surface 222 intersects with the protruding bottom portion 114 at a defined point of intersection 216. In FIG. 20, the secondary transition surface 222 is defined by a spherical arc, and the transition surface 22 and the secondary transition surface 222 are opposite in concavity. Transition surfaces are further discussed below.

In a particular aspect of the embodiments disclosed herein, dimples of the present invention include a top conical sidewall, a bottom portion, and a transition surface that connects the top conical sidewall of the dimple to the land area of the ball. The dimples have an overall dimple diameter (D_D), a bottom portion diameter (D_S), and a transition diameter (D_T). The transition diameter is defined herein as the diameter at the point of intersection between the transition surface and the top conical sidewall. The portion of the overall dimple surface that is attributable to the transition surface is expressed by the transition ratio (T_r), which is defined by the equation T_r=1−(D_T/D_D), where D_T is the transition diameter and D_D is the overall dimple diameter. In a further particular aspect of this embodiment, the dimples have a transition ratio (T_r) of from 0.02 to 0.5. In another further particular aspect of this embodiment, the dimples have a saucer ratio (S_r), defined as the ratio of the bottom portion diameter (D_S) to the overall dimple diameter (D_D), of from 0.05 to 0.75. In another further particular aspect of this embodiment, the transition ratio is less than the saucer ratio, or the transition ratio is greater than the saucer ratio, or the transition ratio is equal to the saucer ratio.

The transition surface is defined by a function rotated about a central axis. The function defining the transition surface may result in an indistinct junction between the dimple surface and the land area, including, for example, embodiments wherein the transition surface is defined by a spherical arc. Thus, the process described herein and shown in FIG. 2 for measuring edge angle and dimple radius when the junction between the land area and dimple is not a sharp corner can be used to determine the overall dimple diameter of dimples that include a transition surface connecting the top conical sidewall of the dimple to the land area of the ball at an indistinct junction, with the exception of embodiments wherein the transition surface is defined by a linear function.

In embodiments of the present invention wherein the function defining the transition surface is a linear function, edge angle is determined as follows. Referring to FIG. 16, the edge angle of the transition surface (θ_t) and the edge angle of the conical sidewall (θ_c) are determined. The edge angle of the transition surface (θ_t) is the angle between the conical transition surface 24 and the line T2 that is tangent with the ball surface at the dimple edge. The edge angle of the conical sidewall (θ_c) is the angle between the conical sidewall 12 and the line T2 that is tangent with the ball surface at the dimple edge. The edge angle of the dimple (Φ_EDGE) is then calculated as:Φ_EDGE=θ_t(T_r)+θ_c(1−T_r),where Tr is the transition ratio, which is defined by the equation T_r=1−(D_T/D_D), where D_T is the transition diameter and D_D is the overall dimple diameter.

FIGS. 13-15 illustrate several embodiments of dimples of the present invention which include a top conical sidewall 12, a bottom portion 14, and a transition surface 22 that connects the top conical sidewall 12 to the land area of the ball. The transition surface 22 intersects with the top conical sidewall 12 at a defined point of intersection 18. The top conical sidewall 12 intersects with the bottom portion 14 at a defined point of intersection 16. The dimple diameter (D_D), transition diameter (D_T), and saucer diameter (D_S) are identified. The transition surface 22 is defined by a spherical arc rotated about a central axis. The bottom portion 14 is a spherical cap.

In a particular aspect of the embodiments shown in FIGS. 13-15, the difference between the slope of the transition surface 22 and the slope of the top conical sidewall 12 at the point of intersection 18 is 2° or less. In another particular aspect of the embodiments shown in FIGS. 13-15, the difference between the slope of the top conical sidewall 12 and the slope of the bottom portion 14 at the point of intersection 16 is 2° or less. In the embodiment shown in FIG. 13, the saucer ratio (S_r) is about 0.05, and the transition ratio (T_r) is about 0.08. In the embodiment shown in FIG. 14, the saucer ratio (S_r) is about 0.16, and the transition ratio (T_r) is about 0.17. In the embodiment shown in FIG. 15, the saucer ratio (S_r) is about 0.26, and the transition ratio (T_r) is about 0.08.

FIGS. 16-18 illustrate several embodiments of dimples of the present invention which include a top conical sidewall 12, a bottom portion 14, and a transition surface 24 that connects the top conical sidewall 12 to the land area of the ball. The transition surface intersects with the top conical sidewall 12 at a defined point of intersection 18. The top conical sidewall 12 intersects with the bottom portion 14 at a defined point of intersection 16. The transition surface 24 is defined by a linear function rotated about a central axis. The bottom portion 14 is a spherical cap.

In a particular aspect of the embodiments shown in FIGS. 16-18, the difference between the slope of the transition surface 24 and the slope of the top conical sidewall 12 at the point of intersection 18 is 2° or less. In another particular aspect of the embodiments shown in FIGS. 16-18, the difference between the slope of the top conical sidewall 12 and the slope of the bottom portion 14 at the point of intersection 16 is 2° or less. In another particular aspect of the embodiments shown in FIGS. 16-18, the angular deviation between the transition surface 24 and the top conical sidewall 12 (i.e., the absolute value of θ_c−θ_t) is 2° or 4° or 6° or 8° or 10° or is within a range having a lower limit and an upper limit selected from these values.

In the embodiment shown in FIG. 17, the saucer ratio (S_r) is about 0.05, and the transition ratio (T_r) is about 0.09. The edge angle of the transition surface (θ_t) is about 9.0° and the edge angle of the conical sidewall (θ_c) is about 13.0°. Thus, the angular deviation between the transition surface 24 and the top conical sidewall 12 is about 4.0°, and the edge angle of the dimple (Φ_EDGE) is calculated as:Φ_EDGE=θ_t(T_r)+θ_c(1−T_r), i.e.,Φ_EDGE=9(0.09)+13(1−0.09)=12.64°.

In the embodiment shown in FIG. 18, the saucer ratio (S_r) is about 0.23, and the transition ratio (T_r) is about 0.23. The edge angle of the transition surface (θ_t) is about 11.0° and the edge angle of the conical sidewall (θ_c) is about 13.0°. Thus, the angular deviation between the transition surface 24 and the top conical sidewall 12 is about 2.0°, and the edge angle of the dimple (Φ_EDGE) is calculated as:Φ_EDGE=θ_t(T_r)+θ_c(1−T_r), i.e.,Φ_EDGE=11(0.23)+13(1−0.23)=12.54°.

In another particular aspect of the embodiments disclosed herein, dimples of the present invention additionally include a secondary transition surface that connects the top conical sidewall of the dimple to the bottom portion. The secondary transition surface is defined by a spherical arc rotated about a central axis. The function defining the secondary transition surface may result in an indistinct junction between the top conical sidewall and the bottom portion. Thus, the protruding bottom portion diameter (D_PB) is determined as follows. As shown in FIG. 20, a reference line 220 is drawn such that it includes a first point of tangency with the secondary transition surface 222 on one side of the dimple cross-sectional profile and a second point of tangency with the secondary transition surface 222 on the other side of the dimple cross-sectional profile. The distance between the first and second points of tangency is calculated as the protruding bottom portion diameter (D_PB).

The secondary transition surface has a length (L_2T), which is measured in the dimple cross-sectional profile as the horizontal distance between the point of intersection 16 between the secondary transition surface 222 and the top conical sidewall 12 and the point of intersection 216 between the secondary transition surface 222 and the protruding bottom portion 114. In different embodiments, L_2T may be equal to, less than, or greater than the protruding spherical cap diameter (D_PS). In different embodiments, L_2T may be equal to, less than, or greater than the difference between the overall dimple diameter (D_D) and the diameter of the dimple at the point of intersection between the first transition surface and the top conical sidewall (D_T).

In a further particular aspect of this embodiment, the secondary transition surface is tangent to the top conical sidewall. In another further particular aspect of this embodiment, the secondary transition surface is tangent to the protruding conical sidewall of the protruding bottom portion. In another further particular aspect of this embodiment, the dimple includes a first transition surface defined by a spherical arc rotated about a central axis and connecting the top conical sidewall to the land area, and the first transition surface and secondary transition surface are opposite in concavity. For example, in FIG. 20, the concavity of the arc of the secondary transition surface is concave up in the direction of the phantom surface of the golf ball, and opposite in concavity to the transition surface connecting the top conical sidewall to the land area of the golf ball.

While it is apparent that the illustrative embodiments of the invention disclosed herein fulfill the objectives of the present invention, it is appreciated that numerous modifications and other embodiments may be devised by those skilled in the art. Additionally, feature(s) and/or element(s) from any embodiment may be used singly or in combination with other embodiment(s) and steps or elements from methods in accordance with the present invention can be executed or performed in any suitable order. Therefore, it will be understood that the appended claims are intended to cover all such modifications and embodiments, which would come within the spirit and scope of the present invention.

Claims

1. A golf ball having a generally spherical surface and comprising a plurality of dimples separated by a land area formed on the ball surface, wherein at least a portion of the dimples are conical-protruding bottom dimples consisting of a top conical sidewall and a protruding bottom portion, wherein: a first transition surface connects the top conical sidewall to the land area;a secondary transition surface connects the top conical sidewall to the protruding bottom portion;the protruding bottom portion consists of a protruding conical sidewall and a protruding spherical cap;the conical-protruding bottom dimples have a protrusion bottom portion ratio, defined as the ratio of the protruding bottom portion diameter (DPB) to the dimple diameter (DD), of from about 0.05 to about 0.75; andthe conical-protruding bottom dimples have a protrusion saucer ratio, defined as the ratio of the protruding spherical cap diameter (DPS) to the protruding bottom portion diameter (DPB), of from about 0.05 to about 0.75.

2. The golf ball of claim 1, wherein the secondary transition surface has a length L2T and L2T=DPS.

3. The golf ball of claim 1, wherein the secondary transition surface has a length L2T and L2T<DPS.

4. The golf ball of claim 1, wherein the secondary transition surface has a length L2T and L2T>DPS.

5. The golf ball of claim 1, wherein the secondary transition surface has a length L2T and L2T=DD−DT, where DT is the diameter of the dimple at the point of intersection between the first transition surface and the top conical sidewall.

6. The golf ball of claim 1, wherein the secondary transition surface has a length L2T and L2T<DD−DT, where DT is the diameter of the dimple at the point of intersection between the first transition surface and the top conical sidewall.

7. The golf ball of claim 1, wherein the secondary transition surface has a length L2T and L2T>DD−DT, where DT is the diameter of the dimple at the point of intersection between the first transition surface and the top conical sidewall.

8. The golf ball of claim 1, wherein the secondary transition surface has a length L2T and L2T=DPS=DD−DT, where DT is the diameter of the dimple at the point of intersection between the first transition surface and the top conical sidewall.

9. The golf ball of claim 1, wherein the protruding bottom portion does not extend at any point beyond the phantom surface of the dimple.

10. The golf ball of claim 1, wherein the protruding bottom portion does not extend at any point beyond the chord plane of the dimple.

11. The golf ball of claim 1, wherein the conical-protruding bottom dimple has a protrusion angle θP between the chord plane of the dimple and the protruding conical sidewall of from 10° to 30°.

12. The golf ball of claim 11, wherein the difference between the edge angle θEDGE of the dimple and the protrusion angle θP of the dimple is 1° or less.

13. The golf ball of claim 11, wherein the difference between the edge angle θEDGE of the dimple and the protrusion angle θP of the dimple is greater than 1°.

14. The golf ball of claim 1, wherein the difference between the protrusion bottom portion ratio and the protrusion saucer ratio is 0.05 or less.

15. The golf ball of claim 1, wherein the difference between the protrusion bottom portion ratio and the protrusion saucer ratio is greater than 0.05.

16. The golf ball of claim 1, wherein the first transition surface is defined by a spherical arc rotated about a central axis.

17. The golf ball of claim 16, wherein the secondary transition surface is defined by a spherical arc rotated about a central axis.

18. The golf ball of claim 17, wherein the first transition surface and the secondary transition surface are opposite in concavity.

19. The golf ball of claim 1, wherein the first transition surface is defined by a linear function rotated about a central axis.

20. The golf ball of claim 19, wherein the secondary transition surface is defined by a spherical arc rotated about a central axis.