Golf ball

• US 7,018,308 B2
• Filed: 03/21/2003
• Issued: 03/28/2006
• Est. Priority Date: 03/29/2002
• Status: Active Grant

• Current Assignee: Bridgestone Sports Co Limited (Bridgestone Corporation)
• Original Assignee: Bridgestone Sports Co Limited (Bridgestone Corporation)
• Inventors: Kasashima, Atsuki
• Primary Examiner(s): Gorden, Raeann
• Application Number:
  US10/392,968
• Publication Number:
  US 20030190968A1
• Time in Patent Office: 1,103 Days
• Field of Search: 473378-385
• US Class Current: 473/383
• CPC Class Codes: A63B 37/0004 Surface depressions or protrusions
• CPC Class Codes: A63B 37/0012 Dimple profile, i.e. cross-sectional view
• CPC Class Codes: A63B 37/0016 Specified individual dimple volume
• CPC Class Codes: A63B 37/0019 Specified dimple depth
• CPC Class Codes: A63B 37/002 Specified dimple diameter
• CPC Class Codes: A63B 37/0031 Hardness
• CPC Class Codes: A63B 37/0033 Thickness
• CPC Class Codes: A63B 37/0039 characterised by the material
• CPC Class Codes: A63B 37/0043 Hardness
• CPC Class Codes: A63B 37/0045 Thickness
• CPC Class Codes: A63B 37/0075 Three piece balls, i.e. cover, intermediate layer and core
• CPC Class Codes: A63B 37/0084 Initial velocity
• CPC Class Codes: A63B 37/0089 Coefficient of drag
• CPC Class Codes: A63B 37/009 Coefficient of lift
• CPC Class Codes: A63B 37/0096 Spin rate

Abstract

A golf ball includes a multiplicity of dimples on its outer surface. At least one or more of the multiplicity of dimples are each configured to have a convex bottom portion formed by a circular-arc defined by a center positioned inside the ball and a curvature radius “r” mm smaller than a radius “R” mm of the ball but larger than a value (R−0.5) mm. The golf ball specified such that the shapes of the dimples are optimized as described above exhibits high flight characteristics.

Claims

1. A golf ball comprising a multiplicity of dimples on its outer surface, wherein at least one or more of said multiplicity of dimples are each configured to have a convex bottom portion formed by a circular-arc defined by a curvature radius “

r”

mm whose center is positioned inside said ball and the radius “

r”

mm of the convex bottom of the dimple and a radius “

R”

mm of said ball satisfy the following relationship;

R>

r>

R−

0.5.

2. A golf ball according to claim 1, wherein said dimple having said convex bottom portion is formed into a circular shape in a plan view.

3. A golf ball according to claim 1, wherein a ration CL/CD of a lift coefficient CL to a drag coefficient CD of said ball during flight thereof is in a range of 0.676 to 0.796 under a condition with a Reynolds number of 200,000 and a spin rate of 2,700 rpm, in a range of 0.813 to 0.933 under a condition with a Reynolds number of 120,000 and a spin rate of 2,400 rpm, and in a range of 0.856 to 0.976 under a condition with a Reynolds number of 80,000 and a spin rate of 2,000 rpm.

4. A golf ball according to claim 1, wherein the circular-arc defined by the curvature radius “

r”

is substantially concentric with the circle defined by the radius “

R”

.

5. A golf ball according to claim 1, wherein the radius “

r”

of the convex bottom of the dimple and the radius “

R”

of the ball satisfy the following relationship;

R−

0.1>

r>

R−

0.4.

6. A golf ball according to claim 1, wherein the depth “

h”

of the dimple is equal to “

R−

r”

.

7. A golf ball according to claim 1, wherein the ratio of the dimples having convex bottom portions to the total of the dimples is in a range of 50% or more.

8. A golf ball according to claim 1, wherein the ratio d/D of a diameter “

d”

of the dimple bottom portion to a diameter D of the dimple is in a range of ⅕

to ⅘

.

9. A golf ball comprising a multiplicity of dimples on its outer surface, wherein at least one or more of said multiplicity of dimples are each configured to have a convex bottom portion formed by a circular-arc defined by a center positioned inside said ball and a curvature radius “

r”

mm smaller than a radius “

R”

mm of said ball but larger than a value (R−

0.5) mm, wherein said dimple having said convex bottom portion is formed into a non-circular shape in a plan view.

10. A golf ball according to claim 9, wherein a ratio CL/CD of a lift coefficient CL to a drag coefficient CD of said ball during flight thereof is in a range of 0.676 to 0.796 under a condition with a Reynolds number of 200,000 and a spin rate of 2,700 rpm, in a range of 0.813 to 0.933 under a condition with a Reynolds number of 120,000 and a spin rate of 2,400 rpm, and in a range of 0.856 to 0.976 under a condition with a Reynolds number of 80,000 and a spin rate of 2,000 rpm.

11. A golf ball according to claim 9, wherein dimple shapes of said multiplicity of dimples in a plan view includes at least one of a triangular shape, a quadrilateral shape, a hexagonal shape, an elliptic shape, an oval shape, a petal shape, a heart shape, a star shape, a dewdrop shape, and a combination thereof.

12. A golf ball according to claim 11, wherein the bottom portion of the dimple is formed into a non-circular shape in a plan view.