Golf ball

Abstract

A golf ball has a core, an inner cover, an outer cover, and dimples, and satisfies the following mathematical formulas. Vw =54+0.01(2.5 A−B+5 Cv)≥58.0 0.08 X 2 −4.25 X +345−20≤D≤0.08 X 2 −4.25 X +345+20 A: a compression of the golf ball B: a hardness difference between a surface and a center of the core Cv: ( Hi×Ti+Ho×To )/( Ti+To ) Cs: ( Hi×Ti+ 2 Ho×To )/( Ti+ 2 To ) D: a total volume of the dimples X:Sw/Vw Hi: a hardness of the inner cover Ho: a hardness of the outer cover Ti: a thickness of the inner cover To: a thickness of the outer cover Sw: 3000+10(A−B− 1.5 Cs)

What is claimed is: 
     
         1 . A golf ball comprising a core, an inner cover positioned outside the core, and an outer cover positioned outside the inner cover, wherein
 the golf ball has a plurality of dimples on a surface thereof, and   the golf ball satisfies the following mathematical formulas (I) and (II),
     Vw= 54+0.01(2.5 A−B+ 5 Cv )≥58.0   (I),
 
   0.08 X   2 −4.25 X+ 345−20≤ D≤ 0.08 X   2 −4.25 X+ 345+20   (II),
 
   A: a compression (Atti) of the golf ball,   B: a hardness difference (Shore C) between a surface and a center of the core,
   Cv: (Hi×Ti+Ho×To)/(Ti+To),
 
   Cs: (Hi×Ti+2Ho×To)/(Ti+2To),
 
   D: a dimple total volume (mm 3 ),
   X: Sw/Vw, 
   Hi: a hardness (Shore D) of the inner cover,   Ho: a hardness (Shore D) of the outer cover,   Ti: a thickness (mm) of the inner cover,   To: a thickness (mm) of the outer cover,
   Sw: 3000+10(A−B−1.5Cs).
 
   
     
     
         2 . The golf ball according to  claim 1 , wherein the golf ball further satisfies the following mathematical formula (III),
     Sa= 4500+10( A− 0.5 B− 2 Cs )≥4000   (III).
   
     
     
         3 . The golf ball according to  claim 1 , wherein a lift force coefficient CL of the golf ball satisfies the following mathematical formula (IV),
   CLL≤CL≤CLU
     CLU: Sw/60×(−9.5×10 −6 ×D+6.1×10 −3 )+(1.871×10 −4 ×D−3.5×10 −3 ),
     CLL: Sw/60×(−3.8×10 −6 ×D+3.0×10 −3 )+(4.52×10 −5 ×D+8.32×10 −2 ).   (IV)
   
     
     
         4 . The golf ball according to  claim 1 , wherein a hardness (shore C) of the center of the core is not less than 35 and not greater than 70. 
     
     
         5 . The golf ball according to  claim 1 , wherein a hardness (shore C) of the surface of the core is not less than 55 and not greater than 95. 
     
     
         6 . The golf ball according to  claim 1 , wherein the hardness difference B is not less than 0 and not greater than 40. 
     
     
         7 . The golf ball according to  claim 1 , wherein an amount of compressive deformation Df of the core is not less than 3.0 mm and not greater than 4.5 mm. 
     
     
         8 . The golf ball according to  claim 1 , wherein the thickness Ti of the inner cover is not less than 0.50 mm and not greater than 1.50 mm. 
     
     
         9 . The golf ball according to  claim 1 , wherein the hardness Hi of the inner cover is not less than 25 and not greater than 75. 
     
     
         10 . The golf ball according to  claim 1 , wherein the thickness To of the outer cover is not less than 0.30 mm and not greater than 2.30 mm. 
     
     
         11 . The golf ball according to  claim 1 , wherein the hardness Ho of the outer cover is not less than 20 and not greater than 75. 
     
     
         12 . The golf ball according to  claim 1 , wherein the index Cv is not less than 25 and not greater than 75. 
     
     
         13 . The golf ball according to  claim 1 , wherein the index Cs is not less than 25 and not greater than 75. 
     
     
         14 . The golf ball according to  claim 1 , wherein the compression A is not less than 20 and not greater than 120. 
     
     
         15 . The golf ball according to  claim 1 , wherein a ratio of a sum of areas of all the dimples relative to a surface area of a phantom sphere of the golf ball is not less than 78%. 
     
     
         16 . The golf ball according to  claim 1 , wherein a total number of the dimples is not less than 250 and not greater than 450. 
     
     
         17 . The golf ball according to  claim 1 , wherein a total volume D of the dimples is not less than 200 mm 3  and not greater than 500 mm 3 .