Multi-piece solid golf ball

Abstract

In a golf ball including a core, an intermediate layer, and a cover, the relationship of the surface hardness between an intermediate layer-encased sphere and the ball satisfies a predetermined relational expression, and with an initial velocity of the ball and a deflection under a predetermined load applied to the ball optimized, and letting a value of (initial velocity of core×weight of core) be Ciw, a value of [(initial velocity of intermediate layer-encased sphere—initial velocity of core)×(weight of intermediate layer-encased sphere−weight of core)] be Miw, and a value of [(initial velocity of ball−initial velocity of intermediate layer-encased sphere)×(weight of ball−weight of intermediate layer-encased sphere)] be CViw, the expression of Ciw+Miw+CViw is optimized, and a volume occupancy ratio VR of the dimples is set within a predetermined range.

1 . A multi-piece solid golf ball comprising a core, an intermediate layer, and a cover, wherein a large number of dimples are formed on an outer surface of the cover, and a relationship between a surface hardness of an intermediate layer-encased sphere and a surface hardness of the ball satisfies the following condition:
   (surface hardness of ball)<(surface hardness of intermediate layer-encased sphere)   [where the surface hardnesses mean Shore C hardnesses], and   when an initial velocity of the ball is 76.5 to 77.724 m/s and a deflection is less than 2.7 mm when the ball is compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf), a value of (initial velocity of core×weight of core) is denoted by Ciw, a value of [(initial velocity of intermediate layer-encased sphere−initial velocity of core)×(weight of intermediate layer-encased sphere−weight of core)] is denoted by Miw, and a value of [(initial velocity of ball−initial velocity of intermediate layer-encased sphere)×(weight of ball−weight of intermediate layer-encased sphere)] is denoted by CViw, the following condition is satisfied:
   2,600≤ Ciw+Miw+CViw≤ 2,715, and
 
   a volume occupancy ratio VR of the dimples is from 0.77 to 0.92%.   
     
     
         2 . The multi-piece solid golf ball according to  claim 1 , wherein a total volume of the dimples is from 314 to 375 mm 3 . 
     
     
         3 . The multi-piece solid golf ball according to  claim 1 , wherein when a ratio CL1/CD1 of a lift coefficient CL1 at a Reynolds number of 218000 and a spin rate of 2800 rpm to a drag coefficient CD1 is denoted by A1, a ratio CL2/CD2 of a lift coefficient CL2 at a Reynolds number of 184000 and a spin rate of 2900 rpm to a drag coefficient CD2 is denoted by A2, and a ratio CL3/CD3 of a lift coefficient CL3 at a Reynolds number of 158000 and a spin rate of 3100 rpm to a drag coefficient CD3 is denoted by A3, the following two conditions are satisfied:
   0.590≤A1≤0.655 and
     ( A 2+ A 3)/2≥0.670.
   
     
     
         4 . The multi-piece solid golf ball according to  claim 1 , wherein the value of (A2+A3)/2 is 0.670 to 0.783. 
     
     
         5 . The multi-piece solid golf ball according to  claim 1 , wherein the value of A2 is 0.635 to 0.750, and the value of A3 is 0.695 to 0.815. 
     
     
         6 . The multi-piece solid golf ball according to  claim 1 , wherein a relationship between a surface hardness of the core and the surface hardness of the intermediate layer-encased sphere satisfies the following condition:
   (surface hardness of intermediate layer-encased sphere)≥(surface hardness of core)
   (where the surface hardnesses mean Shore C hardnesses).   
     
     
         7 . The multi-piece solid golf ball according to  claim 1 , wherein when the initial velocity of the core is denoted by Vc (m/s), and a deflection is denoted by C (mm) when the core is compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf), the following condition is satisfied:
   20≤ Vc/C≤ 30.
   
     
     
         8 . The multi-piece solid golf ball according to  claim 1 , wherein when each sphere of the core, the intermediate layer-encased sphere, and the ball is compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) and the deflections (mm) are denoted by C (mm), M (mm), and B (mm) respectively, the following two conditions are satisfied:
   0.30≤ C−B≤ 0.90
     0.30≤ C−M≤ 0.65.
   
     
     
         9 . The multi-piece solid golf ball according to  claim 1 , wherein when the core is compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) and the deflection (mm) is denoted by C (mm), the following condition is satisfied:
   700≤ Ciw/C≤ 1000.
   
     
     
         10 . The multi-piece solid golf ball according to  claim 1 , wherein the core has a hardness profile in which, letting the Shore C hardness at a core center be Cc, the Shore C hardness at a midpoint M between the core center and a core surface be C m , the Shore C hardnesses at positions 2 mm, 4 mm, and 6 mm inward from the midpoint M be Cm−2, Cm−4, and Cm−6 respectively, the Shore C hardnesses at positions 2 mm, 4 mm, and 6 mm outward from the midpoint M be Cm+2, Cm+4, and Cm+6 respectively, and the Shore C hardness at the core surface be Cs, and defining surface areas A to F as follows:
   surface area A:½×2×(Cm−4−Cm−6)
 
   surface area B:½×2×(Cm−2−Cm−4)
 
   surface area C:½×2×(Cm−Cm−2)
 
   surface area D:½×2×(Cm+2−Cm)
 
   surface area E:½×2×(Cm+4−Cm+2)
 
   surface area F:½×2×(Cm+6−Cm+4)
 
 the following condition is satisfied:
   {(surface area  D +surface area  E )−(surface area  A +surface area  B )}≥4.0.
 
 
 
     
     
         11 . The multi-piece solid golf ball according to  claim 10 , wherein the core has a hardness profile in which the following condition is satisfied:
   ( Cs−Cc )≥22.
   
     
     
         12 . The multi-piece solid golf ball according to  claim 10 , wherein the core has a hardness profile in which the following condition is satisfied:
   ( Cs−Cc )/( Cm−Cc )≥4.0.
   
     
     
         13 . The multi-piece solid golf ball according to  claim 10 , wherein the core has a hardness profile in which the following condition is satisfied:
   surface area E>surface area D>surface area C.