Abstract:
A dimple pattern for a golf ball with multiple sets of dimples is disclosed herein. Each of the multiple sets of dimples has a different entry radius. A preferred set of dimples is eighteen different dimples. The dimples may cover as much as eighty-seven percent of the surface of the golf ball. The unique dimple pattern allows a golf ball to have shallow dimples with steeper entry angles. In a preferred embodiment, the golf ball has 382 dimples with eleven different diameters and eighteen different entry radii.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. patent application Ser. No. 09/843,338, filed on Apr. 25, 2001, now U.S. Pat. No. 6,537,159 which is a continuation-in-part application of U.S. patent application Ser. No. 09/398,919 filed on Sep. 16, 1999, now U.S. Pat. No. 6,224,499. 
    
    
     FEDERAL RESEARCH STATEMENT 
     [Not Applicable] 
     BACKGROUND OF INVENTION 
     1. Field of the Invention 
     The present invention relates to a golf ball. More specifically, the present invention relates to a dimple pattern for a golf ball in which the dimple pattern has different sizes of dimples. 
     2. Description of the Related Art 
     Golfers realized perhaps as early as the 1800&#39;s that golf balls with indented surfaces flew better than those with smooth surfaces. Hand-hammered gutta-percha golf balls could be purchased at least by the 1860&#39;s, and golf balls with brambles (bumps rather than dents) were in style from the late 1800&#39;s to 1908. In 1908, an Englishman, William Taylor, received a patent for a golf ball with indentations (dimples) that flew better and more accurately than golf balls with brambles. A. G. Spalding &amp; Bros., purchased the U.S. rights to the patent and introduced the GLORY ball featuring the TAYLOR dimples. Until the 1970s, the GLORY ball, and most other golf balls with dimples had 336 dimples of the same size using the same pattern, the ATTI pattern. The ATTI pattern was an octahedron pattern, split into eight concentric straight line rows, which was named after the main producer of molds for golf balls. 
     The only innovation related to the surface of a golf ball during this sixty year period came from Albert Penfold who invented a mesh-pattern golf ball for Dunlop. This pattern was invented in 1912 and was accepted until the 1930&#39;s. 
     In the 1970&#39;s, dimple pattern innovations appeared from the major golf ball manufacturers. In 1973, Titleist introduced an icosahedron pattern which divides the golf ball into twenty triangular regions. An icosahedron pattern was disclosed in British Patent Number 377,354 to John Vernon Pugh, however, this pattern had dimples lying on the equator of the golf ball which is typically the parting line of the mold for the golf ball. Nevertheless, the icosahedron pattern has become the dominant pattern on golf balls today. 
     In the late 1970&#39;s and the 1980&#39;s the mathematicians of the major golf ball manufacturers focused their intention on increasing the dimpled surface area (the area covered by dimples) of a golf ball. The dimpled surface for the ATTI pattern golf balls was approximately 50%. In the 1970&#39;s, the dimpled surface area increased to greater than 60% of the surface of a golf ball. Further breakthroughs increased the dimpled surface area to over 70%. U.S. Pat. No. 4,949,976 to William Gobush discloses a golf ball with 78% dimple coverage with up to 422 dimples. The 1990&#39;s have seen the dimple surface area break into the 80% coverage. 
     The number of different dimples on a golf ball surface has also increased with the surface area coverage. The ATTI pattern disclosed a dimple pattern with only one size of dimple. The number of different types of dimples increased, with three different types of dimples becoming the preferred number of different types of dimples. U.S. Pat. No. 4,813,677 to Oka et al., discloses a dimple pattern with four different types of dimples on the surface where the non-dimpled surface cannot contain an additional dimple. United Kingdom patent application number 2,157,959, to Steven Aoyama, discloses dimples with five different diameters. Further, William Gobush invented a cuboctahedron pattern that has dimples with eleven different diameters. See 500  Year of Golf Balls , Antique Trade Books, page 189. However, inventing dimple patterns with multiple dimples for a golf ball only has value if such a golf ball is commercialized and available for the typical golfer to play. 
     Additionally, dimple patterns have been based on the sectional shapes, such as octahedron, dodecahedron and icosahedron patterns. U.S. Pat. No. 5,201,522 discloses a golf ball dimple pattern having pentagonal formations with an equal number of dimples thereon. U.S. Pat. No. 4,880,241 discloses a golf ball dimple pattern having a modified icosahedron pattern wherein small triangular sections lie along the equator to provide a dimple-free equator. 
     Although there are hundreds of published patents related to golf ball dimple patterns, there still remains a need to improve upon current dimple patterns. This need is driven by new materials used to manufacture golf balls, and the ever increasing innovations in golf clubs. 
     SUMMARY OF INVENTION 
     The present invention provides a novel dimple pattern that reduces high speed drag on a golf ball while increasing its low speed lift thereby providing a golf ball that travels greater distances. The present invention is able to accomplish this by providing multiples sets of dimples arranged in a pattern that covers as much as eighty-six percent of the surface of the golf ball. 
     One aspect of the present invention is a dimple pattern on a golf ball in which the dimple pattern has at least eighteen different sets of dimples. Each of the eighteen different sets of dimples has a different entry radius than any other set of dimples. The dimples cover at least 87% of the surface of the golf ball. 
     Another aspect of the present invention is a golf ball having at least 382 dimples. The 382 dimples are partitioned into at least eleven different sets of dimples. Each of the eleven different sets of dimples has a different diameter than any other set of dimples. The 382 dimples cover at least 87% of the surface of the golf ball. 
     Yet another aspect of the present invention is a golf ball having a core and cover. The core has a diameter of 1.50 inches to 1.56 inches, and is composed of a polybutadiene material. The cover encompasses the core and has a thickness of 0.05 inch to 0.10 inch. The cover is preferably composed of an ionomer blend of material. The cover has a surface which has 382 dimples. The 382 dimples are partitioned into at least eleven different sets of dimples. Each of the eleven different sets of dimples have a different diameter than any other set of dimples. The 382 dimples cover at least 87% of the surface of the cover. 
     Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a cross-sectional view of a two-piece golf ball of the present invention. 
     FIG. 1A is a cross-sectional view of a three-piece golf ball of the present invention. 
     FIG. 2 is an equatorial view, of a preferred embodiment of a golf ball of the present invention. 
     FIG. 3 is an equatorial view of a preferred embodiment of a golf ball of the present invention. 
     FIG. 4 is a polar view of the golf ball of FIG.  1 . 
     FIG. 5 is an isolated partial cross-sectional view of a dimple to illustrate the definition of the entry radius. 
     FIG. 6 is an enlarged half cross-sectional view of a typical dimple of a fourth set of dimples of the golf ball of the present invention. 
     FIG. 7 is an enlarged half cross-sectional view of a dimple of a eleventh set of dimples of the golf ball of the present invention. 
     FIG. 8 is an enlarged half cross-sectional view of a dimple of a second set of dimples of the golf ball of the present invention. 
     FIG. 9 is an enlarged half cross-sectional view of a dimple of a first set of dimples of the golf ball of the present invention. 
     FIG. 10 is an enlarged half cross-sectional view of a typical dimple of a sixth set of dimples of the golf ball of the present invention. 
     FIG. 11 is a graph of the lift coefficient for a Reynolds number of 70,000 at 2000 rotations per minute (x-axis) versus the drag coefficient for a Reynolds number of 180,000 at 3000 rotations per minute (y-axis). 
    
    
     DETAILED DESCRIPTION 
     As shown in FIG. 1, a golf ball is generally designated  20 . The golf ball  20  is preferably a two-piece with a solid core and a cover such as disclosed in co-pending U.S. patent application Ser. No. 09/768,846, for a Golf Ball, filed on Jan. 23, 2001, and hereby incorporated by reference. Alternatively, the golf ball  20  is a three-piece golf ball as shown in FIG.  1 A. Such a three-piece golf ball  20  is disclosed in U.S. Pat. No. 6,117,024, which is hereby incorporated by reference. However, those skilled in the pertinent art will recognize that the aerodynamic pattern of the present invention may by utilized on other two-piece or three-piece golf balls, one-piece golf balls, or multiple-layer golf balls without departing from the scope and spirit of the present invention. 
     A cover  21  or  21   a  of the golf ball  20  may be any suitable material. A preferred cover  21  is composed of a thermoplastic material such as an ionomer material or a thermosetting material such as a polyurethane. However, those skilled in the pertinent art will recognize that other cover materials may be utilized without departing from the scope and spirit of the present invention. If the golf ball is a three-piece golf ball  20 , as shown in FIG. 1A, the intermediate layer  21   b  is preferably composed of an ionomer material while the cover  21   a  is composed of a softer material. The golf ball  20  may have a finish of a basecoat and/or top coat with a logo indicia. A core  23  of the golf ball is preferably composed of a polybutadiene material. 
     As shown in FIGS. 2-4, the golf ball  20  has a surface  22 . The golf ball  20  also has an equator  24  dividing the golf ball  20  into a first hemisphere  26  and a second hemisphere  28 . A first pole  30  is located ninety degrees along a longitudinal arc from the equator  24  in the first hemisphere  26 . A second pole  32  is located ninety degrees along a longitudinal arc from the equator  24  in the second hemisphere  28 . 
     On the surface  22 , in both hemispheres  26  and  28 , are a plurality of dimples partitioned into multiple different sets of dimples. In a preferred embodiment, the number of dimples is 382, and there are eleven different sets of dimples, as partitioned by diameter of the dimple. Sets of dimples also vary by entry radius, entry angle and chord depth. In an alternative embodiment, there are eighteen different sets of dimples by entry radius. 
     In a preferred embodiment, there is a first plurality of dimples  40 , a second plurality of dimples  42 , a third plurality of dimples  44 , a fourth plurality of dimples  46  (including  46   a - 46   f ), a fifth plurality of dimples  48 , a sixth plurality of dimples  50  (including  50   a ), a seventh plurality of dimples  52 , an eighth plurality of dimples  54 , a ninth plurality of dimples  56 , a tenth plurality of dimples  58 , and an eleventh plurality of dimples  60 . 
     In the preferred embodiment, each of the first plurality of dimples  40  has the largest diameter dimple, and each of the eleventh plurality of dimples  60  has the smallest diameter dimples. The diameter of a dimple is measured from a surface inflection point  100  across the center of the dimple to an opposite surface inflection point  100 . The surface inflection points  100  are where the land surface  22  ends and where the dimples begin. Each of the second plurality of dimples  42  has a smaller diameter than the diameter of each of the first plurality of dimples  40 . Each of the third plurality of dimples  44  has a smaller diameter than the diameter of each of the second plurality of dimples  42 . Each of the fourth plurality of dimples  46  (including  46   a - 46   f ) has a smaller diameter than the diameter of each of the third plurality of dimples  44 . Each of the fifth plurality of dimples  48  has a diameter that is equal to or smaller than the diameter of each of the fourth plurality of dimples  46 . Each of the sixth plurality of dimples  50  (including  50   a ) has a smaller diameter than the diameter of each of the fifth plurality of dimples  48 . Each of the seventh plurality of dimples  52  has a smaller diameter than the diameter of each of the sixth plurality of dimples  50 . Each of the eighth plurality of dimples  54  has a smaller diameter than the diameter of each of the seventh plurality of dimples  52 . Each of the ninth plurality of dimples  56  has a smaller diameter than the diameter of each of the eighth plurality of dimples  54 . Each of the tenth plurality of dimples  58  has a smaller diameter than the diameter of each of the ninth plurality of dimples  56 . Each of the eleventh plurality of dimples  60  has a smaller diameter than the diameter of each of the tenth plurality of dimples  58 . 
     In a preferred embodiment, the fourth plurality of dimples  46  (including  46   a - 46   f ) are the most numerous. The second plurality of dimples  42 , the third plurality of dimples  44 , and the fifth plurality of dimples  48  are equally the second most numerous. The eleventh plurality of dimples  60  is the least. 
     Table One provides a description of the preferred embodiment. Table One includes the dimple diameter (in inches from inflection point to inflection point), chord depth (in inches measured from the inflection point to the bottom of the dimple at the center), entry angle for each dimple, entry radius for each dimple (in inches) and number of dimples. 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE ONE 
               
               
                   
               
               
                 Dimple 
                 # of 
                 Dimple 
                 Chord 
                 Entry 
                 Entry 
               
               
                 Reference 
                 Dimples 
                 Diameter 
                 Depth 
                 Angle 
                 Radius 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 40 
                 10 
                 0.1838 
                 0.0056 
                 15.01 
                 0.0385 
               
               
                 42 
                 60 
                 0.1678 
                 0.0054 
                 13.37 
                 0.0351 
               
               
                 44 
                 60 
                 0.1668 
                 0.0056 
                 14.09 
                 0.0338 
               
               
                 46 
                 20 
                 0.1648 
                 0.0054 
                 14.85 
                 0.0332 
               
               
                  46a 
                 10 
                 0.1648 
                 0.0056 
                 15.33 
                 0.0375 
               
               
                  46b 
                 10 
                 0.1648 
                 0.0054 
                 14.56 
                 0.0365 
               
               
                  46c 
                 20 
                 0.1648 
                 0.0056 
                 14.71 
                 0.0343 
               
               
                  46d 
                 20 
                 0.1648 
                 0.0057 
                 14.44 
                 0.0340 
               
               
                  46e 
                 10 
                 0.1648 
                 0.0054 
                 14.77 
                 0.0321 
               
               
                  46f 
                 10 
                 0.1648 
                 0.0056 
                 14.35 
                 0.0320 
               
               
                 48 
                 60 
                 0.159 
                 0.0059 
                 14.85 
                 0.0314 
               
               
                 50 
                 10 
                 0.1586 
                 0.0054 
                 15.27 
                 0.0258 
               
               
                  50a 
                 10 
                 0.1586 
                 0.0052 
                 14.69 
                 0.0376 
               
               
                 52 
                 20 
                 0.156 
                 0.0055 
                 14.73 
                 0.0428 
               
               
                 54 
                 20 
                 0.1462 
                 0.0055 
                 13.80 
                 0.0364 
               
               
                 56 
                 10 
                 0.1422 
                 0.0054 
                 14.12 
                 0.0293 
               
               
                 58 
                 20 
                 0.1224 
                 0.0054 
                 15.14 
                 0.0295 
               
               
                 60 
                 2 
                 0.1008 
                 0.0057 
                 20.35 
                 0.0270 
               
               
                   
               
             
          
         
       
     
     The two dimples of the eleventh set of dimples  60  are each disposed on respective poles  30  and  32 . Each of the ninth set of dimples  56  is adjacent one of the eleventh set of dimples  60 . The five dimples of the ninth set of dimples  56  that are disposed within the first hemisphere  26  are each an equal distance from the equator  24  and the first pole  30 . The five dimples of the ninth set of dimples  56  that are disposed within the second hemisphere  28  are each an equal distance from the equator  24  and the second pole  32 . These polar dimples  60  and  56  account for approximately 2% of the surface area of the golf ball  20 . 
     Unlike the use of the term entry radius or edge radius in the prior art, the edge radius as defined herein is a value utilized in conjunction with the entry angle to delimit the concave and convex segments of the dimple contour. The first and second derivatives of the two B é zier curves are forced to be equal at this point defined by the edge radius and the entry angle, as shown in FIG. 5A. A more detailed description of the contour of the dimples is set forth in U.S. Pat. No. 6,331,150, filed on Sep. 16, 1999, entitled Golf Ball Dimples With Curvature Continuity, which is hereby incorporated by reference in its entirety. 
     FIGS. 6-10 illustrate the half cross-sectional views of dimples for some of the different sets of dimples. A half cross-sectional view of a typical dimple of the fourth set of dimples  46   c  is shown in FIG.  6 . The radius R d46c  of the dimple  46   c  is approximately 0.0824 inch, the chord depth CD-CD is approximately 0.0056 inch, the entry angle EA 46c  is approximately 14.7068 degrees, and the entry radius ER 46c  is approximately 0.0343 inch. 
     A half cross-sectional view of a dimple of the eleventh set of dimples  60  is shown in FIG.  7 . The dimple radius R d60  of the dimple  60  is approximately 0.0504 inch, the entry angle EA 60  is approximately 20.3487 degrees, and the entry radius ER 60  is approximately 0.027 inch. The entry angle for each of the two dimples  60  of the eleventh set of dimples is the largest entry angle for a dimple in the preferred embodiment. 
     A half cross-sectional view of a dimple of the second set of dimples  42  is shown in FIG.  8 . The dimple radius R d42  of the dimple  42  is approximately 0.0839 inch, the entry angle EA 42  is approximately 13.3718 degrees, and the entry radius ER 42  is approximately 0.0351 inch. The entry angle for each of the sixty dimples  42  of the second set of dimples is the smallest entry angle for a dimple in the preferred embodiment. 
     A half cross-sectional view of a dimple of the seventh set of dimples  52  is shown in FIG.  9 . The dimple radius R 52  of the dimple  52  is approximately 0.0780 inch, the entry angle EA 52  is approximately 14.7334 degrees, and the entry radius ER 52  is approximately 0.0428 inch. The entry radius for each of the twenty dimples  52  of the seventh set of dimples is the largest entry radius for a dimple in the preferred embodiment. The ten dimples of the seventh set of dimples  52  that are disposed within the first hemisphere  26  are each an equal distance from the equator  24  and the first pole  30 . The ten dimples of the seventh set of dimples  52  that are disposed within the second hemisphere  28  are each an equal distance from the equator  24  and the second pole  32 . 
     A half cross-sectional view of a dimple of the sixth set of dimples  50  is shown in FIG.  10 . The dimple radius R d50  of the dimple  50  is approximately 0.0793 inch, the entry angle EA 50  is approximately 15.2711 degrees, and the entry radius ER 50  is approximately 0.0258 inch. The entry radius for each of the ten dimples  50  of the seventh set of dimples is the smallest entry radius for a dimple in the preferred embodiment. 
     Alternative embodiments of the dimple pattern of the present invention may vary in the number of dimples, diameters, depths, entry angle and/or entry radius. Most common alternatives will not have any dimples at the poles  30  and  32 . Other common alternatives will have the same number of dimples, but with less variation in the diameters. 
     The force acting on a golf ball in flight is calculated by the following trajectory equation: 
     
       
           F=F   L   +F   D   +G   ( A ) 
       
     
     wherein F is the force acting on the golf ball; F L  is the lift; F D  is the drag; and G is gravity. The lift and the drag in equation A are calculated by the following equations: 
       F   L =0.5 C   L   Aρv   2   ( B ) 
     
       
           F   D =0.5 C   D   Aρv   2   ( C ) 
       
     
     wherein C L  is the lift coefficient; C D  is the drag coefficient; A is the maximum cross-sectional area of the golf ball; v is the density of the air; and v is the golf ball airspeed. 
     The drag coefficient, C D,  and the lift coefficient, C L,  may be calculated using the following equations: 
     
       
         C D=2   F   D/   Aρv   2   ( D ) 
       
     
     
       
         C L=2   F   L/   Aρv   2   ( E ) 
       
     
     The Reynolds number R is a dimensionless parameter that quantifies the ratio of inertial to viscous forces acting on an object moving in a fluid. Turbulent flow for a dimpled golf ball occurs when R is greater than 40000. If R is less than 40000, the flow may be laminar. The turbulent flow of air about a dimpled golf ball in flight allows it to travel farther than a smooth golf ball. 
     The Reynolds number R is calculated from the following equation: 
     
       
           R=vDρ/μ   ( F ) 
       
     
     wherein v is the average velocity of the golf ball; D is the diameter of the golf ball (usually 1.68 inches); ρ is the density of air (0.00238 slugs/ft 3  at standard atmospheric conditions); and μ is the absolute viscosity of air (3.74×10 −7  lb*sec/ft 2  at standard atmospheric conditions). A Reynolds number, R, of 180,000 for a golf ball having a USGA approved diameter of 1.68 inches, at standard atmospheric conditions, approximately corresponds to a golf ball hit from the tee at 200 ft/s or 136 mph, which is the point in time during the flight of a golf ball when the golf ball attains its highest speed. A Reynolds number, R, of 70,000 for a golf ball having a USGA approved diameter of 1.68 inches, at standard atmospheric conditions, approximately corresponds to a golf ball at its apex in its flight, 78 ft/s or 53 mph, which is the point in time during the flight of the golf ball when the golf ball travels at its slowest speed. Gravity will increase the speed of a golf ball after its reaches its apex. 
     FIG. 11 is a graph of the lift coefficient for a Reynolds number of 70,000 at 2000 rotations per minute versus the drag coefficient for a Reynolds number of 180,000 at 3000 rotations per minute for a golf ball  20  with the dimple pattern of the present invention thereon as compared to the Titlelist HP DISTANCE  202 , the Titlelist HP ECLIPSE  204 , the SRI Maxfli HI-BRD (from Japan)  206 , the Wilson CYBERCORE PRO DISTANCE  208 , the Titleist PRO V1  210 , the Bridgestone TOUR STAGE MC392 (from Japan)  212 , the Precept MC LADY  214 , the Nike TOUR ACCURACY  216 , and the Titlelist DT DISTANCE  218 . 
     The golf balls  20  with the dimple pattern of the present invention were constructed as set forth in co-pending U.S. patent application Ser. No. 09/768,846, as previously referenced. The aerodynamics of the dimple pattern of the present invention provides a greater lift with a reduced drag thereby translating into a golf ball  20  that travels a greater distance than golf balls of similar constructions. 
     As compared to other golf balls, the golf ball  20  of the present invention is the only one that combines a lower drag coefficient at high speeds, and a greater lift coefficient at low speeds. Specifically, as shown in FIG. 11, none of the other golf balls have a lift coefficient, C L,  greater than 0.19 at a Reynolds number of 70,000, and a drag coefficient C D  less than 0.232 at a Reynolds number of 180,000. For example, while the Nike TOUR ACCURACY  216  has a C L  greater than 0.19 at a Reynolds number of 70,000, its C D  is greater than 0.232 at a Reynolds number of 180,000. Also, while the Titleist DT DISTANCE  218  has a drag coefficient C D  less than 0.232 at a Reynolds number of 180,000, its C L  is less than 0.19 at a Reynolds number of 70,000. Further, the golf ball  20  of the present invention is the only golf ball that has a lift coefficient, C L,  greater than 0.20 at a Reynolds number of 70,000, and a drag coefficient C D  less than 0.235 at a Reynolds number of 180,000. Yet further, the golf ball  20  of the present invention is the only golf ball that has a lift coefficient, C L,  greater than 0.19 at a Reynolds number of 70,000, and a drag coefficient C D  less than 0.229 at a Reynolds number of 180,000. More specifically, the golf ball  20  of the present invention is the only golf ball that has a lift coefficient, C L,  greater than 0.21 at a Reynolds number of 70,000, and a drag coefficient C D  less than 0.230 at a Reynolds number of 180,000. Even more specifically, the golf ball  20  of the present invention is the only golf ball that has a lift coefficient, C L,  greater than 0.22 at a Reynolds number of 70,000, and a drag coefficient C D  less than 0.230 at a Reynolds number of 180,000. 
     In this regard, the Rules of Golf, approved by the United States Golf Association (“USGA”) and The Royal and Ancient Golf Club of Saint Andrews, limits the initial velocity of a golf ball to 250 feet (76.2 m) per second (a two percent maximum tolerance allows for an initial velocity of 255 per second) and the overall distance to 280 yards (256 m) plus a six percent tolerance for a total distance of 296.8 yards (the six percent tolerance may be lowered to four percent). A complete description of the Rules of Golf are available on the USGA web page at www.usga.org. Thus, the initial velocity and overall distance of a golf ball must not exceed these limits in order to conform to the Rules of Golf. Therefore, the golf ball  20  has a dimple pattern that enables the golf ball  20  to meet, yet not exceed, these limits. 
     From the foregoing it is believed that those skilled in the pertinent art will recognize the meritorious advancement of this invention and will readily understand that while the present invention has been described in association with a preferred embodiment thereof, and other embodiments illustrated in the accompanying drawings, numerous changes, modifications and substitutions of equivalents may be made therein without departing from the spirit and scope of this invention which is intended to be unlimited by the foregoing except as may appear in the following appended claims. Therefore, the embodiments of the invention in which an exclusive property or privilege is claimed are defined in the following appended claims.